JP2010245099A - Method and device for evaluation of pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evaluate CD linearity during pattern drawing, relating to a pattern evaluation method and device. <P>SOLUTION: The pattern evaluation method includes a first drawing step in which a first pattern and a pattern having a width of a first multiple are formed sequentially by single shooting to provide n pieces of patterns, a second drawing step in which, with the first pattern as a reference pattern, shooting the reference pattern is repeated multiple times to provide n pieces of patterns, and a third drawing step in which a pattern with a known pattern width is drawn at any ratio by double shooting to provide n pieces of patterns. In an evaluation means, with the pattern width obtained by a line thickness measuring step during the second drawing step as the reference pattern, the pattern widths obtained by the line thickness measuring steps during first drawing step and third drawing step are compared to evaluate the linearity of drawing pattern. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pattern evaluation method and apparatus, and more particularly to a pattern evaluation method and apparatus for evaluating the linearity of a drawing pattern.

  CD linearity (linearity of line width: hereinafter referred to as CD linearity) is one of the things that express the drawing accuracy of a variable area electron beam drawing apparatus. Here, CD is an abbreviation for Critical Dimension and is a line width. For example, the CD linearity is an item for drawing a pattern in which the target line width (design value) is varied as shown in FIG. 2A and confirming that the difference from the target line width is linear.

  FIG. 3 is an explanatory diagram of linearity of line width. The horizontal axis is the line width design value, and the vertical axis is the actual line width value. The line width can be measured by CD-SEM. When the drawing has linearity, the line width design value and the line width measurement value have a linear relationship as shown in the figure. In the figure, f1 and f2 represent two straight lines having an offset Δ. f1 and f2 indicate that the line width measurement value increases as the line width design value increases. This indicates that the drawing has linearity. The inclinations of the straight lines f1 and f2 can be changed by adjusting the gain amplifier of the shaping deflector. FIG. 4 is a diagram showing the relationship between the design CD and the CD error. The horizontal axis is the CD design value, and the vertical axis is the measurement error. The measurement error is also linear.

  As described above, CD-SEM or the like is used for line width measurement. A measuring apparatus such as a CD-SEM performs calibration of CD linearity using a reference sample, but the CD linearity of the reference sample may be incorrect. The variable area electron beam drawing apparatus can adjust the CD linearity by changing the gain of the amplifier of the shaping deflector.

  Therefore, even when the CD linearity of the CD-SEM is not correct, it is possible to match the CD linearity of the CD-SEM by adjusting the gain of the shaping deflector of the drawing apparatus. Further, even when processes such as baking, development, and etching after drawing affect the CD linearity, the error can be adjusted by the gain of the shaping deflector of the drawing apparatus.

  As a conventional apparatus of this type, in a variable shaped beam evaluation method for evaluating the dimensions of a variable shaped beam used for pattern exposure on a photosensitive material formed on a substrate, a plurality of rectangular patterns 1 having the same dimensions are prepared. At least one draws a rectangular pattern with a single shot, the other is obtained by dividing the pattern with a straight line parallel to one side of the rectangular pattern and drawing with two shots 2 and 3, and developing these For the actual pattern, the pattern dimension in the direction perpendicular to the dividing line was measured using SEM, and the relationship between the measured pattern dimension and the presence / absence of the division or the division position was investigated to improve the dimensional accuracy of the variable shaped beam. The technique to evaluate is known (for example, refer patent document 1).

  In addition, the vertical line and horizontal line pattern formed by sequentially joining the rectangular beams of different lengths and the divided rectangular beam of the same width are combined, and the vertical line and horizontal line formed by sequentially changing the width. A technique for evaluating a pattern by observing the pattern shape is known (see, for example, Patent Document 2).

JP-A-9-186070 (paragraphs 0026 to 0033, FIGS. 9 and 10) Japanese Patent Laid-Open No. 7-50248 (paragraphs 0013 to 0018, FIGS. 2 and 3)

  The drawing accuracy of the variable area electron beam drawing apparatus includes shot division accuracy. The shot division accuracy is an item for dividing a pattern with a uniform target line width into two shots of a plurality of types of line widths and checking the uniformity ((c) of FIG. 2). The pattern of (c) of FIG. 2 shows a case where a pattern having a constant width of 1000 [nm] is shot two times at different ratios. In the figure, the cases of 900: 100, 500: 500, and 100: 900 are shown.

