Method for forming metal gap fillers with low resistance
By depositing conformal and non-conformal metal layers in semiconductor processes and depositing metal gap filler materials in feature openings, the problem of high contact resistivity in the prior art is solved, and contacts with low resistivity and high reliability are achieved, and performance and reliability are improved.
Patent Information
- Application Number
- CN202380065707.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-09-14
- Filing Date
- 2023-09-11
- Publication Date
- 2025-04-25
AI Technical Summary
Contacts manufactured in existing semiconductor processes have high resistivity, resulting in reduced conductivity and thermal problems, which in turn affect performance and reliability.
By depositing conformal and non-conformal metal layers on the substrate and depositing metal gap filler material in the feature openings, an anisotropic deposition process and a chemical vapor deposition process ensure that the filler completely fills the openings without voids.
The formation of contacts with low resistivity and high reliability is achieved, which maximizes the volume of the gap filler, enhances the adhesion characteristics, and can better resist chemical mechanical grinding (CMP) forces.
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Figure CN119895560A_ABST
Abstract
Description
Technical Field
[0001] Embodiments of the present principles generally relate to semiconductor chambers used in semiconductor processing. Background Art
[0002] When manufacturing semiconductor devices, the device is formed with contacts to allow other devices to be electrically connected to the device or for electrical connection outside the chip or circuit. The contacts are made of a metallic material that increases electrical conductivity. The higher the electrical conductivity, the lower the resistivity. However, the inventors have observed that current manufacturing techniques produce contacts with high resistivity, which reduces electrical conductivity and may cause thermal problems due to resistive heating in the contacts, resulting in poor performance and reduced reliability.
[0003] Thus, the inventors have provided improved methods for forming contacts having low resistivity metal gap fillers and increased reliability. Summary of the invention
[0004] Methods for forming metal gap fillers having low resistivity and high reliability are provided herein.
[0005] In some embodiments, a method for reducing the resistivity of a metal gap filler may include the steps of depositing a conformal layer in an opening of a feature and on an area of a substrate, wherein a first thickness of the conformal layer is approximately 10 microns or less, depositing a non-conformal metal layer directly on the conformal layer at the bottom of the opening and directly on the area using an anisotropic deposition process, wherein a second thickness of the non-conformal metal layer on the area and on the bottom of the feature is approximately 30 microns or greater, and depositing a metal gap filler material in the opening of the feature and on the area, wherein the metal gap filler material completely fills the opening without any voids.
[0006] In some embodiments, the method may further include the following steps: depositing a conformal layer using an atomic layer deposition (ALD) process, depositing a non-conformal metal layer using a plasma vapor deposition (PVD) process, and depositing a metal gap filler material using a chemical vapor deposition (CVD) process; wherein the first thickness is approximately 3 microns to approximately 8 microns; wherein the second thickness is approximately 40 microns; wherein the sum of the first thickness and the second thickness is at least approximately 40 microns; wherein the conformal layer is titanium nitride, tungsten nitride, or tungsten carbonitride; wherein the non-conformal metal layer is tungsten or cobalt; wherein the metal gap filler material is tungsten or cobalt; wherein the feature is a contact for a logic device; wherein the thickness of the conformal layer is at least a monolayer; and / or the method is performed in an integrated tool.
[0007] In some embodiments, a method for reducing the resistivity of a metal gap filler may include the following steps: depositing a titanium nitride conformal layer in an opening of a feature and on an area of a substrate using an atomic layer deposition (ALD) process, wherein a first thickness of the titanium nitride conformal layer is approximately 10 microns or less, depositing a tungsten non-conformal layer directly on the titanium nitride conformal layer at the bottom of the opening and directly on the area using a plasma vapor deposition (PVD) process, wherein a second thickness of the tungsten non-conformal layer on the area and on the bottom of the feature is approximately 30 microns to approximately 50 microns, and depositing a tungsten gap filler material in the opening of the feature and on the area using a chemical vapor deposition (CVD) process, wherein the tungsten gap filler material completely fills the opening without any voids.
