JP7214452B2 - Photomask manufacturing method - Google Patents

Description

The present invention relates to a photomask manufacturing method. Specifically, the present invention relates to a method for manufacturing a photomask, particularly a multi-tone mask, using a photomask drawing apparatus using a DMD (digital micromirror device).

When manufacturing a photomask used in a lithography process in the manufacturing process of a display device, a semiconductor device, etc., in order to draw a desired pattern on a photoresist on a photomask blank, for example, drawing as described in Patent Documents 1 and 2 is used. Device is in use.

Principal processes for manufacturing a halftone mask (three-tone photomask) using such a known drawing apparatus will be described below.
22A to 22C are process cross-sectional views showing a method of manufacturing a typical bottom-half type multi-tone mask.
First, a photomask blank is prepared in which a semi-transmissive film 101 such as Mosilicide (MoSi) and a light shielding film 102 such as chromium (Cr) are formed in this order on a transparent substrate 100 such as quartz. 22(A), a photoresist 103 is formed by a coating method or the like.
Next, the photoresist 103 is exposed by a drawing device and developed to form a photoresist pattern 103a (FIG. 22(B)).
Next, the light shielding film 102 is etched using the photoresist pattern 103a as a mask to form the light shielding film pattern 102a (FIG. 22C). A pattern 101a is formed (FIG. 22(D)).
Next, the photoresist pattern 103a is removed by ashing or the like (FIG. 22(E)).
Next, a photoresist 104 is formed (FIG. 22(F)), and the photoresist 104 is exposed by a drawing device and developed to form a photoresist pattern 104a (FIG. 22(G)).
Next, using the photoresist pattern 104a as a mask, the light shielding film pattern 102a is selectively etched to form a light shielding film pattern 102b (FIG. 22(H)).
Finally, the photoresist pattern 104a is removed by ashing or the like (FIG. 22(I)).

Japanese Patent Application Laid-Open No. 2003-215782 JP 2014-95827 A

In order to manufacture a halftone mask (multi-tone mask) with a known drawing apparatus, two types of drawing data are prepared: a pattern for etching the laminate of the semi-transmissive film and the light shielding film, and a pattern for etching only the light shielding film. Each must be made separately, requiring two lithography steps. As a result, an increase in the number of manufacturing processes results in a longer manufacturing period and a higher manufacturing cost.
Furthermore, since two (a plurality of) lithography steps are required, alignment is required for superimposing drawing patterns formed in each lithography step. In this case, it is necessary to take measures such as expanding the drawing pattern in consideration of the alignment margin (allowance), which becomes an obstacle to miniaturization of the pattern and high integration.
Further, when forming a multi-tone mask with four or more gradations, the number of lithography steps is further increased.

Also, in the process of etching a light-shielding film or a semi-transmissive film, for example, if isotropic etching such as wet etching is employed, side etching causes a deviation between the design value such as the line width of the pattern and the finished dimension. Therefore, in order to form a pattern with higher precision, a process of uniformly correcting design values such as line width, that is, sizing, has been performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is capable of forming resist patterns having different film thicknesses by a single lithography process, enabling simplification of the manufacturing process of a multi-tone photomask, and achieving high precision. An object of the present invention is to provide a method of manufacturing a photomask that enables pattern formation.
It goes without saying that the method of manufacturing a photomask according to the present invention is not limited to the manufacture of multi-tone photomasks, but can also be used for the manufacture of binary masks, for example.

A method for manufacturing a photomask according to the present invention includes:
A photomask manufacturing method using a drawing apparatus,
The drawing device includes a micromirror array composed of a plurality of micromirrors whose tilt angles can be independently changed in the optical path of the laser light emitted from the semiconductor laser,
a step of acquiring pattern dimension correlation data indicating a correlation between a design value of a drawing pattern to be drawn by the drawing device and an actual measured value of a finished dimension;
setting each pattern area of the micromirror corresponding to the drawing pattern based on the pattern size correlation data;
placing a photomask substrate on which a photoresist film is formed;
irradiating the micromirror array with a laser;
temporally controlling the irradiation state of the laser light by controlling the tilt angle for each of the micromirrors in each of the set pattern areas;
and a step of relatively changing an irradiation position of the laser beam with respect to the photomask substrate.

By using such a photomask drawing apparatus,
The optical path of the laser emitted from the semiconductor laser, which is a laser generator, is controlled by the micromirror unit of the DMD to flexibly correspond to various photomask patterns, facilitate pattern drawing, and achieve desired pattern dimensions. Realization of this makes it possible to manufacture highly accurate photomasks.

Further, the method for manufacturing a photomask according to the present invention includes:
the patterned area of the micromirror comprises a first micromirror area, a second micromirror area and a third micromirror area;
the micromirrors arranged in the first region maintain a first state for a first control time and maintain a second state for the rest of the time;
the micromirrors arranged in the second region maintain the first state during the second control time and maintain the second state for the rest of the time;
the micromirrors arranged in the third region maintain the first state for a third control time and maintain the second state for the rest of the time;
The first control time, the second control time, and the third control time are set to be different from each other.

By adopting such a photomask manufacturing method,
It is possible to manufacture a halftone mask and to reduce the manufacturing man-hours.

Further, the method for manufacturing a photomask according to the present invention includes:
The first micromirror area, the second micromirror area, and the third micromirror area are corrected in micromirror units for each area.

Further, the method for manufacturing a photomask according to the present invention includes:
The step of setting each pattern area of the micromirror corresponding to the drawing pattern based on the pattern dimension correlation data,
After setting the pattern area of the micromirror corresponding to the drawing pattern, the pattern area of the micromirror is corrected based on the pattern dimension correlation data.

By adopting such a photomask manufacturing method,
Even with a photomask having various patterns, the pattern can be easily corrected.

By the method of manufacturing a photomask according to the present invention,
Resists having different film thicknesses can be formed by a single lithography process, which makes it possible to reduce the number of steps for manufacturing a multi-tone photomask and to form a highly accurate pattern.

