WO2022060351A1

WO2022060351A1 - Differentially anodized showerhead

Info

Publication number: WO2022060351A1
Application number: PCT/US2020/050943
Authority: WO
Inventors: Fupo HAO; Weiji CHEN; Yuefeng Sun; Zheng Wei Yang; Shih Yao SUN; Chung-Hee Park; Sang Jeong Oh; Yirong CAO; Zeren SHANG; Yu Yue; Yixi TIAN
Original assignee: Applied Materials, Inc.
Priority date: 2020-09-16
Filing date: 2020-09-16
Publication date: 2022-03-24
Also published as: CN116917540A

Abstract

Embodiments disclosed herein generally relate to an apparatus having a partially anodized gas distribution showerhead including a body having a plurality of gas passages extending therethrough from an upstream side to a downstream side, each of the upstream side and the downstream side having a different porosity, wherein each of the plurality of gas passages include an orifice hole formed in a center of the body, and wherein the downstream side and a portion of each of the plurality of gas passages include an anodized layer disposed thereon.

Description

DIFFERENTIALLY ANODIZED SHOWERHEAD

BACKGROUND

Field

[0001] Embodiments disclosed herein generally relate to an apparatus having a partially differentially anodized gas distribution showerhead.

Description of the Related Art

[0002] Plasma enhanced chemical vapor deposition (PECVD) is generally employed to deposit thin films on substrates, such as semiconductor substrates, solar panel substrates, flat panel display (FPD) substrates, organic light emitting display (OLED) substrates, and others. PECVD is generally accomplished by introducing a processing gas from a gas distribution showerhead into a vacuum chamber having a substrate disposed on a susceptor. The processing gas is energized into a plasma by applying an RF current to an electrode in the chamber from one or more RF sources coupled to the chamber. The plasma reacts to form a layer of material on a surface of the substrate that is positioned on the susceptor. The design of the gas distribution showerhead, as well as the application of RF current, has a great impact on the properties of the plasma.

[0003] Some of the substrates utilized in industry are flat media, such as rectangular, flexible sheets of glass, plastic or other material typically used in the manufacture of flat panel displays, solar devices, and OLED devices, among other applications. Materials to form electronic devices, films and other structures on the flat media are deposited onto the flat media by numerous processes, including PECVD. However, non-uniform ity and/or film contamination causes issues in electronic devices formed on the flat media. Numerous modifications to the gas distribution showerhead and/or the PECVD process parameters have been performed but improvement in film quality remains a priority.

[0004] Therefore, there is a need in the art for an apparatus having a gas distribution showerhead that alleviates or minimizes the problems discussed herein. SUMMARY

[0005] Embodiments disclosed herein generally relate to an apparatus having an anodized gas distribution showerhead. In one embodiment, a gas distribution showerhead is provided that includes a body having a plurality of gas passages extending therethrough from an upstream side to a downstream side, each of the upstream side and the downstream side having a different porosity, wherein each of the plurality of gas passages include an orifice hole formed in a center of the body, and wherein the downstream side and a portion of each of the plurality of gas passages include an anodized layer disposed thereon.

[0006] In another embodiment, a plasma processing apparatus is disclosed. The apparatus includes a processing chamber body having walls and a floor, a susceptor disposed in the processing chamber body and movable between a first position and a second position and one or more straps coupled to the susceptor and to one or more of the floor or walls. The apparatus also includes a showerhead disposed in the processing chamber body opposite to the susceptor. The showerhead includes a body having a plurality of gas passages extending therethrough from an upstream side to a downstream side, each of the upstream side and the downstream side having a different porosity, wherein each of the plurality of gas passages include an orifice hole formed in a center of the body, and wherein the downstream side and a portion of each of the plurality of gas passages include an anodized layer disposed thereon.

[0007] In another embodiment, a plasma enhanced chemical vapor deposition apparatus is disclosed. The apparatus includes a chamber body having a plurality of walls and a chamber floor and a susceptor disposed in the chamber body and movable between a first position spaced a first distance from the chamber floor and a second position spaced a second distance greater than the first distance from the chamber floor. The apparatus also includes a plurality of straps coupled to the susceptor and to one or more of the chamber floor and the plurality of walls. The plurality of straps are unevenly distributed along the susceptor. The apparatus also includes a gas distribution showerhead disposed in the chamber body opposite the susceptor, having a plurality of gas passages extending therethrough. The gas distribution showerhead includes a body having the plurality of gas passages extending therethrough from an upstream side to a downstream side, each of the upstream side and the downstream side having a different porosity, wherein each of the plurality of gas passages include an orifice hole formed in a center of the body, and wherein the downstream side and a portion of each of the plurality of gas passages include an anodized layer disposed thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0009] Figure 1 is a schematic cross sectional view of an apparatus according to one embodiment.

