Gas diffuser with diffuser gas hole plug for substrate processing

Abstract

The embodiments described herein generally relate to semiconductor manufacturing, and more particularly to gas diffusers for substrate processing chambers. In one embodiment, the gas diffuser includes: at least one gas diffuser unit including: a fastening orifice extending through a top surface of a diffuser body; a first gas inlet disposed at an inlet distance from the fastening orifice; a second gas inlet disposed at the inlet distance from the fastening orifice; an orifice plug at a distal end of the fastening orifice; and a gas outlet fluidly coupled to a channel and extending through a bottom surface of the diffuser body. In another embodiment, the gas diffuser has an orifice plug portion at a distal end of the fastening orifice. In yet another embodiment, the processing chamber includes a gas diffuser coupled to a cover structure, the cover structure including a plug portion disposed in the fastening orifice of at least one gas diffuser unit.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to semiconductor manufacturing and, more particularly, to gas diffusers for substrate processing chambers. Prior Art

[0002] A centrally supported gas diffuser is a variant of a gas diffuser that holds one or more central rods. This type of diffuser is typically used when a uniform dispersion of gas over a relatively large area is required.

[0003] The centrally supported gas diffuser operates by drawing gas from a central supply line and releasing it through a series of nozzles. These nozzles are arranged symmetrically around the central rod and are designed to evenly distribute the gas over a designated area.

[0004] In substrate processing chambers, a centrally supported gas diffuser is typically located within the chamber ceiling. Integration with the central gas supply line ensures a continuous gas supply. Construction from stainless steel or similar corrosion-resistant materials is common. Routine inspection and maintenance are standard to ensure consistent functionality.

[0005] The detrimental effects of particles or debris on substrate processing include contamination, physical damage, process disruptions, and safety risks, especially in high-temperature or vacuum environments. Countermeasures are necessary to keep the substrate area free of debris and clean.

[0006] While center-supported gas diffusers are typically constructed of durable materials that resist wear and corrosion, occasional wear or particle blockage may occur over time. These events can cause particles or debris to become dislodged from the diffuser or center rod, potentially contaminating the chamber and the substrate being processed.

[0007] Therefore, a need exists for an improved center-supported gas diffuser to reduce particle contamination on substrates being processed. Summary of the Invention

[0008] Embodiments herein generally relate to semiconductor manufacturing, and more particularly to gas diffusers for substrate processing chambers.

[0009] In one embodiment, a gas diffuser is provided. The gas diffuser includes: a diffuser plate body; and a diffuser array within the diffuser plate body and including at least one gas diffuser unit, the gas diffuser unit including: a fastening aperture extending through a top surface of the diffuser plate body; a first gas inlet disposed at an inlet distance from the fastening aperture; a second gas inlet disposed at the inlet distance from the fastening aperture and opposite the first gas inlet; an aperture plug at a distal end of the fastening aperture; a channel fluidically coupled to the first gas inlet and the second gas inlet; and a gas outlet fluidically coupled to the channel and extending through a bottom surface of the diffuser plate body.

[0010] In another embodiment, a gas diffuser is provided. The gas diffuser includes: a diffuser plate body; and a diffuser array within the diffuser plate body and including at least one gas diffuser unit, the gas diffuser unit including: a fastening aperture through a top surface of the diffuser plate body; a first gas inlet disposed at an inlet distance from the fastening aperture; a second gas inlet disposed at the inlet distance from the fastening aperture and opposite the first gas inlet; a plug portion distal to the fastening aperture; a channel fluidically coupled to the first gas inlet and the second gas inlet; and a gas outlet fluidically coupled to the channel and extending through a bottom surface of the diffuser plate body.

