JP2004264337A - Method for forming mask and mask forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a mask to produce a mask in a short time with high accuracy and to provide a mask forming apparatus so as to solve problems that an electron beam drawing apparatus used for drawing a mask requires several tens to several hundreds hours of drawing time and can not produce a mask in a short time. <P>SOLUTION: The laser light in a pattern reflected by two-dimensionally arranged micromirrors 106 controlled based on the mask data of a mask pattern data output device 107 forms an enlarged pattern 110, which is reduced and projected by a reduction projecting optical system 102 onto a mask substrate 109 to form a drawn pattern 111. As a large amount of patterns can be instantly drawn by the two-dimensionally arranged micromirrors 106, the time for drawing the entire mask patterns is shortened by orders of magnitude compared to a conventional apparatus. As a result, the mask cost can be significantly decreased. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
1. Field of the Invention The present invention relates to a method for producing a mask used in an exposure process at the time of manufacturing a semiconductor integrated circuit, and an apparatus for producing a mask. In addition, the object of the mask according to the present invention may be a photomask for photolithography using ultraviolet light or X-ray as an exposure light source, or a 1: 1 mask for an electron beam.
[0002]
[Prior art]
Generally, in order to form a mask (also called a reticle) used in the manufacture of a semiconductor integrated circuit, a surface such as a quartz plate serving as a substrate of the mask is exposed to a pattern corresponding to a target circuit pattern. It is necessary to attach a chrome film or the like that blocks light. The chromium film or the like is formed by pattern exposure, and a general method of drawing and exposing in a pattern form is electron beam drawing using an electron beam. In this method, a narrowly focused electron beam is drawn along a pattern like direct electron beam drawing, and the apparatus is usually called an EB drawing apparatus.
[0003]
In a general exposure apparatus using ultraviolet light, a mask having a size four to five times the size of a circuit pattern of a semiconductor chip to be manufactured is used. There is also an exposure method using a mask (hereinafter, referred to as an equal-size mask). This is called 1: 1 exposure, and includes, for example, LEEPL (an acronym for Low Energy E-Beam Proximity Lithography) and 1: 1 X-ray exposure. Further, in this exposure technique, an equal-magnification mask is arranged directly above a wafer, and an electron beam is irradiated from above the mask with LEEPL and an X-ray is irradiated with equal-magnification X-ray exposure.
[0004]
On the other hand, as a mask manufacturing apparatus, pattern writing (that is, exposure of a mask substrate coated with a resist in a pattern) using an ultraviolet laser beam (hereinafter, abbreviated as an ultraviolet laser beam) instead of an electron beam is performed. ) Is also commercialized (sometimes called a laser beam drawing apparatus). This apparatus has two types of constitutions, one of which is to pattern-draw one or a plurality of divided ultraviolet laser beams on a mask substrate. Another configuration is to use a reflecting mirror display element (a device called a digital micromirror or the like) in which a large number of minute mirrors are arranged in a two-dimensional array, irradiate this with ultraviolet laser light, and reflect the reflected light. A pattern is drawn on a mask substrate by controlling the pattern. It is known that this laser beam drawing apparatus has a feature that the processing speed is high because a part of the circuit patterns can be exposed collectively. This is described in, for example, Electronic Journal, July 2001, pp. 140-142.
[0005]
[Non-patent document 1]
Electronic Journal, July 2001, pp. 140-142.
[Problems to be solved by the invention]
An issue that has been widely pointed out in recent years as a problem in mask manufacturing is the soaring price of masks. The reason for this is that the amount of information on the mask pattern becomes enormous in order to cope with semiconductors that are becoming highly integrated and miniaturized year by year. This is because it can reach tens to hundreds of hours. Since the EB lithography apparatus is an extremely expensive apparatus that costs 100 million yen to several billion yen or more, it is difficult to prepare many EB writing apparatuses, and since it is occupied for one mask for a long time, As a result of considering depreciation costs and the like, it is known that the price of a mask, when the design rule is 0.10 μm or less, is about 10 times the general mask price up to the 0.18 μm generation. I have.
