JP5489390B2 - Suspension for showerhead in process chamber - Google Patents

Description

Field of Invention

  [0001] The present invention relates to an apparatus and method for hanging a showerhead that supplies a fixed amount of gas into a vacuum chamber used to fabricate flat panel displays, semiconductors and other electronic devices. More specifically, the present invention relates to minimizing stress in such suspensions caused by thermal expansion and contraction of the suspension and the showerhead.

Background of the Invention

  [0002] Electronic devices such as flat panel displays and integrated circuits are typically fabricated by a series of process steps in which layers are deposited on a substrate and the deposited material is etched into a desired pattern. The process steps generally include a plasma chemical vapor deposition (CVD) process, a thermal (non-plasma) CVD process and a plasma etch process.

  [0003] A substrate is typically placed on a susceptor (also called a chuck or workpiece support) in a vacuum chamber called a process chamber. CVD and etching processes generally require the substrate to be hot, in which case the susceptor is heated by some means such as resistive heating or radiant heating. In the plasma process, the plasma supplies additional heat to the substrate and the susceptor.

  [0004] A process gas mixture is generally fed into the process chamber via a gas distribution plate, commonly referred to as a showerhead, which is perforated by hundreds or thousands of orifices or channels. The showerhead generally has a flat or slightly curved lower surface positioned in close proximity and parallel to the upper surface of the substrate (and susceptor), and the gas flow path is over the entire surface of the showerhead. As a result, the process gas supplied in a certain amount via the shower head is uniformly distributed over the entire area of the substrate (and susceptor).

  [0005] In a plasma process, electrical or electromagnetic power is coupled to a process gas that is excited into a plasma state. The plasma decomposes the gas mixture into ionically active species that perform the desired deposition or etching process. In the capacitively excited plasma chamber, the plasma is excited by high frequency power applied between a showerhead that functions as an anode and a susceptor that functions as a cathode. An example of a showerhead in a plasma chamber is described in commonly assigned US Pat. No. 4,854,263, issued Aug. 8, 1989 to Chang et al.

  [0006] It is desirable to maintain the showerhead at a high temperature comparable to the temperature of the susceptor so that the showerhead does not cool the susceptor. Older showerhead designs use a relatively thick mounting flange that keeps the showerhead undesirably cool by transferring heat from the showerhead to a relatively cool wall of the process chamber. Was attached to the walls of the process chamber. In contrast, the same applicant's US Pat. No. 6,477,980 issued Dec. 11, 2002 to White et al., And the same issued on Oct. 8, 2004 to Keller et al. Applicant's US Pat. No. 6,772,827 discloses that heat absorbed by the showerhead from a heated susceptor and plasma is retained in the showerhead, thereby matching the temperature of the susceptor. An improved showerhead suspension is described having thin suspension walls with high thermal impedance to achieve head temperature.

  [0007] The aforementioned US Pat. Nos. 6,477,980 and 6,772,827 further describe suspension walls that are flexible to accommodate the thermal expansion of the heated showerhead. ing. For example, both patents describe rectangular aluminum showerheads suspended by four suspension segments (suspension walls) connected to four sides of the showerhead, respectively, where each suspension wall is A rectangular aluminum sheet. Each sheet is thin enough to be flexible so that the sheet bends easily to accommodate the thermal expansion of the showerhead in a direction generally perpendicular to the surface of the sheet.

  [0008] The above-mentioned US Pat. No. 6,772,827 (FIGS. 5-7 and 17) shows that each suspension wall is not rigidly attached to the showerhead and is located within the bottom flange of each suspension wall. An additional improvement is described which is attached by a pin projecting downwardly from the edge of the showerhead, which engages a corresponding slot. The slots are larger than the pins so that each suspension wall can slide relative to the showerhead in a horizontal direction parallel to the plane of the suspension wall, i.e., perpendicular to the direction in which the suspension wall bends. ing. As described in the patent, allowing such sliding is useful to accommodate rapid thermal contraction of the suspension when the chamber lid is open to air; Thereby, the suspension is cooled much more easily than a larger showerhead.

  [0009] However, Applicants have found that when the temperature of the bottom flange of the showerhead and suspension exceeds about 220 ° C, the static friction of aluminum may prevent the suspension wall from sliding relative to the showerhead. I found Thus, if the chamber lid opens when the suspension is hot, the suspension cools and contracts rapidly, while the bottom flange remains attached to the showerhead and thus receives a thermal shock. there is a possibility.

  [00010] Moreover, even though the pins and slots successfully avoid stresses between the suspension and the showerhead, the pins and slots are subject to a rapid temperature difference between the top and bottom of the suspension wall. Due to the change, potential damage stress in the suspension wall cannot be avoided. Applicants have discovered that such a rapid change in temperature difference generally occurs when a hot suspension is cooled rapidly. Such rapid cooling can occur when a low temperature process such as a chamber purge process follows immediately after a high temperature process such as a thermal CVD or plasma process process. Accordingly, there is a need for an improved design that reduces thermally induced stress in the suspension wall.

Summary of the Invention

  [00011] The present invention includes various aspects that can be used separately or in combination to improve thermally induced stress in the suspension wall.

  [00012] One aspect of the present invention provides a gas seal that surrounds the side of a space (ie, the gas inlet plenum) through which process gas flows from a gas inlet in the chamber and through to a gas outlet in the showerhead. It is a skirt. Since the gas sealing skirt performs this gas enclosing function, the gas sealing skirt protects the suspension from exposure to process gas so that the suspension is external to the space surrounded by the gas sealing skirt. It is preferable that it can be positioned.

  [00013] More specifically, the gas sealing skirt is connected to either the chamber wall or the showerhead, but not to both. The upper or lower end of the gas sealing skirt that is not connected to either the chamber wall or the showerhead is defined by a number of gaps having a total area of about one third of the area of the outer surface of the gas sealing skirt. , Separated from either the chamber wall or the showerhead. The number of gaps is preferably zero.

  [00014] A second aspect of the invention is a suspension having one or more suspension walls, each of the suspension walls being one or more openings that collectively occupy at least 5% of the area of the suspension wall. including. The opening reduces the thermal stress of the suspension by reducing the area of the suspension wall that is exposed to the gas in the process chamber, thereby transferring heat between the suspension and such gas. Reduce the speed of

  [00015] The opening may be used to prevent stress (thermal shock) in the suspension wall when the chamber lid is opened for some reason and the chamber interior is exposed to the atmosphere without first cooling the chamber components. ) Is particularly advantageous. The opening reduces the area of the suspension wall that is exposed to atmospheric cold air entering the chamber, thereby reducing the cooling rate of the suspension wall.

