JP2021157000A - Exposure apparatus and exposure method - Google Patents

Abstract

To provide a method of smoothly forming a pattern gradient line in an exposure apparatus.SOLUTION: In an exposure apparatus, a vector data processing circuit converts the vector data of contour BD0 into contour corrected vector data BD + shifted to ± X direction (outside the contour line and/or the inner side of the contour), and the multi exposure operation is performed using the original contour vector data BD0 and the contour correcting vector data BD + alternately.SELECTED DRAWING: Figure 2

Description

The present invention relates to an exposure apparatus that forms a pattern using an light modulation element array, and more particularly to a data conversion process from vector data (also referred to as vector data) to raster data.

In a maskless exposure apparatus, pattern light is projected onto a substrate by an optical modulation element array such as a DMD (Digital Micro-mirror Device) while moving a stage on which the substrate is mounted along a scanning direction. There, light modulation elements (micromirrors) mounted in a two-dimensional manner so as to project pattern light according to the position of the projection area (exposure area) on the substrate on which the photoresist layer is formed. Etc.) to control.

When vector data (design data) such as CAD / CAM data is input in the exposure apparatus, it is converted into raster data applicable to the light modulation element array. The raster data is bitmap data representing the exposure data of each micromirror, and the projected image of the micromirror has a rectangular shape. Therefore, when the pattern includes an inclined line, a stepped pattern with a step is formed.

In order to reduce this, a method has been proposed in which the exposure data representing the inclined line is given a multi-step density for each exposure region to smooth the inclined line (see Patent Document 1). There, 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 of the stepped portion including the inclined line which is the pattern boundary line. Then, by reducing the light intensity for the exposure region of the intermediate density to half the light intensity for the exposure region of the maximum density, a more multi-step inclined line is formed to improve the resolution.

Japanese Unexamined Patent Publication No. 2011-65223

The process of imparting multi-step densities to the exposure data for each exposure region increases the amount of data as compared with the conventional case, and requires a large-scale data processing circuit. In addition, since raster data conversion processing (correction processing) is separately involved, the processing time increases and the throughput decreases.

Therefore, in the exposure apparatus, it is required to smoothly form the pattern slope line without complicating the data processing.

The exposure apparatus of the present invention includes an optical modulation element array in which a plurality of light modulation elements are arranged in two dimensions, a raster data conversion processing unit that converts vector data that is pattern data into raster data, and a vector that represents a pattern contour line. It is provided with a vector data correction processing unit that converts the data into correction vector data (hereinafter referred to as contour line correction vector data) in which the pattern contour line is shifted along one direction.

The direction in which the pattern contour line is shifted can be set in various ways, and the raster data conversion processing unit shifts the pattern contour line contour size, pattern size, etc. in the direction of expansion (outside) or vice versa (inside direction). It is possible to make it. When the main scanning direction and the sub-scanning direction are defined on the substrate, the raster data conversion processing unit can shift the pattern contour line in one direction of the two-dimensional coordinate system. Here, "shifting along one direction" includes, for example, both positive and negative directions when shifting in the sub-scanning direction.

In the exposure apparatus of the present invention, multiple exposure is performed based on the pattern contour line data that has not been shift-corrected (hereinafter referred to as contour line vector data) and the shift-corrected contour line correction vector data. For example, the exposure apparatus can include an exposure control unit that executes a multiple exposure operation at a predetermined pitch. Since the edge portion corresponding to the photosensitive material threshold value of the substrate based on the integrated exposure amount after the multiple exposure follows the data shift amount, the resolution can be improved.

The vector data correction processing unit can sequentially convert the contour line vector data into a plurality of contour line correction vector data with a shift amount equal to or less than the projection area size of the light modulation element. For example, by setting the shift amount to the shift amount according to the resolution in the main scanning direction (including the apparent resolution), the resolution in the sub-scanning direction is corrected by shifting the vector data, and the resolution in the sub-scanning direction is the main scanning. It is possible to increase the resolution to the same level as the direction.

