Cleaning device and method for removing contaminant particles from surface to be cleaned

Abstract

A cleaning device for removing contaminant particles from a surface to be cleaned. The cleaning device includes an oxygen source configured to emit oxygen and thereby oxidize the contaminant particles and the surface to be cleaned. The cleaning device includes an electron source configured to emit electrons and thereby negatively charge the oxidized contaminant particles and the surface to be cleaned. The cleaning device includes a contaminant particle collector configured to receive the positively charged contaminant particles and thereby attract negatively charged contaminant particles emitted from the surface to be cleaned.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to European Application No. 22208092.1, filed on November 17, 2022, the entire content of which is incorporated herein by reference. Technical field

[0003] The present disclosure relates to a cleaning device and method. Specifically, the present disclosure relates to a particle cleaning device and method for use in conjunction with substrate processing equipment and methods, such as, for example, charged particle equipment, soft x - ray equipment, substrate metrology equipment, substrate inspection equipment, lithography equipment, etc., and associated methods. Background art

[0004] In the manufacture of semiconductor devices, for example, substrate processing equipment is used to produce and inspect substrates. For example, in the manufacture of semiconductor integrated circuit (IC) chips, due to, for example, optical effects and accidental particles, unwanted pattern defects inevitably occur on the substrate (i.e., wafer) or mask during the manufacturing process, thereby reducing the yield. Therefore, monitoring the extent of unwanted pattern defects is an important process in the manufacture of IC chips. More generally, the inspection and / or measurement of the surface of a substrate or other object / material is an important process during and / or after its manufacture. Examples of substrate processing equipment include pattern inspection tools with charged particle beams, and pattern inspection tools with charged particle beams have been used to inspect substrates, for example, to detect pattern defects. These tools typically use electron microscopy techniques, and electron microscopy techniques use, for example, electro - optical systems in a scanning electron microscope (SEM). In an exemplary electron - optical system of such an SEM, a final deceleration step is utilized to target a primary electron beam of electrons at a relatively high energy so that the primary electron beam lands on the sample at a relatively low landing energy. The electron beam is focused into a probe spot on the sample. The interaction between the material structure at the probe spot and the landing electrons from the electron beam causes electrons to be emitted from the surface, such as secondary electrons, backscattered electrons, or Auger electrons. Secondary electrons can be emitted from the material structure of the sample. By scanning the primary electron beam as a probe spot across the surface of the sample, secondary electrons can be emitted across the surface of the sample. By collecting these emitted secondary electrons from the surface of the sample, the pattern inspection tool can obtain an image representing the characteristics of the material structure of the surface of the sample. The intensity of the electron beam, including backscattered electrons and secondary electrons, can vary based on the nature of the internal and external structures of the sample, and thus can indicate whether the sample has a defect.

[0005] Another example of a substrate processing apparatus is a lithographic apparatus. A lithographic apparatus is a machine configured to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). For example, a lithographic apparatus can project a pattern present on a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) provided on a substrate.

[0006] In order to project a pattern onto a substrate, a lithographic apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum feature size that can be formed on the substrate. Compared to a lithographic apparatus that uses radiation having a wavelength of, for example, 193 nm, a lithographic apparatus that uses extreme ultraviolet (EUV) radiation having a wavelength in the range of 4 nm to 20 nm (e.g., 6.7 nm or 13.5 nm) can be used to form smaller features on a substrate.

[0007] Surfaces within a substrate processing apparatus can accumulate deposits of contaminant particles over time. The contaminant particles can emanate from the surfaces and travel towards a substrate to be processed by the substrate processing apparatus. This can lead to errors and / or defects when the substrate processing apparatus processes the substrate. For example, the lithographic surfaces within a lithographic apparatus can accumulate deposits of contaminant particles over time. For example, repeated high-acceleration movement of components such as a mask support and a substrate table can generate contaminant particles by friction. As another example, contaminant particles can enter the lithographic apparatus from the external environment during a vacuum evacuation process. A portion of the contaminant particles lands on a lithographic surface such as a mask, a substrate, and / or one or more optical elements (e.g., an illumination system or a projection system mirror or lens) configured to interact with electromagnetic radiation and adheres to the lithographic surface. A portion of the contaminant particles lands on a surface adjacent to the substrate and adheres to the surface, accumulates over time, and emanates from the surface and travels towards the substrate. Contaminant particles present on the lithographic surface can negatively affect the performance of the lithographic apparatus. For example, contaminant particles present on a mask can negatively affect the accuracy with which the pattern of the mask is imaged onto the substrate, which can in turn result in defective chips manufactured by the lithographic apparatus.

[0008] Known cleaning devices and methods can be limited in their ability to clean surfaces such as surfaces from which contaminant particles emanate and travel towards a substrate to be processed by a substrate processing apparatus. Known cleaning devices and methods can be limited in their ability to clean lithographic surfaces. There is a desire to provide cleaning devices and methods that eliminate or mitigate one or more problems of the prior art identified herein or elsewhere. SUMMARY OF THE INVENTION

[0009] According to a first aspect of the present disclosure, there is provided a cleaning device for removing contaminant particles from a surface to be cleaned. The cleaning device includes an oxygen source configured to emit oxygen and thereby oxidize the contaminant particles and the surface to be cleaned. The cleaning device includes an electron source configured to emit electrons and thereby negatively charge the oxidized contaminant particles and the surface to be cleaned. The cleaning device includes a contaminant particle collector configured to receive positive charge and thereby attract the negatively charged contaminant particles ejected from the surface to be cleaned.

[0010] The cleaning device can be a particle cleaning device. That is, the cleaning device can be configured to remove particles from the surface to be cleaned. The surface to be cleaned can be a critical surface. The surface to be cleaned can be a lithography surface. That is, according to one aspect of the present disclosure, there is provided a cleaning device for removing contaminant particles from a lithography surface to be cleaned. The cleaning device includes an oxygen source configured to emit oxygen and thereby oxidize the contaminant particles and the lithography surface to be cleaned. The cleaning device includes an electron source configured to emit electrons and thereby negatively charge the oxidized contaminant particles and the lithography surface to be cleaned. The cleaning device includes a contaminant particle collector configured to receive positive charge and thereby attract the negatively charged contaminant particles ejected from the lithography surface to be cleaned.

[0011] The oxygen source advantageously converts contaminant particles of different materials, shapes, and / or sizes into dielectric particles and provides an oxide layer on the surface to be cleaned. The electron source advantageously bombards the dielectric particles and the oxide layer on the surface to be cleaned with electrons and thereby negatively charges the oxidized contaminant particles and the oxide layer on the surface to be cleaned. The negatively charged contaminant particles repel each other electromagnetically. The negatively charged surface to be cleaned repels the negatively charged particles electromagnetically. The force generated by the electromagnetic repulsion causes the negatively charged contaminant particles to be ejected or "jump" from the surface to be cleaned. The contaminant particle collector can be provided with positive charge and thereby attract the negatively charged contaminant particles ejected from the surface to be cleaned electromagnetically to prevent the contaminant particles from contacting and / or adhering to any other surface. The cleaning device advantageously functionally changes the surface properties of any particles by providing an oxide layer and also captures the particles once they are released from the surface to be cleaned. The cleaning device serves as a fast and efficient cleaning tool for contamination control in substrate processing equipment such as, for example, charged particle equipment, soft x-ray equipment, substrate metrology equipment, substrate inspection equipment, lithography equipment, and the like.

[0012] A sub-atmospheric pressure (i.e., vacuum or near-vacuum) can be applied to the space containing the cleaning device and the surface to be cleaned.

[0013] The cleaning device advantageously reduces the cleanliness specifications requirements of substrate processing equipment, such as, for example, charged particle equipment, soft x-ray equipment, substrate metrology equipment, substrate inspection equipment, lithography equipment, etc. For example, fewer vacuum pumps may be required to maintain the desired standard of cleanliness in the substrate processing equipment. As another example, fewer pellicles may be required to protect the components of the lithography equipment including the cleaning device, thereby reducing the unwanted absorption rate of electromagnetic radiation during use.

[0014] The cleaning device may be configured to be positioned opposite the surface to be cleaned.

