JPS6041340B2 - Photomask manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photosensitive material for photomasks and a method for manufacturing a photomask using this material.

Photomasks used in the manufacture of semiconductor components such as integrated circuits include an emulsion mask consisting of a silver image created from a high-resolution dry plate, and an opaque inorganic thin film consisting of chromium, other metals, or their oxides, etc., placed on a transparent substrate. A hard mask in which this thin film is imaged is in practical use. The present invention relates to the latter hard mask. Generally speaking, a hard mask manufacturing method is such that a photoresist is coated on an opaque inorganic thin film layer such as a thin chromium film deposited on a transparent substrate, and after processes such as exposure, development, and baking, the thin film layer is A photomask is obtained by etching the exposed portion where no photoresist film is present.

Conventionally, photoresists are generally made of photosensitive polymeric substances, have a sensitive wavelength range around near-ultraviolet light, and have much lower photosensitivity than silver salt photosensitive materials.

Therefore, it is necessary to use a powerful short-wavelength light source such as a mercury lamp or a xenon lamp as the light source for exposure, and to perform a relatively long exposure time, making it impossible to use a tungsten incandescent lamp or xenon flash exposure method. Therefore, two types of light sources are required in this field: one for emulsion mask production and one for hard mask production. On the other hand, recently, a method has been developed in which a silver salt emulsion is processed in a groove pattern so that it can function as a photoresist, which was previously impossible.
No. 007 and Tokken No. 50-31479). These methods have made it possible to directly obtain hard masks using emulsion mask manufacturing equipment. The outline of these new laws is as follows. That is, as a photosensitive material for a photomask, a material is used in which an opaque inorganic thin film layer for a mask made of chromium or the like is deposited on a transparent substrate such as glass, and a silver salt emulsion layer is further formed thereon. Since the photosensitive layer is a silver salt emulsion, image exposure, development, and
Perform fixation. Then, it is baked at a temperature of about 40,000 yen, for example, and the binder layer made of gelatin or the like in the non-silver image area is removed by dissolving it in an aqueous solution of sodium hypochlorite or by treating it with oxygen plasma. Because the silver image area is not attacked by the hypochlorous acid aqueous solution, and because the etching speed by oxygen plasma is much slower than the non-silver image area, it remains, and this silver image area plays the role of a corrosion resistant film after drying or as it is. to do.
Finally, if the exposed opaque thin film layer is removed by chemical etch, sputter etch, plasma etch, etc.
A finished hard mask is obtained. This method has the advantage that since the photosensitive layer is a silver salt emulsion, it has high photosensitivity and that tungsten lamps, xenon flash lamps, etc. can be used freely.

However, in this method, since the opaque thin film layer for the mask consists of a single layer, defects such as pinholes and foreign matter that occur in the original image, iron salt emulsion layer, and opaque thin film layer during the photomask manufacturing process can be avoided. Removal and obtaining a completely defect-free photomask requires a complicated process. However, in recent years, semiconductor components and other components, which are the fields in which photomasks are used, have been required to become smaller and more highly integrated.
The degree of this is gradually increasing.

In such ultra-fine precision parts, not only the accuracy of component images but also the occurrence of defective images or defective lines is critical. This is because even in a highly integrated component with thousands of elements, each component has its own role, and if a defect occurs in one of them, the entire function will be disrupted or stopped. This is because Even if there is a defective image, a slight deviation in dimensional values will not cause the entire part to stop functioning, but defects such as disconnections or short circuits will completely stop the function. In other words, fatal defects that exist in straight parts are a determining factor in the yield rate in parts manufacturing. For this reason, the starting photomask image is required to be completely defect-free. However, in actual photomask manufacturing methods, it is almost impossible to satisfy this requirement, at least from an economic standpoint.

On the other hand, although such a requirement has been challenged and several methods have been proposed, they are still incomplete for various reasons. The principle of these proposed methods is to achieve the objective by combining two types of organic photoresist films with different properties against solvents, developers, etc. Since there is no organic photoresist that exhibits different characteristics, there are still many problems in principle and in practice, so it cannot help but be said to be incomplete. Therefore, the present inventors have proposed a method that can easily and safely achieve the above object without relying on the combination of organic photoresist films as described above (Japanese Patent Laid-Open No. 51-948).

