JP4387699B2 - Mask making method and mask making apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method and a manufacturing apparatus for a photomask (also referred to as a reticle, hereinafter referred to as a mask) used in an exposure process (lithography process) at the time of manufacturing a semiconductor integrated circuit.
[0002]
[Prior art]
In general, in order to create a mask used in the manufacture of a semiconductor integrated circuit, a chromium film that shields exposure light in a pattern corresponding to a target circuit pattern is attached to the surface of a quartz plate or the like as a substrate of the mask. There is a need. The chromium film or the like is formed by pattern exposure, and a general method of drawing and exposing in a pattern shape is electron beam drawing using an electron beam. This is to draw a finely focused electron beam along a pattern as called electron beam direct drawing, and the apparatus is usually called an EB (Electron Beam) drawing apparatus.
[0003]
As a problem in mask manufacturing, the amount of information of a mask pattern becomes enormous because semiconductors are highly integrated and miniaturized year by year. For this reason, the drawing time by the EB drawing apparatus reaches several tens to several hundred hours per mask, and thus an apparatus having a high drawing speed has been strongly desired.
[0004]
On the other hand, as a mask manufacturing apparatus, pattern drawing is performed using a laser beam in the ultraviolet region (hereinafter abbreviated as ultraviolet laser beam) instead of an electron beam (that is, with respect to a mask substrate coated with a resist). A device based on a method of exposure to light (sometimes called a laser beam drawing apparatus) has been commercialized. As a configuration of the apparatus, for example, a reflection mirror display element (device called a digital micromirror) in which a large number of minute mirrors are arranged in a two-dimensional array is used, and this is irradiated with ultraviolet laser light, and the reflected light is patterned. The pattern is drawn on the mask substrate. This laser beam drawing apparatus has a feature that the processing speed is higher than that of the EB drawing apparatus because a part of the circuit pattern can be exposed at a time. Further, unlike the EB drawing apparatus, the drawing area does not need to be evacuated, so that the apparatus structure can be simplified and the apparatus price can be reduced. This is shown, for example, in Electronic Journal, July 2001, pages 140-142.
[0005]
On the other hand, in order to meet the demand for mask patterns that are becoming finer year by year, a method has been proposed in which a mask pattern reduced by a reduction projection optical system is used for exposure as a mask. This is called a photomask repeater, and the first mask may be called a master mask. According to this, since the reduction ratio is 1/4 in a normal exposure machine, the mask pattern can be miniaturized to 1/4. On the other hand, since the pattern line width of the master mask can be increased, the required drawing accuracy can be lowered. The photomask repeater is described in, for example, Proceedings of SPIE Vol. 4186, pp. 34-45 or Proceedings of SPIE Vol. 4562, pp. 522-529.
[0006]
[Non-Patent Document 1]
Electronic Journal July 2001, pp. 140-142 [0007]
[Non-Patent Document 2]
Proceedings of SPIE Vol. 4186, pp. 34-45
[0008]
[Non-Patent Document 3]
Proceedings of SPIE Vol. 4562, pp. 522-529
[0009]
[Non-Patent Document 4]
SEMICON Japan 2002, Technical programs for the semiconductor equipment and materials industries, 3-15-3-16
[0010]
[Problems to be solved by the invention]
In the conventional photomask repeater, the drawing method of the master mask is not particularly mentioned, but if a normal EB drawing apparatus is used, the drawing time will be long as in the conventional case. That is, all the master masks have a data capacity equivalent to that of a mask created using them, so that the drawing time cannot be shortened.
[0011]
Therefore, an object of the present invention is to provide a method for shortening the pattern drawing time of the entire master mask and an apparatus therefor when creating a mask from a plurality of master masks.
[0012]
[Means for Solving the Problems]
According to the present invention, a plurality of pattern projection devices are collectively used to create a plurality of master masks by drawing a pattern on a plurality of master mask substrates, and the plurality of master masks are formed using a reduction projection optical system. A mask creation method for creating a mask by drawing a pattern on a mask substrate by performing reduced projection , wherein each of the pattern projection devices has a two-dimensional array of micromirrors as a two-dimensional array of light control elements. A digital micromirror device comprising a plurality of microlenses arranged two-dimensionally corresponding to the plurality of micromirrors so as to pass laser beams reflected by the plurality of micromirrors in the digital micromirror device, respectively. A mask production method comprising a lens array is obtained.