[0015] The surface to be cleaned may be the surface of a charged particle equipment such as, for example, an electron beam system. The surface to be cleaned may be the surface of a soft x-ray equipment. The surface to be cleaned may be the surface of a substrate metrology equipment. The surface to be cleaned may be the surface of a substrate inspection equipment. The surface to be cleaned may be the surface of a lithography equipment.

[0016] The cleaning device may be configured to form an integral part of a system including the surface to be cleaned. The cleaning device may be configured to be removable. For example, the cleaning device may be inserted into a system including the surface to be cleaned for cleaning the surface and then removed from the system.

[0017] This arrangement advantageously quickly collects the contaminating particles after they are ejected and before they may fall and impinge on other surfaces.

[0018] The cleaning device may include an actuation system configured to create relative movement between the cleaning device and the surface to be cleaned.

[0019] The actuation system advantageously allows a cleaning scan to be performed.

[0020] The oxygen source, the electron source, and the contaminating particle collector may be arranged relative to each other such that the oxygen source directs the electron source in the scan direction of the cleaning device. The oxygen source, the electron source, and the contaminating particle collector may be arranged relative to each other such that the electron source directs the contaminating particle collector in the scan direction of the cleaning device.

[0021] This arrangement advantageously allows the surface to be cleaned in a single scan movement or "sweeping" manner in the scan direction.

[0022] The cleaning device may include a sensor system configured to detect cleaning parameters. The cleaning device may include a controller configured to control at least one of the oxygen source, the electron source, and the contaminating particle collector at least partly dependent on the cleaning parameters.

[0023] The sensor system and the controller advantageously provide an automatic and / or feedback-driven operation of the cleaning device.

[0024] The cleaning parameters can include the distance between the cleaning device and the surface to be cleaned. The cleaning parameters can include the alignment between the cleaning device and the surface to be cleaned. The cleaning parameters can include the relative movement between the cleaning device and the surface to be cleaned.

[0025] The cleaning parameters advantageously ensure that appropriate conditions are met for the desired level of cleaning to occur.

[0026] The contaminant particle collector can be arranged at an angle relative to the oxygen source and the electron source such that an acute angle is formed between the direction the contaminant particle collector faces and the surface to be cleaned.

[0027] This arrangement advantageously improves the ability of the contaminant particle collector to attract and collect negatively charged contaminant particles.

[0028] The acute angle can be in the range of about 10° to about 75°, including the end values 10° and 75°.

[0029] The inventors have found that this angle range is particularly effective in attracting and collecting negatively charged contaminant particles.

[0030] The cleaning device can include a first insulator located between the oxygen source and the electron source. The cleaning device can include a second insulator located between the contaminant particle collector and the housing of the cleaning device. The first insulator can be configured to electrically isolate the oxygen source from the electron source and / or electrons. The second insulator can be configured to electrically isolate the housing from the contaminant particle collector and / or negatively charged contaminant particles.

[0031] The insulators advantageously improve the safety of the cleaning device and reduce the risk of unwanted arc discharges, short circuits, and / or other unwanted electrical effects.

[0032] The cleaning device can include a plurality of oxygen sources, electron sources, and contaminant particle collectors arranged in a cleaning array.

[0033] The cleaning array advantageously enables simultaneous cleaning of different regions of the surface to be cleaned, thereby reducing the amount of time required to clean the surface.

[0034] According to a second aspect of the present disclosure, there is provided a substrate processing apparatus including the cleaning device of the first aspect. The substrate processing apparatus can be a charged particle apparatus such as, for example, an electron beam inspection apparatus. The substrate processing apparatus can be a soft x-ray apparatus. The substrate processing apparatus can be a substrate metrology apparatus. The substrate processing apparatus can be a substrate inspection apparatus.

[0035] The substrate processing apparatus may be a lithographic apparatus. That is, according to one aspect of the present disclosure, there is provided a lithographic apparatus arranged to condition electromagnetic radiation and project a pattern from a patterning device onto a substrate. The lithographic apparatus includes a cleaning device according to the first aspect.

[0036] The cleaning device may be configured to form an integral part of the substrate processing apparatus. The cleaning device may be configured to be removable. For example, the cleaning device may be inserted into the substrate processing apparatus (such as, for example, a lithographic apparatus) for cleaning the surface to be cleaned and then removed from the substrate processing apparatus.

[0037] The cleaning device advantageously allows in-situ cleaning of the surface to be cleaned, thereby avoiding the need to remove the surface from the substrate processing apparatus. For example, the lithographic surface may be cleaned without interrupting the lithographic exposure or reducing the throughput of the lithographic apparatus.

[0038] The cleaning device may be configured to clean the patterning device. The cleaning device may be configured to clean the substrate. The cleaning device may be configured to clean the optical elements configured to interact with the electromagnetic radiation.

[0039] The cleaning device may be configured to clean the surface from which contaminant particles emanate and travel to the substrate to be processed by the substrate processing apparatus.

[0040] The cleaning device may be configured to clean the surface adjacent to the patterning device. The patterning device may be configured to impart a pattern to the radiation. The surface adjacent to the patterning device may be the surface of a support structure configured to support the patterning device.

[0041] The cleaning device may be configured to clean the surface adjacent to the substrate. The substrate may be configured to receive the patterned radiation beam. The surface adjacent to the substrate may be the surface of a substrate table configured to support the substrate.

[0042] The cleaning device may be configured to clean a voltage shield plate. The voltage shield plate may be configured to protect the substrate from discharge and / or arc discharge. The voltage shield plate may be opposite to the substrate. For example, the voltage shield plate may be opposite to the upper surface of the substrate.

[0043] The substrate may be a semiconductor device. The semiconductor device may be fully formed. The semiconductor device may be partially formed. For example, the semiconductor device may be in the manufacturing process. The substrate processing apparatus may be a post-processing tool.

[0044] According to a third aspect of the present disclosure, a method for removing contaminant particles from a surface to be cleaned is provided. The method includes oxidizing the contaminant particles and the surface to be cleaned. The method includes negatively charging the oxidized contaminant particles and the surface to be cleaned. The method includes using a positive charge to attract and thereby collect the negatively charged contaminant particles ejected from the surface to be cleaned.

[0045] The surface to be cleaned may be a lithographic surface. That is, according to one aspect of the present disclosure, a method for removing contaminant particles from a lithographic surface to be cleaned is provided. The method includes oxidizing the contaminant particles and the lithographic surface to be cleaned. The method includes negatively charging the oxidized contaminant particles and the lithographic surface to be cleaned. The method includes using a positive charge to attract and thereby collect the negatively charged contaminant particles ejected from the lithographic surface to be cleaned.

[0046] According to a fourth aspect of the present disclosure, a method of processing a substrate is provided, including the method described in the third aspect.

[0047] The method of removing contaminant particles from the surface to be cleaned may be performed during the operation of a substrate processing apparatus. For example, the method of removing contaminant particles from the surface to be cleaned may be performed during the emission of charged particles such as electrons in a charged particle apparatus. As another example, the method of removing contaminant particles from the surface to be cleaned may be performed during the emission of soft x-rays in a soft x-ray apparatus. As another example, the method of removing contaminant particles from the surface to be cleaned may be performed during the measurement of a substrate in a substrate metrology apparatus. As another example, the method of removing contaminant particles from the surface to be cleaned may be performed during the inspection of a substrate in a substrate inspection apparatus.

[0048] According to one aspect of the present disclosure, a method is provided that includes projecting a patterned radiation beam onto a substrate and performing the method of the third aspect.

[0049] The method of removing contaminant particles from the lithographic surface to be cleaned may be performed during the projection of the patterned radiation beam onto the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Embodiments of the present invention will now be described by way of example with reference to the accompanying schematic drawings, in which:

[0051] - Figure 1 A lithographic system according to the present disclosure including a lithographic apparatus, a radiation source, and a plurality of cleaning devices is schematically depicted.

[0052] - Figure 2 Schematically depicts a side view of a part of a third cleaning device according to the present disclosure Figure 1 of.

[0053] - Figure 3 A top view schematically depicting a third cleaning device according to the present disclosure. Figure 1 of

[0054] - Figure 4 A flowchart showing a method of removing contaminant particles from a surface to be cleaned (e.g., a lithography surface) according to the present disclosure.

