JP2538899B2 - Charged beam drawing method and drawing apparatus - Google Patents

Description

The present invention relates to a technique for drawing a pattern by using a charged beam, and in particular, it relates to a dose correction when a pattern is drawn by a charged beam. The present invention relates to a charged beam drawing method and a drawing apparatus.

(Prior Art) Conventionally, in an electron beam drawing apparatus using a variable shaped beam, pattern repetition is used in order to shorten the time for transferring the pattern drawing data from the external storage device to the drawing control circuit. The drawing data is being compressed. For example, two rectangles 61 and 62 as shown in FIG.
When the group pattern 60 composed of 4 is arranged in a 4 × 4 array, the drawing data is represented by the arrangement data group and the graphic data group as shown in FIG. Here, the figure data group is the irradiation position x _m of the unit figure (shot 1, shot 2),
It is a set of data describing y _m , dimensions h _m , w _m, irradiation time t _{m, and the} like. Further, the arrangement data group is the position X _xi , Y _yi of the reference point of the group pattern, the number of times of repetition N _xi (= 4), N
_yi (= 4), repeated pitches P _xi and P _{yi, the} number N _i of figures for the group pattern, and the head storage address PF _i of the data storing the figure data are a set of data.

FIG. 7 shows the procedure for expanding and drawing the drawing data compressed in this way. External storage device 71 such as a magnetic disk
The drawing data stored in is transferred to the drawing buffer memory 73 through the main memory 72 of the computer that controls the system. For one unit figure to be drawn, the system uses the data X _xi , Y _yi , N _xi , N _yi , P _xi , P in the layout data.
_{Using yi} and the data x _m , y _m in the graphic data, the irradiation position calculation circuit 74 calculates N _xi , N _yi irradiation positions according to the following equation.

However, K ₁ = 0,1, ..., (N _xi −1) K ₂ = 0,1, ..., (N _yi −1) Then, the calculated irradiation positions are sequentially arranged in the irradiation position control circuit 75.
To control the irradiation position. Further, the irradiation time data t _m in the graphic data is sent to the blanking control circuit 76 N _xi × N _yi times to control the irradiation time. Further, the dimension data h _m and w _m in the graphic data are sent to the shot shape control circuit 77 N _xi × N _yi times to control the dimension of the variable shaped beam.

By the way, in the above conventional method, for one of the figures,
Irradiation time data t _m (irradiation dose data) and figure dimensions h _m ,
One each of w _m and irradiation position x _m , y _m (shape data) is defined. On the other hand, when the irradiation amount is changed for the purpose of correcting the proximity effect or the like, even if the shapes of the figures are the same, the irradiation time becomes different depending on the place where the figures exist. For example, the irradiation time of the unit graphic 21 in FIG. 2 is different from the irradiation time of the unit graphic 22 because the surrounding patterns are different.

Therefore, when drawing a pattern as shown in FIG.
Although the shape of the figure is the same in the area surrounded by the two-dot chain line in the figure, the area where data can be compressed is limited to the area within the one-dot chain line due to the difference in irradiation time due to the correction of the proximity effect and the like. It will be. That is, there is a problem that the data compression is insufficient. Further, since the data compression is insufficient, there is a problem that the data transfer time becomes long, the operating rate of the electron beam writing apparatus is lowered, and the writing throughput is lowered.

(Problems to be Solved by the Invention) Conventionally, when the proximity effect is corrected in this way, data compression becomes insufficient, the transfer time of drawing data becomes long, and the operating rate of the electron beam drawing apparatus is increased. There was a problem of lowering it.

The present invention has been made in consideration of the above circumstances, and an object thereof is to enable efficient data compression and decompression even when drawing is performed by changing the irradiation amount for proximity effect correction and the like. The object of the present invention is to provide a charged beam drawing method capable of improving drawing throughput.

Another object of the present invention is to provide a charged beam drawing apparatus for carrying out the above method.

[Structure of the Invention] (Means for Solving Problems) The essence of the present invention is that when drawing figures of the same shape, data of shapes representing height, width, etc. are commonly used,
Moreover, when drawing these figures of the same shape repeatedly,
It is to provide a mechanism capable of selecting one from two or more dose control data. This makes it possible to change the irradiation amount according to the drawing position of the figure while maintaining the same data compression efficiency as the conventional one.

