JP5773637B2 - Charged particle beam drawing apparatus and charged particle beam drawing method - Google Patents

Description

  The present invention relates to a charged particle beam drawing apparatus and a charged particle beam drawing method, and more particularly, to a technique for correcting a pattern dimension variation caused by leaving a resist in electron beam drawing.

  Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for generating a pattern among semiconductor manufacturing processes. In recent years, with the high integration of LSI, circuit line widths required for semiconductor devices have been reduced year by year. In order to form a desired circuit pattern on these semiconductor devices, a highly accurate original pattern (also referred to as a reticle or a mask) is required. Here, the electron beam (electron beam) drawing technique has an essentially excellent resolution, and is used for producing a high-precision original pattern.

FIG. 12 is a conceptual diagram for explaining the operation of a conventional variable shaping type electron beam drawing apparatus.
The variable shaped electron beam (EB) drawing apparatus operates as follows. In the first aperture 410, a rectangular opening for forming the electron beam 330, for example, a rectangular opening 411 is formed. Further, the second aperture 420 is formed with a variable shaping opening 421 for shaping the electron beam 330 having passed through the opening 411 of the first aperture 410 into a desired rectangular shape. The electron beam 330 irradiated from the charged particle source 430 and passed through the opening 411 of the first aperture 410 is deflected by the deflector, passes through a part of the variable shaping opening 421 of the second aperture 420, and passes through a predetermined range. The sample 340 mounted on a stage that continuously moves in one direction (for example, the X direction) is irradiated. That is, the drawing area of the sample 340 mounted on the stage in which the rectangular shape that can pass through both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is continuously moved in the X direction. Drawn on. A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is referred to as a variable shaping method (VSB method).

  In the above-described electron beam drawing, line width uniformity within a sample surface, for example, a mask surface with higher accuracy is required. Here, in such electron beam drawing, when a circuit pattern is drawn by irradiating a resist-coated mask with an electron beam, the electron beam passes through the resist layer and reaches the layer below it, and then reappears on the resist layer again. A phenomenon called a proximity effect due to incident backscattering occurs. Thereby, at the time of drawing, the dimension fluctuation | variation which will be drawn in the dimension shifted | deviated from the desired dimension will arise. On the other hand, even when development or etching after drawing is performed, a dimensional variation called a loading effect due to the density of the circuit pattern occurs.

Here, there is a proximity effect correction coefficient η with which the proximity effect correction matches well for each reference dose D _base . Therefore, there is disclosed a method for calculating a dose that is corrected in accordance with the dimensional variation due to the loading effect while changing the set of the reference dose D _base and the proximity effect correction coefficient η to maintain the proximity effect correction (for example, , See Patent Document 1).

However, the factor causing the dimensional variation is a problem. One of the resists frequently used for electron beam exposure is a chemically amplified resist. The chemically amplified resist has a problem that the optimum exposure amount changes depending on the exposure after exposure. That is, a phenomenon occurs in which the dimension of the drawn pattern fluctuates due to leaving after exposure. As a technique for solving this, a set of a reference dose D _base and a proximity effect correction coefficient η for obtaining a dimensional variation amount according to the elapsed time of the drawn resist in advance and correcting the dimensional variation amount according to the elapsed time is obtained. Is calculated from the correlation data (see, for example, Patent Document 2).

JP 2007-150243 A JP 2008-034781 A

When the above-described two techniques are used, a set of the reference irradiation amount D _base and the proximity effect correction coefficient η that corrects the dimensional variation due to the loading effect while maintaining the proximity effect correction described above and the elapsed time according to the set time. There are two types of combinations of a reference dose D _base for correcting the dimensional variation and a proximity effect correction coefficient η, but it is difficult to simply combine the two. On the other hand, the dimensional variation amount according to the elapsed time of the drawn resist is a global dimensional variation and does not depend on the proximity effect density. Therefore, for example, the proximity effect correction coefficient η is fixed based on a set of the reference irradiation amount D _base and the proximity effect correction coefficient η that also corrects the dimensional variation due to the loading effect while maintaining the proximity effect correction. It is also assumed that the dimensional variation amount corresponding to the elapsed time is corrected by changing the reference irradiation amount D _base . However, this increases the deviation of the proximity effect correction as the correction amount increases. As described above, a sufficient technique for correcting the dimensional variation due to the global phenomenon such as the loading effect and the dimensional variation due to the elapsed time of the drawn resist while maintaining the proximity effect correction has not been established. It was.

  Therefore, the present invention overcomes the above-mentioned problems and corrects the dimensional variation due to the global phenomenon such as the loading effect and the dimensional variation due to the elapsed time of the drawn resist while maintaining the proximity effect correction. It is an object of the present invention to provide an apparatus and a method capable of doing so.

A charged particle beam drawing apparatus according to one embodiment of the present invention includes:
A first set of a proximity effect correction coefficient for correcting pattern variation due to the proximity effect and a reference irradiation amount, and a margin for each proximity effect density that is a coefficient indicating a relationship between the pattern size and the charged particle beam irradiation amount And a first dose calculation unit that calculates a first dose of the charged particle beam for each proximity effect density using a pattern dimensional variation caused by the standing time after drawing,
The first dose for each calculated proximity effect density is a dose that uses the proximity effect correction coefficient and the reference dose as parameters, without using the tolerance and the pattern dimension variation caused by the standing time as parameters. An acquisition unit that performs fitting using an arithmetic expression to acquire a second set for each drawing position of a proximity effect correction coefficient that is dependent on the drawing position and corrects a dimensional variation due to the proximity effect and a reference irradiation amount;
A second irradiation amount calculation unit that calculates a second irradiation amount of the charged particle beam using a second set for each drawing position of the acquired proximity effect correction coefficient and the reference irradiation amount for each drawing position;
A drawing unit that draws a pattern on a sample using a charged particle beam of the second irradiation amount calculated for each drawing position;
It is provided with.

  According to such a configuration, the proximity effect that corrects the dimensional variation due to the global phenomenon such as the loading effect and the dimensional variation due to the elapsed time of the drawn resist using the margin while maintaining the proximity effect correction. A set of correction coefficient and reference dose can be obtained.

Moreover, the charged particle beam drawing apparatus according to another aspect of the present invention includes:
A first dose for each proximity effect density of a charged particle beam at a plurality of proximity effect densities is calculated using a first set of a proximity effect correction coefficient that corrects pattern variation due to the proximity effect and a reference dose. A first dose calculator that
Using the above-described correlation between the pattern size for each of the plurality of proximity effect densities and the irradiation amount of the charged particle beam, the pattern size for each proximity effect density corresponding to the calculated first irradiation amount for each proximity effect density. A pattern dimension calculation unit for calculating
An adding unit that adds the dimensional variation amount of the pattern to the calculated pattern size for each proximity effect density using the dimensional variation amount of the pattern caused by the standing time after drawing,
A second irradiation amount calculation unit that calculates a second irradiation amount for each proximity effect density of the charged particle beam corresponding to the pattern size for each proximity effect density after addition using the above-described correlation;
Fitting the second dose for each calculated proximity effect density using a dose calculation formula using the proximity effect correction coefficient and the reference dose as parameters, and the size variation due to the proximity effect depending on the drawing position An acquisition unit for acquiring a second set for each drawing position of the proximity effect correction coefficient and the reference irradiation amount for correcting
A third dose calculation unit that calculates a third dose of the charged particle beam using a second set for each drawing position of the acquired proximity effect correction coefficient and the reference dose for each drawing position;
A drawing unit that draws a pattern on the sample using a charged particle beam of the calculated third irradiation amount for each drawing position;
It is provided with.

