The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component that can be created using a fabrication process) has decreased.
For example, ICs are formed on a semiconductor substrate. Each IC chip is further attached (such as by bonding) to a circuit board, such as a printed circuit board (PCB) in electronic products. A redistribution layer (RDL) of conductive features (e.g., metal lines, vias) may be formed to reroute bond connections from the edge to the center of the chip. A passivation structure is coupled to the RDL to protect the semiconductor surface from electrical and chemical contaminants. However, an IC chip may be bonded to a package substrate before the package substrate is bonded to a PCB. The IC chip and the package substrate have different coefficients of thermal expansion (CTEs). During or after fabrication processes, the IC chip and the package substrate may expand and contract differently, causing stress near metal lines and cracks in the passivation structure, which lead to device failure. Therefore, although existing metal lines (or conductive pads) and passivation structure and the fabrication thereof have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect.
The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale and are used for illustration purposes only. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
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.
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.
Further, when a number or a range of numbers is described with “about,” “approximate,” and the like, the term is intended to encompass numbers that are within a reasonable range considering variations that inherently arise during manufacturing as understood by one of ordinary skill in the art. For example, the number or range of numbers encompasses a reasonable range including the number described, such as within +/−10% of the number described, based on known manufacturing tolerances associated with manufacturing a feature having a characteristic associated with the number. For example, a material layer having a thickness of “about 5 nm” can encompass a dimension range from 4.25 nm to 5.75 nm where manufacturing tolerances associated with depositing the material layer are known to be+/−15% by one of ordinary skill in the art. Still further, 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.
In some packaging technologies, a semiconductor chip (or IC chip) is bonded to a package substrate to form a semiconductor device package and the semiconductor device package is then bonded to a printed circuit board (PCB). The semiconductor chip and the package substrate haver different material properties. On the one hand, the semiconductor chip is formed primarily of semiconductor materials (such as silicon, germanium, silicon germanium, or III-V semiconductors), semiconductor oxide (such as silicon oxide), and semiconductor nitride (such as silicon nitride). The package substrate, on the other hand, may be a laminated substrate that includes polymeric materials and metals. For example, the package substrate may be fabricated from, for example, polyimide, a polymer composite laminate, an organic (laminate) material such as bismaleimide-triazine (BT), a polymer-based material such as liquid-crystal polymer (LCP), or the like. The package substrate may also include traces/lines that are formed from suitable conductive materials, such as copper, aluminum, silver, gold, other metals, alloys, combination thereof. As a result, a coefficient of thermal expansion (CTE) of the package substrate may be about greater than a CTE of the IC chip. The semiconductor device package may be subject to elevated temperature, for example, during solder reflow process. When the semiconductor device package is cooled down to room temperature, the package substrate may contract more than the IC chip. The deformation may exert stress on the IC chip, and the stress may concentrate near bottom and corners of the metal lines near the edge of the IC chip, causing cracks in the passivation structure and leading to device (e.g., metal-insulator-metal (MIM) capacitor under the passivation structure) failure.
The present disclosure provides a semiconductor structure having barrel-shape metal lines and methods of making the same to address these issues. In some embodiments, after forming metal-insulator-metal (MIM) capacitor, a first passivation structure is formed over the MIM capacitor. Contact via openings are then formed to penetrate through the first passivation structure to expose conductor plates of the MIM capacitor. A conductive material (including a single layer or multiple layers) may be then deposited over the MIM capacitor. In the present embodiment, a first etching process is performed to etch portions of the conductive material over the first passivation structure to form metal lines, and a second etching process is performed to trim lower portions of the metal lines, thereby forming metal lines having barrel-shaped profiles. Since the barrel-shape metal line can reduce stress buildup in certain areas, the barrel-shape metal line is thus less prone to cracks. As such, the resulting IC chip has better reliability and/or enhanced performance.
The various aspects of the present disclosure will now be described in more detail with reference to the figures. In that regard,
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The workpiece 200 also includes a multi-layer interconnect (MLI) structure 210, which provides interconnections (e.g., wiring) between the various microelectronic components of the workpiece 200. The MLI structure 210 may also be referred to as an interconnect structure 210. The MLI structure 210 may include multiple metal layers or metallization layers. In some instances, the MLI structure 210 may include eight (8) to fourteen (14) metal layers. Each of the metal layers includes multiple conductive components embedded in an intermetal dielectric (IMD) layer. The conductive components may include contacts, vias, or metal lines. The IMD layer may be a silicon oxide or silicon-oxide-containing material where silicon exists in various suitable forms. As an example, the IMD layer includes silicon oxide or a low-k dielectric material having k-value (dielectric constant) smaller than that of silicon oxide, which is about 3.9. In some embodiments, the low-k dielectric material includes tetraethylorthosilicate (TEOS) oxide, un-doped silicate glass, doped silicon oxide such as borophosphosilicate glass (BPSG), fused silica glass (FSG), phosphosilicate glass (PSG), fluorine-doped silicon dioxide, carbon-doped silicon dioxide, porous silicon dioxide, porous carbon-doped silicon dioxide, silicon carbon nitride (SiCN), silicon oxycarbide (SiOCN), spin-on silicon based polymeric dielectrics, combinations thereof, or other suitable materials.
