Tungsten gap filling with hydrogen plasma processing

Abstract

Embodiments of methods and associated apparatus for filling features in a silicon-containing dielectric layer of a substrate are provided herein. In some embodiments, a method of filling a feature in a silicon-containing dielectric layer of a substrate includes depositing a discontinuous liner layer in the feature via a physical vapor deposition (PVD) process in a first processing chamber; performing a hydrogen plasma process in the second processing chamber to form silicon-hydrogen bonds on a surface of the feature that is not covered by the discontinuous liner layer; and depositing a bulk tungsten layer on the discontinuous liner layer and over the silicon-hydrogen bonds in the third processing chamber to fill the features with tungsten.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to processing of substrates. Background Art

[0002] Integrated circuits are formed by processes that produce intricately patterned layers of material on a substrate surface. Tungsten is used in the semiconductor industry as a relatively low resistivity conductor with minimal electromigration. Tungsten can be used to fill features as contacts for transistors and to form vias between layers of integrated devices. Tungsten can also be used for interconnects in logic and memory devices due to its stability and low resistivity. However, conventional tungsten metal gapfill processes can be prone to voids during gapfill due to early pinch-off at overhangs.

[0003] Accordingly, the inventors provide embodiments of an improved process that facilitates void-free tungsten gapfill. Summary of the invention

[0004] Embodiments of methods and associated apparatus for filling features in a silicon-containing dielectric layer of a substrate are provided herein. In some embodiments, the method of filling features in a silicon-containing dielectric layer of a substrate includes: depositing a non-continuous liner layer in the feature via a physical vapor deposition (PVD) process in a first processing chamber; performing a hydrogen plasma process in a second processing chamber to form silicon-hydrogen bonds on surfaces of the feature not covered by the non-continuous liner layer; and depositing a bulk tungsten layer on the non-continuous liner layer and over the silicon-hydrogen bonds in a third processing chamber to fill the feature with tungsten.

[0005] In some embodiments, a method of filling a feature in a silicon-containing dielectric layer of a substrate includes: depositing a non-continuous liner layer in the feature via a physical vapor deposition (PVD) process in a first processing chamber; performing a hydrogen plasma process in a second processing chamber to form silicon-hydrogen bonds on a surface of the feature not covered by the non-continuous liner layer; and depositing a bulk tungsten layer on the non-continuous liner layer and over the silicon-hydrogen bonds without a nucleation layer via an atomic layer deposition (ALD) process in a third processing chamber to fill the feature with tungsten.

[0006] In some embodiments, a non-transitory computer readable medium includes one or more processors that, when executed, perform a method of filling a feature in a silicon-containing dielectric layer of a substrate, the method comprising: depositing a non-continuous liner layer in the feature via a physical vapor deposition (PVD) process in a first processing chamber; performing a hydrogen plasma process in a second processing chamber to form silicon-hydrogen bonds on a surface of the feature not covered by the non-continuous liner layer; and depositing a bulk tungsten layer on the non-continuous liner layer and over the silicon-hydrogen bonds in a third processing chamber to fill the feature with tungsten.

[0007] Other and further embodiments of the disclosure are described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The embodiments of the present disclosure, briefly summarized above and discussed in more detail below, can be understood by reference to the illustrative embodiments of the present disclosure depicted in the accompanying drawings. However, the drawings illustrate only typical embodiments of the present disclosure and are therefore not to be considered limiting in scope, as the present disclosure may admit to other equally effective embodiments.

[0009] Figure 1 A flow chart of a method of filling features in a silicon-containing dielectric layer of a substrate is depicted in accordance with at least some embodiments of the present disclosure.

[0010] Figure 2 Depicted is a cross-sectional side view of a portion of a substrate having a non-continuous liner layer deposited in a feature, in accordance with at least some embodiments of the present disclosure.

[0011] Figure 3 Depicted is a cross-sectional side view of a portion of a substrate after performing a hydrogen plasma treatment in accordance with at least some embodiments of the present disclosure.

