JPH0430168A - Manufacture of phase shift mask - Google Patents

Abstract

PURPOSE:To avoid deterioration of yield by subjecting the phase shift material film to isotropic etching to patterning it. CONSTITUTION:Light-shielding parts 10 are formed on the first main surface of a transparent substrate 1, and the phase shift material layer 11' is formed on the parts 10 and the substrate 1, and a negative type photoresist layer 2' is formed on the layer 11'. Next, the layer 11' is exposed from the second main surface by using the parts 10 as a mask to form a resist pattern, further, the film 11' is subjected to isotropic etching by using this pattern as a mask, and the phase shift mask having light transmitting parts 12 between the light- shielding parts 10 and the phase shift parts 11, thus permitting the obtained phase shift mask to avoid deterioration due to dust.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a phase shift mask. The present invention can be used as a method for manufacturing a phase shift mask used in various pattern forming techniques, for example, as a method for manufacturing a phase shift photomask used as a mask for forming a resist pattern in a semiconductor device manufacturing process. be able to.

[Summary of the invention]

In the present invention, when manufacturing a phase shift mask including a light shielding part, a light transmitting part, and a phase shift part on a transparent substrate,
Using the light shielding part formed on the first main surface of the transparent substrate as a mask, the resist layer on the light shielding part is patterned by exposure from the second main surface (back surface), and the resist layer on the light shielding part is patterned using the obtained resist pattern as a mask. By isotropically etching the phase shift material film formed in the previous step, a phase shift mask in which a light transmitting part is formed between the light shielding part and the phase shift part is obtained, thereby reducing the yield due to dust. This makes it possible to obtain a phase shift mask without causing deterioration.

[Conventional technology]

2. Description of the Related Art Devices formed using photomasks, such as semiconductor devices, tend to have smaller processing dimensions year by year.

Against this background, in order to further improve the resolution of photolithography technology for producing miniaturized semiconductor devices, so-called phase shift technology is used to impart a phase difference to the light passing through a mask, thereby improving the light intensity profile. is in the spotlight.

This technique was introduced by IBM's Levenson et al., and the conventional phase shift method can be found in Japanese Patent Application Laid-open No. 173744/1983 and ? IARCD.

LEVENSON and others “Improving Re5o
lution in Photolitho-gr
aphy emith a Phase-5hifti
ng Mask” IEEE TRANS-ACTIO
NS ON ELECTRON DEVICES, V
OL, HD-29No, 12゜DECEMBER19
82, P1828-1836, also MARCD, LE
VENSON and others “The Phase-3hiftin”
g MaskII: ImagingSis+ula
tions and Submicrometer R
e5ist Exposures magazine Vol.1. HD-
31, No, 6. JUNE 1984. P2S5~
There is a description in 763.

The conventionally known phase shift method will be explained using FIG. 4 as follows.

For example, when forming a line-and-space pattern, a normal conventional mask uses a light-shielding material such as Cr (chromium) on a transparent substrate 1 such as a quartz substrate, as shown in FIG. 4(a). A light shielding part 10 is formed using a material, and a repeating pattern of lines and spaces is formed thereby to serve as an exposure mask. Ideally, the intensity distribution of the light transmitted through this exposure mask is zero at the light shielding part 10 and at other parts (transmissive parts 12a, 12b), as shown by the symbol A1 in FIG. 4(a). Let's pass through. Considering one transmitting part 12a, the transmitted light given to the exposed material has a light intensity distribution with a hill-like maximum at both sides of the base, as shown by A2 in FIG. 4(a), due to light diffraction, etc. become. The transmitted light toward the transmitting portion 12b is indicated by a dashed-dotted line. Combining the light from each transmission part 12a and 12b, A3
As shown in the figure, the light intensity distribution loses its sharpness and the image becomes blurred due to light diffraction, making it impossible to achieve sharp exposure. On the other hand, the light transmitting portion 12a of the repeating pattern.

If phase shift parts 11a are provided on every other part 12b as shown in FIG. and focus latitude is improved. That is, Fig. 4 (
As shown in b), one of the transmission parts 12a is provided with a phase shift part 1.
When 1a is formed, if it provides a phase shift of, for example, 180°, the light passing through the phase shift portion 11a is inverted as indicated by the symbol B1. Since the light from the adjacent transmission section 12b does not pass through the phase shift section 11a, such inversion does not occur. The light applied to the exposed material is inverted and cancels each other out at the bottom of the light intensity distribution at the position indicated by B2 in the figure, and the distribution of light applied to the exposed material is as shown in Figure 4(b). As shown in B3, it has a sharp ideal shape.

In the above case, in order to most ensure this effect, it is most advantageous to invert the phase by 180 degrees. establish.

When forming a pattern by exposure, the one that performs reduced projection is sometimes called a reticle, and the one that projects one-to-one is called a mask, or the one that corresponds to the original is called a reticle, and the one that reproduces it is called a mask. However, in the present invention, masks and reticles in various meanings are collectively referred to as a mask.

[Problem that the invention seeks to solve]

As a structure of the phase shift mask as described above, there is one in which a phase shift part is formed adjacent to a peripheral part of a light shielding part made of a light shielding material such as chromium.

