JPH0451967B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a patterned substrate on which a continuous or uninterrupted pattern of a relatively large area is formed.
In particular, the present invention relates to a relatively large-area pattern-formed substrate on which continuous patterns are formed for use in manufacturing liquid crystals, integrated circuits, CCDs, line sensors, and the like.

[Prior art and problems to be solved by the invention]

In recent years, in the field of manufacturing the above-mentioned liquid crystals, integrated circuits, CCDs, line sensors, etc., it has been desired to form continuous or uninterrupted patterns over large areas.

Especially in the field of CCD and line sensors,
It is strongly desired to form a continuous rectangular pattern over a large area.

To ensure pattern continuity, it is most convenient to form an integrated pattern on a large area substrate using a single mask of the same size, such as by optical lithography.

However, although large-area substrates can be made without particular difficulty, manufacturing large masks is difficult to realize. This is mainly due to technical difficulties and the associated increase in manufacturing costs.

An object of the present invention is to provide a patterned substrate on which a continuous pattern of relatively large area is formed.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention divides a region of a substrate where a continuous pattern is formed into at least two regions, and forms alignment marks for these regions for each region outside the region, Components of the pattern transferred to each area of the substrate are aligned with each other.

As mentioned above, manufacturing of large-area masks is not yet at a practical stage. Therefore, in the present invention, a relatively small area mask, such as currently available masks, is used to form a continuous pattern on a substrate.
There are at least two areas within the same substrate where continuous patterns are transferred (hereinafter referred to as pattern transfer areas).
The pattern is transferred successively to the areas, for example via at least two masks with different pattern parts. As a result, one complete pattern is transferred to the substrate.

As is known in the art, the manufacture of semiconductor circuit devices requires repeated pattern transfer to the same area of a substrate, such as a wafer, through the use of different masks having different circuit patterns. When pattern transfer is repeated, these different patterns must be superimposed on each other with high superposition accuracy. However, alignment accuracy is not essentially required for initial pattern transfer using a mask. This is because no pattern is formed on the wafer during the initial pattern transfer, and the pattern of the mask that is transferred is itself integral and not a component of a complete pattern.

On the other hand, if the pattern transfer area of the substrate is divided into a plurality of areas, and if the pattern is transferred successively to the plurality of areas by using different masks having different pattern components, then the pattern that is first transferred to each area in the substrate will be different. Alignment must be established between the components. In other words, when transferring the first pattern for multiple areas within the substrate, alignment of the pattern components is desired to ensure continuity of the pattern to be formed on the substrate.

If this is achieved, the alignment between pattern components that are subsequently transferred to areas within the substrate during successive pattern transfer steps is consistent with pattern components that are transferred to the same area within the substrate and those that have already been transferred. This can only be guaranteed automatically by pursuing overlay accuracy between the pattern components.

[Explanation of Examples]

Referring to FIG. 1, a substrate such as a glass plate, a silicon wafer, etc. has a pattern transfer area 1 on its surface onto which a continuous pattern is transferred. The outer boundaries of the substrate are not shown to simplify the drawing. The center of the pattern transfer area 1 is indicated by symbol C. The pattern transfer area 1 is divided about the center C into an upper half area and a lower half area. A mask having a length or width approximately equal to half the length of the pattern transfer area 1 is indicated by the symbol 2 . Alignment mark 3 is placed on the surface of mask 2.
.about.6 are formed in a predetermined positional relationship with respect to each other and with respect to the center of the mask 2. No circuit pattern is formed on the mask 2. Alignment marks 3 and 4 are for the upper half area of pattern transfer area 1, and alignment marks 5 and 6 are for the lower half area of area 1.

Prior to transferring the pattern to the pattern transfer area 1, the center of the mask 2 is aligned with the center C of the pattern transfer area 1, and the direction in which alignment marks 3 and 5 or 4 and 6 are connected is aligned with the center C of the pattern transfer area 1. The mask 2 is placed on or above the substrate, substantially parallel to the length direction. With this arrangement, alignment marks 3 and 4 are
The alignment marks 5 and 6 are located on or above the upper half area of the substrate with respect to the center C and on or above the area other than the pattern transfer area 1, while the alignment marks 5 and 6 are located below the area of the substrate other than the pattern transfer area 1. Placed above or above the half area.

Mask 2 is then irradiated by a radiation source and the photoresist coated on the substrate is exposed to the light beam transmitted through mask 2. As a result, the alignment marks 3 to 6 are transferred from the pattern transfer area 1 to other areas of the substrate. Images of alignment marks 3 to 6 are visualized by a known developing method.

By the above-described operation, alignment marks are provided on the substrate to enable alignment between the actual device mask having the actual device pattern and the substrate.

Pattern transfer to the pattern transfer area 1 will be explained with reference to FIGS. 2 to 4.

In this example, two real element masks 7 and 8 with complementary halves of one complete pattern are used according to the number of areas of the pattern transfer area 1. Masks 7 and 8 each include, in addition to the constituent parts of the circuit pattern, alignment marks 11 corresponding to alignment marks 3 and 4 (or 5 and 6) on the substrate.

