Reducing particle contamination of a laser entrance window in a pulsed laser deposition tool

Abstract

One example provides a pulsed laser deposition (PLD) tool. The PLD tool comprises a processing chamber comprising a laser entrance window. The PLD tool further comprises a target holder located within the processing chamber. The PLD tool further comprises a substrate holder located within the processing chamber. The PLD tool further comprises a laser configured to direct laser light through the laser entrance window and towards the target holder. The PLD tool further comprises 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 a path of the laser light.

Description

REDUCING PARTICLE CONTAMINATION OF A LASER ENTRANCEWINDOW IN A PULSED LASER DEPOSITION TOOLBACKGROUND

[0001] Pulsed laser deposition (PLD) can be used in semiconductor device manufacturing to deposit a film on a substrate. 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 deposits on the substrate.SUMMARY

[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. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

[0003] One example provides a pulsed laser deposition (PLD) tool. The PLD tool comprises a processing chamber comprising a laser entrance window. The PLD tool further comprises a target holder located within the processing chamber. The PLD tool further comprises a substrate holder located within the processing chamber. The PLD tool further comprises a laser configured to direct laser light through the laser entrance window and towards the target holder. The PLD tool further comprises 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 into a path of the laser light.

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

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

[0006] In some such examples, 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 light. The orifice comprises a perimeter that substantially matches a perimeter of the laser light.

[0008] In some such examples, 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 comprises one or more optics defining a focal plane, and the orifice is located at the focal plane.

[0010] In some such examples, the orifice is alternatively or additionally formed in a parasitic deposition shield.

[0011] In some such examples, the PLD tool alternatively or additionally comprises a barrier configured to form a cavity around the path of laser light. The orifice is alternatively or additionally a first orifice located at a first end of the cavity. The purge gas inlet is alternatively or additionally configured to direct the flow of purge gas into the cavity. The PLD tool alternatively or additionally comprises 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 comprises 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 comprises a processing chamber comprising a laser entrance window. The PLD tool further comprises a target holder located within the processing chamber. The PLD tool further comprises a substrate holder located within the processing chamber. The PLD tool further comprises a laser configured to direct laser light through the laser entrance window and towards the target holder. The PLD tool further comprises an orifice located along a path of the laser light. The orifice comprises a perimeter that substantially matches a perimeter of the laser light.

[0014] In some such examples, the PLD tool alternatively or additionally comprises one or more optics defining a focal plane. The orifice is alternatively or additionally located closer to the focal plane than to the laser entrance window.

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

[0016] In some such examples, the orifice is 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 comprises 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 into the path of the laser light.

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

[0020] In some such examples, 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 comprises a sacrificial window located between the laser entrance window and the target holder. The purge gas inlet is alternatively or additionally located closer to the sacrificial window than to the orifice.

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

[0023] In some such examples, 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 alternatively or additionally comprises positioning the parasitic deposition shield at a focal plane of one or more optics used to focus the laser light.

[0024] In some such examples, 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 alternatively or additionally comprises positioning an aluminum sheet in the path of the laser light in the processing chamber between the laser entrance window and the target holder.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 schematically illustrates an example PLD tool.

[0026] FIG. 2 schematically shows an example purge gas inlet comprising a barrier that deflects a flow of purge gas again through a path of laser light.

[0027] FIG. 3 schematically shows another example purge gas inlet configured to output a flow of purge gas that is diagonal to a path of laser light.

[0028] FIG. 4 schematically shows an example orifice in a parasitic deposition shield.

[0029] FIG. 5 schematically shows an example barrier configured as a cavity with orifices at each end.

[0030] FIGS. 6A-6C schematically show an example of creating an orifice in a parasitic deposition shield by laser ablation.

[0031] FIG. 7 shows a flow diagram illustrating an example method for creating an orifice in a parasitic deposition shield.DETAILED DESCRIPTION

[0032] The term “ablation”, “laser ablation”, and variants thereof generally represent the removal of material from a target using laser energy. Material removed from a target by laser ablation can deposit on a substrate to form a film.

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

[0034] The term "focal plane" generally represents a plane oriented normal to an optical axis of an optical system that is located at a focus of an optic of the optical system.

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

[0036] The term "optic" generally represents a structure configured to modify a property or path of light (in some examples, laser light). Example optics include refractive and diffractive lenses and mirrors.

[0037] The term "orifice" generally represents an opening. For example, an orifice can be an opening formed in a parasitic deposition shield that allows passage of laser light. The term “substantially matches” with reference to a comparison of a perimeter of an orifice to a perimeter of a laser beam generally represents a differencebetween the diameter of the laser beam and the diameter of the orifice of one percent or less.

