JPH1020481A - Mask set for charged beam exposure and charged beam exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mask set for charged beam exposure and a charged beam exposure method capable of transferring patterns and improving throughput by using a smaller wafer. SOLUTION: Masks 11, 12 for constituting the mask set by dividing mask patterns to plural divided patterns and forming these patterns on respectively different samples are manufactured. At the time of exposure, the masks 11, 12 are placed on the stage 4 of the charged beam exposure device and while the stage 4 is successively moved, the patterns formed in the plural regions 2a to 2h of the masks 11, 12 are successively exposed and transferred onto the samples. The masks 11, 12 may be arranged on the stage 4 along the continuous movement direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a charged beam exposure mask set and a charged beam exposure method in a charged beam exposure apparatus used for lithography of semiconductor integrated circuits and the like.

[0002]

2. Description of the Related Art In recent years, in lithography in LSI manufacturing, a charged beam exposure apparatus having both high resolution and high throughput of exposure has been studied. Conventionally, in this type of exposure apparatus, a batch transfer method for exposing a pattern of one chip or a plurality of chips at a time is used. However, the batch transfer method has drawbacks in that it is difficult to manufacture a mask serving as a master for transfer, and it is difficult to suppress aberration to within required accuracy because the optical field has a size of one chip or more.

For this reason, recently, an exposure system called a division transfer system has been proposed. In the split transfer method, 1
The pattern for the chip is divided into a plurality of small areas on the mask, and the charged beam is deflected by the deflector while moving the mask, so that the small areas are sequentially irradiated with the charged beam to perform reduced transfer exposure. In addition, at the time of transfer, aberrations such as focal point and field distortion of an image of a small area formed on a transfer surface (hereinafter, referred to as a sample surface) such as a silicon wafer are corrected for each small area. Expose. Therefore, it has a larger optical field than the batch transfer method, and can perform high-resolution and high-accuracy exposure over a wide area.

FIG. 5 shows an example of a mask used in the division transfer method, and FIG. 5A is a diagram for explaining division of a chip pattern. 1 is a pattern for one chip, and the chip pattern 1 is divided into eight regions 1a, 1b,..., 1g, and 1h. The pattern of the region 1a is formed in the region 2a of the mask 2, and the patterns of the regions 1b, 1c,..., 1h are similarly formed in the corresponding regions 2b, 2c,. On the mask 2, regions 2a to 2h are formed separately from each other, and an alignment mark 3 as shown in FIG.
Are provided. The mask 2 is manufactured using a silicon wafer. The thickness of the portions of the regions 2a to 2h and the alignment marks 3 is several μm or less, and the thickness of the other portions is about 1 mm. FIG. 5B is an enlarged view of a part of the region 2a shown in FIG. 5A, and the region 2a is further divided into a plurality of minute regions 211, 212,. Each side portion of the rectangular minute regions 211, 212,... Has a width (dimension in the surface direction of the mask 2) of 0.1 mm in order to reinforce the mechanical strength of the region 2a having a thickness of several μm or less.
A beam having a thickness (dimension in the thickness direction of the mask 2) of about 1 mm may be formed.

Next, the exposure procedure will be described. .. Represent the areas exposed by one shot of the charged beam, and deflect the charged beam in the y direction while continuously moving the mask 2 in the −x direction in FIG.
The entire region 2a is exposed from the left end to the right end as shown in the path A of (b). After the exposure to the right end of the area 2a, the mask 2 is step-moved in the -y direction, and the mask 2 is moved in the x direction and exposed from the right end to the left end of the area 2b in the same manner as the area 2a. Similarly, by exposing the regions 2c to 2h, the entire chip pattern 1 is exposed and transferred onto the sample surface.

