JP7095395B2 - Charged particle beam drawing device and charged particle beam drawing method - Google Patents

Description

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

With the increasing integration of LSIs, the circuit line width required for semiconductor devices is becoming smaller year by year. In order to form a desired circuit pattern on a semiconductor device, a high-precision original image pattern (mask, especially those used in steppers and scanners) formed on quartz using a reduced projection exposure device is also called a reticle. ) Is reduced and transferred onto the wafer. The high-precision original image pattern is drawn by an electron beam drawing apparatus, and so-called electron beam lithography technology is used.

With the progress of optical lithography technology and the shortening of wavelengths by EUV, the number of shots of an electron beam required for mask drawing is increasing. On the other hand, in order to secure the line width accuracy required for miniaturization, the resistance of the resist is lowered and the irradiation amount is increased to reduce shot noise and edge roughness of the pattern. As the number of shots and the amount of irradiation increase, the drawing time increases. Therefore, it is considered to shorten the drawing time by increasing the current density.

However, when an attempt is made to irradiate the increased amount of irradiation energy with a higher density electron beam in a short time, the substrate temperature rises, the resist sensitivity changes, and the line width accuracy deteriorates, a phenomenon called resist heating. There is a problem that occurs. Therefore, resist heating correction including irradiation dose modulation for suppressing dimensional fluctuation due to resist heating is performed. For example, for each of the minimum deflection regions of different sizes deflected by the multi-stage deflectors that deflect the electron beam, the transfer from the other minimum deflection regions drawn prior to the minimum deflection region. A representative temperature of the minimum deflection region based on heat is calculated, and the irradiation amount is modulated using the representative temperature (see, for example, Patent Document 1).

The resist heating correction is a process performed in the drawing apparatus, and the user could not confirm the correction data such as how much the irradiation amount was modulated.

Japanese Unexamined Patent Publication No. 2012-69675 Japanese Unexamined Patent Publication No. 2008-233687 Japanese Unexamined Patent Publication No. 2000-156342 Japanese Unexamined Patent Publication No. 2010-219371 Japanese Unexamined Patent Publication No. 2011-221555 Japanese Unexamined Patent Publication No. 2016-58564

The present invention has been made in view of the above-mentioned conventional situation, and an object of the present invention is to provide a charged particle beam drawing apparatus and a charged particle beam drawing method for outputting correction data of resist heating correction.

The charged particle beam drawing device according to one aspect of the present invention has a storage unit for temporarily storing drawing data including a drawing position and an irradiation amount at the drawing position and a coordinate designation file , and a drawing area of a substrate having a plurality of temperature calculation areas. For each temperature calculation area, the substrate temperature of the temperature calculation area based on the heat transfer from the previous temperature calculation area is calculated, and the irradiation amount is modulated based on the substrate temperature. A drawing unit that irradiates a substrate with a charged particle beam using drawing data including a modulated irradiation amount to draw a drawing unit, and a drawing unit that draws coordinates on a layout specified by the coordinate specification file are determined by the drawing unit. The coordinate conversion unit that converts to the drawing position and the drawing information extraction unit that extracts drawing information including the modulation amount of the irradiation amount and the substrate temperature corresponding to the drawing position converted by the coordinate conversion unit are designated. It is provided with a temperature information output unit that outputs the drawing information corresponding to the coordinates.

In the charged particle beam drawing apparatus according to one aspect of the present invention, when the coordinates on the layout specified by the coordinate designation file include a plurality of drawing positions, the drawing information extraction unit corresponds to each of the plurality of drawing positions. Drawing information including the modulation amount of the irradiation amount and the substrate temperature is extracted, and the temperature information output unit outputs an average value of the extracted drawing information values.

In the charged particle beam drawing apparatus according to one aspect of the present invention, the drawing data is shot data, and the charged particle beam is a single beam.

In the charged particle beam drawing apparatus according to one aspect of the present invention, the drawing data is pixel data, and the charged particle beam is a multi-beam.

