JP2005181895A - Halftone phase shift mask blank and halftone phase shift mask manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blank for a halftone type phase shift mask capable of providing a blank which can remarkably improve the dimensional accuracy of a pattern of a halftone film as compared with the prior art by using a halftone blank structure without a light shielding film. And a halftone phase shift mask manufacturing method.
A thin-film conductive layer is formed on a halftone film in a blank for a halftone phase shift mask formed by laminating a halftone film on a transparent substrate.
[Selection] Figure 1

Description

  The present invention relates to a blank for a halftone phase shift mask with improved dimensional accuracy and a method for manufacturing a halftone phase shift mask.

Conventionally, generally used halftone type phase shift mask blanks have the following structure. That is, a halftone film is laminated on a glass substrate, and a light shielding film is formed on the halftone film. Further, a resist film is formed on the light shielding film. As for the manufacturing method, the halftone phase shift mask blank resist film having the above-described structure is drawn and developed, the light shielding film is etched, and the etched light shielding film is used as a hard mask. Is etched (see, for example, Patent Document 1).
JP-A-08-82916.

  In the halftone phase shift mask manufacturing method using the conventional halftone phase shift mask blank, the element size of the halftone mask is largely determined by the size of the patterned light shielding film. As the Cr used as the light-shielding film is thinner, the dimensional control is improved. However, the light-shielding property is lowered by the thinning, so that there is a limit to the thinning. In addition, since Cr has a slow dry etching rate and a resist selection ratio is difficult to obtain, it is difficult to control the size of a fine pattern, and it cannot cope with future miniaturization. Moreover, the optimal material which changes to Cr is not found now.

  The present invention has been made paying attention to the above circumstances, and its object is to use a halftone blank structure not provided with a light shielding film, so that the dimensional accuracy of the pattern of the halftone film is significantly higher than the conventional one. A blank for halftone phase shift mask and a method for manufacturing a halftone phase shift mask can be provided.

  The present invention solves such a problem, and the invention according to claim 1 is a halftone phase shift mask blank formed by laminating a halftone film on a transparent substrate, and a thin film conductive film is formed on the halftone film. A blank for a halftone phase shift mask characterized by forming a layer.

  Therefore, according to the first aspect of the invention, a thin film conductive layer is formed on the halftone film instead of the light shielding film. For this reason, the blank which improves the dimensional accuracy of the pattern of a halftone film markedly compared with the past can be provided.

  The invention of claim 2 is the blank for halftone phase shift mask according to claim 1, wherein the film thickness of the halftone film is 10 to 40 nm.

  Therefore, the invention according to claim 2 can provide a blank that greatly improves the dimensional accuracy of the pattern of the halftone film as compared with the conventional one because the film thickness of the halftone film is 10 to 40 nm.

  Further, the invention of claim 3 is the halftone phase shift mask blank according to claim 1 or 2, wherein the halftone phase shift mask blank has an optical density value of 2 or less in the transfer wavelength region. A blank for a halftone phase shift mask, which is characterized in that:

  Therefore, in the invention of claim 3, the optical density value in the transfer wavelength region of the blank for halftone phase shift mask is 2 or less. For this reason, the blank which improves the dimensional accuracy of the pattern of a halftone film markedly compared with the past can be provided.

  According to a fourth aspect of the present invention, in the halftone phase shift mask manufacturing method comprising a halftone film laminated on a transparent substrate, a thin film conductive layer and a resist film are sequentially laminated on the halftone film. Preparing a tone blank; patterning a main pattern on the resist film; etching the thin-film conductive layer and halftone film using the patterned resist film as a mask; and the resist film and thin-film conductive Peeling the layer, laminating a resist film on the patterned halftone film, patterning the resist film so that the resist corresponding to the final light-shielding film pattern is removed, and on the patterned resist film And shading film on halftone film The method comprising a said resist film and the resist halftone phase shift mask manufacturing method characterized by comprising the step of separating the light shielding film on the membrane.

  Accordingly, the invention of claim 4 prepares a halftone blank in which a thin conductive layer and a resist film are sequentially laminated on a halftone film, and patterns a main pattern on the resist film. Then, after etching the thin film conductive layer and the halftone film using the patterned resist film as a mask, the resist film and the thin film conductive layer are peeled off. Subsequently, a resist film is laminated on the patterned halftone film, and the resist film is patterned so that the resist corresponding to the final light-shielding film pattern is removed. Then, a light shielding film is formed on the patterned resist film and the halftone film, and the resist film and the light shielding film on the resist film are peeled off. Therefore, it is possible to provide a halftone phase shift mask in which the dimensional accuracy of the halftone film pattern is remarkably improved as compared with the prior art.