[0055] - Figure 5 A side view schematically depicting a portion of a third cleaning device according to the present disclosure when cleaning a surface different from Figure 2 the surface shown in Figure 2

[0056] - Figure 6 A side view schematically depicting a portion of a cleaning device configured to clean contaminant particles from a surface from which they emanate and travel to a substrate to be processed by a substrate processing apparatus.

[0057] - Figure 7 An exemplary configuration of a charged particle apparatus in the form of a single beam electron beam system that may include a cleaning device according to the present disclosure. Detailed Description

[0058] Figure 1 A lithography system is schematically depicted according to the present disclosure, including a radiation source SO, a lithography apparatus LA, and a plurality of cleaning devices 101 to 103. The radiation source SO is configured to generate an EUV radiation beam B and supply the EUV radiation beam B to the lithography apparatus LA. The lithography apparatus LA includes an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate table WT configured to support a substrate W.

[0059] The illumination system IL is configured to condition the EUV radiation beam B before it is incident on the patterning device MA. Additionally, the illumination system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11. The faceted field mirror device 10 and the faceted pupil mirror device 11 together provide an EUV radiation beam B having a desired cross-sectional shape and a desired intensity distribution. As a supplement or alternative to the faceted field mirror device 10 and the faceted pupil mirror device 11, the illumination system IL may include other mirrors or devices.

[0060] After such adjustment, the EUV radiation beam B interacts with the patterning device MA. Due to this interaction, a patterned EUV radiation beam B' is produced. The projection system PS is configured to project the patterned EUV radiation beam B' onto the substrate W. For this purpose, the projection system PS may include a plurality of mirrors 13, 14 configured to project the patterned EUV radiation beam B' onto the substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B', thereby forming an image having features smaller than the corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 may be applied. Although the projection system PS is illustrated as having only two mirrors 13, 14 in Figure 1 it, the projection system PS may include a different number of mirrors (e.g., six or eight mirrors).

[0061] The substrate W may include a previously formed pattern. In such a case, the lithographic apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the pattern previously formed on the substrate W.

[0062] A relative vacuum may be provided in the radiation source SO, in the illumination system IL, and / or in the projection system PS, i.e., a small amount of gas (e.g., hydrogen) at a pressure sufficiently below atmospheric pressure.

[0063] The radiation source SO may be a laser-produced plasma (LPP) source, a discharge-produced plasma (DPP) source, a free electron laser (FEL), or any other radiation source capable of producing EUV radiation.

[0064] In Figure 1 the example, the lithographic apparatus LA is configured to use EUV radiation. It will be understood that the cleaning device and method of the present disclosure are not limited to use with EUV lithographic apparatuses and may be used with other lithographic apparatuses such as, for example, deep ultraviolet ("DUV") lithographic apparatuses.

[0065] Figure 1 the lithographic apparatus LA includes three cleaning devices 101 to 103 according to the present disclosure. The lithographic apparatus LA may be provided with a larger or smaller number of cleaning devices 101 to 103. The cleaning devices 101 to 103 are substantially the same. In Figure 2 and Figure 3 one of the cleaning devices 103 is shown in more detail. Each of the cleaning devices 101 to 103 is configured to remove contaminant particles from the surfaces MA, 14, W to be cleaned. The first lithographic cleaning device 101 is configured to clean the patterning device MA. The second cleaning device 102 is configured to clean the optical element 14 configured to interact with the electromagnetic radiation B' of the lithographic apparatus LA. In Figure 1In the example, the optical element is the mirror 14 present in the projection system PS. The second cleaning device 102 may be configured to clean other optical elements of the lithographic apparatus LA or a larger number of cleaning devices may be provided to clean other optical elements of the lithographic apparatus LA (e.g., one or more optical elements 10, 11 present in the illumination system IL). The third cleaning device 100 is configured to clean the substrate W.

[0066] The lithographic apparatus LA may include one or more vacuum pumps 110a to 110b. The vacuum pumps 110a to 110b may be configured to provide a sub-atmospheric pressure (i.e., a vacuum or near-vacuum) in the internal space that includes the cleaning devices 101 to 103 and the lithographic surface. In Figure 1 the example, the first vacuum pump 110a provides a sub-atmospheric pressure in the first internal space 111a that includes the first cleaning device 101 and the second vacuum pump 110b provides a sub-atmospheric pressure in the second internal space 111b that includes the second cleaning device 102 and the third cleaning device 103. The lithographic apparatus LA may include a larger or smaller number of vacuum pumps 110a to 110b configured to provide a sub-atmospheric pressure in a larger or smaller number of internal spaces 111a to 111b. The sub-atmospheric pressure may assist the operation of the cleaning devices by providing an improved environment for the controlled and directed targeted emission of oxygen and electrons, as discussed in more detail below.

[0067] Figure 2 Schematically depicts a side view of a portion 103a of the third cleaning device 103 according to the present disclosure Figure 1 The cleaning device 103 is configured to clean the lithographic surface shown as the substrate W in Figure 2 the example. Contaminant particles 120 adhere to the substrate W. It will be appreciated that Figure 2 is not drawn to scale and in particular, the relative size of the contaminant particles 120 has been increased for ease of understanding. The contaminant particles 120 may be generated, for example, by the high-speed and / or accelerating movement of the substrate table WT during exposure. The contaminant particles 120 may have different sizes and / or may be formed of different materials having different surface properties (such as electrostatic properties). The contaminant particles 120 may include dielectric particles, conductive particles, and semiconductor particles. For example, the contaminant particles 120 may include materials such as Al 2 O 3 、SiO 2 、metals, etc. The contaminant particles 120 may have a size of about 1 µm or greater. The contaminant particles 120 may have a size of about 100 µm or less. The contaminant particles 120 may have a size of about 10 µm. The cleaning device 103 is capable of removing contaminant particles 120 of different sizes and materials having different surface properties as explained in more detail below.

[0068] The cleaning device 103 includes an oxygen source 130 configured to emit oxygen 138. The oxygen source 130 can include, for example, an oxygen tank 132 fluidly connected to a gas output 134. The oxygen tank 132 can form part of a pre-existing oxygen supply system (not shown) configured to supply oxygen to one or more components of the lithography apparatus LA (e.g., to flush one or more areas of the lithography apparatus LA). The gas output 134 can include one or more holes or nozzles 135 to 137 configured to emit oxygen in the form of a conical or curtain-like jet 138. The oxygen source 130 can be configured to provide an oxygen flow of about 10 standard cubic centimeters per minute or greater. The oxygen source 130 can be configured to provide an oxygen flow of about 1000 standard cubic centimeters per minute or less. The oxygen 138 reacts with the contaminant particles 120 and the lithography surface W and thereby oxidizes the contaminant particles 120 and the lithography surface W. The oxygen 138 forms an oxide layer 140 on the contaminant particles 120 and the lithography surface W (thereby forming oxidized contaminant particles 122). The oxide layer 140 can have a thickness of about 5 nm or greater. The oxide layer 140 can have a thickness of about 30 nm or less. The presence of the oxide layer 140 functionally changes the surface properties of all different sizes and types of contaminant particles 120 present on the lithography surface W such that the oxidized contaminant particles 122 behave as dielectric particles. Various parameters such as, for example, the temperature of the contaminant particles 120, the oxidation diffusion rate, the material properties can at least partially determine the formation of the oxide layer 140. The temperature can correspond to a typical temperature of the lithography apparatus LA environment. The temperature can be about 20 °C or greater. The temperature can be about 40 °C or less. The speed at which the cleaning device 103 moves relative to the lithography surface W can at least partially determine the thickness of the oxide layer 140.

[0069] The cleaning device 103 further includes an electron source 150 configured to emit electrons 152. The electron source 150 can include, for example, a filament configured to emit electrons 152 upon receiving an electric current. The electron source 150 can take other forms. For example, the electron source 150 can be an electron gun. The electron source 150 can be configured to provide an electron beam 152 having an energy of about 10 eV or greater. The electron source 150 can be configured to provide an electron beam 152 having an energy of about 100 eV or less. The electron source 150 can be configured to provide an electron beam 152 having an energy of about 50 eV. The energy of the electron beam 152 may be limited to avoid arc discharge. The electrons 152 impart a negative charge to the oxidized contaminant particles 122 and the lithography surface W (thereby creating negatively charged contaminant particles 124). The electron source 150 can be referred to as an ionizer. The presence of the oxide layer 140 and the associated dielectric surface properties of the oxidized contaminant particles 122 advantageously allow the electrons 152 to impart a negative charge to the oxidized contaminant particles 122 regardless of the initial surface characteristics of the contaminant particles 120. The negatively charged contaminant particles 124 repel each other electromagnetically. The negatively charged lithography surface W repels the negatively charged contaminant particles 124 electromagnetically. The force generated by the electromagnetic repulsion causes the negatively charged contaminant particles 124 to be ejected or "jump" from the surface W to be lithographed. That is, the negatively charged contaminant particles 124 no longer adhere to the lithography surface W.