  [00016] A third aspect of the invention is a suspension having one or more suspension walls, each of the suspension walls including a substantially vertical array of one or more tears in the suspension wall. . The substantially vertical array of one or more tears can be either a single substantially elongated slit that is vertically elongated, or a plurality of tears of some shape that are separated substantially vertically. . For purposes of this patent specification and claims, “substantially vertical” means within 45 degrees vertical. The tear can be a slit, perforation, or some form of opening that extends completely through the suspension wall. Alternatively, the tear may be a groove or notch that does not extend completely through the suspension wall. Advantageously, the tear improves the stress of the suspension wall by weakening the wall at the location of the tear, thereby facilitating horizontal deflection or buckling of the wall in response to thermal stress. can do.

  [00017] A fourth aspect of the present invention comprises replacing at least one of the suspension walls with a plurality of suspension walls, each center portion being coplanar. Replacing one suspension wall with two, three or more coplanar suspension walls reduces the width of each suspension wall by about 2, 3 or more, respectively, and accordingly each suspension wall The horizontal component of any thermally induced stress at is reduced.

Detailed Description of the Preferred Embodiment

1. Process chamber overview
[00030] FIGS. 1 and 2 show a process chamber that includes a suspended showerhead 20 and a gas sealing skirt 70 according to the present invention. Before describing the present invention, other components of the process chamber will be described.

  [00031] The process chamber provides a chemical process, which is one of a series of steps in the fabrication of an electronic device, such as a flat panel display or semiconductor, on a workpiece or substrate 10 on the workpiece. A vacuum chamber intended to be received. The workpiece is supported in the chamber by a workpiece support 12, also called a chuck or susceptor. Typical examples of workpieces 10 processed in the chamber include rectangular glass substrates on which flat panel displays are fabricated, or circular semiconductor wafers on which integrated circuits are fabricated. Including.

  [00032] The process chamber has a housing or chamber wall 14, 16, 18 that provides a vacuum enclosure for the interior of the chamber. In the illustrated embodiment, the side and bottom walls of the chamber are implemented as a single wall 14. The upper portion of the chamber wall is provided by a hinged lid 16 and a gas inlet manifold upper wall 18. An operator can access the interior of the chamber by raising or removing the lid 16. O-rings 45, 46, 48 (some not shown) provide a vacuum seal between the chamber side and the bottom wall 14, chamber lid 16, and gas inlet manifold top wall 18. The chamber side and bottom wall 14, the chamber lid 16 and the gas inlet manifold top wall 18 are all considered part of the chamber wall.

  [00033] When performing a process of fabricating a semiconductor or other electronic device on the workpiece, one or more process gases are supplied into the chamber through a gas inlet manifold. The gas inlet manifold includes a gas inlet manifold top wall 18, a showerhead 20 (also referred to as a diffuser or gas distribution plate), and a gas inlet manifold sidewall (defined in the following three paragraphs), all of which are Collectively, it encloses a space referred to herein as a gas inlet plenum 30 that constitutes an interior region of the gas inlet manifold.

  [00034] At least one gas inlet channel 26 is coupled between an external gas source (not shown) and a gas inlet plenum 30. In the embodiment of FIG. 1, the gas inlet channel is an opening or tube extending through the gas inlet manifold top wall 18. The gas source supplies process gas to a gas inlet passage 26 that flows from the passage into the gas inlet plenum 30 and then from the gas inlet plenum to a gas outlet passage in the showerhead 20. 22 through the interior of the chamber. Hundreds or thousands of gas outlet channels 22 are typically evenly distributed throughout the showerhead.

  [00035] A conventional vacuum pump (not shown) maintains the interior of the chamber at a desired vacuum level, exhausts the process gas and reaction products from the chamber through an annular exhaust slit 31 into an annular exhaust plenum 32; Then, it discharges | emits to this pump through the discharge channel which is not shown in figure.

  [00036] The gas inlet manifold sidewalls are defined as one or more process chamber components that collectively provide a gas seal extending between the gas inlet manifold top wall 18 and the showerhead 20. In the preferred embodiment shown in FIG. 2, the novel gas sealing skirt 70 of the present invention (described below) functions as the gas inlet manifold sidewall. In an alternative embodiment that lacks a gas sealing skirt, but can be otherwise equivalent, the suspension 50 functions as the gas inlet manifold sidewall.

  [00037] The gas inlet manifold sidewalls must provide a sufficient hermetic seal, ie, sufficient impedance to gas leaks, so that most of the gas flowing into the gas inlet plenum 30 is present in the gas inlet. Rather than leaking through a gap in the manifold sidewall, it flows into the interior of the process chamber by flowing through the showerhead gas outlet channel 22. The amount of leak that can be tolerated depends on the process being performed on the workpiece, but for most processes the leak should be less than 10%. That is, less than 10% (1/10) of the gas entering the gas inlet plenum through the gas inlet channel 26 should be leaked through the gas inlet manifold sidewall, so that at least 90% must be supplied in a certain amount into the process chamber via the gas outlet channel 22. Even in the worst case, 40% or less of the gas entering the gas inlet plenum should leak through the gas inlet manifold sidewall.

  [00038] The gas inlet manifold generally prevents gas from flowing from the gas inlet channel 26 in a straight path to the gas outlet channel 22 directly adjacent to the center of the showerhead, thereby providing a A gas inlet deflector 28 is included to help equalize the flow of each gas through the center and periphery. In the embodiment of FIG. 1, the gas inlet deflector 28 comprises a circular disk having a diameter slightly larger than the diameter of the gas inlet channel 26 and suspended below the gas inlet channel by a post not shown. .

  [00039] In a preferred embodiment, the showerhead 20 is a 3 cm thick aluminum plate. Preferably, the showerhead should be sufficiently thick so that it does not deform significantly under atmospheric pressure when the chamber is in a vacuum.

  [00040] The showerhead 20 is suspended at its periphery by a flexible suspension comprising one or more suspension walls 50. The flexibility of the suspension accommodates the radial expansion and contraction of the shower head as the shower head temperature rises and falls. The suspension will be described in detail in the following section “2. Flexible shower head suspension”.

