KR101873461B1 - Charged particle beam writing apparatus and charged particle beam writing method - Google Patents

Abstract

A charged particle beam drawing apparatus according to an embodiment includes a drawing data storage unit for storing drawing data corresponding to pattern attribute information, a shot division unit for dividing drawing data into shot data associated with pattern attribute information, An index storage unit for storing an index for determining a correction compartment area to be merged by calculation in approximate calculation of a transfer column; a drawing schedule creating unit for creating a drawing schedule based on the shot data; An approximate calculation method determination unit that determines an approximate calculation method of a transfer column from another shot that is drawn before the shot to be drawn by the shot data of the drawing object, and an approximate calculation method determination unit that draws the shot before the shot to be drawn by the shot data A thermal diffusion calculation unit for calculating a temperature rise amount due to transfer heat from another shot; A shot temperature calculating section for obtaining a representative temperature of a shot to be drawn by the shot, a shot amount modulating section for modulating an shot amount of the shot to be drawn by the shot data based on the representative temperature, And a display unit.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a charged particle beam drawing apparatus and a charged particle beam drawing method,

The present invention relates to a charged particle beam drawing apparatus and a charged particle beam drawing method, and more particularly, to a charged particle beam drawing apparatus and a charged particle beam drawing method for performing resist heating correction.

BACKGROUND ART [0002] Lithography technology, which is in charge of advancing miniaturization of semiconductor devices, is a very important process for generating patterns uniquely among semiconductor manufacturing processes. In recent years, the circuit line width required for a semiconductor device has become finer every year with the high integration of LSIs. In order to form a desired circuit pattern on these semiconductor devices, a high-precision original pattern (also referred to as a reticle or mask) is required. Here, the EB (electron beam) drawing technique has inherently excellent resolution and is used for producing a high-precision original pattern.

11 is a conceptual diagram for explaining the operation of the conventional variable-shaped electron beam drawing apparatus. The variable-shape electron beam drawing apparatus is an example of a variable-shaped charged particle beam drawing apparatus. The deformable electron beam drawing apparatus operates as follows. In the first aperture 410, a rectangular opening 411 for forming the electron beam 330 is formed. The second aperture 420 is formed with a variable molding opening 421 for molding the electron beam 330 passing through the opening 411 of the first aperture 410 into a desired rectangular shape. The electron beam 330 irradiated from the charged particle source 430 and passing through the aperture 411 of the first aperture 410 is deflected by the deflector and part of the variable shaping aperture 421 of the second aperture 420 And is irradiated onto a specimen 340 mounted on a stage continuously moving in a predetermined direction (for example, in the X direction). That is, a rectangular shape capable of passing through both the opening 411 of the first aperture 410 and the variable forming opening 421 of the second aperture 420 is mounted on the stage continuously moving in the x direction Is drawn in the drawing area of the formed sample (340). A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable molding opening 421 of the second aperture 420 is referred to as a variable molding method (VSB method).

As the progress of the optical lithography technique or the shortening of the wavelength according to extreme ultra violet (EUV), the number of electron beam shots necessary for mask drawing has been accelerating. On the other hand, in order to secure the line width accuracy required for miniaturization, the resist is reduced in sensitivity and the amount of irradiation is increased to reduce shot noise or edge roughness of the pattern. As described above, since the number of shots and the irradiation amount continuously increase continuously, the drawing time also increases without limit. Therefore, it has been studied to shorten the drawing time by increasing the current density.

However, if an attempt is made to irradiate an increased amount of irradiation energy with a higher density electron beam in a short time, there is a problem that a phenomenon referred to as resist heating, in which the substrate temperature increases, the resist sensitivity changes, and the line width accuracy deteriorates.

Japanese Laid-Open Patent Application No. 2013-243285 discloses a technique in which the average calculation time of TF (under-subfield) and the average drawing time of TF before the correction calculation speed do not fall behind the drawing speed while suppressing the dimensional fluctuation of the pattern by resist heating A calculation time for calculating the temperature rise amount of all the TFs to be rendered is calculated by using the average calculation time for calculating the temperature rise amount generated by the transfer heat from one of the other plurality of TFs to be drawn and the degree of parallelism of the calculator A number arithmetic unit for calculating the number of different TFs to be drawn before the TF, which is used when calculating the temperature rise amount for not exceeding the drawing time of all the TFs; A representative temperature calculating unit for calculating a representative temperature of TF, and a representative temperature calculating unit for calculating a representative temperature of TF by inputting a dose to be irradiated to TF, And a dose modulation section for modulating the irradiation amount irradiated to the TF.

The present invention provides a charged particle beam drawing apparatus and a charged particle beam drawing method for suppressing a dimensional change of a pattern by resist heating while optimizing a calculation amount.

A charged particle beam drawing apparatus according to an embodiment includes a drawing data storage unit for storing drawing data corresponding to pattern attribute information, a shot division unit for dividing drawing data into shot data associated with pattern attribute information, An index storage unit for storing an index for determining a correction compartment area to be merged by calculation in approximate calculation of a transfer column; a drawing schedule creating unit for creating a drawing schedule based on the shot data; An approximate calculation method determination unit that determines an approximate calculation method of a transfer column from another shot that is drawn before the shot to be drawn by the shot data of the drawing object, and an approximate calculation method determination unit that draws the shot before the shot to be drawn by the shot data A thermal diffusion calculation unit for calculating a temperature rise amount due to transfer heat from another shot; A shot temperature calculating section for obtaining a representative temperature of a shot to be drawn by the shot, a shot amount modulating section for modulating an shot amount of the shot to be drawn by the shot data based on the representative temperature, And a display unit.

The charged particle beam drawing method according to the embodiment divides drawing data corresponding to pattern attribute information into shot data corresponding to pattern attribute information, creates a drawing schedule based on the shot data, and corresponds to the drawing schedule and pattern attribute information Determining an approximate calculation method of a transfer column from another shot drawn before the shot to be drawn by the shot data of the drawing object based on an index that determines a correction compartment area to be merge calculated at the time of approximate calculation of the transfer column, Calculating a temperature rise amount due to transferring heat from another shot drawn before the shot to be drawn by the shot data based on the shot data, calculating a representative temperature of the shot to be drawn by the shot data based on the temperature rise amount, Modulates the irradiation amount of the shot to be drawn based on the shot data, and based on the modulated irradiation amount and the imaging schedule W Painting is performed.