[0006]

However, in the above-described split transfer system, the reduction ratio of the optical system is reduced to 1/4, 1 in order to reduce the difficulty in manufacturing a mask, dust, and heating of a charged beam. A high reduction ratio of / 5, 1/10 or the like is adopted, and the size of the mask pattern on the mask 2 becomes 4, 5, 10 times or the like of the size of the chip formed on the sample. In addition, in order to maintain the mechanical strength of the mask 2, the regions 2a,
2b are formed separately, and the minute regions 21 are formed.
Since the beams are provided between 1, 2,..., The size of the mask 2 is further increased.

In the case of transferring a ring-shaped pattern 62 as shown in FIG. 6A in a stencil mask, for example, the pattern 62 is divided into two complementary patterns 62a and 62b. Since each is formed in different regions 63a and 63b on the mask, the size of the mask is twice or more. Therefore, the size of the mask 2 becomes larger than the size of a silicon wafer which can be actually obtained, and there is a possibility that the mask cannot be manufactured.

An object of the present invention is to provide a charged beam exposure mask set and a charged beam exposure method capable of transferring a pattern using a smaller wafer and improving the throughput.

[0009]

An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. (1) The charged beam exposure mask set according to the first aspect of the present invention includes a plurality of divided masks 11 and 12 formed by dividing a mask pattern into a plurality of parts and forming these divided patterns on different substrates (eg, silicon wafers). The above object is achieved by being constituted. (2) The invention of claim 2 is applied to the charged beam exposure method using the mask set according to claim 1, and each of the divided masks 11 and 12 is placed on the mask stage 4 of the charged beam exposure apparatus. Then, the patterns formed in the plurality of small areas 2a to 2h of the divided masks 11 and 12 are sequentially exposed and transferred onto the sample 38 while at least the mask stage 4 is continuously moved. (3) According to a third aspect of the present invention, in the charged beam exposure method according to the second aspect, the plurality of divided masks 11 and 12 are arranged on the mask stage 4 along the continuous movement direction. (4) According to a fourth aspect of the present invention, there is provided an alignment method for a charged beam exposure apparatus for placing each of the divided masks 11 and 12 according to the first aspect on a mask stage 4 and exposing and transferring a mask pattern onto a sample 38. And the positional relationship between each of the divided masks 11 and 12 and the divided mask 11 and the sample 3
The above-mentioned object is achieved by measuring the positional relationship between the sample 8 and the other divided masks 12 based on the measured values. (5) According to a fifth aspect of the present invention, there is provided an alignment method for a charged beam exposure apparatus for placing each of the divided masks 11 and 12 according to the first aspect on a mask stage 4 and exposing and transferring a mask pattern onto a sample 38. And the positional relationship between each of the divided masks 11 and 12 and the mask stage 4 and the positional relationship between the mask stage 4 and the sample 38 are measured. Based on the measured values, each divided mask 1 is measured.
The above-mentioned object is achieved by calculating the positional relationship between the samples 1 and 12 and the sample 38.

(1) According to the first and second aspects of the present invention, the charged beam exposure mask set includes two divided masks 11 and 12 having a smaller area. (2) According to the third aspect of the present invention, for example, two small areas 2a, 2a,
Exposure transfer of the pattern 2b is performed. (3) In the invention of claim 4, when performing the alignment,
Between the division masks 11 and 12 and between the division mask 11 and the sample 3
8 are measured, and the divided mask 12 and the sample 38 are measured.
The measurement of the positional relationship between them is omitted. (4) In the invention of claim 5, when performing the alignment,
The positional relationship between the divided masks 11 and 12 and the mask stage 4 and the positional relationship between the mask stage 4 and the sample 38 are measured, and the measurement of the positional relationship between the divided masks 11 and 12 and the sample 38 is omitted. Is done.