  [00041] Some types of workpiece fabrication processes that are performed in a process chamber, such as thermal chemical vapor deposition (CVD) processes, are performed without a plasma. Many other processes, such as a plasma-enhanced chemical vapor deposition (PECVD) process or a plasma etching process, do not require a plasma. A process chamber intended for plasma is called a plasma chamber.

  [00042] In one type of plasma chamber, plasma is generated in the chamber by capacitively coupled electrical power to the plasma by a radio frequency (RF) power source (not shown) connected to electrodes in the chamber. Or sustained in the chamber. In a capacitively coupled plasma chamber, the showerhead 20 is typically composed of a conductive material, preferably aluminum, so that the showerhead functions as an electrode. For this reason, it is important to provide sufficient electrical and reliable electrical contact to the showerhead to conduct high levels of high frequency power, typically high frequency power on the order of kilowatts.

  [00043] In some plasma chamber structures, the showerhead 20 is directly connected to electrically grounded chamber walls 14-18. However, the illustrated embodiment is intended for the showerhead 20 to be electrically connected to the ungrounded (RF hot) output of the high frequency power source so that the showerhead functions as an anode. This is a plasma chamber structure. The side and bottom walls 14 of the chamber and the chamber lid 16 are connected for electrical grounding and thus function as a cathode. The susceptor or workpiece support 12 is also typically electrically grounded, but can optionally be connected to a second high frequency power source commonly referred to as a bias power source. The present invention is useful regardless of whether or not high frequency power is supplied to the shower head.

  [00044] Because the high frequency power is supplied to the gas inlet manifold upper wall 18 and the showerhead 20, the insulating liners 33, 34, 35, 36 are electrically grounded to the components to which the high frequency power is supplied. It is placed between the chamber lid 16. In order to concentrate the plasma in the region of the chamber between the workpiece support 12 and the showerhead 20, the workpiece support or other metal surface in the chamber near the showerhead is Generally, it is coated with an insulating liner. For example, FIG. 1 shows an insulating liner 37 that covers the lower surface of the chamber lid 16 and an insulating liner 38 that covers the inner surface of the chamber sidewall 14.

  [00045] The cover 19 is generally attached to the top of the chamber lid 16 to prevent an operator from accidentally touching the top wall 18 or shower head to which high frequency power is supplied. Cover 19 is not critical to the functionality of other chamber components discussed herein and will not be discussed further.

  [00046] In the plasma chamber, the gas outlet channel 22 in the showerhead should have a diameter smaller than the width of the plasma dark in order to prevent the plasma in the plasma chamber from entering the gas inlet plenum 30. is there. The width of the dark space and thus the optimum diameter of the gas outlet channel depends on the chamber pressure and other parameters related to the particular semiconductor fabrication process that is desired to be performed in the chamber. Alternatively, to perform a plasma process using a reagent gas that is particularly difficult to dissociate, a narrow inlet and, as described in U.S. Pat. No. 4,854,263 to Chang et al. It may be preferable to use a flow path that is wide and has a protruding outlet.

  [0047] The chamber components should be composed of materials that do not contaminate the semiconductor fabrication process performed in the chamber and are resistant to corrosion by the process gas. Aluminum is the preferred material for all components in the chamber except for the O-ring and insulating liners 33-36.

2. Flexible suspension for shower head
[0048] Figures 2 and 3 show the suspension in detail. The shower head 20 is suspended by a flexible suspension that includes one or more flexible suspension walls 50. The flexibility of the suspension accommodates the radial expansion and contraction of the shower head as the shower head temperature rises and falls.

  [0049] The amount by which the showerhead 20 expands is proportional to the temperature of the showerhead both with the width of the showerhead. For the latter reason, adapting to the thermal expansion of the showerhead without mechanical stress is particularly important for larger showerheads required to process larger workpieces such as large flat panel displays. is there. In order to minimize heat transfer from the work piece and susceptor to the showerhead, it is desirable to perform a CVD process in the chamber while maintaining the showerhead at 350 ° to 400 °. At such high temperatures, the aluminum showerhead expands by about 1% in each outer dimension. For example, a 105 cm × 125 cm wide showerhead expands about 12 mm. With respect to a fixed reference point in the center of the showerhead, each edge of the showerhead expands outward by half this amount (0.5%).

  [0050] When the width of the showerhead 20 expands in response to an increase in temperature during normal operation of the chamber, the showerhead pushes the flexible suspension wall 50 outward (ie, relative to the surface of the suspension). Deflection of the showerhead (in a direction substantially perpendicular to the showerhead radius).

  [0051] In order to support the weight of the shower head, the upper portion of the flexible suspension 50 is connected directly or indirectly to the chamber walls 14-18, and the lower portion of the suspension is directly connected to the shower head 20. Or indirectly connected. “Indirectly connected” means that an intervening component, such as an insulating liner or mounting flange, can be connected between the top of the suspension and the chamber wall. Similarly, such intervening components can be connected between the lower part of the suspension and the showerhead.

  [00052] Where two components are described as being connected throughout this patent specification, the two components may be connected directly or indirectly, except in certain other ways. And the two components may be fabricated as a single component rather than two separate components attached together. For example, the suspension 50 and the showerhead 20 can be machined from a single block of aluminum.

  [00053] The illustrated embodiment is intended for processing large rectangular glass substrates or workpieces 10 on which flat panel displays are fabricated. The workpiece support or susceptor 12, the gas inlet manifold upper wall 18 and the showerhead 20 are rectangular in cross section. The suspension includes four suspension walls 50 respectively connected to the four sides of the showerhead. Each of the four suspension walls is an aluminum sheet having a flat central portion extending between the gas inlet manifold upper wall 18 and the showerhead. The flat central portion is thin enough to bend so that it can be bent in response to thermal expansion and contraction of the showerhead.

  [00054] Each of the four seats 50 is bent at a right angle near its upper end to form an upper flange 52, and to form a lower flange 54, as shown in FIG. It is bent at a right angle near its lower end.

  [00055] The upper flange 52 of each suspension wall 50 is attached to the gas inlet manifold upper wall 18 by bolts 40. Preferably, the attachment of each upper flange 52 to the gas inlet manifold upper wall has a U-shaped cross section that spans the full width of each upper flange 52 and is positioned between the bolt head and the upper flange. The aluminum bar 42 is reinforced. The illustrated embodiment includes four reinforcing bars 42, one for each upper flange 52.

