JPS62160757A - Semiconductor substrate - Google Patents

Abstract

PURPOSE:To form a semiconductor substrate (SOI substrate), which does not give adverse effect on the performance of a semiconductor device, by coating the entire surface of a silicon substrate with a single crystal film of stabilized zirconia. CONSTITUTION:The entire surface of a silicon substrate 1 is coated with a stabilized zirconia film made of an oxide single crystal, which is arranged by a sputtering method. For this coating, one kind of the following materials is added into zirconium oxide ZrO2 as a stabilizer within a range of 6.1mol%-12.6mol%: yttrium, oxide Y2O2, magnesium oxide MgO, calcium oxide CaO, samarium oxide Sm2O3, gadolinium oxide Gd2O3, terbium oxide Tb2O3, ytterbium oxide Yb2O3 and scandium oxide Sc2O5. Thus a single crystal in a cubic system is obtained at a growth temperature of 550-1,000 deg.C. Said stabilized zirconia film can maintain the crystal structure with respect to temperature history.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to improvements in semiconductor substrates.

It is used as <conventional technology>. SO8 technology is a MOS device made by growing a silicon thin film on a sapphire substrate by epitaxy, solving the conventional problems of wiring capacitance and isolation, and increasing the speed of MOS devices. It is.

<Problems to be solved by the invention> In SO8 technology, when a semiconductor such as silicon is epitaxially grown on a sapphire substrate at high temperature, a part of the base surface of the sapphire substrate is reduced by the hydrogen used as the raw material gas. The silicon epitaxial layer formed on the sapphire substrate may be doped with reduced metal At or oxygen and become contaminated, and there is also the problem of a relatively large lattice mismatch with the semiconductor material. Are known. Therefore, the electrical characteristics and crystallinity of the semiconductor layer epitaxially grown on the sapphire substrate are significantly deteriorated.

Furthermore, since the sapphire substrate itself is very expensive, the performance of this sapphire substrate as a practical substrate is hindered, and the reality is that it has not been fully put into practical use.

On the other hand, attempts have been made to form oxide single crystal films directly on silicon substrates, but these attempts have been difficult due to the natural oxide film formed on the silicon substrate surface, making it difficult to heteroepitaxially grow oxide single crystals. there were.

The present invention was devised in view of these points.
The purpose is to provide a semiconductor substrate that does not affect the characteristics of semiconductor devices.

<Means for Solving the Problems> A semiconductor substrate according to the present invention is such that the entire surface of a silicon substrate is coated with a single crystal film of stabilized zirconia formed from zirconium oxide to which a stabilizer has been added.

Effects> In the structure of the semiconductor substrate according to the present invention, the entire surface of the silicon substrate is covered with a stabilized zirconia film made of an oxide single crystal. Therefore, when used as a semiconductor substrate, even if semiconductor materials such as silicon are epitaxially grown at high temperatures (~1200°C), the substrate material will not be decomposed as it is now with sapphire substrates. , and no reduction reaction occurs.

Furthermore, since the stabilized zirconia thin film formed on the substrate surface is stable against active hydrogen, it does not contaminate the epitaxial growth layer of semiconductors such as silicon with zirconium (Zr) or oxygen, resulting in high-purity epitaxial growth. A membrane is 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, isolation between elements becomes easy, and latch-up becomes free.
It becomes possible to create ultra-high-speed, high-density, highly integrated VLSIs such as bipolar transistors and CMO8.

<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 a semiconductor substrate according to the present invention.

In FIG. 1, a single crystal stabilized zirconia film 2 ((ZrO2)+ -n(Y20a
) n Madada (Zr 02 ), -H(MgO) n.

(Zr02)+ -n (CaO)n, (ZrOz
)t −n(Sm20s)n, (ZrO2)+−n
(Gd203)n.

(ZrO2)+ -n (Tb203) n, (Z
rOz)t-yl(Yb+03)n, (ZrO2)
+-n(SC205)n) is coated. However, n
The value is between 0.061 and 0.126.

When the sputtering method is used, the base material zirconium oxide ZrO2 grows epitaxially at a growth temperature of 400°C, but the single crystalline film of this zirconia oxide ZrO2 has a monoclinic crystal system, and crystallizes into a tetragonal system at high temperatures. It is known to cause metastasis. Therefore, a volumetric expansion of 7.4% occurs due to the temperature history, resulting in self-destruction.

