KR20140038536A - Phase-shifting mask blank, and phase-shifting mask and process for producing same - Google Patents

Abstract

It provides a phase shift mask blank suitable for producing edge-enhanced phase shift masks with high yield. The phase shift mask blank MB of the present invention comprises a glass substrate S, a phase shift layer 11 mainly composed of Cr formed on the surface of the glass substrate, and a direction from the glass substrate toward the phase shift layer. And an etching stopper layer 12 containing, as a main component, at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W, and Hf formed on the phase shift layer; The light shielding layer 13 which has Cr as a main component is formed on the etching stopper layer.

Description

Phase shift mask blank, phase shift mask and manufacturing method thereof {PHASE-SHIFTING MASK BLANK, AND PHASE-SHIFTING MASK AND PROCESS FOR PRODUCING SAME}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a phase shift mask blank, a phase shift mask, and a method for producing the same, and more particularly, to one suitable for the manufacture of a flat panel display (hereinafter referred to as "FPD").

In the process of manufacturing a semiconductor device or FPD, a phase shift mask is used to expose and transfer a fine pattern to a resist film formed on a substrate made of silicon, glass, or the like. Since the glass substrate for FPD is larger than the silicon substrate for semiconductor, exposure light of the compound wavelength of g line | wire, h line | wire, and i line | wire is used in order to expose with sufficient exposure light quantity with respect to the board | substrate for FPD. When using such exposure light, the edge enhancement type phase shift mask is conventionally used (for example, refer patent document 1).

In the conventional example, however, a light shielding layer is formed on a transparent substrate, the light shielding layer is etched and patterned, a phase shift layer is formed to cover the patterned light shielding layer, and the phase shift layer is etched and patterned. The phase shift mask is manufactured. Thus, when film-forming and patterning are performed alternately, the conveyance time and processing waiting time between apparatuses will become long, and production efficiency will fall remarkably. In addition, over a single mask having a predetermined opening pattern, the phase shift layer and the light shielding layer cannot be etched continuously, and the mask (resist pattern) needs to be formed twice, thereby increasing the number of manufacturing steps. Therefore, there exists a problem that a phase shift mask cannot be manufactured with high mass productivity.

Patent Document 1: Japanese Patent Application Laid-Open No. 2011-13283

SUMMARY OF THE INVENTION In view of the above, the present invention provides a phase shift mask blank suitable for producing an edge-enhanced phase shift mask with high yield, a phase shift mask manufactured from the phase shift mask blank, and a method of manufacturing the same. It is a task.

In order to solve the said subject, the phase shift mask blank of this invention is a transparent substrate, the phase shift layer which has Cr as a main component formed in the transparent substrate surface, and the direction toward a phase shift layer from a transparent substrate upwards. And 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 phase shift layer, and an etching stopper layer. And a light shielding layer containing Cr as a main component. In addition, in this invention, having Cr as a main component means what consists of any 1 type chosen from oxides, nitrides, carbides, oxynitrides, carbonitrides and oxynitrides of Cr and Cr.

In addition, the phase shift mask of the present invention manufactured from the phase shift mask blank may sequentially etch the light blocking layer and the etching stopper layer over a single mask having a predetermined opening pattern to form a light shielding pattern and an etching stopper pattern. And etching the phase shift layer over the mask to form a phase shift pattern, wherein the opening width of the light shielding pattern is made wider than the opening width of the phase shift pattern.

Moreover, the manufacturing method of the phase shift mask of this invention which manufactures a phase shift mask from the said phase shift mask blanks includes the process of forming the single mask which has a predetermined | prescribed opening pattern on a light shielding layer, and the said mask over this formed mask. Etching the light shielding layer and the etching stopper layer sequentially to form a light shielding pattern and an etching stopper pattern, etching the phase shift layer over the mask to form a phase shift pattern, and further etching the etching stopper pattern Characterized in that it comprises a step to. In this case, it is preferable to use an etching solution containing acetic acid for etching the etching stopper layer.

