JP5865520B2 - Phase shift mask and manufacturing method thereof - Google Patents

Description

The present invention relates to a phase shift mask capable of forming a fine and highly accurate exposure pattern and a manufacturing method thereof, and more particularly to a technique suitable for use in manufacturing a flat panel display.
This application claims priority in December 27, 2012 based on Japanese Patent Application No. 2012-285846 for which it applied to Japan, and uses the content here.

  In the manufacturing process of a semiconductor device or FPD, a phase shift mask is used to expose and transfer a fine pattern onto a resist film formed on a substrate made of silicon, glass, or the like. Since the glass substrate for FPD has a larger area than the silicon substrate for semiconductor, in order to expose the FPD substrate with a sufficient amount of exposure light, the composite wavelength of g-line, h-line and i-line Exposure light is used. When such exposure light is used, an edge-enhanced phase shift mask has been conventionally used (see, for example, Patent Document 1).

  On the other hand, a halftone type phase shift mask is used as a technique for achieving further miniaturization (see, for example, Patent Document 2). According to this method, when the phase is 180 ° at 193 nm, it is possible to set the location where the light intensity becomes zero and improve the patterning accuracy. Further, since there is a portion where the light intensity becomes zero, it is possible to set a large depth of focus, and it is possible to ease exposure conditions or improve patterning yield.

  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.

Japanese Unexamined Patent Publication No. 2011-13283 Japanese Unexamined Patent Publication No. 2006-78953

  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. With such a configuration, when the phase shift mask is manufactured by a photolithography method, an edge-enhanced phase shift mask in which the opening width of the pattern formed in the light shielding layer is wider than the opening width of the phase shift pattern, that is, the phase When the shift mask is viewed in plan, an edge-enhanced phase shift mask in which the phase shift pattern protrudes from the light shielding pattern is obtained.

  However, in the pattern region as an edge-enhanced phase shift mask, a wide shape in which the phase shift pattern protrudes from the light shielding pattern is preferable as described above. Even in this portion, the opening shape (width dimension) differs depending on the layer, which is not preferable.

  An aspect according to the present invention has been made to solve the above-described problem. In a phase shift mask suitable for manufacturing an edge-enhanced phase shift mask with high productivity, the phase shift pattern in the pattern region is shielded from light. It is possible to manufacture a phase shift mask capable of high-definition processing by simultaneously forming a wide shape that protrudes from the pattern and a structure in which the phase shift layer, the etching stopper layer, and the light shielding layer have the same planar shape in the light shielding region. It aims at providing the means to do.

(1) A phase shift mask according to one aspect of the present invention includes: a transparent substrate; a phase shift layer containing Cr as a main component formed on a surface of the transparent substrate; and the phase on the side away from the transparent substrate. An etching stopper layer formed mainly on at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W and Hf formed on the surface of the shift layer; A light shielding layer mainly composed of Cr formed on the etching stopper layer on the side away from the surface, and formed in the light shielding layer with respect to the opening width of the phase shift pattern formed in the phase shift layer. A phase shift region in which the opening width of the light shielding pattern is set wide, the opening width of the phase shift pattern formed in the phase shift layer, and the light shielding pattern formed in the light shielding layer. And having a serial shielding region where the opening width and is set to be equal.
(2) A method of manufacturing a phase shift mask according to one aspect of the present invention includes: a transparent substrate; a phase shift layer mainly composed of Cr formed on the surface of the transparent substrate; and a side separated from the transparent substrate. An etching stopper layer mainly composed of at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W and Hf, formed on the surface of the phase shift layer; A light shielding layer mainly composed of Cr formed on the etching stopper layer on the side away from the phase shift layer, wherein the light shielding layer has a width larger than the opening width of the phase shift pattern formed in the phase shift layer. A phase-shift region in which the opening width of the light-shielding pattern formed is set wide, and the opening width of the phase-shift pattern formed in the phase-shift layer and the light-shielding light previously formed in the light-shielding layer A method of manufacturing a phase shift mask having a light shielding region in which the opening width of a turn is set to be equal, the step of forming the phase shift layer, the etching stopper layer, and the light shielding layer on the transparent substrate Forming a first mask having a predetermined opening pattern on the light shielding layer; and sequentially etching the light shielding layer and the etching stopper layer through the formed first mask to etch the light shielding pattern and the etching mask layer. Forming a stopper pattern; etching the phase shift layer over the first mask to form a phase shift pattern; and covering the light shielding pattern exposed on the light shielding pattern surface and the pattern opening, The etching stopper pattern and the phase shift pattern exposed at the pattern opening are Wherein As is covered by uncovered in the light shielding region and the phase shift region, step and forming a second mask having a predetermined opening pattern; etching the phase shift pattern to a second mask over that this form And a step of further etching the etching stopper pattern after removing the second mask.
(3) In the above aspect (2), an etching solution containing nitric acid can be used for etching the etching stopper layer.

