SEMICONDUCTOR DEVICE WITH POROUS LAYER AND METHOD FOR FABRICATING THE SAME

TECHNICAL FIELD

The present disclosure relates to a semiconductor device and a method for fabricating the semiconductor device, and more particularly, to a semiconductor device with a porous layer and a method for fabricating the semiconductor device with the porous layer.

DISCUSSION OF THE BACKGROUND

Semiconductor devices are used in a variety of electronic applications, such as personal computers, cellular telephones, digital cameras, and other electronic equipment. The dimensions of semiconductor devices are continuously being scaled down to meet the increasing demand of computing ability. However, a variety of issues arise during the scaling-down process, and such issues are continuously increasing. Therefore, challenges remain in achieving improved quality, yield, performance, and reliability and reduced complexity.

This Discussion of the Background section is provided for background information only. The statements in this Discussion of the Background are not an admission that the subject matter disclosed in this section constitutes prior art to the present disclosure, and no part of this Discussion of the Background section may be used as an admission that any part of this application, including this Discussion of the Background section, constitutes prior art to the present disclosure.

SUMMARY

One aspect of the present disclosure provides a semiconductor device including a substrate; a first bottom conductive layer positioned in the substrate; a bottom porous dielectric layer positioned on the substrate; a top porous dielectric layer positioned on the bottom porous dielectric layer; a middle porous dielectric layer positioned between the bottom porous dielectric layer and the top porous dielectric layer; and a mixing-area conductive structure positioned along the top porous dielectric layer, the middle porous dielectric layer, and the bottom porous dielectric layer, and positioned on the first bottom conductive layer. A porosity of the top porous dielectric layer is greater than a porosity of the middle porous dielectric layer. The porosity of the middle porous dielectric layer is greater than a porosity of the bottom porous dielectric layer.

Another aspect of the present disclosure provides a semiconductor device including a substrate including a mixing area and a non-mixing area; a bottom porous dielectric layer positioned on the substrate; a top porous dielectric layer positioned on the bottom porous dielectric layer; a middle porous dielectric layer positioned above the mixing area and positioned between the bottom porous dielectric layer and the top porous dielectric layer; a mixing-area conductive structure positioned along the top porous dielectric layer, the middle porous dielectric layer, and the bottom porous dielectric layer, and positioned on the mixing area of the substrate; and a non-mixing-area conductive structure positioned along the top porous dielectric layer and the bottom porous dielectric layer and positioned on the non-mixing area of the substrate. A porosity of the top porous dielectric layer is greater than a porosity of the middle porous dielectric layer. The porosity of the middle porous dielectric layer is greater than a porosity of the bottom porous dielectric layer.

Another aspect of the present disclosure provides a method for fabricating a semiconductor device including providing a substrate; forming a bottom energy-removable layer on the substrate; forming a top energy-removable layer on the bottom energy-removable layer; forming a mixing-area conductive structure along the bottom energy-removable layer and the top energy-removable layer, and on the substrate; performing an energy treatment to turn the bottom energy-removable layer into a bottom porous dielectric layer, turn the top energy-removable layer into a top porous dielectric layer, and form a middle porous dielectric layer between the bottom porous dielectric layer and the top porous dielectric layer. A porosity of the top porous dielectric layer is greater than a porosity of the middle porous dielectric layer. The porosity of the middle porous dielectric layer is greater than a porosity of the bottom porous dielectric layer.

Due to the design of the semiconductor device of the present disclosure, the top porous dielectric layer, the middle porous dielectric layer, and the bottom porous dielectric layer have low dielectric constant, the parasitic capacitance of the semiconductor device may be reduced by employing the bottom porous dielectric layer, the top porous dielectric layer, and the middle porous dielectric layer having low dielectric constant. As a result, the performance of the semiconductor device may be improved.

The foregoing has outlined rather broadly the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter, and form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRA WINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It should be noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 illustrates, in a flowchart diagram form, a method for fabricating a semiconductor device in accordance with one embodiment of the present disclosure;

FIGS. 2 to 23 illustrate, in schematic cross-sectional view diagrams, a flow for fabricating the semiconductor device in accordance with one embodiment of the present disclosure; and

FIGS. 24 to 26 illustrate, in schematic cross-sectional view diagrams, semiconductor devices in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

It should be understood that when an element or layer is referred to as being “connected to” or “coupled to” another element or layer, it can be directly connected to or coupled to another element or layer, or intervening elements or layers may be present.

It should be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. Unless indicated otherwise, these terms are only used to distinguish one element from another element. Thus, for example, a first element, a first component or a first section discussed below could be termed a second element, a second component or a second section without departing from the teachings of the present disclosure.

Unless the context indicates otherwise, terms such as “same,” “equal,” “planar,” or “coplanar,” as used herein when referring to orientation, layout, location, shapes, sizes, amounts, or other measures do not necessarily mean an exactly identical orientation, layout, location, shape, size, amount, or other measure, but are intended to encompass nearly identical orientation, layout, location, shapes, sizes, amounts, or other measures within acceptable variations that may occur, for example, due to manufacturing processes. The term “substantially” may be used herein to reflect this meaning. For example, items described as “substantially the same,” “substantially equal,” or “substantially planar,” may be exactly the same, equal, or planar, or may be the same, equal, or planar within acceptable variations that may occur, for example, due to manufacturing processes.

In the present disclosure, a semiconductor device generally means a device which can function by utilizing semiconductor characteristics, and an electro-optic device, a light-emitting display device, a semiconductor circuit, and an electronic device are all included in the category of the semiconductor device.

It should be noted that, in the description of the present disclosure, above (or up) corresponds to the direction of the arrow of the direction Z, and below (or down) corresponds to the opposite direction of the arrow of the direction Z.

It should be noted that, in the description of the present disclosure, the terms “forming,” “formed” and “form” may mean and include any method of creating, building, patterning, implanting, or depositing an element, a dopant or a material. Examples of forming methods may include, but are not limited to, atomic layer deposition, chemical vapor deposition, physical vapor deposition, sputtering, co-sputtering, spin coating, diffusing, depositing, growing, implantation, photolithography, dry etching, and wet etching.

It should be noted that, in the description of the present disclosure, the functions or steps noted herein may occur in an order different from the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in a reversed order, depending upon the functionalities or steps involved.

FIG. 1 illustrates, in a flowchart diagram form, a method 10 for fabricating a semiconductor device 1A in accordance with one embodiment of the present disclosure. FIGS. 2 to 23 illustrate, in schematic cross-sectional view diagrams, a flow for fabricating the semiconductor device 1A in accordance with one embodiment of the present disclosure.

With reference to FIGS. 1 to 4, at step S11, a substrate 101 including a non-mixing area NMA and a mixing area MA may be provided, a first bottom conductive layer 103 may be formed in the mixing area MA and a second bottom conductive layer 105 may be formed in the non-mixing area NMA, a bottom dielectric layer 107 may be formed on the substrate 101, and a bottom energy-removable layer 401 may be formed on the bottom dielectric layer 107.

With reference to FIG. 2, in some embodiments, the mixing area MA and the non-mixing area NMA may be separated from each other. In some embodiments, the mixing area MA and the non-mixing area NMA may be formed adjacent to each other.

