JP2740196B2 - Semiconductor wafer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer (hereinafter simply referred to as a wafer) used for manufacturing an integrated circuit and the like, and a method for manufacturing the same.

(Prior art)

Conventionally, in a wafer processing process in which a semiconductor single crystal ingot (hereinafter simply referred to as an ingot) is cut and polished to obtain a mirror-finished wafer, a wafer surface corresponding to an upper side and a wafer surface corresponding to a lower side in an ingot state are distinguished. A common method is to include two orientation flats.

Then, in order to reduce the droop during epitaxial growth in the manufacture of semiconductor devices, a wafer cut and polished at an angle of several degrees from the crystal axis may be used ("LSI Handbook P.346, edited by IEICE"). In order to distinguish the wafer surface corresponding to the upper side from the wafer surface corresponding to the lower side in the ingot state, as described above, two orientation flats (hereinafter, referred to as two orientation flats) are used.
OF) is common.

[Problems to be solved by the invention]

However, according to the study of the inventor, in the above-described conventional technology, compatibility between only one OF-equipped wafer and two OF-equipped wafers in the OF alignment mechanism of various types of semiconductor device manufacturing apparatuses is considered. Not considered, only one
The OF alignment mechanism for a wafer with an OF has a problem that two wafers with an OF cannot often be accurately aligned. In addition, the OF alignment mechanism for two wafers with OF requires a mechanism for distinguishing between the first OF and the second OF, and thus has a problem that an increase in apparatus cost and a decrease in throughput cannot be avoided.

An object of the present invention is to enable OF alignment with only one OF alignment mechanism corresponding to a wafer with an OF, and to cut and polish an ingot (or a single crystal block) into a wafer when processing it into a wafer. It is another object of the present invention to provide a wafer which can easily distinguish a wafer surface corresponding to an upper side from a wafer surface corresponding to a lower side.

The above and other objects and novel features of the present invention are as follows.
It will become apparent from the description of the present specification and the accompanying drawings.

[Means for solving the problem]

The following is a brief description of an outline of typical inventions disclosed in the present application.

That is, it has an arc-shaped outer peripheral portion and an orientation flat portion provided in a part of the outer peripheral portion, and one end and the other end of the orientation flat portion are respectively the arc-shaped outer peripheral portion and Regarding the semiconductor wafer to be connected, the connection shape between one end of the orientation flat portion and the arc-shaped outer peripheral portion, and the connection shape between the other end of the orientation flat portion and the outer peripheral portion on the arc, Are different from each other, and the front surface and the back surface of the semiconductor wafer are specified by the difference in the connection shape with the arc-shaped outer peripheral portion.

[Action]

According to the above-described means, after placing the asymmetrical OF into the ingot, and then cutting to produce a wafer, even after cutting, either surface of the wafer corresponds to the upper side in the ingot state, or the lower side It is possible to identify whether they correspond.

Also, since it is just OF of the left-right asymmetry of the wafer,
The alignment can be easily performed by only one OF alignment mechanism for the wafer with the OF.

(Example of the invention)

Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings.

In all the drawings for describing the embodiments, components having the same function are denoted by the same reference numerals, and their repeated description will be omitted.

First, wafer processing will be described. As described in detail in "LSI Handbook" P.237 (edited by the Institute of Electronics and Communication Engineers), the ingot is divided into several single crystal blocks, outer diameter grinding is performed, and OF is put on the determined surface, and the single crystal block Is cut into wafers, and is completed through edge processing, processing strain removal, mirror polishing, and final cleaning.

The present invention is practiced by making the OF asymmetrical in the step of inserting the OF in the wafer processing process.

FIG. 1, FIG. 2, and FIG. 3 are views for explaining an embodiment of the wafer of the present invention. FIG. 1 shows an ingot having an asymmetrical OF by rounding one end of the OF. Or a single crystal block) as viewed from directly above or directly below, and (b) is a partially enlarged view of (a).

FIG. 2 is a view of an ingot (or a single crystal block) having an asymmetrical OF by dropping a corner of one OF end as viewed from directly above or directly below.

FIG. 3 is a view of a conventional single ingot with OF (or a single crystal block) viewed from directly above or directly below.

In FIGS. 1, 2 and 3, a is the outer circumference of the ingot after polishing the outer diameter, and b is the orientation flat (O
F) and c are asymmetrical portions due to roundness, and d is an asymmetrical portion due to dropping corners.

