JP4587837B2 - Gray tone mask manufacturing method and gray tone mask - Google Patents

Description

 The present invention relates to a gray-tone mask used for manufacturing a liquid crystal display (LCD) and the like and a method for manufacturing the same.

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 because of its advantage of being thin and low in power consumption compared to a CRT (cathode ray tube). Is going on. 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. 4A and FIG. 4B (FIG. 4B is a continuation of the manufacturing process of FIG. 4A) 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. 4). (A) (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 (FIGS. 4A and 2). Next, using the first resist pattern 7a as a mask, the source / drain metal film 6 and the second and first semiconductor films 5 and 4 are etched (FIGS. 4A and 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 (FIGS. 4B and 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 (FIGS. 4B and 2). ), The last remaining second resist pattern 7b is peeled off (FIGS. 4B and 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. 5, 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. 5, the space width of the transmission part 13b in the semi-transmission part 13 is set to less than 3 μm, and the line width of the light shielding pattern 13a 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. 6 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 in which the resist pattern is not formed and the semi-light transmitting film in the lower layer 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.

  However, according to such a conventional gray-tone mask manufacturing method, when the material having the same main component (for example, chromium and chromium compound) is used for the light shielding film and the semi-transparent film, the light shielding film and the semi-transparent film are used. Therefore, 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 light-transmitting film and the etching is over, the semi-transparent film is reduced, and in any case, there is a problem that a desired semi-light-transmitting 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 the following Patent Document 1, a mask is used to prevent the lower semi-transparent film from being reduced when only the light-shielding film in the semi-transparent part region is removed by etching in the second photolithography process. 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 blanks. 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 etching of the light-shielding film in the semi-transparent part region is slightly over-etched. Even if it goes slightly, it is possible to prevent the lower semi-translucent 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.

  As a gray-tone mask capable of solving such problems, a light-shielding portion is formed of a light-shielding film provided on a transparent substrate and a semi-transparent film formed on the light-shielding film. Has previously proposed a gray-tone mask formed by a semi-transparent film formed on a transparent substrate exposing a region corresponding to the semi-transparent part (Japanese Patent Application No. 2004-2004). 65115).

As a manufacturing method of this type of gray tone mask, for example, it can be manufactured by the following method.
First, a mask blank having a light shielding film formed on a transparent substrate is prepared.
Next, a resist pattern of a region corresponding to the light shielding portion is formed on the mask blank, and a light shielding film pattern is formed by etching the exposed light shielding film using the resist pattern as a mask, and the semi-transparent portion And the transparent substrate of the area | region corresponding to a translucent part is exposed.
Next, the resist pattern remaining in the above step is removed, and a semi-transparent film is formed on the entire surface of the obtained substrate.
Further, a resist pattern is formed in a region corresponding to the light shielding portion and the semi-transparent portion, and the exposed semi-transparent film is etched using the resist pattern as a mask, thereby forming the translucent portion.
It can also be produced by the following method.
That is, a resist pattern of a region corresponding to the light-shielding part and the light-transmitting part is formed on the mask blank, and the exposed light-shielding film is etched using the resist pattern as a mask, thereby corresponding to the semi-light-transmitting part. Expose the transparent substrate in the area.
Next, the resist pattern remaining in the above step is removed, and a semi-transparent film is formed on the entire surface of the obtained substrate.
Further, a resist pattern is formed in a region corresponding to the light-shielding part and the semi-light-transmitting part, and the exposed semi-light-transmitting film and the light-shielding film are etched using the resist pattern as a mask. Form.

  According to the gray tone mask, the semi-transparent part is formed by directly forming the semi-transparent film on the transparent substrate exposing the region corresponding to the semi-transparent part. When forming the portion, it is not necessary to remove only the upper light-shielding film by etching and expose the lower semi-light-transmitting film, so that both the light-shielding film and the semi-light-transmitting film have the same or approximate etching characteristics. It can also be formed of a film material, and the range of selection of the film material is expanded. Therefore, 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.

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

  By the way, in the manufacturing method of the gray-tone mask formed of the semi-transparent film formed on the transparent substrate in which the region corresponding to the semi-transparent part is exposed, the resist pattern is formed. Since the pattern drawing for forming needs to be performed twice, a mark for adjusting the position of the pattern drawing of the second time is formed by etching the light shielding film in the same manner as the normal pattern at the time of the first pattern formation. It is conceivable to perform the second drawing by performing alignment based on the above.

8A and 8B, the light shielding portion is formed on the mask blank (FIG. 8A and FIG. 8A) in which the light shielding film 22 is formed on the transparent substrate 21. A resist pattern 24a is formed in a region corresponding to (2) in FIG. 2, and the exposed light shielding film 22 is etched by using the resist pattern 24a as a mask to form a light shielding film pattern 22a. The transparent substrate 21 in the region corresponding to the light transmitting portion and the light transmitting portion is exposed ((3) in the figure).
Next, the resist pattern 24a remaining in the above process is removed (FIG. 4 (4)), and a semi-transmissive film 23 is formed on the entire surface of the obtained substrate (FIGS. 8B and 5). The device pattern portion includes a semi-transparent portion (A (d) region shown), a light-shielding portion (B (d) region shown), and a transparent portion (C (d) region shown). The alignment mark pattern portion has a light shielding portion (B (m) region shown) and a light transmitting portion (C (m) region shown).

