JPH0770466B2 - X-ray mask and method of manufacturing the same - Google Patents

Description

The present invention relates to an X-ray mask used for measuring the sensitivity of an X-ray resist used for X-ray microfabrication in the manufacture of semiconductor integrated devices and the like, or an X-ray mask used for a development monitor, and The manufacturing method is related.

(Prior Art) Recently, in semiconductor integrated circuits, the miniaturization of semiconductor elements has remarkably progressed, and therefore, X-ray lithography technology has attracted attention for pattern formation. On the other hand, various X-ray resists (hereinafter simply referred to as resists) are being developed one after another for X-ray lithography technology, and it is necessary to evaluate their functions as quickly as possible.

Sensitivity and resolution are important functions of resist evaluation. Among them, the sensitivity evaluation involves exposing each of a plurality of resist-coated wafers to X-rays at various times and forming the development results into a sensitivity curve. I am going.

However, this method has a drawback in that a large number of wafers are prepared and each wafer is exposed to various different exposures over time. Recently, in order to eliminate the drawback, X-ray exposure is performed using an X-ray mask in which a plurality of patterns having different transmittances with respect to an X-ray source are formed, and a method of drawing a sensitivity curve by performing one exposure on one wafer Is proposed.

(Problems to be Solved by the Invention) However, it is difficult to carry out the above-mentioned method under the present circumstances because an appropriate means for forming a plurality of patterns having different transmittances has not been solved.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an X-ray mask and a method for manufacturing the same, which can easily draw a sensitivity curve of a resist and easily perform sensitivity evaluation.

(Means for Solving the Problems) The present invention is directed to the above object by forming a plurality of resist regions having different thicknesses on an X-ray absorber, and then forming the resist regions and the X-ray absorber immediately below the resist. This is achieved by a method of manufacturing an X-ray mask by dry etching a portion.

(Operation) According to the present invention, an X-ray mask for measuring the exposure sensitivity of the X-ray resist or monitoring the progress of development of the X-ray resist can be manufactured very easily.

(Embodiment) FIG. 1 is a diagram showing an X-ray mask according to a first embodiment of the present invention. FIG. 1A is a plan view and FIG. 1B is a sectional view taken along the line AA ′, in which 1 denotes an X-ray transmissive body, and a plurality of X-ray absorbers 2 having different thicknesses are formed on the upper surface thereof. Mask support 3
It is a configuration held on top of.

This X-ray mask is used as follows. That is, the X-ray mask is placed on the upper surface of the resist-coated wafer and X
When the line exposure and the development are performed, the thickness of the resist is formed differently due to the difference in the film thickness of each X-ray absorber 2. Therefore, the measurement result of the film thickness is drawn as a sensitivity curve, or The mask is used as a reticle and different types of chips between the element patterns are exposed by using an X-ray stepper to be used as a development monitor during the element pattern development.

FIG. 2 is a diagram showing a second embodiment, (a) and (b) are shown similarly to FIG. 1, and 4 is an X-ray mask pattern,
Other reference numerals are the same as those in FIG.

This is one in which a region in which a plurality of X-ray absorbers 2 having different thicknesses are arranged as shown in FIG. 1 is formed in one corner of the region in which the X-ray mask pattern 4 of the semiconductor element is formed on the X-ray transparent body 1. is there. This X-ray mask has an advantage that it greatly serves as a development monitor for the X-ray mask pattern 4 during development.

FIG. 3 is a process cross-sectional view showing the method of manufacturing the above-mentioned X-ray mask, 5 is a resist film, and the other reference numerals are the same as those of the previous drawings.

To manufacture the X-ray mask of the present invention, first, a silicon nitride (SiN) film having a thickness of 2 μm is formed as an X-ray transparent body 1 on a mask support 3 usually composed of a silicon substrate. Then, a tungsten (W) film having a thickness of 0.6 μm is formed as the X-ray absorber 2. On top of that, for example, chloromethylated polystyrene (CMS) is used as the resist film 5.
Was coated in a thickness of 0.6 .mu.m, 110 ° C., a size of 50 [mu] m × 50 [mu] m after performing the pre-baking treatment for 20 minutes, and the electron beam geometrically varied from 1 [mu] C / cm ² to 50 .mu.C / cm ² and It is exposed and 100 squares are drawn (Fig. 3 (a)).
In addition, in FIG.
Only B, C, D and E are shown.

Next, a pattern is formed by developing with a solution of isoamyl acetate and ethyl cellosolve in a ratio of 1: 3 for 1 minute. At this time, the resist is completely left in the portion having a large exposure amount, the resist remains in the portion having a small exposure amount according to the exposure amount, and the resist is completely removed in the unexposed portion (FIG. 2B). ', B', C ', D',
E'is exposures A, B, C, D, and
The remaining resist area corresponding to E is shown.

Next, using a parallel plate type etching system, SF ₆ was used as the etching gas, and the high frequency power density was 0.3 W / cm ² and the pressure was 15 m.
The X-ray absorber 2 of the tungsten film is etched under the condition of Torr. If the etching time is set so that the etching of the tungsten film of the X-ray absorber 2 is completed when the resist region A ′ having the maximum remaining film thickness is removed by etching, the etching time is set according to the remaining film thickness of the resist. As the X-ray absorber 2 having different thickness, a tungsten film is formed as shown in FIG. A ", B", C ", D",
E ″ is the remaining tungsten film and corresponds to the remaining resists A ′, B ′, C ′, D ′ and E ′. After that, the central portion of the silicon substrate of the mask support 3 is etched from the back surface. If removed, an X-ray mask as shown in Fig. 3D is completed .. In the dry etching of the tungsten film of the X-ray absorber 2, the resist film thickness is made equal to that of the resist film by making the etching rate equal to that of the resist film. However, there is an advantage that it is directly transferred to the tungsten film of the X-ray absorber 2.

(Effects of the Invention) As is apparent from the detailed description above, the present invention can easily configure an X-ray mask in which the X-ray exposure amount changes in fine steps. Since it can be used as a resist sensitivity evaluation or as a development monitor at the time of resist development, it can be used for forming an X-ray pattern accompanying the recent miniaturization of semiconductor elements, and can exert an extremely large effect.

[Brief description of drawings]

1 and 2 are respectively a plan view and a cross-sectional view showing the first and second embodiments of the present invention, and FIG. 3 is a cross-sectional view of the manufacturing process of the X-ray mask of the present invention. 1 ... X-ray transmitter, 2 ... X-ray absorber, 3 ... Mask support, 4 ... X-ray mask pattern, 5 ... Resist film.

Claims (4)

[Claims] 1. An X-ray mask comprising an X-ray transmissive body such as a semiconductor substrate as a mask substrate, and a plurality of X-ray absorbers having different X-ray transmissivities formed on the surface thereof. 2. A plurality of X-ray absorbers having different transmittances,
The X-ray mask according to claim 1, which is formed on the same substrate as the X-ray pattern of the element. 3. A step of forming a plurality of resist regions having different thicknesses on the X-ray absorber and then dry etching the resist regions and a part of the X-ray absorber immediately below the resist. X-ray mask manufacturing method. 4. The method of manufacturing an X-ray mask according to claim 3, wherein the etching rate for the resist region and that for the X-ray absorber are made equal, and dry etching is performed.