JPS5893215A - Manufacture of semiconductor singlecrystal thin film - Google Patents

Abstract

PURPOSE:To effectively manufacture three-dimensional integrated circuits by a method wherein a singlecrystal semiconductor layer is formed on a substrate formed with an insulating film thereon to make elements such as photo transistors with a good electric characteristic on that semiconductor layer. CONSTITUTION:An SiO2 film 12 is selectively formed on an Si singlecrystal substrate 11 through thermal oxidation. With it being put in a vacuum apparatus, an amorphous Si film 13 is deposited thereon in a given thickness through electron beam evaporation under vacuum. Then, after being taken out to the atmosp here, the wafer undergoes heat treatment in N2 for a given time to develop a singlecrystal Si film 14. A laser beam is irradiated on the surface of thus attained sample to melt and recrystalize the Si layer on the film 12, thereby to effect epitaxial growth. At the time of such laser irradiation, the substrare 11 is heated at given temperature, and after laser irradiation the film 13 on the film 12 is monocrystalized. Then, n type channel MOS transistors or so are formed on the monocrystalized film. In this way, three-dimensional integrated circuits are formed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a structure in which a single crystal semiconductor thin film is grown from a semiconductor single crystal surface on an insulating film existing on a part of the semiconductor single crystal surface.

Prior art and its problems Single crystal thin films on insulating plates have the following advantages, as can be seen in the example of SO8 (silicon on sapphire). Or, isolation between elements can be easily and completely achieved by dielectric isolation.
2) When making this m1Ia 17r MOS inverter circuit, the switching speed tW is high because there is no substrate bias effect. ■ Parasitic floating zero failure is small and high speed can be achieved.

However, the problem remains that SO8 uses single-crystal sapphire, which increases the price.・Top (S)
There have been attempts to use semiconductors deposited on iN, 5i02, etc. Thin film structures such as these have recently been developed and are made possible in part by laser annealing techniques.

In other words, taking No. 81 as an example, after forming an S + 02 by etching an S+ silicon crystal substrate, a hole is formed by removing a part of it, and then polycrystalline Si is deposited on the entire surface. Polycrystalline Si is continuously deposited from the surface of the Si substrate to the top of 8102.
Extend it with Next, when an energy beam is scanned and irradiated, the polycrystalline Si melted on the surface of the semiconductor substrate becomes a single crystal by liquid phase epitaxial growth from the substrate, and further, in the scanning direction of the beam, the polycrystalline Si on the SiO2 continues to become a single crystal. It is said that it will be converted into

However, the following drawbacks are observed even in the '4 film obtained by this method. That is, when the beam output was low, horizontal lattice defects were formed from Si on the semiconductor substrate toward 8102 at the edges of the beam scanning band. On the other hand, as the beam power is increased, S'
The phenomenon of roughening of the Si coating surface on 02 has been confirmed. As described above, with the conventional method, it is extremely difficult to form a single crystal film containing no lattice defects and having excellent surface smoothness on a crystalline film such as 8+02.

Purpose of the Invention The present invention has been made in view of the above circumstances, and provides a method for forming a single crystal semiconductor layer with excellent crystallinity and surface smoothness on an insulating film. .

Examples of the invention Examples will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the invention.

((')nl)Si single crystal substrate (1υ thermally oxidized to 0.5
After forming 5iO21 sample 2 of μm, an opening was made.

1 (Remove the natural oxide film on the surface of 81 using F solution, wash with pure water for 10 seconds, wash with Ik, dehydrate and immediately input into the empty device 2.5 x 1.0 "I" Amorphous Sr(13) was deposited by electron beam evaporation in a vacuum of 0.5 orr.
, um only product l~ (Figure 1(a)). Next, this wafer was taken out into the atmosphere and then heated at 600'O for 2 hours with N
Heat treatment was performed in 2. This heat treatment causes in-phase epitaxial growth of the amorphous 81 layer on the open Si active plate.
~, single crystal SimQ4) and S' 02-
Single crystals were formed in the lateral direction up to 11 tm (Fig. 1 (b)
)). Next, the surface of the sample was irradiated with a C laser beam to melt and recrystallize 8!% of the SiO2, resulting in epitaxial growth in the lateral direction (Fig. 1 (C)).The laser beam used was a continuous wave type laser beam. The output of an argon laser is 8N÷
It was 1. During laser irradiation, the substrate was heated to 500'O. After laser beam irradiation, the Si film on the 5102 layer became a single crystal (13)'. An N-channel MO8) transistor (15) was made on this single crystal t6t+31, and the carrier mobility was measured to be 800 ffl/ The value of see was only slightly lower than that of the Belk 5i (001) plane (Fig. 1(d)).

FIG. 2 shows a second embodiment of the invention.

