JP2019003109A - Method for manufacturing phase shift mask - Google Patents

Abstract

To manufacture a phase shift mask showing an accurate phase shift effect with a smaller number of processes.SOLUTION: A method for manufacturing a phase shift mask M is provided, which includes: a step of forming a phase shift layer 11, a light-shielding layer 13 and a resist layer PR1, successively deposited with a predetermined opening pattern on a surface S1 of a transparent substrate S; a step of disposing a reflection part 20 having a reflection surface 21a on the top side of the resist layer, exposing the resist layer PR1 having the pattern through the opening side by use of reflection of exposure light re incident to the back side of the transparent substrate and reflected by the reflection surface, so as to form a resist pattern PR1b; and a step of forming a light-shielding pattern 13b in the light-shielding layer by use of the resist pattern. In the phase shift mask M, the line width of the light-shielding pattern formed in the light-shielding layer in a plan view is set to be narrower than the line width of a phase shift pattern 11a formed in the phase shift layer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a phase shift mask capable of forming a fine and highly accurate exposure pattern, and more particularly to a technique suitable for use in manufacturing a flat panel display.

In semiconductors, pattern miniaturization has been performed over a long period of time in order to perform high-density mounting. For this purpose, various techniques such as shortening the exposure wavelength and improving the exposure method have been studied.
In order to achieve pattern miniaturization in photomasks, a phase shift mask that can form a finer pattern using a single wavelength using light interference at the pattern edge is used from a light shielding film patterning photomask that uses a composite wavelength. Has been done.
For this reason, as shown in Patent Document 1, an edge-enhanced phase shift mask has been used.

  However, in the above conventional example, a light shielding layer is formed on a transparent substrate, this light shielding layer is etched and patterned, and a phase shift layer is formed so as to cover the patterned light shielding layer. A phase shift mask is manufactured by etching and patterning. When film formation and patterning are alternately performed in this way, the transfer time between the apparatuses and the processing waiting time become long, and the production efficiency is remarkably lowered. In addition, the phase shift layer and the light shielding layer cannot be continuously etched through a single mask having a predetermined opening pattern, and it is necessary to form a mask (resist pattern) twice. Will increase. Therefore, there is a problem that the phase shift mask cannot be manufactured with high mass productivity.

  In view of the above points, a phase shift mask in which a phase shift layer, an etching stopper layer, and a light shielding layer are provided in this order on the transparent substrate surface can be considered. The phase shift pattern by the phase shift film transmits several percent to several tens percent of light and inverts the phase angle of the light by approximately 180 degrees. However, side lobes are generated in the vicinity of the phase shift pattern, and transfer to the panel side is performed. Sometimes, it is expected that the resist surface on the panel side is exposed to light by leakage light, and as a result, the pattern accuracy does not increase.

  Further, in pattern formation, as described in Patent Documents 2 and 3, a back exposure technique is known.

JP 2011-13283 A Japanese Patent Laid-Open No. 7-152146 JP 2005-202012 A

In order to reduce the side lobe, it is conceivable to provide a light shielding pattern with a light shielding film in the range of 0.5 to 2.0 μm from the phase shift pattern edge where the influence remains. But,
In the techniques described in Patent Documents 2 and 3, in order to make the light-shielding film pattern thinner than the phase shift pattern edge in this way, the lithography process including resist re-coating must be repeated once more, and a plurality of times. It is necessary to form a resist film, and since there are many steps, there has been a demand to reduce this. That is, in the patterning process, there has been a demand for shortening the manufacturing process by making it possible to form a phase shift pattern, an etching stopper pattern, and a light shielding film pattern by only one resist coating process.

  Furthermore, it is difficult to accurately set a dimension in which the light-shielding film pattern recedes from the phase shift pattern edge as a desired value. In the techniques described in Patent Documents 2 and 3, in the resist film formation multiple times, There was a possibility that the accuracy of the alignment was low.

The present invention has been made in view of the above circumstances, and intends to achieve the following object.
1. The width dimension in which the light shielding pattern recedes from the phase shift pattern is accurately set as a desired value.
2. It is possible to easily manufacture an edge-enhanced phase shift mask that reduces the number of manufacturing steps and reduces the influence of side lobes that appear near the edge of the phase shift pattern.

  As shown in FIGS. 6A and 6B, the halftone mask manufactured in the present invention has a transfer pattern formed of a phase shift pattern 120 and a light shielding pattern 130 laminated on a transparent substrate 110. However, the shape of the transfer pattern, that is, the shape of the light shielding pattern and the phase shift pattern is set according to the use of the halftone mask. For example, a hole pattern shown in FIGS. 6A and 6B or a line and space pattern can be provided as a transfer pattern.

  Here, the light intensity distribution of the halftone mask 100 shown in FIG. 6C corresponds to the transfer dimension set by the light intensity distribution in the single-layer phase shift pattern 120 as shown in FIG. 7C. In order to make it possible to form the transfer dimension more accurately, a light-shielding pattern 130 having a light intensity distribution shown in FIG. 8C alone is laminated at a position retracted from the edge of the phase shift pattern 120. ing.

  This is because, for example, when pattern transfer is performed using a halftone phase shift mask, a pattern edge shape such as a to-hole pattern is formed with high accuracy by the phase effect. Here, the phase effect decreases as the phase shift pattern is separated from the edge in the direction opposite to the hole. Therefore, in the phase shift layer that is a light semi-transmissive layer, the exposure light is transmitted even in the portion where the exposure light should be shielded, and the side lobe in which the area other than the area where the exposure light transmission portion (hole or the like) is formed is exposed. A phenomenon may occur.

  In order to prevent such a side lobe phenomenon, a light shielding layer is formed on the phase shift layer so that the exposure light is not transmitted through a portion where the exposure light should be shielded. At this time, in order to prevent the sidelobe phenomenon while maintaining the phase effect at the pattern edge, it is necessary to accurately arrange the edge of the light shielding layer so as to be at a predetermined distance from the edge of the phase shift layer.