Next, a resist film 24 is formed on the entire surface of the substrate (FIGS. 8B and 6), and drawing and development for exposing a region (C (d) region) corresponding to the light transmitting portion of the device pattern portion. To form a resist pattern 24b ((7) in the figure), and using the resist pattern 24b as a mask, the exposed semi-transparent film 23 of the device pattern translucent part is etched to form a translucent part. ((8) in the figure).
By removing the remaining resist pattern 24b, a gray-tone mask 20A on which a device pattern and a mark pattern are formed is obtained ((9) in the figure). 9A is a plan view of the gray-tone mask 20A, FIG. 9B is a cross-sectional view of the mark pattern (M) formed in the non-device pattern area of the mask, and FIG. 9C is a device pattern (D). FIG. The mark pattern (M) in FIG. 9 and the device pattern (D) shown in the enlarged view are examples thereof. 8A and 8B schematically show the device pattern and the mark pattern, and do not exactly match the device pattern and the mark pattern shown in FIG.

  By the way, a mark pattern having a light shielding portion (B (m) region) and a light transmitting portion (C (m) region) when the first pattern (light shielding film pattern 22a) is formed (FIGS. 8A and 4). However, the semi-transparent film is also formed on the translucent part of the mark pattern by forming the semi-transparent film 23 in the next step. If the mark is detected using transmitted light or reflected light based on the mark and alignment is performed for the second drawing (drawing for forming the resist pattern 24b), the mark is detected when the mark is detected. Since the semi-transparent film 23a and the resist film 24 are formed in the light-transmitting portion of the pattern, the contrast between the light-transmitting portion and the light-shielding portion of the mark pattern is low, making it difficult to recognize the mark and difficult to detect. There was a point. That is, when a mark is detected by transmitted light, the transmittance of the light transmitting portion of the mark pattern is attenuated by the semi-transmissive film 23a and the resist film 24, and the transmittance difference from the light shielding portion of the mark pattern is reduced. Becomes lower. In addition, when a mark is detected with reflected light, the translucent portion and the light-shielding portion of the mark pattern have the same reflectivity, resulting in a low contrast.

  Furthermore, in a gray tone mask, it is necessary to form various marks such as alignment marks for use in alignment with a transfer substrate when using the mask in a non-device pattern area of the mask, as in a normal photomask. In the mask on which the light shielding film pattern is formed, a mark is formed by etching the light shielding film in the non-device pattern region. However, in the gray-tone mask, when the mark for alignment of the pattern drawing described above is also used or another mark is formed in the same manner, the translucency of the mark pattern formed on the light-shielding film in the non-device pattern area of the mask Since the portion is covered with the semi-transparent film and forms a semi-transparent portion (A region) (see FIGS. 8B and 9), the mark is detected using transmitted light and reflected light. However, there is a problem that detection is difficult because of low contrast.

  The present invention has been made in view of the above problems, the light shielding portion is formed of a light shielding film provided on a transparent substrate and a semi-transparent film formed thereon, and the semi-transparent portion is In a gray-tone mask formed from a semi-transparent film formed on a transparent substrate exposing a region corresponding to the semi-transparent part, the contrast of the mark formed in the non-device pattern region is high and detected. An object of the present invention is to provide a gray-tone mask and a method for manufacturing the same.

In order to solve the above problems, the present invention has the following configuration.
(Configuration 1) In a method for manufacturing a gray-tone mask in which a device pattern having a light-shielding part, a light-transmitting part, and a semi-light-transmitting part and a mark pattern used for alignment are formed, at least a light-shielding film is formed on a transparent substrate A step of preparing the mask blank, a first drawing pattern is drawn on a first resist film for forming a light shielding portion pattern, and developed to form a first resist pattern. A light shielding part pattern forming step including a step of etching the light shielding film using a pattern as a mask; a step of forming a semi-transparent film on the transparent substrate on which the light shielding part pattern is formed; and forming a semi-translucent part pattern For this purpose, a second drawing pattern is drawn on the second resist film formed on the semi-transparent film and developed to form a second resist pattern, and the second resist pattern is formed. A semi-transparent part pattern forming step including a step of etching the semi-transparent film using a mask as a mask. In the light shielding part pattern forming step, the light shielding part and the translucent part are formed together with the light shielding part pattern formation. Forming a desired mark pattern, and before drawing the second drawing pattern in the semi-translucent portion pattern forming step, having a step of preventing a semi-transparent film from being present in the translucent portion of the mark pattern This is a method for producing a gray-tone mask.