  According to this configuration, using the correlation between the pattern size for each proximity effect density and the irradiation amount of the charged particle beam, the size variation amount due to a global phenomenon such as the loading effect is drawn while maintaining the proximity effect correction. It is possible to obtain a set of the proximity effect correction coefficient and the reference irradiation amount that are corrected together with the dimensional variation amount due to the elapsed time of the resist.

Moreover, the charged particle beam drawing apparatus according to another aspect of the present invention includes:
Using the tolerance depending on the proximity effect density, which is a coefficient indicating the relationship between the pattern dimension and the irradiation amount of the charged particle beam, and the pattern dimension variation due to the standing time after drawing, the dimension variation is calculated. A correction term calculation unit for calculating a correction term for correction;
A dose calculation unit for calculating the dose of the charged particle beam using a first term and a correction term of a proximity effect correction coefficient and a reference dose for correcting the pattern variation due to the proximity effect for each drawing position; ,
A drawing unit that draws a pattern on a sample using a charged particle beam of a calculated irradiation amount for each drawing position;
It is provided with.

  According to such a configuration, the amount of dimensional variation due to a global phenomenon such as a loading effect and the progress of a drawn resist while maintaining proximity effect correction without converting the pair of the proximity effect correction coefficient and the reference irradiation amount. It can be corrected together with the amount of dimensional variation with time.

The charged particle beam drawing method of one embodiment of the present invention includes:
A first set of a proximity effect correction coefficient for correcting pattern variation due to the proximity effect and a reference irradiation amount, and a margin for each proximity effect density that is a coefficient indicating a relationship between the pattern size and the charged particle beam irradiation amount And calculating a first irradiation amount of the charged particle beam for each proximity effect density using the dimensional variation amount of the pattern caused by the standing time after drawing,
The first dose for each calculated proximity effect density is a dose that uses the proximity effect correction coefficient and the reference dose as parameters, without using the tolerance and the pattern dimension variation caused by the standing time as parameters. Fitting with an arithmetic expression to obtain a second set for each drawing position of the proximity effect correction coefficient for correcting the dimensional variation due to the proximity effect and the reference irradiation amount depending on the drawing position;
Calculating a second irradiation amount of the charged particle beam using a second set for each drawing position of the acquired proximity effect correction coefficient and the reference irradiation amount for each drawing position;
Drawing a pattern on the sample using a charged particle beam of the calculated second irradiation amount for each drawing position;
It is provided with.

A charged particle beam writing method according to another aspect of the present invention includes:
A first dose for each proximity effect density of a charged particle beam at a plurality of proximity effect densities is calculated using a first set of a proximity effect correction coefficient that corrects pattern variation due to the proximity effect and a reference dose. And a process of
Using the above-described correlation between the pattern size for each of the plurality of proximity effect densities and the irradiation amount of the charged particle beam, the pattern size for each proximity effect density corresponding to the calculated first irradiation amount for each proximity effect density. A step of calculating
Adding the dimensional variation amount of the pattern to the calculated pattern size for each proximity effect density using the dimensional variation amount of the pattern caused by the standing time after drawing; and
Using the correlation described above, calculating a second irradiation amount for each proximity effect density of the charged particle beam corresponding to the pattern size for each proximity effect density after addition; and
Fitting the second dose for each calculated proximity effect density using a dose calculation formula using the proximity effect correction coefficient and the reference dose as parameters, and the size variation due to the proximity effect depending on the drawing position Obtaining a second set for each drawing position of the proximity effect correction coefficient and the reference irradiation amount for correcting
Calculating a third dose of the charged particle beam using a second set for each drawing position of the acquired proximity effect correction coefficient and the reference dose for each drawing position;
Drawing a pattern on the sample using the charged particle beam of the calculated third irradiation amount for each drawing position;
It is provided with.

  According to one aspect of the present invention, it is possible to correct the dimensional variation due to the global phenomenon such as the loading effect and the dimensional variation due to the elapsed time of the drawn resist while maintaining the proximity effect correction. As a result, highly accurate drawing can be performed.

1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. FIG. 4 is a flowchart showing main steps of the drawing method according to Embodiment 1. FIG. 3 is a conceptual diagram for explaining a stripe region in the first embodiment. 6 is a graph showing an example of dimensional variation caused by the elapsed time of the drawn resist in the first embodiment. 3 is a graph showing a relationship between an irradiation amount and a proximity effect density in the first embodiment. 6 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 2. FIG. FIG. 10 is a flowchart showing main steps of a drawing method according to Embodiment 2. It is a conceptual diagram for demonstrating the conversion method of the group for every proximity effect density of proximity effect correction coefficient (eta) in Embodiment 2, and the reference irradiation amount Dbase. FIG. 10 is a conceptual diagram illustrating a configuration of a drawing apparatus according to a third embodiment. FIG. 10 is a flowchart showing main steps of a drawing method according to Embodiment 3. FIG. 10 is a diagram showing an example of pattern dimension deviation when drawing is performed by the drawing method according to the third embodiment. It is a conceptual diagram for demonstrating operation | movement of the conventional variable shaping type | mold electron beam drawing apparatus.

  Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam may be used. Further, a variable shaping type drawing apparatus will be described as an example of the charged particle beam apparatus.

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the first embodiment. In FIG. 1, the drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a charged particle beam drawing apparatus. In particular, it is an example of a variable shaping type (VSB type) drawing apparatus. The drawing unit 150 includes an electron column 102 and a drawing chamber 103. In the electron column 102, there are an electron gun 201, an illumination lens 202, a blanking deflector 212, a blanking aperture 214, a first shaping aperture 203, a projection lens 204, a deflector 205, a second shaping aperture 206, an objective. A lens 207, a main deflector 208, and a sub deflector 209 are disposed. An XY stage 105 that can move at least in the XY direction is disposed in the drawing chamber 103. On the XY stage 105, a sample 101 to be drawn is arranged. The sample 101 includes an exposure mask and a silicon wafer for manufacturing a semiconductor device. Masks include mask blanks. On the sample 101, a chemically amplified resist whose pattern dimension varies depending on the elapsed time after exposure is applied.

  The control unit 160 includes control computers 110 and 120, memories 112 and 122, a deflection control circuit 130, a digital-analog converter (DAC) 132, and storage devices 140, 141, 142, 143, 144, and 146 such as a magnetic disk device. Have. The control computers 110 and 120, the memories 112 and 122, the deflection control circuit 130, and the storage devices 140, 141, 142, 143, 144, and 146 are connected to each other via a bus (not shown). The deflection control circuit 130 is connected to the blanking deflector 212 via the DAC 132.

  In the control computer 110, an area density map creation unit 30, a dimensional variation acquisition unit 32, a proximity effect density and reference dose calculation unit 34, a proximity effect density map creation unit 36, a reference dose map creation unit 38, and a drawing A time prediction unit 39 is arranged. Functions such as an area density map creation unit 30, a dimensional variation acquisition unit 32, a proximity effect density and reference dose calculation unit 34, a proximity effect density map creation unit 36, a reference dose map creation unit 38, and a drawing time prediction unit 39 May be configured by software such as a program. Alternatively, it may be configured by hardware such as an electronic circuit. Alternatively, a combination thereof may be used. The input data necessary for the control computer 110 or the calculated result is stored in the memory 112 each time.

  In the control computer 120, there are an elapsed time measuring unit 40, a dimensional variation calculating unit 42, a dose calculating unit 44, a proximity effect correction coefficient and reference dose calculating unit 50, a proximity effect density calculating unit 52, a proximity effect correcting dose. A calculation unit 54, a dose calculation unit 56, and a shot data generation unit 58 are arranged. Elapsed time measurement unit 40, dimensional variation calculation unit 42, dose calculation unit 44, proximity effect correction coefficient and reference dose calculation unit 50, proximity effect density calculation unit 52, proximity effect correction dose calculation unit 54, dose calculation Each function such as the unit 56 and the shot data generation unit 58 may be configured by software such as a program. Alternatively, it may be configured by hardware such as an electronic circuit. Alternatively, a combination thereof may be used. The input data necessary for the control computer 110 or the calculated result is stored in the memory 122 each time.

