WO2014163776A1

WO2014163776A1 - Loadlock conveyor wafer holder design

Info

Publication number: WO2014163776A1
Application number: PCT/US2014/016247
Authority: WO
Inventors: James L'heureux; Alexander S. Polyak; Yongsheng Liu; Christopher T. Lane; Hari K. Ponnekanti; Shengde Zhong
Original assignee: Applied Materials, Inc.
Priority date: 2013-03-13
Filing date: 2014-02-13
Publication date: 2014-10-09

Abstract

Embodiments described herein generally relate to a dynamic load lock chamber that is adapted to transfer one or more substrates from a first region that is at first pressure to a second region that is at a second pressure. More specifically, embodiments relate to apparatuses for restraining substrates on a transport belt. In certain embodiments, wafer retention apparatuses are disposed on a flexible transport belt to maintain a position of a substrate on the transport belt while the substrate is transferred through the dynamic load lock chamber.

Description

LOADLOCK CONVEYOR WAFER HOLDER DESIGN

BACKGROUND Field

[0001] Embodiments described herein generally relate to a dynamic load lock chamber that is adapted to transfer one or more substrates from a first region that is at first pressure to a second region that is at a second pressure. More specifically, embodiments relate to apparatuses for restraining substrates on a transport belt.

Description of the Related Art

[0002] Photovoltaic (PV) or solar cells are devices which convert sunlight into direct current (DC) electrical power. A typical PV cell includes a p-type silicon substrate with a thin layer of an n-type silicon material disposed on top of the p-type substrate. When exposed to sunlight (consisting of energy from photons), the p-n junction of the PV cell generates pairs of free electrons and holes. An electric field formed across a depletion region of the p-n junction separates the free electrons and holes, creating a voltage. A circuit from n- side to p-side allows the flow of electrons when the PV cell is connected to an electrical load. Electrical power is the product of the voltage times the current generated as the electrons and holes move through the external electrical load and eventually recombine. Each solar cell generates a specific amount of electrical power. A plurality of solar cells is tiled into modules sized to deliver the desired amount of system power.

[0003] The PV market has experienced growth with annual growth rates exceeding above 30% for the last ten years. Some articles have suggested that solar cell power production worldwide may exceed 10 GWp in the near future. It has been estimated that more than 90% of all photovoltaic modules are silicon wafer based. The high market growth rate in combination with the need to substantially reduce solar electricity costs has resulted in a number of serious challenges for silicon wafer production development for photovoltaics. [0004] In order to meet these challenges, the following solar cell processing requirements generally need to be met: 1 ) the cost of ownership (CoO) for substrate fabrication equipment needs to be improved {e.g., high system throughput, high machine up-time, inexpensive machines, inexpensive consumable costs), 2) the area processed per process cycle needs to be increased (e.g., reduce processing per Wp) and 3) the quality of the formed layers and film stack formation processes needs to be well controlled and sufficient to produce highly efficient solar cells. Therefore, there is a need to cost effectively form and manufacture silicon sheets for solar cell applications.

[0005] Further, as the demand for solar cell devices continues to grow, there is a trend to reduce cost by increasing the substrate throughput and improving the quality of the deposition processes performed on the substrate. One challenge in this regard involves introduction of these fragile substrates from an atmospheric pressure environment into a low pressure processing environment. Traditionally, this involves moving a batch of substrates through a first slit valve opening, from an environment at atmospheric pressure into a load lock chamber, which is coupled to, but sealed from a low pressure processing environment using a second slit valve. The load lock chamber is then sealed from the atmospheric pressure environment using the first slit valve. The pressure is then slowly reduced within the chamber to at or near that in the processing chamber to prevent the movement of the low mass and fragile solar cell substrates. The solar cell substrates are then moved into the processing chamber through the second slit valve opening in the load lock chamber. The second slit valve is then closed and the load lock chamber is vented so that it can then receive the next batch of substrates.

[0006] However, this traditional load lock transfer process is time intensive and limits the processing capabilities of the entire production line, and thus, increasing the cost for producing the solar cell devices. To reduce this cost while also reducing surface contamination, there is a need for a design of a novel load lock chamber and process that enables high throughput, improved device yield, reduced number of substrate handling steps, and a compact system footprint. Additionally, there is a need in the novel load lock chamber for apparatuses that maintain a position of a substrate during transport between atmospheric and low pressure regions.

SUMMARY

[0007] In one embodiment, an apparatus for transporting a substrate is provided. The apparatus comprises a transport belt having a first surface. The transport belt is configured to be translated relative to a support surface of a support. A substrate retainer having one or more engaging portions that are adapted to retain a substrate disposed over the first surface of the transport belt is also provided. The substrate retainer is rotatably coupled to the transport belt and is coupled to a plurality of activation members. The substrate retainer is adapted to rotate relative to the transport belt as one of the activation members interacts with an actuator this coupled to the support surface of the support.

[0008] In another embodiment, an apparatus for transporting a substrate is provided. The apparatus comprises a transport belt having a first surface. The transport belt is configured to translate relative to a support surface of a support. A motion limiter has one or more first arms and one or more second arms and the motion limiter is rotatably coupled to the transport belt. A trigger is positioned to engage with the one or more first arms or the one or more second arms of the motion limiter as the transport belt is translated relative to the support surface. The engagement of the first arm with the trigger causes the motion limiter to rotate so that the second arm is disposed over a surface of the substrate.

[0009] In yet another embodiment, an apparatus for transporting a substrate is provided. A transport belt has an electrostatic chuck disposed thereon. The electrostatic chuck comprises a plurality of electrodes coupled to a region of the transport belt, and a dielectric material disposed over the plurality of electrodes. A plurality of brushes coupled to the transport belt are adapted to electrically couple the electrodes with a plurality of electrified rails. A chucking power source is adapted to electrically bias the electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] 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.

[0011] Figure 1 is a schematic plan view of a substrate processing system according to one embodiment described herein.

[0012] Figure 2 is a schematic plan view of a dynamic load lock chamber according to one embodiment described herein.

[0013] Figure 3 is a schematic, cross-sectional view of the dynamic load lock chamber shown in Figure 2 taken along section line 3-3 according to one embodiment described herein.

[0014] Figure 4 is a partial plan view of a separation mechanism attached to a transport belt according to one embodiment described herein.

