Reverse Selective Deposition

Abstract

Methods for selectively depositing on non-metallic surfaces are disclosed. Some embodiments of the disclosure utilize a blocking compound to form a blocking layer on metallic surfaces. Deposition is performed to selectively deposit on the unblocked non-metallic surfaces. Some embodiments of the disclosure relate to methods of forming metallic vias with decreased resistance. Some embodiments utilize an unsaturated hydrocarbon as a blocking compound. Some embodiments utilize a triazole as a blocking compound.

Description

TECHNICAL FIELD

Embodiments of the disclosure generally relate to methods of reverse selective deposition. More particularly, some embodiments of the disclosure are directed to methods of selective deposition on non-metallic surfaces using blocking compounds comprising a triazole. More particularly, some embodiments of the disclosure are directed to methods of selective deposition on non-metallic surfaces using blocking compounds comprising an unsaturated hydrocarbon.

BACKGROUND

In middle of the line (MOL) and back end of the line (BEOL) structures, barrier films are typically used between metal lines and dielectric layers to prevent diffusion and other adverse interactions between the dielectric and the metal lines. Yet the largest contribution to via resistance is mainly due to barrier films with high resistivity.

Current approaches have focused on reducing the barrier film thickness or finding barrier films with lower resistivity to decrease via resistance. However, increased via resistance as a result of barrier films remains an issue.

One novel approach has been to block or decrease the thickness of the barrier film on the metal surface at the bottom of the via while the thickness on the dielectric surface at the sidewalls remains. Since the barrier properties of the barrier film are required between the metal and the dielectric, this approach allows for the barrier film to remain intact, but the reduced thickness on the metal surface improves via resistance. These processes are referred to as selective deposition processes.

Selective deposition of materials can be accomplished in a variety of ways. A chemical precursor may react selectively with one surface relative to another surface (metallic or dielectric). Process parameters such as pressure, substrate temperature, precursor partial pressures, and/or gas flows might be modulated to modulate the chemical kinetics of a particular surface reaction. Another possible scheme involves surface pretreatments that can be used to activate or deactivate a surface of interest to an incoming film deposition precursor.

Accordingly, methods which allow for selective deposition on non-metallic (e.g. dielectric) surfaces are needed.

SUMMARY

One or more embodiments of the disclosure are directed to a method of forming a blocking layer. The method comprises exposing a substrate to a blocking compound to selectively form a blocking layer on a first surface over a second surface. The substrate comprises a metallic material having the first surface and a non-metallic material having the second surface

Additional embodiments of this disclosure relate to a method of selective deposition. The method comprises exposing a substrate comprising a metallic material having a first surface and a non-metallic material having a second surface to a triazole to selectively form a blocking layer on the first surface over the second surface. The substrate is sequentially exposed to a metal precursor and a reactant to form a film on the second surface over the blocking layer on the first surface. The blocking layer is removed from the first surface.

Further embodiments of this disclosure relate to a method of forming low-resistance metal vias. The method comprises providing a substrate having a substrate surface with at least one feature formed therein. The at least one feature has a sidewall and a bottom. The sidewall comprises a non-metallic material surface. The bottom comprises a metallic material surface. The substrate is exposed to a triazole to selectively form a blocking layer on the metallic material surface over the non-metallic material surface. The substrate is sequentially exposed to a metal precursor and a reactant to form a film on the non-metallic material surface over the blocking layer on the metallic material surface. The blocking layer is optionally removed from the metallic material surface. A conductive fill material is deposited within the at least one feature to form a low-resistance metal via.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

FIG. 1 illustrates a cross-sectional view of an exemplary substrate during processing according to one or more embodiment of the disclosure; and

FIG. 2 illustrates a cross-sectional view of an exemplary substrate during processing according to one or more embodiment of the disclosure.

In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it is to be understood that the disclosure is not limited to the details of construction or process steps set forth in the following description. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways.