  The storage device 140 stores drawing data necessary for drawing such as a pattern layout, a graphic code, and coordinates from the outside. In the storage device 143, a plurality of discrete tolerances DL (Ui) 22 are input from the outside as parameters and stored. The tolerance DL (Ui) is defined as a coefficient indicating the relationship between the pattern dimension CD and the irradiation amount of the electron beam 200 for each proximity effect density.

  Here, FIG. 1 shows a configuration necessary for explaining the first embodiment. The drawing apparatus 100 may normally have other necessary configurations. For example, the main and sub two-stage main deflector 208 and sub-deflector 209 are used here, but one stage or three or more stages of deflectors may be used. Further, the deflection control circuit 130 is connected to the deflector 205, the main deflector 208, and the sub-deflector 209 via each DAC (not shown).

  FIG. 2 is a flowchart showing main steps of the drawing method according to the first embodiment. In FIG. 2, a pattern input step (S102), a loading correction calculation step (S104), a reference dose Dbase (x) (base dose) map creation step (S106), and a proximity effect correction coefficient η (x) map creation. Step (S108), elapsed time measurement step (S110), dimension variation CD (t) calculation step (S112), reference dose Dbase (x, t) and proximity effect correction coefficient η (x, t) calculation A series of steps such as a step (S120), a proximity effect correction dose Dp (η (x, t), U) map creation step (S126), and a drawing step (S128) are performed.

  First, before starting the drawing process, as a pre-process, a pattern input step (S102), a loading correction calculation step (S104), a reference dose Dbase (x) (base dose) map creation step (S106), The proximity effect correction coefficient η (x) map creation step (S108) is performed.

  As the pattern input step (S102), the control computer 110 inputs drawing data stored in the storage device 140.

  As a loading correction calculation step (S104), the control computer 110 performs a loading correction calculation for each position of the sample 101. First, the area density map creation unit 30 virtually divides the drawing area 10 of the sample 101 into a plurality of mesh-like mesh areas, and calculates the area density ρ of the pattern arranged inside each mesh area. Then, an area density map depending on the position is created.

  Next, the dimensional variation amount acquisition unit 32 acquires the dimensional variation amount ΔCD (x) of the pattern caused by the loading effect. Here, only the dimensional variation amount of the pattern due to the loading effect is shown, but other global dimensional variation amounts may be obtained together. The dimension variation amount ΔCD (x) uses a loading effect correction coefficient γ, an area density ρ (x), a distribution function g (x), and a pattern dimension variation amount CDpos (x) resulting from a position-dependent loading effect. And can be defined by the following equation (1). Here, the position x indicates each mesh position (coordinate) when the drawing region of the sample to be drawn is meshed at a global position or about 1/10 of the loading effect distribution radius.

  The position-dependent dimensional variation CDpos (x) may be obtained in advance through experiments or the like. Then, it may be stored in the storage device 141. Alternatively, the dimensional variation amount ΔCD (x) itself may be acquired from a user or the like and stored in the storage device 141. In such a case, the dimensional variation amount acquisition unit 32 may read the dimensional variation amount ΔCD (x) itself from the storage device 141 without calculating Equation (2). Here, in order to make the contents easy to understand, the position in the x direction is shown, but the position in the y direction is similarly calculated. Both x indicating the position in the x direction and y indicating the position in the y direction indicate a vector. The same applies hereinafter.

  Next, the proximity effect density and reference dose calculation unit 34 corrects the pattern variation amount ΔCD (x) due to the loading effect while maintaining the proximity effect correction, and the proximity effect correction coefficient η (x) and A set of reference dose Dbase (x) is calculated. At this time, a dose D corresponding to a dimension obtained by correcting ΔCD (x) from a desired CD by ΔCD (x) is obtained for each position x, for example, from CD-D correlation data for each proximity effect density. Thereby, the dose D for each discrete proximity effect density is obtained. Then, for each position x, a set of a proximity effect correction coefficient η (x) and a reference dose Dbase (x) where the dose D for each discrete proximity effect density satisfies the following formula (2) is calculated. Good. Correlation data between the pattern dimension CD and the dose D for each proximity effect density may be stored in the storage device 141, for example. Also, a reference dose Dbase that can be corrected well for any proximity effect density U so that processing can be performed regardless of what proximity effect density U region is present in the mesh indicated by x. A set of (x) and the proximity effect correction coefficient h (x) is obtained. Therefore, it is possible to obtain these sets without calculating U (x) in advance.

  Here, the proximity effect correction dose Dp (η (x), U) in the equation (2) is defined by the following equation (3).

  Then, as a reference dose Dbase (x) map creation step (S106), the reference dose map creation unit 38 creates a reference dose Dbase (x) map in which the reference dose Dbase (x) is stored for each position. To do.

  Similarly, as the proximity effect correction coefficient η (x) map creation step (S108), the reference dose map creation unit 38 creates a η (x) map in which the proximity effect correction coefficient η (x) is stored for each position. To do. The created reference dose Dbase (x) map and proximity effect correction coefficient η (x) map are stored in the storage device 142. Alternatively, the reference dose Dbase (x) map and the proximity effect correction coefficient η (x) map may be acquired from a user or the like and stored in the storage device 142. In such a case, the steps from the step of obtaining the pattern dimension variation ΔCD (x) due to the loading effect in the loading correction calculation step (S104) to the proximity effect correction coefficient η (x) map creation step (S108) are unnecessary. It becomes.

  As described above, the proximity fluctuation correction coefficient η (x) and the reference dose Dbase (x) that can correct the pattern dimension variation amount ΔCD (x) due to the loading effect as a base while maintaining the proximity effect correction. ) However, as described above, the dimensional variation amount CD (t) due to the elapsed time of the drawn resist cannot be corrected as it is. Therefore, in the first embodiment, a set of the proximity effect correction coefficient η (x) and the reference irradiation amount Dbase (x) as a base is converted to obtain a pattern dimension variation amount ΔCD (x) caused by the loading effect. The proximity effect correction coefficient η (x, t) and the reference dose Dbase (x, t) that can correct both the dimensional variation CD (t) caused by the elapsed time of the resist while maintaining the proximity effect correction. Get a pair.

  First, before starting the drawing process, as a drawing time prediction step, the drawing time prediction unit 39 starts and ends drawing of the pattern defined in the drawing data stored in the storage device 140. tw is predicted. The prediction of the drawing time tw can be calculated using, for example, the speed profile of the XY stage 105.

  FIG. 3 is a conceptual diagram for explaining stripe regions in the first embodiment. The drawing region 10 of the sample 101 is virtually divided into a plurality of stripe regions 20 in a strip shape with a width that can be deflected by the main deflector 208 in the x direction or the y direction. Then, drawing processing proceeds for each stripe region 20. When the drawing of one stripe area is completed, the next adjacent stripe area is drawn. First, the moving speed of the XY stage 105 is calculated for each stripe region 20. The moving speed may be calculated according to the density or the like of the pattern drawn in the stripe region 20. The dense area is slow and the coarse area is fast. Then, the speed profile of the XY stage 105 is calculated from the moving speed. If the length of the stripe region 20 is divided by the speed indicated by the speed profile of the XY stage 105, the drawing time of the stripe area can be predicted. If the drawing times of the stripe regions are added, the drawing time tw from the start to the end of drawing the pattern defined in the drawing data can be predicted.