According to the above, a case in which a resist pattern is formed as a single mask having a predetermined opening pattern on the light shielding layer of the phase shift mask blank will be described as an example. The light shielding pattern having a predetermined width is formed by etching the light shielding layer over the resist pattern. Is formed. In addition, an etching stopper pattern is formed by etching the etching stopper layer over the resist pattern. At this time, although the side surface of the light shielding pattern is exposed, since the light shielding pattern is comprised from the material different from an etching stopper pattern, it is not etched and the light shielding pattern and an etching stopper pattern become the same width. Next, by etching the phase shift layer over the resist pattern, a phase shift pattern having the same width as the etching stopper pattern is formed. At this time, the light shielding pattern made of the same Cr-based material as the phase shift pattern is also etched, so that the opening width of the light shielding pattern is wider than the width of the phase shift pattern. Finally, by etching the etching stopper pattern further, the light shielding pattern and the etching stopper pattern become the same width. By passing through the above process, the edge shift type phase shift mask of which the opening width of a light shielding pattern is larger than the opening width of a phase shift pattern is obtained. In addition, the resist pattern can be removed at any timing as long as after the formation of the phase shift pattern. As described above, since the phase shift mask can be manufactured only by patterning the phase shift mask blank over a single mask, the film can be manufactured more efficiently than in the case of performing film formation and patterning alternately as in the conventional example. Since the number of manufacturing processes can be reduced compared with the example, a phase shift mask can be manufactured with high mass productivity.

In the present invention, the phase shift layer containing Cr as a main component is composed of any one selected from oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxynitrides of Cr, and the film exhibits sufficient phase shift effect. It is set to the thickness. In order to have a film thickness in which such a phase shift effect is sufficiently exhibited, although the etching time becomes longer than 1 times with respect to the etching time of a light shielding layer, since the adhesive strength between each layer is high enough, a line roughness is generally linear form In addition, it becomes possible to form a good pattern as a photo mask in which a pattern cross section becomes substantially vertical.

Moreover, by using the film containing Ni as an etching stopper layer, the adhesive strength with the light shielding film containing Cr and the phase shift layer containing Cr can fully be raised. For this reason, when etching a light shielding layer, an etching stopper layer, and a phase shift layer with a wet etching liquid, etching liquid does not penetrate deeply from the interface of a light shielding layer and an etching stopper layer, or the interface of an etching stopper layer and a phase shift layer. The CD accuracy of the formed light shielding pattern and the phase shift pattern can be improved, and the cross-sectional shape of the film can be made into a shape close to vertical in the case of a photo mask.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows the phase shift mask blank of embodiment of this invention.
FIG.2 (a)-(e) is process drawing for demonstrating the manufacturing method of the phase shift mask which manufactures a phase shift mask from the phase shift mask shown in FIG.

Referring to Fig. 1, MB is a phase shift mask blank of the embodiment of the present invention. The phase shift mask blank MB includes a transparent substrate S, a phase shift layer 11 formed on the transparent substrate S, an etching stopper layer 12 formed on the phase shift layer 11, The light blocking layer 13 formed on the etching stopper layer 12 is comprised.

As the transparent substrate S, a glass substrate can be used. The phase shift layer 11 and the light shielding layer 13 have Cr as a main component, specifically, one selected from Cr alone and oxides, nitrides, carbides, oxynitrides, carbonitrides and oxynitrides of Cr. In addition, it can also be laminated | stacked and comprised 2 or more types selected from these. The phase shift layer 11 has a thickness capable of having a phase difference of 180 ° with respect to light (for example, i-line having a wavelength of 365 nm) in any wavelength region of 300 nm or more and 500 nm or less (for example, 90-170 nm). The light shielding layer 13 is formed in the thickness (for example, 80 nm-200 nm) from which predetermined optical characteristic is obtained. As the etching stopper layer 12, those having a main component of at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W, and Hf can be used. For example, Ni-Ti -Nb-Mo film can be used. These phase shift layer 11, etching stopper layer 12, and light shielding layer 13 can be formed by a sputtering method, an electron beam vapor deposition method, a laser vapor deposition method, an ALD method, etc., for example.