The charged particle beam drawing method according to one aspect of the present invention includes a step of storing drawing data including a drawing position and an irradiation amount at the drawing position and a coordinate designation file in a storage unit, and a drawing area of a substrate in a plurality of temperature calculation areas. A step of dividing and calculating the substrate temperature of the temperature calculation region based on the heat transfer from the previous temperature calculation region in the drawing order for each temperature calculation region, and modulating the irradiation amount based on the substrate temperature, and modulation. The process of irradiating the substrate with a charged particle beam using the drawing data including the irradiation amount to perform the drawing process, and the coordinates on the layout specified by the coordinate designation file are converted into the drawing position in the drawing process. The step of extracting the drawing information including the modulation amount of the irradiation amount and the substrate temperature corresponding to the converted drawing position, and the step of outputting the drawing information corresponding to the specified coordinates. It is equipped with.

According to the present invention, the correction data of the resist heating correction can be output.

It is a schematic diagram of the drawing apparatus which concerns on embodiment of this invention. It is a conceptual diagram explaining a deflection area. (A) is a diagram showing an example of a coordinate designation file, and (b) is a diagram showing the designated coordinates on the layout. (A) is a diagram showing an example of a coordinate designation file, and (b) is a diagram showing a designated range on the layout. It is a flowchart explaining the drawing method which concerns on this embodiment.

Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to the electron beam, and a beam using charged particles such as an ion beam may be used. Further, as an example of the charged particle beam apparatus, a variable molding type drawing apparatus will be described.

FIG. 1 is a conceptual diagram showing a configuration of a drawing apparatus according to an embodiment. In FIG. 1, the drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing unit 150 includes an electronic lens barrel 102 and a drawing chamber 103. Inside the electronic lens barrel 102, an electron gun 201, an illumination lens 202, a blanking deflector (blanker) 212, a blanking aperture 214, a first molded aperture 203, a projection lens 204, a molded deflector 205, and a second molded aperture 206. , Objective lens 207, main deflector 208, sub-deflector 209, and sub-sub-deflector 216 are arranged.

In the drawing chamber 103, an XY stage 105 that can move at least in the XY direction is arranged. On the XY stage 105, a substrate 101 to be drawn, to which a resist is applied, is arranged. The substrate 101 includes an exposure mask, a silicon wafer, and the like for manufacturing a semiconductor device.

The control unit 160 includes a control computer 110, memories 112, 114, a deflection control circuit 120, a DAC (digital-to-analog converter) amplifier 130, 132, 134, 136, 138 (deflection amplifier), and a storage device 140. ..

DAC amplifiers 130, 132, 134, 136, and 138 are connected to the deflection control circuit 120. The DAC amplifier 130 is connected to the blanking deflector 212. The DAC amplifier 132 is connected to the sub-deflector 209. The DAC amplifier 134 is connected to the main deflector 208. The DAC amplifier 136 is connected to the sub-sub deflector 216. The DAC amplifier 138 is connected to the molding deflector 205.

The control computer 110 includes a shot data generation unit 50, an irradiation amount modulation unit 51, an irradiation time calculation unit 52, a drawing control unit 53, a coordinate conversion unit 54, a drawing information extraction unit 55, and a temperature information output unit 56. Each function of the shot data generation unit 50, the irradiation amount modulation unit 51, the irradiation time calculation unit 52, the drawing control unit 53, the coordinate conversion unit 54, and the drawing information extraction unit 55 may be configured by software or hardware. It may be composed of.

FIG. 2 is a conceptual diagram for explaining a deflection region. In FIG. 2, the drawing region 10 of the substrate 101 is virtually divided into a plurality of stripe regions 20 in a strip shape in the y direction, for example, with the deflectable width of the main deflector 208. Then, the region obtained by dividing the stripe region 20 in the x direction by the deflectable width of the main deflector 208 becomes the deflection region (main deflection region) of the main deflector 208.

This main deflection region is a deflectable size of the sub-deflector 209 and is virtually divided into a plurality of sub-fields (SF) 30 in a mesh shape. Each SF30 has a deflectable size of the sub-secondary deflector 216, and is referred to as “TF” by using a plurality of under-subfields in a mesh shape (here, the abbreviation of Tertiary Deflection Field, which means a third deflection). , Same) Virtually divided into 40.