It should be noted that the mixing area MA may include a portion of the substrate 101 and a space above the portion of the substrate 101. Describing an element as being disposed on the mixing area MA means that the element is disposed on a top surface of the portion of the substrate 101. Describing an element as being disposed in the mixing area MA means that the element is disposed in the portion of the substrate 101; however, a top surface of the element may be even with the top surface of the portion of the substrate 101. Describing an element as being disposed above (or over) the mixing area MA means that the element is disposed above (or over) the top surface of the portion of the substrate 101. Accordingly, the non-mixing area NMA may comprise another portion of the substrate 101 and a space above the other portion of the substrate 101.

With reference to FIG. 2, the substrate 101 may include a bulk semiconductor substrate that is composed entirely of at least one semiconductor material, a plurality of device elements (not shown for clarity), a plurality of dielectric layers (not shown for clarity), and a plurality of conductive features (not shown for clarity). The bulk semiconductor substrate may be formed of, for example, an elementary semiconductor, such as silicon or germanium; a compound semiconductor, such as silicon germanium, silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, indium antimonide, or other III-V compound semiconductor or II-VI compound semiconductor; or combinations thereof.

In some embodiments, the substrate 101 may further include a semiconductor-on-insulator structure which consists of, from bottom to top, a handle substrate, an insulator layer, and a topmost semiconductor material layer. The handle substrate and the topmost semiconductor material layer may be formed of the same material as the bulk semiconductor substrate aforementioned. The insulator layer may be a crystalline or non-crystalline dielectric material such as an oxide and/or nitride. For example, the insulator layer may be a dielectric oxide such as silicon oxide. For another example, the insulator layer may be a dielectric nitride such as silicon nitride or boron nitride. For yet another example, the insulator layer may include a stack of a dielectric oxide and a dielectric nitride such as a stack of, in any order, silicon oxide and silicon nitride or boron nitride. The insulator layer may have a thickness between about 10 nm and 200 nm.

It should be noted that, in the description of present disclosure, the term “about” modifying the quantity of an ingredient, component, or reactant of the present disclosure employed refers to variation in the numerical quantity that can occur, for example, through typical measuring and liquid handling procedures used for making concentrates or solutions. Furthermore, variation can occur from inadvertent error in measuring procedures, differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods, and the like. In one aspect, the term “about” means within 10% of the reported numerical value. In another aspect, the term “about” means within 5% of the reported numerical value. Yet, in another aspect, the term “about” means within 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% of the reported numerical value.

The plurality of device elements may be formed on the substrate 101. Some portions of the plurality of device elements may be formed in the substrate 101. The plurality of device elements may be transistors such as complementary metal-oxide-semiconductor transistors, metal-oxide-semiconductor field-effect transistors, fin field-effect-transistors, the like, or a combination thereof.

The plurality of dielectric layers may be formed on the substrate 101 and cover the plurality of device elements. In some embodiments, the plurality of dielectric layers may be formed of, for example, silicon oxide, borophosphosilicate glass, undoped silicate glass, fluorinated silicate glass, low-k dielectric materials, the like, or a combination thereof. The low-k dielectric materials may have a dielectric constant less than 3.0 or even less than 2.5. In some embodiments, the low-k dielectric materials may have a dielectric constant less than 2.0. The plurality of dielectric layers may be formed by deposition processes such as chemical vapor deposition, plasma-enhanced chemical vapor deposition, or the like. Planarization processes may be performed after the deposition processes to remove excess material and provide a substantially flat surface for subsequent processing steps.

The plurality of conductive features may include interconnect layers, conductive vias, and conductive pads. The interconnect layers may be separated from each other and may be horizontally disposed in the plurality of dielectric layers along the direction Z. In the present embodiment, the topmost interconnect layers may be designated as the conductive pads. The conductive vias may connect adjacent interconnect layers along the direction Z, adjacent device element and interconnect layer, and adjacent conductive pad and interconnect layer. In some embodiments, the conductive vias may improve heat dissipation and may provide structure support. In some embodiments, the plurality of conductive features may be formed of, for example, tungsten, cobalt, zirconium, tantalum, titanium, aluminum, ruthenium, copper, metal carbides (e.g., tantalum carbide, titanium carbide, tantalum magnesium carbide), metal nitrides (e.g., titanium nitride), transition metal aluminides, or a combination thereof. The plurality of conductive features may be formed during the formation of the plurality of dielectric layers.

In some embodiments, the plurality of device elements and the plurality of conductive layers may together configure functional units of the semiconductor device 1A. A functional unit, in the description of the present disclosure, generally refers to functionally related circuitry that has been partitioned for functional purposes into a distinct unit. In some embodiments, the functional units of the semiconductor device 1A may include, for example, highly complex circuits such as processor cores, memory controllers, accelerator units, or other applicable functional circuitry.

With reference to FIG. 2, the first bottom conductive layer 103 may be formed in the mixing area MA. The second bottom conductive layer 105 may be formed in the non-mixing area NMA. In some embodiments, the first bottom conductive layer 103 and the second bottom conductive layer 105 may be referred to as part of the conductive features of the substrate 101. In some embodiments, the first bottom conductive layer 103 and the second bottom conductive layer 105 may be formed of, for example, tungsten, cobalt, zirconium, tantalum, titanium, aluminum, ruthenium, copper, metal carbides (e.g., tantalum carbide, titanium carbide, tantalum magnesium carbide), metal nitrides (e.g., titanium nitride), transition metal aluminides, or a combination thereof. In some embodiments, the width W1 of the first bottom conductive layer 103 and the width W2 of the second bottom conductive layer 105 may be substantially the same. In some embodiments, the width W1 of the first bottom conductive layer 103 and the width W2 of the second bottom conductive layer 105 may be different. The top surfaces of the substrate 101, the first bottom conductive layer 103, and the second bottom conductive layer 105 may be substantially coplanar.

With reference to FIG. 3, the bottom dielectric layer 107 may be formed on the substrate 101 to cover the non-mixing area NMA and the mixing area MA. In some embodiments, the bottom dielectric layer 107 may be formed of a low porous dielectric material. For example, the porosity of the bottom dielectric layer 107 may be less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, or may be 0%. In some embodiments, the bottom dielectric layer 107 may be formed of, for example, silicon oxide. In some embodiments, the bottom dielectric layer 107 may be formed by, for example, chemical vapor deposition, plasma-enhanced chemical vapor deposition, atomic layer deposition, or other applicable deposition processes.

With reference to FIG. 4, a bottom energy-removable layer 401 may be formed on the bottom dielectric layer 107. The bottom energy-removable layer 401 may completely cover the non-mixing area NMA and the mixing area MA. In some embodiments, the bottom energy-removable layer 401 may include a material such as a thermal decomposable material, a photonic decomposable material, an e-beam decomposable material, or a combination thereof. For example, the bottom energy-removable layer 401 may include a base material and a decomposable porogen material that is sacrificially removed upon exposure to an energy source. The base material may include a methylsilsesquioxane based material. The decomposable porogen material may include a porogen organic compound that provides porosity to the base material of the bottom energy-removable layer 401.