[0007]
By the way, in the laser beam drawing apparatus using the two-dimensional array micro mirror, after exposing a partial pattern that can be exposed collectively, when exposing the adjacent partial pattern, it is necessary to move the mask substrate, It is difficult to increase the movement accuracy, and it is not possible to cope with miniaturization. That is, when the minimum line width of a chip to be manufactured is 0.18 μm, and when the mask magnification is four times, the movement accuracy of the mask substrate (that is, the stage movement accuracy on which the mask substrate is mounted) is 0.72 μm, the minimum line width in the mask. It was necessary to be able to move instantaneously with an accuracy of at least 1/10 of about 0.07 μm or less, which was difficult. This is because if it is attempted to move accurately with a high accuracy of about 0.07 μm, it takes time to measure the distance of the stage position.
[0008]
On the other hand, in the exposure technique using the same-size mask, it is considered that the mask can be manufactured in a relatively short time because the area of the mask is small, so that the cost of the mask can be reduced. However, since the line width of the pattern is required to be as narrow as about 0.07 μm or less, which is almost the same as that of an actual chip, it is difficult to obtain high manufacturing accuracy when manufacturing a mask using an EB lithography apparatus.
[0009]
Also, when trying to draw a 1: 1 mask using the laser beam drawing apparatus, the movement accuracy of the mask substrate is 0.007 μm, which is 1/10 or less of the minimum line width, and the stage is instantaneously moved with this accuracy. It is almost impossible. Therefore, there is a problem that there is no mask drawing apparatus capable of drawing at a high speed with respect to the same-size mask.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to provide a mask manufacturing method and a mask manufacturing apparatus capable of manufacturing a mask in a short time with high accuracy in order to solve the above-described conventional problems.
[0011]
[Means for Solving the Problems]
In order to achieve the object, the present invention includes a mask pattern projection device and a reduction projection optical device using a two-dimensional array of light control elements, and controlling the light control elements by mask pattern data. Manufacturing a first mask pattern from a mask pattern projecting device, and inputting the first mask pattern to the reduction projection optical device to form a reduced second mask pattern. Provide a method of making a mask for use.
[0012]
Also, the present invention includes a mask pattern projection device using a two-dimensionally arranged light control element, a second reduction projection optical device, and a second reduction projection optical device, wherein the light control element is controlled by mask pattern data. The first mask pattern is output from the mask pattern projecting device, and the first mask pattern is input to the second reduction projection optical device to form a reduced second mask pattern. A mask manufacturing method for manufacturing a semiconductor device, characterized in that a second mask pattern is input to the second reduction projection optical device to form a further reduced third mask pattern.
[0013]
According to this method, the mask is not directly drawn by using the first pattern formed by the two-dimensionally arranged light control elements, but by using the further reduced second pattern or the third pattern. Since the mask is formed, it is possible to increase the size of the first pattern. As a result, the movement accuracy when forming the first pattern can be increased by about one digit (ie, to a lower accuracy). Therefore, it can be moved instantaneously, and the time for drawing the whole image can be reduced.
[0014]
As the two-dimensionally arranged light control element, a liquid crystal display element, a reflecting mirror display element using a two-dimensionally arranged micromirror such as a digital micromirror or a digital mirror device, or a self-luminous element may be used. Alternatively, a plasma element, a fluorescent element, a phosphorescent element, an organic EL element, an inorganic EL element, or the like may be used.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a configuration diagram of a mask making apparatus 100 according to a first embodiment of the present invention. The mask making apparatus 100 applies the coating to the enlarged pattern generation unit 101 provided with the two-dimensional array micromirror 106 capable of forming an arbitrary pattern, the reduction projection optical system 102, the stage 103 on which the mask substrate 109 is mounted, and the mask substrate 109. An ultraviolet laser oscillator 104 that generates a laser beam L1 in an ultraviolet wavelength range to which the resist is exposed.