As used in this specification and the appended claims, the term “substrate” refers to a surface, or portion of a surface, upon which a process acts. It will also be understood by those skilled in the art that reference to a substrate can also refer to only a portion of the substrate, unless the context clearly indicates otherwise. Additionally, reference to depositing on a substrate can mean both a bare substrate and a substrate with one or more films or features deposited or formed thereon

A “substrate” as used herein, refers to any substrate or material surface formed on a substrate upon which film processing is performed during a fabrication process. For example, a substrate surface on which processing can be performed include materials such as silicon, silicon oxide, strained silicon, silicon on insulator (SOI), carbon doped silicon oxides, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, without limitation, semiconductor wafers. Substrates may be exposed to a pretreatment process to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and/or bake the substrate surface. In addition to film processing directly on the surface of the substrate itself, in the present disclosure, any of the film processing steps disclosed may also be performed on an underlayer formed on the substrate as disclosed in more detail below, and the term “substrate surface” is intended to include such underlayer as the context indicates. Thus for example, where a film/layer or partial film/layer has been deposited onto a substrate surface, the exposed surface of the newly deposited film/layer becomes the substrate surface.

Embodiments of the present disclosure relate to methods for selectively forming a blocking layer on a metallic material surface. Some embodiments of the present disclosure further relate to methods for selectively depositing a film on a non-metallic material surface over a metallic material surface. Some embodiments of the present disclosure further relate to methods for forming metal vias with lower resistance.

Some embodiments of the disclosure advantageously provide methods for selectively forming a blocking layer on a metallic material surface.

As used in this specification and the appended claims, the phase “metallic material surface” or “non-metallic material surface” refers to the surface of a metallic or non-metallic material, respectively. In some embodiments, the non-metallic material is a dielectric material.

As used in this specification and the appended claims, the term “selectively depositing on a first surface over a second surface”, and the like, means that a first amount or thickness is deposited on the first surface and a second amount or thickness is deposited on the second surface, where the second amount or thickness is less than the first amount or thickness, or, in some embodiments, no amount is deposited on the second surface.

As used in this regard, the term “over” does not imply a physical orientation of one surface on top of another surface, rather a relationship of the thermodynamic or kinetic properties of the chemical reaction with one surface relative to the other surface. For example, selectively depositing a cobalt film onto a copper surface over a dielectric surface means that the cobalt film deposits on the copper surface and less or no cobalt film deposits on the dielectric surface; or that the formation of the cobalt film on the copper surface is thermodynamically or kinetically favorable relative to the formation of a cobalt film on the dielectric surface.

In some embodiments, “selectively” means that the subject material forms on the selected surface at a rate greater than or equal to about 2×, 3×, 4×, 5×, 7×, 10×, 15×, 20×, 25×, 30×, 35×, 40×, 45× or 50× the rate of formation on the non-selected surface. Stated differently, the selectivity of the stated process for the selected surface relative to the non-selected surface is greater than or equal to about 2:1, 3:1, 4:1, 5:1, 7:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1 or 50:1.

One or more embodiments of this disclosure are directed to methods of selectively forming a blocking layer on a first surface of a substrate over a second surface. The substrate comprises a metallic material with a first surface and a non-metallic material with a second surface. In some embodiments, the first surface may be described as a metallic material surface and the second surface may be described as a non-metallic material surface.

The metallic material of the substrate may be any suitable metallic material. In some embodiments, the metallic materials of this disclosure are conductive materials. Suitable metallic materials include, but are not limited to, metals, metal nitrides, some metal oxides, metal alloys, silicon, combinations thereof and other conductive materials.