[0008] In some embodiments, the method may further include: wherein the first thickness is approximately 3 microns to approximately 8 microns, wherein the second thickness is approximately 40 microns, wherein the sum of the first thickness and the second thickness is at least approximately 40 microns, wherein the feature is a contact for a logic device, wherein the thickness of the titanium nitride conformal layer is at least a monolayer, and / or the method is performed in an integrated tool.
[0009] In some embodiments, a non-transitory computer-readable medium having instructions stored thereon is disclosed that, when executed, causes a method for reducing the resistivity of a metal gap filler to be performed, the method may include the steps of depositing a conformal layer in an opening of a feature and on an area of a substrate, wherein a first thickness of the conformal layer is approximately 10 microns or less, depositing a non-conformal metal layer directly on the conformal layer at the bottom of the opening and directly on the area using an anisotropic deposition process, wherein a second thickness of the non-conformal metal layer on the area and on the bottom of the feature is approximately 30 microns to approximately 50 microns, and depositing a metal gap filler material in the opening of the feature and on the area, wherein the metal gap filler material completely fills the opening without any voids.
[0010] In some embodiments, the method of non-transitory computer readable media may further include the steps of depositing a conformal layer using an atomic layer deposition (ALD) process, depositing a non-conformal metal layer using a plasma vapor deposition (PVD) process, and depositing a metal gap filler material using a chemical vapor deposition (CVD) process.
[0011] Other and further embodiments are disclosed hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Embodiments of the present principles (briefly summarized above and discussed in more detail below) may be understood by reference to the exemplary illustrative embodiments of the principles depicted in the accompanying drawings. However, the drawings illustrate only typical embodiments of the present principles and are not to be considered limiting of the scope, as the present principles may admit to other equally effective embodiments.
[0013] Figure 1 Depicted are cross-sectional views of features formed in a substrate, according to some embodiments of the present principles.
[0014] Figure 2 Depicted are cross-sectional views of conformal layers deposited on features and substrates, according to some embodiments of the present principles.
[0015] Figure 3 Depicted are cross-sectional views of non-conformal layers deposited on features and substrates, according to some embodiments of the present principles.
[0016] Figure 4 Depicted are cross-sectional views of metal gap filler material deposited on features and substrates, according to some embodiments of the present principles.
[0017] Figure 5 A method of depositing a metal gap filler material having low resistivity in accordance with some embodiments of the present principles.
[0018] Figure 6 An integration tool is described in accordance with some embodiments of the present principles.
[0019] To facilitate understanding, the same reference numerals have been used where possible to designate the same elements shared by the figures. The figures are not drawn to scale and may be simplified for clarity. The elements and features of one embodiment may be advantageously incorporated into other embodiments without further elaboration. DETAILED DESCRIPTION
[0020] The method provides a contact with low resistivity with maximized gap filler volume and enhanced adhesion properties to better resist chemical mechanical polishing (CMP) forces. This technology combines a thin conformal liner layer (e.g., TiN, WN, etc.) and a plasma vapor deposition (PVD) metal (e.g., W, etc.) layer as a liner for a metal gap filler material (e.g., chemical vapor deposition (CVD) W, etc.) to meet both CMP / adhesion requirements and gap filler requirements, providing a low resistivity metal gap filler solution with enhanced parameters. The reduced thickness of the conformal liner reduces the resistivity of the contact. The conformal liner layer provides a continuous sidewall liner for the feature during a CVD metal gap filler process with low incubation and good growth in the feature to prevent the formation of voids, thereby improving the gap filler process. The non-conformal PVD metal layer, as well as the conformal liner layer, provides sufficient thickness on an area of the substrate to meet the adhesion requirements for CMP. Compared to conventional processes, the combined thin conformal liner layer and PVD metal layer has a reduced thickness inside the feature so that the gap filler volume of the feature is increased, further reducing contact resistance and improving gap filler performance. In addition, the combination of the conformal liner layer and the non-conformal PVD metal layer provides an adherent cap over an area of the substrate to improve the CMP process. The method can be used to form contacts in features used in logic devices and the like.