  As described above, after the base proximity effect correction coefficient η (x) and the reference dose Dbase (x) set and the drawing time tw are calculated, the drawing process is started. The drawing process proceeds in units of stripe regions 20 as described above. When the drawing of one stripe region 20 is completed, the next adjacent stripe region is drawn. At that time, in order to perform the drawing process, the data calculation process needs to be completed before actually irradiating the electron beam. Further, since the data calculation process has a large calculation amount, the data calculation process is advanced in advance for at least one stripe area 20 that has not yet been drawn. Thereby, data calculation can be performed in real time. In the example of FIG. 3, for example, when the nth stripe region 20a is drawn, the data calculation processing is performed on the n + 1th stripe region 20b in parallel. In this way, data operation processing is sequentially performed on the preceding stripe region 20. Then, drawing is performed on the stripe region 20 for which the data calculation process has been completed.

  First, as the elapsed time measurement step (S110), the elapsed time measurement unit 40 starts from the start time at which the drawing process is started, for example, until the drawing start time at the drawing start position A of the stripe region currently being drawn. The elapsed time t (A) is measured. The dimensional variation CD (t) due to the elapsed time of the drawn resist is approximately the same between adjacent stripes. Even if they are not adjacent to each other, there is almost no change as long as the stripe regions are separated by several columns. Therefore, in the first embodiment, when calculating the dimension variation amount CD (t) for the stripe region to be subjected to data processing, the elapsed time t (A) measured for the stripe region that has already been drawn is used as the elapsed time t. Use.

  As the dimension variation amount CD (t) calculation step (S112), the dimension variation amount calculation unit 42 calculates the desired pattern number method CD0 before the dimension variation caused by the elapsed time of the drawn resist, the coefficient α (U), Using the drawing time tw and the elapsed time t from the start of drawing, the following equation (4) can be used.

  The coefficient α (U) may be a constant or a value depending on the proximity effect density U. The coefficient α (U) may be obtained in advance through experiments or the like.

  FIG. 4 is a graph showing an example of dimensional variation caused by the elapsed time of the drawn resist in the first embodiment. If the dimension variation due to the elapsed time of the resist is not corrected, as shown in FIG. 4, even if drawing is performed with an irradiation dose corresponding to the pattern dimension CD, the pattern dimension actually formed is finished after drawing the pattern. The longer the time until the blank is taken out and the PEB process is performed, the thicker it becomes. The pattern immediately after the start of the result drawing becomes the thickest and becomes CDini. In order to make the pattern dimensions uniform, the dimensional change amount due to the elapsed time is predicted, and when there is no elapsed time, the pattern is drawn with an irradiation amount so as to obtain a dimensional bias opposite in sign to the dimensional change amount. It is necessary to cancel the dimensional change due to the elapsed time. Therefore, as shown by the correction A, the irradiation amount is controlled in consideration of the drawing elapsed time, and the pattern dimension is corrected to be CDini. Alternatively, it is conceivable to perform correction so that the pattern dimension becomes CD as indicated by correction B. In this case, it is necessary to predict Tfin and CDini before starting the drawing process. In the example of FIG. 4, the dimensional variation amount CD (t) does not depend on the proximity effect density U. Therefore, in such a case, the coefficient α (U) may be a constant. However, the present invention is not limited to this, and the dimensional variation amount CD (t) may depend on the proximity effect density U. In such a case, the coefficient α (U) may be a value depending on the proximity effect density U.

  As the reference irradiation amount Dbase (x, t) and the proximity effect correction coefficient η (x, t) calculation step (S120), first, the irradiation amount calculation unit 44 stores a margin for each of the plurality of proximity effect densities U from the storage device 143. The degree DL (Ui) is read out, and the base proximity correction coefficient η (x) and the reference irradiation amount Dbase (x) set (first set) are read out from the storage device 142 for each position x. Then, a proximity effect density that is a coefficient indicating a relationship between a set of a proximity effect correction coefficient η (x) and a reference dose Dbase (x) (first set) as a base, and a pattern dimension and an electron beam dose By using the tolerance DL (Ui) for each time and the pattern dimension variation amount CD (t) resulting from the standing time after drawing, the irradiation amount D ( x, Ui, t) (first dose) is calculated. The dose calculation unit 44 is an example of a first dose calculation unit. The dose D (x, Ui, t) can be defined by the following equation (5).

  Here, as the proximity effect correction dose Dp in the equation (5), the equation (3) may be used. Further, for example, the tolerance DL (Ui) may be stored in the storage device 143 for each case of the proximity effect density Ui = 0 (0%), 0.5 (50%), 1 (100%). . Since the proximity effect density Ui = 0 actually has no pattern, it can be approximated by drawing, for example, one line pattern for measurement in a state where there is nothing around. On the contrary, the proximity effect density Ui = 1 is a pattern in the entire mesh including the periphery, and the dimension cannot be measured. Therefore, for example, one line pattern for measurement is drawn in a state where the periphery is filled with the pattern. Can be obtained by approximation. Here, the proximity effect density Ui to be set is not limited to 0%, 50%, and 100%. For example, it is also preferable to use any one of 10% or less, 50%, and 90% or more. Moreover, you may measure by not only three types but another number. For example, four or more types may be measured.

  The tolerance DL (U) indicates the relationship between the pattern dimension CD and the dose D (U). The tolerance DL (U) depends on the proximity effect density U (x). In a graph having the pattern dimension CD as the vertical axis and the dose D (U) as the horizontal axis, for example, it is defined by the slope (proportional coefficient) of the graph for each proximity effect density U (x). By showing the logarithm of the dose D on the horizontal axis, a graph close to a straight line can be obtained, which becomes a proportional coefficient, but is not limited thereto. The margin DL (U) only needs to be defined as a parameter (coefficient) indicating the relationship between the pattern dimension CD and the dose D (U).

  As described above, the dose D (x, Ui, t) in each case of Ui = 0 (0%), 0.5 (50%), and 1 (100%) is obtained for each position x.

  FIG. 5 is a graph showing the relationship between the dose and the proximity effect density in the first embodiment. The graph of FIG. 5 shows the dose D on the vertical axis and the proximity effect density U on the horizontal axis. In FIG. 5, the irradiation dose D (x, Ui, t) in each case of Ui = 0 (0%), 0.5 (50%), and 1 (100%) obtained is plotted. Then, the proximity effect correction coefficient and reference dose calculation unit 50 sets the dose in each case of plotted Ui = 0 (0%), 0.5 (50%), and 1 (100%) for each position x. D (x, Ui, t) is fitted by the following equation (6).

  Further, the proximity effect correction dose Dp in equation (6) is defined by the following equation (7).

  Then, the proximity effect correction coefficient and reference dose calculation unit 50 calculates the proximity effect correction coefficient η (x, x, x) that corrects the dimensional variation due to the proximity effect, which is calculated when fitting for each position x. A set (second set) for each drawing position of t) and the reference dose Dbase (x, t) is acquired. The proximity effect correction coefficient and reference dose calculation unit 50 is an example of an acquisition unit. As described above, the proximity effect correction coefficient and reference dose calculation unit 50 uses the calculated dose D (x, Ui, t) for each proximity effect density for each position x as the tolerance DL and the standing time. Fitting by using a dose calculation formula using the proximity effect correction coefficient η and the reference dose Dbase as parameters without using the resulting pattern dimension variation CD (t) as parameters, and depending on the drawing position. A set for each drawing position of the proximity effect correction coefficient η (x, t) and the reference dose Dbase (x, t) for correcting the dimensional variation due to the proximity effect is acquired. Then, it is stored in the storage device 144 as a proximity effect correction coefficient η (x, t) map and a reference dose Dbase (x, t) map for each stripe region 20 that is currently performing data processing. Also, a reference dose Dbase that can be corrected well for any proximity effect density U so that processing can be performed regardless of what proximity effect density U region is present in the mesh indicated by x. A set of (x, t) and the proximity effect correction coefficient h (x, t) is obtained. Therefore, it is possible to obtain these sets without calculating U (x) in advance.