The phase shift mask blank MB is, for example, a phase shift layer 11 having Cr as a main component and an etching stopper layer 12 having Ni as a main component on the glass substrate S by using a DC sputtering method. ) And a light shielding layer 13 containing Cr as a main component in this order. Hereinafter, the manufacturing method of the phase shift mask which manufactures the phase shift mask M from the said phase shift mask blank MB is demonstrated.

As shown in Fig. 2A, on the light shielding layer 13, which is the uppermost layer of the phase shift mask blank MB, the resist pattern RP is formed as a single mask having a predetermined opening by using lithography technique. Form. Next, as shown in FIG.2 (b), the light shielding layer 13 is wet-etched using this 1st etching liquid over this resist pattern RP. As the first etching solution, an etching solution containing cerium acetate diammonium can be used. For example, it is preferable to use cerium acetate diammonium containing an acid such as acetic acid or perchloric acid. Here, since the etching stopper layer 12 has high tolerance with respect to a 1st etching liquid, only the light shielding layer 13 is patterned and the light shielding pattern 13a is formed. Next, the etching stopper layer 12 is wet-etched using the second etching liquid over the resist pattern RP. As the second etching solution, one obtained by adding at least one selected from acetic acid, perchloric acid, 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 tolerance with respect to a 2nd etching liquid, only the etching stopper layer 12 is patterned and the etching stopper pattern 12a is formed.

Next, as shown in FIG.2 (c), the phase shift layer 11 is wet-etched using the said 1st etching liquid over the said resist pattern RP. Here, since the light shielding pattern 13a is made of the same Cr-based material as the phase shift layer 11, and the side surface of the light shielding pattern 13a is exposed, the phase shift layer 11 is patterned to give the phase shift pattern 11a. ) Is formed and the light shielding pattern 13a is also etched. As a result, the opening width d2 of the light shielding pattern 13a becomes wider than the opening width d1 of the phase shift pattern 11a.

As shown in Fig. 2 (d), the etching stopper pattern 12a is further wet-etched using the second etching solution. Thereby, the opening width of the etching stopper pattern 12b becomes the same as the opening width d2 of the light shielding pattern 13b.

Finally, when the resist pattern RP is removed, as shown in FIG. 2E, the light shielding pattern 13b (and the etching stopper pattern 12b) is larger than the opening width d1 of the phase shift pattern 11a. An edge emphasized phase shift mask M having a wide aperture width d2 is obtained. Since the well-known resist stripping liquid can be used for removal of the resist pattern RP, detailed description is abbreviate | omitted here.

In addition, 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 13a when the phase shift layer 11 is wet etched. . Here, the etching rate of this light shielding pattern 13a is influenced by the composition of the light shielding layer 13 and the interface state of the etching stopper layer 12 and the light shielding layer 13. For example, in the case where the light shielding layer 13 is composed of two layers of a film composed mainly of chromium and a layer composed mainly of chromium oxide, when the ratio of the chromium component of the layer composed mainly of chromium is increased, While the etching rate can be increased, a lower chromium component ratio can reduce the etching rate. As an etching amount of the light shielding pattern 13a, it can set in the range of 200 nm-1000 nm, for example.

According to the said embodiment, the phase shift layer 11, the etching stopper layer 12, and the light shielding layer 13 were laminated | stacked in this order on the transparent substrate S, and the phase shift mask blank MB was comprised. The resist pattern RP is formed on the light shielding layer 13 of the phase shift mask blank MB, and each layer is wet etched through the resist pattern RP to thereby form an edge-enhanced phase shift mask M. It can manufacture. Therefore, since the number of manufacturing processes can be reduced and production efficiency can be improved compared with the conventional example which repeats film-forming and etching, the phase shift mask M can be manufactured with high mass productivity.

The phase shift layer 11 is composed of any one selected from oxides of oxides, nitrides, carbides, oxynitrides, carbides, and oxynitrides, and has a film thickness in which the phase shift effect is sufficiently exhibited. In order to have a film thickness in which such a phase shift effect is sufficiently exhibited, although the etching time becomes longer than 1 times with respect to the etching time of the light shielding layer 13, since the adhesive strength between each layer is sufficiently high, the line roughness becomes It becomes possible to form a pattern favorable as a photomask which is generally linear and whose pattern cross section becomes substantially vertical.

