TWI833032B - Exposure device and exposure method - Google Patents

Abstract

In the exposure device, the pattern tilt lines are formed smoothly. In the exposure device 10, the vector data processing circuit 40 converts the vector data of the contour line BD0 into the contour correction vector data BD+ shifted in the ±X direction (outside of the contour line and/or inward direction of the contour line), The original contour vector data BD0 and the contour correction vector data BD+ are alternately used to perform a multiple exposure operation.

Description

Exposure device and exposure method

The present invention relates to an exposure device using an array of light modulation elements to form a pattern, and in particular to a data conversion process for converting vector data into raster data.

In the maskless exposure device, the table with the substrate mounted on it is moved along the scanning direction, while an array of light modulation elements such as DMD (Digital Micro-mirror Device) is used to project pattern light onto the substrate. Here, the light modulation elements (micromirrors, etc.) arranged in a two-dimensional shape are controlled so that the projected pattern corresponds to the position of the projection area (exposure area) on the substrate on which the photoresist layer is formed on the table. Light.

In the exposure device, when vector data (design data) such as CAD/CAM data is input, it is converted into raster data applicable to the light modulation element array. The grid data is bitmap data representing the exposure data of each micromirror, and the projected image of the micromirror is a rectangle. Therefore, when the pattern includes inclined lines, a stepped pattern with a step is formed.

In order to reduce this problem, a method has been proposed in which exposure data representing slanted lines is given multi-step density to each exposure area to smooth the slanted lines (see Patent Document 1). Here, the maximum density is given to the exposed area near the center of the pattern, and the intermediate density is given to the exposed area including a step portion such as an inclined line serving as a pattern boundary line. Moreover, the light intensity for the exposed area of the intermediate concentration is made half of the light intensity for the exposed area of the maximum concentration, thereby forming more stages of inclined lines to improve the resolution. [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2011-65223

For exposure data, the processing of assigning multi-stage density to each exposure area requires an increase in the amount of data and a large-scale data processing circuit compared with the previous method. In addition, the conversion process (correction process) of the raster data is accompanied, so the processing time increases and the throughput decreases.

Therefore, there is a demand for an exposure device that can smoothly form pattern tilt lines without complicating data processing.

The exposure device of the present invention includes: a light modulation element array in which a plurality of light modulation elements are arranged two-dimensionally; a raster data conversion processing unit that converts vector data as pattern data into raster data; and a vector data correction processing unit. The vector data representing the pattern outline is converted into correction vector data (hereinafter referred to as outline correction vector data) that shifts the pattern outline in one direction.

Various settings can be made for shifting the direction of the pattern outline. The raster data conversion processing unit can shift the pattern outline in the direction in which the outline size, pattern size, etc. are expanded (outside), or in the opposite direction (inside). direction) shift. On the substrate, when the main scanning direction and the sub-scanning direction are defined, the grid data conversion processing unit can shift the pattern outline to one direction of the two-dimensional coordinate system. Here, "shifting in one direction" means, for example, when shifting in the sub-scanning direction, including both positive and negative directions.

In the exposure device of the present invention, multiple exposures are performed based on the pattern contour data that has not been shifted and corrected (hereinafter referred to as contour vector data) and the contour correction vector data that has been shifted and corrected. For example, the exposure device may include an exposure control unit that performs multiple exposure operations at a predetermined pitch. The edge portion corresponding to the photosensitive material threshold value of the substrate based on the accumulated exposure amount after multiple exposures follows the data shift amount, so the resolution can be improved.

The vector data correction processing unit can sequentially convert the contour vector data into complex contour correction vector data by a shift amount smaller than the projection area size of the light modulation element. For example, by determining the shift amount corresponding to the resolution in the main scanning direction (including the apparent resolution), the resolution in the sub-scanning direction can be improved through shift correction of vector data. The resolution of the secondary scanning direction is the same as that of the main scanning direction.

The vector data correction processing unit can sequentially convert the contour vector data into contour correction vector data with different shift amounts. For example, the vector data correction processing unit may sequentially convert the contour vector data into contour correction vector data while periodically changing the shift amount.