1 is a diagram showing the configuration of a drawing apparatus according to the present invention; FIG. FIG. 2(A) shows how the laser is irradiated onto the light reflecting portion, and FIG. 2(B) schematically shows the laser intensity distribution. FIG. 3A is an enlarged view of a part of the micromirror control region C, and FIG. 3B is a cross-sectional view showing a state in which the laser reflected by the micromirror 9 is irradiated onto the photoresist. FIG. 4 is a diagram showing a situation in which a photoresist is exposed by a step-and-repeat method; The figure which shows the mechanism which moves an optical system (a DMD is included). The figure which shows the outline|summary of the system of a drawing apparatus. FIG. 7(A) shows measured values of the intensity distribution of the laser reflected from the AA' portion of the micromirror control region C, and FIG. 7(B) shows measured values of the line width of the patterned photoresist. shows the distribution of FIG. 8(A) shows measured values of the intensity distribution of the laser reflected from the AA' portion of the micromirror control region C, and FIG. 8(B) shows measured values of the line width of the patterned photoresist. shows the distribution of FIG. 4 is a diagram showing a setting example of a micromirror control region C; 4 is a graph showing the relationship between the amount of laser exposure and the amount of dimensional variation in resist pattern width after development. FIG. 11A is an enlarged view of a partial region of the light reflecting portion; FIG. 11B is a graph showing a comparison of the timings of the first state and the second state of the micromirror. FIG. 4 is a cross-sectional view of a photoresist patterned by a laser whose irradiation time is controlled for each region by a DMD; 4A to 4C are cross-sectional views showing main steps of a method for manufacturing a halftone mask (multi-tone mask); 4A to 4C are cross-sectional views showing main steps of a method for manufacturing a halftone mask (multi-tone mask); FIG. 10 illustrates correction of areas of micromirrors to suppress pattern dimension variations. It is pattern size correlation data showing the correlation between the difference between the design value of the drawing pattern and the actual measurement value of the finished size of the pattern on the photomask and the design value. The figure which shows the operation condition of a micromirror. FIG. 4 illustrates the problem of correction when lines with different line widths connect; FIG. 10 is a diagram showing an example of correcting pattern widths after converting pattern data into data for each micromirror; FIG. 5 is a cross-sectional view showing the state of side etching of a halftone mask; FIG. 21A schematically shows a circuit pattern to be patterned, and FIGS. 21B and 21C show an example of dividing the circuit pattern into exposure sections. FIG. 10 is a cross-sectional view showing main manufacturing steps of a conventional typical bottom-half type multi-tone mask;

Embodiments of the present invention will be described below with reference to the drawings. However, none of the following embodiments provide a restrictive interpretation in identifying the gist of the present invention. Also, the same reference numerals are given to members of the same or similar type, and description thereof may be omitted.

FIG. 1A shows the main configuration of the drawing apparatus 1. As shown in FIG.
A laser LD (e.g., g-line, h-line, i-line, etc.) emitted from a semiconductor laser 2, which is a laser generator, is guided to a DMD (digital micromirror device) 4 by a reflecting mirror 3 as indicated by a dotted arrow. be. The laser beam reflected by the light reflecting portion 8 of the DMD 4 is projected onto a photomask substrate 7 mounted on a stage 6 at the same magnification or reduced size by an optical system 5 composed of, for example, a lens, as indicated by a white arrow. be done.
The photomask substrate 7 is, for example, a photomask blank in which a semi-transmissive film and a light shielding film are formed on a transparent substrate. there is
The stage 6 moves in X and Y directions perpendicular to each other, and can move the photomask substrate 7 in a predetermined direction by a predetermined distance.

The light reflecting portion 8 of the DMD 4 has a plurality of micromirrors 9, as will be described later, and the tilt angles of the respective micromirrors 9 are electrically independently controlled. , (B) can be changed alternatively as indicated by the white or black arrows.
The laser reflected in the direction of the white arrow passes through (passes through) the optical system 5 and is irradiated onto the photomask substrate 7 . On the other hand, the laser beam reflected in the direction of the black arrow does not enter the optical system 5 and therefore does not irradiate the photomask substrate 7 . By providing the DMD 4 in the optical path in this way, it is possible to select whether or not the photomask substrate 7 is irradiated with the laser.

FIG. 1B is a perspective view showing a part of the light reflecting section 8 of the DMD 4. FIG.
As shown in FIG. 1B, the light reflecting portion 8 is formed by a micromirror array in which a plurality of micromirrors 9 each having a side length of 10.8 [μm], for example 1980×1080 pieces, are arranged in a lattice. It is configured. Each micromirror 9 can independently control the tilt angle. The tilt angle is configured to be switchable in two stages, a first tilt angle or a second tilt angle, for example, −12[°] or +12[°].

In FIG. 1B, the laser LD indicated by the dotted arrow, for example, when reflected by the micromirror 9a set at the first tilt angle, enters the optical system 5 as indicated by the white arrow. After that, the photomask substrate 7 is irradiated with the light. When the light is reflected by the micromirror 9b whose tilt angle is set to the second tilt angle, it does not enter the optical system 5 as indicated by the black arrow, and therefore the photomask substrate 7 is not irradiated.

By controlling the reflection direction of the laser according to the tilt angle of the micromirror 9 in this manner, whether or not to irradiate the photomask substrate 7 with the laser can be selected for each micromirror. The area irradiated onto the photomask substrate 7 from one micromirror 9 via the optical system 5 is the minimum exposure area (pixel) on the photomask substrate 7 .
By individually controlling the tilt angles of the micromirrors 9, it is possible to select the presence or absence of irradiation for each pixel for laser drawing of various patterns. In addition, the inclination angle is an example and is not limited to this.

That is, the DMD 4 individually changes the course of the laser LD irradiated onto the photomask substrate 7, and the state of irradiating the substrate 6 with the laser light (first state: "ON" state) and the state of not irradiating the laser light (second state). 2 state: "OFF" state) can be selectively created.

FIG. 2A is a diagram showing how the surface of the light reflecting portion 8 is irradiated with the laser LD. FIG. 2(B) is a diagram schematically showing the laser intensity distribution in the cross section of the dashed-dotted line ZZ' in FIG. 2(A).
A region surrounded by a circle in FIG. 2A indicates a laser irradiation region S, and this circle corresponds to a laser spot diameter (for example, 1 [mm]). A region surrounded by a rectangle in FIG. 2A is a micromirror control region C set within the laser irradiation region S. The micromirror control area C is set so as to be within the laser irradiation area S, taking into consideration variations in the diameter of the laser spot and the variations in the optical axis.

As shown in FIG. 2(B), outside the laser irradiation area S, the intensity of the laser sharply decreases to 0 (zero). On the other hand, inside the laser irradiation region S, the laser intensity is ideally constant, and the micromirror control region C is set to a region where the uniformity of the intensity distribution is good, for example, a region within the uniformity required by the customer. there is
In addition, since the surface of the light reflecting portion 8 is not necessarily perpendicular to the incident direction of the laser, the laser irradiation area S is not necessarily a circle, but may be an ellipse to be precise. Also, the micromirror control area C is not limited to a square, and may be a rectangle.

The micromirrors located inside the micromirror control area C can selectively control the first state or the second state of each micromirror 9 . On the other hand, the micromirrors arranged outside the micromirror control area C are always set to the second state.

