WO2011094060A2

WO2011094060A2 - Pump baffle design for integrated pump and sputter source

Info

Publication number: WO2011094060A2
Application number: PCT/US2011/020951
Authority: WO
Inventors: Philip Arnold Greene; Daniel Joseph Zehm
Original assignee: Applied Materials, Inc.
Priority date: 2010-01-29
Filing date: 2011-01-12
Publication date: 2011-08-04
Also published as: TW201137147A; WO2011094060A3

Abstract

A method and apparatus for preventing deposition of condensate on the pump in the deposition chamber is provided. In one embodiment, a process chamber lid is provided, wherein the process chamber lid supports at least one vacuum pump having a port fluidly connecting the vacuum pump to a hole formed through the process chamber lid. The process chamber lid comprises at least one target unit coupled with a bottom surface of the process chamber lid for sputtering material on a substrate, wherein the target unit comprises at least one sputter target. The process chamber lid also comprises a plate coupled with the bottom surface of the process chamber lid and disposed between the hole and the target unit such that there is a gap between the process chamber lid and the plate and there is no direct line of sight between the sputter target and the port.

Description

PUMP BAFFLE DESIGN FOR INTEGRATED PUMP AND SPUTTER SOURCE

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] Embodiments of the present invention generally relate to deposition chambers used for coating glass or substrates. More specifically, embodiments of the present invention relate to a pump baffle for preventing deposition of condensate into a vacuum pump connected to a lid of the deposition chamber.

Description of the Related Art

[0002] In the fabrication of semiconductor devices and glass displays, plasma chambers are commonly used to perform various fabrication processes, such as sputtering. Generally, a vacuum pump maintains a very low pressure within the chamber while a mixture of process gases continuously flows into the chamber and an electrical power source excites the gases into a plasma state. The constituents of the process gas mixture are chosen to effect the desired fabrication process.

[0003] In certain applications, such as architectural glass coating, turbomolecular pumps (TMPs) are sometimes installed onto the vacuum lids of physical vapor deposition (PVD) chambers, behind the sputter sources. This configuration helps reduce the overall length of the in-line coating system. In these chambers, the TMPs help maintain the low pressures necessary for the PVD process. However, deposition of condensate on the TMP rotors and ensuing increased maintenance issues, as well as pumping uniformity are major concerns. Therefore, there is a need for baffles that reduce deposition onto the TMPs and encourage uniform pumping, but which do not excessively restrict the pumping speed.

SUMMARY OF THE INVENTION

[0004] Embodiments described herein generally relate to an apparatus and method for preventing deposition of condensate into a vacuum pump. In one embodiment, a process chamber is provided. The process chamber may support at least one vacuum pump on a wall of the process chamber. The vacuum pump may have a port fluidly connecting the vacuum pump to a hole formed through the chamber wall. The process chamber further comprises at least one target unit coupled with the wall for sputtering material on a substrate, wherein the target unit comprises at least one sputter target. The process chamber further comprises a plate coupled with the wall and disposed between the port and the target unit such that there is a gap between the wall and the plate and there is no direct line of sight between the sputter target and the port.

[0005] In another embodiment, a process chamber lid is provided. The process chamber lid supports at least one vacuum pump having a port fluidly connecting the vacuum pump to a hole formed through the process chamber lid. The process chamber lid further comprises at least one target unit coupled with a bottom surface of the process chamber lid for sputtering material on a substrate, wherein the target unit comprises at least one sputter target. The process chamber lid also comprises a plate coupled with the bottom surface of the process chamber lid and disposed between the hole and the target unit such that there is a gap between the process chamber lid and the plate and there is no direct line of sight between the sputter target and the port.

[0006] In another embodiment, a process chamber is provided. The process chamber comprises a conveyor for supporting and transporting a substrate through the process chamber and a chamber body having chamber side walls and a chamber bottom. A chamber lid is also provided, wherein the chamber lid comprises at least one vacuum pump having a port fluidly connecting the at least one vacuum pump to a hole formed through the process chamber lid and at least one target unit coupled with a bottom surface of the chamber lid for sputtering material on the substrate. The target unit may comprise at least one sputter target. The chamber lid also includes a plate coupled with the bottom surface of the chamber lid and disposed between the hole and the target unit such that there is a gap between the chamber lid and the plate and there is no direct line of sight between the at least one sputter target and the port on the vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, 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 invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0008] Figure 1A is a front view of the chamber lid assembly and pump baffle of one embodiment of the invention with a conveyor underneath.