[0021] exist Figure 5 , a method 500 of depositing a metal gap filler material having a low resistivity is depicted in accordance with some embodiments. During discussion of the method 500, reference is made to Figure 1-4 In block 502, a feature 104 having a side 106 and a bottom 108 is formed on a substrate 102 (as in Figure 1 100 of FIG. 100 ). The representative feature in this example is an opening in region 110 of substrate 102 . Feature 104 has a height 114 and a width 112 . In order to provide a maximum volume of gap filler material, the ratio of height 114 to width 112 or aspect ratio of feature 104 should be kept as close as possible. Method 500 as described herein provides the following: close to maximum volume by minimizing any effect on the aspect ratio of feature 104. In block 504 , conformal layer 202 is deposited in feature 104 and on region 110 of substrate 102 (as in FIG. 104 ). Figure 2200 of ). The conformal layer 202 has substantially the same thickness 204 on the region 110 of the substrate 102, on the side 106 of the feature 104, and on the bottom 108 of the feature 104. In some embodiments, the thickness 204 may be about 10 microns or less. In some embodiments, the thickness 204 may be about 3 microns to about 8 microns. In some embodiments, the thickness 204 may have the thickness of one or more monolayers of the deposited material of the conformal layer 202. The thickness of the monolayer determines the minimum thickness of the conformal layer 202. The thinner the conformal layer 202, the lower the resistivity of the conformal layer 202. The conformal layer 202 should be continuous on the region 110 and in the feature 104.
[0022] In some embodiments, the conformal layer 202 may be deposited using an atomic layer deposition (ALD) process. The conformal layer 202 may be, but is not limited to, titanium nitride, tungsten nitride, and / or tungsten carbonitride, among others. The material used for the conformal layer 202 is typically an oxide with a high resistivity, which reduces the conductivity of the contact. By using a thin layer (i.e., less than about 10 microns), the resistivity of the conformal layer 202 is significantly reduced. Metal depositions (e.g., PVD tungsten and CVD tungsten) have a resistivity of about 15 ohm-cm or less. Titanium nitride has a resistivity of about 200 to 500 ohm-cm. The reduction in the thickness of the conformal layer 202 has a significant effect on the contact resistivity. The conformal layer 202 is used to provide adhesion for the CMP process of the gap filler material and to promote the growth of the gap filler material during the gap filler process. The low nucleation period of the conformal layer 202 promotes gap filler growth on the sides 106 of the feature 104, while the non-conformal layer promotes gap filler growth on the bottom 108 of the feature (discussed later). In some conventional approaches, long nucleation periods may occur on the sides of the feature, resulting in voids formed within the gap filler material, which significantly degrades the performance of the contact (and therefore the yield). The conformal layer 202 of the present method provides a solution to the problems found in conventional approaches.
[0023] At block 506, a non-conformal layer 302 is deposited on the bottom 108 of the feature 104 and on the region 110 of the substrate 102 using an anisotropic deposition process (as in Figure 3300 of FIG. 104). Because the deposition process is directional, the first thickness 304 of the non-conformal layer 302 is substantially the same across the region 110 of the substrate 102 and across the bottom 108 of the feature 104. In some embodiments, the first thickness 304 may be about 30 microns to about 50 microns. In some embodiments, the first thickness 304 may be about 30 microns to about 40 microns. In some embodiments, the first thickness 304 may be about 32 microns to about 37 microns. Due to the directional nature of the deposition process, the second thickness 306 of the non-conformal layer 302 on the side 106 of the feature 104 is negligible (and may be discontinuous).
