Reducing particle contamination of laser entrance windows in pulsed laser deposition tools

Abstract

One example provides a pulsed laser deposition (PLD) tool. The PLD tool includes a process chamber with a laser entrance window. The PLD tool further includes a target holder located within the process chamber. The PLD tool further includes a substrate holder located within the process chamber. The PLD tool further includes a laser configured to direct laser light through the laser entrance window and toward the target holder. The PLD tool further includes a purge gas inlet located between the laser entrance window and the target holder, the purge gas inlet configured to direct a flow of purge gas toward a path of the laser light.

Description

[Background technology]

[0001] Pulsed laser deposition (PLD) can be used in semiconductor device manufacturing to deposit films on substrates. PLD involves exposing a target material to pulsed laser energy. The laser energy ablates the target material to form a plasma plume. Material in the plasma plume is deposited on the substrate. Summary of the Invention

[0002] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Moreover, the claimed subject matter is not limited to implementations that solve any or all of the disadvantages noted in any part of this disclosure.

[0003] One example provides a pulsed laser deposition (PLD) tool. The PLD tool includes a process chamber with a laser entrance window. The PLD tool further includes a target holder located within the process chamber. The PLD tool further includes a substrate holder located within the process chamber. The PLD tool further includes a laser configured to direct laser light through the laser entrance window and toward the target holder. The PLD tool further includes a purge gas inlet located between the laser entrance window and the target holder. The purge gas inlet is configured to direct a flow of purge gas toward a path of the laser light.

[0004] In some such examples, the purge gas inlet is alternatively or additionally configured to direct a flow of purge gas through the path of the laser light and towards the barrier, and the barrier is configured to deflect the flow of purge gas back through the path of the laser light.

[0005] In some such examples, the PLD tool alternatively or additionally includes a sacrificial window located between the laser entrance window and the target holder.

[0006] In some such instances, the purge gas inlet is alternatively or additionally located closer to the sacrificial window than to the target holder.

[0007] In some such examples, the PLD tool alternatively or additionally comprises an orifice located along the path of the laser beam, the orifice having a periphery that substantially matches the periphery of the laser beam.

[0008] In some such instances, the purge gas inlet is alternatively or additionally located closer to the orifice than to the laser entrance window.

[0009] In some such examples, the PLD tool alternatively or additionally includes one or more optical elements that define a focal plane, and the orifice is located at the focal plane.

[0010] In some such instances, orifices are alternatively or additionally formed in the parasitic deposition shield.

[0011] In some such examples, the PLD tool alternatively or additionally includes a barrier configured to form a cavity around a path of the laser light. The orifice alternatively or additionally includes a first orifice located at a first end of the cavity. The purge gas inlet alternatively or additionally includes a second orifice located at a second end of the cavity.

[0012] In some such examples, the purge gas inlet is alternatively or additionally a first purge gas inlet located at a first location. The PLD tool alternatively or additionally includes a second purge gas inlet located at a second location between the laser entrance window and the target holder.

[0013] Another example provides a pulsed laser deposition (PLD) tool. The PLD tool includes a process chamber with a laser entrance window. The PLD tool further includes a target holder located within the process chamber. The PLD tool further includes a substrate holder located within the process chamber. The PLD tool further includes a laser configured to direct laser light through the laser entrance window and toward the target holder. The PLD tool further includes an orifice located along a path of the laser light. The orifice has an outer periphery that substantially matches the outer periphery of the laser light.

[0014] In some such examples, the PLD tool alternatively or additionally includes one or more optical elements that define a focal plane, and the orifice alternatively or additionally is located closer to the focal plane than to the laser entrance window.

[0015] In some such examples, the orifice is alternatively or additionally located in the focal plane.

[0016] In some such instances, the orifices are alternatively or additionally formed in a parasitic deposition shield comprising a sheet material.

[0017] In some such examples, the sheet material alternatively or additionally comprises aluminum or titanium.

[0018] In some such examples, the PLD tool alternatively or additionally includes a purge gas inlet located between the laser entrance window and the target holder, the purge gas inlet configured to direct a flow of purge gas into the path of the laser light.

[0019] In some such examples, the purge gas inlet is alternatively or additionally configured to direct a flow of purge gas through the path of the laser light and towards the barrier, and the barrier is configured to deflect the flow of purge gas back through the path of the laser light.