[0009] Figure 1 B is a longitudinal side view of the chamber lid assembly and pump baffle of one embodiment of the invention with a conveyor underneath.

[0010] Figure 2 is a perspective view of the chamber lid and pump baffle of one embodiment of the invention, viewed from underneath the pump baffle.

[0011] Figure 3 is a schematic view of a process chamber with the chamber lid and pump baffle of one embodiment of the invention placed thereon.

[0012] It is contemplated that elements disclosed in one embodiment may be beneficially utilized in other embodiments without specific recitation.

DETAILED DESCRIPTION

[0013] Embodiments described herein provide a pump baffle for preventing deposition on the pump in a deposition chamber. Although discussed in relation to an in-line glass coating deposition chamber system, embodiments of the pump baffle may be used in any system involving vacuum pumps installed on chamber lids. Although this discussion will refer to glass substrates, it should be understood that the apparatus or methods described in the embodiments below are not limited to use with glass substrates, but may be used with other kinds of substrates as well (such as a solar panel, a flat panel display substrate, a semiconductor wafer, or other workpiece). A processing chamber in which the pump baffle described herein may be used is a PVD process chamber such as the AXL-870, available from Applied Materials, Inc. located in Santa Clara, California.

[0014] Figure 1A is a schematic front view of a chamber lid assembly 100 having a cathode unit 107 and a pump baffle 101 in accordance with one embodiment described herein. A conveyor 102 for supporting a substrate 130 is disposed underneath the chamber lid assembly 100. The interior of chamber lid assembly 100 is visible through the front wall of chamber lid assembly 100 in Figure 1A. It should be noted that Figure 1A does not show the entire process chamber. Figure 3, however, shows a schematic and simplified view of a PVD process chamber 350 with a chamber lid and pump baffle of one embodiment of the invention placed thereon. As shown in Figure 3, process chamber 350 may comprise a gas system 333 for introducing process or carrier gases into the sputtering chamber. Process chamber 350 may also comprise slots and/or gates (not shown) for introducing glass substrates (not shown), and conveying wheels 31 1 to transport the substrates through the process chamber 350. Process chamber 350 may also comprise a shield, such as a water cooled shield 331 , for collecting sputter material that does not land on the substrate. The shield 331 may extend horizontally from the chamber walls into process chamber 350 and may include a lower component positioned proximate the conveyor and below a substrate being transported through the process chamber 350. The upper and lower portions of shield 331 may be connected to each other (not shown) so that it can be lifted separately from the conveyor or other chamber components typically attached to the chamber walls. The process chamber 350 may also include two cathode units 307 supported on chamber lid 300 by endblocks 308. Vacuum pump baffle 301 may be supported in a horizontal position by chamber lid 300 between the sputter targets of cathode units 307 and the ports of vacuum pump 306. Although vacuum pumps are normally mounted on the chamber lid adjacent to the sputtering source, in the current embodiment, one or more vacuum pumps 306 may be mounted on chamber lid 300, behind the sputtering source. Accordingly, covers 332 may be positioned over vacuum ports on the side walls of process chamber 350 to block the pumping path. Process chamber 350 may comprise additional components not shown in Figure 3.

[0015] Figure 1A shows an embodiment of a chamber lid assembly with a pump baffle in more detail. Figure 1A shows a conveyor 102 underneath chamber lid assembly 100. The conveyor 102 operates to transport a substrate 130 to be coated, such as a glass substrate, under magnetron or cathode units 107. The conveyor 102 may be adapted to transport substrates in and out of the process chamber. Accordingly, conveyor 102 may extend lengthwise (e.g., as shown in Figure 1 B, conveyor 102 can extend further to the right or left) further than the width of the chamber lid assembly 100.

[0016] As shown in Figure 1A, conveyor 102 may comprise a series of rollers (one roller is shown at 110; Figure 1 B shows three rollers) or long cylinders in parallel each having a plurality of o-ring tires or wheels (one o-ring tire is labeled 1 1 1 ) fixably disposed around each roller 1 10 to form a conveying surface to support a glass substrate 130. As shown in Figure 1 B, each roller 1 10 can be rotatably supported on a frame and mechanically coupled to at least one sprocket 1 13 or pulley. A driving belt 1 14 can be tensioned or stretched around the sprockets 1 13 or pulleys as well as around an additional motorized sprocket or pulley. Rotation of the motorized sprocket 1 13 or pulley moves the driving belt 1 14 which in turn causes the remaining sprockets or pulleys to rotate, thereby rotating the rollers 1 10. As the rollers 1 10 rotate, they may move the glass substrate along the conveyor 102 intermittently or continuously. It should be noted that conveyor 102 is not limited to the above embodiment, and could be any type of conveyor that effectively transports a substrate through a process chamber. For example, conveyor 102 may also use a belt, as opposed to wheels, as the conveying surface.

