Charged particle beam drawing device and charged particle beam drawing method

Abstract

Provided are a charged particle beam drawing device and a charged particle beam drawing method with which it is possible to extend the lifetime of a high vacuum gauge while suppressing the focus shift of a charged particle beam. A charged particle beam drawing apparatus according to an embodiment of the present invention draws a pattern by irradiating a substrate to be drawn with a charged particle beam in a chamber. The charged particle beam drawing apparatus includes: a supply device that supplies a cleaning gas to the chamber; a vacuum pump that discharges gas from the chamber; the pressure sensor is used for detecting the pressure in the chamber; and a control device that acquires a detection value of the pressure sensor and controls the supply device so that the pressure in the chamber becomes a first target value. The control device also controls the supply device so that the pressure in the chamber becomes a second target value different from the first target value when adjusting the charged particle beam irradiated to the substrate.

Description

[0001] Related Applications

[0002] This application claims the priority of Japanese Patent Application No. 2023-094908 (filing date: June 8, 2023) as a basic application. The present application incorporates the entire contents of the basic application by reference. Technical Field

[0003] The present invention relates to a charged particle beam delineation device and a charged particle beam delineation method. Background Art

[0004] With the high integration of LSI, the circuit line width required by semiconductor devices is becoming finer year by year. In order to form the desired circuit pattern on the semiconductor device, the following method is adopted: using a reduced projection exposure device, a high-precision original pattern (mask, or also called intermediate mask used in stepper exposure device and scanner) formed on quartz is reduced and transferred to the wafer. The high-precision original pattern is drawn by an electron beam drawing device, using the so-called electron beam lithography technology.

[0005] In an electron beam drawing device, an electron beam is deflected by a deflector, thereby irradiating the beam to a desired position to draw a pattern. As the drawing device is used, hydrocarbon-based contaminants (contaminants) adhere to the electron optical system components such as the deflector. If electric charges are accumulated in the contaminants, there is a problem of a beam drift phenomenon in which the irradiation position of the electron beam is shifted.

[0006] There is a known method of introducing a clean gas such as ozone gas into a column of a drawing device to keep the electron optical system components clean while drawing. For example, the ozone introduced into the column is collided with an electron beam to separate the ozone into oxygen and active oxygen. The separated active oxygen is reacted with pollutants to change into carbon monoxide gas and exhaust it, thereby reducing the pollutants attached to the electron optical system components.

[0007] If the pressure in the column fluctuates due to the introduction of the cleaning gas, the electron beam focus will shift, so the pressure in the column is controlled to be constant. In the conventional drawing device, if the gas generated from the components in the device gradually decreases with use, the amount of ozone gas introduced is gradually increased to maintain the pressure in the column.

[0008] However, in such a conventional drawing apparatus, since the pressure in the column is always in a high state, there is a problem that the high vacuum gauge (pressure gauge) for pressure measurement deteriorates rapidly. Summary of the invention

[0009] The present invention provides a charged particle beam mapping device and a charged particle beam mapping method capable of suppressing focus deviation of a charged particle beam and extending the life of a high vacuum gauge.

[0010] A charged particle beam drawing device according to one embodiment of the present invention draws a pattern by irradiating a charged particle beam onto a substrate of a drawing object in a chamber, and the charged particle beam drawing device comprises: a supply device for supplying a cleaning gas to the chamber; a vacuum pump for exhausting gas from the chamber; a pressure sensor for detecting the pressure in the chamber; and a control device for obtaining a detection value of the pressure sensor and controlling the supply device so that the pressure in the chamber becomes a first target value. The control device also controls the supply device so that the pressure in the chamber becomes a second target value different from the first target value when adjusting the charged particle beam irradiated onto the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of a multi-beam imaging device according to an embodiment of the present invention.

[0012] Figure 2 is a top view of the shaped aperture array plate.

[0013] Figure 3 It is a graph showing the change in the internal pressure of the vacuum chamber of the comparative example.

[0014] Figure 4 This is a flowchart illustrating the drawing method of this embodiment.