In some embodiments, the bottom energy-removable layer 401 may include about 55% of the decomposable porogen material, and about 45% of the base material. In some embodiments, the bottom energy-removable layer 401 may include about 45% of the decomposable porogen material, and about 55% of the base material. In some embodiments, the bottom energy-removable layer 401 may include about 35% of the decomposable porogen material, and about 65% of the base material. In some embodiments, the bottom energy-removable layer 401 may include about 25% of the decomposable porogen material, and about 75% of the base material. In some embodiments, the bottom energy-removable layer 401 may include about 15% of the decomposable porogen material, and about 85% of the base material.

With reference to FIG. 1 and FIGS. 5 to 12, at step S13, a non-mixing-area conductive structure 200 may be formed on the non-mixing area NMA of the substrate 101.

With reference to FIG. 5, a layer of bottom barrier material 501 may be formed on the bottom energy-removable layer 401. The layer of bottom barrier material 501 may completely cover the non-mixing area NMA and the mixing area MA. In some embodiments, the bottom barrier material 501 may be a material having etching selectivity to the bottom energy-removable layer 401. In some embodiments, the bottom barrier material 501 may be a material having etching selectivity to aluminum, copper, or tungsten. In some embodiments, the bottom barrier material 501 may be, for example, silicon nitride, silicon oxynitride, silicon nitride oxide, or a combination thereof. In some embodiments, the layer of bottom barrier material 501 may be formed by, for example, atomic layer deposition, chemical vapor deposition, plasma-enhanced chemical vapor deposition, or other applicable deposition processes.

It should be noted that, in the description of the present disclosure, silicon oxynitride refers to a substance which contains silicon, nitrogen, and oxygen and in which a proportion of oxygen is greater than that of nitrogen. Silicon nitride oxide refers to a substance which contains silicon, oxygen, and nitrogen and in which a proportion of nitrogen is greater than that of oxygen.

With reference to FIG. 5, a first mask layer 601 may be formed on the layer of bottom barrier material 501. In some embodiments, the first mask layer 601 may be a photoresist layer and may include a pattern of a bottom barrier layer 421 which will be illustrated later. The pattern of the first mask layer 601 may be formed by performing a photolithography process. The un-patterned first mask layer 601 (not shown in FIG. 5) may be exposed to process light according to a mask (not shown in FIG. 5). A wavelength of the process light may be associated with the critical dimension of the pattern. In some embodiments, the process light may be a deep ultraviolet (DUV). In some embodiments, the process light may be an extreme ultraviolet (EUV), and the photolithography process may be an EUV lithography. After exposing the process light, a pattern on the mask is converted to the un-patterned first mask layer 601. The un-patterned first mask layer 601 may be then etched according to the converted pattern so as to form the pattern on the first mask layer 601.

With reference to FIG. 6, a first barrier etching process may be performed using the first mask layer 601 as the mask to remove a portion of the bottom barrier material 501. In some embodiments, the etch rate ratio of the bottom barrier material 501 to the bottom energy-removable layer 401 may be between about 100:1 and about 1.05:1, between about 15:1 and about 3:1, or between about 10:1 and about 5:1 during the first barrier etching process. After the first barrier etching process, the remaining bottom barrier material 501 may be turned into a bottom barrier layer 421. The bottom barrier layer 421 may be formed above the non-mixing area NMA and on the bottom energy-removable layer 401. In some embodiments, the width W3 of the bottom barrier layer 421 may be greater than the width W2 of the second bottom conductive layer 105. In some embodiments, the width W3 of the bottom barrier layer 421 may be substantially the same as the width W2 of the second bottom conductive layer 105. In some embodiments, the width W3 of the bottom barrier layer 421 may be less than the width W2 of the second bottom conductive layer 105. The first mask layer 601 may be removed after the formation of the bottom barrier layer 421.

With reference to FIG. 7, a second mask layer 603 may be formed on the bottom energy-removable layer 401 and may cover a portion of the bottom barrier layer 421. The second mask layer 603 may include a pattern of a non-mixing-area recess R1 which will be illustrated later. The pattern of the second mask layer 603 may be formed with a procedure similar to the first mask layer 601, and descriptions thereof are not repeated herein.

With reference to FIG. 8, a first recess etching process may be performed to remove portions of the bottom barrier layer 421, the bottom energy-removable layer 401, and the bottom dielectric layer 107. In some embodiments, the first recess etching process may be a multi-stage etching process. For example, the first recess etching process may be a three-stage anisotropic dry etching process. The etching chemistry may be different for each stage to provide different etching selectivity. In some embodiments, the etch rate ratio of the bottom barrier layer 421 to the bottom energy-removable layer 401 may be between about 100:1 and about 1.05:1, between about 15:1 and about 2:1, or between about 10:1 and about 2:1 during first stage of the first recess etching process. In some embodiments, the etch rate ratio of the bottom energy-removable layer 401 to the bottom dielectric layer 107 may be between about 100:1 and about 1.05:1, between about 15:1 and about 2:1, or between about 10:1 and about 2:1 during second stage of the first recess etching process. In some embodiments, the etch rate ratio of the bottom dielectric layer 107 to the second bottom conductive layer 105 may be between about 100:1 and about 1.05:1, between about 15:1 and about 2:1, or between about 10:1 and about 2:1 during third stage of the first recess etching process.

With reference to FIG. 8, after the first recess etching process, the non-mixing-area recess R1 may be formed along the bottom barrier layer 421, the bottom energy-removable layer 401, and the bottom dielectric layer 107. The second bottom conductive layer 105 may be partially exposed through the non-mixing-area recess R1. In some embodiments, the width W4 of the non-mixing-area recess R1 may be less than the width W2 of the second bottom conductive layer 105 and the width W3 of the bottom barrier layer 421. After the formation of the non-mixing-area recess R1, the second mask layer 603 may be removed.

With reference to FIG. 9, a layer of first liner material 505 may be conformally formed on the bottom energy-removable layer 401, on the bottom barrier layer 421, on the non-mixing-area recess R1, and on the second bottom conductive layer 105. In some embodiments, the first liner material 505 may include, for example, titanium, titanium nitride, tantalum, tantalum nitride, or a combination thereof. In some embodiments, the first liner material 505 may be formed by, for example, chemical vapor deposition, atomic layer deposition, plasma-enhanced chemical vapor deposition, or other applicable deposition processes.

For example, the layer of first liner material 505 may be formed by chemical vapor deposition. In some embodiments, the formation of the layer of first liner material 505 may include a source gas introducing step, a first purging step, a reactant flowing step, and a second purging step. The source gas introducing step, the first purging step, the reactant flowing step, and the second purging step may be referred to as one cycle. Multiple cycles may be performed to obtain the desired thickness of the layer of first liner material 505.

Detailedly, the intermediate semiconductor device illustrated in FIG. 8 may be loaded in a reaction chamber. In the source gas introducing step, source gases containing a precursor and a reactant may be introduced to the reaction chamber containing the intermediate semiconductor device. The precursor and the reactant may diffuse across the boundary layer and reach the surface of the intermediate semiconductor device (i.e., the surface of the bottom energy-removable layer 401, the bottom barrier layer 421, the non-mixing-area recess R1, and the second bottom conductive layer 105). The precursor and the reactant may adsorb on and subsequently migrate on the surface aforementioned. The adsorbed precursor and the adsorbed reactant may react on the surface aforementioned and form solid byproducts. The solid byproducts may form nuclei on the surface aforementioned. The nuclei may grow into islands and the islands may merge into a continuous thin film on the surface aforementioned. In the first purging step, a purge gas such as argon may be injected into the reaction chamber to purge out the gaseous byproducts, unreacted precursor, and unreacted reactant.