[0017] As shown in Figure 1A, chamber lid assembly 100 may be configured as a hollow box-like structure. Chamber lid assembly 100 may comprise a chamber lid 103 forming the bottom of the box-like structure and walls protruding vertically from the edges of the top surface of chamber lid 103 to form an enclosure, as shown in Figure 1A. Chamber lid assembly 100 may also comprise a cover on the top face of the box-like structure, or in other embodiments, the box-like structure may remain open. In yet another embodiment, chamber lid assembly 100 may be an open structure comprising chamber lid 103 with no walls forming an enclosure. Chamber lid assembly 100 may accommodate utility and water lines at one or both ends thereof. For example, Figure 1A shows a panel 120 for utility connections at the left end of chamber lid 103. Furthermore, a drive 121 for rotating the cathode units 107 may also be connected on the ends of chamber lid 103. The drive may be arranged at least partially outside the coating chamber. The drive shaft may extend through a rotary vacuum feedthrough provided in the chamber lid assembly 100.

[0018] The glass substrate may be coated using a sputter coating process. This process may be static or dynamic. In a static process, the substrate is positioned within the deposition chamber. In a dynamic process, the substrate is transported continuously past a plurality of sputter targets during the coating process. During the sputter coating process, a controlled vacuum may be maintained in an evacuable deposition chamber to cause particles of the target material to be dislodged and deposited as a thin film on the glass substrate being coated. As mentioned above, the target units may be magnetron or cathode units and generally comprise one or more elongated, cylindrical tubes mounted horizontally in the deposition chamber.

[0019] Figure 1 B is a longitudinal side view of a chamber lid and pump baffle of one embodiment of the invention as shown in Figure 1A with the conveyor underneath. Figure 1 B shows two cathode units 107. However, it should be noted that the PVD system may comprise one, three, four or even more cathodes. Cathode units 107 are coupled to the bottom of chamber lid 103 using endblocks 108 which support cathode units 107 in a horizontal position in the deposition chamber and connect cathode units 107 to the chamber lid. Endblocks 108 may carry electrical and cooling water lines from chamber lid assembly 100 to the cathode units 107. The elevation of the cathode units 107 above the conveyor 102 in the process chamber will depend on the coating process, and may be adjusted accordingly. [0020] In the embodiment shown in Figure 1 B, the cathode units 107 are coupled with the chamber lid 03 using endblocks 108 at the ends of each cathode unit 107. As discussed above, there may be one, two or more rotary cathodes. In other embodiments, the cathode units may be planar. As shown in Figure 1A, the chamber lid assembly 100 may house and support three vacuum pumps 106 on an upper surface of the chamber lid 103. Vacuum pumps 106 are provided to evacuate the interior space of the deposition chamber. Vacuum pumps 106 may be turbomolecular pumps (TMPs) in certain applications that require high vacuum pumping systems. A TMP relies on a rotating member that rotates near the velocity of the gas molecules to be pumped. TMPs can evacuate the deposition chamber to a very low pressure, such as about 3 mTorr, during the coating process for a glass substrate. Vacuum pumps 106 may be evenly and centrally spaced along the length of chamber lid 103. Although the embodiment shown in Figure 1A includes three vacuum pumps 106, chamber lid 103 may support one, or two, or more vacuum pumps 106. Vacuum pumps 106 are located within chamber lid assembly 100 such that the vacuum pump ports face downward towards the cathode units 107. Each vacuum pump port may fluidly connect each vacuum pump 106 to a hole formed through the process chamber lid 103. Placing the vacuum pumps 106 behind the cathode units 107, as opposed to behind the chamber sidewalls and adjacent to cathode units 107, helps reduce the overall length of the in-line chamber because it facilitates an in-line arrangement of a large number of target units within a short distance along the transport path of the glass substrate. Pump baffle 101 may be disposed between the ports of vacuum pumps 106 and cathode units 107. As discussed in more detail below, pump baffle 101 may be a long rectangular plate that covers a sufficient area underneath chamber lid 103 such that there is no direct line of sight from any portion of the targets (cathode units 107) into the ports of vacuum pumps 106.