[0015] Figure 5 This is a graph showing an example of the change in the internal pressure of the vacuum chamber.

[0016] Figure 6 This is a diagram showing an example of a parameter setting screen. DETAILED DESCRIPTION

[0017] In the following embodiments, a configuration using an electron beam as an example of a charged particle beam will be described, but the charged particle beam is not limited to an electron beam, and may be a beam using charged particles such as an ion beam.

[0018] Figure 1 2 is a schematic diagram of the structure of a drawing device according to an embodiment. Figure 1As shown, the drawing device 100 includes a drawing unit W and a control system C. The drawing device 100 is an example of a multi-charged particle beam drawing device. The drawing unit W includes a vacuum chamber 60 composed of an electron optical lens barrel 60a and a drawing chamber 60b. The drawing chamber 60b is a rectangular hollow component with a circular opening formed on the upper surface. The electron optical lens barrel 60a is a cylindrical shell with the length direction as the Z-axis direction, and is inserted into the opening formed on the upper surface of the drawing chamber 60b.

[0019] An electron gun 201 , an illumination lens 202 , a shaping aperture array plate 203 , a blanking aperture array plate 204 , a reduction lens 205 , an aperture limiting component 206 , an objective lens 207 , and a deflector 208 are arranged in the electron optical lens barrel 60 a .

[0020] An XY stage 105 is disposed in the drawing chamber 60b. A substrate 101 to be drawn is disposed on the XY stage 105. The substrate 101 is, for example, a mask blank or a semiconductor substrate (silicon wafer).

[0021] Furthermore, a pressure sensor 50 (high vacuum gauge) is disposed in the internal space of the vacuum chamber 60. The pressure sensor 50 outputs a voltage signal having a value corresponding to the pressure in the chamber.

[0022] The control system C includes a control device 110, a stage driving device 120, a deflection control circuit 130, a storage unit 140, a clean gas supply device 30, a vacuum pump 40, and a touch panel 70. Drawing data is input from the outside and stored in the storage unit 140. The drawing data defines information of a plurality of graphic patterns describing a pattern to be formed on the substrate 101. Specifically, a graphic code, coordinates, size, etc. are defined for each graphic pattern.

[0023] The control device 110 is a computer having a CPU, and centrally controls the drawing unit W, the stage driving device 120 , the deflection control circuit 130 , the cleaning gas supply device 30 , the vacuum pump 40 , and the touch panel 70 .

[0024] The electron beam 200 emitted from the electron gun 201 of the drawing unit W passes through the illumination lens 202 to illuminate the entire forming aperture array plate 203 .

[0025] Figure 2 2 is a conceptual diagram showing the structure of the forming aperture array plate 203. Figure 2 As shown, a plurality of openings 203a are formed in the shaping aperture array plate 203 at a predetermined arrangement pitch along the longitudinal direction (y direction) and the transverse direction (x direction). Each opening 203a is preferably formed by a rectangle or a circle of the same size and shape. A part of the electron beam 200 passes through these plurality of openings 203a, thereby forming (emitting) multiple beams 20a to 20e.

[0026] In the blanking aperture array plate 204, a through hole is formed to match the configuration position of each opening 203a of the shaping aperture array plate 203. A blanker consisting of a pair of two electrodes is arranged in each through hole. One electrode of the blanker is grounded and maintained at the ground potential, and the other electrode is switched to the ground potential or a potential other than the ground potential, thereby switching the deflection of the beam passing through the through hole on and off to perform blanking control. When the blanker does not deflect the beam, the beam is turned on. When the blanker deflects the beam, the beam is turned off. In this way, multiple blankers perform blanking deflection of each corresponding beam in the multiple beams after passing through the multiple openings 203a of the shaping aperture array plate 203.

[0027] The multiple beams 20 a to 20 e that have passed through the blanking aperture array plate 204 are reduced by the reduction lens 205 and travel toward the opening formed in the limiting aperture member 206 .