In the reactant flowing step, the reactant may be solely introduced to the reaction chamber to turn the continuous thin film into the layer of first liner material 505. In the second purging step, a purge gas such as argon may be injected into the reaction chamber to purge out the gaseous byproducts and unreacted reactant.

In some embodiments, the formation of the layer of first liner material 505 using chemical vapor deposition may be performed with the assistance of plasma. The source of the plasma may be, for example, argon, hydrogen, or a combination thereof.

In some embodiments, the precursor may be titanium tetrachloride. The reactant may be ammonia. Titanium tetrachloride and ammonia may react on the surface and form a titanium nitride film including high chloride contamination due to incomplete reaction between titanium tetrachloride and ammonia. The ammonia in the reactant flowing step may reduce the chloride content of the titanium nitride film. After the ammonia treatment, the titanium nitride film may be referred to as the layer of first liner material 505.

For another example, the layer of first liner material 505 may be formed by atomic layer deposition such as photo-assisted atomic layer deposition or liquid injection atomic layer deposition. In some embodiments, the formation of the layer of first liner material 505 may include a first precursor introducing step, a first purging step, a second precursor introducing step, and a second purging step. The first precursor introducing step, the first purging step, the second precursor introducing step, and the second purging step may be referred to as one cycle. Multiple cycles may be performed to obtain the desired thickness of the layer of first liner material 505.

Detailedly, the intermediate semiconductor device illustrated in FIG. 8 may be loaded in the reaction chamber. In the first precursor introducing step, a first precursor may be introduced to the reaction chamber. The first precursor may diffuse across the boundary layer and reach the surface of the intermediate semiconductor device (i.e., the surface of the bottom energy-removable layer 401, the bottom barrier layer 421, the non-mixing-area recess R1, and the second bottom conductive layer 105). The first precursor may adsorb on the surface aforementioned to form a monolayer at a single atomic layer level. In the first purging step, a purge gas such as argon may be injected into the reaction chamber to purge out unreacted first precursor.

In the second precursor introducing step, a second precursor may be introduced to the reaction chamber. The second precursor may react with the monolayer and turn the monolayer into the layer of first liner material 505. In the second purging step, a purge gas such as argon may be injected into the reaction chamber to purge out unreacted second precursor and gaseous byproduct. Compared to the chemical vapor deposition, a particle generation caused by a gas phase reaction may be suppressed because the first precursor and the second precursor are separately introduced.

In some embodiments, the first precursor may be titanium tetrachloride. The second precursor may be ammonia. Adsorbed titanium tetrachloride may form a titanium nitride monolayer. The ammonia in the second precursor introducing step may react with the titanium nitride monolayer and turn the titanium nitride monolayer into the layer of first liner material 505.

In some embodiments, the formation of the layer of first liner material 505 using atomic layer deposition may be performed with the assistance of plasma. The source of the plasma may be, for example, argon, hydrogen, oxygen, or a combination thereof. In some embodiments, the oxygen source may be, for example, water, oxygen gas, or ozone. In some embodiments, co-reactants may be introduced to the reaction chamber. The co-reactants may be selected from the group consisting of hydrogen, hydrogen plasma, oxygen, air, water, ammonia, hydrazines, alkylhydrazines, boranes, silanes, ozone, and a combination thereof.

In some embodiments, the formation of the layer of first liner material 505 may be performed using the following process conditions. The substrate temperature may be between about 160° C. and about 300° C. The evaporator temperature may be about 175° C. The pressure of the reaction chamber may be about 5 mbar. The solvent for the first precursor and the second precursor may be toluene.

With reference to FIG. 10, a layer of first conductive material 509 may be formed on the layer of first liner material 505 and may completely fill the non-mixing-area recess R1. In some embodiments, the first conductive material 509 may include aluminum, copper, tungsten, or a combination thereof. In some embodiments, the layer of first conductive material 509 may be formed by, for example, physical vapor deposition, sputtering, electroplating, electroless plating, chemical vapor deposition, or other applicable deposition processes.

In some embodiments, a planarization process, such as chemical mechanical polishing, may be performed on the layer of first conductive material 509 to provide a substantially flat surface for subsequent processing steps.

With reference to FIG. 11, a non-mixing-area hard mask layer 205 may be formed on the layer of first conductive material 509 and formed above the bottom barrier layer 421. In some embodiments, the width W5 of the non-mixing-area hard mask layer 205 may be less than the width W3 of the bottom barrier layer 421. In some embodiments, the width W5 of the non-mixing-area hard mask layer 205 may be greater than the width W2 of the second bottom conductive layer 105.

In some embodiments, the width W5 of the non-mixing-area hard mask layer 205 and the width W2 of the second bottom conductive layer 105 may be substantially the same.

In some embodiments, the non-mixing-area hard mask layer 205 may be formed of, for example, a material having etching selectivity to the first conductive material 509, the first liner material 505, or the bottom barrier layer 421. In some embodiments, the non-mixing-area hard mask layer 205 may be formed of, for example, silicon, silicon germanium, tetraethyl orthosilicate, silicon nitride, silicon oxynitride, silicon nitride oxide, silicon carbide, the like, or a combination thereof. In some embodiments, the non-mixing-area hard mask layer 205 may be formed by a deposition process such as chemical vapor deposition, plasma-enhanced chemical vapor deposition, atomic layer deposition, or the like. The process temperature of forming the non-mixing-area hard mask layer 205 may be less than 400° C.

In some embodiments, the non-mixing-area hard mask layer 205 may be formed of, for example, boron nitride, silicon boron nitride, phosphorus boron nitride, boron carbon silicon nitride, or the like. In some embodiments, the non-mixing-area hard mask layer 205 may be formed by a film formation process and a treatment process. Detailedly, in the film formation process, first precursors, which may be boron-based precursors, may be introduced over the layer of first conductive material 509 to form a boron-based layer. Subsequently, in the treatment process, second precursors, which may be nitrogen-based precursors, may be introduced to react with the boron-based layer and turn the boron-based layer into the non-mixing-area hard mask layer 205.

In some embodiments, the first precursors may be, for example, diborane, borazine, or an alkyl-substituted derivative of borazine. In some embodiments, the first precursors may be introduced at a flow rate between about 5 sccm and about 50 slm (standard liter per minute) or between about 10 sccm and about 1 slm. In some embodiments, the first precursors may be introduced by dilution gas such as nitrogen, hydrogen, argon, or a combination thereof. The dilution gas may be introduced at a flow rate between about 5 sccm and about 50 slm or between about 1 slm and about 10 slm.

In some embodiments, the film formation process may be performed without an assistant of plasma. In such a situation, a substrate temperature of the film formation process may be between about 100° C. and about 1000° C. For example, the substrate temperature of the film formation process may be between about 300° C. and about 500° C. A process pressure of the film formation process may be between about 10 mTorr and about 760 Torr. For example, the process pressure of the film formation process may be between about 2 Torr and about 10 Torr.

