JP2882215B2 - Method for manufacturing phase shift reticle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates relates to a manufacturing <br/> production method of a phase shift reticle, a method of manufacturing a reticle having a shifter, especially giving a phase difference.

[0002]

2. Description of the Related Art In a reticle which is a photomask used in a reduction projection exposure apparatus, a phase shift rakele for transferring an adjacent opening pattern with good resolution is disclosed in, for example, Nikkei Micro Devices, July 1990 No. 61 PP10
3-114.

In the prior art phase shift reticle, as shown in FIG. 4, a thin conductive film 2 for preventing electrification at the time of drawing an electron beam is formed on the entire surface of a glass substrate 1, and a light shielding body is further formed thereon. By forming a chromium film and forming a pattern, a desired pattern of the chromium film 3 is obtained, and a shifter 6 as a retardation material pattern is formed thereon. The conductive film 2 shown here may not be necessary depending on the conditions of electron beam drawing at the time of pattern formation. In this case, the chromium film 3 may be formed directly on the glass substrate 1.

FIG. 5 is a prior art method of manufacturing the structure of FIG.

[0005] First, a conductive film 2 is formed on a glass substrate 1 serving as a base material of a reticle to prevent charging during electron beam drawing, and a chromium film 3 formed thereon is patterned ( FIG. 5 (a)). Next, chemical vapor deposition (hereinafter referred to as C
VD), a silicon dioxide film 7 is formed as a retardation material by a sputtering method or a spin coating method. Further, a resist 8 is applied on the silicon dioxide film 7 by a spin coating method or the like, and a desired pattern is exposed by an electron beam 10 (FIG. 5 (b)). When the silicon dioxide film 7 is patterned as a mask by etching and the resist 8 is finally removed, a reticle having the phase shifter 6 formed from the silicon dioxide film 7 is obtained (FIG. 5C).

In recent years, a summary of lectures at the 38th Lecture Meeting on Applied Physics, Spring 1991 2,5
As introduced in page 35, 29P-ZC-1, a glass substrate is selectively etched as a phase difference material to obtain a phase difference.

One example is shown in FIG. Figure 4 shown earlier
As in the conventional example shown in FIG. 5, a conductive film 2 is provided on a glass substrate 1 and a desired light shielding pattern 3 is formed thereon. Next, a portion other than a portion where a phase difference is to be provided is covered with a resist, the conductive film 2 in a portion where a phase difference is to be provided is removed by etching, and then the glass substrate 1 is dug to a desired depth by an etching method. Fig. 6
Can be obtained.

[0008]

In the phase shift reticle shown in FIGS. 4 and 5 in which the phase difference material pattern 6 is formed on the conventional light-shielding body pattern 3, light is shielded by a step caused by the light-shielding body pattern 3. Phase difference material 6 near body
Since the film thickness difference occurs in (7), the phase of the light transmitting portion becomes non-uniform, and there is a problem that the effect of the phase shift method cannot be sufficiently obtained.

That is, in this conventional method of manufacturing a phase shift reticle, this reticle has a wavelength λ of 365 nm.
(Nanometer) light, the thickness of the shifter 6 by the silicon dioxide film 7 is:
from λ / {2 × (n−1)} to about 424 nm ± 10 nm,
That is, film thickness control and uniformity of about ± 2.4% from the desired film thickness are required.

However, in the case where the silicon dioxide film 7 as a retardation material is formed by the CVD method according to the conventional technique and is patterned to obtain the shifter 6, the uniformity of the film thickness in the reticle plane is about ± 5%. Bad, I can't control the phase of light. Further, when the silicon dioxide film 7 is formed by the spin coating method, there is a problem that the unevenness due to the chromium pattern cannot be eliminated even on the surface of the silicon dioxide film, and the film thickness difference is large between the center and the edge of the unevenness.

On the other hand, in the conventional phase shift reticle shown in FIG. 6 for selectively excavating a glass substrate, the depth is difficult to control because the excavation is performed by time control.
Reactive ion etching (hereinafter abbreviated as IRE)
Since the glass substrate is dug by a method or the like, a portion through which light is transmitted becomes physically rough, and the phase of light is disturbed.

[0012]

A feature of the present invention is to provide a method of manufacturing a phase shift reticle for imparting a phase difference to light transmitted through an adjacent opening, wherein a desired pattern is formed on a glass substrate. The process of forming a light-shielding body and constantly
A light-shielding body is placed on the glass substrate in an aqueous solution maintained in a harmony state.
By immersing in a state where a pattern is formed,
Silicon dioxide is used to cover the entire surface of the glass
A step of forming a planarizing film, and a resist pattern on the planarizing film.
Forming a turn, and exposing between the resist pattern.
The resist pattern is formed on the portion of the flattening film to be exposed.
Is used as a mask to keep silicon dioxide supersaturated at all times.
Immersed in an aqueous solution with the flattening film formed
To form a phase difference material by a silicon dioxide film.
In method of manufacturing a phase shift reticle and a that step.

