Charged particle beam device

Abstract

The purpose of the present disclosure is to provide a technology capable of determining whether a static elimination effect on electrification due to irradiation of light and an improvement effect of an image are saturated or insufficient, in particular, a charged particle beam device capable of deciding a correction amount for obtaining an optimum static elimination effect and an optimum improvement effect of an image. A charged particle beam device according to the present disclosure acquires feature amounts of a sample for respective irradiation amounts of light with respect to the sample, calculates an irradiation amount in which the difference between the feature amounts of a sample image for the respective irradiation amounts satisfies a prescribed condition, and controls a light source so as to irradiate the sample with the light at the calculated irradiation amount (see fig. 4).

Description

charged particle beam device

[0001] The present disclosure relates to charged particle beam devices.

[0002] Charged particle beam devices include electron microscopes and ion microscopes. Microscopes include scanning electron microscopes (SEMs). It is known that charged particle beam devices can cause variations in brightness and distortions in secondary charged particle images due to sample charging during sample observation, analysis, and other processes. In response to this, charging suppression techniques include irradiating the area irradiated with the primary charged particle beam with electromagnetic waves such as light.

[0003] Patent Document 1 describes the following technology (paragraph 0059): "During alignment, the charged particle beam device 1 irradiates light a1 (e.g., light 611) from the light source 8 onto the surface of the alignment sample 60, which has already been irradiated with the beam b1 as described above. Light 611 in a wavelength range exceeding the band gap is irradiated onto the portion where the PN junction 65 is located. The polysilicon plug 63 transmits the light 611 well, and the transmitted light irradiates the N-type semiconductor 62 and the PN junction 65. This generates charged carriers 612. The generated carriers 612 act to cancel out the charge biased by the positive charge 603 on the surface. Therefore, the polysilicon plug 63 irradiated with light a1 emits an increased amount of secondary electrons 613, and the secondary electron image based on the detection of secondary charged particles b2 becomes a bright image with a high brightness value."

[0004] WO2022 / 070311

[0005] Charged particle beam devices, which have the ability to irradiate samples with primary charged particle beams (hereinafter sometimes referred to as beams) and electromagnetic waves such as light (hereinafter sometimes referred to as light), require appropriate control of the charge removal effect due to light irradiation and image quality, such as the image brightness value. Light irradiation of a sample can potentially cause damage to the sample. To minimize sample damage in the semiconductor manufacturing process, it is necessary to achieve both the charge removal effect / image improvement effect due to light irradiation and the suppression of sample damage due to light irradiation. Furthermore, because the charge removal effect and the amount of sample damage due to light irradiation vary depending on the sample, a method is needed to determine the light irradiation conditions for each sample.

[0006] An object of the present disclosure is to provide a technology capable of determining whether the neutralization effect and image improvement effect on electrostatic charge caused by light irradiation are saturated or insufficient, and in particular, a charged particle beam device capable of determining the amount of correction required to obtain the optimal neutralization effect and image improvement effect.

[0007] The charged particle beam device according to the present disclosure acquires a feature of the sample for each irradiation dose of light applied to the sample, calculates the irradiation dose at which the difference between the feature values ​​of the sample image for each irradiation dose satisfies a predetermined condition, and controls the light source to irradiate the light of the calculated irradiation dose.

[0008] According to the charged particle beam device of the present disclosure, it is possible to ascertain as clearly as possible the state in which the de-electrification effect of laser irradiation has saturated from the difference in the amount of charge caused by light irradiation and the difference in the feature amount of the image, and in particular, it is possible to determine the optimal correction amount required to bring the difference in the amount of charge generated by light irradiation and the difference in the feature amount of the image to target values.

