JP4834206B2 - Method for manufacturing gray-tone mask and method for manufacturing object to be processed - Google Patents

Description

The present invention relates to a gray-tone mask used for manufacturing a liquid crystal display (Liquid Crystal Display: hereinafter referred to as LCD) and the like and a manufacturing method thereof.

Conventionally, methods for reducing the number of photomasks required for manufacturing have been proposed in the field of LCDs. That is, a thin film transistor liquid crystal display (hereinafter referred to as TFT-LCD) is currently being commercialized rapidly due to its advantage of being thin and low in power consumption compared to a CRT (cathode ray tube). Progressing. A TFT-LCD includes a TFT substrate having a structure in which TFTs are arranged in pixels arranged in a matrix, and a color filter in which red, green, and blue pixel patterns are arranged corresponding to each pixel. It has a schematic structure superimposed under the intervention of. In TFT-LCD, the number of manufacturing processes is large, and the TFT substrate alone is manufactured using 5 to 6 photomasks. Under such circumstances, a method of manufacturing a TFT substrate using four photomasks has been proposed (for example, Non-Patent Document 1 below).
In this method, the number of masks to be used is reduced by using a photomask (hereinafter referred to as a gray tone mask) having a light shielding portion, a light transmitting portion, and a semi-light transmitting portion (gray tone portion).

FIG. 5 and FIG. 6 (FIG. 6 is a continuation of the manufacturing process of FIG. 5) show an example of a manufacturing process of a TFT substrate using a gray tone mask.
A metal film for a gate electrode is formed on the glass substrate 1, and the gate electrode 2 is formed by a photolithography process using a photomask. Thereafter, a gate insulating film 3, a first semiconductor film 4 (a-Si), a second semiconductor film 5 (N ⁺ a-Si), a source / drain metal film 6, and a positive photoresist film 7 are formed (FIG. FIG. 5 (1)). Next, the positive photoresist film 7 is exposed and developed using the gray tone mask 10 having the light shielding portion 11, the light transmitting portion 12, and the semi-light transmitting portion 13, thereby developing the TFT channel portion and the source / drain forming region. Then, the first resist pattern 7a is formed so as to cover the data line formation region and to make the channel portion formation region thinner than the source / drain formation region (FIG. 5B). Next, the source / drain metal film 6 and the second and first semiconductor films 5 and 4 are etched using the first resist pattern 7a as a mask (FIG. 5 (3)). Next, the thin resist film in the channel portion formation region is removed by ashing with oxygen to form a second resist pattern 7b (FIG. 6 (1)). Thereafter, using the second resist pattern 7b as a mask, the source / drain metal film 6 is etched to form the source / drains 6a and 6b, and then the second semiconductor film 5 is etched (FIG. 6 (2)). The remaining second resist pattern 7b is peeled off (FIG. 6 (3)).

  As a gray-tone mask used here, one having a structure in which a semi-translucent portion is formed in a fine pattern is known. For example, as shown in FIG. 7, the light-shielding portions 11a and 11b corresponding to the source / drain, the translucent portion 12, and the semi-transparent portion (gray tone portion) 13 corresponding to the channel portion are provided. The light part 13 is an area where a light shielding pattern 13a composed of a fine pattern below the resolution limit of an LCD exposure machine using a gray tone mask is formed. Both the light shielding portions 11a and 11b and the light shielding pattern 13a are usually formed from films of the same thickness made of the same material such as chromium or a chromium compound. The resolution limit of an LCD exposure machine that uses a gray-tone mask is about 3 μm for a stepper type exposure machine and about 4 μm for a mirror projection type exposure machine. For this reason, for example, in FIG. 6, the space width of the transmissive part 13 b in the semi-transparent part 13 is set to less than 3 μm, and the line width of the light shielding pattern 13 a is set to less than 3 μm, which is less than the resolution limit of the exposure machine.

However, the above-mentioned fine pattern type semi-transmission part is a line-and-space type design for the gray tone part, specifically, a fine pattern for providing an intermediate halftone effect between the light-shielding part and the light-transmission part. There is a choice between a dot (halftone dot) type or another pattern, and in the case of the line and space type, how much the line width is to be set, and the part through which light is transmitted is blocked. The design had to be made in consideration of many things, such as what should be done with the ratio of the parts to be measured and how much the overall transmittance should be designed. Also in mask manufacturing, management of the center value of the line width and management of line width variation within the mask and extremely difficult production techniques have been required.

Therefore, it has been conventionally proposed to use a semi-transmissive half-tone film (semi-transmissive film) for a portion to be subjected to half-tone exposure. By using this halftone film, halftone exposure can be performed while reducing the exposure amount of the halftone portion. By changing to a halftone film, it is only necessary to consider how much the overall transmittance is necessary in the design, and it is possible to produce a mask only by selecting the film type of the halftone film and the film thickness. It becomes possible. Therefore, in mask manufacturing, it is only necessary to control the film thickness of the halftone film, and management is relatively easy. Further, since a halftone film can be easily patterned by a photolithography process, even a complicated pattern shape is possible.

