Titanium tungsten (TiW) target for physical vapor deposition (PVD) chamber for particle improvement

Abstract

A target assembly for a PVD chamber is provided herein. In some embodiments, a target assembly for a PVD chamber includes: a back plate; and a target coupled to the backing plate and having a substrate facing surface opposite the backing plate, where a peripheral portion of the target includes an angled surface extending radially outward and toward the backing plate, wherein a surface roughness of an annular portion of the angled surface is greater than a surface roughness of a remaining portion of the substrate facing surface of the target.

Description

Technical Field

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

[0002] Tungsten and titanium films are often used in the manufacture of semiconductor devices, for example as diffusion barriers between silicon substrates and aluminum alloy metallizations. Titanium tungsten (TiW) films are formed by sputtering a titanium tungsten target.

[0003] During the sputtering process, titanium-tungsten material is sputtered from the surface of the target and deposited onto a substrate disposed opposite the surface of the target. However, the inventors have observed that nodules may form on the sputtering surface of the target when material from the central portion of the target is sputtered and redeposited on the peripheral edge of the target face rather than on the substrate. In addition, the nodules may flake or peel and generate particles that contaminate and adversely affect the quality of the titanium-tungsten film deposited on the substrate and shorten the life of the target assembly.

[0004] Therefore, the inventors provide embodiments of improved targets for extending the life of target assemblies. Summary of the invention

[0005] A target assembly for a PVD chamber is provided herein. In some embodiments, a target assembly for a PVD chamber includes: a backing plate; and a target coupled to the backing plate and having a substrate facing surface opposite the backing plate, wherein a peripheral portion of the target includes an angled surface extending radially outward and toward the backing plate, wherein a surface roughness of an annular portion of the angled surface is greater than a surface roughness of a remainder of the substrate facing surface of the target.

[0006] In some embodiments, a target assembly for a PVD chamber includes: a backing plate; and a target coupled to the backing plate and having a substrate-facing surface opposite the backing plate, wherein a peripheral portion of the target includes an angled surface extending radially outward and toward the backing plate, wherein about 45% to about 55% of the angled surface has a surface roughness greater than the surface roughness of the remainder of the angled surface.

[0007] In some embodiments, a processing chamber includes: a chamber body having an interior space therein; a substrate support member disposed in the interior space, the substrate support member being used to support a substrate thereon; and a target assembly coupled to the chamber body, the target assembly including: a backing plate; and a target material, the target material being coupled to the backing plate and having a surface facing the substrate, the substrate facing surface being opposite to the backing plate, wherein a peripheral portion of the target material includes an angled surface, the angled surface extending radially outward and toward the backing plate, wherein a surface roughness of an annular portion of the angled surface is greater than a surface roughness of a remaining portion of the substrate facing surface of the target material.

[0008] Other and further embodiments of the disclosure are described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The embodiments of the present disclosure have been briefly summarized above and discussed in more detail below, and can be understood by referring to the exemplary embodiments of the present disclosure illustrated in the attached drawings. However, the attached drawings only illustrate typical embodiments of the present disclosure, and since the present disclosure may allow other equivalent embodiments, the attached drawings shall not be regarded as limiting the scope of the present disclosure.

[0010] Figure 1A A schematic side view of a PVD chamber is shown, in accordance with at least some embodiments of the present disclosure.

[0011] Figure 1B According to at least some embodiments of the present disclosure Figure 1A Detail of 1B is the enlarged indicated area.

[0012] Figure 2 A bottom view of a target assembly according to at least some embodiments of the present disclosure is shown.

[0013] Figure 3 A cross-sectional side view of a target assembly according to at least some embodiments of the present disclosure is shown.

[0014] Figure 4 An enlarged cross-sectional side view of a portion of a target assembly is depicted in accordance with at least some embodiments of the present disclosure.

