CN113363126A - Particle beam system, method of operating a particle beam system and computer program product - Google Patents

Particle beam system, method of operating a particle beam system and computer program product Download PDF

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Publication number
CN113363126A
CN113363126A CN202110237457.4A CN202110237457A CN113363126A CN 113363126 A CN113363126 A CN 113363126A CN 202110237457 A CN202110237457 A CN 202110237457A CN 113363126 A CN113363126 A CN 113363126A
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gas
sample
particle beam
vacuum chamber
temperature
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CN202110237457.4A
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CN113363126B (en
Inventor
A.施曼兹
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Carl Zeiss Microscopy GmbH
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Carl Zeiss Microscopy GmbH
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/026—Means for avoiding or neutralising unwanted electrical charges on tube components
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
    • H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/3002—Details
    • H01J37/3005—Observing the objects or the point of impact on the object
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/317—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/20—Positioning, supporting, modifying or maintaining the physical state of objects being observed or treated
    • H01J2237/2001—Maintaining constant desired temperature

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Sampling And Sample Adjustment (AREA)

Abstract

The invention relates to a particle beam system (1) allowing processing of a cryogenic sample (5) by means of a gas (45) and a method for operating a particle beam system (1). According to the invention, gas is released in a locally limited manner in the vicinity of the surface of the sample (5) in the vacuum chamber (29) of the particle beam system (1). The temperature of the gas (45) is adapted to the temperature of the sample (5). If appropriate, the gas (45) is cooled, for example, by a heat exchanger (51) which is arranged in the vacuum chamber 29) of the particle beam system (1) and cools the gas (45) by means of a cooling medium or by means of a cooling element.

Description

Particle beam system, method of operating a particle beam system and computer program product
Technical Field
The present invention relates to a particle beam system, a method for operating a particle beam system, and a computer program product. In particular, the present invention relates to a particle beam system and a method for operating the particle beam system, by which a sample irradiated with the particle beam system can be treated with a treatment gas, the sample being a low temperature sample, the temperature of which is typically well below 0 ℃, e.g. in the range of-100 ℃ to-200 ℃ or the like. The low temperature water sample is often at a temperature below-135 c, such as about-150 c or less, to avoid undesirable crystal formation.
Background
When inspecting a sample, in particular a non-conductive sample, by using a particle beam system, in particular an electron beam system, the sample may be locally charged by irradiating the sample with a particle beam generated by the particle beam system. This results in an uneven charge distribution in the sample. This charge distribution in the sample affects the particle beams that impinge on the sample, are generated by the particle beam system, and leave the sample due to the interaction of the particle beams with the sample (e.g., backscattered electrons, secondary electrons, etc.). This has the following effect: degrading the quality of the sample image recorded by the particle beam system.
A number of different methods are known to minimize the overall adverse effects of sample charging. For example, the surface of the sample may be coated with a thin layer made of a conductive material so that charges can be dissipated via the layer.
Another conventional method consists in compensating the charging by means of a gas provided locally on part of the surface of the sample. This gas can be ionized by the particle beam of the particle beam system and by the particles leaving the sample. The ions and free charges generated in this way near the part of the surface act to compensate for the sample charging. Charge compensation by supplying a suitable gas to the sample is typically only used for samples at room temperature.
The charge compensation method just described is not applicable to cryogenic samples (i.e., samples having temperatures well below 0 ℃ C.) because the room temperature gas provided for charge compensation warms the cryogenic sample to the point that the cryogenic sample undergoes irreparable damage.
For the same reason, other conventional methods for processing gases of a sample (e.g., for removing material from and depositing material onto the sample) cannot be readily applied to low temperature samples.
Disclosure of Invention
It is an object of the present invention to provide a particle beam system and a method for operating a particle beam system, by which a low temperature sample can be efficiently treated with gas. In particular, it is an object of the invention to provide a particle beam system and a method for operating a particle beam system, by which charging of a cryogenic sample can be reduced and the cryogenic sample can be treated with a treatment gas.
According to a first aspect, the object is achieved by a particle beam system, in particular a particle beam microscope, comprising: a vacuum chamber having a chamber wall; a particle beam column for irradiating a partial surface of a sample disposed in the vacuum chamber with a particle beam of charged particles; and gas supply line means for guiding gas to the portion of the surface of the sample arranged in the vacuum chamber; the gas supply line device includes: a gas line for directing the gas, the gas line having an outlet disposed in the vacuum chamber; and a heat exchanger disposed in the vacuum chamber for cooling the gas guided in the gas line.
The vacuum chamber encloses a volume with its chamber walls. When a sample is to be examined with the particle beam system, the sample is arranged in the volume. In order to examine a sample with a particle beam system, a vacuum is generated in a vacuum chamber, for example by means of a vacuum pump, so that the particle beam can impinge on the sample as undisturbed as possible and therefore particles leaving the sample can be detected efficiently.
The particle beam column is configured to generate a particle beam and to direct the particle beam onto a sample, whereby the sample is irradiated by the particle beam. The particle beam impinges on the surface of the sample. The particle beam may be formed of electrons and, correspondingly, the particle beam system may be an electron beam system. Alternatively, the particle beam may be formed of ions, and accordingly the particle beam system may be an ion beam system.