[0024] In some embodiments, non-conformal layer 302 may be deposited using a PVD process and the like. In some embodiments, the PVD process is self-biased to provide anisotropic deposition of non-conformal layer 302. In some embodiments, the PVD process may further affect the PVD deposition using a bias applied to the substrate. Non-conformal layer 302 is formed on conformal layer 202 on region 110 of substrate 102 and on conformal layer 202 at bottom 108 of feature 104. Any deposition of non-conformal layer 302 on conformal layer 202 on side 106 of feature 104 may be discontinuous and the thickness may be negligible. In some embodiments, non-conformal layer 302 is formed of a metallic material, such as, but not limited to, tungsten and / or cobalt, and the like. The material of non-conformal layer 302 is selected to facilitate growth of a selected gap filler material. Non-conformal layer 302 not only serves to promote the growth of gap filler material in feature 104 , but also meets adhesion requirements during the CMP process on region 110 of substrate 102 .
[0025] At block 508, gap filler material 402 is deposited in feature 104 and on region 110 of substrate 102 (as in Figure 4 400 of ). In some embodiments, the gap filler material 402 may be (but is not limited to): tungsten and / or cobalt, and the like. In some embodiments, a chemical vapor deposition (CVD) process is used to deposit the gap filler material 402. The nucleation periods of the conformal layer 202 and the non-conformal layer 302 are similar, allowing growth to occur on the bottom 108 and the sides 106 without causing voids (empty spaces) to form within the gap filler material 402. Due to the thickness of the conformal layer 202 and the low deposition thickness characteristics of the non-conformal layer 302 on the sides 106 of the feature 104, the resulting width 112B of the feature 104 is within 20 microns or less of the original feature width 112 (see Figure 1), thereby maintaining a low aspect ratio of feature 104 (as opposed to a situation where the width of the feature is reduced and the aspect ratio is increased to a higher level). The maximized width of feature 104 allows for a maximum volume of gap filler material 402 inside feature 104, wherein the conductivity of the contact is increased (the resistivity is reduced) due to the increased volume. In some embodiments, method 500 can produce contacts with 50% or more volume of gap filler material compared to conventional processes.
[0026] The inventors have discovered that CVD gap filler materials have high internal stress and in order to avoid peeling, the thickness of the underlying layer should meet a minimum thickness requirement of at least about 40 microns. The combined thickness 404 of the conformal layer 202 and the non-conformal layer 302 meets the adhesion requirements required to prevent the gap filler material 402 from peeling during the CMP process. For example, when the CMP pad 406 rotates 408, the CMP pad 406 is pressed down on the surface 412 of the gap filler material 402. This rotation causes a shear force 410 to be applied to the surface 412 of the gap filler material 402. If the adhesion holding the gap filler material 402 to the area 110 of the substrate 102 is insufficient, the gap filler material 402 will begin to peel from the area 110 of the substrate 102, thereby potentially causing damage to the substrate 102 and the feature 104. In some embodiments, the combined thickness 404 on the area 110 of the substrate is at least about 40 microns in order to meet the adhesion requirements of the gap filler material 402 during the CMP process. In some embodiments, the thickness 204 of the conformal layer 202 is about 5 microns, and the thickness of the non-conformal layer is about 35 microns. Overall, the contacts produced by the method 500 have lower resistivity (larger gap filler volume and thinner oxide layer), higher yield (no voids), and improved performance.
[0027] The methods described herein can be performed in a single process chamber, which can be configured independently or as a cluster tool (e.g., as described below with respect to Figure 61 and 1 . The integrated tool 600 (i.e., cluster tool) described herein is provided as a portion of an integrated tool 600 (i.e., cluster tool) described herein. An advantage of using the integrated tool 600 is that there is no vacuum break between chambers, thereby eliminating the need to degas and pre-clean the substrate prior to processing in the chamber. For example, in some embodiments, the inventive methods discussed hereinabove may be advantageously performed in an integrated tool so that there is limited or no vacuum break between processes, thereby limiting or preventing contamination (e.g., oxidation, etc.) of the substrate. The integrated tool 600 includes: a vacuum sealed processing platform 601, a factory interface 604, and a system controller 602. The processing platform 601 includes: a plurality of processing chambers (e.g., 614A, 613B, 614C, 614D, 614E, and 614F operatively coupled to vacuum substrate transfer chambers (transfer chambers 603A, 603B)). The factory interface 604 communicates with the processing chambers via one or more load lock chambers (two load lock chambers (e.g., in Figure 6 606A and 606B)) shown in FIG. 6 are operatively coupled to transfer chamber 603A.