In the section of the means for solving the above-mentioned problem which explains the constitution of the present invention, the drawings of the embodiments of the present invention are used in order to make the present invention easy to understand. However, the present invention is not limited to the embodiment.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a view for explaining a charged beam exposure mask according to the present invention. In FIG.
Reference numeral 4 denotes a mask stage of the charged beam exposure apparatus, and two masks 11 and 12
Is placed. The masks 11 and 12 are fixed to the stage 4 by mechanical force including adhesion, electrostatic attraction force, or the like. The mask 11 and the mask 12 are formed on separate silicon wafers. The patterns of the regions 1a, 1d, 1e, and 1h of the chip pattern 1 (see FIG. 5) are in the regions 2a, 2d, 2e, and 2h of the mask 11, and the chip pattern 1 is in the regions 2b, 2c, 2f, and 2g of the mask 12. Are formed respectively in the regions 1b, 1c, 1f, and 1g. The patterns formed in the regions 2a to 2h of the masks 11 and 12 are the same as those formed on the mask 1 of FIG. 11A, 12
A is an alignment mark provided on the masks 11 and 12, and 5 is an alignment mark provided on the stage 4, which is used for alignment of the masks 11 and 12, respectively. During exposure, the stage 4 moves continuously in the x direction in the figure.

FIG. 2 is a view schematically showing a charged beam exposure apparatus, and a method of aligning the masks 11 and 12 will be described with reference to FIG. First, each configuration of the charged beam exposure apparatus will be described. Reference numeral 30 denotes a charged beam generating source. A charged beam 31 emitted from the charged beam generating source 30 is converted into a parallel beam by a condenser lens 44, deflected in an xy plane by a deflector 32, and mounted on the stage 4. Irradiation is performed on any one of 11 and 12. The charged beam 31 that has passed through the mask 11 or 12 is deflected by a predetermined amount by a deflector 46 and then imaged at a predetermined position on a sample 38 by lenses 48 and 49.

A driving device 33 drives the stage 4 in the x and y directions, a position detector 34 detects the position of the stage 4 in the x and y directions, and 35 denotes masks 11 and 12 and alignment marks 11A and 12A of the stage 4. And 5 (see FIG. 1), and the detection values of the position detector 34 and the mark detector 35 are
Sent to 6. Note that a laser interferometer or the like is used as the detector 34. Reference numeral 37 denotes a stage on which the sample 38 is placed, 39 denotes a driving device that drives the stage 37 in the x and y directions, and 40 denotes a position detector that detects the position of the stage 37 in the x and y directions. Reference numeral 41 denotes a mark detector for detecting an alignment mark (not shown) provided on the sample 38, and the detection values of the detectors 40 and 41 are sent to the control device 36. The control device 36 controls the amount of deflection of the charged beam 31 by the deflectors 32 and 46 and the operation of the stages 4 and 37 based on the detection values from the position detectors 34 and 40 and the mark detectors 35 and 41. Required information (for example,
Position and moving speed). The calculation result is the deflector 32,
Deflector setting devices 45 and 47 for setting the deflection amount of 46 and drivers 42 and 4 for controlling the operations of the driving devices 33 and 39.
3 respectively.

Next, a method for aligning the masks 11, 12 and the sample 38 will be described. The alignment marks 11A and 12A of the masks 11 and 12 mounted on the stage 4 are detected by the mark detector 35, and the position of the stage 4 at that time is detected by the position detector 34. The control device 36 calculates the positional relationship (rotation, displacement) between the masks 11 and 12 based on the detection values of the mark detector 35 and the position detector 34. The relative position measurement between the masks 11 and 12 is performed at a frequency of several times a day to several times a week during repeated exposure. Next, the alignment marks 11A of the mask 11 and the alignment marks of the sample 38 are detected by the mark detectors 35 and 41, and the positions of the stages 4 and 37 at that time are detected by the position detectors 34 and 40.
And a mask 11 based on the detected values.
The positional relationship between the sample and the sample 38 is calculated. Meanwhile, mask 1
The positional relationship between 2 and the sample 38 is calculated by the control device 36 using the calculated relative position between the masks 11 and 12 and the position between the mask 11 and the sample 38. Note that the positional relationship between the mask 12 and the sample 38 may be measured, and the positional relationship between the mask 11 and the sample 38 may be calculated by the control device.

