JPS59105648A - Composite reticule - Google Patents

Abstract

PURPOSE:To improve the superpositional accuracy and dimensional accuracy in the manufacture of a master mask and exposing of a wafer by arranging regularly plural kinds of photoetching patterns on hard glass. CONSTITUTION:A-D which are the patterns to be used in different photoetching stages for the same chip are disposed on a composite reticule 11. The other patterns except the pattern A of six pieces in the 1st line on the reticule are masked by an aperture 28 and the respective chip parts over the entire part of the wafer are exposed in the same pattern by a step and repeat system. The pattern B is then exposed and similarly the wafer is exposed in said pattern. The photoetching patterns in the respective stages can be exposed without replacing the reticule in the above-mentioned way. Since the accuracy of plural kinds of the patterns in the reticule is high, the superpositional accuracy, dimensional accuracy, etc. are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a reocurter used in microfabrication performed during the fabrication of semiconductor components, and particularly to a hard mask produced by an electron beam exposure apparatus.

[Technical background of the invention]

In the manufacture of semiconductor devices, microfabrication is performed as an application of optical etching, so a photomask is required. This photomask is one in which a light-shielding image is formed on transparent glass, and is broadly classified into emulsion masks using high-resolution dry plates and hard masks using inorganic thin film materials.

When creating a photomask, generally, a reticle with a 10x image is created first.

This reticle is manufactured using an optical drawing method, in which a variable slit is projected and reduced onto a photosensitive material using a lens while adjusting the data and force, or an electronic drawing method is used, in which a hard reticle is directly produced by drawing on a photoresist using electron beam scanning. It is done using beam writing method.

The thus manufactured reticle is installed in a device called a photomask repeater, and a master mask is manufactured by accurately arranging each element while performing %0 projection exposure on a hard mask. This master mask is expensive, so
Normally, a work copy mask is produced by a contact exposure method and used in the actual photoetching process.

Furthermore, a method called a step-and-repeat method, in which a conventional optical reduction projection method is applied to an electron beam optical system, is used to directly expose a wafer from a reticle.

FIG. 1 shows an example of a conventional reticle. In the case of this reticle, FIG. 2 shows how a full-size master mask is produced using the peak of one layer of one chip.

That is, Zo projection exposure is performed from the reticle 1 to the hard mask 3 through the lens 2, and after the exposure is completed, the hard mask 3 is moved and projection exposure is performed again. By repeating these steps, the entire master mask is formed.

[Problems with background technology]

However, conventional reticles only incorporate one layer of patterns, and since reticles are manufactured for each layer, there are variations in size, pinch, etc. between reticles, and the master made using this When exposing a mask or a wafer directly, the more the number of times the reticle is aligned, the larger the error in alignment will be, and the difference in the coefficient of thermal expansion between the reticle and the positioning table will also cause dimensional errors. do.

The use of multiple reticles in a machine involves complicated work such as cleaning, replacing, and positioning the reticles, which complicates process control, and increases the possibility of dirt and foreign matter entering the product. There is a problem in that there is a high possibility that defects will occur in the master mask or wafer.

[Purpose of the invention]

Therefore, the present invention provides a reticle that can improve overlay accuracy and dimensional accuracy in master mask production and wafer exposure, does not require complicated work, and can reduce the occurrence of defects due to contamination of foreign matter. The purpose is to

[Summary of the invention]

In order to achieve the above object, in the present invention, patterns used in different photo-etching processes of the same chip are arranged on a single piece of hard glass, particularly aiming at improving overlay accuracy and dimensional accuracy. be able to.

[Embodiments of the invention]

Some embodiments of the present invention will be described below with reference to FIGS. 3 to 5.