In an embodiment, a carbide layer 220 is deposited on the MLI structure 210. The deposition process includes chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or combinations thereof. Any suitable type of carbide material such as silicon carbide (SiC) can be used in the carbide layer 220.
In an embodiment, an oxide layer 230 is deposited on the carbide layer 220. Any suitable deposition process for the oxide layer 230 may be used, including CVD, flowable CVD (FCVD), spin-on coating, PVD, ALD, or combinations thereof. In an embodiment, the oxide layer 230 includes undoped silicon oxide.
The workpiece 200 also includes a first etch stop layer (ESL) 240 deposited on the oxide layer 230. The first ESL 240 may include silicon carbonitride (SiCN), silicon oxycarbide (SiOC), silicon carbide (SiC), silicon oxycarbonitride (SiOCN), or silicon nitride (SiN), or combinations thereof and may be formed by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or combinations thereof.
The workpiece 200 also includes a dielectric layer 250 deposited on the first ESL 240. A composition of the dielectric layer 250 may be similar to that of the oxide layer 230. In some embodiments, the dielectric layer 250 includes undoped silica glass (USG) or silicon oxide. The dielectric layer 250 may be deposited using CVD, flowable CVD (FCVD), spin-on coating, PVD, ALD, or combinations thereof.
The workpiece 200 also includes a number of lower contact features (e.g., a lower contact feature 253, a lower contact feature 254, and a lower contact feature 255) formed in the dielectric layer 250. The formation of the lower contact features may include patterning of the dielectric layer 250 to form trenches and deposition of a barrier layer (not separately labeled) and a metal fill layer (not separately labeled) in the trenches. In some embodiments, the barrier layer may include titanium nitride or tantalum nitride and may be conformally deposited using PVD, CVD, metalorganic CVD (MOCVD), or a suitable method. In one embodiment, the barrier layer may include tantalum nitride. The metal fill layer may include copper (Cu) and may be deposited using electroplating or electroless plating. After the barrier layer and the metal fill layer are deposited, a planarization process, such as a chemical mechanical planarization (CMP) process, may be performed to remove excess barrier layer and metal fill layer to form the lower contact features 253, 254 and 255. Although the lower contact features 253, 254, and 255 are disposed below upper contact features (such as upper contact features 288M′), the lower contact features 253, 254, and 255 are sometimes referred to as top metal (TM) contacts.
The workpiece 200 also includes a second etch stop layer 256 formed directly on the dielectric layer 250. In an embodiment, the second etch stop layer 256 is deposited on the dielectric layer 250 by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or combinations thereof. The second etch stop layer 256 may include silicon carbonitride (SiCN), silicon nitride (SiN), other suitable materials, or combinations thereof. In the present embodiments, the second etch stop layer 256 is in direct contact with top surfaces of the lower contact features 253, 254, and 255.
The workpiece 200 also includes an oxide layer 258 formed directly on the second etch stop layer 256. In an embodiment, the oxide layer 258 may include undoped silica glass (USG), silicon oxide, or other suitable material(s).
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After the formation of the third conductor plate 270a, the structure of a MIM capacitor 272 is finalized. In embodiments represented in
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While using the patterned mask film 278 as an etch mask, an etching process may be performed to form an opening 280 and an opening 282, as represented in
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After the second etching process 292, as depicted in
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Although not intended to be limiting, one or more embodiments of the present disclosure provide many benefits to a semiconductor structure and the formation thereof. For example, the present disclosure provides barrel-shaped metal lines. In the present embodiments, by barrel-shaped metal lines, stress that would be concentrated at the metal lines may be reduced, and cracks that may be caused by the stress would be advantages reduced, thereby improving the overall performance and reliability of the semiconductor structure and the IC chip.
The present disclosure provides for many different embodiments. Semiconductor structures and methods of fabrication thereof are disclosed herein. In one exemplary aspect, the present disclosure is directed to a method. The method includes receiving a workpiece including a first conductive feature embedded in a dielectric layer, forming a metal-insulator-metal (MIM) capacitor over the dielectric layer, forming a first passivation structure over the MIM capacitor, forming a first contact via opening extending through the first passivation structure and the MIM capacitor to expose the first conductive feature, depositing a conductive material over the workpiece to fill the first contact via opening, performing a first etching process to the conductive material to form a first metal feature, the first metal feature comprising a first portion filling the first contact via opening and a second portion over the first passivation structure, and performing a second etching process to trim the second portion of the first metal feature, and after the second etching process, a shape of a cross-sectional view of the second portion of the first metal feature comprises a barrel shape.