1 is a conceptual diagram showing a configuration of a drawing apparatus according to the first embodiment.
Fig. 2 is a conceptual diagram for explaining each region in the first embodiment. Fig.
3 is a flow chart showing the main steps of the drawing method in the first embodiment.
FIG. 4 is a conceptual diagram showing a TF imaging sequence in the SF in the first embodiment. FIG.
5 is a conceptual diagram showing an example of a drawing procedure of SFs in a stripe area in the first embodiment.
6 is a conceptual diagram showing an example of a drawing procedure of a TF in the SF in the first embodiment.
Fig. 7 is a conceptual diagram of the merging of deflection areas when AI = 1 in the first embodiment. Fig.
8 is a conceptual diagram of the merging of deflection areas in the case of AI = 2 in the first embodiment.
Fig. 9 is a flowchart showing the main steps of the drawing method in the third embodiment. Fig.
10 is a conceptual diagram of the merging of deflection areas in the third embodiment.
11 is a conceptual diagram for explaining the operation of the conventional variable-shaped electron beam drawing apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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

(First Embodiment)

The charged particle beam drawing apparatus of the present embodiment includes a drawing data storage unit for storing drawing data corresponding to pattern attribute information, a shot division unit for dividing drawing data into shot data associated with pattern attribute information, An index storage unit for storing an index for determining a correction compartment area to be merged by calculation at the time of approximate calculation of a transfer column, a drawing schedule creating unit for creating a drawing schedule based on the shot data, An approximate calculation method determining unit that determines an approximate calculation method of a transfer column from another shot that is drawn before the shot to be drawn by the shot data to be rendered, A thermal diffusion calculation unit for calculating a temperature rise amount due to the transfer heat from the other shot, A shot temperature calculation unit for obtaining a representative temperature of the shot to be drawn by the data, an irradiation amount modulation unit for modulating the irradiation amount of the shot to be drawn by the shot data based on the representative temperature, And a display unit.

1 is a conceptual diagram showing a configuration of a drawing apparatus according to the present embodiment. The drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a charged particle beam drawing apparatus. Particularly, it is an example of a drawing apparatus of a variable mold type (VSB type). The drawing unit 150 includes an electron lens barrel 102 and a drawing chamber 103. An electron gun 201, an illumination lens 202, a blanking deflector (blanker) 212, a blanking aperture 214, a first shaping aperture 203, a projection lens 204, A deflector 205, a second shaping aperture 206, an objective lens 207, a casting scent 208, a shingles 209 and a second deflector 216 are disposed. In the drawing chamber 103, an XY stage 105 movable at least in the XY direction is disposed. On the XY stage 105, a sample 101 (substrate) to which a resist is applied and which is to be imaged is disposed. The sample 101 includes a mask for exposure or a silicon wafer for manufacturing a semiconductor device. The mask includes mask blanks.

The control unit 160 includes a control calculator unit 110, a deflection control circuit 120, DAC (Digital-to-Analog Converter) amplifier units 130, 132, 134 and 136 (deflection amplifiers), a drawing data storage unit 140, And an indicator storage unit 142. The rendering data storage unit 140 and the indicator storage unit 142 are constituted by a storage device such as a magnetic disk device. The control calculator unit 110, the deflection control circuit 120, the rendering data storage unit 140, and the indicator storage unit 142 are connected to each other via a bus not shown. The DAC amplifier units 130, 132, 134, and 136 are connected to the deflection control circuit 120. The DAC amplifier unit 130 is connected to the blanking deflector 212. The DAC amplifier unit 132 is connected to the shunt fragrance 209. The DAC amplifier unit 134 is connected to the casting scent 208. The DAC amplifier unit 136 is connected to the subsidiary deflector 216.

The control calculator unit 110 includes a shot division unit 50, a first correction division shot allocation unit 52, a second correction division shot allocation unit 54, a painting schedule creation unit 56, The total charge amount calculation section 60 in the first correction section, the total charge amount calculation section 62 in the second correction section, the thermal diffusion calculation section 64, the shot temperature calculation section 66, The irradiation amount modulating unit 68, the irradiation amount map creating unit 70, the first correction-zone representative-figure setting unit 72, the second correction-zone representative-figure setting unit 74, the approximate calculation method determining unit 76, An irradiation time calculation unit 78, a temperature rise amount determination unit 80, a rendering processing unit 90, and a memory 92 are arranged. The shot division section 50, the first correction section shot allocation section 52, the second correction section shot allocation section 54, the painting schedule creation section 56, the correction section imaging order setting section 58, The total charge amount calculation section 60 in the first correction section, the total charge amount calculation section 62 in the second correction section, the thermal diffusion calculation section 64, the shot temperature calculation section 66, the irradiation amount modulation section 68, A representative figure setting section 72 in the first correction section, a representative figure setting section 74 in the second correction section, an approximate calculation method determining section 76, an irradiation time calculating section 78, Each function such as the amount-of-rise determining unit 80, the rendering processor 90, and the memory 92 may be configured by software such as a program. Alternatively, it may be constituted by hardware such as an electronic circuit. Or a combination thereof. The necessary input data or calculated results in the control calculator unit 110 are stored in the memory 92 each time. The shot division section 50, the first correction section shot allocation section 52, the second correction section shot allocation section 54, the painting schedule creation section 56, the correction section imaging order setting section 58, The total charge amount calculation section 60 in the first correction section, the total charge amount calculation section 62 in the second correction section, the thermal diffusion calculation section 64, the shot temperature calculation section 66, the irradiation amount modulation section 68, A representative figure setting section 72 in the first correction section, a representative figure setting section 74 in the second correction section, an approximate calculation method determining section 76, an irradiation time calculating section 78, When at least one of the increase amount determining unit 80 and the rendering processor 90 is composed of software, a calculator such as a central processing unit (CPU) or a graphics processing unit (GPU) is disposed. Particularly, a plurality of CPUs or a plurality of GPU-like calculators are arranged for functions having a large amount of computation such as the thermal diffusion calculation section 64 and the representative temperature calculation section 66.

The drawing data storage section 140 stores drawing data associated with pattern attribute information.