In some embodiments, the metallic material comprises chromium, manganese, iron, copper, nickel, cobalt, tungsten, ruthenium, molybdenum, tantalum, titanium or combinations thereof. In some embodiments, the metallic material consists essentially of chromium, manganese, iron, copper, nickel, cobalt, tungsten, ruthenium, molybdenum, tantalum oxide, tantalum nitride, titanium oxide or titanium nitride. In some embodiments, the metallic material consists essentially of one or more of copper, cobalt, ruthenium, tungsten and molybdenum. In some embodiments, the metallic material comprises or consists essentially of silicon. As used in this specification and the appended claims, the term “consists essentially of” means that the material is greater than or equal to about 95%, 98% or 99% of the stated material on an atomic basis.

As used in this specification and the appended claims, the term “oxide” or the like means that the material contains the specified element(s). The term should not be interpreted to imply a specific ratio of elements. Accordingly, an “oxide” or the like may comprise a stoichiometric ratio of elements or a non-stoichiometric ratio of elements.

The non-metallic material of the substrate may be any suitable material. In some embodiments, the non-metallic materials of this disclosure are dielectric materials. Suitable non-metallic materials include, but are not limited to, silicon oxides (e.g. SiO₂), silicon nitrides, silicon carbides and combinations thereof (e.g. SiCON). In some embodiments, the non-metallic material consists essentially of silicon dioxide (SiO₂). In some embodiments, the non-metallic material comprises silicon nitride. In some embodiments, the non-metallic material consists essentially of silicon nitride.

Referring to FIG. 1, an exemplary method 100 begins with a substrate 105 comprising a metallic material 110 having a first surface 112 and a non-metallic material 120 having a second surface 122. The substrate 105 is exposed to a blocking compound (not shown) to selectively form a blocking layer 130 on the first surface 112 over the second surface 122. In some embodiments, the surface of the blocking layer is described as a blocked first surface 132.

In some embodiments, the first surface 112 is cleaned prior to exposure to the blocking compound. The first surface may be cleaned by any suitable method including, but not limited to, a hydrogen thermal anneal, an ethanol clean, or a plasma hydrogen clean.

In some embodiments, the blocking compound comprises an unsaturated hydrocarbon. Without being bound by theory, it is believed that the d orbitals of the metallic materials start to share electrons with the sp² orbitals of the unsaturated hydrocarbon.

Accordingly, in some embodiments, the unsaturated hydrocarbon comprises at least one compound with at least one double bond between two carbon atoms. Stated differently, in some embodiments, the unsaturated hydrocarbon comprises at least one compound with a general formula of R′═R″. In some embodiments, the unsaturated hydrocarbon comprises at least one compound with at least one triple bond between two carbon atoms. Stated differently, in some embodiments, the unsaturated hydrocarbon comprises at least one compound with a general formula of R′≡R″.

In some embodiments, the compound of the unsaturated hydrocarbon contains only one unsaturated bond. Without being bound by theory, it is believed that multiple unsaturated bonds increases the likelihood of polymerization and increases the difficulty of removing the blocking layer without damaging the surrounding substrate materials.

Further, without being bound by theory, it is believed that the unsaturated hydrocarbon suppresses both the nucleation and growth rate of films on the metallic material surface.

In some embodiments, R′ and R″ are identical. In some embodiments, R′ and R″ are independent C2-C6 groups. As used in this regard, a “C2-C6 group” contains 2-6 carbon atoms. In some embodiments, R′ and R″ comprise only carbon and hydrogen atoms. In some embodiments, R′ and R″ do not comprises any surface reactive moieties. In some embodiments, the compound of the unsaturated hydrocarbon does not contain an unsaturated bond on the terminal carbon. In some embodiments, the compound of the unsaturated hydrocarbon comprises 4-12 carbon atoms. In some embodiments, R′ and/or R″ are linear. In some embodiments, R′ and/or R″ are branched.

In some embodiments, the unsaturated hydrocarbon comprises at least one compound with a general formula of R′≡R″, an alkyne. In some embodiments, the compound of the unsaturated hydrocarbon comprises or consists essentially of one or more of 3-hexyne, 4-octyne, 5-decyne, 6-dodecyne and 7-tetradecyne.

