Gas diffuser mounting plate for reducing particle generation

Abstract

A gas diffuser assembly for a vacuum chamber is provided. [Solution] The gas diffuser assembly includes a mounting plate (168) having a hub, a plurality of curved spokes (210) extending radially from the hub, gusset portions connected between the hub (215) and each of the curved spokes, each gusset portion having an axially arranged angled flat surface, and one or more mounting holes positioned adjacent to the curved spokes.

Description

[Technical field]

[0001] TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to a mounting plate for a gas or plasma diffuser utilized in a plasma chamber. [Background technology]

[0002]

[0002] Plasma enhanced chemical vapor deposition (PECVD) is a deposition method in which process gases are introduced into a process chamber through a backing plate, through a diffuser, and then into a gas distribution showerhead. The showerhead is electrically biased so that the process gases are ignited into a plasma. A pedestal positioned opposite the showerhead is electrically grounded and serves as the anode and substrate support. The plasma of the process gases forms one or more films on the substrate.

[0003] Periodic chamber cleaning of internal chamber components is accomplished by flowing a plasma of cleaning gas radicals along and through the same flow path as the process gas. For example, the cleaning gas is ignited outside the process chamber into a plasma and flows through a backing plate, diffuser, and showerhead. The plasma of the cleaning gas radicals is typically at about 400° C. or higher and expands a portion of the flow path. After cleaning, the portion of the gas flow path is gradually cooled. This thermal cycle is repeated multiple times during production.

[0004]

[0004] However, thermal cycles cause parts of the gas flow path to expand and contract at different rates. Differential expansion between adjacent parts causes these parts to rub against each other, generating particles. These particles are then entrapped in the flow path and contaminate the chamber. Particles remaining in the flow path can become entrapped in the process gas stream, thereby contaminating the substrate during the deposition process. Particulate contamination of the substrate reduces yield.

[0005] Therefore, what is needed is an apparatus and method for a mounting plate to support a gas diffuser in a processing chamber. Summary of the Invention

[0006]

[0006] Embodiments of the present disclosure generally provide apparatus and methods for a gas diffuser assembly for a vacuum chamber, the gas diffuser assembly comprising a mounting plate having a hub, a plurality of curved spokes extending radially from the hub, a gusset portion connected between the hub and each of the curved spokes, each of the gusset portions having an axially disposed convex curve, and one or more mounting holes connected to the curved spokes.

[0007]

[0007] In another embodiment, a gas diffuser assembly for a vacuum chamber is described that includes a mounting plate having a hub, a plurality of spokes extending radially from the hub, gusset portions connected between the hub and each of the spokes, each of the gusset portions having an axially disposed convex curve, one or more mounting holes connected to the curved spokes, and a screw hole formed in the hub.

[0008] In another embodiment, a gas diffuser assembly for a vacuum chamber is described that includes a mounting plate having a gas deflector coupled to the mounting plate by a single fastener, the mounting plate including a hub, a plurality of curved spokes extending radially from the hub, and one or more mounting holes coupled to the curved spokes.

[0009]

[0009] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the present disclosure briefly summarized above can be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the present disclosure may admit of other equally effective embodiments, and therefore, the accompanying drawings illustrate only typical embodiments of the present disclosure, and should not be considered as limiting the scope of the present disclosure. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional side view of one embodiment of a chamber; [Diagram 2] 1 is a partial schematic cross-sectional view of a chamber having a gas diffuser support assembly according to an embodiment of the present disclosure. [Figure 3A] 3A is a bottom plan view of a portion of the diffuser assembly taken along line 3A-3A of FIG. 2. [Figure 3B] FIG. 3B is a cross-sectional side elevation view of the mounting plate of FIG. 3A. [Figure 4A] FIG. 2 is a bottom plan view of another embodiment of a mounting plate that can be utilized as the mounting plate of FIG. 1. [Figure 4B] FIG. 4B is a cross-sectional side elevation view of the mounting plate of FIG. 4A. [Figure 5A] FIG. 2 is a bottom plan view of another embodiment of a mounting plate that can be utilized as the mounting plate of FIG. 1. [Figure 5B] FIG. 5B is a cross-sectional side elevation view of the mounting plate of FIG. 5A. [Figure 6A] FIG. 2 is a bottom plan view of another embodiment of a mounting plate that can be utilized as the mounting plate of FIG. 1. [Figure 6B] FIG. 6B is a cross-sectional side elevation view of the mounting plate of FIG. 6A. [Figure 7A] FIG. 2 is a bottom plan view of another embodiment of a mounting plate that can be utilized as the mounting plate of FIG. 1. [Figure 7B] FIG. 7B is a cross-sectional side elevation view of the mounting plate of FIG. 7A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011]

