JPS63172158A - Production of photomask - Google Patents

Abstract

PURPOSE:To permit quick production of a photomask with high accuracy by forming a thin of diamond, diamond-like carbon or amorphous carbon on the surface of a substrate and projecting a high-energy beam to the specific points thereof, thereby drawing a prescribed pattern. CONSTITUTION:The substrater 1 is a flat plate made of quartz glass having high light transmittance and the flatness thereof is 1mum. The thin film 2 having the polycrystalline diamond structure is formed on the substrate 1. The thin film 2 formed in such a manner has excellent light transmittability in a wide wavelength region (0.3-40mum) from UV to IR and has also high hardness and good chemical resistance. The condensing point of the beam is adjusted to the point at which the beam does not arrive at the substrate 1 itself. The beam having the heat capacity sufficient to heat the projected part of the thin film 2 to about 1,500 deg.C is used. Since the beam can be condensed to 1mumphi in order to enhance the accuracy, the graphitized part 3 of a min. line width 1mum, i.e., the prescribed pattern of the low light transmittance is automatically drawn on the thin film 2. The quick production of the photomask having high accuracy is thereby permitted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a photomask, and in particular, to a method for manufacturing a photomask, which enables manufacturing of a photomask through two steps: forming a thin film on a substrate and drawing a pattern. It is something.

[Background technology and its problems]

Photomasks are widely used as a means for defining and drawing minute slits on semiconductor devices, precision measurement scales, and the like.

Conventionally, such a photomask is made by depositing, for example, chromium on the front or back surface of a substrate such as flat glass to form the slits, coating this with photoresist, and then applying a photoresist to a predetermined pattern using a phototransfer method or a laser beam scanning method. They are manufactured by writing a pattern, followed by etching with a negative or positive photoresist and chemicals adapted to the deposition material, followed by a resist stripping process to form a light-blocking pattern on the surface of the substrate. was.

Therefore, the conventional photomask manufacturing method described above has the following problems.

That is, since it is manufactured through multiple steps such as a vapor deposition process, a coating process, a drawing process, an etching process, and a peeling process, the manufacturing time is long and the economical burden is large. Further, even if elaborate work is performed in the drawing process, side etching phenomena occur in the etching process, resulting in a problem in that the accuracy of the final product deteriorates. Furthermore, it is necessary to install treatment equipment for hazardous waste liquids etc. from each process, which also has the disadvantage of being uneconomical.Furthermore, in order to avoid scratches and breakage and to endure long-term use, There was a problem in that the pattern had to be protected.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing a photomask that can quickly manufacture a photomask with high precision through two steps of forming a thin film and forming a pattern.

(Means and effects for solving the problems) The present invention has the following features:
Focusing on the extremely high precision of drawing and other processes in conventional manufacturing methods and the fact that when a diamond structure, etc. is irradiated with a high-energy beam, it turns into graphite and the light transmittance of that part disappears. The present invention aims to solve the above-mentioned problems of the conventional method by making it possible to manufacture the device in two steps: forming a pattern and directly drawing a pattern thereon.

For this reason, a thin film of diamond, diamond-like carbon, or amorphous carbon is formed on the surface of a substrate with high light transmittance, and then a high-energy beam is irradiated to specific parts of the thin film to reduce its light transmittance. The above object is achieved by forming a photomask by drawing a predetermined pattern.

Therefore, if a thin film such as a diamond structure is formed on the surface of a substrate, and the thin film is irradiated with a high-energy beam so as to draw a predetermined trajectory, the corresponding area is graphitized.
A predetermined pattern can be formed in which the light transmittance of that portion is reduced and the light transmittance is low in the remaining portion, and a photomask can be manufactured using two steps of forming a thin film and forming a pattern.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a photomask according to the present invention will be described in detail with reference to the drawings while citing an automatic lithography apparatus that is one for carrying out the method.

First, film formation for forming a thin film on a substrate will be explained. In FIG. 1(A), a substrate 1 is a flat plate made of quartz glass with high light transmittance, and its flatness is 1 μm. Then, the temperature of the substrate 1 is kept at 900°C under a relatively low pressure (40 Torr), and hydrocarbon methane (CH
4) Using a mixed gas of hydrogen (H2) and hydrogen (H2) as a reaction gas, microwaves (2.45 GHz) are introduced through a waveguide to generate discharge plasma around the substrate 1 while ionizing the mixed gas to chemically The so-called plasma vapor phase illumination method (which generates active radicals and ions to promote chemical reactions)
As seen in FIG. 1(B), the substrate 1 is
A thin film 2 having a polycrystalline diamond structure having a thickness of about 5 μm was formed thereon. However, depending on the reaction time, etc., the film thickness may be, for example, 100 μm, or may be several thousand amps. The thin film 2 thus formed has excellent light transmittance in a wide wavelength range (0.3 to 40 μm) ranging from ultraviolet to infrared, and has high hardness and good chemical resistance.

Next, the process of drawing a predetermined pattern will be explained.

The automatic pattern drawing device used in this example is composed of a main body 10, a control device 20, a CPU 30, and a storage device 40, as shown in FIG. 2, and draws a predetermined pattern using a high-energy electron beam. . The main body 10 consists of an X-table 11 that is reciprocated by a motor 13 in the X-axis direction shown by the arrow in the figure (screw mechanisms, etc. are omitted), and a Y-table that is reciprocated in the Y-axis direction by a Y motor 14. 12 (screw mechanism etc. are omitted),
It consists of an electron optical system formed including an electron gun 15, a condensing lens 16, 16, a blanking electrode 17, and an aperture 18, and a beam output from the electron gun 15 is formed by an acousto-optic modulator (AOM). blanking electrode 1
7, the beam is irradiated onto the thin film 2 of the substrate 1 set on the X table 11. The AOM operates so that the beam irradiates onto the thin film 2 when the signal from the blanking control unit 22 (to be described later) is "O", and is blocked by the aperture 18 when the signal is "1". However, the driver etc. are not shown.

