Method for metal gap filling
By using plasma-enhanced atomic layer deposition (PEALD) technology, metal layers are deposited in semiconductor devices using metal precursors and argon-hydrogen plasma, solving the problem of high contact resistivity and achieving a contact structure with low resistivity and high reliability.
Patent Information
- Application Number
- CN202480028165.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-05-26
- Filing Date
- 2024-05-21
- Publication Date
- 2025-12-05
AI Technical Summary
In the prior art, the contact formation of semiconductor devices has high resistivity, which leads to low conductivity and may cause thermal problems, affecting performance and reliability.
Plasma-enhanced atomic layer deposition (PEALD) is employed, which combines metal precursors such as tungsten hexafluoride with argon-hydrogen plasma to deposit metal layers on dielectric layers and directly deposit interstitial materials in the field and openings to ensure complete filling of the openings and avoid the formation of high-resistivity layers.
A low resistivity contact structure was achieved, which reduced the contact resistivity, improved the conductivity and reliability, and avoided thermal problems caused by resistance heating.
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Figure CN121079759A_ABST
Abstract
Description
Technical Field
[0001] Implementation of this principle typically involves gap-filling methods for semiconductor substrates. Background Technology
[0002] When manufacturing semiconductor devices, these devices form contacts to allow electrical connections to the device via other devices or for external electrical connections to the chip or circuit. These contacts are made of metallic materials that promote conductivity. Higher conductivity corresponds to lower resistivity. The inventors have observed that current manufacturing techniques produce contacts with high resistivity, which reduces conductivity and can cause thermal problems due to resistance heating within the contacts, leading to poor performance and reduced reliability.
[0003] Therefore, the inventors have provided an improved method for gap filling when forming contacts with low resistivity and improved reliability. Summary of the Invention
[0004] Embodiments of this disclosure relate to a method for filling gaps in features in a substrate. In one embodiment, the metal gap-filling method includes depositing a metal layer on a dielectric layer present in the field and in the openings of the features by plasma-enhanced atomic layer deposition using a metal precursor according to Formula I;
[0005] Where M is a metal from Group 6 to Group 9; where X is fluorine or chlorine; and a ranges from 2 to 6; and plasma containing hydrogen and an inert gas; and a metal interstitial filling material is deposited directly above the metal layer in the field and opening, wherein the metal interstitial filling material completely fills the opening.
[0006] In an embodiment, the method of metal gap filling includes depositing a base metal layer on a portion of the opening in the dielectric layer and features present in the field by physical vapor deposition or chemical vapor deposition; depositing a conformal metal layer directly on the base metal layer and a portion of the opening in the dielectric layer and features present in the field; and plasma-enhanced atomic layer deposition using a metal precursor according to Formula I.
[0007] Where M is a metal from Group 6 to Group 9; where X is fluorine or chlorine; and a ranges from 2 to 6; and argon-hydrogen plasma; and interstitial metal filling material is deposited directly above the metal layer in the field and in the opening, wherein the interstitial metal filling material completely fills the opening; wherein the mass ratio of argon to hydrogen in the argon-hydrogen plasma is about 1 to 10, to about 10 to 1; and plasma-enhanced atomic layer deposition is performed at a power greater than or equal to about 200 watts and less than or equal to about 1600 watts.
[0008] In some embodiments, a non-transitory computer-readable medium stores instructions that, when executed, will result in performing a method of metal gap filling, the method comprising depositing a metal layer on a dielectric layer present in a field and in a feature opening by plasma-enhanced atomic layer deposition using a metal precursor according to Formula I.
[0009] Where M is a metal from Group 6 to Group 9; where X is fluorine or chlorine; and a ranges from 2 to 6; and a plasma containing hydrogen and an inert gas; and a metal interstitial filling material is deposited directly above the metal layer in the field and the opening, wherein the metal interstitial filling material completely fills the opening. Attached Figure Description
[0010] The implementation of this principle, briefly summarized above and discussed in more detail below, can be understood by referring to the illustrative embodiments of this principle shown in the accompanying drawings. The drawings only illustrate typical embodiments of this principle and should not be considered as limiting the scope, as these principles may be applicable to other equally effective implementations.