[0022] For ease of understanding, wherever possible, like reference numerals have been used to designate like elements common to the figures. Moreover, it is believed that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0012]

[0023] Embodiments of the present disclosure generally provide an apparatus and method for supporting a gas diffuser in a processing chamber. The present disclosure is described below in the context of a plasma enhanced chemical vapor deposition (PECVD) apparatus available from AKT America, Inc., a subsidiary of Applied Materials, Inc., of Santa Clara, Calif. It should be understood that the present disclosure is also applicable to other deposition chambers, including deposition chambers and PECVD apparatus available from other manufacturers.

[0013]

[0024] 1 is a schematic cross-sectional side view of one embodiment of a chamber 100. The chamber 100 is suitable for a PECVD process for fabricating circuits on a large area substrate 105 made of glass, polymer, or other suitable substrate. The chamber 100 is configured to form structures and devices on the large area substrate 105 for use in fabricating liquid crystal displays (LCDs) or flat panel displays, photovoltaic devices for solar cell arrays, or other structures. The structures may be multiple back channel etch inverted staggered (bottom gate) thin film transistors, which may include multiple successive deposition and masking steps. Other structures may include pn junctions to form diodes for photovoltaic cells.

[0014]

[0025] The chamber 100 includes chamber sidewalls 110, a bottom 115, and a substrate support 120 (e.g., a pedestal) that supports the large area substrate 105 during processing. A gas distribution showerhead 145 is positioned opposite the substrate support 120 and the large area substrate 105. The chamber 100 includes a port 125, such as a slit valve opening, that can be selectively opened and closed to facilitate insertion and removal of the large area substrate 105 from the chamber 100. The chamber 100 further includes a lid structure 130, a backing plate 140, and the gas distribution showerhead 145. The lid structure 130 includes a lid plate 135. In one embodiment, the lid structure 130 supports the backing plate 140 and the gas distribution showerhead 145. In one embodiment, an inner surface 146 of the backing plate 140 and an inner surface 147 of the chamber sidewalls 110 define a variable pressure region 148. In one aspect, the chamber 100 comprises a body including a chamber sidewall 110, a bottom 115, and a backing plate 140 that define a variable pressure region 148. The backing plate 140 is sealed at its periphery by a suitable O-ring at the interface where the backing plate 140 and the lid structure 130 may contact one another. The O-ring seals the variable pressure region 148 and facilitates electrical insulation when a negative pressure is applied by a vacuum pump coupled to the chamber 100.

[0015]

[0026] In one embodiment, the gas distribution showerhead 145 is supported at a central region of the backing plate 140 by one or more central support members 150. The one or more central support members 150 facilitate support of the gas distribution showerhead 145 at a central region of the gas distribution showerhead 145, control the horizontal profile of the gas distribution showerhead 145, and reduce the tendency of the gas distribution showerhead 145 to sag or bow due to one or a combination of heat, gravity, and vacuum. The gas distribution showerhead 145 can be supported around its periphery by a flexible suspension 155. The flexible suspension 155 is adapted to support the gas distribution showerhead 145 at its edges and allow for lateral expansion and contraction of the gas distribution showerhead 145.

