JPS5885433A - Photomask - Google Patents

Abstract

PURPOSE:To ensure prevention of deviation or displacement of a repeat due to heat expansion of the substrate of a photomask for forming a pattern of a magnetic bubble memory element, by using a gallium-gadolium-garnet substrate for it. CONSTITUTION:A G.G.G substrate for forming a magnetic bubble memory element (wafer) has far UV transmittance shown as characteristic curveIsimilar to that II of guartz glass, and it has sufficient transmittance. The photomask substrate is formed by using the G.G.G substrate as same as the wafer in material from the view point of said fact.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photomask, particularly a mask substrate for a photomask for forming a pattern of a magnetic bubble memory element.

Generally, various glass substrates are used as photomask substrates, and in particular, quartz glass substrates that absorb little deep ultraviolet rays are used for deep ultraviolet exposure for forming fine patterns of magnetic bubble memory elements.

However, the substrate for magnetic bubble memory devices is usually a gallium-gadolinium-garnet substrate (hereinafter simply CG).
, G substrate), and this G.

G, G, thermal expansion coefficient of the substrate (8,0XIO-6) and thermal expansion coefficient of the quartz glass substrate for mask formation (0,5X10
-6), there was a problem in that beat deviation of the transferred pattern was likely to occur due to deviations (variations) in the ambient temperature during exposure. For this reason, conventionally, when forming a fine pattern with a minimum dimension of approximately 1 μm, the temperature of the wafer and photomask is maintained at approximately ±05°C when aligning the mask over the entire surface of the wafer with high precision. V-peat slippage was completely prevented.

Therefore, an object of the present invention is to provide a photomask that enables highly accurate mask alignment commensurate with the miniaturization of patterns using deep ultraviolet exposure and X-ray exposure in pattern formation of magnetic bubble memory elements. .

The present invention will now be described in detail.

The present invention provides a magnetic bubble memory element that forms a magnetic bubble memory element.

We focused on the fact that the far-UV transmittance of the G,G substrate (wafer), as shown by the characteristic ■ in Figure 1, is almost the same as and sufficiently transmittance of the far-UV transmittance of the quartz glass substrate, as shown by the characteristic ■. G, where the mask substrate is made of the same material as the wafer;
It is formed using G and G substrates.

Figure 2 shows the temperature deviation (
This is a diagram showing the amount of deviation in rebeat due to variations in
The vertical axis shows the reheat shift amount on the wafer per 5 crn, and the horizontal axis shows the temperature of the photomask and the wafer. In the figure, the characteristic T shown by a solid line is a photomask made of a GGG substrate according to the present invention, and the characteristic (2) shown by a dotted line is a photomask made of quartz glass. In this case, the experiment was conducted using a 2001 HRZ mask aligner manufactured by KASPER.
,G.

A G wafer was used. The amount of deviation was measured using an optical microscope after forming a pattern including a scale. In this case, the resolution of this measurement is ±0.1μ
It is m. As is clear from the figure, it is possible to reliably suppress V-beat shift due to deviations (variations) in ambient temperature during exposure.

As explained on stage, the present invention can reliably prevent deviations in rebeat due to thermal expansion, making it possible to perform high-precision mask alignment over the entire wafer surface, making it easy to create high-precision, high-quality fine patterns. It has extremely excellent effects.

[Brief explanation of drawings]

Figure 1 shows a quartz glass substrate, G. G. FIG. 2 is a characteristic diagram showing the light transmittance of the G substrate with respect to wavelength, and FIG. 2 is a characteristic diagram showing the amount of repeat shift due to temperature deviation (variation).

Claims (1)

[Claims] 1. A photomask for pattern formation of a magnetic bubble memory element, characterized in that a gallium gadolinium garnet substrate is used as the mask substrate.