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

The vector data correction processing unit shifts the contour line vector data to the positive side correction vector data shifted in one direction (here, referred to as the positive side) or the negative side shifted to the opposite direction (here referred to as the negative side). It is possible to convert to correction vector data, and it is also possible to convert contour line vector data while shifting in order from the positive side to the negative side. The exposure apparatus performs multiple exposure based on the contour line vector data, the positive side correction vector data, and the negative side correction vector data.

The exposure method according to another aspect of the present invention is an exposure method in which vector data, which is pattern data, is converted into raster data corresponding to the projection area of the optical modulation element, and multiple exposures are performed based on the raster data. The contour line vector data representing the pattern contour line is converted into the contour line correction vector data in which the pattern contour line is shifted in one direction, and the exposure based on the contour line vector data and the exposure based on the contour line correction vector data are combined. Multiple exposures are performed. The contour line vector data is converted into contour line correction vector data or the contour line vector data is shifted in the direction according to the sub scanning direction according to the shift amount equal to or less than the projection area size of the optical modulation element along the main scanning direction. It can be converted into the sub-scanning direction correction vector data.

According to the present invention, the pattern inclination line can be smoothly formed in the exposure apparatus.

It is a block diagram of the exposure apparatus which is this embodiment. It is a figure which showed the correction processing of the vector data for some pattern contour lines. It is a figure which showed the exposure amount along the sub-scanning direction Y. It is a figure which showed the position of the Y direction line of FIG. It is a figure which showed the pattern obtained through the post-process such as exposure and development. It is a figure which illustrated the modification of the correction processing of vector data.

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

FIG. 1 is a block diagram of the exposure apparatus according to the present embodiment.

The exposure apparatus 10 is a maskless exposure apparatus that forms a pattern by irradiating a substrate (exposure target) W to which a photosensitive material such as a photoresist is applied or attached with light, and a stage 12 on which the substrate W is mounted is provided. It is installed so that it can be moved along the main scanning direction. The stage drive mechanism 15 moves the stage 12 along the main scanning direction X and the sub-scanning direction Y.

The exposure apparatus 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 (only one exposure head is shown in FIG. 1). The light source 20 is composed of, for example, a discharge lamp, and is driven by the light source driving unit 21.

The CAD / CAM data, which is the pattern data, is input to the exposure apparatus 10 as vector data. In the controller 30 of the exposure apparatus 10, the vector data represented by the drawing coordinate system is converted into the exposure coordinate system peculiar to the exposure apparatus 10 and 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 sub-scanning direction Y of the exposure apparatus.

In the vector data processing circuit 40, vector data (of the exposure coordinate system) corresponding to a predetermined exposure range is extracted and transmitted to the raster data conversion circuit (raster data conversion processing unit) 26. Further, as will be described later, data correction processing is performed on some vector data.

In the raster data conversion circuit 26, vector data is converted into raster data, stored in a cell size memory (not shown) corresponding to a projection area (unit exposure area, also referred to as a cell) of one micromirror, and then a cell. It is converted into bitmap data in units of areas (hereinafter referred to as subcells) that are smaller than the size. Bitmap data at a predetermined address is read from the raster data conversion circuit 26 according to the control signal from the controller 30, and is sent to the DMD drive circuit 24 as exposure data.

The DMD 22 is a light modulation element array in which micromicromirrors are arranged two-dimensionally, and each micromirror selectively switches the light reflection direction by changing its posture. By controlling the attitude of each mirror by the DMD drive circuit 24, light corresponding to the pattern is projected (imaged) on the surface of the substrate W via the projection optical system 25.