[0020] In some such instances, the purge gas inlet is alternatively or additionally located closer to the orifice than to the laser entrance window.

[0021] In some such examples, the PLD tool alternatively or additionally includes a sacrificial window located between the laser entrance window and the target holder, and the purge gas inlet alternatively or additionally is located closer to the sacrificial window than to the orifice.

[0022] Another example provides a method for creating a laser-formed orifice along the path of a laser beam in a processing chamber of a pulsed laser deposition (PLD) tool. The method includes positioning a parasitic deposition shield in the path of the laser beam in the processing chamber between a laser entrance window and a target holder. The method further includes ablating the parasitic deposition shield using the laser beam to form the laser-formed orifice.

[0023] In some such examples, placing the parasitic deposition shield in the path of the laser light in the processing chamber between the laser entrance window and the target holder alternatively or additionally includes placing the parasitic deposition shield in a focal plane of one or more optical elements used to focus the laser light.

[0024] In some such examples, placing the parasitic deposition shield in the path of the laser light in the processing chamber between the laser entrance window and the target holder alternatively or additionally includes placing an aluminum sheet in the path of the laser light in the processing chamber between the laser entrance window and the target holder. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram of an exemplary PLD tool.

[0026] [Figure 2] 10A and 10B are schematic diagrams illustrating an exemplary purge gas inlet including a barrier that deflects the flow of purge gas back through the path of the laser light.

[0027] [Figure 3] FIG. 10 is a schematic diagram of another exemplary purge gas inlet configured to output a flow of purge gas diagonal to the path of the laser light.

[0028] [Figure 4] FIG. 2 is a schematic diagram illustrating an exemplary orifice in a parasitic deposition shield.

[0029] [Figure 5] FIG. 10 is a schematic diagram of an exemplary barrier configured as a cavity with an orifice at each end.

[0030] [Figure 6A]1A-1C are schematic diagrams illustrating an example of creating orifices in a parasitic deposition shield by laser ablation. [Figure 6B] 1A-1C are schematic diagrams illustrating an example of creating orifices in a parasitic deposition shield by laser ablation. [Figure 6C] 1A-1C are schematic diagrams illustrating an example of creating orifices in a parasitic deposition shield by laser ablation.

[0031] [Figure 7] 1 is a flow chart illustrating an exemplary method for creating an orifice in a parasitic deposition shield. DETAILED DESCRIPTION OF THE INVENTION

[0032] The terms "ablation," "laser ablation," and variations thereof generally refer to the removal of material from a target using laser energy. Material removed from a target by laser ablation can be deposited on a substrate to form a film.

[0033] The term "barrier" generally refers to a structure in a processing chamber configured to deflect the incoming flow of purge gas toward the laser light path.

[0034] The term "focal plane" generally refers to a plane oriented perpendicular to the optical axis of an optical system that is located at the focal point of the optical elements of the optical system.

[0035] The term "laser entrance window" generally refers to a structure that forms part of a wall of a pulsed laser deposition (PLD) processing chamber through which laser light enters the processing chamber.

[0036] The term "optical element" generally refers to a structure configured to modify the properties or path of light (in some examples, laser light). Exemplary optical elements include refractive and diffractive lenses and mirrors.

[0037] The term "orifice" generally refers to an opening. For example, an orifice can be an opening formed in a parasitic deposition shield that allows laser light to pass through. The term "substantially matches" in relation to the comparison of the circumference of an orifice to the circumference of a laser beam generally refers to a difference between the diameter of the laser beam and the diameter of the orifice of 1 percent or less.

[0038] The term "particle" generally refers to a cluster of atoms, for example, with a dimension greater than 5 nm. Some particles in pulsed laser deposition may have a diameter greater than 100 nm.

[0039] The term "parasitic deposition shield" generally refers to a structure within a processing chamber that includes an orifice to allow laser light to pass through. Areas of the parasitic deposition shield other than the orifice help block particles generated during the PLD process from reaching the laser entrance window.

[0040] The term "processing chamber" generally refers to an enclosure in which chemical and / or physical processes are performed on a substrate. For example, pulsed laser deposition (PLD) processes are performed in processing chambers.

[0041] The terms "pulsed laser deposition" and "PLD" generally refer to a physical deposition process in which material is ablated from a target by the application of pulsed laser energy. At least a portion of the target material ablated by the laser adsorbs onto a substrate, forming a film on the substrate.

