JP2010073732A - Evaluating method for charged particle beam drawing device and charged particle beam drawing device - Google Patents

Abstract

An evaluation method of a charged particle beam writing apparatus capable of evaluating a pattern drawn using a charged particle beam and identifying the cause when the desired pattern is not drawn, and a sample having a desired pattern Provided is a charged particle beam drawing apparatus capable of drawing a pattern.
A dummy pattern 102 having the same dimension in the Y direction as the evaluation pattern 101 and a short dimension in the X direction is drawn, and then an evaluation pattern 101 is drawn along the X direction. Similarly, it is possible to specify which operation of the deflector has a problem by drawing patterns having different operations of the deflector and comparing the dimensions of the obtained evaluation patterns.
[Selection] Figure 4

Description

  The present invention relates to a charged particle beam drawing apparatus evaluation method and a charged particle beam drawing apparatus.

  In recent years, as the design rules of semiconductor devices are continually miniaturized and highly accurate, the requirements for dimensional accuracy (CD accuracy) for lithography technology are becoming stricter. In particular, the requirements for masks are very strict.

  In mask drawing, a variable shaping type electron beam drawing apparatus is conventionally used (for example, refer to Patent Document 1). Drawing data in the electron beam drawing apparatus is created by subjecting design data (CAD data) such as a semiconductor integrated circuit designed using a CAD system to processing such as proximity effect correction and figure pattern division. Here, the graphic pattern division processing is performed in units of the maximum shot size defined by the size of the electron beam, and the coordinate position, size, and irradiation time of each divided shot are also set. Then, drawing data is created so that a shot is formed according to the shape and size of the graphic pattern to be drawn. The drawing data is divided into strip-shaped frames (main deflection areas) and further divided into sub-deflection areas. That is, the drawing data of the entire chip has a data hierarchical structure including a plurality of strip-shaped frame data according to the size of the main deflection area and a plurality of sub deflection area units smaller than the main deflection area in the frame. .

  The sub-deflection area is an area where an electron beam is scanned by the sub-deflector at a speed higher than that of the main deflection area, and is generally a minimum drawing unit. When drawing in the sub-deflection area, a shot having a size and shape prepared according to the pattern figure is formed by the shaping deflector. Specifically, after the electron beam emitted from the electron gun is shaped into a rectangular shape by the first aperture, it is projected onto the second aperture by the shaping deflector to change the beam shape and dimensions. . Thereafter, as described above, the light is deflected by the sub-deflector and the main deflector and is irradiated onto the mask placed on the stage.

JP-A-9-293670

  In order to draw a desired pattern on the mask, it is necessary that the electron beam is shaped into a desired size and shape. Therefore, conventionally, patterns drawn according to the order indicated by the arrows in FIGS. 11A and 11B are compared to evaluate whether or not the molding is correctly performed. In these drawings, the patterns belonging to the first regions 801 and 901 have the same shape and dimensions, but the patterns belonging to the second regions 802 and 902 are patterns belonging to the first regions 801 and 901. The dimension in the Y direction is shorter.

  In FIG. 11A, the electron beam first shots the first pattern 803 belonging to the first region 801 and then the second pattern 804 along the + X direction. When the same operation is repeated and all the patterns in the first region 801 are shot, the shaping deflector deflects the first aperture image in the −Y direction. Thereafter, the electron beam is shot in order in the second region 802 from the left in the drawing along the + X direction.

  On the other hand, in FIG. 11B, the electron beam first shots the first pattern 903 belonging to the first region 901, and then shots the first pattern 904 belonging to the second region 902. . Next, the second pattern 905 is shot after returning to the first area 901 and then the second pattern 906 belonging to the second area 902 is shot. By repeating this, all patterns in the first area 901 and the second area 902 are shot.

  According to the drawing method of FIG. 11A, while the electron beam is drawing in the first region 801, the sub deflector is constant in that the electron beam is scanned in the + X direction, and the shaping deflection is performed. There is almost no change in the operation of the vessel. On the other hand, in the drawing method of FIG. 11B, when moving from the first pattern 903 in the first area 901 to the first pattern 904 in the second area 902, the shaping deflector The first aperture image is deflected in the −Y direction, and the sub deflector scans the electron beam in the + Y direction (hereinafter referred to as operation A). Further, when moving from the first pattern 904 of the second region 902 to the second pattern 905 of the first region 901, the shaping deflector deflects the first aperture image in the + Y direction, The sub-deflector scans the electron beam in the direction of 45 degrees obliquely (hereinafter referred to as operation B).

  By comparing each drawing pattern of FIG. 11 (a) and FIG. 11 (b), the operation of the deflector is hardly changed as shown in FIG. 11 (a), and the deflector as shown in FIG. 11 (b). It is possible to compare the dimensional accuracy with the case of frequently changing the operation. Here, when the dimensional accuracy of FIG. 11B is reduced with respect to the dimensional accuracy of FIG. 11A, it is understood that there is a problem in at least one of the operation A and the operation B. However, when only one of the operations A and B has a problem, it has not been possible to identify which operation has the problem. For example, if there is a place where the dimensional accuracy is inferior, it is discriminated whether this is due to a decrease in the dimensional accuracy of one shot or due to a shift in the irradiation position of the electron beam. I couldn't. Further, in actual drawing, there are many operations other than the operations A and B, and even if there is a problem with these operations, it is detected in the evaluation based on the drawing patterns in FIGS. 11A and 11B. could not.