  In the line width measurement in this shot division accuracy, since the target line width is unified, it is possible to evaluate without being influenced by the CD linearity of a measuring apparatus such as a CD-SEM. It is not affected by processes such as development and etching. Therefore, if the CD linearity of the CD-SEM is incorrect, or if the CD linearity changes due to baking, development, etching, etc. after drawing, the CD linearity is adjusted to the measurement result of the CD-SEM by the drawing apparatus. As a result, the CD linearity of the CD-SEM and the shot division accuracy that is not affected by the process may deteriorate.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a pattern evaluation method and apparatus capable of evaluating CD linearity during pattern drawing.

  (1) The invention described in claim 1 is a drawing step on a drawing material in a variable area electron beam apparatus, a process step of developing and etching the material drawn in the drawing step, and a drawing on the drawing material A line width measuring step for measuring the line width, and in order to evaluate the accuracy of the drawing step, the process step, and the line width measuring step, a specific pattern is used as a reference pattern, and a shot of this reference pattern is an integer. It is characterized by using a drawing process of repeating n times to obtain n patterns.

(2) The invention according to claim 2 is a drawing process on the drawing material in the variable area electron beam apparatus, a process step of developing and etching the material drawn in the drawing process, and the drawing material drawn on the drawing material A line width measuring step of measuring a line width, and a first drawing step of sequentially forming a first pattern and a pattern having a width of the first integer multiple in one shot to obtain n patterns ,
The first pattern is used as a reference pattern, and a second drawing process for obtaining n patterns by repeating shots of this reference pattern by an integer multiple, and a pattern having a known pattern width is drawn twice at an arbitrary ratio. A third drawing step for obtaining n patterns, and obtained in the line width measurement step on the basis of the pattern width obtained in the second drawing step obtained in the line width measurement step. Further, the linearity of the drawing pattern is evaluated by comparing the pattern widths obtained in the first drawing step and the third drawing step.

(3) The invention described in claim 3 is characterized in that the first drawing step to the third drawing step are performed by drawing in a blank area of the drawing material.
(4) The invention described in claim 4 is characterized in that the pattern obtained by the second drawing step is measured in the line width measuring step, and the linearity of the process step and the line width measuring step is evaluated. .

  (5) The invention according to claim 5 is a drawing step on a drawing material in a variable area electron beam apparatus, a process step of developing and etching the material drawn in the drawing step, and a drawing on the drawing material A line width measuring step of measuring a line width, and a first drawing step of sequentially forming a first pattern and a pattern having a width of the first integer multiple in one shot to obtain n patterns First pattern is used as a reference pattern, and a second drawing process for obtaining n patterns by repeating shots of this reference pattern by integer multiples, and a pattern whose pattern width is known in advance is drawn twice at an arbitrary ratio. A third drawing step for obtaining n patterns, and obtained in the line width measuring step with reference to the pattern width obtained in the second drawing step obtained in the line width measuring step. The first drawing step By comparing the pattern width obtained by the third rendering process is characterized in that a evaluating means for evaluating the linearity of the drawn pattern.

  (1) According to the first aspect of the present invention, since a plurality of patterns obtained by repeating a shot of this pattern as an integer multiple with a specific pattern as a reference pattern have no influence on the drawing apparatus side, It can be determined that there is a problem in the line width measurement process.

(2) According to the invention described in claim 2, the CD linearity of the first drawing process and the third drawing process can be evaluated based on the pattern obtained in the second drawing process.
(3) According to the invention described in claim 3, the drawing material can be effectively used by drawing the first drawing process to the third drawing process in the margin of the drawing material.

  (4) According to the invention described in claim 4, when the pattern obtained by the second drawing step is measured in the line width measuring step, the measurement does not include an error factor based on the drawing device. That is, the CD linearity of the process and / or the line width measurement process can be evaluated.

  (5) According to the invention described in claim 5, it is possible to evaluate the CD linearity of the first drawing process and the third drawing process on the basis of the pattern obtained in the second drawing process.

It is a block diagram which shows one Example of this invention. It is a figure which shows the example of an evaluation pattern. It is explanatory drawing of the linearity of line | wire width. It is a figure which shows the relationship between design CD and CD error. It is a figure which shows the line | wire width when there exists size shift depending on shot size. It is a figure which shows the line | wire width when there exists a shot amount shift or beam blurring depending on shot size. It is explanatory drawing of an evaluation pattern formation area.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a lens barrel and 1A denotes a sample chamber connected to the lens barrel 1. In the lens barrel 1, 2 is an electron gun that generates an electron beam, and EB is an electron beam. 3 is a blanker for turning on / off the electron beam EB, 4 is an irradiation lens arranged under the blanker 3, 5 is a first shaping aperture arranged under the irradiation lens 4, and 6 is under the first shaping aperture 5. Is a shaping deflector arranged in

  7 is a molded lens disposed under the molded deflector 6, 8 is a second molded aperture disposed under the molded lens 7, 9 is a reduction lens disposed under the second molded aperture 8, This is an objective lens disposed under the reduction lens 9. Reference numeral 11 denotes a positioning deflector disposed below the objective lens 10. In the sample chamber 1A, 12 is a sample stage, and 13 is a drawing material disposed on the sample stage 12.