[0016]

[0027] The chamber 100 is coupled to a gas inlet 160 that is coupled to a gas and plasma source 165. The plasma source 165 may be a direct current or radio frequency (RF) power source. The RF power source may be inductively or capacitively coupled to the chamber 100. The gas inlet 160 routes process gases from the gas source through a bore 162 to a gas diffuser assembly 164. The gas diffuser assembly 164 includes a perforated gas deflector 166 and a mounting plate 168. The mounting plate 168 is coupled to the backing plate 140 by a number of fasteners 169. The gas deflector 166 is fixed to the center of the mounting plate 168. The gas deflector 166 receives gas passing from the bore 162 to the mounting plate 168.

[0017]

[0028] The backing plate 140, the gas deflector 166, and the mounting plate 168 may all comprise a metallic material such as aluminum.

[0018]

[0029] Gases flow through the bore 162 to the mounting plate 168 and are spread by the gas deflector 166 to an intermediate region 170 defined between the backing plate 140 and the gas distribution showerhead 145. In one example of operation, a gas source provides process gases while the interior of the chamber 100 is pumped down to an appropriate pressure by a vacuum pump. One or more process gases flow through the gas inlet 160 to the mounting plate 168 and the gas deflector 166 to the intermediate region 170 defined between the backing plate 140 and the gas distribution showerhead 145. The one or more process gases then flow from the intermediate region 170 through a number of openings or gas passages 175 formed through the gas distribution showerhead 145 to a process region 180 defined in the region below the gas distribution showerhead 145 and above the substrate support 120.

[0019]

[0030] By moving the substrate support 120 towards the gas distribution showerhead 145, the large area substrate 105 is lifted from the transfer position into a processing region 180. The height of the processing region 180 can be varied as a processing parameter based on the spacing between the lower surface of the gas distribution showerhead 145 and the substrate receiving surface 190 of the substrate support 120. The substrate support 120 can be heated by an integral heater (e.g., a heating coil or a resistive heater coupled to or disposed within the substrate support 120).

[0020]

[0031] A plasma may be formed in the processing region 180 by a plasma source 165 coupled to the chamber 100. A plasma excited gas is deposited thereon to form structures on the large area substrate 105. In one embodiment, the substrate support 120 is at ground potential to facilitate plasma formation in the processing region 180. Additionally, plasma may be formed in the chamber 100 by other means, such as thermal induced plasma. In this embodiment, the plasma source 165 is shown as being coupled to the gas inlet 160, however, the plasma source 165 may be coupled to the gas distribution showerhead 145 or other portions of the chamber 100.

[0021]

[0032] After processing the substrate 105, the substrate 105 is removed from the chamber 100 and a cleaning process is performed. A cleaning gas, such as a fluorine-containing gas, is provided from a cleaning gas source 184. The cleaning gas is ignited into a plasma in a remote plasma chamber 186. The plasma of the cleaning gas flows through the bore 162 of the gas inlet 160 and through the mounting plate 168, where the plasma is spread by the gas deflector 166. The plasma then flows through the gas passages 175 of the gas distribution showerhead 145 to clean the interior surfaces of the chamber.

[0022]

[0033] In conventional gas diffusers, the mounting plate for the deflector includes a separate component bolted or otherwise fastened to the underside of the mounting plate 140. However, the high temperature plasma causes differential expansion between the backing 140 and the mounting plate, and / or within the body of the mounting plate itself. The continuous thermal cycling of the chamber 100 causes parts of the conventional gas diffuser to rub against the backing plate 140, particularly the conventional mounting plate, generating particles. For example, the mounting points of the conventional mounting plate expand and rub against the backing plate, generating particles. Additionally, the fasteners utilized to connect the conventional gas diffuser to the backing plate 140 include an anodized coating. The anodized coating can wear away due to the differential expansion, and the wear generates more particles. It has been found that the particles are entrained in the gas flow within the chamber 100, and some of the particles contaminate the substrate.