The vector data correction processing unit converts the contour vector data into positive side correction vector data shifted in one direction (herein, called the positive side), or into the opposite direction of the one direction (herein, called the positive side). Negative side) shifted negative side correction vector data, and the contour vector data can be converted while shifting to the positive side and negative side in sequence. The exposure device performs multiple exposures based on the contour vector data, the positive side correction vector data, and the negative side correction vector data.

Another aspect of the exposure method of the present invention is an exposure method that converts vector data as pattern data into raster data corresponding to the projection area of the light modulation element, and performs multiple exposures based on the raster data. Its characteristics It consists in: converting the contour vector data representing the pattern contour, into contour correction vector data after shifting the pattern contour in one direction, combining the exposure based on the contour vector data and the exposure based on the contour correction vector data Multiple exposures later. By shifting the amount below the size of the projection area of the light modulation element along the main scanning direction, the contour vector data can be converted into contour correction vector data, or the contour vector data can be converted into contour line vector data in the corresponding sub-scanning direction. Sub-scan direction correction vector data shifted in the direction of the aiming direction. [Effects of the invention]

When according to the present invention, in the exposure device, the pattern tilt lines can be formed smoothly.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a block diagram of the exposure device of this embodiment.

The exposure device 10 is a maskless exposure device that irradiates light onto a substrate (exposure object) W coated or pasted with a photosensitive material such as a photoresist, thereby forming a pattern. It is provided as a table 12 carrying the substrate W. Can be moved along the main scanning direction. The table driving mechanism 15 moves the table 12 along the main scanning direction X and the sub-scanning direction Y.

The exposure device 10 includes a DMD 22, an illumination optical system 23, and a projection optical system 25, and is provided with a plurality of exposure heads 18 for projecting pattern light (in FIG. 1, only one exposure head is shown). The light source 20 is constituted by, for example, a discharge lamp, and is driven by the light source driving unit 21 .

The CAD/CAM data as pattern data is input to the exposure device 10 as vector data. In the controller 30 of the exposure device 10, the vector data represented by the drawing coordinate system is converted into an exposure coordinate system unique to the exposure device 10, and is sent to the vector data processing circuit (vector data correction processing unit). The exposure coordinate system is defined along the main scanning direction X and the auxiliary scanning direction Y of the exposure device.

In the vector data processing circuit 40 , vector data (in the exposure coordinate system) corresponding to the predetermined exposure range is extracted and sent to the raster data conversion circuit (grid data conversion processing unit) 26 . In addition, as described below, data correction processing is performed on part of the vector data.

In the raster data conversion circuit 26, the vector data is converted into raster data and stored in a unit size memory (not shown) corresponding to the projection area (unit exposure area, also called a cell) of a micromirror. Furthermore, it is converted into lattice data in units of areas (hereinafter, referred to as subcells) below the cell size. According to the control signal from the controller 30, the dot matrix data at the predetermined address is read from the grid data conversion circuit 26, and is sent to the DMD driving circuit 24 as exposure data.

DMD22 is a two-dimensional light modulation element array of tiny micromirrors. Each micromirror selectively switches the direction of light reflection by changing its posture. The posture of each mirror is controlled by the DMD drive circuit 24, whereby the light corresponding to the pattern is projected (imaged) onto the surface of the substrate W through the projection optical system 25.

The table driving mechanism 15 moves the table 12 in accordance with the control signal from the controller 30 . The controller (exposure control unit) 30 controls the operation of the exposure device 10 and outputs control signals to the table drive mechanism 15, the DMD drive circuit 24, and the vector based on the table position information from the position detection unit (not shown). Data processing circuit 40, etc. During the exposure operation, the table 12 moves at a certain speed, and the entire projection area of the DMD 22 (hereinafter referred to as the exposure area) moves relatively on the substrate W along the main scanning direction X along with the movement of the substrate W. . Furthermore, the table 12 may move intermittently instead of continuously moving.