[0028] Here, the beam controlled to be in the beam-off state is deflected by the blanker, passes through a track passing outside the opening of the limiting aperture member 206, and is therefore shielded by the limiting aperture member 206. On the other hand, the beam controlled to be in the beam-on state is not deflected by the blanker, and thus passes through the opening of the limiting aperture member 206. In this way, blanking control is performed by turning on / off the deflection of the blanker, and the closing / opening of the beam is controlled.

[0029] The multiple beams passing through the limiting aperture member 206 are focused by the objective lens 207 to form a pattern image of a desired reduction ratio. The beams (the entire multiple beams) passing through the limiting aperture member 206 are collectively deflected in the same direction by the deflector 208 and irradiated to a desired position on the substrate 101.

[0030] When the XY stage 105 is continuously moved by the stage driving device 120, at least during the period of irradiating the substrate 101 with the beam, the irradiation position of the beam is controlled by the deflector 208 so as to follow the movement of the XY stage 105. The multiple beams irradiated at one time are preferably arranged at a pitch obtained by multiplying the arrangement pitch of the multiple openings 203a of the forming aperture array plate 203 by the above-mentioned desired reduction ratio.

[0031] The control device 110 virtually divides the drawing area of ​​the substrate 101 into a plurality of grid areas. The size of the grid area is, for example, the same as the size of one single beam included in the multi-beam, and each grid area becomes a pixel (unit irradiation area). The control device 110 reads the drawing data from the storage unit 140, and uses the pattern defined in the drawing data to calculate the pattern area density ρ of each pixel.

[0032] The control device 110 multiplies the pattern area density ρ by the reference irradiation amount D0 , calculate the irradiation amount ρD of the beam irradiating each pixel 0 The correction coefficient for correcting the proximity effect or the like may be further multiplied. The control device 110 divides the irradiation amount by the current amount of each of the plurality of individual beams constituting the multi-beam, and calculates the irradiation time of each of the plurality of individual beams.

[0033] The control device 110 rearranges the irradiation time data in the transmission order along the drawing order, generates irradiation time control data, and outputs it to the deflection control circuit 130. The deflection control circuit 130 outputs the irradiation time control data to the blanking aperture array board 204. The input and output circuit of the blanking aperture array board 204 transmits the irradiation time data to the corresponding blanker.

[0034] The plurality of individual beams constituting the multi-beam expose different pixels simultaneously, and each beam is turned on only for a necessary time in order to provide a desired exposure amount for each pixel.

[0035] In multi-beam drawing, beam adjustment such as focusing is important. For example, the method described in Japanese Patent Publication No. 2018-82120 is used to find the optimal lens value (excitation current value) of the objective lens 207 and focus. It is also possible to adjust the reduction ratio of the multi-beam using the method described in Japanese Patent Publication No. 2017-199758 and adjust the deflection sensitivity using the method described in Japanese Patent Publication No. 10-284392. Beam adjustment is performed at a specified time interval.

[0036] The cleaning gas supply device 30 is connected to the vacuum chamber 60 via a pipe, and includes a cleaning gas generator, a flow rate regulating valve for regulating the amount of cleaning gas introduced into the vacuum chamber 60, etc. The cleaning gas supply device 30 supplies the cleaning gas into the vacuum chamber 60 at a flow rate instructed by the control device 110. The cleaning gas is, for example, ozone gas.

[0037] The vacuum pump 40 exhausts the gas inside the vacuum chamber 60 based on the instruction of the control device 110 to maintain the inside of the vacuum chamber 60 at a predetermined pressure or less.

[0038] In order to suppress the focus deviation of the multi-beam, the control device 110 obtains the measured value of the pressure sensor 50 at a predetermined period, and controls the cleaning gas supply device 30 and the vacuum pump 40 so that the internal pressure of the vacuum chamber 60 is constant. For example, the control device 110 controls the valve opening of the cleaning gas supply device 30 and the start and stop of the vacuum pump 40 based on the measured value of the pressure sensor 50. The generated gas from the blanking aperture array plate 204 and other components in the vacuum chamber 60 gradually decreases over time. Figure 3As shown in FIG. 1 , when the internal pressure of the vacuum chamber 60 is controlled to be a constant value P, the amount of the cleaning gas introduced into the vacuum chamber 60 is gradually increased, and the partial pressure of the cleaning gas in the vacuum chamber 60 is gradually increased. Figure 3 In the graph of , the gray portion is the partial pressure of the cleaning gas, the white portion is the partial pressure of the gas generated from the components in the chamber, and the chamber internal pressure is the sum of these.

