Particle beam inspection apparatus

Abstract

To provide an improved particle beam inspection apparatus, and more specifically, a particle beam inspection apparatus including an improved load lock unit.SOLUTION: An improved load lock system may comprise a plurality of supporting structures configured to support a wafer, and a conditioning plate including a heat transfer element configured to adjust a temperature of the wafer. The load lock system may further comprise a gas vent configured to provide a gas between the conditioning plate and the wafer, and a controller configured to assist with the control of the heat transfer element.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 699,643, filed July 17, 2018, and U.S. Provisional Patent Application No. 62 / 869,986, filed July 2, 2019, both of which are incorporated by reference in their entireties herein.

[0002] SUMMARY OF THE DISCLOSURE

[0002] Embodiments provided herein disclose a particle beam inspection apparatus, and more specifically, a particle beam inspection apparatus that includes an improved load lock unit. [Background technology]

[0003]

[0003] When manufacturing semiconductor integrated circuit (IC) chips, pattern defects and / or unwanted particles (residues) inevitably occur on the wafer or mask during the manufacturing process, which can significantly reduce yields. For example, unwanted particles can be problematic for patterns with smaller critical feature dimensions that have been adopted to meet the increasingly higher performance requirements of IC chips.

[0004]

[0004] Pattern inspection tools using charged particle beams have been used to detect defects or unwanted particles. These tools typically employ scanning electron microscopes (SEMs). In an SEM, a beam of relatively high energy primary electrons is decelerated to impinge on a sample with a relatively low landing energy and focused to form a probe spot on the sample. This focused probe spot of primary electrons generates secondary electrons from the surface. By scanning the probe spot across the sample surface and collecting the secondary electrons, the pattern inspection tool can obtain an image of the sample surface.

[0005]

[0005] During operation of the inspection tool, the wafer is typically held by a wafer stage. The inspection tool may include a wafer positioning device for positioning the wafer stage and the wafer relative to the electron beam. This may be used to position a target area on the wafer, i.e. the area to be inspected, within the operating range of the electron beam. Summary of the Invention

[0006]

[0006] Embodiments provided herein disclose a particle beam inspection apparatus, more specifically, a particle beam inspection apparatus including an improved load lock unit. In some embodiments, the improved load lock system includes a plurality of support structures configured to support a wafer and a first conditioning plate. The first conditioning plate includes a first heat exchange element configured to adjust a temperature of the wafer. The improved load lock system also includes a first gas vent configured to supply gas between the first conditioning plate and the wafer. Additionally, the improved load lock system includes a controller including a processor and a memory. The controller is configured to assist in controlling the first heat exchange element.

[0007]

[0007] In some embodiments, a method for thermal conditioning of a wafer in a load lock system is provided. The method includes loading a wafer into a load lock chamber of the load lock system and pumping down the load lock chamber. The method further includes supplying a gas to the load lock chamber. The method also includes allowing a temperature of the first conditioning plate to be conditioned such that a first heat exchange element in a first conditioning plate transfers heat to the wafer via the gas.

[0008]

[0008] In some embodiments, a non-transitory computer readable medium is provided. The non-transitory computer readable medium includes a set of instructions, which is executable by one or more processors of a controller, causing the controller to perform a method for thermal conditioning of a wafer. The method includes instructing a vacuum pump to pump down a load lock chamber of a load lock system after a wafer is loaded into the load lock chamber. The method also includes instructing a gas supply to supply gas to the load lock chamber, and instructing a first heat exchange element in the first conditioning plate to adjust a temperature of the first conditioning plate to transfer heat to the wafer via the gas.

[0009] In some embodiments, a method of pumping down a load lock chamber is provided, the method including evacuating gas from the load lock chamber with a first vacuum pump configured to evacuate the gas to a first exhaust system, and evacuating gas from the load lock chamber with a second vacuum pump configured to evacuate the gas to a second exhaust system.

[0010]

[0010] Other advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which there are set forth, by way of illustration and example, certain embodiments of the invention. [Brief description of the drawings]

[0011]

[0011] The above and other aspects of the present disclosure will become more apparent from the following description of exemplary embodiments taken in conjunction with the accompanying drawings.

[0012] [Figure 1A] 1 is a schematic diagram illustrating an exemplary charged particle beam inspection system consistent with an embodiment of the present disclosure. [Figure 1B]

[0013] 1B is a schematic diagram illustrating an example wafer loading sequence in the charged particle beam inspection system of FIG. 1A consistent with an embodiment of the present disclosure. [Figure 1C]

[0014] 1 is a schematic diagram illustrating an exemplary wafer deformation effect in a charged particle beam inspection system. [Diagram 2]

[0015] 1 is an exemplary graph illustrating wafer temperature change over time in a charged particle beam inspection system. [Figure 3A]

[0016] FIG. 1 is a schematic diagram illustrating an example load lock system consistent with an embodiment of the present disclosure. [Figure 3B] 1 is a schematic diagram illustrating an exemplary load lock system consistent with an embodiment of the present disclosure. [Figure 3C]

[0017] 1 is an example graph illustrating wafer temperature change over time during adjustment of wafer temperature in a load lock system consistent with an embodiment of the present disclosure. [Figure 3D]

[0018] FIG. 1 is a schematic diagram illustrating an example load lock system consistent with an embodiment of the present disclosure. [Figure 3E] 1 is a schematic diagram illustrating an exemplary load lock system consistent with an embodiment of the present disclosure. [Figure 3F]

[0019] 1 is an example graph illustrating the change in heat transfer efficiency versus gas pressure level in a load lock system, consistent with an embodiment of the present disclosure. [Figure 4]

[0020] FIG. 1 is a schematic diagram of an example pre-aligner in a front-end equipment module (EFEM) consistent with an embodiment of the present disclosure. [Diagram 5]

[0021] 1 is a schematic diagram illustrating an example configuration of a wafer conditioning system consistent with an embodiment of the present disclosure. [Figure 6A]

[0022] 1 is a schematic diagram illustrating an example configuration of a wafer conditioning system consistent with an embodiment of the present disclosure. [Figure 6B]

[0023] 6B is a schematic diagram illustrating an example support structure of the wafer conditioning system of FIG. 6A, consistent with an embodiment of the present disclosure. [Figure 6C]

[0024] 1 is an exemplary graph illustrating temperature changes during a conditioning process in a wafer conditioning system consistent with embodiments of the present disclosure. [Figure 6D]

[0025] 1 is a schematic diagram illustrating an example control circuit for a wafer conditioning system consistent with an embodiment of the present disclosure. [Figure 7]

[0026] 4 is a flow chart illustrating an example method for adjusting a wafer temperature consistent with an embodiment of the present disclosure. [Figure 8A]

[0027] 1 is a schematic diagram illustrating an example charged particle beam inspection system including a vacuum pumping system consistent with an embodiment of the present disclosure. [Figure 8B] FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam inspection system including a vacuum pumping system consistent with an embodiment of the present disclosure. [Figure 9]

[0028] 1 is an exemplary graph illustrating pressure changes in a main chamber of a charged particle beam inspection system consistent with embodiments of the present disclosure. [Figure 10]

[0029] 1 is a schematic diagram illustrating an example charged particle beam inspection system including a vacuum pumping system consistent with an embodiment of the present disclosure. [Figure 11]

[0030] 11 is a flow diagram illustrating an exemplary method for controlling a vacuum level of a load lock chamber of the charged particle beam inspection system of FIG. 10 consistent with an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013]

[0031] Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, in which like numbers in different drawings represent the same or similar elements unless otherwise noted. The implementations set forth in the following description of the exemplary embodiments do not represent all implementations consistent with the present invention. Instead, they are merely examples of apparatus and methods consistent with aspects related to the present invention as recited in the appended claims.

[0014]

[0032] Electronic devices consist of circuits formed on a piece of silicon called a substrate. Many circuits may be formed together on the same piece of silicon and are called an integrated circuit, or IC. The dimensions of these circuits have been dramatically reduced so that many more circuits can fit on a substrate. For example, an IC chip in a smartphone can be as small as a thumbnail yet contain over 2 billion transistors, with each transistor measuring less than 1 / 1000th the size of a human hair.

[0015]

[0033] Manufacturing these extremely small ICs is a complex, time-consuming, and expensive process that often involves hundreds of individual steps. An error in just one step can result in a defect in the finished IC, rendering it useless. Thus, one goal of the manufacturing process is to avoid such defects and maximize the number of functional ICs produced in the process, i.e., to increase the overall yield of the process.