  For this reason, it is extremely important to set the dimension in which the edge of the light shielding pattern 130 recedes from the edge of the phase shift pattern 120, that is, the width dimension of the exposed phase shift pattern 120. Therefore, the inventors of the present application decided to realize high-accuracy side etching in the light shielding layer without going through a new resist coating process.

The method of manufacturing a phase shift mask of the present invention includes a step of forming a phase shift layer, a light shielding layer, and a resist layer, which are sequentially laminated with a predetermined opening pattern on the surface of a transparent substrate,
A reflective part having a reflective surface is disposed on the resist layer surface side, and the resist layer having a pattern is exposed from the opening side by reflection of the exposure light incident from the back side of the transparent substrate by the reflective surface. Forming a step;
Forming a light shielding pattern in the light shielding layer by the resist pattern;
Having
The above problem has been solved by manufacturing a phase shift mask in which the line width of the light shielding pattern formed in the light shielding layer is set narrower than the line width of the phase shift pattern formed in the phase shift layer in plan view.
In the present invention, the transparent substrate;
The phase shift layer formed on the surface of the transparent substrate;
The light shielding layer laminated on the phase shift layer,
A method of manufacturing a phase shift mask in which a line width of a light shielding pattern formed in the light shielding layer is set narrower than a line width of a phase shift pattern formed in the phase shift layer in plan view,
Forming the resist layer on the light shielding layer;
Forming the phase shift pattern and forming the same pattern on the light shielding layer and the resist layer; and
A reflective portion having the reflective surface is disposed on the resist layer surface side, and the resist layer on the phase shift pattern is exposed from the opening side by exposure from the back surface side of the transparent substrate and reflection by the reflective surface. Forming the resist pattern;
Forming the light-shielding pattern with the resist pattern;
It is more preferable to have.
The present invention includes a step of sequentially forming the phase shift layer, the light shielding layer, and the resist layer on the transparent substrate surface;
Exposing from the resist layer surface side, forming a pre-resist pattern having the opening pattern on the light shielding layer;
Etching the light shielding layer and the phase shift layer with the pre-resist pattern to form a pre light shielding pattern and the phase shift pattern;
Disposing a reflective portion having the reflective surface above the pre-resist pattern;
Exposing the pre-resist pattern from the opening side to form the resist pattern by exposing from the back side of the transparent substrate and reflecting by the reflecting surface;
Releasing the arrangement of the reflecting portion;
Etching the pre-light-shielding pattern with the resist pattern to form the light-shielding pattern;
It is possible to have
Further, the reflection part may be disposed on the resist layer surface side by a contact method or a proximity method.
In the present invention, a means in which the resist layer is a positive type may be employed.
Further, the reflectance of the exposure light on the reflecting surface may be 45% to 65%.
Moreover, it is preferable that the said reflection part is formed in the glass plate surface with the said reflective surface which consists of a metal chromium layer.
In the present invention, by controlling the exposure time from the back side of the transparent substrate, it is possible to set a dimension in which the edge of the light shielding pattern is retreated from the edge of the phase shift pattern in plan view.

The method of manufacturing a phase shift mask of the present invention includes a step of forming a phase shift layer, a light shielding layer, and a resist layer, which are sequentially laminated with a predetermined opening pattern on the surface of a transparent substrate,
A reflective part having a reflective surface is disposed on the resist layer surface side, and the resist layer having a pattern is exposed from the opening side by reflection of the exposure light incident from the back side of the transparent substrate by the reflective surface. Forming a step;
Forming a light shielding pattern in the light shielding layer by the resist pattern;
Having
By manufacturing a phase shift mask in which the line width of the light shielding pattern formed on the light shielding layer is set narrower than the line width of the phase shift pattern formed on the phase shift layer in plan view, the phase shift mask is obtained. For example, the reflective portion that is a separate body from the transparent substrate is disposed so as to be close to or in contact with the resist layer, and the patterned phase shift layer and the light shielding layer are used as a mask from the back surface of the transparent substrate. The exposed exposure light is reflected by the reflecting surface through the opening formed in this pattern, and the resist layer is exposed from the side surface of the opening of the pattern, so that the resist layer is moved back from the phase shift pattern contour (edge). Can be removed. Thus, a single resist layer can be exposed in two stages, and each phase can be patterned into a phase shift layer and a light shielding layer can be patterned. Steps such as resist removal, re-application of another resist, re-alignment, and re-exposure are omitted, and the light-shielding pattern formed in the light-shielding layer is wider than the line width of the phase-shift pattern formed in the phase-shift layer in plan view. A phase shift mask having a narrow line width can be manufactured. Further, there is a self-alignment effect, and CD accuracy can be improved.

  In the present invention, the phase shift mask means that the edge of the light-shielding pattern formed on the light-shielding layer is retreated from the edge of the phase-shift pattern formed on the phase-shift layer in plan view. A transparent substrate on which the exposed pattern is not disposed, a phase shift region in which only the phase shift layer is laminated on the transparent substrate, and a light shielding region in which the phase shift layer and the light shielding layer are laminated on the transparent substrate; , Are arranged adjacent to each other in order, the distance from the edge of the phase shift pattern that is the boundary between the light transmission region and the phase shift region to the edge of the light shielding pattern that is the boundary between the phase shift region and the light shielding region, In other words, the width dimension of the phase shift area is set so that the halftone mask has a light intensity that allows the phase shift pattern to be accurately transferred to the exposure object during exposure. Which means that it is.