FIG. 3A shows a partially enlarged view of the micromirror control region C and shows an example of the control state of each micromirror 9. FIG. 3B shows the photoresist 10 formed on the photomask substrate 7 via the optical system 5 after the laser LD is reflected by the micromirror 9 (dotted line ZZ' in FIG. 3A). is a cross-sectional view showing a state of being irradiated to .
In FIG. 3A, micromirrors 9a (hatched areas) are in the first state, and micromirrors 9b (unhatched areas) are in the second state.

By arranging the micromirrors 9a in the first state in a desired pattern, the laser reflected by the micromirrors 9a is irradiated onto the photoresist 10 on the photomask substrate 7 in a desired pattern shape (see FIG. 3). (B)). Therefore, the photoresist 10 can be exposed in a desired pattern shape.
Each micromirror 9 constitutes one picture element (pixel) on the photomask substrate 7, and a photoresist pattern is formed as a set of pixels, which is the minimum unit of the exposure area.

The exposure area (for simplicity, referred to as an exposure section) of the photoresist 10 that can be exposed by one exposure process (one drawing process) is an area that can be irradiated by the laser reflected from the micromirror control area C. be.
Therefore, as shown in FIG. 4, when the exposure processing of one exposure section defined by the micromirror control area C is completed, the size of the exposure section is adjusted by the stage 6 so that continuous pattern formation is possible. The photomask substrate 7 is moved by a distance L. After that, exposure processing is performed by controlling the micromirror 9 to the first state or the second state so as to obtain a desired pattern for the next exposure section.

That is, by repeating the exposure processing of the surface of the photomask substrate 7 and the movement of the photomask substrate 7 by a step-and-repeat method, a desired pattern is formed on the entire surface of the photomask substrate 7 (or on the photoresist 10). area).

An example in which the photomask substrate 7 is moved by the moving stage 6 has been described. good. Therefore, the optical system 5 (and the DMD 4) may be moved, or both the optical system 4 and the photomask substrate 7 may be moved.

FIG. 5 shows an example of the configuration of the drawing apparatus 1 provided with a mechanism for moving the optical system 4. As shown in FIG.
The drawing device 1 includes a first travel guide 16 and a second travel guide 18 .
The longitudinal direction of the first travel guide 16 is parallel to the X direction in the figure, and the longitudinal direction of the second travel guide 18 is parallel to the Y direction in the figure.

The first traveling guide 16 has a fixed reflecting mirror 31 and a movable reflecting mirror 32 inside. A first driving device 17 moves the movable reflecting mirror 32 , DMD 4 and optical system 5 along the first traveling guide 16 . A second drive device 19 moves the first travel guide 16 along the second travel guide 18 .
Therefore, the movable reflecting mirror 32, DMD 4 and optical system 5 are movable in the X and Y directions in the figure.

A laser LD emitted from the semiconductor laser 2 is reflected by the fixed reflecting mirror 31 and irradiated to the movable reflecting mirror 32 . After that, the laser beam is reflected by the movable reflecting mirror 32 and irradiated onto the photomask substrate 7 via the DMD 4 and the optical system 5 . As a result, it becomes possible to scan the photomask substrate 7 with the laser LD in the X direction and the Y direction using the first and second driving devices 17 and 19 .

The amount of laser exposure for exposing the photoresist can be controlled by the time the micromirror 9a is in the first state. By setting the micromirror 9a to the second state after a predetermined time has elapsed, the exposure time for the desired pattern can be easily set.
Furthermore, since one micromirror 9 constitutes one pixel on the photomask substrate 7, the exposure time can be controlled for each pixel.

Since the drawing apparatus 1 includes the light amount detector 15 , the intensity distribution of the laser reflected by the light reflecting portion 8 of the DMD 4 and irradiated onto the photomask substrate 7 can be measured.
The light amount detector 15 uses an image sensor or the like, sets all the micromirrors 9 of the light reflection part 8 of the DMD 4 to the first state, and irradiates the light receiving surface of the light amount detector 15 with the reflected laser beam. It becomes possible to measure the laser irradiation intensity distribution two-dimensionally.
By setting the light receiving surface of the light amount detector 15 at the same height (level) as the irradiated surface of the photomask substrate 7, the intensity can be measured accurately.

As shown in FIG. 6, the drawing apparatus 1 is configured as a system further including a pattern data input unit 51, a storage unit 52, an arithmetic processing unit 53, a DMD control unit 54, a driving system control unit 55, and a light intensity measurement unit 56. may
The light amount measuring unit 56 controls the light amount detector 15 and stores the detected two-dimensional information in the storage unit 52 as image data (two-dimensional array data), for example. The arithmetic processing unit 53 can obtain the in-plane intensity distribution of the irradiated laser from each pixel of the image data, calculate the uniformity of the in-plane intensity distribution, and monitor the state of the light reflecting unit 8 . .

7A and 8A show the results of extracting the intensity distribution of the laser reflected from the AA' portion of the micromirror control region C from the measured two-dimensional intensity distribution detected. 7(B) and 8(B) are patterned by laser reflected from micromirrors 9 controlled by DMD controller 54 to form rows of 5 μm wide line patterns. 3 shows the actual measured line width of the photoresist.
The micromirror 9 forming the line pattern to be drawn is extracted according to the pattern data stored in the storage unit 52 via the pattern data input unit 51, and is controlled by the DMD control unit 54 to be in the first state. there is

As shown in FIG. 7A, the actual laser intensity distribution shows a downwardly convex intensity distribution with a finite fluctuation range. As shown in FIG. 7B, the measured value of the line width of the photoresist exhibits slight periodic fluctuations reflecting the intensity distribution of the laser.

FIG. 8(A) shows the result of measuring the intensity distribution of the reflected laser using a DMD different from the DMD having the intensity distribution shown in FIG. 7(A). The intensity distribution shown in FIG. 8A shows a downwardly convex intensity distribution similar to FIG. 7A, but the fluctuation range of the distribution is larger than that of the laser intensity distribution shown in FIG. .
The uniformity (=standard deviation/average value) of the intensity distribution shown in FIG. 7(A) is 11%, but the intensity distribution shown in FIG. 8(A) increases to 23%.
As shown in FIG. 8B, when the fluctuation width of the intensity distribution increases and the uniformity increases (degrades), the fluctuation width of the measured value of the line width of the photoresist also increases, and the uniformity of the line width increases ( to degrade.

For example, while the laser intensity distribution was initially shown in FIG. 7A, the intensity distribution becomes less uniform as shown in FIG. When deteriorated, the distribution of the photoresist pattern changes from the distribution shown in FIG. 7(B) to the distribution shown in FIG. 8(B).
In such a case, it is possible to take measures such as exchanging the DMD.