As shown in FIG. 3, the conventional ingot (or single crystal block) provided with only one OFb has the same shape when viewed from the front side and the back side. In the later wafer state, it is not possible to distinguish between the surface corresponding to the upper side and the surface corresponding to the lower side in the ingot state.

In contrast, the ingot of the present embodiment shown in FIG.
Only the left end of OFb is rounded to form an asymmetrical portion c, and the front and back sides can be easily distinguished in the wafer state after cutting. FIG. 2 shows the asymmetrical portion d obtained by dropping the corner at the left end of OFb in FIG. 3, and as in the case of FIG.
The front and back can be easily distinguished. In addition, in both of the ingots shown in FIGS. 1 and 2, only one OFb is provided with asymmetry. In the device manufacturing apparatus, a malfunction occurs in only one OF alignment mechanism corresponding to a wafer with OF. There is no.

Next, the improvement of the pattern overlay accuracy in the device manufacturing process when the wafer provided by the present embodiment is used will be described. ("LSI Handbook" P.346
Normally, the epitaxial substrate used for the bipolar device is provided with a buried layer, and the buried portion has a step of about 100 to 300 nm in order to facilitate pattern superimposition in a later process. Is attached. When an epitaxial layer is formed on this step, it is naturally formed along the crystal orientation of the substrate. However, when a wafer inclined at an angle of several degrees from the crystal axis is used, in the ingot shown in FIG. 3, as shown in FIG. 4 and FIG. The crystal orientation when viewed from the wafer surface is different (vertically symmetric in the figure) between the plane corresponding to. Naturally, if the crystal orientation is different, the pattern droop in epitaxial growth, the direction of pattern shift is also different, and between the wafers, the buried layer is adjusted based on
A large step occurs in pattern superposition in a step after the epitaxial growth. The wafer of this embodiment (FIG. 1 and FIG. 2)
FIG. 1), the crystal orientation can be unified, and the reproducibility between wafers can be improved.

As mentioned above, although the present invention was explained concretely based on an example, the present invention is not limited to the above-mentioned example.
It goes without saying that various changes can be made without departing from the scope of the invention.

〔The invention's effect〕

The effects obtained by the representative inventions among the inventions disclosed in the present application will be briefly described as follows.

That is, it is possible to distinguish between the surface corresponding to the upper side and the surface corresponding to the lower side in the ingot state, and it is possible to provide a semiconductor wafer that does not require modification of the OF alignment mechanism of the device manufacturing apparatus. As a result, semiconductor devices can be manufactured on a wafer surface having a unified crystal orientation, and reproducibility in a device manufacturing process can be improved.

[Brief description of the drawings]

Fig. 1 is a view of an ingot (or a single crystal block) having an asymmetrical OF with a rounded end at one side as viewed from directly above or directly below. FIG. 3 is a view of the obtained ingot (or single crystal block) viewed from directly above or directly below. FIG. 3 is a view of a conventional single ingot with OF (or single crystal block) viewed from directly above or directly below. FIG. 5 is a diagram showing the difference in the inclination direction of the crystal orientation when the surface corresponding to the upper side and the surface corresponding to the lower side in the ingot state are taken as the wafer surface. In the figure, a: outer periphery of ingot (or single crystal block) after outer diameter grinding, b: orientation flat (O
F), c: an asymmetric portion due to roundness, d: an asymmetric portion due to dropping a corner,

Claims (2)

(57) [Claims] 1. An outer peripheral portion having an arc shape and an orientation flat portion provided on a part of the outer peripheral portion, and one end and the other end of the orientation flat portion are each formed of the arc shape. A semiconductor wafer connected to an outer peripheral portion, wherein a connection shape between one end of the orientation flat portion and the arc-shaped outer peripheral portion, and the other end of the orientation flat portion and the arc-shaped outer peripheral portion are provided. A semiconductor wafer having a different connection shape from the semiconductor wafer. 2. A semiconductor wafer having an arc-shaped outer peripheral portion and an orientation flat portion provided on a part of the outer peripheral portion, wherein one end and the other end of the orientation flat portion are respectively provided. The semiconductor wafer according to claim 1, wherein a front surface and a back surface of the semiconductor wafer are specified by a difference in a connection shape with the arc-shaped outer peripheral portion.