[0013] Other features of the present invention is a method of manufacturing a phase shift reticle which gives a phase difference to light passing through the aperture adjacent, forming a light shield having a desired pattern on a glass substrate, always dioxide Keeping silicon supersaturated
A light-shielding pattern on the glass substrate in the aqueous solution
Forming a flattening film made of silicon dioxide on the entire surface of the glass substrate including the light-shielding body by dipping in a formed state ; and forming a conductive film on the flattening film.
And always keep the silicon dioxide supersaturated on the conductive film.
Immersed in the dipped aqueous solution with the flattening film formed
Forming a silicon dioxide film by immersion;
Forming a resist pattern on the silicon dioxide film
And the conductive pattern using the resist pattern as a mask.
The silicon dioxide film is selected with the conductive film as the etching stop film.
Etching by the silicon dioxide film
And a step of forming a phase difference material .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing a phase shift reticle of a technique related to the present invention and a method of manufacturing the same.

First, as shown in FIG.
A thin first conductive film 2 is formed on the entire surface, and a chromium film pattern 3 is formed thereon as a light shielding pattern,
A silicon dioxide film as a planarizing film 4 is formed on the entire surface by a CVD method, for example, a low-pressure CVD method (about 200 ° C.) or a photo-CVD method (about 100 ° C.) which can form a film at a low temperature, or a sputtering method. Is formed to a sufficient thickness so that the flatness is satisfactory. In FIG. 1 , a silicon dioxide film 4 of about 800 nm (nanometer) is formed.

Next, as shown in FIG. 1B, a second conductive film 5 is deposited on the entire upper surface of the flattening film 4, and a spin coating method, a CVD method, a sputtering method or the like is further formed thereon. A phase difference material for forming a shifter, here, a silicon dioxide film is formed on the entire surface to a desired thickness. Thereafter, the pattern of the shifter 6 is obtained by patterning the silicon dioxide film formed on the entire surface into a desired shape.

The first conductive film 2 is provided as an antistatic film when the chromium film pattern 3 is formed by electron beam exposure. However, the first conductive film 2 may not be necessary depending on electron beam drawing conditions at the time of formation. . In this case, the chromium film 3 may be formed directly on the glass substrate 1. Similarly, the second conductive film 5 is provided as an antistatic film when the shifter pattern 6 is formed by electron beam exposure. However, the second conductive film 5 may not be necessary depending on electron beam drawing conditions at the time of formation. In this case, the shifter pattern 6 may be formed directly on the flattening film 4.

FIG. 2 is a sectional view showing a method of manufacturing the phase shift reticle according to the first embodiment of the present invention.

First, as shown in FIG.
A chromium film 3 is formed in a desired pattern on the upper conductive film 2. The conductive film 2 shown here may not be necessary depending on the manufacturing method and conditions at the time of forming the chromium pattern.

Next, as shown in FIG.
For example, a low pressure CVD method (200 ° C.
About 50 n) by photo CVD (about 100 ° C.)
A thin silicon dioxide film 9 having a thickness of m is formed. In this embodiment, the light C
Using a VD method, the film thickness is 47 nm ± 2.8 over the entire surface of the reticle.
A silicon dioxide film 9 having a thickness of 10 nm was formed.

[0022] Next Figure 2, as shown (c), the silicon dioxide film 4 by a liquid phase growth method or a spin coating method as a flattening film 4
To form Of these, the embodiment is formed by the liquid phase growth method
It is.

The liquid phase growth method of this embodiment is described in, for example,
About 3.5 mol by the method described in JP-A-97247.
Silanol (Si (OH) ₄ ) in aqueous hydrofluoric acid solution
At a temperature of 30 ° C. using a saturated aqueous solution obtained by melting silicon dioxide powder formed by firing at a low temperature of 150 ° C.
The concentration is about 0.1 mol to keep the supersaturated state at all times
/ L boric acid aqueous solution was continuously added at a rate of 10 cc / hour. This supersaturated aqueous solution has an opening width of 0.2 μm.
The particles were constantly circulated using a Teflon filter to remove particles having a particle size exceeding 0.2 μm. The intermediate product of the reticle is immersed in the aqueous solution which is constantly supersaturated and maintained at a constant temperature of 35 ° C. The growth rate of silicon dioxide is 4
Since it is 0 nm / hour, the flattening film 4 made of a 0.7 μm thick silicon dioxide film is formed by immersion for 17 hours and 30 minutes. At this time, the irregularity difference at the portion where the shifter material is to be formed later on the surface of the flattening film 4 was about 3 nm. When a silicon dioxide film is formed as the flattening film 4 by a spin coating method, the concentration of silicon dioxide is 20 wt%.
Was spin-coated at 2000 rpm for 60 seconds, and baked at 200 ° C. for 30 minutes to form a flattening film 4. As a result, a silicon dioxide flattening film 4 having a thickness of 0.98 μm was formed. At this time, the unevenness difference on the surface of the flattening film 4 where the shifter material is to be formed later was about 1.5 nm. However, the flat effect in this case can be obtained similarly even when the underlying silicon dioxide film 9 is not present.