[0010] Figure 2 is a cross-sectional view of a portion of the diffuser of Figure 1 showing one embodiment of an anodization layer.

[0011] Figure 3 is a cross-sectional view of a portion of the diffuser showing an anodization layer according to another embodiment.

[0012] Figure 4 is a cross-sectional view of a portion of the diffuser showing an anodization layer according to another embodiment.

[0013] Figure 5 is a cross-sectional view of a portion of the diffuser showing an anodization layer according to another embodiment.

[0014] Figure 6 is a flowchart describing a method for making the diffuser as described herein.

[0015] Figure 7 is a cross-sectional view of a portion of the diffuser showing an anodization layer according to another embodiment. [0016] 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 disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

DETAILED DESCRIPTION

[0017] Embodiments disclosed herein generally relate to an apparatus having a partially and/or differentially anodized gas distribution showerhead. In some embodiments, the gas distribution showerhead is fabricated from aluminum and some portions remain bare aluminum while other portions are anodized as disclosed herein. The anodization is provided at portions of the gas distribution showerhead while portions within the peripheral region remain bare aluminum. In other embodiments, the gas distribution showerhead includes more than one anodization layer disposed thereon. In yet other embodiments, the gas distribution showerhead includes a differential roughness and/or porosity on opposing major surfaces thereof.

[0018] The embodiments discussed herein will make reference to a large area PECVD chamber manufactured and sold by AKT America, a subsidiary of Applied Materials, Inc., Santa Clara, CA. It is to be understood that the embodiments discussed herein may be practiced in other chambers as well, including chambers sold by other manufacturers. Large area processing chambers are sized to process flat media, such as flat, flexible substrates having an area of greater than about fifteen thousand square centimeters. In one embodiment, the substrates may have an area of greater than about fifty thousand square centimeters. In another embodiment, the substrates may have an area of greater than about fifty five thousand square centimeters. In another embodiment, the substrates may have an area of greater than about sixty thousand square centimeters. In another embodiment, the substrates may have an area of greater than about ninety thousand square centimeters.

[0019] Figure 1 is a schematic cross sectional view of an apparatus 100 according to one embodiment. In the embodiment shown, the apparatus 100 is a PECVD apparatus. The apparatus 100 includes a chamber body 102 into which is fed processing gas from a gas source 104. When the apparatus 100 is used for deposition, the processing gas is fed from the gas source, through a remote plasma source 106 and through a tube 108. The processing gas is not ignited into a plasma in the remote plasma source 106. During cleaning, the cleaning gas is sent from the gas source 104 into the remote plasma source 106 where it is ignited into a plasma before the radicals from the plasma enter the chamber. The tube 108 is an electrically conductive tube 108.

[0020] The RF current is used to ignite the processing gas into a plasma within the chamber is coupled to the tube 108 from a RF power source 110. RF current travels along the outside of the tube 108 due to the ‘skin effect’ of RF current. RF current will penetrate only a certain, predeterminable depth into a conductive material. Thus, the RF current travels along the outside of the tube 108 and the processing gas travels within the tube 108. The processing gas never ‘sees’ the RF current when traveling in the tube 108 because the RF current does not penetrate far enough into the tube 108 to expose the processing gas to RF current within the tube 108.

[0021] The processing gas is fed to the chamber through the backing plate 114. The processing gas then expands into a volume 118 between the backing plate 114 and a gas distribution plate or diffuser 116. The processing gas then travels through a plurality of gas passages 156 of the diffuser 16 and into the processing volume 148. The gas passages 156 are formed from an upstream side or back face 159 of the diffuser 116 to a downstream side or a front face 160 of the diffuser 116.