  According to a fifth aspect of the present invention, there is provided a blank for a halftone type phase shift mask comprising a halftone film laminated on a transparent transparent substrate, a thin film conductive layer formed on the halftone film, and the transparent substrate. A halftone phase shift mask blank comprising a light shielding film formed on a surface opposite to the surface on which the halftone film is formed.

  Accordingly, the invention of claim 5 includes a thin film conductive layer formed on a halftone film on a transparent substrate, and a light shielding film formed on a surface opposite to the surface on which the halftone film of the transparent substrate is formed. Prepare. For this reason, the blank which improves the dimensional accuracy of the pattern of a halftone film markedly compared with the past can be provided.

  The invention of claim 6 is the blank for halftone phase shift mask according to claim 5, wherein the film thickness of the halftone film is 10 to 40 nm.

  Therefore, since the film thickness of the halftone film is 10 to 40 nm, the blank according to the sixth aspect of the present invention can provide a blank that can remarkably improve the dimensional accuracy of the pattern of the halftone film as compared with the prior art.

  The invention of claim 7 is the blank for halftone phase shift mask according to claim 5 or 6, wherein the optical density value in the transfer wavelength region of the blank for halftone phase shift mask is 2 or less. A blank for a halftone phase shift mask, which is characterized in that:

  Accordingly, in the invention of claim 7, since the optical density value in the transfer wavelength region of the blank for halftone type phase shift mask is 2 or less, the blank that greatly improves the dimensional accuracy of the pattern of the halftone film as compared with the prior art. Can be provided.

  The invention of claim 8 is a halftone phase shift mask manufacturing method comprising a halftone film laminated on a transparent substrate, and a thin film conductive layer and a first resist film are sequentially laminated on the halftone film. And a step of preparing a halftone blank in which a light shielding film and a second resist film are sequentially laminated on a surface of the transparent substrate opposite to the surface on which the halftone film is formed; Patterning a main pattern on a resist film, etching the thin film conductive layer and halftone film using the patterned first resist film as a mask, patterning the second resist film, Etching the light-shielding film using the patterned second resist film as a mask, and That is a halftone phase shift mask manufacturing method.

  Accordingly, in the invention of claim 8, the thin conductive film and the first resist film are sequentially laminated on the halftone film, and the light shielding film is formed on the surface of the transparent substrate opposite to the surface on which the halftone film is formed. A halftone blank in which the second resist films are sequentially laminated is prepared. Subsequently, etching of the thin film conductive layer and the halftone film and etching of the light shielding film are performed to manufacture a halftone phase shift mask. Therefore, it is possible to provide a halftone phase shift mask in which the dimensional accuracy of the halftone film pattern is remarkably improved as compared with the prior art.

  According to the halftone phase shift mask blank of the present invention, since the transparent substrate, the halftone film, and the thin film conductive layer are laminated in this order, the conductivity at the time of EB writing is satisfied even when the EB resist is used. In addition, it is possible to provide a blank capable of greatly improving the dimensional accuracy in etching a halftone film.

  Further, according to the method of manufacturing a halftone phase shift mask of the present invention, even when an EB resist is used, the dimensional accuracy is greatly improved in etching of the halftone film while satisfying the conductivity at the time of EB writing. be able to. Further, since the light shielding film is formed separately without using the light shielding film for patterning of the halftone film, the light shielding film in the halftone phase shift mask of the present invention is a film that maintains a sufficient optical density and reflectance. It can be thick.

(First embodiment)
Next, a first embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of a blank for a halftone phase shift mask according to the first embodiment of the present invention.

  As shown in FIG. 1, the halftone phase shift mask blank according to the first embodiment of the present invention is sequentially formed on a glass substrate 1 with a halftone film 2, a thin film conductive layer 3, and a resist film (for example, an EB resist film). ) 4 is laminated. In the case of using an EB resist film, the thin film conductive layer 3 may be any material that satisfies the conductivity at the time of drawing using an electron beam. For example, Cr can be used, and a multilayer structure may be used. For example, a two-layer structure of a Cr layer for controlling the optical density and a CrO layer for controlling the reflectance of the laser can be used. The thickness of the thin film conductive layer 3 as a whole is preferably about 10 to 40 nm. The halftone film 2 preferably has a thickness of about 50 to 150 nm.

