JP2009016439A - Method and apparatus for correcting proximity effect correction rate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for correcting a proximity effect correction rate which improve a rate of operation without suspending a charged particle beam drawing apparatus as much as possible even at error detection. <P>SOLUTION: The apparatus for correcting a proximity effect correction rate in the charged particle beam drawing apparatus that emits a charged particle beam onto a material surface to draw a given pattern on the material surface includes a pattern data receiving/controlling unit 20 which receives pattern data, a plurality of pattern developing boards 21 which receive output from the pattern data receiving/controlling unit 20 to develop a pattern, a developed pattern receiving/controlling unit 22 which receives output from the pattern developing board 21, a plurality of PEC calculation boards 23 which receive output from the developed pattern receiving/controlling unit 22 to carry out PEC calculation, and a PEC correction rate output control unit 24 which receives output from the PEC calculation boards 23 to output a PEC correction rate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a proximity effect correction amount correction method and apparatus, and more particularly to a proximity effect correction amount correction method and apparatus that do not stop drawing even if an error with low reproducibility occurs and prevent deterioration in running cost.

  When drawing a specific pattern with a charged particle beam device, even if the optimum shot time is determined from the beam current of the charged particle beam device, the resist sensitivity of the mask, etc. A fattening phenomenon occurs. This phenomenon occurs when the charged particle beam irradiated to the mask is scattered and spreads around, and is called a proximity effect.

  Proximity effect correction (hereinafter referred to as PEC) is performed to offset this effect and obtain a drawing pattern that does not depend on the density of the drawing pattern. FIG. 3 is a diagram illustrating a configuration example of a charged particle beam drawing apparatus. Here, an electron beam is used as the charged particle beam. In the figure, reference numeral 1 denotes a disk in which drawing pattern data and job data are stored. Reference numeral 2 denotes a proximity effect correction device that reads out pattern data stored in the disk 1 and performs proximity effect correction. The proximity effect correction device 2 outputs a proximity effect correction signal Smod + 1 for each pattern.

  A data transfer system 3 receives the drawing pattern data from the disk 1 and the proximity effect correction signal Smod + 1 from the proximity effect correction device 2 and transfers the data to each component of the electron beam drawing device. A blanking amplifier 4 receives shot time data sent from the data transfer system 3.

  Reference numeral 5 denotes an electron gun that emits an electron beam 6, 7 denotes a first lens that focuses the electron beam 6, and 8 denotes a blanking electrode provided in the vicinity of the first lens 7 and on the optical axis. The blanking electrode 8 is driven by the blanking amplifier 4 to control the exposure time. A blanking stop 9 is provided directly below the blanking electrode 8.

  Reference numeral 10 denotes a first shaping slit for transmitting a part of the electron beam 6, and 11 denotes a shaping deflector comprising two upper and lower electrodes provided immediately below the first shaping slit 10. The shaping deflector 11 is adapted to receive a shaping control signal from the data transfer system 3. Reference numeral 12 denotes a second lens, and reference numeral 13 denotes a second shaping slit disposed just below the shaping deflector 11. The area of the electron beam 6 is determined using the first shaping slit and the second shaping slit 13. Reference numeral 14 denotes a third lens.

  15 is a sub deflector for deflecting the electron beam 6 upon receiving a deflection signal from the data transfer system 3, 16 is an objective lens, 17 is formed so as to surround the optical axis, and various non-containers included in the electron beam 6 are included. An astigmatism corrector 18 for correcting the point aberration, 18 is a main deflector for deflecting the electron beam 6 upon receiving a deflection signal from the data transfer system 3, and 19 is a drawing material surface on which the drawing is performed.

  The disk 1 stores pattern data to be drawn, drawing conditions, and the like, and the proximity effect correction device and the data transfer system read data necessary for drawing from the disk. The proximity effect correction device 2 reads pattern data and drawing conditions from the disk 1 prior to drawing, and outputs a proximity effect correction amount (Smod + 1).

