JPS6077421A - Alignment pattern - Google Patents

Abstract

PURPOSE:To generate general purpose alignment pattern and transfer it with high accuracy by providing, in the side of mask, the contour figure wherein the L-shaped patterns in different sizes are arranged proportionally and symmetrically. CONSTITUTION:A plurality of contour figures 12 are sequentially formed proportionally and symmetrically to the internal circumference from the external circumference with the scaling and then apertures are formed. Thereby, a pattern image 11 for alignment of masks 1 formed like a letter L. This shape corresponds to the pattern image for alignment of substrate 2 formed in different size indicated by the dotted line and alignment can be realized easily at a high speed. When the pattern image 14 where apertures 15 are radially formed is used, the overlapped pattern portions are reduced, making easier the alignment.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a batch exposure method in photolithography technology, and particularly to a pattern shape for alignment formed on a mask or a reticle.

(b) Technology background With the development of microfabrication technology, in the VLSI field, 1.2~
Microfabrication with a cage width of 1.5μ is required. Conventional photo I + lithography (optical flag light) technology cannot provide sufficient support, so a mixed aligner method is used in which high-precision full-size professional equipment, reduction type projection aligners, etc. are combined with each other for transfer. For example, in a reduction projection forming device, the pattern on the reticle is usually stepped and repeated at a reduction ratio of 10:1.
In this method, projection exposure is performed one shot at a time for each chip, which enables precise image transfer on the OJ, but on the other hand, throughput requires a considerable amount of time. For this reason, this method is optimal for pattern transfer that requires high precision, and for patterning that does not require high precision, a mixed exposure method that increases processing efficiency by using a contact aligner or a projection aligner that forms an image at the same magnification is generally used. used. In either method, a fine pattern precisely drawn on a mask or reticle is transferred onto a wafer, so alignment is a serious problem.

(el) Prior Art and Problems Figure 1 is a plan view showing the alignment of the mask and semiconductor substrate, and Figure 2 is an enlarged view showing the conventional pattern image aligned in Figure 1. In FIG. 1, a fine pattern precisely drawn on a mask 1 is transferred onto a substrate 2, but considerable precision is required for positioning the mask 1 and the substrate 2.

Fine Ni, @! , when patterning a wiring layer, strict precision is required for positioning when performing fine wiring with a pattern width of 1 to 2 μm in the wiring layer.

Therefore, in order to improve throughput and obtain alignment accuracy, we combined coarse alignment and precise alignment.
The step method is effective.

Usually, for rough alignment, a monitor chip 3 is provided at the center and periphery of the mask 1 and substrate 2, a special pattern image 3' as shown in the figure is drawn on this monitor chip 3, and these pattern images are superimposed. Next, for precise positioning, the pattern images drawn on the alignment chips 4 shown by diagonal lines provided at left-right symmetrical positions are superimposed to align the mask 1 and the substrate 2, and the position is precisely corrected using a microscope. Highly accurate pattern transfer is possible by batch exposure after combining. Figure 2 shows a specific example of rectifying position alignment by overlapping alignment patterns, and shows the position alignment chip 4 on the mask.
The pattern image 5 in which the outline figure shown by the body line is drawn is aligned with the alignment pattern image 6 provided on the substrate.

In this case, the pattern images formed are of the same shape, and 4
Comparing the pattern image 6 on the mask with the pattern image 6 on the fli, the pattern llTi1 image on the mask is proportionally and symmetrically reduced in size, and the above-mentioned monitor chip is superimposed and coarsely aligned to create a pattern image as shown in the figure. A map of the location can be obtained. The position between these images is corrected visually using a microscope, that is, by correcting the edge of the pattern image (the distance from the mask side to the pattern on the substrate, for example, a = b, c = d). Accurate 1XL fitting is possible.

However, the pattern 1ilii image 5 formed on the mask side is defined by the size VC of the pattern IIjIl 6 formed on the substrate, so that versatility cannot be obtained. For example, in patterning an electrode wiring layer of a frost-proof one-body separation structure, in which a diffusion layer with a separation structure is formed on the back surface of the substrate, the main surface of the substrate is reversed and polished to form a polar shadow, the size of the alignment pattern is It often happens that the position changes due to the polishing process in the middle of the process and cannot be handled by the alignment pattern on the mask side. Visual errors may occur if the spacing is too narrow or too wide. Or it
, fz will match, resulting in an apparent match of 14, making fine correction impossible.

Purpose of the Invention In view of the above, an object of the present invention is to provide a versatile mask-side alignment pattern and to transfer a highly accurate circuit pattern onto a substrate.

(e) Structure of the Invention According to the present invention, the pattern on the mask side for aligning the mask having the transferred pattern to be transferred onto the sample and the sample is L-shaped with different sizes. This is achieved by forming a contour figure that is arranged proportionally and symmetrically.

(f) Embodiment No. 3 of the invention is a plan view showing the alignment pattern shape according to an embodiment of the present invention, and FIG. 4 is a plan view of the alignment pattern shape showing another embodiment of the invention. be.

Fugu 1F 1F 1F Thousand Roro VR A FAT's brain, two -per -two -percent tax 12T, familiar, and inner circumference ζ ζ ζ ゛ ゛ ゛ ゛ ゛The pattern image 11 has a specific shape, for example, with a pattern width of one side and a pattern interval of 4 μm each, and an outer shape of about 50 μm.
The opening is 80μ and the opening 13 is 10 to 20μ.

By adopting such a shape, it is possible to correspond to the substrate pattern image 14 which is cut in a shape I with different pattern sizes shown by dotted lines.

That is, when aligning two patterns using a microscope, patterns can be mutually selected under optimal conditions, making alignment easier than before, and faster alignment processing can be expected.

FIG. 4 shows a pattern image 14 in which openings 15 are formed radially, so that the number of negative pattern parts is reduced, and alignment becomes easier.

(g) Effects of the Invention As explained in detail above, the mask alignment pattern image according to the present invention can respond to changes in the substrate alignment pattern image, increasing versatility and enabling high-speed alignment. It is effective in improving the output of batch exposure equipment.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a state in which a mask and a semiconductor substrate are aligned; FIG. 2 is an enlarged view showing a conventional pattern image for alignment in FIG. 1; and FIG. FIG. 4 is a plan view showing the alignment pattern shape according to the embodiment.
The figure is a plan view of an alignment pattern shape showing another embodiment of the present invention. In the figure, 1...mask, 2... semiconductor substrate, 3
...Monitor chip, 4...Tip for positioning, 5゜11.14...Pattern image for positioning (mask side), 6...Pattern i[1ll
IJ! (board side), 12...contour figure, 13.
15...Opening.

Claims (1)

[Claims] A pattern on the mask side for aligning a mask having a transferred pattern to be transferred onto a sample and the sample is formed of a contour figure in which L-shapes of different sizes are arranged proportionally and symmetrically at the four corners. An alignment pattern characterized by