(Structure 2) The step of preventing the semi-transparent film from being present in the translucent part of the mark pattern is a step of forming the semi-transparent film, wherein the semi-transparent film is at least the translucent part of the mark pattern. The method of manufacturing a gray-tone mask according to Configuration 1, wherein the film is formed by removing the film.
(Structure 3) The step of preventing the semi-transparent film from being present in the translucent part of the mark pattern removes at least the semi-transparent film in the translucent part of the mark pattern after the semi-transparent film is formed. It is a manufacturing method of the gray tone mask of the structure 1 characterized by being a process.
(Configuration 4) Before drawing the second drawing pattern in the semi-translucent portion pattern forming step, the second resist film is further not present in the translucent portion of the mark pattern. The resist film is applied excluding at least the light transmitting part of the mark pattern, or after the second resist film is formed, at least the second resist film in the light transmitting part of the mark pattern is removed. 4. A method for producing a gray-tone mask according to any one of 3 above.

(Configuration 5) In a method for manufacturing a gray-tone mask in which a device pattern having a light-shielding part, a light-transmitting part, and a semi-light-transmitting part and a mark pattern used for alignment are formed, at least a light-shielding film is formed on a transparent substrate A step of preparing the mask blank, a first drawing pattern is drawn on a first resist film for forming a light shielding portion pattern, and developed to form a first resist pattern. A light shielding part pattern forming step including a step of etching the light shielding film using a pattern as a mask; a step of forming a semi-transparent film on the transparent substrate on which the light shielding part pattern is formed; and forming a semi-translucent part pattern For this purpose, a second drawing pattern is drawn on the second resist film formed on the semi-transparent film and developed to form a second resist pattern, and the second resist pattern is formed. A semi-transparent part pattern forming step including a step of etching the semi-transparent film using a mask as a mask. In the light shielding part pattern forming step, the light shielding part and the translucent part are formed together with the light shielding part pattern formation. Forming a desired mark pattern, and before drawing the second drawing pattern in the semi-translucent portion pattern forming step, so that the second resist film does not exist in the translucent portion of the mark pattern, The second resist film is applied except at least the light-transmitting part of the mark pattern, or after the second resist film is formed, at least the second resist film in the light-transmitting part of the mark pattern is removed. It is a manufacturing method of a gray tone mask.
(Configuration 6) A gray-tone mask in which a device pattern having a light-shielding part, a light-transmitting part, and a semi-light-transmitting part and a mark pattern used for alignment are formed, and the light-shielding part is provided on a transparent substrate A light-shielding film and a semi-transparent film laminated on a part or all of the light-shielding film, the semi-translucent part is formed of a semi-transparent film, and the translucent part is a part where a transparent substrate is exposed. The mark pattern is formed of at least a light-shielding portion made of a light-shielding film and a light-transmitting portion from which the transparent substrate is exposed.

  According to Configuration 1, the graytone mask manufacturing method of the present invention includes a step of preparing a mask blank having at least a light shielding film formed on a transparent substrate, the light shielding portion pattern forming step, and the light shielding portion pattern being formed. Forming a semi-transparent film on the transparent substrate formed, and the semi-transparent part pattern forming step, and in the light-shielding part pattern forming step, together with the light-shielding part pattern formation, Forming a desired mark pattern having a semi-transparent film before the second drawing pattern is drawn in the semi-translucent portion pattern forming step. Have.

  Therefore, the pattern drawing for forming the resist pattern is performed twice, and the mark for aligning the position of the two pattern writings is the same as the normal pattern (device pattern) in the non-device pattern area of the mask at the first pattern formation. In order to prevent the semi-transparent film from being present in the translucent portion of the mark before the second drawing, the mark pattern is formed. Since the contrast of transmitted light and reflected light between the light transmitting part and the light shielding part is high and the mark can be easily recognized, it is easy to detect the mark in the second drawing. Further, in the finally obtained gray-tone mask, the mark pattern is formed of at least a light-shielding portion made of a light-shielding film and a light-transmitting portion where the transparent substrate is exposed. When the mask is used, the mark can be easily detected when used for alignment with the transfer substrate.

Further, as in Configuration 2, in the step of forming the semi-transparent film, the semi-transparent film pattern is formed by forming the semi-transparent film excluding at least the translucent part of the mark pattern. Before drawing the second drawing pattern in the process, it is possible to prevent the semi-transparent film from being present at least in the light-transmitting portion of the mark pattern. Thereby, the contrast of the transmitted light and reflected light of the mark is increased, and mark detection at the time of alignment is facilitated. As a method of forming the semi-transparent film excluding at least the translucent part of the mark pattern, for example, the semi-transparent film is formed through a shielding member that covers at least the translucent part of the mark pattern. Can be mentioned.
Further, as in Configuration 3, after forming the semi-transparent film, at least the semi-transparent film in the translucent part of the mark pattern is removed, so that the second drawing in the semi-transparent part pattern forming step is performed. Before the pattern is drawn, it is possible to prevent the semi-transparent film from existing at least in the translucent part of the mark pattern. Thereby, the contrast of the transmitted light and reflected light of the mark is increased, and mark detection at the time of alignment is facilitated.