[0014]
Further, according to the present invention, there is obtained the mask creating method in which the mirror device projection area by the at least one pattern projection apparatus is arranged obliquely with respect to the scanning direction on the master mask substrate.
[0015]
Further, according to the present invention, each mirror device projection area by all plurality of said pattern projection apparatus, the mask creation method of placing obliquely to the scanning direction of the master mask substrate is obtained.
[0016]
Furthermore, according to the present invention, a plurality of master mask substrates are continuously placed on a one-way stage, each master mask substrate is transported in one direction at a time, and drawing on the previous master mask substrate is completed. Thus, the mask creating method can be obtained in which the pattern projection apparatus continuously performs drawing on the next master mask substrate without any interval.
[0017]
According to the invention, a plurality of pattern projection devices are used for each of a plurality of master mask substrates, the plurality of master mask substrates are placed on the same XY stage, and each master mask is The mask creation that creates a plurality of master masks at once by drawing the entire surface of each master mask substrate by scanning the substrates all at once in the Y direction and stepping each master mask substrate in the X direction at once. A method is obtained.
[0018]
According to the present invention, it is further possible to obtain the mask making method in which the space between the lens closest to the substrate mask and the mask substrate among the plurality of lenses constituting the reduction projection optical system is filled with liquid.
[0019]
Further, according to the present invention, when exposure is performed on the mask substrate by the reduction projection optical system so as to connect the patterns by the plurality of master masks, the pixels drawn by the mirror device projection area in each master mask The above-mentioned mask making method is obtained in which exposure is performed so that the most extreme lines of the lines are shared with each other.
[0020]
Further, according to the present invention, a plurality of pattern projection devices for creating a plurality of master masks by drawing a pattern on a plurality of master mask substrates in a batch and reducing the plurality of master masks It possesses a reduced projection optical system for creating a mask a pattern is drawn on the mask substrate by projecting, wherein each pattern projection apparatus, as a two-dimensional array-like light control element, a plurality of micromirrors are two Dimensionally arranged digital micromirror device and a plurality of microlenses arranged two-dimensionally corresponding to the plurality of micromirrors so as to pass laser beams reflected by the plurality of micromirrors in the digital micromirror device, respectively mask preparation apparatus characterized by having a micro lens array consisting obtain .
[0022]
Further, according to the present invention, there is obtained the mask creating apparatus in which the mirror device projection area by the at least one pattern projecting apparatus is arranged obliquely with respect to the scanning direction on the master mask substrate.
[0023]
Furthermore, according to the present invention, each mirror device projection area by all plurality of said pattern projection apparatus, the mask generating device which is arranged obliquely with respect to the scanning direction of the master mask substrate is obtained.
[0024]
Furthermore, according to the present invention, a plurality of master mask substrates are continuously placed, and each master mask substrate has a one-way stage for transporting the master mask substrates in the one direction at a time. With the pattern projection apparatus that has finished drawing, it is possible to obtain the mask creating apparatus that performs drawing on the next master mask substrate continuously without any interval.
[0025]
According to the present invention, a plurality of pattern projection devices are provided for each of a plurality of master mask substrates, a plurality of master mask substrates are mounted, and each master mask substrate is collectively Y The same XY stage for scanning in the direction and stepping each master mask substrate in the X direction at once is created, and a plurality of master masks are created at once by drawing the entire surface of each master mask substrate. The said mask preparation apparatus is obtained.
[0026]
Further, according to the present invention, there is obtained the mask making apparatus in which a space between the lens closest to the substrate mask and the mask substrate among the plurality of lenses constituting the reduction projection optical system is filled with a liquid.