  The present invention has been made in view of these points. That is, an object of the present invention is to provide an evaluation method for a charged particle beam drawing apparatus that can evaluate a pattern drawn using a charged particle beam and identify the cause when a desired pattern is not drawn. It is to provide.

  Another object of the present invention is to provide a charged particle beam drawing apparatus capable of drawing a desired pattern on a sample.

According to a first aspect of the present invention, a charged particle beam transmitted through the first aperture is deflected by a shaping deflector to form an image on the second aperture, and the charged particle beam transmitted through the second aperture is An evaluation method of a charged particle beam drawing apparatus that draws a pattern on a sample surface by deflecting with a sub-deflector,
Immediately after drawing the first dummy pattern, the first aperture image of the first dummy pattern is deflected in the X direction by the shaping deflector, and the obtained second aperture image is X by the sub deflector. Drawing a first evaluation pattern that is deflected in the direction and having the same dimension in the Y direction as the first dummy pattern but having a different dimension in the X direction, and measuring the dimension of the first evaluation pattern; ,
Immediately after drawing the second dummy pattern, the first aperture image of the second dummy pattern is deflected in the X direction by the shaping deflector, and the obtained second aperture image is Y by the sub deflector. Drawing a second evaluation pattern that is deflected in the direction and having the same dimension in the Y direction as the second dummy pattern but having a different dimension in the X direction, and measuring the dimension of the second evaluation pattern; ,
Immediately after drawing the third dummy pattern, the first aperture image of the third dummy pattern is deflected in the Y direction by the shaping deflector, and the obtained second aperture image is X by the sub deflector. Drawing a third evaluation pattern that is deflected in the direction and having the same dimension in the X direction as the third dummy pattern but different in the Y direction, and measuring the dimension of the third evaluation pattern; ,
Immediately after drawing the fourth dummy pattern, the first aperture image of the fourth dummy pattern is deflected in the Y direction by the shaping deflector, and the obtained second aperture image is Y by the sub deflector. Deflecting in the direction, drawing a fourth evaluation pattern having the same dimension in the X direction as the fourth dummy pattern but different in the Y direction, and measuring the dimension of the fourth evaluation pattern; ,
The dimensions of the first to fourth evaluation patterns are compared to evaluate the deflection operation of the shaping deflector and the sub deflector.
The X direction includes both + X direction and -X direction, and the Y direction includes both + Y direction and -Y direction.

In the evaluation method of the charged particle beam drawing apparatus of the present invention, immediately after drawing the fifth dummy pattern, the first aperture image of the fifth dummy pattern is +45 degrees direction and -45 degrees direction by the shaping deflector. The second aperture image obtained by deflecting in any of the +135 degree direction and the −135 degree direction is selected from the +45 degree direction, the −45 degree direction, the +135 degree direction, and the −135 degree direction by the sub deflector. And drawing a fifth evaluation pattern similar to the fifth dummy pattern and measuring the dimension of the fifth evaluation pattern,
It is preferable to evaluate the deflection operations of the shaping deflector and the sub deflector by comparing the dimensions of the first to fifth evaluation patterns.

  In the evaluation method of the charged particle beam drawing apparatus of the present invention, the evaluation pattern in each of the steps is prepared by drawing one pattern and a pattern drawn by a plurality of shots. It is preferable to evaluate the deflection operation of the sub-deflector and the auxiliary deflector.

  In the evaluation method of the charged particle beam drawing apparatus of the present invention, a systematic error common to the evaluation patterns drawn in the respective steps is obtained, and data obtained by subtracting the systematic error from the dimensions of the evaluation patterns is compared. It is preferable to evaluate deflection operations of the shaping deflector and the sub-deflector.

According to a second aspect of the present invention, a charge for drawing a predetermined pattern on a sample by controlling the shape and irradiation position of the charged particle beam by a shaping deflector and a sub deflector arranged on the optical path of the charged particle beam. A particle beam drawing apparatus,
Means for determining a relationship between a specific deflection operation of the shaping deflector and the sub-deflector and a deviation amount of the deflection amount;
Means for predicting the deflection operation of the shaping deflector and the sub-deflector from the pattern drawing data;
Means for calculating a correction value of a deflection amount for a specific deflection operation.

  According to the first aspect of the present invention, when a desired pattern is not drawn, the cause can be specified.

  According to the 2nd aspect of this invention, the charged particle beam drawing apparatus which can draw a desired pattern on a sample is provided.

  FIG. 1 is a configuration diagram of an electron beam drawing apparatus according to the present embodiment.

  In FIG. 1, a stage 3 on which a mask 2 is installed is provided in a sample chamber 1 of an electron beam drawing apparatus. The stage 3 is driven by the stage drive circuit 4 in the X direction (left and right direction on the paper surface) and the Y direction (vertical direction on the paper surface). The moving position of the stage 3 is measured by a position circuit 5 using a laser length meter or the like.

  An electron beam optical system 10 is installed above the sample chamber 1. The optical system 10 includes an electron gun 6, various lenses 7, 8, 9, 11, 12, a blanking deflector 13, a shaping deflector 14, a beam scanning main deflector 15, and a beam scanning sub deflector. 16 and two beam shaping apertures 17, 18 and the like.

  FIG. 2 is an explanatory diagram of a drawing method using an electron beam. As shown in this figure, the pattern 51 drawn on the mask 2 is divided into strip-shaped frame regions 52. Drawing with the electron beam 54 is performed for each frame region 52 while the stage 3 continuously moves in one direction (for example, the X direction). The frame area 52 is further divided into sub-deflection areas 53, and the electron beam 54 draws only necessary portions in the sub-deflection areas 53. The frame area 52 is a strip-shaped drawing area determined by the deflection width of the main deflector 15, and the sub-deflection area 53 is a unit drawing area determined by the deflection width of the sub-deflector 16.