[0017]
The laser light L1 extracted from the ultraviolet laser oscillator 104 is reflected by the mirrors 105a and 105b, hits the mirror 105c in the enlarged pattern generation unit 101, and irradiates the two-dimensional array minute mirror 106.
[0018]
The two-dimensional array micromirrors 106 are individually controlled by the data from the mask pattern data output device 107 to control the micromirrors in a pattern of a part of the target mask drawing pattern. When the laser light incident on the mirror that forms a part of the drawing pattern is reflected here, it travels as shown by the lower laser light L2 in the figure, passes through the lenses 108a and 108b, and is shown by the enlarged pattern 110 in the figure. An image of the two-dimensional array micromirror 106 is projected on a part of the part thus formed. That is, the lens 108a and the lens 108b form a projection optical system.
[0019]
Since the pattern formed by the two-dimensional array micromirror 106 is a part of a target mask drawing pattern, the entire enlarged pattern generation unit 101 is required to form the entire enlarged pattern 110 in which the drawn pattern is enlarged. 1, the structure is capable of fine movement in the X direction and the Y direction.
[0020]
The enlarged pattern 110 is projected by the reduction projection optical system 102 onto a drawing area on the mask substrate 109 on the stage 103. Thus, the drawing pattern 111 obtained by reducing the enlarged pattern 110 is drawn on the mask substrate 109. As the enlarged pattern 110, an actual mask may be manufactured at that position, or a spatial pattern that is a pattern aggregate of ultraviolet light may be used. Regarding the configuration of the enlarged pattern generation unit 101, the configuration described in the above-mentioned document, US Pat. Nos. 5,870,176, 6,312,134, and 6,425,669 may be used.
[0021]
As shown in the present embodiment, the mask making apparatus 100 of the present invention uses the two-dimensional array micromirror 106 as the two-dimensional array light control element that constitutes the present invention. The enlarged pattern generation unit 101 itself moves while generating a part of the pattern and changing the pattern as needed, whereby the same pattern as the drawing pattern is created and becomes the enlarged pattern 110. However, since the enlarged pattern 110 alone is larger than the actual mask, a drawing pattern having the actual mask size is generated by the reduced projection optical system 102.
[0022]
As described above, according to the present invention, by having the reduced projection optical system 102, it is only necessary to first generate a magnified pattern with the same pattern as the mask drawing pattern, so that the line width of the actual mask pattern is sufficiently large. A minute mirror having dimensions can be used, and a commercially available digital mirror device or the like can be used.
[0023]
The present embodiment will be described by applying actual dimensions. For example, assume that a four-time mask for a semiconductor integrated circuit having a minimum line width of 0.18 μm is formed. In this case, the minimum line width of the drawing pattern 111 is 0.72 μm, but if the reduction magnification of the reduction projection optical system 102 is five times, the minimum line width of the enlarged pattern 110 is 3.6 μm. Therefore, the accuracy when sequentially moving the enlarged pattern generation unit 101 may be about 1/10 of this value, or about 0.36 μm. This is five times larger than the movement accuracy of 0.07 μm in the conventional device, so that the distance measurement becomes easy and the movement can be performed at high speed.
[0024]
Moreover, by increasing the reduction magnification of the projection optical system by the lens 108a and the lens 108b in the enlarged pattern generation unit 101, the enlarged pattern 110 itself can be reduced to 4 to 5 times the actual pattern of the semiconductor integrated circuit. . As a result, by further reducing the size to 1/4 to 1/5 by the reduction projection optical system 102, it is possible to make the drawing pattern the same size as the actual semiconductor integrated circuit. As a result, according to the present invention, it is possible to manufacture a 1: 1 mask with high accuracy.
[0025]
By the way, if an excimer laser (for example, a KrF excimer laser or an ArF excimer laser) is used as the ultraviolet laser oscillator 104 in the present embodiment, the reduction projection optical system 102 constituting the present invention is provided with Or an ArF exposure machine) can be used as it is. However, since the laser light from the excimer laser is a pulse laser, the energy is high, and the two-dimensional array micromirror 106 constituting the present invention may be damaged.