  Next, a halftone phase shift mask manufacturing method using the halftone phase shift mask blank according to the first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 2, the main pattern is patterned (drawn) on the resist film 4 of the halftone phase shift mask blank using, for example, EB (electron beam). Next, as shown in FIG. 3, the development process is performed, and the resist film 4 is peeled off along the patterning. As shown in FIG. 4, the thin film conductive layer 3 and the halftone are formed using the patterned resist film 4 as a mask. The film 2 is dry etched. Next, as shown in FIG. 5, the resist film 4 and the thin film conductive layer 3 are peeled off. Then, as shown in FIG. 6, a resist film 5 is laminated on the patterned halftone film 2. Subsequently, as shown in FIG. 7, for example, RB (laser beam) is applied so that the resist film 5 on the outer peripheral portion of the main pattern is removed in a frame shape 6 (resist films of the light shielding portion and the alignment mark portion). Then, the resist film 5 is patterned. Subsequently, as shown in FIG. 8, development processing is performed to remove the frame-like 6 portion of the resist film 5. Then, as shown in FIG. 9, a light shielding film 7 is formed on the patterned photoresist 5 film and the halftone film 2 using, for example, Cr by sputtering. Subsequently, as shown in FIG. 10, the resist film 5 and the light shielding film 7 on the resist film 5 are peeled off. Finally, cleaning, appearance inspection, and correction are performed, and the production of the halftone phase shift mask is completed.

  As described above, by using the halftone phase shift mask blank and the halftone phase shift mask manufacturing method of the present invention, it is possible to realize a pattern with much higher dimensional accuracy than the conventional method. .

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 11 is a cross-sectional view showing one embodiment of a blank for halftone phase shift mask according to the second embodiment of the present invention.

  As shown in FIG. 11, the halftone phase shift mask blank according to the second embodiment of the present invention sequentially has a halftone film 2, a thin film conductive layer 3, a resist film (for example, EB) on one side of the glass substrate 1. Resist film) 4, and a light shielding film 2 ′ and a resist film (for example, a photoresist film) 5 are laminated on the other side of the glass substrate 1. When an EB resist is used, the thin film conductive layer 3 may be any material that satisfies the conductivity at the time of drawing using an electron beam. The material and film thickness of the thin film conductive layer 3 in this case are the same as those in the first embodiment.

  Next, a halftone phase shift mask manufacturing method to which the blank for halftone phase shift mask according to the second embodiment of the present invention is applied will be described with reference to FIGS. As shown in FIG. 12, a main pattern is patterned (drawn) on the resist film 4 of the halftone phase shift mask blank using, for example, EB (electron beam). Next, as shown in FIG. 13, development processing is performed, and the resist film 4 is peeled off along the patterning. Next, as shown in FIG. 14, the thin film conductive layer 3 and the halftone film 2 are dry-etched using the patterned resist film 4 as a mask. Next, as shown in FIG. 15, the resist film 4 and the thin film conductive layer 3 are peeled off.

  Then, the entire substrate is turned upside down as shown in FIG. 16, and the resist film 5 is patterned using, for example, RB (laser beam) so that the resist film 5 is removed in the frame 8. Then, as shown in FIG. 17, development processing is performed, and the resist film 5 is peeled off along the patterning. Subsequently, as shown in FIG. 18, the light shielding film 2 'is etched using the resist film 5 as a mask. Then, as shown in FIG. 19, the resist film 5 is peeled off. Finally, cleaning, appearance inspection, and correction are performed, and the production of the halftone phase shift mask is completed.

  As described above, by using the halftone phase shift mask blank and the halftone phase shift mask manufacturing method of the present invention, it is possible to realize a pattern with much higher dimensional accuracy than the conventional method. .

  Next, as an example, a test was performed as to how the thinning of the light-shielding film affects the element size using FIGS. 20 to 22. The evaluation contents and evaluation method are shown below.

<Evaluation details>
As shown in FIG. 20, when the light shielding film is etched using a resist pattern having the same resist dimensions (A) and (B) and different pitches as shown in FIG. As shown in FIG. 2, it was found that the dimensions greatly differ depending on the pitch. In this example, it was tested how such a tendency fluctuates depending on the thickness of the light shielding film. The thickness of the light shielding film was 100, 70, and 30 nm, and the test was performed using Cr as the material. The light shielding film of 100 nm and 70 nm is a commonly used Cr blank, and is a light shielding film designed so as to satisfy the specifications of OD = 3 or more, reflectivity of 365 nm = 10 to 15%. The 30 nm Cr blank has an OD = 1.5 and a reflectance = 5%, which is far from the specifications of a general Cr blank and does not play a role as a light-shielding film at all. It can be said that it is a layer provided to prevent up.