The gas supply line arrangement is configured to supply gas to a partial surface of a sample arranged in the vacuum chamber. Directing the gas to the portion of the surface of the sample means that the gas is provided in a spatially substantially restricted area near the surface of the sample. The volume of gas that can be supplied by the gas supply line arrangement is very small compared to the volume of the vacuum chamber.
The gas may vary depending on the application. To cause charge compensation, the gas is, for example, an inert gas (e.g., nitrogen). To deposit material onto the sample, the gas may be a process gas, which may itself be reactive or may be made reactive by interaction with the particle beam, and thus deposit material from the process gas onto the sample. To remove material from the sample (etching process), the gas may be a reactive process gas, such as oxygen. The process gas, ionized by interaction with the particle beam, can remove material from the sample.
In order to be able to provide gas in a small volume near the surface of the sample, the gas supply line arrangement comprises a gas line with an outlet, which is arranged in the vacuum chamber. The gas line is configured to direct gas to the outlet. The gas line thus allows gas to be directed to a specific location within the vacuum chamber near the surface of the sample where the gas exits the gas line through its outlet and enters the volume of the vacuum chamber. Thus, the gas is guided into the vacuum chamber, where it can play its role in the area around the outlet of the gas line.
The gas supply line arrangement further comprises a heat exchanger, which is arranged in the vacuum chamber. The heat exchanger is configured to cool a gas directed in the gas line. The cooling of the gas can be performed by cooling the gas line through a heat exchanger, whereby the gas in the gas line is also cooled. The cooling of the gas by using a heat exchanger can be performed by a cooling medium or a coupling element which is itself cold and/or cooled. In the heat exchanger, thermal energy is exchanged between the gas and the heat exchanger by the process of thermal interaction. The heat exchanger itself may be cooled by a cooling medium delivered to the heat exchanger or by a coupling element thermally connected to the heat exchanger, whereby the gas is also cooled. Thus, the temperature of the gas measured at the outlet of the gas line can be set such that the sample is not warmed, or is only slightly warmed or even cooled by the gas. In this way, the effect of the gas supply can take place without damaging the cryogenic sample by the gas supply.
The particle beam system may include a cooling device configured to cool the sample. The cooling device is used to set the temperature of the cryogenic sample in order to prevent the cryogenic sample from being warmed by its surroundings. The cooling device, the gas supply line device, and the heat exchanger are different devices from each other.
Before, during, and/or after irradiating the portion of the surface of the sample with the particle beam, gas may be directed onto the portion of the surface of the sample by using a gas supply line device, thereby making the effect provided by the gas possible.
During the irradiation of the portion of the surface of the sample with the particle beam, particles that have left the sample as a result of the irradiation may be detected with a detector. The detector may be configured to output an output signal, the output signal being generated in dependence on the detected particles. For example, in this way, an image of the portion of the surface of the sample is recorded by the particle beam system.
According to one embodiment, the gas supply line arrangement further comprises: a supply line passing through the chamber wall for conducting cooling medium from a cooling medium source arranged outside the vacuum chamber to the heat exchanger, and/or a return line passing through the chamber wall for conducting cooling medium from the heat exchanger to a cooling medium sink arranged outside the vacuum chamber. In this case, the cooling medium cools the gas carried in the gas line by means of a heat exchanger. The cooling medium may be gaseous or liquid.
The supply line and the return line may be formed of materials suitable for very low temperatures. These lines are formed of Teflon, for example.
In this embodiment, the cooling medium may be provided in a cooling medium source arranged outside the vacuum chamber. In order to be able to guide the cooling medium from the cooling medium source to the heat exchanger inside the vacuum chamber, the gas supply line arrangement comprises a supply line. The supply line is configured to direct the cooling medium from the cooling medium source to the heat exchanger inside the vacuum chamber. In this case, the cooling medium does not leave the supply line. This avoids contamination of the vacuum created in the vacuum chamber by the cooling medium. The supply line passes through a chamber wall of the vacuum chamber. The supply line may be constituted by a plurality of separate lines and connections and should be understood to mean a functional element which may be constituted by a plurality of different separate parts.
The supply line carries the cooling medium to a heat exchanger, in which the cooling medium cools the gas guided in the gas line. As a result, the cooling medium is warmed in the heat exchanger. The warmed cooling medium is led from the heat exchanger through a return line to a cooling medium tank. The cooling medium tank is disposed outside the vacuum chamber. Accordingly, the return line passes through a chamber wall defining the vacuum chamber. In this case, the cooling medium does not leave the return line. This avoids contamination of the vacuum created in the vacuum chamber by the cooling medium. The return line passes through a chamber wall of the vacuum chamber. The return line may be constituted by a plurality of separate lines and connections and should be understood to mean a functional element which may be constituted by a plurality of different separate parts.
According to another embodiment, the gas supply line arrangement further comprises a heat exchanger flow valve for setting the flow rate of the cooling medium through the heat exchanger. The heat exchanger flow valve is configured to set a flow rate of the cooling medium through the heat exchanger. As a result, the cooling capacity of the heat exchanger can be set. The heat exchanger flow valve may be controlled by a controller of the particle beam system.
According to another embodiment, the supply line, the heat exchanger and the return line form a closed flow channel for the cooling medium. The closed flow channel has no opening in the vacuum chamber. Accordingly, the cooling medium does not exit the flow channels and remains within the flow channels as it passes through the vacuum chamber. Accordingly, the vacuum generated in the vacuum chamber is not contaminated by the cooling medium. In terms of guidance, the gas line and the flow channel can be separated from each other. This means that the cooling medium guided in the channel and the gas guided in the gas line are carried separately.