[0016]

[0034] One component of improving yield is monitoring the chip fabrication process to ensure that a sufficient number of functional integrated circuits are being produced. One way to monitor the process is to inspect the chip circuit structures at various stages in their formation. Inspection can be performed using a scanning electron microscope (SEM). An SEM allows one to image these very small structures, essentially taking a "picture" of them. This image can be used to determine if the structures were formed properly, and if they were formed in the proper location. If the structures are defective, the process can be adjusted to make it less likely that the defects will occur again.

[0017]

[0035] In IC chip manufacturing facilities, a high manufacturing process yield is desirable, but it is also essential to maintain a high wafer throughput, defined as the number of wafers processed per hour. High manufacturing process yield and high wafer throughput can be affected by the presence of defects, especially when operator intervention is required to inspect the defects. Therefore, high throughput detection and identification of micro- and nano-sized defects by inspection tools (such as SEMs) is essential to maintain high yields and low costs.

[0018]

[0036] One aspect of the present disclosure includes an improved load lock system that increases the throughput of the overall inspection system. The improved load lock system prepares the wafer in a manner that speeds up the inspection process when compared to conventional particle beam inspection systems. For example, an operator inspecting a wafer using a conventional particle beam inspection system must wait for the wafer to temperature stabilize before beginning inspection. This temperature stabilization is necessary because changes in temperature cause the size of the wafer to change, which in turn causes elements on the wafer to move as the wafer expands or contracts. For example, FIG. 1C shows that elements 180, 182, 184, and 186 may move to new positions 170, 172, 174, and 178 as wafer 160 expands due to temperature changes. This change in position is significant when the precision for inspecting the wafer is in nanometers. Thus, the operator must wait until the wafer is temperature stabilized before the operator can accurately locate and inspect the elements on the wafer.

[0019]

[0037] The improved load lock system conditions the wafer so that its temperature is close to that of the inspection wafer stage that will hold the wafer. The improved load lock system can condition the wafer before the wafer is placed on the wafer stage by including a conditioning plate that transfers heat to or from the wafer. By conditioning the wafer before it is placed on the wafer stage, inspection can begin with much less delay. Thus, an operator can inspect more wafers in a given period of time, thereby achieving increased throughput.

[0020]

[0038] The relative dimensions of components in the drawings may be exaggerated for clarity. In the following description of the drawings, the same or similar reference numbers refer to the same or similar components or entities, and only the differences with respect to the individual embodiments are described. As used herein, unless otherwise stated, the term "or" includes all possible combinations, unless otherwise stated, where feasible. For example, if a component is described as including A or B, the component may include A, or B, or A and B, unless otherwise stated, where feasible. As a second example, if a component is described as including A, B, or C, the component may include A, or B, or C, or A and B, or C, or A and B, and C, unless otherwise stated, where feasible.

[0021]

[0039] Reference is now made to FIG. 1A, which is a schematic diagram illustrating an exemplary charged particle beam inspection system 100 consistent with an embodiment of the present disclosure. As shown in FIG. 1, the charged particle beam inspection system 100 includes a main chamber 10, a load lock chamber 20, an electron beam tool 40, and an equipment front-end module (EFEM) 30. The electron beam tool 40 is disposed within the main chamber 10. It will be understood that although the description and drawings relate to an electron beam, the embodiments are not used to limit the invention to a particular charged particle. It will be further understood that the electron beam tool 40 can be a single beam tool utilizing a single electron beam, or a multi-beam tool utilizing multiple electron beams.

[0022]

[0040] The EFEM 30 includes a first loading port 30a and a second loading port 30b. The EFEM 30 may include additional loading ports. The first loading port 30a and the second loading port 30b may receive, for example, a wafer FOUP (front opening unified pod) that contains a wafer (e.g., a semiconductor wafer, or a wafer made of other material) or a sample (wafers and samples are hereinafter collectively referred to as "wafers") to be inspected. One or more robotic arms (e.g., the robotic arms shown in FIG. 1B) in the EFEM 30 transport the wafer to the load lock chamber 20.

[0023]

[0041] The load lock chamber 20 may be attached to the main chamber 10 with a gate valve (e.g., gate valve 26 in FIG. 1B) between the chambers. The load lock chamber 20 may include a sample holder (not shown) capable of holding one or more wafers. The load lock chamber 20 may also include a mechanical transfer device (e.g., robot arm 12 in FIG. 1B) for moving the wafer to and from the main chamber 10. The load lock chamber 20 may be connected to a load lock vacuum pumping system (not shown) that removes gas molecules in the load lock chamber 20 to reach a first pressure that is lower than atmospheric pressure. After the first pressure is reached, one or more robot arms (shown in FIG. 1B) carry the wafer from the load lock chamber 20 to the main chamber 10. The main chamber 10 is connected to a main chamber vacuum pumping system (not shown) that removes gas molecules in the main chamber 10 to reach a second pressure that is lower than the first pressure. After the second pressure is reached, the wafer is subjected to inspection by an electron beam tool 40.

[0024]

[0042] The controller 50 is electronically connected to the electron beam tool 40. The controller 50 may be a computer configured to perform various controls of the charged particle beam inspection system 100. In FIG. 1A, the controller 50 is shown as being external to the structure including the main chamber 10, the load lock chamber 20, and the EFEM 30, but it will be understood that the controller 50 may also be part of this structure. It should be noted that while the present disclosure provides an example of a main chamber 10 housing an electron beam inspection tool, aspects of the present disclosure in its broadest sense are not limited to chambers housing an electron beam inspection tool. Rather, it will be understood that the principles described above may also be applied to other tools operating under a second pressure.

[0025]

[0043] 1B, which is a schematic diagram illustrating an example wafer loading sequence in the charged particle beam inspection system 100 of FIG. 1A, consistent with embodiments of the present disclosure. In some embodiments, the charged particle beam inspection system 100 may include a robot arm 11 disposed within the EFEM 30 and a robot arm 12 disposed within the main chamber 10. In some embodiments, the EFEM 30 may include a pre-aligner 60 configured to precisely position the wafer before transferring the wafer to the load lock chamber 20.

[0026]

[0044] In some embodiments, the first loading port 30a and the second loading port 30b may receive, for example, wafer front opening unified pods (FOUPs) that house the wafers. A robot arm 11 in the EFEM 30 may transport the wafer from either of the loading ports to a pre-aligner 60 to assist in positioning. The pre-aligner 60 may use mechanical or optical alignment methods to position the wafer. After pre-alignment, the robot arm 11 may transport the wafer to the load lock chamber 20.

[0027]

[0045] After the wafer is transferred to the load lock chamber 20, a load lock vacuum pump (not shown) may remove gas molecules within the load lock chamber 20 to reach a first pressure that is lower than atmospheric pressure. After the first pressure is reached, the robot arm 12 may transfer the wafer from the load lock chamber 20 to a wafer stage 80 of the electron beam tool 40 in the main chamber 10. The main chamber 10 is connected to a main chamber vacuum pumping system (not shown), which removes gas molecules within the main chamber 10 to reach a second pressure that is lower than the first pressure. After the second pressure is reached, the wafer may be subjected to inspection by the electron beam tool.

[0028]

[0046] In some embodiments, the main chamber 10 may include a parking station 70 configured to temporarily store wafers prior to inspection. For example, once inspection of a first wafer is completed, the first wafer may be removed from the wafer stage 80, and the robot arm 12 may then transfer a second wafer from the parking station 70 to the wafer stage 80. The robot arm 12 may then transfer a third wafer from the load lock chamber 20 to the parking station 70 to temporarily store the third wafer until inspection of the second wafer is completed.

[0029]

[0047]

[0023] Referring now to Figure 2, Figure 2 is an exemplary graph showing wafer temperature change over time in a charged particle beam inspection system. The vertical axis represents temperature change and the horizontal axis represents time passing. The graph shows that the temperature of a wafer changes over time as the wafer is processed through multiple stages of a wafer loading sequence. According to the exemplary data shown in Figure 2, when a FOUP containing a wafer to be inspected is loaded into the first loading port 30a or the second loading port 30b, the temperature of the wafer is about 22.5 degrees.