  Positioning of the reference position of the sub deflection area is performed by the main deflector 15, and drawing in the sub deflection area 53 is controlled by the sub deflector 16. That is, the main deflector 15 positions the electron beam 54 in a predetermined sub-deflection region 53, and the sub-deflector 16 determines the drawing position in the sub-deflection region 53. Further, the shape and size of the electron beam 54 are determined by the shaping deflector 14 and the beam shaping apertures 17 and 18. Then, the sub-deflection area 53 is drawn while continuously moving the stage 3 in one direction. When drawing of one sub-deflection area 53 is completed, the next sub-deflection area 53 is drawn. When drawing of all the sub-deflection areas 53 in the frame area 52 is completed, the stage 3 is stepped in a direction orthogonal to the direction in which the stage 3 is continuously moved (for example, the Y direction). Thereafter, the same processing is repeated, and the frame area 52 is sequentially drawn.

  In FIG. 1, the drawing data of the mask 2 is stored in the magnetic disk 20 which is a storage medium. The drawing data read from the magnetic disk 20 is temporarily stored in the pattern memory 21 for each frame area 52. The pattern data for each frame area 52 stored in the pattern memory 21, that is, the frame information composed of the drawing position, the drawing graphic data, etc. is sent to the pattern data decoder 22 and the drawing data decoder 23 which are data analysis units.

  Information from the pattern data decoder 22 is sent to a blanking circuit 24 and a beam shaper driver 25. Specifically, blanking data based on the data is created by the pattern data decoder 22 and sent to the blanking circuit 24. Desired beam size data is also created and sent to the beam shaper driver 25. Then, a predetermined deflection signal is applied from the beam shaper driver 25 to the shaping deflector 14 of the electron optical system 10 to control the size of the electron beam 54.

  The deflection control unit 30 in FIG. 1 is connected to a settling time determination unit 29, the settling time determination unit 29 is connected to a sub deflection region deflection amount calculation unit 28, and the sub deflection region deflection amount calculation unit 28 is a pattern data decoder. 22 is connected. The deflection control unit 30 is connected to the blanking circuit 24, the beam shaper driver 25, the main deflector driver 26, and the sub deflector driver 27.

  The output of the drawing data decoder 23 is sent to the main deflector driver 26 and the sub deflector driver 27. Then, a predetermined deflection signal is applied from the main deflector driver 26 to the main deflection unit 15 of the electron optical system 10, and the electron beam 54 is deflected and scanned to a predetermined main deflection position. Further, a predetermined sub deflection signal is applied from the sub deflector driver 27 to the sub deflector 16, and drawing in the sub deflection region 53 is performed.

  Next, a drawing method by the electron beam drawing apparatus will be described.

  First, the mask 2 is placed on the stage 3 in the sample chamber 1. Next, the position of the stage 3 is detected by the position circuit 5, and the stage 3 is moved to a position where drawing can be performed by the stage drive circuit 4 based on a signal from the control computer 19.

  Next, an electron beam 54 is emitted from the electron gun 6. The emitted electron beam 54 is collected by the illumination lens 7. Then, the blanking deflector 13 performs an operation for irradiating the mask 2 with the electron beam 54.

  The electron beam 54 incident on the first aperture 17 passes through the opening of the first aperture 17 and is then deflected by the shaping deflector 14 controlled by the beam shaper driver 25. And it passes through the opening part provided in the 2nd aperture 18, and becomes a beam shape which has a desired shape and a dimension. This beam shape is a drawing unit of the electron beam 54 applied to the mask 2.

  The electron beam 54 is shaped into a beam shape and then reduced by the reduction lens 11. The irradiation position of the electron beam 54 on the mask 2 is controlled by the main deflector 15 controlled by the main deflector driver 26 and the sub deflector 16 controlled by the sub deflector driver 27. The main deflector 15 positions the electron beam 54 in the sub deflection region 53 on the mask 2. The sub deflector 16 positions the drawing position in the sub deflection region 53.

  Drawing with the electron beam 54 on the mask 2 is performed by scanning the electron beam 54 while moving the stage 3 in one direction. Specifically, the pattern is drawn in each sub deflection region 53 while moving the stage 3 in one direction. After all the sub-deflection areas 53 in one frame area 52 have been drawn, the stage 3 is moved to a new frame area 52 and drawn similarly.

  After drawing all the frame regions 52 of the mask 2 as described above, the drawing is replaced with a new mask and drawing by the same method as described above is repeated.

  Next, drawing control by the control computer 19 will be described.

  The control computer 19 reads the mask drawing data recorded on the magnetic disk 20 in the storage medium. The read drawing data is temporarily stored in the pattern memory 21 for each frame area 52.

  Drawing data for each frame area 52 stored in the pattern memory 21, that is, frame information composed of drawing positions, drawing graphic data, and the like is transmitted via a pattern data decoder 22 and a drawing data decoder 23 which are data analysis units. It is sent to the sub deflection area deflection amount calculation unit 28, the blanking circuit 24, the beam shaper driver 25, the main deflector driver 26, and the sub deflector driver 27.

  The pattern data decoder 22 generates blanking data based on the drawing data and sends it to the blanking circuit 24. Further, desired beam shape data is created based on the drawing data and is sent to the sub deflection region deflection amount calculation unit 28 and the beam shaper driver 25.