[0011] In yet another embodiment, a processing chamber is provided. The processing chamber includes a processing region and a variable pressure region defined by sidewalls, a chamber base, and a lid structure of the processing chamber; and a gas diffuser coupled to the lid structure, the gas diffuser including a plug portion disposed in a fastening aperture of at least one gas diffuser unit. Simple diagram description

[0012] In order to enable a detailed understanding of the above-described features of the present disclosure, a more particular description of the present disclosure, briefly summarized above, may be obtained by reference to the embodiments, some of which are shown in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only exemplary embodiments of the present disclosure and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.

[0013] FIG. 1 shows a schematic cross-sectional view of a processing chamber according to certain embodiments.

[0014] FIG. 2 shows a schematic diagram of a portion of a center-supported gas diffuser according to certain embodiments.

[0015] FIG. 3A shows a schematic cross-sectional view of a portion of a diffuser array of the center-supported gas diffuser of FIG. 2 , according to certain embodiments.

[0016] FIG. 3B shows a schematic cross-sectional view of a diffuser of the diffuser array of FIG. 3A , according to certain embodiments.

[0017] FIG. 3C shows a close-up, cross-sectional view of the diffuser of FIG. 3B , according to certain embodiments.

[0018] FIG. 4A shows a schematic cross-sectional view of a portion of a diffuser array of the center-supported gas diffuser of FIG. 2 , according to certain embodiments.

[0019] FIG. 4B shows a schematic cross-sectional view of a diffuser of the diffuser array of FIG. 4A , according to certain embodiments.

[0020] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. Implementation Method

[0021] Embodiments herein generally relate to semiconductor manufacturing, and more particularly to gas diffusers for substrate processing chambers.

[0022] Centrally supported gas diffusers, supported by one or more central rods, are used to evenly distribute gas over a large area. They draw gas from a central supply line and release it through nozzles arranged around the rod(s). Compared to other distribution methods, they offer advantages in ensuring precise gas release and simplifying maintenance.

[0023] In substrate processing chambers, a centrally supported gas diffuser (CSD) can be used to achieve a uniform environment for substrate processing. The CSD is secured to the processing chamber, such as to the lid, by fasteners. However, the fasteners and fastener holes in the CSD can generate particles during operation of the processing chamber, which can then enter the processing volume through the fastener holes. Embodiments of the present disclosure address this issue by sealing the fastener holes in the CSD.

[0024] FIG1 is a schematic side cross-sectional view of one embodiment of a processing chamber 100 of a substrate processing system. Processing chamber 100 is suitable for plasma-enhanced chemical vapor deposition (PECVD) processing to fabricate circuits on a large-area substrate 105 made of glass, polymer, or other suitable substrates. Processing chamber 100 is configured to form structures and devices on large-area substrate 105 for use in manufacturing liquid crystal displays (LCDs) or flat panel displays, photovoltaic devices for solar cell arrays, or other structures. The structures may be a plurality of back-channel etched inversely staggered (bottom-gate) thin-film transistors, which may include a plurality of sequential deposition and masking steps. Other structures may include pn junctions to form diodes for photovoltaic cells.

[0025] The processing chamber 100 includes chamber sidewalls 110, a bottom 115, and a substrate support 120 (such as a susceptor) that supports a large-area substrate 105 during processing. A centrally supported gas diffuser 145 is disposed opposite the substrate support 120 and the large-area substrate 105. The processing chamber 100 also has a port 125 (such as a slit valve) that facilitates the transfer of the large-area substrate 105 and the deposition process on the large-area substrate 105 by selectively opening and closing. The processing chamber 100 also includes a lid structure 130, a backing plate 140, and the centrally supported gas diffuser 145. In one embodiment, the lid structure 130 supports the backing plate 140 and the centrally supported gas diffuser 145. In one embodiment, an inner surface 146 of the backing plate 140 and an inner surface 147 of the chamber sidewall 110 define a variable pressure region 148. In one aspect, the processing chamber 100 includes a body comprising chamber sidewalls 110, a bottom 115, and a backing plate 140 that define a variable-pressure region 148. At the interface where the backing plate 140 and the lid structure 130 may contact each other, the backing plate 140 is sealed around its perimeter by a suitable O-ring. The O-ring facilitates electrical insulation and seals the variable-pressure region 148 when a vacuum pump coupled to the processing chamber 100 provides negative pressure.