The index storage unit 142 stores an index for determining a deflection area to be merged by calculation in the approximate calculation of the transfer column corresponding to the pattern attribute information. Here, the deflection area is an example of the correction division area.

Here, Fig. 1 shows the necessary configuration for explaining the present embodiment. It is also possible to provide other structures that are normally required in the drawing apparatus 100. [

Fig. 2 is a conceptual diagram for explaining each area in this embodiment. 2, the drawing region 10 of the sample 101 is virtually divided into a plurality of stripe regions 20 in a rectangular shape toward the y direction at a deflectable width of the speckle 208, for example. In addition, each stripe region 20 is a deflectable size of the shingles 209 and virtually divided into a plurality of subfields (SF) 30 in a mesh shape. Each SF 30 is a deflectable size of the deflector 216 and has a plurality of under-subfields (USF), referred to herein as "TF", which is abbreviated as Tertiary Firld, which means a third deflection area (Hereinafter the same) 40 as shown in Fig. Then, a shot figure is drawn at each shot position 42 of each TF 40. The number of TF divisions in each SF is preferably a number of times that the drawing operation is not controlled by the thermal diffusion calculation of TF. For example, 10 or less is preferable. More suitably, it is preferably 5 or less.

The deflection control circuit 120 outputs a digital signal for blanking control to the DAC amplifier unit 130. [ Then, the DAC amplifier unit 130 converts the digital signal into an analog signal, amplifies it, and then applies it to the blanking deflector 212 as a deflection voltage. With this deflection voltage, the electron beam 200 is deflected to form a beam of each shot.

The deflection control circuit 120 outputs a digital signal for main deflection control to the DAC amplifier unit 134. [ Then, the DAC amplifier unit 134 converts the digital signal into an analog signal, amplifies it, and then applies it to the scent 208 as a deflection voltage. With this deflection voltage, the electron beam 200 is deflected, and the beam of each shot is deflected to the reference position of a predetermined subfield SF which is virtually divided into a mesh shape.

The deflection control circuit 120 outputs a digital signal for sub-deflection control to the DAC amplifier unit 132. [ Then, the DAC amplifier unit 132 converts the digital signal into an analog signal, amplifies it, and then applies it to the fragrance 209 as a deflection voltage. The electron beam 200 is deflected by this deflection voltage so that an under sub-field TF in which the beam of each shot is a minimum deflection area virtually divided into a mesh shape in a predetermined sub-field SF virtually divided into mesh- As shown in FIG.

The deflection control circuit 120 outputs a digital signal for controlling the deflection of the secondary to the DAC amplifier unit 136. [ Then, the DAC amplifier unit 136 converts the digital signal into an analog signal, amplifies it, and then applies it to the deflector 216 as a deflection voltage. The electron beam 200 is deflected by this deflection voltage so that an under sub-field TF in which the beam of each shot is a minimum deflection area virtually divided into a mesh shape in a predetermined sub-field SF virtually divided into mesh- As shown in FIG.

The drawing apparatus 100 advances the drawing process for each stripe area 20 by using a plurality of stages of deflectors. Here, as an example, a three-stage deflector such as a casting scent 208, a shingling fragrance 209, and a deflector 216 is used. The XY stage 105 continuously moves toward the -x direction, for example, and progresses the drawing toward the x direction with respect to the first stripe area 20. [ Then, after the completion of the drawing of the first stripe area 20, the drawing of the second stripe area 20 is proceeded in the same or opposite direction. Thereafter, similarly, the drawing of the third and subsequent stripe areas 20 is advanced. Then, the electron beam 200 is sequentially deflected to the reference position A of the SF 30 so that the scribe scent 208 (first deflector) follows the movement of the XY stage 105. In addition, the shunt fragrance 209 (second deflector) sequentially deflects the electron beam 200 from the reference position A of each SF 30 to the reference position B of the TF 40. The 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 to be irradiated in the TF 40 . As described above, the casting scent 208, the shingles 209, and the minor deflector 216 have deflection areas having different sizes. Then, the TF 40 becomes the minimum deflection region of the deflection regions of the plurality of stages of deflectors.

Hereinafter, the first correction division region will be referred to as TF 40 and the second correction division region will be referred to as SF (30). However, the first correction division area and the second correction division area are not limited to the TF 40 or the SF 30, and the independent areas, which are neither the TF 40 nor the SF 30, 2 correction division area. The size of the independent area is preferably smaller than the SF (30).

Fig. 3 is a flowchart showing main steps of the drawing method in the embodiment. The drawing method in this embodiment includes a shot division step S102, an irradiation amount D mapping step S104, a first correction section shot allocation step S106, a total correction amount calculation step in the first correction section (S108), a representative graphic form setting step (S110) in the first correction section, a shot allocation step (S112) in the second correction section, a total charge amount calculation step (S114) in the second correction section, (Step S116), a painting order setting step S118, a painting schedule creating step S120, an approximate calculating method determining step S122, a thermal diffusion calculating step S124, a shot temperature calculation A series of processes such as the step (S126), the irradiation amount modulation step (S190), and the drawing step (S192) are performed.

In the shot dividing step (S102), the shot dividing unit 50 inputs the drawing data associated with the pattern attribute information from the drawing data storage unit 140, and divides the drawing data into the shot data associated with the pattern attribute information.

In the irradiation amount (D) map creating step (S104), the irradiation amount map creating unit 70 calculates the necessary irradiation amount for each mesh area of a predetermined size. The mesh area is, for example, a correction compartment area. Then, the irradiation amount map is created for the entire drawing area or for each stripe area. For example, in the case of correcting the proximity effect, it is suitable to calculate the necessary dose for each proximity effect mesh area. The size of the proximity effect mesh region is preferably about 1/10 of the influence range of the proximity effect. For example, about 1 μm is suitable. Here, the irradiation dose map creating step (S104) and the shot dividing step (S102) are suitable if they are processed in parallel. However, the present invention is not limited to this, and it may be performed in series. In this case, the order may be the first.

In the first correction zone-specific shot allocation process (S106), the first correction zone-specific shot allocation unit 52 allocates each shot data segmented to the TF 40 where the shot graphic corresponding to the shot data is located .

