JPH0584675B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to improvements in insulating substrates for semiconductors.

<Prior Art> Sapphire substrates have conventionally been used as insulating substrates for semiconductors instead of Si substrates, for example in SOS technology. SOS technology forms MOS devices by epitaxially growing a Si thin film on a sapphire substrate, solving the conventional problems of wiring capacitance and isolation between elements, and increasing the speed of MOS devices. This is what I did. However, with SOS substrates using saphire, when semiconductors such as silicon are epitaxially grown at high temperatures, part of the base surface of the saphire substrate is reduced by the hydrogen used as the raw material gas, and the surface of the saphire substrate is reduced. It is known that some of the silicon epitaxial layers formed in 2015 are doped with reduced metal Al or oxygen and are therefore contaminated. Therefore, the electrical characteristics and crystallinity of the semiconductor layer epitaxially grown on the sapphire substrate are significantly degraded. For this reason, the performance of the sapphire substrate as a practical substrate is hampered, and the reality is that it has not been fully put into practical use.

In view of this situation, the present applicant first coated the entire surface of the sapphire substrate with Y, Ca, and
Patent application for a new semiconductor insulating substrate coated with a stabilized zirconia thin film doped with Mg, Sc, etc.
-187661, Japanese Patent Application No. 60-7032, etc., and realized an insulating substrate for semiconductors that does not affect the characteristics of semiconductor devices.

<Problems to be Solved by the Invention> However, when forming a stabilized zirconia thin film in the insulating substrate for semiconductors previously proposed by the present applicant, the growth temperature is as high as 550°C or higher, and the addition range of oxides is too high. The content was also within a relatively narrow range of 6.2 mol% to 12.6 mol%, which placed restrictions on the conditions for forming the stabilized zirconia thin film.

The present invention was devised in view of the above points, and uses a stabilizer that can be added at a lower temperature and has a wider range of addition than the stabilizer used in the semiconductor insulating substrate previously proposed by the applicant. An object of the present invention is to provide an insulating substrate for a semiconductor, which is formed by coating a sapphire substrate with a stabilized zirconia thin film that is easily formed.

<Means for Solving the Problems> In order to achieve the above object, the insulating substrate for semiconductors of the present invention includes yttrium on the entire surface of the sapphire substrate.
It is constructed by coating a single crystal film of stabilized zirconia to which a stabilizer containing a rare earth element having a mass number larger than (Y) is added in a content of 6.1 mol % to 19.4 mol %.

In addition, as an embodiment of the present invention, the semiconductor insulating substrate according to the present invention has a mass number of
A single crystal of stabilized zirconia formed from zirconium oxide added with stabilizers samarium (Sm), gadolinium (Gd), and ytterbium (Yb), which are larger than yttrium (Y) with a value of 150.3 to 173.0, is coated. It is something.

<Function> In the structure of the semiconductor insulating film according to the present invention, the entire surface of the sapphire substrate is covered with a stabilized zirconia film made of an oxide single crystal. When forming a stabilized zirconia film, the addition of a stabilizer with a larger mass number than yttrium (Y) is more advantageous than the method previously proposed by the applicant in terms of lowering the growth temperature and increasing the amount added. It is. Furthermore, even when used as an insulating substrate for semiconductors, even if semiconductor materials such as silicon are epitaxially grown at high temperatures (~1200℃), the internal sapphire is covered with stable zirconia. There is no direct exposure to active hydrogen and no reduction reaction occurs. Furthermore, since the stabilized zirconia thin film formed on the substrate surface is stable against active hydrogen, it can be used without contaminating the epitaxial growth layer of semiconductors such as silicon with zirconium (Zr) or oxygen (O ₂ ). A highly pure epitaxial film can be obtained. Therefore, by applying the insulating substrate having the structure according to the present invention to a semiconductor device made of silicon or the like, it becomes easy to isolate between elements, and it becomes latch-up free. It becomes possible to create VLSI such as Bi-CMOS and CMOS.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view schematically showing the basic structure of an insulating substrate for semiconductors according to the present invention.

