JP2018133494A - Evaluation method of charged particle beam drawing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain a preferable settling time.SOLUTION: An evaluation method of a charged particle beam drawing apparatus according to an embodiment deflects a charged particle beam by using a deflector controlled by a DAC amplifier to draw a pattern on a substrate. In this method, a step of drawing a line-like evaluation pattern in which a plurality of evaluation target pattern portions and reference pattern portions are alternately arranged is executed for each settling time while varying the settling time of the DAC amplifier, a plurality of evaluation patterns are drawn, roughness of the plurality of evaluation patterns is measured, and a settling time of the DAC amplifier is determined on the basis of the measured roughness.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for evaluating a charged particle beam drawing apparatus.

  With the high integration of LSI, the circuit line width of a semiconductor device has been reduced year by year. In order to form a desired circuit pattern on a semiconductor device, a reduction projection type exposure apparatus is used to form a high-precision original pattern pattern formed on quartz (a mask, or a pattern used particularly in a stepper or scanner is also called a reticle). )) Is reduced and transferred onto the wafer. A high-precision original pattern is drawn by an electron beam drawing apparatus, and so-called electron beam lithography technology is used.

  The electron beam drawing apparatus performs drawing by deflecting an electron beam with a deflector. The role of beam deflection by the deflector includes, for example, control of the shape and size of the beam shot, control of the shot position, and blanking of the beam. When the deflector is driven with an output voltage from a DAC (digital analog converter) amplifier, settling time (settling time) of the output voltage corresponding to the load is required. Here, if the settling time is insufficient, an error occurs in the deflection movement amount of the electron beam, and the drawing accuracy is lowered. On the other hand, if the settling time is too long, the throughput decreases. For this reason, it is desirable to set a settling time as short as possible within a range where the drawing accuracy does not deteriorate.

  Conventionally, a plurality of evaluation patterns are drawn on the evaluation mask while changing the settling time, and the reference pattern is drawn with a sufficiently long settling time, and the dimension measurement result of the evaluation pattern and the dimension measurement result of the reference pattern To determine the optimal settling time. If the evaluation pattern and the reference pattern are separated from each other, the process-induced dimensional variation may occur. Therefore, the reference pattern is drawn in the vicinity of each of the plurality of evaluation patterns having different settling times. In order to evaluate each settling time, it is necessary to measure the dimension of the evaluation pattern and the dimension of the reference pattern corresponding to this, so that it takes time to determine the optimum settling time.

JP 2014-41952 A JP 2009-88202 A JP2013-58699A JP 2014-183267 A Japanese Patent Laying-Open No. 2015-153873 JP 2016-149400 A JP 2013-74130 A Japanese Patent Laid-Open No. 2008-71986

  It is an object of the present invention to provide a method for evaluating a charged particle beam drawing apparatus capable of efficiently obtaining a suitable settling time.

  An evaluation method for a charged particle beam drawing apparatus according to an aspect of the present invention is an evaluation method for a charged particle beam drawing apparatus that draws a pattern on a substrate by deflecting the charged particle beam using a deflector controlled by a DAC amplifier. The step of drawing a line-shaped evaluation pattern in which a plurality of evaluation target pattern portions and reference pattern portions are alternately arranged is performed for each settling time while varying the settling time of the DAC amplifier, and a plurality of the evaluation patterns , The roughness of the plurality of evaluation patterns is measured, and the settling time of the DAC amplifier is determined based on the measured roughness.

  In the evaluation method of the charged particle beam drawing apparatus according to one aspect of the present invention, the DAC amplifier is connected to a first shaping deflector that controls a shot shape, and the evaluation target pattern portion and the reference pattern portion include a plurality of the evaluation target pattern portions. This pattern is a combination of figures of various shapes. When drawing the evaluation target pattern portion, the shot shape is changed for each shot, and when drawing the reference pattern portion, the same shot shape is shot continuously. .

  In the evaluation method of the charged particle beam drawing apparatus according to one aspect of the present invention, the evaluation object pattern portion and the reference pattern portion include a plurality of rectangular patterns in which rectangles and / or right triangles are combined in different ways.

  In the evaluation method of the charged particle beam drawing apparatus according to an aspect of the present invention, the DAC amplifier is connected to a second deflector that controls a shot size, and the evaluation target pattern unit includes a plurality of rectangles having different sizes. When drawing the evaluation target pattern part, the shot size is changed for each shot, and the evaluation target pattern part is a rectangular pattern composed of one rectangle or a plurality of rectangles of the same size. When the reference pattern portion is drawn, the same shot size is shot continuously.

  In the evaluation method of the charged particle beam drawing apparatus according to an aspect of the present invention, the DAC amplifier is connected to an objective deflector that controls an irradiation position of the charged particle beam on the substrate, and the evaluation target pattern unit and the reference The pattern part is a pattern in which a plurality of rectangles of the same size are combined. When the evaluation target pattern part is drawn, the settling time of the evaluation target is set in the DAC amplifier, and the reference pattern part is drawn. A settling time longer than the settling time of the evaluation target is set.