  The sub deflection region deflection amount calculation unit 28 calculates the deflection amount (movement distance) of the electron beam for each shot in the sub deflection region 53 from the beam shape data created by the pattern data decoder 22. The calculated information is sent to the settling time determination unit 29, and the settling time corresponding to the movement distance by the sub deflection is determined.

  The settling time determined by the settling time determination unit 29 is sent to the deflection control unit 30, and then the deflection control unit 30 measures the blanking circuit 24, the beam shaper driver 25, It is appropriately sent to either the deflector driver 26 or the sub deflector driver 27.

  In the beam shaper driver 25, a predetermined deflection signal is applied to the shaping deflector 14 of the optical system 10, and the shape and size of the electron beam 54 are controlled.

  The drawing data decoder 23 generates positioning data for the sub deflection region 53 based on the drawing data, and this data is sent to the main deflector driver 26. Next, a predetermined deflection signal is applied from the main deflector driver 26 to the main deflector 15, and the electron beam 54 is deflected and scanned to a predetermined position in the sub deflection region 53.

  The drawing data decoder 23 generates a control signal for scanning the sub deflector 16 based on the drawing data. After the control signal is sent to the sub deflector driver 27, a predetermined sub deflection signal is applied from the sub deflector driver 27 to the sub deflector 16. Drawing in the sub deflection region 53 is performed by repeatedly irradiating the electron beam 54 after the settling time has elapsed.

  Next, a method for evaluating the drawn pattern and examining whether or not the electron beam has been formed into a desired shape and size and irradiated to a desired position will be described.

  The deflection direction and the deflection amount due to the shaping deflection are uniquely determined by the shape of the pattern drawn immediately before and the shape of the pattern drawn from now on. For example, as shown in FIG. 3A, assume that the dimension in the X direction of the rectangular pattern drawn immediately before is a and the dimension in the Y direction is b. Then, as shown in FIG. 3B, it is assumed that the rectangular pattern to be drawn now has a dimension in the X direction of (a + Δx) and a dimension in the Y direction of b. In this case, the shaping deflector only needs to horizontally move the first aperture image of the pattern drawn immediately before by Δx in the + X direction. Here, if the pattern drawn immediately before is used as a dummy pattern and the pattern to be drawn from now on is used as an evaluation pattern, a certain fixed operation is performed on both the shaping deflector and the sub-deflector immediately before drawing the evaluation pattern. be able to. By preparing a plurality of types of these constant operations and evaluating them in combination, it is possible to identify which deflector is causing the problem. The specific method will be described below.

  FIG. 4 is an example of an evaluation pattern in the present embodiment. This evaluation pattern is characterized in that a dummy pattern 102 having the same dimension in the Y direction and a short dimension in the X direction is drawn immediately before the evaluation pattern 101 is drawn. In the present embodiment, the dummy pattern 102 having the same dimension in the Y direction and a long dimension in the X direction may be rendered immediately before the evaluation pattern 101 is rendered.

  When drawing the evaluation pattern of FIG. 4, the electron beam first draws the first dummy pattern 102 belonging to the first region 103. Next, the shaping deflector deflects the first aperture image in the + X direction, and the sub deflector deflects the second aperture image in the + X direction to draw the first evaluation pattern 101. Thereafter, the shaping deflector deflects the first aperture image in the −X direction, and the sub deflector deflects the second aperture image in the + X direction to draw the second dummy pattern 102. Thereafter, the above operation is repeated to draw all the patterns in the first area 103.

  Next, an electron beam is scanned by the sub deflector to draw a pattern in the second region 104. The drawing method is the same as in the case of the first region 103.

  In all the evaluation patterns drawn by repeating the above operation, the operation of the deflector immediately before the drawing is uniform. That is, the shaping deflector deflects the first aperture image in the + X direction, and the sub deflector deflects the second aperture image in the + X direction. This is because the dummy pattern is drawn immediately before any of the evaluation patterns, and the deflection direction and the deflection amount of the deflector depend on the shape of the pattern drawn immediately before and the shape of the pattern drawn from now on. This is because it is uniquely determined.

  FIG. 5 is another example of an evaluation pattern in the present embodiment. In this evaluation pattern, a dummy pattern 202 having the same Y-direction dimension and a short X-direction dimension is drawn immediately before the evaluation pattern 201 is drawn, as in FIG. In this embodiment, a dummy pattern 202 having the same dimension in the Y direction and a long dimension in the X direction may be drawn immediately before the evaluation pattern 201 is drawn.

  When drawing the evaluation pattern of FIG. 5, the electron beam first draws the first dummy pattern 202 belonging to the first region 203. Next, the shaping deflector deflects the first aperture image in the + X direction, and the sub deflector deflects the second aperture image in the + Y direction to draw the first evaluation pattern 201. Thereafter, the shaping deflector deflects the first aperture image in the −X direction, and the sub deflector deflects the second aperture image in the + Y direction, thereby drawing the second dummy pattern 202. Then, the above operation is repeated to draw all the patterns in the first area 203.

  Next, after the electron beam is scanned in the −Y direction by the sub deflector, the pattern in the second region 204 is drawn. The drawing method is the same as in the case of the first region 203.

  In all the evaluation patterns drawn by repeating the above operation, the operation of the deflector immediately before the drawing is uniform as in FIG. That is, after drawing the dummy pattern, the shaping deflector deflects the first aperture image in the + X direction, and the sub deflector deflects the second aperture image in the + Y direction, thereby drawing the evaluation pattern.