The stage drive mechanism 15 moves the stage 12 according to a control signal from the controller 30. The controller (exposure control unit) 30 controls the operation of the exposure device 10, and based on the stage position information sent from the position detection unit (not shown), the stage drive mechanism 15, the DMD drive circuit 24, and vector data. A control signal to the processing circuit 40 or the like is output. During the exposure operation, the stage 12 moves at a constant speed, and the projection area of the entire DMD 22 (hereinafter referred to as an exposure area) moves relative to the substrate W along the main scanning direction X as the substrate W moves. The stage 12 may move intermittently instead of continuously moving.

The controller 30 controls the vector data processing circuit 40, the DMD drive circuit 24, and the like, and executes multiple exposure, that is, overlap exposure in which the next exposure is sequentially performed at a position overlapping a part of the previous exposure area. The exposure operation is executed according to a predetermined pitch interval, and by modulating each micromirror of the DMD 22 according to the relative position (stage position) of the exposure area, the light of the pattern to be drawn at the position of the exposure area is sequentially projected.

The projection area by each exposure head 18, that is, the projection area (hereinafter referred to as the exposure area) EA of the entire DMD 22 is a region inclined by a small angle with respect to the main scanning direction X, and moves relative to the main scanning direction X in the inclined state. Let me. As a result, the exposure point (exposure shot center position) is gradually shifted along the sub-scanning direction Y.

The pitch interval of the multiple exposure operation is set so as to deviate from an integral multiple of the unit exposure region, and the shift amount along the sub-scanning direction Y is also smaller than the unit exposure region. Therefore, a large number of exposure points are distributed in both the main scanning direction X and the sub-scanning direction Y within the unit exposure region, and it is possible to form a pattern with a resolution equal to or less than the unit exposure region.

Further, in the present embodiment, the apparent resolution is improved by adjusting the pitch interval of the multiple exposure operation with respect to the main scanning direction X, while the apparent resolution is improved by correcting the vector data with respect to the sub-scanning direction Y. I'm letting you. This will be described in detail below.

FIG. 2 is a diagram showing correction processing of vector data for a part of pattern contour lines. In FIG. 2, it is represented by the exposure coordinate system (XY).

The vector data is vector data defined by the two-dimensional coordinates of the start point and the end point of the contour line of the pattern data (graphic data), and is defined by the expression unit of the drawing data (for example, 1 μm). Here, the vector data representing the partial contour line BD0 of the pattern is represented 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 raster data RD, which is bitmap data for each subcell. Raster data RD0 is a bit in which the cell size C (unit exposure area) of the micromirror is divided into n along the main scanning direction X and the sub scanning direction Y (n is an integer, in this case n = 16) and arranged in units of subcells. It is represented as map data, and a step-like step is formed in the contour portion T thereof. With respect to the main scanning direction X, the resolution in units of 1/2 subcell is realized by adjusting the pitch interval of the exposure operation.

In the multiple exposure operation, repeated exposure is performed based on the vector data of the pattern to be formed on the substrate W. Here, the vector data under shift correction and the original vector data are sequentially sent to the raster data conversion circuit 26. That is, for each exposure step of the multiple exposure operation, the exposure data created based on the shift-corrected vector data and the exposure data created based on the unshifted vector data are alternately used for 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 the vector data extraction processing, the vector data of the contour line BD0 is subjected to the coordinate conversion processing, and the vector data of the contour line BD + shifted by a predetermined shift amount ΔS along the sub-scanning direction Y. Convert (correct) to (contour line correction vector data).

When the subcell size is expressed by SC, the shift amount ΔS corresponds to a distance of 1/2 × SC along the subscan direction Y. As shown in FIG. 2, the contour line BD + is a line moved parallel to the outside of the contour line BD0, that is, from the pattern boundary line to the outside of the pattern, and the distance interval D between the contour line BD0 and the contour line BD + is It is smaller than the cell size C and the subcell size SC. The vector data of the contour line BD + is represented by the position coordinates P1'to P4'. Since the vector data of the contour line BD + is converted into the raster data RD +, the stepped contour line T + of the raster data RD + is also shifted as a whole in the sub-scanning direction Y by the subcell size 1/2 × SC (Step 2). ).