[0009] 1 is a configuration diagram of a charged particle beam device 1 according to a first embodiment. FIG. 2 shows an example of the configuration of a computer system 2. FIG. 3 is a graph showing the charge amount of a sample 104 for each light irradiation amount. FIG. 4 is a graph showing the feature amount of a secondary electron image of a sample 104 for each light irradiation amount. FIG. 5 is a process flow illustrating a procedure for calculating a correction amount of a laser output parameter. FIG. 6 is a process flow illustrating a procedure for calculating a correction amount of a laser output parameter in a second embodiment. FIG. 7 is a graph showing a pattern dimension CD for each light irradiation amount. FIG. 8 is a process flow illustrating a procedure for calculating a correction amount of a laser output parameter in a third embodiment.

[0010] The following describes embodiments in detail with reference to the drawings. In principle, identical components are denoted by the same reference numerals, and repeated explanations are omitted. In the drawings, the actual position, size, shape, and scope of each component may not be depicted to facilitate understanding. For the purpose of explanation, when describing program-based processing, the program, functions, processing units, etc. are sometimes described as the main focus. However, the hardware main focus of these is a processor, or a controller, device, computer, system, etc., configured with the processor. A computer executes processing in accordance with a program loaded into memory using resources such as memory and communication interfaces as appropriate, thereby realizing predetermined functions, processing units, etc. The processor may be configured with semiconductor devices such as a CPU or GPU. The processor may be configured with devices or circuits capable of performing predetermined calculations. Processing is not limited to software program processing, and can also be implemented using dedicated circuits. Dedicated circuits such as FPGAs and ASICs can be used. The program may be pre-installed as data on the target computer, or it may be distributed as data from a program source to the target computer and installed. The program source may be a program distribution server on a communication network or a non-transitory computer-readable storage medium. The program may be composed of a plurality of program modules.

[0011] 1 is a configuration diagram of a charged particle beam device 1 according to a first embodiment of the present disclosure. The charged particle beam device 1 has a function of being able to irradiate a sample 104 or the like with both a beam b1 and light a. This function is capable of irradiating the sample 104 or the like with only the beam b1, only the light a, or both the beam b1 and the light a simultaneously, depending on the control.

[0012] The charged particle beam device 1 performs the following: irradiating only the beam b1 of the beam b1 and the light a to measure the charge amount or the image feature amount Qn obtained from the secondary electron image; irradiating both the beam b1 and the light a two or more times to measure the charge amount or the image feature amount Qn obtained from the secondary electron image; calculating difference information between each charge amount or each image feature amount; and adjusting the light irradiation conditions (output, wavelength, deflection angle, irradiation amount, etc.) so that the difference information satisfies the conditions. The user U1 may perform the adjustment using only the automatic adjustment function, or may perform adjustments using the automatic adjustment function after performing some adjustments by operating the device himself.

[0013] The charged particle beam device 1 includes: an electron source 101 that generates a beam b1 to be irradiated onto a sample 104; a light source 107 that generates light a to be irradiated onto the sample 104; a detector 105 that detects secondary charged particles b2 (e.g., secondary electrons, backscattered electrons) such as secondary electrons obtained by irradiating the beam b1 onto the sample 104; and an energy filter 106 that is disposed on the incident side of the detector 105. The energy filter 106 may also be a device that can measure the energy of other electron beams. For example, a device that measures the energy of an electron beam from the trajectory of the electron beam, such as a Wien filter, may be used.

[0014] The charged particle beam device 1 further includes a computer system 2 that controls the irradiation of the beam b1 and the light a, and generates and displays an image based on the detection signal detected by the detector 105 when the sample 104 is irradiated with the light a and the beam b1 or only the beam b1 is irradiated.

[0015] The computer system 2 has a function of calculating the charge amount and the image feature amount, a function of calculating difference information between the charge amount and the image feature amount from the calculated charge amount and the image feature amount, and a function of calculating a correction amount for the laser output parameter based on the calculated difference information. The correction amount for the laser output parameter can be calculated using only the charge amount difference information or only the image feature amount difference information.

