JPH10172875A - Exposure pattern data correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the arithmetic operation time by computing, using approximate equations, correcting values for designed dimensions of an exposure pattern in the X- and Y-axis directions involved in an exposure pattern data for an electron beam aligner. SOLUTION: The correcting method comprises preparing exposure pattern data, verifying pattern dimensional information of the prepared pattern data, judging if the dimensional correction is made, computing, if the correction is made, the correction values ΔLx , ΔLy for designed lengths Lx , Ly of a designed exposure pattern in the X- and Y-axis directions, using equations ΔLx =C1 +C2 Lx <-1> +C3 Lx <-2> and, ΔLy =C1 +C2 Ly <-1> +C3 Ly <-2> , approximating the relation to the dimensional error by measurement where Lx and Ly are designed lengths of the pattern in the X- and Y-axis directions, sending the corrected exposure pattern data to an electron beam aligner and sending, it no dimensional correction is made, the prepared exposure pattern data to the aligner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure pattern data correction method for preventing a pattern from being deteriorated in dimensional accuracy due to a proximity effect when a pattern is formed by using an electron beam exposure technique.

In recent years, with the miniaturization of patterns in semiconductor devices, even when a reticle pattern is formed, a problem of deterioration in dimensional accuracy of the pattern due to the influence of the proximity effect has become a problem.

As factors of the proximity effect, besides the backscattering of the electron beam, there are thermal factors involving the glass substrate and secondary electron irradiation from the lower part of the column of the electron beam exposure apparatus. In the case of using an electron beam, it is not possible to ignore the thermal factor involving the glass substrate and the influence of the secondary electron irradiation from the lower part of the column of the electron beam exposure apparatus.

[0004]

2. Description of the Related Art Conventionally, an electron beam exposure apparatus used for forming a reticle pattern has, as a measure against heat, a lower accelerating voltage of an electron beam than an electron beam exposure apparatus which performs direct exposure on a wafer. However, this also led to suppression of backscattered electrons, and the proximity effect could be reduced.

However, when forming patterns of various dimensions under the same exposure conditions and the same post-exposure processing conditions (conditions such as development processing and etching processing), the finer the pattern, the lower the exposure amount. Deterioration of dimensional accuracy with respect to design dimensions has become a problem, and a proximity effect correction program used in an electron beam direct exposure technique for a wafer is also required when a reticle pattern is created.

[0006]

The proximity effect correction program conventionally used in the electron beam direct exposure technology for a wafer is based on the exposure energy and exposure time of an electron beam exposure apparatus, and the size and interval of a pattern. Each pattern is divided so as to be easily corrected, and thereafter, the size and the exposure amount of the divided pattern are corrected.

Here, the reticle has a large exposure area,
Due to the large number of exposure pattern data, if the proximity effect correction program used in the direct electron beam exposure technology for wafers is used to correct the exposure pattern data for reticle creation, the design dimensions and exposure amount of the exposure pattern There is a problem that it takes too much time for the calculation process by the computer to calculate the correction amount.

In view of the above, the present invention provides a pattern having high dimensional accuracy for all dimensional patterns even when forming patterns of various dimensions including a fine pattern in which dimensional degradation is a problem on the same plate. And an exposure pattern data correction method capable of shortening a calculation processing time required by a computer to calculate a design dimension of an exposure pattern and a correction value of an exposure amount. The purpose is to do.

[0009]

According to a first aspect of the present invention, there is provided an exposure pattern data correcting method according to claim 1, wherein an exposure pattern included in exposure pattern data for an electron beam exposure apparatus in the X-axis direction is provided. correction amount [Delta] L _X, [Delta] L _Y and dimensional error amount of the actual measurement and the design dimensions of the X-axis direction of the exposure pattern L _X and Y-axis direction of the design dimension L _Y with respect to the design dimensions L _X and Y-axis direction of the design dimension L _Y ( However, the dimensional error is a value obtained by subtracting the actual measurement value from the design dimension.) ΔL _X = C ₁ + C ₂ L _X ^-1 + C ₃ L _X ^-2 ΔL _Y = C ₁ + C ₂ Calculated by the formula L _Y ^-1 + C ₃ L _Y ^-2 (where C ₁ , C ₂ , and C ₃ are parameters obtained from actual measurement results), and the design dimension L _X , Correcting the design dimension _LY and the starting point coordinates in the Y-axis direction to correct the exposure pattern data It is.