  According to the present invention, a suitable settling time can be obtained efficiently.

1 is a schematic diagram of an electron beam drawing apparatus according to a first embodiment of the present invention. It is the schematic explaining the beam shaping in the 1st embodiment. It is a figure which shows the example of the overlap position of the 1st aperture image and the variable shaping | molding opening of a 2nd shaping | molding aperture. (A) and (b) are figures which show the example of the part which passes the variable shaping | molding opening of a 1st aperture image. (A) and (b) are figures which show the example of the part which passes the variable shaping | molding opening of a 1st aperture image. It is the schematic for demonstrating a drawing area | region. It is a figure which shows the evaluation pattern by a comparative example. It is a figure which shows the evaluation pattern in the said 1st Embodiment. (A)-(e) is a figure explaining the drawing method of the evaluation pattern in the 1st embodiment. (A) and (b) are top views of a light shielding film pattern. (A)-(g) is a figure which shows the combination of the figure which comprises a rectangular pattern. It is a figure which shows the evaluation pattern in the 2nd Embodiment. (A) and (b) are figures which show the evaluation pattern in the 3rd embodiment. (A) and (b) are figures which show the evaluation pattern in the 4th embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic view of an electron beam drawing apparatus according to the first embodiment of the present invention. An electron beam drawing apparatus 100 shown in FIG. 1 is a variable shaping type drawing apparatus including a drawing unit 150 and a control unit 160.

  The drawing unit 150 includes an electron column 102 and a drawing chamber 103. In the electron column 102, there are an electron gun 201, an illumination lens 202, a blanker 212, a blanking aperture 214, a first shaping aperture 203, a projection lens 204, a first shaping deflector 220, a second shaping deflector 222, and a second. A shaping aperture 206, an objective lens 207, a main deflector 232 (first objective deflector), a sub deflector 230 (second objective deflector), and a sub sub deflector 234 (third objective deflector) are arranged. .

  The first shaping deflector 220 and the second shaping deflector 222 are provided with eight pairs (16 pieces) of electrodes arranged at equal intervals in a circumferential shape, and electrons are applied by applying a voltage between the opposing electrodes. It is configured to deflect the beam.

  An XY stage 105 is arranged in the drawing chamber 103. On the XY stage 105, a sample 101 such as a mask (reticle) coated with a resist and a semiconductor wafer, which is a drawing target substrate, is disposed.

  The control unit 160 includes a control computer 110, a deflection control circuit 120, digital-analog conversion (DAC) units 130, 132, 134, 136, 137, 138, and a storage device 140 such as a magnetic disk device. The control computer 110, the deflection control circuit 120, and the storage device 140 are connected to each other via a bus. The deflection control circuit 120 and the DAC units 130, 132, 134, 136 to 138 are connected to each other via a bus.

  The control computer 110 includes a shot data generation unit 112, a memory 114, and a settling time setting unit 116. The shot data generation unit 112 and the settling time setting unit 116 may be configured by hardware or software.

  The deflection control circuit 120 includes a deflection amount calculation unit 122, a deflection signal generation unit 124, and a memory 126. The deflection amount calculation unit 122 and the deflection signal generation unit 124 may be configured by hardware or software. Input / output data of the deflection amount calculation unit 122 and the deflection signal generation unit 124 and data being calculated are appropriately stored in the memory 126.

  The DAC unit 130 converts the blanking signal output from the deflection control circuit 120 from digital to analog, amplifies it, and outputs a deflection voltage applied to the blanker 212.

  The DAC unit 132 converts the first shaping deflection signal output from the deflection control circuit 120 from digital to analog, amplifies it, and outputs a deflection voltage applied to the first shaping deflector 220.

  The DAC unit 134 converts the second shaping deflection signal output from the deflection control circuit 120 from digital to analog, amplifies it, and outputs a deflection voltage applied to the second shaping deflector 222.

  The DAC unit 136 converts the sub deflection data signal output from the deflection control circuit 120 from digital to analog, amplifies it, and outputs a deflection voltage applied to the sub deflector 230.

  The DAC unit 137 converts the main deflection data signal output from the deflection control circuit unit 120 from digital to analog, amplifies it, and outputs a deflection voltage applied to the main deflector 232.

  The DAC unit 138 converts the sub-sub deflection data signal output from the deflection control circuit 120 from digital to analog, amplifies the signal, and outputs a deflection voltage applied to the sub-sub deflector 234.

  The storage device 140 (storage unit) stores drawing data (layout data) composed of a plurality of graphic patterns from the outside.

  The electron beam 200 emitted from the electron gun 201 (emission unit) provided in the electron column 102 is blanked by the blanker 212 when it passes through the blanker 212 (blanking deflector) in the beam-on state. It is controlled to pass through the aperture 214, and in the beam-off state, the entire beam is deflected so as to be shielded by the blanking aperture 214. The electron beam 200 that has passed through the blanking aperture 214 until the beam is turned off after the beam is turned off becomes one shot of the electron beam.