This method involves forming two opaque thin film layers with different etching characteristics on a transparent substrate, and imaging the thin film layers using conventional photoresist techniques. However, this method also relied on an organic photoresist as the photosensitive material, and was unsatisfactory in terms of sensitivity. In addition, when creating a hard mask from a photosensitive material for a photomask using the above-mentioned silver salt emulsion, as mentioned above, a hard mask substrate that is completely defect-free (for example, without any pinholes or material abnormalities) is required. The material is actually very difficult to obtain and expensive.

Although high sensitivity characteristics are provided on such an expensive substrate material, a photosensitive material coated with a silver salt emulsion is inevitably more expensive. Furthermore, even if the above defect-free photosensitive material is used, there is no guarantee that a defect-free hard mask will be obtained from it, and various defects will occur during the photomask manufacturing process (for example, due to adhesion of foreign matter, etc.).
Moreover, the reality is that the number of such process-generated defects is far greater than the raw material defects, and it is extremely uneconomical to discard a defective photomask due to the occurrence of defects.
Since expensive materials are used, it is essential that a 100% good product be obtained when a photomask is manufactured under normal use. The present inventors have discovered that after coating, the coating film thickness of the silver salt emulsion decreases to approximately 1'9 mm by the time it dries, resulting in an extremely dense coating film, and that the film thickness is also lower than that of conventional organic photoresists. Since it is relatively large (typically about 2 Buddhas), defects such as pinholes in the coating layer itself are extremely small (if the emulsion is perfect, defects can be completely eliminated), and its photosensitivity is A photosensitive material with high photosensitivity and with which a completely defect-free hard mask can be created is created by using a transparent substrate having two inorganic thin film layers with different etching characteristics. I found out what I got.

The present invention provides a photosensitive material that satisfies the above-mentioned essential conditions by providing a silver salt emulsion layer on a transparent substrate on which two thin film layers having different etching characteristics are formed.

The present invention will be explained in detail below with reference to the drawings.

The structure of the photosensitive material of the present invention is shown in FIG. That is, it is formed by laminating a colored transparent thin film layer 2, an opaque thin film layer 3, and a silver salt emulsion layer 4 on a transparent substrate (for example, a glass plate). Here, a colored transparent thin film layer 2 and an opaque thin film layer 3
and have different chemical properties. For example, for a method in which the colored transparent thin film layer 2 can be etched, the opaque thin film layer 3 is either not etched at all, or its etching speed is significantly lower than that of other layers; For methods in which the opaque thin film layer 3 can be etched, the colored transparent thin film layer 2 is not etched at all, or is made of a material whose etching rate is significantly lower than that of other layers. There must be. Furthermore, it is preferable that both of them have splitting characteristics that can individually block light at the wavelength to which the silver salt emulsion is sensitive. Materials for the colored transparent thin film layer 2 that have photomask properties include, for example, cadmium sulfide (yellow), arsenic sulfide (yellow), selenium (red), and cadmium selenide (yellow to red).
, iron oxide (light), amorphous silicon (foundation), silicon-germanium mixed oxide (light brown), etc., which are relatively rare, and the mask materials of this type that are in practical use include iron oxide, amorphous silicon, etc. It is.

Amorphous silicon is good in terms of chemical resistance, and silicon-germanium mixed oxide systems, which have similar properties, are also good. Further, as the material for the opaque thin film layer 3, for example,
Chromium, nickel, tantalum, tungsten, molybdenum, etc. have good properties, and the most commonly used material for this type of mask is chromium.

In the present invention, the objective can be achieved by selectively combining the various colored transparent materials and opaque materials described above, but it is possible to achieve the object by selectively combining the various colored transparent materials and opaque materials described above.

The combination of these materials is optimal in terms of substrate manufacturing and chemical properties. These materials can be easily laminated as a thin film of any thickness on a transparent substrate by vacuum evaporation or sputtering. For example, in the case of amorphous silicon and silicon-germanium mixed oxide thin films, etching methods for the above materials include etching with a maric acid-based aqueous solution and plasma etching in a fluorine compound gas such as fluorocarbon (CF4). In the case of chromium and chromium oxide thin films, etching with ceric nitrate-perchloric acid aqueous solution, argon-chlorine-oxygen (or air) etching, etc. have been established. Gas etching by mixed gas etc. has been established.