[0039] In the multi-beam imaging device, there are many parts in the vacuum chamber 60. Especially at the beginning of operation, the amount of gas generated is large, so the initial internal pressure is high, and the target value P of the pressure constant control also becomes high. If the internal pressure of the vacuum chamber 60 is high for a long time, the pressure sensor 50 will deteriorate prematurely.

[0040] Therefore, in this embodiment, the target value of the pressure constant control is lowered at the timing of beam adjustment. If the target value of the pressure constant control is lowered, the internal pressure of the vacuum chamber 60 changes, but since the beam adjustment is performed, the focus deviation of the multi-beam is suppressed.

[0041] according to Figure 4 The flowchart shown explains the multi-beam imaging method of this embodiment.

[0042] The control device 110 activates the vacuum pump 40 (step S1 ). Gas in the vacuum chamber 60 is exhausted, and the pressure inside the chamber is reduced.

[0043] The cleaning gas supply device 30 supplies the cleaning gas into the vacuum chamber 60 (step S2 ).

[0044] The control device 110 controls the cleaning gas supply device 30 based on the measured value of the pressure sensor 50 to adjust the gas supply amount so that the internal pressure of the vacuum chamber 60 becomes a predetermined target value (within the target range) (step S3_No, S4). The target value is based on the internal pressure of the vacuum chamber 60 before the start of the cleaning gas supply. For example, it is a value obtained by adding a predetermined value to the internal pressure of the vacuum chamber 60 before the start of the cleaning gas supply, or a value obtained by multiplying it by a predetermined multiplication factor. The user can arbitrarily set the predetermined addition value and multiplication factor by operating the touch panel 70.

[0045] For example, the touch panel 70 displays the following Figure 6 The parameter setting screen is shown. The user presses touch key 73 to set a predetermined addition value (partial pressure (B) of the cleaning gas) in advance. The internal pressure of the vacuum chamber 60 before the start of the cleaning gas supply is displayed in display field 72. The target value is displayed in display field 74.

[0046] While controlling the pressure in the chamber to be constant at the target value, the multi-beam is formed by the above method and irradiated to the substrate 101 to draw the desired pattern (step S3_Yes, S5). The detection value (measurement value) of the pressure sensor 50 is displayed in real time in the display column 71 of the parameter setting screen.

[0047] When the timing for beam adjustment comes (step S6_Yes), the supply of the cleaning gas from the cleaning gas supply device 30 is stopped (step S7).

[0048] The control device 110 obtains the internal pressure of the vacuum chamber 60 from the pressure sensor 50 after a predetermined time (e.g., about 3 minutes) has passed since the supply of the cleaning gas was stopped (step S8). At this time, the cleaning gas is almost completely exhausted from the vacuum chamber 60 by the vacuum pump 40, and the pressure in the chamber measured by the pressure sensor 50 is derived from the gas generated from the components in the chamber (equivalent to Figure 3 (white part of the graph).

[0049] The control device 110 calculates a new target value of the pressure in the chamber based on the measured pressure in step S8, and updates the target value (step S9). For example, the new target value is calculated by adding a predetermined value to the measured pressure in step S8 or multiplying it by a predetermined multiplier. The measured pressure in step S8 is displayed in the display column 72 of the parameter setting screen. The new target value obtained by adding the partial pressure (B) of the cleaning gas set by the touch key 73 to the measured pressure is displayed in the display column 74.

[0050] The supply of the cleaning gas is restarted (step S10 ), and the cleaning gas supply device 30 is controlled to adjust the gas supply amount so that the internal pressure of the vacuum chamber 60 becomes the updated target value (steps S11 —No, S12 ).

