JPS58194032A - Raw material of photomask having transparent conductive layer - Google Patents

Abstract

PURPOSE:To enhance adhesion between the interlayers of a photomask and to obtain a photomask material having a transparent conductive layer small in occurrence of defects during a washing step, by forming a thin chromium oxide layer as an adhesive layer between a transparent electrode layer and a chromium layer. CONSTITUTION:A base 15 is fixed to a holder, placed into a sputtering chamber, the chamber is evacuated a gaseous mixture of 3:2 Ar and O2 is introduced, and the base 15 is heated to 200 deg.C. The transparent electrode layer 1 composed mainly of tin oxide is formed to 30nm thickness by the DC magnetron method using tin as a target. The gaseous mixture is changed to 4:1 Ar/O2, a 5nm thick chromium oxide layer 4 is formed on the layer 1 using chromium as a target, then the gaseous mixture is changed to 100% Ar, and a 70nm thick chromium layer 2 is formed on the layer 4. The gas is again changed into a mixture of 4:1 Ar/O2, and a 25nm thick chromium oxide layer 3 is formed by sputtering chromium.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in photomask materials used in the manufacturing process of semiconductor devices and the like.

In the manufacture of small electronic circuits such as semiconductor devices, one of the most important steps is to create a pattern of a desired shape using photolithography.

The precision of this process is the main factor governing the degree of refinement achieved. Therefore, with the miniaturization and high density of electronic circuits, photomasks have shifted from emulsion masks to hard masks, and pattern transfer techniques have changed from conventional ultraviolet contact exposure to projection exposure and deep ultraviolet exposure. Various proposals have been made. Etching technology is also shifting from the conventional wet processing method to the dry processing method.

Hard masks have come to be widely used as photomasks due to their high strength, low defects, and long lifespan. However, on the other hand, hard masks have drawbacks such as pattern defects due to static electricity charging. Ta. In order to compensate for this drawback, a photomask material in which a transparent conductive layer is provided on a base substrate has been proposed.

An example of the photomask material with the transparent conductive layer is shown in FIG.

In FIG. 1, a chromium layer 2 is formed on a thin layer 1 of indium oxide and/or tin oxide, and a chromium oxide layer 3 is further formed thereon as an antireflection layer. However, although the chromium layer 2 has a very strong adhesion force to the glass substrate 5, the adhesion force to the indium oxide or tin oxide thin layer 1 is very small. The formed photomask may peel off or develop pinholes during use or during a cleaning process, increasing defects.

The purpose of the present invention is to improve the above-mentioned drawbacks, improve the adhesion between the transparent conductive layer and the mask layer, which are provided to prevent pattern defects due to electrostatic charging, and prevent the occurrence of defects during use and cleaning processes. The objective is to provide a photomask material with excellent practical durability.

The purpose is to provide a transparent conductive layer, which is characterized in that a transparent and conductive thin film is provided on a substrate, a chromium oxide or chromium nitride layer is provided closely thereon, and a chromium layer is further provided on top of the chromium oxide or chromium nitride layer. This can be achieved by using a photomask material.

As a result of research experiments to eliminate the above-mentioned drawbacks, the present inventors have found that the chromium oxide layer and the chromium nitride layer have a large adhesion force to the above-mentioned transparent conductive layer and the like.

Based on the above knowledge, the chromium oxide or chromium nitride layer may be a very thin layer, for example, a film thickness of about 50A will have sufficient practical effects.

1 The structure of the photomask material of the present invention is shown in cross section in FIG. A transparent conductive layer l is coated on a substrate 5, a chromium oxide or chromium nitride layer 4 is provided on the transparent conductive layer 1, a chromium layer 2 is provided as a mask layer on top of the chromium oxide layer 4, and an oxidized chromium layer 2 is provided as an antireflection layer on top of the chromium layer 2 as required. A chromium layer 3 was provided. Note that the layer 4 functions as an adhesive layer for the chromium layer 2 and the transparent groove N layer I.

The substrate of the present invention only needs to be transparent to exposure light, and is not limited to a general glass plate. For example, quartz or synthetic resin may be used depending on the allowable temperature range for manufacturing and use. Regarding the transparency of the substrate, any material that is sufficiently transparent to exposure light may be used.