[0015] Figure 5 is a cross-sectional view of the separation mechanism in Figure 4 taken along lines 5-5 according to one embodiment described herein.

[0016] Figure 6 is a cross-sectional view of the separation mechanism in Figure 4 taken along line 6-6 according to one embodiment of the present invention.

[0017] Figure 7 is a schematic end view of the separation mechanism in Figure 4 according to one embodiment described herein. [0018] Figure 8A is a plan view of substrates positioned on transport belts with substrate retainers in an unengaged position according to one embodiment described herein.

[0019] Figure 8B is a perspective view of the substrate retainer and the transport belt according to one embodiment described herein.

[0020] Figure 8C is a bottom view of the transport belt having a substrate retainer housing disposed therein and a support plate according to one embodiment described herein.

[0021] Figure 8D is a cross-sectional view of an engaged substrate retainer according to one embodiment described herein.

[0022] Figure 8E is a cross-sectional view of an unengaged substrate retainer according to one embodiment described herein.

[0023] Figure 9A is a partial schematic cross-sectional view of the dynamic load lock chamber and motion limiter trigger according to one embodiment described herein.

[0024] Figures 9B-C are plan views of motion limiters and substrates disposed on a transport belt according to one embodiment described herein.

[0025] Figure 10A is a plan view of an electrostatic chuck integrated with a transport belt according to one embodiment described herein.

[0026] Figure 10B is a perspective view of the electrostatic chuck and associated architecture according to one embodiment described herein.

[0027] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

[0028] Embodiments described herein generally include a dynamic load lock chamber that may be disposed within a production line, for example, a solar cell production line, for processing a film stack used to form regions of a solar cell device. The dynamic load lock chamber includes a plurality of actuators positioned along its length to achieve a desired pressure gradient from an atmospheric pressure side of the dynamic load lock chamber to a processing pressure side of the dynamic load lock chamber. The dynamic load lock chamber further includes a flexible transport belt continuously running through the dynamic load lock chamber to transport substrates from the atmospheric pressure side of the dynamic load lock chamber to the processing pressure side of the dynamic load lock chamber, if situated on an inlet side of the production line, and from the processing pressure side of the dynamic load lock chamber to the atmospheric pressure side of the dynamic load lock chamber, if positioned on the outlet side of the production line. Separation mechanisms may be attached to the belt in order to separate discrete regions within the dynamic load lock chamber into a plurality of discrete volumes.

[0029] Substrates, such as solar cell substrates, may be disposed singularly or in an array between the separation mechanisms, such that separation between adjacent pressure regions within the dynamic load lock chamber is maintained as the substrates are transported through the dynamic load lock chamber. It has been found that gas turbulence in the discrete volumes, due to the movement of the substrates between regions of differing pressure (e.g., 1 atmosphere of pressure), there is a need to prevent the fragile solar cell substrates from fluttering, moving around and/or breaking while they are being transported from one end of the load lock to other. To resolve these issues, in certain embodiments, wafer retention apparatuses are disposed on the flexible transport belt to maintain a position of the substrates on the transport belt while the substrates are transferred through the dynamic load lock chamber.

[0030] Figure 1 is a schematic plan view of a substrate processing system 100. The processing system 100, for example, may be used for performing one or more solar cell fabrication processes on a linear array of substrates. The processing system 100 includes an input system 1 10, a first dynamic load lock chamber 120, one or more processing chambers 130, a second dynamic load lock chamber 140, and an output system 150. As illustrated, the substrate processing system 100 is configured for transferring a linear array of substrates during processing in a direction "M" from the input system 1 10 to the output system 150.

[0031] The input system 1 10 may include one or more automation devices, such as a conveyor system 107 that is configured to receive substrates from a substrate transport interface 105 and position them on a portion of the conveyor system 107 for transfer through the various chambers of the processing system 100. The substrate transport interface 105 may receive substrates from an upstream location {e.g., an upstream processing module in a solar cell fabrication line).

[0032] In operation, the conveyor system 107 may be loaded with unprocessed substrates via the substrate transport interface 105 in a clean environment at atmospheric pressure. The conveyor system 107 may then transfer the substrates into the first dynamic load lock chamber 120. As subsequently described, the first dynamic load lock chamber 120 provides staged pressure reduction as the substrates are passed from the input system 1 10, at atmospheric pressure, to an automation device 125 (Figure 2) coupled to the one or more processing chambers 130, which is maintained in an environment that is at a moderate vacuum pressure {e.g., 10^"2-10^"5 mbar).

[0033] After reaching the one or more processing chambers 130, the substrates are processed in a sequential fashion as they are transferred therethrough. In one embodiment, the one or more processing chambers include a series of sequential processing chambers. The processing chambers may include one or more of plasma enhanced chemical vapor deposition (PECVD) chambers, low pressure chemical vapor deposition (LPCVD) chambers, atomic layer deposition (ALD) chambers, physical vapor deposition (PVD) chambers, thermal processing chambers {e.g., rapid thermal processing (RTA) chambers), or other similar processing chambers. In addition, the one or more processing chambers 130 may also include one or more substrate buffer chambers, substrate transfer chambers, or substrate reorientation chambers.

[0034] After passing through the one or more processing chambers 130 by the use of one or more automation devices 125 {e.g., one or more conveyors), the linear array of substrates may be serially transferred into the second dynamic load lock chamber 140, which provides staged pressure increase as the substrates are passed from the one or more automation devices 125 in the one or more processing chambers 130, which is disposed in a region maintained at a moderate vacuum pressure {e.g., 10^"2-10^"5 mbar), to the output system 150, which is maintained at atmospheric pressure.

[0035] The output system 150 may include one or more automation devices, such as a conveyor system 157 that is configured to deliver substrates to a substrate transport interface 155. The substrate transport interface 155 may deliver substrates to a downstream location {e.g., a downstream processing module in a solar cell fabrication line).

[0036] Figure 2 is a schematic plan view of a dynamic load lock chamber 200. Figure 3 is a schematic, cross-sectional view of the dynamic load lock chamber 200 shown in Figure 2 taken along section line 3-3. The dynamic load lock chamber 200 may correspond to the first dynamic load lock chamber 120, when configured to transport the substrates 101 in the forward direction "F" {e.g., from atmospheric pressure to vacuum), and it may correspond to the second dynamic load lock chamber 140, when configured to transport the substrates 101 in a reverse direction "R" {e.g., from vacuum to atmospheric pressure), as shown in Figures 2 and 3.