[0012] Figure 4 Depicted is a cross-sectional side view of a portion of a substrate after deposition of a bulk tungsten layer, in accordance with at least some embodiments of the present disclosure.

[0013] Figure 5 A multi-chamber processing tool in accordance with at least some embodiments of the present disclosure is depicted.

[0014] For ease of understanding, the same reference numerals are used as much as possible to represent the same components common to the figures. The figures are not drawn to scale and may be simplified for clarity. Components and features of one embodiment may be beneficially incorporated into other embodiments without further description. DETAILED DESCRIPTION

[0015] The methods and apparatus described herein provide tungsten gap filling with no voids or substantially no voids in a substrate. The embodiments provided herein can be used to fill features formed in a substrate, such as vias, trenches, etc. Due to the unique stability and low resistivity of tungsten, tungsten is widely used as metal interconnects in logic and memory devices. However, with technological advances and smaller feature sizes, the demand for metal filling solutions with no voids or substantially no voids is increasing. Traditionally, a nucleation layer is deposited in the feature before the bulk tungsten filling process to achieve an effective tungsten bulk filling process with reduced voids or no voids. However, the nucleation layer is a high resistance film, which leads to a significantly higher level of stack resistivity. Higher stack resistivity leads to increased power consumption and reduced device performance. Therefore, the method provided herein involves performing a hydrogen plasma treatment before the bulk tungsten filling process to advantageously provide good gap filling in the feature without a nucleation layer in the feature.

[0016] Figure 1 A flow chart of a method 100 of filling a feature (e.g., feature 204) in a substrate (e.g., substrate 202) according to at least some embodiments of the present disclosure is depicted. At step 102, method 100 includes depositing a non-continuous liner layer (e.g., non-continuous liner layer 208) in the feature via a physical vapor deposition (PVD) process in a first processing chamber (e.g., one of processing chambers 514A to 514D). The feature is typically formed in a silicon-containing dielectric layer of the substrate. Figure 2 Depicted is a cross-sectional side view of a portion of a substrate 202 having a non-continuous liner layer 208 deposited in a feature 204, in accordance with at least some embodiments of the present disclosure. In some embodiments, the feature has a critical dimension of about 20 nanometers or less.

[0017] The feature 204 may be a via, a trench, etc. formed in the substrate 202. The feature 204 may extend from the field region 210 or the upper surface of the substrate 202 into the substrate 202. The feature 204 may include a bottom surface 212 and a sidewall 206 extending from the bottom surface 212 to the field region 210. In some embodiments, the non-continuous liner layer 208 includes or consists essentially of (e.g., greater than or equal to 95%) titanium nitride (TiN) or tungsten.

[0018] In some embodiments, the PVD process is performed at a temperature of about 200 to about 500 degrees Celsius. In some embodiments, the PVD process is performed at a chamber pressure of about 0.1 to about 10 mTorr. The non-continuous liner layer 208 generally covers at least a portion of the bottom surface 212 of the feature 204 and a portion of the sidewall 206 of the feature 204. The non-continuous liner layer 208 may also be deposited on the field region (e.g., field region 210) of the substrate 202 and form an overhang region 312 near the front opening 316 of the feature 204. The non-continuous nature of the non-continuous liner layer 208 provides a poor bottom layer for subsequent bulk fill of the feature 204.

[0019] At step 104, the method 100 includes performing a hydrogen plasma treatment in a second processing chamber (e.g., one of the processing chambers 514A-514D) to form silicon-hydrogen bonds (e.g., silicon-hydrogen bonds 330) on surfaces of the features not covered by the discontinuous liner layer. The hydrogen plasma treatment advantageously overcomes the problem of the discontinuous liner layer 208 by providing a substantially continuous bottom layer along the surfaces of the features including silicon-hydrogen bonds and the discontinuous liner layer 208 for bulk fill processing. In some embodiments, the hydrogen plasma treatment is performed in a capacitively coupled plasma (CCP) chamber. In some embodiments, the hydrogen plasma treatment is performed at a temperature of about 200 to about 500 degrees Celsius.