[0042] The term "PLD tool" generally refers to a machine that includes a processing chamber and other hardware configured to allow PLD processing to occur in the processing chamber.

[0043] The term "purge gas" generally refers to a gas used to remove other gases from a space (such as from a portion of a processing chamber). Examples of purge gases include nitrogen, argon, helium, neon, krypton, and xenon.

[0044] The term "purge gas inlet" generally refers to a structure configured to direct a flow of purge gas into a space.

[0045] The term "sacrificial window" generally refers to a structure in a processing chamber through which laser light passes. The sacrificial window is generally located in the processing chamber between the laser entrance window and the target. The sacrificial window blocks some particles generated during the PLD process from reaching the laser entrance window. The term "substrate" generally refers to any object onto which a film can be deposited.

[0046] The term "substrate holder" generally refers to a structure for supporting a substrate in a processing chamber.

[0047] The term "target" generally refers to a solid mass of material to be deposited on a substrate in a deposition process. The target is ablated by laser light to form a plasma plume. Chemical species in the plasma plume deposit on the substrate.

[0048] The term "target holder" generally refers to any structure for supporting a target in a processing chamber.

[0049] As previously mentioned, pulsed laser deposition (PLD) involves using a pulsed laser to remove material from a target and deposit the removed material onto a substrate. The removal of material from a target using a laser is sometimes referred to as ablation. The laser forms a plasma plume containing the material removed from the target. The material in the plasma plume is deposited onto the substrate, forming a film on the substrate.

[0050] However, pulsed lasers also create particles that are emitted from the target. These particles can include atoms, molecules, clusters of atoms, larger particles (e.g., larger than 100 nm), and / or any combination thereof. The pulsed laser enters the processing chamber through a laser entrance window. Some of the particles created by the laser ablation process can reach and deposit on the laser entrance window. Over time, particle deposition on the laser entrance window can reduce laser light transmission through the laser entrance window.

[0051] To prevent particle buildup on the laser entrance window from adversely affecting PLD tool performance, the laser entrance window is periodically cleaned or replaced, resulting in tool downtime and associated costs.

[0052] Some PLD tools include a sacrificial window positioned between the laser entrance window and the target. The sacrificial window blocks some particles from reaching the laser entrance window. The sacrificial window may be designed to be rotatable or optionally movable to expose different portions of the sacrificial window to laser light and particle contaminants. When particulate buildup on the currently exposed portion of the sacrificial window begins to adversely affect the PLD process, the sacrificial window may be rotated or optionally moved to expose a different portion of the sacrificial window to laser light and block particle contaminants from the target. In some embodiments, the sacrificial window may be replaced after all portions of the sacrificial window are coated with particle contaminants, thus reducing the transmission of laser light through the sacrificial window below a desired limit.

[0053] Although the use of a sacrificial window can increase the number of PLD processes performed between laser entrance window cleanings, some particles still reach the laser entrance window. Therefore, examples are disclosed relating to reducing particle contamination on the laser entrance window of a PLD tool. In some embodiments, a purge gas inlet is disposed in the processing chamber between the laser entrance window and the target holder to direct a flow of purge gas into the path of the laser light. The flow of purge gas diverts particles from the target away from the laser entrance window. This can reduce the number of particles that reach the laser entrance window during the deposition process. As a result, the frequency of laser entrance window cleanings can be reduced.

[0054] In some embodiments, the PLD tool includes an orifice formed in a parasitic deposition shield located along the path of the laser light. In some embodiments, the orifice is formed by the laser light. Such an orifice may be referred to as a laser-formed orifice. The laser-formed orifice has an outer periphery that substantially matches the outer periphery of the laser light (e.g., the diameter of the laser light beam). The area of ​​the parasitic deposition shield other than the orifice helps block particles generated during the PLD process from reaching the laser entrance window. Again, this can allow the frequency of laser entrance window cleaning to be reduced. In some embodiments, the PLD tool relies solely on the laser-formed orifice to block particles from the laser entrance window. In other words, a sacrificial window and a purge gas inlet are not incorporated. In some embodiments, the laser-formed orifice is used in combination with a sacrificial window and / or a purge gas inlet feature.

[0055] 1 shows a schematic diagram of an exemplary PLD tool 100. The PLD tool 100 includes a process chamber 102 for performing a PLD process on a substrate. A target holder 104 and a substrate holder 106 are located within the process chamber 102. A target 108 is disposed on the target holder 104 during the PLD process. Furthermore, a substrate 110 is disposed on the substrate holder 106.