In the total charge amount calculation step S108 in the first correction section, the total charge amount calculation section 60 in the first correction section calculates the total amount of charge of the electron beam 200 to be irradiated in the TF 40 per TF 40, The total charge amount is calculated. The total charge quantity Q is calculated as the sum of the product of the area of each shot figure irradiated in the TF 40 and the irradiation dose. The position of the TF 40 to be noted here is defined as i '. The total amount of charge Q (i ') in the TF 40 is calculated by using the area S (i) of the i-th shot in this attention TF 40 and the dose D (i) Can be defined by Equation (1). D (i) and S (i) may be calculated through the shot dividing step S102, the irradiation amount D mapping step S104, and the first correction section shot allocation step S106.

In the representative figure setting step (S110) in the first correction section, the representative figure setting section (72) in the first correction section creates a representative figure having the same area as the total area of all the shots located in the TF (40). The shape of the representative figure is, for example, square. In addition, the center of the representative figure is located, for example, at the same place as the center of gravity of all the shots located in the TF 40.

As the second correction segment shot allocation process (S112), the second correction segment shot allocation unit 54 allocates each shot data segment to the SF 30 in which the shot graphic segment is placed.

In the total charge amount calculation step S114 in the second correction section, the total charge amount calculation section 60 in the second correction section calculates the total charge amount of the electron beam 200 to be irradiated in the SF 30 for each SF 30 . The total charge amount is calculated as the sum of the product of the area of each shot figure to be irradiated and the irradiation amount in the SF 30.

As the representative figure setting step S116 in the second correction section, the representative figure setting section 74 in the second correction section creates a representative figure having the same area as the total area of all the shots located in the SF 30. [ The shape of the representative figure is, for example, square. The center of the representative figure is, for example, the same place as the place where the center of gravity of all the shots located in the SF 30 is located.

As the drawing order setting step (S118), the drawing order setting unit 58 sets the drawing order of the SF 30 and the TF 40.

4 is a conceptual diagram showing the TF imaging schedule in the SF and the total charge amount of each TF in the present embodiment. As an example in Fig. 4, a TF sequence in the x-direction first column is sequentially drawn from the TF in the lower left (lower left) disposed in the SF toward the y-direction, and the TF sequence in the x- And each TF is sequentially drawn toward the y direction. Likewise, the TFs in the TF columns in the third and subsequent rows in the x direction are similarly drawn in the y direction. In the example shown in Fig. 4, the drawing is performed using the above-described drawing schedule. In FIG. 4, the average current obtained by dividing the total charge amount Q by the drawing time of the TF is shown in the drawing order.

5 is a conceptual diagram showing an example of a drawing procedure of SFs in a stripe area in the present embodiment. 5, the SF in each stripe area includes a sequence of drawing an upWard (UWD) in which a plurality of SFs arranged in each stripe area are successively drawn in the y direction from the SF below for each SF column arranged in the y direction, And a drawing sequence of a downward word (DWD) to be sequentially drawn from the above SF toward the -y direction can be prepared.

6 is a conceptual diagram showing an example of a drawing procedure of a TF in the SF in the present embodiment. In FIG. 6, TF in each SF represents a drawing procedure (0) for drawing a first line in the y direction from the TF in the lower left direction to the x direction in order, and drawing the T line in the y direction from the TF in the left end sequentially in the x direction, (1) in which the first row in the x direction is sequentially drawn from the TF of the left side in the x direction and the y direction after the second row in the x direction and the drawing direction (2) sequentially drawing the first line in the -y direction and the second line after the -y direction in order from the TF at the left end toward the x direction, (3) in which the drawing is sequentially performed from the TF at the upper end to the -y direction in the second and subsequent rows in the x direction and the first row in the y direction are sequentially drawn from the TF at the lower right (lower right) toward the -x direction , the second row in the y direction A drawing sequence (4) for sequentially drawing from the TF at the right end toward the -x direction, and a drawing sequence (4) for drawing the first-x direction in turn from the TF at the lower right toward the y direction and the TF at the lower end (Y-1) -th direction from the TF of the upper right (upper right) to the -x direction, and -x Direction in the -x direction from the TF in the upper right direction to the -y direction in the -x direction in the order of the -x direction, and the drawing direction (7) can be prepared.

5 and 6 may be combined to set the drawing order of SF and TF. For example, it is more preferable to set it in a sequence in which heat diffusion hardly occurs.

In the drawing schedule creation step (S120), the drawing schedule creation unit 56 creates a drawing schedule based on the shot data. As an example, a method of calculating the drawing time (t _i ) of the i-th shot 42 will be described. the drawing time t _i of the i-th shot 42 is the sum of the dose D (j) of the shot 42 drawn before the i-th shot, the current density H of the electron beam 200, Th shot and the sooting time L (j) between the (j + 1) -th shot. The rendering time t _i of each shot 42 can be defined by the following equation (2). Further, the information of the current density H of the electron beam 200 may be input and set from outside. The settling time L (j) between the jth and (j + 1) th shots is calculated based on the settling time information input from the outside, the distance between the jth and (j + 1) Or the distance between the TF to which the jth shot belongs and the TF to which the (j + 1) th shot belongs, or the distance between the SF to which the jth shot belongs and the SF to which the (j + 1) do.

For the imaging time (t _j) of each TF (40), by way of example it can be set as an average value of the rendering time (t _i) of all shots belonging to the art TF. The drawing time _tk of each SF 30 can be similarly set.

If the above calculation is performed for each TF, the drawing schedule can be determined.

In the approximate calculation method determination step S122, the approximate calculation method determination unit 76 determines the approximate calculation method based on the imaging schedule created by the imaging schedule creation unit 56 and the index stored in the index storage unit 142, Lt; RTI ID = 0.0 > of the transferring < / RTI >

Table 1 summarizes the number of correction division regions that are not merged in calculation at the time of approximate calculation of the transfer column corresponding to each AI (attribute information) value in the present embodiment. The AI value is an example of pattern attribute information.

AI value The number of TFs that do not merge shots computationally Number of SFs that do not merge computationally the TF 0 ∞ ∞ One 200 10 2 One One

When the AI value is 0, the number of TFs that do not merge shots is infinite (infinite), and the number of SFs that do not merge TF by calculation is infinite. That is, drawing data corresponding to an AI value of 0 is not calculated merge. The drawing data to which the AI value of 0 is associated is the drawing data that requires the most accuracy.