However, zirconium oxide ZrO2 contains yttrium oxide Y20a, magnesium oxide MgO, calcium oxide CaO, and samarium oxide Sm2 as stabilizers.
O3, gadolinium oxide Gd2O3, terbium oxide T
b2O3, ytterbium oxide Yb2O3゜Scandium oxide 5c205 6.1 mol% to 12.6
By adding within the range of mol%, the growth temperature can be increased to 550°C.
A cubic single crystal film is obtained at ~1000°C. It was found that this stabilized zirconia film maintains its crystal structure even under temperature history.

The feature of the present invention is that a stabilized zirconia film 2 is formed on the silicon substrate 1 by sputtering to a thickness in the range of 0.2 to 1.0 μm.

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

Next, an example of the manufacturing process of the semiconductor substrate according to the present invention shown in FIG. 1 will be specifically explained.

The stabilized zirconia film 2 described above is a silicon substrate (100
) 1 by reactive magnetron sputtering using Ar+02. The silicon substrate 1 is coated with HCI:H2O2"H in advance in order to remove the influence of the natural oxide film existing on the surface.
20=3:1:1, 90-100°C.

The sample was immersed for 5 to 10 minutes, and then heat treated in a vacuum at 900° C. for 30 minutes at 5 Pa (3×10 ) in a sputtering device. Thereafter, a stabilized zirconia film 2 was produced by sputtering, and the sputtering conditions were as follows: gas pressure (Ar+0
2) Stabilized zirconia film 2 was grown to a thickness of 1000 Å by using 0.5 pa, Rf power ~ 4 W/cn, and substrate temperature of 900°C.

As a result of crystal evaluation of the stabilized zirconia film 2 grown under the above conditions using RHEED, X-ray analysis, etc., growth of the (100) plane was observed, indicating that a good single crystal film had grown. Admitted.

Conventionally, it has been difficult to heteroepitaxially grow an oxide single crystal on the (100) surface of a silicon substrate due to the presence of a natural oxide film, but it is possible to perform a preliminary treatment to remove the natural oxide film as described above. As a result, it has become possible to easily form a stabilized zirconia film into a single crystal by sputtering.

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

In FIG. 2, a semiconductor epitaxial film 12 made of silicon or the like is formed on a semiconductor substrate 11 by using a semiconductor material gas such as monosilane (SiH4), silicon chloride (SiCl2), or dichlorosilane (S i HCt3) to maintain the substrate temperature. It is heated to 950° C. to 1250° C. to form a thickness in the range of 0.3 to 20 μm over the entire surface of the substrate. As described above, the formed epitaxial film 12 exhibits good electrical properties and crystallinity without worrying about contamination with At or oxygen from the sapphire substrate 1.

Note that the present invention is applicable not only to silicon semiconductor devices.
It goes without saying that the present invention can also be applied to compound semiconductor devices such as GaAs, InP, and the like.

<Effects of the Invention> As described above, according to the present invention, a semiconductor substrate is constructed in which a single crystal film of a high-quality oxide is formed on a silicon substrate,
This results in sharpening of the semiconductor device.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the basic structure of a semiconductor substrate according to the present invention, and FIG. 2 is a cross-sectional view showing a silicon semiconductor substrate using the semiconductor substrate according to the present invention. 1...Silicon substrate, 2...Single crystal stabilized zirconia film, 11...Insulating substrate for semiconductor, 12...Silicon epitaxial film. Agent Patent attorney Aihiko Fukushi (and 2 others) Figure 1 NLL Koshi Ushiko Furi Line Tai ω Ward Figure 2

Claims (1)

[Claims] 1. Using a sputtering method, growing at a temperature of 550°C to 1000°C.
C, and a stabilizer added in an amount of 6.1 mol% to 12.6 mol%, the entire surface of a silicon substrate is coated with a single crystal film of stabilized zirconia. 2. Yttrium oxide Y_2O_3 and magnesium oxide M in zirconium oxide ZrO_2 as the stabilizer.
gO, calcium oxide CaO, samarium oxide Sm_2
O_3, gadolinium oxide Gd_2O_3, terbium oxide Tb_2O_3, ytterbium oxide Yb_2O_
3. The semiconductor substrate according to claim 1, wherein one type of stabilizer selected from the group consisting of scandium oxide Sc_2O_5 is added.