That is, according to the present invention, in a charged beam drawing method for irradiating a sample with a charged beam to draw a desired pattern, drawing data is used as shape data representing the shape and size of a unit figure and a drawing position of the unit figure. One unit figure to be drawn when the group pattern is repeatedly drawn N times on the same sample. The same shape data is used for N times of repetition, and the irradiation time of the unit figure is one irradiation amount from the irradiation control data depending on the number of times of drawing or the drawing position of the group pattern. This is a method of making a decision by selecting data.

Further, according to the present invention, in a charged beam drawing apparatus for carrying out the above method, a shape data storage memory for storing shape data representing a shape and a size of a unit figure, and a dose control data for a drawing position of the unit figure. An irradiation amount control data storage memory to be stored, an arrangement data storage memory to store arrangement data of a group pattern consisting of a set of unit figures, a shape data storage memory and an irradiation amount according to the contents of the arrangement data storage memory Means for selecting the contents of the control data storage memory and means for controlling the charged beam in accordance with the contents of the arrangement data storage memory and each of the selected data are provided.

(Operation) In the present invention, even when unit figures having the same shape but different irradiation doses are repeatedly drawn, one data for the shape of the unit figure to be drawn can be repeatedly used. Therefore, it is possible to improve the compression efficiency of drawing data and shorten the data transfer time, which is unavoidable in the conventional method and eliminates the need to provide data representing the shape separately for figures with different irradiation amounts. Is possible.

(Examples) The details of the present invention will be described below with reference to illustrated examples.

FIG. 4 is a diagram showing an optical system configuration of an electron beam drawing apparatus used in the method of the embodiment of the present invention. In the figure, 40 is an electron gun, 41 is various lens systems, 42, ..., 44 are various deflection systems, 45 is a blanking plate, 46 and 47 are beam shaping aperture masks, 48 is a backscattered electron detector, and 49 is a target. Shows. The electron beam emitted from the electron gun 40 is turned on and off by the blanking deflector 42. The present apparatus makes it possible to change the irradiation amount according to the irradiation position by adjusting the irradiation time at this time.

The beam that has passed through the blanking plate 45 is shaped into a rectangular beam by the beam shaping deflector 43 and the beam shaping aperture masks 46 and 47, and the size of the rectangle is variable. The shaped beam is then used as a scanning deflector.
The target 49 is deflected and scanned by the beam 44, and the target 49 is drawn in a desired pattern by this beam scanning. The accelerating voltage of the electron beam in this apparatus is 50 [KV], and the variable shaped beam that can be generated is a rectangular beam having a maximum size of 2 [μm] and a width of 2 [μm].

FIG. 1 is a schematic diagram showing a repetitive pattern and drawing data in the method of one embodiment of the present invention. Fig. 1 (a)
As shown in FIG. 4, it is assumed that the group pattern 10 composed of two rectangles 11 and 12 is arranged in a 4 × 4 array. With respect to this array, the drawing data is composed of an arrangement data group, a shape data group, and a dose control data group, as shown in FIG. 1 (b). That is, the conventional graphic data group is divided into a shape data group and a dose control data group, and the shape data group describes the irradiation positions x _m , y _m and the dimensions h _m , w _m of the unit graphic. Data collection, dose control data group is dose of unit figure
It has become a set of data that marks the t _m. Further, as in the conventional method, the arrangement data group belongs to the group pattern reference point positions X _xi and Y _yi , the number of repetitions N _xi and N _yi , the repetition pitches P _xi and P _yi , and the group pattern. Number of unit figures
In addition to N _i , the storage start address PF _i of the shape data and the storage start address PD _{i of the} dose data are described.

Next, the repeating pattern and the drawing data for the repeating pattern will be described more specifically with reference to FIGS. 2 and 3. FIG. 2 is an example of a repeating pattern. A group pattern 10 composed of two rectangles 11 and 12 is arranged in a 5 × 5 array. The patterns within the dashed line in the figure have the same shape and size of the figure, and the same irradiation amount. However, the pattern outside the one-dot chain line has the same size and shape of the figure but different irradiation doses.