In some embodiments, the film formation process may be performed in the presence of plasma. In such a situation, a substrate temperature of the film formation process may be between about 100° C. and about 1000° C. For example, the substrate temperature of the film formation process may be between about 300° C. and about 500° C. A process pressure of the film formation process may be between about 10 mTorr and about 760 Torr. For example, the process pressure of the film formation process may be between about 2 Torr and about 10 Torr. The plasma may be generated by a RF power between 2 W and 5000 W. For example, the RF power may be between 30 W and 1000 W.

In some embodiments, the second precursors may be, for example, ammonia or hydrazine. In some embodiments, the second precursors may be introduced at a flow rate between about 5 sccm and about 50 slm or between about 10 sccm and about 1 slm.

In some embodiments, oxygen-based precursors may be introduced with the second precursors in the treatment process. The oxygen-based precursors may be, for example, oxygen, nitric oxide, nitrous oxide, carbon dioxide, or water.

In some embodiments, silicon-based precursors may be introduced with the second precursors in the treatment process. The silicon-based precursors may be, for example, silane, trisilylamine, trimethylsilane, or silazanes (e.g., hexamethylcyclotrisilazane).

In some embodiments, phosphorus-based precursors may be introduced with the second precursors in the treatment process. The phosphorus-based precursors may be, for example, phosphine.

In some embodiments, oxygen-based precursors, silicon-based precursors, or phosphorus-based precursors may be introduced with the second precursors in the treatment process.

In some embodiments, the treatment process may be

performed with an assistant of a plasma process, a UV cure process, a thermal anneal process, or a combination thereof.

When the treatment is performed with the assistance of the plasma process. The plasma of the plasma process may be generated by the RF power. In some embodiments, the RF power may be between about 2 W and about 5000 W at a single low frequency of between about 100 kHz up to about 1 MHz. In some embodiments, the RF power may be between about 30 W and about 1000 W at a single high frequency greater than about 13.6 MHz. In such a situation, a substrate temperature of the treatment process may be between about 20° C. and about 1000° C. A process pressure of the treatment process may be between about 10 mTorr and about 760 Torr.

When the treatment is performed with the assistance of UV cure process, in such a situation, a substrate temperature of the treatment process may be between about 20° C. and about 1000° C. A process pressure of the treatment process may be between about 10 mTorr and about 760 Torr. The UV cure may be provided by any UV source, such as mercury microwave arc lamps, pulsed xenon flash lamps, or high-efficiency UV light emitting diode arrays. The UV source may have a wavelength of between about 170 nm and about 400 nm. The UV source may provide a photon energy between about 0.5 eV and about 10 eV, or between about 1 eV and about 6 eV. The assistance of the UV cure process may remove hydrogen from the non-mixing-area hard mask layer 205. As hydrogen may diffuse through into other areas of the semiconductor device 1A and may degrade the reliability of the semiconductor device 1A, the removal of hydrogen by the assistance of UV cure process may improve the reliability of the semiconductor device 1A. In addition, the UV cure process may increase the density of the non-mixing-area hard mask layer 205.

When the treatment is performed with the assistant of the thermal anneal process. In such a situation, a substrate temperature of the treatment process may be between about 20° C. and about 1000° C. A process pressure of the treatment process may be between about 10 mTorr and about 760 Torr.

With reference to FIG. 12, a first etching process may be performed using the non-mixing-area hard mask layer 205 as the mask to remove portions of the first conductive material 509 and the first liner material 505. In some embodiments, the first etching process may be a multi-stage etching process. For example, the first etching process may be a two-stage anisotropic dry etching process. The etching chemistry may be different for each stage to provide different etching selectivity. In some embodiments, the etch rate ratio of the first conductive material 509 to the non-mixing-area hard mask layer 205 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during first stage of the first etching process. In some embodiments, the etch rate ratio of the first conductive material 509 to the first liner material 505 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during first stage of the first etching process.

In some embodiments, the etch rate ratio of the first liner material 505 to the non-mixing-area hard mask layer 205 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during second stage of the first etching process. In some embodiments, the etch rate ratio of the first liner material 505 to the bottom barrier layer 421 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during second stage of the first etching process. In some embodiments, the etch rate ratio of the first liner material 505 to the bottom energy-removable layer 401 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during second stage of the first etching process.

With reference to FIG. 12, after the first etching process, the remaining first conductive material 509 may be referred to as the non-mixing-area conductive layer 203. The remaining first liner material 505 may be referred to as the non-mixing-area liner layer 201. The non-mixing-area liner layer 201, the non-mixing-area conductive layer 203, and the non-mixing-area hard mask layer 205 together configure the non-mixing-area conductive structure 200. The non-mixing-area conductive structure 200 may be formed on the second bottom conductive layer 105 and on the non-mixing area NMA.

With reference to FIG. 12, the non-mixing-area conductive layer 203 may include a vertical portion 203V and a horizontal portion 203H. The vertical portion 203V may be disposed on the second bottom conductive layer 105 and in the non-mixing-area recess R1. A top part of the vertical portion 203V may protrude from the top surface 401TS of the bottom energy-removable layer 401 and may be surrounded by the bottom barrier layer 421. State differently, the top surface of the vertical portion 203V may be at a vertical level VL1 higher than the top surface 401TS of the bottom energy-removable layer 401. A bottom part of the vertical portion 203V may be surrounded by the bottom dielectric layer 107. In some embodiments, the width W6 of the vertical portion 203V may be less than the width W5 of the non-mixing-area hard mask layer 205.

With reference to FIG. 12, the horizontal portion 203H may be disposed on the vertical portion 203V and on the bottom barrier layer 421. In some embodiments, the horizontal portion 203H may have the same width W5 as the non-mixing-area hard mask layer 205. In some embodiments, the width W5 of the horizontal portion 203H may be greater than the width W6 of the vertical portion 203V. That is, the non-mixing-area conductive layer 203 may have a T-shaped cross-sectional profile. In some embodiments, the width W5 of the horizontal portion 203H may be less than the width W3 of the bottom barrier layer 421.

With reference to FIG. 12, the non-mixing-area liner layer 201 may be conformally disposed between the non-mixing-area conductive layer 203 and the bottom energy-removable layer 401, between the non-mixing-area conductive layer 203 and the bottom barrier layer 421, between the non-mixing-area conductive layer 203 and the bottom dielectric layer 107, and between the non-mixing-area conductive layer 203 and the second bottom conductive layer 105. Detailedly, the non-mixing-area liner layer 201 may be conformally disposed between the horizontal portion 203H and the bottom barrier layer 421, between the vertical portion 203V and the bottom barrier layer 421, between the vertical portion 203V and the bottom energy-removable layer 401, between the vertical portion 203V and the bottom dielectric layer 107, and between the vertical portion 203V and the second bottom conductive layer 105. The non-mixing-area liner layer 201 may improve the adhesion between the non-mixing-area conductive layer 203 and the bottom barrier layer 421, the bottom energy-removable layer 401, the bottom dielectric layer 107, and the second bottom conductive layer 105. The non-mixing-area liner layer 201 may also prevent the metal ion diffusing from the non-mixing-area conductive layer 203 to the bottom energy-removable layer 401 or the substrate 101.