According to the above aspect (1), a transparent substrate; a phase shift layer mainly composed of Cr formed on the surface of the transparent substrate; and formed on the surface of the phase shift layer on the side away from the transparent substrate An etching stopper layer mainly composed of at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W and Hf; and on the side away from the phase shift layer A light shielding layer mainly composed of Cr formed on the etching stopper layer, and an opening of the light shielding pattern formed in the light shielding layer than an opening width of the phase shift pattern formed in the phase shift layer. A phase shift region having a wide width, the opening width of the phase shift pattern formed in the phase shift layer, and the opening width of the light shielding pattern formed in the light shielding layer are equal. In the edge-enhanced phase shift mask, the opening widths of the phase shift pattern, the etching stopper pattern, and the light-shielding pattern are made equal in the light-shielded area to maintain the alignment mark accuracy. However, an edge-enhanced phase shift mask that can cope with high definition can be manufactured with high mass productivity.
In the present invention, Cr as a main component is composed of any one selected from Cr and Cr oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides. That means.

According to the above aspect (2), a transparent substrate; a phase shift layer mainly composed of Cr formed on the surface of the transparent substrate; and formed on the surface of the phase shift layer on the side away from the transparent substrate An etching stopper layer mainly composed of at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W and Hf; and on the side away from the phase shift layer A light shielding layer mainly composed of Cr formed on the etching stopper layer, and an opening of the light shielding pattern formed in the light shielding layer than an opening width of the phase shift pattern formed in the phase shift layer. The phase shift region having a wide width, the opening width of the phase shift pattern formed in the phase shift layer, and the opening width of the preceding light shielding pattern formed in the light shielding layer are equal. A method of manufacturing a phase shift mask having a defined light shielding region, the step of forming the phase shift layer, the etching stopper layer, and the light shielding layer on the transparent substrate; Forming a first mask having a plurality of opening patterns; and sequentially etching the light shielding layer and the etching stopper layer through the formed first mask to form a light shielding pattern and an etching stopper pattern; Etching the phase shift layer through the first mask to form a phase shift pattern; and covering the light shielding pattern surface and the pattern opening, and exposing the etching stopper exposed to the pattern opening; The pattern and the phase shift pattern are not covered with the light shielding region. As will be covered in the phase shift region, step and forming a second mask having a predetermined opening pattern; the second mask; step and etching said phase shift pattern on the second mask over that this form In the edge-enhanced phase shift mask, the opening widths of the phase shift pattern, the etching stopper pattern, and the light shielding pattern are made equal in the light shielding region. Therefore, it is possible to manufacture an edge-enhanced phase shift mask that can cope with high definition while maintaining the accuracy of the alignment mark with high mass productivity.

  In the case of (3) above, an etching solution containing nitric acid can be used for etching the etching stopper layer (etching stopper pattern).

In the phase shift region, a resist pattern (first mask) is formed as a single mask having a predetermined opening pattern on the light shielding layer of the phase shift mask blank, and the light shielding layer is etched through the resist pattern. A light shielding pattern having a predetermined width is formed.
Further, the etching stopper pattern is formed by etching the etching stopper layer through the resist pattern. At this time, although the side surface of the light shielding pattern is exposed, the light shielding pattern is made of a material different from that of the etching stopper pattern, so that the light shielding pattern and the etching stopper pattern have the same width.

