JP2018205441A - Manufacturing method of phase shift mask, and phase shift mask - Google Patents

Abstract

To increase side etching amount.SOLUTION: There is provided a method for manufacturing a phase shift mask M having a phase shift layer 11 formed on a transparent substrate S and a light shading layer 13 mainly containing Cr, in which a light shading pattern 13a is positioned with retraction with respect to a line width of a phase shift pattern 11a by a plane view, having: a process for forming the phase shift layer and the light shading layer on a transparent substrate; a process for forming a mask PR1 having a prescribed opening pattern on the light shading layer on the light shading layer; a process for forming the light shading pattern by etching the light shading layer over the mask; and a process for forming the phase shift pattern by wet etching of the phase shift layer over the mask and sandwiching the light shading layer, and having a filming atmosphere containing nitrogen as a filming gas while the light shading layer is filmed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a phase shift mask manufacturing method and 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.
In the semiconductor phase shift mask described above, an edge-enhanced phase shift mask using an i-line single wavelength is used as shown in Patent Document 1, but for further miniaturization, Patent Document 2 As shown in FIG. 1, a semi-transmission type phase shift mask has been used in which the exposure wavelength is shortened to a single ArF wavelength.

Flat panel displays, on the other hand, need to be produced at high throughput in order to reduce costs, and patterning is performed by exposure with an exposure wavelength that is a composite wavelength of g-line, h-line, and i-line. It has been broken.
Recently, in order to form a high-definition screen even in the above flat panel display, the pattern profile has been further miniaturized, and instead of a photomask having a light shielding film patterned, which has been conventionally used, Patent Document 3 discloses. As shown, 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. 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, when the phase shift mask is viewed in plan, an edge-enhanced phase shift mask in which the light shielding pattern is retracted from the phase shift pattern is obtained.

  As shown in Patent Document 4, when manufacturing an edge-enhanced phase shift mask (halftone mask), the phase shift layer and the light shielding layer are continuously etched so that the light shielding layer is side-etched. Therefore, it is necessary to form an edge-enhanced phase shift mask in which the light shielding pattern recedes from the phase shift pattern.

JP-A-8-272071 JP 2006-78953 A JP 2011-13283 A JP 2013-134435 A

However, in the technique described in Patent Document 4, there is a possibility that the side etching speed of the light shielding layer is insufficient in the halftone mask serving as the phase shift mask, and the dimension that the light shielding pattern recedes from the phase shift pattern is predetermined. There was a problem that the width dimension could not be set. Alternatively, when the etching amount is increased while the side etching rate of the light shielding layer is insufficient, the etching time becomes too long, and there is a possibility that the uniformity of the line width such as the occurrence of a defect is deteriorated.
Therefore, there has been a demand to increase the side etching amount in the light shielding layer, thereby reducing the number of photolithography processes, reducing the manufacturing time, and reducing the manufacturing cost.
At the same time, it has been desired to prevent deterioration of film characteristics such as deterioration of line width uniformity and light shielding properties.

The present invention has been made in view of the above circumstances, and intends to achieve the following object.
1. It is possible to increase the etching rate of side etching in the light shielding layer.
2. Prevent deterioration of characteristics as a halftone mass.

  As shown in FIGS. 8A and 8B, 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 stacked 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. 8A and 8B 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. 8C corresponds to the transfer dimension set by the light intensity distribution in the single-layer phase shift pattern 120 as shown in FIG. 9C. In order to make it possible to form this transfer dimension more accurately, a light-shielding pattern 130 that can independently have a light intensity distribution shown in FIG. 10C is laminated at a position retracted from the edge of the phase shift pattern 120. ing. 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.

  In order to retract the light shielding pattern 130 from the edge of the phase shift pattern 120, the light shielding layer made of chromium is processed by side etching.