According to an alternative embodiment, the supply line or the return line has a branch to which the gas line is connected. At the branch, a part of the cooling medium carried in the supply line or the return line enters the gas line. Accordingly, the gas is provided by the cooling medium itself. In this case, the gas and the cooling medium are, for example, nitrogen. In this embodiment, the cooling medium for cooling the gas and the gas itself are conveyed through a common line (supply line) which passes through the chamber wall of the vacuum chamber.
According to another embodiment, the particle beam system further comprises a cooling device arranged outside the vacuum chamber for cooling the coupling element, which passes through the chamber wall and is thermally coupled with the heat exchanger. In this embodiment, the gas or heat exchanger in the vacuum chamber is not cooled by a liquid or gaseous cooling medium, but by a coupling element in the solid state of aggregation. For this purpose, the coupling element is thermally connected with the heat exchanger in an efficient manner. The coupling element extends through a chamber wall of the vacuum chamber and can thus be cooled outside the vacuum chamber by the cooling device. The cooling device may be, for example, a Dewar flask (Dewar flash) or a cooled heat exchanger.
According to another embodiment, the gas line passes through a chamber wall of the vacuum chamber. In this embodiment, the gas is provided outside the vacuum chamber and is directed onto the partial surface of the sample from outside the vacuum chamber through a gas line passing through a chamber wall of the vacuum chamber.
According to another embodiment, the gas supply line arrangement further comprises a gas supply line valve for setting a flow rate of the gas through the gas line. The gas line valve is configured to set a flow rate of gas through the gas line. Thus, the flow rate of the gas at the outlet of the gas line can be set. This in turn affects the contamination of the vacuum provided in the vacuum chamber, the effectiveness of the action of the gas, and also the cooling of the gas by the heat exchanger. The gas line valve may be controlled by a controller of the particle beam system. The gas line valve may be arranged inside or outside the vacuum chamber.
According to another embodiment, the particle beam system further comprises a controller configured to control the cooling capacity of the heat exchanger. In particular, the controller may control the cooling capacity of the heat exchanger according to the temperature of the heat exchanger and/or according to the temperature of the (outlet) gas and/or according to the temperature of the sample and/or according to the temperature of a sample stage carrying the sample in the vacuum chamber. In embodiments where the use of a cooling medium is contemplated, the controller may control the cooling capacity of the heat exchanger based on the temperature of the cooling medium. In embodiments where the use of a coupling element is contemplated, the controller may control the cooling capacity of the heat exchanger based on the temperature of the coupling element.
The controller may set the cooling capacity of the heat exchanger, for example, by correspondingly controlling the gas line valve and/or the heat exchanger flow valve and/or the cooling device cooling the coupling element (e.g., an operating parameter of the cooling device, such as a flow rate of a cooling medium in the cooling device for cooling the coupling element, a temperature of the cooling medium in the cooling device for cooling the coupling element, etc.). In order to set the cooling capacity of the heat exchanger, the controller uses, for example, the temperature of the heat exchanger itself, which can be detected by means of a temperature sensor. Additionally or alternatively, the temperature of the gas and/or the temperature of the cooling medium and/or the temperature of the coupling element may be measured by means of a corresponding temperature sensor and used to control the cooling capacity of the heat exchanger by means of a controller.
The controller may control the cooling capacity of the heat exchanger such that the temperature of the heat exchanger or the temperature of the (outlet) gas tends towards a predetermined value. The predetermined value may be a dedicated value based on the sample to be analyzed and the analysis/manipulation method to be used. For example, a low temperature water sample should be maintained at a temperature below-135 ℃; therefore, the predetermined value should be at or below-135 ℃.
The predetermined value may be or depend on the (current) temperature of the sample. For example, considering a case where the temperature of the sample is changed during analysis/operation (e.g., by controlling the temperature of a sample stage carrying the sample) and the gas (e.g., provided for charge compensation, etching, and generally processing the sample) should not change the temperature of the sample, the gas temperature must be changed according to the changing temperature of the sample. Thus, the predetermined value may be the temperature of the sample.
The temperature of the sample may be obtained by direct or indirect measurement. For example, a temperature sensor may be placed in or near the sample to directly measure the temperature of the sample. Such a temperature sensor may be realized, for example, by a resistance thermometer. In particular, the temperature of the sample may be measured contactlessly, for example using an infrared thermometer. According to another example, the temperature of the sample may be represented by and estimated based on the temperature of a sample stage carrying the sample, wherein the temperature of the sample stage may be measured by a temperature sensor, for example. Alternatively, the predetermined value may be a value within a predetermined range with respect to the temperature of the sample, i.e. the predetermined value may be determined in dependence on the temperature of the sample. For example, the predetermined value may be determined to be a value lower than the temperature of the sample by a predetermined amount.
According to another embodiment, the particle beam system further comprises a positioning device for setting the position of the outlet of the gas line in the vacuum chamber. In this embodiment, the outlet of the gas line may be positioned in the vacuum chamber by a positioning device. This allows the outlet of the gas line to be arranged near the surface of the sample and near the region on which the particle beam at the surface of the sample is directed.
According to another aspect, the object is achieved by a method for operating a particle beam system, the method comprising: disposing a sample in a vacuum chamber of the particle beam system; irradiating a portion of a surface of the sample disposed in the vacuum chamber with a beam of charged particles; and directing a gas having a temperature below 0 ℃ to the portion of the surface of the sample disposed in the vacuum chamber.