[0070] The cleaning device 103 further includes a contaminant particle collector 160. The contaminant particle collector 160 may include a container. The container may be generally bowl-shaped. The contaminant particle collector 160 may be formed of a conductor such as, for example, aluminum or stainless steel. The contaminant particle collector 160 is configured to receive a positive charge and thereby attract, electromagnetically, negatively charged contaminant particles 124 that have been ejected from the lithography surface W. The contaminant particle collector 160 may be configured to receive a bias voltage of about 10 V or greater. The contaminant particle collector 160 may be configured to receive a bias voltage of about 100 V or less. The electromagnetic attraction may act on the negatively charged contaminant particles immediately or shortly after the negatively charged contaminant particles 124 are ejected from the lithography surface W. The electromagnetic attraction causes the negatively charged contaminant particles 124 to move toward and adhere to the contaminant particle collector 160 before the negatively charged contaminant particles 124 can move back to and adhere to the lithography surface W or move toward and adhere to any other lithography surface present in the lithography apparatus LA. The contaminant particle collector 160 may provide an electrostatic force that attracts the negatively charged contaminant particles 124. The contaminant particle collector 160 may be emptied and / or cleaned at regular intervals to remove the collected contaminant particles. The contaminant particle collector 160 may be positioned closer to the lithography surface W than the oxygen source 130 or the electron source 150. The contaminant particle collector 160 may be positioned at about half the path between the lithography surface W and the oxygen source 130 and the electron source 150. For example, the contaminant particle collector 160 may be positioned about 0.5 mm away from the lithography surface W.

[0071] The cleaning device 103 is configured to be positioned opposite the lithography surface W to be cleaned. This arrangement advantageously improves the rapid attraction and collection of the negatively charged contaminant particles 124 after they are ejected from the lithography surface W and before the negatively charged contaminant particles 124 can travel and adhere to any lithography surface. In Figure 2 an example, the cleaning device 103 includes a housing 170 configured to house the oxygen source 130, the electron source 150, and the contaminant particle collector 160. The housing 170 includes one or more openings for allowing the emission of oxygen 138 and electrons 152 toward the lithography surface W and for allowing the attraction of the negatively charged contaminant particles 124 toward the contaminant particle collector 160. The oxygen source 130, the electron source 150, and the contaminant particle collector 160 may be arranged along the base 171 of the housing 170 and supported by the base 171. In Figure 2In the example, the oxygen source 130, the electron source 150, and the base 171 face downward and the lithography surface W faces upward, such that the cleaning device 103 and the lithography surface W are opposite each other along a vertical axis. It will be appreciated that different lithography apparatuses LA may be arranged in different ways, and the cleaning device 103 and the lithography surface W may be opposite each other along different directions or axes. For example, in Figure 1 the lithography apparatus, it can be seen that the second cleaning device 102 faces its associated lithography surface 14 along a non-vertical axis and a non-horizontal axis (e.g., a substantially diagonal axis). As another example, the first cleaning device 103 faces its associated lithography surface MA along a vertical axis. However, compared to the third cleaning device 103, the first cleaning device 101 faces upward while its associated lithography surface MA faces downward. In Figure 2 the example, the contaminant particle collector 160 is arranged at an angle relative to the oxygen source 130 and the electron source 150, such that the contaminant particle collector 160 faces the lithography surface W at an acute angle relative to the lithography surface W. The acute angle formed between the direction in which the contaminant particle collector 160 faces and the lithography surface W may be, for example, about 10° or greater. The acute angle formed between the direction in which the contaminant particle collector 160 faces and the lithography surface W may be, for example, about 75° or less.

[0072] The cleaning device 103 includes an actuation system 180, WT configured to generate relative movement between the cleaning device 103 and the lithography surface W. In Figure 2 the example, the actuation system 180, WT includes an actuator 180 configured to move the cleaning device 103 and a substrate table WT configured to move the substrate W. The actuator 180 may take any suitable form, such as a robotic arm, a step-and-scan platform (such as the step-and-scan platform for moving the patterning device MT and the substrate W), etc. The actuation system 180, WT may be capable of providing both a coarse and a fine adjustment of the relative positioning of the cleaning device 103 and the lithography surface W. The actuation system 180, WT may consist of only the actuator 180 or the substrate table WT. It will be appreciated that the actuation system 180, WT may take other forms. For example, referring to Figure 1 , the actuation system of the first cleaning device 101 may include Figure 2 an actuator 180 of the kind shown in Figure 2 and / or a support structure MT configured to support the patterning device MA. As another example, the actuation system of the second cleaning device 102 may include Figure 2 an actuator 180 of the kind shown in Figure 2 and / or an optical element actuator 185 configured to move the optical element 14. Each actuation system 180, MT, 185, WT may be configured such that a cleaning scan of the corresponding lithography surface MA, 14, W can be performed. An example of the cleaning scan direction 190 is shown in Figure 2 .

[0073] In Figure 2 the example, the actuator 180 moves the cleaning device 103 relative to the lithography surface W in the scan direction 190. The oxygen source 130, the electron source 150, and the contaminant particle collector 160 are arranged relative to each other such that the oxygen source 132 guides the electron source 150 in the scan direction 190 of the cleaning device 103. This arrangement ensures that the contaminant particles 120 present on the lithography surface W first undergo exposure to the oxygen 138 emitted by the oxygen source 130, thereby allowing the first step of the cleaning process (i.e., forming the oxide layer 140) to be performed first during the cleaning scan. The electron source 150 guides the contaminant particle collector 160 in the scan direction 190 of the cleaning device 103. That is, the electron source 150 follows the oxygen source 130 in the scan direction 190. This arrangement ensures that the oxidized contaminant particles 122 (which have been exposed to the oxygen 138 by the oxygen source 130) undergo exposure to the electrons 152 emitted by the electron source 150, thereby allowing the second step of the cleaning process (i.e., forming the negatively charged contaminant particles 124) to be performed a second time during the cleaning scan. Finally, the contaminant particle collector 160 follows the electron source 150 in the scan direction 190, thereby allowing the third step of the cleaning process (i.e., electromagnetically attracting the negatively charged contaminant particles 124 towards the contaminant particle collector 160) to be performed a third time during the cleaning scan. This arrangement advantageously allows at least a portion or at least one strip of the lithography surface W to be cleaned in the scan direction 190 in a single scan motion or "sweeping" manner.

[0074] The cleaning device 103 includes a sensor system 200 configured to detect cleaning parameters. The sensor system 200 may include pre-existing sensors present in the lithography apparatus LA. The sensor system 200 may include optical sensors such as time-of-flight sensors or cameras. The cleaning device 103 includes a controller 210 configured to control at least one of the oxygen source 130, the electron source 150, and the contaminant particle collector 160 at least in part depending on the cleaning parameters.

[0075] The cleaning parameters may include the distance 220 between the cleaning device 103 and the lithography surface W. The sensor system 200 may monitor the distance 220 between the cleaning device 103 and the lithography surface W, and the controller 210 may activate or deactivate one or more of the oxygen source 130, the electron source 150, and the contaminant particle collector 160 at least in part depending on the distance 220. For example, the controller 220 may be configured to activate the oxygen source 130, the electron source 150, and the contaminant particle collector 160 when the distance 220 detected by the sensor system 200 is about 1 mm or less. The inventors have found that this distance advantageously provides for the rapid formation of the oxide layer 140 while also reducing the unwanted dispersion of the oxygen 138 to other areas.