The control device 20 also processes design pattern data from an electron optical system adjustment unit 21 for adjusting beam current, beam diameter, etc. and a storage device 40 formed from a magnetic tape or a magnetic disk in a predetermined manner using a CUP 30. Each table 11.12 is synchronized with blanking control etc. by the blanking control unit 22 which outputs a blanking signal based on the determined drawing pattern equivalent signal and the CPU 30.
In order to perform good beam scanning, the timing of the feed control unit 24, which positions and controls the blanking control unit 22, the feed control unit 24, etc., is adjusted by detecting the actual transfer displacement amount of each table 11, 12, etc. It is formed from a scanning control unit 23.

Therefore, by setting the substrate 1 on which the diamond-structured thin film 2 is formed on the X table 11 of the main body 10, setting the corresponding pattern design data to be drawn on the substrate 1 in the storage device 40, and starting up the entire system, CPU30
Blanking control unit 2 based on the command signal from
2 works to blank the beam from the electron gun 15, and the feed control unit 24 reciprocates each table 11, 12, so that the thin film 2 on the substrate 1 is irradiated with a high-energy beam in a trajectory that draws a predetermined pattern. be done.

Here, since the electron optical system including the electron gun 15 uses a focused beam to graphite the irradiated part of the thin film 2 to make it have low light transmittance, the focused point of the beam is on the substrate 1 itself. It is designed to be a point that cannot be reached, and has enough heat capacity to heat the irradiated part of the thin film 2 to about 1500°C, and is also designed to be able to focus the beam to 41 μm for high precision. Therefore, a graphitized portion 3 with a minimum line width of 1 μm, that is, a predetermined pattern with low light transmittance, can be automatically drawn on the thin film 2 of the substrate 1 (see FIG. 1(C)).

Here, the photomask 5 could be manufactured.

Furthermore, in this example, after pattern drawing to ensure practical protection, a diamond structure protective film 4 with an average diameter of 5000A was formed on the thin film 2 by the same method as the thin film forming process described above (see Fig. 1). (See (D)).

Therefore, according to this embodiment, the photomask 5 can be formed by simply forming the diamond-structured thin film 2 on the substrate 1 and forming a predetermined pattern while irradiating it with a high-energy beam. It is possible to manufacture high-precision products quickly compared to conventional methods. Further, since the diamond structure has excellent light transmission characteristics in a wide wavelength range, it has sufficient optical characteristics as the photomask 5, and also has high hardness, mechanical strength, and chemical resistance, so long-term stable use is guaranteed. Further, since the pattern is formed integrally within the thin film 2 and there are no irregularities caused by chromium vapor deposition and etching methods, there is no deformation or loss of the pattern, and high precision can be maintained for a long period of time.

In addition, since the photomask 5 is completed in two steps, and the pattern is automatically formed using a pattern drawing device, mass production can be carried out in a short period of time, and since there is no conventional etching process, high precision is achieved from this point of view. Guaranteed.

Although the substrate 1 is made of quartz glass in the above embodiments, other glass (blue plate, white plate, etc.) may be used as long as it is capable of forming the thin film 2 and has high light transmittance. It can also be carried out with substrates.

Further, although the thin film 2 is formed by the CVD method, the thin film 2 may be formed by a thermal filament method, an ionized vapor deposition method, a sputtering method, a laser vapor deposition method, etc., since it is sufficient to have a diamond structure.

Moreover, although the pattern drawing method is performed by an automatic drawing device using an electron beam, the device is not limited to the scope disclosed above, and drawing may be performed using a laser beam, an X-ray, or the like.

Furthermore, the above-mentioned diamond structure is a concept that includes so-called diamond-like carbon, amorphous carbon, etc., since it is sufficient if a part of it can be made into graphite with low light transmittance. The high energy for the beam irradiation portion of the thin film 2 was set at about 1500° C. in the above embodiment, but it may be 300 to 800° C. depending on the type. As described above, in the present invention, the energy or temperature change for graphitizing, the thickness of the thin film 2, etc. can be arbitrarily selected depending on the quality grade of the photomask 5, the mode of use, etc.

(Effects of the Invention) As explained above, the present invention provides two methods for forming a thin film on a substrate and forming a pattern while turning a part of the film into graphite.
Since it can be completed in one process, it has the excellent effect of being able to quickly manufacture a high-precision photomask.

[Brief explanation of the drawing]

FIG. 1 is a process explanatory diagram showing an embodiment of the photomask manufacturing method according to the present invention, and FIG. 2 is an overall configuration diagram of an automatic pattern writing system for pattern writing. l... Substrate, 2... Thin film having a diamond structure, 3... Graphitized portion of the thin film, 4...
Protection home, 5... Photomask, 10... Body, 20
···Control device.

Claims (1)

[Claims] (1) A thin film of diamond, diamond-like carbon, or amorphous carbon is formed on the surface of a substrate with high light transmittance, and then a high-energy beam is irradiated to specific parts of the thin film to reduce its light transmittance. A method for manufacturing a photomask, characterized in that the photomask is manufactured by drawing a predetermined pattern.