A shot figure is drawn at each shot position 42 of each TF 40. In this way, each of the deflection regions becomes the main deflection region, SF30, and TF40 in order from the larger one having a different deflection region size by the three-stage deflector that deflects the electron beam 200.

A digital signal for blanking control is output from the deflection control circuit 120 to the DAC amplifier 130. In the DAC amplifier 130, a digital signal is converted into an analog signal, amplified, and then applied to the blanking deflector 212 as a deflection voltage. The electron beam 200 is deflected by this deflection voltage, and blanking control of each shot is performed.

A digital signal for molding deflection is output from the deflection control circuit 120 to the DAC amplifier 138. In the DAC amplifier 138, the digital signal is converted into an analog signal, amplified, and then applied to the deflector 205 as a deflection voltage. This deflection voltage deflects the electron beam 200 to a specific position on the second molded aperture 206 to form an electron beam of the desired size and shape.

A digital signal for main deflection control is output from the deflection control circuit 120 to the DAC amplifier 134. The DAC amplifier 134 converts a digital signal into an analog signal, amplifies it, and then applies it to the main deflector 208 as a deflection voltage. The electron beam 200 is deflected by this deflection voltage, and the beam of each shot is virtually divided into a mesh shape as a reference position A of a predetermined subfield (SF) (for example, the center position of the corresponding SF or the lower left corner position). Etc.). Further, when drawing while the XY stage 105 continuously moves, the deflection voltage includes a deflection voltage for tracking that follows the stage movement.

A digital signal for sub-deflection control is output from the deflection control circuit 120 to the DAC amplifier 132. The DAC amplifier 132 converts a digital signal into an analog signal, amplifies it, and then applies it to the sub-deflector 209 as a deflection voltage. The electron beam 200 is deflected by this deflection voltage, and the beam of each shot is deflected to the reference position B of the TF 40 (for example, the center position of the corresponding TF or the lower left corner position) which is the minimum deflection region.

A digital signal for sub-sub deflection control is output from the deflection control circuit 120 to the DAC amplifier 136. The DAC amplifier 136 converts a digital signal into an analog signal, amplifies it, and then applies it to the sub-sub deflector 216 as a deflection voltage. This deflection voltage deflects the electron beam 200, and the beam of each shot is deflected to each shot position 42 in the TF 40.

In the drawing apparatus 100, the drawing process is advanced for each stripe region 20 by using a plurality of stages of deflectors. Here, as an example, a three-stage deflector such as a main deflector 208, a sub-deflector 209, and a sub-secondary deflector 216 is used. While the XY stage 105 continuously moves, for example, in the −x direction, drawing proceeds in the x direction for the first stripe region 20. Then, after the drawing of the first stripe area 20 is completed, the drawing of the second stripe area 20 is proceeded in the same manner or in the opposite direction. After that, the drawing of the third and subsequent stripe areas 20 is carried out in the same manner.

The main deflector 208 sequentially deflects the electron beam 200 to the reference position A of the SF 30 so as to follow the movement of the XY stage 105. Further, the sub-deflector 209 deflects the electron beam 200 in order from the reference position A of each SF30 to the reference position B of the TF40. Then, the sub-secondary deflector 216 deflects the electron beam 200 from the reference position B of each TF 40 to the shot position 42 of the beam irradiated in the TF 40.

As described above, the main deflector 208, the sub-deflector 209, and the sub-sub-deflector 216 have deflection regions of different sizes. The TF 40 is the minimum deflection region among the deflection regions of the plurality of stages of deflectors.

The storage device 140 is, for example, a magnetic disk device, and stores drawing data for drawing a pattern on the substrate 101. This drawing data is data in which design data (layout data) is converted into a format for the drawing device 100, and is input to the storage device 140 from an external device and stored.

The processing by the shot data generation unit 50, the irradiation amount modulation unit 51, the irradiation time calculation unit 52, the drawing control unit 53, the coordinate conversion unit 54, the drawing information extraction unit 55, and the temperature information output unit 56 is according to the flowchart shown in FIG. I will explain.