[0022] The RF current, on the other hand, does not enter the volume 118 between the backing plate 114 and the diffuser 116. Instead, the RF current travels along the outside of the tube 108 to the backing plate 114. Then, the RF current travels along the atmospheric side 158 of the backing plate 114. The backing plate 114 comprises an electrically conductive material. In one embodiment, the backing plate 114 comprises aluminum. The RF current then travels from the backing plate along a bracket 120 that comprises a conductive material. In one embodiment, the bracket 120 comprises aluminum. In The RF current then travels along the front face 160 of the diffuser 116 where the RF current ignites the processing gas that has passed through the gas passages 156 into a plasma in the processing volume 148 located between the diffuser 116 and the substrate 124. The path that the RF current travels to reach the front face 160 of the diffuser 116 is shown by arrows “A”. An O-ring 122 electrically isolates the wall 146 from the backing plate 114.

[0023] In one embodiment, the diffuser 116 may comprise a conductive material. In another embodiment, the diffuser 116 comprises a metal. In another embodiment, the diffuser 116 comprises aluminum.

[0024] Due to the plasma, material, such as silicon nitride (SiN), is deposited onto the substrate 124. In the embodiment shown in Figure 1 , the substrate 124 is disposed on a susceptor 126 that is movable between a first position spaced a first distance from the diffuser 116 and a second position spaced a second distance from the diffuser 116 where the second distance is less than the first distance. In the embodiment shown in Figure 1 , the susceptor 126 is disposed on a stem 136 and is movable by an actuator 140.

[0025] The substrate 124 is a large area substrate and hence, may bow when elevated on lift pins 130, 132. Thus, the lift pins 130, 132 may have different lengths. When the substrate 124 is inserted into the chamber through the slit valve opening 144, the susceptor 126 may be in a lowered position. When the susceptor 126 is in a lowered position, the lift pins 130, 132 extend above the susceptor 126. Thus, the substrate 124 is placed on the lift pins initially. The lift pins 130, 132 have different lengths. The outer lift pins 130 are longer than the inner lift pins 132 so that the substrate 124 sags in the center when placed on the lift pins 130, 132. The susceptor 126 is raised to meet the substrate 124. The substrate 124 contacts the susceptor 126 in a center to edge progression so that any gas that is present between the susceptor 126 and the substrate 124 is expelled. The lift pins 130, 132 are then raised by the susceptor 126 along with the substrate 124.

[0026] When the susceptor 126 is raised above the slit valve opening 144, the susceptor 126 encounters a shadow frame 128. The shadow frame 128, when not in use, rests on a ledge 142 positioned above the slit valve opening 144. The shadow frame 128, due to the size, may not align properly. Therefore, rollers may be present on either the shadow frame 128 or the susceptor 126 to permit the shadow frame 128 to roll into proper alignment on the susceptor 126. The shadow frame 128 serves a dual purpose. The shadow frame 128 shields areas of the susceptor 126 that are not covered by a substrate 124 from deposition. Additionally, the shadow frame 128, when comprising an electrically insulating material, electrically shields the RF current that travels along the susceptor 126 from the RF current that travels along the walls 146. In one embodiment, the shadow frame 128 comprises an insulating material. In another embodiment, the shadow frame 128 comprises a ceramic material. In another embodiment, the shadow frame 128 comprises AI2O3. In another embodiment, the shadow frame comprises a metal with an anodized layer thereover. In one embodiment, the metal comprises aluminum. In another embodiment, the anodized layer comprises AI2O3.

[0027] The RF current needs to return to the power source 110 that drives the RF current. The RF current couples through the plasma to the susceptor 126. In one embodiment, the susceptor 126 comprises a conductive material such as aluminum. The RF current travels back to the power source 110 by traveling the path shown by arrows “B”. The RF current returns back along the wall 146 and a backing plate 112 before reaching the power source 110.

[0028] To shorten the RF current return path, in one embodiment, one or more straps 134 are coupled to the susceptor 126. By utilizing straps 134, the RF current will travel down the straps 134 to the bottom 138 of the chamber and then back up the interior walls 146 of the chamber. In the absence of the straps 134, the RF current would travel along the bottom of the susceptor 126, down the stem 136 and then back along the bottom 138 and interior walls 146 of the chamber. A high potential difference may exist between the RF current travelling along the bottom of the susceptor 126 and the RF current on either the stem 136 or the bottom 138 of the chamber. Because of the potential different, arcing may occur in the volume 150 below the susceptor. The straps 134 reduce the likelihood of arcing in volume 150.

