TWI892325B - Charged particle beam device, and method for adjusting the same - Google Patents

Abstract

Appropriately selecting the adjustments to be performed and executing them at the appropriate time. A charged particle beam device generates an observation image of a sample by irradiating it with a charged particle beam. In this device, a control unit executes a program to instruct the execution of sample processing (S601). Based on the charged particle beam device's adjustment history or the observation image, an adjustment recipe to be executed is selected from a plurality of adjustment recipes (S604). Based on the charged particle beam device's status and the program's execution status, the timing for executing the adjustments is determined during program execution (S605-S607). The selected adjustment recipe is then executed (S608).

Description

Charged particle beam device, and method for adjusting the same

This disclosure relates to a charged particle beam device and a method for adjusting the charged particle beam device.

Charged particle beam devices, such as scanning electron microscopes (SEMs) and focused ion beam (FIB) devices, are suitable for observing and processing semiconductor patterns formed on increasingly miniaturized semiconductor wafers.

In order to perform high-precision observation or processing using devices such as SEMs and FIBs, device conditions must be appropriately adjusted. Patent Document 1 discloses a charged particle beam device that performs automatic adjustment, such as axial adjustment, of the charged particle beam at appropriate times. In the charged particle beam device of Patent Document 1, the need for automatic adjustment is determined when optical conditions are changed (see S903 in FIG. 9 ). Automatic adjustment is performed when a considerable amount of time has passed since the last automatic adjustment.

Prior Art Literature Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2017-076523

While Patent Document 1 discloses automatic adjustment at the time when optical conditions are changed or the measurement point is moved, the content of the automatic adjustment performed in Patent Document 1 is fixed. Various adjustments are required depending on the adjustment history of the charged particle beam device or changes in the observed image, but Patent Document 1 automatically performs adjustments integrated into the recipe, making it impossible to perform appropriate adjustments at the appropriate time.

In view of this, the present disclosure provides a charged particle beam device that can appropriately select the adjustments to be performed and perform them at the appropriate time.

In order to solve the above-mentioned problems to be solved, the charged particle beam device disclosed in the present invention generates an observation image of the sample by irradiating the sample with a charged particle beam, and comprises: a memory unit for storing a program for instructing the execution of processing of the sample and a plurality of adjustment recipes for instructing the execution of adjustment of the device conditions of the charged particle beam device; and a control unit for instructing the execution of processing of the sample by executing the program stored in the memory unit. The processing unit commands the execution of device condition adjustments by executing an adjustment recipe stored in a memory unit. The control unit selects an adjustment recipe to be executed from among the multiple adjustment recipes stored in the memory unit based on the adjustment history or observation image of the charged particle beam device. Based on the status of the charged particle beam device and the execution status of the program, the control unit determines the timing of the adjustment during program execution and executes the selected adjustment recipe.

According to the present disclosure, it is possible to appropriately select the adjustments to be performed and execute them at the appropriate time.

Other unresolved issues, structures, and effects beyond those mentioned above will become clear through the following description of the implementation methods.

100: FIB-SEM composite device

10: SEM lens tube

20: FIB lens

30: Gas ion beam lens tube

4: Secondary electron detector

5: Gas Gun

6: Control device

7: Display device

8: Input device

9: Memory device

40: Vacuum Chamber

50: Sample platform

51: Sample table

200:Sample

[Figure 1] Schematic diagram of the overall structure of the FIB-SEM hybrid device according to the embodiment.

[Figure 2] A block diagram illustrating the hardware configuration of the control device according to one embodiment.

[Figure 3] A diagram illustrating multiple adjustment recipes and application programs stored in a memory device according to an embodiment.

[Figure 4] A diagram illustrating an adjustment recipe display screen displayed on a display device according to an embodiment.

[Figure 5] A diagram illustrating a customized method for adjusting a recipe according to an embodiment.

[Figure 6] Flowchart illustrating the method for adjusting the FIB-SEM hybrid device according to an embodiment.

The following describes the implementation of this disclosure with reference to the drawings.