With reference to FIG. 1 and FIGS. 13 to 21, at step S15, a mixing-area conductive structure 300 may be formed on the mixing area MA of the substrate 101.

With reference to FIG. 13, a top energy-removable layer 403 may be formed on the bottom energy-removable layer 401 and cover the non-mixing-area conductive structure 200 and the bottom barrier layer 421. The top energy-removable layer 403 may completely cover the non-mixing area NMA and the mixing area MA. In some embodiments, the top energy-removable layer 403 may include a material such as a thermal decomposable material, a photonic decomposable material, an e-beam decomposable material, or a combination thereof. For example, the top energy-removable layer 403 may include a base material and a decomposable porogen material that is sacrificially removed upon exposure to an energy source. The base material may include a methylsilsesquioxane based material. The decomposable porogen material may include a porogen organic compound that provides porosity to the base material of the top energy-removable layer 403.

In some embodiments, the ratio of the base material of the top energy-removable layer 403 may be less than the ratio of the base material of the bottom energy-removable layer 401. In some embodiments, the top energy-removable layer 403 may include about 55% of the decomposable porogen material, and about 45% of the base material. In some embodiments, the top energy-removable layer 403 may include about 65% of the decomposable porogen material, and about 35% of the base material. In some embodiments, the top energy-removable layer 403 may include about 75% of the decomposable porogen material, and about 25% of the base material. In some embodiments, the top energy-removable layer 403 may include about 85% of the decomposable porogen material, and about 15% of the base material.

In some embodiments, a planarization process, such as chemical mechanical polishing, may be performed to provide a substantially flat surface for subsequent processing steps.

With reference to FIG. 14, a layer of top barrier material 503 may be formed on the top energy-removable layer 403. The layer of top barrier material 503 may completely cover the non-mixing area NMA and the mixing area MA. In some embodiments, the top barrier material 503 may be a material having etching selectivity to the top energy-removable layer 403. In some embodiments, the top barrier material 503 may be a material having etching selectivity to aluminum, copper, or tungsten. In some embodiments, the top barrier material 503 may be, for example, silicon nitride, silicon oxynitride, silicon nitride oxide, or a combination thereof. In some embodiments, the layer of top barrier material 503 may be formed by, for example, atomic layer deposition, chemical vapor deposition, plasma-enhanced chemical vapor deposition, or other applicable deposition processes.

With reference to FIG. 14, a third mask layer 605 may be formed on the layer of top barrier material 503. In some embodiments, the third mask layer 605 may be a photoresist layer and may include a pattern of a top barrier layer 423 which will be illustrated later. The pattern of the third mask layer 605 may be formed by performing a photolithography process. The un-patterned third mask layer 605 (not shown in FIG. 14) may be exposed to process light according to a mask (not shown in FIG. 14). A wavelength of the process light may be associated with the critical dimension of the pattern. In some embodiments, the process light may be a deep ultraviolet (DUV). In some embodiments, the process light may be an extreme ultraviolet (EUV), and the photolithography process may be an EUV lithography. After exposing the process light, a pattern on the mask is converted to the un-patterned third mask layer 605. The un-patterned third mask layer 605 may be then etched according to the converted pattern so as to form the pattern on the third mask layer 605.

With reference to FIG. 15, a second barrier etching process may be performed using the third mask layer 605 as the mask to remove a portion of the top barrier material 503. In some embodiments, the etch rate ratio of the top barrier material 503 to the top energy-removable layer 403 may be between about 100:1 and about 1.05:1, between about 15:1 and about 3:1, or between about 10:1 and about 5:1 during the second barrier etching process. After the second barrier etching process, the remaining top barrier material 503 may be turned into a top barrier layer 423. The top barrier layer 423 may be formed above the mixing area MA and on the top energy-removable layer 403.

In some embodiments, the width W7 of the top barrier layer 423 may be greater than the width W1 of the first bottom conductive layer 103. In some embodiments, the width W7 of the top barrier layer 423 may be substantially the same as the width W1 of the first bottom conductive layer 103. In some embodiments, the width W7 of the top barrier layer 423 may be less than the width W1 of the first bottom conductive layer 103. In some embodiments, the width W7 of the top barrier layer 423 and the width W3 of the bottom barrier layer 421 may be substantially the same. In some embodiments, the width W7 of the top barrier layer 423 and the width W3 of the bottom barrier layer 421 may be different. The third mask layer 605 may be removed after the formation of the top barrier layer 423.

With reference to FIG. 16, a fourth mask layer 607 may be formed on the top energy-removable layer 403 and may cover a portion of the top barrier layer 423. The fourth mask layer 607 may include a pattern of a mixing-area recess R2 which will be illustrated later. The pattern of the fourth mask layer 607 may be formed with a procedure similar to the third mask layer 605, and descriptions thereof are not repeated herein.

With reference to FIG. 17, a second recess etching process may be performed to remove portions of the top barrier layer 423, the top energy-removable layer 403, the bottom energy-removable layer 401, and the bottom dielectric layer 107. In some embodiments, the second recess etching process may be a multi-stage etching process. For example, the second recess etching process may be a three-stage anisotropic dry etching process. The etching chemistry may be different for each stage to provide different etching selectivity.

In some embodiments, the etch rate ratio of the top barrier layer 423 to the top energy-removable layer 403 may be between about 100:1 and about 1.05:1, between about 15:1 and about 2:1, or between about 10:1 and about 2:1 during first stage of the second recess etching process. In some embodiments, the etch rate ratio of the top energy-removable layer 403 (and the bottom energy-removable layer 401) to the bottom dielectric layer 107 may be between about 100:1 and about 1.05:1, between about 15:1 and about 2:1, or between about 10:1 and about 2:1 during second stage of the second recess etching process. In some embodiments, the etch rate ratio of the bottom dielectric layer 107 to the first bottom conductive layer 103 may be between about 100:1 and about 1.05:1, between about 15:1 and about 2:1, or between about 10:1 and about 2:1 during the third stage of the second recess etching process.

With reference to FIG. 17, after the second recess etching process, the mixing-area recess R2 may be formed along the top barrier layer 423, the top energy-removable layer 403, the bottom energy-removable layer 401, and the bottom dielectric layer 107. The first bottom conductive layer 103 may be partially exposed through the mixing-area recess R2. In some embodiments, the width W8 of the mixing-area recess R2 may be less than the width W1 of the first bottom conductive layer 103 and the width W7 of the top barrier layer 423. After the formation of the mixing-area recess R2, the fourth mask layer 607 may be removed.

With reference to FIG. 18, a layer of second liner material 507 may be conformally formed on the top energy-removable layer 403, on the top barrier layer 423, on the mixing-area recess R2, and on the first bottom conductive layer 103. In some embodiments, the second liner material 507 may include, for example, titanium, titanium nitride, tantalum, tantalum nitride, or a combination thereof. In some embodiments, the second liner material 507 may be formed by, for example, chemical vapor deposition, atomic layer deposition, plasma-enhanced chemical vapor deposition, or other applicable deposition processes.