[0021] As shown more clearly in Figure 1 B, each cathode unit 107 comprises a rotatable cathode 104. Cathode 104 may be formed of a suitable non-magnetic material such as, for example, brass or stainless steel. As further shown in Figure 1 B, each cathode 104 has a cylindrical target 105, which may be a layer of a selected coating or target material to be deposited onto the glass substrate being coated. In one embodiment, different target materials can be applied to different portions of cylindrical target 105 so that by turning cathode 104, a particular selected coating material can be brought into sputtering position. Cathodes 104 may be arranged in line with a short distance between the cylindrical targets 105. During the coating process, each of cylindrical targets 105 may be rotated around a longitudinal central axis, either in a step-by-step fashion or continuously, while magnets systems, if present, within the targets are stationary. The endblocks 108 may also comprise a rotating mechanism for transferring a rotation of a shaft or spindle to move a magnet assembly to scan the target surface on a substantially linear (reciprocating) path, wherein the magnet assembly is accommodated in the interior space of the target unit. The rotation may be accomplished using a drive loader 121 coupled to cathodes 104. These rotatable cathode units may prevent re-deposition of particles on the surface of the target and may be arranged in the deposition chamber in line. In a particular embodiment of the invention, endblocks 108 may comprise a tilting mechanism to provide a tilt of the target unit and the target.

[0022] Cathode units 107 may be cooled using a coolant conduit (not shown), which may also be made of a suitable material extending longitudinally in the lower portion of cathode tube 104. A suitable coolant, such as water, may be circulated through the coolant conduit.

[0023] Although Figures 1A-1 B show rotating cylindrical sputtering sources, the present invention is not limited to that type of target. It should be noted that other embodiments may include a planar target instead. In an alternative embodiment (not shown), planar magnetrons may be arranged in line and may be equipped with a stationary or moveable magnet system for generating, e.g., a racetrack, above the sputter surface of the target. The magnets in the magnet system may be driven by a drive system. A cooling system may be disposed behind each planar target in order to ensure cooling of the target.

[0024] Vacuum pumps 106 may be placed in close proximity to where the sputter sources, such as cathode units 107, are located. In some instances, the proximity of vacuum pumps 106 to cathode units 107 may lead to undesirable deposition of condensate at and near the pump rotors. The general direction of sputtering from the sputter sources (cathode units 107) is downward towards the glass substrate. However, scattering within the chamber causes some amount of the sputtered target material to go back up towards the chamber lid 103 and towards inlet ports of vacuum pumps 106. If the inlet ports are open, vacuum pumps 106 will receive too much deposited material going up nearby and into the inlet ports 1 15. This scattering of material towards vacuum pumps 106 results in increased servicing, process and maintenance issues. Therefore, as shown in Figures 1A and 1 B, pump baffle 101 is placed underneath vacuum pumps 106 and over the sputter source, such as cathode units 107, in order to hinder scattering of material towards and into vacuum pumps 106.

[0025] Pump baffle 101 may be a solid plate manufactured from a planar sheet of metal, such as copper, or other suitable material. Pump baffle 101 may comprise one solid plate, or multiple overlapping or adjacent plates coupled to one another using a coupling device, such as rivets. Pump baffle 101 may be attached to or coupled with the bottom face of the chamber lid 103 using, for example, small posts which may be welded to the plate. The posts may be small enough such as not to block gas flow or access. The posts may include a threaded rod with a nut or a bolt on the end in order to allow for removal of the pump baffle 101 for maintenance, replacement, cleaning, etc. The plate or plates which form pump baffle 101 may be of sufficient thickness so as to be rigid enough to hold form and withstand the operating temperatures within the chamber. Furthermore, the one or more plates may be covered by a deposition mesh for holding condensate onto pump baffle 101. The dimensions and placement of pump baffle 101 should be such that there is no direct line of sight (as shown in one dimension by dashed line L in Figure 1A) between any of the vacuum pump ports (shown as 215 in Figure 2) and the cylindrical targets of cathode units 107. This prevents exposure of the vacuum pump ports to sputtered material. Accordingly, pump baffle 101 may extend along the entire length of the sputtering cathode electrode close to endblocks 108 on either end of the cathodes. As shown in Figure 1 B, pump baffle 101 should also be positioned under chamber lid 103 such that there is a gap g between the pump baffle 101 and the bottom surface of chamber lid 103. Maintaining a gap g between the chamber lid and the pump baffle serves as a vacuum space to help minimize pumping non-uniformities.