The controller 30 controls the vector data processing circuit 40, the DMD drive circuit 24, etc., to perform multiple exposures, that is, perform superimposed exposures of the next exposure in sequence at a position that overlaps a part of the previous exposure area. The exposure action is executed according to the predetermined pitch interval. If each micromirror of the DMD22 is modulated according to the relative position of the exposure area (table position), the light of the pattern that must be drawn at the position of the exposure area is Projection in sequence.

The projection area made by each exposure head 18, that is, the projection area (hereinafter referred to as the exposure area) EA of the entire DMD 22, is an area that is only tilted at a slight angle with respect to the main scanning direction X. In this state, move relatively in the main scanning direction X. Thereby, the exposure point (exposure shooting center position) is slowly shifted along the sub-scanning direction Y.

The pitch interval of the multiple exposure action is set so as to deviate from an integer multiple of the unit exposure area, and the displacement amount along the sub-scanning direction Y is also smaller than the unit exposure area. Therefore, in the unit exposure area, a large number of exposure points are distributed in both the main scanning direction X and the sub-scanning direction Y, so that a pattern can be formed with a resolution below the unit exposure area.

Furthermore, in this embodiment, the main scanning direction , improve the apparent resolution. This is explained in detail below.

FIG. 2 is a diagram showing a correction process for vector data of a part of a pattern outline. In Figure 2, it is represented by the exposure coordinate system (X-Y).

Vector data is vector data defined by the two-dimensional coordinates of the starting point and the end point of the outline of the pattern data (graphic data), and is defined in the representation unit of the drawing data (for example, 1 μm). Here, the vector data representing the partial outline line BD0 of the pattern is expressed by the position coordinates of the points P1 to P4.

As described above, in the raster data conversion circuit 26, the vector data of the contour line BD0 is converted into the raster data RD as dot matrix data in sub-cell units. The grid data RD0 is expressed as dividing the unit size C (unit exposure area) of the micromirror by n along the main scanning direction X and the sub-scanning direction Y (n is an integer, here, n = 16) sub-cell, which is used as a unit to arrange the lattice data, resulting in a step-like drop in the outline part T. Regarding the main scanning direction X, the resolution of 1/2 sub-cell unit is achieved by adjusting the pitch interval of the exposure action.

In the multiple exposure operation, repeated exposure is performed based on the vector data of the pattern that must be formed on the substrate W. However, here, the vector data under shift correction and the original vector data are sequentially transmitted to the grid. Data conversion circuit 26. That is, in each exposure step of the multiple exposure operation, the exposure data based on the shift-corrected vector data and the exposure data based on the unshifted vector data are alternately used. to exposure.

In the vector data processing circuit 40, first, the vector data of the contour line BD0 is extracted without correction (step 1). In the next exposure operation, after extracting the processed vector data, the vector data of the contour line BD0 is subjected to coordinate conversion processing, and is converted (corrected) along the sub-scanning direction Y and shifted by a predetermined shift amount ΔS. The vector data of the contour line BD+ (contour line correction vector data).

When the sub-unit size is expressed as SC, the shift amount ΔS is equivalent to the distance of 1/2×SC along the sub-scanning direction Y. As shown in Figure 2, the contour line BD+ is toward the outside of the contour line BD0, that is, the line is moved parallel from the pattern boundary line to the outside of the pattern. The distance D between the contour line BD0 and the contour line BD+ is smaller than the unit size. C and sub-unit size SC. The vector data of the contour line BD+ is expressed by the position coordinates P1’~P4’. The vector data of the contour line BD+ is converted into the raster data RD+. Therefore, the stepped contour line T+ of the raster data RD+ is also shifted overall to the sub-scanning direction Y by only shifting the sub-unit size 1/2×SC. (Step 2).

In the multiple exposure operation, although the exposure operation is performed in the same exposure area according to a predetermined number of exposures (for example, dozens of times), during this period, steps 1 and 2 are repeated. This processing is performed not only for the vector data of the contour line BD0 shown in FIG. 2, but for all vector data. However, it is also possible to represent only inclined lines that are not parallel in the X direction and the Y direction with respect to the exposure coordinate system X-Y. The vector data of the curve is performed.