  The blanker 212 controls the direction of the passing electron beam 200 to alternately generate a beam-on state and a beam-off state. For example, no deflection voltage is applied to the blanker 212 when the beam is on, and a deflection voltage is applied to the blanker 212 when the beam is off. The irradiation amount per shot of the electron beam 200 irradiated on the sample 101 is adjusted according to the irradiation time of each shot.

  The electron beam 200 of each shot generated by passing through the blanker 212 and the blanking aperture 214 is irradiated onto the entire first shaping aperture 203 having a rectangular opening 32 (see FIG. 2) by the illumination lens 202. By passing through the opening 32 of the first shaping aperture 203, the electron beam 200 is shaped into a rectangle.

  The electron beam 200 of the first aperture image that has passed through the first shaping aperture 203 is projected onto the second shaping aperture 206 having the opening 34 (see FIG. 2) by the projection lens 204. At that time, the first shaping deflector 220 and the second shaping deflector 222 control the deflection of the first aperture image projected onto the second shaping aperture 206, and electrons passing through the opening 34 as shown in FIG. The shape and dimensions of the beam can be changed (variable shaping is performed).

  The electron beam 200 of the second aperture image that has passed through the opening 34 of the second shaping aperture 206 is focused by the objective lens 207, and is deflected in three stages by the main deflector 232, the sub deflector 230, and the sub sub deflector 234. The target position of the sample 101 placed on the continuously moving XY stage 105 is irradiated.

  FIG. 2 is a schematic perspective view for explaining beam shaping by the first shaping aperture 203 and the second shaping aperture 206. In the first shaping aperture 203, a rectangular (rectangular or square) opening 32 for shaping the electron beam 200 is formed.

  The second shaping aperture 206 has a variable shaping opening 34 for shaping the electron beam 200 that has passed through the opening 32 of the first shaping aperture 203 into a desired shape. As shown in FIG. 3 to be described later, the variable shaped opening 34 forms sides 34 a and 34 e parallel to one side of the opening 32, sides 34 b and 34 h orthogonal to each other, and 45 degrees or 135 degrees with respect to one side of the opening 32. The sides 34c, 34d, 34f, and 34g are combined.

  The shape of the variable shaping opening 34 will be described in detail. The sides 34c and 34d are orthogonal to each other, and the sides 34f and 34g are orthogonal to each other. One ends of the sides 34f and 34d are connected by a side 34e. One end sides of the sides 34b and 34h are connected to both ends of the side 34a in an orthogonal shape, and the other end sides of the sides 34b and 34h are connected to one end of the sides 34c and 34g, respectively. The variable shaped opening 34 has an octagonal shape sharing a hexagonal portion surrounded by the sides 34c to 34g and a quadrangular portion surrounded by the sides 34a, 34b and 34h and connected to the hexagonal portion.

  The electron beam 200 irradiated from the electron gun 201 and passed through the opening 32 of the first shaping aperture 203 is deflected by the first shaping deflector 220 and the second shaping deflector 222, passes through the variable shaping opening 34, and has a desired shape. It becomes an electron beam of size and shape. An electron beam having a desired size and shape that has passed through a part of the variable shaping opening 34 of the second shaping aperture 206 is mounted on an XY stage 105 that continuously moves in a predetermined direction (for example, the X direction). The irradiated sample 101 is irradiated. That is, the shape of the beam that can pass through both the opening 32 of the first shaping aperture 203 and the variable shaping opening 34 of the second shaping aperture 206 is that of the sample 101 mounted on the XY stage 105 that continuously moves in the X direction. It is drawn in the drawing area.

  In the example of FIG. 2, the rectangular shape is first formed by passing through the opening 32 of the first shaping aperture 203, and then the region including the 135 ° side 34 c of the variable shaping opening 34 of the second shaping aperture 206 is irradiated. . As a result, out of the rectangular electron beam formed at the opening 32, only the electron beam irradiated to the inside of the variable shaping opening 34 from the side 34 c of the variable shaping opening 34 is blocked by the second shaping aperture 206. Instead, it passes through the variable shaped opening 34. As a result, the electron beam 200 is shaped so that the cross-sectional shape perpendicular to the beam axis direction is a right isosceles triangle, and the sample 101 is irradiated with the shot beam 36 having a right isosceles triangle.

  FIG. 3 is a plan view illustrating an example of an overlapping position between the first aperture image 50 that has passed through the opening 32 of the first shaping aperture 203 and the variable shaping opening 34 of the second shaping aperture 206.

  When the electron beam 200 is shaped into a rectangle, the first aperture image 50 is deflected by the first shaping deflector 220 and the second shaping deflector 222 and irradiated to the position indicated by # 1. The hatched portion passing through the variable shaping opening 34 is a shaped image.