  The side etching rate of a general chromium film is about 0.05 μm to 0.15 μm / 10 sec as the pattern line width at both sides in the opening pattern width direction, and the target width dimension is reduced, that is, one side of the pattern opening In order to make 0.5 to 2.0 μm thinner, overetching time of 66 sec to 200 sec is required at the shortest, and 267 sec to 800 sec is required for the long time.

For example, when the line width (one side) to be thinned is 1.5 μm, an over-etching time of 200 sec to 600 sec is required.
Such a long over-etching time is not realistic because the occurrence of defects increases and the uniformity of the line width (pattern edges become gritty) is inferior. Therefore, the inventors of the present application decided to realize a chromium film having an extremely large side etching rate.

The method for producing a phase shift mask of the present invention includes a transparent substrate,
A phase shift layer formed on the surface of the transparent substrate;
A light-shielding layer mainly composed of Cr laminated on the phase shift layer,
A method of manufacturing a phase shift mask in which an edge of a light shielding pattern formed in the light shielding layer is disposed at a position retreated in plan view from an edge of a phase shift pattern formed in the phase shift layer,
Forming the phase shift layer and the light shielding layer on the transparent substrate;
Forming a mask having a predetermined opening pattern on the light shielding layer;
Etching the light shielding layer through the formed mask to form a light shielding pattern;
Wet etching the phase shift layer over the mask to form a phase shift pattern, and side etching the light shielding layer;
Have
When the light shielding layer is formed, the above problem is solved by having a film forming atmosphere containing nitrogen as a film forming gas.
In the present invention, it is more preferable not to contain methane as a film forming gas for forming the light shielding layer.
In the present invention, the light shielding layer can be formed as a plurality of layers.
In the present invention, when wet-etching the light shielding layer, means using an etching solution containing ceric ammonium nitrate can be employed.
The phase shift mask of the present invention is a phase shift mask manufactured by any one of the manufacturing methods described above, wherein the wet etching side etching amount in the light shielding layer is formed by a film forming gas containing methane. It can be set to be larger than the filmed light shielding layer.
Further, it is preferable that the side etching amount of the wet etching in the light shielding layer is set to an order of magnitude larger than that of the light shielding layer formed by a film forming gas containing methane.
In the present invention, the light shielding layer may contain 30% or more of nitrogen.
In the present invention, the light shielding layer may contain 40% or more of nitrogen.

The method for producing a phase shift mask of the present invention includes a transparent substrate,
A phase shift layer formed on the surface of the transparent substrate;
A light-shielding layer mainly composed of Cr laminated on the phase shift layer,
A method of manufacturing a phase shift mask in which an edge of a light shielding pattern formed in the light shielding layer is disposed at a position retreated in plan view from an edge of a phase shift pattern formed in the phase shift layer,
Forming the phase shift layer and the light shielding layer on the transparent substrate;
Forming a mask having a predetermined opening pattern on the light shielding layer;
Etching the light shielding layer through the formed mask to form a light shielding pattern;
Wet etching the phase shift layer over the mask to form a phase shift pattern, and side etching the light shielding layer;
Have
When forming the light shielding layer, a light shielding layer having an amount of side etching one order of magnitude larger than that of the conventional film can be formed by having a film forming atmosphere containing nitrogen as a film forming gas.
As a result, the time for etching the phase shift layer and the light shielding layer is shortened, and the halftone mask in which the light shielding pattern is retracted from the phase shift pattern by a predetermined shape is manufactured while preventing the film characteristics from deteriorating. It becomes possible.

  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, by not containing methane as a film forming gas for forming the light shielding layer, it is possible to form a light shielding layer whose side etching amount is one digit larger than the conventional one.

  In the present invention, by forming the light shielding layer as a plurality of layers, it is possible to obtain a phase shift mask having a film property comparable to that of the prior art. Specifically, it has sufficient optical density (OD (Optical Density) 2.4 or more) and film surface reflectance 10 ± 5% as adhesion and optical characteristics with a glass substrate (transparent substrate). Is possible. Further, since the etching time is shortened, it is possible to prevent the pattern edge from being jagged even if the pattern width is greatly reduced by etching.