[0030]

[0048] After the wafer is transferred to the load lock chamber, the wafer temperature drops rapidly by approximately 1 degree when the load lock chamber is pumped down to vacuum. This rapid temperature drop may be referred to as the pump-down effect. When the wafer is then transferred to and loaded onto the wafer stage, the wafer and the wafer stage may be at different temperatures. For example, the graph in FIG. 2 shows that when the wafer is loaded onto the wafer stage (annotated as 210 in FIG. 2), there may be a temperature difference of approximately 2.5 degrees between the wafer located in the load lock chamber (annotated as 220 in FIG. 2) and the wafer stage located in the main chamber (annotated as 230 in FIG. 2). Under such circumstances, heat transfer may occur between the wafer and the wafer stage, which may cause deformation of the wafer (or wafer stage) (e.g., thermal expansion as shown in FIG. 1C). While the wafer stage or wafer is undergoing thermal deformation, inspection of the target area may not be possible or may be less accurate. Thus, in order to perform a more accurate inspection, the system may wait a significant period of time for the temperature of the wafer to stabilize before beginning the inspection. This wait time reduces the throughput of the inspection system.

[0031]

[0049] An example of a wafer stage for faster temperature stabilization can be found in European Patent Application No. EP18174642.1, filed May 28, 2018, entitled "PARTICLE BEAM APPARATUS," which is incorporated by reference in its entirety. Another way to address this long stabilization time is to adjust the wafer temperature before the wafer is loaded onto the wafer stage by pre-heating or pre-cooling the wafer to match the temperature of the wafer stage. In such an embodiment, the adjustment step may occur while the previous wafer is being inspected on the wafer stage, thus improving the overall throughput of the inspection system as compared to a system in which the adjustment is made after the wafer is loaded onto the wafer stage.

[0032]

[0050] In some embodiments, the temperature conditioning function may be implemented in the load lock chamber, which may provide increased throughput as well as future flexibility. If wafer temperature conditioning is performed in the load lock chamber, the next wafer in the pipeline may be loaded into the load lock chamber while inspection of the previous wafer is in progress. In some examples, it is calculated that in this sequence, the maximum time available to condition a wafer is about 5-10 minutes, which is roughly the minimum wafer inspection time for the shortest user case in the current range. Thus, one advantage of performing wafer temperature conditioning in the load lock chamber is that the wafer conditioning time can be hidden behind the inspection time, since the conditioning of the next wafer and the inspection of the current wafer can be performed simultaneously. This may improve the overall throughput of the particle beam inspection system.

[0033]

[0051] In some embodiments, a charged particle beam inspection system (such as the charged particle beam inspection system 100 of FIG. 1B) may include a coarse temperature adjuster and a fine temperature adjuster. For example, a pre-aligner (such as the pre-aligner 60 of FIG. 1B) may include a coarse adjuster, while a load lock chamber (such as the load lock chamber 20) includes a fine adjuster. The coarse adjuster may adjust the wafer, for example, from a coarse offset of 2 degrees to 500 mK, while the fine adjuster may adjust the wafer, for example, from a fine offset of 500 mK to 50 mK.

[0034]

[0052] 3A, which illustrates an exemplary load lock system 300a consistent with embodiments of the present disclosure. In some embodiments, the load lock system 300a may include an adjusting plate 315 and a number of support structures 325 configured to transfer heat to the wafer 320. In other embodiments, the adjusting plate 315 may additionally or alternatively be configured to transfer heat from the wafer 320. The support structures 325 coupled to the adjusting plate 315 may support the wafer 320 such that there is space between the wafer 320 and the adjusting plate 315. It will be appreciated that more efficient heat transfer may be achieved if the wafer 320 is positioned closer to the adjusting plate 315, but in some embodiments, it may be desirable to provide a sufficient distance between the wafer 320 and the adjusting plate 315 to provide space for a robotic arm to lift or carry the wafer 320. In some embodiments, the distance between the wafer 320 and the adjusting plate 315 may be in the range of 1.5 mm to 10 mm to provide space to accommodate various robot arm sizes when lifting or transporting the wafer. In some embodiments, the distance between the wafer 320 and the adjusting plate 315 may be in the range of 3 mm to 5 mm to provide space to accommodate certain types of robot arms while providing more efficient heat transfer without requiring special treatment for the robot arm transport. In some embodiments, a special mechanism for lifting the wafer 320 may be used to make this distance smaller.

[0035]

[0053] 3A, it will be understood that the system 300a may include any number of support structures 325. In some embodiments, the wafer 320 may be passively placed on top of the support structures 325 without the use of any active coupling means (e.g., electrostatic clamps). In other embodiments, the wafer 320 may be held on the support structures 325 using an active holding means, such as an electrostatic clamp.

[0036]

[0054] The load lock system 300a may include a load lock chamber 310, such as the load lock chamber 20 of FIG. 1A. In some embodiments, the load lock chamber 310 may be configured to vary its internal pressure between atmospheric pressure and vacuum. A pump, such as a turbo pump (not shown), may be connected to the load lock chamber 310 to maintain the vacuum level at an appropriate level for regulating the temperature of the wafer 320. It will be appreciated that the pump may be a different type of pump than a turbo pump, so long as the pump is suitable for establishing a vacuum within the load lock chamber 310.

[0037]

[0055] In some embodiments, the conditioning plate 315 may include a heat exchange element 340 configured to alter a temperature of the conditioning plate 315, which in turn affects the temperature of the wafer 320. The heat exchange element 340 may be coupled to a heater / cooler 360. In some embodiments, the heater / cooler 360 may be located outside the load lock chamber 310. In other embodiments, the heater / cooler 360 may be located inside the load lock chamber 310.

[0038]

[0056] The load lock system 300a may further include a controller 350 configured to adjust the heater / cooler 360 or heat exchange element 340 to change the temperature of the conditioning plate 315, which in turn affects the temperature of the wafer 320. In some embodiments, the controller 350 may receive stage temperature data related to the temperature of the wafer stage 395 in the main chamber 390. For example, in some embodiments, the controller 350 may receive an electrical signal conveying the stage temperature data from a temperature sensor 396 configured to measure the temperature of the wafer stage 395. In such embodiments, the controller 350 may control the heater / cooler 360 to adjust the temperature of the conditioning plate 315 based on the stage temperature data related to the temperature of the wafer stage 395.

[0039]

[0057] In some embodiments, the controller 350 may receive heater temperature data related to the temperature of the output of the heater / cooler 360. In such embodiments, the controller 350 may control the heater / cooler 360 to adjust the temperature of the conditioning plate 315 based on the heater temperature data. For example, in some embodiments, the heater / cooler 360 may be a hot or cold water device. In such embodiments, heated or cooled water flows through the heat exchange element 340 in the conditioning plate 315, and the controller 350 may receive heater temperature data related to the temperature of the water at the output of the heater / cooler 360. The controller 350 may adjust the heater / cooler 360 based on the temperature of the water. In some embodiments, the controller 350 may receive an electrical signal carrying the heater temperature data from a temperature sensor 365 configured to measure the temperature of the water. In some embodiments, the controller 350 may adjust the temperature of the conditioning plate 315 using both the stage temperature data and the heater temperature data. In such an embodiment, for example, the controller 350 may adjust the heater / cooler 360 to match the heater temperature (eg, the temperature of the water at the output of the heater / cooler 360 ) to the temperature of the wafer stage 395 .

[0040]

[0058] In some embodiments, the controller 350 may be further optimized using additional temperature sensors. For example, in some embodiments, the system may include one or more additional sensors configured to measure the temperatures of the wafer 320 and the conditioning plate 315.

[0041]

[0059] In some embodiments, the load lock system 300a may include one or more gas vents (e.g., gas vents 330 or 335) to supply gas 338 from a gas supply to the load lock chamber 310. In such embodiments, the gas 338 may increase thermal conduction between the wafer 320 and the conditioning plate 315, leading to a shorter time for the wafer 320 to reach a stable temperature. For example, heat transfer between the wafer 320 and the conditioning plate 315 may occur by radiation and gas 338. The gas 338 may be nitrogen, helium, hydrogen, argon, CO2, or compressed dry air. It will be appreciated that the gas 338 may be any other gas suitable for heat transfer. Valves 370 and 375 may be disposed between the gas supply and the load lock chamber 310. The gas vents 330 and 335 may be connected to a gas supply via gas lines extending from the gas supply to the holes 330 and 335, which lead to the load lock chamber 310 and may provide gas between the wafer 320 and the conditioning plate 315. In some embodiments, the gas vents 330 and 335 may be opened after the load lock chamber is pumped down to a vacuum level. In some embodiments, a load lock vacuum pump (e.g., a turbo pump) may be enabled while the gas 338 is being supplied to the load lock chamber 310 to continuously remove a portion of the gas 338 molecules and maintain the vacuum level during the wafer conditioning process.