  When the electron beam 200 is shaped into a right-angled isosceles triangle with a right-angled corner located in the lower left, the first aperture image 50 is deflected by the first shaping deflector 220 and the second shaping deflector 222 and is halfway along the side 34c. The position indicated by # 2 is irradiated. The hatched portion passing through the variable shaping opening 34 is a shaped image.

  When the electron beam 200 is shaped into a right-angled isosceles triangle with a right-angled corner located at the lower right, the first aperture image 50 is deflected by the first shaping deflector 220 and the second shaping deflector 222 to form the side 34g. Irradiate to the position indicated by # 3 in the middle. The hatched portion passing through the variable shaping opening 34 is a shaped image.

  When the electron beam 200 is shaped into a right-angled isosceles triangle with a right-angled corner located in the upper right, the first aperture image 50 is deflected by the first shaping deflector 220 and the second shaping deflector 222 and is halfway along the side 34f. The position indicated by # 4 is irradiated. The hatched portion passing through the variable shaping opening 34 is a shaped image.

  When the electron beam 200 is shaped into a right-angled isosceles triangle with a right-angled corner located in the upper left, the first aperture image 50 is deflected by the first shaping deflector 220 and the second shaping deflector 222 and is halfway along the side 34d. The position indicated by # 5 is irradiated. The hatched portion passing through the variable shaping opening 34 is a shaped image.

  As shown in FIGS. 4 (a), 4 (b) and 5 (a), 5 (b), by changing the size of the portion of the first aperture image 50 that passes through the variable shaping opening 34, a rectangular or similar shape is obtained. The size of the image (shot) changes while maintaining the right isosceles triangle shape. In FIG. 4A, a small-sized rectangular image is formed by reducing the overlap between the first aperture image 50 and the variable shaping opening 34. In FIG. 4B, a large-sized rectangular image is formed by increasing the overlap between the first aperture image 50 and the variable shaping opening 34. In FIG. 5A, a small-size right-angled isosceles triangle image is formed by reducing the overlap between the first aperture image 50 and the variable shaping opening 34. In FIG. 5B, a large-size right-angled isosceles triangle image is formed by increasing the overlap between the first aperture image 50 and the variable shaping opening 34.

  As described above, by changing the irradiation position (deflection position) of the first aperture image 50 on the second shaping aperture 206, the electron beam 200 is changed into five types of figures (rectangles and four types of right-angled isosceles sides) of a desired size. (Triangle). In the present embodiment, the shot shape is controlled by the first shaping deflector 220, and the shot size is controlled by the second shaping deflector 222.

FIG. 6 is a schematic diagram for explaining a drawing area. In FIG. 6, the drawing region 10 of the sample 101 is virtually divided into a plurality of stripe regions 20 in a strip shape in the y direction, for example, with a deflectable width of the main deflector 232. Each stripe region 20 is virtually divided into a plurality of subfields (SF) 30 in a mesh shape with a deflectable size of the sub deflector 230. Each SF 30 is a deflectable size of the sub-sub deflector 234 and has a plurality of under sub-fields (USF: Tertiary which means a third deflection region in this case) in a mesh shape.
The abbreviation for Field is used as “TF”. ) 40 is virtually divided. A shot figure is drawn at each shot position 42 of each TF 40. The number of TF divisions in each SF is desirably such that the drawing operation is not rate-determined by the thermal diffusion calculation of TF. For example, it is preferably 10 or less in length and width, more preferably 5 or less in length and width.

  When drawing on the sample 101 with the shaped electron beam 200, first, the main deflector 232 deflects the shaped electron beam 200 to the reference position of the SF 30 to be shot. Since the XY stage 105 is moving, the main deflector 232 deflects the electron beam 200 so as to follow the movement of the XY stage 105. Then, the sub deflector 230 deflects the shaped electron beam 200 from the reference position of the SF 30 to the reference position of the TF 40 shot in the SF 30. Then, the electron beam 200 deflected by the sub-sub deflector 234 is irradiated to each position in the TF 40.

  In performing such a drawing operation, first, the shot data generation unit 112 reads drawing data (pattern data) from the storage device 140, and performs a plurality of stages of data conversion processing to generate device-specific shot data. The drawing data defines the shapes and positions of multiple graphic patterns.

  The shot data generation unit 112 divides the graphic pattern defined in the drawing data by the maximum shot size that can be irradiated with one beam shot, and generates a shot graphic. After dividing the graphic pattern, the shot data generating unit 112 generates shot data for each shot graphic. In the shot data, for example, a figure type, a figure size, an irradiation position, an irradiation time, and the like are defined. The deflection amount of the first shaping deflector 220 is controlled by the “graphic type” included in the shot data, and the deflection amount of the second shaping deflector 222 is controlled by the “graphic size”.

  The shot data generation unit 112 allocates each shot data to the TF 40 where the shot graphic is arranged. Further, the shot data generation unit 112 sets the drawing order of a plurality of TFs in the SF for each SF 30. The generated shot data is stored in the memory 114.