  FIG. 6 is another example of the evaluation pattern in the present embodiment. In this evaluation pattern, immediately before the evaluation pattern 301 is drawn, a dummy pattern 302 having the same dimension in the X direction and a short dimension in the Y direction is drawn. In the present embodiment, immediately before the evaluation pattern 301 is drawn, a dummy pattern 302 having the same dimension in the X direction and a long dimension in the Y direction may be drawn.

  When the evaluation pattern shown in FIG. 6 is drawn, the electron beam first draws the first dummy pattern 302 belonging to the first region 303. Next, the shaping deflector deflects the first aperture image in the + Y direction, and the sub deflector deflects the second aperture image in the + X direction to draw the first evaluation pattern 301. Thereafter, the shaping deflector deflects the first aperture image in the −Y direction, and the sub deflector deflects the second aperture image in the + X direction to draw the second dummy pattern 302. Then, all the patterns in the first region 303 are drawn by repeating the above operation.

  Next, after the electron beam is scanned in the −X direction by the sub deflector, the pattern in the second region 304 is drawn. The drawing method is the same as in the case of the first area 303.

  In all the evaluation patterns drawn by repeating the above operation, the operation of the deflector immediately before the drawing is uniform as in FIGS. That is, after drawing the dummy pattern, the shaping deflector deflects the first aperture image in the + Y direction, and the sub deflector deflects the second aperture image in the + X direction to draw the evaluation pattern.

  FIG. 7 is also another example of the evaluation pattern in the present embodiment. In this evaluation pattern, immediately before the evaluation pattern 401 is drawn, a dummy pattern 402 having the same dimension in the X direction and a short dimension in the Y direction is drawn. In this embodiment, a dummy pattern 402 having the same dimension in the X direction and a long dimension in the Y direction may be drawn immediately before the evaluation pattern 401 is drawn.

  When drawing the evaluation pattern of FIG. 7, the electron beam first draws the first dummy pattern 402 belonging to the first region 403. Next, the shaping deflector deflects the first aperture image in the + Y direction, and the sub deflector deflects the second aperture image in the + Y direction, thereby drawing the first evaluation pattern 401. Thereafter, the shaping deflector deflects the first aperture image in the −Y direction, and the sub deflector deflects the second aperture image in the + Y direction to draw the second dummy pattern 402. Then, all the patterns in the first area 403 are drawn by repeating the above operation.

  Next, after the electron beam is scanned in the −Y direction by the sub deflector, the pattern in the second region 404 is drawn. The drawing method is the same as in the case of the first area 403.

  In all the evaluation patterns drawn by repeating the above operation, the operation of the deflector immediately before the drawing is uniform as in FIGS. That is, after drawing the dummy pattern, the shaping deflector deflects the first aperture image in the + Y direction, and the sub deflector deflects the second aperture image in the + Y direction, thereby drawing the evaluation pattern.

  In order to check whether or not the electron beam is shaped into a desired shape and size and irradiated at a desired position, all the patterns in FIGS. 4 to 7 are drawn, and a CD (critical dimension of pattern) of each pattern in the X direction is drawn. size) and the CD in the Y direction, and the position of each pattern is also examined, and the results should be comprehensively judged.

  For example, it is assumed that the pattern of FIG. 4 is not drawn with a desired dimension, but the patterns of FIGS. 5 to 7 are all drawn with a desired dimension. In this case, there is a problem with the operation when the electron beam is deflected in the X direction by the (1) shaping deflector and deflected in the X direction by the sub-deflector, but other operations, namely (2) the shaping deflector. To deflect in the X direction, and to deflect in the Y direction by the sub-deflector, (3) to deflect in the Y direction by the shaping deflector, and to deflect in the X direction by the sub-deflector, and (4) Y by the shaping deflector. It can be estimated that there is no problem in the operation of deflecting in the direction and deflecting in the Y direction by the sub deflector.

  Further, it is assumed that the pattern of FIG. 5 is not drawn with a desired dimension, but the patterns of FIGS. 4, 6, and 7 are all drawn with a desired dimension. In this case, there is a problem in the operation of (1) deflecting the electron beam in the X direction by the shaping deflector and deflecting it in the Y direction by the sub-deflector, but other operations, that is, (2) X by the shaping deflector. Operation when deflecting in the direction and deflecting in the X direction by the sub-deflector, (3) operation by deflecting in the Y direction by the shaping deflector and deflecting in the X direction by the sub-deflector, (4) Y by the shaping deflector It can be estimated that there is no problem in the operation of deflecting in the direction and deflecting in the Y direction by the sub deflector.

  Further, the pattern of FIG. 6 is not drawn with a desired dimension, but the patterns of FIGS. 4, 5 and 7 are all drawn with a desired dimension. In this case, there is a problem in the operation of (1) deflecting the electron beam in the Y direction by the shaping deflector and deflecting it in the X direction by the sub-deflector, but other operations, that is, (2) X by the shaping deflector. Operation when deflecting in the direction and deflecting in the X direction by the sub deflector, (3) operation by deflecting in the X direction by the shaping deflector and deflecting in the Y direction by the sub deflector, and (4) Y by the shaping deflector. It can be estimated that there is no problem in the operation of deflecting in the direction and deflecting in the Y direction by the sub deflector.