When the AI value is 1, the number of TFs that do not merge shots is 200, and the number of SFs that do not merge TFs is 10. The rendering data to which the AI value of 1 is associated is the rendering data that requires precision next to the rendering data to which the AI value of 0 is associated.

Fig. 7 is a conceptual diagram of the merging of deflection areas when AI = 1 in the present embodiment. The shot to be rendered in Fig. 7 is Shot _i , and the shot on the left side of the drawing is a shot drawn temporally earlier than the shot on the right side of the paper. 7 is a conceptual diagram of a memory area of shot information stored in the memory 92, a memory area of TF information, and a memory area of SF information, and the behavior of merging the deflection areas is expressed as a transition between memory areas.

If the AI = 1, since the number TF does not merge the shot image calculation is 200, of from about the shot belongs to the TF of 200 minutes each shot in the TF TF TF _j belongs Shot _i to _{j -199} to Shot _i Respectively.

Then, the number of SFs for which the TF is not calculated for the AI value of 1 is 10. Thus, from SF _{k -18} to SF _{k -27} to which TF _j-200 belongs, the transfer sequence from each shot to Shot _i is computed for each TF to compute the transfer sequence from each TF to Shot _i , The calculation amount is reduced as compared with the case of performing the calculation every time. Here, as the merging method, for example, a representative figure having an area equal to the total area of all the shots located in the TF is referred to as a place where the center of gravity of all the shots located in the TF is located and the center of the representative figure Place them in the same place. Then, the sum of the transferring columns from each shot to Shot _i is calculated as a transferring column from the representative figure to Shot _i .

For shots belonging to SF _{k - 28} and SF _{k -29} , calculation is carried out for each SF and the transfer sequence from each SF to Shot _i is calculated, thereby reducing the amount of calculation as compared with the case of performing calculation for each shot or TF. Here, as the above merging method, for example, a representative figure having an area equal to the total area of all the shots located in the SF is referred to as a place where the center of gravity of the representative shots located in the SF is located, Place them in the same place. Then, the sum of the transferring columns from each shot to Shot _i is calculated as a transferring column from the representative figure to Shot _i .

If the AI value is 2, the number of TFs that do not merge shots is 1, and the number of SFs that do not merge TFs is 1. 2 is the drawing data in which the precision is not required.

8 is a conceptual diagram of the merging of deflection areas in the case of AI = 2 in the present embodiment. The shot to be rendered in Fig. 8 is Shot _i , and the shot on the left side in the drawing is a shot drawn temporally before the right side shot on the ground. 8 is a conceptual diagram of a memory area of shot information stored in the memory 92, a memory area of TF information, and a memory area of SF information, and the behavior of the merging of deflection areas is expressed as a transition between respective memory areas.

If AI = 2, the number of TFs that do not merge shots by calculation is 1, so the transfer column from Shot _i to Shot _i is computed only for Shot _{i -1} and Shot _{i -2} in the TF ₁ to which Shot _i belongs. do.

Then, the number of SFs that do not merge TF by calculation is 1. For this reason, TF is not calculated merely for the SF _k to which Shot _i belongs. However, since the calculation of the heat transfer Shot _i from individual shots, as described above for TF _j, by calculating the combined delivery of heat to the Shot _i for each TF from individual shots on TF _{j -1} individual By calculating the transfer sequence from TF to Shot _i , the amount of calculation is reduced as compared with the case of performing calculation for each shot.

SF _{k -1} to SF _{k -8} are computationally merged for each SF to calculate the transfer sequence from each SF to Shot _i , thereby reducing the amount of calculation as compared with the case of performing calculation for each shot or TF.

Subsequently, as the thermal diffusion calculation step (S124), the thermal diffusion calculation unit 64 calculates the heat diffusion from the other shots drawn before the shot to be drawn by the shot data, based on the approximate calculation method determined by the approximate calculation method determination unit 76 Lt; RTI ID = 0.0 ># Tij < / RTI > The temperature rise amount delta Tij represents the temperature rise amount generated by the transfer heat from the jth shot, TF or SF, of the i-th shot. The temperature rise amount delta Tij depends on the elapsed time ti-tj until the shot is drawn at time ti after another shot, TF or SF, is drawn at time tj. The temperature rise amount delta Tij is a temperature rise A (Qj), a thermal diffusion coefficient K, and a grun range (Grj) depending on the total charge Qj of shot, TF or SF drawn at time tj (3) using the coordinates (Xi, Yi) of the shot drawn at time ti, coordinates (Xj, Yj) of other shots, TF or SF drawn at time tj, can do. In this equation (3), for example, Z (depth) direction rectangular parallelepiped approximation, and TF irradiation in the case of diffusion approximation.

The heat diffusion coefficient K in equation (3) is a coefficient expressed by K ² [(mm) ² / s] = λ / (ρCp). Where λ is the thermal conductivity [W / (K · m)], ρ is the gram density [g / cm ³ ], and Cp is the specific heat [J / (K · g)]. The ground range Rg in the equation (3) is expressed by the following equation (4).

The grinding range Rg shows an average range approximation expression in the depth direction when the electron beam of energy E [keV] is vertically incident on the material having the gram density p [g / cm ³ ]. Also, A (Qj) can be expressed as A = (E Qj) / (? Cp Rg S) as an example. Here, the total charge amount [fC] (femtocoulomb) of TF _j , S is the area of the shot or representative figure [μm ² ], E, ρ, Cp and Rg are the same as above. In Equation (3), erf () represents an error function.

Based on the calculated temperature rise amount DELTA Tij, the shot temperature calculation section 66 calculates the shot temperature based on the transfer trajectory from another shot, TF, or SF drawn earlier than the shot per shot, The temperature of the shot to be drawn by the data is calculated. The shot temperature calculation unit 66 cumulatively adds the respective temperature rise amounts delta Tij generated by the transfer trains from other shots, TF, or SF drawn before the shot, for example, to obtain the representative temperature Ti of the shot , And the representative temperature (Ti) is taken as the temperature of the shot. The representative temperature Ti is defined by the following equation (5).