[0026]
Therefore, as another embodiment of the present invention, an argon ion laser is used for the ultraviolet laser oscillator 104. The argon ion laser oscillates at a number of wavelengths at the same time. Among them, particularly when only the wavelength of 363.8 nm is selected and used, the wavelength for the i-line of the mercury lamp is very close to 365 nm. A resist can be used. Further, a reduced projection optical system for an i-line exposure apparatus can be used as it is for the reduced projection optical system 102 constituting the present invention. In addition, since the argon ion laser oscillates continuously, the two-dimensional array micromirrors 106 constituting the present invention are not damaged.
[0027]
FIG. 2 is a configuration diagram of a mask creating apparatus 200 according to the second embodiment of the present invention. The present embodiment is different from the mask making apparatus 100 shown in FIG. 1 in the following two points, but has the same other basic configuration, and is different from the mask forming apparatus 100 shown in FIG. An ultraviolet laser oscillator and a pattern data output device are also used, but are omitted in FIG. The different points are the control method of the ultraviolet laser light in the enlarged pattern generation unit 202 and the configuration of the reduction projection optical system.
[0028]
The laser light L3 enters the beam splitter 221 in the enlarged pattern generation unit 202, is reflected upward, passes through the wave plate 222, and enters the two-dimensional array micro mirror 206. In the two-dimensional array micro mirror 206, the laser beam reflected by the micro mirror corresponding to the pattern forming a part of the target mask drawing pattern passes through the lens 223a, and then the aperture 224 (plate with micro holes) Pass through. On the other hand, in the two-dimensionally arranged micro mirror 206, the laser beam reflected by the micro mirror corresponding to the pattern not forming the mask drawing pattern is stopped by the aperture 224 because the reflection angle is slightly deflected. The function of the wave plate 222 is to convert the linearly polarized laser light reflected by the beam splitter 221 into circularly polarized light. After the light is reflected by the two-dimensional array minute mirror 206 and passes through the wave plate 222 again. Then, the polarization direction becomes orthogonal to the original polarization direction, and 99% or more of the light passes through the beam splitter 221 (that is, travels straight).
[0029]
In the present embodiment, the reduction projection optical system of the present invention has a two-stage configuration including a first reduction projection optical system 202a and a second reduction projection optical system 202b. Therefore, the first enlarged pattern 210a formed in front of the first reduced projection optical system 202a is a huge mask having a side of about 128 cm. Therefore, a second enlarged pattern of about 32 cm on a side is formed by the first reduced projection optical system 210a. By using the second reduction projection optical system 202b, a drawing pattern 211 of about 8 cm on a side, which is 4 to 5 times the normal size, is formed on the mask substrate 209 on the stage 213.
[0030]
A feature of the present embodiment is that the line width of the first enlarged pattern 210a can be made 64 to 80 times as large as the actual size of the semiconductor integrated circuit (that is, the wafer size) because the reduction projection optical system is used in two stages. Even if this is not formed with particularly high accuracy, the dimensional accuracy of the drawing pattern 211 formed by reducing twice finally is remarkably improved. In addition, high precision is not required for positioning of the enlarged pattern generation unit 201, and it can be moved at high speed, so that the drawing speed is further improved.
[0031]
That is, in the present embodiment, as shown in FIG. 1, the allowable range of the movement error of the enlarged pattern generation unit 201 is further increased by 4 to 5 times as compared with the first embodiment using one reduction projection optical system. It can be made larger, move faster, and create masks in less time.
[0032]
FIG. 3 is a configuration diagram of a mask making apparatus 300 according to the third embodiment of the present invention. In the mask making apparatus 300, a two-dimensional array self-luminous device 306 is used as a two-dimensional array light control element constituting the present invention. In the two-dimensional array self-luminous device 306, only the elements corresponding to a part of the target mask drawing pattern are made to emit light, and the light emission pattern is reduced by the first reduction projection optical system 302a to form the second enlarged pattern 310b. The drawing pattern 311 is formed on the mask substrate 309 on the stage 303 by the second reduction projection optical system 302b. The two-dimensional array self-luminous device 306 can scan in the X and Y directions in the figure, thereby forming a first enlarged pattern 310a in which all drawing patterns are formed.