  [00056] The lower flange 54 of each suspension wall is slidably provided in a groove 62 in the edge 60 of the showerhead. In order to prevent the lower flange 54 from slipping out of the groove 62, each lower flange has a plurality of mounting holes 56, 57 that each engage a corresponding pin 64 extending downwardly from the edge of the showerhead. To do. As shown in FIG. 2, the edge of the showerhead includes a notch adjacent to each pin to form a space for inserting the pin. After insertion, the lower end of each pin can be bent inward so that the pin is pushed over a small outward projection on the edge of the showerhead that prevents the pin from falling.

  [00057] As shown in FIG. 3, a small number of mounting holes 56 near the center of each lower flange 54 are circular with a diameter slightly larger than the diameter of the pin, thereby providing a center of the showerhead. The alignment with the suspension wall 50 is maintained. The remaining mounting holes 57 extend along the direction, i.e., parallel to the edge of the shower head and along the horizontal direction perpendicular to the plane of the central portion of the suspension wall. It is elongated in a parallel direction along the length of the lower flange to allow relative thermal expansion and contraction with the flange.

  [00058] In the embodiment of FIG. 1 described above, the flexible suspension 50 supports the entire weight of the shower head 20. Since this embodiment of the suspension supports the showerhead only near its periphery, the central portion of the showerhead can be slid over time. In order to prevent the center portion from sagging, it is preferable to add shower head center portion supports 100 to 108 as shown in FIG. 4 to the suspension.

  [00059] The showerhead center support 100-108 has a tubular gas conduit 100 that extends through a central opening in the gas inlet manifold top wall 18. The shower head 20 has a cavity extending to two-thirds of the depth of the shower head at the center of the upper surface thereof. The lower end of the gas conduit extends into the cavity and extends to the lower surface of the complementary flange of the showerhead extending radially inward over the opening of the cavity. A central portion of the shower head is mechanically supported by a flange extending radially outward from the portion. Accordingly, the central support members 100 to 108 support a part of the weight of the shower head, and the flexible suspension 50 supports the remaining weight.

  [0060] A plurality of radially extending gas passages 102 couple the interior of the gas conduit 100 to the gas inlet plenum 30. One or more downwardly extending channels 104 couple the interior of the gas conduit to a cavity or plenum between the bottom of the gas conduit and the upper end of the showerhead gas channel 22 below the cavity. To do. As a result, the interior of the gas conduit 100 and the gas flow paths 102, 104 function together as the gas inlet flow path 26.

  [00061] The upper end of the gas conduit 100 is attached to and mechanically supported by the chamber cover 19 by a mounting ring 106 and jack screw 108 that allow for adjustment of the height of the gas conduit. Yes. When the gas conduit is raised, the central portion of the shower head 20 is raised. Therefore, the height of the gas conduit can be adjusted to prevent the center portion of the showerhead from sagging or to achieve the desired appearance of the showerhead.

[00062] A mounting ring 106 surrounds a portion of the gas conduit 100 that extends through the chamber cover. The mounting ring 106 is rigidly attached to the chamber cover, preferably by bolts. The upper end of the gas conduit is attached to the upper end of the mounting ring by a plurality of jack screws so that the height of the gas conduit can be adjusted by rotating the jack screw. Specifically, the upper end of the gas conduit has an outwardly extending flange having a plurality of screw holes for receiving the jack screws. The lower end of each screw extends into the screw hole of the mounting ring. (A jack screw is an ordinary screw, and the term “jack” simply describes its function.)
[00063] All aspects of the invention described below are useful in both the embodiment of FIG. 4 with a showerhead center support and the embodiment of FIG. 1 without such a center support. is there.

3. Suspension stress problem during cooling
[00064] In order to minimize the stress between the suspension 50 and the showerhead 20 caused by different thermal expansions, the suspension and the showerhead are preferably composed of the same material, preferably aluminum, As a result, the suspension and the showerhead expand and contract by the same amount in response to temperature changes. Further, the above-described method of slidably attaching the lower flange 54 of each suspension wall to the shower head by the pin 64 engaged with the elongated hole 57 is pulled by the temperature difference between the suspension wall and the shower head. Allows a certain amount of relative movement between the suspension wall and the showerhead to accommodate different thermal expansions that may occur.

  [00065] However, as mentioned in the background of the present invention, rapid changes in the temperature gradient in the suspension wall will eventually cause stresses that can deform, crack, or tear the suspension. Can cause In practice, such a rapid change in temperature gradient is generally observed when performing a process sequence immediately following a high temperature process step such as a thermal CVD or plasma process step followed by a low temperature step such as a chamber purge step. Caused by rapid cooling of the suspension walls. Also, rapid cooling is performed when the chamber lid 16 is opened for some reason and the suspension wall 50 is exposed to the atmosphere without first allowing the chamber components, particularly the showerhead, to cool to room temperature. It is possible that

  [00066] When such rapid cooling occurs, the suspension wall 50 typically has a significantly lower heat quantity, since the suspension wall is preferably much thinner than the showerhead. It cools much faster than the showerhead 20. The suspension wall is intended to be thin enough to be extremely flexible so that it can be bent outward to accommodate the thermal expansion of the showerhead. In contrast, the showerhead may cause spatial non-uniformity in the process performed on the workpiece, so that depending on the temperature gradient, It should be thick enough to avoid distortion of appearance. For example, in a preferred embodiment, the suspension wall is an aluminum sheet having a thickness of 1 mm, whereas the aluminum showerhead has a thickness of 30 mm.

  [00067] When cooling gas is supplied to the gas inlet plenum 30, the suspension wall 50 cools much faster than the showerhead 20 because it has a much lower amount of heat. Also, because the shower head cools slower and has a higher amount of heat, the shower head transfers heat to the lower part to prevent the lower part of each suspension from cooling as fast as the upper part. It will be. The resulting temperature gradient between the cold upper portion and the hot lower portion of each suspension wall 50 will shrink faster than the lower portion as the upper portion is cooled more rapidly. , Generate mechanical stress in each suspension wall. Such mechanical stress caused by a temperature gradient is generally referred to as thermal stress or thermal shock.

  [00068] The present invention provides four solutions that are useful alone or in combination to reduce thermal stresses in the suspension walls. (1) a gas-tight skirt that helps to protect the suspension wall from direct contact with process gas; (2) exposure of the suspension wall to process gas or atmosphere when the chamber lid is opened. (3) a substantially vertical alignment of one or more tears in the suspension wall that facilitates horizontal buckling or deflection of the suspension wall; (4) ) A plurality of suspension walls, each center part of which is coplanar.