In the irradiation amount modulation step (S190), the irradiation amount modulating part 68 inputs the irradiation amount D (first irradiation amount) obtained for each shot, and calculates the irradiation amount D based on the representative temperature Ti of the shot to be drawn by the shot data The irradiation dose D for the shot (first irradiation dose) is modulated. The irradiation amount D '(second irradiation amount) after modulation can be obtained as D' = D · f (Ti).

In the rendering process (S192), the irradiation time calculating section 78 first calculates the irradiation time for each shot. The irradiation time can be obtained by dividing the irradiation amount D '(second irradiation amount) after modulation by the current density (H). When drawing each shot, the rendering processor 90 controls the deflection control circuit 120 so as to have an irradiation time corresponding to each shot. The rendering processor 90 controls the rendering unit 150 via the deflection control circuit 120 and the like to start the rendering process. The drawing unit 150 draws a desired pattern on the sample 101 using the electron beam 200 of the irradiation amount D '(second irradiation amount) after modulation obtained for each shot. Specifically, it operates as follows. The deflection control circuit 120 outputs to the DAC amplifier unit 130 a digital signal for controlling the irradiation time for each shot. Then, the DAC amplifier unit 130 converts the digital signal into an analog signal, amplifies it, and then applies it to the blanking deflector 212 as a deflection voltage.

The electron beam 200 emitted from the electron gun 201 (emitter) is allowed to pass through the blanking aperture 214 in the beam-ON state by the blanking deflector 212 when passing through the blanking deflector 212 And in the state of beam OFF, the entire beam is deflected so as to be shielded by the blanking aperture 214. The beam is turned ON in the beam OFF state, and then the electron beam 200 passing through the blanking aperture 214 becomes one shot of the electron beam until the beam is turned OFF. The blanking deflector 212 controls the direction of the electron beam 200 passing therethrough to alternately generate the beam ON state and the beam OFF state. For example, a voltage may be applied to the blanking deflector 212 at the time of beam-off without applying a voltage in the beam-ON state. The irradiation amount per shot of the electron beam 200 to be irradiated on the sample 101 is adjusted by the irradiation time of each shot.

Also, the process of obtaining the imaging schedule based on the irradiation dose D '(second irradiation dose) after the modulation and calculating the above temperature again to obtain the imaging schedule is repeated, and the temperature calculation is repeated until the imaging schedule converges And the number of times the drawing schedule is calculated may be limited according to the calculation speed of the calculator.

As the pattern is miniaturized, the dose is increased to reduce the influence of the shot noise. However, when the irradiation amount is increased, the resist is heated and the dimensional precision is deteriorated. It is possible to correct the irradiation amount based on the heating temperature of the resist in order to alleviate the deterioration of the dimensional accuracy. However, there is a problem that the contribution of the transfer column from all the past shots needs to be calculated and the amount of calculation is excessively increased.

It is also possible to reduce the calculation amount by stopping the influence from the past shot temporally in the middle so that the calculation time becomes shorter than the rendering time. However, depending on whether the pattern of the stopped part is dense or uneven, the temperature correction value may be uneven, and depending on the degree of interruption, heating correction from other SFs can not be coped with.

The drawing apparatus according to the present embodiment includes the drawing data storage section and the shot division section, so that the information about the degree of the precision demand is provided for the pattern figure formed by each shot. Then, by including the indicator storage unit, the rendering schedule creation unit, and the approximate calculation method determination unit, it is possible to change the method of merge in the calculation according to the degree of accuracy requirement. This makes it possible to reduce the amount of calculation required for suppressing the dimensional change of the pattern due to resist heating to a large amount for a pattern requiring precision and to a pattern for which accuracy is not required. This makes it easy to optimize the amount of calculation required to suppress the dimensional change of the pattern due to resist heating.

As described above, according to the drawing apparatus and the drawing method of the present embodiment, it is possible to provide a drawing apparatus and a drawing method that suppress the dimensional change of a pattern by resist heating while optimizing the amount of calculation.

(Second Embodiment)

The drawing apparatus of the present embodiment differs from the first embodiment in that the index that does not merge the correction division region at the time of approximate calculation of the transfer column is time. Here, description overlapping with the first embodiment will be omitted.

Table 2 summarizes the time for which the correction division area is not merged at the time of approximate calculation of the transfer column for each AI value in the present embodiment as an index.

AI value Time when the shot does not merge computationally Time when TF is not calculated merge 0 ∞ ∞ One 4 μs 40 μs 2 1 μs 10 μs

When the AI value is 0, the time during which the shot is not merged is infinite (infinite), and the time during which the TF is not merged is infinite (infinite). That is, the rendering data corresponding to the AI value of 0 is not merged by calculation.

When the AI value is 1, the time for not merging shots is 4 μs, and the time for not merging TFs is 40 μs. When the AI value is 0, the time during which the shot is not merged is 1 μs, and the time during which the TF is not merged is 10 μs.

Taking the case where the AI value is 1, for example, the transfer trajectory from the individual shot to the shot to be computed is calculated without merging for the shot drawn up to 4 μs before the shot to be computed . Subsequently, for shots drawn up to 40 μs before the shot to be calculated, the transfer sequence from each shot to the shot to be calculated is calculated for each TF except the shot drawn up to 4 μs before the shot to be calculated The amount of calculation is reduced as compared with the case of performing calculation for each shot. For the shots drawn at the previous time, the computation amount is reduced as compared with the case of performing calculation for each shot or TF by calculating merge for each SF and calculating the transfer column from the individual SF to the shot to be calculated.

In the drawing apparatus according to the present embodiment, since the merge in the calculation of shot or TF is divided by time, the approximate calculation method can be more simply determined.

As described above, according to the drawing apparatus and the drawing method of the present embodiment, it is possible to provide a drawing apparatus and a drawing method for suppressing a dimensional change of a pattern by resist heating while optimizing the amount of calculation.

(Third Embodiment)

The drawing apparatus of the present embodiment differs from the first and second embodiments in that the index for determining whether or not the correction divisional area is merged at the time of approximation of the transfer column is a temperature increase amount. Here, the description of the points overlapping with those of the first and second embodiments will be omitted.

Fig. 9 is a flowchart showing essential steps of the drawing method in the present embodiment. 10 is a conceptual diagram of the merging of deflection areas in the present embodiment.