The transparent conductive layer used in the present invention is made of indium oxide or tin oxide, and is usually made of indium, tin, etc. It can be formed on a substrate by vapor deposition, sputtering, etc. in an atmosphere containing elements. Further, its transparency may be as long as it is transparent to exposure light.

The chromium, chromium oxide, and chromium nitride layers of the photomask material of the present invention can be created by vapor deposition and sputtering, and if chromium, chromium oxide, or chromium nitride is the main component, a small amount of impurity or property improvement can be used without any problem. It may also contain additives such as carbon, boron, etc.

The transparent conductive layer-attached photomask material of the present invention produced as described above can be used to produce a photomask by the same process as conventional general hard mask materials.

That is, a photoresist suitable for the usage form is applied to the photomask material of the present invention, and after prebaking, the photoresist is exposed to active light and developed using a developer such as meta-gravel soda to form an image on the photomask material surface. expose. After washing with water, the exposed photoelectric material surface is dry-etched or wet-etched to prevent reflection/If'
) Oxide l:l A, the chromium layer of the mask layer and the chromium oxide or ffl chromium layer of the adhesive layer are removed by etching. At this time, the indium oxide or tin oxide layer of the transparent conductive layer remains because it has strong etching resistance, and exerts an antistatic function when used as a mask.

After etching, the photoresist is removed, and it is preferable to remove the photoresist by oxygen plasma ashing or the like for dry etching.

The thus obtained photomask with a transparent conductive layer has strong adhesion between the mask layer and the transparent conductive layer, and the film does not peel off during use or during the cleaning process, causing defects such as pinholes. There is no. Of course, since it has conductivity, pattern defects due to electrostatic charging will not occur.

Next, the present invention will be explained with reference to examples, but the present invention is not limited to the examples.

After the Example substrate is mounted on the holder of the sputtering tank, the inside of the sputtering tank is evacuated to a vacuum level of I.times.10'' Torr or higher. Next, a mixed gas of Ar and 0 at a mixing ratio of 3:2 is introduced to a pressure of around 3 m Torr.

After heating the substrate to 200° C., sputtering was performed by a DC magnetron method using tin as a target to form a 30 OA transparent conductive layer containing tin oxide as a main component. Next, after increasing the Ar and 0□0 mixing ratio to 4:l (2@Torr
Before and after), a chromium oxide layer was formed by sputtering using chromium as a target. Then the gas is Ar 10
0% (approximately 21 rLTorr), chromium was sputtered to form a chromium layer of 70 OA. Ar again
I would like to introduce a mixed gas of 4:1 and O3 at a mixing ratio of 2 m T.
orr), chromium was sputtered to form 25OA of chromium oxide.

Even when the photomask material with a transparent conductive layer obtained in this way was subjected to a tape peeling test using Scotch tape,
No peeling of the film was observed.

Further, even when scrubbing with a sponge brush was performed, almost no increase in pinholes was observed.

The above results are shown in FIG. 3 in comparison with the photomask material prepared using the conventional method. As is clear from the figure, in the photomask material of the present invention, as the degree of cleaning (time) increases, the generation of mohinhole remains at a constant V value.

As explained above, according to the present invention, by providing the thin layer 4 mainly composed of oxidized chlorine as an adhesive layer between the transparent conductive layer and the chromium layer, the adhesion of the mask layer is improved and the use of the mask layer is improved. It is possible to obtain a photomask material with a transparent conductive layer that has fewer defects during cleaning and cleaning processes.

[Brief explanation of the drawing]

Figure 1 - Photomask material with a transparent conductive layer made by the conventional method Figure 2 - Photomask material with a transparent conductive layer made by the present invention Figure 3 - Increase in defects when photomask materials prepared by the present invention and the conventional method are scrub-cleaned 2 is a transparent conductive layer, 2 is a mask layer (chromium layer), 3 is an antireflection layer (Il chloride chromium II), 4 is an adhesive layer mainly composed of chromium oxide or chromium nitride, and 5 is a substrate. Agent Yoshimi Kuwahara

Claims (1)

[Claims] A transparent conductive layer characterized in that a transparent and conductive thin film is provided on a substrate, a chromium oxide or chromium nitride layer is provided in close contact with the thin film, and a chromium layer is further provided in close contact therewith. Includes photomask material.