4). Gas tight skirt
[00069] One aspect of the present invention is that the process gas shown in FIGS. 1, 2, 4 and 5 passes through a gas inlet 26 in the chamber wall through the gas outlet 22 in the showerhead 20. A gas sealing skirt 70 that surrounds the side of the space flowing through (i.e., the gas inlet plenum 30).

  [00070] In the prior art suspended showerhead described in the background of the present invention, the side of the gas inlet plenum is surrounded by the suspension wall. In the present invention, this gas-enclosing function is performed by the gas sealing skirt 70 rather than the suspension wall. As a result, the present invention allows the suspension wall 50 to be positioned preferably outside the space (ie, gas inlet plenum 30) enclosed by the gas sealing skirt, so that the gas sealing skirt As in the preferred embodiment shown in FIGS. 1, 2, 4 and 5, it is interposed between the gas inlet plenum 30 and the suspension wall 50. In this preferred embodiment, the gas sealing skirt protects the suspension wall from direct contact with the process gas entering the chamber, so that after performing a hot process in the chamber, the cooling process gas is When rapidly supplied, the cooling rate and temperature gradient of the suspension are reduced.

  [00071] In the alternative embodiment of FIG. 4, the flexible suspension wall 50 is external to the gas inlet plenum 30, but the suspension further includes a showerhead center support 100 that is within the gas inlet plenum. That is, the central support 100 is not protected from direct contact with the process gas by the gas sealing skirt 70.

  [00072] Returning now to the general description of the present invention rather than the illustrated embodiment, the gas sealing skirt 70 includes an upper portion adjacent to the chamber walls 14-18 and a lower portion adjacent to the showerhead 20. It extends in between. As described in the next three paragraphs, “adjacent” means “connected to”, “abutted”, or “by one or more gaps specified in the following paragraphs” It means “separated”.

  [00073] The gas sealing skirt 70 is connected to either the chamber wall or the showerhead, but not to both of them. That is, either the upper end of the gas sealing skirt is connected to the chamber wall or the lower end of the gas sealing skirt is connected to the showerhead, but not both. Thus, unlike the suspension 50 connected to both the chamber wall and the showerhead, the gas-tight skirt does not support the weight of the showerhead, and the skirt does not support the showerhead and the chamber. Has greater freedom to expand or contract without being limited by the distance to the wall. The upper or lower end of the gas sealing skirt that is not connected to either the chamber wall or the showerhead is referred to as the “unconnected” end of the gas sealing skirt.

  [00074] To clarify the terminology used in the previous paragraph, when the upper end of the gas sealing skirt 70 is connected to the chamber walls 14-18, the lower end of the gas sealing skirt is The “unconnected end” of the sealing skirt and the “one component” are the shower head 20. Conversely, when the lower end of the gas sealing skirt is connected to the shower head, the upper end of the gas sealing skirt is the “unconnected end” of the gas sealing skirt, The “one component” is the chamber wall.

  [00075] Since the gas sealing skirt 70 is not connected to either the chamber walls 14-18 or the showerhead 20, the unconnected upper or lower end of the gas sealing skirt is caused by a number of gaps. Can be separated from the one component, and the number of gaps is greater than or equal to zero. If the number of gaps is zero, the unconnected end of the gas sealing skirt contacts the one component as illustrated by the embodiment of FIGS. 6 and 7 described in detail below. Means contact. Also, as described below, FIG. 8 illustrates a non-zero gap between the gas tight skirt and the suspension.

[00076] The gas sealing skirt includes the chamber wall, the showerhead, the gas sealing skirt, and the gap described above, and a gas inlet plenum 30, ie, process gas, passes from the gas inlet channel 26 therethrough. The gas sealing skirt is installed so as to surround a side portion of the region between the chamber wall and the shower head so as to surround a space that can flow to the gas outlet channel 22. (In the specification of the present application, the term “surround” means that the side portion of the above-described region is surrounded by a band or does not include the meaning of a circular shape.)
[00077] As described above, the gas sealing skirt is such that the gas sealing skirt is interposed between the gas inlet plenum and the suspension wall 50, ie, the suspension wall 50 is external to the gas inlet plenum 30. Thus, it is preferably positioned radially inward of the suspension wall 50. In the gas sealing skirt 70, when the number of the gaps is zero as specified in the previous paragraph, that is, the upper end or the lower end of the gas sealing skirt not connected to the gas sealing skirt is connected. In the absence of a gap with a non-existing component, the process gas flowing through the gas inlet plenum 30 will be completely prevented from contacting the suspension, in which case such a component is Either the chamber walls 14-18 or the showerhead 20, as described in the previous paragraph.

  [00078] Conversely, in the presence of such a gap, some of the process gas entering the gas inlet plenum 30 leaks through the gap and contacts the suspension wall 50, which is undesirable. The suspension wall is cooled. The percentage of process gas that leaks through the gap is determined by the total area of the gap and the inner surface 74 of the gas sealing skirt, i.e., the gas inlet plenum 30, i. It is roughly proportional to the ratio of the area. For the gas sealing skirt that substantially protects the suspension wall from undesired cooling by the process gas flow, the present invention provides that the total area of the gap is 3 minutes of the area of the inner surface of the gas sealing skirt. It is preferably intended to be no greater than one tenth so that it is not greater than one.

  [00079] In the illustrated preferred embodiment where the cross section of the gas inlet manifold top wall 18 and showerhead 20 is rectangular, the gas sealing skirt 70 is preferably each on four sides of the gas inlet manifold top wall. It has four connected segments. Each of the four segments is preferably a rectangular aluminum sheet.

  [00080] The lower end of each sheet of the gas sealing skirt 70 is preferably adjacent to the edge 60 of the shower head 20 so as to minimize the size of the gap between the gas sealing skirt and the shower head. It has been picked up. In the preferred embodiment shown in FIG. 2, the upper surface of the showerhead edge 60 includes a groove 66 proximate to and parallel to the periphery of the showerhead. The lower end of each sheet of the gas sealing skirt extends into the groove 66, thereby extending below the upper surface of the showerhead. When the shower head expands in response to the raised temperature, the radially inner side wall of the groove 66 contacts the lower end of each sheet of the gas sealing skirt 70 and pushes the lower end outward. As a result, any gap between the gas sealing skirt and the showerhead can be ignored, thereby forming a good gas seal between the gas sealing skirt and the showerhead.