Further, the positional relationship between the divided masks 11 and 12 and the mark 5 provided on the mask stage 4 and the positional relationship between the mark 5 and the sample 38 are measured, and based on the measured values. The positional relationship between the divided masks 11 and 12 and the sample 38 may be calculated. When the masks 11 and 12 are fixed to the stage 4 using a holder, the mark 5 may be provided on the holder.

FIG. 3 is a diagram showing a procedure for scanning a charged beam. The transfer operation of a mask pattern will be described with reference to FIGS. 3 and 2. FIG. FIG. 3A shows the case of the mask according to the present embodiment, and FIG. 3B shows the case of the conventional mask. First, the case of FIG. 3A will be described. In this case, the masks 11 and 12 are arranged along the continuous movement direction of the stage 4, and the charged beam is scanned as a path B. That is, the masks 11 and 1
While continuously moving the stage 4 on which the sample 2 is mounted in the -x direction and the stage 37 on which the sample 38 is mounted in the x direction, the charged beam is scanned rightward from the left side of the mask 11 in the figure to pattern the area 2a. Transcribe When the pattern transfer in the area 2a is completed, the pattern in the area 2b is transferred while continuously moving the stages 4 and 37. In addition,
The detailed structure of the regions 2a and 2b is the same as that of the region 2a in FIG. 5B described above, and the detailed scanning path of the charged beam 31 in the regions 2a and 2b is also the same. At this time, the charged beam 31 is deflected by the deflector 32 in the y direction in FIG. In the following description, a detailed scanning path of the charged beam 31 in the regions 2c to 2h is omitted.

When the pattern transfer in the area 2b is completed, the movement of the stages 4 and 37 is stopped, and the stages 4 and 37 are moved stepwise in the -y direction and the y direction by a predetermined amount. Next, the pattern transfer of the area 2c and the area 2d is performed while the stage 4 is continuously moved in the x direction and the stage 37 is continuously moved in the −x direction. By repeating the same operation, the masks 11, 1
All the patterns formed in the regions 2a to 2h
Transfer onto 8 At this time, as can be seen from the figure, the reversal of the moving direction of the stage 4 is performed three times.

When the mask 12 is fixed to the stage 4 while being inclined with respect to the mask 11, the deflectors 32 and 46 charge the data by using the data on the positional relationship between the mask 11 and the mask 12 obtained at the time of alignment. Exposure is performed while correcting the deflection of the beam 31.

On the other hand, in the case of FIG.
2h are arranged side by side in the y direction, and the charged beam is scanned as in the path C. That is, the pattern of the area 2a is transferred while the stage 4 is continuously moved in the -x direction and the stage 37 is continuously moved in the x direction. When the pattern transfer of the area 2a is completed, the stages 4 and 37 are stopped and then the -y direction and the The step is moved by a predetermined amount in the y direction. Next, the stage 4 is moved in the x direction,
The pattern of the area 2b is transferred while continuously moving in the x direction. When the pattern transfer of the area 2b is completed, the stages 4 and 37 are stopped and then step-moved by a predetermined amount in the −y direction and the y direction, and again the area 2c is continuously moved in the −x direction and the x direction again. Is transferred. By repeating the same operation, mask 2
All the patterns formed in the regions 2a to 2h
Transfer to the top. At this time, the movement direction of the stage 4 is reversed seven times.

According to the above-described embodiment, the following effects can be obtained. (1) Since the chip pattern 1 is formed by being divided into a plurality of masks 11 and 12, the size of one mask is smaller than that of the conventional mask 2. As a result, when forming the mask, the mask can be manufactured using a smaller silicon wafer. (2) Since the plurality of masks 11 and 12 are arranged along the continuous movement direction of the stage 4, the number of inversions of the stage 4 during exposure is smaller than that of the conventional mask 2, and
Throughput can be improved. (3) When aligning the mask and the sample,
One of the plurality of masks 11 and 12, for example, the mask 11
The positional relationship between the mask 12 and the sample 38 is actually measured, and the positional relationship between the mask 12 and the sample 38 is calculated based on the previously measured positional relationship between the mask 11 and the mask 12 and the above-described measured value. Therefore, even if the number of masks increases, an increase in alignment time can be suppressed.