Table 3 summarizes the temperature rise amount for determining whether or not the correction compartment area is merged with respect to each AI value in this embodiment.

AI value ε1 ε2 0 0 K 0 K One 0.01 K 0.005 K 2 0.04 K 0.02 K

When the AI value is 0, the temperature rise amount (? ₁ ) of the shot which is not calculated for the shot is 0 K, and the temperature rise amount (? ₂ ) of the TF that does not merge TF by calculation is 0 K. That is, drawing data corresponding to an AI value of 0 is not calculated merge.

When AI is 1, ε ₁ is 0.01 K and ε ₂ is 0.005 K. When the AI value is 2,? ₁ is 0.04 K and? ₂ is 0.02 K.

In the present embodiment, the rendering schedule creation unit 56 checks whether there is a shot for which the temperature rise amount? Tij is calculated (S130). When there is a shot to be subjected to the calculation processing, in the inter-shot heat spread calculation step (S132), the thermal diffusion calculation unit 64 calculates the temperature rise amount by the transfer heat from each shot to the shot (Shot _i ) lt; / RTI > Subsequently, the shot temperature calculation section 66 calculates the representative temperature Ti. On the other hand, when there is no shot to be subjected to the calculation processing, the shot temperature calculation unit 66 determines the representative temperature Ti (S188).

Next, the temperature rise amount determination unit 80 determines whether the temperature rise amount delta Tij from the shot to Shot _i is smaller than? ₁ . If? Tij is? ₁ or more, the process returns to S130. On the other hand, if? Tij is smaller than? ₁ , the drawing schedule creation unit 56 checks whether the shot is a shot to be subjected to the last calculation processing within the TF to be calculated (S134).

If the shot is the shot for which the last calculation processing should be performed in S134, the rendering schedule creation unit 56 checks whether there is a TF for which the temperature rise amount? Tij 'calculation processing should be performed (S136). When there is a TF to be subjected to the calculation processing, the thermal diffusion calculation unit 64 calculates the temperature rise amount delta Tij 'by the transfer heat from each TF to Shot _i in the shot-TF thermal diffusion calculation step (S138) , The shot temperature calculation unit 66 calculates the representative temperature Ti using the temperature rise amount? Tij '.

On the other hand, if the shot is not a shot to be subjected to the last calculation processing in S134, that is, if there remains a shot to be calculated yet in the TF to be calculated, the target of calculation in S130 and S132 The temperature rise amount delta Tij and the representative temperature Ti of the whole shot which are to be subjected to the calculation processing in the TF which is set in the TF are calculated. Then, the temperature rise amount delta Tij and the representative temperature Ti are calculated for the final shot in the TF to be calculated (S134), and the process proceeds to S136.

Taking FIG. 10 as an example, the temperature rise amount delta Tij and the representative temperature Ti are calculated in the inter-shot thermal diffusion calculation step S132 since delta Tij from Shot _i to Shot _{i -11} is larger than? ₁ . Then, in Shot _{i -12} , delta Tij <epsilon ₁ and Shot _{i - 12} is the final shot in TF _{j- 3} (S134). Subsequently, since it is possible to judge that a shot shot temporally before TF _{j -4} and TF _{j -4} can be determined as a shot in the TF to be subjected to calculation processing (S136), in the shot-TF thermal diffusion calculation step (S138) The thermal diffusion calculation unit 64 calculates the temperature rise amount DELTA Tij 'by the transfer heat from TF to Shot _i and the shot temperature calculation unit 66 calculates the representative temperature Ti. In addition, the temperature increase amount calculated by merging in terms of the TF unit may become larger than the temperature increase amount calculated in units of shots since the correction section to be calculated becomes large. Temperature increase amount of from _-4 TF _j in Figure 10 heat transfer to the Shot is Shot _{i i -} is larger than the temperature increase amount of heat transfer to the Shot _i from _12.

Then, the temperature rise amount determination unit 80 determines whether the temperature rise amount? Tij 'from the TF to the shot _i is smaller than? ₂ (S140). If? Tij 'is? ₂ or more, the process returns to S136. On the other hand, if? Tij 'is smaller than? ₂ , the rendering schedule generator 56 checks whether the TF is the TF to be subjected to the last calculation processing in the SF to be calculated (S140).

If the TF is the TF for which the TF is to be subjected to the last calculation processing in S140, the drawing schedule creation unit 56 checks whether there is an SF to which the temperature rise amount? Tij '' calculation process should be performed (S142). If there is an SF to be subjected to the calculation processing, the thermal diffusion calculation unit 64 calculates the temperature rise amount delta Tij '' due to the transfer column from each SF to Shot _i in the shot-SF thermal diffusion calculation step (S144) , And the shot temperature calculation section 66 calculates the representative temperature Ti using the temperature rise amount? Tij ''. This is done for all of the SFs to be calculated, and the representative temperature Ti is determined (S188).

On the other hand, if it is determined in step S140 that the TF is not the TF to be subjected to the last calculation process, that is, if there is a TF to be calculated yet in the SF to be calculated, the process proceeds to steps S136 and S138 And calculates the representative temperature (Ti) and the temperature rise amount (DELTA Tij ') of the entire TF to be subjected to the calculation processing in the SF. Then, the temperature rise amount delta Tij 'and the representative temperature Ti are calculated for the final TF in the SF to be calculated (S140), and the process proceeds to S142.

10, since δTij '> ε ₂ from TF _{j -4} to TF _{j -12} , the temperature rise amount ΔTij' and the representative temperature Ti are calculated in the shot-TF thermal diffusion calculation step (S138) do. SF in TF _{j -13} , since δTij '<ε ₂ , the shots drawn temporally before SF _{k -7} and SF _{k -7} are obtained from SF to Shot _i in the shot-SF thermal diffusion calculation step (S144) Calculate the temperature rise (ΔTij '') and the representative temperature (Ti) by the transfer heat. In addition, the temperature rise amount calculated by merging calculation in SF unit may become larger than the temperature increase amount calculated in TF unit because the correction section to be calculated becomes larger. In Fig. 10, the temperature rise amount due to the transfer heat from SF _{k -7} to Shot _i is larger than the temperature rise amount due to the transfer heat from TF _{j - 13} to Shot _i .