Moreover, by using the film containing Ni as the etching stopper layer 12, the adhesion strength with the light shielding layer 13 containing Cr and the phase shift layer 11 containing Cr can fully be raised. For this reason, when etching the light shielding layer 13, the etching stopper layer 12, and the phase shift layer 11 with a wet etching liquid, the interface of the light shielding layer 13 and the etching stopper layer 12, and the etching stopper layer ( Since the etching liquid does not penetrate deeply from the interface of 12 and the phase shift layer 11, the CD precision of the light shielding pattern 13b and the phase shift pattern 11a which are formed can be improved, and the cross-sectional shape of a film can be made into the photomask. In this case, a good shape close to the vertical can be obtained.

In order to confirm the effect, the following experiment was conducted. That is, on the glass substrate S, the chromium oxynitride carbonized film which is the phase shift layer 11 is formed into a film by thickness of 120 nm by sputtering method, and Ni-Ti-Nb-Mo which is the etching stopper layer 12 is carried out. A film was formed to a thickness of 30 nm, and 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 was formed at a total thickness of 100 nm to form a phase shift mask blank (MB). Got it. A resist pattern RP is formed on the phase shift mask blank MB, and the light shielding layer 13 is etched by using a mixed etching solution of cerium diammonium acetate and perchloric acid over the resist pattern RP. (13a) was formed, and the etching stopper layer 12 was etched using the mixed etching liquid of acetic acid and perchloric acid, and the etching stopper pattern 12a was formed. Next, the phase shift layer 11 is etched using a mixed etching solution of cerium diammonium acetate and perchloric acid over the resist pattern RP to form a phase shift pattern 11a, and simultaneously, the light shielding pattern 13a is formed. Side etching was performed to form the light shielding pattern 13b. Next, the etching stopper pattern 12a is etched using the mixed etching solution of acetic acid and perchloric acid to form the etching stopper pattern 12b, and the resist pattern RP is removed to thereby remove the edge-enhanced phase shift mask M. FIG. ) Using the phase shift mask M obtained in this way, exposure was performed using exposure light of a compound wavelength of g line, h line and i line, the line width of the exposed pattern was measured, and the target line width (2.5 μm) was measured. As a result of the difference, it was confirmed that it can be suppressed to about 10%. By this, it turned out that the phase shift mask M which can be manufactured with high mass productivity can be used for FPD.

The present invention is not limited to the above embodiments. For example, in the above embodiment, the case where the resist pattern RP is removed after the etching stopper pattern 12 is formed has been described. However, the etching may be performed at any timing as long as the phase shift layer 11 is after etching. .

MB: phase shift mask blank S: glass substrate (transparent substrate)
11: Phase Shift Layer 11a: Phase Shift Pattern
12: etching stopper layer 12a, 12b: etching stopper pattern
13 shading layer 13a, 13b shading pattern

Claims (4)

A transparent substrate,
A phase shift layer composed mainly of Cr formed on the surface of the transparent substrate,
At least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W, and Hf formed on the phase shift layer with the direction from the transparent substrate toward the phase shift layer upward. An etching stopper layer containing as a main component,
A phase shift mask blank, provided with a light shielding layer containing Cr as a main component, formed on an etching stopper layer. As a phase shift mask manufactured from the phase shift mask blank of Claim 1,
Sequentially etching the light blocking layer and the etching stopper layer through a single mask having a predetermined opening pattern to form a light blocking pattern and an etching stopper pattern, and etching the phase shift layer over the mask to form a phase shift pattern, A phase shift mask comprising an opening width of a light shielding pattern wider than an opening width of the phase shift pattern. As a method of manufacturing a phase shift mask from the phase shift mask blank of claim 1,
Forming a single mask having a predetermined opening pattern on the light shielding layer,
Etching the light shielding layer and the etching stopper layer sequentially through the formed mask to form a light shielding pattern and an etching stopper pattern;
Etching the phase shift layer over the mask to form a phase shift pattern;
And a step of further etching the etching stopper pattern. The method of claim 3,
The etching liquid containing acetic acid is used for the etching of the said etching stopper layer, The manufacturing method of the phase shift mask characterized by the above-mentioned.

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