[0020] The hydrogen plasma treatment is performed using a plasma comprising hydrogen ions (e.g., hydrogen ions 310). In some embodiments, the plasma comprises hydrogen ions and argon ions (e.g., argon ions 320). In some embodiments, the amount of hydrogen plasma in the plasma is greater than the amount of argon ions in the plasma. In some embodiments, the ratio between hydrogen ions and argon ions is from about 4:1 to about 50:1. For example, in some embodiments, the ratio between hydrogen ions and argon ions is from about 35:1 to about 50:1. In some embodiments, the ratio between hydrogen ions and argon ions is from about 8:1 to about 12:1. In some embodiments, the chamber pressure during the hydrogen plasma treatment is greater than about 100 mTorr. For example, in some embodiments, the chamber pressure during the hydrogen plasma treatment is from about 0.3 to about 11 Torr. In some embodiments, the chamber pressure during the hydrogen plasma treatment is from about 0.3 to about 1.8 Torr. In some embodiments, the chamber pressure during the hydrogen plasma treatment is from about 9 to about 11 Torr. In some embodiments, the hydrogen plasma treatment is performed for about 90 to about 250 seconds.

[0021] Figure 3A cross-sectional side view of a portion of substrate 202 after performing a hydrogen plasma treatment according to at least some embodiments of the present disclosure is depicted. Hydrogen plasma treatment includes exposing substrate 202 and discontinuous liner layer 208 to plasma 302. In some embodiments, plasma 302 includes hydrogen ions 310 for bonding with exposed silicon on surfaces of features 204 not covered by discontinuous liner layer 208. Hydrogen ions 310 combine with silicon in substrate 202 to form silicon-hydrogen bonds 330. In some embodiments, plasma 302 includes argon ions 320 combined with hydrogen ions 310 to help stabilize plasma 302.

[0022] At step 106, method 100 includes depositing a bulk tungsten layer consisting essentially of tungsten (e.g., bulk tungsten layer 410) on the non-continuous liner layer and over the silicon-hydrogen bonds in a third processing chamber (e.g., one of processing chambers 514A to 514D) to fill the features with tungsten. In some embodiments, consisting essentially of tungsten is greater than or equal to 95% tungsten. The bulk tungsten is typically deposited via a suitable deposition process in an atomic layer deposition (ALD) chamber or a chemical vapor deposition (CVD) chamber. In some embodiments, the CVD process or the ALD process is performed at a temperature of about 200 to about 500 degrees Celsius. In some embodiments, no etching process is performed between the PVD deposition process of step 102 and the bulk tungsten deposition process of step 106. The hydrogen plasma process is typically performed at a chamber pressure that is greater than the chamber pressure during each of the PVD deposition of step 102 or the ALD / CVD deposition of step 106.

[0023] Figure 4 A cross-sectional side view of a portion of substrate 202 after depositing bulk tungsten layer 410 according to at least some embodiments of the present disclosure is depicted. Silicon-hydrogen bonds 330 formed at step 104 act as soaks at bottom surface 212 and sidewalls 206 of feature 204 for ALD / CVD growth of bulk tungsten layer 410 without any nucleation layer. Bulk tungsten layer 410 fills feature 204 with no voids or substantially no voids. In some embodiments, method 100 includes performing a planarization process, such as chemical mechanical planarization, of bulk tungsten layer 410 after depositing the bulk tungsten layer to planarize bulk tungsten layer 410.

[0024] In some embodiments, the method 100 is performed in a multi-chamber processing tool (e.g., the multi-chamber processing tool 500) without a vacuum break between the first processing chamber, the second processing chamber, and the third processing chamber. Figure 5A multi-chamber processing tool 500 is depicted in accordance with at least some embodiments of the present disclosure. The multi-chamber processing tool 500 may be adapted to perform the methods of the present disclosure. The methods described herein may be practiced using other multi-chamber processing tools having suitable processing chambers coupled thereto, or in other suitable processing chambers. For example, in some embodiments, the inventive methods discussed above may be advantageously performed in a multi-chamber processing tool such that there are very limited or no vacuum breaks between processing steps. For example, the absence of vacuum breaks may limit or prevent contamination of any substrate being processed in the multi-chamber processing tool.