[0023]

[0034] 2 is a partial schematic cross-sectional view of the chamber 100 having a gas diffuser assembly 164 according to one embodiment of the present disclosure. The gas diffuser assembly 164 includes a mounting plate 168 coupled to the backing plate 140 and a gas deflector 166 coupled to the mounting plate 168.

[0024]

[0035] Figure 3A is a bottom plan view of a portion of gas diffuser assembly 164 taken along line 3A-3A of Figure 2. Figure 3B is a side elevation view of mounting plate 168 of Figure 3A.

[0025]

[0036] 2, 3A, and 3B, the mounting plate 168 includes a plurality of apertures 205A-205D (shown as 205 in FIG. 2). Each aperture 205A-205D is separated by a spoke 210. Each spoke 210 is joined to the geometric center of the backing plate 140 at a hub 215.

[0026]

[0037] In the illustrated embodiment, each spoke 210 is joined around its periphery to a circular mounting structure 300. The mounting structure 300 includes a plurality of circular arc segments 305. Each of the plurality of circular arc segments 305 includes a mounting hole 310. Each mounting hole 310 receives one of the fasteners 169 (shown in FIG. 2).

[0027]

[0038] Each spoke 210 includes an intersecting structure 220. Each opening 205A-205D is provided as a quadrant separated by spokes 210. Each opening 205A-205D is sized to maximize gas flow or electrical conductivity. The open area of ​​openings 205A-205D is increased by about 50% or more using the intersecting structures 220 described herein over conventional gas diffusion devices. In one embodiment, the open area of ​​openings 205A-205D is about 7 square inches.

[0028]

[0039] As shown in FIG. 3A , the spokes 210 have a first or proximal end 312 and a second or distal end 315, radially from the hub 215. The distal end 315 of each spoke 210 includes an obtuse radial portion 320 and an acute radial portion 325. In some embodiments, the proximal end 312 of each spoke 210 includes an acute radial portion 330 and an obtuse radial portion 335. A distal body 340 is formed by the obtuse and acute portions 320 and 325 of the spokes 210. In some embodiments (shown in FIGS. 4A , 5A , 6A , and 7A ), the attachment holes 310 are formed in the distal body 340.

[0029]

[0040] 3B , the mounting plate 168 includes a first thickness or height 345 in the axial direction 342. The first height 345 includes the hub 215. The mounting plate 168 includes a second thickness or height 350 in the axial direction 342 that is shorter than the first height 345. The second height 350 includes the mounting holes 310. The mounting plate 168 includes a third thickness or height 355 in the axial direction 342 that is shorter than the second height 350. The third height 355 includes the thickness of a major portion of each spoke 210.

[0030]

[0041] In some embodiments, the hub 215 of the mounting plate 168 includes a flat surface 360. The mounting plate 168 shown in FIG. 3B further includes gussets 365 disposed between the hub 215 and the spokes 210. Each gusset 365 has a thickness or height between the first height 345 and the third height 355. In the illustrated embodiment, the gussets 365 include a convex curve 370 in the axial direction 342 transitioning from the spokes 210 to the hub 215.

[0031]

[0042] 2, the mounting plate 168 is coupled to the mounting plate 140 by a number of fasteners 169. The gas deflector 166 is coupled to the mounting plate 168 by a single fastener 225. The fastener 225 is a bolt or a screw, such as a shoulder screw. The fastener 225 couples to a threaded hole 275 (shown in phantom in FIG. 3A ) formed in the hub 215. Additionally, the fastener 225 maintains a gap 230 between an upper surface 235 of the gas deflector 166 and a lower surface 240 of the backing plate 140 and / or the mounting plate 168.