[0033]
As the two-dimensional array self-luminous device 306 used in this embodiment, a self-luminous element such as PDP (plasma display panel), EL (electroluminescence), or LED used in a large flat panel display or the like is suitable. I have. However, these displays usually use the three primary colors of red, green, and blue light, but in this embodiment, since they are used as an exposure light source, an element that emits only monochromatic light may be used. However, it is preferable to use a material that emits light at a wavelength as short as possible, and it is preferable to use a material that emits light strongly near 365 nm (i-line wavelength) of a mercury lamp. The reason is that an i-line resist can be used as it is as a resist applied to the mask substrate. In addition, not only the self-luminous element but also a reflective mirror display element such as a liquid crystal, a digital micromirror, or a digital device for controlling light emission by a backlight may be used.
[0034]
The size of the first enlarged pattern is about 128 cm on one side and the size of the second enlarged pattern is about 32 cm on one side, as in the second embodiment. As a result, a normal drawing pattern 311 is obtained. A pattern corresponding to a 4 to 5 times mask can be formed.
[0035]
In this embodiment, the third reduced projection optical system can be used in the same manner to manufacture a 1: 1 mask.
[0036]
Meanwhile, as the light control elements of the first to third embodiments, as shown in FIG. 4A, a simple two-dimensional array light control element 410 in which the light control elements 411 are arranged vertically and horizontally may be used. However, the two-dimensional array light control element 420 in which the adjacent light control elements 421 are arranged with a slight shift as shown in (b), or the light control element 431 is tilted as shown in (c). The arranged two-dimensional array light control elements 430 may be used. By using the structure of the arrangement of (b) or (c), when scanning the light control elements, there is no gap between the exposure portions on the mask substrate corresponding to each element, so that a line is drawn in the drawing pattern. There is no interruption or a step on an oblique line, and the resolution can be improved.
[0037]
Further, the two-dimensional array self-luminous device 500 shown in FIG. 5 may be used instead of the two-dimensional array self-luminous device in the mask making apparatus 300 according to the third embodiment of the present invention shown in FIG. The two-dimensional array self-luminous device 500 is formed by arranging a number of ordinary two-dimensional array self-luminous devices 502 to form one device. To form the first enlarged pattern shown in FIG. 3 using this, the two-dimensional array self-luminous device 500 is moved by the length of the light-emitting devices in one two-dimensional array self-luminous device 502. By scanning, a pattern corresponding to a large number of light emitting devices can be formed at a time. That is, in the drawing, it is only necessary to move ΔX when scanning in the X direction and ΔY when scanning in the Y direction.
[0038]
【The invention's effect】
As described above, according to the apparatus and method according to the present invention, when drawing a mask, a large number of patterns corresponding to a part of the entire target mask pattern can be drawn instantaneously, and each partial pattern can be written at high speed. As a result, the entire mask pattern can be drawn in a matter of minutes, and the mask drawing time has been reduced by orders of magnitude. As a result, it is possible to manufacture all of the 20 to 30 masks required for normal semiconductor manufacturing within one day, and the period can be shortened to 1/10 or less of that of the related art. This has also made it possible to significantly reduce mask manufacturing costs.
[0039]
Furthermore, according to the present apparatus, a mask can be manufactured in a short period of time and at low cost. Therefore, the mask is used for manufacturing a mask for EUVL (Extremely Ultraviolet Lithography), which is concerned that an expensive mask is deteriorated in a short period of time. Even if the effect is great. That is, in EUVL, X-rays having a wavelength of 13.5 nm are used as exposure light. However, at such a short wavelength, the photon energy is extremely high, so that the mask is damaged and needs to be replaced in a short period of time. In that case, if the mask is frequently recreated using a conventional mask drawing apparatus, the production of the semiconductor will be stopped for a long time each time.