[0026] In one embodiment, the centrally supported gas diffuser 145 is supported by the backing plate 140 at its central region by one or more central support members 150. The one or more central support members 150 help support the centrally supported gas diffuser 145 at its central region to control the horizontal profile of the centrally supported gas diffuser 145 and mitigate the tendency of the centrally supported gas diffuser 145 to sag or sag due to one or a combination of heat, gravity, and vacuum. The centrally supported gas diffuser 145 may also be supported at its perimeter by flexible suspensions 155. The flexible suspensions 155 are adapted to support the centrally supported gas diffuser 145 from its edges and allow for lateral expansion and contraction of the centrally supported gas diffuser 145.

[0027] The processing chamber 100 is coupled to a gas inlet 160 that is coupled to a gas source and a plasma source 165. The plasma source 165 can be a DC power source, a wireless radio frequency (RF) power source, or a remote plasma source. The RF power source can be inductively or capacitively coupled to the processing chamber 100. The gas inlet 160 delivers process or cleaning gas from the gas source through holes 162 to an intermediate region 170 defined between the backing plate 140 and the centrally supported gas diffuser 145. In one exemplary operation, process gas is delivered from the gas source while the interior of the processing chamber 100 is evacuated to a suitable pressure by a vacuum pump. One or more process gases flow through the gas inlet 160 to the intermediate region 170 defined between the backing plate 140 and the centrally supported gas diffuser 145. The one or more process gases then flow from the intermediate region 170 through a plurality of openings or gas passages 175 formed through the centrally supported gas diffuser 145 to a processing region 180 defined in an area below the centrally supported gas diffuser 145 and above the substrate support 120 .

[0028] The large area substrate 105 is lifted from the transfer position to the processing region 180 by moving the substrate support 120 toward the center-supported gas diffuser 145. The height of the processing region 180 can be varied as a processing parameter based on the spacing between the lower surface of the center-supported gas diffuser 145 and the substrate receiving surface 190 of the substrate support 120. The substrate support 120 can be heated by an integrated heater, such as a heating coil or resistive heater coupled to or disposed within the substrate support 120.

[0029] Plasma can be formed in the processing region 180 by a plasma source 165 coupled to the processing chamber 100. Gases excited by the plasma are 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. Plasma can also be formed in the processing chamber 100 by other means, such as thermally induced plasma. Although the plasma source 165 is shown coupled to the gas inlet 160 in this embodiment, the plasma source 165 can be coupled to the centrally supported gas diffuser 145 or other portions of the processing chamber 100.

[0030] The centrally supported gas diffuser 145 is made of or coated with a conductive material and is coupled to the plasma source 165 via the gas inlet 160 or other connection, allowing it to function as a first electrode within the processing chamber 100. Materials selected for the centrally supported gas diffuser 145 may include steel, titanium, aluminum, or combinations thereof, and the surface may be polished or anodized. The centrally supported gas diffuser 145 may include a first or upper surface 185A and a second or lower surface 185B. In one embodiment, the upper surface 185A and the lower surface 185B are substantially parallel in cross-section. In another embodiment, at least one of the upper surface 185A and the lower surface 185B may be curved in cross-section to define a concave surface. In another embodiment, at least one of the upper surface 185A and the lower surface 185B may be curved to define a convex surface. In another embodiment, at least one of the upper surface 185A and the lower surface 185B is non-parallel. In one embodiment, the centrally supported gas diffuser 145 may include a thickness or cross-sectional dimension that is thicker at the perimeter and thinner at its center to form a dished or "scooped" lower surface 185B. In this embodiment, at least the upper surface 185A is substantially planar or flush. Thus, the thicker cross-sectional dimension at the perimeter of the centrally supported gas diffuser 145 relative to the center of the centrally supported gas diffuser 145 forms a desired horizontal profile that is concave relative to the horizontal profile of the substrate support 120. In another embodiment, the substrate receiving surface 190 of the substrate support 120 is substantially planar, and the lower surface 185B of the centrally supported gas diffuser 145 is concave relative to the substrate receiving surface 190.