[0056] PLD tool 100 further includes a laser 112 configured to direct laser light 114 through a laser entrance window 116 of processing chamber 102 and toward target holder 104. One or more optical elements 118 (shown here as a single component) may be used to focus laser light 114 to reduce the spot size of laser light 114 on target 108.

[0057] During the PLD process, the laser light 114 generates a plasma plume 120 and particles from the target 108. A filter 122 passes the plasma plume 120 toward the substrate 110 while blocking some particles from reaching the substrate 110. Chemical species in the plasma plume 120 deposit as a film on the substrate 110. In some examples, the filter 122 rotates synchronously with the laser pulse. Because the particles travel slower than the plasma plume 120, an opening in the filter 122 can rotate during laser irradiation to a location between the laser spot on the target 108 and the substrate 110. In this way, the opening in the filter 122 allows the plasma plume 120 to pass. The opening in the filter 122 then rotates away to block at least some of the slower-moving particles.

[0058] The substrate holder 106 can be configured to move during the PLD process to expose multiple portions across the substrate 110 to the plasma plume 120. The PLD tool 100 further includes a heater 124 disposed on the substrate holder 106. The heater 124 is used to control the temperature of the substrate 110.

[0059] Particles from the target 108 may travel throughout the processing chamber 102. Some particles may reach the laser entrance window 116, thereby contaminating the laser entrance window 116. Particle contamination may reduce the laser power reaching the target, which may affect deposition efficiency and consistency. Cleaning the laser entrance window 116 may also involve breaking the system vacuum, which results in tool downtime. Therefore, in some embodiments, the PLD tool 100 further includes a sacrificial window 126 to help reduce particles from reaching the laser entrance window 116. As shown, the sacrificial window 126 is located between the laser entrance window 116 and the target holder 104. The sacrificial window 126 may be rotatable or, in some cases, movable. As a specific example, the sacrificial window 126 may include multiple indexes, each representing a different location on the sacrificial window 126. When a first location of the sacrificial window 126 reaches a threshold use condition, the sacrificial window 126 is moved to a next index to advance a clean location on the sacrificial window 126 into the path of the laser light 114. In that way, multiple clean locations of the sacrificial window 126 can be exposed in the processing chamber 102 before replacing the sacrificial window 126. This can help reduce the frequency at which the sacrificial window is changed. In other examples, the sacrificial window 126 can be configured as a fixed window. In a further example, a PLD may omit the sacrificial window 126.

[0060] The PLD tool 100 further includes a first purge gas inlet 128 configured to direct a flow of purge gas toward the path of the laser beam 114. The flow of purge gas can be continuous or pulsed. In some examples, the flow of purge gas can be in the range of 10 to 25 sccm (standard cubic centimeters per minute). As shown, the first purge gas inlet 128 is located closer to the sacrificial window 126 than to the target holder 104. Such a configuration helps reduce particles from reaching the sacrificial window 126. In other examples, the first purge gas inlet 128 can be located in any other suitable location between the laser entrance window 116 and the target holder 104. In further examples, the first purge gas inlet 128 can be omitted.

[0061] The PLD tool 100 further includes an orifice 130 located along the path of the laser beam 114. As shown, the orifice 130 is formed in a parasitic deposition shield 132. The parasitic deposition shield 132 helps block particles traveling toward the laser entrance window 116. The orifice 130 provides an opening in the parasitic deposition shield 132 through which the laser beam 114 can pass. In some examples, the orifice 130 can be formed by ablating the parasitic deposition shield 132 with the laser beam 114 (e.g., a laser-formed orifice), as described below. This can help form an orifice with an outer perimeter that substantially matches the outer perimeter of the laser beam 114. Such a configuration presents a narrower path for particles to reach the laser entrance window 116 compared to an orifice with an outer perimeter larger than the outer perimeter of the laser beam 114.

[0062] The parasitic deposition shield 132 may be formed from a material that is compatible with the PLD process being performed in the PLD tool 100. Examples of materials suitable for use as the parasitic deposition shield 132 include aluminum, stainless steel, titanium, and semiconductors such as silicon. As a more specific example, the parasitic deposition shield 132 may include an aluminum sheet, such as an aluminum foil or an aluminum plate. Such a parasitic deposition shield 132 may be suitable for use in a PLD chamber used to deposit aluminum-containing films, such as aluminum nitride or aluminum oxide.