[0011] Figure 1 A cross-sectional view showing a feature formed in a substrate according to an embodiment disclosed herein.
[0012] Figure 2 This shows a cross-sectional view of the dielectric layer deposited on the feature and substrate according to the embodiments disclosed herein.
[0013] Figure 3 This shows a cross-sectional view of the base metal layer deposited on the feature and substrate according to the embodiments disclosed herein.
[0014] Figure 4 This shows a cross-sectional view of a metal layer deposited on a substrate metal layer by plasma-enhanced atomic layer deposition according to the embodiments disclosed herein.
[0015] Figure 5 This shows a metal gap-filling material deposited on a metal layer on a feature and a substrate according to the embodiments disclosed herein.
[0016] Figure 6 This is a flowchart illustrating a method for filling metal gaps according to the embodiments disclosed herein.
[0017] Figure 7 This demonstrates the integration tools according to the implementation methods disclosed herein. Detailed Implementation
[0018] These methods provide a way to fill metal gaps, in which the metal gap-filling material completely fills the characteristic openings of the substrate.
[0019] In some embodiments, a metal layer is deposited in the dielectric layer and the characteristic opening present in the field by using a metal precursor according to Formula I, the method being plasma-enhanced atomic layer deposition.
[0020] Where M is a metal from Group 6 to Group 9; where X is fluorine or chlorine; and a ranges from 2 to 6; and includes a plasma containing hydrogen and an inert gas; and deposits a metal interstitial material directly over the metal layer in the field and the opening, wherein the metal interstitial material completely fills the opening.
[0021] In some embodiments, the metal precursor comprises tungsten hexafluoride. In some embodiments, the plasma is an argon-hydrogen plasma with an argon to hydrogen mass ratio of about 1 to 10, to about 10 to 1. In some embodiments, plasma-enhanced atomic layer deposition is performed at a temperature of about 250°C or higher; at a pressure of about 0.1 to 250 Torr; at a power of about 200 watts or higher; or a combination thereof. In some embodiments, the thickness of the metal layer is less than or equal to about 15 nm. In some embodiments, the metal layer is a conformal metal layer having a thickness of about 5 nm to about 10 nm. In some embodiments, the metal layer is tungsten, and the interstitial metal filling material comprises tungsten, is substantially composed of tungsten, or is composed of tungsten. In some embodiments, the metal layer is deposited by plasma-enhanced atomic layer deposition and the interstitial metal filling material is deposited in an integrated tooling without vacuum interruption between the two. In some embodiments, the interstitial metal filling material is deposited by physical vapor deposition or chemical vapor deposition.
[0022] In some embodiments, the metal layer is deposited on a substrate metal layer that is deposited on a portion of the dielectric layer in the field and feature openings by physical vapor deposition or chemical vapor deposition. In some embodiments, the substrate metal layer is deposited anisotropically by physical vapor deposition or chemical vapor deposition, followed by plasma-enhanced atomic layer deposition in the integration process without vacuum interruption between the two. In some embodiments, the metal layer is tungsten, the substrate metal layer is tungsten, and the intermetallic interstitial filling material is tungsten.
[0023] Figure 1Features of substrate 100 are depicted, including feature 104 having a side 106 and a bottom 108 in the form of an opening 103 formed on or within a dielectric layer 102 of substrate 100. The dielectric layer 102 can be any suitable dielectric material, typically used in the fabrication of microelectronic devices, such as silicon oxide or similar materials. Although not shown, a conductive layer may be disposed within the dielectric layer 102, for example, exposed at the bottom 108 location of feature 104. A representative feature 104 in this example is the opening 103 in field 110 of substrate 100. Feature 104 has a height of 114 and a width of 112.
[0024] Figure 2 Feature 104 of substrate 100 is depicted, which further includes a pad or barrier layer 202, which can be deposited using atomic layer deposition (ALD), physical vapor deposition (PVD), or chemical vapor deposition (CVD) processes. In some embodiments, barrier layer 202 is a conformal layer formed by atomic layer deposition. In some embodiments, the barrier layer may include, but is not limited to, titanium nitride, tungsten nitride, and / or tungsten carbonitride and similar materials. The materials used for barrier layer 202 are typically dielectric materials with high resistivity, such as oxides, nitrides, and / or carbides, which can reduce the conductivity of the contact. By using a thin layer (i.e., less than about 10 micrometers), the resistivity of barrier layer 202 is significantly reduced. Metal deposition, such as by PVD tungsten and CVD tungsten, typically has a resistivity of about 15 ohm-cm or lower. Titanium nitride, on the other hand, has a resistivity of about 200 to 600 ohm-cm. Reducing the thickness of barrier layer 202 has a significant impact on contact resistivity.