  A conventionally proposed method for manufacturing a halftone film type gray tone mask is as follows. Here, an LCD substrate pattern 100 as shown in FIG. 8 will be described as an example. The pattern 100 includes a light-shielding part pattern 101 including patterns 101a and 101b, a semi-transparent part pattern 103 between the light-shielding part patterns 101a and 101b, and a translucent part pattern 102 formed around these patterns. Has been.

  First, a mask blank in which a semi-transparent film and a light-shielding film are sequentially formed on a transparent substrate is prepared, and a resist film is formed on the mask blank. Next, a pattern is drawn and developed to form a resist pattern in a region corresponding to the light shielding part pattern 101 and the semi-transparent part pattern 103 of the pattern 100. Next, by etching with an appropriate method, the light shielding film in the region corresponding to the light transmitting portion pattern 102 where the resist pattern is not formed and the semi-light transmitting film thereunder are removed, and FIG. A pattern as shown is formed. That is, the light transmitting portion 202 is formed, and at the same time, the light shielding pattern 201 in the region corresponding to the light shielding portion and the semi-light transmitting portion of the pattern 100 is formed. After removing the remaining resist pattern, a resist film is formed again on the substrate, pattern drawing is performed, and development is performed, so that a resist pattern is formed in a region corresponding to the light shielding portion pattern 101 of the pattern 100 this time. Form. Next, only the light shielding film in the region of the semi-transparent portion where the resist pattern is not formed is removed by appropriate etching. As a result, a pattern corresponding to the pattern 100 is formed as shown in FIG. That is, a semi-transparent portion is formed by the semi-transparent film pattern 203, and simultaneously, light-shielding portion patterns 201a and 201b are formed.

  Further, in Patent Document 1 below, when only the light shielding film in the region of the semi-transparent portion is removed by etching in the second photolithography process, the film thickness of the lower semi-transparent film is prevented. It is disclosed that an etching stopper film is provided between a semi-transparent film and a light shielding film on a transparent substrate in a mask blank.

JP 2002-189281 A “Monthly FP Intelligence”, May 1999, p. 31-35

  However, according to such a conventional gray-tone mask manufacturing method, when the light shielding film and the semi-transparent film are made of, for example, the same material (for example, chromium and chromium compound), the light shielding film and the semi-transparent film are formed. Since the etching characteristics are approximate, it is difficult to determine the end point of etching when only the light-shielding film in the region of the semi-transparent portion is removed by etching in the second photolithography process described above. If the light-shielding film remains on the optical film and the etching is over, the semi-transparent film is reduced, and in any case, the desired semi-transparent property cannot be obtained. Therefore, it is necessary to select a combination of materials having different etching characteristics at least for the light shielding film and the semi-transparent film, and the range of material selection is limited. Further, even if a combination of materials having different etching characteristics is selected for the light-shielding film and the semi-transparent film as described above, it is not possible to completely prevent the above-described reduction of the semi-transparent film.

  In this case, as described in Patent Document 1, by providing an etching stopper film between the semi-transparent film and the light-shielding film on the transparent substrate in the mask blank to be used, the light-shielding film in the semi-transparent part region is provided. Even if etching is performed slightly overlying, it is possible to prevent the lower semi-transparent film from being reduced. However, the layer structure of the mask blank to be used is a three-layer structure of a semi-transparent film, an etching stopper film, and a light shielding film, and three stages of film formation are required, which imposes manufacturing costs. Further, since the entire film thickness is increased, the aspect ratio (ratio between the pattern dimension and the height) is large. As a result, there is a problem that the pattern shape and pattern accuracy of the light shielding portion are deteriorated and the etching time is increased. Further, when the remaining etching stopper film is removed after the light shielding film is etched, there is a problem that the underlying semi-transparent film is reduced. Even if the etching stopper film remains, any material that does not affect the transmissivity of the semi-transparent film can be left without being removed, but the material and thickness of the etching stopper film are limited. Is done.

In addition, according to the conventional gray-tone mask manufacturing method, pattern drawing is performed in each of the photolithography process for forming the first translucent part and the photolithography process for forming the second semi-transparent part. However, even if the alignment accuracy is increased, it is actually very difficult to completely eliminate the misalignment. For example, in the above TFT substrate, when the pattern of the semi-transparent portion corresponding to the channel portion of the TFT substrate is shifted due to misalignment, the area of the light shielding portion corresponding to the source / drain of the TFT substrate is designed. This causes a problem that the TFT characteristics change due to the difference in value, or a defect due to a short circuit between the source and drain occurs.
Therefore, the object of the present invention is to solve the conventional problems, and even without providing an etching stopper film, the light-shielding film and the semi-transparent film can be composed of film materials having the same or similar etching characteristics, It is another object of the present invention to provide a halftone film type gray-tone mask and a method of manufacturing the same, which can prevent the pattern shift of the semi-translucent portion.