  Next, the phase shift layer having the same width as the etching stopper pattern is formed by etching the phase shift layer through the resist pattern. At this time, since the light shielding pattern made of the same Cr-based material as the phase shift pattern is also etched, the opening width of the light shielding pattern becomes wider than the width of the phase shift pattern. Through the above steps, the opening width of the light shielding pattern becomes wider than the opening widths of the phase shift pattern and the etching stopper pattern.

Similarly in the light shielding region, the opening width of the light shielding pattern is wider than the opening width of the phase shift pattern by using the first mask. Next, a predetermined opening pattern is formed so that the surface of the light shielding layer and the light shielding layer (side surface) exposed at the pattern opening are covered, and the etching stopper layer and the phase shift layer (phase shift pattern) exposed at the pattern opening are not covered. A second mask is formed.
At this time, in the phase shift region, unlike the light shielding region, the side surfaces of the light shielding pattern, the etching stopper pattern, and the phase shift pattern exposed on the surface of the light shielding pattern and the pattern opening are all covered with the second mask. That is, a second mask having a predetermined width narrower than the opening width of the light shielding pattern, the etching stopper pattern, and the phase shift pattern is formed.

Next, the phase shift pattern having the same opening width as the opening width of the light shielding pattern is formed by etching the side face of the phase shift pattern exposed to the pattern opening through the resist pattern. At this time, the light shielding pattern exposed to the pattern opening is protected by the second mask and is not etched. Thereafter, after the second mask is removed, finally, the etching stopper pattern is further etched. At this time, by setting only the side surface of the etching stopper pattern, the light shielding pattern and the etching stopper pattern are set to have the same side surface. At this time, the side surfaces of the phase shift pattern and the light shielding pattern are exposed, but the phase shift pattern and the light shielding pattern are not etched because they are made of a material different from the etching stopper pattern, and the phase shift pattern, the light shielding pattern and the etching stopper are not etched. The pattern is the same.
At the same time, the etching stopper pattern is etched also in the phase shift region. Through the above steps, an edge-enhanced phase shift mask in which the opening width of the light shielding pattern and the etching stopper pattern is wider than the opening width of the phase shift pattern is obtained.

  Thus, the phase shift mask can be manufactured in the light shielding region only by patterning the previously formed phase shift mask blanks. For this reason, it can be manufactured more efficiently compared to the case where film formation and patterning are performed alternately as in the conventional example, and the number of manufacturing steps can be reduced compared to the conventional example, so that a phase shift mask can be manufactured with high mass productivity. it can.

  In the present invention, the phase shift layer containing Cr as a main component is composed of any one selected from the oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides of the Cr, The film thickness is set so that the phase shift effect is sufficiently exhibited. In order to have such a film thickness that the phase shift effect can be sufficiently exerted, the etching time becomes longer than 1 time with respect to the etching time of the light shielding layer, but the adhesion strength between the layers is sufficient. Since it is high, it is possible to form a favorable pattern as a photomask having a substantially straight line roughness and a substantially vertical pattern cross section.

  Further, by using a film containing Ni as the etching stopper layer, the adhesion strength between the light shielding film containing Cr and the phase shift layer containing Cr can be sufficiently increased. For this reason, when the light shielding layer, the etching stopper layer, and the phase shift layer are etched with the wet etching liquid, the etching liquid penetrates from the interface between the light shielding layer and the etching stopper layer or the interface between the etching stopper layer and the phase shift layer. Therefore, the CD accuracy of the formed light-shielding pattern and phase shift pattern can be increased, and the cross-sectional shape of the film can be made to be a shape close to a favorable vertical for the photomask.

  According to an aspect of the present invention, in a phase shift mask suitable for manufacturing an edge-enhanced phase shift mask with high mass productivity, a wide shape in which the phase shift pattern in the pattern region protrudes from the light shielding pattern, and light shielding. It is possible to form a high-definition mask by forming a structure in which the phase shift pattern, the etching stopper pattern, and the light shielding pattern in the region have the same planar shape.

It is process drawing explaining the manufacturing method of the phase shift mask which concerns on the 1st Embodiment of this invention. It is process drawing explaining the manufacturing method of the phase shift mask which concerns on the 1st Embodiment of this invention.