[0025] The multi-chamber processing tool 500 generally includes a vacuum-sealed processing platform 501, a factory interface 504, and a system controller 502. The processing platform 501 includes a plurality of processing chambers, such as 514A, 514B, 514C, and 514D, operably coupled to a transfer chamber 503 under vacuum. In some embodiments, the first processing chamber may be processing chamber 514A, the second processing chamber may be 514B, and the third processing chamber may be processing chamber 514C. In some embodiments, the multi-chamber processing tool 500 may include a plurality of transfer chambers 503 in fluid communication with each other to accommodate a greater number of processing chambers in a vacuum-sealed environment. The factory interface 504 is coupled to the system controller 502 via one or more load lock chambers (e.g., Figure 5 506A and 506B) shown in FIG. 5 are selectively operably coupled to the transfer chamber 503.

[0026] In some embodiments, the factory interface 504 includes at least one docking station 507 and at least one factory interface robot 538 to facilitate transfer of substrates 521, such as substrate 202. The at least one docking station 507 is configured to accept one or more front opening unification units (FOUPs). Figure 5 505A, 505B, 505C, and 505D are shown. At least one factory interface robot 538 is configured to transfer a substrate 521 from the factory interface 504 to the processing platform 501 via a load lock chamber 506A, 506B. Each of the load lock chambers 506A and 506B has a first port coupled to the factory interface 504 and a second port coupled to the transfer chamber 503. The load lock chambers 506A and 506B are coupled to a pressure control system (not shown) that pumps and exhausts the load lock chambers 506A and 506B to facilitate the passage of substrates between the vacuum environment of the transfer chamber 503 and the substantially ambient (e.g., atmospheric) environment of the factory interface 504.

[0027] The transfer chamber 503 has a vacuum robot 542 disposed therein. The vacuum robot 542 is capable of transferring substrates 521 between the load lock chambers 506A and 506B and the plurality of processing chambers 514A, 514B, 514C, and 514D. In some embodiments, the vacuum robot 542 includes one or more upper arms that can rotate about corresponding shoulder axes. In some embodiments, the one or more upper arms are coupled to corresponding forearms and wrist members so that the vacuum robot 542 can extend into and retract from any processing chamber coupled to the transfer chamber 503.

[0028] A plurality of processing chambers 514A, 514B, 514C, and 514D are coupled to the transfer chamber 503. Each of the plurality of processing chambers 514A, 514B, 514C, and 514D may include a suitable processing chamber for substrate processing, such as a chemical vapor deposition (CVD) chamber, an atomic layer deposition (ALD) chamber, a physical vapor deposition (PVD) chamber, a plasma enhanced atomic layer deposition (PEALD) chamber, an etching chamber (i.e., a dry etching chamber), a pre-cleaning / annealing chamber, etc. In some embodiments, the plurality of processing chambers 514A, 514B, 514C, and 514D include at least one PVD chamber configured to deposit the non-continuous liner layer 208 and at least one ALD or CVD chamber configured to deposit the bulk tungsten layer 410.

[0029] The system controller 502 controls the operation of the multi-chamber processing tool 500 using direct control of the processing chambers 514A, 514B, 514C, and 514D or alternatively by controlling a computer (or controller) associated with the processing chambers 514A, 514B, 514C, and 514D. The system controller 502 generally includes a central processing unit (CPU) 530, a memory 534, and support circuits 532. The CPU 530 can be one of any form of general-purpose computer processor that can be used in an industrial environment. The support circuits 532 are conventionally coupled to the CPU 530 and may include caches, clock circuits, input / output subsystems, power supplies, etc. Software routines (e.g., processing methods as described above) can be stored in the memory 534 and, when executed by the CPU 530, transform the CPU 530 into the system controller 502. The software routines can also be stored and / or executed by a second controller (not shown) located remotely from the multi-chamber processing tool 500.