[0029] In another embodiment, an anodized layer 170 is provided on a portion of the diffuser 116. In some embodiments, the susceptor 126 has not only the straps 134 coupled to the susceptor 126, but also an RF return element 172 by way of an extension 174 coupled to the bottom of the susceptor 126. The RF return element 172 couples to the ledge 142 which supports the shadow frame 128 when the susceptor 126 is in the lowered position. The RF return element 172 shown in Figure 1 is a rod that provides the electrical connection between the susceptor 126 and the ledge 142. The RF return element 172 provides a shorter return path than the straps 134 and thus, the majority of the RF current will return to the RF power source by way of the RF return elements 172 rather than the straps 134. Other RF return elements may also be used in conjunction with the anodized layer 170 and the straps 134, which will be discussed below. In one embodiment, the RF return element 172 may be disposed on the ledge 142 and extend therebelow until the extension 174 from the susceptor 126 moves into contact with the RF return element 172.

[0030] The anodized layer 170 may be utilized to tune plasma within the processing volume 148. As described in more detail below, the diffuser 116 includes a center region and an edge or peripheral region surrounding the center region. The phrase “bare aluminum” is defined as a surface free from a coating, with the exception of a natural or native oxide layer which is common to aluminum surfaces. The anodized layer 170 may be defined as a layer or coating deliberately provided on a surface as opposed to a naturally occurring layer, such as a native oxide layer. The anodized layer 170 may be an oxide layer that is thicker than a naturally occurring oxide layer. The surface area of the diffuser 116 covered by the anodized layer 170 may be determined based on a balance of two competing concerns: particle generation (which affects yield) and plasma uniformity (which affects film uniformity).

[0031] For example, surfaces of conventional diffusers are typically covered by an anodization film which includes a porous microstructure. The microstructure tends to trap (i.e. , adsorb) process gases and/or cleaning gases (or species thereof) that is later desorbed from the microstructure and onto electronic devices on a substrate. In a specific example, nitrogen species from NH3 and/or N2O as well as fluorine species from NF3 can be absorbed into the microstructure and later desorbed out of the microstructures and onto silicon films formed on a substrate. It has been found that these desorbed species can cause a shift in threshold voltage of electronic devices formed on the substrate. It has also been discovered that the majority of these species are absorbed on the back face 159 of the diffuser 116 and then are desorbed therefrom, which affects film and/or device formation. Each of the nitrogen species contains one or more nitrogen atoms and optionally one or more other atoms, such as hydrogen, fluorine, and/or other elements. In one example, the nitrogen species can be NHx or NFx, where x is 0, 1 , 2, or 3.

[0032] Accordingly, it has been found that optimizing the surface morphology improves the film purity therefore minimizing or eliminating threshold voltage shift in devices formed on a substrate.

[0033] Figure 2 is a cross-sectional view of a portion of the diffuser 116 of Figure 1 . The diffuser 116 includes a body 200 having a first or upstream side 202 facing the backing plate 112 (shown in Figure 1 ) corresponding to the back face 159 of the diffuser 116 of Figure 1 , and an opposing second or downstream side 204 that faces the susceptor 126 (shown in Figure 1) corresponding to the front face 160 of the diffuser 116 of Figure 1. Each gas passage 156 is defined by a first bore 210 coupled by an orifice hole 214 to a second bore 212 that combine to form a fluid path through the diffuser 116. The first bore 210 extends a first depth or length 230 from the upstream side 202 of the diffuser 116 to a bottom or upper transition region 218. The upper transition region 218 of the first bore 210 may be tapered, beveled, chamfered or rounded to minimize the flow restriction as gases flow from the first bore 210 into the orifice hole 214. The first bore 210 generally has a diameter of about 0.093 to about 0.218 inches, and in one embodiment is about 0.156 inches.