[0031] FIG2 shows a top view of a portion of a gas diffuser 200. Gas diffuser 200 may be a centrally supported gas diffuser (CSD) and includes a diffuser plate body 202 and a diffuser array 204 having an array centerline 206 aligned along the length of diffuser plate body 202. Diffuser array 204 may also include a plurality of gas inlets 208 distributed between gas diffuser units 210, with no direct fluid communication between the gas diffuser units 210. It should be noted that only a portion of gas diffuser 200 is shown to illustrate a single column of diffuser array 204. Gas diffuser 200 typically includes a diffuser array 204 having multiple columns. Each column of diffuser array 204 includes a desired number of gas diffuser units 210. At least one of gas diffuser units 210 includes a fastening aperture 212, a first gas inlet 214, and a second gas inlet 216. The fastening apertures 212 allow the diffuser plate body 202 to be secured to the processing chamber 100 via a plurality of fasteners (not shown). Each of the first gas inlet 214 and the second gas inlet 216 is separated from the fastening aperture 212 by an inlet distance 218. The first gas inlet 214 is separated from the fastening aperture 212 by the inlet distance 218 along the array centerline 206. The second gas inlet 216 is separated from the fastening aperture 212 by the inlet distance 218 along the array centerline 206 and is opposite the first gas inlet 214. In one embodiment, the inlet distance 218 is uniform across the entire diffuser array 204.

[0032] Figures 3A-3C illustrate a gas diffuser 300 according to one embodiment of the present disclosure. Specifically, Figure 3A shows a schematic cross-sectional side view of the gas diffuser 300 (taken along section line AA in Figure 2). Figure 3B shows a close-up cross-sectional side view of a gas diffuser unit 310 of the gas diffuser 300. Figure 3C is a close-up cross-sectional view of the unit's central axis 330 of the gas diffuser 300. As shown in Figure 3A, the gas diffuser 300 may be a centrally supported diffuser and includes a diffuser plate body 302 with a gas diffuser array 304 of gas diffuser units 310 evenly spaced thereon. Each gas diffuser unit 310 includes a fastening aperture 312, a first gas inlet 314, and a second gas inlet 316. The fastening aperture 312, the first gas inlet 314, and the second gas inlet 316 open at a top surface 318 of the diffuser plate body 302. The fastening orifice 312 may have an inner surface that is threaded and configured to mate with a fastener (not shown) to secure the diffuser plate body 302 to the processing chamber ( FIG. 1 ). The first gas inlet 314 and the second gas inlet 316 are fluidically coupled to the venturi channel 320 and the gas outlet 322. The gas outlet 322 opens at a bottom surface 324 of the diffuser plate body 302 that faces the processing volume ( FIG. 1 ) and is fluidically coupled to the processing volume.

[0033] As shown in FIG. 3B , the first gas inlet 314 and the second gas inlet 316 may include inlet axes, such as first inlet axis 332 and second inlet axis 334, extending radially about the unit central axis 330. The first gas inlet 314 may be aligned at a first axis angle 336, defined as the angle between the first inlet axis 332 and the unit central axis 330. Similarly, the second gas inlet 316 may be aligned at a second axis angle 338, defined as the angle between the second inlet axis 334 and the unit central axis 330. In one embodiment, the first inlet axis 332 and the second inlet axis 334 are equal. In another embodiment, the first inlet axis 332 and the second inlet axis 334 are different. The fastening orifice 312 includes an orifice depth 312a, is concentrically aligned with the unit central axis 330, and includes an orifice plug 340 at a distal end of the fastening orifice 312. First gas inlet 314 and second gas inlet 316 create or form a gas path 326 that flows inwardly from top surface 318 to a junction along unit central axis 330, below orifice plug 340. Gas path 326 then flows into venturi passage 320 and through to gas outlet 322 to enter the processing volume.