  [00081] As explained in the previous section entitled "2. Flexible suspension for showerheads", each sheet of the gas tight skirt 70 is preferably thin enough to bend. In a preferred embodiment, each sheet is 1 mm thick aluminum. Since the gas sealing skirt is flexible, when the showerhead is heated and radially expanded during operation of the chamber, the edges of the showerhead will cause the flexible sheet 70 of the gas sealing skirt to The abutting lower end may be pushed radially outward, so that the gas tight skirt remains in contact with the showerhead. As a result, any gap between the gas sealing skirt and the showerhead remains negligible at all temperatures experienced by the gas sealing skirt and the showerhead during operation of the chamber. is there. As described in the second paragraph of the above-mentioned paragraph "2. Flexible suspension for shower head", each side of the aluminum shower head 20 is located with respect to its central portion at a typical operating temperature of the plasma chamber. And expands by about 0.5%. Thus, each sheet of the gas sealing skirt is preferably at least 0.5 of the horizontal width of one side of the gas sealing skirt radially outward (ie perpendicular to the plane of the sheet). % Flexible enough to bend.

  [00082] The upper end of each rectangular aluminum sheet of gas sealing skirt 70 can be bent preferably at a right angle to form an upper flange 72 that can be connected to chamber walls 14-18. That is, the upper end of each of the four aluminum sheets functions as an upper flange 72, the remaining portion of each sheet extending downward from the upper flange functions as a gas sealing skirt 70, and the upper flange 72 is The gas sealing skirt 70 is connected to the chamber walls 14-18.

  [00083] Preferably, each of the four upper flanges 72 is gas-filled using the same bolt 40 that is used to bolt the upper flanges 52 of the four suspension walls 50 to the gas inlet manifold upper wall 18. Fixed to the inlet manifold top wall 18. The gas sealing skirt upper flange 72 preferably extends radially inward from the bolt a distance longer than the suspension upper flange 52, so that the gas sealing skirt 70 has a diameter from the suspension wall 50. It is separated inward in the direction. The radial spacing between the gas sealing skirt and the suspension wall must be large enough to prevent them from contacting each other when they undergo thermal expansion or contraction. In a preferred embodiment, this radial spacing is about 5 mm at room temperature.

[00084] FIGS. 6, 7 and 8 show alternative designs for the portion of the showerhead edge 60 adjacent to or abutting the lower end of the gas sealing skirt 70. FIG.

  [00085] In the embodiment of FIG. 6, each sheet of the gas sealing skirt extends below the upper surface of the showerhead so as to abut the radially outer surface of the showerhead edge 60. In this embodiment, each sheet of the gas sealing skirt preferably has an upper end of the sheet extending in the vertical direction of the gas sealing skirt when the showerhead is cooled (ie, at room temperature), The chamber is connected to the chamber wall at a position slightly inward of the periphery of the shower head edge. That is, the lower end portion of the gas sealing skirt is outside the upper end portion so that a certain amount of tension is maintained between the shower head edge and the lower end portion of the gas sealing skirt at all temperatures. Has been deflected so that any gap between the gas-tight skirt and the showerhead is negligible at all temperatures.

  [00086] In the embodiment of FIG. 7, the lowermost end of the gas sealing skirt is slightly above the top surface of the showerhead 20. The upper surface of the showerhead edge 20 includes an upward protruding ridge or stop 68 whose radially outer surface is in contact with the radially inner surface of the lower end of each sheet of the gas-tight skirt. A ridge 68 extends parallel to the perimeter of the showerhead along the full width of each sheet of the gas sealing skirt so that any gap between the sheet and the gas sealing skirt is negligible. Similar to the embodiment of FIG. 6, each sheet of the gas sealing skirt is preferably configured such that when the shower head is cooled, the upper end of the sheet extending vertically in the gas sealing skirt has the shower It is connected to the chamber wall at a position that is slightly radially inward of the outer surface of the head edge ridge 68.

  [00087] In the embodiment of FIG. 8, the gas sealing skirt does not contact any part of the shower head 20, but the lowermost end of the gas sealing skirt is close to the upper surface of the shower head edge 60. Is positioned. The total area of the gap between the lower end of the gas sealing skirt and the showerhead should be as large as the specified maximum area.

  [00088] The unconnected end of the gas sealing skirt is the bottom end in the illustrated embodiment, but the present invention is such that the unconnected end of the gas sealing skirt is the upper end, Alternative implementations in which the bottom end of the gas sealing skirt is connected to the showerhead are also included.

5. Opening that reduces the surface area of the suspension wall
[00089] To improve or avoid the stress described in section "3. Suspension Stress Issues During Cooling", the second aspect of the present invention comprises providing an opening 80 in each suspension wall 50. . Such an opening reduces the surface area of the suspension wall that is exposed to the gas in the process chamber, thereby reducing heat transfer between the suspension wall and the gas. Thus, when the chamber lid is opened so that cold air at room temperature and atmospheric pressure flows into the chamber, the opening reduces the cooling rate of the suspension wall, thereby reducing the stress in the suspension wall ( (Thermal shock) is reduced.

  [00090] To substantially reduce heat transfer between the suspension wall 50 and the gas in the process chamber, an opening 80 in each suspension wall is the portion of the suspension wall that is exposed to the gas, ie, , It must collectively occupy at least 5%, preferably at least a quarter of the total area of the portion extending vertically between the chamber walls 14-18 and the showerhead 20. The “total area” here includes both the area of the solid line portion of the suspension wall and the area of the opening 80. Alternatively, in a less severe expression of the present invention, the openings 80 in each suspension wall must collectively occupy at least 5%, preferably at least a quarter of the area of the suspension wall. is there. The total area of opening 80 does not include any area occupied or covered by bolts or fasteners inserted through some of the openings.

  [00091] FIG. 9 illustrates a preferred embodiment in which the apertures 80 occupy about two-thirds of the area of each suspension wall 50 extending vertically. Each of the four suspension walls extends in the vertical direction so that each opening 80 spans substantially all of the vertical height of the suspension wall. In this preferred embodiment, the lateral spacing between the openings is about half the width of each opening, so that the openings occupy about two thirds of the area of the vertical portion of each suspension wall.