  Further, as in Configuration 4, the second resist film is applied at least excluding the light transmitting portion of the mark pattern, or after the second resist film is formed, at least a second portion in the light transmitting portion of the mark pattern is applied. By removing the resist film, the second resist film does not exist in the light-transmitting portion of the mark pattern before the drawing of the second drawing pattern in the semi-light-transmitting portion pattern forming step. it can. Thereby, in addition to the absence of the semi-transparent film at least in the light-transmitting portion of the mark pattern, the second resist film is not present, so that the transparent substrate is exposed in the light-transmitting portion of the mark pattern, The reduction in transmittance due to the resist film is suppressed, and a higher contrast of transmitted light and reflected light between the light shielding portion and the light transmitting portion of the mark pattern is obtained, making it easier to recognize the mark. Detection is further facilitated.

Further, according to Configuration 5, the graytone mask manufacturing method of the present invention includes a step of preparing a mask blank having at least a light shielding film formed on a transparent substrate, the light shielding portion pattern forming step, and the light shielding portion pattern. A step of forming a semi-transparent film on the transparent substrate on which is formed, and the semi-transparent part pattern forming step. In the light-shielding part pattern forming step, together with the light-shielding part pattern formation, the light-shielding part and the light-transmissive part And forming a desired mark pattern having a portion, and before drawing the second drawing pattern in the semi-light-transmitting portion pattern forming step, the second resist film does not exist in the light-transmitting portion in the mark pattern. The second resist film is applied excluding at least the light-transmitting part of the mark pattern, or after forming the second resist film, at least the light-transmitting part of the mark pattern Removing the definitive second resist film.
Accordingly, since the second resist film does not exist at least in the light transmitting portion of the mark pattern, it is possible to suppress a decrease in the transmittance of the light transmitting portion of the mark pattern due to the second resist film. Compared with the case where the second resist film is present in the optical portion, the contrast between the transmitted light and the reflected light is improved, and the mark detection at the second drawing is further facilitated.

  Further, as described in Structure 6, the gray-tone mask of the present invention is such that the light-shielding portion of the device pattern includes a light-shielding film provided on the transparent substrate and a semi-transparent film laminated on a part or all of the light-shielding film. The translucent part is formed of a semi-transparent film, the translucent part is formed by a portion where the transparent substrate is exposed, and the mark pattern is at least a light-shielding portion made of the light-shielding film and the transparent substrate exposed. Because it is formed from the light part, the contrast of the transmitted light and reflected light between the light-transmitting part and the light-shielding part in the mark pattern is high, and it is easy to detect the mark when using the mask for alignment with the transfer substrate. is there.

According to the gray-tone mask manufacturing method of the present invention, pattern drawing for forming a resist pattern is performed twice, and a mark for aligning the positions of the two pattern writings is formed on the non-device of the mask during the first pattern formation. When the pattern area is formed in the same way as the normal pattern (device pattern), and alignment is performed based on the mark and the second drawing is performed, the translucent portion of the mark is translucent before the second drawing. Since the film is not present, the mark contrast is high, and mark detection at the second drawing is easy.
Further, according to the method of manufacturing a gray-tone mask of the present invention, pattern drawing for forming a resist pattern is performed twice, and a mark for aligning the position of two pattern writings is formed on the mask at the first pattern formation. When a second pattern is formed by aligning on the non-device pattern area in the same way as a normal pattern (device pattern) and performing the second pattern, the resist is placed on the transparent part of the mark before the second pattern. Since the film is not present, the mark contrast is high, and mark detection at the second drawing is easy.
Further, according to the gray-tone mask of the present invention, the light shielding part is formed of the light shielding film provided on the transparent substrate and the semi-transparent film laminated on a part or all of the light shielding film, It is formed from a semi-transparent film, and the translucent part is formed in a non-device pattern area in a gray-tone mask formed by a portion where the transparent substrate is exposed, and is used for alignment with a transfer substrate when using the mask. Since mark patterns of various marks such as alignment marks are formed from at least a light-shielding portion made of a light-shielding film and a light-transmitting portion from which the transparent substrate is exposed, the mark contrast is high and easy to detect.

Hereinafter, the present invention will be described in detail by embodiments.
(Embodiment 1)
1 (a) and 1 (b) show a first embodiment of a method for manufacturing a gray-tone mask according to the present invention, and are schematic cross-sectional views sequentially illustrating the manufacturing process.
The mask blank used in the present embodiment is obtained by forming a light shielding film 22 on a transparent substrate 21 such as quartz glass, as shown in FIGS.
Here, the material of the light shielding film 22 is preferably a thin film that provides high light shielding properties, and examples thereof include Cr, Si, W, and Al.
The mask blank is obtained by forming the light shielding film 22 on the transparent substrate 21. The film forming method can be selected from film types such as vapor deposition, sputtering, and CVD (chemical vapor deposition). A suitable 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.