[0030] In operation, the system controller 502 enables data and feedback to be collected from the respective chambers and systems to optimize the performance of the multi-chamber processing tool 500, and provides instructions to the system components for performing the methods described herein. For example, the memory 534 may be a non-transitory computer-readable storage medium having instructions that, when executed by the CPU 530 (or the system controller 502), perform the methods described herein.

[0031] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof.

Claims

1. A method of filling a feature in a silicon-containing dielectric layer of a substrate, comprising: depositing a non-continuous liner layer in the feature via a physical vapor deposition (PVD) process in a first processing chamber; performing a hydrogen plasma treatment in a second processing chamber to form silicon-hydrogen bonds on surfaces of the features not covered by the non-continuous liner layer; as well as A bulk tungsten layer consisting essentially of tungsten is deposited in a third processing chamber on the non-continuous liner layer and over the silicon-hydrogen bonds to fill the features with tungsten.

2. The method of claim 1, wherein the method is performed in a multi-chamber processing tool wherein there is no vacuum break between the first processing chamber, the second processing chamber, and the third processing chamber. 3 . The method of claim 1 , wherein the hydrogen plasma treatment is performed in a capacitively coupled plasma (CCP) chamber. The method of claim 1 , wherein the non-continuous liner layer comprises titanium nitride (TiN) or tungsten.

5. The method of claim 1, wherein a chamber pressure during the hydrogen plasma treatment is greater than about 100 mTorr.

6. The method of claim 1, wherein the features have a critical dimension of about 20 nanometers or less.

7. The method of any one of claims 1 to 6, wherein the hydrogen plasma treatment is performed for about 90 to about 250 seconds.

8. The method of any one of claims 1 to 6, wherein a chamber pressure during the hydrogen plasma treatment is about 0.3 to about 1.8 Torr.

9. The method according to any one of claims 1 to 6, wherein the hydrogen plasma treatment is performed using a plasma comprising hydrogen ions and argon ions.

10. The method of claim 9, wherein a ratio between the hydrogen ions and the argon ions is about 4:1 to about 45:

1.

11. The method of any one of claims 1 to 6, wherein depositing the bulk tungsten layer is performed in a chemical vapor deposition (CVD) chamber.

12. The method of any one of claims 1 to 6, wherein depositing the bulk tungsten layer is performed in an atomic layer deposition (ALD) chamber.

13. The method of claim 12, wherein the hydrogen plasma treatment is performed for about 90 to about 250 seconds, and wherein a chamber pressure during the hydrogen plasma treatment is about 0.3 to about 1.8 Torr.

14. The method according to any one of claims 1 to 6, wherein the hydrogen plasma treatment is performed using a plasma including hydrogen ions and argon ions, wherein an amount of hydrogen plasma in the plasma is greater than an amount of argon ions in the plasma.

15. A non-transitory computer readable medium storing instructions which, when executed by one or more processors, perform the method according to any one of claims 1 to 6.

16. The non-transitory computer readable medium of claim 15, wherein the hydrogen plasma treatment is performed using a plasma comprising hydrogen ions and argon ions.

17. The non-transitory computer readable medium of claim 16, wherein a ratio between the hydrogen ions and the argon ions is about 4:1 to about 45:

1.

18. The non-transitory computer readable medium of claim 15, wherein at least one of the following: The chamber pressure during the hydrogen plasma treatment is greater than about 100 mTorr; or The hydrogen plasma treatment is performed for about 90 to about 250 seconds.

19. The non-transitory computer readable medium of claim 15, wherein depositing the bulk tungsten layer is performed in a chemical vapor deposition (CVD) chamber.

20. The non-transitory computer readable medium of claim 15, wherein depositing the bulk tungsten layer is performed in an atomic layer deposition (ALD) chamber.

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