In some embodiments, the second liner material 507 may be the same material as the first liner material 505. The formation of the layer of second liner material 507 may be similar to the formation of the layer of first liner material 505 which is illustrated in FIG. 9, and descriptions thereof are not repeated herein.

With reference to FIG. 19, a layer of second conductive material 511 may be formed on the layer of second liner material 507 and may completely fill the mixing-area recess R2. In some embodiments, the second conductive material 511 may include aluminum, copper, tungsten, or a combination thereof. In some embodiments, the layer of second conductive material 511 may be formed by, for example, physical vapor deposition, sputtering, electroplating, electroless plating, chemical vapor deposition, or other applicable deposition processes.

In some embodiments, a planarization process, such as chemical mechanical polishing, may be performed on the layer of second conductive material 511 to provide a substantially flat surface for subsequent processing steps.

With reference to FIG. 20, a mixing-area hard mask layer 305 may be formed on the layer of second conductive material 511 and formed above the top barrier layer 423. In some embodiments, the width W9 of the mixing-area hard mask layer 305 may be less than the width W7 of the top barrier layer 423. In some embodiments, the width W9 of the mixing-area hard mask layer 305 may be greater than the width W1 of the first bottom conductive layer 103. In some embodiments, the width W9 of the mixing-area hard mask layer 305 and the width W1 of the first bottom conductive layer 103 may be substantially the same. In some embodiments, the width W9 of the mixing-area hard mask layer 305 and the width W5 of the non-mixing-area hard mask layer 205 may be substantially the same. In some embodiments, the width W9 of the mixing-area hard mask layer 305 and the width W5 of the non-mixing-area hard mask layer 205 may be different.

In some embodiments, the mixing-area hard mask layer 305 may be formed of, for example, a material having etching selectivity to the second conductive material 511, the second liner material 507, and the top barrier layer 423. In some embodiments, the mixing-area hard mask layer 305 may be formed of, for example, silicon, silicon germanium, tetraethyl orthosilicate, silicon nitride, silicon oxynitride, silicon nitride oxide, silicon carbide, the like, or a combination thereof. In some embodiments, the mixing-area hard mask layer 305 may be formed of, for example, boron nitride, silicon boron nitride, phosphorus boron nitride, boron carbon silicon nitride, or the like. The mixing-area hard mask layer 305 may be formed with a procedure similar to the non-mixing-area hard mask layer 205 which is illustrated in FIG. 11, and descriptions thereof are not repeated herein.

With reference to FIG. 21, a second etching process may be performed using the mixing-area hard mask layer 305 as the mask to remove portions of the second conductive material 511 and the second liner material 507. In some embodiments, the second etching process may be a multi-stage etching process. For example, the second etching process may be a two-stage anisotropic dry etching process. The etching chemistry may be different for each stage to provide different etching selectivity. In some embodiments, the etch rate ratio of the second conductive material 511 to the mixing-area hard mask layer 305 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during first stage of the second etching process. In some embodiments, the etch rate ratio of the second conductive material 511 to the second liner material 507 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during first stage of the second etching process.

In some embodiments, the etch rate ratio of the second liner material 507 to the mixing-area hard mask layer 305 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during second stage of the second etching process. In some embodiments, the etch rate ratio of the second liner material 507 to the top barrier layer 423 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during second stage of the second etching process. In some embodiments, the etch rate ratio of the second liner material 507 to the top energy-removable layer 403 may be between about 100:1 and about 1.05:1, between about 15:1 and about 5:1, or between about 10:1 and about 3:1 during second stage of the second etching process.

With reference to FIG. 21, after the second etching process, the remaining second conductive material 511 may be referred to as the mixing-area conductive layer 303. The remaining second liner material 507 may be referred to as the mixing-area liner layer 301. The mixing-area liner layer 301, the mixing-area conductive layer 303, and the mixing-area hard mask layer 305 together configure the mixing-area conductive structure 300. The mixing-area conductive structure 300 may be formed on the first bottom conductive layer 103 and on the mixing area MA.

With reference to FIG. 21, the mixing-area conductive layer 303 may include a vertical portion 303V and a horizontal portion 303H. The vertical portion 303V may be disposed on the first bottom conductive layer 103 and in the mixing-area recess R2. A top part of the vertical portion 303V may protrude from the top surface 403TS of the top energy-removable layer 403 and may be surrounded by the top barrier layer 423. State differently, the top surface of the vertical portion 303V may be at a vertical level VL2 higher than the top surface 403TS of the top energy-removable layer 403. A bottom part of the vertical portion 303V may be surrounded by the bottom dielectric layer 107. In some embodiments, the width W10 of the vertical portion 303V may be less than the width W9 of the mixing-area hard mask layer 305. In some embodiments, the width W10 of the vertical portion 303V and the width W6 of the vertical portion 203V may be substantially the same. In some embodiments, the width W10 of the vertical portion 303V and the width W6 of the vertical portion 203V may be different.

With reference to FIG. 21, the horizontal portion 303H may be disposed on the vertical portion 303V and on the top barrier layer 423. In some embodiments, the horizontal portion 303H may have the same width W9 as the mixing-area hard mask layer 305. In some embodiments, the width W9 of the horizontal portion 303H may be greater than the width W10 of the vertical portion 303V. That is, the mixing-area conductive layer 303 may have a T-shaped cross-sectional profile. In some embodiments, the width W9 of the horizontal portion 303H may be less than the width W7 of the top barrier layer 423. In some embodiments, the width W9 of the horizontal portion 303H and the width W5 of the horizontal portion 203H may be substantially the same. In some embodiments, the width W9 of the horizontal portion 303H and the width W5 of the horizontal portion 203H may be different.

With reference to FIG. 21, the mixing-area liner layer 301 may be conformally disposed between the mixing-area conductive layer 303 and the bottom energy-removable layer 401, between the mixing-area conductive layer 303 and the top energy-removable layer 403, between the mixing-area conductive layer 303 and the top barrier layer 423, between the mixing-area conductive layer 303 and the bottom dielectric layer 107, and between the mixing-area conductive layer 303 and the first bottom conductive layer 103.

Detailedly, the mixing-area liner layer 301 may be conformally disposed between the horizontal portion 303H and the top barrier layer 423, between the vertical portion 303V and the top barrier layer 423, between the vertical portion 303V and the top energy-removable layer 403, between the vertical portion 303V and the bottom energy-removable layer 401, between the vertical portion 303V and the bottom dielectric layer 107, and between the vertical portion 303V and the first bottom conductive layer 103. The mixing-area liner layer 301 may improve the adhesion between the mixing-area conductive layer 303 and the top barrier layer 423, the top energy-removable layer 403, the bottom energy-removable layer 401, the bottom dielectric layer 107, and the first bottom conductive layer 103. The mixing-area liner layer 301 may also prevent the metal ion diffusing from the mixing-area conductive layer 303 to the bottom energy-removable layer 401, the top energy-removable layer 403, or the substrate 101.

With reference to FIGS. 1, 22, and 23, at step S17, an energy treatment may be performed to turn the bottom energy-removable layer 401 into a bottom porous dielectric layer 411, turn the top energy-removable layer 403 into a top porous dielectric layer 413, and form a middle porous dielectric layer 415 over the mixing area MA of the substrate 101 and between the bottom porous dielectric layer 411 and the top porous dielectric layer 413, and a top dielectric layer 109 may be formed on the top porous dielectric layer 413.