[0025] Figure 3 One embodiment is shown, wherein feature 104 of substrate 100 further includes a base metal layer 302, which in some embodiments is a non-conformal layer deposited on the bottom 108 of feature 104 and the field 110 of substrate 100 using an anisotropic deposition process. Because the deposition process is oriented, the first thickness 304 of the base metal layer 302 may be substantially the same on the field 110 of substrate 100 and the bottom 108 of feature 104. In some embodiments, the first thickness 304 is approximately 30 micrometers to approximately 50 micrometers. In some embodiments, the first thickness 304 is approximately 30 micrometers to approximately 40 micrometers. In some embodiments, the first thickness 304 is approximately 32 micrometers to approximately 37 micrometers. Figure 3 As shown, the second thickness 306 of the base metal layer 302 on the side 106 of feature 104 is negligible and may be discontinuous due to the directionality of the deposition process.
[0026] In some embodiments, the base metal layer 302 may be deposited using a PVD process or a similar method. In some embodiments, the PVD process is self-biased to provide anisotropic, non-conformal deposition of the base metal layer 302. In some embodiments, the PVD process may apply a bias to the substrate to further influence the PVD deposition. The base metal layer 302 is formed on a barrier layer 202 on field 110 of the substrate 100 and on a barrier layer 202 on the bottom 108 of feature 104. Any deposition of the base metal layer 302 on the barrier layer 202 on the side 106 of feature 104 may be discontinuous and of negligible thickness. In some embodiments, the base metal layer 302 is formed of one or more Group 6 to Group 9 metals, such as tungsten and / or cobalt. In some embodiments, the base metal layer 302 is formed of tungsten.
[0027] Figure 4 The metal layer 406 is shown to be deposited directly on the barrier layer 202 and directly on the base metal layer 302 present in the opening 103 of the field 110 and feature 104 by using plasma enhanced atomic layer deposition (PEALD) of the metal precursor according to Formula I.
[0028] Where M is a metal from Group 6 to Group 9; where X is fluorine or chlorine; and a ranges from 2 to 6, and is combined with a plasma containing hydrogen and an inert gas.
[0029] For example, a PEALD process may involve multiple sequential cycles that contact the substrate with a metal precursor (e.g., a first pulse) and then contact the substrate with a plasma containing hydrogen and an inert gas (e.g., a second pulse). An inert purge gas may be provided between the first and second pulses. In some embodiments, the purge gas may be continuously supplied throughout the PEALD process.
[0030] In some embodiments, the metal precursor is tungsten hexafluoride, and the inert gas includes helium and / or argon. In some embodiments, the inert gas is argon, and the plasma is an argon-hydrogen plasma. In some embodiments, the purge gas is an inert gas. In some embodiments, the purge gas is argon.
[0031] The inventors observed that, by using an ALD combining a metal halide (e.g., tungsten hexafluoride) with argon-hydrogen plasma, germanium atoms can be directly deposited on a barrier layer 202 and a base metal layer 302, the barrier layer typically located on the side 106 of feature 104, and the base metal layer 302 typically located on the base metal layer at the bottom 108 of field 110 and feature 104. Figure 3As shown, the base metal layer 302 may be located on a portion of the side surface 106. The inventors have observed that by using an ALD combining a metal halide with an argon-hydrogen plasma according to embodiments disclosed herein, a metal layer can be formed directly over the barrier layer 202 and portions of the discontinuous base metal layer 302, thereby creating a continuous metal seed layer. In some embodiments, the plasma is an argon-hydrogen plasma having an argon to hydrogen mass ratio ranging from about 1 to 10, to about 10 to 1, or from about 1 to 5 to about 5 to 1, or from about 10 to 1 to about 1 to 1.