FIG. 3 is a diagram showing the exposure amount along the sub-scanning direction Y. Figure 4 is a diagram showing the position of the line in the Y direction of Figure 3. However, in FIG. 4 , the sub-cell size SC is divided into four parts of the cell size C for convenience of explanation.

In FIG. 3 , the exposure amount along the line AB in FIG. 4 (especially, between the position (1) and the position (2) in the Y direction) is shown. The photosensitive material formed on the substrate W is exposed to light with an exposure amount above the threshold, and the area above the threshold appears as a pattern. As mentioned above, the exposure area of DMD22 is tilted at a slight angle relative to the main scanning direction . Therefore, when exposure is performed based on the vector data of the contour line BD0, the exposure amount M0 is represented by the line shown in Figure 3, which has a certain inclination and decreases toward the outside of the pattern.

In addition, when exposure is performed based on the vector data of the contour line BD+, the exposure amount M+ also has a certain inclination, becoming a line that decreases toward the outside of the pattern, and becomes, relative to the exposure amount M0, in the sub-scanning direction. On Y, only shift the line by 1/2×SC. As a result, the exposure M after combining the exposure M0 and the exposure M+ becomes a line with a constant slope near the threshold value, and its slope is substantially equal to the slope of the exposure M0 and the exposure M+.

As a result, the contour line (edge) EL along the X direction is not formed at the end edge position of the sub-cell, but is formed inside the sub-cell, realizing pattern formation with a resolution of 1/2×SC. The exposure pitch interval along the sub-scanning direction Y does not change. In appearance, the resolution in the sub-scanning direction Y is 1/2×SC, which is the same as the apparent resolution in the main scanning direction X. The resolutions are equal.

Figure 5 is a diagram showing the pattern obtained after exposure, development, etc. steps. As shown in FIG. 5 , the inclined line PL of the pattern P is formed with a resolution of less than or equal to the sub-cell size SC, and becomes a line in which the drop is suppressed.

In this way, according to this embodiment, in the exposure device 10 , the vector data processing circuit 40 converts the vector data of the contour line BD0 into the ±Y direction (outside of the contour line and/or inward direction of the contour line). The shifted contour line correction vector data BD+ alternately uses the original contour line vector data BD0 and the contour line correction vector data BD+ to create exposure data and perform a multiple exposure operation.

Generally speaking, the smoothness of the pattern formed is proportional to the resolution of the lattice data of the sub-cell unit, that is, to the scale of the cell-size memory. However, by correcting the vector data as described above, a smooth pattern can be formed while suppressing the size of the cell-size memory. That is to say, the inclined lines of the pattern can be smoothed through simple calculation processing without complicated and large-scale circuit scale. Furthermore, by reducing the number of exposures of the vector data of the original contour line to less than half of the number of multiple exposures, the edges of the pattern can be made clearer.

In this embodiment, the shift amount of the vector data of the contour line is one, and the vector data of the uncorrected contour line is used alternately to perform the multiple exposure operation. However, different shift amounts may also be used. , to create complex shift correction vector data, which are used sequentially to perform multiple exposure operations. Alternatively, the vector data of the contour line may be shifted not in the positive direction (+Y) side of the sub-scanning direction Y, but in the negative (negative) direction (-Y). Moreover, the vector data of a contour line can also be shifted and corrected in both positive and negative directions.

FIG. 6 is a diagram showing a modified example of vector data correction processing using a complex shift amount.

Here, for the vector data of the contour line BD0, the vector data of the contour line BD+ is generated by shifting it by only 1/2×SC (=ΔS) in the +Y direction, and also shifting it by SC (=Δ2S) in the +Y direction. The vector data of the contour line BD2+, and the vector data of the contour line BD- shifted only by 1/2×SC (=ΔS) in the -Y direction. Moreover, the vector data of the contour lines BD0, BD+, BD2+, and BD- are repeatedly used in order to perform multiple exposure operations. This can form a pattern with a smoothness equivalent to 1/64 of the number of cell divisions.