  14 is a blanking control circuit for controlling the blanker 3, 15 is a shaping deflector control circuit for controlling the shaping deflector 6, and 16 is a gain amplifier that receives and amplifies the output of the shaping deflector control circuit 15. The output of 16 is applied to the shaping deflector 6. Reference numeral 17 denotes a positioning deflector control circuit that controls the positioning deflector 11, and reference numeral 18 denotes a stage driving circuit that controls the sample stage 12.

  20 is a control CPU for controlling the operation of the entire apparatus, 21 is a pattern data disk for storing drawing patterns, 22 is a blanking control circuit 14, a shaping deflector control circuit 15 and a positioning deflector in response to a control signal from the control CPU 20. This is a data transfer circuit for supplying control data to the control circuit 16. Further, the control CPU 20 gives a control signal for stage driving to the stage driving circuit 17.

  In the apparatus configured as described above, the electron beam EB generated from the electron gun 2 is irradiated onto the first shaping aperture 5 via the irradiation lens 4. The aperture image of the first shaping aperture 5 is formed on the second shaping aperture 8 by the shaping lens 7, and the position of the image formation can be changed by the shaping deflector 6. The image formed by the second shaping aperture 8 is irradiated onto the drawing material 13 through the reduction lens 9 and the objective lens 10. The image formed by the second shaping aperture 8 can be set to an arbitrary beam size by the shaping deflector 6.

  The present invention proposes a pattern for evaluating CD linearity of a CD-SEM and CD linearity generated by processes such as baking, development, and etching after drawing. As shown in FIG. 2B, all the CD linearity evaluation patterns are divided into shot sizes having the same line width. At this time, the reference of the position of the divided shot size is the upper left of the shot. For shots divided into the same size, a systematic error possessed by the variable area electron beam lithography system, a gain of the amplifier 16 of the shaping deflector 6 (shot size deviation depending on the shot size), and a shot depending on the shot size Since the CD linearity obtained from the pattern measurement result includes the CD linearity possessed by the CD-SEM other than the drawing apparatus, since it is not affected by the deviation of the amount and the beam blur depending on the shot size (FIGS. 5 and 6). Evaluation of CD linearity caused by the process is possible.

  FIG. 5 is a diagram showing the line width when there is a size shift depending on the shot size. When there is a size shift that depends on the shot size, an error occurs only on one side of the line width. In the case of one shot shown in (a), the line width (Line Width) is represented by 100 + X (nm). Here, 100 is the original line width and X is the error. (B) is the line width in the case of two shots. Here, for the sake of easy understanding, a step is provided in the line width. The line width in this case is represented by 200 + X (nm). (C) is the line width in the case of 3 shots. The line width in this case is represented by 300 + X (nm). Thus, when the pattern used in the present invention is used, the original line width is reproduced with good linearity. The error is constant at X (nm) regardless of the increase in line width. That is, it indicates that no cumulative error occurs due to shots.

  FIG. 6 is a diagram showing the line width when there is a shot amount deviation depending on the shot size or beam blur. An error when there is a shot amount deviation or beam blur occurs at both ends of the original line width. In the case of one shot shown in (a), the line width is represented by 100 + 2X (nm). (B) is the line width in the case of two shots. The line width in this case is represented by 200 + 2X (nm). (C) is the line width in the case of 3 shots. The line width in this case is represented by 300 + 2X (nm). Thus, when the pattern used in the present invention is used, the original line width is reproduced with good linearity. The error is constant at 2X (nm) regardless of the increase in line width. That is, it indicates that no cumulative error occurs due to shots.

  Therefore, as shown in FIG. 2B, all the CD linearity evaluation patterns are divided into shot sizes having the same line width. At this time, the reference of the position of the divided shot size is the upper left of the shot. With this shot method, all shots are shot with the same shot, so the systematic error of the variable-area electron beam lithography system, the gain of the shaping deflector 6 (shot size deviation depending on the shot size), and the shot that depends on the shot size The CD linearity obtained from this pattern measurement result is not affected by the deviation of the amount or the beam blur depending on the shot size (FIGS. 5 and 6). Evaluation of CD linearity generated by the process becomes possible.