[0032]

[0043] In operation, gas from a gas source of FIG. 1 or a plasma of a cleaning gas from the remote plasma chamber 186 of FIG. 1 flows through the bore 162. The flow follows a conductance path through openings 205A-205D in the mounting plate 168 into an intermediate region 170 defined between the backing plate 140 and the gas distribution showerhead 145. The conductance path includes a number of flow paths, including, for example, a lateral flow path 245 around the gas deflector 166 and a downward flow path 250 through a number of through-holes 255 formed in the gas deflector 166. The conductance path continues to the processing region 180 via a flow path 260 through a gas passage 175 formed through the gas distribution showerhead 145.

[0033]

[0044] The spokes 210 are spaced at 90 degree intervals within the cross structure 220. In one embodiment, the spokes 210 are curved along their length or radial direction. This curved configuration and the thickness (third height 355) of the spokes 210 provide flexibility during temperature fluctuations, which allows the mounting plate 168 to expand and contract in areas away from the fasteners 169. This prevents rubbing contact between the backing plate 140 and the mounting plate 168, minimizing particle generation.

[0034]

[0045] In one embodiment, the gap 230 (between the backing plate 140 and the gas deflector 166) is about 0.15 inches to about 0.5 inches. In one embodiment, the gap 230 is about 0.25 inches.

[0035]

[0046] In one embodiment, the through-holes 255 are evenly distributed across a major surface of the gas deflector 166. In one embodiment, each through-hole 255 has a diameter between about 0.05 inches and about 0.2 inches. In one embodiment, each through-hole 255 has a diameter of about 0.1 inches.

[0036]

[0047] 2, the gas deflector 166 substantially blocks a majority of the vertically downward gas or plasma flow 265 from the bore 162, creating a substantially horizontal lateral flow path 245 that is substantially parallel to the backing plate 140 and the gas distribution showerhead 145. A small portion of the vertically downward gas or plasma flow 265 passes through a plurality of through-holes 255 in the gas deflector 166, creating a downward flow path 250 that is generally parallel to the longitudinal axis 270 of the backing plate 140 and / or the chamber 100.

[0037]

[0048] Figure 4A is a bottom plan view of another embodiment of a mounting plate 400, which may be utilized as mounting plate 168 of Figure 1. Figure 4B is a side elevation view of mounting plate 400 of Figure 4A.

[0038]

[0049] Mounting plate 400 is similar to mounting plate 168 with the following exceptions: mounting plate 400 does not include circular mounting structures 300 as shown in FIG. 3A. Instead, mounting holes 310 are positioned at the ends of spokes 210 in distal body 340. Additionally, gusset portion 365 includes angled flats 405 that transition from spokes 210 to hub 215.

[0039]

[0050] Figure 5A is a bottom plan view of another embodiment of a mounting plate 500, which may be utilized as mounting plate 168 of Figure 1. Figure 5B is a side elevation view of the mounting plate 500 of Figure 5A.

[0040]

[0051] Mounting plate 500 is similar to mounting plate 400 with the following exceptions: hub 215 of mounting plate 500 includes a curved surface 505 (shown in FIG. 5B). Mounting plate 500 further includes a gusset portion 365 having a convexly curved portion 510 having a radius substantially similar to the radius of curved surface 505. Convexly curved portion 510 is connected to spokes 210 by concave portions 515 that are radially outward of convexly curved portion 510.

[0041]

[0052] Figure 6A is a bottom plan view of another embodiment of a mounting plate 600, which may be utilized as mounting plate 168 of Figure 1. Figure 6B is a side elevation view of mounting plate 600 of Figure 6A.

[0042]

[0053] Mounting plate 600 is similar to mounting plate 500 with the following exceptions: mounting plate 500 includes a gusset portion 365 having a convexly curved portion 510 with a radius substantially similar to the radius of curved surface 505. Convexly curved portion 510 is connected to spokes 210 by angled surfaces 605 that are radially outward of convexly curved portion 510.

[0043]

[0054] Figure 7A is a bottom plan view of another embodiment of a mounting plate 700, which may be utilized as mounting plate 168 of Figure 1. Figure 7B is a side elevation view of mounting plate 700 of Figure 7A.

