JPH08250393A - Charged particle beam lithography method - Google Patents

Abstract

PURPOSE: To realize a method for drawing a charged particle beam in which the influence of the height change of a material or the drift of the beam can be made uniform over a predetermined entire drawing area. CONSTITUTION: The positions of first mark groups M1a to M3a are detected, and the deflecting amplitude, the emitting position shift of an electron beam and the correction data of the deflecting rotation are obtained based on the obtained three mark positions. Then, fields are sequentially drawn according to the flow L1 of a real line from the field F1, drawn to a field Fn, and the first drawing over the entire chip T is finished. Then, the positions of second mark groups M1b to M3b are detected, and correction data are obtained based on the obtained three mark positions. Thereafter, fields are sequentially drawn according to the flow L2 of a broken line from the field Fn, drawn to the field F1, and the second drawing ouer the entire chip T is finished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle beam drawing method for drawing a fine pattern using an electron beam or an ion beam.

[0002]

2. Description of the Related Art In recent years, as the memory capacity of semiconductor memory devices has advanced from 4M to 16M, and further to 64M bits, the density has become high and the accuracy has been high. The beam lithography system is also required to have high accuracy and high speed to meet the demand. By the way, in the direct writing in which the electron beam is directly irradiated onto the wafer to perform the drawing, for example, an alignment mark is provided for each chip, the mark is detected, and the irradiation position shift of the electron beam, the deflection amplitude of the electron beam, Deflection rotation is corrected.

FIG. 1 shows the chip T and three alignment marks M1, M2 and M3. Before drawing the pattern included in the chip T, the electron beam is sequentially scanned at the three alignment marks M1, M2, and M3, and each mark position is detected by a well-known method. If the irradiation position of the electron beam is shifted based on the detected mark position, the position shift is corrected by, for example, correcting the deflection amount of the electron beam.

Further, the deflection amplitude of the electron beam and the deflection rotation are corrected based on each mark position. In addition,
The deflection amplitude is corrected by changing the amplification factor of an amplifier that amplifies the deflection signal of the electron beam, and the deflection rotation is corrected by adding the deflection amount of the electron beam. After completion of such a correction operation, a predetermined pattern is drawn on the chip T. For example, drawing of this pattern is performed for each field in order from the point A to the point B of the chip T.

[0005]

Among the electron beam corrections based on each mark position detection, the deflection amplitude correction is as follows.
The mark positions of M1 to M3 are detected, and the deflection for the electron beam is deflected so that the deflection distance between the marks M1 and M2 and the deflection distance between the marks M1 and M3 become equal to the design value. Adjust the amplification factor of the signal amplifier. However, if the height of the material changes from the point C to the point D in FIG. 1, even if the deflection amplitude is adjusted at the mark portion, the proper deflection amplitude is obtained at the point C close to the mark, The deflection amplitude does not match at the point D far from.

This situation will be described with reference to FIG. FIG. 2 shows a cross section of the material including points C and D, and M shows a mark. When the point D is lower than the point C as shown in the figure, an electron beam deflection amplitude error E occurs,
It becomes impossible to perform accurate drawing.

When the electron beam drifts, the mark positions of the marks M1 to M3 are detected, and after the position correction and the rotation correction are performed, the points T to B on the chip T are detected. When the drawing is started, the electron beam drift does not occur so much in the vicinity of the point A at the start time, and the drawing can be performed with high accuracy, but the accuracy of the drawing deteriorates because the drift amount is large at the last point B in the drawing. Such problems also occur in ion beam drawing.

The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to uniformize the influence of the height change of the material and the drift of the charged particle beam over the entire specific drawing region. This is to realize a particle beam drawing method.

[0009]

According to a charged particle beam drawing method based on the invention of claim 1, in a specific drawing area,
Provide a plurality of mark groups each consisting of a plurality of marks,
The mark position of the first mark group of the plurality of mark groups is detected to obtain the correction data of the electron beam, and based on this correction data, from a position close to the first mark group to a specific drawing area The first drawing is performed, then the mark position of another mark group of the plurality of mark groups is detected to obtain the correction data of the electron beam, and based on this correction data, from the position close to the mark group. Drawing is performed in a specific drawing area, and predetermined drawing is performed in the specific drawing area by a plurality of drawing operations.

In the charged particle beam drawing method according to the present invention, a mark group consisting of a plurality of marks is provided in a specific drawing area, and the mark position of the mark group is detected to correct the electron beam correction data. Based on this correction data, the first drawing is performed on the specific drawing area from the position close to the mark group, and then the second drawing is performed in the opposite direction to the first drawing. It is characterized in that predetermined drawing is performed in a specific drawing area by a plurality of drawing operations.