Therefore, by monitoring and managing the intensity distribution of the laser beam reflected by the light reflecting portion 8 of the DMD 4, fluctuations in the line pattern of the photoresist can be suppressed and a predetermined uniformity can be maintained. For example, when the intensity distribution exceeds a predetermined threshold value, the arithmetic processing unit 53 of the drawing apparatus 1 can display a warning on a lamp or a display screen to prompt the operator to replace the DMD. . As a result, it becomes possible to control and guarantee the quality of the manufactured photomask.

In order to detect the light intensity, the light intensity may be two-dimensionally detected by the light amount detector 15 with all the micromirrors 9 in the first state. The light intensity may be detected one-dimensionally by the light amount detector 15 in sequence by setting the micromirrors 9 to the first state row by row in the direction parallel to the line indicated by Z'. A pattern for placing the micromirror 9 for detecting the light intensity distribution in the first state can be appropriately set.

In addition, in order to clarify the relationship between the position of the micromirror 9 and the position in the image data of the light quantity detector 15, for example, the micromirror 9 in the micromirror array is set to the cross shape in the first state, and the light quantity detector 15 The intensity distribution may be measured by The crossed micromirrors 9 and the intersection points of the intensity distribution detected by the photodetector 15 are made to correspond to each other. By correlating such intersections at a plurality of locations, the relationship between the position of the micromirror 9 and the coordinates in the image data of the light amount detector 15 can be clarified.

As shown in FIGS. 7(A) and 8(A), both intensity distributions show a relatively flat distribution in the central portion while the intensity increases in the peripheral portion. This tendency is the same in the direction perpendicular to AA', and although the intensity distribution is relatively flat near the center of the laser irradiation area S, the intensity increases in the peripheral area of the laser irradiation area S. do.
Therefore, by selecting a region exhibiting a relatively flat intensity distribution, the uniformity of the resist pattern is reduced (improved).
A region indicated by BB' in FIGS. 7A and 8A is a region where the uniformity of the light intensity distribution is improved.

As shown in FIG. 9, from the light intensity distribution detected by the light intensity detector 15, the micromirror control region C is set to, for example, B The area determined by -B' may be set again. Similarly, in the direction perpendicular to BB', the variation width is set to be smaller than the threshold value.
For example, a threshold is set according to specifications (customer-requested values) such as the minimum line width and minimum spacing of the photomask to be manufactured, and micromirror Control region C may be set

If the micromirror control area C is set narrow, the exposure processing time by the step-and-repeat method is lengthened, so it may be appropriately set according to the required photomask specifications.
Since the DMD 4 can control each micromirror 9 independently, the setting of the micromirror control area C can also be easily controlled.

By setting the spatial resolution of the light intensity detection of the light amount detector 15 to be smaller than that of the pixels for writing the photoresist, the laser irradiation intensity for each pixel can be measured. By clarifying the correlation between the coordinates of the intensity distribution data of the light amount detector 15 and the positions of the micromirrors by the above method, the intensity of the laser reflected by each micromirror can be measured. Therefore, by multiplying the time for each micromirror to maintain the first state by a coefficient that is inversely proportional to the laser reflection intensity, the intensity distribution may be corrected and the photoresist may be uniformly irradiated with the laser.

FIG. 10 shows the correlation between the amount of laser exposure and the amount of dimensional variation in the resist pattern width after development, plotting the amount of dimensional variation on the vertical axis and the amount of laser exposure on the horizontal axis.
The exposure dose is normalized with the exposure dose for forming a resist pattern with a line width of 5 [μm] being 1. Such a relationship between the exposure amount and the resist pattern dimension after development depends on the resist to be used, and is obtained by actual measurement for each pattern dimension (for example, for a plurality of line widths, space widths, or a plurality of hole diameters). be able to.

From the laser intensity distribution of FIG. 7A (or FIG. 8A) and the correlation data between the exposure amount and the resist pattern dimension of FIG. 10, FIG. 7B (or FIG. 8B) A distribution of pattern dimensions (widths) can be calculated.
By storing basic data on the correlation between the exposure amount and the pattern dimension shown in FIG. can be calculated automatically. Further, by acquiring correlation data for a plurality of resists, it is possible to present candidates for the photoresist to be used.

FIG. 11A is an enlarged view of a partial area of the light reflecting portion 8 of the DMD 4 for manufacturing a multi-tone photomask. As shown in FIG. 11A, the light reflecting portion 8 has three regions Ra (cross-hatched region in the drawing), Rb (single-hatched region in the drawing), and Rc (white-painted region in the drawing). there is

FIG. 11B is a graph showing the timing of the first state and second state of the micromirrors 9a, 9b and 9c in the regions Ra, Rb and Rc when one exposure process is performed. In the region Rc, each micromirror 9c stays in the first state for zero (first control time), that is, always maintains the second state. In the region Ra, each micromirror 9a is in the first state for a predetermined period (third control time ta) and is otherwise maintained in the second state. The period remains in the second state. As shown in FIG. 11B, tb is set shorter than ta. For example, when ta is 100%, tb is 30% to 50%.

Therefore, during one exposure process, the periods (exposure times) during which the laser is reflected in the three regions Ra, Rb, and Rc and irradiated onto the photomask substrate 7 are ta, tb, and tc (0: none), respectively. is.
Note that the irradiation period (exposure time) does not necessarily have to be continuous, and the total period for maintaining the first state may be, for example, ta and tb.

FIG. 12 shows the film thickness of the photoresist 10 patterned using the drawing apparatus 1. FIG. Laser LD is reflected at regions Ra, Rb, and Rc shown in FIG. 12 to irradiate regions Pa, Pb, and Pc of photoresist 10 on photomask substrate 7, respectively. Since the regions Pa, Pb, and Pc of the photoresist 10 have different exposure times, the thickness of the photoresist after development also differs.
For example, in the case of a negative photoresist, the exposure time of the laser irradiated through the region Rc is 0, so the film thickness of the photoresist 10 in the region Pc is 0. The film thickness (Hb) of the photoresist 10 in the region Pb and the film thickness (Ha) of the photoresist 10 in the region Pa are Hb<Ha because the exposure time tb is shorter than the exposure time ta (tb<ta).

A desired film thickness of the photoresist 10 can be obtained from the correlation data (sensitivity curve) between the film thickness of the photoresist 10 and the exposure time. By acquiring the data of the sensitivity curve of the photoresist 10 to be used in advance, it is possible to determine the exposure time for forming the photoresist 10 with a desired film thickness in each region. The determined exposure time can be controlled by setting the time to maintain the first state of each micromirror 9 of DMD 4 . Therefore, by controlling the laser irradiation using the DMD 4, any exposure time can be set in any region with one micromirror 9 as a unit.