  Furthermore, although the pattern of FIG. 7 is not drawn with a desired dimension, it is assumed that all of the patterns of FIGS. 4 to 6 are drawn with a desired dimension. In this case, there is a problem in the operation of (1) deflecting the electron beam in the Y direction by the shaping deflector and deflecting it in the Y direction by the sub-deflector, but other operations, that is, (2) X by the shaping deflector. Operation when deflecting in the direction and deflecting in the X direction by the sub deflector, (3) operation by deflecting in the X direction by the shaping deflector and deflecting in the Y direction by the sub deflector, and (4) Y by the shaping deflector. It can be estimated that there is no problem in the operation of deflecting in the direction and deflecting in the X direction by the sub deflector.

  4 and 5 are not drawn with desired dimensions, but the patterns shown in FIGS. 6 and 7 are both drawn with desired dimensions. In this case, the electron beam is (1) deflected in the X direction by the shaping deflector and deflected in the X direction by the sub deflector, and (2) is deflected in the X direction by the shaping deflector. Thus, there is a problem with the operation of deflecting in the Y direction. On the other hand, other operations, that is, (3) the operation of deflecting the electron beam in the Y direction by the shaping deflector and the deflection in the X direction by the sub-deflector, and (4) the deflection of the electron beam in the Y direction by the shaping deflector. There is no problem with the operation of deflecting in the Y direction by the deflector. From the above, it can be estimated that there is a problem in the operation of deflecting in the X direction by the shaping deflector.

  6 and 7 are not drawn with desired dimensions, but the patterns shown in FIGS. 4 and 5 are both drawn with desired dimensions. In this case, the electron beam is (1) deflected in the Y direction by the shaping deflector and deflected in the X direction by the sub-deflector, and (2) deflected in the Y direction by the shaping deflector and Y by the sub-deflector. There is a problem with the operation of deflecting in the direction. On the other hand, other operations, that is, (3) an operation in which the electron beam is deflected in the X direction by the shaping deflector and deflected in the X direction by the sub deflector, and (4) the electron beam is deflected in the X direction by the shaping deflector. There is no problem with the operation of deflecting in the Y direction by the sub deflector. From the above, it can be inferred that there is a problem in the operation of deflecting in the Y direction by the shaping deflector.

  As described above, in this embodiment, all the patterns in FIGS. 4 to 7 are drawn, the dimensions of each evaluation pattern are measured, and whether each evaluation pattern is formed in a desired dimension at a desired position. Find out. Then, by comprehensively judging the result, it is possible to identify which operation of the deflector has a problem, so that it is sufficient to feed back to the electron beam drawing apparatus and perform correction according to the operation.

  Specifically, in the electron beam drawing apparatus of FIG. 1, measured data is stored in the magnetic disk 20, read by the control computer 19, and sent to the correlation calculation unit 32 for the deflection operation and the deviation amount. Here, the relationship between the specific operation of the shaping deflector and the sub deflector and the deviation amount of the deflection amount is required. Further, based on the drawing data read from the magnetic disk 20, the deflection operation predicting unit 31 predicts the deflection operation of the shaping deflector and the sub deflector in the actual drawing pattern. Next, each data of the deflection operation / deviation amount correlation calculation unit 32 and the deflection operation prediction unit 31 is sent to the deflection amount correction value calculation unit 33 to calculate a deflection amount correction value for a specific deflection operation. Thereafter, this data is sent to the deflection control unit 30 to correct the deflection amount of the shaping deflector 14 and / or the sub deflector 16.

  Further, in the present embodiment, the evaluation result may be comprehensively determined to identify which operation of the deflector is causing a problem, and the part at that location may be adjusted or replaced. In this case, the same evaluation is performed again after adjustment or replacement, and if there is no problem, the pattern is drawn on the mask instead of the evaluation substrate. Furthermore, when the evaluation method of the present embodiment is applied to the inspection before shipment of the electron beam lithography apparatus, the same evaluation is performed again after adjusting or replacing the parts where the problem occurs. If not, the electron beam drawing apparatus can be shipped.

  Specifically, the drawn pattern can be evaluated as follows.

  First, as a reference, drawing is performed while keeping the shape and dimensions of the electron beam constant without changing the operation of the shaping deflector, and the CD variation (3σ) is obtained. At this time, the CD measurement may be performed at a plurality of locations in the same mask, or may be performed at the same location by drawing on a plurality of masks. Next, the patterns of FIGS. 4 to 7 are drawn, and the CD of each pattern is measured. For example, the reference CD variation is in the range of 1.4 nm to 2.0 nm, the pattern variation in FIG. 4 is 1.6 nm (3σ), and the pattern variation in FIG. 5 is 2.4 nm (3σ). To do. In this case, since the variation of the pattern in FIG. 4 is within the reference error range, it is determined that the pattern is normal, that is, the pattern is formed with a desired dimension. On the other hand, since the variation of the pattern in FIG. 5 is outside the reference error range, it is determined that there is an abnormality, that is, the pattern is not formed with a predetermined dimension. The same applies to the patterns of FIGS.

  In the present embodiment, it is preferable to evaluate a pattern as shown in FIG. 8 in addition to the patterns of FIGS. Specifically, a dummy pattern similar to the evaluation pattern is drawn, and then the evaluation pattern is drawn in the direction of 45 degrees from the dummy pattern, and then the dimension of the evaluation pattern is measured. And it is preferable to evaluate together with the result of FIGS.

  In FIG. 8, immediately before the evaluation pattern 701 is drawn, a dummy pattern 702 similar to the evaluation pattern 701 is drawn.