FIG. 3 is a diagram showing the configuration of an embodiment of a composite reticle according to the present invention, and the reticle 11 has patterns A to be used for different photoetching processes on the same chip.
-/Each D is distributed in 4 rows with 6 pieces per row arranged in parallel. This arrangement is designed to minimize pinch errors and parallelism errors. FIG. 4 is a diagram showing the configuration of another embodiment of the composite reticle according to the present invention. This is an explanatory diagram showing how the wafer 21 is directly exposed to light using 6 different layer patterns A to D arranged in 2 rows and 3 columns. @2
4a, 24b and lenses 25a to 251El, etc., a stage 26 that is freely movable in the X direction and the Y direction, a support stand 27, etc., and the reticle 11 is inserted in the middle of the optical system together with the aperture 28. be done. FIG. 5(b) is a diagram showing the positional relationship between the reticle 11 and the aperture 28 when viewed from the source side.
Except for pattern 1, the rest are masked by the aperture 28. Therefore, in this state, only the fAl pattern will be exposed on the wafer. Since several hundred chips are formed on one wafer, in this apparatus, when one exposure is completed, the stage 26
Using a step-and-repeat method in which the wafer is moved a predetermined distance and the exposure is repeated, each chip portion over the entire wafer is exposed in the same pattern. About a certain layer
``/< After the sardine base of the turn, etching etc. are performed, and when performing the next photo etching etc., the positional relationship between the reticle 11 and the aperture 28 in the exposure device 22 is changed, and '
Similarly, the wafer is exposed using a step-and-repeat method so that the B'' pattern is exposed. By changing the positional relationship between the reticle 11 and the aperture 28 in this way, the photoetching pattern in each process can be changed by changing the reticle. If exposed to light, a black mark will appear.

FIGS. 6 and 7 show the results of comparing the accuracy when using the composite reticle according to the present invention with that of a conventional single pattern reticle.

FIG. 6 is a graph comparing the deviation when two patterns are overlapped using the composite reticle according to the present invention and the deviation when two types of conventional single reticle are overlapped in order. 'l represents the overlay deviation in the X direction, and FIG. 6(b) represents the overlay misalignment in the y direction.Furthermore, FIG. 7(a) shows the pitch variation for each chip in different patterns of the composite reticle of the present invention and Figure 7(b) is a graph comparing the distribution of pitch variations for each chip between reticles with a single pattern, and Figure 7(b) is a graph comparing the distribution of distance variations between adjacent chips in the same case.These graphs Therefore, by using the composite reticle according to the present invention, the accuracy was previously reduced to ±0.5μ for 100mm.
It can be seen that the dispersion has improved by more than a factor of 50 from about m.

In the above embodiment, there are four types of patterns included in the reticle, and the arrangement thereof is also limited, but the type, amount, and number of patterns included in the reticle can be arbitrarily selected. be able to.

In addition, the inclination reticle of the present invention can be used not only to directly optically expose a wafer as described in the embodiments, but also to manufacture a mask using an electron beam exposure device, allowing for the production of high-precision master masks. It is possible to manufacture.

〔Effect of the invention〕

As described above, if the composite reticle according to the present invention is used, patterns used in different photoetching processes are arranged in one reticle with highly accurate dimensions and pitches. There is no need to replace the reticles of multiple types M when manufacturing a wafer or exposing a single white wafer, and there is no need for complicated operations such as replacement, cleaning, and alignment. Since the reticle does not need to be replaced, it is not affected by thermal expansion due to temperature434+, and the multiple types of patterns inside the reticle have high accuracy, which improves overlay accuracy and dimensional accuracy in mask production and wafer exposure. etc. can be improved.

Furthermore, since the frequency of setting the reticle in the device is reduced, the chance of contamination with foreign matter such as dust is reduced, and the occurrence of defects due to group S contamination can be prevented and the yield can be improved. Furthermore, if multiple types of reticles are regularly arranged on one reticle, efficient inspection can be performed using an automatic defect inspection device. In addition, the number of reticles used is greatly reduced and the exposure process is simplified, so the manufacturing cost per 10 integrated circuits is reduced, which is especially advantageous for prototype products.

[Brief explanation of drawings]

Figure 1 is a diagram explaining a conventional single pattern reticle;
FIG. 2 is an explanatory diagram showing how a master mask is manufactured from a reticle, FIGS. 3 and 4 are diagrams showing an example of a composite reticle according to the present invention, and FIG. 5 is an explanatory diagram showing how a master mask is manufactured from a reticle. 6 and 7 are graphs showing the difference in product accuracy between the composite reticle according to the present invention and the conventional single pattern reticle. 1.11, 12... Reticle, 21... Wafer, 22... Exposure equipment row, 28... Aperture.

Claims (1)

[Scope of Claims] 1. A composite reticle characterized by having a plurality of types of photo-etched patterns regularly arranged on hard glass. 2. The composite reticle according to claim 1, wherein the plurality of types of photoetching patterns are a series of photoetching patterns used for each material for manufacturing semiconductor integrated circuits.