JPH01225349A - Material for electronic element formation - Google Patents

Abstract

PURPOSE:To sharply increase an element formation area without increasing a size of an island region by forming a conductive layer at the outside of an insulating layer. CONSTITUTION:In a DI substrate 1, a conductive layer (polysilicon layer) 5 is arranged and installed at the outside of an insulating layer 3; an insulating layer (SiO2 layer) 6 used to electrically insulate this conductive layer 5 from a polysilicon layer 2 is formed between the conductive layer and the polysilicon layer; the insulating layer 3, an island-shaped region 4 and the conductive layer 5 are separated from the polysilicon layer 2 as a whole. The conductive layer 5 is formed in advance in a shape and with an area corresponding to an element to be formed in the island region 4. In the DI substrate 1, a V-groove is formed on the surface of an N<-> silicon semiconductor wafer (not shown in the figure) by an anisotropic etching operation; the surface is thermally oxidized; an SiO2 layer for the insulating layer 3 is formed; a polysilicon layer for the conductive layer 5 is deposited on it to be thin; in addition, an SiO2 layer for the insulating layer 6 is formed. In succession, the polysilicon layer 2 is deposited to be thick; the wafer is polished from its outside until the bottom of the V-groove is exposed; then, the island region 4 is completed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to semiconductor materials for manufacturing electronic devices.

[Conventional technology]

For example, a semiconductor material for manufacturing electronic devices, which has a semiconductor island-like region provided on a support layer with an insulating layer interposed therebetween, and is used to manufacture electronic devices, has an insulating layer. There is a separation board (CDI board). The DI board is, for example,
This substrate has a silicon semiconductor single crystal island region electrically separated by a 5ift layer on a support layer made of a polysilicon layer. Each island region has the advantage that the insulation is perfect, the isolation capacitance is small, and carriers generated within the island region do not invade other regions. MO is one of the electronic devices made using the semiconductor single crystal island region of the D1 substrate.
S) There is a transistor. In the case of a MOS transistor, the amplification factor is determined by L/W. L is the channel length, and W is the channel width. The larger the channel width W, the higher the amplification factor. Furthermore, the longer the channel and the wider the channel width W, the more variation in amplification factor due to fluctuations in the manufacturing process can be suppressed. In the case of an operational amplifier using a MOS (MOS) transistor, the accuracy of the amplification degree improves as the channel width W and channel length increase.

[Problem to be solved by the invention]

However, the area of each semiconductor single crystal island region is not very large. Therefore, it is difficult to increase the channel length and channel @W of the MOS transistor. In addition, in one semiconductor heavy crystal island region, MOS)
It is also not easy to form a large number of transistors.

Increasing the area of the semiconductor single-crystal island region increases the device formation area, but this increases the substrate area, resulting in an increase in the overall size of the device and an increase in substrate cost. The invention was made in view of the above circumstances,
It is an object of the present invention to provide a semiconductor material for manufacturing electronic devices, which has a structure that allows the device formation area to be increased without increasing the area of semiconductor island regions.

[Means for solving problems]

In order to solve the above problems, a semiconductor island-like region (
In a semiconductor material for manufacturing electronic devices having a structure (hereinafter simply referred to as an "island region"), a conductive layer is disposed outside an insulating layer.

[For production]

Semiconductor material for manufacturing electronic devices according to this invention (hereinafter referred to as
(simply referred to as a "semiconductor material"), not only the surface of the island-like region but also the bottom surface of the island-like region can be used as an element formation region by utilizing the conductive layer outside the insulating layer. Therefore, even if the size of the island region does not change, the element formation region increases dramatically.

〔Example〕

Hereinafter, examples of the semiconductor material according to the present invention will be explained in detail with reference to the accompanying drawings.

FIG. 1 shows a DI substrate which is an example of the semiconductor material of the present invention.

As shown in FIG. 1, the DI substrate 1 has a polysilicon layer (
It has an island-like region 4 electrically separated by an insulating layer (SiOg layer) 3 on the support layer) 2, and the electronic device is made using the region 4.

In this DI substrate l, a conductive layer (polysilicon layer) 5 is disposed outside the insulating layer 3, and an insulating layer (S
Ift layer) 6 is formed to separate the entire insulating layer 3, island isolation 4 and conductive layer 5 from the polysilicon layer 2. The conductive layer 5 is formed in advance to have a shape and area depending on the elements to be formed in the island region 4 .