In some embodiments of the alkyne, the triple bond attaches to a terminal carbon. Stated differently, in some embodiments, R′ or R″ is a C1 group. In some embodiments, when R′ is a C1 group, R″ is a C3-C18 group. In some embodiments, the unsaturated hydrocarbon comprises or consists essentially of one or more of 1-heptyne, 1-octyne, 1-nonyne, 1-decyne, 1-undecyne, 1-dodecyne, and 1-tetradecyne.

In some embodiments, the blocking compound comprises a triazole. In some embodiments, the blocking compound comprises one or more of 1,2,3-triazole, 1,2,4-triazole, benzotriazole, alkyl substituted 1,2,3-triazoles and alkyl substituted benzotriazoles. As used in this specification and the appended claims, an alkyl substitution may include substitution with a C1-C4 alkyl group. The alkyl group may be linear or branched. In some embodiments, the blocking compound consists essentially of benzotriazole.

In some embodiments, the processing conditions for exposing the substrate to the blocking compound may be controlled. In some embodiments, the substrate is soaked in a vapor of the blocking compound.

In some embodiments, the pressure of the processing chamber is controlled. The pressure of the processing chamber may be any suitable pressure for forming the blocking layer. In some embodiments, the pressure of the processing chamber is maintained at less than or equal to about 80 Torr, less than or equal to about 70 Torr, less than or equal to about 60 Torr, less than or equal to about 50 Torr, less than or equal to about 40 Torr, less than or equal to about 30 Torr, less than or equal to about 20 Torr, less than or equal to about 15 Torr, less than or equal to about 10 Torr, or less than or equal to about 5 Torr. In some embodiments, the pressure of the processing chamber is maintained at about 10 Torr, about 20 Torr, about 30 Torr, about 40 Torr, or about 50 Torr.

In some embodiments, the flow rate of the blocking compound is controlled. The flow rate of the blocking compound may be any suitable flow rate for forming the blocking layer. In some embodiments, the flow rate of the blocking compound is in a range of about 50 sccm to about 100 sccm, or in a range of about 75 sccm to about 100 sccm. In some embodiments, the flow rate of the blocking compound is less than or equal to about 600 sccm, less than or equal to about 500 sccm, less than or equal to about 400 sccm, less than or equal to about 300 sccm, less than or equal to about 250 sccm, less than or equal to about 200 sccm, less than or equal to about 150 sccm, less than or equal to about 100 sccm, less than or equal to about 75 sccm, or less than or equal to about 50 sccm. In some embodiments, the flow rate of the blocking compound is about 50 sccm or about 100 sccm.

In some embodiments, the soak period, during which the blocking compound is exposed to the substrate, is controlled. The soak period may be any suitable period for forming the blocking layer. In some embodiments, the soak period is greater than or equal to about 10 s, greater than or equal to about 20 s, greater than or equal to about 30 s, greater than or equal to about 45 s, greater than or equal to about 60 s, greater than or equal to about 80 s, greater than or equal to about 120 s, greater than or equal to about 150 s, or greater than or equal to about 200 s. In some embodiments, the soak period is about 60 s. In some embodiments, the soak period is about 200 s.

In some embodiments, the temperature of the substrate is controlled during exposure to the blocking compound. In some embodiments, the temperature of the substrate is less than or equal to about 400° C., less than or equal to about 380° C., less than or equal to about 350° C., less than or equal to about 300° C., less than or equal to about 275° C., less than or equal to about 250° C., less than or equal to about 225° C., or less than or equal to about 200° C. In some embodiments, the temperature of the substrate is in a range of about 20° C. to about 380° C. or in a range of about 50° C. to about 400° C.

In some embodiments, the compound of the blocking compound is a liquid at the operating temperature. In some embodiments, the blocking compound has a vapor pressure greater than or equal to about 0.1 Torr at the exposure temperature.

In some embodiments, the method 100 continues with the deposition of a film 115 on the second surface 122 over the blocked first surface 132 (see FIG. 1C). The film 115 may be deposited by any known method.