[0037] Regardless of the direction in which the substrates 101 are transferred, a function of the dynamic load lock chamber 200 is to continuously transport the substrates 101 to or from the one or more processing chambers 130, while eliminating the flow of gases from an atmospheric pressure side of the dynamic load lock chamber 200 to the vacuum conditions inside the one or more processing chambers 130. To accomplish this desired function, the internal volume of the dynamic load lock chamber 200 is configured into a plurality of discrete volumes that are moveable along a linear path between the atmospheric side of the dynamic load lock chamber 200 and the vacuum conditions inside the one or more processing chambers 130 as the substrates, disposed within these discrete volumes, are transported therebetween.

[0038] As subsequently described below, the pressure in the discrete volumes are separately reduced to staged levels as they are transferred along the substrate transfer path during the substrate transfer process. The division between the discrete volumes is provided by separation mechanisms disposed on a continuously moving, linear substrate transport belt, which transports substrates in either direction between the atmospheric side of the dynamic load lock chamber 200 and the one or more processing chambers 130, depending on whether it is the first or second dynamic load lock chamber. While the discussion below primarily discusses a dynamic load lock chamber 200 being used to transport substrates from atmospheric pressure to a vacuum pressure, this configuration is not intended to be limiting as to the scope of the invention described herein, since the dynamic load lock chamber 200 can also be adapted to transport substrates from a vacuum pressure to atmospheric as discussed above.

[0039] The dynamic load lock chamber 200 includes a top wall 202, a bottom wall 204, and side walls 206 enclosing a staged load lock region 208. The walls 202, 204, and 206 may be fabricated from typical material used for substrate processing chambers, such as stainless steel or aluminum. A linear conveying mechanism 210 extends through the staged load lock region 208 from an atmospheric pressure side 212 of the dynamic load lock chamber 200 to a processing pressure side 214 of the dynamic load lock chamber 200. The linear conveying mechanism 210 includes one or more rollers 216 positioned on the atmospheric pressure side 212 and one or more rollers 218 positioned on the processing pressure side of the dynamic load lock chamber 200. The one or more rollers 216, 218 support and drive a continuous transport belt 220 of material configured to support and transport the substrates 101 through the load lock chamber 200.

[0040] The rollers 216, 218 may be driven by a mechanical drive 294 (Figure 2), such as a motor/chain drive (not shown), and may be configured to transport the transport belt 220 at a linear speed of up to about 10 m/min. The mechanical drive 294 may be an electric motor {e.g., AC or DC servo motor) that is geared to provide a desired transport belt 220 velocity during processing. The transport belt 220 may be made of a stainless steel, aluminum, or polymeric material. The transport belt 220 may be a unitary piece of material or may comprise a plurality of components coupled together to form the transport belt 220. One or more support plates 222 may extend between the side walls 206 to support an interior surface of the transport belt 220. The interior surface of the transport belt 220 is generally supported by a support surface 222A (Figure 5) of the one or more support plates 222.

[0041] The upper wall 202 of the load lock chamber 200 includes a plurality of pockets 226, 227, 228, 229, and 230 formed therein that are fluidly coupled to a plurality of actuators 231 , 232, 233, 234, and 235, respectively. Each of the pockets 226-230 is further in fluid communication with a respective discrete region of the staged load lock region 208. For example, the pocket 226 is in fluid communication with a region 246. The pocket 227 is in fluid communication with a region 247. The pocket 228 is in fluid communication with a region 248. The pocket 229 is in fluid communication with a region 249, and the pocket 230 is in fluid communication with a region 250.

[0042] The bottom wall 204 includes a plurality of corresponding pockets 236, 237, 238, 239, and 240 formed therein and coupled to the plurality of actuators 231 , 232, 233, 234, and 235, respectively. Each of the pockets 236-240 is further in fluid combination with a respective discrete region of the staged load lock region 208. For example, the pocket 236 is in fluid communication with a region 256. The pocket 237 is in fluid communication with a region 257. The pocket 238 is in fluid communication with a region 258. The pocket 239 is in fluid communication with a region 259, and the pocket 240 is in fluid communication with a region 260.

[0043] In addition, the one or more support plates 222 may also include corresponding pockets 241 , 242, 243, 244, and 245 formed therein that are coupled to the plurality of actuators 231 , 232, 233, 234, and 235, respectively. Each of the pockets 241 -245 are fluidly coupled to respective discrete regions of the staged load lock region 208. For example, the pocket 241 is in fluid communication with respective regions 246 and 256. The pocket 242 is in fluid communication with respective regions 247 and 257. The pocket 243 is in fluid communication with respective regions 248 and 258. The pocket 244 is in fluid communication with respective regions 249 and 259, and the pocket

245 is in fluid communication with respective regions 250 and 260.

[0044] In one embodiment, the plurality of actuators 231 -235 includes a plurality of pumps set to progressively reduce the pressure in the dynamic load lock chamber 200 from the atmospheric pressure side 212 to the processing pressure side 214. In this embodiment, each of the pumps are configured to reduce a volume within the staged load lock region 208 corresponding to the pockets to which the pump is coupled. For example, the actuator 231 may be configured to reduce the pressure in respective regions

246 and 256 to a first pressure {e.g., 480-600 mbar), which is less than atmospheric pressure. The actuator 232 may be configured to reduce the pressure in respective regions 247 and 257 to a second pressure (e.g., 100- 300 mbar), which less that the first pressure. The actuator 233 may be configured to reduce the pressure in respective regions 248 and 258 to a third pressure {e.g., 10-100 mbar), which is less than the second pressure. The actuator 234 may be configured to reduce the pressure in respective regions 249 and 259 to a fourth pressure (10^"2-1 mbar), which is less than the third pressure, and the actuator 235 may be configured to reduce the pressure in respective regions 250 and 260 to a fifth pressure (10^~4-10^~2 mbar), which is less than the fourth pressure and which may be greater than the pressure within the one or more processing chambers 130 {e.g., 10^"5 mbar). [0045] In one configuration, the plurality of actuators 231 -235 are replaced by a single actuator that is fluidly coupled to each of the pockets 226-230 and 236-245, wherein the single actuator is separately connected and valved to control the pressure within and/or gas flow received from each of these pockets. In another embodiment, the actuator 231 may include a compressor configured to inject clean dry air (CDA) or alternatively an inert gas, such as argon or nitrogen, into the respective regions 246 and 256 at a first pressure slightly above atmospheric pressure {e.g., 15-100 mbar above atmospheric pressure). Such an overpressure condition within the regions 246 and 256 assures that contaminants from the atmospheric pressure side 212 are not introduced into the dynamic load lock chamber 200 and consequently the one or more processing chambers 130.