[0076] The cleaning parameter can be the alignment between the cleaning device 103 and the lithography surface W. The sensor system 200 can monitor the alignment (i.e., relative positioning) between the cleaning device 103 and the lithography surface W and detect the cleaning scan start position 230 and the cleaning scan end position 232. The controller 220 can be configured to activate one or more of the oxygen source 130, the electron source 150, and the contaminant particle collector 160 when the sensor system 200 indicates that the cleaning device 103 has reached the cleaning scan start position 230. The controller 220 can be configured to sequentially activate the oxygen source 130, the electron source 150, and the contaminant particle collector 160 when each of the oxygen source 130, the electron source 150, and the contaminant particle collector 160 reaches the cleaning scan start position 230. The controller 220 can be configured to deactivate one or more of the oxygen source 130, the electron source 150, and the contaminant particle collector 160 when the sensor system 200 indicates that the cleaning device 103 has reached the cleaning scan end position 232. The controller 220 can be configured to sequentially deactivate the oxygen source 130, the electron source 150, and the contaminant particle collector 160 when each of the oxygen source 130, the electron source 150, and the contaminant particle collector 160 reaches the cleaning scan end position 232.

[0077] The cleaning parameter can be the relative movement between the cleaning device 103 and the lithography surface W. The sensor system 200 can monitor the speed of the cleaning device 103 relative to the lithography surface W. The sensor system 200 can monitor the movement direction 190 of the cleaning device 103 relative to the lithography surface W. For example, the sensor system 200 can monitor the speed and direction 190 of the cleaning scan. The controller 220 can be configured to activate one or more of the oxygen source 130, the electron source 150, and the contaminant particle collector 160 when the sensor system 200 indicates that the cleaning device 103 has reached the desired scan speed and / or direction 190 relative to the lithography surface W. For example, the controller 220 can control the oxygen flow rate provided by the oxygen source 130, the current supplied to the electron source 150 (e.g., between about 100 µA and about 1000 µA), the bias voltage supplied to the contaminant particle trap 160, etc. The controller 220 can be configured to deactivate one or more of the oxygen source 130, the electron source 150, and the contaminant particle collector 160 when the sensor system 200 indicates that the cleaning device 103 has deviated from the desired scan speed and / or direction 190 relative to the lithography surface W.

[0078] The cleaning device 100c includes a power supply 172. The power supply 172 is configured to supply power to the electron source 150 and the contaminant particle collector 160. When the power supply 172 supplies power to the electron source 150, the electron source 1540 emits electrons 152. When the power supply 172 supplies power to the contaminant particle collector 160, the contaminant particle collector 160 becomes positively charged. The controller 210 may be configured to control the power supply 172 at least in part depending on the cleaning parameters detected by the sensing system 200. The power supply 172 may be configured to operate at an energy of 1 watt or less.

[0079] The cleaning device 103 includes one or more insulators 175a, 175b. In Figure 2 the example, the cleaning device includes a first insulator 175a between the oxygen source 130 and the electron source 150 and a second insulator 175b between the contaminant particle collector 160 and the base 171 of the housing 170. The cleaning device 103 may include a larger or smaller number of insulators 175a, 175b. The first insulator 175a is configured to electrically isolate the oxygen source 130 from the electron source 150 and / or the electrons 152. The second insulator 175b is configured to electrically isolate the housing 170 from the contaminant particle collector 160 and / or the negatively charged contaminant particles 124.

[0080] Figure 3 Schematically depicts a top view of a third cleaning device 103 according to the present disclosure Figure 1 As can be seen from Figure 3 the cleaning device 103 includes a plurality of oxygen sources, electron sources, and contaminant particle collectors arranged in a cleaning array (i.e., a plurality of portions 103a to 103y of the cleaning device 103). In Figure 3 the example, the cleaning array includes a five-by-five square array of twenty-five portions 103a to 103y of the cleaning device 103. Each portion 103a to 103y of the cleaning device 103 is configured to clean a corresponding portion Wa to Wy of the lithography surface W. Each cleaning portion 103a to 103y may include its own oxygen source, electron source, contaminant particle collector, and sensor system. A larger or smaller number of portions 103a to 103y may be provided. Different shaped arrays may be used. Generally, the number of portions 103 to 103y and / or the shape of the cleaning array may be selected at least in part depending on the shape and / or size of the lithography surface to be cleaned.

[0081] An actuation system (not shown) is configured to move the entire cleaning array such that each portion 103a to 103y of the cleaning device 103 moves co-ordinately. An example of a three-stage cleaning scan 191 to 193 is shown in Figure 3is shown. It will be appreciated that portions 103a to 103y of the cleaning device 103 can be moved in different directions and / or scanned a different number of times as needed to clean a particular lithography surface W. In Figure 3 the example, the starting scan positions of portions 103a to 103y of the cleaning device 103 are located at the lower left corners of the corresponding portions Wa to Wy of the lithography surface W. The starting scan positions can be changed. The first scan phase 191 includes moving portions 103a to 103y of the cleaning device 103 forward in a plane parallel to the lithography surface W such that portions 103a to 103y of the cleaning device 103 move from the lower left corners of portions Wa to Wy of the lithography surface W to the upper left corners of portions Wa to Wy of the lithography surface W. The oxygen source, electron source, and contaminant particle collector of portions 103a to 103y of the cleaning device 103 are activated during the first scan phase 191. The second scan phase 192 includes moving portions 103a to 103y of the cleaning device 103 backward and to the right in a plane parallel to the lithography surface W such that portions 103a to 103y of the cleaning device 103 move from the upper left corners of portions Wa to Wy of the lithography surface W to the lower right corners of portions Wa to Wy of the lithography surface W. The oxygen source, electron source, and contaminant particle collector of portions 103a to 103y of the cleaning device 103 can be deactivated during the second scan phase 192. The third scan phase 193 includes moving portions 103a to 103y of the cleaning device 103 forward in a plane parallel to the lithography surface W such that portions 103a to 103y of the cleaning device 103 move from the lower right corners of portions Wa to Wy of the lithography surface W to the upper right corners of portions Wa to Wy of the lithography surface W. The oxygen source, electron source, and contaminant particle collector of portions 103a to 103y of the cleaning device 103 are activated during the third scan phase 193. In Figure 3 the example, the ending scan positions of portions 103a to 103y of the cleaning device 103 are located at the lower right corners of the corresponding portions Wa to Wy of the lithography surface W. The ending scan positions can be changed.

[0082] The cleaning array advantageously enables the simultaneous cleaning of multiple different regions Wa to Wy of the lithography surface W, thereby reducing the amount of time required to clean the lithography surface W. For example, Figure 3The section of the lithography surface W shown may have a surface area of approximately 10 cm by approximately 10 cm. That is, each part Wa to Wy of the lithography surface W may have a surface area of approximately 2 cm by approximately 2 cm. Each part 103a to 103y of the cleaning device may have dimensions of approximately 1 cm by approximately 1 cm by approximately 1 cm. The actuation system 180 may be configured, for example, to provide a moving speed of approximately 1 meter per second between the cleaning device 103 and the lithography surface W. The cleaning device 103 may be capable of cleaning the Figure 3 section of the lithography surface W shown.

[0083] In Figure 3 the example of, the first scan phase 191 and the third scan phase 191 of the cleaning array are sufficient to clean the entire lithography surface W.

[0084] Figure 4 A flowchart showing a method of removing contaminant particles from a surface to be cleaned (such as a lithography surface). The first step 201 of the method includes oxidizing the contaminant particles and the surface to be cleaned. The second step 202 of the method includes negatively charging the oxidized contaminant particles and the surface to be cleaned. The third step 203 of the method includes using a positive charge to attract and thereby collect the negatively charged contaminant particles ejected from the surface to be cleaned.

[0085] Figure 4 The method of can form part of a method of processing a substrate. For example, the method of removing contaminant particles from the surface to be cleaned can be performed during the operation of a substrate processing device. For example, the method of removing contaminant particles from the surface to be cleaned can be performed during the emission of charged particles such as electrons in a charged particle device. As another example, the method of removing contaminant particles from the surface to be cleaned can be performed during the emission of soft x-rays in a soft x-ray device. As another example, the method of removing contaminant particles from the surface to be cleaned can be performed during the measurement of a substrate in a substrate metrology device. As another example, the method of removing contaminant particles from the surface to be cleaned can be performed during the inspection of a substrate in a substrate inspection device.