  The settling time setting unit 116 sets the settling time for each of the DAC units 130, 132, 134, 136 to 138, and notifies the deflection control circuit 120 of the settling time.

  The deflection control circuit 120 receives shot data stored in the memory 114 from the control computer 110. The deflection amount calculation unit 122 uses the input shot data in the blanker 212, the first shaping deflector 220, the second shaping deflector 222, the main deflector 232, the sub deflector 230, and the sub sub deflector 234. Each deflection amount is calculated.

  The deflection signal generation unit 124 generates a blanking signal from the deflection amount in the blanker 212 and outputs the blanking signal to the DAC unit 130. The deflection signal generator 124 generates a first shaping deflection signal from the deflection amount in the first shaping deflector 220 and outputs the first shaping deflection signal to the DAC unit 132. The deflection signal generator 124 generates a second shaping deflection signal from the deflection amount in the second shaping deflector 222 and outputs the second shaping deflection signal to the DAC unit 134.

  The deflection signal generator 124 generates a main deflection data signal from the deflection amount in the main deflector 232 and outputs the main deflection data signal to the DAC unit 137. The deflection signal generation unit 124 generates a sub deflection data signal from the deflection amount in the sub deflector 230 and outputs the sub deflection data signal to the DAC unit 136. The deflection signal generation unit 124 generates a sub-sub deflection data signal from the deflection amount in the sub-sub deflector 234 and outputs it to the DAC unit 138.

  In addition, the deflection control circuit 120 outputs a control signal to the DAC units 130, 132, 134, and 136 to 138 so that the settling time notified from the settling time setting unit 116 is reached.

  The DAC units 130, 132, 134, 136 to 138 generate a deflection voltage based on the signal output from the deflection control circuit 120 and apply it to each electrode of the corresponding deflector.

  In this embodiment, an evaluation substrate as the sample 101 is placed on the XY stage 105, an evaluation pattern shown below is drawn, and the optimum settling time of the DAC unit 132 is obtained.

  Prior to the description of the method for calculating the optimum settling time according to the present embodiment, the method for calculating the optimum settling time according to the comparative example will be described. FIG. 7 shows an evaluation pattern 310 and a reference pattern 320 according to a comparative example. The evaluation pattern 310 and the reference pattern 320 are line patterns in which # 3 and # 5 right isosceles triangles in FIG. 3 are alternately arranged. In the example shown in FIG. 7, the symbols S1, S2, S3. The reference pattern 320 is drawn in the vicinity of the evaluation pattern 310.

  The evaluation pattern 310 is drawn by alternately shooting the # 3 right isosceles triangle and the # 5 right isosceles triangle from the left end to the right side in the drawing. The first shaping deflector 220 changes the shot shape for each shot. At this time, the settling time to be evaluated is set in the DAC unit 132.

  On the other hand, the reference pattern 320 continuously shots # 3 right isosceles triangles from the left end to the right side in the figure, then returns to the left end, and then continuously shots # 5 right isosceles triangles. While the # 3 right isosceles triangle is continuously shot and while the # 5 right isosceles triangle is continuously shot, the first shaping deflector 220 does not change the shot shape.

  The reference pattern 320 continuously shots the same shape. Hereinafter, performing the shot by rearranging the shot order based on the shape so as to continuously shot the same shape is referred to as “sort ON”. On the other hand, shots in order from the end, regardless of the shape as in the evaluation pattern 310, are referred to as “sort OFF”.

  For each settling time to be evaluated, an evaluation pattern 310 is drawn, and a reference pattern 320 is drawn in the vicinity thereof. The substrate on which the evaluation pattern 310 and the reference pattern 320 are drawn is developed to form a resist pattern, the resist pattern is transferred to the underlying light shielding film, and the dimensions of the light shielding film pattern are measured. The shortest settling time is set as the optimum settling time within a range in which the dimension error between the evaluation pattern and the reference pattern is a predetermined value or less. However, the method according to this comparative example draws the evaluation pattern 310 and the reference pattern 320 for each settling time to be evaluated, and measures each dimension, so that it takes time to obtain the optimum settling time.

  Therefore, in the present embodiment, as shown in FIG. 8, a linear evaluation pattern 400 in which the first pattern portion 410 drawn with sort OFF and the second pattern portion 420 drawn with sort ON are alternately arranged and connected. Draw. For example, the first pattern portion 410 and the second pattern portion 420 are rectangular patterns obtained by combining the # 3 right isosceles triangle and the # 5 right isosceles triangle in FIG. Similarly to FIG. 7, in FIG. 8, the symbols S1, S2, S3.

  A method for drawing the evaluation pattern 900 will be described with reference to FIGS. As shown in FIG. 9A, a # 3 right isosceles triangle is shot, and then a # 5 right isosceles triangle is shot to draw the first first pattern portion 410. Subsequently, as shown in FIG. 9B, a # 3 right isosceles triangle is shot at a predetermined distance from the first first pattern portion 410, and then a # 5 right isosceles is taken. A triangle is shot to draw the second first pattern portion 410.