[0027]
According to the invention, the reduction projection optical system is drawn by the mirror device projection area in each master mask when exposing on the mask substrate so as to connect the patterns by the plurality of master masks. The mask creating apparatus for performing exposure so that the endmost lines of the lines of pixels are shared with each other can be obtained.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0029]
FIG. 1 is a configuration diagram of a pattern projection apparatus 10 used in the mask creation method of the present invention. Referring to FIG. 1, a pattern projection apparatus 10 uses a mirror device 6 in which a plurality of micromirrors are arranged two-dimensionally as a two-dimensional array of light control elements.
[0030]
The laser light L1 traveling from each micromirror in the mirror device 6 passes through the microlens array 7 so that each beam is collected and enters a hole in the pinhole plate 8. The laser beam L2 emitted from the pinhole plate 8 passes through the lenses 9a and 9b, and as a result, a pattern is drawn as an aggregate of dots like the mirror device projection region 2 on the master mask substrate 1. That is, the lenses 9a and 9b constitute a projection optical system, and project an optical image on the pinhole plate 8 onto the master mask substrate 1.
[0031]
In the present invention, the mirror device projection area 2 is projected obliquely with respect to the master mask substrate 1 as shown in FIG. Thus, by scanning the mirror device projection area 2 in the scanning direction in the figure, it becomes possible to draw with many pixels at a time, and the scan width can be increased.
[0032]
As described above, in the pattern projection apparatus 10, since the pixels are reduced by the microlens array 7 when projecting onto the master mask substrate 1 by the micromirror in the mirror device 6, the projection optics configured by the lenses 9 a and 9 b. For the system, a particularly high reduction ratio is not necessary. Therefore, the pattern projection apparatus 10 can be made as small as 4 or 5 cm in diameter, and can be configured at a low price of around 1 million yen.
[0033]
As shown in FIG. 3, the mask creation method of the present invention is characterized in that a master mask is drawn using a plurality of pattern projection apparatuses 10a, 10b, and 10c as described above. The master mask substrates 11a, 11b, and 11c created by the above are used, and these are reduced and projected onto the mask substrate 13 by the reduction projection optical system 12, thereby drawing a mask. As described above, in order to draw a plurality of master masks, it is a major feature that a pattern projection apparatus using a mirror device or the like is used. Since the pattern projection apparatus is small and can be obtained at a low price, a large number It becomes possible to perform simultaneous parallel drawing on a single master mask. Therefore, the drawing time of all master masks does not increase.
[0034]
For example, when the size of the master mask is 16 times that of the mask, simultaneous parallel writing can be performed on each master mask substrate 21 using three pattern projection apparatuses 20 as shown in FIG. It is. FIG. 4 is a layout view seen from above. In this case, each master mask substrate 21 is placed on the same XY stage 22, and when scanning each master mask substrate 21 in the Y direction, the pattern projection device 20 draws only the scan width and steps in the X direction. Thus, the entire surface of each master mask substrate 21 is drawn.
[0035]
By the way, in the mask making method of the present invention shown in FIG. 3, the space between the reduction projection optical system 12 and the mask substrate 13 may be filled with a liquid such as pure water. According to this, the reduction projection optical system 12 becomes an optical system called an immersion optical system, and the resolution is improved. The resolution has an effect that the wavelength of exposure light is shortened to the same wavelength as that of exposure at a wavelength obtained by dividing the wavelength of the exposure light by the refractive index of the liquid at that wavelength.
[0036]
As for the immersion optical system, in a normal exposure target for exposing a semiconductor device, in order to increase the resolution, the space between the lens closest to the wafer in the reduction projection optical apparatus and the wafer is filled with pure water, This is a technique for shortening the actual exposure wavelength. For example, an apparatus that is applied to an exposure apparatus using an ArF excimer laser having a wavelength of 193 nm as a light source (hereinafter referred to as an ArF exposure machine) is called an ArF immersion optical system. It is known as a method for improving the resolution of an ArF exposure machine that exposes a normal semiconductor chip. For example, it is shown in SEMICON Japan 2002, Technical programs for the semiconductor equipment and materials industries, Nos. 3-15 to 3-16. Yes.