[0026] In order to more clearly show the placement of the pump baffle relative to the pump inlet ports, Figure 2 shows one embodiment of the chamber lid in the embodiments shown in Figures A and 1 B as viewed from underneath the chamber lid. Because pump baffle 201 does not extend the entire area of the chamber lid, the bottom face of chamber lid 203 overlaps pump baffle 201 and is visible from behind all edges of pump baffle 201 in the perspective shown in Figure 2. The dashed circles represent the outlines of vacuum pump inlet ports 215 located behind pump baffle 201 and show the placement of pump baffle 201 relative to vacuum pump inlet ports 215. It should be noted that although Figure 2 shows outlines for three vacuum pumps, this embodiment is not limited to three pumps, and can be used in arrangements having one, two, four or more pumps. Pump baffle 201 may cover all three vacuum pump inlet ports 215 and may extend horizontally and longitudinally beyond the vacuum pump inlet ports 215 so as to create an overhang on all sides. As shown in Figure 2, pump baffle 201 may overhang vacuum pump inlet ports 215 by a distance d past the edges of the vacuum pump inlet ports 215 in order to prevent scattering of sputtered material into vacuum pump inlet ports 215.

[0027] It has been shown that a gap g of about one mean free path (mfp) and an overhang having a distance d between 2-3 mfp provides adequate chances for scattering and subsequent removal of sputtered atoms from the gas phase before they enter the vacuum pumps. Using this overhang dimension, a gas atom would have to bounce over the pump baffle and travel 2-3 mfp from the baffle plate before it reaches the pump. At a common sputtering pressure used in glass substrate sputtering of about 3 mTorr, 50 mm is approximately equivalent to one mean free path (mfp) for the gas atoms. Therefore, the gap g (as shown in Figure 1 B) between pump baffle 101 and the bottom surface of chamber lid 103 may be about 50 mm.

Furthermore, pump baffle 201 may have an overhang distance d (as shown in

Figure 2) of about 120 mm (slightly greater than twice the mfp) from the outer edge of the portion of pump baffle 201 just underneath the circumference of vacuum pump ports 215, shown by the dashed lines in Figure 2. Increasing the overhang distance d to more than three times the mfp increases protection to the vacuum pumps from deposition, but may reduce the pumping speed too much.

[0028] In some embodiments, pump baffle 101 may be planar in shape with raised edges along some or all of the edges. For example, one, two, three or all four edges may be raised, in the case of a quadrilateral plate. In another embodiment, all four edges of the plate may be raised perpendicular to the horizontal plane of the plate (forming a box-like shape having an open top face). In such embodiments, the raised edges can help form a vacuum space underneath the pumps and can be used to control pumping so that it is uniform along the length of the pump baffle. For example, in cases where there is only one vacuum pump on the chamber lid, there will be more efficient pumping near the middle of the pump baffle than at the ends. Therefore, pumping may be controlled at certain areas along the pump baffle by raising edges of the baffle plate at certain desired locations, or creating apertures along raised vertical sides of the pump baffle in embodiments where it resembles a box-like structure. Therefore, these configurations may facilitate more uniform pumping. In another embodiment, the edges of the plate may be raised at an obtuse angle from the horizontal plane of the plate (forming an open cup-like shape having an open top face). In another embodiment, the edges of the plate may be raised perpendicular to the plane of the chamber lid and the top portions of the raised edges may then flare out at an obtuse angle from the horizontal plane of the plate. In yet another embodiment, the pump baffle 101 may be a curved plate with the concave side facing the lid. Other embodiments may be devised for different configurations of pump baffle 101 to prevent deposition of sputter material on the pump ports.