<First Embodiment>
Below, one Embodiment of the manufacturing method of the phase shift mask which concerns on this invention is described based on drawing.
FIG. 1 and FIG. 2 are process diagrams schematically showing a method of manufacturing a phase shift mask according to the present embodiment, where MB is a phase shift mask blank.

  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, a material excellent in transparency and optical isotropy is used. For example, a quartz glass substrate or a 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 this 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, and a quartz substrate having a length of 450 mm, a width of 550 mm, and a thickness of 8 mm, and a maximum side dimension. 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 and the light shielding layer 13 are mainly composed of Cr, and specifically, Cr alone, oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides of Cr. It can be composed of one selected from a product, or two or more selected from these can be laminated.

  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). ). The light shielding layer 13 is formed with a thickness (for example, 80 nm to 200 nm) that provides predetermined optical characteristics. 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 phase shift layer 11, the etching stopper layer 12, and the light shielding layer 13 can be formed by, for example, a sputtering method, an electron beam evaporation method, a laser evaporation method, an ALD method, or the like.

The phase shift mask M of the present embodiment has a phase shift layer (phase shift pattern) 11 capable of giving a phase difference of 180 °, and the opening width of the phase shift pattern 11a formed in the phase shift layer 11. The phase shift area PSA in which the opening width d2 of the light shielding pattern 13b formed in the light shielding layer 13 is set wider than d1 and the opening width d5 of the phase shift pattern 11b formed in the phase shift layer 11 and the light shielding layer 13 are formed. A light shielding area MSA in which the opening width d5 of the light shielding pattern 13b is set to be equal.
For example, an alignment mark AM can be provided in the light shielding area MSA, and the light shielding area MSA can be provided around the periphery of the transparent substrate S so as to surround the phase shift area PSA in plan view. .

  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 a chromium oxynitride-based material, and the thickness of the phase shift layer can be set to have a phase difference of about 180 ° with respect to 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.

  As shown in FIG. 1A, the phase shift mask blank MB of the present embodiment has a phase shift layer 11 containing Cr as a main component on a glass substrate S using a DC sputtering method, and Ni as a main component. The etching stopper layer 12 and the light shielding layer 13 mainly composed of Cr are sequentially formed. Hereinafter, a method of manufacturing a phase shift mask for manufacturing the phase shift mask M from the phase shift mask blanks MB will be described.

  Next, as shown in FIG. 1B, a photoresist layer PR1a is formed on the light shielding layer 13 which is the uppermost layer of the phase shift mask blank MB. The photoresist layer PR1a may be a positive type or a negative type. A liquid resist is used as the photoresist layer PR1a, but a dry film resist may be used.

  Subsequently, as shown in FIGS. 1C and 1D, the photoresist layer PR <b> 1 a is exposed and developed to remove the region PR <b> 1 b and form a resist pattern RP <b> 1 on the light shielding layer 13. The resist pattern RP <b> 1 functions as an etching mask for the light shielding layer 13, and the shape is appropriately determined according to the etching pattern of the light shielding layer 13. As an example, the phase shift area PSA is set to have a shape having an opening width d1 equal to the opening width dimension d1 of the phase shift pattern to be formed.

  Next, as shown in FIG. 1E, the light shielding layer 13 is wet etched using the first etching solution over the resist pattern RP1. As the first etching solution, an etching solution containing cerium diammonium nitrate can be used. For example, cerium diammonium nitrate containing an acid such as nitric acid or perchloric acid is preferably used. 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 13a. The light shielding pattern 13a has a shape having an opening width d1 equal to the resist pattern RP1.

  Next, as shown in FIG. 1F, the etching stopper layer 12 is wet etched using the second etching solution over the resist pattern RP. As the second etching solution, a solution obtained by adding at least one selected from acetic acid, perchloric acid, aqueous hydrogen peroxide 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 etching stopper pattern 12a. The etching stopper pattern 12a has a shape having an opening width d1 equal to the opening width dimension d1 of the light shielding pattern 13a and the resist pattern RP1.