  By repeating this, as shown in FIG. 9C, a plurality of first pattern portions 410 are drawn at predetermined intervals. In drawing the plurality of first pattern portions 410, # 3 right isosceles triangles and # 5 right isosceles triangles are alternately shot. At this time, the settling time to be evaluated is set in the DAC unit 132.

  Next, as shown in FIG. 9D, a # 5 right isosceles triangle is shot between the first pattern portions 410 (and the right side of the first pattern portion 410 at the right end in the figure).

  Subsequently, as shown in FIG. 9E, the # 3 right-angled isosceles triangle is sequentially shot between the first pattern portions 410 (and on the right side of the first pattern portion 410 at the right end in the drawing). In this way, the first pattern portion 410 (evaluation target pattern portion) drawn with sort OFF and the second pattern portion 420 (reference pattern portion) drawn with sort ON are alternately arranged and connected. An evaluation pattern 400 is drawn.

  Such an evaluation pattern 400 is drawn at every settling time to be evaluated. The substrate on which a plurality of evaluation patterns 400 having different settling times is drawn is developed to form a resist pattern. Subsequently, the lower light shielding film (for example, a chromium film) is etched using the resist pattern as a mask to form a light shielding film pattern. FIG. 10A is a plan view of the light shielding film pattern when the settling time is sufficient, and FIG. 10B is a plan view of the light shielding film pattern when the settling time is insufficient. As shown in FIGS. 10A and 10B, when the settling time is insufficient, the roughness (LER: Line Edge Roughness) is deteriorated.

  The roughness of a plurality of light shielding film patterns having different settling times is measured, and the shortest settling time among the settling times of the light shielding film patterns having the roughness below a predetermined value is calculated as the optimum settling time.

  According to the present embodiment, one evaluation pattern 400 may be drawn for each settling time and the roughness may be measured. As in the comparative example, the optimum settling time of the DAC unit 132 can be efficiently obtained as compared with the method of measuring the dimensions by drawing two patterns of the evaluation pattern 310 and the reference pattern 320 for each settling time. it can.

  In the above embodiment, the roughness position may be Fourier-transformed at the spatial frequency, and it may be determined whether the settling time is sufficient at the peak of the shot period. By this method, the number of dimension measurement points can be reduced.

  In the above embodiment, the first pattern portions 410 and the second pattern portions 420 are alternately arranged one by one. However, n pieces (n is an integer of 2 or more) may be alternately arranged.

  In the above embodiment, the example in which the second pattern unit 420 is drawn after the first pattern unit 410 is drawn has been described. However, the first pattern unit 410 may be drawn after the second pattern unit 420 is drawn.

[Second Embodiment]
In the first embodiment, the example in which the rectangular first pattern portion 410 and the second pattern portion 420 are drawn by combining the # 3 right isosceles triangle and the # 5 right isosceles triangle has been described. The combination of figures for creating the rectangular pattern is not limited to this. For example, seven types of combinations shown in FIGS. 11A to 11G are conceivable for drawing a rectangular pattern.

  In the present embodiment, as shown in FIG. 12, a first pattern unit 510 (drawn by sorting OFF a rectangular pattern R1 to R7 having a different combination of figures and a reference rectangular pattern R8 using only the # 1 rectangle. The evaluation pattern portion) and the second pattern portion 520 (reference pattern portion) drawn by sorting ON are alternately arranged and connected to form a linear evaluation pattern 500. The rectangular patterns R1 to R7 correspond to FIGS. 11A to 11G, respectively. Each figure of the 1st pattern part 510 and the 2nd pattern part 520 is attached with a code of S1, S2, S3.

  Such an evaluation pattern 500 is drawn for every settling time to be evaluated. A resist pattern is formed by developing a substrate on which a plurality of evaluation patterns 500 having different settling times are drawn. Subsequently, the lower light shielding film is etched using the resist pattern as a mask to form a light shielding film pattern. The roughness of the light shielding film pattern is measured, and the shortest settling time among the settling times of the light shielding film pattern in which the roughness is equal to or less than a predetermined value can be calculated as the optimum settling time.

  In this embodiment, since a plurality of rectangular patterns R1 to R7 having different graphic combinations are included in one evaluation pattern, there is no need to draw an evaluation pattern for each graphic combination, and the optimum settling of the DAC unit 132 is achieved. Time can be obtained efficiently.

  Further, it is possible to detect which figure combination causes roughness deterioration from the edge position of the light shielding film pattern.

[Third Embodiment]
In the first and second embodiments, the method for obtaining the optimum settling time of the DAC unit 132 connected to the first shaping deflector 220 has been described. In the present embodiment, the second shaping deflector that controls the shot size is used. A method for obtaining the optimum settling time of the DAC unit 134 connected to the 222 will be described.