[0011]

According to the charged particle beam drawing method of the first aspect of the present invention, a plurality of mark groups each including a plurality of marks are provided in a specific drawing area, and the first mark group of the plurality of mark groups is provided. Mark position detection is performed to obtain electron beam correction data. Based on this correction data, the first drawing is performed on a specific drawing area from a position close to the first mark group, and then a plurality of The mark position of another mark group in the mark group is detected to obtain electron beam correction data, and based on this correction data, drawing is performed in a specific drawing area from a position close to the mark group, A predetermined drawing is performed in a specific drawing area by the drawing operation of.

According to the charged particle beam drawing method of the present invention, a mark group including a plurality of marks is provided in a specific drawing area, and the mark position of the mark group is detected to correct the electron beam correction data. Based on this correction data, the first drawing is performed on the specific drawing area from the position close to the mark group, and then the second drawing is performed in the opposite direction to the first drawing. , Predetermined drawing is performed in a specific drawing area by a plurality of drawing operations.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 3 shows an example of an electron beam writing system for carrying out the method according to the invention. An electron beam from the electron gun 1 is focused by an electron lens 2 on a drawing material 3 such as a wafer. The material 3 is held by the material holder 4, and the material holder 4 is placed on the moving stage 5.

The irradiation position of the electron beam on the material 3 is determined by the deflection of the electron beam by the positioning deflector 6. Further, the drawing of the material by the electron beam is performed while blanking the electron beam, and therefore the blanker 7 is provided. Reference numeral 8 is a control computer, and drawing pattern data from the control computer 8 is sent to a pattern data transfer circuit 9.

Blanking data is transferred from the transfer circuit 9 to the blanker control circuit 10, and the deflector control circuit 11
Deflection data corresponding to the drawing pattern is transferred to the stage control circuit 12, and stage position data corresponding to the drawing pattern is transferred to the stage control circuit 12. A memory 13 is connected to the computer 8 and stores a drawing program. Secondary electrons generated by irradiating the material 3 with the electron beam are detected by the secondary electron detector 14. The detection signal of the detector 14 is supplied to the control computer 8 via the amplifier 15 and the AD converter 16. The operation of such a configuration will be described below.

First, an embodiment in which the drawing operation is repeated twice on the same chip will be described with reference to FIG. FIG.
Is a chip T on which drawing is performed, a first mark group M1a to M3a provided close to the upper left part of the chip T, and a second mark group M1b provided close to the lower right part of the chip T.
~ M3b are shown. This chip T is virtually divided into fields F1 to Fn.

In drawing such a chip, first of all,
The positions of the mark groups M1a to M3a are detected. That is, the electron beam is irradiated onto the position of the first mark M1a, and the mark portion is scanned in the X and Y directions. The signal detected by the detector 14 along with the scanning of the electron beam at the mark portion is supplied to the control computer 9. The control computer 9 obtains and stores the mark position based on the detection signal.

When the detection of the position of the first mark M1a is completed, the positions of the marks M2a and M3a are subsequently irradiated with an electron beam, and the positions of the respective marks are detected by the same method. It is stored in the computer 9. The computer 9 obtains correction data for the deflection amplitude of the electron beam, the irradiation position shift, and the deflection rotation based on the obtained three mark positions.

The computer 9 is based on this correction data.
Adjusts the amplification factor of the deflection amplifier in the deflector control circuit 11, and performs position shift and correction of rotation for the electron beam deflection signal based on the drawing pattern data. Then, according to the flow L1 indicated by the solid line from the field F1 in FIG.
Drawing is performed up to and the first drawing of the entire chip T is completed. When writing in each field, the stage 5 is moved by the stage control circuit 12 under the control of the computer 9 for each field, and the dose amount of the electron beam is necessary for normal writing (exposure). It is set to 1/2 of the normal dose.

Next, the second drawing operation is performed, but before that, the position detection of the second mark groups M1b to M3b is performed. That is, the electron beam is applied to the position of the first mark M1b, and the mark portion is scanned in the X and Y directions. As the electron beam scans the mark portion, the detector 14
The signal detected at is supplied to the control computer 9. The control computer 9 obtains and stores the mark position based on the detection signal.

After the detection of the position of the first mark M1b is completed, the positions of the marks M2b and M3b are subsequently irradiated with an electron beam, and the position of each mark is detected by the same method. It is stored in the computer 9. The computer 9 obtains correction data for the deflection amplitude of the electron beam, the irradiation position shift, and the deflection rotation based on the obtained three mark positions.