In the multiple exposure operation, the exposure operation is performed on the same exposure area according to a predetermined number of exposures (for example, several tens of times), during which Step1 and Step2 are repeatedly performed. This processing is performed not only on the vector data of the contour line BD0 shown in FIG. 2 but also on all the vector data. However, it may be performed only for vector data representing slope lines / curves that are not parallel to the X direction and the Y direction with respect to the exposure coordinate system XY.

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

FIG. 3 shows the exposure amount along the lines AB of FIG. 4 (particularly, between the position (1) and the position (2) in the Y direction). The photosensitive material formed on the substrate W is exposed to an exposure amount equal to or higher than the threshold value, and a region equal to or higher than the threshold value appears as a pattern. As described above, the exposure area of the DMD 22 is tilted by a small angle with respect to the main scanning direction X, and the exposure points are shifted to the sub-scanning direction Y at pitch intervals equal to or less than the cell size during the multiple exposure operation. Therefore, when exposure is performed based on the vector data of the contour line BD0, the exposure amount M0 is represented as a line shown in FIG. 3, and decreases toward the outside of the pattern with a constant inclination.

On the other hand, when the exposure is performed based on the vector data of the contour line BD +, the exposure amount M + becomes a line that similarly decreases toward the outside of the pattern with a constant inclination, and is in the sub-scanning direction Y with respect to the exposure amount M0. The line is shifted by 1/2 x SC. As a result, the exposure amount M, which is the sum of the exposure amount M0 and the exposure amount M +, becomes a line having a constant slope near the threshold value, and the slope is substantially equal to the slopes of the exposure amount M0 and the exposure amount M +.

As a result, the contour line (edge) EL along the X direction is formed inside the subcell instead of the end edge position of the subcell, and pattern formation with a resolution of 1/2 × SC is realized. The exposure pitch interval along the sub-scanning direction Y is not changed, and the apparent resolution of the sub-scanning direction Y is 1/2 × SC, which is equal to the apparent resolution of the main scanning direction X.

FIG. 5 is a diagram showing a pattern obtained through post-processes such as exposure and development. As shown in FIG. 5, the inclined line PL of the pattern P is formed with a resolution equal to or less than the subcell size SC, and is a line in which a step is suppressed.

As described above, according to the present embodiment, in the exposure apparatus 10, the vector data processing circuit 40 shifts the vector data of the contour line BD0 in the ± Y direction (outside the contour line and / or inside the contour line). It is converted into contour line correction vector data BD +, exposure data is created by alternately using the original contour line vector data BD0 and contour line correction vector data BD +, and multiple exposure operations are performed.

In general, the smoothness of the formed pattern is proportional to the resolution of the bitmap data in subcell units, that is, the size of the cell size memory. However, by correcting the vector data described above, smooth pattern formation becomes possible while suppressing the scale of the cell size memory. That is, the slope line of the pattern can be smoothed by a simple arithmetic process without increasing the circuit scale and the size. By reducing the number of exposures of the vector data of the original contour line to half or less of the number of multiple exposures, the edge portion of the pattern can be made clearer.

In the present embodiment, the shift amount of the contour line vector data is set as one, and the multiple exposure operation is performed by alternately using the uncorrected contour line vector data, but a plurality of shift correction vector data with different shift amounts. May be created and used in order to perform a multiple exposure operation. Further, 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 reverse (negative) direction (−Y). Further, the vector data of one contour line may be shift-corrected in both positive and negative directions.

FIG. 6 is a diagram showing a modified example in which vector data correction processing is performed with a plurality of shift amounts.