According to the first aspect, the correction amount ΔL _X ,
Expression, a design dimension L _Y in the design dimensions L _X and Y-axis direction of the X-axis direction of the exposure pattern, because it is obtained by approximating the relationship between the dimensional error amount of the actual measurement, on the same plate to calculate the [Delta] L _Y Even in the case of forming patterns of various dimensions including a fine pattern in which dimensional degradation is a problem, the X-axis direction of the exposure pattern is adjusted so that a pattern with high dimensional accuracy can be formed for patterns of all dimensions. design dimension L _X, design dimensions L _Y and the start point coordinates of the Y-axis direction can be corrected.

According to the first aspect, the correction amount Δ
Since the equations for calculating L _X and ΔL _Y are simple and do not require exposure correction, the calculation processing time required by a computer to calculate the dimension correction amount and the exposure correction amount is reduced. be able to.

[0012] In the present invention, the second invention (the exposure pattern data correcting method according to claim 2) is the first invention, wherein
The correction of the starting point coordinates of the exposure pattern is such that, when ΔL _X is a positive value, the positions of both ends of the exposure pattern in the X-axis direction are corrected by ΔL _X / 2 in the outward direction of the pattern, and ΔL _X is a negative value. In this case, the positions of both ends of the exposure pattern in the X-axis direction are corrected by ΔL _X / 2 inward in the pattern, and when ΔL _Y is a positive value, the positions of both ends of the exposure pattern in the Y-axis direction are corrected. Correction is performed by ΔL _Y / 2 in the outward direction of the pattern, and when ΔL _Y is a negative value, the position of both ends in the Y-axis direction of the exposure pattern is corrected by ΔL _Y / 2 in the inward direction of the pattern. It is.

According to the second aspect of the invention, the proximity effect, in particular, an insufficient exposure amount at the time of exposing a fine pattern (internal proximity effect)
The starting point coordinates of the exposure pattern can be corrected so that a pattern with high dimensional accuracy can be formed by efficiently preventing the deterioration of the dimensional accuracy of the pattern due to
By simplifying the correction method and removing the exposure correction,
The calculation processing time required by the computer for calculating the correction amount can be reduced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a flowchart schematically showing an embodiment of the present invention. When the embodiment of the present invention is executed, it is assumed that exposure pattern data is firstly stored. A creation process is performed (step S1), and pattern dimension information of the created exposure pattern data is confirmed (step S2).

FIG. 2 is a diagram schematically showing a part of an example of the exposure pattern data. Areas 8 to 13 demarcated by dotted lines 1 to 7 are determined by a beam deflectable range of the electron beam exposure apparatus. This is an area called a field which is a generated pattern generation area.

Exposure pattern data is created as information having a pattern shape, starting point coordinates, dimensions, and an exposure amount correction coefficient in units of each of the fields which are unique to the electron beam exposure apparatus. Will be done.

When step S2 is completed, it is determined whether or not to perform a dimension correction process (step S2).
3) When performing the dimension correction process (YES in step S3)
), A dimension correction process is performed (step S4).

Here, in the dimensional correction processing in step S4, the dimensional correction amount of each pattern is calculated, the correction value of the starting point coordinate of each pattern is calculated, the correction value is written to the exposure pattern data, and the correction is performed. The output processing of the exposure pattern data is sequentially performed.

When the procedure of the dimension correction processing in step S4 is completed, the corrected exposure pattern data is sent to the electron beam exposure apparatus (step S5), and the processing is terminated.

On the other hand, if NO in step S3, that is, if the dimensional correction is not performed, the created exposure pattern data is sent to the electron beam exposure apparatus without performing the dimensional correction (step S3). S5), the process ends.

Here, in step S4-, the design dimensions L _X and Y of the designed exposure pattern in the X-axis direction are set.
The correction amounts ΔL _X and ΔL _Y with respect to the axial design dimension L _Y
Dimensional error amount due to the X-axis direction of the design dimension L _X and Y-axis direction of the design dimension L _Y and the measured exposure pattern (where the dimension error amount is a value obtained by subtracting the measured value from the design dimension.) Relationship ΔL _X = C ₁ + C ₂ L _X ^-1 + C ₃ L _X ^-2 (1) ΔL _X = C ₁ + C ₂ L _Y ^-1 + C ₃ L _Y ^-2 (2) I do.

In these equations (1) and (2),
C ₁ , C ₂ , and C ₃ are parameters, and these C ₁ , C ₂ ,
C ₃ uses the same resist to creating the actual reticle to form a reticle pattern for testing in the same exposure conditions and the same post-exposure processing conditions as to create the actual reticle design obtained relation between the dimensional error amount due to dimensional and measured, by substituting the designed dimensions L _X of the formula (1), the dimensional error due to the actual measurement can be obtained by substituting the [Delta] L _X of the formula (1).