In some embodiments, the film 115 is deposited by atomic layer deposition. In some embodiments, the film 115 is deposited by sequentially exposing the substrate 105 to a metal precursor and a reactant. In some embodiments, the film 115 comprises a metal nitride. In some embodiments, the film 115 comprises a metal oxide. In some embodiments, the film 115 comprises one or more of silicon, aluminum, titanium, tantalum, hafnium and zirconium.

In some embodiments, the film 115 functions as a barrier film, barrier layer or diffusion layer. In some embodiments, the film 115 comprises titanium nitride. In some embodiments, the film 115 comprises tantalum nitride. In some embodiments, the film 115 comprises aluminum oxide. In some embodiments, the film is formed without the use of plasma.

In some embodiments, the film 115 is deposited at a temperature which does not impact the stability of the blocking layer 130. In some embodiments, the film 115 is deposited at a temperature in a range of about 100° C. to about 380° C. or in a range of about 100° C. to about 400° C.

In some embodiments, the substrate is exposed to the blocking compound between ALD cycles. In some embodiments, the substrate may be re-exposed to the blocking compound after each deposition cycle. In some embodiments, the substrate may be re-exposed to the blocking compound after several deposition cycles.

In some embodiments, the method continues by removing the blocking layer 130 from the first surface 112. The blocking layer may be removed by any suitable means, including but not limited to, plasma cleaning processes or thermal decomposition.

In some embodiments, the substrate is exposed to a plasma to remove the blocking layer 130 from the first surface 112. In some embodiments, the plasma comprises argon (Ar), nitrogen (N₂) or hydrogen (H₂). In some embodiments, the plasma consists essentially of argon. In some embodiments, the plasma comprises a mixture of H₂/Ar. In some embodiments, the mixture of H₂/Ar is about 1:1.

The power of the plasma may be varied depending on the composition and thickness of the blocking layer and the surrounding materials. In some embodiments, the plasma power is in a range of about 50 W to about 500 W, in a range of about 100 W to about 450 W, or in a range of about 200 W to about 400W. In some embodiments, the plasma power is about 50 W, about 200 W or about 400 W.

The duration of the plasma exposure may be varied depending on the composition and thickness of the blocking layer and the surrounding materials. In some embodiments, the substrate is exposed to the plasma for a period in a range of about 2 s to about 60 s, in a range of about 3 s to about 30 s, or in a range of about 5 s to about 10 s. In some embodiments, the substrate is exposed to the plasma for a period of about 3 s, about 5 s, about 10 s or about 30 s.

In some embodiments, the substrate is exposed to an elevated temperature to remove the blocking layer 130 from the first surface 112. In some embodiments, the elevated temperature is greater than or equal to about 300° C., greater than or equal to about 320° C., greater than or equal to about 325° C., greater than or equal to about 330° C., greater than or equal to about 350° C., greater than or equal to about 380° C., or greater than or equal to about 400° C.

Referring to FIG. 2, an exemplary method 200 begins by providing a substrate 210 having a substrate surface 205 with at least one feature 220 formed therein. The at least one feature 220 has sidewalls 222, 224 and a bottom 228. The sidewalls 222, 224 comprise a non-metallic material 230 surface. The bottom 228 comprises a metallic material 240 surface.

The method 200 continues by exposing the substrate 210 to a blocking compound (not shown) to selectively form a blocking layer 250 on the metallic material 240 surface on the bottom 228 of the feature 220 over the non-metallic material 230 surface on the sidewalls 222, 224.

The method 200 continues by depositing a film 260 on the non-metallic material 230 surface on the sidewalls 222, 224 of the feature 220 over the blocking layer 250. In some embodiments, the film 260 is deposited by sequentially exposing the substrate 210 to a metal precursor and a reactant.

The method 200 includes optionally removing the blocking layer 250 from the metallic material 240 surface on the bottom 228 of the feature 220. FIG. 2 shows the substrate 210 after the blocking layer 250 is removed according to some embodiments.