The computer 9 is based on this correction data.
Adjusts the amplification factor of the deflection amplifier in the deflector control circuit 11, and performs position shift and correction of rotation for the electron beam deflection signal based on the drawing pattern data. Thereafter, drawing of each field is executed in order according to the flow L2 of the dotted line from the field Fn of FIG.
Drawing is performed up to and the second drawing of the entire chip T is completed. Of course, also in this case, when drawing each field, the stage 5 is moved by the stage control circuit 12 under the control of the computer 9 for each field, and the dose amount of the electron beam is the normal drawing. It is set to 1/2 of the dose amount required for (exposure).

In this way, a predetermined pattern is drawn by the drawing operation twice on the same chip T. At this time, for example, in the first pattern drawing in the field F1, the first mark groups M1a to M1 at the close positions are formed.
Drawing is performed by performing various corrections based on the correction data obtained by the position detection of 3a. Therefore, the deflection error due to the height displacement of the material is hardly generated, and since the drawing is performed in a short time from the mark position detection time (correction data acquisition time), the influence of the electron beam drift is extremely small. . As a result, drawing is performed with high accuracy.

On the other hand, in the second drawing in the field F1, since the correction data is created using the mark groups M1b to M3b located at the distant positions, the influence of the height displacement of the material is strongly influenced. . Further, since the drawing is performed after a relatively long time has elapsed from the time when the mark is detected, if the electron beam drifts, the influence thereof is relatively large. Therefore, the drawing accuracy of the second time deteriorates. By the highly accurate first drawing and the second drawing performed in a state where the accuracy is relatively deteriorated,
Since a predetermined pattern is drawn, the final drawing accuracy is averaged.

Next, regarding the field Fn located symmetrically to the field F1, since various correction data are obtained by detecting the mark positions at the distant positions in the first drawing, the height displacement of the material is changed. Is strongly affected. In addition, if there is a drift of the electron beam, drawing is performed after a lapse of time from the mark position detection, so the drift deteriorates the accuracy of the electron beam irradiation position.

On the contrary, in the second drawing, the drawing is performed with high accuracy because the drawing is performed by the correction data obtained by the second mark group located at the close position. Since the predetermined pattern drawing is performed by the first drawing performed in such a state that the accuracy is relatively deteriorated and the second drawing with high accuracy, the final pattern is also written for the field Fn. The drawing accuracy is averaged.

As described above, in the drawing of the fields F1 and Fn at both ends of the chip T, the drawing accuracy is similarly averaged by two drawing operations. Although not described in detail, the drawing accuracy of each intermediate field is also averaged by two drawing operations. As a result, it is possible to reduce variations in drawing accuracy over the entire chip.

FIG. 5 is a diagram for explaining the second embodiment. In this embodiment, writing is repeated four times over the entire chip T, but the dose amount of the electron beam in each writing is performed. Is 1/4 of that in the case where exposure is performed by drawing once. Further, in this embodiment, the chip T
Are virtually divided into nine fields F1 to F9, and a mark group consisting of three marks is provided at each of the four corners of the chip.

First, the positions of the first mark groups M1a to M3a are detected to obtain the correction data, and then the field F1 to the field F9 approaching the first mark group is taken along the route L1 shown by the solid line in the figure. Draw. After the drawing up to the field F9 is completed, the second mark group M1b
~ After detecting the position of M3b and obtaining the correction data,
Drawing is performed from the field F9 approaching the second mark group to the field F1 along a path L2 indicated by a dotted line in the figure.

Next, after the positions of the third mark groups M1c to M3c are detected to obtain the correction data, the field F3 approaching the third mark group from the field F7 to the field F7 is shown by a dashed line L3 in FIG. Draw with. After the drawing up to the field F7 is completed, the fourth mark group M1
After detecting the positions of d to M3d and obtaining the correction data, the field F7 to the field F3 approaching the fourth mark group is drawn by the path L4 indicated by the chain double-dashed line in the figure.

As described above, in the embodiment shown in FIG. 5, the pattern in each field is set to the required dose amount by the drawing operation of four times, and the start fields of the four times of drawing are made different, and each of them is made different. Since the correction data at the time of drawing is performed by the mark group close to the start field, the drawing accuracy of each field can be averaged.