[0046] In this embodiment, the actuators 232-235 include a plurality of pumps set to progressively reduce the pressure from the respective regions 246 and 256 to the processing pressure side 214 of the dynamic load lock chamber 200. For example, the actuator 232 may be configured to reduce the pressure in respective regions 247 and 257 to a second pressure (e.g., 300-600 mbar), which is less that the first pressure. The actuator 233 may be configured to reduce the pressure in respective regions 248 and 258 to a third pressure {e.g., 50-200 mbar), which is less than the second pressure. The actuator 234 may be configured to reduce the pressure in respective regions 249 and 259 to a fourth pressure {e.g., 1 -50 mbar), which is less than the third pressure, and the actuator 235 may be configured to reduce the pressure in respective regions 250 and 260 to a fifth pressure {e.g., 10^"2-1 mbar), which is less than the fourth pressure and which may be greater than the pressure within the one or more processing chambers 130 {e.g., 10^"5 mbar).

[0047] Although the actuators 231 -235 are configured for increased pressure reduction from the atmospheric pressure side 212 to the processing pressure side 214 of the dynamic load lock chamber 200, a difficulty remains in maintaining some separation between adjacent regions within the staged load lock region 208 because each of the adjacent regions are in fluid communication with one another. In order to assure such separation between adjacent regions and provide a semi-enclosed region in which to expose individual or groups of substrates 101 to each pressure stage as it passes through the dynamic load lock chamber 200, a plurality of separation mechanisms 252 are attached to the transport belt 220. The separation mechanisms 252 may be spaced along the surface of the transport belt such that one or more substrates 101 {e.g., an array of two or more substrates 101 ) may be positioned between each separation mechanism 252.

[0048] In addition, the separation mechanisms 252 may be positioned so that a small gap "X" is provided between surfaces of each separation mechanism 252, which are coupled to a portion of the transport belt 220, and the top wall 202, side wall 206 and/or bottom wall 204 of the dynamic load lock chamber 200. The gap "X" may have height "H" between 0 and 3 mm, preferably between 0 and 0.2 mm, and a width "W" between 1 and 30 mm. In one configuration, the gap "X" defined between each separation mechanism 252 and the top wall 202, side wall 206 and/or bottom wall 204 of the dynamic load lock chamber 200 provides a controlled fixed gap through which the gas disposed in an adjacent higher pressure region (e.g., region 246) will pass as it leaks into an adjacent lower pressure region [e.g., region 247) as both are moved in a desired direction as the transport belt 220 is moved by the mechanical drive 294. The separation mechanisms 252 are used to form a known and repeatable space through which gas will flow as the separation mechanisms 252 and substrates are moved, for example, from the atmospheric pressure side 212 to the processing pressure side 214 of the first dynamic load lock chamber 120.

[0049] The pumping capacity of each of the actuators 231 -235 and the size of gap "X" formed between the walls 202, 204, 206 and the separation mechanisms 252 are selected so that a controlled flow of gas, or "gas leak", is created between the separation mechanisms 252 and the walls 202, 204, 206, during the substrate transferring process, so that the pressure over the substrates 101 is continually reduced as they are transferred from one end of the dynamic load lock chamber 200 to the other in the forward "F" direction (i.e., first dynamic load lock chamber 120), or vice versa in the reverse direction "R" (i.e., second dynamic load lock chamber 140). In one embodiment, at least a portion of one or more of the separation mechanisms 252 are configured to contact one or more of the walls 202, 204, 206 to minimize the gap through which gas can flow from the higher pressure region on one side of the separation mechanism to the other side of the separation mechanism.

[0050] Further, since a back side 221 of the substrate transport belt 220 may provide a "gas leak" path between adjacent regions of the dynamic load lock chamber 200, the pockets 241 -245 disposed within the one or more support plates 222 are configured to assure that the pressure conditions between the back side 221 of the transport belt 220 and the one or more support plates 222 is maintained at the same pressure as the remainder of the respective regions in which it is in fluid communication. For example, the pocket 241 is configured to assure that the back side 221 of the transport belt 220 within the region 246 is maintained at the same pressure as the region 246.

[0051] Figure 4 is a partial plan view of a separation mechanism 400 attached to a transport belt 220. Figure 5 is a cross-sectional view of the separation mechanism taken along lines 5-5. Figure 6 is a cross-sectional view of the separation mechanism 400 taken along line 6-6. Figure 7 is a schematic end view of the separation mechanism 400 from Figure 4.

[0052] As illustrated, the separation mechanism 400 is a linear member disposed across the width of the transport belt 220. The separation mechanism 400 includes a housing member 402 attached to the transport belt 220 using one or more suitable fasteners, such as screws, bolts, adhesives, or the like. The housing member 402 may be fabricated from a material typically used in substrate processing environments, such as stainless steel, aluminum, or a suitable polymeric material. A vane 410 is disposed within the housing member 402. The vane 410 may be manufactured from a suitable polymer material, such as a self lubricating polymer to provide low sliding resistance and possibility of contamination when the vane 410 is in contact with the top wall 202 or bottom wall 204. One example of a polymer material that may be used in the vane 410 is ORIGINAL MATERIAL "S"^® 8000 manufactured by Murtfeldt Kunststoffe GmbH & Co. KG of Dortmund, Germany. Alternatively, the vane 410 may be manufactured of other materials, such as a metallic material (e.g., stainless steel, aluminum) or graphite.

[0053] The vane 410 is spring-loaded within the housing member 402 using spring members 420. The spring members 420 may be mechanical springs. Alternatively, the spring members 420 may include magnetic, hydraulic, or pneumatic actuators. Optionally, the spring members 420 may include gravity activated actuation, such as a pivot or rocker which may be configured to an extended position under normal circumstances and pivot to a retracted position if contacted. The spring members 420 may be disposed within a slot 412 and contacting the housing member 402 such that an upper portion 414 of the vane 410 extends through an opening 404 in the housing member 402 and above an upper surface 406 of the housing member 402. As such, the vane 410 provides the gap "X" between the separation mechanism 400 and the top wall 202 and/or the bottom wall 204. The vane 410 may be in contact with the top wall 202 and/or bottom wall 204 as the substrates are transported through the dynamic load lock chamber 200 to minimize the gas leak between discrete regions of the chamber 200. In addition, since the vane 410 is spring loaded, less friction between the separation mechanism 400 and top wall 202 or bottom wall 204 is provided during contact. Consequently, the probability of contamination within the dynamic load lock chamber 200 is significantly reduced.