[0042]

[0060] As shown in FIG. 3F, increasing the gas pressure increases the efficiency of heat transfer. However, as the gas pressure approaches a certain level, e.g., 100 Pa or more in FIG. 3F, the efficiency may not increase as much. Thus, in some embodiments, the gas pressure in the space between the wafer 320 and the conditioning plate 315 may be in the range of 50 Pa to 5,000 Pa during conditioning of the wafer 320 to provide efficient heat transfer while keeping the gas pressure level low enough. In some embodiments, the gas pressure may be in the range of 100 Pa to 1,000 Pa during conditioning of the wafer 320 to provide a balance between heat transfer efficiency while keeping the gas pressure close to vacuum.

[0043]

[0061] In some embodiments, the gas 338 may be temperature conditioned so that the gas molecules themselves can provide heat transfer to the wafer 320. For example, the gas supply, gas valves 370 and 375, or any other portion of the load lock system 300a may include heaters to precondition the temperature of the gas 338 before providing it to the chamber 310.

[0044]

[0062] In some embodiments, one or more gas vents 330 and 335 may be included in the load lock chamber 310 as shown in FIG. 3A. In other embodiments, such as the load lock system 300b shown in FIG. 3B, at least one of the gas vents (e.g., gas vent 330 of FIG. 3B) may be included in the conditioning plate 315 and may directly supply gas 338 to the space between the wafer 320 and the conditioning plate 315. For example, in such an embodiment, the gas vent 330 may be included in the conditioning plate 315 and may be located at or near the center of the wafer 320. It will be appreciated that the gas vent may be located anywhere else, so long as the vent is suitable for supplying gas 338 to the space between the wafer 320 and the conditioning plate 315 in the load lock chamber 310. It will also be appreciated that the load lock systems 300a and 300b may include any number of gas vents. In some embodiments, the controller 350 may be configured to adjust the gas vents 330 or 335 to vary the gas flow rate into the load lock chamber 310 .

[0045]

[0063] FIG. 3C shows an example graph illustrating the change in wafer temperature over time during wafer temperature conditioning in a load lock system. As heat is transferred to the wafer, the temperature of the wafer (T wafer ) is the temperature of the wafer stage (T wafer stage ) gradually approaches the stable temperature (T stable ) the adjustment process may be complete. stable may be the same as the temperature of the wafer stage. stable is approximately 100 mK lower than the wafer stage temperature (T wafer stage −100 mK), resulting in improved effective throughput. stable can be a set point at about 22° C. In another example, T stable can be a set value within the range of 20 to 28°C.

[0046]

[0064] In some embodiments, as shown in FIG. wafer T stable , a controller (such as controller 350 in FIG. 3A) may adjust a heater (such as heater / cooler 360 in FIG. 3A) to gradually reduce the conditioning plate temperature to prevent overshooting of the wafer temperature.

[0047]

[0065] Wafer 320 is T stable After reaching the conditioning step, the conditioning step ends and then the gas flow through the gas vents (such as gas vents 330 and 335 in FIG. 3A) may be stopped. In some embodiments, after stopping the gas flow, the load lock vacuum pump may continue to operate until the pressure in the load lock chamber (such as load lock chamber 310 in FIG. 3A) is at or near the pressure in the main chamber (such as main chamber 390 in FIG. 3A). Because the pressure inside the load lock chamber may already be maintained near a vacuum (e.g., 10-10,000 Pa), the pressure difference between the load lock chamber and the main chamber may be relatively small. In some embodiments, a heater (such as heater / cooler 360 in FIG. 3A) may maintain the temperature of the conditioning plate such that residual radiation from the conditioning plate can help maintain the temperature of the wafer during pump down.

[0048]

[0066] Once the gas pressure in the load lock chamber reaches or near the pressure in the main chamber, in some embodiments the wafer may be transferred to a wafer stage (such as wafer stage 395 in FIG. 3A) for inspection. The temperature of the wafer may be at or near the temperature of the wafer stage so that inspection can begin with a minimal waiting period. In other embodiments, the wafer may be transferred to a parking station (such as parking station 70 in FIG. 1B) and temporarily stored until the ongoing inspection of the previous wafer is completed.

[0049]

[0067] 3D , which illustrates another example load lock system 300d consistent with embodiments of the present disclosure. In some embodiments, the load lock system 300d can include an adjusting plate 315 and a number of support structures 325 configured to transfer heat to a wafer 320. In some embodiments, the adjusting plate 315 can include a heat exchange element 340.

[0050]

[0068] In some embodiments, as shown in FIG. 3D, the conditioning plate 315 may be positioned above the wafer 320. In such embodiments, the wafer 320 is supported by a support structure 325 coupled to the support plate 319. It will be appreciated that more efficient heat transfer can be achieved if the wafer 320 is positioned closer to the conditioning plate 315, but in some embodiments, it may be desirable to provide a sufficient distance between the wafer 320 and the conditioning plate 315 to provide space for a robotic arm to lift or carry the wafer 320. However, in the configuration shown in FIG. 3D, the conditioning plate 315 is positioned above the wafer 320, allowing the conditioning plate 315 to be positioned much closer to the wafer 320. In some embodiments, the distance between the wafer 320 and the conditioning plate 315 may be reduced to about 1 mm.

[0051]

[0069] In some embodiments, the load lock system 300d may include gas vents 330 and 335 to supply gas 338 to the space between the wafer 320 and the conditioning plate 315. In some embodiments, at least one gas vent may be included in the conditioning plate 315 to supply gas 338 to the space. It will be appreciated that the gas vents 330 or 335 may be located in other locations of the load lock system 300d, so long as those locations are suitable for supplying gas 338 to the space between the wafer 320 and the conditioning plate 315 in the load lock chamber 310. It will also be appreciated that the load lock system 300d may include any number of gas vents.

[0052]

[0070] 3E, which illustrates another exemplary load lock system 300e consistent with embodiments of the present disclosure. The load lock system 300e may include multiple conditioning plates configured to transfer heat to the wafer 320 from multiple directions. For example, the load lock system 300e may include an upper conditioning plate 317 configured to transfer heat in a downward direction and a lower conditioning plate 318 configured to transfer heat in an upward direction. In some embodiments, the upper conditioning plate 317 may include a heat exchange element 340. In some embodiments, the lower conditioning plate may include a heat exchange element 340. The lower conditioning plate 318 may be coupled to a support structure 325 configured to support the wafer 320. The load lock system 300e may include gas vents 330 and 335 to provide gas 338 to a space between the wafer 320 and the conditioning plates 317 and 318. In some embodiments, at least one gas vent may be included in the upper conditioning plate 317. In some embodiments, at least one gas vent may be included in the lower adjusting plate 318 .

[0053]

[0071] Reference is now made to FIG. 4, which is a schematic diagram of an exemplary pre-aligner in an equipment front-end module (EFEM) consistent with an embodiment of the present disclosure. In some embodiments, the pre-aligner may include one or more support structures 425 configured to support a wafer 420 and an conditioning plate 415 configured to transfer heat via heated compressed air from one or more air vents 440. In some embodiments, the conditioning plate 415 further includes one or more vacuum channels 450 configured to remove air. In such an embodiment, heat transfer between the wafer 420 and the conditioning plate 415 may occur primarily by convection via temperature-conditioned compressed air provided via one or more air vents 440. Because the conditioning of the wafer is performed through forced convection of temperature-conditioned compressed air, heat is efficiently transferred to and from the wafer 420, and thus the wafer temperature can be quickly stabilized to a stable temperature.

[0054]

[0072] Referring now to FIG. 5, FIG. 5 illustrates a schematic diagram showing an example configuration of a wafer conditioning system 500 consistent with embodiments of the present disclosure. In some embodiments, the wafer conditioning system 500 may include a conditioning plate 515 and a number of support structures 525 configured to transfer heat to the wafer 520. The support structures 525 coupled to the conditioning plate 515 may support and transfer heat to the wafer 520. It will be appreciated that the support structures 525 may be of any shape suitable for support and transfer of heat. In some embodiments, the conditioning plate 515 may include a heat exchange element 540 configured to alter a temperature of the conditioning plate 515, which in turn affects the temperature of the wafer 520. The heat exchange element 540 may be coupled to a heater 560. In some embodiments, the heater 560 may be located outside the vacuum chamber 510. In other embodiments, the heater 560 may be located inside the vacuum chamber 510.