Here, C ₁ is a parameter relating to dimensional change due to process conditions (type of resist, conditions such as development and etching), C ₂ and C ₃ are resolution characteristics of the resist,
It is a parameter relating to the total exposure energy relating to forward scattering, back scattering of electrons, and fogging of reflected electrons depending on the thickness of the resist and the conditions of the electron beam exposure apparatus (such as the acceleration voltage of the electron beam).

According to the inference from the experimental results, C ₂ is a parameter representing the spread of forward scattering, C ₃ is back scattering,
It is considered to be a parameter that indicates an increase in energy due to reflected electrons.

FIG. 3 is a diagram showing a specific example of calculation of the parameters C _1, C _2, C _3, and displays the design dimension L _X of the pattern formed on reticle for testing in the horizontal axis, the vertical axis A dimensional error amount of a pattern formed on a test reticle by actual measurement, that is, a required dimensional correction amount ΔL _X is displayed. However, the dimensional error amount is obtained by ([design dimension]-[actual measurement value]).

In FIG. 3, □ plots the relationship between the design dimension L _{X of the} pattern formed on the test reticle and the dimensional error amount by actual measurement, and the curve 14 is formed on the test reticle. ΔL _X, which is an equation approximating the relationship between the design dimension L _{X of} the formed pattern and the dimensional error amount obtained by actual measurement.
= C ₁ + C ₂ L _X ^-1 + C ₃ L _X ^-2 . In this case, C ₁ = −0.03, C ₂ = 0.109, C ₃ = 0.0.
It becomes 11.

FIG. 4 is a diagram for explaining a method of calculating the correction value of the start point coordinates of the exposure pattern performed in step S4--the exposure pattern 15 before the dimension correction is set.
Reference numeral 6 denotes the start point coordinates of the exposure pattern 15 before the dimension correction, 17 denotes the exposure pattern after the dimension correction, and 18 denotes the start point coordinates of the exposure pattern 17 after the dimension correction.

That is, in one embodiment of the present invention,
When ΔL _X is a positive value, the position of both ends of the exposure pattern 15 in the X-axis direction is corrected by ΔL _X / 2 toward the outer side of the pattern when ΔL _X is a positive value, and when ΔL _X is a negative value, In
The positions at both ends of the exposure pattern 15 in the X-axis direction are corrected in the pattern inward direction by ΔL _X / 2, and when ΔL _Y is a positive value, the positions at both ends in the Y-axis direction of the exposure pattern 15 are corrected to the outside of the pattern. Correct direction by [Delta] L _Y / 2, if [Delta] L _Y is a negative value, as calculated by correcting the positions of both ends of the Y-axis direction of the exposure pattern 15 in the pattern inward direction by [Delta] L _Y / 2 I do.

As described above, according to the embodiment of the present invention, the equations (1) and (2) for obtaining the correction amounts ΔL _X and ΔL _Y.
Is to form a test reticle pattern under the same exposure conditions and the same post-exposure processing conditions as in the case of creating the actual reticle, using the same resist as in the case of creating the actual reticle, _It is assumed that the relationship between _X , _LY and the dimensional error amount by the actual measurement is approximated. In addition, the correction of the starting point coordinates is performed by correcting the positions of both ends of the exposure pattern 15 in the X-axis direction when ΔL _X is a positive value. Δ in the outer direction of the pattern
Fixed by L _X / 2, if [Delta] L _X is a negative value, the positions of both ends of the X-axis direction of the exposure pattern 15 as well as modifications to the pattern inward direction by [Delta] L _X / 2, [Delta] L _Y is a positive value In the case of, the positions of both ends of the exposure pattern 15 in the Y-axis direction are corrected by ΔL _Y / 2 in the outward direction of the pattern, and when ΔL _Y is a negative value, both ends of the exposure pattern 15 in the Y-axis direction are corrected. Since the position is corrected by correcting the position by ΔL _Y / 2 inward of the pattern, the exposure of the fine pattern can be performed even when forming patterns of various sizes including a fine pattern in which dimensional deterioration is a problem on the same plate. Deterioration of dimensional accuracy due to insufficient quantity can be efficiently prevented, and a pattern with high dimensional accuracy can be formed for patterns of all dimensions.

Incidentally, Table 1 shows that the width of the maximum value and the minimum value of the error from the design dimension of the pattern of 0.5 to 10 μm are defined as the width of the dimensional error, and the presence or absence of the dimensional correction according to the embodiment of the present invention. It shows the relationship with the width of the dimensional error.