In the present invention, the transparent substrate;
The phase shift layer formed on the surface of the transparent substrate;
The light shielding layer laminated on the phase shift layer,
A method of manufacturing a phase shift mask in which a line width of a light shielding pattern formed in the light shielding layer is set narrower than a line width of a phase shift pattern formed in the phase shift layer in plan view,
Forming the resist layer on the light shielding layer;
Forming the phase shift pattern and forming the same pattern on the light shielding layer and the resist layer; and
A reflective part having the reflective surface is arranged on the resist layer surface side, and the resist layer on the phase shift pattern is exposed from the opening side by being exposed from the back side of the transparent substrate and reflected by the reflective layer. Forming the resist pattern;
Forming the light-shielding pattern with the resist pattern;
The resist layer formed on the upper side (outer surface) of the light-shielding layer is subjected to surface exposure (exposure from the front side), and the resist layer corresponding to the opening is removed, whereby the phase shift pattern Furthermore, back exposure (exposure from the back side) is performed using the formed pattern as a mask, so that the same resist layer is directed from the pattern opening to the transparent substrate in-plane direction (substrate surface by reflected light from the reflection surface). The width of the light-shielding pattern receding from the phase shift pattern by further removing the light-sensitive layer corresponding to the removed resist layer Dimensions can be formed as desired values.
As a result, it is possible to form a phase shift pattern and a light-shielding pattern with only the single resist layer described above, and the number of manufacturing steps, manufacturing time, amount of emissions associated with manufacturing, and manufacturing costs can be greatly reduced. It becomes.

The present invention includes a step of sequentially forming the phase shift layer, the light shielding layer, and the resist layer on the transparent substrate surface;
Exposing from the resist layer surface side, forming a pre-resist pattern having the opening pattern on the light shielding layer;
Etching the light shielding layer and the phase shift layer with the pre-resist pattern to form a pre light shielding pattern and the phase shift pattern;
Disposing a reflective portion having the reflective surface above the pre-resist pattern;
Exposing the pre-resist pattern from the opening side to form the resist pattern by exposing from the back side of the transparent substrate and reflecting by the reflecting surface;
Releasing the arrangement of the reflecting portion;
Etching the pre-light-shielding pattern with the resist pattern to form the light-shielding pattern;
With respect to the pre-light-shielding pattern and the pre-resist pattern that are substantially the same shape as the phase shift pattern in plan view, the opening contour that recedes toward the light-shielding area side covered with the light-shielding layer rather than the pattern opening area A resist pattern having the same is formed. At this time, by exposing the back surface using the phase shift pattern and the pre-light-shielding pattern as a mask, the pre-resist pattern is further exposed from the pattern opening to the in-plane direction of the transparent substrate (direction along the substrate surface) by the reflected light of the reflecting surface. Can be removed. Thereby, it is possible to expose the resist layer in two stages without peeling off, to form the phase shift pattern and the pre-light-shielding pattern for each stage, and to form the light-shielding pattern.

  In addition, by arranging the reflective portion on the resist layer surface side by a contact method or a proximity method, the reflective portion that is separate from the transparent substrate that becomes the phase shift mask can be disposed close to the resist film, for example. The exposure light irradiated from the back surface of the transparent substrate is placed on the reflection surface through the opening formed in the pattern, with the phase shift layer and the light shielding layer formed as a mask, arranged so as to contact each other. By reflecting the resist layer from the side surface of the opening in the pattern, it is possible to form a width dimension at which the light shielding pattern recedes from the phase shift pattern as a desired value.

  In the present invention, since the resist layer is a positive type, a predetermined portion can be removed by exposure and exposure in each of the front surface exposure and the back surface exposure. In particular, in the backside exposure process, it is necessary to be a positive type in order to perform exposure by reflection from the side of the resist layer.

  Further, the reflectance of the exposure light on the reflecting surface is set to 45% to 65%, so that the reflected light is controlled to a desired state, and exposure / photosensitivity to the resist layer from the side is in a predetermined state. It can be easily controlled so that

  In addition, by forming the reflective portion formed of a metallic chrome layer on the glass plate surface, the reflective portion forms a chrome layer serving as a reflective surface on a glass substrate separate from the phase shift mask. In the back exposure process using reflected light, this reflective surface is brought into contact with or close to the light-shielding layer, and by moving the glass substrate, there is no need to provide a wet process as a removal process from the transparent substrate. Because glass substrates can be used repeatedly, it does not require consumable materials, so there is no need for extra material costs, reducing manufacturing costs, and the number of manufacturing processes other than glass substrate cleaning processes. It is possible to reduce the time required for manufacturing and manufacturing.

  In the present invention, the side lobe phenomenon is prevented by controlling the exposure time from the back side of the transparent substrate and setting a dimension in which the edge of the light-shielding pattern recedes from the edge of the phase shift pattern in plan view. Thus, a phase shift mask capable of controlling the phase shift characteristics with high accuracy can be manufactured. As a result, the accuracy of the pattern 11CD can be increased.

  Further, in the present invention, at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W and Hf is formed on the surface of the phase shift layer on the side away from the transparent substrate. Is a method of manufacturing a phase shift mask in which the light shielding layer is formed on the etching stopper layer, the step of forming the etching stopper layer, and over the mask The light shielding layer and the etching stopper layer may be sequentially etched to form a light shielding pattern and an etching stopper pattern, and the etching stopper layer may be further etched. As a result, the etching stopper layer can also be used as a mask for backside exposure.

  Alternatively, in the present invention, the phase shift layer is mainly composed of at least one metal selected from Cr, Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W, and Hf. it can.

  According to the present invention, a phase shift mask that reduces the number of resists to be used, reduces the number of necessary steps, prevents sidelobe phenomenon only by controlling the back exposure light, and has a more accurate phase shift effect. It is possible to produce an effect that it can be manufactured.

It is process drawing which shows 1st Embodiment of the manufacturing method of the phase shift mask which concerns on this invention. It is process drawing which shows 1st Embodiment of the manufacturing method of the phase shift mask which concerns on this invention. It is a SEM photograph which shows the experimental example of the manufacturing method of the phase shift mask which concerns on this invention. It is a SEM photograph which shows the experimental example of the manufacturing method of the phase shift mask which concerns on this invention. It is a SEM photograph which shows the experimental example of the manufacturing method of the phase shift mask which concerns on this invention. It is a schematic plan view (a) for explaining a phase shift mask, a sectional view (b), and a figure (c) showing light intensity distribution. It is a schematic plan view (a) for explaining a phase shift mask, a sectional view (b), and a figure (c) showing light intensity distribution. It is a schematic plan view (a) for explaining a phase shift mask, a sectional view (b), and a figure (c) showing light intensity distribution.