FIG. 12 shows an example of forming the photoresist 10 with three different film thicknesses (Ha, Hb, 0). In this way, the light reflecting section 8 is divided into a plurality of regions, for example, first to n-th (n≧3) regions, and each micromirror arranged in each region is in the first state. By setting n control times (including time 0), resist patterns having n different film thicknesses (including film thickness 0) can be formed. Therefore, it is also possible to form a photoresist with three or more different film thicknesses.
It is also possible to form a photoresist with a stepwise sloped cross-section.

In addition, when the exposure time changes as described above, the pattern dimension of the photoresist fluctuates. Therefore, the width of the area of the micromirror 9 in the micromirror control area C may be changed based on the correlation between the exposure amount and the pattern dimension, as will be described later.

After exposing the photoresist 10 using the laser reflected from the light reflecting portion 8, the photomask substrate 7 is moved, and the exposure process and the movement of the photomask substrate 7 are repeated by a step-and-repeat method to obtain a plurality of film thicknesses. A pattern of photoresist 10 having a pattern can be formed on the photomask substrate 7 .
It should be noted that a photoresist having a plurality of different film thicknesses can be formed by one exposure process even for a positive photoresist.

If a conventional drawing apparatus is used to form a photoresist pattern with such different film thicknesses, it is necessary to expose the photoresist by a plurality of drawing processes. For this reason, it is necessary to take into account pattern misalignment (position misalignment, alignment misalignment) in different exposure processes, and to include in the pattern a width (dimension) corresponding to an overlay margin.
However, when the drawing apparatus 1 using the DMD 4 is used as in the present embodiment, the photoresist 10 having different film thicknesses can be patterned by one exposure, so it is necessary to design the pattern in consideration of this overlay margin. Therefore, it is possible to miniaturize the dimension corresponding to the overlay margin. Furthermore, since the design rule for the overlay margin is relaxed, the pattern design is facilitated and the pattern designer's labor is reduced.

FIG. 13 is a cross-sectional view showing main steps of a method for manufacturing a halftone mask (multi-tone mask).
As shown in FIG. 13A, a semi-transmissive film 12 (eg MoSi, Ti) and a light shielding film 13 (eg Cr) are formed in this order on a transparent substrate 11 made of quartz or the like by vapor deposition or sputtering. A photomask blank is prepared, and a photoresist 10 is formed on the light shielding film 13 by coating or the like.
The light transmittance of the semi-transmissive film 12 is arbitrarily set between the light transmittance of the transparent substrate 11 and the light transmittance of the light shielding film 13 .

Next, as shown in FIG. 13B, the photoresist 10 is exposed by controlling the exposure time in units of the micromirrors 9 of the DMD 4, and then developed to pattern the photoresist 10. Next, as shown in FIG.
As described above, since the exposure time can be controlled for each micromirror 9, the first photoresist pattern 10a and the second photoresist pattern 10b having different film thicknesses can be simultaneously formed by one exposure process. can. Further, it is also possible to form patterns of the photoresist 10 having three or more different film thicknesses.

In the conventional drawing process of the photoresist pattern 104a shown in FIG. 22(G), since the pattern 102a of the light-shielding film and the pattern 101a of the semi-transmissive film are formed on the base, the influence of halation from these patterns is reduced. Although it may occur, in the process shown in the example of FIG. 13B, there is also an effect that there is no influence of such halation due to the underlying pattern.

Next, as shown in FIG. 13C, using the photoresist 10 (the first photoresist pattern 10a and the second photoresist pattern 10b) as a mask, the light shielding film 13 is etched by a known wet etching method or dry etching method. and the semitransparent film 12 are sequentially etched.

Next, as shown in FIG. 13D, the entire surface of the photoresist 10 is etched (etched back) by an ashing method until the portion of the second photoresist pattern 10b is removed.
That is, the film thickness of the photoresist 10 is reduced by etching back by an amount larger than the film thickness Hb and smaller than the film thickness Ha.
Since the film thickness Ha of the first photoresist pattern 10a is larger than the film thickness Hb of the second photoresist pattern 10b, the film thickness of the first photoresist pattern 10a is reduced to Ha-Hb or less. Some can be left behind.

In the process of FIG. 13C, when at least one of the light-shielding film 13 and the semi-transmissive film 12 is etched by a dry etching method, if the selectivity is adjusted by optimizing the etching gas (etchant) in advance, The photoresist 10 may be etched at the same time, and when at least one of the light shielding film 13 and the semitransparent film 12 is etched, the portion of the second photoresist pattern 10b may be removed at the same time.

Incidentally, the film thickness of the photoresist may be determined from the viewpoint of the process such as the etching resistance to the etchant, the uniformity of the amount of etching back, and the like.

Next, as shown in FIG. 14E, using the photoresist 10 (first photoresist pattern 10a) as a mask, the light shielding film 13 is selectively etched by wet etching or dry etching. Etching of the semi-transmissive film 12 is suppressed by using a known etchant (etching liquid, etching gas) and setting the selectivity to a sufficiently high value (for example, 10 or more).

Next, as shown in FIG. 14F, the photoresist (first photoresist pattern 10a) is removed by an ashing method or the like.
Through the above steps, a region 3 where the transparent substrate 11 is exposed, a region where only the semi-transmissive film 12 is formed on the transparent substrate 11, and a region where the semi-transmissive film 12 and the light shielding film 13 are formed on the transparent substrate 11 are provided. A grayscale halftone mask 14 can be obtained.

Although the method for forming a three-tone halftone mask has been described above, the photoresist 10 can be formed to have four or more film thicknesses by controlling the time in which the micromirror 9 is in the first state. By patterning, it is also possible to manufacture a multi-gradation photomask.
In order to form patterns of semi-transmissive films with different film thicknesses, etching back of resist patterns with different film thicknesses and partial etching (half-etching) of the semi-transmissive film may be sequentially repeated.

In addition, from the relationship between the exposure time and the pattern width shown in FIG. 10, the pattern width may change if the exposure time is changed depending on the region in order to form different resist film thicknesses.
For example, in FIG. 11A, the pattern width is reduced (thinner) in the area Rb as compared with the area Ra because the exposure amount is reduced. Therefore, as shown in FIG. 15A, the width of the region (region Rb) of the micromirror 9b corresponding to the region with a small amount of exposure is reduced by the pattern width variation (region Ra) of the micromirror 9a. It may be set (corrected) so that it becomes wider by the amount of decrease. Alternatively, as shown in FIG. 15B, conversely, the area (area Ra) of the micromirror 9a corresponding to the area where the exposure amount is small may be reduced by the variation of the pattern width.
Dotted lines in FIGS. 15A and 15B indicate regions before correction.