[0055]

[0073] In some embodiments, the conditioning plate 515 may further include an electrostatic clamp 570. The electrostatic clamp 570 may clamp the wafer 520 to the conditioning plate 515 via an electric charge. A power source (not shown) provides the electric charge that connects the wafer 520 to the electrostatic clamp 570. For example, the electrostatic clamp 570 may be part of or included within the conditioning plate 515. In other examples, the electrostatic clamp 570 may be separate from the conditioning plate 515. In some embodiments, the conditioning plate 515 may include a lifting structure 526 configured to accommodate a robotic arm (not shown) for lifting the wafer 520 and transporting the wafer 520.

[0056]

[0074] In some embodiments, the vacuum chamber 510 may include a heat exchange element 545 configured to change the temperature of the vacuum chamber 510. In such embodiments, heat may be transferred from an inner surface of the vacuum chamber 510 to the wafer 520 via radiation (as shown in FIG. 5). The vacuum chamber 510 may be the load lock chamber 20 of FIG. 1B, part of the parking station 70 of FIG. 1B, or the main chamber 10 of FIG. 1B.

[0057]

[0075] 6A, which illustrates a schematic diagram illustrating another exemplary configuration of a wafer conditioning system 600 consistent with embodiments of the present disclosure. System 600 may include a vacuum chamber 610 and one or more support structures 625 configured to support a wafer 620. In some embodiments, wafer conditioning system 600 may include one or more heating devices configured to transfer heat to wafer 620 via radiation from multiple directions. For example, as shown in FIG. 6A, system 600 may include an upper heating device 617 and a lower heating device 618.

[0058]

[0076] In some embodiments, the heating device 617 or 618 may be a conditioning plate, one or more tubes, or one or more coils configured to radiate heat to the wafer 620. In some embodiments, the system 600 may include a single heating device, which may be located above or below the wafer 620. In some embodiments, the system 600 may include an upper heating device 617 and a lower heating device 618 positioned relative to the wafer 620. In some embodiments, the system 600 may include three or more heating devices. In some embodiments, the system 600 may include a heater 660 configured to provide heat to the heating device 617 or 618. In some embodiments, the heater 660 may be a water heater or any other type of heater capable of providing heat to the heating device 617 or 618.

[0059]

[0077] In some embodiments, the support structure 625 may include a temperature sensor 627 configured to measure the temperature of the wafer 620. The temperature sensor 627 may include a thermocouple (TC), an NTC thermistor, a PTC thermistor, a resistance thermometer, an infrared thermometer, or any other device suitable for measuring the temperature of the wafer 620. For example, as shown in FIG. 6B, the support structure 625 may include a thermocouple configured to measure the temperature of the wafer 620. To enable the temperature of the wafer to be measured, the support structure 625 may include a spring-like structure to urge the thermocouple into contact with the wafer 620. In some embodiments, the thermocouple and the spring-like structure may be surrounded by the support structure 625.

[0060]

[0078] Because the system 600 operates in a vacuum chamber 610, heat transfer from the wafer to the thermocouples to measure the wafer temperature may be via conduction and radiation. For some embodiments, it may be desirable to minimize heat radiation to the thermocouples to more accurately measure the temperature of the wafer 620. Thus, the surfaces of the thermocouples, except for the surfaces that contact the wafer 620, may be covered by one or more structures made of a material that does not transfer heat so that the thermocouples can receive heat from the wafer 620 via conduction. In some embodiments, the support structure 625 may be made of a material that prevents heat transfer. In some embodiments, the system 600 may include multiple thermocouples to collect temperature information from multiple portions of the wafer 620. In such an embodiment, a controller (such as the controller 650 shown in FIG. 6E) may determine a temperature distribution characteristic of the wafer 620.

[0061]

[0079] Reference is now made to FIG. 6C, which is an exemplary graph showing temperature changes during the conditioning process. The wafer conditioning system may include a control mechanism to change the temperature of the heating device in-situ while wafer conditioning is in progress. Additionally, in some embodiments, the wafer conditioning system may include one or more temperature sensors configured to measure the temperature of various parts of the system. In some embodiments, the wafer conditioning system may include one or more temperature sensors configured to measure the temperature of the wafer itself. FIG. 6C shows the temperature change over time in one such embodiment. In such an embodiment, the heating device may be heated to a high temperature (a desired stable temperature, T stable (higher) to start the adjustment process, and then T wafer T stable As the temperature approaches the desired stable temperature, the temperature can be gradually decreased to the desired stable temperature. In such an embodiment, the process may be further optimized with temperature information from the sensor. As shown in Figure 6C, by controlling the temperature in such a manner, the adjustment time can be significantly reduced.

[0062]

[0080] Referring now to FIG. 6D, FIG. 6D is a schematic diagram illustrating an example control circuit of a wafer conditioning system consistent with an embodiment of the present disclosure. In some embodiments, a wafer conditioning system, such as system 600 of FIG. 6A, may include a controller and one or more temperature sensors configured to measure various parts of the system. In some embodiments, a wafer conditioning system may include one or more temperature sensors configured to measure the temperature of a wafer. For example, controller 650 may receive temperature data related to the incoming wafer temperature from temperature sensor 696 in an equipment front-end module (such as EFEM 30 of FIG. 1A). Controller 650 may receive wafer temperature data related to the wafer temperature from temperature sensor 627. Controller 650 may receive heater temperature data related to the temperature of the heater 660 output (e.g., water at the output of a water heater) from temperature sensor 665. In some embodiments, controller 650 may control heater 660 based on at least one of the temperature data from sensors 696, 627, and 665. For example, the heater 660 may include an electric water heater configured to transfer heat to the water. Using temperature feedback, the controller 650 may adjust the current supplied to the heater 660, which results in a change in temperature of the heat exchange element (e.g., heating device 617 or 618 of FIG. 6A). In some embodiments, the controller 650 may be calibrated based on the type or condition of the wafer.

[0063]

[0081] Although the control mechanisms are described in the context of system 600 of FIG. 6A to explain functionality, it will be understood that the same control mechanisms can be applied to any of the embodiments of the wafer conditioning system shown in this disclosure.

[0064]

[0082] 7, which is a flow diagram illustrating an exemplary method for adjusting a wafer temperature consistent with an embodiment of the present disclosure that may be performed by a load lock system (e.g., load lock systems 300a, 300b, 300d, and 300e of FIGS. 3A-3D) of an electron beam system (e.g., charged particle beam inspection system 100 of FIG. 1A).

[0065]

[0083] In step 710, a wafer is loaded by a robot arm into the load lock chamber relative to the adjusting plate. In some embodiments, the wafer may be positioned above the adjusting plate. In other embodiments, the wafer may be positioned below the adjusting plate. In some embodiments, the wafer may be positioned between two adjusting plates.

[0066]

[0084] In step 720, after the wafer is loaded into the load lock chamber (eg, load lock chamber 20 of FIG. 1A), the controller (eg, controller 50 of FIG. 1A) turns on the vacuum pump to remove air from the load lock chamber.

[0067]

[0085] In step 730, the temperature of the wafer stage (eg, wafer stage 395 in FIG. 3A) is determined and provided to the controller.

[0068]

[0086] In step 740, a gas supply (e.g., the gas supply of FIG. 3A) supplies gas to the load lock chamber for heat transfer between the conditioning plate and the wafer. The gas may be temperature regulated to match the measured temperature of the wafer stage to provide more efficient heat transfer.

[0069]

[0087] In step 750, the controller receives the wafer stage temperature data and adjusts the heating temperature based on the determined temperature of the wafer stage.

[0070]

[0088] In step 760, after wafer conditioning is complete, the wafer conditioning system transfers the conditioned wafer from the load lock chamber to the main chamber (e.g., main chamber 390 of FIG. 3A) or to a parking station (e.g., parking station 70 of FIG. 3B). In some embodiments, if a temperature sensor is present to measure the temperature of the wafer, the controller may monitor the wafer temperature to determine whether wafer conditioning is complete.

[0071]

[0089] It will be appreciated that the controller of the wafer conditioning system can use software to control the above-mentioned functions. For example, the controller can send instructions to the aforementioned heater to change the temperature of the heat exchange element. The controller can also send instructions to adjust the input voltage or current to the heater. The software may be stored on a non-transitory computer-readable medium. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid state drives, magnetic tapes or any other magnetic data storage media, CD-ROMs, any other optical data storage media, any physical media with a pattern of holes, RAM, PROMs, and EPROMs, cloud storage, FLASH-EPROMs or any other flash memory, NVRAMs, caches, registers, any other memory chips or cartridges, and networked versions of the above.