[0015] For ease of understanding, the same reference numerals are used to represent the same components in the drawings, where possible. The drawings are not drawn to scale and may be simplified for clarity. Components and features in one embodiment may be advantageously used in other embodiments without further description. DETAILED DESCRIPTION

[0016] Embodiments of target assemblies for use in PVD chambers are provided herein. Target assemblies may have delamination issues, for example, when the target is near the end of the target life, especially in the edge areas of the target assembly. Delamination from the target assembly may fall on and contaminate the substrate being processed in the PVD chamber. However, the inventors have observed that by texturing certain areas of the target, the life of the target can be extended, and by extending the life of the target, the life of the chamber can be extended. For example, delamination can be reduced, prevented, or the onset of delamination can be delayed by texturing an area near the edge of the target. The texturing process can be performed, for example, via one or more of twin wire arc spraying, abrasive media, and the like. In some embodiments, the target assembly can be degreased, cleaned, rinsed, and dried prior to texturing.

[0017] Figure 1A A schematic side view of a PVD chamber is shown, in accordance with at least some embodiments of the present disclosure. Figure 1B According to at least some embodiments of the present disclosure Figure 1A 1B is an enlarged indication area of ​​detail. Relative terms (e.g., top, bottom, front, or back) are used herein for clarity and consistency with the views shown in the drawings, and are not intended to limit the scope of the present disclosure, which may be implemented in configurations other than those shown herein. In general, a PVD chamber or processing chamber 100 includes a sputtering source, such as a target assembly 150 including a target 152 (e.g., source material) and a backing plate 154, which will be described in more detail below. The processing chamber 100 includes a chamber body 106, which together with the target assembly 150 defines an interior space 140 of the processing chamber 100. A substrate support 102 for receiving a substrate 104 (e.g., a semiconductor substrate) is disposed in the interior space 140 opposite the target assembly 150. The chamber body 106 may include a sidewall 105 coupled to a bottom chamber wall 108. The chamber body 106 may be grounded via a ground 117. In some embodiments, the chamber body 106 is made of aluminum.

[0018] In some embodiments, the target 152 is made of a source material including titanium tungsten (TiW). In some embodiments, the source material consists essentially of titanium (Ti) and tungsten (W). In some embodiments, the source material of the target 152 comprises about 90 weight percent tungsten (W) and about 10 weight percent titanium (Ti). In some embodiments, the source material of the target 152 has a density (i.e., weight / volume) of at least about 98%.

[0019] In general, titanium-tungsten targets are made by mixing tungsten raw material powder and titanium raw material powder. The resulting mixture is compacted and heated using an appropriate forming method (e.g., inert gas hot pressing, vacuum hot pressing, hot isostatic pressing, cold pressing / sintering, or the like). The inventors have observed that adjusting the average grain size of the tungsten raw material powder and the titanium raw material powder can reduce titanium-rich or tungsten-rich regions, thereby advantageously reducing or eliminating nodule formation and peeling. In some embodiments, the average grain size of the titanium powder is less than or equal to the average grain size of the tungsten powder. For example, in some embodiments, the average grain size of the titanium grains is less than about 25 μm, or less than about 20 μm in some embodiments. In some embodiments, the average grain size of the tungsten grains is from about 20 μm to about 45 μm.

[0020] The substrate support 102 supports a substrate 104 to be sputter coated in planar opposition to the substrate facing surface 132 or sputtering surface plane of the target assembly 150. The substrate support 102 has a flat substrate receiving surface disposed opposite and generally parallel to the sputtering surface of the target assembly 150. The substrate support 102 is vertically movable by a bellows (not shown) connected to the bottom chamber wall 108 to allow the substrate 104 to be transferred onto the substrate support 102 through a slit valve (not shown) in the lower portion of the chamber body 106 and subsequently raised to a deposition position.

[0021] In some embodiments, the grounded conductive cathode assembly 107 is coupled to the sidewall 105. In some embodiments, a rotatable magnetron 118 is coupled to the grounded conductive cathode assembly 107, which is positioned behind the backing plate 154 and the target assembly 150. In some embodiments, the target assembly 150 is coupled to the grounded conductive cathode assembly 107 via a fastener 109 extending through the backing plate 154. The rotatable magnetron 118 may include a plurality of magnets 120 (such as the magnets schematically shown) supported by a base plate 122, which is connected to a rotation axis 124 that coincides with the central axis of the chamber body 106 and the substrate 104. The plurality of magnets 120 may be arranged in a closed pattern, such as having a kidney shape. The magnets 120 generate a magnetic field within the interior space 140 that is substantially parallel to and proximate to the substrate-facing surface 132 to capture electrons and increase the local plasma density, which in turn may increase the sputtering rate. The magnet 120 generates an electromagnetic field around the top of the processing chamber 100 , and the magnet 120 can be rotated to rotate the electromagnetic field, which affects the plasma density of the process to sputter the target 152 more uniformly.