  The evaluation pattern used in the present invention can be formed using a blank portion of the drawing material. FIG. 7 is an explanatory diagram of an evaluation pattern formation region. In the figure, 13 is a drawing material, and 13a is an evaluation pattern forming region provided in a blank area of the drawing material 13. Three types of evaluation patterns shown in FIGS. 2A to 2C shown in FIG. 2 are formed in the evaluation pattern formation region 13a. This blank area is not necessarily formed at the upper left of the drawing material 13 shown in the figure, and can be formed in an arbitrary blank area. In this way, it is possible to effectively use the drawing material.

  As described above, according to the present invention, the pattern shown in FIG. 2B is used as a reference pattern, and a plurality of patterns obtained by repeating shots of this pattern by an integer multiple have no influence on the drawing apparatus side. Therefore, it can be determined that there is a problem in the process step and / or the line width measurement step.

Further, according to the present invention, it is possible to evaluate the CD linearity of the drawing process of FIG. 2A and FIG. 2C with reference to the pattern obtained in the drawing process of FIG. it can.
Further, according to the present invention, the drawing material can be effectively used by drawing the drawing steps of FIGS. 2A to 2C in the margin of the drawing material.

  Further, according to the present invention, when the pattern obtained by the drawing process in FIG. 2B is measured by the line width measuring process (CD-SEM), the measurement does not include an error factor based on the drawing apparatus. Therefore, the CD linearity of the remaining steps, that is, the process step and / or the line width measurement step can be evaluated.

  Further, according to the present invention, it is possible to evaluate the CD linearity of the drawing process of FIGS. 2A and 2C with reference to the pattern obtained in the drawing process of FIG. it can.

DESCRIPTION OF SYMBOLS 1 Lens barrel 1A Sample chamber 2 Electron gun 3 Blanker 4 Irradiation lens 5 1st shaping | molding aperture 6 Molding deflector 7 Molding lens 8 2nd shaping | molding aperture 9 Reduction lens 10 Objective lens 11 Positioning deflector 12 Sample stage 13 Drawing material 14 Blanking Control circuit 15 Molding deflector control circuit 16 Gain amplifier 17 Positioning deflector control circuit 18 Stage drive circuit 20 Control CPU
21 Pattern data disk 22 Data transfer circuit EB Electron beam

Claims (5)

A drawing process on a drawing material in a variable area electron beam apparatus, a process process for developing and etching the material drawn in the drawing process, and a line width measurement process for measuring a line width drawn on the drawing material Have
In order to evaluate the accuracy of the drawing step, the process step, and the line width measurement step, a drawing step is used in which a specific pattern is used as a reference pattern, and shots of the reference pattern are repeated an integer number to obtain n patterns. A pattern evaluation method characterized by the above. A drawing process on a drawing material in a variable area electron beam apparatus, a process process for developing and etching the material drawn in the drawing process, and a line width measuring process for measuring a line width drawn on the drawing material Have
A first drawing step of sequentially forming a first pattern and a pattern having a width of the first integer multiple in one shot to obtain n patterns;
A second drawing step in which a first pattern is set as a reference pattern, and a shot of the reference pattern is repeated an integer number of times to obtain n patterns;
A third drawing step in which a pattern having a known pattern width is drawn in a shot twice at an arbitrary ratio to obtain n patterns;
Have
The pattern obtained in the first drawing step and the third drawing step obtained in the line width measuring step on the basis of the pattern width obtained in the second drawing step obtained in the line width measuring step. A pattern evaluation method, wherein the linearity of a drawing pattern is evaluated by comparing widths.   3. The pattern evaluation method according to claim 2, wherein the first drawing step to the third drawing step are performed by drawing in a blank area of a drawing material.   The pattern evaluation method according to claim 2, wherein the pattern obtained by the second drawing step is measured in a line width measurement step, and the linearity of the process step and the line width measurement step is evaluated. A drawing process on a drawing material in a variable area electron beam apparatus, a process process for developing and etching the material drawn in the drawing process, and a line width measurement process for measuring a line width drawn on the drawing material Have
A first drawing step of sequentially forming a first pattern and a pattern having a width of the first integer multiple in one shot to obtain n patterns;
A second drawing step in which a first pattern is set as a reference pattern, and a shot of the reference pattern is repeated an integer number of times to obtain n patterns;
A third drawing step in which a pattern having a known pattern width is drawn in two shots at an arbitrary ratio to obtain n patterns;
Have
The pattern obtained in the first drawing step and the third drawing step obtained in the line width measuring step on the basis of the pattern width obtained in the second drawing step obtained in the line width measuring step. An apparatus for evaluating a pattern, comprising: an evaluation unit that compares the width and evaluates the linearity of a drawing pattern.

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