[0054] The separation mechanism 400 further includes an end member 430 disposed at each end of the separation mechanism 400. Each end member 430 is spring-loaded within the vane 410 using spring members 432. The spring members 432 may be disposed within a slot 434 and contacting the vane 410 such that an outer portion 436 of the end member 430 extends outside of the outer surface of the vane 410. As such, each end member 430 provides a small gap {e.g., same dimensions as the gap "X") between the separation mechanism 400 and the respective side wall 206. Preferably, each end member 430 is in contact with the respective side wall 206 as the substrates are transported through the dynamic load lock chamber 200 to minimize the gas leak between discrete regions of the chamber 200. In addition, since the end members 430 are spring loaded, less friction between the separation mechanism 400 and the side walls 206 is provided during contact.

[0055] Further, the spring members 432 may be manufactured from the same material as the vane 410, such as a self-lubricating polymer. Consequently, the probability of contamination within the dynamic load lock chamber 200 is significantly reduced. The end member 430 is generally configured so that a desirable gap (e.g., gap "X") is formed between its exterior surfaces and the surface 222A of the support plates 222 and the inner surfaces of side wall 206 and top wall 202. As described above, the gap "X" is sufficiently small to minimize "gas leak" between adjacent regions of the dynamic load lock chamber 200 as the substrates 101 are transported therethrough.

[0056] Figure 8A is a plan view of substrates 101 positioned on transport belts 220 with substrate retainers 802 in an unengaged position. As described above, substrates 101 travel through the dynamic load lock chamber 200 (See Figure 2) and pressure in the discrete volumes of the dynamic load lock chamber 200 may be separately reduced or increased to staged levels as the substrate 101 are transferred along the substrate transfer path during the substrate transfer process. The division between the discrete volumes is provided by separation mechanisms 252 disposed on the continuously moving, linear substrate transport belt 220, which transports the substrates 101 to or from the one or more processing chambers 130 (See Figure 1 ). While the substrates 101 travel through the discrete volumes having different pressures, the substrates 101 may experience "flutter." Substrate flutter may be defined as the undesirable movement of the substrate 101 on the transport belt 220 due to turbulence or pressure gradients formed within the discrete volumes as the substrates 101 are transported through the load lock 200, which may result in damage to the substrate 101 .

[0057] The substrate retainers 802 may be disposed on the transport belt 220 to engage the substrates 101 and prevent flutter. As shown in Figure 8A, the substrate retainers 802 are not engaged. The substrate retainers 802 may be in an unengaged position when the substrates 101 are entering or exiting the dynamic load lock 200, such as when the substrates are being transferred to and from the dynamic load lock chamber 200 from other transporting devices. However, the substrate retainers 802 may be engaged while the substrates 101 are transferred through the dynamic load lock chamber 200 where the ambient pressure along the length of the dynamic load lock is in flux.

[0058] Figure 8B is an isometric perspective view of the substrate retainer 802 and a portion of the transport belt 220, such as a single link in the transport belt 220. The transport belt 220 may be similar to the transport belt previously described. In certain embodiments, the transport belt 220 may have a first hole 805 disposed through a center region of the transport belt, which is adapted to receive the substrate retainer 802. The transport belt 220 may also have a plurality of second holes 806 disposed through regions adjacent the center region and adapted to receive a plurality of rotation retention members 812 and 814, which may include magnets that are attached to the transport belt 220. A bottom surface of the transport belt 220 may be formed to receive a substrate retainer housing 804 such that the substrate retainer housing 804 may be flush with the bottom surface of the transport belt 220. The substrate retainer housing 804 may be rotatably disposed within the transport belt 220. In another embodiment, the substrate retainer housing 804 may extend beyond the bottom surface of the transport belt 220.

[0059] In certain embodiments, the substrate retainer housing 804 comprises a plurality of recesses adapted to receive a portion of the substrate retainer 802 and a plurality of rotational activation members 808 and 810, such as magnets. The rotational activation members 808 and 810 may be contained within recesses of the substrate retainer housing 804 that are disposed adjacent to a central recess of the substrate retainer housing 804. In one embodiment, a bottom portion of the substrate retainer 802 is disposed through the first hole 805 and may be contained within and engaged with a recess in the center region of the substrate retainer housing 804.

[0060] The retainer housing 804 and the substrate retainer 802 are physically coupled together, so that the orientation of the retainer housing 804 relative to the substrate retainer 802 remains constant as they are rotated about an axis that is aligned to the central axis of the first hole 805. An upper portion of the substrate retainer 802 may remain above a top surface of the transport belt 220. The portion of the substrate retainer 802 disposed above the top surface of the transport belt may comprise a plurality of engaging portions 822, such as wings, which are adapted to extend beyond a top surface of a substrate 101 disposed on the transport belt 220.

[0061] Figure 8C is a bottom view of the transport belt 220 having the substrate retainer housing 804 disposed therein and a support plate 222. As shown, the transport belt 220 receives the substrate retainer housing 804 disposed in a recess in the bottom surface of the transport belt 220. The recess in the bottom surface of the transport belt 220 may be adapted to accommodate rotational movement of the substrate retainer housing 804. The substrate retainer housing 804, containing a bottom portion of the substrate retainer 802, and rotational activation members 808 and 810, is rotatably disposed in the recess of the bottom surface of the transport belt 220 about the central axis of the first hole 805 (not shown in Figure 8C). The rotation retention members 812 and 814 may be disposed in the transport belt 220 and may be adapted to maintain a position of the substrate retainer housing 804.

[0062] The support plate 222 is generally stationary within the dynamic load lock 200 and may be disposed below the moving transport belt 220. The transport belt 220 moves in a transport direction 818 over the support plate 222. An actuator 816 may be disposed in the support plate 222. In one embodiment, the actuator 816 may be flushly disposed within the support plate 222 in a fixed manner, such that the actuator 816 does not extend beyond a top surface of the support plate 222.