[0022] Process gas may be supplied from a gas source 110 through a mass flow controller 112 into the interior space 140, for example adjacent to the substrate support 102. An RF power supply 116 may be connected to the substrate support 102 to induce a negative DC self-bias on the substrate 104 - although in other applications, the substrate support 102 may be grounded or held electrically floating - and a controllable DC power supply 114 coupled to the processing chamber 100 may be used to apply a negative voltage or bias to the target assembly 150.

[0023] Continue to refer Figure 1A , the processing chamber 100 includes a grounded shield 126 having an upper portion 128 including a flange 129 supported on and electrically connected to a lug 130 of the sidewall 105. The shield 126 also includes an elongated portion 125 extending downwardly from the upper portion 128 along the sidewall 105 and a bottom 127 coupled to the bottom surface 101 of the substrate support 102 via one or more suitable coupling devices (e.g., screws, bolts, clips, etc.). The shield 126 can be formed, for example, from hard, non-magnetic stainless steel.

[0024] refer to Figure 1B , the upper portion 128 of the shield 126 fits tightly in an annular recess formed between the front surface or substrate-facing surface 162 of the backing plate 154 and the outer sidewall 134 of the target 152. The inner corner 136 of the upper portion 128 and the outer sidewall 134 of the target 152 define a gap 138 therebetween. The gap 138 is narrow enough to prevent plasma from penetrating between the inner corner 136 and the outer sidewall 134, thereby protecting other components within the processing chamber 100 (such as the dielectric isolator 123 ( Figure 1A and 1B )) is protected from being sputter coated with a metal layer, which may cause electrical shorting of the target 152 by other components within the processing chamber 100. The top surface 133 of the shield 126 is spaced apart from the substrate-facing surface 162 of the backing plate 154. In some embodiments, the backing plate 154 includes an O-ring groove 172 configured to receive an O-ring 178 for providing a seal between the backing plate 154 and the dielectric isolator 123.

[0025] Figure 2 A bottom view, or substrate-facing view, of a target assembly 150 is depicted in accordance with at least some embodiments of the present disclosure. Figure 3A cross-sectional side view of a target assembly 150 is depicted in accordance with at least some embodiments of the present disclosure. The backing plate 154 includes an inner portion 210 and an outer portion 218, the inner portion 210 being used to bond the target 152 to the backing plate 154. The outer portion 218 can include a plurality of features disposed therethrough, such as holes 204, notches 220 (e.g., three), slits 216 (e.g., two), openings 232 for power connections, and the like.

[0026] The holes 204 are configured, for example, to receive one or more types of fasteners (e.g., screws, bolts, etc.) for mounting the backing plate 154 including the target 152 to the processing chamber 100, for example, to the conductive cathode assembly 107. The notches 220 are configured to help align the holes 204 of the backing plate 154 with corresponding holes on the conductive cathode assembly 107 when mounting the backing plate 154 to, for example, the conductive cathode assembly 107. The backing plate 154 can be mounted via the fasteners 109. The slits 216 are configured to provide an exhaust path for gas from the O-ring groove 172 when the target assembly 200 is mounted. For example, the openings 232 can be configured to receive features for coupling the target assembly 150 to a power source, such as the DC power source 114.

[0027] like Figure 3 As shown, the substrate-facing surface 132 of the target 152 includes an angled surface 230 at a peripheral portion 236 of the target 152. The angled surface 230 is disposed radially inward from the outer portion 218 of the backing plate 154. The angled surface 230 is generally annular and extends radially outward and toward the backing plate 154. In some embodiments, the angled surface 230 begins at a distance of about 7.9 inches to about 8.2 inches from the central axis 320 of the target assembly 150.