<Evaluation method>
1. 1. Resist is applied on three types of light shielding films with different film thicknesses. 2. Drawing and developing an evaluation pattern (Line & space pattern with a pitch of 0.4-8 μm). 3. Dry etching of light shielding film using chlorine gas. Measuring the length of the light-shielding film (line portion of the line & space) after stripping the remaining resist Next, FIG. The thickness of the light shielding film was 100, 70, and 30 (nm). The X axis is the pitch, and the Y axis is the deviation ΔCD from the design dimension. It can be seen that the pitch-dependent CD fluctuation is greatly improved as the light shielding film is made thinner. However, 30 nm Cr has a low OD and hardly plays a role as a light shielding film. Therefore, the inventors have invented a manufacturing method in which a Cr film of about 30 nm is used only for etching a halftone layer, and a Cr film serving as a light shielding film is separately provided.

Sectional drawing which shows the structure of the blank for halftone type phase shift masks concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 1st Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 2nd Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 2nd Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 2nd Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 2nd Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 2nd Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 2nd Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 2nd Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 2nd Embodiment of this invention. Sectional drawing which shows the halftone type phase shift mask manufacturing method concerning 2nd Embodiment of this invention. The figure which shows the evaluation content and evaluation method about the test of how thinning of the light shielding layer concerning the Example of this invention influences an element dimension. The figure which shows the evaluation content and evaluation method about the test of how thinning of the light shielding layer concerning the Example of this invention influences an element dimension. The figure which shows the result of the experiment concerning the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Halftone film, 2 ', 7 ... Light-shielding film, 3 ... Thin film conductive layer, 4 ... Resist film, 5 ... Resist film

Claims (8)

In a blank for a halftone phase shift mask formed by laminating a halftone film on a transparent substrate,
A blank for a halftone phase shift mask, wherein a thin film conductive layer is formed on the halftone film. The blank for a halftone phase shift mask according to claim 1, wherein the film thickness of the halftone film is 10 to 40 nm. In the blank for a halftone type phase shift mask according to claim 1 or 2,
The halftone phase shift mask blank, wherein the halftone phase shift mask blank has an optical density value of 2 or less in a transfer wavelength region. In a halftone phase shift mask manufacturing method in which a halftone film is laminated on a transparent substrate,
A step of preparing a halftone blank in which a thin film conductive layer and a resist film are sequentially laminated on the halftone film; and
Patterning a main pattern on the resist film;
Etching the thin film conductive layer and the halftone film using the patterned resist film as a mask;
Peeling the resist film and the thin film conductive layer;
Patterning a patterned resist film on the halftone film;
Patterning the resist film so that the resist corresponding to the final light-shielding film pattern is removed;
Forming a light shielding film on the patterned resist film and the halftone film;
Peeling off the resist film and the light shielding film on the resist film;
A method for producing a halftone phase shift mask, comprising: In a blank for a halftone phase shift mask formed by laminating a halftone film on a transparent substrate,
A thin film conductive layer formed on the halftone film;
A light shielding film formed on a surface opposite to the surface on which the halftone film of the transparent substrate is formed;
A blank for a halftone phase shift mask, comprising:   6. The halftone phase shift mask blank according to claim 5, wherein the halftone film has a thickness of 10 to 40 nm. In the blank for a halftone type phase shift mask according to claim 5 or 6,
The halftone phase shift mask blank, wherein the halftone phase shift mask blank has an optical density value of 2 or less in a transfer wavelength region. In a halftone phase shift mask manufacturing method in which a halftone film is laminated on a transparent substrate,
A thin film conductive layer and a first resist film are sequentially laminated on the halftone film, and a light shielding film and a second resist are formed on the surface of the transparent substrate opposite to the surface on which the halftone film is formed. Preparing a halftone blank in which films are sequentially laminated;
Patterning a main pattern on the first resist film;
Etching the thin-film conductive layer and the halftone film using the patterned first resist film as a mask;
Patterning the second resist film;
Etching the light-shielding film using the patterned second resist film as a mask;
A method for producing a halftone phase shift mask, comprising:

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