[0037]
However, when the immersion optical system is applied to a normal exposure machine, there are the following problems. That is, in wafer exposure, it is necessary to move the wafer each time one chip is exposed, and the wafer is placed on a high-precision stage at high speed. This stage is usually an air levitation mechanism so that it can move at a particularly high speed. However, in order to apply the immersion optical system, it is necessary to make such a high-speed stage have a water-resistant structure, which is very difficult to realize.
[0038]
On the other hand, in the mask drawing method of the present invention, the mask is drawn by reducing and projecting the master mask by the reduction projection optical system, so that it is not necessary to move the mask substrate at high speed when drawing the mask pattern. Accordingly, it is not necessary to place the mask substrate on a high-speed stage or the like that floats on the air, so that it is easy to apply the immersion optical system.
[0039]
Further, as shown in FIG. 5A, by arranging eight pattern projectors 30, the master mask substrate 31 can be drawn in one scan. That is, the respective mirror device projection areas from the pattern projection devices 30 can be connected. However, as shown in FIG. 5A, every time the master mask substrate 31 is drawn, the scan of the length of the overscan 32 is wasted. Therefore, as shown in FIG. 5B, the overmask 32 is substantially over-scanned 32 by drawing on the one-way stage 33 continuously like the master masks 31a, 31b, 31c, 31d, and 31e. It is possible to reduce the useless drawing time due to the occurrence of only one time.
[0040]
By the way, as shown in FIG. 3, with regard to the joint exposure when the patterns from the respective master masks are joined on the mask substrate 13, the extreme end lines of the pixel lines drawn by the mirror device projection area are shared with each other. It is preferable to perform exposure.
[0041]
In addition, when creating a mask from a plurality of master masks as in the present invention, the master mask may be stored after the mask is completed, or chromium may be etched by etching to create the next mask. The pattern film such as may be removed and reused. By reusing, it is possible to reduce the production cost of the master mask.
[0042]
In addition, by storing the master mask, for example, a mask for an electron beam exposure apparatus (for example, LEEPL (Low Energy E-Beam Proximity Lithography)) in which the pellicle can not be used, or a mask for EUVL (Extreme Ultraviolet Lithography) In this case, the mask can be remanufactured immediately when particles that cannot be removed or damage occurs.
[0043]
【The invention's effect】
According to the present invention, a pattern projection apparatus using a two-dimensional array of light control elements can generate a large amount of patterns instantaneously, and therefore can increase the pattern drawing speed. In addition, unlike normal EB, it is easy to reduce the size and cost, and it is easy to process a plurality of devices side by side, so that a plurality of images in a plurality of master masks can be drawn simultaneously. Therefore, the pattern drawing time for all the master masks can be shortened to be the same as the pattern drawing time for one master mask.
[0044]
An ordinary EB drawing apparatus is said to cost about 1.5 billion yen, and it is extremely difficult to draw a plurality of master masks at once by using a plurality of them.
[0045]
In addition, a digital micromirror device is used as a two-dimensional array of light control elements, and the laser light reflected by each micromirror in the digital micromirror device is passed through the microlens array, thereby projecting with a high reduction ratio. Since the lens is unnecessary, the pattern projection apparatus can be significantly reduced in size and price. Therefore, even if the number of master masks increases, it is easy in terms of money to arrange the pattern projection devices by the number of master masks, and the drawing time does not increase.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a pattern projection apparatus used in a mask creation method of the present invention.
FIG. 2 is an explanatory diagram showing a pattern drawing method by a pattern projection apparatus.
FIG. 3 is an explanatory diagram showing a mask creation method of the present invention.
FIG. 4 is an explanatory diagram showing a mask creation method of the present invention.
FIG. 5 is an explanatory diagram of pattern drawing by the pattern projection device used in the mask creating method of the present invention.
[Explanation of symbols]
1, 11a, 11b, 11c, 21, 31a, 31b, 31c, 31d Master mask substrate 2 Mirror device projection area 6 Mirror device 7 Micro lens array 8 Pinhole plate 9a, 9b Lens 10a, 10b, 10c, 20, 30 pattern Projector 33 One-way stage L1, L2 Laser light

Claims (14)

Create multiple master masks by drawing patterns on multiple master mask substrates using multiple pattern projection devices at once.