  When drawing the evaluation pattern shown in FIG. 8, the electron beam first draws the first dummy pattern 702 belonging to the first region 703. Next, the shaping deflector deflects the first aperture image in the +45 degree direction, and the sub deflector also deflects the second aperture image in the +45 degree direction to draw the first evaluation pattern 701. Thereafter, the shaping deflector deflects the first aperture image in the −135 degree direction, and the sub deflector deflects the second aperture image in the +135 degree direction to draw the second dummy pattern 702. . Then, the above operation is repeated to draw all the patterns in the first area 703.

  Next, after the electron beam is scanned by the sub deflector, the pattern in the second region 704 is drawn. The drawing method is the same as in the case of the first region 703.

  In all the evaluation patterns drawn by repeating the above operation, the operation of the deflector immediately before the drawing is uniform, as in FIGS. That is, after drawing the dummy pattern, the shaping deflector deflects the first aperture image in the +45 degree direction, and the sub deflector deflects the second aperture image in the +45 degree direction to draw the evaluation pattern. . Note that the deflection direction of the shaping deflector and the sub deflector may be any of +45 degrees, -45 degrees, +135 degrees, and -135 degrees. Further, the deflection directions of the shaping deflector and the sub-deflector may be the same or different.

  By evaluating the patterns shown in FIGS. 4 to 8, in the electron beam lithography system, it is possible to identify which of the eight-pole deflectors arranged around the optical path of the electron beam has a problem in operation. It becomes possible to do. That is, in an electron beam drawing apparatus, a shaping deflector and a sub-deflector configured with four pairs (eight) of electrodes are often used because of a small deflection distortion, a deflection speed, and ease of manufacture. All the operations of these deflectors can be confirmed by evaluating the patterns of FIGS. However, in the present embodiment, the shaping deflector and the sub-deflector may be configured with two pairs (four) of electrodes, in which case, by evaluating the patterns of FIGS. It is possible to identify whether there is a problem in the operation of the deflector.

  In the above example, the case where one evaluation pattern is drawn by one shot has been described. However, in this embodiment, it is preferable that one evaluation pattern is drawn by a plurality of shots and evaluated in combination with the above example. . Thereby, the error originating in the position of each shot can be evaluated together.

  For example, an evaluation pattern as shown in FIG. 9 is prepared and compared with the evaluation pattern of FIG. The pattern in FIG. 9 has the same shape and arrangement as the pattern in FIG. 4, but differs in that the evaluation pattern is formed in one shot in FIG. 4 and is formed in two shots in FIG. That is, in FIG. 9, the electron beam first draws the first dummy pattern 502 belonging to the first region 503. Next, the shaping deflector deflects the first aperture image in the + X direction, and the sub-deflector deflects the second aperture image in the + X direction, and the first pattern 501a of the first evaluation pattern. And then the second pattern 501b is shot. Thereafter, the shaping deflector deflects the first aperture image in the −X direction, and the sub deflector deflects the second aperture image in the + X direction to draw the second dummy pattern 102. After all the patterns in the first region 103 are drawn by repeating the above operation, the sub-deflector scans the electron beam in the −X direction to draw the pattern in the second region 104. After drawing, the dimension in the X direction of the evaluation pattern is measured, and the pattern of FIG. 9 is compared with the pattern of FIG. If the two dimensions do not match, it can be determined that an abnormality has occurred in the operation in the X direction by the sub deflector.

  Also, an evaluation pattern as shown in FIG. 10 is prepared and compared with the evaluation pattern of FIG. The pattern in FIG. 10 has the same shape and arrangement as the pattern in FIG. 5 except that the evaluation pattern is formed in one shot in FIG. 5 and is formed in two shots in FIG. That is, in FIG. 10, the electron beam first draws the first dummy pattern 602 belonging to the first region 603. Next, the shaping deflector deflects the first aperture image in the + X direction, and the sub deflector deflects the second aperture image in the + Y direction, thereby first pattern 601a of the first evaluation pattern. Is shot, and then the second pattern 601b is shot. Thereafter, the shaping deflector deflects the first aperture image in the −X direction, and the sub deflector deflects the second aperture image in the + Y direction to draw the second dummy pattern 602. After all the patterns in the first area 603 are drawn by repeating the above operation, the stage is moved in the −X direction, the electron beam is scanned in the −Y direction by the sub deflector, and the second area is scanned. The pattern in 604 is drawn. After drawing, the dimension in the Y direction of the evaluation pattern is measured, and the pattern of FIG. 10 is compared with the pattern of FIG. If the two dimensions do not match, it can be determined that an abnormality has occurred in the operation in the Y direction by the sub-deflector.

  In the present embodiment, it is preferable to obtain a systematic error common to these patterns after measuring the CD of each evaluation pattern. For example, when CD is measured for a plurality of evaluation patterns in a predetermined area of one substrate, the obtained value shows a predetermined distribution. If the same measurement is performed for each of FIGS. 4 to 8, a CD value having a predetermined distribution can be obtained for each of the evaluation patterns. Therefore, if a systematic error common to each evaluation pattern is obtained and the data obtained by subtracting this value from the CD value is compared, more accurate evaluation can be performed.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, although the electron beam is used in the above embodiment, the present invention is not limited to this, and the present invention can also be applied to cases where other charged particle beams such as an ion beam are used. Further, the shapes of the dummy pattern and the evaluation pattern are not limited to a rectangle, and may be other shapes such as a triangle. A plurality of electron beams whose one shot shape is a triangle are shot into a rectangular shape. A pattern may be formed. Further, in the above embodiment, the case where the evaluation pattern drawn immediately after the dummy pattern is positioned in the + X direction or the + Y direction of the dummy pattern has been described. You may do it.