Hereinafter, a first embodiment of a method of manufacturing a phase shift mask according to the present invention will be described with reference to the drawings.
FIG. 1 is a process diagram illustrating a method for manufacturing a phase shift mask in the present embodiment, and FIG. 2 is a process diagram illustrating a method for manufacturing a phase shift mask in the present embodiment. In the figure, reference numeral MB denotes a phase shift mask. Mask blanks.

  As shown in FIG. 1A, the phase shift mask blank MB of the present invention includes a transparent substrate S, a phase shift layer 11 formed on the transparent substrate S, and an etching formed on the phase shift layer 11. It comprises a stopper layer 12 and a light shielding layer 13 formed on the etching stopper layer 12.

As the transparent substrate S, quartz glass made of a material excellent in transparency and optical isotropy, low expansion glass containing SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , RO, R ₂ O, etc. For example, a quartz glass substrate can be used. The magnitude | size in particular of the transparent substrate S is not restrict | limited, It selects suitably according to the board | substrate (for example, board | substrate for FPD, a semiconductor substrate) exposed using the said mask. In the present embodiment, the present invention can be applied to a substrate having a diameter of about 100 mm, a rectangular substrate having a side of about 50 to 100 mm, and a side of 300 mm or more. A substrate having a thickness of 1000 mm or more and a thickness of 10 mm or more can also be used.

  Further, the flatness of the transparent substrate S may be reduced by polishing the surface of the transparent substrate S. The flatness of the transparent substrate S can be set to 20 μm or less, for example. As a result, the depth of focus of the mask is increased, and it is possible to greatly contribute to the formation of a fine and highly accurate pattern. Further, the flatness is preferably as small as 10 μm or less.

  The phase shift layer 11 is mainly composed of Cr, and is specifically selected from Cr alone, and oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides of Cr. In addition, two or more kinds selected from these can be stacked and configured.

  The phase shift layer 11 has a thickness (for example, 90 to 170 nm) that can give a phase difference of about 180 ° to any light in a wavelength region of 300 nm to 500 nm (for example, i-line having a wavelength of 365 nm). ).

  As the etching stopper layer 12, a material mainly composed of at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W and Hf can be used. A -Ti-Nb-Mo film can be used.

  The light shielding layer 13 is mainly composed of Cr, and is specifically selected from Cr alone, and oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides of Cr. In addition, it has a reflection suppression layer on the outermost surface, which has two or more selected from these layers, and has a reflection suppression function for exposure light and drawing light on the surface. It can also be configured.

  The phase shift layer 11, the etching stopper layer 12, and the light shielding layer 13 can be formed by sputtering, electron beam vapor deposition, laser vapor deposition, ALD, or the like, for example.

  The phase shift mask M of the present embodiment includes, for example, a phase shift layer (phase shift pattern) 11 capable of giving a phase difference of 180 °, and the phase shift pattern 11a formed in the phase shift layer 11 The opening width of the light shielding pattern 13b formed in the light shielding layer 13 is set wider than the opening width.

  According to the phase shift mask M, by using a composite wavelength including light in the above-described wavelength region, particularly g-line (436 nm), h-line (405 nm), and i-line (365 nm) as exposure light, the phase inversion action A region where the light intensity is minimized can be formed to make the exposure pattern clearer. By such a phase shift effect, the pattern accuracy is greatly improved, and a fine and highly accurate pattern can be formed. The phase shift layer can be formed of chromium oxide, chromium oxynitride, chromium oxynitride chromium carbide, or the like, and can be formed of an oxide film, a nitride film, or an oxynitride film containing Si.

  The thickness of the phase shift layer can be set to a thickness that gives a phase difference of about 180 ° with respect to the i-line. Furthermore, the above-described phase shift layer may be formed with a thickness capable of giving a phase difference of about 180 ° with respect to the h-line or the g-line. Here, “substantially 180 °” means 180 ° or near 180 °, and is, for example, 180 ° ± 10 ° or less. According to this phase shift mask, it is possible to improve the pattern accuracy based on the phase shift effect by using the light in the wavelength region, and it is possible to form a fine and highly accurate pattern. Thereby, a high-quality flat panel display can be manufactured.

  The phase shift mask of this embodiment can be configured, for example, as a patterning mask for an FPD glass substrate. As will be described later, for the patterning of the glass substrate using the mask, a composite wavelength of i-line, h-line and g-line is used for exposure light.

  Hereinafter, the manufacturing method of the phase shift mask which manufactures the phase shift mask M from the phase shift mask blanks MB of this embodiment is demonstrated.

  As shown in FIG. 1A, the phase shift mask blanks MB of the present embodiment is first formed on the surface S1 of the glass substrate S by using a DC sputtering method or the like, using a phase shift layer 11 containing Cr as a main component. Then, an etching stopper layer 12 containing Ni as a main component and a light shielding layer 13 containing Cr as a main component are sequentially formed. The phase shift layer 11, the etching stopper layer 12, and the light shielding layer 13 are all formed over the entire surface S1 of the glass substrate S so as to have a uniform thickness.

  Next, as shown in FIG. 1B, a photoresist layer (resist layer) PR1 is formed on the light shielding layer 13 which is the uppermost layer of the phase shift mask blanks MB. The photoresist layer PR1 is made of a positive photoresist material. As the photoresist layer PR1, for example, a liquid resist such as GRX-M237 manufactured by Nagase Chemtex Co., Ltd. is used, and it is formed using a technique such as spin coating.

Subsequently, as shown in FIG. 1C, the photoresist layer PR1 is exposed to the exposure light fe from the surface S1 side of the glass substrate S and is developed as shown in FIG. 1D. Then, the development region PR is deleted, and a pre-resist pattern PR1a is formed on the light shielding layer 13.
Specifically, the exposure light fe is irradiated (exposed) to the resist layer PR1 that covers the opening formation planned region PR of the light shielding layer 13, and a developer composed of an organic solvent or the like is supplied to the resist layer PR1 by a spray method or the like. Development is performed to form a pre-resist pattern PR1a that covers a region where the phase shift pattern 11a is to be formed.