[0063] In one embodiment, the rotation retention members 812 and 814, the rotational activation members 808 and 810, and the actuator 816 may be magnets. In this embodiment, the polarity of the actuator 816 and the rotation retention members 812 and 814 are identical (e.g., both north or both south magnetic polarities) while the polarity of the rotational activation members 808 and 810 is opposite the polarity of the actuator 816 and the rotation retention members 812 and 814 (e.g., north versus south polarity). As the transport belt 220 moves along the transport direction 818, one of the rotational activation members 808 and 810 passes above the actuator 816.

[0064] Generally, the substrate retainer 802 will either be in an engaged or unengaged position. In the embodiment shown, the transport belt 220 continues over the actuator 816, the opposite polarities of the actuator 816 and the rotational activation member 808 are attracted to one another and the substrate retainer housing 804 rotates around a central axis along a rotational path 820 from a first position to a second position.

[0065] In the embodiment shown, the rotation retention member 812 holds the substrate retainer housing 804 in place as a result of the alignment of the opposite polarities of the rotation retention member 812 and the rotational activation member 808. While moving along the transport path 818, the actuator 816's magnetic force overcomes the magnetic force of the rotation retention member 812 which allows the substrate retainer housing 804 to move freely along the rotational path 820 as the transport belt moves along the transport path 818. The magnetic force of the actuator 816 may be greater than the magnetic force of the rotation retention members 812 and 814.

[0066] Therefore, as the transport belt 220 continues in the transport direction 818, the substrate retainer housing 804 rotates along the rotational path 820 to a second position where the rotation retention member 814 causes the substrate retainer housing 804 to maintain the second position as a result of the alignment of the opposite polarities of the rotation retention member 814 and the rotational activation member 808. In this embodiment, the opposite polarities of the rotation retention member 814 and the rotational activation member 808 prevent the substrate retainer housing 804 from rotating along the rotational path 820 in a reverse direction until the transport belt 220 passes over an actuator, which may be the actuator 816 or a different actuator disposed in a different location within the dynamic load lock 200, such as a second support plate 222 disposed at an opposing end of the dynamic load lock 200.

[0067] In certain embodiments, the substrate retainer 802 may be fixed in the substrate retainer housing 804. Rotational movement of the substrate retainer housing 804 translates to the rotational movement of substrate retainer 802 and cause the substrate retainer 802 to attain either an engaged or unengaged position. In one embodiment, the substrate retainer housing 804 is rotated about 90° due to the interaction of the rotational activation members 808 and 810 with one or more actuators 816.

[0068] Figure 8D is a side view of the transport belt 222 that illustrates a substrate retainer 802 in an engaged position over the substrate 101 . The substrate retainer 802 may have an engaging portion 822 and a non-engaging portion 824. In the embodiment shown, the substrate retainer 802 is in an engaged position, such that the engaging portion 222 is disposed over a portion of the substrate 101 . The engaged position prevents the substrate 101 from moving on the transport belt 220 as a result of flutter. The engaging portion 822 may be disposed above a top surface of the substrate 101 , so that it maintains a small gap (e.g., between 0 mm and 10 mm) between the top surface of the substrate 101 or it may engage with a portion of the top surface of the substrate 101 when it is in the engaged position. In certain embodiments, the small gap may be between about 0 mm and about 5mm, more specifically between about 0 mm and about 2 mm, such as between about 0 mm and about 1 mm. In one embodiment, the substrate retainer 802 remains engaged for during transport through the dynamic load lock chamber 220 (See Figure 2).

[0069] Figure 8E is a side view of an unengaged substrate retainer 802. In the embodiment shown, the substrate retainer 802 is in an unengaged position, such that the engaging portion 222 is not disposed over a portion of the substrate 101 . The unengaged position allows the substrate 101 to be placed on or transferred from the transport belt 220. The non-engaging portion 824 may be disposed such that substantially no portion of the substrate 101 is beneath the non-engaging portion 824. In one embodiment, the substrate retainer 802 remains unengaged during the transport of the substrate 101 to or from the dynamic load lock chamber 220 (See Figure 2; entrance exit of the dynamic load lock).

[0070] Figure 9A is a partial schematic cross-sectional view of the dynamic load lock chamber 200 and motion limiter trigger 902. The top wall 202, bottom wall 204, separation mechanism 252, support plate 222, transport belt 220, roller 218, and substrates 101 have been described above with reference to Figure 3 and will not be described here for the sake of brevity. Figures 9B- 9C are plan views of motion limiters 910 and substrates 101 disposed on the transport belt 220.

[0071] Referring back to Figure 9A, the trigger 902 may be disposed on a conveyor 904 which may be coupled to a power source. In one embodiment, the trigger 902 may comprise a wire or other apparatus capable of acting as a trigger mechanism for a motion limiter 910 (not shown in Figure 9A) attached to the transport belt 220. The trigger 902 may be sufficiently rigid to engage or disengage the motion limiter 910 as the trigger 902 contacts the motion limiter 910. The trigger 902 may physically contact the motion limiter 910, causing the motion limiter 910 to engage the substrate so that the motion limiter 910 attains a position that may prevent substrate 101 flutter during transport through the discrete volumes and disengage the motion limiter 910 for loading/unloading of the substrates 101 . The trigger 902 may be disposed on the conveyor 904 such that the trigger 902 extends toward the transport belt 200 to contact the motion limiters.

[0072] In certain embodiments, multiple triggers 902 are disposed on the conveyor 904 and spacing between the triggers 902 on the conveyor 904 may be adapted to avoid the separation mechanisms 252. Although not shown, in some embodiments, a controller may be communicatively coupled to the transport belt 220 and the conveyor 904 to coordinate the movement of the transport belt 220 and the conveyor 904 relative to one another. In one embodiment, the conveyor 904 may travel in a direction 906 opposite the travel direction of the transport belt 220. In this embodiment, the trigger 902 avoids contact with the separation mechanisms 252 in their respective directions of travel.