An example of such a structure is shown in FIG. 2(a). The example in FIG. 2(a) shows a light shielding part 1 formed on a substrate 1.
A phase shift material film 11' is formed to cover the phase shift material film 11', and a side end portion of the phase shift material film 11' that does not overlap with the light shielding part 10 is used as a phase shift part 11. The structure is such that a light transmitting part 12 exists between the phase shift parts 11.

FIG. 2(b) shows another example of the above structure. In the example shown in FIG. 2(b), a light shielding part 10 is formed on the phase shift material film 11' formed on the substrate 1 so as not to completely cover it, and the phase shift material film 11'
The side end portion of the light shielding portion 10 that is not covered with the light shielding portion 10 is used as a phase shift portion 11 . In this example as well, the light transmission section 12 exists between the phase shift sections 11.

However, all of these conventional structures require some form of etching of the phase shift material on the substrate 1.

For example, FIG. 3 shows a case where a structure as shown in FIG. 2(b) is to be obtained by etching a phase shift material (for example, Sing) on a substrate 1 such as glass using a resist 2 or the like as a mask. A patterning step is essential, and at this time, it is difficult to avoid damaging the underlying substrate 1.

In Fig. 3, arrow A schematically shows the etching situation.
The damage to the substrate 1 caused by this is also schematically represented by the waveform indicated by B.

On the other hand, various other methods for manufacturing phase shift masks have been proposed; for example, a method for manufacturing phase shift masks using the lift-off method has been introduced (Proceedings of the Japan Society of Applied Physics, Autumn 1989, 29a -L-9
, Autumn 1988, 4a-7, etc.).

However, in the conventional method using the lift-off method, dust is inevitably generated during the lift-off process in which a part of the mask is removed along with the resist, and this dust may cause defective products, resulting in a decrease in yield. There is a big risk.

The present invention solves the above-mentioned problems and provides a method for manufacturing a phase shift mask that can obtain a phase shift mask without damaging the substrate and also avoids a decrease in yield due to dust. purpose.

[Means for solving problems]

The method for manufacturing a phase shift mask of the present invention includes: a transparent substrate;
A method for manufacturing a phase shift mask including a light shielding part, a light transmitting part, and a phase shift part, the method comprising forming a light shielding part on a first main surface of a transparent substrate, and forming a phase shift material film on the light shielding part. , further form a negative photoresist layer thereon, irradiate light from the main surface of the apprentice 2, expose the photoresist layer using the light shielding part as a mask, and pattern it to form a resist pattern. The phase shift material film is isotropically etched using the resist pattern as a mask, thereby obtaining a phase shift mask in which a light transmitting part is formed between a light shielding part and a phase shift part. The above objectives have been achieved.

In the present invention, the phase shift portion refers to a portion that transmits light at a phase different from that of the light transmitted by the light transmitting portion. The light shielding section is a section that blocks the exposure light used, and the light transmitting section is a section that transmits the exposure light used.

It is desirable that the light-shielding part and the light-transmitting part have a high light-shielding property and a high light-transmitting property, respectively, but they do not necessarily have to be completely or close to it, and should be able to block or transmit light to the extent that the desired pattern can be formed. It is fine as long as it is done.

Like the light transmitting part, the phase shift part is also desired to have a high light transmittance, but it may be of any type as long as it can perform the necessary phase inversion and exposure.

The material for the light shielding part is chromium, other chromium oxide,
Alternatively, high melting point metals (W, Mo5Be, etc.) in general, their oxides, silicides (MoSiz, etc.), etc. can be used.

In the present invention, any material can be used for the phase shift portion as long as it can produce the above-mentioned phase shift effect, and Si
Silicon oxide such as n, SiO, silicon nitride, resist, etc. can be used.

The light transmitting section can be configured to transmit light from a transparent substrate portion in which no light shielding section or phase shift section is formed, as it is.

As the transparent substrate, quartz, ordinary glass, glass containing various components as appropriate, and other appropriate materials can be used.

In the present invention, a negative photoresist refers to a resist in which the exposed portion remains to form a resist pattern and the unexposed portion is removed, and any such photoresist can be used. .

In the present invention, the first main surface of the transparent substrate refers to the surface of the substrate on which the phase shift portion is formed, and hereinafter referred to as "surface" as appropriate.
It is also sometimes called. The second main surface refers to the opposite surface, and is also sometimes referred to as the "back surface."

[Effect]

According to the present invention, the phase shift material film is patterned by isotropic etching, and therefore anisotropic etching such as RIE, which damages the underlying substrate, is not used, so the problem of damage to the substrate is solved. .

Moreover, there is no need to use a lift-off method, and therefore, a decrease in yield due to dust generation etc. can be avoided.

〔Example〕

Examples of the present invention will be described below. However, it goes without saying that the present invention is not limited to the examples described below.

Example 1 This example embodies the present invention in the case of manufacturing a phase shift mask used in manufacturing a miniaturized and integrated semiconductor device.

Please refer to FIGS. 1(a) to (e).