[0028] Figure 4 An enlarged cross-sectional side view of a portion of a target assembly according to at least some embodiments of the present disclosure is depicted. The surface roughness of the annular portion 410 of the angled surface 230 is greater than the surface roughness of the remainder of the substrate-facing surface 132 of the target 152. In some embodiments, the annular portion 410 of the angled surface 230 is about 45% to about 55% of the total length of the angled surface 230. In some embodiments, the angled surface 230 extends at an angle 412 of about 12 degrees to about 17 degrees. In some embodiments, the annular portion 410 is a bead blasted surface.

[0029] In some embodiments, the surface roughness of the annular portion 410 is greater than about 200 micro-inches roughness average (RA). For example, in some embodiments, the annular portion 410 has a surface roughness of about 250 micro-inches roughness average to about 300 micro-inches roughness average (RA). In some embodiments, the annular portion 410 of the angled surface 230 extends from a distance of about 8.1 inches to about 8.6 inches from the central axis 320 of the target 152 to the outer edge 408 of the target 152, such as from the point 416 to the outer edge 408.

[0030] In some embodiments, the surface roughness of the inner sidewall 432 of the backing plate 154 adjacent to the outer edge 408 of the target 152 is greater than the surface roughness of the remainder of the substrate-facing surface 132 of the target 152. In some embodiments, a portion 414 of the substrate-facing surface 162 of the backing plate 154 has a greater surface roughness than the remainder of the substrate-facing surface 132 of the target 152. In some embodiments, the inner sidewall 432 of the backing plate 154 extends radially inward and away from the target 152.

[0031] In some embodiments, the inner sidewall 432 includes a first portion 452 proximate the outer edge 408 and a second portion 454 proximate the substrate-facing surface 162. In some embodiments, the inner sidewall 432 includes a step 442 disposed between the first portion 452 and the second portion 454. In some embodiments, the step 442 extends from a point 418 of the inner sidewall 432 to the second portion 454. In some embodiments, the step 442 extends radially inward and upward from the point 418 to the second portion 454. In some embodiments, the step 442 extends at an angle 422 of about 30 degrees to about 40 degrees. In some embodiments, the first portion 452 extends linearly. In some embodiments, the second portion 454 is curved. In some embodiments, the first portion 452 has a surface roughness substantially similar to the surface roughness of the annular portion 410. In some embodiments, the first portion 452 is sandblasted. In some embodiments, the first portion 452 has a surface roughness different from that of the second portion 454.

[0032] The backing plate 154 extends radially outward beyond the target 152, and the substrate-facing surface 162 of the backing plate 154 extends from the inner sidewall 432 of the backing plate 154 to the outer sidewall 450 of the backing plate 154. In some embodiments, a portion 414 of the substrate-facing surface 162 of the backing plate 154 has a greater surface roughness than the remainder of the substrate-facing surface 132 of the target 152. In some embodiments, the portion 414 extends from the inner sidewall 432 to a point 420. In some embodiments, the point 420 is disposed about 9 inches to about 9.5 inches from the central axis 320. In some embodiments, the O-ring groove 172 is disposed radially outward from the point 420. In some embodiments, the portion 414 of the backing plate 154 is an arc sprayed surface. In some embodiments, the second portion 454 of the inner sidewall 432 is an arc sprayed surface. In some embodiments, the portion 414 has a surface roughness of about 200 micro-inch average roughness to about 300 micro-inch average roughness (RA).

[0033] In some embodiments, portion 414 has a surface roughness that is different from the surface roughness of first portion 452 and annular portion 410. In some embodiments, portion 414 has the same surface roughness as second portion 454. In some embodiments, target assembly 150 has a similar surface finish from point 416 to point 418. In some embodiments, target assembly 150 has a similar surface roughness from point 416 to point 418. In some embodiments, target assembly 150 has a similar surface brightness from point 418 to point 420. In some embodiments, outer sidewall 450 includes a first beveled edge 462 adjacent to substrate-facing surface 162. In some embodiments, outer sidewall 450 includes a second beveled edge 464 proximate to back surface 466 of backing plate 154.

[0034] 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 of the present disclosure.