[0086] Figure 4 The method of can be used in combination with, for example, a lithography exposure performed when using Figure 1 a lithography apparatus LA. For example, such a method can include projecting a patterned radiation beam B' onto a substrate W and performing Figure 4 the method of. For example, the method of can be performed during the projection of the patterned radiation beam B' onto the substrate W Figure 4 (i.e., the method of removing contaminant particles 120 from the surface to be cleaned W).

[0087] Figure 5 Schematically depicts, according to the present disclosure, when cleaning a surface 250 different from Figure 2 the surface shown in Figure 2 a side view of a portion of a third cleaning device. The cleaning device 103a according to the present disclosure is configured to clean a surface 250 of a substrate W from which contaminant particles 120 emanate and travel to be processed by a substrate processing apparatus (not shown). In Figure 5 the example, the surface 250 of the substrate W from which contaminant particles 120 emanate and travel to be processed by the substrate processing apparatus is adjacent to the surface of the substrate W, and the substrate processing apparatus is Figure 1 a lithography apparatus LA. For example, the surface 250 may be a metal area adjacent to the substrate W where contaminant particles 120 may accumulate and then emanate and travel toward the substrate W. Figure 1 Any one of the cleaning devices 101 to 103 of

[0088] Figure 6 is configured to clean any surface of the lithography apparatus LA. For example, the first cleaning device 101 may be configured to clean a surface (not shown) adjacent to the patterning device MA from which contaminant particles may additionally emanate and travel to the patterning device MA. Surfaces from which contaminant particles 120 adjacent to the substrate W and / or the patterning device MA may emanate and travel toward the substrate W and / or the patterning device MA may be referred to in the art as critical surfaces. Figure 5 The cleaning device 300 of Figure 2 is the same as the cleaning device 103a of Figure 6Not to scale and specifically, the relative size of contaminant particles 120 has been increased for ease of understanding. Contaminant particles 120 can be generated during substrate processing, for example, by high-speed and / or accelerating movement of components of a substrate processing apparatus. Oxygen 138 reacts with contaminant particles 120 and the surface 310 to be cleaned and thereby oxidizes contaminant particles 120 and the surface 310 to be cleaned. Electrons 152 impart a negative charge to the oxidized contaminant particles 122 and the surface 310 to be cleaned (thereby creating negatively charged contaminant particles 124). The negatively charged contaminant particles 124 repel each other electromagnetically. The negatively charged surface 310 to be cleaned repels the negatively charged contaminant particles 124 electromagnetically. The force resulting from the electromagnetic repulsion causes the negatively charged contaminant particles 124 to be ejected or "jump" from the surface 310 to be cleaned. That is, the negatively charged contaminant particles 124 no longer adhere to the surface 310 to be cleaned. The contaminant particle collector 160 is configured to receive a positive charge and thereby attract the negatively charged contaminant particles 124 that have been ejected from the surface 310 to be cleaned electromagnetically. The electromagnetic attraction causes the negatively charged contaminant particles 124 to move towards and adhere to the contaminant particle collector 160 before the negatively charged contaminant particles 124 can move back towards the surface 310 to be cleaned and adhere to the surface 310 to be cleaned or move towards and adhere to any other surface (such as substrate W).

[0089] Compared to Figure 2 the arrangement of, Figure 5 the cleaning device 300 forms part of a substrate processing apparatus other than a lithographic apparatus and is for cleaning a surface 310 other than a lithographic surface. In Figure 6 an example of, the surface 310 from which contaminant particles 120 emanate and travel to the substrate 450 to be processed by the substrate processing apparatus is a voltage shield 310, and the substrate processing apparatus is a charged particle apparatus (reference Figure 7 shows and describes an example of a charged particle apparatus). The voltage shield 310 can be configured to protect the substrate 450 from unwanted discharges and / or arc discharges. The voltage shield 310 can be opposite the substrate 450. For example, the voltage shield 310 can be opposite the upper surface of the substrate 450. In Figure 6 the arrangement of, the cleaning device 300 is used to clean the critical surface of the substrate processing apparatus before contaminant particles 120 on the critical surface of the substrate processing apparatus can travel towards the substrate 450. Thus, the cleaning device 300 serves as a preventive measure to protect the substrate 450 from defects during processing and / or post-processing. The substrate processing apparatus can be a charged particle apparatus such as, for example, an electron beam apparatus. The substrate processing apparatus can be a soft x-ray apparatus. The substrate processing apparatus can be a substrate metrology apparatus. The substrate processing apparatus can be a substrate inspection apparatus.

[0090] A charged particle apparatus generally includes a charged particle source for emitting charged particles, electron optics for controlling and redirecting the charged particles, a substrate holder for positioning a substrate to interact with the charged particles, and a detector for capturing interaction products that may arise due to the interaction between the charged particles and the substrate in the case of an inspection or metrology system. The charged particle apparatus can be used to evaluate a substrate, such as inspecting a semiconductor wafer to detect defects in a pattern on and / or in the semiconductor wafer, or can be used for metrology to measure the dimensions of features that make up a pattern on and / or in the semiconductor wafer.

[0091] The particle source typically emits an extended beam of charged particles, such as electrons, in use. The electron beam that originates from the particle source and reaches the substrate is often also referred to as the primary beam of the charged particle system.

[0092] The electron optics can be configured to focus the charged particles (or the primary beam) onto the substrate (or semiconductor wafer), can be configured to reduce aberrations that may be present in the charged particle beam (or the primary beam), and / or can be configured to change the beam path of the charged particle beam (or the primary beam), for example to scan the charged particle beam across the substrate or to temporarily block the beam (temporarily blocking the beam refers to redirecting the primary beam into a beam trap to temporarily prevent the primary beam from reaching the substrate). To enable the electron optics to control and redirect the charged particles, the electron optics can include magnetic and / or electrostatic lenses and deflector elements in many different combinations. Generally, the extended charged particle beam from the source can first be collimated and then focused onto the substrate by the electron optics. The electron optics can be configured to control or redirect a single charged particle beam (also referred to as a single beam system) or to control or redirect multiple charged particle beams simultaneously (also referred to as a multi-beam system). In the case of multiple charged particle beams, the electron optics can include a macro lens in which a single macro lens interacts with multiple multi-charged particle beams, or can include one or more individual lens columns for each individual beam among the multiple charged particle beams, or a combination of a macro lens and individual lens columns that are either simultaneous or partially individual. A multi-beam system can include a single source that emits an extended charged particle beam that can be sliced into multiple individual beams that are redirected and focused onto the substrate by the electron optics. Alternatively, a multi-beam system can include multiple sources that can be referred to as a multi-column system, each of the multiple sources emitting a primary beam that is redirected and focused onto the substrate. Each primary beam in the multi-column system can be sliced into multiple individual beams such that each column in the multi-column system includes a multi-beam system.

[0093] During the interaction between the (multiple) primary beam and the substrate, interaction products are emitted from the substrate. In the case of an electron beam system, the interaction products can include X-rays and / or signal particles such as secondary electrons and / or backscattered electrons. The electron optical device can be configured to assist the secondary electrons and / or backscattered electrons to reach one or more detectors that may be present in the charged particle system. The electron optical device can for example include a beam separator (such as a Wien filter) to separate the primary beam electrons from the signal particles from the substrate and redirect (at least some of) the signal electrons into a secondary beam column that focuses these redirected signal electrons onto the detector. Alternatively, the detector can be integrated into the electron optical device (such as one or more in-lens detectors) (or even be part of the electron optical device). In such a configuration, the electron optical device can include elements configured to ensure that the signal electrons reach one or more detectors. The electron optical device can include for example one or more integrated detectors on a part of the electron optical device facing the substrate. This is a particularly beneficial configuration in a multi-beam system such that each beam in the multi-beam system has its own detector, which is for example arranged around the aperture from which the primary beam is emitted from the electron optical device towards the substrate. However, also in a single-beam charged particle system, the bottom electrode of the electron optical device can contain a detector that is often specifically arranged to detect relatively high energy backscattered electrons.