  As described above, the set of the proximity effect correction coefficient η (x) and the reference irradiation amount Dbase (x) as a base is converted, and the pattern size variation amount ΔCD (x) resulting from the loading effect and the resist A set of a proximity effect correction coefficient η (x, t) and a reference irradiation amount Dbase (x, t) that can correct both the dimensional variation CD (t) caused by the elapsed time while maintaining the proximity effect correction. get.

  In the proximity effect correction dose Dp (η (x, t), U) map creation step (S126), first, the proximity effect density calculation unit 52 performs the proximity effect density at each position of the stripe region 20 on which data processing is performed. U (x) is calculated.

  The proximity effect density U (x) is defined as a value obtained by convolving and integrating the distribution function g (x) with the pattern area density ρ (x) in the proximity effect mesh in a range equal to or greater than the influence range of the proximity effect. 8).

  The proximity effect mesh preferably has a size of, for example, about 1/10 of the influence range of the proximity effect, and for example, a size of about 1 μm is preferable. For example, a Gaussian function may be used as the distribution function g (x). Thus, the position x from here in the first embodiment is a local position or each mesh position (coordinate) when the drawing region of the sample to be drawn is meshed with about 1/10 of the proximity effect distribution radius. Pointing.

  Then, the proximity effect correction dose calculator 54 calculates the proximity effect correction dose Dp at each position. The proximity effect correction dose Dp may be obtained by reading the proximity effect correction coefficient η (x, t) from the storage device 144 and using the above-described equation (7). In the proximity effect correction coefficient η (x, t) map stored in the storage device 144, x indicates a global size mesh coordinate. Here, the global size mesh including the local small size mesh coordinate described above is used. Refer to the value of coordinates. However, U (x) calculated | required by Formula (8) is used for U in Formula (7).

  Then, it is stored in the storage device 144 as a proximity effect correction dose Dp (η (x, t), U) map for each stripe region 20 on which data processing is performed.

  In the above-described example, the proximity effect correction dose Dp is indicated by a linear function of η (x, t). However, the present invention is not limited to this, and high-order calculation is performed using an iteration method (not shown). It is also suitable to carry out. For example, it is preferable to perform a third order calculation.

  When the calculation up to the proximity effect correction dose Dp (η (x, t), U) map for each stripe region 20 currently undergoing data processing is completed as described above, data for the next stripe region 20 is completed. Return to computation. That is, the process returns to the elapsed time measurement step (S110). Then, calculation is performed up to the proximity effect correction dose Dp (η (x, t), U) map for each stripe region 20. In this way, the proximity effect correction coefficient η (x, t) map, the reference dose Dbase (x, t) map, and the proximity effect correction dose Dp (η (x, t), U) for each stripe region 20 are obtained. Create maps sequentially.

  As the drawing step (S128), the dose calculation unit 56 sets a set for each drawing position of the acquired proximity effect correction coefficient η (x, t) and the reference dose Dbase (x, t) for each drawing position. Using this, the dose D (second dose) of the electron beam 200 is calculated. The dose calculation unit 56 serves as a second dose calculation unit. Specifically, the proximity effect correction dose Dp (η (x, t), U) obtained from the acquired proximity effect correction coefficient η (x, t) and the reference dose Dbase (x, t) are obtained. Using this, the dose D (x, U, t) is calculated. The dose D (x, U, t) is obtained by the above-described equation (6). In the reference dose Dbase (x, t) map stored in the storage device 144, x indicates a global size mesh coordinate. Here, the global size mesh coordinate including the local small size mesh coordinate described above is used. Refer to the value of.

  The shot data generation unit 58 receives drawing data from the storage device 140 and performs a plurality of stages of data conversion processing to generate device-specific shot data. The shot data generation unit 58 converts a plurality of figure patterns defined in the drawing data into shot figures of a size that can be irradiated with one electron beam 200 (size that can be formed), and the irradiation amount and irradiation of each shot figure Shot data in which a position, a shot figure type, a shot figure size, and the like are defined is generated. As the irradiation amount, the above-described irradiation amount D (x, U, t) is used.

  The generated shot data is stored in the storage device 146. Then, the deflection control circuit 130 calculates a deflection amount for deflecting the electron beam 200 to the defined drawing position along the shot data. Similarly, the electron beam 200 is irradiated for the irradiation amount (irradiation time) defined for each shot figure, and when the irradiation time elapses, a deflection amount for deflecting the electron beam 200 to be shielded is calculated. Similarly, a deflection amount for forming a graphic of the graphic type and size defined for each shot graphic is calculated. Then, the deflection voltage of each deflection amount is applied to the corresponding deflector. By such each deflection, the drawing unit 150 draws a pattern on the sample 101 using the electron beam 200 with the calculated irradiation amount D (x, U, t) for each drawing position. Specifically, the following operation is performed.

  When the electron beam 200 emitted from the electron gun 201 (emission unit) passes through the blanking deflector 212, it is controlled by the blanking deflector 212 so as to pass through the blanking aperture 214 in the beam ON state. In the beam OFF state, the entire beam is deflected so as to be shielded by the blanking aperture 214. The electron beam 200 that has passed through the blanking aperture 214 until the beam is turned off after the beam is turned off becomes one shot of the electron beam. The blanking deflector 212 controls the direction of the passing electron beam 200 to alternately generate a beam ON state and a beam OFF state. For example, the voltage may be applied to the blanking deflector 212 when the beam is OFF, without applying a voltage when the beam is ON. The irradiation amount per shot of the electron beam 200 irradiated on the sample 101 is adjusted in the irradiation time of each shot.

  As described above, the electron beam 200 of each shot generated by passing through the blanking deflector 212 and the blanking aperture 214 illuminates the entire first shaping aperture 203 having a rectangular hole, for example, a rectangular hole, by the illumination lens 202. To do. Here, the electron beam 200 is first formed into a rectangle, for example, a rectangle. Then, the electron beam 200 of the first aperture image that has passed through the first shaping aperture 203 is projected onto the second shaping aperture 206 by the projection lens 204. The deflector 205 controls the deflection of the first aperture image on the second shaping aperture 206 and can change the beam shape and dimensions (variable shaping is performed). Such variable shaping is performed for each shot, and is usually shaped into different beam shapes and dimensions for each shot. Then, the electron beam 200 of the second aperture image that has passed through the second shaping aperture 206 is focused by the objective lens 207, deflected by the main deflector 208 and the sub deflector 209, and continuously moved. The desired position of the sample 101 arranged at 105 is irradiated. The stripe region is virtually divided into subfields (SF) that can be deflected by the sub deflector 209. First, the electron beam 200 is deflected to the SF reference position where the main deflector 208 is shot. Since the XY stage 105 is moving, the main deflector 208 deflects the electron beam 200 so as to follow the movement of the XY stage 105. The sub deflector 209 irradiates each position in the SF.

  As described above, according to the first embodiment, the amount of dimensional variation due to a global phenomenon such as the loading effect and the elapsed time of the drawn resist is maintained while maintaining proximity effect correction using tolerance. Thus, it is possible to obtain a set of the proximity effect correction coefficient and the reference dose that are corrected together. Therefore, it is possible to correct the dimensional variation due to the global phenomenon such as the loading effect and the dimensional variation due to the elapsed time of the drawn resist while maintaining the proximity effect correction. As a result, highly accurate drawing can be performed.

Embodiment 2. FIG.
In the first embodiment, a set of a base proximity effect correction coefficient η (x, t) and a reference dose Dbase (x, t) is converted using a plurality of discrete tolerances DL (Ui). However, it is not limited to this.