(Overall structure of FIB-SEM hybrid device 100)

Figure 1 schematically illustrates the overall structure of a hybrid FIB-SEM apparatus 100. The hybrid FIB-SEM apparatus 100 is a charged particle beam apparatus that generates an observation image of a sample by irradiating it with a charged particle beam (electron beam, focused ion beam, gas ion beam). In Figure 1, the hybrid FIB-SEM apparatus 100 comprises an electron beam column (SEM column) 10, which houses the optical system for irradiating the sample with the electron beam; a focused ion beam column (FIB column) 20, which houses the optical system for irradiating the sample with the focused ion beam; a gas ion beam column 30; a secondary electron detector 4; and a gas gun 5. The FIB-SEM hybrid apparatus 100 also includes a control device 6 (control unit), which is a computer system including a CPU and memory; a display device 7 (display unit), such as a liquid crystal display; an input device 8, such as a keyboard or mouse; and a storage device 9, such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). Furthermore, the FIB-SEM hybrid apparatus 100 includes a sample platform 50 and a sample stage (sample holder) 51 disposed on the sample platform 50. Some or all of the components of the FIB-SEM hybrid apparatus 100 are located within a vacuum chamber 40, which is depressurized to a predetermined vacuum level.

The sample platform 50 movably supports a sample table 51, on which a sample 200 is placed. The sample platform 50 also includes a movement mechanism capable of displacing the sample table 51 along five axes. This movement mechanism can be implemented using various actuators, such as piezoelectric elements and stepping motors. By displacing the sample table 51 along five axes, the sample platform 50 moves the sample 200 to multiple irradiation positions using electron beams, focused ion beams, and gas ion beams. At these irradiation positions, the surface (cross-section) of the sample 200 is irradiated with the electron beam, focused ion beam, or gas ion beam, and the sample 200 is processed (processed and observed).

Although not shown, the SEM lens barrel 10 includes an electron source that emits electrons and an electron optical system that shapes and scans the electrons emitted from the electron source into a beam. When the SEM lens barrel 10 irradiates the sample 200 with an electron beam, which is a beam of charged particles, secondary electrons are generated from the sample 200. These generated secondary electrons are detected by a secondary electron detector (not shown) within the lens barrel or a secondary electron detector 4 outside the lens barrel, thereby obtaining an image of the sample 200. The electron optical system includes, for example, a focusing lens that focuses the electron beam; an aperture that constricts the electron beam; a collimator that adjusts the optical axis of the electron beam; an object lens that focuses the electron beam on the sample 200; and a deflector that scans the electron beam across the sample 200.

Although not shown, the FIB barrel 20 includes an ion source for generating ions and an ion optical system for shaping the ions emitted from the ion source into a focused ion beam and scanning the beam. When the FIB barrel 20 irradiates the sample 200 with a charged particle beam, or focused ion beam, secondary charged particles such as secondary ions and secondary electrons are generated from the sample 200. The secondary electron detector 4 detects these secondary charged particles, acquiring an observation image of the sample 200. Furthermore, the FIB barrel 20 increases the irradiation dose of the focused ion beam to perform etching (cross-section processing) on the sample 200 within the irradiation range. The ion optical system has a well-known structure, for example, comprising: a focusing lens for focusing the focused ion beam; an aperture for confining the focused ion beam; a collimator for adjusting the optical axis of the focused ion beam; an object lens for focusing the focused ion beam onto the sample; and a deflector for scanning the focused ion beam onto the sample 200.

Although not shown, the gas ion beam column 30 includes an ion source for generating, for example, argon ions, a focusing lens for focusing the ion beam from the ion source, a shutter, an aperture for limiting the ion beam, and an object lens for focusing the ion beam.

The gas gun 5 discharges a predetermined gas, such as an etching gas, toward the sample 200. By supplying the etching gas from the gas gun 5 while irradiating the sample 200 with an electron beam, focused ion beam, or gas ion beam, the etching rate of the sample due to beam irradiation can be increased. Alternatively, by supplying a compound gas from the gas gun 5 while irradiating the sample 200 with an electron beam, focused ion beam, or gas ion beam, localized precipitation (deposition) of gas components can be achieved near the beam irradiation area. While this example describes the discharge of gas for deposition, deposition can also be performed by irradiating the sample with an electron beam, focused ion beam, or gas ion beam in a contaminated environment without using gas.