  In the present invention, when the light shielding layer is wet-etched, by using an etching solution containing ceric ammonium nitrate, a side etching amount that is an order of magnitude larger than that of the conventional light shielding layer can be realized.

  The phase shift mask of the present invention is a phase shift mask manufactured by any one of the manufacturing methods described above, wherein the wet etching side etching amount in the light shielding layer is formed by a film forming gas containing methane. By setting the thickness to be larger than that of the formed light shielding layer, a side etching amount that is an order of magnitude larger than that of the conventional light shielding layer can be realized.

  Further, the wet etching side etching amount in the light shielding layer can be set to an order of magnitude larger than that of the light shielding layer formed by the film forming gas containing methane.

  In the present invention, the above-described side etching amount can be realized when the light shielding layer contains 30% or more of nitrogen.

  In the present invention, when the light shielding layer contains 40% or more of nitrogen, the above side etching amount can be realized.

  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.

  Alternatively, in the present invention, the phase shift layer may contain at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W, and Hf as a main component.

  In the present invention, the ratio of the etching rate in the phase shift layer between the transparent substrate side and the etching stopper layer side is set, and the etching processing time is controlled to thereby adjust the thickness dimension of the phase shift layer. The ratio of the width dimensions of the side surfaces in plan view can be set within a predetermined range.

  According to the present invention, a light-shielding layer having a side etching amount that is an order of magnitude larger than that of the conventional film is realized while maintaining the same film characteristics as the conventional film, and a desired side etch amount is ensured without deteriorating the film characteristics. However, the time required for the etching process can be reduced, and the manufacturing cost can be reduced.

It is process drawing which shows 1st Embodiment of the manufacturing method of the phase shift mask which concerns on this invention. It is sectional drawing which shows the process in 1st Embodiment of the manufacturing method of the phase shift mask which concerns on this invention. It is a graph which shows the amount of side etching of the light shielding layer in 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 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 schematically showing a method of manufacturing a phase shift mask in the present embodiment. In the figure, reference numeral MB denotes 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 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 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 phase shift layer 11 and the etching stopper layer 12 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 light shielding layer 13 is mainly composed of Cr, and specifically includes Cr and nitrogen. Furthermore, the light shielding layer 13 may have a composition different in the thickness direction. In this case, as the light shielding layer 13, Cr alone, Cr oxide, nitride, carbide, oxynitride, carbonitride, and oxycarbonitride One or two or more selected from a product can be laminated.
The light shielding layer 13 is formed with a thickness (for example, 80 nm to 200 nm) that provides predetermined optical characteristics.

  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 first has a phase shift layer 11 containing Ni as a main component and Ni on a glass substrate S using a DC sputtering method or the like. An etching stopper layer 12 having a main component is sequentially formed.

Next, a light shielding layer 13 containing Cr as a main component is formed on the etching stopper layer 12.
At this time, sputtering is performed in a state containing argon and nitrogen (N ₂ ) as a sputtering gas by DC sputtering using chromium as a target as a film forming condition. At this time, it is preferable to reduce the gas containing carbon such as methane as much as possible.

  Thereby, the light shielding layer 13 is formed into a film containing nitrogen in a rich state, and has a high side etch rate at the time of wet etching as a subsequent process.

  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.

  Subsequently, as shown in FIG. 1C, the photoresist layer PR1a is exposed and developed as shown in FIG. 1D, whereby a resist pattern PR1 is formed on the light shielding layer 13. . The resist pattern PR1 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, in the phase shift region PS, a shape having an opening width corresponding to the opening width dimension of the phase shift pattern to be formed is set.

Next, as shown in FIG. 1E, the light shielding layer 13 is wet etched using the first etching solution over the resist pattern PR1. 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 corresponding to the resist pattern PR1. Furthermore, as shown in FIG. 1 (f), a descum process is performed. Note that the descum treatment means removal of residues during development by performing O ₂ plasma irradiation treatment. By performing this descum treatment, the wettability of the film surface is changed to hydrophilic, and etching can be performed uniformly in the subsequent etching process.