  The data transfer system 3 converts the pattern data and drawing conditions stored in the disk 1 into each deflector of the lens barrel, blanking timing (shot time), and focus astigmatism correction data. The proximity time correction amount Smod + 1 is modulated by multiplication with respect to the shot time obtained from the pattern data and the drawing conditions and output to the blanking amplifier.

  The blanking amplifier 4 outputs an analog signal having a pulse width of the shot time (digital data) output from the data transfer system 3 to the blanking electrode. The operation of the apparatus configured as described above will be described as follows.

  First, pattern data stored in the disk 1 enters the proximity effect correction device 2 and proximity effect correction data Smod + 1 is output. The data transfer system 3 receives the pattern data from the disk 1 and the proximity effect correction data Smod + 1 obtained by the proximity effect correction device 2, determines the shot time of the pattern data so that the proximity effect does not occur, and the blanking amplifier 4 is given shot time data.

  The blanking amplifier 4 controls on / off of the blanking electrode 8 to turn on the pattern data for a predetermined shot time. This pattern data passes through the first shaping slit 10 and is shaped by the shaping deflector 11, then passes through the second shaping slit 13, is deflected by the sub-deflector 15, and is corrected by the astigmatism corrector 17. Thereafter, the drawing material surface 19 is focused by the objective lens 16 and irradiated. In this case, a predetermined pattern is drawn on the drawing material surface 19 by the main deflector 18 in accordance with the pattern data to be shot.

  According to this embodiment, the correction data Smod + 1 is drawn on the drawing material surface 19 by the proximity effect correction device 2 in the shot time added to the pattern data, so that a drawing pattern from which the influence of the proximity effect is removed can be obtained. it can.

  Here, the operation of the proximity effect correction apparatus 2 will be described. FIG. 4 is a block diagram showing the configuration of the proximity effect correction apparatus. The proximity effect correction device 2 includes a pattern data reception / control unit 20, a plurality (n) of pattern development substrates 21, a development pattern reception / control unit 22, a plurality (m) of PEC operation substrates 23, and a PEC. The correction amount output control unit 24 is configured to output a PEC correction amount output from the PEC correction amount output control unit 24. The pattern development board 21 and the PEC calculation board 23 are configured by hardware because the calculation speed needs to be increased.

  The pattern data reception / control unit 20 receives the pattern data stored on the disk. The pattern data receiving / control unit 20 divides the received pattern data into sizes determined by the charged particle beam apparatus, and sequentially transfers them to the pattern development substrates 21 from # 1 to #n that are not processed. The pattern development board 21 develops pattern data sent in a specific format into two-dimensional information.

  The pattern development substrate 21 executes the development completely in parallel in order to realize high speed. The developed pattern data is received by the developed pattern reception / control unit 22 and transferred to the unprocessed PEC operation board 23. These PEC computation boards 23 perform PEC computations on the received two-dimensional data that has been developed.

  The PEC correction amount output control unit 24 receives the PEC correction amount output from the PEC calculation board 23 and outputs the PEC correction amount output according to the protocol determined by the charged particle beam drawing apparatus. The configuration shown in FIG. 4 is roughly divided into pattern development substrates 21 to #n that perform pattern development operations, a PEC operation substrate 23 that performs PEC operations, and efficiently supplies data to these operation units. The control units 20, 22, and 24 that receive output data are divided.

  This type of apparatus includes an irradiation unit that performs irradiation or non-irradiation of an electron beam based on a control signal, a deflection unit that deflects an electron beam generated from an electron beam source in accordance with an exposure pattern, and the electron beam. A technique comprising: a focusing unit that focuses on an exposure object; and a monitoring unit that monitors an abnormality of the control signal; and a mask unit that prevents the control signal from being input to the irradiation unit when the control signal is abnormal. It is known (see, for example, Patent Document 1).

