JPH01290595A - Formation of si/al2o3/si multilayered structure - Google Patents

Abstract

PURPOSE:To improve both electrical characteristics and stability at a time of heat-treatment at high temp. by growing an Si single crystal film on a gamma-Al2O3 single crystal film formed on an Si base plate. CONSTITUTION:Both trimethylaluminum and gaseous N2O are fed on an Si base plate heated at 720-800 deg.C and a gamma-Al2O3 single crystal film is grown in partial pressure not higher than 5X10<-5>Torr by a molecular beam epitaxial method. Then an Si single crystal film is epitaxially grown on this gamma-Al2O3 single crystal film by utilizing gaseous Si2H6.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a method for forming a Si film At203/Si multilayer structure used in the industry for manufacturing semiconductors such as integrated circuits and transistors.

"Prior art and its problems" Single crystal insulating films on Si substrates are used for three-dimensional integrated circuits and SO
It is one of the elements necessary for realizing an I (Si on In5ulator) element.

For this reason, various insulating films have been studied so far, but they still have some problems in practical use and are not yet fully satisfactory.

If it becomes possible to create a three-layer multilayer structure in which an Al2O3 film is epitaxially grown on a Si substrate and a Si film is epitaxially grown thereon, various significant effects will be produced. First, since the substrate is Si, 5OS (Si
On 5apphire), the price is significantly lower than the large diameter 5ol (Si on 5apphire).
ter) substrate, and since it has a sandwich structure of epitaxial Si/γ-Al2O3/substrate Si, it has the advantage of reducing compressive stress. Furthermore, it also has excellent advantages as described below.

(1) The lattice mismatch between S i -A I2O3 is smaller than 2.42t SO3.

(2) The interface level of γ-Al2O3/Si is lX1O
It is as low as eVca-'.

(3) Works effectively as a barrier against Na and other impurities.

(4) Great radiation damage resistance effect.

(5) It has a high dielectric constant (ε-8 to 9).

(6) γ-A1゜03 is stable even at a high temperature of 1100°C. Conventionally, in order to grow γ-Al2O3 on a Si substrate by low pressure vapor phase epitaxy, it takes 10
Although a substrate temperature close to 00° C. was required, there was a problem that such a high temperature was too high to form a multilayer structure to form a three-dimensional integrated circuit. That is, when a semiconductor device is assembled in Si and a γ-Al2O3 insulating film is formed thereon, if the temperature is close to 1000° C., the impurity concentration in the semiconductor device will differ.

The present invention eliminates these drawbacks and allows γ to be grown at a low growth temperature.
-Si/Al2O3/S+ to grow AlO insulating film
The purpose is to provide a method for forming a multilayer structure.

"Means to solve problems" This forms a shrimp layer.

In order to achieve the above object, the present inventors conducted intensive research and discovered that trimethylaluminum and N20 gas were mixed at 5xlO-
By epitaxially growing a molecular beam on a Si substrate under the reaction conditions of a substrate temperature of 720 to 800°C, extremely high quality γ-AI,. The present invention was achieved by discovering that a film can be formed.

That is, the present invention uses trimethylaluminum and N20 gas as gas sources, and under a low partial pressure of 5XIQ') or less,
At a low temperature of 720 to 800°C, a γ-Al2O3 single crystal is grown on a Si substrate by molecular beam epitaxial method, and then a Si single crystal film is grown on the γ-Al2O3 single crystal film. It is characterized by

"Example" Next, one example of the present invention will be given to further explain the present invention.

Briefly explaining the method of the present invention, first, as shown in FIG. 1, a γ-Al2O3 single crystal film was grown on a Si wafer, and then Si was formed on the film using Si2H6.

Using a 2-inch Si (100) wafer as a substrate, the substrate temperature was 72°C in a molecular beam epitaxial growth apparatus.
Partial pressure 3X10 of trimethylaluminum heated to 0-800°C and bubbled with N2 gas as reaction gas
γ-
An Al2O3 crystal film was epitaxially grown.

In the present invention, one reaction temperature is 720°C to 800'0
However, if the temperature is lower than 720℃, γ-Al2O3 will not become a single crystal, and the temperature will be lower than 80O”C.
This is because, if the temperature exceeds 100 nm, the impurity concentration in the semiconductor device will differ in the case of forming a multilayer structure as described above, and the surface unevenness of the γ-AI 203 single crystal will become severe.

The orientation of the substrate (7) S i is (100), (1
11) Epitaxial growth was possible regardless of the edge.

From the reflected electron beam diffraction patterns in Figures 2 and 3, the relationship between the plane orientations is as follows: γ-Al2O3
(100)/S+(100)γ-A I203(111
)/Sl (111) It has been confirmed by analysis using Auger electron spectroscopy that the composition of the film grown as described above is composed of AI and 0.

Next, γ-Al2O3 (1o
O)/5i(100) On the top, Si, H6 gas is used for IT' ”C, SiOx bitaxial growth is performed, and the grown film is 5i(100)/γ-Al2O3(100)
/S+(100) structure was revealed from the reflection electron diffraction results shown in FIG. It has been experimentally confirmed that this third layer of Si can be grown at approximately 700°C using molecular beam epitaxial growth, and that it can be grown under the same conditions as normal SO8 growth using vapor phase growth. There is.

"Effects of the Invention" As described above, according to the present invention, it is possible to easily form an insulating film on a Si substrate that exhibits remarkable electrical characteristics and has excellent stability during high-temperature heat treatment.
It will greatly contribute to the realization of dimensional integrated circuits and SO2 devices.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the Sl/Al2Cl3/S+ multilayer structure of the present invention, FIG. 2 (1) is an electron micrograph showing a RHEED image of a 5i (100) substrate before deposition, and FIG. )teeth. Backscattered electron diffraction pattern before deposition, Figure 2 (3
) is γ-Al2O3(100)/S after deposition
+ Electron micrograph showing a RHEED image of (100),
Figure 2 (4) shows γ-Al2O3 (1
00)/5i(100), FIG. 3(1) is an electron micrograph showing the RHEED image of the 5i(111) substrate before deposition, and FIG. 3(2) is the electron micrograph showing the RHEED image of the 5i(111) substrate before deposition. Backscattered electron diffraction pattern before deposition, Figure 3 (3
) is γ-Al2O3(111)/5 after deposition
Electron micrograph showing RHEerJ image of i(II+),
FIG. 3 (4) shows γ-A after deposition! 203(1)
The reflected electron diffraction pattern of γ-Al2O3(100)/Sl (11)/5i(111), Figure 4(1), is
100) 5i (10
0) Electron micrograph showing RHEED image from membrane, 4th
Figure (2) shows Si(+00)/γ-Al2O3(100
)/5i (100) surface reflection electron beam diffraction pattern. Patent applicant Toyoko Chemical Co., Ltd. President of Toyotachi University of Technology Namio Honda Sj2/-1e Figure 2

Claims (1)

[Claims] Using trimethylaluminum and N_2O gas as gas sources, under a low partial pressure of less than 5×10^-^5 Torr, 72
A γ-Al_2O_3 single crystal film is grown on a Si substrate at a low temperature of 0°C to 800°C by molecular beam epitaxial method, and then a Si single crystal film is grown on the γ-Al_2O_3 single crystal film. Characteristic method for forming a Si/Al_2O_3/Si multilayer structure using an epitaxial method.