JP2660128B2 - Method for manufacturing phase change 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 method of manufacturing a mask used in a manufacturing process of a semiconductor device, and more particularly, to a method of precisely controlling the thickness of a phase change film so that there is no difference in light intensity.
The present invention relates to a method for manufacturing a phase change mask capable of improving a side wall structure of a film.

[0002]

2. Description of the Related Art In general, light passing through a mask has a phase difference due to a change in the thickness of the mask through which the light passes.

[0003] A mask capable of obtaining light having different phases is called a phase change mask. That is, as shown in FIG. 1C, when the thickness of the phase change film 1 becomes different, as shown in FIG. Since the electric field of the light (LT) and the electric field of the light (LT) passing through a thin portion have different phases, the light intensity is as shown in FIG. Here, reference numeral 2 denotes a light blocking film.

In the conventional method of manufacturing a phase change mask as described above, in order to accurately adjust the thickness of the phase change film, a quartz layer which is a base layer of the film is directly etched by a normal dry etching method. Although there is a method, as shown in FIG. 2, since the etching rate changes with respect to the etching area ratio, the etching is actually performed after estimating about 80 to 90% of the etching amount in the primary etching. The depth of etching with a stylus profiler
This is a method in which measurement is performed by a method of directly contacting with a profiler or the like, and the residue is secondarily dry-etched.

[0005]

However, in such a method of manufacturing a phase change mask, since the etched depth is measured by a direct contact method, not only is the accuracy inferior, but also the position to be measured and actual Since the accurate measurement of the etched depth is fundamentally impossible because of the difference between the measured area and the accuracy of the etched depth, there is a disadvantage that the accuracy of the etched depth is inferior. Since the density varies depending on the position, there is a disadvantage that the uniformity of etching is not very good. In order to eliminate such a defect, a third substance ES (Si) is provided between the underlayer 11 and the phase change layer 12 of the phase change film as shown in FIG.
₃ N _4, add the _Al 2 _{O 3,} or the like), an etch stop layer E
Although a method of manufacturing a phase change mask used as S has been proposed, this method has an advantage that etching can be performed at an accurate depth, but the refractive index of the etching stop layer ES is limited to the underlayer 11 or the phase change mask. Different from the refractive index of the layer 12, there is a disadvantage that the transmittance changes due to the difference in the refractive index between the respective layers and a difference in light intensity occurs, and the manufacturing process is complicated.

[0006] The present invention is intended to eliminate the drawbacks which the conventional phase change mask manufacturing method has, by etching in combination with dry etching and wet etching, the side wall of the film vertical It is an object of the present invention to provide a method for manufacturing a phase change mask, in which the etching depth is accurately adjusted while maintaining a uniform light intensity.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a phase change mask according to the present invention will be described below with reference to the drawings.

FIGS. 4A to 4D are views for explaining a method of manufacturing a phase change mask according to the present invention. As shown in FIG. A phase change film 22 of about 3800 ° is formed on the substrate 21 by a plasma CVD method.
Thickness (when applying i-ray photolithography with a wavelength of 365 nm)
365 nm / [2 · (N−1)] thickness; N is a refractive index)
The light shielding film 23 of chromium (Cr) or the like is formed on the phase change film 22 by a sputtering method.

Next, as shown in FIG. 1B, a photoresist 24 is applied on the light blocking film 23, and the photoresist 24 is subjected to a photolithography method (Lithograph).
patterning by y method)
Then, a part of the light shielding film 23 is etched by a normal etching method. Thereafter, the photoresist 24 is removed.

Further, as shown in FIG. 1C, a photoresist 25 is applied to the entire surface and the photoresist 2 is applied.
After patterning by 5 the photoetching method, a dry etching which is an active ion etching with an etchant (CF _4), a portion of the phase change film 22, based on the etching area ratio of 2, the total etching amount 80 ~
Anisotropic etching is performed for about 90% (a depth of 3500 ° to 3700 ° from the surface).

Next, as shown in FIG. 1D, an etching agent (usually HF or NH ₄ F and CH ₃ COO) is used.
H ) (mixture with H ) and the remaining portion R of the phase change film 22 by wet etching (20 to 10% of the total etching amount).
Is isotropically etched.

At this time, the etching rates of the chromium light shielding film 23 and the quartz layer 21 are 10 ° / min and 5
At about 00 ° / min, the etching rate of the phase change film 22 is about 5000 to 9000 ° / min. Accordingly, the phase change film 22 can be wet-etched with an accurate thickness while maintaining the sidewall inclination of the phase change film 22 formed at the time of dry etching vertical. After the wet etching, the photoresist 25 is removed to obtain a desired phase change mask.

As described above, in the phase change mask manufactured by the method of the present invention, when the phase change film is etched, for example , 80 to 90% of the total etching amount is dry-etched and the remaining 20 to 10% is etched. Is manufactured by wet etching, so that the accuracy of the etched depth is high and the uniformity of the thickness of the phase change film can be maintained. Since there is no difference between the rates and the rate of change of transmitted light is minimized, there is an advantage that uniform light intensity can be obtained.

[Brief description of the drawings]

FIG. 1 is a view for explaining the principle of a phase change mask.

FIG. 2 is a graph showing a change in an etching rate with respect to an etching area ratio.

FIG. 3 is a view for explaining a method of manufacturing a conventional phase change mask using an etching stop layer.

FIG. 4 is a diagram illustrating a method of manufacturing a phase change mask according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Phase change film 2 Light blocking film 21 Underlayer 22 Phase change layer 23 Light blocking film 24 Photoresist 25 Photoresist

Claims (3)

(57) [Claims] 1. A phase change film (22) on an underlayer (21).
And a light blocking film (2) is formed on the phase change film (22).
After forming 3), a part of the light blocking film (23) is etched by a normal etching method using a first patterned photoresist (24), and the phase deposited on the underlayer is removed. A part of the phase change film (22) is partially etched by using a second patterned photoresist (25) in a thickness direction by a dry etching method, and then is further etched by a wet etching method. A method for manufacturing a phase change mask, comprising etching a part of the residual portion. 2. The method according to claim 1, wherein the dry etching is performed by anisotropic etching for about 80 to 90% of the total etching amount of the phase change film. 3. The wet etching includes an etching agent H.
2. The method according to claim 1, wherein the etching is performed by isotropic etching using F or using a mixture of NH ₄ F and CH ₃ COOH.