[0073] In another embodiment, the trigger 902 may be spring loaded. A spring may couple the trigger 902 to the conveyor 904. In this embodiment, the spring may be rigid enough to ensure engagement or disengagement of the motion limiter 910 with the trigger 902, but allow for lateral movement of the trigger 902 as the trigger 902 contacts the separation mechanisms 252. In this embodiment, the conveyor 904 may be stationary or may move in a predetermined manner that may or may not be coordinated with the movement of the transport belt 220. In another embodiment, the trigger 902 may be retractable. In this embodiment, the trigger may extend from a housing (not shown) to engage or disengage the motion limiter 910 and retract to avoid contact with the separation mechanism 252. In this embodiment, the extending and retracting may be coordinated by a controller (not shown) which coordinates movement of the trigger 902 and the transport belt 220. [0074] Figure 9B shows the motion limiters 910 in an engaged position. The sidewalls 206, support plate 222, and transport belt 220 are provided to show the general configuration contemplated. In one embodiment, the motion limiters 910 may be rotatably coupled to the transport belt 220 in a similar manner as described above. The motion limiters 910 may have one or more long arms 91 OA which extend over and above the substrate 101 to prevent substrate flutter. The long arms 91 OA may be perpendicular to the travel direction of the transport belt 220 when the motion limiter 910 is in an engaged position. In one embodiment, three motion limiters 910 may be disposed on the transport belt 220. In this embodiment, the motion limiters 910 nearest the sidewalls 206 engage the substrate 101 with one of the plurality of long arms 91 OA. The motion limiter 910 disposed between the substrates 101 engages two substrates 101 with its two long arms 91 OA.

[0075] The trigger path 912 is the path along which the relative motion of the trigger 902 (See Figure 9A) and transport belt 220 travel, so as to cause the engagement or disengagement of the motion limiters 910. As shown, the motion limiters 910 are engaged and the trigger path 912 contacts a long arm 91 OA of the motion limiter 910. As the transport belt 220 travels in a direction parallel with the trigger path 912, the trigger 902 may contact the motion limiter 910 which may cause the motion limiter 910 to rotate about a central axis. In one embodiment, the central axis may correspond to the region where the motion limiter 910 is coupled to the transport belt 220. In one embodiment, the trigger 902 may contact a long arm 91 OA of the motion limiter 910 and may cause the motion limiter 910 to rotate about 90° around the central axis.

[0076] Figure 9C shows the motion limiters 910 in a disengaged position. In one embodiment, the motion limiters 910 may have one or more short arms 910B which do not extend over the substrate 101 . If the short arms 910B of the motion limiter 910 are perpendicular to the edge of the substrate 101 (Figure 9C), the motion limiter 910 may be in a disengaged position for loading or unloading the substrate 101 from the transport belt 220. Moreover, the short arms 91 OB may be perpendicular to the travel direction of the transport belt 220 when the motion limiter 910 is in a disengaged position. The trigger path 912, as described with regard to Figure 9B, is the path along which the relative motion between the trigger 902 and the short arm 91 OB, so as to cause the engagement or disengagement of the motion limiter 910 with the substrate 101 .

[0077] In the embodiment shown, the trigger path 912 may be positioned to contact the short arms 910B of the motion limiter 910 and cause rotation of the motion limiter 910 as the transport belt 220 travels in a direction parallel to the trigger path 912. In one embodiment, the trigger 902 may contact a short arm 910B of the motion limiter 910 and may cause the motion limiter 910 to rotate about 90° around the central axis.

[0078] It is contemplated that the trigger 902 may either be movably disposed along the trigger path 912 or may maintain a stationary position within the trigger path 912. In the embodiments described above, the trigger 902 contacts either a long arm 91 OA or short arm 910B of the motion limiter 902 to cause its movement between an engaged or disengaged position. If the trigger 902 contacts the long arm 91 OA in an engaged position, the trigger 902 may cause the motion limiter 910 to disengage the substrate 101 . If the trigger 902 contacts the short arm 910B in a disengaged position, the trigger 902 may cause the motion limiter 910 to engage the substrate 101 .

[0079] Figure 10A is a plan view of an electrostatic chuck 1020 and transport belt 220. Electrostatic chucks are widely used to hold substrates, such as semiconductor wafers, during substrate processing in processing chambers used for various applications, such as physical vapor deposition, etching, or chemical vapor deposition. Electrostatic chucks typically include one or more electrodes embedded within a unitary chuck body which comprises a dielectric or semi-conductive ceramic material across which an electrostatic clamping force can be generated. However, most electrostatic chucks are stationary and not adapted to retain, or chuck, a substrate during a continuous linear transport motion between or through a chamber. Embodiments described herein utilize an electrostatic chuck to hold and retain a substrate during its linear motion through the dynamic load lock 200 using a transport belt 220 that is continually driven in one direction through the chamber.

[0080] The sidewalls 206 define the transport path of the transport belt 220 above the support plate 222. Electrified rails 1002 and 1004 may be coupled to the sidewalls 206. In one embodiment, the electrified rails 1002 and 1004 may be embedded in the sidewalls 206 such that the surface of the sidewall facing the transport belt 220 may be substantially planar. The electrified rails 1002 and 1004 may be further coupled to a chucking power source, such as a DC power supply. In one embodiment, the electrified rail 1002 may be coupled to a positive (+) chucking power source 1032. In this embodiment, the electrified rail 1004 may be coupled to a negative (-) chucking power source 1030.

[0081] The transport belt 220 may be slidably coupled to the electrified rails 1002 and 1004 by a plurality of brushes 1010. The brushes 1010 may be formed from an electrically conductive material, such as aluminum or stainless steel. The brushes 1010 conduct electricity from a power source (not shown) to a plurality of electrodes, such as electrodes 1006 and 1008. In certain embodiments, the brushes 1010 may be coupled to the transport belt 220 by a force exerting member, such as a spring or pneumatic or fluid piston adapted to exert force for maintaining electrical contact between the brushes 1010 and the electrified rails 1002 and 1004. In one embodiment, the brushes 1010 may be spring loaded such that the brushes 1010 maintain physical contact with the electrified rails 1002 and 1004 while the transport belt 220 moves along the sidewalls 206. In this embodiment, the brush 1010 may be similar to the end member 430 and may have a spring similar to the spring member 432 as shown in Figure 5.