Before, during, and/or after illuminating the portion of the surface of the sample, gas is directed to the portion of the surface of the sample. The gas may be an inert gas (e.g., nitrogen) or a reactive gas (e.g., oxygen). The temperature of the gas may be below-50 ℃ or below-100 ℃ or below-150 ℃ and is selected according to the temperature of the sample.
The gas can be directed to the partial surface by means of a gas line, the gas leaving the gas line at the outlet of the gas line towards the partial surface. The temperature of the gas may refer to the temperature of the gas at the outlet.
By this method, cold samples, in particular cryogenic samples, can be examined and processed with a particle beam system. In this case, the gas exerts its effect without damaging the cold sample by warming.
According to another embodiment, the temperature of the gas is at most 50 ℃ higher than the temperature of the sample, preferably at most 20 ℃ higher than the temperature of the sample, more preferably at most 10 ℃ higher than the temperature of the sample, still more preferably at most 5 ℃ higher than the temperature of the sample when the gas is directed to the part of the surface (i.e. at the outlet of the gas line). Alternatively, the temperature of the gas is lower than the temperature of the sample when the gas is directed to the portion of the surface (i.e., at the outlet of the gas line). This ensures that the sample is not warmed, or only slightly warmed or even cooled by the supply of gas. As a result, the cryogenic sample can be inspected and processed with the particle beam system, and it is also possible to avoid the cryogenic sample from being warmed and damaged due to the supply of gas.
According to another embodiment, the temperature of the sample is below 0 ℃ or below-50 ℃ or below-100 ℃ or below-150 ℃. In particular, the specified temperature is achieved during irradiation with the particle beam and/or during the introduction of the gas to the partial surface. These are the customary temperatures for cold and cryogenic samples. To keep the temperature of the sample low during inspection and processing with the particle beam system, or to cool the sample, the sample may be cooled with a gas or sample cooling device. For example, the sample may be cooled by a cooled sample holder, cooling fingers, cold surface areas, Peltier elements, or the like. In this case, the temperature of the sample may be adjusted to a predetermined temperature specific to the sample.
According to another embodiment, the method further comprises cooling the gas in the vacuum chamber by means of a heat exchanger. As described above, the heat exchanger itself can be cooled by means of a cooling medium or by means of a coupling element. The cooling of the gas is such that the gas has a temperature so low that the cryogenic sample is not damaged by the gas and the gas can still perform its function. Furthermore, the gas does not have to be provided in a cold state itself, since it is cooled before reaching the outlet. The cooling of the gas is performed in a vacuum chamber. This achieves the effect that the gas is not warmed, or only slightly warmed, by the ambient environment between the cooling gas and the part of the surface supplied to the sample.
According to another embodiment, the method further comprises: a heat exchanger directing a cooling medium into a supply line passing through the chamber wall of the vacuum chamber, the cooling medium having a temperature below-50 ℃ or below-100 ℃ or below-150 ℃.
Accordingly, the cooling medium is guided into the vacuum chamber already at a low temperature in the supply line. The cooling medium may be gaseous or liquid. The cooling medium may be an inert gas, such as nitrogen.
According to another embodiment, the method further comprises: a gas is directed in a gas line that passes through a chamber wall of the vacuum chamber, the temperature of the gas as it passes through the chamber wall being higher than the temperature of the gas as it is directed to the partial surface (i.e., the outlet of the gas line). In particular, the temperature of the gas as it passes through the chamber walls is higher than 0 ℃.
In this embodiment, the gas is provided outside the vacuum chamber and its temperature is then higher than the temperature of the gas at the outlet of the gas line in the vacuum chamber. For example, the temperature of the gas outside the vacuum chamber or as it passes through the chamber walls of the vacuum chamber in the gas line is above 0 ℃ or about room temperature between 15 ℃ and 30 ℃. The gas, which is warmer with respect to the temperature at the outlet of the gas line, is guided in the gas line through the chamber wall of the vacuum chamber and fed to a heat exchanger, in which it is cooled. The gas thus cooled is directed through the outlet of the gas line to the desired portion of the surface.
According to an alternative embodiment, the method further comprises: providing the gas by using a portion of a cooling medium supplied to the heat exchanger to cool the gas in the vacuum chamber; and returning another portion of the cooling medium from the vacuum chamber in a return line through a chamber wall of the vacuum chamber. The gas can be separated off from the cooling medium before or after cooling.
In this embodiment, the gas is provided by the cooling medium itself or a portion thereof. For example, part of the cooling medium is tapped off into the gas line from the supply line or the return line of the previously described gas supply line arrangement. This portion then acts as a gas. This also means that the cooling medium is usually gaseous, the flow rate of the cooling medium through the vacuum chamber in the supply/return line being much higher than the flow rate of the gas through the outlet of the gas line. Accordingly, usually only part of the cooling medium is tapped off to provide the gas. The remaining or another part of the cooling medium is guided out of the vacuum chamber again (to be precise in a return line through the chamber walls of the vacuum chamber). Thus, separate gas lines need not be provided to provide gas through the chamber walls of the vacuum chamber.