[0032] In some embodiments, plasma-enhanced atomic layer deposition is performed at temperatures greater than or equal to about 250°C, or greater than or equal to about 300°C, or greater than or equal to about 350°C and less than or equal to about 600°C, or less than or equal to about 450°C, or less than or equal to about 400°C.
[0033] In some embodiments, plasma-enhanced atomic layer deposition is performed under pressures ranging from about 0.1 to 250 Torr, or from about 0.1 to 150 Torr, or from about 0.1 to 100 Torr, or from about 0.1 to 10 Torr.
[0034] In some embodiments, plasma-enhanced atomic layer deposition is performed at a power greater than or equal to about 200 watts, or greater than or equal to about 300 watts, or greater than or equal to about 600 watts and less than or equal to about 1600 watts.
[0035] In some embodiments, the thickness of the metal layer is less than or equal to about 15 nm. In some embodiments, the thickness of the metal layer is greater than or equal to about 5 nm and less than or equal to about 10 nm.
[0036] Figure 5 The metal interstitial filling material 502 is depicted deposited on the neutral field 110 of the opening 103, directly above the metal layer 406, wherein the metal interstitial filling material 502 completely fills the opening 103 of the feature 104.
[0037] In some embodiments, the interstitial metal filling material 502 completely fills the opening 103 of feature 104 without any pores. In some embodiments, the interstitial metal filling material 502 may be, but is not limited to, tungsten and / or cobalt. In some embodiments, the interstitial metal filling material 502 comprises tungsten. In some embodiments, the interstitial metal filling material 502 is tungsten, or is substantially composed of tungsten. In some embodiments, the substrate metal layer 302, metal layer 406, and interstitial metal filling material 502 are all the same metal. In some embodiments, the substrate metal layer 302, metal layer 406, and interstitial metal filling material 502 all comprise tungsten. In some embodiments, the substrate metal layer 302, metal layer 406, and interstitial metal filling material 502 are all tungsten, or are substantially composed of tungsten. In some embodiments, the interstitial metal filling material 502 is deposited by physical vapor deposition or chemical vapor deposition. In some embodiments, the interstitial metal filling material 502 is deposited by chemical vapor deposition.
[0038] The inventors discovered that the gap-filling method according to the embodiments can produce an internal structure with full tungsten contact without resulting in a high-resistivity layer due to the metal layer 406 not being directly deposited on the barrier layer 202 present in the field 110 and the feature opening 103. This deposition is performed by plasma-enhanced atomic layer deposition using hexafluorotungsten and argon-hydrogen plasma. Furthermore, the chemical vapor deposition tungsten metal gap-filling material 502 grown on the atomic layer deposition tungsten layer 406 has a low resistance of less than about 5 microohms per mm². Moreover, the metal gap-filling material 502 completely fills the feature 104 without forming pores.
[0039] Figure 6 This is a flowchart of a method 600 according to an embodiment disclosed herein. Method 600 includes depositing a metal layer in a dielectric layer and a feature opening present in a field by plasma-enhanced atomic layer deposition utilizing a metal precursor according to Formula I;
[0040] Where M is a metal from Group 6 to Group 9; X is fluorine or chlorine; and a ranges from 2 to 6; and a plasma containing hydrogen and an inert gas (block 602). Method 600 further includes depositing a metal interstitial material directly on the metal layer within the field and opening, wherein the metal interstitial material completely fills the opening. In some embodiments, method 600 may include, except... Figure 6 Additional blocks beyond those shown.
[0041] The methods described in this paper can be executed in separate processing chambers, which can be provided either independently or as part of a cluster tool, for example, as described below. Figure 7The described integrated tool 700 (i.e., cluster tool) is used in some embodiments. In some implementations, the method 600 according to one or more embodiments is performed within the integrated tool, and there is no vacuum interruption between the deposition of the metal layer 406 and the deposition of the metal interstitial filling material 502. An advantage of using the integrated tool 700 is the absence of vacuum interruptions between chambers, thus eliminating the need for degassing and pre-cleaning of the substrate prior to processing within the chambers. For example, in some implementations, the above-described methods can be advantageously performed in the integrated tool such that vacuum interruptions between processes are limited or eliminated, thereby limiting or preventing substrate contamination, such as oxidation and the like. The integrated tool 700 includes a vacuum-sealed processing platform 701, a factory interface 704, and a system controller 702. The processing platform 701 includes multiple processing chambers, such as 714A, 714B, 714C, 714D, 714E, and 714F, which are operatively coupled to vacuum substrate transfer chambers (transfer chambers 703A, 703B). The factory interface 704 is connected via one or more load-locked chambers (two load-locked chambers, such as...). Figure 7 The 706A and 706B shown are operatively coupled to the transfer chamber 703A.