As described above, the drawing data is stored in the storage device 140. Further, the coordinate specification file created by the user, which will be described later, is also stored (step S1). The shot data generation unit 50 performs a plurality of stages of data conversion processing on the drawing data stored in the storage device 140, and a shot figure having a size capable of illuminating each figure pattern to be drawn with one shot. And generate shot data in a format peculiar to the drawing device (step S2). The shot data includes, for example, a graphic code indicating a graphic type of each shot graphic, a graphic size, a shot position, an irradiation amount, and the like, which are set for each shot. The irradiation amount may be expressed by the irradiation time obtained by dividing this by the current density. The generated shot data is temporarily stored in the memory 112. The shot data generation unit 50 does not necessarily have to be provided in the control computer 110, and may be stored in the memory 112 after the shot data is generated externally.

The shot data generation unit 50 makes various corrections when generating shot data. For example, a process of correcting an error in the shot position due to bending of the substrate 101 to be drawn is performed.

Further, the shot data generation unit 50 calculates the irradiation amount of the electron beam at each position of the drawing area 10 in consideration of factors that cause dimensional fluctuation of the pattern such as the proximity effect, the fogging effect, and the loading effect, and the calculated irradiation amount. Is divided by the current density to obtain the irradiation time.

The irradiation amount of the electron beam at each position of the drawing area 10 can be calculated by using a known method. For example, the method described in JP-A-2007-150243 can be used. In this method, first, the fogging effect correction irradiation amount in the first mesh region in which the drawing region is divided into a mesh shape by the first dimension is calculated. In addition, the loading effect correction dimension value in the second mesh region obtained by dividing the drawing region into a mesh shape by the second dimension is calculated. Then, based on this correction dimension value, a reference irradiation amount map and a proximity effect correction coefficient map of the electron beam in the second mesh region are created. Next, using these maps, the proximity effect correction irradiation amount in the third mesh region in which the drawing area is divided into meshes by the first dimension and the third dimension smaller than the second dimension is calculated. Then, the electron beam irradiation amount at each position in the drawing area is calculated based on the fogging effect correction irradiation amount and the proximity effect correction irradiation amount.

The irradiation amount modulation unit 51 virtually divides the drawing area 10 into small mesh-like areas (temperature calculation areas) of a predetermined size (step S3). For each divided small area, the amount of temperature rise caused by heat transfer from another small area drawn before the small area is calculated. The small area is, for example, TF40.

The irradiation amount modulation unit 51 cumulatively adds up the amount of temperature increase generated by heat transfer from a plurality of other small areas drawn before the small area for each small area, and the substrate temperature of the small area. Is calculated (step S4). Then, the irradiation amount modulation unit 51 modulates the irradiation amount for each small region by using the calculated substrate temperature so that the dimensional fluctuation of the pattern due to resist heating is suppressed (step S5). The irradiation amount before modulation is an irradiation amount for correcting dimensional fluctuations due to the above-mentioned proximity effect and the like.

The irradiation time calculation unit 52 calculates the irradiation time after resist heating correction by dividing the irradiation amount after modulation by the current density.

In the drawing step (step S6), the drawing process is performed using the shot data including the irradiation time obtained by the irradiation time calculation unit 52 from the irradiation amount after the modulation. The drawing control unit 53 transfers the shot data to the deflection control circuit 120. The deflection control circuit 120 outputs deflection data having a desired irradiation time to the DAC amplifier 130 for the blanking deflector 212.

The deflection control circuit 120 outputs the deflection data to the DAC amplifier 134 for the main deflector 208 so that the beam follows the movement of the XY stage 105. The deflection control circuit 120 outputs the deflection data to the DAC amplifier 132 for the secondary deflector 209 that deflects the beam to a relative position in the SF30. The deflection control circuit 120 outputs the deflection data to the DAC amplifier 136 for the sub-sub deflector 216 that deflects the beam to a relative position in the TF 40.

Further, the deflection control circuit 120 outputs the deflection data to the DAC amplifier 138 for the molding deflector 205 so that the beam has a desired shape.