[0040]
On the other hand, in the mask making apparatus of the present invention, since the drawing speed is extremely high, all the masks can be manufactured in a short time, and as a result, the masks can be manufactured at low cost. Frequent replacement of the mask does not pose a cost or production planning problem.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a mask making apparatus according to a first embodiment of the present invention.
FIG. 2 is an overall configuration diagram of a mask making apparatus according to a second embodiment of the present invention.
FIG. 3 is an overall configuration diagram of a mask creating apparatus according to a third embodiment of the present invention.
FIGS. 4A, 4B and 4C are diagrams showing an arrangement of light control elements used in the present invention.
FIG. 5 is a plan view showing another arrangement of the self-luminous device.
[Explanation of symbols]
100, 200, 300 Mask making device 101, 201 Enlarged pattern generation unit 102 Reduction projection optical system 103, 203, 303 Stage 104 Ultraviolet laser oscillator 105a, 105b, 105c Mirror 106, 206 Two-dimensional array micro mirror 107 Mask pattern data output device 108a, 108b, 223a, 223b Lens 109, 209, 309 Mask substrate 110 Enlarged pattern 111, 211, 311 Drawing pattern 202a, 302a First reduced projection optical system 202b, 302b Second reduced projection optical system 210a, 310a First enlarged pattern 210b, 310b Second enlarged pattern 221 Beam splitter 222 Wave plate 224 Apertures 410, 420, 430 Two-dimensional array light control elements 411, 421, 431 Light control elements 306, 500, 02 two-dimensional array self-light-emitting device

Claims (13)

A mask pattern projecting device using a two-dimensional array of light control elements and a reduction projection optical device, and the first mask pattern is output from the mask pattern projecting apparatus by controlling the light control elements according to mask pattern data. And forming the reduced second mask pattern by inputting the first mask pattern to the reduced projection optical device. A mask pattern projecting device using a two-dimensional array of light control elements, a first reduction projection optical apparatus, and a second reduction projection optical apparatus, wherein the mask is controlled by controlling the light control elements with mask pattern data. A first mask pattern is output from the pattern projection device, and the first mask pattern is input to the first reduction projection optical device to form a reduced second mask pattern. Is input to the second reduction projection optical device to form a further reduced third mask pattern. 3. The method according to claim 1, wherein a micromirror in a two-dimensional array is used as the light control element. 3. The method according to claim 1, wherein a self-luminous element is used as the light control element. 3. The method according to claim 1, wherein a liquid crystal display element or a reflector display element is used as the light control element. 3. The method according to claim 1, wherein the first mask pattern is a spatial pattern. 6. A method according to claim 1, wherein an equal-size mask is obtained by the second mask pattern. 6. The method according to claim 2, wherein an equal-size mask is obtained by the third mask pattern. A mask pattern projecting device using a two-dimensional array of light control elements and a reduction projection optical device, and the first mask pattern is output from the mask pattern projecting apparatus by controlling the light control elements according to mask pattern data. A mask forming apparatus for manufacturing a semiconductor device, wherein the first mask pattern is input to the reduction projection optical device to form a reduced second mask pattern. A mask pattern projection apparatus using a two-dimensional array of light control elements, a first reduction projection optical apparatus, and a second reduction projection optical apparatus, wherein the mask is controlled by controlling the light control elements with mask pattern data. A first mask pattern is output from the pattern projection device, and the first mask pattern is input to the first reduction projection optical device to form a reduced second mask pattern. Is input to the second reduction projection optical device to form a further reduced third mask pattern. 11. The apparatus according to claim 9, wherein a micro mirror in a two-dimensional array is used as the light control element. 11. The apparatus according to claim 9, wherein a self-luminous element is used as the light control element. 11. The apparatus according to claim 9, wherein a liquid crystal display element is used as the light control element.

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