[0034] The thickness of the diffuser 116 may be between about 0.8 inch to about 3.0 inches, for example, between about 0.8 inch to about 2.0 inch. The second bore 212 is formed in the diffuser 116 and extends from the downstream side (or end) 204 to a depth 232 of about 0.10 inch to about 2.0 inches. In one embodiment, the depth 232 may be between about 0.1 inch to about 1.0 inch. The diameter 236 of the second bore 212 may be generally about 0.1 inch to about 1.0 inch and may be flared at an angle 216 of about 10 degrees to about 50 degrees relative to the downstream side 204. In one embodiment, the diameter 236 may be between about 0.1 inch to about 0.5 inch and the flaring angle 216 may be between 20 degrees to about 40 degrees. The surface of the second bore 212 may be between about 0.05 inch² to about 10 inch² and in one embodiment may be between about 0.05 inch² to about 5 inch². The diameter of second bore 212 refers to the diameter intersecting the downstream side 204. An example of diffuser 116, used to process 1500 mm by 1850 mm substrates, has second bores 212 at a diameter of 0.250 inch and at a flare angle 216 of about 22 degrees. The distances 280 between rims 282 of adjacent second bores 212 are between about 0.0 inch to about 0.6 inch, and in one embodiment, may be between about 0.0 inch to about 0.4 inch. The diameter of the first bore 210 is usually, but not limited to, being at least equal to or smaller than the diameter of the second bore 212. A bottom or lower transition region 220 of the second bore 212 may be tapered, beveled, chamfered or rounded to minimize the pressure loss of gases flowing out from the orifice hole 214 and into the second bore 212. Moreover, as the proximity of the orifice hole 214 to the downstream side 204 serves to minimize the exposed surface area of the second bore 212 and the downstream side 204 that face the substrate, the downstream area of the diffuser 116 exposed to fluorine provided during chamber cleaning is reduced, thereby reducing the occurrence of fluorine contamination of deposited films.

[0035] In one embodiment, the volumes of the second bores 212 may comprise hollow cathode cavities 250. For example, the orifice holes 214 generate a back pressure on the upstream side 202 of the diffuser 116. Due to the back pressure, process gases may evenly distribute on the upstream side 202 of the diffuser 116 before passing through the gas passages 156. The volumes of the hollow cathode cavities 250 permit a plasma to be generated within the gas passages 156, specifically within the hollow cathode cavities 250. The variations of the volume of the hollow cathode cavities 250 permit greater control of plasma distribution as opposed to the situation where no hollow cathode cavities are present. At least a portion of the hollow cathode cavities 250 at the downstream side 204 may have a larger diameter 236 or width than the orifice holes 214. The first bore 210 has a width or diameter less than the plasma dark space and thus, plasma is not formed above the hollow cathode cavities 250. [0036] The orifice hole 214 generally couples the upper transition region 218 of the first bore 210 and the lower transition region 220 of the second bore 212. The orifice hole 214 may include a diameter of about 0.01 inch to about 0.3 inch, for example, about 0.01 inch to about 0.1 inch, and may include a length 234 of about 0.02 inch to about 1.0 inch, for example, about 0.02 inch to about 0.5 inch. The orifice hole 214 may be a choke hole and the length 234 and diameter (or other geometric attribute) of the orifice hole 214 is the primary source of back pressure in the volume between the diffuser 116 and the backing plate 112 (shown in Figure 1) which promotes even distribution of gas across the upstream side 202 of the diffuser 116. The orifice hole 214 is typically configured uniformly among the plurality of gas passages 156; however, the restriction through the orifice hole 214 may be configured differently among the gas passages 156 to promote more gas flow through one area or region of the diffuser 116 relative to another area or region. For example, the orifice hole 214 may have a larger diameter and/or a shorter length 234 in those gas passages 156, of the diffuser 116, closer to the wall 146 (shown in Figure 1 ) of the chamber 100 so that more gas flows through the edges of the diffuser 116 to increase the deposition rate at portions of the perimeter areas of the substrate 105.

[0037] In one embodiment of the disclosure, the diffuser 116 includes an anodized layer 170 on the downstream side 204 and a portion of the gas passages 156 as shown in Figure 2. In this embodiment, the anodized layer 170 is a conformal and/or uninterrupted layer that covers the entirety of the downstream side 204, the second bore 212, the lower transition region 220, and the orifice hole 214. Conversely, the upper transition region 218, the first bore 210, and the upstream side 202 of the diffuser 116 are bare (i.e., un-anodized) metal, such as aluminum. Although only three gas passages 156 are shown, the other gas passages 156 across the diffuser 116 are the same.