In this embodiment, a light shielding portion 10 is formed on the first main surface (front surface) of the transparent substrate 1, as shown in FIG. 1(a).

Next, a phase shift material film 11' is formed on the light shielding part 10, and a negative type photoresist layer 2' is further formed thereon to obtain the structure shown in FIG. 2(b).

Thereafter, as schematically indicated by the arrow P in FIG. 1(b), light is irradiated from the second main surface (the back surface with respect to the first main surface) to expose the photoresist layer 2' using the light shielding part 10 as a mask. .

This patterning is performed to form a resist pattern 2 as shown in FIG. 1(C).

Using the resist pattern 2 as a mask, the phase shift material film 11' is isotropically etched to form the structure shown in FIG. 1(d). As a result, as shown in FIG. 1(e), a phase shift mask is obtained in which a light transmitting section 12 is formed between a light blocking section 10 and a phase shifting section 11.

The present example will be explained in more detail as follows.

In this embodiment, chromium or the like is formed on the entire surface of a substrate 1 such as a glass substrate to form a light-shielding material film, and this is appropriately patterned using an EB resist or the like to form a light-shielding part 10.
The structure is shown in Figure (a).

Next, a phase shift material film 11' is formed of SiO□ or the like, and further a negative type photoresist layer 2' is formed.

For the phase shift material film 11', an appropriate deposition method can be used. In this case, the thickness of the phase shift material film 11' is adjusted so as to achieve a desired phase shift with respect to exposure light when used as a phase shift mask. The photoresist layer 2' can also be formed using any appropriate conventional means.

As a result, as shown in FIG. 1(b), the first
A structure is obtained in which a light shielding part 10 is formed on the main surface of the light shielding part 10, a phase shift material 1flll' is formed on the entire surface of the light shielding part 10, and a photoresist layer 2' is further formed on the entire surface thereof.

Regarding the structure of FIG. 1(b), as shown in the same figure,
Exposure light P is irradiated from the second main surface (back surface) to perform so-called back exposure. As a result, only the portion where the exposure light is not blocked by the light blocking section 10 is exposed.

Next, patterning is performed by developing with a developing means suitable for the resist material, and as shown in FIG.
get.

Next, using the resist pattern 2 as a mask, the phase shift material 1111' is isotropically etched.

As the isotropic etching means, it is possible to use an etching solution that etches the phase shift material, thereby performing wet etching.

Other appropriate means may be used.

As a result, the parts not covered by the resist pattern 2' and the side parts thereof (parts in the left and right direction in the figure)
is etched, so that the structure shown in FIG. 1(d) is obtained in which the phase shift material is removed from the portion adjacent to the light shielding portion 10.

Next, when the resist pattern 2 is removed, the result is shown in FIG. 1(e).
As shown in FIG. 2, a phase shift mask is obtained in which a light transmitting section 12 is formed between a light blocking section 10 and a phase shifting section 11.

In this embodiment, it is not necessary to perform etching of the phase shift film by RIE or the like, thereby preventing damage to the substrate.

Further, in this embodiment, since a lift-off method is not used, there is no risk of a decrease in yield due to dust generation or the like.

In the description of the above embodiment, it is assumed that the substrate 1 can be made of glass, but it can be made of any material as long as it is transparent to the exposure light used. Glass or the like containing components can be used arbitrarily. In addition to chromium, the light shielding part 10 is also made of chromium oxide or a high melting point metal (
W, Mo, Be, etc.), their oxides, silicides, etc. can be used.

The material of the phase shift film may also be SiO, in addition to SiO□.
Any material can be used, such as silicon nitride or various resists, as long as it has good transparency for exposure light when used as a phase shift mask (and can achieve the desired phase shift).

〔Effect of the invention〕

As described above, the method for manufacturing a phase shift mask of the present invention has the advantage that a phase shift mask can be obtained without damaging the substrate, and a decrease in yield due to dust can also be avoided. .

[Brief explanation of drawings]

FIGS. 1(a) to 1(e) are cross-sectional views showing the steps of Example 1 in the manufacturing process of a phase shift mask. FIG. 2(a) and FIG. 2(b) are cross-sectional views each showing a configuration example of a conventional phase shift mask. FIG. 3 is a diagram showing the problem. FIG. 4 is a diagram explaining the principle of a phase shift mask. DESCRIPTION OF SYMBOLS 1... Substrate, 10... Light blocking part, 11... Phase shift part, 11'... Phase shift material film, 12... Light transmitting part, 2'... Photoresist layer, 2... ...Resist pattern.

Claims (1)

[Claims] 1. A method for manufacturing a phase shift mask including a light blocking portion, a light transmitting portion, and a phase shifting portion on a transparent substrate, the method comprising: providing a light blocking portion on a first main surface of the transparent substrate; forming a phase shift material film on the light shielding part, further forming a negative photoresist layer thereon, and then irradiating light from the second main surface to remove the photoresist using the light shielding part as a mask. The layer is exposed and patterned to form a resist pattern, and the phase shift material film is isotropically etched using the resist pattern as a mask, thereby forming a light transmitting part between the light shielding part and the phase shift part. A method for manufacturing a phase shift mask to obtain a phase shift mask.