JPH0673343B2 - Charged beam drawing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a charged beam drawing method for drawing a pattern of an LSI or the like on a sample using a variable shaped beam, and particularly to a method for controlling an exposure time at the time of drawing. The present invention relates to an improved charged-beam drawing method.

[Technical background of the invention and its problems]

When a fine LSI pattern is drawn using an electron beam drawing apparatus, there is a so-called proximity effect in which the pattern size becomes thicker or thinner than the original exposure pattern depending on the shape of the drawing pattern. In order to correct this proximity effect, the conventional apparatus employs a method of controlling the shape of the exposure pattern or the exposure time by the variable shaped beam.

However, this type of method has the following problems. That is, data for controlling the beam shape, position and exposure time are sent from the control computer. The correction amount of the proximity effect depends on the development condition of the exposed resist and the like, and if the conditions are different, it is necessary to re-execute the proximity effect correction calculation and create another drawing data. This correction calculation usually requires a large amount of calculation processing, has a large calculation processing cost, and has a problem of having to wait a long calculation time.

The above problem is not limited to the electron beam writing method, and can be similarly applied to the ion beam writing method of writing a desired pattern using an ion beam.

[Object of the Invention]

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to make it possible to easily perform variable control of an exposure time, and to perform a resist process when a pattern is drawn by performing proximity effect correction. It is an object of the present invention to provide a charged beam drawing method capable of effectively performing the proximity effect correction calculation again without changing the conditions and the like even if the conditions are changed.

[Outline of Invention]

The essence of the present invention is that, as the drawing data, instead of specifying the beam exposure time (or the irradiation amount) for each pattern as in the conventional case, the change amount of the reference exposure time is specified. Is to be set in advance separately from the drawing data, and the actual exposure time is determined by these data.

That is, the present invention is a charged beam drawing method for drawing a desired pattern on a sample by controlling the position, shape and exposure time of the variable shaped beam on the sample, and presetting variable reference exposure time data, and The pattern design data includes exposure time change data representing the amount of change with respect to the reference exposure time, and as the control of the exposure time, the exposure time change data specified by the pattern design data with respect to the reference exposure time data is used. Calculate the actual exposure time using, control the actual exposure time using this calculation result,
When the process condition is changed, the reference exposure time data is changed to the reference exposure time data corresponding to the process condition, a new actual exposure time is calculated, and an actual exposure time is calculated using this new calculation result. This is a method of controlling the exposure time.

EFFECTS OF THE INVENTION According to the present invention, the exposure time designated by the drawing data (pattern design data) after the proximity effect correction calculation indicates the change amount of the reference exposure time, and the process conditions are changed to change the reference irradiation. Even if it is necessary to change the amount, it is only necessary to reset the reference exposure time without re-execution of the proximity effect correction calculation. Therefore, even if the process conditions of the resist are changed, the proximity effect can be effectively corrected without requiring a large amount of calculation processing and a long calculation time.

Example of Invention

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

FIG. 1 is a schematic configuration diagram showing an electron beam drawing apparatus used in a method of an embodiment of the present invention. In the figure, 10 is an electron optical lens barrel, and this optical lens barrel 10 is composed of an electron gun, various lenses, various deflection systems, and the like. A sample chamber 11 is provided below the electron optical column 10. In this sample chamber 11,
A sample stage 13 on which a sample 12 to be subjected to electron beam drawing is placed is housed. The sample stage 13 is moved in the X direction (left and right direction on the paper) and the Y direction (front and back direction on the paper) by the stage drive circuit 16 which receives a command from the computer 14 via the interface 15. Then, the moving position of the sample stage 13 is measured by the position measuring circuit 17, and the position information is sent to the beam control circuit 18.