[0072]

[0090] 8A and 8B, which show schematic diagrams illustrating an exemplary charged particle beam inspection system 800 with a vacuum pumping system consistent with embodiments of the present disclosure. In some embodiments, the charged particle beam inspection system 800 may include a main chamber 890 and a load lock chamber 810. In some embodiments, the system 800 may include a gas supply 811, a gas vent valve 812, and a gas vent diffuser 813 connected to the load lock chamber 810. The gas supply 811 may supply a gas (e.g., gas 338 in FIG. 3A) to the load lock chamber 810 during a wafer conditioning process to enhance thermal conductivity between the wafer (e.g., wafer 320 in FIG. 3A) and the conditioning plate (e.g., conditioning plate 315 in FIG. 3A). The gas may be nitrogen, helium, hydrogen, argon, CO2, or compressed dry air. It will be understood that the gas may be any other gas suitable for heat transfer.

[0073]

[0091] In some embodiments, evacuating the loadlock chamber 810 may be done in two stages via two separate paths. This first path may be referred to as the rough path and may include the loadlock rough line 816 and the loadlock rough valve 853. During the rough stage, the loadlock chamber 810 is pumped from atmospheric conditions to a "rough" vacuum level (e.g., 5×10 -1 In the first stage, the loadlock roughing valve 853 is opened to initially pump down the loadlock chamber 810 via the loadlock roughing line 816 while the other path is closed.

[0074]

[0092] The second path is referred to as the turbo pump path and may include a load lock turbo valve 814, a load lock turbo pump 815, a load lock turbo pump line 817, and a load lock turbo pump backing valve 851. After roughing of the load lock chamber 810 is complete, the load lock turbo pump 815 takes over to pump the load lock chamber 810 to a deeper vacuum level (e.g., 1.5×10 -6In this second phase, the loadlock roughing valve 853 is first closed. The loadlock turbo valve 814 and the loadlock turbo pump backing valve 851 are then opened so that the loadlock turbo pump 815 pumps down the loadlock chamber 810.

[0075]

[0093] The main chamber 890 may be evacuated in a similar manner. First, the main chamber 890 is evacuated from atmospheric conditions to a “rough” vacuum level (e.g., 5×10 ) via a main chamber roughing pathway (including a main chamber roughing line 896 and a main chamber roughing valve 854). -1 After the roughing phase is completed, main chamber turbo pump 895 takes over and pumps a deeper vacuum level (e.g., 1.5×10 Torr) via the main chamber turbo pump path (including main chamber turbo valve 894, main chamber turbo pump 895, main chamber turbo pump line 897, and main chamber turbo pump backing valve 852). -6 In some embodiments, the main chamber turbo pump 895 may continue to run until wafer inspection is complete.

[0076]

[0094] 8A shows the system 800 having one roughing path and one turbo pump path for the load lock chamber 810, it will be understood that the system may utilize any number of roughing and turbo pump paths to evacuate the load lock chamber 810. For example, the system 800 may have two or more roughing paths connected in parallel to the load lock chamber 810. Regardless of the number of roughing paths, the system 800 may have two or more turbo pumps connected in parallel to the load lock chamber 810. Similarly, it will be understood that the system may utilize any number of roughing and turbo pump paths to pump down the main chamber 890.

[0077]

[0095] In some embodiments, the system 800 may include a central manifold box 850 where all the roughing lines (e.g., load lock roughing line 816 and main chamber roughing line 896) and all the pumping lines (e.g., load lock turbo pump line 817 and main chamber turbo pump line 897) are grouped together. The central manifold box 850 may house multiple valves for controlling the vacuum process. For example, the central manifold box 850 may include a load lock roughing valve 853, a main chamber roughing valve 854, a load lock turbo pump backing valve 851, and a main chamber turbo pump backing valve 852. After these individual valves, all the lines are coupled to a front line 858. Final evacuation via a dry vacuum pump 860 is controlled by a front line valve 859, which may be located before the dry vacuum pump 860.

[0078]

[0096] As described in the previous section with respect to FIG. 3A, in some embodiments, during the wafer temperature conditioning process, the load lock chamber 810 may be continuously pumped down via roughing line 816 or turbo pump 815 to continuously remove a portion of the gas molecules (e.g., gas 338 in FIG. 3A) and maintain the vacuum level in the load lock chamber 810 until wafer conditioning is complete.

[0079]

[0097] 8B, in some embodiments, this continuous pump-down of the loadlock chamber 810 may introduce a temporary pressure jump in the shared front line (e.g., front line 858) that may interrupt the inspection process in the main chamber 890. For example, as described in the previous section, a wafer temperature conditioning process may be performed in the loadlock chamber 810 at the same time that the previous wafer is being inspected in the main chamber 890. However, opening the loadlock roughing valve 853 to start the continuous pump-down process may cause a high pressure inside the front line 858 because the high pressure condition in the loadlock chamber 810 is exposed to the front line 858 due to the open connection established through the loadlock roughing line 816. The increased pressure in the front line 858 may create a higher back pressure for the main chamber turbo pump 895. In some embodiments, the sudden increase in back pressure may affect the dynamic behavior of the turbo pump 895 since the main chamber turbo pump 895 may be simultaneously operating to maintain a low pressure level in the main chamber during inspection of the previous wafer while wafer temperature conditioning is taking place in the load lock chamber 810. As a result, sudden vibrations may occur in the system 800. This sudden vibration may cause inspection errors. Therefore, if the vibration level is higher than the margin of inspection error, it may be necessary to interrupt the inspection process until the back pressure is removed and the vibrations subside. This interruption in the inspection process may impair the throughput of the system. The increased back pressure may also reduce the effective pumping speed of the turbo pump 895, which may cause a temporary increase in pressure in the main chamber 890. This temporary increase in main chamber pressure may also affect the throughput of the system and the overall system performance. These effects are described in more detail in the next section with respect to FIG. 9.

[0080]

[0098] 9, which is an exemplary graph illustrating the change in pressure in a main chamber (e.g., main chamber 890 of FIGS. 8A and 8B) of a charged particle beam inspection system (e.g., charged particle beam inspection system 800 of FIGS. 8A and 8B). As described above with respect to FIG. 8A, the main chamber is pumped down over two stages, a roughing stage 911 and a turbo pump-down stage 912. During the roughing stage 911, the main chamber is pumped down from atmospheric conditions to a "rough" vacuum level 910 (e.g., 5×10 -1 After the main chamber pressure reaches the "rough" vacuum level 910, the roughing valve (e.g., main chamber roughing valve 854 in FIG. 8A) is closed and the main chamber turbo pump (e.g., main chamber turbo pump 895) takes over to further reduce the main chamber pressure to a deeper vacuum level. When the main chamber pressure reaches the "ready to test" vacuum level 920 (e.g., 1.5×10 -6 Torr), the wafer inspection process can begin. In some embodiments, the main chamber turbo pump 895 may continue to operate to maintain the main chamber pressure level near the "ready for inspection" level 920.

[0081]

[0099] Once inspection of the first wafer is complete, in some embodiments, a wafer exchange may occur in period 923. During wafer exchange, the main chamber pressure may temporarily increase because a gate valve (e.g., gate valve 26 in FIG. 1B) between the load lock chamber (e.g., load lock chamber 810 in FIG. 8A) and the main chamber (e.g., main chamber 890 in FIG. 8A) is opened. After wafer exchange, the inspection process may resume once the main chamber turbo pump returns the main chamber pressure to the "ready for inspection" vacuum level 920.

[0082]

[0100] Prior to wafer swap, a second wafer may be subjected to a wafer temperature conditioning process while the first wafer is being inspected in the main chamber, and as described above, the main chamber pressure may temporarily increase due to back pressure applied to the main chamber turbo pump. An example of a temporary pressure jump 950 is shown in the graph.

[0083]

[0101] If the temporary pressure jump 950 is still below the "ready to test" vacuum level 920, then testing of the first wafer can continue without interruption as long as the vibration level remains within the margin of error. However, if the main chamber pressure rises above the "ready to test" vacuum level 920 during the temporary jump 950, then testing of the first wafer may need to be interrupted until the main chamber pressure returns to the "ready to test" level. As a result, system throughput may be affected by this interruption.