  The pre-resist pattern PR1a functions as an etching mask for the phase shift layer 11 and the light shielding layer 13, and the shape is appropriately determined according to the phase shift pattern 11a of the phase shift layer 11 and the pre light shielding pattern 13a of the light shielding layer 13.

  Here, the pre-resist pattern PR1a is formed in a state where the phase shift layer 11 covers a region exposed from the light shielding layer 13, and has a shape having an opening width corresponding to the opening width dimension of the phase shift pattern 11a to be formed. Set to Accordingly, the pre-resist pattern PR1a is formed with an opening width dimension that is narrower than the opening width dimension of the light shielding pattern 13b described later.

Next, as shown in FIG. 1E, the light shielding layer 13 is wet-etched using the first resist solution over the pre-resist pattern PR1a using the pre-resist pattern PR1a as an etching mask. As the first etching solution, cerium ammonium nitrate ((NH ₄ ) ₂ Ce (NO ₃ ) ₆ ) and a chromium etching solution made of pure water containing acids such as nitric acid and perchloric acid can be used. For example, it is preferable to use ceric ammonium nitrate containing perchloric acid (HClO ₄ ). Here, since the etching stopper layer 12 has high resistance to the first etching solution, only the light shielding layer 13 is patterned to form the pre-light shielding pattern 13a. The pre-light shielding pattern 13a has a shape having an opening width corresponding to the pre-resist pattern PR1a. Furthermore, as shown in FIG. 1 (f), a descum process is performed. Descum treatment is a process in which the resist surface is modified from hydrophobic (repelling water) to hydrophilic (easy to get wet with water) and introduced to eliminate uneven processing of the etching solution. It is exposed to the resist pattern surface.

  Next, as shown in FIG. 1G, the etching stopper layer 12 is wet etched using the second etching solution over the pre-resist pattern PR1a. As the second etching solution, a solution obtained by adding at least one selected from acetic acid, perchloric acid, hydrogen peroxide solution and hydrochloric acid to nitric acid can be suitably used. Here, since the light shielding layer 13 and the phase shift layer 11 have high resistance to the second etching solution, only the etching stopper layer 12 is patterned to form the pre-etching stopper pattern 12a. The pre-etching stopper pattern 12a has a shape having an opening width corresponding to the opening width dimension of the pre-light-shielding pattern 13a and the pre-resist pattern PR1a.

  Next, as shown in FIG. 2A, the phase shift layer 11 is wet etched using the first etching solution over the pre-resist pattern PR1a, that is, without removing the pre-resist pattern PR1a. Here, the phase shift layer 11 is patterned to form the phase shift pattern 11a. The phase shift pattern 11a has a shape having a predetermined opening width dimension.

At the same time, the pre-light-shielding pattern 13a is made of the same Cr-based material as the phase shift layer 11, and is slightly side-etched because the side surface of the pre-light-shielding pattern 13a is exposed. The light shielding pattern 13b having a slightly larger opening width is formed.
However, since the light shielding layer 13 is made of the same Cr material as that of the phase shift layer 11, the side etching amount is not so large.

  Further, in order to increase the side etching amount of the pre-light-shielding pattern 13a so that a necessary shape can be formed only by etching in the light-shielding layer 13, the side of the pre-light-shielding pattern 13a with respect to the etching amount of the phase shift layer 11 While it is necessary to increase the etching amount and lengthen the total etching processing time, in this way, when the etching processing time is increased, the pre-light-shielding pattern is damaged by the etching solution beyond the side etching of the pre-light-shielding pattern 13a. 13a or phase shift pattern 11a.

  The formed pre-resist pattern PR1a, phase shift pattern 11a, pre-etching stopper pattern 12a, and pre-light-shielding pattern 13a all have substantially the same opening pattern in plan view. The openings formed in the pre-resist pattern PR1a, the phase shift pattern 11a, the pre-etching stopper pattern 12a, and the pre-light shielding pattern 13a penetrate in the thickness direction of the resist layer PR1, the phase shifting layer 11, the etching stopper layer 12, and the light shielding layer 13. In the bottom surface, the surface S1 of the glass substrate S is exposed.

  Next, as shown in FIG. 2B, the front and back surfaces of the glass substrate S on which the pre-resist pattern PR1a, the phase shift pattern 11a, the pre-etching stopper pattern 12a, and the pre-light-shielding pattern 13a are formed are reversed, and the reflecting portion 20 As described above, the glass substrate 22 having the reflective layer 21 formed on the entire surface is disposed so as to contact the surface of the pre-resist pattern PR1a.

  The reflective layer 21 is, for example, a layer made of metallic chrome, and the reflectance with respect to the exposure light in the reflective layer 21a on the surface thereof is 45% to 65%.

  Further, the reflection layer 21 is preferably reflected so as to scatter exposure light, as will be described later. For this reason, the reflective layer 21 has a thickness that can withstand the reflection of the exposure light, and the reflective surface 21a that reflects the exposure light in the reflective layer 21 can expose a side surface of the pre-resist pattern PR1a described later. Has roughness.

  Specifically, the composition in the reflective layer 21 made of metallic chrome is adjusted so as to have the above-described reflectance, or the reflectance by controlling the film thickness in the reflective layer 21 made of metallic chrome is controlled. Can have a rate.

  As the reflective layer 21, if the reflective surface 21a can exhibit a predetermined reflectivity and does not adversely affect the phase shift layer 11, the etching stopper layer 12, and the light shielding layer 13 during the mask formation process, the chrome film In addition, it is possible to form a film made of other metals such as aluminum. However, if the reflectance of the reflecting surface 21a exceeds 65%, a standing wave appears on the cross section of the resist image during exposure using the reflecting portion 20. Occurs, and the pattern width accuracy decreases, which is not preferable.