(Hardware structure of control device 6)

Figure 2 is a block diagram illustrating the hardware configuration of control device 6. Control device 6 includes a processor 201, main memory 202, auxiliary memory 203, input/output interface 204, and a bus 205 that communicatively connects these modules. Processor 201 may be, for example, a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or an ASIC (Application Specific Integrated Circuit). Processor 201 loads application programs or adjustment recipes stored in memory device 9 into the working area of main memory 202 for execution. The main memory 202 stores applications or recipes executed by the processor 201, as well as data processed by the processor. The main memory 202 can be flash memory, RAM (Random Access Memory), or similar. The auxiliary memory 203 stores the boot program for the FIB-SEM hybrid apparatus 100 and can be, for example, ROM (Read Only Memory).

The input/output interface 204 is communicatively connected to the aforementioned SEM tube 10, FIB tube 20, gas ion beam tube 30, secondary electron detector 4, gas gun 5, and sample stage 50. Furthermore, the input/output interface 204 is communicatively connected to a display device 7 that displays an image of the sample 200, an input device 8 that receives input from the operator, and a memory device 9 that stores application programs and adjustment recipes. The processor 201 executes various calculations based on the application programs and adjustment recipes stored in the memory device 9, allowing the control device 6 to control the various components of the FIB-SEM hybrid apparatus 100.

FIG3 is a diagram illustrating a plurality of adjustment recipes 60 and 61 and application programs 62 and 63 stored in the memory device 9. An application program is a program that instructs the execution of sample processing (machining, observation). An adjustment recipe is a program that instructs the execution of adjustments to the device conditions (optical system conditions, gas supply system conditions) of the FIB-SEM hybrid device 100. In the example of FIG3 , the memory device 9 stores a plurality of adjustment recipes 60 and 61 and a plurality of application programs 62 and 63. However, the adjustment recipes 60 and 61 and the application programs 62 and 63 may also be stored in different memory devices. The control device 6 executes the sample processing (machining, observation) by executing the application programs. In addition, the control device 6 adjusts the device conditions by executing the adjustment recipe.

(Adjust recipes 60 and 61)

Memory device 9 stores a plurality of adjustment recipes 60 and 61. Adjustment recipes 60 and 61 are programs that command execution of adjustments to the apparatus conditions of FIB-SEM hybrid apparatus 100. These apparatus conditions include the conditions of the optical system within SEM barrel 10 and the conditions of the gas supply system for the gas discharged by gas gun 5. Adjustment recipe 60 includes a plurality of adjustment items 60A-60D in a predetermined execution order. When control device 6 executes adjustment recipe 60, adjustment items 60A, 60B, 60C, and 60D are executed in this execution order. Furthermore, the adjustment recipe 61 includes a plurality of adjustment items 61A to 61D in a predetermined execution order. Once the control device 6 executes the adjustment recipe 61, the adjustment items 61A, 61B, 61C, and 61D are executed in this execution order.

(Example of adjustment items)

Here, we explain the specific examples of adjusting items 60A~60D and 61A~61D.

Adjustment items include, for example, powering on the FIB-SEM hybrid device 100 (startup), powering on the FIB barrel 20 (startup), powering on the SEM barrel 10 (startup), flashing and degassing of the SEM barrel 10, axis adjustment of the charged particle beam (electron beam, focused ion beam), contrast adjustment, focus adjustment, stigma adjustment, and DepoRate coefficient setting.

Furthermore, the memory device 9 stores a continuous cross-section processing and observation application 62 and a thin-section sample preparation application 63 for TEM observation. The applications stored in the memory device 9 are not limited to these applications 62 and 63.

(Continuous Section Observation Application 62)

The continuous cross-section observation application 62 is used for 3D structural analysis of samples. It is an application that performs evenly spaced slicing by FIB and observation of the processed surface by SEM in a command-based interactive manner.