When the electron beam 200 emitted from the electron gun 201 (emission unit) passes through the blanking deflector 212, the electron beam 200 passes through the blanking aperture 214 by the blanking deflector 212, for example, when the beam is ON. When the beam is off, 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 from the beam OFF state to the beam ON and then to the beam OFF becomes one shot of the electron beam.

The electron beam 200 of each shot generated by passing through the blanking deflector 212 and the blanking aperture 214 illuminates the entire first molded aperture 203 having a rectangular hole by the illumination lens 202. Here, the electron beam 200 is first formed into a rectangular shape.

The electron beam 200 of the first aperture image that has passed through the first molded aperture 203 is projected onto the second molded aperture 206 by the projection lens 204. By the forming deflector 205, the first aperture image on the second forming aperture 206 is deflected and controlled, and the beam shape and dimensions can be changed (variable forming is performed). Such variable molding is performed for each shot, and can be molded into different beam shapes and dimensions for each shot.

The electron beam 200 of the second aperture image that has passed through the second molded aperture 206 is focused by the objective lens 207, deflected by the main deflector 208, the sub-deflector 209, and the sub-sub-deflector 216, and moves continuously. The desired position of the substrate 101 arranged on the XY stage 105 is irradiated. As described above, each deflector deflects a plurality of shots of the electron beam 200 onto the substrate 101 which is a substrate in order.

The drawing apparatus 100 according to the present embodiment creates and outputs drawing information such as how much the irradiation time is corrected by the resist heating correction in units of shot data in parallel with the drawing process. However, if drawing information is created for all the shot data in the drawing area 10, the amount of data becomes enormous. Therefore, in the present embodiment, drawing information corresponding to the shot data of the specified coordinates is created and output.

As described above, the storage device 140 stores the coordinate designation file created by the user together with the drawing data (step S1). For example, the user creates a coordinate specification file in the format shown in FIG. 3A. FIG. 3B shows the coordinates (positions) on the layout specified in the coordinate specification file of FIG. 3A.

The specified coordinates are, for example, a plurality of coordinates that serve as line width measurement points of the drawing pattern.

As described above, in generating the shot data, a process of correcting an error in the shot position due to bending of the substrate 101 or the like is performed, and the coordinates of the actual shot are shifted. The corresponding shot data cannot be searched with the coordinates specified in the coordinate specification file. Therefore, the coordinate conversion unit 54 performs coordinate conversion processing on the coordinates designated in the coordinate designation file, and calculates the shot position corresponding to the designated coordinates (step S10).

The drawing information extraction unit 55 determines the corrected irradiation time and irradiation time calculated in response to the modulation amount of the irradiation amount based on the modulated irradiation amount, for example, with respect to the shot data corresponding to the position calculated by the coordinate conversion unit 54. Drawing information such as the correction ratio and the temperature (board temperature) of the substrate 101 at the shot position after irradiation is extracted (step S11). The correction rate of the irradiation time can be obtained from the irradiation time before the correction based on the shot data and the irradiation time after the correction based on the modulated irradiation amount. The substrate temperature is represented, for example, by the representative temperature of a small region including the specified position. The substrate temperature can be expressed by the amount of change (temperature rise) of the substrate temperature.

In parallel with the generation of shot data and the calculation of the irradiation time, the drawing information extraction unit 55 extracts the drawing information corresponding to the converted position (step S11).

The temperature information output unit 56 stores the drawing information extracted by the drawing information extraction unit 55 corresponding to the coordinates specified in the coordinate designation file in the memory 114 (step S12). The temperature information output unit 56 can output drawing information to the outside of the drawing device 100 (step S13). The shot data in the memory 112 is erased after being transferred to the deflection control circuit 120 (after further creating drawing information if it corresponds to the coordinates specified in the coordinate specification file).

As described above, according to the present embodiment, the correction amount of the irradiation time based on the modulation amount of the irradiation amount by the resist heating correction at the specified coordinates and the increase amount of the substrate temperature can be visualized immediately after drawing. Can be obtained. The effect of the resist heating correction can be verified based on the line width of the drawing pattern and the correction amount of the irradiation time.