FIG. 16 is pattern size correlation data showing the correlation between the design value of the drawing pattern (design size on CAD) and the measured value of the pattern size after etching (finished size).
The horizontal axis plots the design value of the drawing pattern, and the vertical axis plots the difference between the design value and the measured value of the pattern dimension formed on the photomask substrate 7. FIG. 16 shows an example of the pattern dimension of the light shielding film.
The drawing patterns used for the measurement are, for example, patterns with line/space design values of 2/2, 3/3, 5/5, 10/10, 15/15, and 50/50 [μm]. The pattern for measurement may include a pattern in which lines and spaces are arranged, an isolated line, an isolated space, a pattern in which holes are two-dimensionally arranged, and an isolated hole. Correlation data is obtained in advance using such a standard pattern and stored in the storage unit 52 .
Here, the difference was calculated by subtracting the measured value of the finished pattern dimension from each design value of the drawing pattern, that is, [design value]-[actual value].
Note that even when reduced projection is performed by the optical system 5, each design value of the drawing pattern uses a value in consideration of the reduction magnification, so the calculation of the difference is as described above.

As shown in FIG. 16, when the pattern width is narrow (shorter than 10 [μm]), the measured value tends to be small, and when the pattern width is wide (longer than 10 [μm]), the measured value tends to be large. That is, it can be understood that the difference is not constant with respect to the line width.

Also, as can be seen from FIG. 16, it can be understood that the pattern width dependency of the difference differs between the X direction and the Y direction.
That is, the line width dependence of the difference differs depending on the longitudinal direction (X direction or Y direction) of the line pattern.

17A, 17B, and 17C are cross-sectional views showing the state of one micromirror 9, and FIG. 17D is a perspective view of an inclined micromirror 9. FIG.
As shown in FIGS. 17A and 17B, since the micromirror 9 reflects the laser in the tilted state, the laser reflecting area is reduced compared to the non-tilted state shown in FIG. 17C. However, the laser reflecting area does not decrease in the direction perpendicular to the cross section and parallel to the axis of rotation for tilting the micromirror 9, ie, the direction indicated by the dotted line in FIG. 17(D).
Therefore, the effective light intensity exhibits geometric direction dependency depending on the arrangement direction of the micromirror 9 . Therefore, it is considered that the design value dependency of the difference in FIG. 16 is different in the X direction and the Y direction as described above.

Therefore, in order to obtain the finished dimension as designed, it is necessary to correct the value corresponding to the difference between them depending on the line pattern width (the length in the direction perpendicular to the longitudinal direction).
For example, in the case of the example of FIG. 16, the pattern width is designed so that the finished dimension is equal to the design value for a pattern whose actual measurement value is smaller than the design value (pattern width is shorter than 10 [μm]). Corrects the value to be thicker (longer) by the amount of the difference. Conversely, for a pattern (pattern width longer than 10 [μm]) in which the actual measurement value is larger than the design value, the design value of the pattern width is reduced by the amount of the difference so that the finished dimension is equal to the design value. Correct to make it thinner (shorter).

The relationship between the design values and the actual measurements of the finished dimensions also depends on the exposure dose. Therefore, correlation data between the design values and the actual measurement values of the finished dimensions as shown in FIG. 16 is obtained for each of the regions having different exposure amounts, such as the region Ra and the region Rb, and correction is performed.
Note that the correlation data shown in FIG. 16 is an example, and the present invention is not limited to this.

When correcting the pattern width, the design data input by CAD (original data of the design drawing pattern determined from the product specifications, etc.) is corrected, and each micromirror of the DMD 4 is calculated from the corrected design data. 9 into control data. For example, in CAD design, a line is defined as vector data connecting the vertices with the coordinates of each vertex specified. After this vector data is corrected, it is converted into pixel-by-pixel data for each micromirror 9, that is, dot data, and stored in the storage unit 52 as micromirror 9 control data.

On the other hand, the pattern width may be corrected after the CAD design data (design drawing) is converted into pixel-by-pixel data (dot data) for each micromirror 9 .

18A and 18B show an arrangement in which a wide line 61 (with a pattern width longer than 10 [μm]) is connected to a narrow line 62 (with a pattern width shorter than 10 [μm]). Give an example.
FIG. 18A shows the pattern arrangement before correction, and FIG. 18B shows the pattern arrangement after correction. When the short side of the line 62 touches the long side of the line 61, if the width of the line 61 is simply reduced when correcting the pattern, the connection relationship between the line 61 and the line 62 is as shown in FIG. is lost. Therefore, in such a case, it is necessary to detect the connection relationship between the lines and perform additional correction such as extending the line 62 by a value equal to the reduced width of the line 61 .

FIG. 19 shows an example of pattern correction after converting various drawing pattern data into data for each micromirror 9 . FIG. 19A is a pattern before correction (original pattern of a designed drawing pattern), FIG. 19B is an enlarged view of a region surrounded by a dotted circle in FIG. 19A, and FIG. 19C. shows an enlarged view of the pattern after correction in the same area.
FIG. 19A shows an example in which a wide line 61 and a narrow line 62 are connected, and other areas are transparent areas.

As shown in FIG. 19B, the wide line 61 is always in the second state (the photomask substrate 7 is not in contact with the micromirror 961b in contact with the narrow line 62, and the micromirror 961b is not in contact with the narrow line 62). It has a micromirror 961a in contact with a micromirror 9 that maintains a state in which no laser is applied. No correction is performed for the micromirror 961b (or the control condition for the narrow line 62, which is a different adjacent pattern area), and the control condition for the micromirror 961a is to always maintain the second state (adjacent The width of the thick line 61 can be reduced by changing the control condition of the transparent area, which is a different pattern area. By repeating this operation until the desired decrease is reached, the pattern can be corrected without losing the connection between the lines.

Although the above description is for the case of correcting the pattern width in the X-axis direction in FIG. 19, the same applies to the case of correcting the pattern width in the Y-axis direction.

Since control information is given to each micromirror 9, the drawing apparatus 1 using the DMD 4 checks the control conditions of adjacent micromirrors for each micromirror 9 and corrects the control conditions of the micromirrors. It is possible to correct the pattern while repeating a simple algorithm of (changing) and maintaining the connection relationship between the wide line 61 and the narrow line 62 .

Although the case of reducing the wide line 61 has been described above, it can also be applied to the correction of reducing the narrow line 62 .
Note that the above two types of correction are possible not only for line patterns but also for hole patterns.
In addition to the light-shielding film 13, the pattern dimension of the semi-transmissive film 12 can also be corrected in the same manner.