[0038] Figure 3 is a cross-sectional view of a portion of the diffuser 116 showing a single gas passage 156, although other gas passages 156 across the diffuser 116 are the same. In this embodiment, the diffuser 116 includes an anodized layer 170 on the downstream side 204 and the entirety of the gas passage 156. Specifically, the anodized layer 170 is a conformal and/or uninterrupted layer that covers the entirety of the downstream side 204, the second bore 212, the lower transition region 220, the orifice hole 214, the upper transition region 218 and the first bore 210. Conversely, the upstream side 202 of the diffuser 116 are bare (i.e., unanodized) metal, such as aluminum.

[0039] Figure 4 is a cross-sectional view of a portion of the diffuser 116 showing a single gas passage 156, although other gas passages 156 across the diffuser 116 are the same. In this embodiment, the diffuser 116 includes an anodized layer 170 on the downstream side 204 and a portion of the gas passage 156. Specifically, the anodized layer 170 is a conformal and/or uninterrupted layer that covers the entirety of the downstream side 204, the second bore 212, and the lower transition region 220. Conversely, the orifice hole 214, the upper transition region 218, the first bore 210 and the upstream side 202 of the diffuser 116 are bare (i.e., un-anodized) metal, such as aluminum.

[0040] Figure 5 is a cross-sectional view of a portion of the diffuser 116 showing a single gas passage 156, although other gas passages 156 across the diffuser 116 are the same. In this embodiment, the diffuser 116 includes an anodized layer 170 on the downstream side 204 and a portion of the gas passage 156. Specifically, the anodized layer 170 is a conformal and/or uninterrupted layer that covers the entirety of the downstream side 204, the second bore 212, the lower transition region 220, the orifice hole 214, the upper transition region 218, and a portion of the first bore 210. Conversely, the remainder of the first bore 210 and the upstream side 202 of the diffuser 116 are bare (i.e., un-anodized) metal, such as aluminum.

[0041] In some embodiments, the length 230 of the first bore 210 (including the upper transition region 218) is about 1.0 inches to about 1.03 inches from the upstream side 202 of the diffuser 116. In this embodiment, the anodized layer 170 covers about 50 % of the surfaces of the first bore 210 (e.g., of the length 230). For example, a terminating end 500 of the anodized layer 170 includes a depth or length 505 that is about 0.48 inches to about 0.53 inches, such as about 0.51 inches. [0042] The length 505 being greater than 50% may be more beneficial from a gas absorption standpoint. However, the greater depth of the length 505 provides a higher probability of acid solution (during a de-anodization process described below in Figure 6) flowing into the orifice hole 214 and further downstream into the lower transition region 220 and/or the second bore 212. Thus, acid flowing into the gas passage 156 past the terminating end 500 of the anodized layer 170 should be avoided to maintain the anodized layer 170 as shown in Figure 5.

[0043] In some embodiments, which can be combined with other embodiments as described herein, the thickness of the anodized layer 170 is about 1.8 microns (pm) to about 2.2 pm. In some embodiments, which can be combined with other embodiments as described herein, the average surface roughness (Ra) of the downstream side 204 (i.e., the anodized layer 170) is about 1.9 pm to about 3.07 pm. In some embodiments, which can be combined with other embodiments as described herein, the Ra of the upstream side 202 of the diffuser 116 is about 2.8 pm to about 3.1 pm.

[0044] Figure 6 is a flowchart describing a method 600 for making the diffuser 116 as described herein. The method 600 includes box 605 where the diffuser 116 is machined. The machining includes forming the gas passages 156 as disclosed herein and may include other machining that the diffuser 116 for mounting in a chamber. After machining at 605, the method 600 includes a heat treatment process in box 610. The heat treating includes annealing as well as other thermal processes.

[0045] A first cleaning process, indicated at box 615, is performed after the heat treating. The first cleaning process includes one or a combination of stripping, power washing, and drying.

[0046] After the cleaning process at 615, the method 600 includes a roughening process at box 620. The roughening process includes, but is not limited to, a bead blasting process. During the roughening process, all or a portion of external surfaces of the diffuser 116 are roughened. In some embodiments, the orifice hole 214 is not roughened as the diameter may be too small. [0047] While not shown, an optional polishing process can be performed an some surfaces of the diffuser 116. For example, the upstream side 202 of the diffuser 116 may be polished to minimize surface roughness. Minimizing surface roughness on portions of the diffuser 116 reduces gas absorption, which minimizes threshold voltage shift in devices formed by the diffuser 116. In one example, the upstream side 202 of the diffuser 116 may be polished (as well as portions of the first bore 210) to have an Ra of less than 1.5 pm.

