JP2535957B2 - Semiconductor substrate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor substrate used when manufacturing various semiconductor devices such as a single semiconductor device or a semiconductor integrated circuit device, and particularly first and second semiconductor substrates. Related to a semiconductor substrate formed by bonding.

[Outline of Invention]

The present invention relates to a semiconductor substrate in which two semiconductor substrates are bonded together, so that at least the outer peripheral edge of the first semiconductor substrate is inside the outer peripheral edge of the second semiconductor substrate. The defective part in the bonding part at the peripheral part which is a problem in the bonding is eliminated, the effective use area is increased, and the semiconductor substrate conforming to the standard as the semiconductor substrate can be obtained. Make it simple.

[Conventional technology]

Conventionally, as shown in a partially enlarged cross-sectional view of FIG. 4, first and second silicon single crystal semiconductor substrates (1) and (2) are bonded directly or through an oxide film. BACKGROUND ART Various semiconductor devices for high power or high breakdown voltage, or a semiconductor substrate (3) such as a so-called SOI type (semiconductor on insulator) or the like is constructed. This kind of first and second silicon semiconductor substrates (1)
Regarding the direct joining or (2) joining by means of an oxide film or the like, for example, JP-A-60-121776 and JP-A-60-
-121777, IEICE Technical Report SDM87-25
Pages 9-14, SDM 87-24, pages 5-8, or Applied Physics Letter (Appl.Phys.Lett.) V
ol.48, No.1,6, January 1986, pages 78 to 80, etc.

In the semiconductor substrate in which the first and second semiconductor substrates are joined and combined, as shown in FIG. 4, when polishing the first semiconductor substrate (1) and the second semiconductor substrate (2) themselves, etc. When these two semiconductor substrates (1) and (2) are joined and joined by positively or inevitably having a rounded outer peripheral shoulder, the outer peripheral ends are joined together. A gap is formed in the portion, and uneven steps are generated due to either of the substrates (1) and (2), which may cause dust adhesion and contamination during the manufacturing process of various semiconductor elements on the semiconductor substrate (3). In order to cause generation and uncertainties in mechanical handling, the gap or the portion having the step (4) is eliminated before the manufacturing process of the semiconductor device. The width W ₁ to be excluded is, for example, W ₁ = 0.4 inch in the case of joining semiconductor substrates having a diameter of 6 inches as the first and second semiconductor substrates. Therefore, when the outer peripheral edge of the bonded semiconductor substrate is removed only for the purpose of eliminating the gap or the step (4), the diameter of the semiconductor substrate having a diameter of 6 inches should be reduced to about 5.6 inches. However, in various devices that actually handle semiconductor substrates in the manufacture of semiconductor devices, the diameter of the semiconductor substrate to be handled is regulated, and for example, standard sizes of 3 inches, 4 inches, 5 inches, 6 inches, 8 inches ... Even if the minimum required cutting width W ₁ is about 0.4 inch because it is decided, by cutting from the outer peripheral edge with a width W ₂ that is sufficiently larger than this,
For example, when the initial diameter of both substrates (1) and (2) is a 6-inch substrate, it is necessary to make a standard-sized substrate of 5 inches after joining, which results in a large waste of semiconductor material.
Further, if the periphery of the bonded substrate is largely excluded with such a large width W _2, the processing work requires a long time, which is technically troublesome and the workability is deteriorated.

[Problems to be solved by the invention]

According to the present invention, in a semiconductor substrate formed by joining the above-described first and second semiconductor substrates, waste of semiconductor material is reduced as much as possible, and a conventional semiconductor device manufacturing apparatus that handles a standard size is used as it is. The present invention provides a semiconductor substrate that enables the above.

[Means for solving problems]

According to the present invention, as shown in FIG. 1, first and second semiconductor substrates (1) and (2) are attached to each other, and at least the outer peripheral edge of the first semiconductor substrate (1) is second. The semiconductor substrate (2) is located inside the outer peripheral edge.

[Action]

According to the above-described semiconductor substrate of the present invention, one semiconductor substrate (2) has a standard size standard because at least a part of the outer peripheral edge thereof is left, and one semiconductor substrate (1) ), A non-uniform step due to gaps or deviations between the first and second substrates (1) and (2) can be avoided by adopting a small diameter configuration in which the outer peripheral edge is excluded. It is possible to avoid problems such as fouling in the manufacturing process of the device, and since the diameter as a whole has the standard size of the initial state, it is possible to use the manufacturing device that handles the standard size, eliminating the semiconductor material, that is, minimizing the waste. It can be limited.

〔Example〕

An example of the present invention will be described together with an example of a manufacturing method thereof in order to facilitate understanding thereof with reference to FIG. First,
As shown in FIG. 2A, the first and second semiconductor substrates (1) and (2) each made of, for example, a single crystal silicon semiconductor are known by the presence of an SiO ₂ oxide film (5) accompanied by, for example, an oxidation treatment. It is joined and united by a technique. One of the joined semiconductor substrates, for example, corresponds to the width W ₁ necessary for eliminating the gap or the step (4) described in FIG. 4 on the first substrate (1) in the figure. An etching mask (6) such as a photoresist is deposited on the entire surface, leaving a width W from the outer peripheral edge.