In some embodiments, a bias power of the first etching process may be different than a bias power of the second etching process. In some embodiments, the first etching process and the second etching process implement same etchant, and a flow rate of etchant of the first etching process may be different than a flow rate of etchant of the second etching process. In some embodiments, the second portion of the first metal feature may include a lower sidewall surface and an upper sidewall surface, and the lower sidewall surface and a top surface of the first passivation structure may form an obtuse angle. In some embodiments, the method may also include, before the depositing of the conductive material, conformally depositing a barrier layer over the workpiece, where the first portion of first metal feature further may include a portion of the barrier layer extending along sidewall and bottom surfaces of a portion of the conducive material in the first contact via opening, and the second portion of the first metal feature further may include a portion of the barrier layer disposed on the first passivation structure. In some embodiments, the method may also include, after the performing of the second etching process, forming a second passivation structure over the first metal feature, where a composition of the second passivation structure may be different than a composition of the first passivation structure. In some embodiments, the method may also include, before the performing of the first etching process, depositing an anti-reflective layer on the conducive material, forming a patterned mask film on the anti-reflective layer, and patterning the anti-reflective layer using the patterned mask film as an etch mask, where a top surface of the first metal feature may be spaced apart from the second passivation structure by the anti-reflective layer. In some embodiments, the conducive material may include aluminum (Al) or aluminum copper (Al—Cu), and the anti-reflective layer may include silicon oxynitride (SiON). In some embodiments, the workpiece may also include a second conductive feature embedded in a dielectric layer, and the method may also include forming a second contact via opening extending through the first passivation structure and the MIM capacitor to expose the second conductive feature, and forming a second metal feature, where the second metal feature may include a first portion filling the second contact via opening and a second portion over the first passivation structure, and a shape of cross-sectional view of the second portion of the second metal feature may include a barrel shape.
In another exemplary aspect, the present disclosure is directed to a method. The method includes forming a metal-insulator-metal (MIM) capacitor over a substrate, forming a dielectric layer over the MIM capacitor, forming a conductive pad on the dielectric layer, and forming a passivation structure on the dielectric layer and the conductive pad, where a sidewall surface of the conductive pad includes a lower portion and an upper portion, the lower portion and a bottom surface of the conductive pad forms a first angle, and the upper portion and the bottom surface of the conductive pad forms a second angle, the first angle is different from the second angle, and the first angle is an obtuse angle.
In some embodiments, the forming of the conductive pad may include depositing a barrier layer on a top surface of the dielectric layer, depositing a conductive layer on the barrier layer, etching the conductive layer and the barrier layer to form a conductive feature over the MIM capacitor, and trimming a lower portion of the conductive feature to form the conductive pad. In some embodiments, the etching of the conductive layer and the barrier layer may include implementing an etchant under a first bias power, and the trimming of the lower portion of the conductive feature may include implementing the etchant under a second bias power, the first bias power may be different than the second bias power. In some embodiments, the forming of the conductive pad may include, after the depositing of the conductive layer, forming an anti-reflective layer on the conductive layer, forming a patterned mask film on the anti-reflective layer, patterning the anti-reflective layer using the patterned mask film as an etch mask, where the etching of the conductive layer and the barrier layer may use the patterned anti-reflective layer as an etch mask. In some embodiments, a top surface of the conductive pad may be spaced apart from the passivation structure by the patterned anti-reflective layer. In some embodiments, the forming of the passivation structure may include conformally depositing a first oxide layer over the conductive pad, conformally depositing a first nitride layer over the first oxide layer, forming an oxide liner over the first nitride layer, depositing a second oxide layer over the oxide liner, performing a planarization process to the second oxide layer, and forming a second nitride layer over the second oxide layer. In some embodiments, the second angle may be an acute angle.
In yet another exemplary aspect, the present disclosure is directed to a semiconductor structure. The semiconductor structure includes a lower contact feature in a dielectric layer, a metal-insulator-metal (MIM) capacitor disposed over the dielectric layer and comprising a vertical stack of conductor plates, a first passivation structure disposed over the MIM capacitor, a conductive feature electrically coupled to the lower contact feature, wherein the conductive feature comprises a first portion extending through the first passivation structure and a second portion over the first passivation structure, where, in a cross-sectional view, a shape of the second portion of the conductive feature comprises a substantially barrel shape.
In some embodiments, the conductive feature may include a barrier layer and a conductive fill layer disposed on the barrier layer, where the barrier layer comprises tantalum nitride (TaN), and the conductive fill layer may include aluminum (Al) or aluminum copper (Al—Cu). In some embodiments, a sidewall surface the second portion of the conductive feature may include an upper portion and a lower portion, an angle formed between the lower portion of the sidewall surface and a top surface of the first passivation structure may be between about 95° C. and about 115° C. In some embodiments, the semiconductor structure may also include an anti-reflective layer formed on a top surface of the conductive feature, and a second passivation structure formed on the first passivation structure and the anti-reflective layer.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
This application claims the priority of U.S. Provisional Application Ser. No. 63/411,227 filed Sep. 29, 2022, entitled “Novel Barrel-Shaped AP Profile To Prevent PASS Crack,” the entire disclosure of which is incorporated herein by reference.
Number | Date | Country | |
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63411227 | Sep 2022 | US |