[0042] In some implementations, the factory interface 704 includes at least one docking station 607 and at least one factory interface robot 738 to facilitate the transfer of semiconductor substrates. The docking station 607 is configured to receive one or more front-opening unified pods (FOUPs). Figure 7 The embodiment shows four FOUPs, designated 705A, 705B, 705C, and 705D. A factory interface robot 738 is configured to transfer substrates from a factory interface 704 to a processing platform 701 via load-locking chambers (such as 706A and 706B). Each load-locking chamber 706A and 706B has a first port coupled to the factory interface 704 and a second port coupled to a transfer chamber 703A. Load-locking chambers 706A and 706B are coupled to a pressure control system (not shown) that evacuates and ventilates load-locking chambers 706A and 706B to facilitate the passage of substrates between the vacuum environment of transfer chamber 703A and the basic surrounding (atmospheric) environment of the factory interface 704. Vacuum robots 742A and 742B are respectively located within the transfer chambers 703A and 703B. Vacuum robot 742A is capable of transferring substrate 721 between load locking chambers 706A, 706B, processing chambers 714A and 714F, and cooling station 740 or pre-cleaning station 741. Vacuum robot 742B is capable of transferring substrate 721 between cooling station 740 or pre-cleaning station 741 and processing chambers 714B, 714C, 714D and 714E.
[0043] In some embodiments, processing chambers 714A, 714B, 714C, 714D, 714E, and 714F are coupled to transfer chambers 703A and 703B. Processing chambers 714A, 714B, 714C, 714D, 714E, and 714F may, for example, include atomic layer deposition (ALD) processing chambers, physical vapor deposition (PVD) processing chambers, chemical vapor deposition (CVD) chambers, annealing chambers, or the like. These chambers may include any chamber suitable for performing all or part of the methods described herein, as previously described, provided in one or more ALD deposition chambers, non-conformal PVD deposition chambers, CVD deposition chambers, and the like. In some embodiments, one or more optional service chambers (shown as 716A and 716B) may be coupled to transfer chamber 703A. Service chambers 716A and 716B may be configured to perform other substrate processing, such as degassing, orientation, substrate metering, cooling, and the like.
[0044] System controller 702 controls the operation of tool 700 by directly controlling processing chambers 714A, 714B, 714C, 714D, 714E, and 714F or by controlling a computer (or controller) associated with processing chambers 714A, 714B, 714C, 714D, 714E, and 714F and tool 700. During operation, system controller 702 enables the collection and feedback of data from the relevant chambers and systems to optimize the performance of tool 700. System controller 702 typically includes a central processing unit (CPU) 730, memory 734, and support circuitry 732. CPU 730 can be any type of general-purpose computer processor suitable for industrial environments. Support circuitry 732 is conventionally coupled to CPU 730 and may include cache memory, clock circuitry, input / output subsystems, power supply, and the like. Software programs, such as those described above, can be stored in memory 734, which, when executed by CPU 730, transforms CPU 730 into a dedicated computer (system controller) 702. These software programs can also be stored and / or executed by a second controller (not shown) located remotely to tool 700.
[0045] Implementations based on this principle can be implemented in hardware, firmware, software, or any combination thereof. Implementations can also be implemented as instructions stored using one or more computer-readable media, which can be read and executed by one or more processors. Computer-readable media can include any mechanism for storing or transmitting information in a machine-readable form (e.g., a computing platform or a “virtual machine” running on one or more computing platforms). For example, computer-readable media can include any suitable form of volatile or non-volatile. In some implementations, computer-readable media can include a non-transitory computer-readable medium.
[0046] While the foregoing describes an implementation of this principle, other and further implementations of this principle may be conceived without departing from its basic scope.