Then, as shown in FIG. 2B, the SiO ₂ oxide film (5) formed on the surface of the substrate (1) which is not covered with the etching mask (6) is used as an anisotropy. Etching, for example, reactive ion etching (RIE), the SiO ₂ oxide film (5) on the peripheral portion of the main surface of the substrate (1) opposite to the side bonded to the substrate (2) is removed by etching.

Next, as shown in FIG. 2C, the silicon substrate (1) from which the insulating layer has been removed is removed by chemical etching or the like with a width W at the outer peripheral edge thereof. For example, etching is performed with a KOH aqueous solution. In this case, Si and Si
The ratio of the etching rate Rsi and RSiO ₂ against the O _2, Rsi / Rs
Since io ₂ = 10 ³ to 10 ⁴ , when the etching from the substrate (1) side reaches the SiO ₂ oxide film (5) between both substrates (1) and (2), the etching progresses rapidly. However, if the etching operation is stopped at this time, only the substrate (1) has a width W corresponding to the peripheral portion not covered with the SiO ₂ oxide film (5). The width of the substrate (2) is removed by etching to remove the gap or step (4), and the diameter of the substrate (2) is left as it is. That is, the substrate (1)
Since the overall diameter of the bonded and combined substrate (3) of (2) and (2) is set by the outer diameter of the second substrate (2) which is not etched, this outer diameter is used, for example, 6 inches. In this case, the finally obtained semiconductor substrate (3) also has an outer diameter of 6 inches, and a handling device for manufacturing a semiconductor device handling a 6-inch standard size substrate can be used.

In the example of FIG. 2 described above, an example is shown in which the first and second semiconductor substrates (1) and (2) are joined by the interposition of the insulating layer. Two
The present invention can be applied to the case where the substrates (1) and (2) are directly mirror-bonded to each other. An example of this case can be understood with reference to FIG. For ease of explanation, the manufacturing method will be described. Also in this case, for example, the first and second silicon single crystal bodies are used.
The well-known direct bonding of the semiconductor substrates (1) and (2), that is, the bonding surfaces of the two substrates (1) and (2) are mirror-planarized, and both are combined and heated to a required temperature. As shown in FIG. 3A, both substrates (1) and (2)
A bonded united substrate is manufactured.

Next, in this example, as shown in FIG. 3B, the surface of the substrate on which both substrates (1) and (2) have been combined is thermally oxidized to form an oxide film (5) such as SiO ₂ . Then the second
Similarly to the case described with reference to FIG. B, the etching mask (6) is entirely deposited on the inner side of the outer peripheral edge of the substrate (1) except for the width W, and the etching treatment is performed as shown in FIG. 3C. The oxide film (5) on the surface of the substrate (1) is selectively removed by etching.

Next, as shown in FIG. 3D, the portion of the substrate (1) from which the oxide film (5) has been removed is etched by an etching solution such as KOH so as to extend over a part of the substrate (2), that is, the substrate (2). The substrate (2) is etched to the position where it crosses the joining surface of (1) and (2) and leaving the substrate (2) as thick as possible.

In this way, the semiconductor substrate (3) in which the first and second substrates (1) and (2) are joined is obtained, and the step difference in the gap at the outer peripheral edge between the two substrates (1) and (2) is obtained. (4)
Can be eliminated, and the same semiconductor substrate (3) as described above having an outer diameter dimension as a whole determined by the outer diameter of the substrate (2) can be obtained.

In the examples described with reference to FIGS. 2 and 3, a case has been described in which the outer peripheral edge of the substrate (1) is etched by chemical etching, but this is cut by lapping the outer peripheral edge of the substrate (1). It is also possible to eliminate it by mechanical polishing with, a mechanical grinding with a diamond cup wheel or the like, or a mechanical cutting method with a diamond bite or the like.

〔The invention's effect〕

As described above, according to the present invention, the semiconductor substrate (3) is formed by bonding the first and second substrates (1) and (2), but only the first substrate (1) is The outer peripheral edge is cut off to eliminate unnecessary portions such as gaps in the outer peripheral portion of the bonding of the substrates (1) and (2), which poses a problem in the manufacture of the semiconductor device. Since it is formed as a substrate of a standard size diameter, it is possible to minimize the waste of semiconductor materials, and since it is possible to apply a semiconductor manufacturing apparatus that handles a standard size semiconductor substrate, it is possible to achieve the objective without increasing the cost. The present invention is applied to a power or high breakdown voltage semiconductor device to which a junction type semiconductor substrate is applied, or an SOI type integrated circuit, etc. It is enormous.

[Brief description of drawings]

1 is a schematic cross-sectional view of an example of a semiconductor substrate according to the present invention, FIG. 2 is a manufacturing process diagram for explaining the example of a semiconductor substrate according to the present invention, and FIG. 3 is another example of a substrate of the present invention. FIG. 4 is a manufacturing process diagram used for the explanation, and FIG. (1) is a first semiconductor substrate, (2) is a second semiconductor substrate, and (3) is a semiconductor substrate obtained by combining the first and second semiconductor substrates.

Claims (1)

(57) [Claims] 1. A first semiconductor substrate and a second semiconductor substrate are bonded together, and at least the outer peripheral edge of the first semiconductor substrate is inside the outer peripheral edge of the second semiconductor substrate. Semiconductor substrate.