(Application 63 for creating thin slice samples for TEM observation)

This application is used to create thin slice samples for observation in a TEM (Transmission Electron Microscope). By running this application 63, the film thickness is reduced to a thin slice containing only the desired observation target (e.g., a single device structure of interest), thereby creating a thin slice sample for TEM observation.

(Adjust recipe display screen 70)

Figure 4 illustrates the adjustment recipe display screen displayed on display device 7. Adjustment recipe display screen 70 displays the selected adjustment recipe. The user can customize adjustment items on this adjustment recipe display screen 70. Customizing adjustment items includes rearranging adjustment items, adding adjustment items, deleting adjustment items, and changing parameters within adjustment items.

Adjustment recipe display screen 70 includes a selection box 71 for selecting an adjustment recipe. The user can use selection box 71 to select an adjustment recipe. In the example shown in Figure 4 , adjustment recipe 60 is selected in selection box 71 . Therefore, adjustment items 60A through 60D of adjustment recipe 60 are displayed in this order on adjustment recipe display screen 70 .

(Adjust recipe customization)

In the FIB-SEM hybrid device 100, adjustment recipes can be customized automatically or manually. Figure 5 illustrates the method for customizing adjustment recipes.

Here, we will explain how to manually customize an adjustment recipe according to user instructions. First, the user selects an adjustment recipe from a plurality of adjustment recipes in selection box 71 (see Figure 4). For example, if adjustment recipe 60 is selected, the adjustment items 60A-60D of adjustment recipe 60 will be displayed in that order on display device 7.

If the order of adjustment items 60B and 60C in adjustment recipe 60 is reversed, for example, by moving adjustment item 60B below adjustment item 60C, adjustment recipe 60 can be customized to be executed in the order of adjustment items 60A, 60C, 60B, and 60D.

When adding adjustment item 60E to adjustment recipe 60, for example, the user drags adjustment item 60E from another window and drops it onto adjustment recipe 60 displayed on display device 7. This allows adjustment recipe 60 to be customized into adjustment recipe 60b, which executes adjustment items 60A, 60B, 60C, 60D, and 60E in the order they were executed. Here, although adjustment item 60E is added to the end of adjustment recipe 60b, adjustment item 60E could also be added to the dragged location.

To delete adjustment item 60D in adjustment recipe 60, for example, the user selects and deletes adjustment item 60D. This allows adjustment recipe 60 to be customized to be executed in the order of adjustment items 60A, 60B, and 60C.

(Adjustment Method of FIB-SEM Hybrid Device 100)

FIG6 is a flow chart illustrating a method for adjusting the FIB-SEM hybrid device 100.

First, the control device 6 executes an application stored in the memory device 9 (e.g., the continuous cross-section observation application 62 or the thin-section sample creation application 63 for TEM observation) (step S601). During the execution of the application, the control device 6 determines whether a determination time has been reached (step S602). If the determination time has been reached (step S602: Yes), the control device 6 determines whether adjustment is necessary based on an implementation determination criterion (step S603). In this embodiment, the control device 6 determines whether adjustment is necessary based on the adjustment history or observation images of the FIB-SEM hybrid apparatus 100. If it is determined that the time point is not reached (step S602: No) or if adjustment is determined to be unnecessary (step S603: No), it is determined again after the specified time has passed whether the time point has been reached (step S602).

If adjustment is determined to be necessary (step S603: Yes), the control device 6 selects an adjustment recipe to be executed from a plurality of adjustment recipes based on an implementation determination criterion (step S604). For example, if adjustment is performed periodically based on adjustment history, an adjustment recipe including the adjustment items that must be performed periodically is selected. If adjustment is performed based on changes in an observed image, an adjustment recipe for brightness adjustment is selected if changes in brightness are visible in the observed image. Alternatively, the control device 6 can automatically customize the selected adjustment recipe based on an implementation determination criterion (e.g., an adjustment history or observed image of adjustments performed in the FIB-SEM hybrid apparatus 100).

Next, the control device 6 obtains the status of the FIB-SEM hybrid device 100 (e.g., processing, observing, on standby, etc.) (step S605). Furthermore, the control device 6 obtains the execution status of the executed application (step S606).