On the other hand, the drawing data (pattern design data) is sent from the computer 14 via the interface 15 to the beam control circuit 18 and the exposure time changing circuit 19. Exposure time changing circuit 19
Is for inputting reference exposure time data T ₀ and exposure time change data A, which will be described later, to calculate the actual exposure time, and the calculation result is supplied to the beam control circuit 18. The beam control circuit 18 generates a signal for controlling the shape and position of the beam based on each of the above-mentioned input data, controls the electron optical lens barrel 10 for drawing, and also generates a beam blanking signal. The exposure time is controlled accordingly.

In drawing a pattern in this apparatus, first, the sample stage 13 is moved to a predetermined position from the computer 14 via the interface 15. After that, by deflecting and blanking the electron beam while the sample stage 13 is stopped or continuously moved,
Draw the desired pattern on 12.

Here, the pattern design data is stored in a format pattern data memory or the like as shown in FIG. That is,
Assuming that a pattern 22 to be drawn exists in the drawing area 21 as shown in FIG. 2 (a), in the conventional device, as shown in FIG. 2 (b), the pattern (22) has coordinates (x, y) and a width W. The exposure time T is stored in the pattern data memory or the like together with the data such as the height H and the like. On the other hand, in this embodiment, instead of the exposure time data T, the exposure time change data A is stored as shown in FIG. Then, the exposure time change data A of the pattern design data
Is supplied to the exposure time changing circuit 19 together with the reference exposure time data T ₀ . Other data x, y, W, H are beam control circuit 18
Has been supplied to. The reference exposure time data T ₀ is data representing a reference time for all patterns to be drawn and is preset in the computer 14. Exposure time change data A (A ₁ , A ₂ , ...
...) is for obtaining the actual exposure time by adding, subtracting or multiplying to the reference exposure time data T ₀ , which is determined for each pattern and together with the x, y, W, H data. It is included in the pattern design data.

3 and 4 are block diagrams showing a specific configuration of the exposure time changing circuit 19, respectively. In the example of FIG. 3, the exposure time change data A is added to the reference exposure time data T ₀ to obtain the actual exposure time. The exposure time change circuit 19 is composed of a reference exposure time register 31 and an adder 32. Has been done. The reference exposure time data T ₀ is written in the register 31 by the computer 13 prior to drawing. At the time of drawing, the data stored in the register 31 is supplied to the adder 32 together with the exposure time change data A designated by the pattern design data. And
The addition output (T ₀ + A) of the adder 32 is supplied to the beam control circuit 18 as actual exposure time data. The exposure time change data A can take both positive and negative values.

In the example of FIG. 4, the reference exposure time data T ₀ is multiplied by the exposure time change data A to obtain the actual exposure time.
The exposure time changing circuit 19 includes a reference exposure time register 41, an offset register 42, a multiplier 43, and an adder 44. Further, in this example, the offset data B for time change
Is to be added. This offset value is treated as a part of the reference exposure time data T ₀ . The reference exposure time data T ₀ (including the offset data B) is stored in the registers 41 and 42 in advance before drawing. When drawing,
Exposure time change data A specified by pattern design data
Is input to the multiplier 43, the reference exposure time data T ₀ is multiplied by the exposure time change data A by the multiplier 43, and the content of the offset register 42 is added by the adder 44. Then, the addition output (A · T ₀ + B) is sent to the beam control circuit 18 as actual exposure time data. It should be noted that the offset register 42 and the adder 44 may be omitted if they are not necessary in terms of device performance.

Next, a pattern drawing method using the electron beam device configured as described above will be described. Since the method is the same as the conventional method except for the control of the exposure time, the method of controlling the exposure time will be described here in particular.

As described above, the pattern design data includes various data x, y, W, H, A, and the exposure time change data A is determined in advance according to conditions such as the size of the pattern. To do. First, depending on the resist process conditions, etc.
The reference exposure time data T ₀ is set in the computer 14. At the time of drawing, the exposure time change data A of the pattern design data
Are supplied to the exposure time changing circuit 19 together with preset reference exposure time data T ₀ . Other pattern data x, y,
W and H are supplied to the beam control circuit 18.