In order to solve the above problems, the present invention has the following configuration.
(Configuration 1) A gray-tone mask having a light-shielding part, a light-transmitting part, and a semi-light-transmitting part, wherein the exposure amount of the photosensitive material layer in the object to be exposed using the gray-tone mask is determined by the light-shielding part. Gray tone used to obtain a mask layer on the object to be processed, which is made of a photosensitive material layer having a different film thickness by making the light transmitting part and the light transmitting part different from each other In the mask, the light shielding part is formed of a light shielding film provided on a transparent substrate and a semi-transparent film formed thereon, and the semi-transparent part exposes a region corresponding to the semi-transparent part. A gray-tone mask, which is formed of a semi-transparent film formed on a transparent substrate.
(Structure 2) The gray-tone mask according to Structure 1, wherein the light shielding film and the semi-transparent film are made of a film material having the same or similar etching characteristics.
(Structure 3) The gray-tone mask has a portion where the light shielding portion and the semi-transparent portion are adjacent to each other, and the film thickness of the semi-transparent film forming the semi-transparent portion is the same as the light shielding portion in the semi-transparent portion. 3. The gray-tone mask according to Configuration 1 or 2, wherein the gray-tone mask is thicker than other semi-transparent portions in the vicinity of the boundary.
(Configuration 4) The processing of the object to be processed is an etching process, and the gray-tone mask has a portion where a light shielding portion and a semi-translucent portion are adjacent to each other, and in the vicinity of the boundary between the semi-transparent portion and the light shielding portion 4. The gray-tone mask according to any one of configurations 1 to 3, wherein the pattern shape of the object to be processed corresponding to 1 is a tapered shape.

(Structure 5) A gray-tone mask manufacturing method having a light-shielding part, a light-transmitting part, and a semi-light-transmitting part, comprising: preparing a mask blank having a light-shielding film formed on a transparent substrate; A resist pattern is formed in a region corresponding to the light-shielding portion and the light-transmitting portion, and the exposed light-shielding film is etched using the resist pattern as a mask to expose the transparent substrate in the region corresponding to the semi-light-transmitting portion. A step of removing the resist pattern remaining in the step and forming a semi-translucent film by forming a semi-transparent film on the entire surface of the obtained substrate; and the light-shielding unit and the semi-translucent unit Forming a light-transmitting part and a light-shielding part by forming a resist pattern in a region corresponding to the part and etching the exposed semi-light-transmitting film and light-shielding film using the resist pattern as a mask. Method for manufacturing a gray-tone mask characterized by having a and.
(Structure 6) The gray-tone mask according to Structure 5, wherein the light-shielding film and the semi-transparent film are formed of film materials having the same or similar etching characteristics and are treated with the same etching solution or the same etching gas. Manufacturing method.
(Structure 7) The photosensitive material layer in a to-be-processed object is exposed using the gray tone mask which has a light-shielding part, a translucent part, and a semi-transparent part, and the exposure amount to the photosensitive material layer in this to-be-processed object is set. A step of obtaining a mask layer made of a photosensitive material layer having a different film thickness by making the light-shielding part, the light-transmitting part, and the semi-light-transmitting part different, and the photosensitive material having the different film thickness A process for forming a pattern on a target object by appropriately using a mask layer composed of layers to form a pattern on the target object, wherein the light-shielding portion is transparent A light-shielding film provided on a substrate and a semi-transparent film formed thereon, and the semi-transparent part is formed on a transparent substrate exposing a region corresponding to the semi-transparent part. To be treated, characterized by being formed from a semi-translucent film The method of production.
(Structure 8) The process of the to-be-processed object is an etching process, and the gray-tone mask has a part where a light shielding part and a semi-transparent part are adjacent to each other, and in the vicinity of the boundary between the semi-transparent part and the light shielding part 8. The method for manufacturing an object to be processed according to Configuration 7, wherein the pattern shape of the object to be processed is a tapered shape.

According to Configuration 1, the gray-tone mask of the present invention has a light shielding part, a light transmitting part, and a semi-light transmitting part, and the light shielding part is formed on the light shielding film provided on the transparent substrate and the light shielding film. The semi-transparent part is formed of a semi-transparent film formed on a transparent substrate exposing a region corresponding to the semi-transparent part.
As described above, the semi-transparent portion is formed by directly forming the semi-transparent film on the transparent substrate in which the region corresponding to the semi-transparent portion is exposed. In this case, it is not necessary to remove only the upper light-shielding film by etching and expose the lower semi-transparent film. Therefore, both the light-shielding film and the semi-transparent film are formed of film materials having the same or similar etching characteristics. It is also possible to expand the range of choice of film material. Therefore, in the present invention, the etching stopper film provided between the conventional light-shielding film and the semi-transparent film is unnecessary, the entire film thickness can be reduced, and the aspect ratio can be reduced.

