JP2871263B2 - How to make a polyphase phase shift mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask (reticle) used in a reduction projection exposure apparatus.

[0002]

2. Description of the Related Art As an example of a photomask using a plurality of phase shift amounts, the 51st Annual Meeting of the Japan Society of Applied Physics, 27p-ZG-5 (1990) pp. 492 (hereafter,
Reference 1).

In Reference 1, the thickness of the shifter is adjusted by EB.
The exposure amount is adjusted to actually create a photomask.
FIG. 5 shows an example. As shown in FIG.
A resist 21 is applied to the glass substrate 4 on which the light shielding portion 1 is formed by chromium patterning, and is irradiated with an electron beam. The arrow indicates an electron beam, and the length of the arrow indicates a difference in the intensity of the electron beam. The thickness of the shifter is adjusted as shown in FIG. 5B according to the difference in the intensity of the electron beam.

[0004] In addition, the 38th Annual Meeting of the Japan Society of Applied Physics, 29P-ZC-6 (1990) pp. 536
(Hereinafter referred to as Document 2) creates various types of shifters by patterning the shifters a plurality of times.

[0005]

In the method of Reference 1, a resist is used as a shifter, and the resist thickness after development is controlled by changing the exposure amount of an electron beam. The resist thickness depends sensitively on the exposure amount. Therefore, it is difficult to adjust the film thickness.
Also, it is not practical to use a resist as a shifter because of its low resistance.

In Document 2, the shifter is an oxide film having characteristics. However, since various shifters repeatedly perform patterning and etching, the formation of the shifter involves a plurality of steps, which complicates the operation.

An object of the present invention is to provide a method of producing a phase shift mask having a plurality of types of shifters capable of more accurately controlling the film thickness by using an oxide film or the like having a higher resistance than a resist as a shifter.

[0008]

According to a first aspect of the present invention, there is provided a method for forming a shifter of a phase shift mask having a plurality of types of shifters, wherein a chromium-patterned mask substrate is provided.
After forming a first shifter material having a thickness corresponding to the smallest phase shift amount, a mask for forming a shifter by an etching method and a resist as an etching stopper of an upper layer shifter are applied, and the resist is applied by electron beam exposure. And then forming a second shifter material having a thickness that is the difference between the thickness corresponding to the second smallest phase shift amount and the thickness of the first shifter material. It is characterized in that patterning is performed, and thereafter, this is sequentially repeated up to the required number of shifters, and finally various shifters are formed by one etching.

According to a second aspect of the present invention, there is provided a method for forming a shifter of a phase shift mask having a plurality of types of shifters. After applying a resist as an etching stopper, patterning it by electron beam exposure and forming it, repeating this process sequentially to the required number of shifters, and finally forming various shifters by one etching, and forming the phase Chromium is deposited on the shift mask substrate and patterned to form a light shielding portion.

[0010]

In the present invention, since the same resist film is used as a mask during shift formation and as an etching stopper for forming an upper layer shifter, the resist film thickness of each layer may be controlled to a film thickness corresponding to the shifter film thickness. . Further, after the shifters are stacked in multiple layers, the etching of the shifter film and the peeling of the resist may be performed only once, and the process is not complicated.

[0011]

1 and 2 are views showing a process of forming a phase shift mask according to the first invention. In the figure, 1
Is a light shielding portion made of chromium, 21, 22, 23 are resist portions, 31, 32, 33 are shifter layers, 4 is a glass substrate, 5
Is an etching stopper.

Here, the creation method will be specifically described.

First, as shown in FIG. 1A, an etching stopper 5 and a chromium layer are provided on a glass substrate 4 and chromium patterning is performed to form a light shielding portion 1 of chromium.

Next, as shown in FIG. 1B, a shifter film 31 corresponding to a phase shift amount of α ° is formed on the mask substrate having the chromium patterning.

Next, as shown in FIG.
1 is coated with a resist 21.

Next, as shown in FIG. 1D, a resist 21 is patterned on the α ° shifter film 31 by electron beam exposure.