[0016] The charged particle beam device 1 includes an electron optical system, a light irradiation system, and an image generation system. The electron optical system (charged particle column) includes an electron source 101, a polarizer 102, an electron lens 103, a detector 105, etc. The light irradiation system includes a light source 107, a light control unit 108, etc. The image generation system includes a control unit 109, an image processing unit 110, an image display unit 111, etc.

[0017] The computer system 2 includes a control unit 109, an image processing unit 110, an image display unit 111, a light control unit 108, a memory unit 112, etc. The control unit 109 mainly controls the electron optical system, and acquires detection signals and charge amounts from the energy filter 106 and the detector 105. The image processing unit 110 calculates image features by performing image processing based on the detection signals. The light control unit 108 mainly controls the light irradiation system.

[0018] When the beam b1 is irradiated onto the surface of the sample 104, secondary electrons and the like are emitted from the surface of the sample 104 as secondary charged particles b2. The detector 105 detects the secondary charged particles as a detection signal. The detector 105 has elements arranged two-dimensionally, so it can detect a two-dimensional image of the secondary charged particles. The control unit 109 detects and acquires the secondary electron signal from the detector 105 as a detection signal in synchronization with a beam scanning signal in the control signal for the electron optical system.

[0019] The image processing unit 110 generates a secondary electron image based on the detection signals. This image has pixels arranged two-dimensionally, and each pixel has feature information such as brightness. The image display unit 111 displays the secondary electron image generated by the image processing unit on a display screen. A user U1 can view the image on the display screen. The computer system 2 also stores data such as each detection signal and the secondary electron image in a memory unit 112.

[0020] The light source 107 is, for example, a laser light source, and the emitted light a is laser light. However, the light a is not limited to this, and other types of light may be used. For example, light obtained by splitting white light and concentrating a specific split light may be used.

[0021] The charged particle beam device 1 can irradiate the sample 104 with light a from the light source 107 based on the control of the light control unit 108. For example, irradiating the sample 104 with light a can suppress charging of the sample 104. The light source 107 can control the on / off and power of the irradiation of light a based on the control.

[0022] 2 shows an example configuration of a computer system 2. The computer system 2 comprises a computer 201, an input device 202, and a display device 203 connected to the computer 201. The computer 201 comprises a processor 204, a communication interface device 205, an input / output interface device 206, a memory 207, and a bus interconnecting these devices. The input / output interface device 206 is connected to an input device 202 such as a keyboard or a mouse, and a display device 203 such as a liquid crystal display. The communication interface device 205 is also connected to each component, such as the detector 105, via signal lines, and inputs / outputs or communicates signals with each component. The communication interface device 205 may also be connected to an external device (e.g., a server) via a predetermined communication interface (e.g., a LAN) to communicate with the external device.

[0023] The processor 204 is composed of, for example, a CPU, a ROM, a RAM, etc., and constitutes a controller of the computer system 2. The processor 204 realizes the functions of the computer system 2 and the functions of each unit such as the control unit 109 based on software program processing. The functions include the output adjustment function of the light a.

[0024] The memory 207 is configured with a non-volatile storage device or the like, and stores various data and information used by the processor 204 and the like. The memory 207 stores a control program 207A, setting information 207B, detection data 207C, image data 207D, and the like. The control program 207A is a program for realizing functions. The setting information 207B is setting information for the control program 207A and user setting information set by the user U1. The setting information 207B may include information such as a control threshold value. The detection data 207C is data corresponding to a detection signal from the detector 105. The image data 207D is data of an image to be displayed on the image display unit 111.

[0025] 3A is a graph showing the charge amount of the sample 104 for each light irradiation amount. When the light irradiation amount irradiated onto the sample 104 from the light source 107 is increased, the charge amount changes accordingly. The computer system 2 calculates the charge amount difference Kn for each measurement point n of the light irradiation amount and charge amount according to Equation 1. Tn is the charge amount at measurement point n. The charge amount can be estimated or calculated, for example, based on the energy of electrons returning from the sample 104.