  Further, as the reflection portion 20, the reflection layer 21 and the glass substrate (glass plate) 22 on which the reflection layer 21 is formed have predetermined flatness and flatness, and exhibit the reflection characteristics on the reflection surface 21a described above. If possible, these configurations are not particularly limited.

  Subsequently, as shown in FIG. 2C, the pre-resist pattern PR1a is exposed by irradiating exposure light re from the back surface S2 side of the glass substrate S. By irradiating the back surface with this exposure light re, exposure is performed through portions not shielded by the pre-light-shielding pattern 13a and the phase-shift pattern 11a, that is, the openings formed in the phase-shift pattern 11a, the etching stopper pattern 12a, and the pre-light-shielding pattern 13a. The light re reaches the reflecting layer 21 and is reflected by the reflecting surface 21a.

The exposure light re reflected by the reflecting surface 21a of the reflecting layer 21 is scattered in the lateral direction (in-plane direction of the glass substrate S) because the reflecting surface 21a of the reflecting layer 21 is in the state described above. ) Is reflected.
The exposure light re reflected in the lateral direction exposes the development region PRS which is the opening side (side surface) of the pre-resist pattern PR1a, and the development region PRS is deleted by developing in the same manner for each surface exposure. As shown in FIG. 2 (d), a resist pattern PR1b can be formed.

  Here, the side exposure (side exposure) in the pre-resist pattern PR1a becomes the development area PRS as it is, but the size of the development area PRS, that is, the side exposure (side exposure) in the pre-resist pattern PR1a is performed. The depth in the horizontal direction can be set by controlling the exposure time with the exposure light re.

  Specifically, if the reflectance of the reflection surface 21a in the reflection layer 21 and the sensitivity in the resist layer 11 are set to predetermined values in advance and the exposure time for irradiating the exposure light re is increased, the size of the development region PRS is increased. Can be set large, and if the exposure time for irradiating the exposure light re is shortened, the size of the development region PRS can be set small. The width dimension of the development region PRS can be set within a range of 200 nm to 1000 nm, for example.

  As will be described later, since the size of the development region PRS is the region where the phase shift pattern 11a is exposed as it is, the dimension that the light shielding layer 13 recedes from the phase shift layer 11, that is, the phase shift effect, It can be made controllable by the exposure time for irradiating the exposure light re in exposure.

  After the back surface exposure and the development processing are completed, the reflecting portion 20 is removed. At this time, since the reflection part 20 is separate from the glass substrate S, the reflection layer 21 can be removed simply by moving the reflection part 20.

Next, as shown in FIG. 2E, the light shielding layer 13 is wet etched using the first etching solution over the resist pattern PR1b. Here, since the etching stopper layer 12 has high resistance to the first etching solution, only the light shielding layer 13 is patterned to form the light shielding pattern 13b. The light shielding pattern 13b has a shape having an opening width corresponding to the resist pattern PR1b. Here, the phase shift pattern 11a is also slightly side-etched, but when the pre-resist pattern PR1a is formed, the shape is set in consideration thereof.
Further, the descum process can be performed as in FIG.

  Next, as shown in FIG. 2F, the etching stopper layer 12a exposed from the side surface of the light shielding pattern 13b is wet-etched using a second etching solution, and etching having an opening width corresponding to the light shielding pattern 13b is performed. The resist pattern PR1a is removed as the stopper pattern 12b. Since a known resist stripping solution can be used for removing the resist pattern PR1a, detailed description is omitted here. The removal of the resist pattern PR1a is satisfactory even after the light shielding pattern 13b is formed.

  As a result, as shown in FIG. 2G, an edge-enhanced phase shift mask M in which the opening width of the light shielding pattern 13b (and the etching stopper pattern 12b) is wider than the opening width of the phase shift pattern 11a is obtained.

  In the phase shift pattern 11a, the thickness in the region where the light shielding layer 13 is removed has a value corresponding to the thickness Tg (for example, 145 nm) at which the light intensity corresponding to the g line becomes zero. Alternatively, the thickness Th (for example, 133 nm) and Ti (for example, 120 nm) corresponding to the h line and i line can be used. Alternatively, the thickness of the phase shift layer 11 can be set to a value larger than Tg.

According to the present embodiment, the width of the phase shift pattern 11a exposed to the outside of the light shielding pattern 13b can be set by the exposure time for irradiating the exposure light re in the back surface exposure.
Furthermore, in order to control the size of the development region PRS, in addition to the setting of the exposure time irradiated by the exposure light re, the setting of the reflectance of the reflective layer 21 and the intensity setting of the exposure light re, ie, the resist pattern PR1. It is also possible to adopt a method of setting the energy applied to the to be a predetermined value.

  In FIG. 1 and FIG. 2, the side surfaces of the phase shift pattern 11 a and the light shielding pattern 13 b are shown to be formed vertically. However, actually, the unevenness caused by the difference in etching rate in the film thickness direction is present. Has occurred.

  Therefore, with respect to the width dimension of the pre-resist pattern PR1a, the width dimension between the resist layer PR1 side and the etching stopper layer 12b side (inclined state on the light shielding pattern 13b side), phase shift in the light shielding pattern 13b in plan view. The width dimension of the uniform thickness region of the pattern 11a, the dimension in which the phase shift pattern 11a recedes from the etching stopper layer 12a in plan view, and the sagging width in which the thickness of the phase shift pattern 11a decreases (inclined state of the side surface of the phase shift pattern 11a) ), The film forming conditions for each layer, the exposure time for irradiating the exposure light re in the back surface exposure, and the etching conditions are set to a desired state so that each dimension is a predetermined value.

  At this time, the light-shielding pattern 13b is in an inclined state where the etching stopper layer 12b side is located closer to the opening inner region (surface S1 exposed region of the glass substrate S) side than the resist layer PR1 side in plan view, and the etching stopper in plan view. An inclined state in which the resist layer PR1 side is located closer to the surface S1 exposed region side of the glass substrate S than the layer 12b side can be selected.