[0063] In the illustrated example, orifice 130 is located at a focal plane defined by one or more optical elements 118. In such a configuration, a smaller orifice may be used than an orifice at a different location along the path of laser light 114. Additionally, in such a location, orifice 130 may be used as an optical spatial filter. In other examples, orifice 130 may be located closer to the focal plane than to laser entrance window 116.

[0064] In some examples, a pressure differential can be created across the parasitic deposition shield 132 and the orifice 130 using a flow of purge gas. More specifically, a higher pressure region can be created in the processing chamber 102 between the orifice 130 and the laser entrance window 116. In some such examples, the higher pressure region can be formed by directing a flow of purge gas into a cavity comprising the orifice 130 on a first end and a second orifice on a second end. The higher pressure region can help increase the drag force on particles between the laser entrance window 116 and the orifice 130. Furthermore, the higher pressure region can have a directional flow toward the plasma plume 120. Thus, the higher pressure region can help reduce particles reaching the laser entrance window 116. In other examples, the PLD tool 100 may omit the parasitic deposition shield 132.

[0065] In some examples, the PLD tool can have a single purge gas inlet along the path of the laser beam between the laser entrance window and the target holder. In other examples, the PLD tool can have two or more purge gas inlets. FIG. 1 shows an optional second purge gas inlet 134 located along the path of the laser beam 114. The second purge gas inlet 134 is located closer to the orifice 130 than to the laser entrance window 116. Similar to the first purge gas inlet 128, the second purge gas inlet 134 is configured to direct a flow of purge gas toward the path of the laser beam 114. In that way, some particles from the plasma plume 120 can be deflected away from the direction toward the laser entrance window 116. In other examples, the second purge gas inlet 134 can be located in any other suitable location between the laser entrance window 116 and the target holder 104. In further examples, the PLD tool 100 may omit the second purge gas inlet 134. In yet a further example, PLD tool 100 may include three or more purge gas inlets located along the path of laser beam 114 .

[0066] The first purge gas inlet 128 and the second purge gas inlet 134 are configured to receive a flow of purge gas from a purge gas source 136. In some embodiments, more than two purge gas inlets may be provided. In some embodiments, different gas inlets may receive purge gas from different gas sources. Additionally, the PLD tool may also be configured to receive a flow of process gas from a process gas source 138 during the PLD process. In some examples, the process gas includes nitrogen. In other examples, the process gas may alternatively or additionally include argon, helium, neon, krypton, xenon, and / or other suitably inert gases. The PLD tool 100 further includes an exhaust system 140 configured to draw gas from within the process chamber 102. The process gas source 138, the purge gas source 136, and the exhaust system 140 may be controlled to maintain a desired pressure within the process chamber 102 during the PLD process. In some examples, the pressure of the process chamber 102 may be maintained at a pressure within a range of 0.01 to 0.1 millibars. In other instances, pressures outside this range may be used.

[0067] The PLD tool 100 further comprises a controller 142 configured to control components of the PLD tool 100. For example, the controller 142 controls the flow of purge gas to the first purge gas inlet 128 and / or the second purge gas inlet 134. In some examples, the controller 142 can pulse the flow of purge gas to the first purge gas inlet 128 and / or the second purge gas inlet 134 in synchronization with the pulses of the laser 112. The controller is further connected to the sacrificial window 126. Accordingly, the controller 142 can be configured to advance the sacrificial window 126 to a clean position when its current position becomes optically degraded due to particle contamination. The controller 142 is further configured to control the laser 112, the exhaust system 140, the substrate holder 106, the heater 124, and other suitable components of the PLD tool 100.