Claims
1. A method for metal gap fill, comprising: depositing a metal layer on a dielectric layer present on a field and an opening of a feature by plasma enhanced atomic layer deposition using a metal precursor according to Formula I; where M is a Group 6 to Group 9 metal, X is fluorine or chlorine, and a ranges from 2 to 6, and with a plasma containing hydrogen and an inert gas; and depositing a metal gap fill material directly over the metal layer in the field and the opening, wherein the metal gap fill material completely fills the opening.
2. The method of claim 1, wherein the metal precursor comprises tungsten hexafluoride.
3. The method of claim 1, wherein the plasma is an argon-hydrogen plasma with a mass ratio of argon to hydrogen of about 1 to 10, to about 10 to 1.
4. The method of claim 1, wherein the plasma enhanced atomic layer deposition is performed at a temperature of about 250 °C or greater, a pressure ranging from about 0.1 to 250 Torr, a power of about 200 Watts or greater, or a combination thereof.
5. The method of claim 1, wherein the metal layer has a thickness of less than or equal to about 15 nm.
6. The method of claim 1, wherein the metal layer is a conformal metal layer having a thickness ranging from about 5 nm to about 10 nm.
7. The method of claim 1, wherein the metal layer is tungsten, and the metal gap fill material comprises tungsten.
8. The method of any one of claims 1 to 7, wherein depositing the metal layer and depositing the metal gap fill material by plasma enhanced atomic layer deposition are performed in an integrated tool without a vacuum break between the two.
9. The method of any one of claims 1 to 7, wherein the metal gap fill material is deposited by physical vapor deposition or chemical vapor deposition.
10. The method of any one of claims 1 to 7, wherein the metal layer is deposited on a base metal layer deposited by physical vapor deposition or chemical vapor deposition on a portion of the dielectric layer present on the field and the opening of the feature.
11. The method of claim 10, wherein the base metal layer is deposited by physical vapor deposition or chemical vapor deposition in an anisotropic manner, followed by depositing the metal layer by plasma enhanced atomic layer deposition without a vacuum break in the integrated process.
12. The method of claim 10, wherein the metal layer is tungsten, the base metal layer is tungsten, and the metal gap fill material is tungsten.
13. The method of claim 1, wherein the metal layer is deposited on a base metal layer deposited by physical vapor deposition or chemical vapor deposition on a portion of the dielectric layer present on the field and the opening of the feature; wherein the plasma enhanced atomic layer deposition utilizes an argon-hydrogen plasma; wherein the mass ratio of argon to hydrogen in the argon-hydrogen plasma is about 1 to 10, to about 10 to 1; and wherein the metal gap fill material is deposited by physical vapor deposition or chemical vapor deposition. wherein the plasma enhanced atomic layer deposition is performed at a power greater than or equal to about 200 Watts and less than or equal to about 1600 Watts.
14. The method of claim 13, wherein the metal precursor is tungsten hexafluoride.
15. The method of claim 13, wherein the metal gap fill material is tungsten.
16. The method of claim 13, wherein the base metal layer is tungsten, and wherein the base metal layer is deposited by physical vapor deposition or chemical vapor deposition in an anisotropic manner, then the metal layer is deposited by plasma enhanced atomic layer deposition, followed by depositing the metal gap fill material in an integrated process without vacuum interruption.
17. The method of claim 13, wherein the metal gap fill material is deposited by physical vapor deposition or chemical vapor deposition.
18. The method of claim 13, wherein the plasma enhanced atomic layer deposition is performed at a temperature greater than or equal to about 250 °C, and the plasma enhanced atomic layer deposition is performed at a pressure of about 0.1 to 250 Torr.
19. A non-transitory computer readable medium having instructions stored thereon that, when executed, will result in performing a method for metal gap fill as described in any of claims 1 to 7.
20. The non-transitory computer readable medium of claim 19, wherein the method further comprises: performing deposition of the metal layer and deposition of the metal gap fill material in an integrated tool by plasma enhanced atomic layer deposition, without vacuum interruption between the two; depositing the metal gap fill material by physical vapor deposition or chemical vapor deposition; or depositing the metal layer on top of a base metal layer deposited by physical vapor deposition or chemical vapor deposition on a portion of the dielectric layer and the opening of the feature present on the field.