  The etching rate in the thickness direction of the phase shift layer 11 is such that when the phase shift layer 11 is formed on the surface of the glass substrate S, the film characteristics are adjusted such that the grain size of the chromium grains is increased as the film thickness increases. Thus, the etching rate on the etching stopper layer 12 side from the surface of the glass substrate S can be lowered. The grain size is different between the glass substrate S side and the etching stopper layer 12 side, and the etching stopper layer can be set to be 10% or smaller. Furthermore, if it is smaller than 20%, further effects can be obtained. The composition of the phase shift layer 11 may be continuously changed or may be changed stepwise.

  Similarly, the etching rate in the thickness direction of the light shielding layer 13 is a film characteristic such as increasing the grain size of the chromium grains as the film thickness increases when the light shielding layer 13 is formed on the surface of the etching stopper layer 12. Thus, the etching rate on the outer surface side can be made lower than the surface side of the etching stopper layer 12. The grain size is different between the etching stopper layer side and the surface side, and can be set so that the outer surface side is 10% or more smaller. Furthermore, if it is smaller than 20%, further effects can be obtained. The composition of the light shielding film 13 may be changed continuously or may be changed stepwise.

  Moreover, the influence of the side etching in the phase shift layer 11 in the etching process after the back exposure can be reduced by setting the etching rate in the light shielding layer 13 higher than the etching rate in the phase shift layer 11.

Further, the etching rate in the thickness direction of the phase shift pattern 11a is the ratio of the side etching rate in the phase shift layer 11 described above, and the value of the ratio of the etching rate on the glass substrate S side to the etching rate on the etching stopper layer 12 side. (Etching rate on the etching stopper layer 12 side) / (Etching rate on the glass substrate S side) = 7.10 to 21.78 may be set.

  By setting the back surface exposure time for the pre-resist pattern PR1a as described above, the development region PRS in the pre-resist pattern PR1a changes in the in-plane direction (lateral direction), and the etching region of the pre-shield pattern 13a becomes the substrate surface. It will change inward (lateral). Therefore, it is only necessary to set the back exposure time as a single parameter without taking the troublesome procedure of setting the etching amount, the side etching rate, and the ratio of both the phase shift layer 11 and the light shielding layer 13. While the side lobe phenomenon is prevented, the width dimension in which the light shielding pattern 13b recedes from the phase shift pattern 11a, that is, the width dimension in which the phase shift pattern 11a is exposed to the light shielding pattern 13b can be changed.

  Thereby, the width dimension of the phase shift pattern 11a in plan view with respect to the light shielding pattern 13b can be set within a predetermined range.

  According to the present embodiment, the phase shift mask blank MB is configured by laminating the phase shift layer 11, the etching stopper layer 12, and the light shielding layer 13 in this order on the transparent substrate S. An edge-enhanced phase shift mask M is manufactured by forming a pre-resist pattern PR1a on the light-shielding layer 13 of the phase-shift mask blank MB and controlling the backside exposure time for the pre-resist pattern PR1a using the reflective layer 21. it can. Therefore, a high-definition and highly visible phase shift mask M can be manufactured in a short time with a small number of steps without removing the resist layer PR1 and re-forming a different resist layer.

  According to the present embodiment, the phase shift mask M can have a phase difference of 180 ° with respect to any light that is, for example, g-line, h-line, or i-line in a wavelength region of 300 nm to 500 nm. A phase shift pattern 11a. Here, the width dimension of the phase shift pattern 11a formed adjacent to the edge of the light shielding pattern 13b can be set to about 0.5 μm to 2.0 μm.

  Therefore, according to the manufacturing method described above, the pattern accuracy based on the phase shift effect can be improved by using the light in the wavelength region, and the depth of focus can be further increased. For example, about 2.0 μm Corresponding to the mask pattern line width, the exposure width of the phase shift layer 11a having a uniform thickness that exhibits the phase shift effect is set to a width dimension of about 0.5 μm, and a fine and highly accurate pattern can be formed. . Thereby, a high-quality flat panel display can be manufactured.

  In the above embodiment, the etching rate of the phase shift layer 11 and the light shielding layer 13 is set by controlling the grain size. However, the phase shift layer 11 and the light shielding layer 13 are set by other factors such as film formation conditions and film composition. Is also possible.

  In the present embodiment, the glass substrate 22 is arranged as a contact method so as to contact the surface of the pre-resist pattern PR1a at the time of backside exposure. However, the glass substrate 22 is arranged as a proximity method separated from the surface of the pre-resist pattern PR1a. May be. In the case of the proximity method, the reflectance and the exposure time of the reflecting surface 21a described later can be set by changing to predetermined values so as to realize the corresponding exposure.

Furthermore, in the phase shift mask M of the above-described embodiment, the phase shift layer 11 is a layer containing chromium. However, the film configuration such as a layer made of MoSi, or a layer made of chromium laminated with a MoSi layer. It can also be. In addition to this, the phase shift mask M may be a MoSi-based etching stopper layer 12 with respect to the chromium-based phase shift layer.
Regardless of the layer configuration, an optimum edge-emphasized phase shift mask M can be manufactured by changing the exposed width dimension of the phase shift pattern 11a with respect to the light shielding pattern 13b only by the exposure time of the back surface exposure.

  Examples according to the present invention will be described below.

<Experimental example>
In order to confirm the above effect, the following experiment was conducted. That is, on the glass substrate S, a chromium oxynitride carbide film as the phase shift layer 11 is formed with a thickness of 120 nm by sputtering, and a Ni—Ti—Nb—Mo film as the etching stopper layer 12 is formed with a thickness of 30 nm. Then, a film composed of a main component layer of chromium oxynitride and a main component layer of chromium oxynitride carbide serving as the light shielding layer 13 is formed with a total thickness of about 100 nm, and the phase shift mask blank MB Got.