  In the present embodiment, as shown in FIG. 13A, the first pattern portion 610 (evaluation target pattern portion) in which the figure type is a rectangle of # 1 and two rectangles having different sizes are combined and 2 of the same size are used. A line-shaped evaluation pattern 600A in which second pattern portions 620 (reference pattern portions) obtained by combining two rectangles are alternately arranged and connected is drawn. In the drawing of the plurality of first pattern portions 610, the shot size is changed for each shot. In the figure, the symbols S1, S2, S3,...

  For example, a rectangle having a height of 120 nm is shot, and then a rectangle having a height of 130 nm is shot to draw the first first pattern portion 610. A plurality of first pattern portions 610 are drawn at predetermined intervals. At this time, the settling time to be evaluated is set in the DAC unit 134.

  Next, two rectangles with a height of 125 nm are shot between the first pattern portions 610 (and on the right side of the first pattern portion 610 at the right end in the drawing) to draw the second pattern portion 620. As a result, a line-shaped evaluation pattern 600A is drawn in which the first pattern portion 610 combining two rectangles having different sizes and the second pattern portion 620 combining two rectangles of the same size are alternately arranged and connected. The

  Further, as shown in FIG. 13B, the graphic type is the rectangle of # 1, the third pattern portion 630 (evaluation target pattern portion) including two rectangles having different sizes, and the fourth pattern composed of one rectangle. A line-shaped evaluation pattern 600B in which the portions 640 (reference pattern portions) are alternately arranged and connected is drawn. In the figure, the symbols S1, S2, S3,... One of the two rectangles of the third pattern portion 630 is the same size as the rectangle of the fourth pattern portion 640. The other of the two rectangles of the third pattern portion 630 is within one rectangular area.

  For example, a rectangle (S1) with a height of 100 nm is shot, and then a rectangle (S2) with a height of 250 nm is shot so as to overlap the rectangle (S1), thereby drawing the first third pattern portion 630. . A plurality of third pattern portions 630 are drawn at predetermined intervals. At this time, the settling time to be evaluated is set in the DAC unit 134.

  Next, a rectangle having a height of 250 nm is shot between the third pattern portions 630 (and on the right side of the third pattern portion 630 at the right end in the drawing) to draw the fourth pattern portion 640. Thereby, a line-shaped evaluation pattern 600B in which the third pattern part 630 including two rectangles having different sizes and the fourth pattern part 640 formed of one rectangle are alternately arranged and connected is drawn.

  In the evaluation pattern 600A, the difference between the sizes of the two rectangles in the first pattern portion 610 is 10 nm, and the change in the deflection amount of the second shaping deflector 222 is small. On the other hand, in the evaluation pattern 600B, the difference between the sizes of the two rectangles in the third pattern portion 630 is 150 nm, and the change in the deflection amount of the second shaping deflector 222 is large.

  Such evaluation patterns 600A and 600B are drawn for every settling time to be evaluated. A substrate on which a plurality of evaluation patterns 600A and 600B having different settling times is drawn is developed to form a resist pattern. Subsequently, the lower light shielding film is etched using the resist pattern as a mask to form a light shielding film pattern. The roughness of the light shielding film pattern is measured, and the shortest settling time among the settling times of the light shielding film pattern in which the roughness is equal to or less than a predetermined value can be calculated as the optimum settling time.

  In the present embodiment, since a pattern part including figures of different sizes in one evaluation pattern and a pattern part (or a pattern part made up of one rectangle) combining figures of the same size are included, the figure size There is no need to draw an evaluation pattern every time, and the optimum settling time of the DAC unit 134 can be obtained efficiently.

  The number of rectangles constituting the first pattern portion 610 and the second pattern portion 620 is not two, but may be three or more. The plurality of rectangles constituting the first pattern portion 610 have different sizes, and the plurality of rectangles constituting the second pattern portion 620 have the same size.

[Fourth Embodiment]
In the present embodiment, a method for obtaining the optimum settling time of the DAC unit 138 connected to the sub-sub deflector 234 that controls the shot position in the TF 40 (see FIG. 6) will be described.

  In the present embodiment, as shown in FIG. 14A, the graphic type is a rectangle of # 1, the same size rectangles are combined in a matrix, and the settling time to be evaluated by the DAC unit 138 is set and drawn. A line-shaped evaluation pattern 700A in which a pattern portion 710 (evaluation target pattern portion) and a second pattern portion 720 (reference pattern portion) drawn with a sufficiently long settling time set in the DAC unit 138 are arranged and connected alternately. Form. In the figure, in the first pattern portion 710 and the second pattern portion 720, symbols of S1, S2, S3,.

  In the first pattern portion 710 and the second pattern portion 720, after the first rectangle (S1) is shot, the second rectangle (S2) is shot with an interval in the y direction (upward in the figure). The third and fourth rectangles (S3, S4) are shot between the first rectangle and the second rectangle. Such four rectangular shots arranged in the y direction are performed while shifting the position in the x direction. The sub-sub deflector 234 changes the shot position of each rectangle.