Next, the control device 6 determines the time to perform the adjustment based on the status of the FIB-SEM hybrid apparatus 100 obtained in step S605 and the application execution status obtained in step S606 (step S607). The control device 6 then executes the selected adjustment recipe at the determined time to perform the adjustment (step S608). The control device 6 executes the adjustment items in the adjustment recipe sequentially according to the order specified in the adjustment recipe.

The control device 6 then determines whether the application has completed (step S609). If the application has completed (step S609: Yes), this flowchart ends. If the application has not yet completed (step S609: No), it again determines whether the determination time point has been reached (step S602).

(Determine time point)

Next, we will explain a specific example of the determination timing in step S602 of Figure 6.

The determination time point in step S602 of Figure 6 can be at each designated time during sample processing and/or observation, at each range interval during sample processing and/or observation, at each specified time unit (e.g., seconds), at each sample transport, at each designated location (e.g., a designated processing location, a designated observation location), or when a designated GUI button displayed on the display device 7 is selected.

(Implementation Criteria)

Next, we will explain a specific example of the implementation criteria for step S604 in Figure 6.

The implementation judgment criteria can be a pre-determined time, the number of executions of a recipe commanded to process and/or observe a sample, a specified time during sample processing and/or observation, each range interval during sample processing and/or observation, each specified time unit (e.g., seconds), the number of sample transfers, or each designated location (e.g., a designated processing location, a designated observation location).

Furthermore, the charged particle beam apparatus 1 can determine whether to make adjustments based on a comparison between the previous observation image and the current observation image, can determine whether to make adjustments based on a comparison between the solution image and the current observation image, can determine whether to make adjustments based on the shape or area of the hole formed by FIB hole processing, can determine whether to make adjustments based on the thickness of the film deposited by Depo, can determine whether to make adjustments based on sample processing failure, can determine whether to make adjustments based on the created drift correction. The system determines whether adjustments are required based on the deviation between the mark position and the processed position of the sample after processing. The created drift-corrected mark can be observed using the parameters of the charged particle beam used for processing. If the deviation exceeds a threshold, adjustments are made. AI can be used to determine the feature values of the observed image, and adjustments are made based on the AI's determination. Adjustments can also be determined based on the edge value, edge vector, and binary large object (Blob) between the observed image and the normal image.

Furthermore, the above-mentioned observation image may be an observation image of a sample processed by irradiating the sample with an electron beam, or an observation image of a sample processed by irradiating the sample with a focused ion beam.

(Effect of implementation method)

In this embodiment, the need for adjustment is determined based on the adjustment history or observation images of the FIB-SEM hybrid apparatus 100, and an adjustment recipe to be executed is selected from multiple adjustment recipes. Furthermore, in this embodiment, the timing of adjustment execution within the application is determined based on the status of the FIB-SEM hybrid apparatus 100 and the application execution status. This allows for appropriate selection of the adjustment to be performed and its execution at the appropriate time.

The aforementioned automatic adjustment function can improve the efficiency of operations in the FIB-SEM hybrid device 100.

Furthermore, the aforementioned automatic adjustment function allows for timely adjustments, thereby achieving leveling of sample processing and observation images.

Furthermore, in this embodiment, a selected adjustment recipe can be automatically customized based on the adjustment history or observation images of the FIB-SEM hybrid apparatus 100. This allows for the creation of an appropriate adjustment recipe based on the adjustment history or observation images. Furthermore, the user can also manually customize the adjustment recipe.

The present disclosure has been specifically described above based on the aforementioned embodiments. However, the present disclosure is not limited to the aforementioned embodiments, and various modifications may be made without departing from the gist of the present disclosure.

For example, in the above embodiments, a FIB-SEM hybrid device 100 including a SEM lens barrel 10 and a FIB lens barrel 20 is described as an example of a charged particle beam device disclosed herein. However, the charged particle beam device disclosed herein may also be an SEM device including only the SEM lens barrel 10 or an FIB device including only the FIB lens barrel 20.