Further, when forming photoresist patterns with different film thicknesses by changing the period for maintaining the first state of the micromirror 9 by one exposure process, the exposure amount of the photoresist changes. Therefore, the correlation between the design value (design dimension on CAD) and the difference between the measured value of the finished dimension after etching for each exposure amount of the photoresist (that is, the time for which the micromirror 9 is maintained in the first state) is obtained, and correction values are determined for different exposure doses.

When a multi-tone mask is created using resist patterns having different resist film thicknesses by one exposure process, part of the light-shielding film is exposed, for example, in the etching process shown in FIG. 13D and in FIG. A plurality of etching processes of the etching steps shown are performed.

FIG. 20 shows a cross section of part of the photomask in the step of FIG. 14(E). A first pattern end portion 13A of the light shielding film 13 surrounded by a dotted line circle in the drawing is subjected to the etching treatment of both FIG. 13(D) and FIG. 13B receives only the etching process of FIG. 14(E). Therefore, to be precise, the side etching amount of the first pattern end portion 13A is larger than the side etching amount of the second pattern end portion 13B.
Therefore, when the difference in the side etching amount cannot be ignored, the pattern of the light shielding film 13 adjacent to the pattern of the semi-transmissive film 12 and the pattern of the isolated light shielding film 13 not adjacent to the pattern of the semi-transmissive film 12 have the design value and the measured values of the finished dimensions after etching are different, and accordingly the correlation between the design values and the measured values of the finished dimensions is different.

In addition, it can be seen that the pattern of the semi-transmissive film adjacent to the light-shielding film has a larger finished line width due to the side etching of the light-shielding film, contrary to the line width of the light-shielding film.

This difference in correlation is due to the fact that photoresist patterns having different film thicknesses are formed in a single lithography process, and the formed photoresist pattern is used as a mask, unlike the conventional method of manufacturing a multi-tone mask. This is because a plurality of etching processes are performed.

Therefore, when patterns with different transmittances are adjacent to each other, the amount of side etching differs depending on the combination of the transmittances. Therefore, for each pattern transmittance combination, pattern dimension correlation data indicating the correlation between the design value and the actual measured value of the finished dimension of the pattern is acquired, and the pattern dimension is corrected according to the correlation data.
The patterns with different transmittances correspond to regions divided by a combination of holding times of the first state and the second state in each micromirror 9 when patterning is performed using the drawing apparatus 1 .

Here, the pattern composed of the isolated light shielding film 13 and the semi-transmissive film 12 (or the pattern composed only of the semi-transmissive film 12) is treated as a pattern adjacent to the pattern composed of the exposed area of the transparent substrate 11. can be done.

13(B) to 13(D), the pattern consisting only of the semi-transmissive film 12 is the first photoresist pattern 10a on the lamination of the isolated light shielding film 13 and the semi-transmissive film 12 on the right side in FIG. is changed to the second photoresist pattern 10b having the film thickness Hb, and the upper light-shielding film 13 is etched in the step shown in FIG. 14(E).

In the case of the drawing apparatus 1 using the DMD 4, since the pattern shape can be corrected for each micromirror 9, pattern correction based on a plurality of pattern size correlation data is also possible.

For example, when designing with CAD, it is possible to create pattern data for a photomask by creating separate layers for each combination of adjacent patterns with different transmittances and synthesizing these layers.

Hereinafter, a method for forming a resist pattern of a photomask (halftone mask) will be described in detail, taking as an example the case of forming a three-gradation halftone mask.

(1) Using a design tool such as CAD, the pattern data (coordinate data) of the transparent portion (light transmitting portion or transparent substrate exposed portion) that is the first pattern region, and the pattern of the light shielding portion that is the second pattern region. Desired pattern data 20 (for example, , electric circuit pattern. See FIG. 21.) are determined (designed). The pattern data 20 are stored in the storage unit 52 via the pattern data input unit 51 of the drawing apparatus 1 .
(2) The intensity distribution of the laser beam reflected from the reflecting portion 8 of the DMD 4 is measured by the light amount measuring section 56 using the light amount detector 15 and the measurement result is stored in the storage section 52 .
The laser intensity distribution may be periodically measured in advance and stored in the storage unit 52 of the drawing apparatus 1, or may be measured each time a photomask is manufactured.

(3) The arithmetic processing unit 53 determines the micromirror control region C so that the uniformity of the pattern width satisfies the threshold value based on the light amount measurement result. The threshold is determined depending on design requirements such as customer specifications.
(4) The pattern data 20 is divided into exposure sections 21 defined by the micromirror control areas C (irradiation areas on the photoresist of the laser reflected by the micromirror control areas).
At this time, it is also possible to adjust so that the important circuit portion of the pattern data 20 does not overlap the boundary portion of the divided exposure section 21 .
By doing so, it is possible to avoid fluctuations in the pattern width of the important circuit portion even when the exposure amount fluctuates.
That is, an important circuit portion is specified and designated in advance as an undivided portion, and the size of the exposed portion 21 is adjusted around the undivided portion so that the boundary portion of the exposed portion 21 does not overlap with the undivided portion. should be changed with

FIG. 21 shows an example of dividing the pattern data 20 (FIG. 21A) into exposure sections 21 (FIGS. 21B and 21C). FIGS. 21B and 21C show examples of division into exposure sections 21 corresponding to different micromirror control regions C depending on the threshold value.

(5) Determine the photoresist film thickness corresponding to each region from the requirements of the manufacturing process.
(6) The exposure time of the photoresist corresponding to the first, second, and third pattern regions (transparent portion, light shielding portion, and semi-transmissive portion) is measured in advance on the sensitivity curve and the photoresist film corresponding to each region. Calculate from the thickness.
From the calculated exposure time, the control conditions (tilt angle (that is, first state or second state) and its holding time) of the micromirror 9 corresponding to the first, second and third pattern regions are determined. do.

Here, the micromirrors corresponding to the first, second and third pattern regions refer to micromirrors that reflect the laser and irradiate the first, second and third pattern regions, respectively. The pattern area (Pc in FIG. 12) is irradiated with a laser, and the area (Rc in FIG. 12) composed of micromirrors is the first micromirror area, and the second pattern area (Pa in FIG. 12) is irradiated with the micromirror. A region made of mirrors (Ra in FIG. 12) is called a second micromirror region, and a region made of micromirrors (Rb in FIG. 12) for irradiating a third pattern region (Pb in FIG. 12) is called a third micromirror region. It is called a micromirror area. The first, second and third micromirror regions belong to the micromirror control region C. FIG.

The micromirror control conditions including the arrangement (coordinate) information in the micromirror array of the micromirrors 9 belonging to the first, second and third micromirror regions and the duration of the first state are stored in the storage unit 52. Keep
Note that the sensitivity curve may be stored in advance in the storage unit 52 and the exposure time may be calculated by the arithmetic processing unit 53 .