Here, with respect to the vector data of the contour line BD0, the vector data of the contour line BD + shifted in the + Y direction by 1/2 × SC (= ΔS), and the contour line BD2 + shifted in the + Y direction by only SC (= Δ2S). Vector data of contour line BD − shifted in the −Y direction by 1/2 × SC (= ΔS) is generated. Then, the multiple exposure operation is performed by repeatedly using the vector data of the contour lines BD0, BD +, BD2 +, and BD− in this order. Thereby, a smooth pattern corresponding to the number of cell divisions of 1/64 can be formed.

Further, the vector data of the contour line BD + shifted in the + Y direction by 1/2 × SC (= ΔS) with respect to the vector data of the contour line BD0 and the vector data of the contour line BD + shifted in the −Y direction by 1/2 × SC (= ΔS). The vector data of the contour line BD− may be generated, and the multiple exposure operation may be performed while repeatedly using the vector data of the three contour lines in order. According to such a multiple exposure operation, the vector data of the original contour line that is not corrected is used for the number of exposures that is half or less of the number of multiple exposures.

When a plurality of shift amounts are used, a reference table representing the shift amount is stored in a memory or the like, and the controller 30 controls the vector data processing circuit 40 using the reference table to sequentially convert the vector data of the contour line. You may do it. Further, the vector data conversion (correction) processing may be performed by another circuit such as the controller 30. Regarding the subcell size SC, the cell size C may be divided by a number of divisions other than 16 divisions according to the scale of the cell size memory.

In the present embodiment, the correction process for shifting the vector data of the contour line along the sub-scanning direction Y is performed, but the present invention is not limited to this, and the vector data is in a predetermined one direction within the expressible range of the vector data. It may be shifted along. Further, the vector data correction process may be configured to be performed by an arithmetic processing unit other than the exposure apparatus.

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

Claims (10)

An optical 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, which is pattern data, into raster data,
It is provided with a vector data correction processing unit that converts vector data representing a pattern contour line into contour line correction vector data in which the pattern contour line is shifted along one direction.
An exposure apparatus characterized in that multiple exposures are performed based on contour line vector data and contour line correction vector data. The exposure apparatus according to claim 1, wherein the vector data correction processing unit sequentially converts contour line vector data into contour line correction vector data with different shift amounts. The exposure apparatus according to claim 1 or 2, wherein the vector data correction processing unit sequentially converts contour line vector data into contour line correction vector data while periodically changing the shift amount. The vector data correction processing unit sequentially converts the contour line vector data into positive side correction vector data shifted to the positive side in one direction and negative side correction vector data shifted to the negative side in the one direction.
The exposure apparatus according to any one of claims 1 to 3, wherein multiple exposures are performed based on the contour line vector data, the positive side correction vector data, and the negative side correction vector data. Any of claims 1 to 4, wherein the vector data correction processing unit sequentially converts contour line vector data into a plurality of contour line correction vector data with a shift amount equal to or less than the projection area size of the light modulation element. The exposure device described in Crab. The exposure apparatus according to claim 5, wherein the shift amount is a shift amount according to the resolution in the main scanning direction. The exposure according to any one of claims 1 to 6, wherein the vector data correction processing unit converts the contour line vector data into sub-scanning direction correction vector data shifted in a direction corresponding to the sub-scanning direction. Device. Vector data, which is pattern data, is converted into raster data corresponding to the projection area of the light modulation element.
An exposure method that performs multiple exposures based on raster data.
The contour line vector data representing the pattern contour line is converted into the contour line correction vector data in which the pattern contour line is shifted in one direction.
An exposure method characterized by performing multiple exposures in which exposure based on contour line vector data and exposure based on contour line correction vector data are combined. The exposure method according to claim 8, wherein the contour line vector data is converted into the contour line correction vector data by a shift amount equal to or less than the projection area size of the light modulation element along the main scanning direction. The exposure method according to claim 8 or 9, wherein the contour line vector data is converted into sub-scanning direction correction vector data shifted in a direction corresponding to the sub-scanning direction.

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