FIG. 3 is an example of drawing data for describing the pattern within the chain double-dashed line in FIG. The 16 group patterns outside the one-dot chain line have the same shape but different irradiation doses, so these are designated as the 1st to 16th group patterns. further,
Nine of the group patterns in the one-dot chain line have the same shape and the same irradiation amount, and thus they are collectively referred to as the 17th group pattern. In the conventional method, the dimensions and irradiation positions of the unit figures inside the 1st to 17th group patterns had to be set 17 times in duplicate, but in this method, as shown in the figure, the 1st to 17th groups Regarding the pattern, the shape of the unit drawing figure is expressed by one data, and the irradiation amount is also expressed by one data in the 17th group pattern.

Comparing the above-mentioned drawing data with the case of the conventional method, the arrangement data is substantially the same in both the embodiment and the conventional example, and the information amount of the irradiation amount control data is the same in both the embodiment and the conventional example. However, with regard to the shape data, conventionally, the shape data was required independently for each of the first to seventeenth group patterns, but since the shape data for one group pattern is shared by all the group patterns in the embodiment. The information amount of the shape data is remarkably reduced in the embodiment as compared with the conventional example. That is,
The data compression efficiency can be greatly improved.

FIG. 5 shows a control system for carrying out the method of this embodiment, which determines the irradiation position, irradiation shape, and irradiation amount of a unit figure from the compressed drawing data in the buffer memory, and controls it. It is a block diagram of a circuit.

The buffer memory for storing the drawing data is the arrangement data storage memory 51 for storing the array data, the shape data storage memory 52 for storing the shape data, and the irradiation control data storage memory 53 for storing the irradiation data. Seed memory. By separating the memory for shape data and the memory for dose data, a plurality of dose data can be stored for one shape data.

In the figure, the controller 50a repeatedly accesses the arrangement data storage memory 51, thereby controlling the repeated drawing of the unit figure in the group pattern, and also from the counter 54.
The control is transferred to the repeated drawing of the next group pattern by the END signal. By the access of the controller 50a, the number of repetitions N _xi , N in the xy direction is read from the arrangement data storage memory 51.
_yi , the repeating pitches P _xi and P _yi , the number of unit figures in the group pattern N _i , the storage addresses of the shape data and the dose data are output. The counter 54 receives N _xi and N _yi as inputs, and outputs an irradiation end signal sent from the irradiation position control circuit 55 to N _i × N
_When received _xi × N × N _yi times, send END signal to controller 50a
Send to

The irradiation position calculation circuit 56 calculates N _xi × N _yi irradiation positions (x _k , y _k ) for each unit figure in the group pattern according to the following equation.

However, K ₁ = 0,1, ..., (N _xi −1) K ₂ = 0,1, ..., (N _yi −1) Then, the calculated irradiation positions are sequentially sent to the irradiation position control circuit 55.

The controller 50b outputs the output from the multiplier 57 (N _xi ×
N _yi ), the number of figures N _i in the group pattern, and the shape data storage address are input. The controller 50b stores the shape data storage address in an internal register, sequentially adds a predetermined value to this register value, and obtains the storage address of the size and position data of the N unit figures in the group pattern to obtain the shape. The storage address of the data storage memory 52 is accessed. The controller 50b repeats such an operation (N _xi × N _yi ) times.

The controller 50c outputs the output from the multiplier 57 (N _xi ×
N _yi ), the number of figures N _i in the group pattern, and the irradiation data storage address. The controller 50c stores an irradiation amount data storage address in an internal register, sequentially adds a predetermined value to this register value, obtains the irradiation amount data storage addresses of N unit figures in the group pattern, and calculates the irradiation amount control data. The storage address of the storage memory 53 is accessed. The controller 50c repeats such an operation (N _xi × N _yi ) times.

The shape data storage memory 52 receives irradiation position data x _i , y _i to the irradiation position calculation circuit 56 and unit pattern size data h, w by the access of the controller 50b, and irradiation shape control circuit 5
Send to 8. The irradiation amount control data storage memory 53 sends the irradiation amount data to the irradiation amount control circuit 59 by the access of the controller 50c.

Then, the irradiation position control circuit 55 determines the deflection signal given to the scanning deflector 44, and thereby controls the beam position on the target 49. Further, the irradiation shape control circuit 58 determines the deflection signal applied to the beam shaping deflector 43, and thereby controls the shape and size of the beam. In addition, the dose control circuit 59
As a result, the blanking signal given to the blanking deflector is determined, and the irradiation time of the beam is controlled accordingly.