  [00092] FIG. 10 shows an alternative embodiment in which the opening 80 extends to the end of the suspension that is not connected to either the chamber walls 14-18 or the showerhead 20. In the illustrated embodiment, the unconnected end of the suspension is the lower flange 54 at the bottom end of each suspension wall 50 so that each opening 80 is radially directed to the lower flange between adjacent openings 80. It extends beyond the lower flange to form an extending “finger”. In an alternative embodiment, the lower end of each finger includes one of mounting holes 56, 57 that engage a corresponding pin 64 in the showerhead edge, so the number of openings 80 at each lower end of the suspension. Is smaller than the number of mounting holes 56, 57.

  [00093] Compared to the preferred embodiment of FIG. 9, the alternative embodiment of FIG. 10 is that (1) the suspension expands and contracts in the direction of arrow 82, ie, in the horizontal direction of the surface of the suspension wall. In that case, it has the advantage of further reducing the stress in each suspension, (2) allowing each finger to twist to accommodate different thermal expansions between the showerhead and the suspension. However, the alternative embodiment of FIG. 10 (1) aligns the mounting holes 56, 57 in the lower flange 54 with the corresponding pins 64 in the showerhead edge as compared to the embodiment of FIG. 9. (2) The “finger” of the lower flange is somewhat affected by being bent for some reason by the operator attaching the showerhead to the suspension It has two potential disadvantages.

  [00094] FIG. 11 shows that each opening 80 is not completely cut away from the suspension side wall 50, but instead only a portion around the opening is cut and formed to form one edge (not shown). The left edge in the embodiment) shows the various embodiments of FIG. 9 that remain unchanged. The unchanged edge acts as a hinge that allows the suspension sidewall portion 81 around the opening to be pushed outward to form the opening.

6. Vertical alignment of one or more rifts
[00095] In order to improve the heat-induced stress in the suspension wall described in the section "3. Problems of suspension stress during cooling" above, the third aspect of the present invention provides each suspension wall 50 with 1 Providing at least one substantially vertical array of at least one tear. The tear can improve the stress at the suspension wall by weakening the wall at the location of the tear, thereby facilitating horizontal deflection or buckling of the wall in response to thermal stress. . Such flexing or buckling can reduce the risk that repeated stresses will ultimately deform the wall, crack the wall, or tear the wall. Can be released.

  [00096] A tear can be formed in the suspension wall by any means such as cutting, drilling or punching. Further, the tear can be any shape and need not extend through the entire suspension. For example, the tear can be a slit, a punched hole, or an opening shaped to extend through the entire suspension wall. Such tears can be formed, for example, by cutting or drilling the suspension wall to create an incision without removing any material from the wall, or creating an opening. Can be formed by removing material from the wall. Alternatively, the tear may be a groove or notch that does not extend through the entire suspension wall. However, the fastener may interfere with the function of the opening facilitating the deflection or buckling of the suspension wall, so the rift is caused by a bolt or other fastener that securely attaches the suspension wall to another object. Does not include occupied openings.

  [00097] The substantially vertical arrangement of the one or more tears is a single tear that is substantially vertically elongated (Figure 12), or any shape that is substantially vertically spaced apart. It can be any of a plurality of tears (FIG. 13). FIG. 12 shows a suspension wall 50 having a plurality of vertically elongated tears 84, where each vertically elongated tear 84 is oriented in a vertical direction that is formed such that the suspension material is not removed. It consists of a slit. FIG. 13 shows the suspension wall 50 having a plurality of vertically elongated tears 84, where each vertically elongated tear 84 comprises a plurality of vertically spaced circular openings 86.

  [00098] For purposes of this patent specification and claims, "substantially vertically" means within 45 degrees of vertical. In the case of splits of any shape that are substantially vertically spaced apart, the splits need not be collinear, and the splits are elongated regions that are oriented within 45 degrees of the vertical. It is enough to be located within.

  [00099] Arranging one or more tears in each suspension wall in a substantially vertical rather than horizontal direction is important to achieve the best stress reduction. Specifically, the substantially vertical alignment of the tears in the suspension wall facilitates the horizontal deflection (in the direction of arrow 82) of the surface of the suspension wall, thereby allowing the suspension wall to flex or buckle. The horizontal component of stress is released. The horizontal stress of the suspension wall can typically be relieved by the suspension wall deflecting inward or outward. However, in the absence of a substantially vertical arrangement of rips according to the present invention, the upper portion of each suspension wall (such as upper flange 52 in FIG. 3) typically has a plurality of widths along its width. At a location that is rigidly bolted to the chamber walls 14-18, and the lower portion of each suspension wall (such as the lower flange 54 in FIG. 3) is typically rigidly connected to the edge 60 of the showerhead 20. Since horizontal expansion is limited by the width of the elongated mounting hole 57, horizontal stress typically cannot be easily relieved.

7). Coplanar suspension wall
[00100] In order to improve the heat-induced stress in the suspension wall described in the section “3. Problem of suspension stress during cooling” above, the fourth aspect of the present invention provides at least one suspension wall 50. , Comprising a plurality of coplanar suspension walls 50 as shown in FIG.

  [00101] To be more precise, the suspension walls 50 described herein as being coplanar are actually coplanar only at their respective central portions. Such a suspension wall has a central part between an upper part and a lower part, in which case the upper part is connected to the chamber walls 14 to 18, and the lower part is connected to the showerhead 20. It is connected. The upper and lower portions may include flanges 52, 54 that are not coplanar. However, at least two of the suspension walls have a central portion that is coplanar. Preferably, the coplanar central portions of the two suspension walls are separated horizontally by a vertical gap 88.

  [00102] When the number of coplanar suspension walls is represented by the variable N, each coplanar wall will have a width that is reduced by approximately N times compared to the width of the single suspension wall to replace. The width of each coplanar wall is reduced by a larger multiple if the gap 88 between the coplanar walls has a width that is at least a fraction of the width of each coplanar wall. Become.

  [00103] Comparing the embodiment of the invention shown in FIG. 14 with the prior art design shown in FIG. 3, the two long suspension walls 50 of FIG. 3 are approximately one third in the design of FIG. Is replaced by three walls (N = 3). The two shorter suspension walls in FIG. 3 have been replaced in FIG. 4 with two walls (N = 2) of approximately half width.

  [00104] Reducing the width of the suspension wall correspondingly reduces the horizontal component of any thermally induced stress in the suspension wall. Therefore, the present invention must reduce the risk that the suspension wall will eventually undergo deformation, cracking or tearing in response to such stress.