According to another alternative embodiment, the method further comprises: the heat exchanger is cooled by a coupling element which passes through a chamber wall of the vacuum chamber and is cooled by a cooling device arranged outside the vacuum chamber. In this embodiment, the heat exchanger arranged in the vacuum chamber is cooled by the coupling element, which in turn is cooled by a cooling device arranged outside the vacuum chamber. The cooling of the gas is thus caused indirectly by the coupling element, which is in the solid state of aggregation and which passes through the chamber walls of the vacuum chamber.
Another aspect of the invention relates to a computer program product comprising computer readable instructions which, when executed by a controller of a particle beam system, cause the particle beam system to perform the method described herein. The particle beam system may be one of the particle beam systems described herein.
The computer program product may be a computer program physically embodied on an information carrier. The information carrier may be, for example, a machine-readable storage medium. Alternatively, the computer program may be implemented by means of signals which may be received, stored and processed by a data processing device, in particular a controller, a processor, one or more computers.
Drawings
Embodiments of the present invention will be explained in more detail below based on the drawings.
Fig. 1 shows a schematic representation of a particle beam system with a gas supply line arrangement.
Fig. 2 shows a schematic representation of another embodiment of a gas supply line arrangement.
Fig. 3 shows a schematic representation of a further embodiment of a gas supply line arrangement.
Fig. 4 shows a schematic representation of a further embodiment of a gas supply line arrangement.
Fig. 5 shows a schematic representation of another particle beam system with the gas supply line arrangement shown in fig. 1.
Detailed Description
Fig. 1 shows, by way of example, a particle beam system 1 suitable for carrying out the method described herein, in particular for analyzing and/or processing a sample 5.
The particle beam system 1 comprises a particle beam column 3. The particle beam column 3 comprises a particle source 7 configured to generate a particle beam 9. The particle beam 9 is formed, for example, by electrons or ions.
The particle beam column 3 further comprises a suppression electrode 11 to which an electrical potential can be applied in such a way that only those particles generated by the particle source 7 with sufficient kinetic energy can pass through an opening 13 in the suppression electrode 11.
The particle beam column 3 further comprises an accelerating electrode 15 to which an electrical potential can be applied in order to accelerate particles passing through the opening 13 in the suppression electrode 11 to a predetermined kinetic energy.
The particle beam column 3 further comprises a particle-optical lens 17 adapted to focus the particle beam 9 onto the sample 5.
The particle beam column 3 further comprises a deflection system 19 adapted to deflect the particle beam 9 such that the particle beam 9 can be directed onto different locations of the surface of the sample 5. The deflection system 19 may be adapted to deflect the particle beam 9 in two mutually perpendicularly oriented directions, which in turn are each oriented perpendicularly to the main axis 21 of the particle-optical lens 17.
The particle beam system 1 further comprises a controller 23 adapted to control the particle beam column 3. The controller 23 is configured to control the particle source 7, the potential applied to the suppression electrode 11, the potential applied to the acceleration electrode 15, the deflection system 19, and the particle-optical lens 17.
The particle beam system 1 further comprises a detector 25 adapted to detect particles 27 generated by interaction of the particle beam 9 with the sample 5. The particles 27 may be, inter alia, backscattered electrons, secondary electrons, backscattered ions or secondary ions. The detector 25 may be arranged outside or inside the particle beam column 3. In the example shown in fig. 1, the detector 25 is arranged in a vacuum chamber 29.
The detector 25 is adapted to output a detection signal indicative of the amount and/or energy of the detected particles 27. The controller 23 may receive the detection signal from the detector 25, process it and display it on, for example, a display device.
The particle beam system 1 further comprises a vacuum chamber 29. The vacuum chamber 29 has chamber walls 31 that spatially define the vacuum chamber 29. A vacuum can be created in the vacuum chamber 29, for example, by a vacuum pump 33 connected to the vacuum chamber 29 via line 35. The vacuum chamber 29 is connected to the particle beam column 3 and has an opening 37 through which the particle beam 9 can enter the vacuum chamber 29.
A sample stage 41 is disposed in the vacuum chamber 29, i.e., inside the vacuum chamber 29. The sample stage 41 is used to carry, spatially position and orient the sample 5. The sample stage 41 may be controlled by the controller 23 so that the controller 23 may spatially position and orient the sample 5.
The particle beam system 1 further comprises a gas supply line arrangement 43. The gas supply line arrangement 43 is configured to direct (indicated by arrows) a gas 45 to a part of the surface of the sample 5. The gas 45 may have a number of different effects. For example, gas 45 is used for charge compensation. The gas 45 may be used as a process gas for depositing material onto the sample 5 or for removing material from the sample 5. In some applications, the gas 45 is activated by the particle beam 9.
The gas supply line arrangement 43 includes a gas line 47 having an outlet 49. A gas line 47 is used to direct gas onto the portion of the surface of the sample 5. The gas flows inside the gas line 47 to the outlet 49 and exits the gas line 47 at the outlet. The gas 45 exiting the gas line 47 is drawn from the interior of the vacuum chamber 29 by the vacuum pump 33.
An outlet 49 is arranged in the vacuum chamber 29 near the portion of the surface of the sample 5. Accordingly, the gas is provided in a locally limited manner in the region of the partial surface of the sample 5 irradiated with the particle beam 9. Thus, for example, charge compensation can be provided and the vacuum generated in the vacuum chamber 29 is only slightly contaminated by gas.
The particle beam system 1 further comprises a positioning means 39. The positioning device 39 is configured to set the position of the outlet 49 of the gas line 47 in the vacuum chamber 29. Using the positioning means 39, the outlet 49 may be aligned with the portion of the surface of the sample 5.