  FIG. 6 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the second embodiment. In FIG. 6, in place of the dose calculation unit 44 in the control computer 120, a dose D (Ui) calculation unit 43, a pattern dimension CD (Ui) calculation unit 45, an addition unit 46, and a dose D (Ui). Except for the point where the calculation unit 47 is added and the point that the CD-D correlation data 26 for each proximity effect density is stored in the storage device 143 instead of the tolerance DL (Ui) 22 for each proximity effect density, FIG. It is the same. Further, the elapsed time measuring unit 40, the dimensional variation calculation unit 42, the irradiation dose D (Ui) calculation unit 43, the pattern dimension CD (Ui) calculation unit 45, the addition unit 46, the irradiation dose D (Ui) calculation unit 47, the proximity Each function such as the effect correction coefficient and reference dose calculation unit 50, the proximity effect density calculation unit 52, the proximity effect correction dose calculation unit 54, the dose calculation unit 56, and the shot data generation unit 58 is configured by software such as a program. May be. Alternatively, it may be configured by hardware such as an electronic circuit. Alternatively, a combination thereof may be used. The input data necessary for the control computer 110 or the calculated result is stored in the memory 122 each time.

  FIG. 7 is a flowchart showing main steps of the drawing method according to the second embodiment. In FIG. 7, instead of the reference dose Dbase (x, t) and the proximity effect correction coefficient η (x, t) calculation step (S120), the reference dose Dbase (x, t) and the proximity effect correction coefficient η (x, t t) A calculation step (S121) is added, and in the reference irradiation amount Dbase (x, t) and the proximity effect correction coefficient η (x, t) calculation step (S121), the tolerance DL (Ui) 22 for each proximity effect density. 2 is the same as FIG. 2 except that the CD-D correlation data 26 for each proximity effect density is used instead of.

  In the second embodiment, contents not particularly described are the same as those in the first embodiment. The contents of each process from the pattern input process (S102) to the dimension variation CD (t) calculation process (S112) are the same as those in the first embodiment.

  As the reference dose Dbase (x, t) and the proximity effect correction coefficient η (x, t) calculation step (S121), the dose D (Ui) calculation unit 43 uses a plurality of proximity effect densities Ui for each position x. The dose D (x, U) (first dose) for each proximity effect density of the electron beam 200 is calculated. The irradiation amount D (Ui) calculation unit 43 calculates the irradiation amount D (x, U) for each proximity effect density Ui, and a proximity effect correction coefficient η (x) that corrects a pattern variation due to the proximity effect and a reference. A set (first set) with the dose Dbase (x) is used. The dose D (Ui) calculation unit 43 is an example of a first dose calculation unit. Here, for each position x, the dose D (x, U) for each proximity effect density Ui may be calculated using Equation (2).

  FIG. 8 is a conceptual diagram for explaining a pair conversion method for each proximity effect density between the proximity effect correction coefficient η (x) and the reference dose Dbase (x) in the second embodiment. As shown in FIG. 8A, for example, in each case of the proximity effect density Ui = 0 (0%), 0.5 (50%), and 1 (100%), the dose D ( x, U) is calculated. At this time, if a set (first set) of the reference dose Dbase (x) at the corresponding position x from the base proximity effect correction coefficient η (x) map and the reference dose Dbase (x) map as a base is used. Good. In this way, each dose D (x, U) at a plurality of discrete proximity effect densities is calculated for each position x.

  Next, the pattern dimension CD (Ui) calculation unit 45 uses the correlation between the pattern dimension CD for each proximity effect density and the dose D of the electron beam 200 for each calculated proximity effect density for each position x. The pattern dimension CD (Ui) for each proximity effect density corresponding to the irradiation dose D (x, U) (first irradiation dose) is calculated. Specifically, the pattern dimension CD (Ui) calculation unit 45 reads the CD-D correlation data 26 indicating the relationship between the pattern dimension CD and the dose D for each proximity effect density from the storage device 143, and calculates the calculated proximity. A pattern dimension CD (x, Ui) corresponding to each dose D (x, U) for each effect density Ui is calculated. In other words, the pattern dimension CD (x, Ui) is obtained for each case of the proximity effect density Ui = 0 (0%), 0.5 (50%), and 1 (100%) for each position x. It is obtained.

  Next, the adding unit 46 uses the pattern dimension variation amount CD (t) resulting from the standing time after drawing to calculate the pattern dimension CD (x, Ui) for each calculated proximity effect density for each position x. In addition, the dimension variation amount CD (t) of the pattern is added. In other words, as shown in FIG. 8B, the adding unit 46 calculates the pattern dimension CD (x, Ui) for each proximity effect density Ui in the dimension variation amount CD (t) calculation step (S112). The dimension variation CD (t) is added.

  Then, the dose D (Ui) calculation unit 47 reads the CD-D correlation data 26 from the storage device 143, and uses the correlation, for each position x, the pattern size CD ( A dose D (x, U, t) (second dose) for each proximity effect density of the electron beam 200 corresponding to x, Ui, t) is calculated. The dose D (Ui) calculation unit 47 is an example of a second dose calculation unit. With this calculation, a pattern in which the dimensional variation amount CD (t) is added for each position x in each case of the proximity effect density Ui = 0 (0%), 0.5 (50%), and 1 (100%). The irradiation dose D (x, Ui, t) corresponding to the dimension CD (x, Ui, t) is obtained.

  Then, as the reference dose Dbase (x, t) and the proximity effect correction coefficient η (x, t) calculation step (S121), the proximity effect correction coefficient and the reference dose calculation unit 50 are as shown in FIG. For each position x, the dose D (x, Ui, t) in each case of Ui = 0 (0%), 0.5 (50%), and 1 (100%) is expressed by the above-described equation (6). Fit. Then, the proximity effect correction coefficient and reference dose calculation unit 50 calculates the proximity effect correction coefficient η (x, x, x) that corrects the dimensional variation due to the proximity effect, which is calculated when fitting for each position x. A set (second set) for each drawing position of t) and the reference dose Dbase (x, t) is acquired. In addition, as described above, correction can be performed well for any proximity effect density U so that processing can be performed regardless of what proximity effect density U region exists in the mesh indicated by x. A set of a reference irradiation amount Dbase (x, t) and a proximity effect correction coefficient h (x, t) is obtained. The proximity effect correction coefficient and reference dose calculation unit 50 is an example of an acquisition unit. Then, it is stored in the storage device 144 as a proximity effect correction coefficient η (x, t) map and a reference dose Dbase (x, t) map for each stripe region 20 that is currently performing data processing. As described above, the proximity effect correction coefficient and reference dose calculation unit 50 performs fitting using the dose calculation formula using the proximity effect correction coefficient and the reference dose as parameters for each position x, and depends on the drawing position. Then, a set for each drawing position of the proximity effect correction coefficient for correcting the dimensional variation due to the proximity effect and the reference irradiation amount is acquired. Then, it is stored in the storage device 144 as a proximity effect correction coefficient η (x, t) map and a reference dose Dbase (x, t) map for each stripe region 20 that is currently performing data processing.

  As described above, the set of the proximity effect correction coefficient η (x) and the reference irradiation amount Dbase (x) as a base is converted, and the pattern size variation amount ΔCD (x) resulting from the loading effect and the resist A set of a proximity effect correction coefficient η (x, t) and a reference irradiation amount Dbase (x, t) that can correct both the dimensional variation CD (t) caused by the elapsed time while maintaining the proximity effect correction. get. The subsequent steps are the same as those in the first embodiment. In other words, the dose calculation unit 56 uses, for each drawing position, an electron beam by using a set for each drawing position of the acquired proximity effect correction coefficient η (x, t) and the reference dose Dbase (x, t). An irradiation amount D (third irradiation amount) of 200 is calculated. The dose calculation unit 56 is an example of a third dose calculation unit. Then, the drawing unit 150 draws a pattern on the sample 101 using an electron beam having a calculated irradiation amount D (third irradiation amount) for each drawing position.