In the coordinate specification file, a range as shown in FIGS. 4A and 4B may be specified instead of the coordinates of one point. The drawing information extraction unit 55 extracts, for example, the irradiation time after correction, the correction rate of the irradiation time, the amount of increase in the substrate temperature after irradiation, and the like for all the shot data included in this range, and stores them in the memory 114. ..

Further, the temperature information output unit 56 may obtain an average value, a maximum value, a minimum value, a standard deviation, and the like of a plurality of extracted values for each item.

In the case of multiple drawing, correction information is extracted from the shot data corresponding to each path.

In the above embodiment, an example of a drawing apparatus using a single beam has been described, but the present invention can also be applied to a drawing apparatus using a multi-beam. In the multi-beam drawing device, the irradiation time is set for each irradiation area (pixel) of each beam. The resist heating correction corrects the irradiation time of each pixel. Similar to the case of the single beam drawing device, the coordinate conversion unit 54 performs coordinate conversion processing for multi-beam on the coordinates specified in the coordinate specification file, and calculates the shot position corresponding to the specified coordinates. The drawing information extraction unit 55 extracts drawing information such as the corrected irradiation time, the correction ratio of the irradiation time, and the substrate temperature for the pixel shot data (pixel data) corresponding to the position calculated by the coordinate conversion unit 54. ..

It should be noted that the present invention is not limited to the above embodiment as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by an appropriate combination of the plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments. In addition, components across different embodiments may be combined as appropriate.

50 Shot data generation unit 51 Irradiation amount modulation unit 52 Irradiation time calculation unit 53 Drawing control unit 54 Coordinate conversion unit 55 Drawing information extraction unit 56 Temperature information output unit 100 Drawing device 110 Control computer 150 Drawing unit 160 Control unit

Claims (5)

A storage unit that temporarily stores the drawing position and the drawing data including the irradiation amount at the drawing position and the coordinate specification file .
The drawing area of the substrate is divided into a plurality of temperature calculation areas, and the substrate temperature of the temperature calculation area based on the heat transfer from the previous temperature calculation area in the drawing order is calculated for each temperature calculation area, and based on the substrate temperature. And the irradiation amount modulator that modulates the irradiation amount,
A drawing unit that irradiates a substrate with a charged particle beam using drawing data including a modulated irradiation amount and draws.
A coordinate conversion unit that converts the coordinates on the layout specified by the coordinate specification file to the drawing position by the drawing unit, and
A drawing information extraction unit that extracts drawing information including the modulation amount of the irradiation amount and the substrate temperature corresponding to the drawing position converted by the coordinate conversion unit, respectively.
A temperature information output unit that outputs the drawing information corresponding to the specified coordinates, and
A charged particle beam lithography system. When the coordinates on the layout specified by the coordinate designation file include a plurality of drawing positions, the drawing information extraction unit draws including the modulation amount of the irradiation amount corresponding to the plurality of drawing positions and the substrate temperature. Extract information,
The charged particle beam drawing device according to claim 1, wherein the temperature information output unit outputs an average value of the values of the extracted drawing information. The charged particle beam drawing apparatus according to claim 1 or 2, wherein the drawing data is shot data and the charged particle beam is a single beam. The charged particle beam drawing apparatus according to claim 1 or 2, wherein the drawing data is pixel data and the charged particle beam is a multi-beam. A step of storing the drawing data including the drawing position and the irradiation amount at the drawing position and the coordinate designation file in the storage unit, and
The drawing area of the substrate is divided into a plurality of temperature calculation areas, and the substrate temperature of the temperature calculation area based on the heat transfer from the previous temperature calculation area in the drawing order is calculated for each temperature calculation area, and based on the substrate temperature. And the step of modulating the irradiation amount
A process of irradiating a substrate with a charged particle beam using drawing data including a modulated irradiation amount to perform drawing processing, and
The step of converting the coordinates on the layout specified by the coordinate specification file into the drawing position in the drawing process.
A step of extracting drawing information including a modulation amount of an irradiation amount and a substrate temperature corresponding to each of the converted drawing positions, and a step of extracting the drawing information.
The process of outputting the drawing information corresponding to the specified coordinates, and
Charged particle beam drawing method.

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