[0068] In the above example, the purge gas inlet directs a flow of purge gas into the path of the laser light to help prevent particles from reaching the laser entrance window 116. In such a configuration, the purge gas is exhausted after a single pass through the laser light. In other examples, a barrier may be used to deflect the purge gas so that it passes through the laser light again. FIG. 2 schematically illustrates an exemplary purge gas inlet 200 utilizing a barrier. The purge gas inlet 200 is an example of the first purge gas inlet 128. As previously described, the laser light 202 is directed through the laser entrance window 204 and the sacrificial window 206 toward the target holder (not shown). As shown, the purge gas inlet 200 is configured to direct a flow of purge gas 208 through the path of the laser light 202 and toward the surface of the barrier 210. The barrier 210 is configured to deflect the flow of purge gas 208 so that at least a portion of the purge gas passes through the path of the laser light 202 again. The second surface of the barrier 210 can further deflect the flow of the purge gas 208 back through the path of the laser light 202. In this way, a localized region of gas pressure relatively higher than the overall pressure in the processing chamber is created between the first and second surfaces of the barrier 210. The localized region of relatively higher gas pressure can help increase the probability that purge gas atoms or molecules will encounter particles from the target. This can help reduce the number of particles reaching the laser entrance window 204 and the sacrificial window 206. In some examples, the barrier 210 can form a housing for the sacrificial window 206. The barrier 210 can have any suitable shape. Examples include a volume of space, or an open-ended cylinder or other shape that partially encloses a wall. In some examples, more than one barrier can be used. In further examples, the sacrificial window 206 can be omitted.

[0069] In some examples, the flow of purge gas can alternatively or additionally have a direction diagonal to the path of the laser light. FIG. 3 schematically illustrates an exemplary purge gas inlet 300 configured to direct the flow of purge gas 302 diagonally relative to the direction of laser light 304. The purge gas inlet 300 is an example of the first purge gas inlet 128. As previously described, the laser light 304 is directed toward the target holder (not shown) through a laser entrance window 306 and a sacrificial window 308. Here, the purge gas inlet 300 is positioned to direct the flow of purge gas 302 in a downstream diagonal direction relative to the path of the laser light 304. The term “downstream” indicates that the purge gas flow path has a directional component along the direction of the laser light. Such a configuration helps to divert particles away from the sacrificial window 308. In other examples, the flow of purge gas can be directed diagonally upstream. The term “upstream” indicates that the purge gas flow has a directional component opposite to the direction of the laser light. 3 shows a single purge gas inlet, other examples may use any suitable number of purge gas inlets configured in any suitable manner as described herein, and in still other examples, the sacrificial window 308 may be omitted.

[0070] In the above example, the purge gas inlet is used to divert particles away from the sacrificial window. In other examples, a parasitic deposition shield with an orifice may alternatively or additionally be used to help prevent particles from reaching the laser entrance window. FIG. 4 shows an exemplary orifice 400 formed in a parasitic deposition shield 401. The orifice 400 is an example of the orifice 130 in FIG. 1. As previously mentioned, a lens 402 or other optical element(s) may be used to focus the laser light, which strikes the target 404 and generates the plasma plume 406. The parasitic deposition shield 401 helps block particles from the target 404 traveling toward the laser entrance window 410. The orifice 400 allows the laser light to pass through the parasitic deposition shield 401.

[0071] In some examples, the parasitic deposition shield 401 can be machined to form the orifice 400. In other examples, the orifice 400 is formed in the parasitic deposition shield 401 by ablating the parasitic deposition shield 401 with a laser beam (e.g., a laser-formed orifice). This allows the outer periphery of the orifice 400 to match the outer periphery of the laser beam. Such an orifice can provide a smaller opening for particles to pass through than a machined orifice with a larger diameter. Furthermore, the laser-formed orifice can be formed by ablation with the parasitic deposition shield 401 installed in the processing chamber so that the position of the orifice does not need to be aligned with the laser beam after the orifice is formed. As shown, the parasitic deposition shield 401 is located in a focal plane defined by the lens 402. When the parasitic deposition shield is located in the focal plane, a smaller orifice can be created than in a parasitic deposition shield that is not located in the focal plane. Thus, an orifice formed in the focal plane provides a smaller opening for particles to pass through at the optimum laser approach angle than a machined orifice with a larger perimeter.

[0072] As previously mentioned, a region of higher pressure can be created in a processing chamber by directing a flow of purge gas into the cavity. FIG. 5 schematically illustrates an exemplary barrier 500 that forms a cavity 502 around the path of a laser beam 504. As shown, a first orifice 506 is located at a first end of the cavity 502. The first orifice 506 is an example of the orifice 130 of FIG. 1 . Similarly, a second orifice 508 is located at a second end of the cavity 502. One or both of the first orifice 506 and the second orifice 508 can have an outer perimeter that substantially matches the outer perimeter of the laser beam 504. In other examples, the outer perimeter of one or both of the first orifice 506 and the second orifice 508 can be larger than the outer perimeter of the laser beam 504.