  Next, as shown in FIG. 1G, the etching stopper layer 12 is wet etched using the second etching solution over the resist pattern PR1. 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 an etching stopper pattern 12a. The etching stopper pattern 12a has a shape having an opening width corresponding to the opening width dimension of the light shielding pattern 13a and the resist pattern PR1.

    Next, as shown in FIG. 1H, the phase shift layer 11 is wet etched using the first etchant over the resist pattern PR1, that is, without removing the resist pattern PR1. 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 a predetermined opening width dimension. At the same time, since the light shielding pattern 13a is formed to have a high side etch amount, it is side etched further than the phase shift pattern 11a, and has a shape having an opening width larger than the opening width dimension of the phase shift pattern 11a. A light shielding pattern 13b is formed.

  At this time, since the light shielding layer 13 or the light shielding pattern 13a has a high side etch amount, the etching process time can be shortened and damage to the phase shift layer 11 or the phase shift pattern 11a can be reduced.

  Next, as shown in FIG. 1 (j), 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 PR1 is removed as the stopper pattern 12b. Since a known resist stripping solution can be used for removing the resist pattern PR1, a detailed description thereof is omitted here. The removal of the resist pattern is satisfactory even after the light shielding pattern 13b is formed.

  As described above, as shown in FIG. 1 (k), 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.

  As shown in FIG. 2, in the phase shift pattern 11a, the thickness T11 in the uniform thickness region B1a is equal to the thickness of the phase shift pattern 11a other than the boundary portion B1, and this thickness is The value corresponds to the thickness Tg (for example, 145 nm) at which the corresponding light intensity 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.

In FIG. 1, the side surfaces of the phase shift pattern 11 a and the light shielding pattern 13 b are shown to be formed vertically, but actually, as shown in FIG. 2, the unevenness caused by the difference in etching rate is present. Has occurred.
FIG. 2 shows a state in which the etching of the phase shift layer 11 is finished and the etching stopper pattern 12a is not peeled off.

  According to the present embodiment, the width of the phase shift pattern 11a exposed to the outside of the light shielding pattern 13b is the etching rate in the thickness direction of the phase shift layer 11 when the phase shift layer 11 is wet etched, and the light shielding at that time. It can be set by the difference between the etching rate in the horizontal direction of the pattern 13b and the etching state of the light shielding pattern 13b at that time.

  Here, the lateral etching rate of the light shielding pattern 13b is such that when the light shielding layer 13 is formed on the surface of the etching stopper layer 12, nitrogen is contained as an atmospheric gas, and the film forming gas composition increases as the film thickness increases. The side etching rate can be set by adjusting the film characteristics such as changing. In particular, it is possible to set the side etching rate to be increased by reducing the carbon in the light shielding layer 13 so as to hardly contain it and increasing the amount of nitrogen contained in the light shielding layer 13. is there.

  In particular, as will be described later, in order to increase the side etching rate in the light shielding layer 13, it is preferable to contain 30% or more of nitrogen, and more preferably 40% or more of nitrogen. Here, the ratio of nitrogen contained can be expressed as a percentage of elemental analysis by Auger electron spectroscopy (AES).

  Further, the etching rate in the thickness direction of the light shielding pattern 13b and the direction intersecting with the thickness 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, and this can be taken into consideration. .

  Here, as shown in FIG. 2, with respect to the width dimension PR1 of the resist layer PR1, the width dimension B2a (the light shielding pattern 13b side) between the resist PR1 side and the etching stopper layer 12b side in plan view in the light shielding pattern 13b. The inclination of the eye), the width dimension B1a of the uniform thickness region of the phase shift pattern 11a, the width dimension B12 in which the etching stopper layer 12a and the phase shift pattern 11a are separated in plan view, and the thickness of the phase shift pattern 11a are reduced. The film forming conditions and etching conditions of each layer are set to desired states so that the dimensions of the sagging width B1b (tilt state of the side surface of the phase shift pattern 11a) become predetermined values.