Claims

1. A target assembly for a PVD chamber, comprising: Back panel; as well as A target is coupled to the backing plate and has a substrate-facing surface opposite the backing plate, wherein a peripheral portion of the target includes an angled surface that extends radially outward and toward the backing plate, wherein at least an annular portion of the angled surface has a surface roughness greater than a surface roughness of a remainder of the substrate-facing surface of the target. 2 . The target assembly of claim 1 , wherein a surface roughness of an inner sidewall of the backing plate adjacent to an outer edge of the target is greater than a surface roughness of the remaining portion of the substrate-facing surface of the target. 3 . The target assembly of claim 2 , wherein the inner sidewall of the backing plate extends radially inward and away from the target. The target assembly of claim 2 , wherein the inner sidewall of the backing plate comprises a step.

5. The target assembly of claim 1, wherein the surface roughness of the annular portion of the angled surface is greater than about 200 microinches average roughness.

6. The target assembly of claim 1, wherein the angled surface extends at an angle of about 12 degrees to about 17 degrees.

7. The target assembly of claim 1 , wherein the backing plate extends radially outward beyond the target, and wherein the backing plate comprises a sidewall extending from an outer edge of the target to the substrate-facing surface of the backing plate, and the substrate-facing surface of the backing plate extends to an outer sidewall of the backing plate.

8. The target assembly of any one of claims 1 to 7, wherein a portion of the substrate-facing surface of the backing plate has a surface roughness that is greater than a surface roughness of the remaining portion of the substrate-facing surface of the target.

9. The target assembly according to any one of claims 1 to 7, wherein the target is made of titanium-tungsten (TiW).

10. The target assembly of any one of claims 1 to 7, wherein the annular portion of the angled surface is about 45% to about 55% of the total length of the angled surface.

11. The target assembly of claim 10, wherein the annular portion of the angled surface is a sandblasted surface, and wherein the portion of the substrate-facing surface of the backing plate is an arc sprayed surface.

12. The target assembly of claim 10, wherein the backing plate includes a substrate-facing surface radially outward from the target, and wherein a portion of the substrate-facing surface of the backing plate has a surface roughness greater than the remaining portion of the substrate-facing surface of the target.

13. The target assembly of claim 9, wherein the grain size of the tungsten in the target is about 20 microns to about 45 microns, and the grain size of the titanium in the target is about 20 microns or less.

14. The target assembly of any one of claims 1 to 7, wherein the backing plate comprises a plurality of holes for coupling the target assembly to the PVD chamber.

15. The target assembly of any one of claims 1 to 7, wherein the backing plate comprises an O-ring groove radially outward from the target.

16. A target assembly as described in any one of claims 1 to 7, wherein the surface roughness of the portion of the substrate-facing surface of the backing plate is greater than the surface roughness of the remaining portion of the substrate-facing surface of the target, wherein the target is made of titanium tungsten (TiW), and wherein the annular portion of the angled surface is about 45% to about 55% of the total length of the angled surface.

17. A target assembly as described in any one of claims 1 to 7, wherein the annular portion of the angled surface is about 45% to about 55% of the total length of the angled surface, wherein the annular portion of the angled surface is a sandblasted surface and the portion of the substrate-facing surface of the backing plate is an arc sprayed surface, wherein the backing plate includes a substrate-facing surface radially outward from the target, and wherein the surface roughness of the portion of the substrate-facing surface of the backing plate is greater than the surface roughness of the remaining portion of the substrate-facing surface of the target, and wherein the grain size of the tungsten in the target is about 20 microns to about 45 microns, and the grain size of the titanium in the target is about 20 microns or less.

18. A processing chamber comprising: a chamber body having an interior space therein; a substrate support disposed in the inner space, the substrate support being configured to support a substrate thereon; and A target assembly as claimed in any one of claims 1 to 7 coupled to the chamber body.

19. The processing chamber of claim 18, wherein the annular portion of the angled surface is about 45% to about 55% of the total length of the angled surface, and wherein the annular portion has a surface roughness of about 200 micro-inches roughness average to about 300 micro-inches roughness average (RA).

20. The processing chamber of claim 18, wherein at least one of the following is present: The target material is made of titanium-tungsten (TiW); The grain size of the tungsten in the target is from about 20 microns to about 45 microns, and the grain size of the titanium in the target is about 20 microns or less; or Wherein the annular portion of the angled surface extends from a distance of about 8.1 inches to about 8.6 inches from a central axis of the target to an outer edge of the target.

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