In order to process samples at low temperatures (i.e. samples at temperatures well below 0 ℃), the gas supply line arrangement 43 further comprises a heat exchanger 51. The heat exchanger 51 is disposed in the vacuum chamber 29. The heat exchanger 51 is configured to cool the gas 45 directed in the gas line 47.
Specific details of the embodiment of the gas supply line arrangement 43 shown in fig. 1 are explained below. Fig. 2 and 3 show alternative embodiments of the gas supply line arrangement.
The gas supply line arrangement 43 comprises a supply line 53 which passes through the chamber wall 31 and is configured to guide a cooling medium for cooling the gas 45 from a cooling medium source 55 arranged outside the vacuum chamber 29 to the heat exchanger 51. The flow rate through the supply line 53 may be set by the supply line valve 57. The supply line valve 57 may be disposed outside or inside the vacuum chamber 29. Supply line valve 57 may be controlled by controller 23. Accordingly, the controller 23 may set the flow rate of the cooling medium through the supply line 53 by using the supply line valve 57.
The gas supply line arrangement 43 further comprises a return line 59 through the chamber wall 31. The return line 59 is configured to guide the cooling medium from the heat exchanger 51 to a cooling medium tank 61 arranged outside the vacuum chamber 29. The flow rate through the return line 59 may be set by a return line valve 63. The return line valve 63 may be disposed outside or inside the vacuum chamber 29. The return line valve 63 may be controlled by the controller 23. Accordingly, the controller 23 may set the flow rate of the cooling medium through the return line 59 by using the return line valve 63.
The cooling capacity of the heat exchanger 51 can be set by the supply line valve 57 and the return line valve 63. However, the two valves need not be provided together. In this description, the supply line valve 57 and the return line valve 63 are referred to collectively or individually as heat exchanger flow valves.
In the example shown in fig. 1, the gas supply line arrangement 43 further comprises a gas source 65 arranged outside the vacuum chamber 29 and connected to the gas line 47. As a result, gas can be conveyed from the gas source 65 arranged outside the vacuum chamber 29 into the gas line 47 and via the outlet 49 to the portion of the surface of the sample 5. The flow rate of gas through gas line 47 can be set by gas line valve 67. In the example shown in FIG. 1, the gas line valve 67 is disposed outside the vacuum chamber 29. However, a gas line valve 67 may also be arranged in the vacuum chamber 29. The gas line valve 67 may be controlled by the controller 23. Accordingly, the controller 23 may set the flow rate of the gas 45 through the gas line 47 by using the gas line valve 67.
In the embodiment of the gas supply line arrangement 43 shown in fig. 1, the supply line 53, the heat exchanger 51 and the return line 59 form a flow path for the cooling medium, which flow path is closed in the vacuum chamber 29. This means that the cooling medium does not contaminate the vacuum formed in the vacuum chamber 29, since the cooling medium cannot leave the flow channels. In addition, a gas line 47 passes through the chamber wall 31 of the vacuum chamber 29. The gas line 47, supply line 53, and return line 59 are separate lines.
In the embodiment shown in fig. 1, the gas supply line arrangement 43 further comprises a temperature sensor 69 configured to measure the temperature of the heat exchanger 51. The gas supply line arrangement 43 further comprises a temperature sensor 71 configured to measure the temperature of the cooling medium in the supply line 53. The gas supply line arrangement 43 further comprises a temperature sensor 73 configured to measure the temperature of the cooling medium in the return line 59. Although not shown in the drawings, the gas supply line arrangement 43 further comprises a temperature sensor configured to measure the temperature of the gas 45 in the gas line 47 or in the vicinity of the outlet 49. The controller 23 may use the measured temperature to control the cooling capacity of the heat exchanger 51.
In the embodiment shown in fig. 1, a further temperature sensor 74 is provided, which is configured to measure the temperature of the sample stage 41. The temperature of the sample stage 41 may be used to represent or estimate the temperature of the sample 5. Other means for measuring or estimating the temperature of the sample 5 may be used. The controller 23 may use the temperature of the sample 5 to control the cooling capacity of the heat exchanger 51.
Fig. 2 shows a schematic representation of another embodiment of a gas supply line arrangement 43A. The gas supply line device 43A is different from the gas supply line device 43 basically only in the following features. The supply line 53A has a branch 75A to which the gas line 47A is connected. The branch 75A is arranged in the vacuum chamber 29. At the branch 75A, the supply line 53A divides into a gas line 47A on the one hand and into a supply line portion 77A on the other hand. The cooling medium carried by the supply line portion 77A is supplied to the heat exchanger 51.
The cooling medium flowing into gas line 47A at branch 75A provides the gas. As also shown in fig. 1, the gas line 47A extends through a heat exchanger 51, whereby the gas 45 carried in the gas line 47A is cooled and then directed to the portion of the surface of the sample 5 through an outlet 49 of the gas line 47A.
The difference with the embodiment of the gas supply line arrangement 43 is that in the case of the gas supply line arrangement 43A of fig. 2 only two lines, instead of three, have to be guided through the chamber wall 31 of the vacuum chamber 29.