When the exposure time changing circuit 19 has the configuration shown in FIG. 3, the reference exposure time data T ₀ and the exposure time changing data A
Based on the above, the actual exposure time data (T ₀ + A) is calculated by adding them. And this data (T ₀ +
A) is supplied to the beam control circuit 18. Beam control circuit
In 18, a beam deflection signal and a blanking signal are generated based on the above-mentioned input data (T ₀ + a) and the input data x, y, W, H, etc. from the computer 13. This allows
The shape, position, exposure time, etc. of the electron beam are controlled, and a desired pattern is drawn on the sample 12 in a state where there is little influence of the proximity effect.

Here, when the developing process conditions of the resist are changed, the reference exposure time data T _{0 is} reset. in this case,
The actual exposure time is automatically obtained by the arithmetic processing in the exposure time changing circuit 19 described above, and the changed exposure time data is supplied from the exposure time changing circuit 19 to the beam control circuit 18. Then, the beam control circuit 18 changes the exposure time and draws a pattern in the same manner as described above.

As described above, according to the method of this embodiment, the amount of change from the reference exposure time T ₀ (exposure time change data A) is designated as the pattern design data, and the reference exposure time data T ₀ is used as the pattern design data. By setting them separately, the actual exposure time for each pattern can be calculated by the exposure time changing circuit 19 and obtained. In this case, when it is necessary to change the exposure time due to a change in the resist process condition, it is only necessary to reset the reference exposure time T ₀ , and the proximity effect correction is recalculated to obtain another pattern design data. No need to create. Therefore, it is possible to easily perform the variable control of the exposure time and effectively correct the proximity effect.

The present invention is not limited to the method of the embodiment described above. For example, the calculation process for obtaining the actual exposure time is not limited to (T ₀ + A), (A · T ₀ ), (A · T ₀ + B), etc., and the exposure time may vary depending on the resist development process conditions. It may be determined to be optimum. Further, the configuration of the exposure time changing circuit can be changed as appropriate according to the above-described arithmetic processing. The structure of the exposure apparatus is not limited to that shown in FIG. 1 and can be applied to various apparatuses as long as it is a variable shaped beam type electron beam drawing apparatus. Further, the present invention is not limited to the electron beam drawing method, and can be applied to an ion beam drawing apparatus that draws a desired pattern using an ion beam. In addition, various modifications can be made without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an electron beam drawing apparatus used in a method of one embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of pattern design data used in the above embodiment, FIGS. 3 and 4.
Each of the drawings is a block diagram showing a specific configuration of the exposure time changing circuit. 10 ... Electron optical lens barrel, 11 ... Sample chamber, 12 ... Sample, 13 ...
… Sample stage, 14 …… Computer, 15 …… Interface, 16 …… Stage drive circuit, 17 …… Position measuring circuit, 18
...... Beam control circuit, 19 …… Exposure time change circuit, 31,41,
42 ... Register, 32,44 ... Adder, 43 ... Multiplier.

Claims (3)

[Claims] 1. A charged beam extraction method for extracting a desired pattern on a sample by controlling the position, shape and exposure time of the variable formed beam on the sample, and presetting variable reference exposure time data. In addition, the pattern design data includes exposure time change data representing the amount of change with respect to the reference exposure time, and the exposure time change is specified with respect to the reference exposure time data as control of the exposure time. The actual exposure time is calculated using the data, the actual exposure time is controlled using this calculation result, and when the process condition is changed, the reference exposure time data is changed to the reference exposure time corresponding to the process condition. Charged beam characterized by changing to data, newly calculating the actual exposure time, and controlling the actual exposure time using this new calculation result Field method. 2. An exposure time conversion data designated by the pattern design data is added to or subtracted from the reference exposure time data as a means for calculating an actual exposure time. Item 1. The charged beam extraction method according to item 1. 3. As a means for calculating an actual exposure time, the reference exposure time data is multiplied by exposure time conversion data specified by the pattern design data as an exposure time adjustment ratio. The charged particle beam drawing method according to claim 1.