  As shown in FIGS. 1B and 9, the gray tone mask 20 </ b> B of the present embodiment obtained using the mask blank is formed with a device pattern and a mark pattern. The device pattern has a semi-transparent portion (A (d) region shown), a light-shielding portion (B (d) region shown), and a translucent portion (C (d) region shown). The mark pattern has a light shielding portion (B (m) region shown) and a light transmitting portion (C (m) region shown). The light shielding portion of the device pattern is formed by a light shielding film 22a provided on the transparent substrate 21 and a semi-transparent film 23 thereon, and the semi-transparent portion is a semi-transparent film formed on the transparent substrate 21. The transparent portion is formed by a portion where the transparent substrate 21 is exposed. The mark pattern is formed in a non-device pattern region of the mask, and is formed by a light shielding portion made of a light shielding film 22a provided on the transparent substrate 21 and a light transmitting portion where the transparent substrate 21 is exposed. In the plan view, the device pattern and the mark pattern are, for example, the mark pattern (M) in FIG. 9 and the device pattern (D) shown in the enlarged view. However, in FIGS. 1A and 1B of the present embodiment, the device pattern and the mark pattern are schematically shown, and exactly match the device pattern and the mark pattern shown in FIG. is not.

Next, a manufacturing process of the gray tone mask 20B using the mask blank will be described.
First, for example, a positive resist for drawing is applied on the mask blank (FIGS. 1A and 1), and baking is performed to form a resist film, and an electron beam drawing machine or a laser drawing machine is used. And draw. For example, in the case of the device pattern (D) shown in FIG. 9 described above, the drawing data in this case is a pattern corresponding to the translucent portion pattern (A region) and the translucent portion (C region). Data and pattern data corresponding to the translucent part of the mark pattern for alignment. After drawing, this is developed to form a semi-transparent part and a translucent part of the device pattern on the mask blank (areas A (d) and C (d) shown in FIG. 1A) In addition, in the region where the light transmission part of the mark pattern is formed (the region C (m) shown in FIG. 1A), the resist film is removed and the region where the light shielding part of the device pattern is formed (FIG. 1A). (B (d) region shown in FIG. 1) and a region (B (m) shown in FIG. 1 (a)) where the light shielding portion of the mark pattern is formed (resist pattern 24a in which the resist film remains is formed (FIG. 1 (a)). (Refer FIG. 1 (a) (2)).

Next, using the formed resist pattern 24a as a mask, the exposed light shielding film 22 is etched to form light shielding film patterns 22a corresponding to the light shielding portions of the device pattern and the mark pattern (FIG. 1A). 3)). The light shielding is performed in the semi-transparent portion and the translucent portion of the device pattern (A (d) and C (d) region) and the region corresponding to the translucent portion of the mark pattern (C (m) region). The underlying transparent substrate 21 is exposed by the etching of the film 22. Accordingly, in this step, a desired mark pattern is formed together with the light shielding portion pattern of the device pattern.
The remaining resist pattern 24a is removed using ashing with oxygen or concentrated sulfuric acid (see FIGS. 1A and 1D).

Next, the semi-transparent film 23 is formed on the substrate having the light shielding film pattern 22a on the transparent substrate 21 obtained as described above (see FIGS. 1B and 5). At this time, the semi-transparent film 23 is formed at least on the translucent part of the mark pattern by arranging the shielding plate 30 covering at least the region corresponding to the translucent part of the mark pattern to form the semi-transparent film 23. Do not be. A semi-transparent film 23 is directly formed on the exposed transparent substrate 21 in the semi-transparent part and the region corresponding to the translucent part of the device pattern.
The material of the semi-transparent film 23 is preferably a thin film that can obtain a semi-transmissivity of about 50% when the transmissivity of the translucent part is 100%. For example, a Cr compound (Cr oxidation) Material, 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. 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 combination of the materials of the light shielding film 22 and the semi-transparent film 23 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. That is, in the present invention, the semi-transparent part is formed by directly forming the semi-transparent film on the transparent substrate in which the region corresponding to the semi-transparent part is exposed. It is possible to select a combination of materials having the same or similar etching characteristics of the light shielding film and the semi-transparent film. 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.
As for the method for forming the semi-transparent film 23, as in the case of the light shielding film 22 described above, a method suitable for the film type, such as a vapor deposition method, a sputtering method, or a CVD (chemical vapor deposition) method, may be selected as appropriate. Good. Further, the film thickness of the semi-transparent film 23 is not particularly limited, but may be formed with an optimized film thickness so as to obtain desired semi-translucency.

Next, the positive resist is applied again to the entire surface and baked to form a resist film 24 (see FIGS. 1B and 6).
Then, the second drawing is performed. The drawing data at this time is pattern data corresponding to the translucent portion (C (d) region) of the device pattern. This second drawing is performed by irradiating light having a wavelength of 413 nm, for example, based on the mark formed in the previous light shielding film pattern 22a forming step (FIGS. 1A and 4), and detecting the reflected light to detect the position. However, since the translucent film 23 is not formed in the translucent part of the mark, the contrast between the translucent part and the light-shielding part in the mark is high and the mark can be easily recognized. It is easy to detect the mark at this time. Although the resist film 24 is formed in the light transmitting portion of the mark, the transmittance of the resist film with respect to the alignment light used for alignment is relatively high. High contrast is obtained in the relationship.
After drawing, this is developed to form a resist pattern 24b in which the resist film is removed in the light-transmitting portion of the device pattern and the resist film remains in other regions (see FIGS. 1B and 7).