[0038] The term “particle” generally represents clusters of atoms, for example, with a dimension larger than 5nm. Some particles in pulsed laser deposition can have diameters larger than lOOnm.

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

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

[0041] The terms “pulsed laser deposition” and “PLD” generally represents a physical deposition process in which a material is ablated from a target by application of pulsed laser energy. At least some target material ablated by the laser adsorbs onto a substrate to form a film on the substrate.

[0042] The term “PLD tool” generally represents a machine including a processing chamber and other hardware configured to enable PLD processing to be carried out in the processing chamber.

[0043] The term “purge gas” generally represents 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 represents a structure configured to direct a flow of purge gas into a space.

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

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

[0047] The term "target" generally represents a solid mass of a 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 represents 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 the target using the laser can be referred to as ablation. The laser forms a plasma plume comprising the material removed from the target. The material in the plasma plume deposits on the substrate to form a film on the substrate.

[0050] However, the pulsed laser also produces particles that are ejected from the target. The particles may comprise atoms, molecules, clusters of atoms, larger particles (e.g. greater than lOOnm), and / or any combination thereof. The pulsed laser enters the processing chamber through a laser entrance window. Some of the particles produced by the laser ablation process can reach the laser entrance window and deposit on the laser entrance window. Over time, the particles depositing on the laser entrance window result can reduce laser light transmission through the laser entrance window.

[0051] To avoid particle deposition on the laser entrance window from negatively impacting PLD tool performance, the laser entrance window is periodically cleaned or replaced. Cleaning the laser entrance window results in tool down time and associated expense.

[0052] Some PLD tools include a sacrificial window positioned between a laser entrance window and a target. The sacrificial window blocks some particles from reaching the laser entrance window. The sacrificial window can be designed to be rotatable or otherwise moveable to expose different portions of the sacrificial window to the laser light and particle contaminants. When particulate deposition on a currently exposed portion of the sacrificial window starts to negatively impact PLD processes, the sacrificial window can be rotated or otherwise moved to expose a different portion of the sacrificial window to the laser light and to block particle contaminants from the target. In some embodiments, after all portions of the sacrificial window have been coated with particle contaminants such that transmission of laser light through the sacrificial window is reduced below a desired limit, the sacrificial window can be replaced.

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

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

[0055] FIG. 1 shows a schematic view of an example PLD tool 100. PLD tool 100 comprises a processing chamber 102 for performing PLD processes on substrates. A target holder 104 and a substrate holder 106 are located within processing chamber 102. A target 108 is arranged on target holder 104 during the PLD process. Further, a substrate 110 is arranged on substrate holder 106.

[0056] PLD tool 100 further comprises a laser 112 configured to direct laser light 114 through a laser entrance window 116 of processing chamber 102 and towards target holder 104. One or more optics 118 (shown here as a single component) can be used to focus laser light 114 to decrease a spot size of laser light 114 at target 108.

[0057] Laser light 114 generates a plasma plume 120 and particles from target 108 during the PLD process. A filter 122 blocks some particles from reaching substrate 110 while passing plasma plume 120 towards substrate 110. Chemical species in plasmaplume 120 deposit on substrate 110 as a film. In some examples, filter 122 rotates in synchronization with laser pulses. As particles travel slower than plasma plume 120, an opening in filter 122 can rotate to a location between a laser spot on target 108 and substrate 110 during laser illumination. In this manner, the opening in filter 122 can pass plasma plume 120. The opening in filter 122 then rotates away to block at least some of the slower traveling particles.

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

[0059] Particles from target 108 can travel throughout processing chamber 102. Some particles can reach laser entrance window 116 and thereby contaminate laser entrance window 116. Particle contamination can reduce a laser power that reaches the target. This can impact deposition efficiency and consistency. Also, cleaning the laser entrance window 116 can involve breaking system vacuum. Breaking the system vacuum results in tool downtime. Thus, in some embodiments, PLD tool 100 further comprises a sacrificial window 126 to help reduce particles reaching laser entrance window 116. As shown, sacrificial window 126 is located between laser entrance window 116 and target holder 104. Sacrificial window 126 can be rotatable or otherwise moveable. As a specific example, sacrificial window 126 can comprise a plurality of indexes each representing a different location on sacrificial window 126. When a first location of sacrificial window 126 reaches a threshold use condition, sacrificial window 126 is moved to a next index to advance a clean location on sacrificial window 126 into the path of laser light 114. In such a manner, multiple clean locations of sacrificial window 126 can be exposed in processing chamber 102 before replacing sacrificial window 126. This can help to reduce a frequency at which a sacrificial window is changed. In other examples, sacrificial window 126 can be configured as a fixed window. In further examples, a PLD can omit sacrificial window 126.