[0026] K ｎ =T ｎ -T ｎ－１ (1)

[0027] FIG. 3B is a graph showing the feature quantity of the secondary electron image of the sample 104 for each light irradiation dose. Here, the image contrast of the sample is used as the feature quantity. As the light irradiation dose increases, the feature quantity changes accordingly. Typically, the smaller the charge amount of the sample 104, the better the image contrast. The computer system 2 calculates the feature quantity difference Qn for each measurement point n of the light irradiation dose and feature quantity according to Equation 2. Cn is the feature quantity at measurement point n.

[0028] Qｎ =C ｎ -C ｎ－１ (2)

[0029] 4 is a process flow for explaining the procedure for calculating the correction amount of the laser output parameter. Each step is performed by the computer system 2.

[0030] Step S301: n used in Equations 1 and 2 is initialized to 0. The charged particle beam device 1 irradiates the beam b1 onto the sample 104. The computer system 2 measures the charge amount (T0) of the sample 104 from the detection signal at that time, or measures the image feature amount (C0) that appears in the secondary electron image.

[0031] Step S302: n is incremented by one (i.e., the light irradiation amount is increased as shown in FIG. 3AB, and so on). The charged particle beam device 1 irradiates the sample 104 with beam b1 and light a. The computer system 2 measures the charge amount (Tn) of the sample 104 or the image feature amount (Cn) appearing in the secondary electron image from the detection signal at that time. Only one of the charge amount or the image feature amount needs to be used. The same applies to the following steps.

[0032] Step S303: n is incremented by 1. As in S302, the charged particle beam device 1 measures the charge amount (Tn) of the sample 104 or the image feature amount (Cn) that appears in the secondary electron image.

[0033] Steps S301 to S303: Note: The amount of light irradiation increases in proportion to the value of n. All measurements may be performed at different locations or at the same location. The charge amount and image feature values ​​change for each measurement, as shown in FIG. 3AB.

[0034] Step S304: The computer system 2 calculates the charge amount difference information Kn from the charge amounts measured in S301 to S303 according to Equation 1. Alternatively, the computer system 2 calculates the image feature amount difference information Qn from the image feature amounts measured in S301 to S303 according to Equation 2.

[0035] Step S305: The computer system 2 determines whether n is smaller than a set value nk. If n is smaller than nk (Y), the process proceeds to step S306. If not (N), the process ends. The set value nk serves as a limit to prevent the sample 104 from being damaged by light irradiation.

[0036] Step S306: The computer system 2 calculates the charge amount difference information Ln1 for the entire section according to Equation 3, and determines whether Ln1 is equal to or greater than the set threshold (L1). If it is equal to or greater than L1 (Y), proceed to step S307. If it is not equal to or greater than L1 (N), end this flowchart. Alternatively, for the image feature amount, the computer system 2 calculates the image feature amount difference information Ln2 for the entire section according to Equation 4, and determines whether Ln2 is equal to or greater than the set threshold (L2). If it is equal to or less than Ln2 (Y), proceed to step S307. If it is not equal to or less than Ln2 (N), end this flowchart.

[0037] L ｎ１ =|T ｎ -T ０ | (3)

[0038] L ｎ２ =|C ｎ -C ０ | (4)

[0039] Step S307: The computer system 2 determines whether Kn is equal to or less than the set value P1. If it is equal to or less than P1 (Y), proceed to step S308. If it is not equal to or less than P1 (N), return to S303 and perform further measurements. Alternatively, for the image feature quantity, it determines whether Qn is equal to or less than the set value P2. If it is equal to or less than P2 (Y), proceed to step S308. If it is not equal to or less than P2 (N), return to S303 and perform further measurements. This step is for determining whether the change in the charge amount or image feature quantity has sufficiently saturated. This is because if the difference between adjacent measurement points is sufficiently small, the measurement value is considered to be saturated.

[0040] Step S308: The computer system 2 adopts the current light irradiation amount (i.e., at the time of reaching this step).