  A pre-resist pattern PR1a is formed on the phase shift mask blanks MB by surface exposure, and the light-shielding layer 13 is etched using a mixed etching solution of cerium diammonium nitrate and perchloric acid over the pre-resist pattern PR1a. Then, a pre-light-shielding pattern 13a was formed, and the etching stopper layer 12 was etched using a mixed etching solution of nitric acid and perchloric acid to form a pre-etching stopper pattern 12a. Next, the phase shift layer 11 was etched using a mixed etching solution of ceric ammonium nitrate and perchloric acid to form a phase shift pattern 11a.

  Furthermore, the glass substrate 22 having a film thickness of 80 nm deposited thereon is placed on the pre-resist pattern PR1a, exposed from the back surface S2 of the glass substrate S, and the pre-resist pattern PR1a is side-exposed to form the resist pattern PR1b. After the formation, the pre-light-shielding pattern 13a is etched through the resist pattern PR1b using a mixed etching solution of ceric ammonium nitrate and perchloric acid to form the light-shielding pattern 13b. An edge-enhanced phase shift mask M was obtained by forming the etching stopper pattern 12b by etching the pre-etching stopper pattern 12a using a mixed etching solution.

At this time, the exposure high intensity in the back surface exposure was the same, and the exposure time was changed to 7.0 sec, 60 sec, and 180 sec, and these were designated as experimental examples 1 to 3.
Each energy imparted to the pre-registration pattern PR1a from the exposure corresponding to the exposure time, 40 mJ / cm ² in Experimental Example 1, 342mJ / cm ² in Experimental Example 2, the 1026mJ / cm ^2, in Experimental Example 3.

Cross-sectional SEM photographs corresponding to each of Experimental Examples 1 to 3 are shown as FIGS.
From these photographs, the exposed width dimension (length dimension) of the phase shift pattern 11a with respect to the light shielding pattern 13b is 0.04 μm in Experimental Example 1, 1.12 μm in Experimental Example 2, and 1.88 μm in Experimental Example 3. It became.

  From these results, it was found that the width dimension (length dimension) exposed by the phase shift pattern 11a with respect to the light shielding pattern 13b can be precisely controlled by controlling the exposure time of the back surface exposure.

  As an application example of the present invention, it is possible to form a light-shielding film with a large side etch rate by using an underlay-type halftone mask having a phase shift effect particularly adapted for TFT contact hole pattern fabrication, and to shorten the manufacturing process. And TFT line and pattern.

MB ... Phase shift mask blanks M ... Phase shift mask S ... Glass substrate (transparent substrate)
S1 ... front surface S2 ... back surface PR1 ... resist layer (photoresist layer)
PR1a ... Pre-resist pattern PR ... Development area PR1b ... Resist pattern PRS ... Development area fe ... Exposure light re ... Exposure light 11 ... Phase shift layer 11a ... Phase shift pattern 12 ... Etching stopper layer 12a ... Pre-etching stopper pattern 12b ... Etching stopper Pattern 13 ... Light-shielding layer 13a ... Pre-light-shielding pattern 13b ... Light-shielding pattern 20 ... Reflection part 21 ... Reflection layer 21a ... Reflection surface 22 ... Glass substrate

Claims (8)

Forming a phase shift layer, a light shielding layer, and a resist layer, which are sequentially laminated with a predetermined opening pattern on the surface of the transparent substrate;
A reflective part having a reflective surface is disposed on the resist layer surface side, and the resist layer having a pattern is exposed from the opening side by reflection of the exposure light incident from the back side of the transparent substrate by the reflective surface. Forming a step;
Forming a light shielding pattern in the light shielding layer by the resist pattern;
Having
A phase shift mask for manufacturing a phase shift mask in which a line width of a light shielding pattern formed in the light shielding layer is set narrower than a line width of a phase shift pattern formed in the phase shift layer in plan view Manufacturing method. The transparent substrate;
The phase shift layer formed on the surface of the transparent substrate;
The light shielding layer laminated on the phase shift layer,
A method of manufacturing a phase shift mask in which a line width of a light shielding pattern formed in the light shielding layer is set narrower than a line width of a phase shift pattern formed in the phase shift layer in plan view,
Forming the resist layer on the light shielding layer;
Forming the phase shift pattern and forming the same pattern on the light shielding layer and the resist layer; and
A reflective portion having the reflective surface is disposed on the resist layer surface side, and the resist layer on the phase shift pattern is exposed from the opening side by exposure from the back surface side of the transparent substrate and reflection by the reflective surface. Forming the resist pattern;
Forming the light-shielding pattern with the resist pattern;
The method of manufacturing a phase shift mask according to claim 1, wherein: Forming the phase shift layer, the light shielding layer, and the resist layer in order on the transparent substrate surface;
Exposing from the resist layer surface side, forming a pre-resist pattern having the opening pattern on the light shielding layer;
Etching the light shielding layer and the phase shift layer with the pre-resist pattern to form a pre light shielding pattern and the phase shift pattern;
Disposing a reflective portion having the reflective surface above the pre-resist pattern;
Exposing the pre-resist pattern from the opening side to form the resist pattern by exposing from the back side of the transparent substrate and reflecting by the reflecting surface;
Releasing the arrangement of the reflecting portion;
Etching the pre-light-shielding pattern with the resist pattern to form the light-shielding pattern;
The method of manufacturing a phase shift mask according to claim 2, wherein:   4. The method of manufacturing a phase shift mask according to claim 1, wherein the reflection portion is disposed on the resist layer surface side by a contact method or a proximity method. 5.   5. The method of manufacturing a phase shift mask according to claim 1, wherein the resist layer is a positive type.   6. The method of manufacturing a phase shift mask according to claim 1, wherein a reflectance of the exposure light on the reflecting surface is 45% to 65%.   The method of manufacturing a phase shift mask according to any one of claims 1 to 6, wherein the reflection portion is formed by forming the reflection surface made of a metal chromium layer on a glass plate surface.   8. The exposure time from the back side of the transparent substrate is controlled to set a dimension in which the edge of the light shielding pattern recedes from the edge of the phase shift pattern in plan view. Manufacturing method of the phase shift mask.