The DI board l is made as follows.

A V-groove is formed on the surface of an N-silicon semiconductor wafer (not shown) by anisotropic etching, the surface is thermally oxidized to form a 5i (h layer) for the insulating N3, and a 5i (h) layer for the conductive layer 5 is formed on it. A thin layer of polysilicon is deposited (patterned if necessary), followed by another 5ins layer for insulation layer 6. Next, a thick layer of polysilicon N2 is deposited. When the wafer is polished from the outside until it is completely removed, the island-like regions 4 are completed.

FIG. 2 shows a semiconductor device in which a photodiode D and a MOS transistor T are formed in one island region 4 of the DI substrate 1. FIG. 3 is a circuit diagram of this semiconductor device.

A photodiode D is formed on the surface of the island region 4,
A MOS transistor T is formed on the bottom surface of the island region 4. The photodiode D has a P region 11 and an N- region 1.
It has a PiN structure consisting of 2 and N' regions 13. 1
1' and 13' are extraction electrodes. On the other hand, the MOS transistor T is formed on the bottom surface of the island region 4, and the P region 1
5 serves as a source, and P region 16 serves as a drain. The gate electrode of this MOS transistor T is a conductive layer (polysilicon layer) 5 outside the insulating layer 3.

15', 16', and 5' are extraction electrodes. Because of the presence of such a conductive layer 5, the bottom surface of the island region 4 can also be used as an element formation region.

This MOS) transistor T is formed using the entire bottom surface of the island region 4, and is designed to have a large gain and suppress variations in amplification factor due to fluctuations in the manufacturing process. is getting bigger.

Moreover, although the photodiode D normally requires a fairly large area (for example, 100 microns square), such a device and the MOS transistor T can be formed together in one island region 4.

Next, the circuit shown in FIG. 3 will be briefly explained.

When light enters the photodiode D, the photodiode D which was in the cut-off state becomes conductive, and the MOS transistor T
As a result, the MOS transistor T, which has been in a cut-off state, becomes conductive, and a voltage is applied across the resistor R8 connected to the source. When light is no longer incident, the photodiode D is in a cut-off state, and its gate becomes zero potential.At the same time, the MOS transistor T is also cut-off, and the voltage across the resistor R8 connected to the source becomes zero.

Note that the resistive elements R, , Rs of this circuit may also be provided in the island-like region 4 or another island-like region without being provided externally.

P regions 15 and 16, which become the source and drain regions of transistor T (i-1', :, MOS), may be formed during the manufacturing process of D1 substrate 1 instead of being formed after manufacturing DI substrate 1. good.

This invention is not limited to the above embodiments. As the electronic element, not only an active element but also a capacitor, which is a passive element, may be formed in the island region 4 as shown in FIG. In this capacitor, the insulating layer 3 is BP and serves as an electric body, and the N layer 19 and the conductive layer 3 are electrodes. It has a large electrode area (element formation area) and can increase capacitance. The conductive layer may be made of tungsten or the like instead of polysilicon. Complex circuitry may be created on the bottom surface by baking the conductive layer. The structure of the semiconductor substrate is also not limited to the structure shown in FIG.

〔Effect of the invention〕

As described above, the semiconductor material of the present invention has a conductive layer outside the insulating layer. Therefore, since the bottom surface of the island region also serves as an element formation region, the element formation area can be significantly increased without increasing the size of the island region.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a DI substrate as an example of the semiconductor material according to the present invention, and FIG. 2 shows a photodiode D and a MOS transistor T formed in one island-like region of the DI substrate 1. FIG. 3 is a circuit diagram of the semiconductor device of FIG. 2, and FIG. 4 is a cross-sectional view of a capacitor formed in the island-like region of the semiconductor material. 1... DI substrate (semiconductor material) 2... Support layer 3
... Insulating layer 4 ... Island region 5 ... Conductive M
(Polysilicon layer) Agent: Patent attorney Takehiko Matsumoto Figure 3 Figure 4

Claims (1)

[Claims] 1. In a semiconductor material for manufacturing an electronic device, which has a semiconductor island-like region provided on a support layer with an insulating layer interposed therebetween, and the semiconductor island-like region is used to manufacture an electronic device, the insulating A semiconductor material for manufacturing electronic devices, characterized in that a conductive layer is provided on the outside of the layer.