Thus, according to the present embodiment, the drawing data is divided into three pieces of arrangement data, shape data, and dose control data. Therefore, when changing the dose for proximity effect correction, It is possible to greatly improve the compression efficiency of the drawing data. That is, the compression efficiency does not change in the group pattern having the same shape and the same irradiation amount, but the shape data for each individual group pattern, which is conventionally necessary, is available in the group pattern having the same shape but the different irradiation amount. It becomes unnecessary and one shape data can be shared. Therefore, the data transfer time can be shortened and the operating rate of the electron beam drawing apparatus can be increased.

The present invention is not limited to the above embodiment. Although the electron beam drawing apparatus of the embodiment is a system that can generate only a rectangular variable shaped beam, the present invention can be applied to a system that generates a triangular variable shaped beam. In that case, for example, a code for distinguishing a rectangular shape from a triangular shape can be introduced inside the shape data. Further, in the embodiment, the dose control data is stored in a memory different from the shape data storage memory, but the data format in which the shape data is paired with the same dose as before is used as it is to correspond to the drawing position. Read the irradiation correction amount for the entire group pattern from the above irradiation amount control data,
It can also be implemented by a method of adding the irradiation amount of each shot to each.

Further, the structure of the electron optical lens barrel is not limited to that shown in FIG. 4 and can be appropriately changed according to the specifications. Further, it can be applied to an ion beam drawing apparatus using an ion beam instead of the electron beam. In addition, various modifications can be made without departing from the scope of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, the amount of drawing data in which the irradiation amount of each shot is set can be significantly reduced as compared with the conventional method. Therefore, the data transfer time is shortened as compared with the conventional method, and the number of samples that can be drawn in a unit time by the electron beam drawing apparatus is increased.
The drawing throughput can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a format of drawing data according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of a pattern to be drawn, and FIG. 3 is a pattern diagram of FIG. FIG. 4 is a schematic diagram showing drawing data when expressed in the data format of FIG. 4, FIG. 4 is a diagram showing an optical system configuration of an electron beam drawing apparatus for carrying out the method of the embodiment, and FIG. FIG. 6 is a block diagram showing a control system, FIG. 6 is a schematic diagram showing a data format by the conventional system, and FIG. 7 is a schematic diagram showing transfer and expansion of compressed data by the conventional system. 10 …… Group pattern, 11,12 …… Rectangular figure, 40…
… Electron gun, 41 …… Lens system, 42, ～, 44 …… Deflecting system, 46,4
7 ... Aperture mask for beam shaping, 48 ... Reflected electron detector, 49 ... Target, 50a, ~, 50c ... Controller, 51 ... Memory for storing layout data, 52 ... Memory for storing shape data, 53 ...... Memory for storing dose control data,
54: Counter, 55: Irradiation position control circuit, 56: Irradiation position calculation circuit, 57: Multiplier, 58: Irradiation shape control circuit, 59: Irradiation amount control circuit.

Claims (3)

(57) [Claims] 1. A charged beam drawing method for irradiating a sample with a charged beam to draw a desired pattern on the sample, wherein drawing data is shape data representing a shape and a size of a unit figure, and a drawing position of the unit figure. One unit figure to be drawn when the above group pattern is repeatedly drawn N times on the same sample. Shape data is N
The same irradiation amount is used for the number of times of repetition, and the irradiation time of the unit figure is set to one irradiation amount control data from the above irradiation amount control data according to the number of times of drawing repetition or the drawing position of the group pattern. A charged beam drawing method characterized by being determined by selecting. 2. A charged particle beam drawing apparatus for irradiating a sample with a charged beam to draw a desired pattern, and a shape data storage memory for storing shape data representing the shape and size of a unit figure, and a unit. Contents of the dose control data storage memory for storing the dose control data for the drawing position of the graphic, the layout data storage memory for storing the layout data of the group pattern consisting of a set of unit graphics, and the layout data storage memory And means for selecting data in the shape data storage memory and dose control data storage memory, and means for controlling the charged beam according to the contents of the arrangement data storage memory and each selected data. A charged beam drawing apparatus characterized in that 3. The means for controlling the charged beam determines a beam irradiation position according to the contents of the arrangement data storage memory and the data of the selected shape data storage memory, and stores the selected shape data storage memory. The charged beam according to claim 2, wherein the shape and size of the beam are determined according to the data of the memory, and the irradiation time of the beam is determined according to the data of the memory for storing the dose control data. Drawing device.