[0094] A charged particle device may include different types of detectors. A single charged particle device may include different combinations of different types of detectors. A first example of one type of detector may include a conversion material that converts impinging charged particles, such as (signal) electrons, into photons (also referred to as a scintillation material), for example using a YAG crystal. These converted photons may subsequently be measured using an optical detector, such as a photodiode or an array of photodiodes. The scintillation material may be applied, for example, directly on the surface of the (array of) photodiodes, or, for example, on the surface of an optical waveguide that may direct the photons generated by the scintillation material to the (array of) photodiodes. A second example of one type of detector includes a sensing diode or an array of sensing diodes that are specifically configured to directly convert impinging charged particles, such as (signal) electrons, into an electrical signal. This electrical signal is proportional to the charged particles or (signal) electrons that are collected. A third example of one type of detector is a charge detector and includes one or an array of charge capture electrodes (such as metal plates) that capture signal particles, such as (signal) electrodes that cause the charge to be measured. Such a charge detector can be beneficial especially when positioned adjacent to a substrate, since the detector surface can be integrated in a relatively straightforward manner on the substrate-facing part of an electron optical device. A fourth example of one type of detector may be configured to detect other types of interaction products, such as X-rays that may be generated by the interaction of a substrate with a relatively high electron beam. The collection of X-rays in a charged particle device may be used to identify, for example, the type of material that interacts with the primary beam. The collection of signal electrons caused by the interaction of the primary beam with a part of the substrate allows a charged particle system to generate an image representation of the part of the substrate. Such a generated image representation may be used to measure features (metrology) on the part of the substrate, or may be used to identify defective structures or particles by comparing the image representation with a reference (inspection).

[0095] Reference is now made to Figure 7 , Figure 7 which schematically depicts an exemplary configuration of a charged particle device in the form of a single beam electron beam system 400. The electron beam system 400 may include a source, which may include a cathode 403, an extractor electrode 402, a gun aperture 420, and an anode 422. The electron beam system 400 may further include an electron optical device that, in the example of Figure 7 includes a Coulomb aperture array 424, a condenser lens 426, a beam limiting aperture array 435, and an objective lens assembly 432. The electron beam system 400 also includes a detector that, in the example of Figure 7Examples include an electron detector 444 within the lens. The electron beam system 400 may include a substrate holder 436 supported by a motorized platform 434 to hold a substrate 450 (e.g., a semiconductor wafer that may be inspected or measured). It will be appreciated that other related components may be added or omitted as needed.

[0096] The electron source and / or condenser lens 426 and / or objective lens assembly 432 and / or beam limiting aperture array 435 and / or electron detector 444 may be aligned with the main optical axis 401 of the charged particle device 400. The electron detector 444 may be placed away from the main optical axis 401 along a secondary optical axis (not shown).

[0097] In Figure 7 Examples, the objective lens assembly 432 includes pole pieces 432a, a control electrode 432b, a beam manipulator assembly including deflectors 440a, 440b, 440c, 440d, and 440e, and an excitation coil 432d. In an exemplary imaging process, a primary electron beam 404 emitted from the tip of the cathode 403 is accelerated by an acceleration voltage applied to the anode 422. A portion of the primary electron beam 404 passes through the holes of the gun aperture 420 and the Coulomb aperture array 424 and is focused by the condenser lens 426 to pass entirely or partially through the holes of the beam limiting aperture array 435. The electrons passing through the holes of the beam limiting aperture array 435 may be focused to form a probe spot on the surface of the substrate 450 and deflected by one or more deflectors of the beam manipulator assembly to scan the surface of the substrate 450. Secondary electrons emitted from the substrate 450 may be collected by the electron detector 444 to form an image of the scanned area of the substrate 450.

[0098] In the objective lens assembly 432, the excitation coil 432d and the pole pieces 432a may be configured to generate a magnetic field. In use, a portion of the substrate 450 scanned by the primary electron beam 404 may be immersed in the magnetic field. In Figure 7 Examples, the control electrode 432b electrically isolated from the pole pieces 432a may control, for example, the electric field above and on the substrate 450 to reduce the aberration of the objective lens assembly 432 and control the focusing of signal electrons. One or more deflectors of the beam manipulator assembly may deflect the primary electron beam 404 to facilitate beam scanning on the substrate 450 to provide data for image reconstruction of different portions of the substrate 450.

[0099] In an alternative example of an electron beam system (not shown), there may be an aperture array provided at or near the position of the Coulomb aperture array 424, and the Coulomb aperture array 424 is configured to convert a primary beam from a source into a plurality of primary beams that can all be controlled and directed by macroscopic electron optical devices.

[0100] In another alternative example, the objective lens assembly can be fully or partially electrostatic, for example including one or more electrostatic elements. Such electrostatic elements can include one or more stacked plates in which one or more holes can be defined. These components can operate on the beam as lenses, deflectors, and / or correctors. One or more of the plates can be a large component (i.e., where holes are defined for the entire beam), a medium-sized component (i.e., where holes are defined for a selection of all different beams), or holes for each beam. An electron optical system including such an objective lens assembly or components of a charged particle device or any other component is shown and described in WO2022207265 (2022 / 07 / 26) which is incorporated herein by reference, where different electron optical designs and different electronic components include the disclosed electron optical devices and the electron optical components and elements included therein.

[0101] When interacting with the primary electron beam 404, backscattered electrons (BSE) and / or secondary electrons (SE) can be emitted from portions of the substrate 450. In one example, a beam separator (not shown) can direct the backscattered and / or secondary electrons to a sensor surface of an electron detector. In Figure 7 an example, the electron beam system 400 includes an in-lens electron detector 444. Signal electrons can be captured by the in-lens electron detector 444, which is configured to generate a signal (such as a voltage, current, etc.) representative of the intensity of the received signal electrons and provide the signal to a processing system such as the controller 455. The intensity of the secondary and / or backscattered electrons can vary depending on the external or internal structure of the substrate 450. By deflecting the primary electron beam 404 to different positions on the surface of the substrate 450, different intensities can be recorded by the electron detector 444 from which an image reflecting the internal or external structure of the substrate 450 can be reconstructed. Such an image can be used for inspection and / or metrology purposes.

[0102] In some examples, the controller 455 can control the motorized platform 434 to move the substrate 450 during inspection. In some examples, the controller 455 can control the motorized platform 434 to continuously move the substrate 450 at a constant speed in the scan direction. In other examples, the controller 455 can control the motorized platform 434 to vary the speed of movement of the substrate 450 over time depending on the steps of the desired scan process.

[0103] In particular, when the substrate 450 includes an organic material (such as cured or uncured resist), any of the components of the charged particle device 400 may be prone to contamination by contaminant particles or debris. The interaction between the charged particle beam 404 and the organic material may result in contamination (such as carbon deposition) on parts of the charged particle system 400. Such contamination may affect the operation of the charged particle system 400. For example, electrostatic lenses typically require a relatively high voltage difference across a relatively small distance. If contamination or debris is present on the components of such a lens, the contamination may trigger unwanted electrostatic discharges, which may in turn damage the charged particle system 400 and / or the substrate 450. Additionally, the charged particle system 400 often includes relatively small holes to define the beam or to create electrostatic lenses. Contamination can reduce the size of such holes or may even completely block the holes, which may affect the operation of the charged particle system 400. The deposition of contaminant particles on parts of the magnetic lens may negatively affect the strength and / or shape of the magnetic field generated by such a magnetic lens, which may in turn negatively affect the operation of the charged particle system 400. The deposition of contaminants on any of the detectors may reduce the efficiency of the detection of interaction products. The cleaning device 300 may be configured to clean any of the surfaces of the charged particle system 400 (such as a voltage shield plate ( Figure 7 not shown in) on which contaminant particles have accumulated. The controller 455 may be configured to control the cleaning device 300.

[0104] WO2022207265, which is incorporated herein by reference, discloses an example of a particle collection device. Such a particle collection device is disclosed merely as an example of collecting contaminant particles from a substrate and / or a substrate support. Other designs and configurations of particle collection devices may be used to collect particles from any other surface of the substrate processing equipment disclosed herein.

[0105] Although the use of a lithography apparatus in IC manufacturing may be specifically referred to herein, it should be understood that the lithography apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guiding and detecting patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

[0106] Although embodiments of the present invention may be specifically referred to herein in the context of a lithography apparatus, embodiments of the present invention may be used in other devices. Embodiments of the present invention may form part of a mask inspection device, a metrology device, or any device for measuring or processing an object such as a wafer (or other substrate) or a mask (or other patterning device). These devices may generally be referred to as lithography tools. Such lithography tools may use vacuum conditions or ambient (non-vacuum) conditions.