Next, as shown in FIG.
2 is attached so that the phase shift amount combined with the shifter film 31 becomes β °. A resist 22 is applied thereon.

Next, as shown in FIG. 1F, a resist 22 is patterned on the shifter film 32 of β °.

Next, as shown in FIGS. 2 (g) and 2 (h), the shifter forming process is repeated for the required number of shifter types.
In the figure, 33 is a shifter film, and 23 is a resist.

After this patterning is completed for all shifters, etching is performed until the 0 ° shifter film is completely etched as shown in FIG. 2 (i). When the shifter film is completely etched, the etching is stopped by the stopper and the glass substrate 4 is not damaged.

Finally, by removing the resist,
A multi-phase shift mask having the structure shown in FIG.

FIGS. 3 and 4 relate to the second invention.
FIG. 5 is a diagram illustrating a method of forming a phase shift mask when a chrome pattern is formed on a shifter.

A specific description will be given of a preparation method.

First, as shown in FIG. 3A, an etching stopper 5, a shifter film 31 corresponding to a phase shift amount of α °, and a resist 21 are provided on a glass substrate 4.

Next, as shown in FIG. 3B, a resist 21 is patterned on the α ° shifter film 31 by electron beam exposure.

Next, as shown in FIG.
2 is attached so that the phase shift amount combined with the shifter film 31 becomes β °. A resist 22 is applied thereon.

Next, as shown in FIG. 3D, a resist 22 is patterned on the shifter film 32 of β °.

Next, as shown in FIG. 3E, etching is performed until the 0 ° shifter is completely etched. When the shifter film is completely etched, the etching is stopped by the stopper and the glass substrate 4 is not damaged.

Next, as shown in FIG. 4F, after stripping the resist, the shifter is patterned and chromium 1 is deposited. Next, a resist 23 is applied.

Next, as shown in FIG.
3 is patterned.

Next, as shown in FIG. 4H, the chromium 1 is etched.

Finally, as shown in FIG. 4 (i), by removing the resist 23, a multi-phase shifter mask having chromium as a light shielding portion on the shifter is prepared.

[0033]

According to the conventional method of manufacturing a phase shift mask, it is difficult to control the thickness of the shifter by the exposure layer of the resist and the etching time, but it is difficult to manufacture the shifter. A plurality of types of shifter portions can be formed by controlling the respective film thicknesses with high accuracy by a simple process.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the first invention.

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

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

FIG. 4 is a sectional view showing an embodiment of the second invention.

FIG. 5 is a drawing showing a manufacturing process of a conventional multi-phase shift mask.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light shielding part 21, 22, 23 Resist part 31, 32, 33 Shifter film 4 Glass substrate 5 Etching stopper

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-188140 (JP, A) JP-A-5-100409 (JP, A) JP-A-5-241318 (JP, A) JP-A-5-241 107732 (JP, A) JP-A-5-53290 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03F 1/00-1/16

Claims (2)

(57) [Claims] In a method for forming a shifter of a phase shift mask having a plurality of types of shifters, a first shifter material having a thickness corresponding to the smallest phase shift amount is formed on a chromium-patterned mask substrate. Thereafter, a mask for forming a shifter by an etching method and a resist as an etching stopper for the upper layer shifter are applied, the resist is patterned by electron beam exposure, and then a thickness corresponding to the second smallest phase shift amount is obtained. After forming a second shifter material having a thickness different from the thickness of the first shifter material, resist coating and patterning are performed in the same manner, and this process is sequentially repeated until the required number of shifters is completed. A method of forming a multi-phase shift mask, wherein various shifters are formed by etching. 2. A method for forming a shifter of a phase shift mask having a plurality of types of shifters, wherein a shifter material is formed on a glass substrate, and then a mask for forming the shifter by an etching method and an etching stopper of an upper layer shifter. The resist is applied and patterned by electron beam exposure. This is sequentially repeated until the required number of shifters is formed. Finally, various shifters are formed by one etching, and then the phase shift mask substrate created as described above is formed. A method for producing a polyphase type phase shift mask, comprising depositing chromium and patterning to form a light shielding portion.