[0073] A purge gas inlet 510 is configured to direct a flow of purge gas 512 toward the path of the laser beam 504. As shown, a barrier 500 deflects the flow of purge gas 512 so that at least a portion of the purge gas passes back through the path of the laser beam 504. In that manner, a region of higher pressure can be formed in the cavity 502. The region of higher pressure can help increase the probability that purge gas atoms or molecules will collide with particles from the target. In other examples, any suitable number of purge gas inlets can be configured to direct a flow of purge gas into the cavity in any suitable manner disclosed herein.

[0074] FIGS. 6A, 6B, and 6C schematically illustrate the creation of an exemplary laser-formed orifice 600 using a laser in a PLD tool by laser ablation of a parasitic deposition shield. The orifice 600 is an example of the orifice 130. FIG. 6A schematically illustrates an optical element 602 and a parasitic deposition shield 604A of a PLD tool. Other components of the PLD tool are omitted for clarity. As shown, the parasitic deposition shield 604A is a new parasitic deposition shield. Thus, the parasitic deposition shield 604A does not include an orifice. The parasitic deposition shield 604A is positioned in the PLD tool along the path of the laser light in the PLD tool. Next, in FIG. 6B, the laser light is directed through the PLD tool. The optical element 602 focuses the laser light. The laser light may include pulsed laser light. As shown, the parasitic deposition shield 604B is located in the focal plane defined by the optical element 602. The laser beam ablates an orifice 600 in the parasitic deposition shield 604B. In this manner, the orifice 600 is created with a perimeter that substantially matches the perimeter of the laser beam, as shown in FIG. 6C. Furthermore, the laser-formed orifice 600 is aligned with the path of the laser beam. In other examples, the parasitic deposition shield may be located at a location other than the focal plane. However, the orifice created in the parasitic deposition shield that is not located at the focal plane may be larger than the orifice 600.

[0075] FIG. 7 shows a flow chart of an exemplary method 700 for creating a laser-formed orifice in a parasitic deposition shield along the path of laser light in a processing chamber of a PLD tool. Method 700 can be performed on, for example, PLD tool 100. Method 700 includes, at 702, positioning a parasitic deposition shield in the path of laser light in the processing chamber between a laser entrance window and a target holder. In some examples, positioning the parasitic deposition shield includes, at 704, positioning the parasitic deposition shield in a focal plane of one or more optical elements used to focus the laser light. An orifice created at the focal plane can be smaller than an orifice created off the focal plane. In other examples, positioning the parasitic deposition shield in the path of the laser light can include positioning the parasitic deposition shield away from the focal plane of one or more optical elements. The parasitic deposition shield can comprise any suitable material. Suitable materials include materials compatible with the deposition process occurring in the PLD tool. Exemplary materials include aluminum, titanium, stainless steel, or a semiconductor. As a more specific example, aluminum may be used for a parasitic deposition shield where an aluminum-containing target, such as an aluminum nitride target, is used. In such an example, the method 700 may include, at 706, placing an aluminum sheet in the path of the laser light in the process chamber between the laser entrance window and the target holder. Examples of aluminum sheets include aluminum foil or aluminum plate.

[0076] Continuing, method 700 includes ablating an orifice in the parasitic deposition shield using laser light to form a laser-formed orifice at 708. In this manner, method 700 produces an orifice with a perimeter that substantially matches the perimeter of the laser light. In that way, the orifice is aligned with the laser light with less alignment effort than using mirrors to align the laser light within the laser channel.

[0077] Therefore, utilizing a parasitic deposition shield with purge gas flow and / or orifices as disclosed can help reduce the frequency of cleaning of the laser entrance window depending on the number of substrates being processed, which can help reduce downtime for the PLD tool and thereby reduce operating costs.

[0078] It will be understood that the configurations and / or techniques described herein are presented for purposes of example, and that these specific embodiments or examples are not to be considered in a limiting sense, as numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Thus, various acts shown and / or described may be performed in the sequence shown and / or described, in other sequences, in parallel, or omitted. Similarly, the order of the processes described above may be changed.

[0079] The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various processes, systems, and configurations disclosed herein, and other features, functions, acts, and / or properties, and any and all equivalents thereof.

