JPS6212503B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing masks, particularly hard masks such as chrome.

The first method for manufacturing this kind of hard mask is
Shown in Figures A to D. That is, first, a mask layer 2 of chromium or the like is formed on a transparent glass substrate 1 by vapor deposition or the like (FIG. 1A), a resist 3 is applied onto the mask layer 2, and a desired pattern is formed using light or electron beams. A prescribed pattern is formed by drawing and development (FIG. 1B). Using this resist 3 as a mask, the mask layer 2 is selectively removed by gas plasma etching or ion etching to create openings 4 (FIG. 1C). Finally, the remaining resist 3 is removed to obtain a desired hard mask.

In recent years, when manufacturing semiconductor devices, especially semiconductor devices that require fine patterns, hard masks such as chromium used in the photolithography process can be made of thinner materials than conventional emulsion masks. Although it has great advantages such as making it possible to miniaturize the pattern and increasing its lifespan, etching technology for hard mask materials such as chromium has been important.

Taking chromium as an example, conventional etching methods include ceric ammonium nitrate [Ce(NH ₄ ) ₂
Wet chemical etching using chemicals such as a mixed aqueous solution of (NO ₂ ) ₆ ] and perchloric acid [HClO ₄ ] has been applied, but recently this etching technology has progressed, and gas plasma etching or ion etching has been applied. Dry etching techniques have been developed and are being used, and ion etching is particularly effective in manufacturing high-precision masks as a technique for obtaining sharp pattern edges and small distribution of variations within the mask. However, when the above-mentioned dry etching method is applied, the resist as a mask, especially the electron beam resist that has come to be used in microfabrication in recent years, has poor dry etching resistance due to heat generated by plasma or ion collision, etc. When the etching of hard mask materials such as these is completed, large film loss of the resist makes it difficult to finally produce a fine pattern mask, as seen in FIGS. 1C and 1D.

The present invention aims to improve these conventional drawbacks in manufacturing hard masks, and below, examples of the method of the present invention will be described with reference to FIGS. 2A to F, 3A and B, and 3D. This will be explained in detail with reference to FIGS. 4A and 4B.

FIGS. 2A to 2F show an embodiment of the method of this invention in the order of steps. That is, first, a photoresist such as AZ1350 or an electron beam resist 13 such as PMMA is applied on a mask layer 2 of chromium or the like formed by vapor deposition on one surface of a transparent glass substrate (Fig. 2A), and this is prebaked. After that, a high-sensitivity electron beam resist 14 such as PGMA or COP is applied, a desired pattern is drawn thereon using an electron beam (Fig. 2B), and this electron beam resist 14 is developed. Patterning (Figure 2C). For example, in the case of PGMA, this development is performed using a mixed solvent of methyl ethyl ketone (MEK) and ethyl alcohol.

Next, this patterned electron beam resist 1
4 as a mask, and the electron beam resist 1 below it.
3 is developed or dissolved and patterned in the same manner (FIG. 2D). For example, in the case of AZ, this development is performed with an alkaline solution after irradiation with ultraviolet rays, and in the case of PMMA, it may be removed with methyl isobutyl ketone (MIBK) or the like after irradiation with X-rays. Continuing again,
Thereafter, the mask layer 2 made of chromium or the like is etched using mixed gas plasma containing a halogen element such as chlorine and oxygen, reactive sputtering, or argon ion etching (Fig. 2E), and finally patterned. The resists 14 and 13 are removed to obtain the desired hard mask (FIG. 2F).

As described above, the method of the embodiment shown in FIG. 2 enables dry etching of hard mask materials such as chromium by using an electron beam resist such as AZ, which has good heat resistance, as the lower layer as an etching mask. be. In other words, used for the lower layer
The plasma resistance of AZ1350 is approximately 10 nm/min, and the sputter etching resistance is approximately 20 nm/min, which is better than other resists. In this example, AZ1350 can be used as an electron beam resist, but its sensitivity is as low as about 10 ^-5 C/cm ² .
By layering a highly sensitive electron beam resist on top of this, it is possible to perform pattern processing using electron beams at high speed.In this way, the top layer is a highly sensitive resist, and the bottom layer is a resist with good dry etching resistance. By using multiple layers, precise microfabrication can be achieved in a short time, and a high-quality hard mask with less variation, which is a feature of dry processing, can be manufactured.

The method of the above embodiment is applicable to the silicon dioxide (SiO ₂ ) film 22 and the aluminum (Al) layer 23 formed on the surface of the semiconductor substrate 21, as shown in FIGS. 3A, B and 4A, B. It can be applied as is to dry etching processing, and similar effects can be expected.

As described in detail above, when using the method of the present invention, a resist with good heat resistance is used as the lower layer and a highly sensitive resist is used as the upper layer, so that dry etching can be performed with high accuracy and uniformity. Moreover, it is possible to manufacture a high-quality hard mask without defects such as pinholes.

[Brief explanation of the drawing]

1A to 1D are cross-sectional views showing a conventional hard mask manufacturing method in the order of steps; FIGS. 2A to 2F are sectional views showing an embodiment of the hard mask manufacturing method according to the present invention in the order of steps; Figures A and B and Figures 4A and 4B are cross-sectional views when the method of the present invention is applied to the manufacture of semiconductor devices. 1... Transparent glass substrate, 2... Mask layer such as chromium, 13... Highly sensitive resist, 14... Heat resistant resist.

Claims (1)

[Claims] 1. A step of sequentially forming and applying a mask layer made of a hard mask material, a heat-resistant resist layer, and a highly sensitive electron beam resist layer on a transparent glass substrate;
A step of drawing the high-sensitivity electron beam resist layer into a desired pattern with an electron beam and then developing and patterning it; and developing or dissolving the heat-resistant resist using the patterned resist layer as a mask. A method for manufacturing a hard mask, comprising the steps of patterning in the same manner, and selectively etching and removing the mask layer using each of the patterned resist layers as a mask. 2. The method of manufacturing a hard mask according to claim 1, wherein the etching is a dry etching process such as plasma, sputtering or ion etching.