  At this time, the width B2a of the light shielding pattern 13b becomes a negative value, that is, the light shielding pattern 13b is in an inclined state in which the etching stopper layer 12b side is located on the substrate exposed region C side rather than the resist PR1 side in plan view. In a plan view, it is possible to select an inclined state in which the resist PR1 side is positioned on the substrate exposed region C side rather than the etching stopper layer 12b side.

  Further, the etching rate of the light shielding pattern 13 a is affected by the composition state in the thickness direction of 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 oxynitride and a layer mainly composed of chromium oxynitride carbide, the nitrogen component of the layer mainly composed of chromium oxynitride If the ratio is increased, the etching rate can be increased. On the other hand, if the ratio of the carbon component of the layer mainly composed of chromium oxynitride carbide is increased, the etching rate can be decreased. The etching amount of the light shielding pattern 13a can be set within a range of 200 nm to 1000 nm, for example.

  At this time, when forming a layer mainly composed of chromium oxynitride in the light shielding layer 13, the film formation conditions are further changed between the first half and the second half to form two layers having different film configurations, and chromium oxynitride carbide is mainly used. It can also be configured by a three-layer film with a component layer.

Alternatively, it can be formed of two layers of films having chromium oxynitride as a main component and different film configurations.
Furthermore, it can also be comprised by the film | membrane of 2 layers from which chromium oxynitride carbide carbide is a main component and from which a film | membrane structure differs.

  At this time, it is preferable to set the gas pressure, the applied voltage, and the like as conditions other than the atmospheric gas as the film forming conditions. In particular, in order to improve the adhesion between the light shielding layer 13 and the etch stopper layer 12, it is possible to set a condition that the substrate temperature during film formation is 120 ° C. or higher.

  On the other hand, the etching rate in the thickness direction of the phase shift pattern 11b is affected by the composition of the phase shift layer 11 and the interface state between the etching stopper layer 12 and the phase shift layer 11, so that the side etching rate of the light shielding layer 13 is increased. Is set to a predetermined value.

  The etching rate in the thickness direction of the phase shift pattern 11b is adjusted when the phase shift layer 11 is formed on the surface of the glass substrate S, such as increasing the grain size of the chromium grains 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 etching stopper layer and the phase shift layer, and the etching stopper layer can be set by being 10% or more smaller. Furthermore, if it is smaller than 20%, further effects can be obtained.

Furthermore, the etching rate in the thickness direction of the phase shift pattern 11b 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 controlling the etching processing time in the phase shift layer 11 with the etching rate set in this manner, the phase shift which is the inclined state of the slope formed in the phase shift pattern 11a as shown by B1b in FIG. The sagging width B1b of the pattern 11a can be controlled, that is, the sagging width (corresponding to B1b) of the phase shift pattern 11a can be reduced and an edge can be set, and vice versa.

  By setting the side etching rate in the light shielding layer 13 with respect to the etching rate in the phase shift layer 11 as described above, the etching amount of the light shielding layer 13 changes in the substrate in-plane direction (lateral direction). When the etching process time is increased, the rate of increase in the etching amount of the light shielding layer 13 is larger than the rate of increase in the etching amount of the phase shift layer 11. The width dimension at which the light shielding pattern 13b alternates with respect to the shift pattern 11a, that is, the width dimension at which the phase shift pattern 11a is exposed with respect to the light shielding pattern 13b can be changed.

  At this time, the width direction position of the upper end of the phase shift pattern 11a with respect to the end portion of the etching stopper pattern 12a and the width direction position of the lower end of the phase shift pattern 11a also change. Therefore, the etching processing time is set in consideration of these.