[0048] A second cleaning process, indicated at box 625, is performed after the roughening process. The second cleaning process includes one or a combination of stripping, power washing, and drying.

[0049] After the second cleaning, the diffuser 116 is anodized as shown at box 630. During the anodizing process, all or a portion of external surfaces of the diffuser 116 are roughened, including the gas passages 156.

[0050] A third cleaning process, indicated at box 635, is performed after the anodizing process. The third cleaning process includes one or a combination of stripping, power washing, and drying.

[0051] After the third cleaning process, the diffuser 116, having the anodization layer disposed thereon, is de-anodized, as shown at box 640. The de-anodization process includes dipping portions of the diffuser 116 into an acid bath, which selectively removes the anodized layers. In one example, the diffuser 116 is suspended in the acid bath and lowered to a level in the acid solution where removal of the anodized layer is desired.

[0052] After the de-anodization process, a fourth cleaning process, indicated at box 645, is performed. The fourth cleaning process includes one or a combination of stripping, power washing, and drying. The fourth cleaning process may also include an inspection of the diffuser 116 as well as packaging the diffuser 116 for shipment.

[0053] Figure 7 is a cross-sectional view of a portion of the diffuser 116 showing a single gas passage 156, although other gas passages 156 across the diffuser 116 are the same. In this embodiment, the diffuser 116 includes an anodized layer 170 on the downstream side 204 and a portion of the gas passage 156. Specifically, the anodized layer 170 is a conformal and/or uninterrupted layer that covers the entirety of the downstream side 204, the second bore 212, the lower transition region 220, the orifice hole 214, the upper transition region 218, and a portion of the first bore 210. The anodized layer 170 according to this embodiment is a first anodized layer.

[0054] In this embodiment, the remainder of the first bore 210 and the upstream side 202 of the diffuser 116 include a second anodized layer 700. In this embodiment, which can be combined with other embodiments as described herein, the anodized layer 170 includes a plurality of pores 705 defining a first porosity. The plurality of pores 705 include a mean diameter of about 100 nanometers (nm). Conversely, the second anodized layer 700 includes a second porosity that is greater than the first porosity of the anodized layer 170. In one example, the second anodized layer 700 includes a plurality of pores 710 that each include a mean diameter of greater than 100 nm. In a specific example, the pores 710 include a mean diameter of about 110 nm to about 130 nm, or greater. A transition from the first porosity to the second porosity is indicated by a conversion line 715, which is within the upper transition region 218 according to this embodiment. The conversion line may be within or on other portions of the gas passage 156 according to other embodiments. The differences in porosity can be controlled by varying voltage applied during the anodization process.

[0055] In some embodiments, the second anodized layer 700 may overlap the anodized layer 170 at or near the conversion line 715. In some embodiments, the conversion line 715 mat be at the interface of the upper transition region 218 and the orifice hole 214. However, the length 234 of the orifice hole 214 is a small percentage of a total thickness 720 of the diffuser 116. For example, the length 234 may be about 5% to about 9 %, such as about 7% of the total thickness 720. Thus, any overlap at the conversion line 715 does not drastically impact the absorption of gases of the diffuser 116 which has a large influence on reducing threshold voltage shift in formed devices. [0056] The larger pore size of the pores 710 relative to the size of the pores 705 help to reduce gas absorption of the diffuser 116. For example, the size of the pores 710 reduce gas absorption at the upstream side 202 relative to the absorption of gases at the downstream side 204. In some embodiments, the size of the pores 710 are about 1 time greater than the size of the pores 705. In other embodiments, the size of the pores 710 are about 2 times greater than the size of the pores 705. In other embodiments, the size of the pores 710 are about 2.5 times greater than the size of the pores 705. It is contemplated that the larger pore size at the upstream side 202 of the diffuser 116 eases pumping out absorbed gases in vacuum condition, which reduces threshold voltage shift.

[0057] While multiple different embodiments of the diffuser 116 with the anodized layer 170 are shown above, the various embodiments may be mixed together across the diffuser 116. For example, some of the gas passages 156 may be configured as shown in one figure (e.g., Figure 2) while others may be configured as shown in other figures (e.g., one or a combination of the anodized layer 170 shown in Figures 3-5). In addition, another diffuser 116 is disclosed in Figure 7 that includes anodization layers on both sides. This embodiment may be combined with any of the others shown in Figures 2-5. In addition, the method 600 described in Figure 6 may be altered to selectively remove anodized layers on the diffuser 116 and add another anodized layer where the previous anodized layer was removed. In one example, the diffuser 116 may be anodized first with the second anodized layer 700 and then a portion of the second anodized layer 700 removed where the anodized layer 170 is desired. Then, the anodized layer 170 is applied to the diffuser 116.

