JPS63148611A - Marking method for semiconductor substrate - Google Patents

Abstract

PURPOSE:To prevent the breakage of a substrate and the occurrence of a crystal defect by a method wherein a marking item is marked on the substrate by means of photolithography and etching or by depositing a metal simultaneously with the formation of an alignment mark. CONSTITUTION:After an alignment mark has been exposed onto a positive-type photoresist layer 2 by means of, e.g., a mask 3 for the formation of the alignment mark, a marking item is exposed again onto a part other than the previously exposed part on the resist layer 2 by means of a mask 4 for the marking item; after that, the resist layer 2 is developed; a resist pattern 2a, where the resist layer corresponding to the alignment mark and the marking item is removed, is obtained. Accordingly, if a substrate 1 is etched by making use of the resist pattern 2a or a metal is deposited on the substrate 1, the alignment mark and the marking item are formed on the semiconductor substrate 1 by depositing the metal or by etching. As a result, it is possible to prevent the breakage of the substrate and the occurrence of a crystal defect of the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor substrate marking method for writing necessary information such as a Lot number on a semiconductor substrate.

(Prior Art) Conventionally, in order to write necessary information such as Lot number 2 machine date 9 on a semiconductor substrate, such as a QaAs substrate, it is necessary to write directly on the substrate with a diamond pen, or to mechanically remove the resist when forming alignment marks. They used methods such as peeling it off and etching it.

(Problems to be Solved by the Invention) However, in the above conventional method, the GaAs substrate is particularly vulnerable to force and vibration, so the substrate may be damaged when writing with a diamond pen or when mechanically peeling off the resist. There are problems such as defects occurring in the substrate crystal, resulting in deterioration of the characteristics of manufactured devices and a decrease in yield. In addition, if you do not fill out the necessary information for the board,
This led to work errors, time loss, and increased costs, making it impossible to obtain a product that was technically satisfactory.

This invention has been made in view of the above points, and is a semiconductor device that allows necessary information (marking information) to be written on a semiconductor substrate without damage to the substrate, occurrence of substrate crystal defects, deterioration of semiconductor element characteristics, and reduction in yield. The purpose of the present invention is to provide a method for marking a substrate.

(Means for Solving the Problems) In the alignment mark forming process, the present invention spreads a positive type resist on a semiconductor substrate, and separates the alignment marks and marking items into the positive type resist using separate masks. The exposed resist is exposed using different exposure steps, the exposed resist is developed, and the developed resist is used as a mask to perform etching of the substrate or metal deposition on the substrate.

(Function) After exposing an alignment mark to a positive type resist using, for example, an alignment mark forming mask, a marking item is exposed again at a different location on the resist using a marking item mask, and then the resist is developed. For example, a resist pattern is obtained in which resist is removed in correspondence with alignment marks and marking items.

L, 7'c Then, by etching the substrate or depositing metal on the substrate using the resist pattern as a mask, alignment marks and marking items are formed on the semiconductor substrate by the metal deposition or etching.

(Incoming side) An embodiment of the present invention will be described below with reference to FIG.

First, as shown in FIG. 1(a), a GaAs substrate 1 is prepared.
Apply positive type resist 2 on top. Here, the positive type resist 2 is a resist whose portions irradiated with light are bath-dissolved by development, although there is no need to explain it.

Next, alignment marks are exposed on the positive type resist 2 using an alignment mark forming mask 3, as shown in FIG. 1(b). The exposed area is indicated by A.

Next, the exposure mask is replaced with the marking item mask 4. Then, using the marking item mask 4, marking items are exposed at different positions on the positive tag resist 2 as shown in FIG. 1(e).

The exposed portion of the marking is indicated by B.

Next, the positive type resist 2 is developed. Then, the first
As shown in figure (d), the exposed part A of the alignment mark
The exposed portion B of the marking item is removed, and a resist pattern 2a is obtained in which the resist is removed corresponding to the alignment mark and the marking item.

After that, the resist pattern 2ai is masked and Ga
The As substrate 1 is etched. Then, GaAaJ[
1fl and the resist pattern 2m are etched in correspondence with the removed portions of the resist, and as a result, markings B' are formed on the GaAs substrate 1 as alignment marks as shown in FIG. 1(e).

In addition, in the above method, the order of the exposure process of the alignment mark and the exposure process of the marking items on the positive type resist 2 may be reversed.

Also, the final etching step can be replaced by a metal deposition step. That is, metal is deposited with the resist pattern 2a formed on the GaAs substrate 1, and unnecessary metal is removed from the entire resist to form the resist pattern 2a.
By leaving only the metal in the portion where the turtle resist has been removed, alignment marks and marking items can be formed on the GaAs substrate 1 by metal deposition.

In addition, in the above method, marking item mask 4F
i. Quartz is generally used as a lath mask, but if precision is not required, a film-like mask may also be used.

(Effects of the Invention) As described in detail above, according to the method of the present invention, marking items are written on the semiconductor substrate by photolithography and etching or metal deposition at the same time as alignment marks are formed. Even in the case of the substrate, stress that would cause damage to the substrate or generation of crystal defects in the substrate is not applied, and damage to the substrate and generation of crystal defects can be prevented. Therefore, it is possible to eliminate deterioration in characteristics of manufactured elements and decrease in yield. Further, according to the method of the present invention, marking items are not added to the alignment mark forming mask and the marking items are made into an independent mask, so the marking items mask can be used in combination with other alignment mark forming masks. You can also do that. In addition, when adding marking items to the mask for forming alignment marks, you need as many high-precision alignment mark forming masks as there are marking items, but if you separate the marking items into separate masks, you can create high-precision alignment marks. It is economical because only one forming mask is required.

[Brief explanation of the drawing]

FIG. 1 is a process sectional view showing an embodiment of the semiconductor substrate marking method of the present invention. 1...GaAs substrate, 2...Positive type resist,
2a...Resist pattern, 3...Mask for alignment mark formation, 4...Marking item mask, A
...Alignment mark exposure area, B...Marking item exposure area,...Alignment mark, ``...Marking item.

Claims (1)

[Claims] In the alignment mark forming step, (a) a step of applying a positive type resist on a semiconductor substrate; and (b) a step of forming an alignment mark and marking items on the positive type resist using separate masks. (c) developing the exposed positive type resist; and (d) etching the semiconductor substrate or depositing a layer on the substrate using the developed positive type resist as a mask. A method for marking a semiconductor substrate, comprising a step of forming an alignment mark and a marking item on a semiconductor substrate.