It is a conceptual diagram which shows the structure of the electron beam drawing apparatus in this Embodiment. It is an example of the electron beam drawing method by this Embodiment. (A) And (b) is a figure which shows the operation | movement of a shaping | molding deflector, and the relationship of a shot shape. It is an example of the pattern for evaluation in this Embodiment. It is an example of the pattern for evaluation in this Embodiment. It is an example of the pattern for evaluation in this Embodiment. It is an example of the pattern for evaluation in this Embodiment. It is an example of the pattern for evaluation in this Embodiment. It is an example of the pattern for evaluation in this Embodiment. It is an example of the pattern for evaluation in this Embodiment. (A) And (b) is a figure which shows the conventional pattern evaluation method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sample chamber 2 Mask 3 Stage 4 Stage drive circuit 5 Position circuit 6 Electron gun 7, 8, 9, 11, 12 Various lenses 10 Optical system 13 Blanking deflector 14 Molding deflector 15 Main deflector 16 Sub deflector 17 First aperture 18 Second aperture 19 Control computer 20 Magnetic disk 21 Pattern memory 22 Pattern data decoder 23 Drawing data decoder 24 Blanking circuit 25 Beam shaper driver 26 Main deflector driver 27 Sub deflector driver 28 Sub deflection area deflection Amount calculation unit 29 Settling time determination unit 30 Deflection control unit 31 Deflection operation prediction unit 32 Deflection operation and deviation amount correlation calculation unit 33 Deflection amount correction value calculation unit 51 Pattern to be drawn 52 Frame region 53 Sub deflection region 54 Electron beam 101 , 201, 301, 401, 7 1 evaluation pattern 102,202,302,402,702 dummy pattern 103,203,303,403,703 first region 104,204,304,404,704 second region

Claims (5)

A charged particle beam that has passed through the first aperture is deflected by a shaping deflector to form an image on the second aperture, and the charged particle beam that has passed through the second aperture is deflected by a sub-deflector to obtain a sample surface. An evaluation method of a charged particle beam drawing apparatus for drawing a pattern on the top,
Immediately after drawing the first dummy pattern, the first aperture image of the first dummy pattern is deflected in the X direction by the shaping deflector, and the obtained second aperture image is X by the sub deflector. Drawing a first evaluation pattern that is deflected in the direction and having the same dimension in the Y direction as the first dummy pattern but having a different dimension in the X direction, and measuring the dimension of the first evaluation pattern; ,
Immediately after drawing the second dummy pattern, the first aperture image of the second dummy pattern is deflected in the X direction by the shaping deflector, and the obtained second aperture image is Y by the sub deflector. Drawing a second evaluation pattern that is deflected in the direction and having the same dimension in the Y direction as the second dummy pattern but having a different dimension in the X direction, and measuring the dimension of the second evaluation pattern; ,
Immediately after drawing the third dummy pattern, the first aperture image of the third dummy pattern is deflected in the Y direction by the shaping deflector, and the obtained second aperture image is X by the sub deflector. Drawing a third evaluation pattern that is deflected in the direction and having the same dimension in the X direction as the third dummy pattern but different in the Y direction, and measuring the dimension of the third evaluation pattern; ,
Immediately after drawing the fourth dummy pattern, the first aperture image of the fourth dummy pattern is deflected in the Y direction by the shaping deflector, and the obtained second aperture image is Y by the sub deflector. Deflecting in the direction, drawing a fourth evaluation pattern having the same dimension in the X direction as the fourth dummy pattern but different in the Y direction, and measuring the dimension of the fourth evaluation pattern; ,
An evaluation method for a charged particle beam drawing apparatus, wherein dimensions of the first to fourth evaluation patterns are compared to evaluate a deflection operation of the shaping deflector and the sub deflector. Immediately after drawing the fifth dummy pattern, the first aperture image of the fifth dummy pattern is placed in any of +45 degree direction, −45 degree direction, +135 degree direction, and −135 degree direction by the shaping deflector. The second aperture image obtained by deflecting is deflected by the sub-deflector in any of +45 degrees, -45 degrees, +135 degrees, and -135 degrees, and similar to the fifth dummy pattern. Drawing a fifth evaluation pattern, and measuring a dimension of the fifth evaluation pattern;
The evaluation of the charged particle beam drawing apparatus according to claim 1, wherein dimensions of the first to fifth evaluation patterns are compared to evaluate a deflection operation of the shaping deflector and the sub deflector. Method.   Prepare the pattern for evaluation in each step drawn with one shot and those drawn with a plurality of shots, and compare them to evaluate the deflection operation of the shaping deflector and the sub-deflector The method for evaluating a charged particle beam drawing apparatus according to claim 1, wherein:   A systematic error common to the evaluation patterns drawn in the respective steps is obtained, and data obtained by subtracting the systematic error from the dimensions of the evaluation patterns are compared, and the deflection operation of the shaping deflector and the sub deflector is performed. The method for evaluating a charged particle beam drawing apparatus according to any one of claims 1 to 3, wherein: A charged particle beam drawing apparatus for drawing a predetermined pattern on a sample by controlling the shape and irradiation position of the charged particle beam by a shaping deflector and a sub deflector arranged on an optical path of the charged particle beam,
Means for determining a relationship between a specific deflection operation of the shaping deflector and the sub-deflector and a deviation amount of the deflection amount;
Means for predicting the deflection operation of the shaping deflector and the sub-deflector from the pattern drawing data;
And a means for calculating a correction value of a deflection amount for a specific deflection operation.

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