Next, using the formed resist pattern 24b as a mask, the semi-transparent film 23 in a region to be a light transmitting portion of the device pattern is removed by dry etching. Thereby, the semi-transparent portion of the device pattern is defined as the translucent portion, and the semi-transparent portion (A (d) region) and the translucent portion (C (d) region) of the device pattern are formed (FIG. 1). (Refer to (b) (8)).
The remaining resist pattern 24b is removed using oxygen ashing or the like.

As described above, the gray-tone mask 20B of the present embodiment is completed (see FIGS. 1B and 9). Also in the finally obtained gray-tone mask 20B, the mark pattern portion is formed by a light shielding portion (B region shown) made of the light shielding film 22a and a light transmitting portion (C region shown) where the transparent substrate 21 is exposed. Therefore, the contrast between the light-transmitting portion and the light-shielding portion in the mark pattern portion is high, and it is easy to detect the mark when using the mask for alignment with the transfer substrate.
In this embodiment, a shielding plate is arranged so that a semi-transparent film is not formed at least on the light transmitting portion of the mark pattern. However, a shielding tape or a shielding film (for example, at least on the light transmitting portion of the mark pattern) After attaching the resist film) and forming the semi-transparent film, the semi-transparent film may be prevented from being formed at least on the translucent part of the mark pattern by removing the shielding tape or the shielding film. .

(Embodiment 2)
FIG. 2 shows Embodiment 2 of the method for manufacturing a gray-tone mask according to the present invention, and is a schematic cross-sectional view sequentially illustrating a part of the manufacturing process.
In the present embodiment, the steps until the predetermined light shielding film pattern 22a is formed using the mask blank in which the light shielding film 22 is formed on the transparent substrate 21 are the same as those in FIG. Since it is exactly the same as the steps (1) to (4), illustration and duplication description are omitted here.

A semi-transmissive film 23 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. 2 (5)).
Next, the positive resist is applied again on the entire surface and baked to form a resist film on the semi-translucent film 23, and at least the translucent portion (C (m)) of the mark pattern is formed on the resist film. The resist pattern 24c is formed by drawing and developing for exposing the region (see FIG. 2 (6)). In consideration of the positional deviation of drawing in this case, a margin may be provided as shown to expose a region slightly larger than the translucent portion (C (m) region) of the mark pattern. Next, the semi-transparent film 23 formed on the translucent part of the mark pattern is removed by etching using the resist pattern 24c as a mask (see FIG. 2 (7)).

Next, after removing the remaining resist pattern 24c, the positive resist is applied again on the entire surface and baked to form a resist film 24 (see FIG. 2 (8)).
Then, the second device pattern drawing is performed. The drawing data at this time is pattern data corresponding to the light-transmitting portion (C (d) region) of the device pattern. At the time of drawing, the light-transmitting portion of the mark for alignment is first displayed. By removing the semi-transparent film 23 by etching, since the semi-transparent film 23 does not exist, the mark can be easily recognized and the mark can be easily detected at the time of drawing. In this embodiment as well, the resist film 24 is formed in the light transmitting part of the mark, but high contrast is obtained in relation to the light shielding part of the mark formed by the light shielding film 22a.
After the drawing, this is developed to form a resist pattern 24b in which the resist film is removed in the light-transmitting portion of the device pattern and the resist film remains in other regions (see FIG. 2 (9)).

Next, by using the formed resist pattern 24b as a mask, the semi-transparent film 23 in the region that becomes the translucent part of the device pattern is removed by dry etching, so that the semi-transparent part of the device pattern is separated from the translucent part. Then, a semi-transparent portion (A (d) region) and a translucent portion (C (d) region) of the device pattern are formed (see FIG. 2 (10)).
The remaining resist pattern 24b is removed using oxygen ashing or the like.

As described above, the gray tone mask 20C of the present embodiment is completed (see FIG. 2 (11)). Also in the obtained gray-tone mask 20C of the present embodiment, the mark pattern portion has a light shielding portion (B region shown in the figure) composed of the light shielding film 22a and the semi-transparent film 23 thereon, and the transparent substrate 21 exposed. Since it is formed from the light part (C area shown in the figure), the contrast of the transmitted light and reflected light between the light-transmitting part and the light-shielding part in the mark pattern part is high, and alignment with the transfer substrate is performed when using the mask. It is easy to detect the mark when performing.
In the present embodiment, the semi-transparent film 23 formed on the translucent part of the mark pattern is removed by etching using the resist pattern 24c as a mask. However, the resist pattern 24c is not formed, and wiping with an etching solution is performed. The semi-transparent film formed in the translucent part of the mark pattern may be removed by a partial process such as the above.

(Embodiment 3)
FIG. 3 shows a third embodiment of the method for manufacturing a gray-tone mask according to the present invention, and is a schematic cross-sectional view sequentially illustrating a part of the manufacturing process.
Also in the present embodiment, the steps until the predetermined light shielding film pattern 22a is formed using the mask blank in which the light shielding film 22 is formed on the transparent substrate 21 are the same as those in the first embodiment shown in FIG. Since the steps (1) to (4) are exactly the same as those shown in FIG.