[0029] As explained above, ideally pump baffle 101 covers a sufficient area underneath the chamber lid 103 such that there is no direct line of sight from the end of the target into a pump port, as shown by dashed line L in Figure 1A. Therefore, the degree of overhang between the pump baffle and the vacuum pump ports will at least depend on the number of vacuum pumps behind the sputtering cathodes and the dimensions of the sputtering cathodes. The number of vacuum pumps will depend on the application, how much pumping will be needed, and the size of the pump (determined by, e.g., diameter and pumping speed). The overhang between the pump baffle and the vacuum pump ports should provide sufficient hindrance to prevent sputtered material from lodging in the pump ports. For example, in an embodiment having just one vacuum pump and a long cathode, the longitudinal overhang may need to be greater than the horizontal overhang in order to avoid having a direct line of sight from the sputtering cathode to any portion of the vacuum pump inlet port. Additionally, the process chamber operating pressure will determine the mean free path of the gas atoms. Therefore, a large increase in operating pressure would change the mean free path and therefore require different pump baffle dimensions to achieve a similar hindrance effect. However, at the low pressures typically used during operation of glass deposition chambers, variance in the mean free path should be minimal.

[0030] It should be noted that in an alternate embodiment of the invention, the deposition system may have cathode units mounted in a vertical position such that target material is sputtered sideways, as opposed to downward, onto substrates being conveyed through the chamber with a carrier system. Utility connections can be made at the sidewalls of the chamber. In this embodiment, one or more pump baffles may be disposed in relation to the targets and pump ports as described above, but in a vertical configuration.

[0031] Thus, a pump baffle for preventing deposition of condensate on vacuum pumps in the deposition chamber is provided. The overhang on the pump baffle and the vertical distance between the pump baffle and the chamber lid where the vacuum pump inlet ports are located are sized to encourage scattering and subsequent removal of sputtered atoms from the gas phase before they enter the vacuum pump ports. Furthermore, the dimensions and placement of the pump baffle should be such that there is no direct line of sight between any of the vacuum pump ports and the sputter targets. [0032] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention 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 process chamber supporting at least one vacuum pump on a wall of the process chamber, wherein the at least one vacuum pump has a port fluidly connecting the at least one vacuum pump to a hole formed through the wall, the process chamber comprising:

at least one target unit coupled with the wall for sputtering material on a substrate, wherein the at least one target unit comprises at least one sputter target; and

a plate coupled with the wall and disposed between the port and the at least one target unit such that there is a gap between the wall and the plate and there is no direct line of sight between the at least one sputter target and the port.

2. The process chamber lid of claim 1 , wherein the at least one vacuum pump is a turbomolecular pump.

3. The process chamber lid of claim 1 , wherein the plate is a distance of about one mean free path from the wall.

4. The process chamber lid of claim 1 , wherein the plate extends a distance of between two to three mean free paths beyond the edge of the port.

5. A process chamber lid supporting at least one vacuum pump having a port fluidly connecting the vacuum pump to a hole formed through the process chamber lid, comprising:

at least one target unit coupled with a bottom surface of the process chamber lid for sputtering material on a substrate, wherein the at least one target unit comprises at least one sputter target; and

a plate coupled with the bottom surface of the process chamber lid and disposed between the port and the at least one target unit such that there is a gap between the process chamber lid and the plate and there is no direct line of sight between the at least one sputter target and the port.

6. The process chamber lid of claim 5, wherein the at least one vacuum pump is a turbomolecular pump.

7. The process chamber lid of claim 5, wherein the plate is a distance of about one mean free path from the bottom surface of the process chamber lid.

8. The process chamber lid of claim 5, wherein the plate extends a distance of between two to three mean free paths beyond the edge of the port.

9. The process chamber lid of claim 5, wherein the at least one sputter target is cylindrical.

10. The process chamber lid of claim 5, wherein the at least one sputter target is planar.

1 1. A process chamber comprising:

a conveyor for supporting and transporting a substrate through the process chamber;

a chamber body having chamber side walls and a chamber bottom;

a chamber lid, wherein the chamber lid comprises:

at least one vacuum pump having a port fluidly connecting the at least one vacuum pump to a hole formed through the process chamber lid;

at least one target unit coupled with a bottom surface of the chamber lid for sputtering material on the substrate, wherein the at least one target unit comprises at least one sputter target; and

a plate coupled with the bottom surface of the chamber lid and disposed between the hole and the at least one target unit such that there is a gap between the chamber lid and the plate and there is no direct line of sight between the at least one sputter target and the port on the at least one vacuum pump.

12. The process chamber of claim 1 1 , wherein the at least one vacuum pump is a turbomolecular pump.

13. The process chamber of claim 1 1 , wherein the plate is a distance of about one mean free path from the bottom surface of the lid.

14. The process chamber of claim 1 1 , wherein the plate extends a distance of between two to three mean free paths beyond the edge of the port.