[0051] When the pressure in the chamber reaches the target value (step S11_Yes), beam adjustment is performed (step S13). In beam adjustment, focus, reduction ratio adjustment, deflection sensitivity adjustment, etc. are performed. After beam adjustment, pattern drawing is resumed.

[0052] Figure 5 An example of the change in the internal pressure of the vacuum chamber 60 is shown. In this example, the initial target value of the internal pressure constant control of the vacuum chamber 60 is P0. When it is the timing T1 of the beam adjustment, the cleaning gas is exhausted to measure the pressure in the chamber and update it to a new target value P1. Since the amount of gas generated from the components in the chamber is reduced, the updated target value P1 becomes a value smaller than the target value P0 before the update.

[0053] Before the next beam adjustment timing T2, the pressure in the chamber is controlled to be P1. When the beam adjustment timing T2 is reached, the cleaning gas is exhausted to measure the pressure in the chamber and update it to a new target value P2. Since the amount of gas generated from the components in the chamber is reduced, the updated target value P2 becomes a value smaller than the target value P1 before the update.

[0054] Before the timing T3 of the next beam adjustment, control is performed so that the pressure in the chamber becomes P2.

[0055] Thus, in this embodiment, as the amount of gas generated from the components in the chamber decreases, the target value of the pressure constant control in the vacuum chamber 60 is gradually reduced at the timing of each beam adjustment. By reducing the target value of the pressure constant control, the internal pressure of the vacuum chamber 60 changes, but since the beam adjustment is performed, the focus deviation of the multi-beam can be suppressed.

[0056] Since the internal pressure of the vacuum chamber 60 decreases at the timing of each beam adjustment, the internal pressure of the vacuum chamber 60 does not continue to be high, and degradation of the pressure sensor 50 can be suppressed, thereby extending the life of the pressure sensor 50 .

[0057] In addition, the amount of cleaning gas supplied to the vacuum chamber 60 can be reduced.

[0058] In the above embodiment, an example is described in which a target value of the constant pressure control is automatically calculated and updated by adding a predetermined value (first predetermined value) to the pressure in the chamber after the purge gas is exhausted. However, if the calculated target value of the constant pressure control is less than a predetermined threshold value (second predetermined value), a value (third predetermined value) set in advance by the user may be used as a new target value. In this way, it is possible to prevent the target value of the constant pressure control from becoming too low.

[0059] The user can press Figure 6 The user can set an arbitrary threshold value (Th) by pressing a touch key 75 of the parameter setting screen shown in the figure. In addition, the user can press a touch key 76 to manually set a target value (SV_f) of the chamber internal pressure.

[0060] When the timing for beam adjustment comes, a new target value is calculated by adding the cleaning gas partial pressure (B) set by the user to the internal pressure (A) after the cleaning gas is exhausted, and is displayed in the display field 73 .

[0061] When the calculated target value is smaller than the preset threshold value (Th), the target value of the pressure constant control becomes the target value (SV_f) set by the user. Thereafter, the automatic calculation and update process of the target value (steps S7 to S12) is skipped and the target value is constant.

[0062] It is also possible to replace components in the vacuum chamber 60 such as the blanking aperture array plate 204 at the timing of beam adjustment. In this case, the generated gas increases due to the replacement of the components, the measured pressure in step S8 becomes higher, and the new target value calculated by adding a predetermined value or multiplying by a predetermined magnification may be higher than the previous target value (before the component replacement).

[0063] Furthermore, when the previous target value is the target value (SV_f) set by the user and the new target value calculated after the component replacement is also less than the target value (SV_f) set by the user, the target value may not be changed (SV_f is maintained).

[0064] In the above-mentioned embodiment, a multi-beam drawing device is described, but the drawing device may be a single-beam drawing device.