FIG. 4 is a diagram showing a case where the chip pattern 1 is formed by dividing it into four masks. FIG. 4A shows the case where the four masks 21, 22, 23 and 24 are moved along the continuous movement direction of the stage 4. FIG. 4B shows four masks 25, 26, 27, and 28 arranged in two rows along the continuous movement direction. Regions 2a to 2h formed on masks 21 to 28 have the same pattern as the corresponding regions of masks 11 and 12, and alignment marks 21A to 28A are formed on masks 21 to 28 similarly to masks 11 and 12.
Are provided respectively. In the case of FIG. 4A, the charged beam is scanned as shown by a path D, and the number of reversals of the stage 4 is one. On the other hand, in the case of FIG. 4B, the charged beam is scanned as shown by a path E, and the number of inversions is three.

In the correspondence between the embodiment of the invention described above and the elements of the claims, the stage 4 constitutes a mask stage, and the masks 11 and 12 constitute divided masks, respectively. Mask set is configured.

[0024]

As described above, according to the present invention,
Since the mask pattern is divided into a plurality of divided masks and formed on different substrates, the size of each divided mask is reduced, and the substrate can be manufactured using a substrate smaller than before. According to the third aspect of the present invention, since each of the divided masks is arranged along the continuous movement direction of the mask stage, the number of inversions of the mask stage is reduced, and the throughput is improved. According to the fourth and fifth aspects of the present invention, it is possible to suppress an increase in the alignment time due to the charged beam exposure mask set including a plurality of divided masks.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a mask according to the present invention.

FIG. 2 is a schematic diagram of a charged beam exposure apparatus.

FIG. 3 is a diagram showing a scanning procedure of a charged beam, and FIG.
Shows the case of the mask of the present embodiment, and (b) shows the case of the conventional mask.

4A and 4B are diagrams illustrating another example of the mask according to the present embodiment, in which FIG. 4A illustrates a case where the masks are arranged in one row, and FIG. 4B illustrates a case where the masks are arranged in two rows.

5A and 5B are diagrams showing a conventional mask, wherein FIG. 5A is a diagram for explaining division of a chip pattern, and FIG. 5B is a region 2 of FIG.
The enlarged view of a.

FIG. 6 is a view for explaining a stencil mask, and FIG.
Is a plan view of a mask pattern, and (b) is a plan view of a complementary pattern.

[Explanation of symbols]

2a-2h area 4,37 stage 5,11A, 12A, 21A-28A alignment mark 11,12,21-28 mask 34,40 position detector 35,41 mark detector 36 controller 38 sample

Claims (5)

[Claims] 1. A charged beam exposure mask set comprising a plurality of divided masks obtained by dividing a mask pattern into a plurality of parts and forming these divided patterns on different substrates. 2. The charged beam exposure method using a mask set according to claim 1, wherein each of the divided masks is placed on a mask stage of a charged beam exposure apparatus, and at least the mask stage is continuously moved. A charged beam exposure method, comprising sequentially exposing and transferring patterns formed on a plurality of small areas of the divided mask onto a sample. 3. The charged beam exposure method according to claim 2, wherein the plurality of divided masks are arranged on the mask stage along the continuous movement direction. 4. An alignment method for a charged beam exposure apparatus, wherein each of the divided masks according to claim 1 is mounted on a mask stage and a mask pattern is exposed and transferred onto a sample. And measuring a positional relationship between any one of the plurality of divided masks and the sample, and calculating a positional relationship between the other divided masks and the sample based on the measured values. And alignment method. 5. An alignment method for a charged beam exposure apparatus, wherein each of the division masks according to claim 1 is mounted on a mask stage and a mask pattern is exposed and transferred onto a sample. Or, the positional relationship between the holder that fixes the divided mask to the mask stage, and the positional relationship between the mask stage or the holder and the sample are measured, and each of the divided masks is measured based on the measured value. An alignment method comprising calculating a positional relationship with the sample.