With reference to FIG. 22, the energy treatment may be performed to the intermediate semiconductor device in FIG. 21 by applying the energy source thereto. The energy source may include heat, light, or a combination thereof. When heat is used as the energy source, a temperature of the energy treatment may be between about 800° C. and about 900° C. When light is used as the energy source, an ultraviolet light may be applied. The energy treatment may remove the decomposable porogen material from the bottom energy-removable layer 401 and the top energy-removable layer 403 to generate empty spaces (pores), with the base material remaining in place. The empty spaces may be filled with air so that a dielectric constant of the resulting layers containing the empty spaces may be significantly low.

After the energy treatment, the bottom energy-removable layer 401 may be turned into the bottom porous dielectric layer 411. The bottom porous dielectric layer 411 may be disposed on the bottom dielectric layer 107 and above the non-mixing area NMA and the mixing area MA of the substrate 101. The top energy-removable layer 403 may be turned into the top porous dielectric layer 413. The top porous dielectric layer 413 may be disposed on the bottom porous dielectric layer 411 and above the non-mixing area NMA and the mixing area MA of the substrate 101. In some embodiments, the porosity of the top porous dielectric layer 413 may be greater than the porosity of the bottom porous dielectric layer 411.

In some embodiments, above the mixing area MA, due to no barrier layer is present between the bottom energy-removable layer 401 and the top energy-removable layer 403, the bottom energy-removable layer 401 and the top energy-removable layer 403 may mix at the interface between the bottom energy-removable layer 401 and the top energy-removable layer 403. As a result, the middle porous dielectric layer 415 may be formed between the bottom porous dielectric layer 411 and the top porous dielectric layer 413 and only above the mixing area MA after the energy treatment. In some embodiments, the porosity of the middle porous dielectric layer 415 may be less than the porosity of the top porous dielectric layer 413 and may be greater than the porosity of the bottom porous dielectric layer 411. In some embodiments, the interface between the top porous dielectric layer 413 and the middle porous dielectric layer 415 may be vague. In some embodiments, the interface between the middle porous dielectric layer 415 and the bottom porous dielectric layer 411 may be vague.

In some embodiments, along the direction Z and toward the substrate 101, the porosity of the middle porous dielectric layer 415 may be gradually decreased. In some embodiments, the porosity of the bottom dielectric layer 107 may be less than the porosity of the bottom porous dielectric layer 411, the porosity of the middle porous dielectric layer 415, or the porosity of the top porous dielectric layer 413.

With reference to FIG. 23, the top dielectric layer 109 may be formed on the top porous dielectric layer 413 and cover the mixing-area conductive structure 300 and the top barrier layer 423. In some embodiments, the top dielectric layer 109 may be formed of, for example, silicon dioxide, undoped silicate glass, fluorosilicate glass, borophosphosilicate glass, a spin-on low-k dielectric layer, a chemical vapor deposition low-k dielectric layer, or a combination thereof. The term “low-k” as used throughout the present application denotes a dielectric material that has a dielectric constant of less than silicon dioxide. In some embodiments, the top dielectric layer 109 may include a self-planarizing material such as a spin-on glass or a spin-on low-k dielectric material such as SiLK™. The use of a self-planarizing dielectric material may avoid the need to perform a subsequent planarizing step. In some embodiments, the top dielectric layer 109 may be formed by a deposition process including, for example, chemical vapor deposition, plasma enhanced chemical vapor deposition, evaporation, or spin-on coating.

By employing the bottom porous dielectric layer 411, the top porous dielectric layer 413, and the middle porous dielectric layer 415 having low dielectric constant, the parasitic capacitance of the semiconductor device 1A may be reduced. As a result, the performance of the semiconductor device 1A may be improved. In addition, the bottom barrier layer 421 or the top barrier layer 423 may prevent outgassing issue of the porous layers (i.e., the bottom porous dielectric layer 411, the top porous dielectric layer 413, and the middle porous dielectric layer 415) to avoid the damage of the conductive structures (i.e., the mixing-area conductive structure 300 and the non-mixing-area conductive structure 200) and to improve the reliability of the semiconductor device 1A. Furthermore, the bottom barrier layer 421 and the top barrier layer 423 may also serve as etching stop layers during the formation of the conductive structures to avoid the damage of the bottom energy-removable layer 401 and the top energy-removable layer 403 during the formation of the conductive structures.

FIGS. 24 to 26 illustrate, in schematic cross-sectional view diagrams, semiconductor devices 1B, 1C, and 1D in accordance with some embodiments of the present disclosure.

With reference to FIGS. 24 to 26, each of the semiconductor devices 1B, 1C, and 1D may have a structure similar to that illustrated in FIG. 23. The same or similar elements in FIGS. 24 to 26 as in FIG. 23 have been marked with similar reference numbers and duplicative descriptions have been omitted.

With reference to FIG. 24, in the semiconductor device 1B, the bottom barrier layer 421 may be disposed between the bottom porous dielectric layer 411 and the top porous dielectric layer 413 and may completely separate the bottom porous dielectric layer 411 and the top porous dielectric layer 413 above the non-mixing area NMA of the substrate 101.

With reference to FIG. 25, in the semiconductor device 1C, the top barrier layer 423 may completely separate the top dielectric layer 109 and the top porous dielectric layer 413 above the non-mixing area NMA and the mixing area MA of the substrate 101. In this regard, the top barrier layer 423 may be referred to as the capping layer or the sealing layer of the top barrier layer 423.

With reference to FIG. 26, in the semiconductor device ID, the bottom barrier layer 421 may be disposed between the bottom porous dielectric layer 411 and the top porous dielectric layer 413 and may completely separate the bottom porous dielectric layer 411 and the top porous dielectric layer 413 above the non-mixing area NMA of the substrate 101. The top barrier layer 423 may completely separate the top dielectric layer 109 and the top porous dielectric layer 413 above the non-mixing area NMA and the mixing area MA of the substrate 101.

Due to the design of the semiconductor device of the present disclosure, the parasitic capacitance of the semiconductor device 1A may be reduced by employing the bottom porous dielectric layer 411, the top porous dielectric layer 413, and the middle porous dielectric layer 415 having low dielectric constant. As a result, the performance of the semiconductor device 1A may be improved. In addition, the bottom barrier layer 421 or the top barrier layer 423 may prevent outgassing issue of the porous layers (i.e., the bottom porous dielectric layer 411, the top porous dielectric layer 413, and the middle porous dielectric layer 415) to avoid the damage of the conductive structures (i.e., the mixing-area conductive structure 300 and the non-mixing-area conductive structure 200) and to improve the reliability of the semiconductor device 1A. Furthermore, the bottom barrier layer 421 and the top barrier layer 423 may also serve as etching stop layers during the formation of the conductive structures to avoid the damage of the bottom energy-removable layer 401 and the top energy-removable layer 403 during the formation of the conductive structures.

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. For example, many of the processes discussed above can be implemented in different methodologies and replaced by other processes, or a combination thereof.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, and steps.

SEMICONDUCTOR DEVICE WITH POROUS LAYER AND METHOD FOR FABRICATING THE SAME

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