A semi-transmissive film 23 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. 3 (5)).
Next, the positive resist is applied again over the entire surface to form a resist film 24 (see FIG. 3 (6)), and then a resist film formed at least in the light transmitting portion (C (m) region) of the mark pattern. Is removed so that the resist film does not exist in the translucent portion of the mark pattern (see FIG. 3 (7)). In order to prevent the resist film 24 from being present in the light transmitting portion in the mark pattern, the resist film may be formed by applying at least the light transmitting portion region of the mark pattern. Further, in the present embodiment, in order to prevent the resist film 24 from existing at least in the light transmitting portion of the mark pattern, the resist film 24 may not be formed on the entire mark pattern including the light shielding portion as illustrated. Of course it is good.
Next, the semi-transparent film 23 exposed in the mark pattern portion is removed by etching using the resist pattern 24d as a mask (see FIG. 3 (8)). Thereby, at least the translucent part in the mark pattern is in a state where the transparent substrate 21 is exposed.

Next, the second drawing is performed. The drawing data at this time is pattern data corresponding to the translucent portion (C (d) region) of the device pattern. At the time of drawing, the translucent part of the mark pattern for alignment does not have the semi-transparent film 23 by removing the semi-transparent film 23 by etching first, and there is also a resist film. Therefore, the transparent substrate 21 is exposed. Accordingly, a higher contrast between the light shielding portion and the light transmitting portion of the mark pattern can be obtained, and the mark can be more easily recognized, so that the mark detection at the second drawing is further facilitated.
After drawing, this is developed to form a resist pattern 24e in which the resist film is removed in the light-transmitting portion of the device pattern and the resist film remains in other regions of the device pattern (see FIG. 3 (9)).

Next, by using the formed resist pattern 24e as a mask, the semi-transparent film 23 in the region to be the translucent part of the device pattern is removed by dry etching, so that the semi-transparent part of the device pattern is separated from the translucent part. Thus, a semi-transparent portion (A (d) region) and a translucent portion (C (d) region) of the device pattern are formed (see FIG. 3 (10)). At this time, since the light shielding film 22a in the mark pattern is exposed, a slight film reduction is expected, but there is no problem because a high contrast is still obtained.
The remaining resist pattern 24e is removed using oxygen ashing or the like.

  As described above, the gray-tone mask 20D of the present embodiment is completed (see FIG. 3 (11)). Also in the obtained gray-tone mask 20D of the present embodiment, the mark pattern portion is formed by a light shielding portion (B region shown) made of the light shielding film 22a and a light transmitting portion (C region shown) where the transparent substrate 21 is exposed. Thus, the contrast between the light transmitting portion and the light shielding portion in the mark pattern portion is high, and it is easy to detect the mark when using the mask for alignment with the transfer substrate.

Note that, in relation to the above-described third embodiment, also in the step of forming the resist film 24 for performing the second drawing in the first embodiment (FIGS. 1B and 6). Then, after the resist film 24 is formed on the entire surface, at least the resist film formed in the light transmitting portion (C (m) region) of the mark pattern is removed, or the resist film is formed at least in the light transmitting portion of the mark pattern. By coating and forming excluding the region, it is possible to prevent the resist film from being present in the light-transmitting portion of the mark pattern, so that the contrast can be further enhanced during mark detection.
Also, in the step of forming the resist film 24 for performing the second device pattern drawing in the above-described second embodiment (FIG. 2 (8)), after forming the resist film 24 over the entire surface, at least the above-mentioned By removing the resist film formed in the light transmitting portion (C (m) region) of the mark pattern, or by coating and forming the resist film excluding at least the light transmitting portion region of the mark pattern, Since it is possible to prevent the resist film from being present in the optical part, the contrast can be further enhanced during mark detection.
In the third embodiment, the semi-transparent film 23 exposed in the mark pattern portion is removed. However, even if the semi-transparent film 23 is not removed, the resist film 24 is removed. The contrast can be improved as compared with the case where the resist film 24 is not removed.

The method for forming the device pattern portion is not limited to the embodiment described above. For example, the resist pattern in the region corresponding to the light shielding portion and the light transmitting portion of the device pattern is drawn on the mask blank by the first drawing. Using the resist pattern as a mask, the exposed light shielding film is etched to expose the transparent substrate in the region corresponding to the semi-transparent portion of the device pattern. After removing the resist pattern, the entire surface of the substrate is semi-transparent. An optical film is formed, and a resist pattern is formed in a region corresponding to the light-shielding portion and the semi-transparent portion by the second drawing, and the semi-transparent portion of the exposed translucent portion is formed using the resist pattern as a mask. The light transmitting part and the light shielding part may be formed by etching the film and the light shielding film.
In the embodiment described above, the case where a positive resist is used is exemplified, but a negative resist may be used. In this case, the process can be performed in the same manner as described above, only by reversing the drawing data.