Alternatively, the vector data of the contour line BD0 may be generated by shifting the vector data of the contour line BD0 by only 1/2×SC (=ΔS) in the +Y direction, and by shifting the vector data of the contour line BD0 by only 1/2×SC in the −Y direction. The vector data of the contour line BD- after (=ΔS) is used sequentially to repeatedly use the vector data of the three contour lines while performing a multiple exposure operation. When this multiple exposure operation is performed, the uncorrected vector data of the original contour becomes the number of exposures that is less than half of the number of multiple exposures used.

Moreover, when a complex shift amount is used, a reference table representing the shift amount can also be stored in a memory. The controller 30 uses the reference table to control the vector data processing circuit 40 to sequentially convert the vector data of the contour line. In addition, the conversion (correction) processing of vector data may also be performed by other circuits such as the controller 30. Regarding the sub-cell size SC, the unit size C can also be divided into divisions other than 16 in accordance with the scale of the cell-size memory.

In this embodiment, correction processing is performed to shift the vector data of the contour line along the sub-scanning direction Y. However, the present invention is not limited to this, and may also be performed within the expressible range of the vector data. Shift in a predetermined one-way direction. In addition, the structure of the correction processing of vector data may also be performed by an arithmetic processing unit other than the exposure device.

10:Exposure device 22:DMD (light modulation element array) 30:Controller 40: Vector data processing circuit (vector data correction processing section)

[Fig. 1] is a block diagram of the exposure device of this embodiment. [Fig. 2] is a diagram showing the correction process of the vector data of a part of the pattern outline. [Fig. 3] is a diagram showing the exposure amount along the sub-scanning direction Y. [Fig. 4] is a diagram showing the position of the line in the Y direction of Fig. 3. [Figure 5] is a diagram showing the pattern obtained after exposure, development, etc. steps. [Fig. 6] is a diagram showing a modification of the correction process of vector data.

Claims (10)

An exposure device, which includes: a light modulation element array that arranges a plurality of light modulation elements in two dimensions; a projection optical system that projects light corresponding to the posture of the corresponding light modulation elements onto a substrate; and a grid data conversion processing unit that The vector data as the pattern data is converted into raster data corresponding to the projection area of the light modulation elements made by the projection optical system; and the vector data correction processing unit makes the contour vector representing the contour of the pattern data The data is converted into contour correction vector data that shifts the contour line in one direction, and the light modulation elements are modulated according to the converted raster data of the contour vector data and the contour correction vector data respectively. , perform multiple exposures on the substrate. The exposure device of claim 1, wherein the vector data correction processing unit sequentially converts the contour vector data into the contour correction vector data using different shift amounts. The exposure device of claim 2, wherein the vector data correction processing unit sequentially converts the contour vector data into the contour correction vector data while periodically changing the shift amount. The exposure device of claim 3, wherein the vector data correction processing unit sequentially converts the contour vector data into positive side correction vector data shifted to the positive side of one direction, and then to the negative side of the one direction. The negative side correction vector data after side shifting is subjected to multiple exposures on the substrate based on the contour vector data, the positive side correction vector data and the negative side correction vector data. The exposure device of claim 4, wherein the vector data correction processing unit sequentially converts the contour vector data into complex data using the shift amount below the projection area size of the light modulation elements. Count the contour correction vector data. Such as the exposure device of claim 5, wherein the displacement amount is a displacement amount corresponding to the resolution of the main scanning direction. The exposure device of any one of claims 1 to 6, wherein the vector data correction processing unit converts the contour vector data into a sub-scanning direction correction vector shifted in the direction corresponding to the sub-scanning direction. data. An exposure method that converts vector data as pattern data into raster data corresponding to the projection area of a light modulation element, and performs multiple exposures based on the raster data. It is characterized in that: a contour line representing the pattern data is The contour vector data is converted into contour correction vector data after shifting the contour line in one direction, and the exposure of the converted raster data based on the contour vector data is combined with the contour correction vector data. Multiple exposure after exposure of converted raster data. The exposure method of claim 8, wherein the contour vector data is converted into the contour correction vector data by a shift amount below the projection area size of the light modulation elements along the main scanning direction. The exposure method of claim 8 or 9, wherein the contour vector data is converted into sub-scanning direction correction vector data shifted in the direction corresponding to the sub-scanning direction.

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