Alignment marks 3, 4, 5, 6 and 11
The positional relationship between them is determined in advance as follows. The positional relationship between the alignment marks 11 of masks 7 and 8 that is established when masks 7 and 8 are placed side by side is such that the pattern components of the masks are precisely connected to define a precise continuous pattern. The positional relationship between the alignment marks 3 to 6 is exactly the same or exactly matches the positional relationship between the alignment marks 3 to 6. By using a known electron beam patterning method etc., alignment marks 3 to 6,
11 can be easily formed on the masks 2, 7 and 8, respectively, while accurately maintaining the above-mentioned positional relationship.

For example, if it is desired to first transfer the pattern to the upper half area of the pattern transfer area 1, the mask 7 is placed on or above the upper half area of the substrate and then the spacing between the alignment marks is adjusted as shown in FIG. The mask 7 is suitably aligned with the substrate via the alignment marks 3, 4 and 11 in a known manner as disclosed in JP-A-53-090872 until they are equal to each other. After this alignment operation is completed, an accurate positional relationship is established between the mask 7 and the upper half area of the substrate,
The upper half area of the substrate is thus exposed. During this exposure, the area of the alignment mark 11 as well as the area of the lower half of the substrate are protected from the exposure beam by suitable shielding elements.

A similar pattern transfer method is then performed on the lower half area of the pattern transfer area 1. This may be done either prior to or after processing the photoresist material on the upper half of region 1.

The degree of continuity of the pattern components transferred onto pattern transfer area 1 is only a fraction of the continuity achieved with a single mask with a large area covering area 1 (if it can be practically manufactured). It is inferior to However, such slight inferiority can be completely ignored for the following reasons. liquid crystal, some kind
The manufacturing precision required for IC, CCD, line sensors, etc.
The precision required for large-area ICs such as VLSI is not as severe. Alignment marks 3 to 6 indicate a sufficient degree of alignment between pattern constituent parts.
satisfied by.

alignment marks 3 to 6 and alignment marks 11 formed on the substrate in a similar manner to alignment marks 11 formed on the next mask when pattern transfer is required to be repeated for each of the areas of pattern transfer area 1; The pattern transfer is repeated through the next mask, achieving alignment with the pattern already transferred by the marks.

FIG. 5 is a drawing for explaining the considerations made when determining the position of the alignment mark. In the arrangement of FIG. 5, alignment marks 5 and 6 are separated from each other by a distance D, and alignment marks 3 and 6 are separated from the centerline 9 of region 1 by distances L ₄ and L ₅ , respectively.
The sum of L ₄ and L ₅ is L ₂ . Similarly, alignment marks 3 and 6 are spaced from the corresponding edges of region 1 by distances L ₁ and L ₃ respectively. If the alignment achieved by alignment marks 3 and 4 includes an error ±Δ, then the error in the rotational direction, Δθ, is given by tan ⁻¹ (2Δ/D). At this time, in Fig. 5, the upper edge of region 1 is separated from alignment mark 3 by distance L ₁ , so L ₁ · sin
(Δθ) and is shifted by L ₁ [1−cos(Δθ)] in the Y direction.

In this case, the position of the alignment mark is determined by the inequality D
There is no problem if it is determined to satisfy >L ₁ , but usually, especially in the case of elongated line sensors, the inequality D<L ₁ is satisfied due to the limited dimensions of region 1.
holds true. Therefore, a positional shift of ±Δ or less occurs at the edge of the pattern transfer area. Especially L ₄
If =L ₅ =0 (meaning that only two alignment marks are formed) is satisfied, the overlay accuracy at the edge is the worst. In view of the above, it is preferable to increase the distance D and to place the alignment marks at positions close to the corresponding centers of the areas, ie at positions satisfying L ₁ =L ₄ and L ₃ =L ₅ in FIG.

〔Effect of the invention〕

As described above, according to the substrate of the present invention, a continuous pattern with a relatively large area can be provided on its surface.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing the positional relationship between a substrate and a mask when forming alignment marks on a substrate according to the present invention. FIGS. 2 and 3 are plan views schematically showing the method of pattern transfer to a substrate according to the present invention. FIG. 4 is an enlarged view showing the alignment marks when achieving alignment. FIG. 5 is a diagram for explaining the considerations made when determining the position of the alignment mark. 1... Pattern transfer area, 3, 4, 5, 6...
Alignment mark.

Claims (1)

[Claims] 1. An alignment mark area in which the first and second alignment marks are formed and a first part of a pattern for forming an actual device are positioned using the first alignment mark and are printed in a predetermined state. a first real element region; and a second real element region in which a second part of the pattern is positioned using the second alignment mark and is printed in a predetermined state with respect to the first part; A pattern-formed substrate characterized in that the first and second rows of real element regions are arranged so as not to sandwich the alignment mark region.