Fig. 3 shows a schematic representation of a further embodiment of a gas supply line arrangement 43B. The gas supply line arrangement 43B differs from the gas supply line arrangement 43A only in that the gas line 47B is connected at a branch 79B in the return line 59B. Correspondingly, the return line 59B has a return line section 81B which carries the cooling medium from the heat exchanger 51 to the branch 79B. At the branch 79B, the cooling medium conveyed in the return line section 81B is divided into the gas line 47B on the one hand and into the other return line section 83B on the other hand. A part of the cooling medium introduced into the gas line 47B serves as the gas 45. Part of the cooling medium guided into the other return line portion 83B is supplied to the cooling medium tank 61.
In both the supply line portion 77A shown in fig. 2 and the return line portion 81B shown in fig. 3, a valve for setting the flow rate may be provided. As shown in both fig. 2 and 3, the branches 75A, 79B are arranged in the vacuum chamber 29.
As explained in connection with fig. 1 to 3, the gas 45 in the vacuum chamber 29 can be cooled by means of a cooling medium. In the embodiment shown in fig. 1 to 3, the gas 45 is cooled by a heat exchanger 51 supplied with a cooling medium. The cooling medium may for example be conducted in a supply line 53 through the chamber wall 31 at a temperature below-50 c or below-100 c or below-150 c.
Fig. 4 shows a schematic representation of another embodiment of a gas supply line arrangement 43C. The gas supply line arrangement 43C differs from the gas supply line arrangement 43 shown in fig. 1 essentially only in that the heat exchanger 51 is not cooled by the cooling medium conveyed to the heat exchanger 51 from outside the vacuum chamber 29 but is cooled by the coupling element 85. The cooling of the heat exchanger 51 by the coupling element 85 indirectly causes a cooling of the gas 45.
The coupling element 85 is connected to the heat exchanger 51 in a highly efficient heat-conducting manner. The coupling element 85 extends from the heat exchanger 51 through the chamber wall 31 of the vacuum chamber 29 to the cooling device 87. The cooling device 87 is configured to cool the coupling element 85. The cooling means 87 may be provided by a simple cold source, such as a dewar with liquid nitrogen. The cooling means 87 may also be provided by a heat exchanger with a cooling medium similar to the example shown with reference to fig. 1 to 3.
The portion of the surface of the sample 5 disposed in the vacuum chamber 29 can be supplied with the gas having the temperature lower than 0 deg.c by the gas supply line devices 43, 43A, 43B, and 43C shown in fig. 1 to 4. The specification of temperature refers to, for example, the temperature of the gas 45 at the outlet 49 of the gas line. The gas 45 may be provided such that the temperature when the gas is directed to the portion of the surface of the sample 5 (i.e., at the outlet 49 of the gas line 47) is only slightly above the temperature of the sample 5 or below the temperature of the sample 5.
The sample 5 may be cooled by the gas 45. Alternatively, the sample 5 may be kept at a temperature as low as well below 0 ℃ by some other means or some other means. For example, the sample 5 is cooled by means of a separate cooling member (not shown) on the sample stage 41.
By means of the gas supply line arrangements 43, 43C shown in fig. 1 and 4, the gas 45 can be guided through the chamber wall 31 of the vacuum chamber 29 in a gas line 47, the temperature of the gas being higher when it passes through the chamber wall 31 than when the gas 45 is guided to the part of the surface of the sample 5, i.e. at the outlet 49 of the gas line 47. For example, the temperature of the gas 45 as it passes through the chamber wall 31 in the gas line 47 may be a temperature above 0 ℃ or room temperature. The gas is then cooled by the heat exchanger 51 to the desired temperature at the outlet 49.
Fig. 5 shows a schematic representation of another particle beam system 101. The particle beam system 101 differs from the particle beam system 1 shown in fig. 1 essentially only in that the particle beam system 101 comprises a plurality of particle beam columns having a common working area. In the example shown in fig. 5, the particle beam system 101 comprises a first particle beam column 103 and a second particle beam column 105. For example, the first particle beam column 103 is an electron beam column, and the second particle beam column 105 is an ion beam column. The particle beam columns 103 and 105 may be configured in a manner similar to the particle beam column 3 of fig. 1. The particle beam columns 103 and 105 may be controlled by the controller 23.
The sample 5 is arranged in a common working area of the particle beam columns 103 and 105. Therefore, the particle beams 109 and 111 generated by the two particle beam columns 103 and 105 can be directed onto the same area of the sample 5 without having to move the sample 5.
The gas supply line arrangement 43 corresponds to the gas supply line arrangement shown in fig. 1. However, other gas supply line arrangements described herein, particularly the gas supply line arrangements 43A, 43B and 43C shown in fig. 2, 3 and 4, may be used in place of or in combination with the gas supply line arrangement 43.

Claims (21)

1. A particle beam system (1), comprising:
a vacuum chamber (29) having a chamber wall (31);
a particle beam column (3) for irradiating a partial surface of a sample (5) arranged in the vacuum chamber (29) with a particle beam (9) of charged particles;
gas supply line means (43, 43A, 43B, 43C) for guiding a gas (45) to the portion of the surface of the sample (5) arranged in the vacuum chamber (29);
the gas supply line device (43, 43A, 43B) comprises:
-a gas line (47, 47A, 47B) for guiding the gas (45), the gas line (47, 47A, 47B) having an outlet (49) arranged in the vacuum chamber (29); and
-a heat exchanger (51) arranged in the vacuum chamber (29) for cooling the gas (45) guided in the gas line (47, 47A, 47B).