[0034] As shown in FIG. 3C , the fastening orifice 312 includes a major diameter 350 at the orifice depth 312a. At the end of the orifice depth 312a, the fastening orifice 312 includes a plug diameter 352 that is smaller than the major diameter 350. The fastening orifice 312 extends through the diffuser plate body 302 into the gas path 326 at the intersection with the first and second gas inlets 314, 316. An orifice plug 340 is disposed at the bottom of the orifice depth 312a and secured to the fastening orifice 312 by a smaller plug diameter 352. The orifice plug 340 is made of a material inert to the process gas being diffused and can be made of the same material as the diffuser plate body 302. Such materials may include aluminum, stainless steel, or silicon carbide. The orifice plug 340 may include a plug depth 342 that separates the fastening orifice 312 from the gas path 326 created by the first and second gas inlets 314, 316. Additionally, the orifice plug 340 may include a plug taper 344 to facilitate gas flow along the outer surface of the orifice plug 340. As shown, the orifice plug 340 may also include a planar bottom surface 346 to reduce interference with the gas path 326. The orifice plug 340 may be coupled to the fastening orifice 312 by any suitable method, including shrink fit, press fit, adhesive bonding, welding, or a combination thereof. The orifice plug 340 prevents debris and particles from the fastening orifice 312 and associated fasteners from entering the gas path 326 created by the first gas inlet 314 and the second gas inlet 316, which ultimately prevents contamination of substrates being processed in the processing volume (not shown).

[0035] Figures 4A and 4B illustrate a gas diffuser 400 according to another embodiment of the present disclosure. Specifically, Figure 4A shows a schematic cross-sectional side view of the gas diffuser 400 (taken along section line AA in Figure 2). Figure 4B is a close-up cross-sectional side view of a gas diffuser unit 410 of the gas diffuser 400. Figure 4C is a close-up cross-sectional view of the unit's central axis 430 of the gas diffuser 400. As shown in Figure 4A, the gas diffuser 400 includes a diffuser plate body 402 having a gas diffuser array 404 of gas diffuser units 410 evenly spaced thereon. Each gas diffuser unit 410 includes a fastening aperture 412, a first gas inlet 414, and a second gas inlet 416. The fastening aperture 412, the first gas inlet 414, and the second gas inlet 416 open at a top surface 418 of the diffuser plate body 402. The first gas inlet 414 and the second gas inlet 416 are fluidically coupled to a venturi passage 420 and a gas outlet 422. The gas outlet 422 opens at a bottom surface 424 facing the processing volume ( FIG. 1 ).

[0036] As shown in FIG. 4B , the first gas inlet 414 and the second gas inlet 416 may include inlet axes (e.g., first inlet axis 432 and second inlet axis 434) extending radially about the cell central axis 430. The first gas inlet 414 may be aligned at a first axis angle 436, defined as the angle between the first inlet axis 432 and the cell central axis 430. Similarly, the second gas inlet 416 may be aligned at a second axis angle 438, defined as the angle between the second inlet axis 434 and the cell central axis 430. In one embodiment, the first inlet axis 432 and the second inlet axis 434 are equal. In another embodiment, the first inlet axis 432 and the second inlet axis 434 are different. The fastening aperture 412 includes an aperture depth 412a concentrically aligned with the cell central axis 430 and includes a plug portion 440 at a distal end of the fastening aperture 412. First gas inlet 414 and second gas inlet 416 create or form a gas path 426 that flows inwardly from top surface 418 to a junction along unit central axis 430, below plug portion 440. Gas path 426 then flows into venturi passage 420 and through to gas outlet 422 to enter the processing volume.