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

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

[0062] Parasitic deposition shield 132 can be formed from a material that is compatible with a PLD process being performed in PLD tool 100. Examples of materials suitable for use as parasitic deposition shield 132 include aluminum, stainless steel, titanium, and semiconductors such as silicon. As a more specific example, parasitic deposition shield 132 can comprise 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 depicted example, orifice 130 is located at a focal plane defined by one or more optics 118. In such a configuration a smaller orifice can be used than an orifice at a different location along the path of laser light 114. Further, in such a location, orifice 130 can be used as an optical spatial filter. In other examples, orifice 130 can be located closer to the focal plane than to laser entrance window 116.

[0064] In some examples, a pressure differential can be created over parasitic deposition shield 132 and orifice 130 using the flow of purge gas. More specifically, a higher-pressure region can be created between orifice 130 and laser entrance window 116 in processing chamber 102. In some such examples, the higher-pressure region can be formed by directing the flow of purge gas into a cavity comprising orifice 130 on a first end and a second orifice on a second end. The higher-pressure region can help to increase a drag on particles between laser entrance window 116 and orifice 130. Further, the higher-pressure region can have a directional flow towards plasma plume120. Thus, the higher-pressure region can help to reduce particles reaching laser entrance window 116. In other examples, PLD tool 100 can omit parasitic deposition shield 132.

[0065] In some examples, a PLD tool can have a single purge gas inlet along the path of laser light between a laser entrance window and a target holder. In other examples, a 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 laser light 114. Second purge gas inlet 134 is located closer to orifice 130 than to laser entrance window 116. Similar to first purge gas inlet 128, second purge gas inlet 134 is configured to direct a flow of purge gas into the path of laser light 114. In such a manner, some particles from plasma plume 120 can be deflected away from a direction toward laser entrance window 116. In other examples, second purge gas inlet 134 can be located at any other suitable location between laser entrance window 116 and target holder 104. In further examples, PLD tool 100 can omit second purge gas inlet 134. In yet further examples, PLD tool 100 can comprise three or more purge gas inlets located along the path of laser light 114.

[0066] First purge gas inlet 128 and 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 installed. In some embodiments, different gas inlets may receive purge gas from different gas sources. Further, the PLD tool also can be configured to receive a flow of a processing gas from a processing gas source 138 during a PLD process. In some examples, the process gas comprises nitrogen. In other examples, the processing gas alternatively or additionally comprises argon, helium, neon, krypton, xenon, and / or other suitably inert gas. PLD tool 100 further comprises an exhaust system 140 configured to draw gases out of processing chamber 102. Processing gas source 138, purge gas source 136, and exhaust system 140 can be controlled to maintain a desired pressure within processing chamber 102 during a PLD process. In some examples, the pressure of processing chamber 102 can be maintained at a pressure within a range of 0.01-0.1 millibars. In other examples, pressures outside of this range can be used.

[0067] PLD tool 100 further comprises a controller 142 configured to control components of PLD tool 100. For example, controller 142 controls the flow of the purge gas to first and / or second purge gas inlets 128, 134. In some examples, controller 142 can pulse the flow of purge gas to first and / or second purge gas inlets 128, 134synchronously with a pulse of laser 112. Controller further is connected to sacrificial window 126. As such, controller 142 can be configured to advance sacrificial window 126 to a clean position once a current position is optically degraded from particle contamination. Controller 142 is further configured to control laser 112, exhaust system 140, substrate holder 106, heater 124, and other suitable components of PLD tool 100.

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

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

[0070] In the examples above, a purge gas inlet is used to divert particles away from a sacrificial window. In other examples, a parasitic deposition shield comprising an orifice alternatively or additionally can be used to help prevent particles from reaching a laser entrance window. FIG. 4 shows an example orifice 400 formed in a parasitic deposition shield 401. Orifice 400 is an example of orifice 130 of FIG. 1. As previously mentioned, a lens 402 or other optic(s) can be used to focus laser light that impinges a target 404 to generate a plasma plume 406. Parasitic deposition shield 401 helps to block particles from target 404 that are traveling toward a laser entrance window 410. Orifice 400 allows the laser light to pass through parasitic deposition shield 401.