2. Particle beam system (1) according to claim 1,
the gas supply line device (43, 43A, 43B) further comprises:
-a supply line (53, 53A) passing through the chamber wall (31) for leading cooling medium from a cooling medium source (55) arranged outside the vacuum chamber (29) to the heat exchanger (51),
-a return line (59, 59B) passing through the chamber wall (31) for leading the cooling medium from the heat exchanger (51) to a cooling medium tank (61) arranged outside the vacuum chamber (29),
the cooling medium is adapted to cooling the gas (45) in the heat exchanger (51).
3. The particle beam system (1) of claim 2, the gas supply line arrangement (43, 43A, 43B) further comprising:
a heat exchanger flow valve (57, 63) for setting a flow rate of the cooling medium through the heat exchanger (51).
4. Particle beam system (1) according to claim 2 or 3, the supply line (53), the heat exchanger (51) and the return line (59) forming a flow path for the cooling medium, which flow path is closed within the vacuum chamber (29).
5. Particle beam system (1) according to one of claims 2 to 4, the supply line (53A) or the return line (59B) having a branch (75A, 79B) to which the gas line (47A, 47B) is connected.
6. The particle beam system (1) of claim 1, the gas supply line arrangement (43C) further comprising:
a cooling device (87) arranged outside the vacuum chamber (29) for cooling a coupling element (85) which passes through the chamber wall (31) and is thermally coupled with the heat exchanger (51).
7. Particle beam system (1) according to one of the claims 1 to 6, the gas line (47) passing through a chamber wall (31) of the vacuum chamber (29).
8. The particle beam system (1) according to one of claims 1 to 7, the gas supply line arrangement (43, 43A, 43B, 43C) further comprising:
a gas line valve (67) for setting a flow rate of the gas (45) through the gas line (47).
9. The particle beam system (1) according to one of claims 1 to 8, further comprising:
a controller (23) configured to control the cooling capacity of the heat exchanger (51) as a function of the temperature of the heat exchanger (51) and/or as a function of the temperature of the gas (45) and/or as a function of the temperature of the sample (5) and/or as a function of the temperature of a sample stage (41) carrying the sample (5) in the vacuum chamber (29).
10. Particle beam system (1) according to claim 9, the controller (23) being configured to control the cooling capacity of the heat exchanger (51) such that the temperature of the heat exchanger (51) or the gas (45) tends to a predetermined value.
11. The particle beam system (1) according to claim 10, wherein the predetermined value is indicative of a temperature of the sample (5) or dependent on a temperature of the sample (5), or indicative of a temperature of a sample stage (41) carrying the sample (5) or dependent on a temperature of a sample stage (41) carrying the sample (5).
12. The particle beam system (1) according to one of claims 1 to 11, further comprising: a positioning device (39) for setting the position of the outlet (49) of the gas line (47) in the vacuum chamber (29).
13. A method for operating a particle beam system (1), the method comprising:
arranging a sample (5) in a vacuum chamber (29) of the particle beam system (1);
irradiating a partial surface of the sample (5) arranged in the vacuum chamber (29) with a particle beam (9) of charged particles; and
a gas (45) having a temperature below 0 ℃ is directed to the portion of the surface of the sample (5) arranged in the vacuum chamber (29).
14. The method of claim 13, wherein the first and second light sources are selected from the group consisting of,
the temperature of the gas (45) is at most 50 ℃ higher than the temperature of the sample (5) when the gas is directed to the part surface, or
The temperature of the gas (45) is lower than the temperature of the sample (5) when the gas is directed to the portion of the surface.
15. The method according to claim 13 or 14,
the temperature of the sample (5) is below 0 ℃ during the irradiation and/or during the supply of the gas (45).
16. The method according to one of claims 13 to 15, further comprising:
the gas (45) is cooled in the vacuum chamber (29) by means of a heat exchanger (51).
17. The method of claim 16, further comprising:
a cooling medium is led to a heat exchanger (51) in a supply line (33) which passes through the chamber wall (31) of the vacuum chamber (29), the temperature of the cooling medium being below-50 ℃.
18. The method of claim 16, further comprising: the heat exchanger (51) is cooled by a coupling element (85) which passes through a chamber wall (31) of the vacuum chamber (29) and is cooled by a cooling device (87) arranged outside the vacuum chamber (29).
19. The method according to one of claims 16 to 18, further comprising:
the gas (45) is directed in a gas line (47) that passes through a chamber wall (31) of the vacuum chamber (29), the temperature of the gas (45) as it passes through the chamber wall being higher than the temperature of the gas (45) as it is directed to the partial surface.
20. The method of claim 16 or 17, further comprising:
-providing the gas (45) by using part of the cooling medium, which is fed to the heat exchanger (51) to cool the gas (45) in the vacuum chamber (29); and
another part of the cooling medium is returned from the vacuum chamber (29) through a return line (59) through a chamber wall (31) of the vacuum chamber (29).
21. A computer program product comprising computer readable instructions which, when executed by a controller of a particle beam system, cause the particle beam system to perform the method according to one of claims 13 to 20.
CN202110237457.4A 2020-03-03 2021-03-03 Particle beam system, method of operating a particle beam system, and computer program product Active CN113363126B (en)

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CN101964294A (en) * 2009-07-15 2011-02-02 卡尔蔡司Nts有限责任公司 Particle beam microscopy system and method for operating the same
CN106024563A (en) * 2015-03-31 2016-10-12 Fei 公司 Charged particle beam processing using process gas and cooled surface

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