[0041] S306-S307: Supplement: Whether the image quality improvement effect of adjusting the light irradiation amount has reached saturation can be determined by S307. However, because S307 only considers the area between adjacent measurement points, it may not fully consider the initial state when no light is irradiated. In other words, unless it is taken into account whether the sample 104 is charged in the initial state when no light is irradiated, it may not be possible to find the appropriate light irradiation amount. Therefore, S306 is also used as a search condition. This is because S306 considers the feature amount T0 or C0 in the initial state.

[0042] Summary of First Embodiment The charged particle beam device 1 according to the first embodiment irradiates the sample 104 with the beam b1 and light a and compares the difference information of the resulting charge amount or image feature amount. This makes it possible to determine how close the neutralization effect or image improvement effect obtained from the light irradiation is to the maximum value. Because charge may not be completely removed from some samples 104, using a method for calculating the neutralization effect based on the absolute value of the charge amount may not always accurately calculate the neutralization effect. In contrast, the first embodiment uses difference information rather than the absolute value of the charge amount or feature amount, making it possible to search for conditions that maximize the neutralization effect even if the sample 104 has properties that make it impossible to completely remove charge. By calculating the actual amount of neutralization from the difference in the charge amount, it is possible to select only conditions that achieve a neutralization effect that is at least significantly different.

[0043] In the first embodiment, it has been described that the light irradiation amount that maximizes the static elimination effect is searched for using either the charge amount difference information or the image feature amount difference information. In the second embodiment of the present disclosure, an operation example using both of these difference information will be described. The configuration of the charged particle beam device 1 is the same as in the first embodiment.

[0044] 5 is a process flow illustrating a procedure for calculating the correction amount of the laser output parameter in embodiment 2. Each step is performed by the computer system 2.

[0045] Step S501: n is initialized to 0. The charged particle beam device 1 irradiates the beam b1 onto the sample 104. The computer system 2 measures the charge amount (T0) of the sample 104 from the detection signal at that time, and also measures the image feature amount (C0) that appears in the secondary electron image.

[0046] Step S502: n is incremented by 1. The charged particle beam device 1 irradiates the beam b1 and the light a onto the sample 104. The computer system 2 measures the charge amount (Tn) of the sample 104 and the image feature amount (Cn) appearing in the secondary electron image from the detection signal at that time.

[0047] Step S503: n is incremented by 1. As in S502, the charged particle beam device 1 measures the charge amount (Tn) of the sample 104 and the image feature amount (Cn) that appears in the secondary electron image.

[0048] Step S504: The computer system 2 calculates the charge amount difference information Kn according to Equation 1 from the charge amounts measured in S501 to S503, and calculates the image feature amount difference information Qn according to Equation 2 from the image feature amounts measured in S501 to S503.

[0049] Step S505: The computer system 2 determines whether n is smaller than the set value nk. If n is smaller than nk (Y), the process proceeds to step S506. If not (N), the process ends.

[0050] Step S506: The computer system 2 calculates the charge amount difference information Ln1 for the entire section according to Equation 3, and determines whether Ln1 is equal to or greater than the set threshold (L1). If it is not equal to or greater than L1 (N), the process ends. The computer system 2 further calculates the image feature amount difference information Ln2 for the entire section according to Equation 4, and determines whether Ln2 is equal to or greater than the set threshold (L2). If it is not equal to or less than Ln2 (N), the process ends. If Ln1 is equal to or greater than L1 and Ln2 is equal to or greater than L2 (Y), the process proceeds to step S507.

[0051] Step S507: The computer system 2 determines whether Kn is equal to or less than the set value P1 or whether Qn is equal to or less than the set value P2. If either of these conditions is met (Y), proceed to step S508. If not (N), return to S503 and perform further measurements.

[0052] Step S507: Supplement: In this step, if the process proceeds to S508 when either Kn or Qn satisfies the condition, the light irradiation amount will not be increased any further, thereby suppressing damage to the sample 104. On the other hand, if there is no need to consider damage to the sample 104, the process may proceed to S508 only when both Kn and Qn satisfy the condition.