In the gray tone mask of Configuration 1, the exposure amount to the photosensitive material layer in the object to be exposed using the gray tone mask is different between the light shielding portion, the light transmitting portion, and the semi-light transmitting portion. Thus, the gray tone mask is used to obtain a mask layer on the target object for processing the target object made of the photosensitive material layer having a different thickness.
Here, the object to be processed includes a substrate serving as a material of a display device, a semiconductor device, and the like, and the process of the object to be processed includes processes such as an etching process and an ion implantation process.

Further, as in Configuration 2, the light-shielding film and the semi-transparent film are made of film materials having the same or similar etching characteristics, for example, the light-shielding film and the semi-transparent film are made of the same material or the same main component. The film forming process can be simplified.
Further, in Configuration 3, the gray-tone mask has a portion where the light shielding portion and the semi-transparent portion are adjacent to each other, and the thickness of the semi-transparent film forming the semi-transparent portion is the light shielding portion in the semi-transparent portion. In the vicinity of the boundary, the thicker than the other semi-translucent portion. In the gray-tone mask of the present invention, the semi-transparent film is covered from the light-shielding film to the transparent substrate in the vicinity of the boundary between the semi-transparent part and the light-shielding part. In the vicinity of the boundary between the light-transmitting portion and the light-shielding portion, it is thicker than the other semi-transparent portions. The configuration 3 is suitable when the pattern shape of the object to be processed as in the configuration 4 is a tapered shape.

  According to Configuration 4, the processing of the object to be processed is an etching process, and the gray-tone mask has a portion where a light-shielding portion and a semi-transparent portion are adjacent to each other, and the light-shielding portion in the semi-transparent portion The pattern shape of the object corresponding to the vicinity of the boundary is a tapered shape. In the gray-tone mask of the present invention, the semi-transparent film is covered from the light-shielding film to the transparent substrate in the vicinity of the boundary between the semi-transparent part and the light-shielding part. When the transmittance of exposure light in the vicinity of the boundary becomes an intermediate transmittance between the semi-transparent portion and the light shielding portion by becoming thicker than the other semi-transparent portions in the vicinity of the boundary of the light transmitting portion with the light shielding portion. The photosensitive material layer on the object to be processed corresponding to the vicinity of the boundary with the light shielding part in the semi-translucent part can be formed into a taper-shaped pattern. The shape of the material layer is transferred to form a tapered pattern.

  Further, according to Configuration 5, the gray-tone mask manufacturing method of the present invention uses a mask blank in which a light-shielding film is formed on a transparent substrate, and corresponds to the light-shielding part and the light-transmitting part on the mask blank. Forming a resist pattern in the region, and etching the exposed light-shielding film using the resist pattern as a mask to expose the transparent substrate in the region corresponding to the semi-translucent portion; and the resist pattern remaining in the step And forming a semi-translucent film on the entire surface of the obtained substrate, thereby forming a semi-translucent portion, and forming a resist pattern in a region corresponding to the light-shielding portion and the semi-transparent portion And using the resist pattern as a mask to etch the exposed semi-transparent film and light shielding film, thereby forming a light transmitting part and a light shielding part.

Accordingly, although the photolithographic process is performed twice, only the portion that becomes the semi-transparent portion is patterned in the first photolithographic step, and at this time, the region including the semi-transparent portion and the other light-shielding portion is formed. It is formed. As a result, the size of the semi-translucent portion, the positional relationship with the light-shielding portion, and the like are determined by the first patterning, so that the positional accuracy of the semi-translucent portion can be ensured with the accuracy of one drawing. Therefore, in particular, it is possible to prevent the pattern shift of the semi-translucent portion, and it is possible to reduce the influence due to the alignment shift at the time of drawing in the second photolithography process as in the prior art. As described above, according to the method of the configuration 4, for example, it is possible to prevent the pattern shift of the channel portion which is particularly important in the TFT, and to ensure the quality as a mask.

Further, according to the method of Configuration 5, the semi-transparent portion is formed by exposing the transparent substrate in the region corresponding to the semi-transparent portion in the mask blank and forming the semi-transparent film by the first patterning. Therefore, in the region corresponding to the conventional semi-transparent part, there is no step of forming the semi-transparent part by removing only the upper light-shielding film by etching and exposing the lower semi-transparent film. Therefore, the semi-transparent portion can be formed even if film materials having the same or similar etching characteristics are used as the light shielding film and the semi-transparent film. Further, in the present invention, the etching stopper film provided between the conventional light-shielding film and the semi-transparent film is unnecessary, so that the film formation and etching process of the etching stopper film is not necessary, and the mask blank having a simple layer structure is used. Can be used, which is advantageous in terms of manufacturing process and manufacturing cost.