[0028] In some embodiments, the factory interface 604 includes at least one docking station 607 and at least one factory interface robot 638 to facilitate the transfer of semiconductor substrates. The docking station 607 is configured to receive one or more front opening wafer transport boxes (FOUPs). Four FOUPS (e.g., 605A, 605B, 605C, and 605D) are shown in FIG. Figure 6 In an embodiment of the present invention, the factory interface robot 638 is configured to transfer substrates from the factory interface 604 to the processing platform 601 via the load lock chambers (e.g., 606A and 606B). Each of the load lock chambers 606A and 606B has a first port coupled to the factory interface 604 and a second port coupled to the transfer chamber 603A. The load lock chambers 606A and 606B are coupled to a pressure control system (not shown) that pumps and exhausts the load lock chambers 606A and 606B to facilitate the transfer of substrates between the vacuum environment of the transfer chamber 603A and the substantially ambient (e.g., atmospheric) environment of the factory interface 604. The transfer chambers 603A, 603B have vacuum robots 642A, 642B disposed in the respective transfer chambers 603A, 603B. The vacuum robot 642A can transfer the substrate 621 between the load lock chambers 606A, 606B, the process chambers 614A and 614F, and the cooling station 640 or the pre-cleaning station 642. The vacuum robot 642B can transfer the substrate 621 between the cooling station 640 or the pre-cleaning station 642, and the process chambers 614B, 614C, 614D, and 614E.
[0029] In some embodiments, processing chambers 614A, 614B, 614C, 614D, 614E, and 614F are coupled to transfer chambers 603A, 603B. Processing chambers 614A, 614B, 614C, 614D, 614E, and 614F may include, for example, atomic layer deposition (ALD) process chambers, physical vapor deposition (PVD) process chambers, chemical vapor deposition (CVD) chambers, annealing chambers, and the like. The chambers may include any chamber suitable for performing all or part of the methods described herein, as discussed above (e.g., conformal layer ALD deposition chambers, non-conformal layer PVD deposition chambers, and gap filler material CVD deposition chambers, and the like). In some embodiments, one or more optional service chambers (shown as 616A and 616B) may be coupled to transfer chamber 603A. The service chambers 616A and 616B may be configured to perform other substrate processing (eg, degassing, orientation, substrate metrology, cooling, etc.).
[0030] The system controller 602 controls the operation of the tool 600 using direct control of the processing chambers 614A, 614B, 614C, 614D, 614E, and 614F, or alternatively, by controlling a computer (or controller) associated with the processing chambers 614A, 614B, 614C, 614D, 614E, and 614F, and the tool 600. In operation, the system controller 602 can implement data collection and feedback from the various chambers and systems to optimize the performance of the tool 600. The system controller 602 generally includes: a central processing unit (CPU) 630, a memory 634, and support circuits 632. The CPU 630 can be any form of general purpose computer processor that can be used in an industrial environment. The support circuits 632 are conventionally coupled to the CPU 630 and can include: caches, clock circuits, input / output subsystems, power supplies, etc. The software routines (e.g., as described above) may be stored in the memory 634 and, when executed by the CPU 630, switch the CPU 630 to a specific target computer (system controller) 602. The software routines may also be stored and / or executed by a second controller (not shown) located remotely from the tool 600.
[0031] Embodiments in accordance with the present principles may be implemented in hardware, firmware, software, or any combination thereof. Embodiments may also be implemented using instructions stored in one or more computer-readable media that can be read and executed by one or more processors. Computer-readable media may include: any means for storing or transmitting information in a form readable by a machine (e.g., a computing platform or a "virtual machine" executed on one or more computing platforms). For example, computer-readable media may include: any suitable form of volatile memory or non-volatile memory. In some embodiments, computer-readable media may include: non-transitory computer-readable media.