The above-mentioned two or four drawing operations are carried out under the control of the computer 9, but the computer 9 performs various controls based on the drawing program stored in the drawing program storage area 13a of the memory 13. Run. In addition to the drawing program storage area 13a, the memory 13 also has a parameter storage area 13b. In this parameter storage area 13b, drawing order parameters and multiple parameters are stored. With such a configuration, when the number of times of drawing is designated, necessary parameters are read out from the multiplex parameter and the drawing order parameter, and the drawing program is created based on this parameter. With this drawing program, the drawing shown in the above-described embodiments of FIGS. 4 and 5 is executed.

FIG. 6 shows another embodiment of the present invention. In this embodiment, the chip T is repeatedly drawn twice. Although the number of times of drawing is the same as that in the embodiment of FIG. 4, in this embodiment, the mark groups M1 to M3 are first detected and the drawing is started from the field F1, and the drawing is performed up to the field F9 via the solid line path L1. To do. afterwards,
Immediately (without performing mark detection), field F9
From the solid line path L1 to the field F1 via the dotted line path L2 which is the reverse of the solid line path L1. According to such drawing, it is not possible to average the error with respect to the height displacement of the material, but it is possible to average the influence with respect to the drift of the electron beam.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, the present invention can be applied to not only an electron beam drawing apparatus but also an ion beam drawing apparatus. Further, although an example of drawing the entire chip has been described, the present invention can be applied to a specific drawing area other than the chip.

[0035]

As described above, in the charged particle beam drawing method according to the invention of claim 1, a plurality of mark groups each including a plurality of marks are provided in a specific drawing area, and a plurality of mark groups are provided. The mark position of the first mark group of the first mark group is detected to obtain the correction data of the electron beam, and based on this correction data, the first drawing is performed on the specific drawing area from the position close to the first mark group. Drawing is performed, then the mark position of another mark group of the plurality of mark groups is detected to obtain electron beam correction data, and based on this correction data, a specific drawing area is started from the position close to the mark group. Drawing is performed on each of the drawing areas, and predetermined drawing is performed on a specific drawing area by a plurality of drawing operations. As a result,
The influence of the height displacement of the material to be drawn and the drift of the charged particle beam can be made uniform over the entire drawing area.

In the charged particle beam drawing method according to the present invention, a mark group consisting of a plurality of marks is provided in a specific drawing area, and the mark position of this mark group is detected to correct the electron beam correction data. Based on this correction data, the first drawing is performed on the specific drawing area from the position close to the mark group, and then the second drawing is performed in the opposite direction to the first drawing. The predetermined drawing is performed in a specific drawing area by a plurality of drawing operations. As a result, the deterioration of the drawing accuracy due to the drift of the charged particle beam can be made uniform over the entire drawing region.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a conventional drawing method.

FIG. 2 is a diagram for explaining a relationship between a change in height of a material to be drawn and a deflection error.

FIG. 3 is a diagram showing an example of an electron beam drawing system for carrying out a drawing method according to the present invention.

FIG. 4 is a diagram for explaining an example of a drawing method according to the present invention.

FIG. 5 is a diagram for explaining an example of a drawing method according to the present invention.

FIG. 6 is a diagram for explaining an example of a drawing method according to the present invention.

[Explanation of symbols]

 1 Electron Gun 2 Electron Lens 3 Material 4 Material Holder 5 Moving Stage 6 Deflector 7 Blanker 8 Control Computer 9 Pattern Data Transfer Circuit 10 Blanker Control Circuit 11 Deflector Control Circuit 12 Stage Control Circuit 13 Memory 14 Secondary Electron Detector 15 Amplifier 16 AD converter

Claims (2)

[Claims] 1. A correction data of an electron beam by providing a plurality of mark groups, each of which is composed of a plurality of marks, with respect to a specific drawing area, and detecting a mark position of a first mark group of the plurality of mark groups. Based on this correction data, the first drawing is performed in a specific drawing area from a position close to the first mark group, and then the mark positions of other mark groups in the plurality of mark groups are obtained. Detection is performed to obtain electron beam correction data, and drawing is performed on a specific drawing area from a position close to the mark group based on the correction data,
A charged particle beam drawing method for performing a predetermined drawing on a specific drawing area by a plurality of drawing operations. 2. A mark group including a plurality of marks is provided in a specific drawing area, the mark position of the mark group is detected to obtain electron beam correction data, and the mark group is formed based on the correction data. The first drawing is performed in a specific drawing area from an approaching position, then the second drawing is performed in the opposite direction to the first drawing, and a predetermined drawing area is specified in a plurality of drawing operations. Charged particle beam drawing method adapted to perform drawing.