In addition, in addition to simplifying the film forming process by forming the light shielding film and the semi-transparent film with a film material having the same or similar etching characteristics as in configuration 6, in the method of configuration 4, Using the resist pattern formed in the region corresponding to the light-shielding part and the semi-transparent part as a mask, the exposed semi-transparent film and the light-shielding film can be successively processed with the same etching solution or the same etching gas. As a result, the etching process can be simplified.
Moreover, according to the structure 7, the to-be-processed object, for example, the board | substrate used as a raw material of a display device, a semiconductor device, etc. are manufactured in the manufacturing process which reduced the number of masks to be used using the gray tone mask of this invention. I can do it.
Further, according to Configuration 8, by using the gray tone mask of the present invention, the pattern shape of the object corresponding to the vicinity of the boundary with the light shielding portion in the semi-transparent portion of the gray tone mask is tapered. A to-be-processed object can be manufactured.

According to the present invention, even if an etching stopper film is not provided, a semi-transparent portion can be formed when the light shielding film and the semi-transparent film are made of film materials having the same or similar etching characteristics. A gray-tone mask that can prevent the pattern shift of the semi-translucent portion is obtained.
Further, by using the gray tone mask of the present invention, the pattern shape of the object to be processed corresponding to the vicinity of the boundary with the light shielding portion in the semi-transparent portion of the gray tone mask can be formed to have a tapered shape. .

Hereinafter, the present invention will be described in detail by embodiments.
FIG. 1 shows one embodiment of a method for manufacturing a gray-tone mask according to the present invention, and is a schematic cross-sectional view sequentially showing the manufacturing process. FIG. 2 is a diagram showing a continuation of the manufacturing process of FIG.
As shown in FIG. 1A, a mask blank 20 used in the present embodiment has a light shielding film 22 formed on a transparent substrate 21 such as quartz.
As shown in FIG. 2 (i), the gray-tone mask 30 of the present embodiment obtained using the mask blanks 20 includes a light-shielding portion, a light-shielding film 22b provided on the transparent substrate 21, and a top thereof. The semi-transparent film is formed of the semi-transparent film 24a, and the semi-transparent part is formed of the semi-transparent film 24a formed on the transparent substrate 21 exposing the region corresponding to the semi-translucent part.

Here, the material of the light shielding film 22 (22b) is preferably a thin film that provides high light shielding properties, and examples thereof include Cr, Si, W, and Al. Further, the material of the semi-transparent film 24a is preferably a thin film that can obtain a semi-transmissivity of about 50% when the transmissivity of the translucent part is 100%. Oxide, nitride, oxynitride, fluoride, etc.), MoSi, Si, W, Al and the like. Si, W, Al, and the like are materials that can provide high light shielding properties or semi-transparency depending on the film thickness. Further, since the light-shielding portion of the gray-tone mask to be formed is a laminated film of the light-shielding film 22b and the semi-transparent film 24a formed thereon, the semi-transparent film can be used even if the light-shielding film alone does not have sufficient light shielding properties. It is sufficient that sufficient light shielding properties can be obtained when combined with the above. Here, the transmittance is the transmittance with respect to the wavelength of the exposure light of, for example, a large LCD exposure machine using a gray tone mask. Further, the transmissivity of the semi-transparent film is not necessarily limited to about 50%. How much the translucency of the semi-translucent portion is set is a design problem.

  Further, the material combination of the light shielding film 22 (22b) and the semi-transparent film 24a is not particularly limited in the present invention. The etching characteristics of the films may be the same or similar, or the etching characteristics of the films may be different. According to the conventional manufacturing method, the semi-transparent portion is formed by removing the upper light-shielding film and exposing the lower semi-transparent film. In the etching environment, the other film needs to have a combination that has resistance. For example, when the light shielding film is made of Cr and the semi-transparent film is made of MoSi, the Cr light shielding film is made of the underlying MoSi semi-transparent film. It was indispensable to remove only the Cr light-shielding film by etching without damaging the MoSi semi-transparent film. According to the present invention, the semi-transparent portion is formed by directly forming the semi-transparent film on the transparent substrate in which the region corresponding to the semi-transparent portion is exposed. There is no particular limitation, and a combination of materials having the same or similar etching characteristics of the light shielding film and the semi-transparent film can be selected. For example, a combination of materials having the same material and materials having the same main component (for example, Cr and Cr compound) can be arbitrarily selected.

  In the present invention, if the light-shielding film and the semi-transparent film are formed of film materials having the same or similar etching characteristics, the film forming process becomes simple (for example, it is not necessary to replace the film forming target). In addition, when the light-shielding film and the semi-light-transmitting film on the transparent substrate are etched to form the light-transmitting portion, it can be processed simultaneously or continuously using the same etching liquid or the same etching gas. There are advantages. In the conventional manufacturing method, when the light shielding film and the semi-transparent film are made of a film material having the same or similar etching characteristics, it is necessary to provide an etching stopper film. In the present invention, such an etching stopper is used. Even if a film is not provided, a combination of film materials having the same or similar etching characteristics can be selected. As described above, in the present invention, there is no restriction from the viewpoint of the etching characteristics regarding the combination of the light shielding film and the semi-transparent film, but it is no problem to select a combination of materials having different etching characteristics in the present invention. Of course not.