[0037] The fastening aperture 412 includes a major diameter 450 extending relative to the aperture depth 412a. A plug portion 440 is concentrically aligned with the unit central axis 430 and is continuous with the diffuser plate body 402, i.e., the plug portion 440 is a portion of the diffuser plate body 402. The plug portion 440 includes a plug depth 442 defined by the ends of the aperture depth 412a and the gas path 426 created by the first and second gas inlets 414, 416. The plug portion 440 includes a plurality of plug tapers 444 that are continuous with the first and second gas inlets 414, 416. This configuration allows the fastening aperture 412 to function as a blind hole in the diffuser plate body 402 that couples to fasteners (not shown) to secure the gas diffuser 400 to a processing chamber (not shown). The plug portion 440 prevents debris and particles from the fastening apertures 412 and associated fasteners from entering the gas path 426 created by the first and second gas inlets 414, 416, which ultimately prevents contamination of substrates being processed in a processing volume (not shown).

[0038] This disclosure provides a centrally supported gas diffuser for use in a substrate processing chamber. The gas diffuser includes a plug or plug portion at the bottom of the fastener opening to prevent fasteners from directly threading into the diffuser's gas path, thereby sealing out particles generated by the threading interaction. The seal created by the plug prevents particle contamination from entering the gas path and flowing onto substrates in the processing volume.

[0039] When introducing elements of the present disclosure or exemplary aspects or embodiments thereof, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements.

[0040] The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0041] As used herein, the term "coupled" refers to a direct or indirect coupling between two objects. For example, if object A physically contacts object B and object B contacts object C, objects A and C are considered coupled to each other—even if objects A and C are not in direct physical contact. For example, a fist-shaped object may be coupled to a second object even if the first object has never been in direct physical contact with the second object.

[0042] 100: Processing chamber 105: Large area substrate 110: chamber side wall 115: bottom 120: substrate support 125: Port 130: Cover structure 140: Back panel 145: Center-supported gas diffuser 146: Inner surface 147: Inner surface 148: Variable pressure area 150:Center support member 155: Flexible suspension 160: Gas inlet 162: Hole 165: Plasma Source 170: Middle area 175: Gas channel 180:Processing area 185A: Upper surface 185B: Lower surface 190: substrate receiving surface 200:Gas Diffuser 202: Diffuser plate body 204: Diffuser Array 206: Array centerline 208: Gas inlet 210: Gas diffuser unit 212: Fastening hole 214: First gas inlet 216: Second gas inlet 218:Entrance distance 300:Gas Diffuser 302: Diffuser plate body 304: Gas Diffuser Array 310: Gas diffuser unit 312: Fastening hole 312a: Orifice depth 314: First gas inlet 316: Second gas inlet 318: Top surface 320: Venturi channel 322: Gas outlet 324: bottom surface 326: Gas passage 330: unit center axis 332: First inlet axis 334: Second inlet axis 336: First axis angle 338: Second axis angle 340: Orifice plug 342: Plug Depth 344: Plug taper 346: Plane bottom surface 350: Main diameter 352: plug diameter 400:Gas Diffuser 402: Diffuser plate body 404: Gas Diffuser Array 410: Gas diffuser unit 412: Fastening hole 412a: Orifice depth 414: First gas inlet 416: Second gas inlet 418: Top surface 420: Venturi channel 422: Gas outlet 424: bottom surface 426: Gas Path 430: unit center axis 432: First inlet axis 434: Second inlet axis 436: First axis angle 438: Second axis angle 440: plug part 442: plug depth 444: Plug taper 450: Main diameter

[0043] Domestic storage information (please note the order of storage institution, date, and number) none Overseas deposit information (please note the order of deposit country, institution, date, and number) none

Claims

1. A gas diffuser comprising: a diffuser plate body; and a diffuser array comprising at least one gas diffuser unit in the diffuser plate body, the gas diffuser unit comprising: a fastening orifice through a top surface of the diffuser plate body; a first gas inlet disposed at an inlet distance from the fastening orifice; a second gas inlet disposed at the inlet distance from the fastening orifice and opposite to the first gas inlet; an orifice plug at a distal end of the fastening orifice; a channel fluidly coupled to the first gas inlet and the second gas inlet; and a gas outlet fluidly coupled to the channel and extending through a bottom surface of the diffuser plate body.