  As described above, according to the second embodiment, the CD-D correlation data 26 indicating the relationship between the pattern dimension CD and the irradiation amount D for each proximity effect density is used, and the loading effect and the like are maintained while maintaining the proximity effect correction. It is possible to obtain a set of the proximity effect correction coefficient and the reference irradiation amount for correcting the dimensional variation due to the global phenomenon and the dimensional variation due to the elapsed time of the drawn resist. Therefore, it is possible to correct the dimensional variation due to the global phenomenon such as the loading effect and the dimensional variation due to the elapsed time of the drawn resist while maintaining the proximity effect correction. As a result, highly accurate drawing can be performed.

Embodiment 3 FIG.
In the first and second embodiments, the set of the proximity effect correction coefficient η (x) and the reference dose Dbase (x) that are the base is converted, but the present invention is not limited to this. In the third embodiment, the dimensional variation due to the elapsed time of the resist drawn by using the correction term without converting the set of the proximity effect correction coefficient η (x) and the reference dose Dbase (x) as a base. Correct the amount.

  FIG. 9 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the third embodiment. In FIG. 9, a tolerance calculator 60 and a correction term calculator 62 are added to the control computer 120 instead of the dose calculator 44 and the proximity effect correction coefficient and reference dose calculator 50. The point where the calculation order of each component in the control computer 120 is changed, and the proximity effect correction coefficient η (x, t) map and the reference dose Dbase (x, t) map for each stripe are stored in the storage device 144. This is the same as FIG. Further, the elapsed time measuring unit 40, the dimensional variation calculating unit 42, the proximity effect density calculating unit 52, the proximity effect correcting dose calculating unit 54, the dose calculating unit 56, the shot data generating unit 58, the tolerance calculating unit 60, and Each function such as the correction term calculation unit 62 may be configured by software such as a program. Alternatively, it may be configured by hardware such as an electronic circuit. Alternatively, a combination thereof may be used. The input data necessary for the control computer 110 or the calculated result is stored in the memory 122 each time.

  FIG. 10 is a flowchart showing main steps of the drawing method according to the third embodiment. In FIG. 10, a reference dose Dbase (x, t) and proximity effect correction coefficient η (x, t) calculation step (S120) and a proximity effect correction dose Dp (η (x, t), U) map creation step ( A point in which a correction term M (U, t) calculation step (S113) and a proximity effect correction dose Dp (η (x, t), U) map creation step (S127) are added instead of S126). And the reference dose Dbase (x, t) and the proximity effect correction coefficient η (x, t) map and the reference dose Dbase (x, t) map after the proximity effect correction coefficient η (x, t) calculation step (S120). 2 is the same as FIG. 2 except that is unnecessary.

  In the third embodiment, contents that are not particularly described are the same as those in the first embodiment. The contents of each process from the pattern input process (S102) to the dimension variation CD (t) calculation process (S112) are the same as those in the first embodiment.

  In the third embodiment, first, a proximity effect correction dose Dp (η (x, t), U) map creation step (S127) is performed. In the proximity effect correction dose Dp (η (x, t), U) map creation step (S127), the proximity effect density calculation unit 52 performs the proximity effect density U () at each position of the stripe region 20 on which data processing is performed. x) is calculated. Then, the proximity effect correction dose calculator 54 calculates the proximity effect correction dose Dp at each position. The proximity effect density U (x) may be obtained by Expression (8). The proximity effect correction dose Dp may be obtained by reading out the corresponding proximity effect correction coefficient η (x) from the base proximity effect correction coefficient η (x) map stored in the storage device 142, and calculating it by Expression (3). A position x from here in the third embodiment indicates each mesh position (coordinate) when the drawing region of the sample to be drawn is meshed at a local position or about 1/10 of the proximity effect distribution radius. . In the proximity effect correction coefficient η (x) map stored in the storage device 142, x indicates a global size mesh coordinate. Here, the global size mesh coordinate including the local small size mesh coordinate described above is used. Refer to the value.

  Then, it is stored in the storage device 144 as a proximity effect correction dose Dp (η (x), U) map for each stripe region 20 on which data processing is performed.

  Next to the proximity effect correction dose Dp (η (x, t), U) map creation step (S127), or the proximity effect correction dose Dp (η (x, t), U) map creation step (S127) In parallel, an elapsed time measurement step (S110) and a dimensional variation CD (t) calculation step (S112) are performed. The contents of the elapsed time measurement step (S110) and the dimension variation CD (t) calculation step (S112) are the same as those in the first embodiment.

  Then, as the correction term M (U, t) calculation step (S113), first, the tolerance calculation unit 60 inputs each tolerance DL (Ui) at a plurality of discrete proximity effect densities from the storage device 143. The tolerance DL (Ui) for each input proximity effect density is plotted with the tolerance DL on the vertical axis and the proximity effect density U on the horizontal axis. Then, the tolerance DL (Ui) for each plotted proximity effect density is fitted, and the tolerance DL (U) for the continuous proximity effect density U is calculated.

  The correction term calculation unit 62 uses the tolerance DL (U) depending on the proximity effect density and the dimensional variation CD (t) of the pattern caused by the standing time after drawing, and the dimensional variation CD (t). A correction term M (U, t) for correcting is calculated. The correction term calculation unit 62 is an example of a correction term calculation unit. The correction term M (U, t) is defined by the following equation (9).

  Then, as the drawing step (S128), the dose calculation unit 56 corrects the pattern variation due to the proximity effect for each drawing position, and the base proximity effect correction coefficient η (x) and the reference dose Dbase (x ) And the correction term M (U, t) and the irradiation amount D (x, U, t) of the electron beam 200 are calculated. Specifically, the proximity effect correction dose Dp (η (x), U) obtained from the base proximity effect correction coefficient η (x), the base reference dose Dbase (x), and the correction term M ( The dose D (x, U, t) is calculated using U, t). The dose D (x, U, t) is defined by the following equation (10). In the reference dose Dbase (x) map stored in the storage device 142, x represents a global size mesh coordinate. Here, the value of the global size mesh coordinate including the local small size mesh coordinate described above is used. Please refer to.

  The subsequent steps are the same as those in the first embodiment. Here, in the third embodiment, the irradiation effect is changed without converting the set of the proximity effect correction coefficient η (x) and the reference irradiation amount Dbase (x) as the base, and thus the proximity effect correction is shifted. However, it is known that there is no problem as explained below.

  FIG. 11 is a diagram showing an example of pattern dimension deviation when drawing is performed by the drawing method according to the third embodiment. FIG. 10A shows a case where the dimension variation amount CD (t) = 0 due to the elapsed time of the drawn resist. In such a case, since the correction term M (U, t) is 1, there is no deviation in the proximity effect correction. Next, FIG. 10B shows a case where the dimensional variation CD (t) = 5 nm caused by the elapsed time of the drawn resist. In such a case, it can be seen that the deviation of the proximity effect correction is within about ± 0.2 nm with respect to the dimensional variation amount CD (t) = 5 nm. Next, FIG. 10C shows a case where the dimension variation amount CD (t) due to the elapsed time of the drawn resist is 10 nm. In such a case, it can be understood that the deviation of the proximity effect correction is within about ± 0.5 nm with respect to the dimensional variation amount CD (t) = 10 nm. In these verification results, the deviation of the proximity effect correction is less than 5% with respect to the dimension variation CD (t), and there is only an error that does not cause a problem even if the correction term M (U, t) is used. It turns out that it does not occur. In addition, since the calculation of the correction term M (U, t) has a small calculation amount, it can be performed at a higher speed than other embodiments.