Here, the other is not substantially eroded due to the action of each etching agent. 4. It is easy to select an etching agent that does not attack each other in combination with other colored transparent materials and opaque materials. Note that the color transparent thin film layer does not necessarily have to be a colored transparent layer, and may be a colorless transparent layer or an opaque layer, but it is necessary to have the above-mentioned etching characteristics. .

Next, a typical example of the manufacturing process of a photomask using the photosensitive material shown in FIG. 1 will be explained with reference to FIGS. 2 to 6.

FIG. 2 shows that the silver salt emulsion layer 4 of the photosensitive material shown in FIG. 1 was exposed through a photographic original plate 5 having a predetermined opaque original image 54 and transparent original image 52, and then developed, fixed, and baked. Thereafter, the unexposed non-line drawing twill portion is removed by a method to be described later, and a silver image 41 having a negative/positive relationship with the transparent original image 51 is formed. In addition, if there is a defect such as a pinhole 52 in the opaque original image 54 of the photographic original plate 5 during the process of processing the original photographic plate 5, the silver salt emulsion layer 4 in the corresponding portion will be exposed and remain, resulting in the formation of ominous dots. 42 is formed.

In addition, an opaque foreign substance 53 is present in the transparent image area 51 of the photographic original plate 5.
If it is attached, the light is blocked by it, and the armor door thorns that should be exposed are not exposed, and pinholes 43 are formed in the silver image 41. Unnecessary dots 42 and pinholes 43
In addition to the above-mentioned causes, there are other causes such as foreign matter entering the silver salt emulsion layer 4, local defects in the emulsion layer itself, and adhesion of dust and other foreign matter to the surface. It may be considered impossible to maintain the silver salt emulsion layer 4 completely defect-free in terms of materials and processing steps.

Therefore, the above-mentioned unnecessary dots 42 and pinholes 43 will inevitably occur, although the number may vary. Baking refers to heating the silver salt emulsion layer after fixing in air or other gas (eg, argon, nitrogen, oxygen, hydrocarbon, halogenated hydrocarbon, etc.).

The baking temperature is 250°C or higher, preferably 300°C or higher.
The range is from oo to 600oo. If the temperature is lower than this, the baking time will be longer, and if the temperature is higher than this, the substrate may be deformed and the coin image may be destroyed. By the baking process, the binder is thermally relaxed, so that it is substantially no longer swollen, softened, or chemically affected by the etching solution, and is no longer impermeable to the etching solution.

That is, at the same time as it becomes resistive to the etching solution, the pyrolytic binder is not removed by the pyrolytic removal liquid from the silver image area, but is selectively removed only from the non-ferrous image area, as described below. It becomes like this. The baking time is
This is the time it takes for the binder to be thermally decomposed to have resist properties and to be selectively removed in non-silver image areas by the thermal decomposition binder removal solution as mentioned above, although it varies depending on the baking temperature. For example, if the binder consists mainly of alkali-processed gelatin with a thickness of 2 mm,
From 4 minutes at o] It is preferable to complete the course.

Following the baking process, non-silver image areas are selectively removed using a pyrolytic binder removal solution.
Aqueous solutions of commonly known bleaching agents such as potassium hypochlorite, sodium chlorite, potassium chlorite, sodium chlorate, potassium chlorate, sodium bromate, potassium bromate, etc. ranges up to % by weight) are used.

The temperature of the removal liquid is suitably in the range of 15 qC to 6000 qC, but even if the temperature is outside this range, the operation will be difficult, but it is possible to remove the pyrolytic pinter.

The removal time varies depending on the concentration, temperature, type, etc. of the removal solution, but is usually in the range of several tens of seconds to several tens of minutes.
If the baking time is too short or the baking temperature is too low, the removal time will be shortened, but the silver image area will also be easily removed, which is undesirable. Further, the selective removal of the non-silver image area is also possible by plasma etching.

Plasma etching as referred to in the present invention refers to the removal of material in that area by colliding ions or radicals in plasma, and examples thereof include low temperature gas plasma and cathode sputtering. If the silver salt emulsion layer is baked before plasma etching, the binder will be thermally decomposed, increasing the speed of plasma etching and making the binder resistive. It was found that the marking speed was lower than that of the non-silver image area. For example, oxygen gas plasma etching etches and removes non-silver image areas faster than silver image areas, exposing the underlying opaque thin film layer. If plasma etching is stopped at that point, only the silver image area will remain. When plasma etching is performed, baking is performed in air, vacuum or other gas at a temperature of 12,000 or more, preferably 150
~600qo.