[0058] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims:

1 . A gas distribution showerhead, comprising: a body having a plurality of gas passages extending therethrough from an upstream side to a downstream side, the upstream side having a different porosity and roughness than the downstream side, wherein each of the plurality of gas passages include an orifice hole, and wherein the downstream side and a portion of each of the plurality of gas passages include an anodized layer disposed thereon.

2. The gas distribution showerhead of claim 1 , wherein the anodized layer is disposed on a portion of the orifice hole.

3. The gas distribution showerhead of claim 1 , wherein the anodized layer is disposed on an entire surface of the orifice hole.

4. The gas distribution showerhead of claim 1 , wherein the upstream side of the body comprises bare aluminum.

5. The gas distribution showerhead of claim 1 , wherein each of the plurality of gas passages include a first bore and a second bore surrounding the orifice hole.

6. The gas distribution showerhead of claim 5, wherein the anodized layer is disposed on surfaces of the orifice hole and the second bore.

7. The gas distribution showerhead of claim 5, wherein the anodized layer is disposed on surfaces of the orifice hole, a portion of the first bore, and an entirety of the second bore.

8. The gas distribution showerhead of claim 1 , wherein the anodized layer comprises a material selected from the group consisting of AI2O3, SiC>2, polytetrafluoroethylene and combinations thereof.

9. The gas distribution showerhead of claim 8, wherein the anodized layer has a thickness between about 1 micron and about 2 microns.

10. The gas distribution showerhead of claim 1 , wherein the anodized layer is a first anodized layer, and the upstream side of the body includes a second anodized layer that is different from the first anodized layer.

11 . The gas distribution showerhead of claim 10, wherein the first anodized layer has a composition that is different than a composition of the second anodized layer.

12. A plasma processing apparatus, comprising: a processing chamber body having walls and a floor; a susceptor disposed in the processing chamber body and movable between a first position and a second position; and a showerhead disposed in the processing chamber body opposite to the susceptor, the showerhead comprising: a body having a plurality of gas passages extending therethrough from an upstream side to a downstream side, the upstream side having a different porosity and roughness than the downstream side, wherein each of the plurality of gas passages include an orifice hole, and wherein the downstream side and a portion of each of the plurality of gas passages include a first anodized layer disposed thereon.

13. The apparatus of claim 12, wherein each of the plurality of gas passages include a first bore and a second bore surrounding the orifice hole, and wherein the anodized layer is disposed on surfaces of the orifice hole and the second bore.

14. The apparatus of claim 13, wherein the anodized layer is disposed on surfaces of the orifice hole, a portion of the first bore, and an entirety of the second bore.

15. The apparatus of claim 12, wherein the upstream side of the body includes a second anodized layer.

16. The apparatus of claim 12, wherein the upstream side of the body comprises bare aluminum.

17. A plasma enhanced chemical vapor deposition apparatus, comprising: a chamber body having a plurality of walls and a chamber floor; a susceptor disposed in the chamber body and movable between a first position spaced a first distance from the chamber floor and a second position spaced a second distance greater than the first distance from the chamber floor; a plurality of straps coupled to the susceptor and to one or more of the chamber floor and the plurality of walls, the plurality of straps are unevenly distributed along the susceptor; and a gas distribution showerhead disposed in the chamber body opposite the susceptor, the gas distribution showerhead comprising: a body having a plurality of gas passages extending therethrough from an upstream side to a downstream side, the upstream side having a different porosity and roughness than the downstream side, wherein each of the plurality of gas passages include an orifice hole, and wherein the downstream side and a portion of each of the plurality of gas passages include an anodized layer disposed thereon.

18. The apparatus of claim 17, wherein the anodized layer is disposed on surfaces of the orifice hole.

19. The apparatus of claim 17, wherein the upstream side of the body comprises bare aluminum.

20. The gas distribution showerhead of claim 17, wherein the anodized layer is a first anodized layer, and the upstream side of the body includes a second anodized layer.

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