Further, a technique is known in which an error that may occur during processing of control data for controlling the exposure operation is detected and the error is completely corrected (see, for example, Patent Document 2).
JP 2001-196297 A (paragraphs 0016 to 0023, FIGS. 1 and 2) JP 2001-76991 A (paragraphs 0025 to 0063, FIGS. 1 to 8)

Drawing patterns tend to be miniaturized and highly integrated, and shortening of drawing time is also desired. For this reason, both the pattern development calculation unit and the PEC calculation unit require a larger amount and a higher speed calculation. In order to realize these, hardware operations have become more severe, and the following problems have occurred more frequently than before.
1) When an error occurs, it takes time to identify and resolve the cause.
2) The error is not reproducible and it is difficult to identify the cause.
3) Due to high integration, an error may occur due to a substrate defect, and it is difficult to separate 1) and 2).

For this reason, in the charged particle beam drawing apparatus, when an abnormality occurs during drawing, the correction takes time and the running cost is deteriorated.
The present invention has been made in view of such problems, and a proximity effect correction amount correction method capable of improving the operation rate without stopping the charged particle beam drawing apparatus as much as possible even if an error is detected, and The object is to provide a device.

(1) The invention according to claim 1 is a method for correcting a proximity effect correction amount in a charged particle beam drawing apparatus that draws a predetermined pattern on a material surface by irradiating the material surface with the charged particle beam. A pattern development process for inputting and developing a pattern, and a PEC calculation process for receiving the pattern-developed data and performing a PEC calculation. The pattern development process and the PEC calculation process are continuously performed on the same substrate. If an error occurs, retry the specified number of times, and if the error is restored below the maximum number of retries, return to normal processing.If the error does not return after retrying the maximum number of retries, remove the board. It is characterized by not using it.
(2) The invention according to claim 2 is a correction device for a proximity effect correction amount in a charged particle beam writing apparatus that irradiates a material surface with a charged particle beam and draws a predetermined pattern on the material surface. Receiving pattern data receiving / controlling unit, a plurality of pattern developing substrates receiving patterns outputted from the pattern data receiving / controlling unit, a developing pattern receiving / controlling unit receiving outputs from the pattern developing substrate, and the developing pattern A plurality of PEC calculation boards that perform PEC calculation in response to an output from the reception / control section, and a PEC correction amount output control section that receives the output of the PEC calculation board and outputs a PEC correction amount, When an error occurs on the board and / or PEC calculation board, retry a specified number of times, and if the error is restored below the maximum number of retries Returning to normal processing, even if the maximum number of retries retry error If resetting, characterized in that to avoid using the substrate.

(1) According to the first aspect of the invention, when the error is recovered within the maximum number of retries, the process returns to the normal processing, and when the error is not recovered even after retrying the maximum number of retries, the board is not used. Therefore, even if an error is detected, the operating rate can be improved without stopping the charged particle beam drawing apparatus as much as possible.
(2) According to the invention described in claim 2, when the error is recovered within the maximum number of retries, the process returns to the normal processing, and when the error is not recovered even after retrying the maximum number of retries, the board is not used. Therefore, even if an error is detected, the operating rate can be improved without stopping the charged particle beam drawing apparatus as much as possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart showing pattern development processing. 3 and 4 are used as the charged particle beam drawing apparatus and the proximity effect correction apparatus. The proximity effect correction device 2 constantly monitors whether an error has occurred in the pattern development substrate 21 during normal operation (S1). If no error has occurred, normal processing continues.

  When a pattern development error occurs, the pattern development board 21 in which the error has occurred has its own number #i (i = 1 to n) and the pattern division number Fi in which the error has occurred in the development pattern reception / control unit 22. Notify (S2). Here, the partition number is a field number (the same applies hereinafter). The developed pattern reception control unit 22 rereads the Fi section pattern (S3). Then, the proximity effect correction device 2 checks whether or not the number of consecutive errors that occur in the same #i and Fi is equal to or less than the maximum number of retries (S4). Here, it is assumed that the maximum number of retries is set and stored in the proximity effect correction apparatus 2 in advance.

  When the number of times that an error has occurred is less than or equal to the maximum number of retries, that is, when the error is recovered without reaching the maximum number of retries, the proximity effect correction device 2 initializes the pattern development board #i and returns from the error state. (S5). Then, the development pattern receiving / control unit 22 transfers the pattern of the section Fi to the pattern development board #i (S6). The pattern development substrate #i re-deploys the section Fi (S7). Then, it returns to step S1.