In particular, since the light shielding portion is composed of the light shielding film 22b on the substrate 21 and the semi-transparent film 24a formed thereon, it is desirable that the mutual adhesion is good.
The mask blank 20 can be obtained by forming the light shielding film 22 on the transparent substrate 21. The film forming method is suitable for film types such as vapor deposition, sputtering, and CVD (chemical vapor deposition). The method may be selected as appropriate. Further, the film thickness is not particularly limited, but the film thickness may be optimized so as to obtain a good light shielding property.

Next, a manufacturing process of a gray tone mask using this mask blank 20 will be described.
First, for example, a positive resist for electron beam is applied on the mask blanks 20 and baked to form a resist film 23 (see FIG. 1A).
Next, drawing is performed using an electron beam drawing machine or a laser drawing machine. For example, in the case of the pattern 100 shown in FIG. 7 described above, the drawing data is pattern data corresponding to the translucent portion pattern 103 of the pattern 100. After drawing, this is developed, and the resist is removed on the mask blank 20 in the region where the semi-transparent portion is formed (region A shown in FIG. 1), and the region where the light shielding portion is formed (shown in FIG. 1). The resist pattern 23a in which the resist remains is formed in the region B and the region where the light-transmitting portion is formed (the region C shown in FIG. 1) (see FIG. 1B).

Next, using the formed resist pattern 23a as a mask, the light shielding film 22 is dry-etched to form a light shielding film pattern 22a corresponding to the light shielding portion (B region) and the light transmitting portion (C region) (FIG. 1 ( c)). When the light shielding film 22 is made of a Cr-based material, dry etching using chlorine gas can be used. In this case, even if the light shielding film 22 is slightly overetched, the transmittance of the underlying transparent substrate 21 is not affected. In the region (A region) corresponding to the semi-translucent portion, the underlying transparent substrate 21 is exposed by the etching of the light shielding film 22.
The remaining resist pattern 23a is removed using ashing with oxygen or concentrated sulfuric acid (see FIG. 1D).

By the first photolithography process described above, a region corresponding to the semi-translucent portion (A region) is formed, and at this time, the light-shielding portion (B region) and the translucent portion (C region) are not drawn, The pattern dimension of the semi-translucent portion and the positional relationship with the light shielding portion are obtained at a time by one drawing. Therefore, the position accuracy of the pattern of the semi-translucent portion can be ensured by one drawing. For example, it is possible to form a channel portion that is important for TFT characteristics without causing a pattern shift.

Next, the semi-transparent film 24 is formed on the entire surface of the substrate having the light shielding film pattern 22a on the transparent substrate 21 obtained as described above (see FIG. 1E). Thereby, in the region corresponding to the semi-transparent portion, the semi-transparent film 24 is directly formed on the exposed transparent substrate 21 to form the semi-transparent portion (A region).
The combination of the material of the semi-transparent film 24 and the material of the light shielding film is as described above, and the description thereof is omitted here. As a method for forming the semi-transparent film, a method suitable for the film type, such as a vapor deposition method, a sputtering method, a CVD (chemical vapor deposition) method, or the like may be selected as appropriate as in the case of the light shielding film described above. The thickness of the semi-translucent film is not particularly limited, but it may be formed with an optimized film thickness so as to obtain a desired semi-translucency.

Next, the positive resist is again applied to the entire surface and baked to form a resist film 23 (see FIG. 2F).
Then, the second drawing is performed. The drawing data at this time is pattern data including a semi-translucent portion (A region) and a light shielding portion (B region). After drawing, this is developed to form a resist pattern 23b in which the resist is removed in the light transmitting portion (C region) and the resist remains in the light shielding portion (B region) and the semi-light transmitting portion (A region) ( (Refer FIG.2 (g)).

Next, using the formed resist pattern 23b as a mask, the semi-transparent film 24 and the light-shielding film 22a in the C region to be a light transmitting part are removed by dry etching. As a result, the light shielding portion is defined as a light transmitting portion, and a light shielding portion (B region) and a light transmitting portion (C region) are formed (see FIG. 2H). Here, when the etching characteristics of the semi-transparent film and the light-shielding film are different, it is necessary to etch the semi-transparent film and the light-shielding film under different conditions, but both films such as Cr and Cr compound are required. When the etching characteristics of the materials are the same or similar, they can be processed at once or continuously with the same etching gas or the same etching liquid (wet etching). For example, when the light shielding film 22a is made of Cr and the semi-transparent film 24 is made of a Cr compound, dry etching using chlorine gas can be used.
The remaining resist pattern 23b is removed using oxygen ashing or the like (see FIG. 2 (i)).