[0053] Step S508: Same as S308.

[0054] <Summary of Second Embodiment> The charged particle beam device 1 according to the second embodiment can search for a light irradiation condition that satisfies the conditions with a smaller irradiation amount by determining which of the charge amount difference Kn and the feature amount difference Qn is saturated, because the light irradiation amount at that time is adopted without further increasing the light irradiation amount in S508.

[0055] Third Embodiment In the first and second embodiments, it has been described that the light irradiation amount that maximizes the neutralization effect is searched for using at least one of the charge amount difference information and the image feature amount difference information. In a third embodiment of the present disclosure, an operation example will be described in which, in addition to these difference information, the dimension (Critical Dimension: CD) of the pattern formed on the sample 104 is used as the second feature amount. The configuration of the charged particle beam device 1 is the same as in the first and second embodiments.

[0056] 6 is a graph showing the pattern dimension CD for each light irradiation dose. When the light irradiation dose irradiated onto the sample 104 from the light source 107 is increased, the pattern on the sample 104 is damaged and the dimension gradually decreases. The pattern dimension CD can be measured from the pattern shape appearing in the secondary electron image. In the third embodiment, the pattern dimension CD is treated as the second image feature.

[0057] 7 is a process flow illustrating a procedure for calculating the correction amount of the laser output parameter in embodiment 3. Each step is performed by the computer system 2.

[0058] Step S601: n is initialized to 1. The charged particle beam device 1 irradiates the beam b1 and the light a onto the sample 104. The computer system 2 measures the charge amount (T1) of the sample 104 from the detection signal at that time, and also measures the image feature amount (C1) and the second image feature amount (CD1) that appear in the secondary electron image.

[0059] Step S602: n is incremented by 1. The charged particle beam device 1 irradiates the beam b1 and the light a onto the sample 104. The computer system 2 measures the charge amount (Tn) of the sample 104 from the detection signal at that time, and also measures the image feature amount (Cn) and the second image feature amount (CDn) that appear in the secondary electron image.

[0060] Step S603: n is incremented by 1. The charged particle beam device 1 measures the charge amount (Tn), the image feature amount (Cn), and the second image feature amount (CDn) of the sample 104, similarly to S602.

[0061] Step S604: The computer system 2 calculates the charge amount difference information Kn according to Equation 1 from the charge amounts measured in S601 to S603, and calculates the image feature amount difference information Qn according to Equation 2 from the image feature amounts measured in S601 to S603.

[0062] Step S605: The computer system 2 calculates difference information Zn from the second image feature amount measured in S601 to S603 and the previously stored specification value R of the pattern dimension according to Equation 5. The difference information Zn represents the amount of damage inflicted on the sample 104 by irradiating the sample 104 with light and a charged particle beam.

[0063] Z ｎ =|R-CD ｎ | (5)

[0064] Steps S606, S608 to S610: These steps are the same as steps S305 to S308 or S505 to S508. In Fig. 7, an example in which these steps are the same as steps S505 to S508 is described.

[0065] Step S607: The computer system 2 determines whether the difference information Zn is equal to or less than the set value P3. If it is equal to or less than P3 (Y), the process proceeds to step S608. If it is not equal to P3 (N), the process ends this flowchart. If Zn is equal to or less than the threshold value P3, the pattern dimension can be considered to be equivalent to the specification value, and therefore, regardless of whether the pattern dimension has decreased due to light irradiation, the search conditions are considered to be satisfied.

[0066] <Summary of Third Embodiment> In addition to the operations described in the second embodiment, the charged particle beam device 1 according to the third embodiment determines whether the difference between the pattern dimension and the specification value R is within an allowable range and searches for a light irradiation amount that satisfies this. This makes it possible to suppress damage to the pattern, while suppressing the amount of charge and improving the image feature amount.