If the temperature is lower than this, the baking time will be longer, and if the temperature is higher than this, the substrate may be deformed. Baking time is the time it takes for the binder to be thermally decomposed, and it varies depending on the baking temperature, but for example, if the binder is mainly made of alkali-treated gelatin with a thickness of 2 cm, it is about 10 to 20 minutes at 250oC. , 40,000 for about 2 to 3 minutes is sufficient. It has been found that baking increases the plasma etch rate by approximately twice. FIG. 3 shows an opaque thin film image 31 corresponding to the silver image 41 by etching the exposed inorganic opaque thin film layer 3 as a resist mask by etching the silver image 41 shown in FIG. A state in which the silver image 41 is removed after being formed using a chromium mixed acid solution (for example, a mixed solution of potassium dichromate and concentrated sulfuric acid) is shown.

Therefore, opaque unnecessary dots 32 and pinholes 3
3 is also accurately reproduced. If the opaque thin film layer 3 is incomplete, unnecessary dots 32 and pinholes 33
The number of defects such as the number of defects is increased compared to the case of the silver image 41. If a normal photosensitive material having only a single thin film layer is used, the completed hard mask will be completed in this state, and the number of defects in the completed hard mask will be relatively large. The etching of the opaque thin film layer 3 using the silver image 41 as a grist mask can be performed by known chemical etching, but plasma etching or ion etching can also be used.

That is, when performing plasma etching or ion etching using the silver image 41 as a resist mask, the opaque thin film layer 3
The etching of the opaque thin film layer 3 is successful if the silver image layer 41 still remains or just disappears while the exposed parts of the silver image layer 41 are completely removed by this etching. However, if the silver image layer 41 is removed before the opaque thin film layer 3 is completely removed, this step will fail. Therefore, what is required of the silver image layer 41 is a plasma etching or ion etching rate of 4 mm. In the present invention, the thickness of the silver image layer 41 serving as a resist layer is usually much larger than the thickness of the opaque thin film layer 3, and therefore the etching speed of the silver image layer 41 is higher than that of the opaque thin film layer 3. It does not need to be smaller than the ticking speed.

For example, if a chromium layer with a thickness of 0.1 inch is used as the opaque thin film layer 3, and the thickness of the iron image layer 41 is 3 inch thick,
The etching speed of the silver image layer 41 is 2 times that of the opaque thin film layer 3.
It may be as loud as . 4 and 5 relate to a method for removing unnecessary dots 32 existing on the colored transparent thin film layer 2. FIG.

Since this type of defect on the colored transparent thin film layer 2 can be seen through,
Even the smallest things can be easily discovered. 3, a positive photoresist layer (for example, M-1350 manufactured by Shitsupre Co., Ltd.) is applied to the surface, and a small area including unnecessary dots 32 and not affecting other images is locally exposed ( Spot exposure) and developing, unnecessary dots 3
2 is exposed, and the other part is protected by the resist layer 6.
The state shown in the figure is obtained.

Here, only the unnecessary dots 32 can be etched and removed using an etching liquid or plasma etching to completely eliminate them. Next, after removing the resist layer 6 and applying a negative photoresist (for example, KTFR manufactured by Kodak) to the entire surface, the pinholes 33 in the opaque thin film image 31 are looked through and searched, and the area including the pinholes 33 is removed. Spot exposure is performed on nearby areas. In this case, if the exposure atmosphere is a nitrogen gas atmosphere, polymerization is promoted. When this is developed, the resist layer 9 remains only in the spot-exposed areas, resulting in the state shown in FIG. 5 in which the pinhole 33 is locally protected by the resist layer 7. Next, the opaque thin film image layer 31 and the resist layer 7 are etched to form a resist mask, and the exposed colored transparent thin film layer 2 is etched using an etching liquid or plasma etching, and then the remaining resist layer 7 is etched. When removed, a defect-free colored transparent image layer 21 is formed.
That is, a photomask having a laminated image layer consisting of the colored transparent image layer 21 and the opaque image layer 31 is obtained. In this case, the etching of the colored transparent thin film layer 2 may be carried out by the method described above, which does not affect the opaque thin film layer 3 at all and leaves at least the resist layer 7. In this photomask, the pinhole 33 that existed in the opaque image layer 31 remains as it is, but the colored transparent image layer 21 below blocks the photoresist sensitive wavelength light, so that when applying another image from this photomask, , no pinhole effects occur. Therefore, a completely defect-free photomask can be obtained. In addition to the above-mentioned advantages of the photosensitive material in which the colored transparent thin film layer 2 and the opaque thin film layer 3 are laminated, as shown in FIG.
4 overlap each other, rarely match, and erase each other, making it possible to easily obtain a photosensitive material having a thin film layer with no pinholes, which is difficult to produce in the case of a single layer. In the above, a method of manufacturing a photomask through a process including a baking treatment after imagewise exposure, development, and fixing of a photosensitive material has been described, but the following method can be cited as another embodiment of the present invention.