[0044]

[0055] Mounting plate 700 is similar to mounting plate 600 or mounting plate 400 of Figures 4A-4B with the following exceptions: Mounting plate 500 includes gusset portion 365 having angled flat surface 405, but further includes an angled perimeter region 705 at the end of hub 215.

[0045]

[0056] The gas diffuser assembly 164 described herein substantially eliminates particle formation and other problems encountered with conventional gas diffusion devices. Stresses that can cause rubbing between parts are significantly reduced in the gas diffuser assembly 164 described herein compared to conventional gas diffusion devices. For example, the maximum lateral deformation of the mounting plate described herein is reduced by over 10%. The maximum vertical deformation is reduced by over 98% using the mounting plate described herein. As described herein, the maximum Von-Mises stress is reduced by approximately 80% using the mounting plate described herein. The reaction force (representing friction between the backing plate 140 and the conventional gas diffusion device) is reduced by 99% using the mounting plate described herein. The reaction moment (representing rubbing between the mounting hardware of the conventional gas diffusion device) is reduced by 98% using the mounting plate described herein.

[0046]

[0057] While the above description is directed to embodiments of the present disclosure, other and additional embodiments of the disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the claims that follow.

Claims

1. 1. A gas diffuser assembly for a vacuum chamber, comprising: A mounting plate comprising: Hub and a plurality of curved spokes extending radially from the hub; a gusset portion coupled between the hub and each of the curved spokes, each of the gusset portions having an axially disposed angled flat surface; one or more attachment holes positioned adjacent the curved spokes; Mounting plate with Equipped with a gas diffuser assembly, wherein the angled plane is angled such that a distance between the angled plane and a plate surface of the mounting plate decreases along a direction from the hub toward the curved spokes.

2. The gas diffuser assembly of claim 1 , wherein each of said mounting holes is formed in a circular mounting structure between said curved spokes.

3. The gas diffuser assembly of claim 1 , wherein one of the one or more mounting holes is positioned at a distal end of each of the curved spokes.

4. The gas diffuser assembly of claim 1 , wherein each of the curved spokes includes a distal body.

5. The gas diffuser assembly of claim 4 , wherein each of the curved spokes includes an acute angled portion and an obtuse angled portion at the distal body.

6. The gas diffuser assembly of claim 1 , wherein each of the curved spokes includes an acute angle portion and an obtuse angle portion.

7. The gas diffuser assembly of claim 1 , wherein the hub includes a flat surface.

8. The gas diffuser assembly of claim 1 , wherein the hub includes a curved surface.

9. The gas diffuser assembly of claim 1 , wherein each of the curved spokes includes an obtuse angled portion adjacent the gusset portion.

10. 1. A gas diffuser assembly for a vacuum chamber, comprising: A mounting plate comprising: Hub and a plurality of curved spokes extending radially from the hub; a gusset portion coupled between the hub and each of the curved spokes, each of the gusset portions having an axially disposed angled flat surface; one or more attachment holes positioned adjacent the curved spokes; a threaded hole formed in the hub; Mounting plate with Equipped with a gas diffuser assembly, wherein the angled plane is angled such that a distance between the angled plane and a plate surface of the mounting plate decreases along a direction from the hub toward the curved spokes.

11. The gas diffuser assembly of claim 10 , wherein each of the mounting holes is formed in a circular mounting structure between the curved spokes.

12. The gas diffuser assembly of claim 10 , wherein one of the one or more mounting holes is positioned at a distal end of each of the curved spokes.

13. The gas diffuser assembly of claim 10 , wherein each of the curved spokes includes a distal body.

14. The gas diffuser assembly of claim 13 , wherein each of the curved spokes includes an acute angled portion and an obtuse angled portion at the distal body.

15. The gas diffuser assembly of claim 10 , wherein each of the curved spokes includes an acute angle portion and an obtuse angle portion.

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