  Thereby, the width dimension of the phase shift pattern 11a in plan view with respect to the light shielding pattern 13b indicated by B1a in FIG. 2 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. By forming a resist pattern PR1 on the light shielding layer 13 of this phase shift mask blank MB, and controlling the side etching rate of the light shielding layer 13, the thickness direction etching rate of the other layers, and the wet etching processing time in each layer, An edge-enhanced phase shift mask M can be manufactured. Therefore, the phase shift mask M with high definition and high visibility can be manufactured in a short time.

  The light shielding layer 13 is composed of at least one selected from Cr oxide, nitride, carbide, oxynitride, carbonitride, and oxycarbonitride, and exhibits a sufficient light shielding effect. It has a film thickness. By having such a film thickness that sufficiently exhibits the light shielding effect, the etching time of the light shielding layer 13 becomes longer than the etching time of the phase shift layer 11, but the side etching rate of the light shielding layer 13 is sufficiently high. Since it is large, the etching amount is controlled by setting the etching rate of the light shielding layer 13 and the phase shift layer 11 within a suitable range, and the line roughness of the phase shift layer 11 and the light shielding layer 13 is approximately linear, In addition, it is possible to form a good pattern as a photomask in which the cross section of these patterns is substantially vertical, to improve the CD accuracy of the formed light shielding pattern 13b and phase shift pattern 11a, and to change the cross sectional shape of the film. A shape close to vertical which is favorable for a photomask can be obtained.

  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 the wet etching liquid, 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.

  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.

  In the above embodiment, the etching rate of the phase shift layer 11 is set by controlling the grain size. However, it may be set by other factors such as film forming conditions and film composition. .

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.
Even when these layer structures are adopted, it is possible to manufacture the phase shift mask in a short time by controlling the nitrogen and carbon contents to control the side etching amount of the light shielding layer 13.

In the present embodiment, the phase shift layer 11 can be mainly composed of at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W, and Hf. In this case, the etching stopper layer 12 may not be provided. In particular, the phase shift layer 11 can be made of molybdenum silicide (MoSi _x ).

  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.
At this time, the light blocking layer 13 is to contain nitrogen and a condition containing nitrogen gas (N ₂₎ as a sputtering gas.

  A resist pattern PR1 is formed on the phase shift mask blank MB, and a light shielding pattern 13a is formed by etching the light shielding layer 13 using a mixed etching solution of cerium diammonium nitrate and perchloric acid over the resist pattern PR1. 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. Subsequently, the phase shift layer 11 was etched using a mixed etching solution of cerium diammonium nitrate and perchloric acid to form the phase shift pattern 11a, whereby an edge-enhanced phase shift mask M was obtained.

The weight ratio of the etchant is
Cerium nitrate secondary ammonium: perchloric acid: pure water = 13-18: 3-5: 77-84
It was.
Further, Experimental Examples 1 to 4 were manufactured by changing the sputtering gas when forming the light shielding layer 13.
In these experimental examples, the sputtering gas, gas pressure, and applied voltage are listed in Table 1 as the layer configuration of the light shielding film 13 and the conditions for forming the light shielding layer 13.

In the above manufacturing process, a plurality of phase shift masks were manufactured by changing the etching time of the light shielding layer 13.
Further, in these experimental examples, the side etching rate with respect to the etching time of the light shielding layer 13 and the optical density as the light shielding layer were measured.

Here, during LR etching, the light shielding layer 13a formed in the horizontal direction (substrate) when the light shielding layer 13 is wet etched using the first etching solution over the resist pattern PR1 shown in FIG. Side etching in the in-plane direction),
In the PSM etching, the light shielding layer 13b is formed in the horizontal direction (in-plane of the substrate) when the phase shift layer 11 is wet etched using the first etching solution over the resist pattern PR1 shown in FIG. Direction).
The optical density is O.D. D. (Optical Density) = 2.4 or more, and film surface reflectance was 10 ± 5%.