Claims

1. 1. A pulsed laser deposition (PLD) tool comprising: a processing chamber having a laser entrance window; a target holder located within the processing chamber; a substrate holder positioned within the processing chamber; a laser configured to direct laser light through the laser entrance window and toward a target in the target holder; a purge gas inlet located between the laser entrance window and the target holder, the purge gas inlet configured to direct a flow of purge gas toward a path of the laser light; A PLD tool comprising:

2. 10. The PLD tool of claim 1, a PLD tool, wherein the purge gas inlet is configured to direct the flow of the purge gas through the path of the laser light and toward a barrier, the barrier being configured to deflect the flow of the purge gas back through the path of the laser light.

3. 10. The PLD tool of claim 1, The PLD tool further comprises a sacrificial window located between the laser entrance window and the target holder.

4. 4. The PLD tool of claim 3, A PLD tool, wherein the purge gas inlet is located closer to the sacrificial window than to the target holder.

5. 10. The PLD tool of claim 1, The PLD tool further comprising an orifice located along the path of the laser beam, the orifice having a periphery that substantially matches a periphery of the laser beam.

6. 6. A PLD tool according to claim 5, A PLD tool, wherein the purge gas inlet is located closer to the orifice than to the laser entrance window.

7. 6. A PLD tool according to claim 5, The PLD tool further comprising one or more optical elements defining a focal plane, the orifice being located at the focal plane.

8. 6. A PLD tool according to claim 5, The orifice is formed in a parasitic deposition shield.

9. 6. A PLD tool according to claim 5, a barrier configured to form a cavity around the path of laser light, the orifice being a first orifice located at a first end of the cavity, and the purge gas inlet configured to direct the flow of purge gas into the cavity, the purge gas inlet further comprising a second orifice located at a second end of the cavity.

10. 10. The PLD tool of claim 1, The PLD tool further comprises a first purge gas inlet located at a first location and a second purge gas inlet located at a second location between the laser entrance window and the target holder.

11. 1. A pulsed laser deposition (PLD) tool comprising: a processing chamber having a laser entrance window; a target holder located within the processing chamber; a substrate holder positioned within the processing chamber; a laser configured to direct laser light through the laser entrance window and towards the target holder; an orifice located along the path of the laser beam, the orifice having an outer periphery that substantially corresponds to an outer periphery of the laser beam; A PLD tool comprising:

12. 12. The PLD tool of claim 11, The PLD tool further comprising one or more optical elements defining a focal plane, the orifice being located closer to the focal plane than to the laser entrance window.

13. 13. The PLD tool of claim 12, The orifice is located in the focal plane.

14. 12. The PLD tool of claim 11, A PLD tool, wherein the orifice is formed in a parasitic deposition shield comprising a sheet material.

15. 15. A PLD tool as claimed in claim 14, The PLD tool, wherein the sheet material comprises aluminum.

16. 12. The PLD tool of claim 11, The PLD tool further comprising a purge gas inlet located between the laser entrance window and the target holder, the purge gas inlet configured to direct a flow of purge gas toward the path of the laser light.

17. 17. A PLD tool as claimed in claim 16, a PLD tool, wherein the purge gas inlet is configured to direct the flow of the purge gas through the path of the laser light and toward a barrier, the barrier being configured to deflect the flow of the purge gas back through the path of the laser light.

18. 17. A PLD tool as claimed in claim 16, A PLD tool, wherein the purge gas inlet is located closer to the orifice than to the laser entrance window.

19. 17. A PLD tool as claimed in claim 16, The PLD tool further comprising a sacrificial window located between the laser entrance window and the target holder, the purge gas inlet being located closer to the sacrificial window than to the orifice.

20. 1. A method for creating a laser-defined orifice along a path of a laser beam in a processing chamber of a pulsed laser deposition (PLD) tool, comprising: placing a parasitic deposition shield in the path of the laser light in the processing chamber between a laser entrance window and a target holder; ablating the parasitic deposition shield using the laser light to form the laser-defined orifice; A method comprising:

21. 21. The method of claim 20, The method of claim 1, wherein positioning the parasitic deposition shield in the path of the laser light in the processing chamber between the laser entrance window and the target holder comprises positioning the parasitic deposition shield in a focal plane of one or more optical elements used to focus the laser light.

22. 21. The method of claim 20, wherein placing the parasitic deposition shield in the path of the laser light in the processing chamber between the laser entrance window and the target holder comprises placing an aluminum sheet in the path of the laser light in the processing chamber between the laser entrance window and the target holder.

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