(7) Based on the correlation data between the design value of the pattern for each exposure dose and the actual measurement value of the finished dimension (if necessary, the adjacent from the correlation data for each of the combinations), correcting (enlarging or contracting) the first, second and third micromirror regions corresponding to the first, second and third pattern regions on a micromirror-by-micromirror basis, and correcting The arrangement (coordinate) information of the micromirrors 9 thus obtained in the micromirror array is stored in the storage unit 52 .
After correcting the design data (on CAD) of the pattern data 20, the first, second and third pattern regions are corrected for the corrected first pattern region, second pattern region and third pattern region. A micromirror area may be calculated.

(8) The corrected micromirror control conditions for the first, second, and third micromirror regions are stored in the storage unit 52 for each exposure section 21 by the arithmetic processing unit 53 .
The micromirror control condition for the regions other than the first, second, and third micromirror regions, ie, the micromirror control region C, is to always maintain the second state.

(9) A photomask substrate 7 having a photoresist 10 formed thereon is prepared on a photomask blank in which a light transmission portion and a light shielding portion are formed in this order on a transparent substrate, and placed on the stage 6 .
(10) The micromirror 9 of the DMD 4 is controlled by the DMD controller 54 according to the stored micromirror control conditions corresponding to each exposure section 21, and the photoresist 10 on the photomask substrate 7 is irradiated with the laser.

(11) At least one of the stage 6, the first driving device 17 and the second driving device 19 is driven by the drive system control unit 55, and the stage 6 (and the stage 6) is moved by a distance corresponding to one exposure section. The relative distance between the photomask substrate 7) placed on the optical system 5 and the optical system 5 is moved.
In this step, the relative distance between the photomask substrate 7 and the optical system 5 is moved. good too. Thus, the exposure section on the photoresist 10 can be moved to expose all areas on the photoresist 10 that require exposure processing.
Relative movement can be performed, for example, in each direction of two orthogonal axes, the X-axis and the Y-axis of a so-called orthogonal coordinate system.

When the optical system 5 is moved, it is necessary to configure so that the laser reflected from the micromirror 9 in the first state can irradiate the photomask substrate 7 via the optical system 5 . Therefore, as shown in FIG. 5, the DMD 4 is moved together with the optical system 5 .

(12) The arithmetic processing unit 53 controls the driving system control unit 55 and the DMD control unit 54, repeats (10) and (11) according to the step-and-repeat method, and removes the photoresist formed on the photomask substrate 7. 10 are exposed sequentially.

Through the above procedure, exposure of the photoresist 10 on the photomask substrate 7 is completed, and then patterning of the photoresist 10 is completed by development.
After that, the photomask can be completed by the manufacturing process described with reference to FIGS.

Note that the above steps can be replaced as appropriate.
For example, (4) may be performed after (7). That is, the pattern data (coordinate data) of the first, second, and third pattern regions are corrected from the correlation data for each exposure amount obtained in advance, and then each pattern data is determined in the micromirror control region C. The control conditions of the DMD 4 (the tilt angle of each micromirror 9 and its holding time) may be determined for each exposure section 21 and stored in the storage section 52 .

According to the present photomask manufacturing method, it is possible to form photoresist patterns with different film thicknesses on a photomask substrate by a single exposure process, and the desired finished dimensions of the pattern can be obtained with high precision. can be controlled. As a result, it is possible to reduce the number of manufacturing steps of the multi-tone photomask, and further contribute to miniaturization of the pattern of the photomask.
A photomask manufactured by this method of manufacturing a photomask can be used in a lithography process in the manufacturing process of electronic devices and the like, and has high industrial applicability.

1 drawing device 2 semiconductor laser 3 reflecting mirror 31 fixed reflecting mirror 32 movable reflecting mirror 4 DMD
5 optical system 6 stage 7 photomask substrate 8 light reflecting portions 9, 9a, 9b, 9c, 961a, 961b micromirror 10 photoresist 10a first photoresist pattern 10b second photoresist pattern 11 transparent substrate 12 semi-transmissive film 13 Light-shielding film 13A First pattern end 13B Second pattern end 14 Halftone mask 15 Light amount detector 16 First traveling guide 17 First driving device 18 Second traveling guide 19 Second driving device 20 Pattern data 21 Exposure section 51 Pattern data input section 52 Storage section 53 Arithmetic processing section 54 DMD control section 55 Driving system control section 56 Light intensity measurement section 61 Wide line 62 Narrow line 100 Transparent substrate 101 Semi-transmissive film 101a Semi-transmissive Film pattern 102 Light-shielding films 102a, 102b Light-shielding film pattern 103 Photoresist 103a Photoresist pattern 104 Photoresist 104a Photoresist pattern

Claims (4)

A photomask manufacturing method using a drawing apparatus,
The drawing device includes a micromirror array composed of a plurality of micromirrors whose tilt angles can be independently changed in the optical path of the laser light emitted from the semiconductor laser,
a step of acquiring pattern dimension correlation data indicating a correlation between a design value of a drawing pattern to be drawn by the drawing device and an actual measured value of a finished dimension;
Based on the pattern size correlation data, the drawing pattern is corrected by the difference between the measured values and the design values in the directions parallel and perpendicular to the rotation axis of the micromirror, respectively, so as to correspond to the drawing pattern. a pattern area setting step of setting each pattern area of the micromirror;
placing a photomask substrate on which a photoresist film is formed;
irradiating the micromirror array with a laser;
temporally controlling the irradiation state of the laser light by controlling the tilt angle for each of the micromirrors in each of the set pattern areas;
and a step of relatively changing an irradiation position of the laser beam with respect to the photomask substrate. the patterned area of the micromirror comprises a first micromirror area, a second micromirror area and a third micromirror area;
the micromirrors arranged in the first micromirror region maintain a first state for a first control time and maintain a second state for the rest of the time;
the micromirrors arranged in the second micromirror region maintain the first state during the second control time and maintain the second state for the rest of the time;
the micromirrors arranged in the third micromirror region maintain the first state for a third control time and maintain the second state for the rest of the time;
2. The method of manufacturing a photomask according to claim 1, wherein the first control time, the second control time, and the third control time are set to be different from each other. In the pattern area setting step,
3. The photomask according to claim 2, wherein said first micromirror area, said second micromirror area and said third micromirror area are corrected in micromirror units for each area. manufacturing method. The pattern area setting step includes:
After setting the pattern area of the micromirror corresponding to the drawing pattern, based on the pattern size correlation data, for the directions parallel and perpendicular to the rotation axis of the micromirror, the 4. The method of manufacturing a photomask according to claim 1, wherein the pattern area of the micromirror is set by correcting the drawing pattern based on a difference between measured values .

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