Claims (12)

A charged particle beam device that generates an observation image of a sample by irradiating the sample with a charged particle beam, characterized by comprising: a memory unit storing a program for instructing execution of processing of the sample and a plurality of adjustment recipes for instructing execution of adjustment of device conditions of the charged particle beam device; and a control unit for instructing execution of processing of the sample by executing the program stored in the memory unit and for instructing execution of adjustment of the device conditions by executing the adjustment recipe stored in the memory unit; the control unit, based on an adjustment history of the charged particle beam device or the observation image, selects an adjustment recipe to be executed from the plurality of adjustment recipes stored in the memory unit. Based on the status of the charged particle beam device and the execution status of the program, a time point for performing the adjustment is determined during the execution of the program, and the selected adjustment recipe is executed at the determined time point. The charged particle beam device as recited in claim 1, wherein: the adjustment recipe includes one or more adjustment items with a predetermined execution order; the control unit, selecting the adjustment recipe based on the adjustment history or observation image of the charged particle beam device, changes the execution order of the one or more adjustment items, adds the adjustment items, deletes the adjustment items, or changes the parameters of the adjustment items. The charged particle beam device as recited in claim 1, wherein: the adjustment recipe includes one or more adjustment items with a predetermined execution order; the control unit, in accordance with user instructions, changes the execution order of the one or more adjustment items in the adjustment recipe, adds the adjustment items, deletes the adjustment items, or changes parameters of the adjustment items. The charged particle beam device as recited in claim 1, further comprising at least one of an optical system for irradiating the sample with the charged particle beam or a gas supply system for supplying gas to the sample irradiated with the charged particle beam, wherein the device conditions include at least one of the conditions of the optical system or the conditions of the gas supply system. The charged particle beam device according to claim 1, comprising at least one of an electron beam lens for irradiating the sample with an electron beam or a focused ion beam lens for irradiating the sample with a focused ion beam. The charged particle beam device according to claim 1, wherein: the charged particle beam device processes the sample by irradiating the sample with an electron beam, thereby generating the observation image of the processed sample; the control unit selects the adjustment recipe to be executed from among the plurality of adjustment recipes stored in the memory unit based on the observation image of the sample processed by the electron beam. The charged particle beam device as recited in claim 1, wherein: the charged particle beam device processes the sample by irradiating the sample with a focused ion beam to generate the observed image of the sample; the control unit selects the adjustment recipe to be executed from among the plurality of adjustment recipes stored in the memory unit based on the observed image of the sample processed by the focused ion beam. The charged particle beam device as recited in claim 1, wherein: the program includes a program for instructing the continuous execution of processing of the sample and observation of the processed surface of the sample; the control unit selects the adjustment recipe to be executed from among the plurality of adjustment recipes stored in the memory unit based on changes in the observed image of the processed surface. The charged particle beam apparatus as recited in claim 1, wherein: the control unit determines whether the adjustment is necessary at each designated time during sample processing or observation, at each designated range interval during sample processing, at each designated time, at each time the sample is transported, at each designated position of the sample, or when a GUI (Graphical User Interface) button displayed on the display unit is selected. A method for adjusting a charged particle beam device, which generates an observation image of a sample by irradiating the sample with a charged particle beam, is characterized by: Executing a program that instructs execution of processing of the sample to thereby execute processing of the sample; Based on the charged particle beam device's adjustment history or the observation image, selecting an adjustment recipe to be executed from a plurality of adjustment recipes that instruct execution of adjustment of the device conditions; and Determining a time point during the execution of the program to execute the adjustment based on the status of the charged particle beam device and the execution status of the program, and executing the selected adjustment recipe at the determined time point. The method for adjusting a charged particle beam device as recited in claim 10, wherein: the adjustment recipe includes one or more adjustment items with a predetermined execution order; and further comprises: performing, based on the adjustment history or the observed image of the charged particle beam device, changing the execution order of the one or more adjustment items, adding the adjustment items, deleting the adjustment items, or changing the parameters of the adjustment items. The method for adjusting a charged particle beam device as recited in claim 10, wherein: the adjustment recipe includes one or more adjustment items with a predetermined execution order; and further comprises: following user instructions, changing the execution order of the one or more adjustment items in the adjustment recipe, adding the adjustment items, deleting the adjustment items, or changing the parameters of the adjustment items.