[0031]

[Table 1]

According to one embodiment of the present invention, the equations (1) and (2) for obtaining the correction amounts ΔL _X and ΔL _Y of the design dimensions L _X and L _Y of the exposure pattern are simple. Therefore, it is possible to reduce the calculation processing time required by the computer to obtain the correction amounts ΔL _X and ΔL _Y.

[0033]

As described above, according to the first aspect of the present invention (exposure pattern data correction method according to the first aspect), the equations for calculating the correction amounts ΔL _X and ΔL _Y are expressed as follows. Design dimension L in X axis direction Design dimension L in _X axis direction
_Since the relationship between _Y and the dimensional error amount due to actual measurement is approximated and simple, patterns of various dimensions including fine patterns that cause dimensional degradation due to insufficient exposure on the same plate Is formed, the X-axis direction design dimension L _X , the Y-axis direction design dimension L _Y, and the starting point of the exposure pattern are formed so that a pattern having high dimensional accuracy can be formed for all dimension patterns. The coordinates can be corrected, and the correction amount ΔL _X ,
The calculation processing time required by the computer to calculate ΔL _Y can be reduced.

Further, according to the first aspect, since the exposure amount is not corrected, it is not necessary to reconsider the influence of the proximity effect on the surrounding pattern. Can be achieved.

According to the second aspect of the present invention, in the exposure pattern data correcting method according to the second aspect, the correction of the start point coordinates of the exposure pattern is performed when ΔL _X is a positive value. The position of both ends in the X-axis direction is
L _X / 2 is corrected, and when ΔL _X is a negative value, the positions of both ends of the exposure pattern in the X-axis direction are shifted by Δ in the pattern inner direction.
In addition to the correction of L _X / 2, if ΔL _Y is a positive value, the positions of both ends in the Y-axis direction of the exposure pattern are corrected by ΔL _Y / 2 in the outward direction of the pattern, and ΔL _Y is a negative value. In this case, the position of both ends of the exposure pattern in the Y-axis direction is corrected by ΔL _Y / 2 inward of the pattern, so that the proximity effect, particularly, the pattern size due to the insufficient light exposure at the time of exposing the fine pattern. A pattern with high dimensional accuracy can be formed by efficiently preventing deterioration in accuracy, and correction amounts ΔL _X and ΔL _Y are calculated by simplifying the correction method and eliminating exposure amount correction. For this purpose, the time required for the arithmetic processing by a computer can be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart schematically showing an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a part of an example of exposure pattern data.

FIG. 3 is a diagram showing a specific calculation example of parameters C ₁ , C ₂ , and C ₃ of an approximate expression used in an embodiment of the present invention.

FIG. 1 is a diagram for explaining a method of calculating a correction value of a start point coordinate of an exposure pattern performed in an embodiment of the present invention.

[Explanation of symbols]

 8-13 fields

Claims (2)

[Claims] 1. An X-axis design dimension L _X and Y of an exposure pattern included in exposure pattern data for an electron beam exposure apparatus.
The correction amounts ΔL _X and ΔL _Y with respect to the axial design dimension L _Y
Dimensional error amount due to the X-axis direction of the design dimension L _X and Y-axis direction of the design dimension L _Y and Measurement of the exposure pattern (where the dimension error amount is a value obtained by subtracting the measured value from the design dimension.) And The relation ΔL _X = C ₁ + C ₂ L _X ^-1 + C ₃ L _X ^-2 ΔL _Y = C ₁ + C ₂ L _Y ^-1 + C ₃ L _Y ^-2 which approximates the relationship (however, C ₁ , C ₂ , C ₃ is a parameter obtained from an actual measurement result.)
An exposure pattern data correction method, comprising correcting a design dimension L _{X in} the axial direction, a design dimension L _{Y in the} Y-axis direction, and start point coordinates to correct the exposure pattern data. 2. The correction of the starting point coordinates of the exposure pattern, when ΔL _X is a positive value, corrects the positions of both ends of the exposure pattern in the X-axis direction by ΔL _X / 2 in the outward direction of the pattern. When the ΔL _X is a negative value, the positions of both ends in the X-axis direction of the exposure pattern are set to ΔL in the pattern inward direction.
_{When the} correction is made by _X / 2, and when ΔL _Y is a positive value, the positions of both ends in the Y-axis direction of the exposure pattern are corrected by ΔL _Y / 2 in the outward direction of the pattern, and the ΔL _Y is negative. 2. The exposure pattern data correction method according to claim 1, wherein, in the case of the value, the position of both ends in the Y-axis direction of the exposure pattern is corrected by ΔL _Y / 2 inward of the pattern.