[0084]

[0102] 10, which illustrates a schematic diagram of an exemplary charged particle beam inspection system 1000 with an improved vacuum pumping system consistent with embodiments of the present disclosure. In some embodiments, a separate pumping path may be added to the load lock chamber 810 to prevent vibrations and pressure jumps in the main chamber 890. For example, in some embodiments, the charged particle beam inspection system 1000 may include a load lock booster roughing valve 1010, a load lock booster roughing pump 1011, and an auxiliary pumping system 1012. All other parts of the system 1000 are the same as the system 800 of FIG. 8A.

[0085]

[0103] In such an embodiment, during wafer temperature conditioning, the loadlock booster roughing pump 1011 may operate continuously to remove gas molecules (e.g., gas 338 in FIG. 3A). However, because the loadlock roughing valve 853 and the loadlock turbo pump backing valve 851 remain closed during this period, there may be no pressure build-up in the front line 858 and therefore no back pressure on the main chamber turbo pump 895.

[0086]

[0104] Thus, in some embodiments, the pump-down process for the loadlock chamber 810 can be broken down into three stages. First, the loadlock booster roughing pump 1011 may operate from atmospheric conditions to vacuum level for wafer temperature conditioning (after receiving a new set of wafers from the EFEM (e.g., EFEM 30 of FIG. 1A)). Second, the regular loadlock roughing path (via the loadlock roughing line 816) may operate from the wafer temperature conditioning vacuum level to a "coarse" vacuum level. Finally, the loadlock turbo pump 815 may operate from the "coarse" vacuum level to a deeper vacuum level. When starting pumping near atmospheric conditions, the backpressure problem is greatest when the front line 858 is exposed to the viscous region. As a result, after the loadlock chamber pressure level has been pumped down to the wafer temperature regulation vacuum level by a separate booster pump (e.g., loadlock booster roughing pump 1011), the regular pumping mechanism (e.g., loadlock roughing line 816 or loadlock turbo pump 815) can be used without creating excessive backpressure.

[0087]

[0105] 11, which is a flow diagram illustrating an exemplary method for controlling a vacuum level of a load lock chamber of the charged particle beam inspection system of FIG. 10, consistent with an embodiment of the present disclosure, that may be implemented by the charged particle beam inspection system of FIG.

[0088]

[0106] In step 1110, a wafer (or multiple wafers) is loaded into a load lock chamber (eg, load lock chamber 810 in FIG. 10) by a robot arm (eg, robot arm 11 in FIG. 1B).

[0089]

[0107] In step 1111, a gas supply (eg, gas supply 811 in FIG. 10) begins supplying gas (eg, gas 338 in FIG. 3A) to the load lock chamber for wafer temperature regulation.

[0090]

[0108] In step 1112, all gates (e.g., gate valves 25 and 26 in FIG. 1B) are closed in preparation for the evacuation process. In some embodiments, step 1111 may be performed after all gates have been closed in step 1112.

[0091]

[0109] In step 1113, the booster pump valve (e.g., load lock booster roughing valve 1010) is opened and the booster pump (e.g., load lock booster roughing pump 1011) begins pumping down the load lock chamber. As described above with respect to FIG. 10, in this first phase, the load lock chamber is pumped down from atmospheric conditions to a vacuum level suitable for wafer temperature regulation. Because the booster pump line is connected to a separate exhaust system (e.g., auxiliary exhaust system 1012 in FIG. 10) and is not coupled to the regular roughing path to form a shared front line (e.g., front line 858 in FIG. 10) in a manifold box (e.g., central manifold box 850 in FIG. 10), the booster pumping does not cause back pressure in the front line. Thus, the throughput of the system may not be affected.

[0092]

[0110] In step 1114, the wafer conditioning flow begins. This step may include adjusting the heating temperature of the conditioning plate (e.g., conditioning plate 315 of FIG. 3A) based on the determined temperature of the wafer stage (e.g., wafer stage 395 of FIG. 3A) in the main chamber (e.g., main chamber 890 of FIG. 10). While the wafer temperature conditioning is taking place, the booster pump continues to operate to maintain a suitable vacuum level for the wafer temperature conditioning. In step 1115, the wafer temperature is adjusted to a stable temperature (e.g., T stable ) is reached, the adjustment process is complete.

[0093]

[0111] In step 1116, after wafer temperature conditioning is completed, the gas vent valves (e.g., gas vent valves 812 in FIG. 10) are closed and the gas supplies are turned off. In step 1117, the first stage of the pump-down process is completed and the booster valves (e.g., load lock booster roughing valve 1010) are closed.

[0094]

[0112] In step 1118, the second phase of the pump-down process begins by opening the loadlock roughing valve (e.g., loadlock roughing valve 853 in FIG. 10). During this second phase, in some embodiments, the loadlock chamber is pumped from the wafer regulated vacuum level to a "rough" vacuum level (e.g., 5×10 -1 After the "rough" vacuum level is reached, in step 1119, the loadlock roughing valve is closed.

[0095]

[0113] In step 1120, the third stage of the pump-down process begins, where a turbo pump (eg, the load lock turbo pump 815) takes over to pump the load lock chamber 810 to a deeper vacuum level that is close to the main chamber pressure.

[0096]

[0114] In step 1121, after wafer inspection of the previous wafer is completed, the previous wafer is removed from the main chamber and the temperature conditioned wafer is transferred from the load lock chamber to the main chamber. In step 1122, once wafer exchange is complete, the load lock turbo pump valve is closed.

[0097]

[0115] After step 1122, step 1110 may be performed to load a new set of wafers into the load lock chamber. If there are still unconditioned and uninspected wafers in the load lock chamber, the system may proceed to step 1111 to condition another wafer in preparation for the inspection process.

[0098]

[0116] It will be appreciated that the controller of the wafer conditioning system can use software to control the above-mentioned functions. For example, the controller can send instructions to the valves and pumps mentioned above to control the pump-down path. The software may be stored on a non-transitory computer-readable medium. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid state drives, magnetic tapes or any other magnetic data storage media, CD-ROMs, any other optical data storage media, any physical media with a pattern of holes, RAM, PROMs, and EPROMs, cloud storage, FLASH-EPROMs or any other flash memory, NVRAMs, caches, registers, any other memory chips or cartridges, and networked versions of the above.

[0099]