  Next, as shown in FIG. 1G, the phase shift layer 11 is wet etched using the first etching solution over the resist pattern RP1, that is, without removing the resist pattern RP1. Here, since the light shielding pattern 13a is made of the same Cr-based material as the phase shift layer 11 and the side surfaces of the light shielding pattern 13a are exposed, the phase shift layer 11 is patterned to form the phase shift pattern 11a. The phase shift pattern 11a has a shape having an opening width dimension d1. At the same time, the light shielding pattern 13a is further side-etched to form a light shielding pattern 13b having an opening width d2 larger than the opening width dimension d1 of the phase shift pattern 11a. At this time, the etching stopper pattern 12a and the phase shift pattern 11a have a shape having an opening width d1 equal to the resist pattern RP1.

Next, as shown in FIG. 2H, the resist pattern RP1 is removed. Since a known resist stripping solution can be used for removing the resist pattern RP1, detailed description thereof is omitted here.
So far, the dimensions in the phase shift area PSA have been described. In the light shielding area MSA, for example, the etching stopper pattern 12a and the phase shift pattern 11a have a shape having an opening width d3 equal to the resist pattern RP1, and the light shielding pattern. Reference numeral 13b denotes a shape having an opening width d5 larger than the opening width dimension d3 of the phase shift pattern 11a.

  In the opening located near the boundary between the phase shift area PSA and the light shielding area MSA, for example, the etching stopper pattern 12a and the phase shift pattern 11a have a shape having an opening width d6 equal to the resist pattern RP1, and the light shielding pattern. Reference numeral 13b denotes a shape having an opening width d4 larger than the opening width dimension d6 of the phase shift pattern 11a.

  Next, as shown in FIG. 2J, a photoresist layer PR2a is formed on the entire surface of the glass substrate S. At this time, the photoresist layer PR2a is provided so as to cover the entire surface of the glass substrate S including the inside of the opening formed by the light shielding pattern 13b, the phase shift pattern 11a, and the etching stopper pattern 12a.

  Subsequently, as shown in FIGS. 2K and 2M, the photoresist layer PR2a is exposed and developed to remove the region PR2b and form a resist pattern RP2. At this time, the resist pattern RP2 is provided so as to cover the entire opening pattern on the glass substrate S including the inside of the opening formed by the light shielding pattern 13b, the phase shift pattern 11a, and the etching stopper pattern 12a. The resist pattern RP2 has a pattern shape similar to the opening pattern on the glass substrate S, that is, a planar shape similar to the resist pattern RP1, and is formed to have different opening width dimensions.

Specifically, in the phase shift area PSA and the opening located near the boundary between the phase shift area PSA and the light shielding area MSA, the resist pattern RP2 has an opening width smaller than the opening width dimensions d1 and d6 of the resist pattern RP1. The shape has d10 and d7. That is, the resist pattern RP2 has a light shielding pattern 13b, a phase shift pattern 11a, and an etching stopper pattern 12a in a pattern portion whose main purpose is to improve the patterning accuracy by setting a portion where the light intensity becomes zero. The width dimension is set so as to cover the side surface inside the opening pattern in which are stacked.
In the light shielding area MSA, the resist pattern RP2 has an opening width equal to the opening width dimension d3 of the resist pattern RP1, and covers only the side surface of the light shielding pattern 13b among the stacked side surfaces inside the opening. At the same time, the width dimension is set so that the side surfaces of the phase shift pattern 11a and the etching stopper pattern 12a are exposed.

Next, as shown in FIG. 2 (n), the phase shift pattern 11a is wet-etched using the first etching solution over the resist pattern RP2, that is, in a state covered with the resist pattern RP2. Here, the light shielding pattern 13b is not etched because it is covered with the resist pattern RP2 in both the phase shift area PSA and the light shielding area MSA.
At the same time, in the phase shift region PSA, the phase shift pattern 11a is not etched because it is covered with the resist pattern RP2.

  In the light shielding area MSA, the phase shift pattern 11a made of a Cr-based material is side-etched to form the phase shift pattern 11b. The phase shift pattern 11b has a shape having opening width dimensions d5 and d9. At the same time, the light shielding pattern 13b is not etched. As a result, the opening width dimension of the phase shift pattern 11b can be set to be the same opening width d5 as that of the light shielding pattern 13b. The etching stopper pattern 12a remains in a shape having opening widths d3 and d6 equal to those before this step.