One method is to imagewise expose, develop, and fix the photosensitive material (with or without drying) to form a line image area corresponding to the transparent original image, without baking. In this method, plasma etching is directly performed to remove at least the non-silver image area.

Although it is well known that photoresist layers can be removed by plasma treatment, it is not well known that the plasma etching speed of non-silver image areas of a silver salt emulsion layer is faster than that of silver image areas. .

In fact, it has been confirmed that when the silver salt emulsion layer of a photosensitive material is plasma etched, the non-silver image areas are quickly etched and removed, and the silver image areas also become thinner, albeit at a very slow speed. There is. Therefore, plasma etching may be performed such that the non-silver image area is removed, the underlying thin film layer is exposed, and the silver image area remains. That is, plasma etching is
Determined by plasma conditions (frequency, output, gas type, gas pressure, etc.). Incidentally, if the energy of the plasma is appropriately selected, the binder contained in the emulsion layer can be thermally decomposed by the heat generated by it, so that an effect similar to that of baking described above can be produced. The silver image thus obtained on the thin film layer is heat resistant, and the edges of the image are also smoother and have higher contrast than the original silver image, thus providing improved resolution.

When a silver salt emulsion layer that forms a silver image area and is not baked is etched, for example, by an oxygen gas plasma, the non-silver image area is removed first, exposing the underlying opaque thin film layer; The silver image area will remain.

Using this silver image area as a resist mask, use the method described above to
By etching the opaque thin film layer and the colored transparent thin film layer, a desired photomask can be obtained. In addition, a silver salt emulsion layer that forms a silver image area and is not subjected to baking can be etched by, for example, freon (CC12F2) sputtering to "not only form a non-silver image area in the emulsion layer but also opaque the underlying opaque area." It is also possible to remove thin film layers.

Furthermore, after the silver salt emulsion layer of the photosensitive material is imagewise exposed and reverse developed, the silver image area corresponding to the opaque original image is removed by etch bleaching, and the remaining binder image (corresponding to the transparent original image) is removed. The object of the present invention can be achieved even if the subsequent food waste zero treatment is performed as a mask.

Here, etch bleaching refers to a processing method that utilizes the phenomenon that when a layer containing a silver image is treated with an etch bleaching liquid, the silver image portion falls off from the support together with the binder.

The composition of the etch bleach solution can also be appropriately selected from known ones. For example, compositions consisting of cupric chloride, citric acid and hydrogen peroxide; compositions consisting of cupric nitrate, potassium bromide, lactic acid and hydrogen peroxide; ferric nitrate, potassium bromide, lactic acid and peroxide; For example, the composition consists of hydrogen water. It is sufficient to consider that the etch bleaching process is completed when the silver image completely disappears, so there is no need to specifically indicate the processing time. The present invention will be explained in more detail below using examples.

Example 1 A 4×4-inch transparent glass plate whose surface had been cleaned was placed in a high-frequency sputtering apparatus, and two target electrodes were attached with silicon and chromium, respectively.

The inside of the sputtering equipment was set to an argon atmosphere with a vacuum level of 10 [2 torr], and sputtering was first performed using a silicon target electrode to deposit a silicon thin film to a thickness of approximately 2500 A on a glass plate, and then the switch was made to a chromium target electrode. Chromium sputtering was performed to deposit a 1000 Å thick chromium thin film on the silicon film.
After placing a part of the laminated substrate thus obtained in the sputtering system and separating the other laminated substrates from the system, several percent of air was introduced into the apparatus to create an argon-air mixed atmosphere. Sputtering was performed again.