  [00105] When the showerhead 20 is rectangular as shown in FIG. 14, the suspension walls connected to a predetermined one of the four side portions of the showerhead should be coplanar And the suspension walls, each connected to two adjacent sides of the showerhead, should be at right angles.

1 is a partial schematic side cross-sectional view of a plasma chamber including a gas sealing skirt of the present invention. FIG. It is a vertical sectional view of a suspension, a shower head, and a gas sealing skirt. FIG. 2 is a plan view of a suspension showing the features that the preferred embodiment of the present invention uses the same as the prior art design. FIG. 2 is a partial schematic side cross-sectional view of a plasma chamber similar to that of FIG. 1 and further including a center support for the showerhead. FIG. 5 is a perspective view of the gas sealing skirt of FIGS. 1, 2, and 4. FIG. 3 is a vertical cross-sectional view of a suspension, shower head and gas sealing skirt similar to that of FIG. 2, but showing an alternative embodiment of the edge portion of the shower head adjacent to the lower end of the gas sealing skirt. FIG. 3 is a vertical cross-sectional view of a suspension, shower head and gas sealing skirt similar to that of FIG. 2, but showing an alternative embodiment of the edge portion of the shower head adjacent to the lower end of the gas sealing skirt. FIG. 3 is a vertical cross-sectional view of a suspension, shower head and gas sealing skirt similar to that of FIG. 2, but showing an alternative embodiment of the edge portion of the shower head adjacent to the lower end of the gas sealing skirt. FIG. 6 is a side view of one wall of a suspension having a vertically extending elongated opening according to a second aspect of the present invention. FIG. 6 is a side view of one wall of an alternative embodiment of a suspension, the opening of which extends to the bottom end of the suspension. FIG. 6 is a side view of one wall of a second alternative embodiment of a suspension in which each opening is formed by cutting only a portion of the periphery of the opening, leaving one edge. FIG. 6 is a side view of one wall of a suspension having one or more vertically elongated tears according to a third aspect of the present invention. FIG. 5 is a side view of one wall of an alternative embodiment in which the suspension has one or more vertical arrays of tears, each vertical array of tears comprising a plurality of generally spaced apart tears. . 7 is a plan view of a suspension comprising a plurality of coplanar suspension walls separated by a vertical gap according to a fourth aspect of the present invention. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Workpiece, 12 ... Workpiece support body, chuck, susceptor, 14 ... Chamber wall, 14 ... Chamber side and bottom wall, 15 ... Chamber wall, 16 ... Chamber wall, 16 ... Lid, 17 ... Chamber wall , 18 ... chamber wall, 18 ... upper wall, gas inlet manifold, 19 ... (does not work) cover, 20 ... shower head / diffuser, 22 ... gas outlet channel, 26 ... gas inlet channel, 28 ... gas inlet channel 30 ... gas inlet plenum (in the inner region of the gas inlet manifold), 31 ... exhaust slit, 32 ... exhaust plenum, 33 ... insulating liner, 34 ... insulating liner, 35 ... insulating liner, 36 ... insulating liner, 37 ... Insulating liner, 38 ... Insulating liner, 40 ... Bolt between upper flange and upper wall, 42 ... U-shaped bar, 45 ... O-ring, 46 ... O-ring, 4 ... O-ring, 48 ... O-ring, 50 ... suspension wall, 52 ... upper flange, 54 ... lower flange, 56 ... circular hole in lower flange, 57 ... elongate hole in lower flange, 60 ... edge of showerhead, 62 ... slots in the edge of the showerhead (for engaging the lower flange of the external suspension), 64 ... pins in the edge of the showerhead (for engaging the lower flange of the external suspension), 66 ... (gas sealing) Groove in the upper surface of the showerhead edge (for engaging the inner skirt), 68 ... ridge, FIG. 2B, 70 ... gas-tight skirt (inner skirt), 72 ... upper flange of the skirt, 74 ... inner face of the skirt, 80 ... the opening in the suspension wall, 81 ... the material in the hinge-type opening, 82 ... the horizontal direction in the plane of the suspension wall (double arrow), 84 Vertical tear, 86 ... opening in crevices, 100 ... center support, the tubular gas conduit, 102 ... side gas flow channel, 104 ... lower gas passage 106 ... mounting ring, 108 ... jack screw.

Claims (7)

In the process chamber gas inlet manifold,
A chamber wall comprising a chamber top wall and a chamber sidewall, the chamber wall including one or more gas inlet channels;
A shower head having a plurality of gas outlet channels;
A flexible suspension connected between the chamber wall and the showerhead so as to hang the showerhead slightly below the upper wall;
A gas-tight skirt having an upper portion connected to the chamber wall and a lower portion in contact with the showerhead but not connected;
With
The chamber wall, the showerhead and the gas sealing skirt collectively enclose a space through which gas can flow from the gas inlet channel and through to the gas outlet channel;
The suspension is outside the space;
Gas inlet manifold.   The gas inlet manifold according to claim 1, wherein the gas sealing skirt is in contact with a peripheral portion of the showerhead. The showerhead includes at least one upwardly protruding ridge;
The gas inlet manifold of claim 1, wherein the gas sealing skirt abuts a radially outer surface of the at least one ridge. In the process chamber gas inlet manifold,
A chamber wall comprising a chamber top wall and a chamber side wall, the chamber wall comprising one or more gas inlet channels;
(I) upward and downward surfaces,
(Ii) a plurality of gas outlet channels extending between the upward surface and the downward surface;
(Iii) one or more grooves in the upward surface, wherein the groove is disposed between the gas outlet channel and a peripheral portion of the upward surface;
Including shower head,
A flexible suspension connected between the chamber wall and the showerhead so as to hang the showerhead slightly below the upper wall;
(I) an upper portion connected to the chamber wall;
(Ii) a lower portion extending into one or more of the grooves and not connected to the showerhead;
Including a gas-tight skirt, and
With
The chamber wall, the showerhead and the gas sealing skirt collectively enclose a space through which gas can flow from the gas inlet channel and through to the gas outlet channel;
The suspension is outside the space;
Gas inlet manifold. The gas inlet manifold according to any one of claims 1 to 4 , wherein the gas sealing skirt is flexible. The shower head is rectangular with four sides;
The gas sealing skirt comprises the four four that are adjacent respectively to each side of the sheet of the shower head, gas inlet manifold according to any one of claims 1 to 5. The gas inlet manifold according to any one of claims 1 to 6 , wherein the suspension and the showerhead are a single component.

Images