It is typical sectional drawing which shows the manufacturing process of the gray tone mask which concerns on Embodiment 1 of this invention. It is typical sectional drawing which shows the manufacturing process (continuation of the manufacturing process of Fig.1 (a)) of the gray tone mask which concerns on Embodiment 1 of this invention. It is typical sectional drawing which shows the manufacturing process of the gray tone mask which concerns on Embodiment 2 of this invention. It is typical sectional drawing which shows the manufacturing process of the gray tone mask which concerns on Embodiment 3 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 (a)) of the TFT substrate using a gray tone mask. It is a top view which shows an example of a fine tone type gray tone mask. It is a top view which shows an example of a gray-tone mask pattern of a halftone film type. It is a mask pattern top view for demonstrating the manufacturing method of a gray-tone mask of a halftone film type. It is typical sectional drawing which shows an example of the manufacturing process of a gray tone mask. It is typical sectional drawing which shows an example (continuation of the manufacturing process of Fig.8 (a)) of the manufacturing process of a gray tone mask. (A) is a plan view of the gray-tone mask 20A, (b) is a cross-sectional view of the mark pattern (M) portion formed in the non-device pattern region of the mask, and (c) is a cross-sectional view of the device pattern (D).

Explanation of symbols

20A, 20B, 20C, 20D Gray tone mask 21 Transparent substrate 22 Light shielding film 23 Semi-transparent film 24 Resist film

Claims (6)

In the manufacturing method of a gray-tone mask in which a device pattern having a light-shielding part, a light-transmitting part and a semi-light-transmitting part and a mark pattern used for alignment are formed,
Preparing a mask blank having at least a light shielding film formed on a transparent substrate; and
A first drawing pattern is drawn on a first resist film for forming a light-shielding part pattern, developed to form a first resist pattern, and the light-shielding film is etched using the first resist pattern as a mask. A light shielding part pattern forming process including a process;
Forming a semi-translucent film on the transparent substrate on which the light shielding part pattern is formed;
A second drawing pattern is drawn on a second resist film formed on the semi-transparent film to form a semi-transparent portion pattern, and developed to form a second resist pattern. A semi-transparent part pattern forming step including a step of etching the semi-transparent film using a resist pattern as a mask,
In the light shielding part pattern forming step, together with the light shielding part pattern formation, a desired mark pattern having a light shielding part and a light transmitting part is formed,
A gray tone mask comprising: a step of preventing a semi-transparent film from being present in a translucent portion of the mark pattern before drawing of the second drawing pattern in the semi-translucent portion pattern forming step. Production method.   The step of preventing the semi-transparent film from being present in the translucent portion of the mark pattern is the step of forming the semi-transparent film in the step of forming the semi-transparent film, excluding at least the translucent portion of the mark pattern. 2. The method of manufacturing a gray-tone mask according to claim 1, wherein the method is a film forming step.   The step of preventing the semi-transparent film from being present in the translucent portion in the mark pattern is a step of removing at least the semi-transparent film in the translucent portion of the mark pattern after forming the semi-transparent film. The method for producing a gray-tone mask according to claim 1, wherein:   Before drawing the second drawing pattern in the semi-transparent part pattern forming step, at least the second resist film is formed so that the second resist film does not exist in the transparent part in the mark pattern. 4. The method according to any one of claims 1 to 3, wherein the coating is applied except for the light transmitting part of the mark pattern, or at least the second resist film in the light transmitting part of the mark pattern is removed after the second resist film is formed. A method for producing a gray tone mask according to claim 1. In the manufacturing method of a gray-tone mask in which a device pattern having a light-shielding part, a light-transmitting part and a semi-light-transmitting part and a mark pattern used for alignment are formed,
Preparing a mask blank having at least a light shielding film formed on a transparent substrate; and
A first drawing pattern is drawn on a first resist film for forming a light-shielding part pattern, developed to form a first resist pattern, and the light-shielding film is etched using the first resist pattern as a mask. A light shielding part pattern forming process including a process;
Forming a semi-translucent film on the transparent substrate on which the light shielding part pattern is formed;
A second drawing pattern is drawn on a second resist film formed on the semi-transparent film to form a semi-transparent portion pattern, and developed to form a second resist pattern. A semi-transparent part pattern forming step including a step of etching the semi-transparent film using a resist pattern as a mask,
In the light shielding part pattern forming step, together with the light shielding part pattern formation, a desired mark pattern having a light shielding part and a light transmitting part is formed,
Prior to the drawing of the second drawing pattern in the semi-transparent part pattern forming step, at least the second resist film is formed in the mark pattern so that the second resist film does not exist in the transparent part of the mark pattern. A method for producing a gray-tone mask, which is applied except for the light-transmitting portion, or after the second resist film is formed, at least the second resist film in the light-transmitting portion of the mark pattern is removed. A gray-tone mask in which a device pattern having a light-shielding part, a light-transmitting part and a semi-light-transmitting part and a mark pattern used for alignment are formed,
The light-shielding part is formed of a light-shielding film provided on a transparent substrate and a semi-transparent film laminated on a part or all of the light-shielding film, and the semi-translucent part is formed of a semi-transparent film, The translucent part is formed by a portion where the transparent substrate is exposed,
2. The gray tone mask according to claim 1, wherein the mark pattern includes at least a light-shielding portion made of a light-shielding film and a light-transmitting portion from which the transparent substrate is exposed.

Images