2. The gas diffuser as claimed in claim 1, wherein the fastening orifice includes a main diameter and a plug diameter, the plug diameter being smaller than the main diameter.

3. The gas diffuser as claimed in claim 2, wherein the orifice plug is disposed within the plug diameter.

4. The gas diffuser as claimed in claim 1, wherein the orifice plug comprises a material configured to be inert to a variety of process gases flowing through the first gas inlet and the second gas inlet.

5. The gas diffuser as claimed in claim 1, wherein the orifice plug includes a plurality of plug tapers along the first gas inlet and the second gas inlet.

6. The gas diffuser as claimed in claim 1, wherein the orifice plug is provided at an orifice depth of the fastening orifice.

7. The gas diffuser as claimed in claim 1, wherein the orifice plug is configured to seal the fastening orifice from a gas path formed by the first gas inlet and the second gas inlet.

8. A gas diffuser comprising: a diffuser plate body; and a diffuser array comprising at least one gas diffuser unit in the diffuser plate body, the gas diffuser unit comprising: a fastening orifice through a top surface of the diffuser plate body; a first gas inlet disposed at an inlet distance from the fastening orifice; a second gas inlet disposed at the inlet distance from the fastening orifice and opposite to the first gas inlet; a plug portion at a distal end of the fastening orifice; a channel fluidly coupled to the first gas inlet and the second gas inlet; and a gas outlet fluidly coupled to the channel and extending through a bottom surface of the diffuser plate body.

9. The gas diffuser as claimed in claim 8, wherein the plug portion is continuous with the diffuser plate body.

10. The gas diffuser as claimed in claim 8, wherein the plug portion includes a plug depth configured to seal the fastening orifice from the first gas inlet and the second gas inlet.

11. The gas diffuser as claimed in claim 8, wherein the plug portion includes a plurality of plug tapers along the first gas inlet and the second gas inlet.

12. The gas diffuser as claimed in claim 8, wherein the plug portion is concentrically aligned with the central axis of a unit of the gas diffuser.

13. The gas diffuser as claimed in claim 8, wherein the plug portion is disposed at a depth of the fastening orifice.

14. The gas diffuser as claimed in claim 8, wherein the first gas inlet is at a first axial angle to the central axis of a unit, the second gas inlet is at a second axial angle to the central axis of the unit, and the first axial angle and the second axial angle are equal.

15. A processing chamber comprising: a processing region and a variable pressure region defined by a plurality of sidewalls of the processing chamber, a chamber base and a cover structure; and a gas diffuser coupled to the cover structure, the gas diffuser including a plug portion disposed in a fastening orifice of at least one gas diffuser unit.

16. The processing chamber as described in claim 15, wherein the plug portion is continuous with a diffuser plate body of the gas diffuser.

17. The processing chamber as claimed in claim 15, wherein the plug portion includes a plug depth configured to seal the fastening orifice from a first gas inlet and a second gas inlet.

18. The processing chamber as claimed in claim 15, wherein the plug portion is concentrically aligned with the central axis of one unit of the at least one gas diffuser unit.

19. The processing chamber as claimed in claim 15, wherein the plug portion is provided at an orifice depth of the fastening orifice.

20. The processing chamber as claimed in claim 15, wherein the plug portion includes a plurality of plug tapers along a first gas inlet and a second gas inlet.

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