JPS6148253B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photomask used for manufacturing semiconductor devices and the like.

Semiconductor devices such as IC LSI are manufactured with a diameter of 60 to 100 mm as a starting material.
A large number of element pellets (approximately 0.3 to 30.0 mm diameter) are obtained from one wafer by using semiconductor wafers of approximately 100 mm and subjecting them to various wafer treatments.

However, when a silicon wafer after wafer processing is divided into a large number of pellets, harmful scribe cracks are generated on the wafer in a target area dedicated to alignment on the wafer, resulting in a problem of reduced product yield.

When photoetching a silicon wafer, an auto-alignment device is used to align the photomask and the wafer. This automatically controls the alignment target on the photomask. However, as shown schematically in FIG. 1, this type of alignment-specific target 1 has the advantage of improving the detection voltage (improving workability, productivity, precision, etc.) during mask alignment by photoetching on a silicon wafer 2. In order to prevent pitch deviation, a pair of target regions 3 for alignment are provided at each location, the number of which corresponds to the number of photoetching steps. Therefore, since there is no scribe area on the photomask between the target units,
No scribe area (area indicated by two-dot chain lines in the figure) is formed between this group of alignment-only targets, and the total number of targets 1 (i.e., the number of photo-etching steps for manufacturing a semiconductor device) is not formed between these alignment targets. When scribing a silicon wafer 2 whose size is smaller than the size of the pellet 2a (the number corresponds to the number of steps after deducting the first photo-etching step, which is a number of targets dedicated to alignment in bipolar ICs). In this case, a group of targets 1 spans over two or more pellets 2a, and a sufficient linear groove (scribe line) cannot be created on the wafer 2 by scribing, and the pellets 2a are cracked at this portion during cracking. In addition to the drawbacks, the diamond cutter for scribing is subject to severe wear and tear.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a photomask that can be used to prevent pellet cracking when dividing a wafer.

The gist of the present invention for achieving such an object is to include a grid-like dividing pattern, a plurality of regions surrounded by the dividing pattern, and two adjacent regions among the plurality of regions. and an alignment target pattern to be formed, and the alignment target pattern is formed in the two adjacent regions with no element region pattern present in one of the two adjacent regions. It is on a photomask featuring the following. A negative photoresist photomask as an example will be described in detail with reference to the drawings.

FIG. 2 is a plan view showing a photomask for negative photoresist according to the present invention. In the figure, numeral 4 indicates a photomask for negative photoresist, and thick line 5 indicates a baking pattern for scribing a silicon wafer, which is an object to be photoetched. It consists of a thin film that is opaque to the surface. Reference numeral 6 indicates the alignment-only target of the photomask 4 and the area of this target unit, and the scribing burn pattern 5
It is provided on the surface of the inner glass substrate.

This alignment-dedicated target area is provided on the photomask 4 in a number corresponding to the number of photoetching processes performed on the silicon wafer to be photoetched, that is, the number of a series of photoetching processes minus 1 (the first photoetching process). It is being That is, a group of alignment-dedicated target areas is divided into subdivided target units 6, and these target units are neatly incorporated into the grid-like scribing pattern lines. In addition, in the figure, what is shown by a dashed dot line indicates an exclusive area of this group of target areas. Also,
Although not shown, a pattern having a shape for photoetching a silicon wafer, which is an object to be photoetched, in a predetermined shape is provided in the grid-like scribe baking pattern.

When a negative type photoresist is used as a shielding film for photoetching, the printed pattern for scribing on a photomask is formed by a black pattern, that is, a thin chrome film, etc., and when a positive type photoresist is used as a shielding film for photoetching. In this case, a white pattern is formed, that is, an opaque thin film such as a thin chrome film is formed on the periphery of this area.

Using such a photomask 4, a mask alignment operation is performed to form a predetermined printed pattern on a silicon wafer, which is an object to be photoetched, using an auto-alignment device, and when the predetermined pattern is formed on the silicon wafer by photoetching, As schematically shown in the figure, passivation films such as silicon oxide and phosphosilicate glass films and wiring films such as aluminum films and polycrystalline silicon films in the scribe region on the surface of the silicon wafer 7 can be removed. In particular, even in a region 9 (indicated by a dashed line in the figure) where a group of target units 8 dedicated to alignment exist on the surface of the silicon wafer 7, there is a scribe region 10 between the target units 8.
(indicated by a two-dot chain line in the figure), and since there is no passivation film or wiring film in that area, which is made of a hard material and makes it difficult to draw scribe lines with a diamond cutter for scribing, the pellet cracks smoothly in this area as well. Scribing can be performed while preventing. That is, by using the photomask according to the present invention, when dividing the silicon wafer 7, which is the object to be photoetched, into pellets, the pellet size is smaller than the exclusive area of the target consisting of a group of alignment targets. Even if there is a problem, a scribing area can be provided within this group of alignment-dedicated target areas, so that pellet cracking does not occur during smoliving, and the scribing diamond cutter does not wear out more than necessary.

The present invention can be applied to photomasks having alignment-specific targets in various types of mask alignment devices, and can also be used for photoetching in the production of various electronic components such as IC LSI diodes and transistors. .

[Brief explanation of the drawing]

Figure 1 is a plan view showing a silicon wafer obtained after a conventional photoetching process;
The figure is a plan view showing a photomask for negative photoresist, which is an embodiment of the present invention, and FIG. 3 is a plan view showing a silicon wafer obtained by photoetching using the photomask according to the present invention. It is. 1, 8... Alignment dedicated target on silicon wafer, 2, 7... silicon wafer,
3, 9...A group of target areas, 4...Photomask, 5...Burning pattern for scribing the object to be etched on the photomask, 6...
Dedicated alignment target on photomask,
10...Scribe area on the surface of the silicon wafer.

Claims (1)

[Claims] 1 comprising a lattice-like dividing pattern, a plurality of regions surrounded by the dividing pattern, and an alignment target pattern formed in two adjacent regions among the plurality of regions; 2. A photomask characterized in that a target pattern is formed within the two adjacent regions with no element region pattern present in one of the two adjacent regions.