After the atmosphere was exchanged, reactive sputtering of oxygen occurred, and a thin chromium oxide layer was formed on the chromium thin film. When the thickness of this chromium oxide layer was 200 to 300 Å, the underlying chromium thin film lost its metallic luster, but at this point the entire sputtering operation was completed. The obtained laminated substrate consists of a laminated substrate with a silicon thin film and a metallic luster (reflectance of 50 to 60%) on the surface, and a laminated substrate with a low surface reflectance (reflectance of 2 to 60%) consisting of a silicon thin film, a chromium thin film, and a chromium oxide thin film. 5%
) and two types of so-called surface antireflection type laminated substrates.

When these substrates were inspected for pinholes using transmitted light under an optical microscope, several clear-colored pinholes were found.
There were no colorless pinholes at all, and it was shown that the substrate had no defects in appearance as a substrate for a photomask. Then,
A high-resolution line salt emulsion was applied to the above substrate using a spinner for about 2
A silver salt photosensitive material consisting of two types of substrates was created by applying the film to the thickness of a mountain surface.

The silver salt emulsion used here is, for example, a 140' silver bromide emulsion (average grain size of silver bromide is about 0.06') prepared using 500 g of gelatin and 188 g of bromide. This was optically sensitized to 510 to 56 mm by adding 0.15 mm of 5-[2-(3-methylthiazolinidene)ethylideso]-3-carboxymethylhodanine. Next, the photosensitive material was exposed to an integrated circuit pattern including a black image of two French desks by a contact exposure method using a tungsten light source.

The proper exposure amount needed to be 10 to 20% higher for the metallic gloss substrate and for the antireflection type substrate.
Then, the usual processes of fixing, washing, and drying were carried out. The compositions of the developer and fixer used are as follows.
Developer 1-phenyl-3-pyrazolidone 0.5 t Sodium sulfite (anhydrous salt) 50 t Hydroquinone 12 t Sodium carbonate (monohydrate) 60 T Potassium bromide
2 evening penzotriazole
0.2 1-phenyl-5-mercaptotetrazole 5-9 phenazine-2-carboxylic acid
Add 1 tsp of water and set aside.

Fixer 70% ammonium thiosulfate aqueous solution 200'
Sodium sulfite (anhydrous salt) 15 Taboric acid 8 Yugla acetic acid
16'aluminum sulfate
10T sulfuric acid (98%)
2 Add water and set aside.

After fixing and drying, the photosensitive material was placed in a 400 qo oven and baked for about IQ minutes, and then soaked in a 5% solution of sodium hypochlorite to remove the gelatin layer in the non-silver image area. A relief pattern of silver images was created.

At this point, the pattern was inspected for defects, but the defect discovery rate was low because it was a reflected light inspection. Furthermore, the laminated substrate with the silver image formed thereon is coated with the silver image as a resist mask.
The exposed comb layer, chromium oxide layer, and chromium layer are etched with a ceric ammonium nitrate monoperchloric acid aqueous solution, and after completion, the silver image is removed by immersion in a 9000 chromium mixed acid solution. A chromium layer corresponding to a silver image and an opaque pattern consisting of a chromium oxide layer and a chromium layer were obtained.

When this opaque pattern was inspected under magnification using transmitted light, more than ten defects were found. On the entire surface of the opaque pattern side of the obtained laminated substrate with two types of opaque patterns,
Positive photoresist AZ-1350 (manufactured by Shipley)
was spin-coated onto the mountain surface to a thickness of 0.6 mm.

After pre-baking at 9000°C, spot exposure was applied to unnecessary dots and defective protrusions of the image using a spot exposure device, followed by development, drying, and post-baking at 140°C.
After kinging, the defective portions were etched and removed using a chrome etching solution.

Next, the remaining resist film was dissolved and removed with 90 oo of chromic acid solution, washed with water, dried, and then coated with negative photoresist K again.
Spin-coat TFR (manufactured by Kodak) to a thickness of approximately 1 inch, pre-baked at 900°, spot exposure to pinholes and defective concave areas of the image, develop, dry, and apply post-baking at 12,000°. - Kinging was performed to form a protective film of resist on the spot exposed portions. Then,
The cast silicon thin film layer was etched using a silicon etching solution. In this case, the chromium and chromium oxide thin film layers were not attacked at all, allowing accurate etching. Finally, the remaining resist film was removed in a chromium mixed acid with a concentration of 9.0 mm, washed with water, dried, and inspected for defects using a 40-degree microscope. No defects were found in the resulting photomask. Example 2 Using two types of substrates on which the silver image relief produced in Example 1 was formed, the chromium thin film layer, chromium oxide, and chromium thin film layer were exposed in a gas atmosphere with the following composition under reduced pressure (1 to 2 torr). Gas plasma etching was performed on the part (
(using LFE's PES/PDE/PDS-501 gas plasma etching apparatus).