Without being bound by theory, it is believed that the blocking layer increases the resistance of the metal via only marginally when compared to the increase in resistance typically seen with most barrier layers (e.g. film 260). Accordingly, the removal of the blocking layer is an optional process which may further decrease the resistance of the metal via.

Referring to FIG. 2, the method 200 continues by depositing a conductive fill material 270 within the at least one feature 220 to form a low-resistance metal via. In some embodiments, the low-resistance metal via has a resistance less than or equal to about 80% of a metal via formed without the blocking layer. Stated differently, the low-resistance metal vias formed by the disclosed process including the blocking layer 250 provide a via resistance reduction of greater than or equal to about 20%.

Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

Although the disclosure herein has been described with reference to particular embodiments, those skilled in the art will understand that the embodiments described are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present disclosure without departing from the spirit and scope of the disclosure. Thus, the present disclosure can include modifications and variations that are within the scope of the appended claims and their equivalents.

Claims

1. A method of forming a blocking layer, the method comprising exposing a substrate comprising a metallic material having a first surface and a non-metallic material having a second surface to a blocking compound to selectively form a blocking layer on the first surface over the second surface, wherein the blocking compound comprises a triazole.

2. The method of claim 1, wherein the blocking compound further comprises an unsaturated hydrocarbon with a general formula R′≡R″.

3. The method of claim 2, wherein the unsaturated hydrocarbon contains only one triple bond.

4. The method of claim 3, wherein the unsaturated hydrocarbon comprises 3-hexyne.

5. The method of claim 2, wherein R′ is a C1 group.

6. The method of claim 5, wherein R″ is a C3-C18 group.

7. The method of claim 1, wherein the triazole comprises one or more of 1,2,3-triazole, 1,2,4-triazole, benzotriazole, an alkyl substituted 1,2,3-triazole and an alkyl substituted benzotriazole.

8. The method of claim 7, wherein the triazole consists essentially of benzotriazole.

9. The method of claim 1, wherein the metallic material comprises one or more of copper, cobalt, tungsten, molybdenum or ruthenium.

10. The method of claim 1, wherein the non-metallic material comprises silicon oxide.

11. The method of claim 1, further comprising selectively depositing a film on the second surface over the blocked first surface.

12. The method of claim 10, wherein the film is deposited by sequentially exposing the substrate to a metal precursor and a reactant.

13. The method of claim 1, further comprising exposing the substrate to an elevated temperature to remove the blocking layer.

14. The method of claim 13, wherein the elevated temperature is greater than or equal to about 330° C.

15. A method of selective deposition, the method comprising: exposing a substrate comprising a metallic material having a first surface and a non-metallic material having a second surface to a triazole to selectively form a blocking layer on the first surface over the second surface; andsequentially exposing the substrate to a metal precursor and a reactant to form a film on the second surface over the blocking layer on the first surface; andremoving the blocking layer from the first surface.

16. The method of claim 15, wherein the triazole comprises benzotriazole.

17. A method of forming low-resistance metal vias, the method comprising: providing a substrate having a substrate surface with at least one feature formed therein, the at least one feature having a sidewall and a bottom, the sidewall comprising a non-metallic material surface, the bottom comprising a metallic material surface;exposing the substrate to a triazole to selectively form a blocking layer on the metallic material surface over the non-metallic material surface;sequentially exposing the substrate to a metal precursor and a reactant to form a film on the non-metallic material surface over the blocking layer on the metallic material surface;optionally removing the blocking layer from the metallic material surface; anddepositing a conductive fill material within the at least one feature to form a low-resistance metal via.

18. The method of claim 17, wherein the triazole comprises benzotriazole.

19. The method of claim 17, wherein the film comprises aluminum oxide.

20. The method of claim 17, wherein the low-resistance metal via has a resistance less than or equal to about 80% of a metal via formed without a blocking layer.