Next, as shown in FIG. 2D, a resist is applied on the flattening film, and is exposed and developed to a desired pattern, so that a resist pattern is formed on a portion where it is not necessary to form a retardation material. 8 is formed. Next, while the resist pattern 8 is formed, the silicon dioxide film having a thickness of 286 nm is selectively formed between the resist patterns 8 by immersing the resist pattern 8 for 7 hours, 9 minutes, and 27 seconds. Obtain shifter 6. At this time, the thickness uniformity of the silicon dioxide film of the phase difference material to be the shifter 6 was as good as ± 1.0%.

Finally, by stripping the resist 8,
As shown in FIG. 2E, a phase shift reticle in which a shifter 6 which is a pattern of a retardation material is formed at a desired portion is obtained.

FIG. 3 is a sectional view showing a method of manufacturing a phase shift reticle according to a second embodiment of the present invention.

First, as shown in FIGS. 3A and 3B, FIG.
The pattern of the chromium film 3 and the flattening film 4 are formed on the conductive film 2 on the glass substrate 1 in the same manner as in the second embodiment.

However, when the flattening film 4 is formed by the liquid phase growth method, as shown in FIG. 3B of the first embodiment, a thin silicon dioxide film is formed on the chromium film 3 by a CVD method or the like. A film 9 is formed.

Next, as shown in FIG. 3C, a conductive film 5 serving as an etching stop film is formed on the flattening film 4 in a later step. Further, a silicon dioxide film 7 serving as a phase difference material is formed on the entire surface of the conductive film 5 by a liquid phase growth method or a spin coating method. In the case of the liquid phase growth method, the silicon dioxide film 7 having a thickness of 286 nm is formed on the entire surface by immersing in the aqueous solution of hydrogen silicon fluoride described in the first embodiment for 7 hours, 9 minutes, and 27 seconds. At this time, the thickness uniformity of the silicon dioxide film 7 is ± 1.0%.
Met.

In the case of forming by a spin coating method, a coating agent having a silicon dioxide concentration of 12 wt% is applied at 4000 rpm for 6 hours.
Spin coating is performed for 0 second, followed by baking at 200 ° C. for 30 minutes to form a silicon dioxide film 7. At this time, the thickness of the silicon dioxide film 7 is 287 nm, and the uniformity of the thickness is ± 1.4%.
Met.

Next, as shown in FIG. 3D, a resist is applied on the silicon dioxide film 7, and a desired pattern is exposed and developed. By selectively etching the silicon dioxide film 7 by a reactive ion etching method or the like using the resist pattern 8 as an etching mask, a shifter 6 which is a pattern of the silicon dioxide film 7 as a retardation material is formed.
Get.

Finally, as shown in FIG.
Is peeled off, a phase shift reticle in which the retardation material 6 is formed at a desired portion on the reticle is obtained. According to the method of this embodiment, the same effects as those of the above embodiment can be obtained.

[0033]

As described above, according to the present invention, the unevenness of the surface caused by the light-shielding pattern made of the chromium film is flattened by the flattening film, thereby minimizing the phase disturbance in the same light transmitting portion. It has the effect that can be done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a technique related to the present invention.

FIG. 2 is a sectional view showing a first embodiment of the present invention.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional technique.

FIG. 5 is a cross-sectional view illustrating a prior art method of manufacturing FIG.

FIG. 6 is a sectional view showing another conventional technique.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 glass substrate 2 conductive film 3 chromium film 4 flattening film 5 conductive film 6 shifter 7 silicon dioxide film as retardation material forming shifter 6 8 resist pattern 9 thin silicon dioxide film 10 electron beam

Claims (2)

(57) [Claims] In a method of manufacturing a phase shift reticle for giving a phase difference to light transmitted through an adjacent opening, a step of forming a light shield of a desired pattern on a glass substrate;
In an aqueous solution always kept in a supersaturated state of silicon dioxide,
Immerse in a state where a light shielding pattern is formed on a glass substrate
By Rukoto, forming a planarization film on silica over the entire surface of the glass substrate including the light-shielding member, the flat
Forming a resist pattern on the carrier film;
On the portion of the flattening film exposed between the distant patterns,
Using the resist pattern as a mask, silicon dioxide
Of the flattening film in an aqueous solution maintained in a supersaturated state
The silicon dioxide film by immersion
Forming a phase difference material by using the method. 2. A method of manufacturing a phase shift reticle for giving a phase difference to light transmitted through an adjacent opening, forming a light shielding body having a desired pattern on a glass substrate.
In an aqueous solution always kept in a supersaturated state of silicon dioxide,
Immerse in a state where a light shielding pattern is formed on a glass substrate
By Rukoto, forming a planarization film on silica over the entire surface of the glass substrate including the light-shielding member, the flat
Forming a conductive film on the carrier film;
In an aqueous solution that is always kept in a supersaturated state of silicon dioxide.
By immersing with the flattened film formed
Forming a silicon dioxide film; and forming a silicon dioxide film on the silicon dioxide film.
Forming a resist pattern;
Stop etching of the conductive film using the mask as a mask
The silicon dioxide film is selectively etched as a film.
Forming a phase difference material by the silicon dioxide film
Method of manufacturing a phase shift reticle and having a degree.