As described above, the gray tone mask 30 of the present embodiment is completed.
In this embodiment, the case where a positive resist is used is exemplified, but a negative resist may be used. In this case, the process can be carried out in exactly the same manner as described above only by reversing the drawing data.

Next, a method for manufacturing an object to be processed such as a liquid crystal display device using the gray tone mask of the above embodiment will be described.
FIG. 3 shows an example of a manufacturing process of an object to be processed such as a liquid crystal display device using the gray tone mask 30 of the above embodiment.
For example, a substrate 40 for manufacturing an object to be processed shown in FIG. 6A has a base metal 41 on which a first metal film 42 and a second metal film 43 are formed. A resist film 44 is formed (see FIG. 3A). Since the configuration of the substrate 40 varies depending on the object to be manufactured, the configuration illustrated here is merely an example. Depending on the type of the object to be processed, an insulating film or a semiconductor film may be provided in addition to the metal film, and the number of layers is not limited to those exemplified here.

Next, by using the gray tone mask 30 of the above-described embodiment, the positive type photoresist film 44 of the substrate for manufacturing an object to be processed 40 is exposed and developed, whereby the light shielding portion and the semi-translucent portion of the gray tone mask 30 are developed. The first resist pattern 44a is formed so as to cover a region corresponding to the portion and to make a region corresponding to the semi-translucent portion thinner than a region corresponding to the light shielding portion (see FIG. 3B). In the gray tone mask 30 of the above embodiment, the semi-transparent film 24a is formed so as to cover from the light shielding film 22b to the transparent substrate 21 in the vicinity of the boundary between the semi-transparent part and the light shielding part. As a result, the film thickness of the semi-transparent film 24a is thicker in the vicinity of the boundary between the semi-transparent portion and the light-shielding portion than in the other semi-transparent portions. With the intermediate transmittance between the light transmitting portion and the light shielding portion, the photoresist film on the substrate 40 corresponding to the vicinity of the boundary can be formed into a tapered pattern.

Next, using the first resist pattern 44a as a mask, the second metal film 43 and the first metal film 42 in the region corresponding to the light transmitting portion are etched (see FIG. 3C). Next, the thin resist film in the region corresponding to the semi-translucent portion is removed by ashing with oxygen to form a second resist pattern 44b (see FIG. 3D). At this time, the tapered shape of the photoresist film corresponding to the vicinity of the boundary with the light shielding portion in the semi-transparent portion is maintained.
Thereafter, using the second resist pattern 44b as a mask, the second metal film 43 in the region corresponding to the semi-translucent portion is etched to form a second metal film pattern 43a (see FIG. 3E). Then, the remaining second resist pattern 44b is removed (see FIG. 3F). The second metal film 43 is formed into a tapered pattern by the etching described above in the region corresponding to the vicinity of the boundary between the semi-translucent portion and the light shielding portion.

As described above, a desired object to be processed is obtained using the gray tone mask 30. By using the gray-tone mask 30, the photoresist film on the substrate 40 corresponding to the vicinity of the boundary between the semi-transparent portion and the light shielding portion can be formed into a tapered pattern, and as a result, corresponding to the vicinity of the boundary. The pattern of the object to be processed can also be formed into a tapered pattern by transferring the shape of the photoresist film. Therefore, the gray tone mask of the present invention is particularly suitable when the boundary portion of the pattern needs to be formed in a taper shape, for example, because the film tends to crack due to the film material of the object to be processed and the film stress. Is preferred.

Further, in order to form a tapered pattern on the object to be processed, the object to be processed may be manufactured using a gray tone mask as shown in FIG.
In other words, as shown in the upper side of FIG. 4A, the gray-tone mask of the present embodiment has the semi-transparent film 24b formed only in the vicinity of the boundary with the light-shielding portion in the semi-transparent portion. Such a gray-tone mask can be obtained, for example, by not forming a resist film in the semi-transparent portion other than the vicinity of the boundary with the light-shielding portion in the semi-transparent portion in the step of FIG.
By using this gray-tone mask, for example, by exposing and developing the positive photoresist film 44 of the substrate for manufacturing an object in which the metal film 42 and the positive photoresist film 44 are formed on the base material 41, and developing, A resist pattern 44c is formed in which the photoresist film in a region corresponding to the vicinity of the boundary with the light shielding portion in the semi-transparent portion of the gray tone mask is tapered (see FIG. 4B).
Next, using the resist pattern 44c as a mask, the metal film 42 is etched to form a metal film pattern 42a (see FIG. 4C), and the remaining resist pattern 44c is peeled off (see FIG. 4D). The metal film 42 is formed in a tapered pattern in a region corresponding to the vicinity of the boundary between the semi-translucent portion and the light shielding portion.