[0082] The electrostatic chuck 1020 comprises a plurality of electrodes 1006 and 1008. The electrodes 1006 and 1008 may each be coupled to the brushes 1010 disposed on the transport belt 220. In one embodiment, power is coupled to the electrodes 1006 and 1008 via the electrified rails 1002 and 1004 and brushes 1010. In the embodiment shown, a first electrode 1006 (cathode) may be coupled to the negative (-) chucking power source 1030 and a second electrode 1008 (anode) may be coupled to the positive (+) chucking power source 1032. The electrodes 1006 and 1008 may be embedded in or disposed on an electrically insulative member, such as the transport belt 220. The transport belt 220 electrically isolates the electrodes 1006 and 1008 from each other. The electrodes 1006 and 1008 may be arranged in any suitable shape, such as a grid pattern, rings, wedges, strips, and so on. The electrodes 1006 and 1008 may be formed from any suitable electrically conductive materials, such as a metal or metal alloy, for example, a glass-reinforced epoxy laminate.

[0083] In one embodiment, the electrodes 1006 and 1008 are electrically insulated from substrates disposed on the transport belt 220. To enable electrostatic chucking of the substrates, a top surface of the transport belt 220 having the electrodes 1006 and 1008 embedded therein or disposed thereon may be coated or encapsulated with an electrically insulating material, such as a dielectric material.

[0084] The dielectric material may be deposited conformally onto the electrodes 1006 and 1008 and transport belt 220 to form a thin, uniform dielectric layer (not shown) or coating over the electrodes 1006 and 1008 and transport belt 220. In one embodiment, the dielectric material may be a dielectric tape adhered to the transport belt 220 and substantially covering the electrodes 1006 and 1008. The dielectric layer may comprise one of boron nitride, aluminum oxide, diamond-like carbon (DLC), DLC matrix composite materials, Dylyn®, Kapton®, or combinations thereof, although other materials may be used. In one embodiment, a Kapton® tape having a silicon adhesive may be disposed over the top surface of the transport belt 220 and the electrodes 1006 and 1008. As power is provided to the electrodes 1006 and 1008, an electrical potential, or field, may be created across the electrodes 1006 and 1008 to chuck the substrates. By chucking the substrates, flutter may be eliminated which may reduce the risk of substrate damage.

[0085] Figure 10B is a perspective view of the electrostatic chuck 1020 and associated architecture. The electrostatic chuck 1020 comprises the electrodes 1006 and 1008 and a dielectric layer disposed over the electrodes 1006 and 1008 and the transport belt 220. In the embodiment shown, the brush 1010 couples the second electrode 1008 (anode) to the electrified rail 1002 which may be coupled to the positive (+) chucking power source 1032. The electrified rail 1002 may be disposed on or embedded in the sidewall 206. The transport belt 220 having the electrostatic chuck 1020 disposed thereon moves linearly along a transport path, generally disposed above the support plate 222.

[0086] In one embodiment, a substrate may be loaded on to the transport belt 220 and transferred through the discrete volumes to or from the one or more processing chambers. As the substrate is loaded on the transport belt 220, the substrate may not be chucked. After the substrate is loaded, the substrate may become chucked by the electrostatic chuck 1020. The location at which the substrate becomes chucked may be determined by the location of the electrified rails 1002 and 1004 on the sidewalls 206. The electrified rails 1002 and 1004 may continuously occupy a length along the transport path of the dynamic load lock chamber during which it may be desirable to chuck the substrate. The electrified rails 1002 and 1004 may terminate and not be present at regions along the transport path of the dynamic load lock chamber where it is undesirable to chuck the substrate, such as regions where the substrate may be loaded and unloaded.

[0087] It is contemplated that other electrostatic chucking techniques that are capable of chucking a substrate while the substrate is moved over a distance may also be utilized. For example, an electrostatic puck, which may negate the necessity of continuous electrical contact during chucking due to the capability of forming a charge across electrodes on the chuck, holding a charge through the transfer process and being able to discharge the retained charge at a later time, may be utilized to prevent substrate flutter as the substrate is transferred through the dynamic load lock chamber.

[0088] 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 . An apparatus for transporting a substrate, comprising:

a transport belt having a first surface, wherein the transport belt is configured to be translated relative to a support surface of a support; and

a substrate retainer having one or more engaging portions that are adapted to retain a substrate disposed over the first surface of the transport belt, the substrate retainer being rotatably coupled to the transport belt and to a plurality of activation members, and wherein the substrate retainer is adapted to rotate relative to the transport belt as one of the activation members interacts with an actuator that is coupled to the support surface of the support.

2. The apparatus of claim 1 , wherein the engaging portions of the substrate retainer extend above the first surface of the transport belt.

3. The apparatus of claim 1 , wherein at least a portion of the substrate retainer is disposed within a first hole of the transport belt.

4. The apparatus of claim 3, wherein a plurality of second holes are formed in the first surface of the transport belt.

5. The apparatus of claim 4, wherein rotation retention members are disposed within the second holes.

6. The apparatus of claim 3, further comprising a retainer housing aligned with the first hole of the transport belt on a second surface of the transport belt, wherein the second surface is opposite the first surface.

7. The apparatus of claim 6, wherein the retainer housing is coupled to the substrate retainer through the first hole.

8. The apparatus of claim 6, wherein the activation members are disposed within the retainer housing.

9. The apparatus of claim 5, wherein the rotation retention members are magnets.

10. The apparatus of claim 9, wherein the activation members are magnets.

1 1 . The apparatus of claim 10, wherein a first rotation retention member has a first polarity and a second rotation retention member has a second polarity opposite the first polarity.

12. The apparatus of claim 1 1 , wherein a first activation member has a polarity opposite the polarity of the first rotation retention member.

13. The apparatus of claim 12, wherein a second activation member has a polarity opposite the polarity of the second rotation retention member.

14. An apparatus for transporting a substrate, comprising:

a transport belt having a first surface, wherein the transport belt is configured to translate relative to a support surface of a support;

a motion limiter comprising one or more first arms and one or more second arms, wherein the motion limiter is rotatably coupled to the transport belt; and

a trigger positioned to engage with the one or more first arms or the one or more second arms of the motion limiter as the transport belt is translated relative to the support surface, wherein the engagement of the first arm with the trigger causes the motion limiter to rotate so that the second arm is disposed over a surface of the substrate.

15. An apparatus for transporting a substrate, comprising:

a transport belt having an electrostatic chuck disposed thereon, the electrostatic chuck comprising; a plurality of electrodes coupled to a region of the transport belt; and a dielectric material disposed over the plurality of electrodes;

a plurality of brushes coupled to the transport belt and adapted to electrically couple the electrodes with a plurality of electrified rails; and

a chucking power source adapted to electrically bias the electrodes.