  As described above, according to the third embodiment, the amount of dimensional variation due to a global phenomenon such as the loading effect while maintaining the proximity effect correction without converting the set of the proximity effect correction coefficient and the reference irradiation amount. And the dimensional variation due to the elapsed time of the drawn resist can be corrected together. As a result, highly accurate drawing can be performed.

  As described above, according to each embodiment, the dimensional variation caused by the global phenomenon such as the loading effect and the elapsed time of the drawn resist while maintaining the proximity effect correction without complicating the data processing. It can be corrected together with the amount.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the first and second embodiments described above, after the drawing process is started, the base proximity effect correction coefficient and the reference dose are converted, but the present invention is not limited to this. Before starting the drawing process, it is also preferable to perform an operation for converting a set of the proximity effect correction coefficient and the reference irradiation amount as a base. In other words, the contents of each step from the pattern input step (S102) in Embodiments 1 and 2 to the reference dose Dbase (x, t) and the proximity effect correction coefficient η (x, t) calculation step (S120) are drawn. You may implement before starting a process.

  In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used. For example, although the description of the control unit configuration for controlling the drawing apparatus 100 is omitted, it goes without saying that the required control unit configuration is appropriately selected and used.

  In addition, all charged particle beam writing apparatuses and methods that include elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Drawing area | region 20 Stripe area | region 22 Tolerance 26 Cd-D correlation data 30 Area density map preparation part 32 Dimension fluctuation amount acquisition part 34 Proximity effect density and reference irradiation amount calculation part 36 Proximity effect density map preparation part 38 Reference irradiation amount map preparation Unit 39 Drawing time prediction unit 40 Elapsed time measurement unit 42 Dimension variation CD calculation units 43, 44, 47 Irradiation amount calculation unit 45 Pattern size calculation unit 46 Addition unit 50 Proximity effect correction coefficient and reference irradiation amount calculation unit 52 Proximity effect density Calculation unit 54 Proximity effect correction dose calculation unit 56 Dose calculation unit 58 Shot data generation unit 60 Tolerance calculation unit 62 Correction term calculation unit 100 Drawing device 101 Sample 102 Electron barrel 103 Drawing chamber 105 XY stage 110, 120 Control computer 112, 122 Memory 130 Deflection control circuit 132 DAC
140, 141, 142, 143, 144, 146 Storage device 150 Drawing unit 160 Control unit 200 Electron beam 201 Electron gun 202 Illumination lens 203 First shaping aperture 204 Projection lens 205 Deflector 206 Second shaping aperture 207 Objective lens 208 Main deflector 209 Sub deflector 212 Blanking deflector 214 Blanking aperture 330 Electron beam 340 Sample 410 First aperture 411 Opening 420 Second aperture 421 Variable shaped opening 430 Charged particle source

Claims (4)

A first set of a proximity effect correction coefficient for correcting pattern variation due to the proximity effect and a reference irradiation amount, and a margin for each proximity effect density that is a coefficient indicating a relationship between the pattern size and the charged particle beam irradiation amount And a first dose calculation unit that calculates a first dose of the charged particle beam for each proximity effect density using a pattern dimensional variation caused by the standing time after drawing,
The first dose for each calculated proximity effect density is a dose that uses the proximity effect correction coefficient and the reference dose as parameters, without using the tolerance and the pattern dimension variation caused by the standing time as parameters. An acquisition unit that performs fitting using an arithmetic expression to acquire a second set for each drawing position of a proximity effect correction coefficient that is dependent on the drawing position and corrects a dimensional variation due to the proximity effect and a reference irradiation amount;
A second irradiation amount calculation unit that calculates a second irradiation amount of the charged particle beam using a second set for each drawing position of the acquired proximity effect correction coefficient and the reference irradiation amount for each drawing position;
A drawing unit that draws a pattern on a sample using a charged particle beam of the second irradiation amount calculated for each drawing position;
A charged particle beam drawing apparatus comprising: A first dose for each proximity effect density of a charged particle beam at a plurality of proximity effect densities is calculated using a first set of a proximity effect correction coefficient that corrects pattern variation due to the proximity effect and a reference dose. A first dose calculator that
Using the correlation between the pattern size for each of the plurality of proximity effect densities and the irradiation amount of the charged particle beam, the pattern size for each proximity effect density corresponding to the calculated first irradiation amount for each proximity effect density is obtained. A pattern dimension calculation unit to be calculated;
An adding unit that adds the dimensional variation amount of the pattern to the calculated pattern size for each proximity effect density using the dimensional variation amount of the pattern caused by the standing time after drawing,
A second dose calculation unit that calculates a second dose for each proximity effect density of the charged particle beam corresponding to the pattern size for each proximity effect density after addition using the correlation;
Fitting the second dose for each calculated proximity effect density using a dose calculation formula using the proximity effect correction coefficient and the reference dose as parameters, and the size variation due to the proximity effect depending on the drawing position An acquisition unit for acquiring a second set for each drawing position of the proximity effect correction coefficient and the reference irradiation amount for correcting
A third dose calculation unit that calculates a third dose of the charged particle beam using a second set for each drawing position of the acquired proximity effect correction coefficient and the reference dose for each drawing position;
A drawing unit that draws a pattern on the sample using a charged particle beam of the calculated third irradiation amount for each drawing position;
A charged particle beam drawing apparatus comprising: A first set of a proximity effect correction coefficient for correcting pattern variation due to the proximity effect and a reference irradiation amount, and a margin for each proximity effect density that is a coefficient indicating a relationship between the pattern size and the charged particle beam irradiation amount And calculating a first irradiation amount of the charged particle beam for each proximity effect density using the dimensional variation amount of the pattern caused by the standing time after drawing,
The first dose for each calculated proximity effect density is a dose that uses the proximity effect correction coefficient and the reference dose as parameters, without using the tolerance and the pattern dimension variation caused by the standing time as parameters. Fitting with an arithmetic expression to obtain a second set for each drawing position of the proximity effect correction coefficient for correcting the dimensional variation due to the proximity effect and the reference irradiation amount depending on the drawing position;
Calculating a second irradiation amount of the charged particle beam using a second set for each drawing position of the acquired proximity effect correction coefficient and the reference irradiation amount for each drawing position;
Drawing a pattern on the sample using a charged particle beam of the calculated second irradiation amount for each drawing position;
A charged particle beam drawing method comprising: The first set for each proximity effect density of the charged particle beam at a plurality of proximity effect densities is used by using the first set for each proximity effect density of the proximity effect correction coefficient for correcting the pattern variation due to the proximity effect and the reference irradiation amount. Calculating the irradiation amount of
Using the correlation between the pattern size for each of the plurality of proximity effect densities and the irradiation amount of the charged particle beam, the pattern size for each proximity effect density corresponding to the calculated first irradiation amount for each proximity effect density is obtained. A process of calculating;
Adding the dimensional variation amount of the pattern to the calculated pattern size for each proximity effect density using the dimensional variation amount of the pattern caused by the standing time after drawing; and
Using the correlation, calculating a second irradiation amount for each proximity effect density of the charged particle beam corresponding to the pattern size for each proximity effect density after the addition; and
Fitting the second dose for each calculated proximity effect density using a dose calculation formula using the proximity effect correction coefficient and the reference dose as parameters, and the size variation due to the proximity effect depending on the drawing position Obtaining a second set for each drawing position of the proximity effect correction coefficient and the reference irradiation amount for correcting
Calculating a third dose of the charged particle beam using a second set for each drawing position of the acquired proximity effect correction coefficient and the reference dose for each drawing position;
Drawing a pattern on the sample using the charged particle beam of the calculated third irradiation amount for each drawing position;
A charged particle beam drawing method comprising:

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