[0032] While the foregoing is of embodiments of the present principles, other and further embodiments of the present principles may be devised without departing from the basic scope thereof.
Claims
1. A method for reducing the resistivity of a metal gap filler, comprising the following steps: depositing a conformal layer in the opening of the feature and on the region of the substrate, wherein a first thickness of the conformal layer is about 10 microns or less; depositing a non-conformal metal layer directly on the conformal layer at the bottom of the opening and directly on the region using an anisotropic deposition process, wherein a second thickness of the non-conformal metal layer on the region and on the bottom of the feature is approximately 30 microns or greater; and A metal gap filler material is deposited in the opening of the feature and over the region, wherein the metal gap filler material completely fills the opening without any voids.
2. The method of claim 1, further comprising the following steps: depositing the conformal layer using an atomic layer deposition (ALD) process; depositing the non-conformal metal layer using a physical vapor deposition (PVD) process; and The metal gap filler material is deposited using a chemical vapor deposition (CVD) process.
3. The method of claim 1, wherein the first thickness is about 3 microns to about 8 microns. The method of claim 1 , wherein the second thickness is approximately 40 microns.
5. The method of claim 1, wherein the sum of the first thickness and the second thickness is at least about 40 microns.
6. The method of claim 1, wherein the conformal layer is titanium nitride, tungsten nitride, or tungsten carbonitride.
7. The method of claim 1, wherein the non-conformal metal layer is tungsten or cobalt.
8. The method of claim 1, wherein the metal gap filler material is tungsten or cobalt.
9. The method of claim 1, wherein the feature is a contact for a logic device.
10. The method of claim 1, wherein the thickness of the conformal layer is at least a monolayer.
11. The method of claim 1, wherein the method is performed in an integrated tool.
12. A method for reducing the resistivity of a metal gap filler, comprising the steps of: depositing a conformal layer of titanium nitride in the opening of the feature and on the area of the substrate using an atomic layer deposition (ALD) process, wherein a first thickness of the conformal layer of titanium nitride is about 10 microns or less; depositing a tungsten non-conformal layer directly on the titanium nitride conformal layer at the bottom of the opening and directly on the region using a plasma vapor deposition (PVD) process, wherein a second thickness of the tungsten non-conformal layer on the region and on the bottom of the feature is about 30 microns to about 50 microns; and A tungsten gap filler material is deposited in the opening of the feature and on the region using a chemical vapor deposition (CVD) process, wherein the tungsten gap filler material completely fills the opening without any gaps.
13. The method of claim 12, wherein the first thickness is about 3 microns to about 8 microns.
14. The method of claim 12, wherein the second thickness is approximately 40 microns.
15. The method of claim 12, wherein the sum of the first thickness and the second thickness is at least about 40 microns.
16. The method of claim 12, wherein the feature is a contact for a logic device.
17. The method of claim 12, wherein the thickness of the titanium nitride conformal layer is at least a monolayer.
18. The method of claim 12, wherein the method is performed in an integrated tool.
19. A non-transitory computer readable medium having instructions stored thereon, which when executed cause a method for reducing the resistivity of a metal gap filler to be performed, the method comprising the steps of: depositing a conformal layer in the opening of the feature and on the region of the substrate, wherein a first thickness of the conformal layer is about 10 microns or less; depositing a non-conformal metal layer directly on the conformal layer at the bottom of the opening and directly on the region using an anisotropic deposition process, wherein a second thickness of the non-conformal metal layer on the region and on the bottom of the feature is about 30 microns to about 50 microns; and A metal gap filler material is deposited in the opening of the feature and over the region, wherein the metal gap filler material completely fills the opening without any gaps.
20. The non-transitory computer readable medium of claim 19, the method further comprising the steps of: depositing the conformal layer using an atomic layer deposition (ALD) process; depositing the non-conformal metal layer using a plasma vapor deposition (PVD) process; and The metal gap filler material is deposited using a chemical vapor deposition (CVD) process.