[0117] The embodiments may be further described using the following clauses. Clause 1. A load lock system comprising: a plurality of support structures configured to support the wafer; a first adjusting plate including a first heat exchange element configured to adjust a temperature of the wafer; a first gas vent configured to supply gas between the first adjusting plate and the wafer; A load lock system comprising: a controller including a processor and a memory, the controller configured to assist in controlling the first heat exchange element. Clause 2. The load lock system of clause 1, wherein the first adjusting plate is positioned above the wafer. Clause 3. The load lock system of clause 1, wherein the first adjusting plate is positioned below the wafer. Clause 4. The load lock system of clause 3, wherein the plurality of support structures are coupled to the first adjustment plate. Clause 5. A load lock system as described in any one of clauses 1 to 4, wherein the first gas vent is attached to the first adjustment plate. Clause 6. A load lock system as described in any one of clauses 1 to 5, wherein the controller is further configured to assist in control of the first heat exchange element based on the temperature of the wafer stage. Clause 7. A load lock system as described in any one of clauses 1 to 6, wherein the controller is further configured to control a gas flow rate through the first gas vent. Clause 8. The load lock system of any one of clauses 1 to 7, further comprising a second adjusting plate including a second heat exchange element configured to adjust the temperature of the wafer. Clause 9. The load lock system of clause 8, wherein a plurality of support structures configured to support a wafer are disposed between the first and second adjusting plates. Clause 10. The load lock system of clause 9, further comprising a second gas vent configured to supply a portion of the gas between the second adjusting plate and the wafer. Clause 11. The load lock system of clause 10, wherein the second gas vent is coupled to the second adjustment plate. Clause 12. A load lock system as described in any one of clauses 8 to 11, wherein the controller is further configured to assist in control of the second heat exchange element based on the temperature of the wafer stage. Clause 13. A load lock system according to any one of clauses 10 to 12, wherein the controller is further configured to control a gas flow rate through the second gas vent. Clause 14. A load lock system according to any one of clauses 1 to 13, wherein the gas comprises nitrogen, helium, hydrogen, argon, CO2, or compressed air. Clause 15. The load lock system of any one of clauses 1-14, further comprising a load lock chamber configured to enclose the first adjusting plate, the plurality of support structures, and the wafer. Clause 16. The load lock system of clause 15, further comprising a first vacuum pump connected to the load lock chamber. Clause 17. The load lock system of clause 16, wherein the controller is further configured to control the first vacuum pump to pump out gas during a wafer conditioning process. Clause 18. The load lock system of clause 17, wherein the controller is further configured to maintain a pressure within the load lock chamber within a range of 50 to 5,000 Pa during the wafer conditioning process. Clause 19. The load lock system of any one of clauses 16 to 18, further comprising a second vacuum pump connected to the load lock chamber. Article 20. The Controller further: enabling a first vacuum pump to reduce pressure within the load lock chamber to a first pressure level; 20. The load lock system of claim 19, wherein a second vacuum pump is configured to enable a pressure inside the load lock chamber to be reduced to a second pressure level, the second pressure level being lower than the first pressure level. Clause 21. The load lock system of clause 20, wherein the second vacuum pump shares an exhaust path with a third vacuum pump connected to the main chamber. Clause 22. A load lock system as described in any one of clauses 20 and 21, wherein the second vacuum pump is disabled while the first vacuum pump is enabled. Clause 23. The load lock system of any one of clauses 20 to 22, wherein the first vacuum pump and the third vacuum pump are enabled simultaneously. Clause 24. A method for thermal conditioning a wafer in a load lock system, comprising: loading a wafer into a load lock chamber of a load lock system; Pumping down the load lock chamber; Supplying gas to a load lock chamber; and allowing a first heat exchange element in the first conditioning plate to adjust a temperature of the first conditioning plate to transfer heat to the wafer via the gas. Clause 25. The method of clause 24, wherein supplying the gas to the load lock chamber further comprises adjusting a temperature of the gas prior to supplying the gas to the load lock chamber. Clause 26. The method of any one of clauses 24 and 25, wherein supplying gas to the load lock chamber further comprises supplying gas to a space between the first adjusting plate and the wafer. Clause 27. The method of any one of clauses 24-26, further comprising determining a temperature of a wafer stage within the main chamber. Clause 28. The method of any one of clauses 24 to 27, wherein enabling the first heat exchange element to adjust the temperature of the first adjusting plate further comprises adjusting the first heat exchange element based on the determined temperature of the wafer stage. Clause 29. The method of any one of clauses 24 to 28, further comprising: a second heat exchange element in the second adjusting plate capable of adjusting the temperature of the second adjusting plate to transfer heat to the wafer via the gas. Clause 30. The method of any one of clauses 24 to 29, wherein the gas comprises nitrogen, helium, hydrogen, argon, CO2, or compressed air. Clause 31. The method of any one of clauses 24-30, wherein pumping down the load lock chamber includes evacuating gas from the load lock chamber using a first vacuum pump connected to the load lock chamber. Clause 32. Pumping down the load lock chamber further comprises: enabling a first vacuum pump to reduce pressure within the load lock chamber to a first pressure level; and enabling a second vacuum pump connected to the load lock chamber to reduce a pressure inside the load lock chamber to a second pressure level, the second pressure level being lower than the first pressure level. Clause 33. The method of clause 32, wherein the second vacuum pump shares an exhaust path with a third vacuum pump connected to the main chamber. Clause 34. The method of any one of clauses 32 and 33, wherein the second vacuum pump is disabled while the first vacuum pump is enabled. Clause 35. The method of any one of clauses 32 to 34, wherein the first vacuum pump and the third vacuum pump are enabled simultaneously. Clause 36. A non-transitory computer-readable medium, comprising a set of instructions executable by one or more processors of a controller to cause the controller to perform a method for thermally conditioning a wafer, the method comprising: directing a first vacuum pump to pump down a load lock chamber of the load lock system after the wafer is loaded into the load lock chamber; directing a gas supply to supply gas to the load lock chamber; and instructing a first heat exchange element in the first conditioning plate to adjust a temperature of the first conditioning plate to transfer heat to the wafer via the gas. Clause 37. The method may be executed by one or more processors of a controller, the controller further comprising: 37. The computer-readable medium of claim 36, wherein the set of instructions directs a temperature sensor to determine a temperature of a wafer stage within the main chamber. Clause 38. The computer-readable medium of clause 37, wherein instructing the first heat exchange element in the first adjusting plate further includes adjusting the first heat exchange element based on the determined temperature of the wafer stage. Clause 39. The method may be executed by one or more processors of a controller, the controller further comprising: The computer-readable medium of any one of clauses 36-38, wherein the set of instructions instructs a second heat exchange element in the second adjusting plate to adjust the temperature of the second adjusting plate to transfer heat to the wafer via the gas. Clause 40. The computer-readable medium of clause 39, wherein instructing the second heat exchange element in the second adjusting plate further includes adjusting the second heat exchange element based on the determined temperature of the wafer stage. Clause 41. The method may be executed by one or more processors of a controller, the controller further comprising: directing a first vacuum pump to pump down the load lock chamber to a first pressure level; The computer-readable medium of any one of clauses 36-40, further comprising a set of instructions for directing a second vacuum pump to pump down the load lock chamber to a second pressure level, the second pressure level being lower than the first pressure level. Clause 42. A method for pumping down a load lock chamber, comprising: evacuating gas from the load lock chamber using a first vacuum pump configured to evacuate the gas to a first exhaust system; and evacuating the gas from the load lock chamber using a second vacuum pump configured to evacuate the gas to a second exhaust system. Clause 43. enabling a first vacuum pump to reduce pressure within the load lock chamber to a first pressure level; 43. The method of claim 42, further comprising: enabling a second vacuum pump to reduce a pressure inside the load lock chamber to a second pressure level, the second pressure level being lower than the first pressure level. Clause 44. The method of clause 43, wherein the second vacuum pump shares a second exhaust system with a third vacuum pump configured to pump down the main chamber. Clause 45. The method of any one of clauses 42 to 44, wherein the second vacuum pump is disabled while the first vacuum pump is enabled. Clause 46. The method of any one of clauses 44-45, wherein the first vacuum pump and the third vacuum pump are enabled simultaneously.

[0100]

[0118] Although the disclosed embodiments have been described in connection with preferred embodiments, it should be understood that other modifications and variations can be made without departing from the spirit and scope of the subject matter hereinafter claimed.

Claims

1. a plurality of support structures configured to support the wafer; a first conditioning plate including a first heat exchange element configured to condition a temperature of the wafer; a first gas vent configured to supply gas between the first adjusting plate and the wafer; a controller including a processor and a memory configured to facilitate controlling the first heat exchange element; A load lock system.

2. The load lock system of claim 1 , wherein the first adjusting plate is positioned above the wafer.

3. The load lock system of claim 1 , wherein the first adjusting plate is positioned below the wafer.

4. The load lock system of claim 1 , wherein the plurality of support structures are coupled to the first adjusting plate.

5. The load lock system of claim 1 , wherein the first gas vent is attached to the first adjusting plate.

6. The load lock system of claim 1 , wherein the controller is further configured to assist in the controlling of the first heat exchange element based on a temperature of a wafer stage.

7. 10. The load lock system of claim 1, further comprising a second conditioning plate including a second heat exchange element configured to condition the temperature of the wafer.

8. 8. The load lock system of claim 7, wherein the plurality of support structures configured to support a wafer are disposed between the first and second adjusting plates.

9. 8. The load lock system of claim 7, further comprising a second gas vent configured to provide a portion of the gas between the second adjusting plate and the wafer.

10. The load lock system of claim 7 , wherein the controller is further configured to assist in controlling the second heat exchange element based on a temperature of the wafer stage.

11. The load lock system of claim 1 , further comprising a load lock chamber configured to enclose the first adjusting plate, the plurality of support structures, and the wafer.

12. The load lock system of claim 11 further comprising a second vacuum pump connected to the load lock chamber.

13. The controller further comprises: enabling the first vacuum pump to reduce pressure within the load lock chamber to a first pressure level; 13. The load lock system of claim 12, wherein the second vacuum pump is configured to enable a pressure inside the load lock chamber to be reduced to a second pressure level, the second pressure level being lower than the first pressure level.

14. 14. The load lock system of claim 13, wherein the second vacuum pump shares an exhaust path with a third vacuum pump connected to a main chamber.

15. 1. A non-transitory computer readable medium comprising a set of instructions executable by one or more processors of a controller to cause the controller to perform a method for thermal conditioning a wafer, the method comprising: directing a first vacuum pump to pump down a load lock chamber of a load lock system after a wafer has been loaded into the load lock chamber; directing a gas supply to supply gas to the load lock chamber; directing a first heat exchange element in a first conditioning plate to adjust a temperature of the first conditioning plate to transfer heat to the wafer through the gas; A non-transitory computer readable medium comprising:

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