  On the other hand, if the number of consecutive errors in step S4 exceeds the maximum number of retries, the pattern development substrate 21 is not used. For this reason, the proximity effect correction apparatus 2 thereafter sets the pattern development substrate #i not to be used for pattern development (S8). Next, the development pattern receiving / control unit 22 transfers the pattern of the section Fi to the pattern development board #i and the pattern development board 21 other than the pattern development board 21 in which the past error has occurred (S9). In this case, the pattern development substrate 21 that has received the pattern of the section Fi re-deploys the section Fi pattern, and returns to step S1.

  FIG. 2 is a flowchart showing the PEC calculation process. 3 and 4 are used as the charged particle beam drawing apparatus and the proximity effect correction apparatus. The proximity effect correction device 2 constantly monitors whether an error has occurred in the PEC computation board 23 during normal operation (S1). If no error has occurred, normal processing continues.

  When an error occurs, the PEC computation board 23 in which the error has occurred notifies the development pattern reception control unit 22 of its own #j and the development pattern section number Fj in which the error has occurred (S2). The development pattern reception control unit 22 reads the development pattern of the section of Fj again (S3). Next, the proximity effect correction device 2 checks whether or not the number of consecutive errors in the same #j and Fj is equal to or less than the maximum number of retries (S4).

  If it is less than the maximum number of retries, the error is recovered. Therefore, the proximity effect correction device 2 initializes the PEC operation boards # 1 to #m and returns them from the error state (S5). Then, the development pattern reception / control unit 22 transfers the development pattern of the section Fj to the PEC computation board #j (S6). Next, the PEC operation board #j recalculates the section Fj development pattern (S7), and the process returns to step S1.

  On the other hand, if the number of errors exceeds the maximum number of retries in step S4, the proximity effect correction device 2 thereafter sets not to use the PEC calculation board #j for pattern development (S8). Thereafter, the development pattern reception / control unit 22 transfers the development pattern of the section Fj to other than the PEC computation board #j and the PEC computation board 23 in which the past error has occurred (S9). Then, the PEC computation board 23 that has received the development pattern of the section Fj recalculates the development pattern of the section Fj (S10), and returns to step S1.

  As described above, according to the present embodiment, when the error is recovered within the maximum number of retries, the process returns to the normal processing, and when the error is not recovered even after the maximum number of retries is retried, the board is not used. Therefore, even if an error is detected, the operation rate can be improved without stopping the charged particle beam drawing apparatus as much as possible.

  Next, the principle of proximity effect correction (PEC) will be described. The scattering distribution around the beam shot position due to the scattering of the charged particle beam is expressed by the following equation.

Here, E is the incident electron energy distribution on the mask, which is an amount normalized by the energy required for painting. It is 1 at the position where the pattern is to be drawn, and 0 when there is no pattern. At the present time, including no approximation, the distribution amount has only binary values of 1, 0. Eid represents the distribution of the electron beam when the electron beam is applied to only one point on the mask. By the proximity effect correction, the following calculation is performed in order to obtain a pattern as aimed at E regardless of the pattern distribution.

Here, Da is the amount of electron beam energy for each electron beam first shot for drawing one figure, and η is the backscattering coefficient. The meaning of this equation is an equation indicating that the sum of the first term representing the amount of incident electrons and the second term representing the scattering of incident electrons is constant. Therefore, the object of the proximity effect correction calculation is to obtain Smod + 1 that satisfies this equation for each electron beam shot. However, it is difficult to solve equations (2) and (3) analytically for Smod + 1. This is because Smod + 1 in the second term of the expressions (2) and (3) is a weight for E in the convolution integral of E and Eid. Therefore, Smod + 1 in the second term of the expressions (2) and (3) is regarded as a multiplication of Ebp, and the expression (4) is obtained.
(Smod + 1) + C2 × η × Ebp (x, y) × {Smod (xx ′, yy ′) + 1}
= C1 (4)
Solving equation (4) for Smod + 1,
Smod (x, y) + 1 = C1 / {1 + C2 × η × Ebp (x, y)} (5)
However, since what is obtained by equation (5) includes the approximation performed by equation (4), it is asymptotic to the analytical values of equations (2) and (3) by the following procedure. By substituting Smod + 1 obtained by the equation (5) into the equations (2) and (3) again, Ebp ′ is expressed by the following equation.