Next, as shown in FIG. 2 (p), the resist pattern RP2 is removed. The resist pattern RP2 can be removed in the same manner as the resist pattern RP1.
Then, as shown in FIG. 2 (q), the etching stopper pattern 12a is further wet etched using the second etching solution. Thereby, the opening width of the etching stopper pattern 12b is made the same as the opening widths d2, d4, d5 of the light shielding pattern 13b.

  As described above, as shown in FIG. 2 (q), in the phase shift area PSA, the edge-enhanced phase in which the opening width d2 of the light shielding pattern 13b (and the etching stopper pattern 12b) is wider than the opening width d1 of the phase shift pattern 11b. A shift mask M is obtained.

  In this phase shift mask M, in the light shielding area MSA, the phase shift pattern 11b, the light shielding pattern 13b, and the opening width d5 of the etching stopper pattern 12b are equal, that is, the phase shift pattern 11b in the opening pattern serving as the alignment mark AM, The side surfaces of the light shielding pattern 13b and the etching stopper pattern 12b are flush with each other, and have a shape substantially equal to the exposure direction of the exposure process.

  Further, in the opening located near the boundary between the phase shift area PSA and the light shielding area MSA, for example, an edge having an opening width d4 of the light shielding pattern 13b (and the etching stopper pattern 12b) wider than the opening width d9 of the phase shift pattern 11b. An enhanced phase shift mask M is obtained. At the same time, the side surfaces of the phase shift pattern 11b, the light shielding pattern 13b, and the etching stopper pattern 12b in the opening pattern on the light shielding area MSA side are flush with each other, and the shape is substantially the same as the exposure direction of the exposure process.

  In the phase shift area PSA, the width (d2-d1) of the phase shift pattern 11a exposed outside the light shielding pattern 13b is determined by the etching rate of the light shielding pattern 13b when the phase shift layer 11 is wet etched. Here, the etching rate of the light shielding pattern 13 a is affected by the composition of the light shielding layer 13 and the interface state between the etching stopper layer 12 and the light shielding layer 13. For example, when the light shielding layer 13 is composed of two layers of a layer mainly composed of chromium and a layer mainly composed of chromium oxide, the ratio of the chromium component of the layer mainly composed of chromium can be increased. While the etching rate can be increased, the etching rate can be decreased by reducing the ratio of the chromium component. The etching amount of the light shielding pattern 13a can be set within a range of 200 nm to 1000 nm, for example.

  According to the above embodiment, the phase shift mask blanks MB are 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. By forming resist patterns RP1 and RP2 on the light shielding layer 13 of the phase shift mask blanks MB and performing wet etching on each layer using the resist patterns RP1 and RP2, the edge emphasis type with high positional accuracy of the alignment mark AM The phase shift mask M can be manufactured. Therefore, since the number of manufacturing steps can be reduced and the production efficiency can be increased as compared with the conventional example in which film formation and etching are repeated, the phase shift mask M with high mass productivity and high visibility can be manufactured.

  The phase shift layer 11 is composed of any one selected from Cr oxide, nitride, carbide, oxynitride, carbonitride, and oxycarbonitride, and exhibits a phase shift effect sufficiently. It has a film thickness. In order to have such a film thickness that the phase shift effect is sufficiently exerted, the etching time becomes longer than 1 time with respect to the etching time of the light shielding layer 13, but the adhesion strength between the respective layers is increased. Since it is sufficiently high, it is possible to form a favorable pattern as a photomask having a line roughness that is approximately linear and a pattern cross section that is approximately vertical.

Moreover, by using a film containing Ni as the etching stopper layer 12, the adhesion strength between the light shielding layer 13 containing Cr and the phase shift layer 11 containing Cr can be sufficiently increased.
Therefore, when the light shielding layer 13, the etching stopper layer 12 and the phase shift layer 11 are etched with a wet etching solution, the interface between the light shielding layer 13 and the etching stopper layer 12, or the interface between the etching stopper layer 12 and the phase shift layer 11 is used. Therefore, the CD accuracy of the formed light-shielding pattern 13b and phase shift pattern 11a can be increased, and the cross-sectional shape of the film can be made close to a good vertical shape for the photomask.