In FIG. 1, a single crystal stabilized zirconia film 2 (ZrO ₂ ) _{1-o is} formed on the entire surface of a sapphire substrate 1.
(Yb ₂ O ₃ ) _o or (ZrO ₂ ) _1-o (Sm ₂ O ₃ ) _o , (ZrO ₂ ) _1-
o (Gd ₂ O ₃ ) _o is coated. However, the value of n is 0.061
and 0.194.

When using the sputtering method, the base material zirconium oxide ZrO ₂ grows epitaxially at a growth temperature of 400°C or higher _;
It is known that the single-crystalline film has a monoclinic crystal system, which changes to a tetragonal crystal at high temperatures, and undergoes a phase transition to a cubic crystal at higher temperatures. Therefore, depending on the temperature history, a volume expansion of as much as 7.4% may occur, leading to self-destruction. However, yttrium (Y) is added as a stabilizer in zirconium oxide _ZrO2 .
6.1 mol% to 19.4 mol% of one of ytterbium oxide (Yb ₂ O ₃ ), samarium oxide (Sm ₂ O ₃ ), and cadrinium oxide (Gd ₂ O ₃ ) containing elements with higher mass numbers. By adding within the range,
A cubic single crystal film can be obtained at a growth temperature of 450°C to 1000°C. It was found that this stabilized zirconia film maintains the same crystal structure despite temperature history. The present invention is characterized by a structure in which a zirconia film 2 to which a stabilizer having a mass number larger than yttrium (Y) is added is formed on a sapphire substrate 1, preferably by a sputtering method, to a film thickness in the range of 0.01 to 10 μm. .

In particular, the single-crystal stabilized zirconia film 2 can withstand high temperatures and is resistant to thermal shock. Furthermore, the lattice mismatch with silicon is within 4%, which is smaller than that of the sapphire substrate, so the lattice matching is good.

Next, the manufacturing process of a silicon semiconductor substrate using the semiconductor insulating substrate according to the present invention will be explained with reference to FIG.

In FIG. 2, a semiconductor epitaxial film 12 such as silicon is formed on a semiconductor insulating substrate 11 using a semiconductor raw material gas such as monosilane (SiH ₄ ), silicon tetrachloride (SiCl ₄ ), or trichlorosilane (SiHCl ₃ ). The substrate is heated to a temperature of 950° C. to 1200° C. and formed to a thickness within the range of 0.3 to 20 μm over the entire surface of the substrate. As described above, the formed epitaxial film 12 is free from contamination with Al, oxygen, etc. from the sapphire substrate 1, and exhibits good electrical characteristics and crystallinity. It goes without saying that the present invention is applicable not only to silicon semiconductor devices but also to compound semiconductor devices such as GaAs, InP, and SiC.

<Effects of the Invention> As described above, according to the present invention, a cubic zirconia film can be easily obtained by lowering the growth temperature of the stabilized zirconia thin film, expanding the area where the stabilizer is added, and further improving the stability of semiconductor devices. It is possible to provide an insulating substrate for semiconductors that does not adversely affect the performance of semiconductor devices when used for.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the basic structure of an insulating substrate for semiconductors according to the present invention, and FIG. 2 is a cross-sectional view of a silicon semiconductor substrate using the insulating substrate for semiconductors according to the present invention. 1: Sapphire substrate, 2: Single crystal stabilized zirconia film, 11: Insulating substrate for semiconductor, 12: Semiconductor epitaxial film such as silicon.

Claims (1)

[Scope of Claims] 1 The entire surface of a sapphire substrate is coated with a stabilized zirconia single crystal film to which a stabilizer containing an element with a mass number higher than yttrium (Y) is added in a content of 6.1 mol% to 19.4 mol%. An insulating substrate for semiconductors characterized by the following. 2 Zirconium oxide ZrO ₂ as the stabilizer
Itterbium oxide Yb ₂ O ₃ and samarium oxide inside
The insulating substrate for a semiconductor according to claim 1, wherein one type of stabilizer selected from Sm ₂ O ₃ and gadolinium oxide Gd ₂ O ₃ is added.