[0065] In addition, the present invention is not limited to the above-mentioned embodiments, and the constituent elements can be deformed and concretized in the implementation stage without departing from the scope of its main purpose. In addition, various inventions can be formed by appropriate combinations of multiple constituent elements disclosed in the above-mentioned embodiments. For example, several constituent elements can also be deleted from all the constituent elements shown in the embodiments. In addition, the constituent elements of different embodiments can also be appropriately combined.

[0066] [Explanation of Reference Numerals]

[0067] 30 Clean gas supply device

[0068] 40 Vacuum pump

[0069] 50 Pressure Sensor

[0070] 60 Vacuum chamber

[0071] 100 Drawing Device

[0072] 110 Control device

Claims

1. A charged particle beam drawing device, which draws a pattern by irradiating a charged particle beam to a substrate to be drawn in a chamber, The charged particle beam mapping device comprises: a supply device for supplying a cleaning gas to the chamber; a vacuum pump to exhaust gas from the chamber; a pressure sensor for detecting the pressure in the chamber; and a control device that obtains a detection value of the pressure sensor and controls the supply device so that the pressure in the chamber becomes a first target value, The control device further controls the supply device so that the pressure in the chamber becomes a second target value different from the first target value when adjusting the charged particle beam irradiated onto the substrate.

2. The charged particle beam mapping device according to claim 1, in, The control device controls the supply device to stop supply of the cleaning gas before adjusting the charged particle beam, and calculates the second target value based on a detection value of the pressure sensor after a predetermined time has passed since the supply of the cleaning gas was stopped.

3. The charged particle beam mapping device according to claim 2, in, The control device controls the supply device to stop supply of the cleaning gas before adjusting the charged particle beam, and calculates the second target value by adding a predetermined value to a detection value of the pressure sensor after a predetermined time has passed since the supply of the cleaning gas was stopped.

4. The charged particle beam mapping device according to claim 2, in, The control device controls the supply device to stop the supply of the cleaning gas before adjusting the charged particle beam, and sets the third specified value as the second target value when a value obtained by adding the first specified value to the detection value of the pressure sensor after a specified time has passed since the supply of the cleaning gas was stopped is less than the second specified value.

5. The charged particle beam mapping device according to claim 1, in, The second target value is smaller than the first target value.

6. The charged particle beam mapping device according to claim 1, in, The adjustment of the charged particle beam includes focusing, deflection sensitivity adjustment or adjustment of the reduction ratio of the multi-beam.

7. A charged particle beam drawing method, wherein a charged particle beam is irradiated on a substrate to be drawn in a chamber to draw a pattern, The charged particle beam drawing method comprises: supplying a cleaning gas to the chamber; the step of exhausting gas from the chamber; The process of detecting the pressure in the chamber by using a pressure sensor; a step of controlling the supply amount of the cleaning gas based on a detection value of the pressure sensor so that the pressure in the chamber reaches a first target value; and performing a step of adjusting the charged particle beam irradiated onto the substrate, controlling the supply amount of the cleaning gas to adjust the pressure in the chamber to a second target value different from the first target value, After the adjustment, the supply amount of the cleaning gas is controlled so that the pressure in the chamber reaches the second target value.

8. The charged particle beam delineation method according to claim 7, in, stopping the supply of the cleaning gas, The second target value is calculated based on a detection value of the pressure sensor after a predetermined time has passed since the supply of the cleaning gas was stopped.

9. The charged particle beam delineation method according to claim 8, in, The second target value is calculated by adding a predetermined value to a detection value of the pressure sensor after a predetermined time has passed since the supply of the cleaning gas was stopped.

10. The charged particle beam mapping method according to claim 8, in, When a value obtained by adding a first predetermined value to a detection value of the pressure sensor after a predetermined time has elapsed since the supply of the cleaning gas was stopped is smaller than a second predetermined value, a third predetermined value is set as the second target value.

11. The charged particle beam drawing method according to claim 7, in, The second target value is smaller than the first target value.

12. The charged particle beam mapping method according to claim 7, in, The adjustment of the charged particle beam includes focusing, deflection sensitivity adjustment or adjustment of the reduction ratio of the multi-beam.

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