  As shown in FIG. 14B, an evaluation pattern 700B having a larger size per rectangle than the evaluation pattern 700A may be further drawn. In the evaluation pattern 700B, the third pattern portion 730 drawn by setting the settling time to be evaluated in the DAC unit 138 and the fourth pattern portion 740 drawn by setting a sufficiently long settling time in the DAC unit 138 are alternately arranged. -It is a connected line pattern.

  For example, in the first pattern unit 710 and the second pattern unit 720, the height (length in the y direction) of one rectangle is 100 nm. On the other hand, in the third pattern unit 730 and the second pattern unit 740, the height (length in the y direction) of one rectangle is 150 nm. The settling time set in the DAC unit 138 when drawing the second pattern portion 720 and the fourth pattern portion 740 is, for example, 400 nsec.

  Such evaluation patterns 700A and 700B are drawn at every settling time to be evaluated. A substrate on which a plurality of evaluation patterns 700A and 700B having different settling times is drawn is developed to form a resist pattern. Subsequently, the lower light shielding film is etched using the resist pattern as a mask to form a light shielding film pattern. The roughness of the light shielding film pattern is measured, and the shortest settling time among the settling times of the light shielding film pattern in which the roughness is equal to or less than a predetermined value can be calculated as the optimum settling time.

  By using the same method, the optimal settling time of the DAC unit 137 connected to the main deflector 232 and the optimal settling time of the DAC unit 136 connected to the sub deflector 230 can be calculated.

  In the first to fourth embodiments described above, the example of measuring the roughness of the light shielding film pattern has been described. However, the roughness of the resist pattern may be measured.

  The roughness of the pattern may be LWR (Line Width Roughness) instead of LER.

  In the above embodiment, an electron beam is used. However, the present invention is not limited to this, and the present invention can also be applied to cases where other charged particle beams such as an ion beam are used.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 10 Drawing area | region 20 Stripe area | region 30 Subfield 32 Opening 34 Variable shaping | molding opening 36 Shot beam 40 Under subfield 100 Electron beam drawing apparatus 101 Sample 102 Electron barrel 103 Drawing chamber 105 XY stage 110 Control computer 112 Shot data generation part 114 Memory 116 Settling time setting unit 120 Deflection control circuit 122 Deflection amount calculation unit 124 Deflection signal generation unit 126 Memory 130, 132, 134, 136, 137, 138 DAC unit 140 Storage device 150 Drawing unit 160 Control unit 200 Electron beam 201 Electron gun 202 Illumination Lens 203 First shaping aperture 204 Projection lens 206 Second shaping aperture 207 Objective lens 212 Blanker 214 Blanking aperture 220 First shaping bias Directing device 222 Second shaping deflector 230 Sub deflector 232 Main deflector 234 Sub sub deflector

Claims (5)

An evaluation method of a charged particle beam drawing apparatus for drawing a pattern on a substrate by deflecting a charged particle beam using a deflector controlled by a DAC amplifier,
A plurality of evaluation patterns are drawn by performing a step of drawing a line-like evaluation pattern in which a plurality of evaluation target pattern portions and reference pattern portions are alternately arranged for each settling time while varying the settling time of the DAC amplifier. And
Measuring the roughness of the plurality of evaluation patterns;
An evaluation method for a charged particle beam drawing apparatus, wherein a settling time of the DAC amplifier is determined based on measured roughness. The DAC amplifier is connected to a first shaping deflector that controls the shot shape,
The evaluation target pattern portion and the reference pattern portion are patterns combining a plurality of types of figures,
When drawing the evaluation target pattern portion, change the shot shape for each shot,
The charged particle beam drawing apparatus evaluation method according to claim 1, wherein when the reference pattern portion is drawn, the same shot shape is continuously shot.   3. The evaluation method for a charged particle beam drawing apparatus according to claim 2, wherein the evaluation target pattern portion and the reference pattern portion include a plurality of rectangular patterns in which rectangles and / or right triangles are combined in different ways. The DAC amplifier is connected to a second deflector that controls a shot size;
The evaluation target pattern portion is a rectangular pattern in which a plurality of rectangles having different sizes are combined,
When drawing the evaluation target pattern portion, change the shot size for each shot,
The evaluation target pattern portion is a rectangular pattern composed of one rectangle, or a rectangular pattern combining a plurality of rectangles of the same size,
The charged particle beam drawing apparatus evaluation method according to claim 1, wherein when the reference pattern portion is drawn, the same shot size is shot continuously. The DAC amplifier is connected to an objective deflector that controls the irradiation position of the charged particle beam on the substrate,
The evaluation object pattern part and the reference pattern part are a combination of a plurality of rectangles of the same size,
When drawing the evaluation target pattern part, set the settling time of the evaluation target in the DAC amplifier,
The charged particle beam drawing apparatus adjustment method according to claim 1, wherein when drawing the reference pattern portion, a settling time longer than the settling time of the evaluation target is set.

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