As a result, the silver image is hardly eroded, only the chromium and chromium oxide thin film layers are etched, and there is no side etching.
A colored transparent thin film layer of precise dimensions appeared on the non-ferrous image area. Next, the silver image was removed using the same machine as in Example 1, unnecessary dots were erased, and a resist film was formed to protect spots such as pinholes in the opaque thin film layer, and then an opaque thin film image was formed using a gas having the following composition. The resisted silicon colored thin film layer was gas plasma etched. In this case, the opaque thin film image was not eroded at all and only the silicon thin film layer was easily removed. Finally, the remaining resist film was dissolved and removed, washed with water, and dried to obtain a defect-free photomask having a high surface reflectance and an antireflection type photomask having a low surface reflectance in the same manner as in Example 1. Etching gas composition of chromium and chromium oxide thin film layer Oxygen 2-3% Chlorine
25-30% Argon 65-75% Silicon thin film layer etching gas composition Freon (CF4) 95% Oxygen 5% Example 3 In Example 1, the non-silver image area was removed from the photosensitive material after baking. A photomask was manufactured in the same manner as in Example 1 or 2, except that oxygen gas plasma was used, and similar results were obtained.

Example 4 A photosensitive material prepared in the same manner as in Example 1 was subjected to image exposure, development, fixation, and drying, and then subjected to oxygen gas plasma treatment to remove the non-silver image area in the silver salt emulsion layer and to form a silver image relief. A substrate was fabricated.

The subsequent steps were similar to those in Example 1 or 2 to produce a photomask, and similar results were obtained. Example 5 A photosensitive material prepared in the same manner as in Example 1 was subjected to image exposure,
By subjecting the developed material to Freon (CC12F2) sputtering, not only the non-silver image area in the Zenishio emulsion layer but also the underlying opaque thin film layer can be removed at the same time.

Next, remove unnecessary dots existing on the transparent thin film layer,
The process of covering the pinhole portion of the opaque thin film layer with photoresist and then etching the transparent thin film layer is the same as in Example 1. The obtained photomask was also equivalent to that obtained in Example 1 and the like. Example 6 A photosensitive material prepared in the same manner as in Example 1 was subjected to image exposure,
After development, bleaching with a mixed acid of dichromic acid and concentrated acid salt, and then uniform exposure, after development, without fixing, or after fixing, with cupric chloride, citric acid, hydrogen peroxide moat. Etch bleach with liquid and dry.

A photomask was manufactured in the same manner as in the previous example from a substrate on which a binder image relief corresponding to the transparent original image thus obtained was formed. This mask was also equivalent to that obtained in Example 1 and the like. In the above, the case where a colored transparent inorganic thin film layer is used as the thin film lower layer is explained as an example, but the thin film lower layer is not limited to this, and the thin film lower layer may be colorless and transparent or opaque.In short, the upper layer and the lower layer are as described above. However, the present invention can be practiced with other materials having different etching characteristics.