  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 two layers of a chromium main component layer and a chromium oxide main component layer as the light shielding layer 13 is formed with a total thickness of 100 nm to obtain a phase shift mask blank MB. It was.

  A resist pattern RP1 is formed on the phase shift mask blanks MB, and the light shielding layer 13 is etched through the resist pattern RP1 using a mixed etching solution of cerium diammonium nitrate and perchloric acid to form a light shielding pattern 13a. Further, the etching stopper layer 12 was etched using a mixed etching solution of nitric acid and perchloric acid to form an 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.

  Next, a resist pattern RP2 was formed, and the phase shift pattern 11a was side-etched using a mixed etching solution of cerium diammonium nitrate and perchloric acid through the resist pattern RP2 to form a phase shift pattern 11b. Next, the resist pattern RP2 is removed, and then the etching stopper pattern 12a is etched using a mixed etching solution of nitric acid and perchloric acid to form the etching stopper pattern 12b. Got.

  Using the thus obtained phase shift mask M, exposure is performed using exposure light having a composite wavelength of g-line, h-line, and i-line, the line width of the exposed pattern is measured, and the target line width (2. As a result of obtaining the deviation with respect to 5 μm), it was confirmed that it can be suppressed to about 10%. At the same time, it was confirmed that the contour visibility of the alignment mark AM was good. Thus, it was found that the phase shift mask M that can be manufactured with high mass productivity can be used for FPD.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to this, In the range which does not deviate from the meaning of invention, it can change suitably.

  MB ... phase shift mask blanks, S ... glass substrate (transparent substrate), 11 ... phase shift layer, 11a ... phase shift pattern, 12 ... etching stopper layer, 12a, 12b ... etching stopper pattern, 13 ... light shielding layer, 13a, 13b ... light-shielding pattern.

Claims (3)

A transparent substrate;
A phase shift layer mainly composed of Cr formed on the surface of the transparent substrate;
The main component is at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W, and Hf formed on the surface of the phase shift layer on the side away from the transparent substrate. An etching stopper layer to perform;
A light-shielding layer mainly composed of Cr formed on the etching stopper layer on the side away from the phase shift layer,
A phase shift region in which the opening width of the light shielding pattern formed in the light shielding layer is set wider than the opening width of the phase shift pattern formed in the phase shift layer;
A phase shift mask comprising: a light shielding region in which the opening width of the phase shift pattern formed in the phase shift layer and the opening width of the light shielding pattern formed in the light shielding layer are set equal to each other. . A transparent substrate;
A phase shift layer mainly composed of Cr formed on the surface of the transparent substrate;
The main component is at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W, and Hf formed on the surface of the phase shift layer on the side away from the transparent substrate. An etching stopper layer to perform;
A light-shielding layer mainly composed of Cr formed on the etching stopper layer on the side away from the phase shift layer,
A phase shift region in which an opening width of the light shielding pattern formed in the light shielding layer is set wider than an opening width of the phase shift pattern formed in the phase shift layer; and the phase shift pattern formed in the phase shift layer. A phase shift mask having a light-shielding region in which the opening width and the opening width of the light-shielding pattern formed in the light-shielding layer are set equal to each other,
Forming the phase shift layer, the etching stopper layer, and the light shielding layer on the transparent substrate;
Forming a first mask having a predetermined opening pattern on the light shielding layer;
A step of sequentially etching the light shielding layer and the etching stopper layer through the formed first mask to form a light shielding pattern and an etching stopper pattern;
Etching the phase shift layer through the first mask to form a phase shift pattern;
The light shielding pattern exposed at the surface of the light shielding pattern and the pattern opening is covered, and the etching stopper pattern and the phase shift pattern exposed at the pattern opening are not covered by the light shielding area but covered by the phase shift area. Forming a second mask having a predetermined opening pattern;
Etching the phase shift pattern through the formed second mask;
And a step of further etching the etching stopper pattern after removing the second mask.   3. The method of manufacturing a phase shift mask according to claim 2, wherein an etching solution containing nitric acid is used for etching the etching stopper layer.

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