[0067] <Regarding Modifications of the Present Disclosure> The present disclosure is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present disclosure, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0068] In the above embodiment, the image contrast has been described as an example of the image feature. However, other image features representing image quality, such as the image brightness value of the region of interest, may be used instead of or in combination with the image contrast. In addition to the CD value, any value that can be compared with the specification value of the sample 104 may be used as the image feature.

[0069] The procedure for adjusting the light irradiation amount in the same manner as in the charged particle beam system 1 described in the above embodiment can also be applied to a general-purpose scanning electron microscope or the like.

[0070] In the above embodiments, simultaneously irradiating the sample 104 with light and a charged particle beam includes any of the following: (a) at least a portion of the period during which the sample 104 is irradiated with light and the period during which the sample 104 is irradiated with the charged particle beam overlap; or (b) irradiating the sample 104 with light and then quickly irradiating the sample 104 with the charged particle beam a very short time after the light irradiation and before the effect of removing the charge on the sample 104 by the light irradiation is diminished. In either case, it can be considered that the sample 104 is effectively irradiated with light and a charged particle beam simultaneously.

[0071] 1: Charged particle beam device 104: Sample 105: Detector 106: Energy filter 107: Light source 108: Light control unit 109: Control unit 110: Image processing unit 111: Image display unit 112: Storage unit 2: Computer system

Claims

1. A charged particle beam apparatus comprising: a charged particle column that irradiates a sample with a charged particle beam; a light source that irradiates the sample with light; a detector that detects secondary charged particles generated from the sample by irradiating the sample with the charged particle beam and outputs a detection signal representing the intensity of the secondary charged particles; and a computer system that generates an image of the sample based on the detection signal, wherein the computer system acquires feature quantities of the sample for each dose of light irradiated onto the sample, calculates the dose at which the difference between the feature quantities for each dose satisfies a predetermined condition, and controls the light source to irradiate the light of the calculated dose.

2. The charged particle beam device according to claim 1, characterized in that the feature is the charge amount of the sample or a first image feature amount possessed by the image, and the computer system calculates the irradiation amount such that at least one of the charge amount or the first image feature amount satisfies the specified condition.

3. The charged particle beam apparatus according to claim 1, characterized in that the computer system determines, as the predetermined condition, whether or not the absolute difference between the feature amount when the sample is irradiated with the charged particle beam but not with the light, and the feature amount when the sample is irradiated with both the charged particle beam and the light or when the sample is irradiated with the light and then with the charged particle beam, is equal to or greater than a threshold value.

4. The charged particle beam device according to claim 1, characterized in that the computer system calculates the difference while changing the irradiation dose in stages, and the computer system determines, as the predetermined condition, whether the difference between adjacent stages is equal to or less than a threshold value.

5. A charged particle beam device as described in claim 1, characterized in that the computer system searches for the irradiation dose that satisfies the specified condition by repeatedly comparing the difference with the specified condition while gradually changing the irradiation dose.

6. A charged particle beam device according to claim 2, characterized in that the computer system determines whether the charge amount satisfies a first condition and the first image feature amount satisfies a second condition as the predetermined conditions.

7. A charged particle beam device as described in claim 6, characterized in that the computer system searches for the irradiation amount that satisfies the specified condition by repeatedly comparing the charge amount with the first condition and the first image feature amount with the second condition while gradually changing the irradiation amount.

8. The charged particle beam device according to claim 1, characterized in that the computer system calculates the dimension of the pattern on the sample contained in the image as the feature while gradually changing the irradiation dose, and the computer system determines, as the predetermined condition, whether the absolute difference between the dimension at each irradiation dose and the specification value of the dimension is equal to or less than a threshold value.

9. A charged particle beam device as described in claim 8, characterized in that the computer system calculates image features of the image in addition to the dimensions as the features, and the computer system searches for the irradiation dose at which the dimensions and image features satisfy the specified conditions by repeatedly comparing the difference with the specified conditions while gradually changing the irradiation dose.

Images