When Smod + 1 obtained by the equation (5) is used to obtain the equation (6) and the equation (6) is substituted as Ebp into the equations (2) and (3), Smod + 1 is expressed by the following equation.
Smod + 1 = C1− {C2 × η × Ebp ′ (x, y)} (7)
And can be solved for Smod + 1. Subsequently, Smod + 1 can be made asymptotic to the analytical solution of equations (2) and (3) by repeating the calculations of equations (6) and (7) in the same manner.

  However, in actual calculations, since the equations (1), (5), (6), and (7) are calculated at high speed by hardware, it is necessary to sample and quantize each signal. Expressions (1), (5), (6), and (7) are respectively expressed by expressions (8), (9), (10), and (11).

Smod + 1 = C1 / (1 + C2 × η × Ebp _{m, n} ) (9)

Smod + 1 = C1- {C2 * [eta] * Ebp'm _{, n} } (11)
Expressions (8) to (11) are all sampled in the same section with m, n, i, and j. However, E is the ratio of the incident energy of electrons from the binary signal of only 1 and 0 in the equation (1), which is 1 when the entire area is filled and 0 when there is no pattern in the area. Has a value in the range.

From the above, when performing proximity effect correction, the hardware performs the convolution of equations (8) and (10) and the four arithmetic operations necessary for equations (9) and (11).
The effects of the present invention described above will be described as follows.
1) Even if an error with low reproducibility occurs, drawing does not stop, and deterioration of running cost can be prevented. 2) Further, since the influence of errors with low reproducibility does not appear in drawing, the mask is not wasted.
3) Since a defective board is specified, it is possible to quickly cope with a problem by replacing the board.

  As described above, according to the present invention, it is possible to provide a proximity effect correction amount correction method and apparatus that can improve the operation rate without stopping the charged particle beam drawing apparatus as much as possible even if an error is detected. .

It is a flowchart which shows a pattern expansion process. It is a flowchart which shows PEC calculation processing. It is a figure which shows the structural example of a charged particle beam drawing apparatus. It is a block diagram which shows the structure of a proximity effect correction apparatus.

Explanation of symbols

20 Pattern Data Reception / Control Unit 21 Pattern Development Board 22 Development Pattern Reception / Control Unit 23 PEC Calculation Board 24 PEC Correction Output Control Unit

Claims (2)

In a method for correcting a proximity effect correction amount in a charged particle beam drawing apparatus that irradiates a material surface with a charged particle beam and draws a predetermined pattern on the material surface.
Pattern development process to input pattern data and develop the pattern,
A PEC operation step of receiving the pattern expanded data and performing a PEC operation;
In each of the pattern development process and the PEC calculation process, when an error occurs continuously on the same substrate, a predetermined number of retries are performed, and when the error is restored below the maximum number of retries, a normal operation is performed. Return to processing
A proximity effect correction amount correction method, wherein an error is not recovered even after retrying the maximum number of retries, and the board is not used. In a proximity effect correction amount correction apparatus in a charged particle beam drawing apparatus that irradiates a material surface with a charged particle beam and draws a predetermined pattern on the material surface.
A pattern data receiving / control unit for receiving pattern data;
A plurality of pattern development substrates that receive the output of the pattern data reception / control unit and develop a pattern;
A development pattern receiving / control unit for receiving the output of the pattern development substrate;
A plurality of PEC operation boards for performing a PEC operation in response to an output from the development pattern reception / control unit;
A PEC correction amount output control unit that receives the output of the PEC calculation board and outputs a PEC correction amount;
When an error occurs in the pattern development board and / or the PEC calculation board, a predetermined number of retries are performed, and when the error is restored below the maximum number of retries, the process returns to normal processing.
A proximity effect correction amount correction apparatus, wherein an error is not recovered even after retrying the maximum number of retries, and the board is not used.

Images