However, searching for defects such as unnecessary dots and pinholes becomes more difficult in the order of colored transparent thin films, colorless transparent thin films, and opaque thin films.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of the photosensitive material for photomasks of the present invention, FIGS. 2 to 6 are diagrams for explaining the photomask manufacturing process using the photosensitive material of the present invention, and FIG. , is a diagram for explaining the effects of the present invention. In the figure, 1: transparent substrate, 2: colored transparent inorganic thin film layer,
3: Opaque inorganic thin film layer, 4: Silver salt emulsion layer, 5: Original photographic plate, 51: Transparent original image, 54: Opaque original image, 52: Pinhole, 53: Opaque foreign matter, 41: Silver image, 42 : unnecessary dot, 43: pinhole, 31: opaque thin film image,
32: unnecessary dot, 33: pinhole, 6, 7: photoresist layer, 24, 34: pinhole. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. Consisting of a transparent substrate, an inorganic thin film layer provided on the substrate and consisting of two layers, a lower layer and an upper layer, and a silver salt emulsion layer provided on the thin film layer, the lower thin film layer and the thin film The silver salt emulsion layer of the photosensitive material is made of a material in which one of the upper layers is etched by an etching method, but the other is not etched, and imagewise exposed, developed, and fixed to form a silver image area for a predetermined original image. After baking the photosensitive material on which the silver image area has been formed at a predetermined temperature, the non-silver image area is selectively removed from the emulsion layer on the baked photosensitive material using the silver image area as a mask. After exposing the upper thin film layer under the image and selectively etching the exposed upper thin film layer to expose the lower thin film layer below the upper thin film layer, the silver image area is selectively removed, and then the silver image area is selectively removed. A photoresist layer is provided on a portion of the thin film upper layer other than the thin film upper layer dots existing on the thin film lower layer other than the portion, and the dots are selectively etched and removed, and then a photoresist layer is provided on the portion of the pinhole existing on the thin film upper layer. . A method of manufacturing a photomask, comprising selectively etching and removing the exposed lower layer of the thin film, and then removing the photoresist layer. 2 Consists of a transparent substrate, an inorganic thin film layer consisting of two layers, a lower layer and an upper layer, provided on the substrate, and a silver salt emulsion layer provided on the thin film layer, with the lower thin film layer and the upper thin film layer having one side opposite to the other. The silver salt emulsion layer of the photosensitive material, the other side of which is made of a non-etchable material, is imagewise exposed, developed and fixed by an etching method to form a silver image area corresponding to a predetermined original image. Using the image area as a mask, the photosensitive material is plasma etched to selectively remove the non-silver image area of the emulsion layer to expose the upper layer of the thin film below the non-silver image, and the exposed upper layer of the thin film is selectively etched. to expose the thin film lower layer below the thin film upper layer,
After selectively removing the silver image area, then providing a photoresist layer on the area other than the thin film upper layer dots existing on the thin film lower layer other than the predetermined image area, and selectively etching and removing the dots, A method for manufacturing a photomask, comprising: providing a photoresist layer in the pinhole portion existing in the upper layer of the thin film, selectively etching and removing the exposed lower layer of the thin film, and then removing the photoresist layer. 3 Consists of a transparent substrate, an inorganic thin film layer consisting of two layers, a lower layer and an upper layer, provided on the substrate, and a silver salt emulsion layer provided on the thin film layer, with the lower thin film layer and the upper thin film layer having one side opposite to the other. The silver salt emulsion layer of the photosensitive material, the other side of which is made of a non-etchable material, is imagewise exposed, developed and fixed by an etching method to form a silver image area corresponding to a predetermined original image. Using the image area as a mask, the photosensitive material was sputter-etched to selectively etch the non-silver image area of the emulsion layer as well as the thin film upper layer below the non-silver image to expose the thin film lower layer below the thin film upper layer. After that, the silver image area was selectively removed, and then a photoresist layer was provided on the area other than the thin film upper layer dots existing on the thin film lower layer other than the predetermined image area, and the dots were selectively etched and removed. After that, a photoresist layer is provided in the pinhole portion existing in the upper layer of the thin film, the exposed lower layer of the thin film is selectively etched and removed, and then the photoresist layer is removed. Method. 4 Consists of a transparent substrate, an inorganic thin film layer consisting of two layers, a lower layer and an upper layer, provided on the substrate, and a silver salt emulsion layer provided on the thin film layer, with the lower thin film layer and the upper thin film layer having one side opposite to the other. The silver salt emulsion layer of a photosensitive material, the other of which is made of a non-etchable material, is imagewise exposed by an etching method, and after reversal development, without fixing or after fixing, it is etched bleached to form a predetermined image. After forming a binder image area corresponding to the original image and selectively etching the exposed thin film upper layer using the binder image area as a mask to expose the thin film lower layer below the thin film upper layer, the binder image area is selected. Then, a photoresist layer is provided on a portion other than the dots of the thin film upper layer existing on the thin film lower layer other than the predetermined image area, and the dots are selectively etched and removed, and then the pins existing on the thin film upper layer are removed. 1. A method of manufacturing a photomask, comprising: providing a photoresist layer in the hole portion; selectively etching and removing the exposed lower layer of the thin film; and then removing the photoresist layer.