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

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

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

[0074] FIGS. 6A, 6B, 6C schematically show the creation of an example laser- formed orifice 600 using a laser in a PLD tool by laser ablating a parasitic deposition shield. Orifice 600 is an example of orifice 130. FIG. 6A schematically illustrates an optic 602 and a parasitic deposition shield 604 A of the PLD tool. Other components of the PLD tool are omitted for clarity. As shown, parasitic deposition shield 604A is a new parasitic deposition shield. Therefore, parasitic deposition shield 604A does not comprise an orifice. Parasitic deposition shield 604A is positioned in the PLD tool located along a path of laser light of the PLD tool. Next, in FIG. 6B, laser light is directed through the PLD tool. Optic 602 focuses the laser light. The laser light can comprise pulsed laser light. As shown, parasitic deposition shield 604B is located at a focal plane defined by optic 602. The laser light ablates orifice 600 in parasitic deposition shield 604B. In this manner, orifice 600 is created having a perimeter that substantially matches a perimeter of the laser light, as shown in FIG. 6C. Further, laser- formed orifice 600 is aligned to the path of laser light. In other examples, a parasitic deposition shield can be located at a location other than the focal plane. However, an orifice created in the parasitic deposition shield not located at the focal plane can be larger than orifice 600.

[0075] FIG. 7 illustrates a flow diagram of an example method 700 for creating a laser-formed orifice in a parasitic deposition shield along a path of laser light in a processing chamber of a PLD tool. Method 700 can be performed on PLD tool 100, for example. Method 700 comprises, at 702, positioning the parasitic deposition shield in the path of the laser light in the processing chamber between a laser entrance window and a target holder. In some examples, positioning the parasitic deposition shield comprises, at 704, positioning the parasitic deposition shield at a focal plane of one or more optics used to focus the laser light. An orifice created at the focal plane can be smaller than an orifice created not at the focal plane. In other examples, positioning the parasitic deposition shield in the path of the laser light can comprise positioning the parasitic deposition shield away from the focal plane of one or more optics. The parasitic deposition shield can comprise any suitable material. Suitable materials include materials compatible with a deposition process being carried out in the PLD tool. Example materials include aluminum, titanium, stainless steel, or a semiconductor. As a more specific example, aluminum can be used for the parasitic deposition shield where an aluminum-containing target is used, such as an aluminum nitride target. In such an example, method 700 can comprise, at 706, positioning an aluminum sheet in the path of the laser light in the processing chamber between the laser entrance window and the target holder. Examples of the aluminum sheet comprise aluminum foil or an aluminum plate.

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

[0077] Thus, utilizing a purge gas flow and / or a parasitic deposition shield comprising an orifice as disclosed can help to reduce a frequency of cleanings of the laser entrance window as a function of a number of substrates processed. This can help reduce downtime for the PLD tool, and thereby reduce operating costs.

[0078] It will be understood that the configurations and / or approaches described herein are presented for example, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or moreof any number of processing strategies. As such, various acts illustrated and / or described may be performed in the sequence illustrated and / or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed.

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

Claims

CLAIMS:

1. A pulsed laser deposition (PLD) tool, comprising: a processing chamber comprising a laser entrance window; a target holder located within the processing chamber; a substrate holder located within the processing chamber; a laser configured to direct laser light through the laser entrance window and towards a target in the target holder; and 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 a path of the laser light.

2. The PLD tool of claim 1, 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 configured to deflect the flow of the purge gas again through the path of the laser light.

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

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

5. The PLD tool of claim 1, further comprising an orifice located along the path of the laser light, the orifice comprising a perimeter that substantially matches a perimeter of the laser light.

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

7. The PLD tool of claim 5, further comprising one or more optics defining a focal plane, and wherein the orifice is located at the focal plane.

8. The PLD tool of claim 5, wherein the orifice is formed in a parasitic deposition shield.

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

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

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

12. The PLD tool of claim 11, further comprising one or more optics defining a focal plane, and wherein the orifice is located closer to the focal plane than to the laser entrance window.

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

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

15. The PLD tool of claim 14, wherein the sheet material comprises aluminum.

16. The PLD tool of claim 11, further comprising 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 into the path of the laser light.

17. The PLD tool of claim 16, 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 configured to deflect the flow of the purge gas again through the path of the laser light.

18. The PLD tool of claim 16, wherein the purge gas inlet is located closer to the orifice than to the laser entrance window.

19. The PLD tool of claim 16, further comprising a sacrificial window located between the laser entrance window and the target holder, and wherein the purge gas inlet is located closer to the sacrificial window than to the orifice.

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

21. The method of claim 20, 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 at a focal plane of one or more optics used to focus the laser light.

22. The method of claim 20, 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 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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