A mask creation method for creating a mask by drawing a pattern on a mask substrate by reducing and projecting the plurality of master masks using a reduction projection optical system ,
Each of the pattern projection devices is
A digital micromirror device in which a plurality of micromirrors are arranged two-dimensionally as a two-dimensional array of light control elements;
And a microlens array comprising a plurality of microlenses arranged two-dimensionally corresponding to the plurality of micromirrors so as to pass laser beams reflected by the plurality of micromirrors in the digital micromirror device, respectively. A mask creation method. The mask creation method according to claim 1, wherein a mirror device projection region by at least one of the pattern projection devices is disposed obliquely with respect to the scanning direction on the master mask substrate. Each mirror device projection area by all plurality of said pattern projection apparatus, a mask generating method according to claim 2, disposed obliquely with respect to the scanning direction of the master mask substrate. A plurality of master mask substrates are continuously placed on a one-way stage, and each master mask substrate is conveyed in the one direction at a time. mask making process according to any one of claims 1 to 3 carried out continuously without placing the interval drawing for the master mask substrate. Using the plurality of pattern projection devices, a plurality of units for each of a plurality of master mask substrates,
A plurality of master mask substrates are placed on the same XY stage, each master mask substrate is scanned in the Y direction at a time, and each master mask substrate is collectively stepped in the X direction so that each master mask is mask making process according to any one of claims 1 to 3 the entire surface of the substrate by drawing to create a plurality of master masks collectively. The mask creation method according to any one of claims 1 to 5 , wherein a space between the lens closest to the substrate mask among the plurality of lenses constituting the reduction projection optical system and the mask substrate is filled with a liquid. When exposure is performed on the mask substrate by the reduction projection optical system so as to connect the patterns formed by a plurality of master masks, the endmost line of the lines composed of pixels drawn by the mirror device projection area in each master mask mask a method as claimed in any one of claims 1 to 6 is exposed to the share with each other. A plurality of pattern projection devices for creating a plurality of master masks by drawing a pattern on a plurality of master mask substrates using a batch,
Possess a reduced projection optical system for creating a mask a pattern is drawn on the mask substrate by reduction projection said plurality of master masks,
Each of the pattern projection devices is
A digital micromirror device in which a plurality of micromirrors are arranged two-dimensionally as a two-dimensional array of light control elements;
And a microlens array comprising a plurality of microlenses arranged two-dimensionally corresponding to the plurality of micromirrors so as to pass laser beams reflected by the plurality of micromirrors in the digital micromirror device, respectively. Mask making device. The mask creation apparatus according to claim 8 , wherein a mirror device projection area by at least one pattern projection apparatus is arranged obliquely with respect to a scanning direction on a master mask substrate. Each mirror device projection area by all plurality of said pattern projection apparatus, a mask generating apparatus according to claim 9 which is arranged obliquely with respect to the scanning direction of the master mask substrate. A plurality of master mask substrates are continuously placed, and each master mask substrate has a unidirectional stage for conveying the master mask substrates in one direction at a time,
Mask generating apparatus according to any of claims 8 to 10 carried out in the pattern projection device drawing for the previous master mask substrate is terminated without setting interval drawing for the next master mask substrate continuously. While having a plurality of the pattern projection device for each of a plurality of master mask substrates,
A plurality of master mask substrates are mounted, each master mask substrate is scanned in the Y direction at once, and the same XY stage for stepping each master mask substrate in the X direction is provided.
Mask generating apparatus according to any of claims 8 to 10 to create a plurality of master masks collectively by drawing the entire surface of the master mask substrate. Most substrate mask generating apparatus according to any of claims 8 to 12 is filled with the liquid between the lens and the said mask substrate close to the mask of a plurality of lenses constituting said reduction projection optical system. When the reduction projection optical system performs exposure on a mask substrate so as to connect patterns formed by a plurality of master masks, the reduction projection optical system forms the end of a line composed of pixels drawn by the mirror device projection area in each master mask. mask generating apparatus according to any of claims 8 to 13, the exposure to share the line with each other.

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