Hereinafter, it is the same as that of the first or second embodiment and will be omitted.

According to the drawing apparatus of the present embodiment, because the calculation is performed based on the temperature rise amount, the calculation amount can be reduced while calculating a high accuracy even for a shot, TF, or SF with a particularly large temperature rise amount.

As described above, according to the drawing apparatus and the drawing method of the present embodiment, it is possible to provide a drawing apparatus and a drawing method for suppressing a dimensional change of a pattern by resist heating while optimizing the amount of calculation.

In the embodiment, the description of the parts such as the apparatus configuration or the inspection method which are not directly required in the description of the present invention is omitted, but the necessary apparatus configuration or inspection method can be appropriately selected and used. All multi-charged particle beam imaging apparatuses and methods that include the elements of the present invention and which can be appropriately designed and changed by those skilled in the art are included in the scope of the present invention. The scope of the present invention is defined by the scope of the appended claims and equivalents thereof.

Claims (15)

A drawing data storage unit for storing drawing data corresponding to the pattern attribute information;
A shot division unit for dividing the rendering data into shot data associated with the pattern attribute information;
An index storage unit for storing an index for determining a correction region to be merged by calculation in approximate calculation of a transfer column corresponding to the pattern attribute information;
A drawing schedule creating unit that creates a drawing schedule based on the shot data;
Calculating approximate transferring columns from other shots drawn prior to the shots to be drawn by the shot data to be rendered, based on the rendering schedule created by the rendering schedule creation unit and the index stored in the indicator storage unit An approximate calculation method determination unit for determining an approximate calculation method for the approximate calculation method,
A thermal diffusion calculation unit for calculating a temperature rise amount due to the transferring heat from the other shot drawn before the shot to be drawn by the shot data based on the determined approximate calculation method by the approximate calculation method determining unit,
A shot temperature calculation section for obtaining a representative temperature of the shot to be drawn by the shot data based on the temperature rise amount,
An irradiation amount modulating section for modulating the irradiation amount of the shot to be drawn by the shot data based on the representative temperature,
A rendering unit for rendering the image based on the modulated irradiation amount and the imaging schedule,
A representative figure setting unit in a correction section that creates a representative figure having the same area as the total area of all the shots located in the correction division area,
And,
Wherein a center of gravity of all the shots located in the correction compartment area to be merged is located at the same position as the center of the representative figure,
And calculates the sum of the transfer column from the shot located in the correction segment area to the shot to be rendered as the transfer column from the representative figure to the shot to be imaged. The method according to claim 1,
Wherein the indicator is a number of correction division regions that do not merge at the time of approximate calculation of the transfer column. The method according to claim 1,
Wherein the indicator is a time during which the correction division area is not merged at the time of approximate calculation of the transfer column. The method according to claim 1,
Wherein the indicator is the temperature rise amount for determining whether or not the correction compartment area is merged at the time of approximate calculation of the transfer column. delete The method according to claim 1,
Further comprising: a dose map creating unit for creating the dose map by calculating the dose of the shot to be drawn by the shot data. The method according to claim 1,
And a correction section-specific shot allocation section for allocating the divided shot data to the correction division area. Dividing the rendering data corresponding to the pattern attribute information into the shot data corresponding to the pattern attribute information,
Creating a drawing schedule based on the shot data,
And a second dividing step of dividing the number of different shots to be drawn by the shot data to be rendered by the shot data to be drawn, And an approximate calculation method for approximating the transfer column from the transfer column,
Calculating a temperature increase amount due to the transferring heat from the other shot drawn before the shot to be drawn by the shot data based on the approximate calculation method,
A representative temperature of the shot to be drawn by the shot data is calculated based on the temperature rise amount,
Modulates the irradiation amount of the shot to be drawn by the shot data based on the representative temperature,
Drawing is performed based on the modulated irradiation amount and the above-described imaging schedule,
The computationally merging method includes:
A representative figure having an area equal to the total area of all the shots located in the correction compartment area to be merged on the calculation,
Wherein a center of gravity of all the shots located in the correction compartment area to be merged is located at the same position as the center of the representative figure,
Wherein the sum of the transfer column from the shot located in the correction compartment area to the shot to be rendered is calculated as a transfer column from the representative figure to the shot to be drawn from the representative figure. Dividing the rendering data corresponding to the pattern attribute information into the shot data corresponding to the pattern attribute information,
Creating a drawing schedule based on the shot data,
And a second dividing step of dividing the number of different shots to be drawn by the shot data to be rendered by the shot data to be drawn, And an approximate calculation method for approximating the transfer column from the transfer column,
Calculating a temperature increase amount due to the transferring heat from the other shot drawn before the shot to be drawn by the shot data based on the approximate calculation method,
A representative temperature of the shot to be drawn by the shot data is calculated based on the temperature rise amount,
Modulates the irradiation amount of the shot to be drawn by the shot data based on the representative temperature,
Drawing is performed based on the modulated irradiation amount and the above-described imaging schedule,
Wherein the indicator is the temperature increase amount for determining whether or not the correction compartment area is merged at the time of approximate calculation of the transfer column,
When the temperature rise amount due to the transfer column from the other shot to the shot to be drawn is equal to or larger than the temperature rise amount for determining whether or not the correction division area is merged, The lift amount is calculated,
And when the temperature rise amount due to the transfer column from the other shot to the shot to be drawn is smaller than the temperature rise amount for determining whether or not the correction division area is merged, And calculating the temperature increase amount due to the transfer heat to the shot,
Charged particle beam imaging method. 10. The method according to claim 8 or 9,
Wherein the indicator is a number of correction division regions that are not merged at the time of approximate calculation of the transfer column. 10. The method according to claim 8 or 9,
Wherein the indicator is a time during which the correction division area is not merged at the time of approximate calculation of the transfer column. 9. The method of claim 8,
Wherein the indicator is the temperature rise amount for determining whether or not the correction compartment area is merged at the time of approximate calculation of the transfer column. 10. The method according to claim 8 or 9,
And calculating the irradiation amount before modulating the irradiation amount of the shot to be drawn by the shot data,
Charged particle beam imaging method. 10. The method according to claim 8 or 9,
And allocating the divided shot data to the correction division area,
Charged particle beam imaging method. delete

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