These results are shown in Table 1 and FIG.
In FIG. 3, the over-etching time indicates an etching time that exceeds the reference etching time.

In these experimental examples, the percentage of elemental analysis by Auger electron spectroscopy (AES) of the light shielding layer 13 was analyzed using an Auger analyzer SAM680 manufactured by ULVAC-PHI.
The results are shown in Table 2.

Further, in each experimental example, the over-etching time is 120 sec, and the experimental example 1 is shown in FIG. 4 and the experimental example 4 is shown in FIG. 5 as SEM photographs before removing the etch stopper layer. In FIG. 4, it can be seen that the light-shielding film pattern is thinned (retreated) by 0.385 μm side etching from the edge of the phase shift pattern across the etch stopper layer. In FIG. 5, it can be seen that the light-shielding film pattern is narrowed (retreated) by the 2.98 μm side etch from the phase shift pattern edge with the etch stopper layer interposed therebetween.
Similarly, Experimental Example 2 is shown in FIG. Further, FIG. 7 shows an SEM photograph after removing the etch stopper layer. In FIG. 6, it can be seen that the light shielding film pattern is thinned (retreated) by the 0.679 μm side etching from the phase shift pattern edge with the etch stopper layer interposed therebetween.

  From these results, the side etching amount is increased by increasing the nitrogen content in the light shielding layer with the sputtering gas containing nitrogen, and the etching rate in Experimental Example 4 is increased to about 10 times the etching rate in Experimental Example 1. It can be seen that it is possible to increase.

  On the other hand, the side etch rate of the chromium film in Experimental Example 1 formed by the manufacturing method as a sputtering gas containing methane is about 0.01 μm / 10 sec, and the chromium film is etched by 1.0 μm side etching. 1,000 seconds (a little less than 17 minutes), the occurrence of defects is expected, and it is understood that this is not a practical process.

  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. Can be mentioned.

MB ... Phase shift mask blanks M ... Phase shift mask S ... Glass substrate (transparent substrate)
PR1a ... Photoresist layer PR1b ... Exposure and development region PR1 ... Resist pattern 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 (8)

A transparent substrate;
A phase shift layer formed on the surface of the transparent substrate;
A light-shielding layer mainly composed of Cr laminated on the phase shift layer,
A method of manufacturing a phase shift mask in which an edge of a light shielding pattern formed in the light shielding layer is disposed at a position retreated in plan view from an edge of a phase shift pattern formed in the phase shift layer,
Forming the phase shift layer and the light shielding layer on the transparent substrate;
Forming a mask having a predetermined opening pattern on the light shielding layer;
Etching the light shielding layer through the formed mask to form a light shielding pattern;
Wet etching the phase shift layer over the mask to form a phase shift pattern, and side etching the light shielding layer;
Have
A method of manufacturing a phase shift mask, comprising forming a film formation atmosphere containing nitrogen as a film formation gas when forming the light shielding layer.   The method for producing a phase shift mask according to claim 1, wherein methane is not contained as a film forming gas for forming the light shielding layer.   The method of manufacturing a phase shift mask according to claim 1, wherein the light shielding layer is formed as a plurality of layers.   4. The method of manufacturing a phase shift mask according to claim 1, wherein an etchant containing ceric ammonium nitrate is used when the light shielding layer is wet-etched. 5.   5. The phase shift mask manufactured by the manufacturing method according to claim 1, wherein a side etching amount of wet etching in the light shielding layer is a light shielding layer formed by a film forming gas containing methane. A phase shift mask characterized by being set to be larger than that.   6. The phase shift mask according to claim 5, wherein a side etching amount of wet etching in the light shielding layer is set to be one digit larger than that of the light shielding layer formed by a film forming gas containing methane.   The phase shift mask according to claim 5 or 6, wherein the light shielding layer contains 30% or more of nitrogen.   The phase shift mask according to claim 7, wherein the light shielding layer contains 40% or more of nitrogen.