SiN was applied as an I oxidation-resistant mask through the first 5i02@'2″2 to the location where the opening of the Si substrate (21) was to be formed.
After forming the film (23), the Si pigeon plate is etched with a KON solution (FIG. 2(a)). Next, oxidation was carried out in a 1000° ClO2 gas atmosphere, and a second sio2 film of 0.5 ttm was applied to the area other than the deposited area. remove (
211(b)). Next, using the second CvD method, polycrystalline Sr
After depositing a thin layer (0.3 μm thick), S+ ion implantation (
Applied energy: 180KeV.

The polycrystalline Si is made into an amorphous Si film by applying a dose of 8xl 015 (x ”). This sample is exposed to N2
Heat treatment was performed at 600°C for 2 hours. As a result of this heat treatment, the amorphous layer on the Si hole plate in the opening caused in-phase epitaxial growth to become a single crystal layer (251), and also became single crystal in the lateral direction (12) as shown in FIG. Second
Figure (C)). Next, the surface of the sample was irradiated with an argon laser under the same conditions as in the example shown in FIG.

It was observed that the Si film surface after irradiation had a smooth surface similar to the Si film before irradiation, and that the entire 81 area was still single crystallized.

Next, we will discuss the reason why the method of the present invention satisfies both Si crystallinity and Si surface smoothness.
Thermal conductivity of 8 + 02 is about 1/10 compared to that of Si.
0, therefore, the heat escape when the beam is irradiated is 5
When the 102 membrane is expanded, the amount decreases. Therefore, in one case of irradiation with the same energy, 1 change in the 81 film on the Sil board is smaller than that of the Sr film on 5102114'.

In the conventional method, the 81 pattern on the Sil plate and the S1 pattern on the 5IO2 layer are melted and turned into autocrystals, so if you try to melt the former, the temperature of the latter will rise more than necessary, and the temperature will increase. The surface may become rough or partially evaporate. On the other hand, if an attempt is made to melt the latter, the temperature must become sufficiently high in the former, especially near the edge of the beam, or lattice defects will be introduced, which will extend to S1 on 5i02.

On the other hand, in the method of the present invention, since the 81 film on the Si substrate is crystallized by solid phase growth, there is no need to melt it during beam irradiation, and only the Si film on the 5IO2 is melted and recrystallized. It is considered that this makes it possible to satisfy the crystallinity and surface smoothness.

Effects of the Invention As described above, according to the present invention 1C, a single crystal semiconductor layer can be formed on an insulating film, and an element such as a transistor can be formed on this single crystal semiconductor layer with excellent chemical characteristics. It became possible. Therefore, integrated circuits can be manufactured not only on a semiconductor substrate but also three-dimensionally, and the same effect as the degree of integration can be obtained.

Other Embodiments of the Invention Although Si was used for the substrate and the semiconductor film in the above embodiments, it goes without saying that the effects of the present invention can also be achieved with Ge, GaA, s, GaP, InP, etc. . Also, the effect may be reduced depending on the method of forming the semiconductor film, the method of forming the amorphous layer, their thickness, etc. (A
o Although a thermalized S+02 film is used as the insulating film, the effect of the present invention is not reduced by the material of the insulating film, its formation method, its thickness, etc. (d) It is obvious that the heat treatment temperature is 400°C. ℃ or more is sufficient.Also, the effect of the present invention could also be achieved by a method (C) in which a high temperature heat treatment at 900'O or the like is performed after a low temperature heat treatment.

Energy beam 74 kr +/- only p, Nd
-YA() laser, ruby laser, or other laser light, and even if an electron beam is used, the effects of the present invention will not be impaired.

Note that the atmosphere during heat treatment and beam annealing is limited to N2.02. Inert gas such as Ar and mixture of these gases,
Furthermore, similar effects could be achieved even in a vacuum.

[Brief explanation of drawings]

Figure 1 (・) to (d) and 1j Figure 21 (a) to (
.) are sectional views for explaining details of the present invention. 11.21 ・S+ single crystal plate 12. ．． 22.24
...SiO2 film, 23...Si film, 13...amorphous Si film, 14.25...single crystal sI model. Figure 1 Figure 2) 7

Claims (1)

[Claims] A step of selectively forming an insulating film on a semiconductor single-crystal wood board, a step of forming an amorphous semiconductor layer on the substrate on which the insulating film is formed, and a step of solid-phase epitaxial growth of the amorphous layer on the substrate by heat treatment. and a step of subsequently melting and recrystallizing the semiconductor layer on the insulating layer using the single crystal on the substrate as a seed by irradiating it with an energy beam, thereby causing epitaxial growth in the lateral direction. A method for manufacturing semiconductor single crystal thin films.