As described above, according to the present invention, there is no restriction on the combination of the film material of the light shielding film and the semi-transparent film, and the film material having the same or similar etching characteristics can be obtained without providing the conventional etching stopper film. Even when the light-shielding film and the semi-transparent film are formed in combination, a gray-tone mask of a halftone film type can be manufactured. Therefore, when the semi-transparent portion is formed, various conventional methods such as reduction of the semi-transparent film due to etching of the light shielding film, increase in the number of layers due to the provision of the etching stopper film, and problems associated with removal of the etching stopper film, etc. The problem can be solved. The gray tone mask of the present invention is particularly suitable when a tapered pattern is formed on the object to be processed.

It is a schematic sectional drawing which shows the manufacturing process of the gray tone mask of this invention. It is a schematic sectional drawing which shows the manufacturing process (continuation of the manufacturing process of FIG. 1) of the gray tone mask of this invention. It is a schematic sectional drawing which shows the process of manufacturing to-be-processed objects, such as LCD, using one Embodiment of the gray tone mask of this invention. It is a schematic sectional drawing which shows the process of manufacturing to-be-processed objects, such as LCD, using other embodiment of the gray tone mask of this invention. It is a schematic sectional drawing which shows the manufacturing process of the TFT substrate using a gray tone mask. It is a schematic sectional drawing which shows the manufacturing process (continuation of the manufacturing process of FIG. 4) of the TFT substrate using a gray tone mask. It is a figure which shows an example of the gray tone mask of a fine pattern type. It is a figure which shows an example of a gray tone mask pattern. It is a mask pattern top view for demonstrating the manufacturing method of the conventional gray tone mask.

Explanation of symbols

21 transparent substrate 22 light shielding film 23 resist film 24 semitransparent film 20 mask blanks 30 gray tone mask 100 mask pattern 101 light shielding part pattern 102 translucent part pattern 103 semitransparent part pattern

Claims (7)

Shielding portion, a gray-tone mask having a light-transmitting portion and the semi-light-transmitting portion,
By making the exposure amount to the photosensitive material layer in the object to be exposed using the gray tone mask different between the light shielding portion, the light transmitting portion, and the semi-light transmitting portion, the photosensitive material layers having different film thicknesses In a manufacturing method of a gray tone mask used for obtaining a mask layer on a target object for processing the target object consisting of:
Preparing a mask blank having a light shielding film formed on a transparent substrate;
A resist pattern of a region corresponding to the light shielding portion and the light transmitting portion is formed on the mask blank, and the exposed light shielding film is etched using the resist pattern as a mask, so that the region corresponding to the semi-light transmitting portion is etched. A first photolithography process for exposing the transparent substrate;
Removing the resist pattern remaining in the step, and forming a semi-transparent portion by forming a semi-transparent film on the entire surface of the obtained substrate; and
A resist pattern is formed in a region corresponding to the light-shielding portion and the semi-light-transmitting portion, and the exposed semi-light-transmitting film and the light-shielding film are etched using the resist pattern as a mask, thereby forming the light-transmitting portion and the light-shielding portion. A second photolithography step;
I have a,
In the first photolithography process, a pattern dimension of the semi-transparent portion is formed by defining a region corresponding to the semi-transparent portion . 2. The gray tone mask according to claim 1, wherein a resist pattern in which a region corresponding to the semi-transparent portion is thinner than a region corresponding to the light shielding portion is formed on the object to be processed. The manufacturing method of the gray-tone mask of description. 2. The gray tone mask manufacturing method according to claim 1, wherein the gray tone mask is a liquid crystal display manufacturing gray tone mask. 4. The method of manufacturing a gray tone mask according to claim 3, wherein the semi-translucent portion corresponds to a channel portion of the TFT substrate, and the light shielding portion corresponds to a source and a drain of the TFT substrate. The light shielding film and HanToruHikarimaku, the etching characteristic is formed with the same or close to that film material, the same etching solution or claims 1 to 4, characterized in that the treatment with the same etching gas as described in any A method for manufacturing a gray-tone mask. Using the gray-tone mask obtained by the manufacturing method according to any one of claims 1 to 5, the photosensitive material layer in the object to be processed is exposed, and the exposure amount to the photosensitive material layer in the object to be processed is determined. A step of obtaining a mask layer made of a photosensitive material layer having a different film thickness by making the light-shielding part, the light-transmitting part, and the semi-light-transmitting part different, and the photosensitive material having the different film thickness And a process of forming a pattern on the object to be processed by appropriately using a mask layer composed of layers to form a pattern on the object to be processed. The processing of the object to be processed is an etching process, and the gray-tone mask has a portion where a light shielding part and a semi-transparent part are adjacent to each other, and the object to be processed corresponding to the vicinity of the boundary of the semi-transparent part with the light shielding part. The method for manufacturing an object to be processed according to claim 6 , wherein the pattern shape of the object to be processed is a tapered shape.

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