[0107] While the foregoing may have specifically referred to the use of embodiments of the present invention in the context of optical lithography, it will be understood that, where the context permits, the present invention is not limited to optical lithography and can be used in other applications (such as imprint lithography).

[0108] Embodiments of the present invention can be implemented in hardware, firmware, software, or any combination thereof, where the context permits. Embodiments of the present invention can also be implemented as instructions stored on a machine-readable medium, which can be read and executed by one or more processors. A machine-readable medium can include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium can include: read-only memory (ROM); random access memory (RAM); magnetic storage media; optical storage media; flash memory devices; electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.); and the like. Additionally, firmware, software, routines, instructions can be described herein as performing certain actions. However, it should be understood that these descriptions are for convenience only, and these actions are actually caused by a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., and so doing may cause an actuator or other device to interact with the physical world.

[0109] While specific embodiments of the present invention have been described above, it will be understood that the present invention can be practiced in other ways different from those described. The above description is intended to be illustrative, not restrictive. Thus, those skilled in the art will appreciate that the present invention can be modified without departing from the scope of the claims as described.

[0110] Aspect

[0111] 1. A cleaning device for removing contaminant particles from a lithography surface to be cleaned, the cleaning device comprising:

[0112] An oxygen source configured to emit oxygen and thereby oxidize the contaminant particles and the lithography surface to be cleaned;

[0113] An electron source configured to emit electrons and thereby negatively charge the oxidized contaminant particles and the lithography surface to be cleaned; and,

[0114] A contaminant particle collector configured to receive positive charge and thereby attract the negatively charged contaminant particles ejected from the lithography surface to be cleaned.

[0115] 2. The cleaning device according to aspect 1, wherein the cleaning device is configured to be positioned opposite the lithography surface to be cleaned.

[0116] 3. The cleaning device according to any one of the foregoing aspects, comprising an actuation system configured to generate relative movement between the cleaning device and the lithographic surface to be cleaned.

[0117] 4. The cleaning device according to aspect 3, wherein the oxygen source, the electron source, and the contaminant particle collector are arranged relative to each other such that:

[0118] the oxygen source guides the electron source in the scanning direction of the cleaning device; and,

[0119] the electron source guides the contaminant particle collector in the scanning direction of the cleaning device.

[0120] 5. The cleaning device according to any one of the foregoing aspects, comprising:

[0121] a sensor system configured to detect cleaning parameters; and,

[0122] a controller configured to control at least one of the oxygen source, the electron source, and the contaminant particle collector at least partially depending on the cleaning parameters.

[0123] 6. The cleaning device according to aspect 5, wherein the cleaning parameters are at least one of the following:

[0124] the distance between the cleaning device and the lithographic surface to be cleaned;

[0125] the alignment between the cleaning device and the lithographic surface to be cleaned; and,

[0126] the relative movement between the cleaning device and the lithographic surface to be cleaned.

[0127] 7. The cleaning device according to any one of the foregoing aspects, wherein the contaminant particle collector is arranged at an angle relative to the oxygen source and the electron source such that an acute angle is formed between the direction facing the contaminant particle collector and the lithographic surface.

[0128] 8. The cleaning device according to aspect 7, wherein the acute angle is in the range of about 10° to about 75°, including the end values 10° and 75°.

[0129] 9. The cleaning device according to any one of the foregoing aspects, comprising:

[0130] a first insulator located between the oxygen source and the electron source; and,

[0131] A second insulator, which is located between the contaminant particle collector and the housing of the cleaning device,

[0132] wherein the first insulator is configured to electrically isolate the oxygen source from the electron source and / or the electrons, and the second insulator is configured to electrically isolate the housing from the contaminant particle collector and / or the negatively charged contaminant particles.

[0133] 10. The cleaning device according to any one of the preceding aspects, comprising a plurality of oxygen sources, electron sources, and contaminant particle collectors arranged in an array for cleaning.

[0134] 11. A lithographic apparatus arranged to condition electromagnetic radiation and project a pattern from a patterning device onto a substrate, comprising a cleaning device according to any one of the preceding aspects.

[0135] 12. The lithographic apparatus according to aspect 11, wherein the cleaning device is configured to clean at least one of:

[0136] the patterning device;

[0137] the substrate; and

[0138] an optical element configured to interact with the electromagnetic radiation.

[0139] 13. A method of removing contaminant particles from a lithographic surface to be cleaned, the method comprising:

[0140] oxidizing the contaminant particles and the lithographic surface to be cleaned;

[0141] negatively charging the oxidized contaminant particles and the lithographic surface to be cleaned; and

[0142] using a positive charge to attract and thereby collect the negatively charged contaminant particles ejected from the lithographic surface to be cleaned.

[0143] 14. A method comprising:

[0144] projecting a patterned radiation beam onto a substrate; and

[0145] performing the method according to aspect 13.

[0146] 15. The method according to aspect 14, wherein the method of removing contaminant particles from the lithographic surface to be cleaned is performed during the projection of the patterned radiation beam onto the substrate.

Claims

1. A cleaning device for removing contaminant particles from a surface to be cleaned, the cleaning device comprising: an oxygen source configured to emit oxygen and thereby oxidize the contaminant particles and the surface to be cleaned; an electron source configured to emit electrons and thereby negatively charge the oxidized contaminant particles and the surface to be cleaned; and, a contaminant particle collector configured to receive a positive charge and thereby attract the negatively charged contaminant particles ejected from the surface to be cleaned.

2. The cleaning device according to claim 1, wherein, the cleaning device is configured to be positioned opposite to the surface to be cleaned.

3. The cleaning device according to any one of the preceding claims, comprising: an actuation system configured to generate relative movement between the cleaning device and the surface to be cleaned.

4. The cleaning device according to claim 3, wherein, the oxygen source, the electron source and the contaminant particle collector are arranged relative to each other such that: the oxygen source guides the electron source in the scanning direction of the cleaning device; and, the electron source guides the contaminant particle collector in the scanning direction of the cleaning device.

5. The cleaning device according to any one of the preceding claims, comprising: a sensor system configured to detect cleaning parameters; and, a controller configured to control at least one of the oxygen source, the electron source and the contaminant particle collector at least partially depending on the cleaning parameters.

6. The cleaning device according to claim 5, wherein, the cleaning parameters are at least one of the following: the distance between the cleaning device and the surface to be cleaned; the alignment between the cleaning device and the surface to be cleaned; and, the relative movement between the cleaning device and the surface to be cleaned.

7. The cleaning device according to any one of the preceding claims, wherein, the contaminant particle collector is arranged at an angle relative to the oxygen source and the electron source such that an acute angle is formed between the direction facing the contaminant particle collector and the surface.

8. The cleaning device according to claim 7, wherein, the acute angle is in the range of about 10° to about 75° including the end values 10° and 75°.

9. The cleaning device according to any one of the preceding claims, comprising: a first insulator located between the oxygen source and the electron source; and, a second insulator located between the contaminant particle collector and the housing of the cleaning device, wherein the first insulator is configured to electrically isolate the oxygen source from the electron source and / or the electrons, and the second insulator is configured to electrically isolate the housing from the contaminant particle collector and / or the negatively charged contaminant particles.

10. The cleaning device according to any one of the preceding claims, comprising: a plurality of oxygen sources, electron sources and contaminant particle collectors arranged as a cleaning array.

11. A substrate processing apparatus comprising the cleaning device according to any one of the preceding claims.

12. The substrate processing apparatus according to claim 11, wherein, the surface to be cleaned is the surface from which the contaminant particles emanate and travel to the substrate to be processed by the substrate processing apparatus.

13. The substrate processing apparatus according to claim 12, wherein, the surface to be cleaned is at least one of the following: a surface adjacent to a patterning device configured to impart a pattern to radiation; a surface adjacent to the substrate configured to receive a patterned radiation beam; and, a voltage shield configured to protect the substrate.

14. A method of removing contaminant particles from a surface to be cleaned, the method comprising: oxidizing the contaminant particles and the surface to be cleaned; negatively charging the oxidized contaminant particles and the surface to be cleaned; and, using a positive charge to attract and thereby collect the negatively charged contaminant particles ejected from the surface to be cleaned.

15. A method of processing a substrate, comprising the method according to claim 14.

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