JPH0216720A - Solid phase epitaxy method - Google Patents

Abstract

PURPOSE:To extend the lateral growth length of epitaxial growth by a method wherein an aperture for a seed is so formed as to have a linear pattern with a width not less than 50mum and an a-Si film is formed by a depressurized CVD method at 520-530 deg.C. CONSTITUTION:An SiO2 film 2 is deposited on a single crystal Si substrate 1 by a CVD method. Then the SiO2 film 2 is patterned so as to form a linear aperture 2' along the orientation <100> of the substrate 1. At that time, a seed part 1' is so formed as to have a linear pattern having a width (d) not less than 50mum. Then, in order to clean an a-Si film forming surface, the substrate 1 is placed in the reaction tube of a depressurized CVD apparatus. An Ar plasma is generated and the substrate 1 is sputtered to clean the surface. After that, the temperature of the substrate 1 is elevated to 520-530 deg.C and SiH4 gas is supplied to build up an a-Si film by vapor growth and the a-Si film 3 is formed on the seed part 1' and the SiO2 film 2. Then an annealing treatment is carried out to convert the film 3 into a single crystal Si film 3'.

Description

DETAILED DESCRIPTION OF THE INVENTION A) Industrial Application Field The present invention is directed to the formation of an SOI structure.
This invention relates to a method for solid-phase epitaxial growth of i-films.

r: 1) Conventional technology The one in which a single crystal Si layer is formed on an insulating layer (including an insulating substrate) is 5OI (S 1 con on Insul).
It is known as a structure in which elements can be easily separated in a narrow area and can be highly integrated and operate at high speed. Compared to semiconductor integrated circuits (ICs) in which elements are fabricated on conventional Si substrates, R&D is actively being carried out because the characteristics can be improved [e.g.
nese Journal of Applie
d Physics Vol, 26°No, 1
1. November, 1987. pp-1Si6-1
822).

The in-phase epitaxial growth method is used to form a single-crystal Si film on an insulating layer.This method forms an insulating film on a single-crystal Si substrate by exposing a part of the Si substrate surface as a seed. and amorphous Si (hereinafter a-
A-fSi
This makes the film single-crystal.

C] fs problem to be solved by the invention However, in the conventional in-phase epitaxial method, the distance from the seed for single crystallization in the lateral direction is short, and only a small area SOI structure can be obtained.

The present invention has been made with these points in mind, and provides a solid-phase epitaxial growth method that can extend the lateral single crystal growth distance from a seed in solid-phase epitaxial growth and form an SOI structure with a larger area. It is something to do.

2) Means for Solving the Problems The present invention is a solid-phase epitaxial growth method in which a hole is opened in an insulating film and the exposed seed has a line shape with a width of 50 μm or more. This is a solid phase epitaxial growth method in which a-fSi is deposited on the substrate by low pressure vapor phase growth at a growth temperature of 520°C to 550°C.

E) Effect: By making the shape of the seed into a line shape with a width of 50 μm or more, the single-crystal Si surface exposed as the seed can be well cleaned, and the in-phase epitaxial growth distance of the a-8 mass film can be improved. grows. In addition, a-S by reduced pressure vapor phase growth
By depositing the i film at a growth temperature of 520°C to 550°C, a high quality a-Si film is formed.
The in-phase epitaxial growth distance of the a-Si film increases.

Example FIG. 1 shows a schematic process diagram of an embodiment of the present invention.

In this embodiment, a single crystal Si substrate is used as the single crystal Si base, but a single crystal Si film formed on the substrate may also be used.

11) is a single-crystal Si substrate as a single-crystal Si base with the (100) plane as the main surface, and an insulating film on the surface with a thickness of 1
Approximately 2 SiOZ films (21 are CVD (chemical vapor deposition)
Deposit it by law (Figure 1 person). Single crystal Si substrate (1
2-inch opening in the <100> direction of 1 (2-inch, S
A shiba pattern is formed on the i02 film (2) by photolithography technology (FIG. B). At this time, as shown in FIG.
The shape of the seed portion +11 in which the substrate tlj surface is exposed is formed in a line shape with a width d of 50 μm or more.

Next, a Ka-Si film is formed on the entire surface.
The Si forming surface, especially the seed part (6 surface), is cleaned. Prior to cleaning the seed part uf surface, a vacuum CV (not shown)
The inside of the reaction tube of apparatus D is cleaned together with the substrate holder (susceptor).In other words, the inside of the reaction tube is cleaned with 8 x 10-'To
After creating a vacuum state below RR, the temperature was raised to 600°C and maintained at a vacuum level below 1 x 10-' Torr, Ar gas was introduced at a flow rate of 120 SCCM, and R
Ar plasma is generated by applying RF with an output of about 50 W using an F oscillator, and a negative voltage of 5QQV is applied to the substrate holder to perform sputtering on the inside of the reaction tube and the substrate holder using the Ar plasma. After sputtering for 30 minutes, the temperature is lowered to room temperature while the degree of vacuum is 5×10 Torr or higher.

Now, the substrate 11) on which the Si0z film (2) has been selectively formed is placed inside the convection tube (not shown) of the vacuum CVD apparatus that has been cleaned in this manner. Then, set the substrate temperature to 550
While the temperature is raised to and maintained at °C, At gas is introduced into the reaction chamber at a flow rate of 1208 CCM as described above, and RF of 1556 MHz is applied using an RF oscillator to generate Ar plasma. The low RF output at this time is about 50 films.

Then, when a negative voltage of about 500V is applied to the substrate, Ar
The + ions collide with the substrate surface and the substrate is sputtered, thereby cleaning the surface. The sputtering time required for cleaning is about 30 minutes.

When cleaning of the substrate surface is completed, the supply of Ar gas is stopped, and the substrate temperature is lowered to 530° C. and maintained.

Thereafter, SiH4 gas was supplied into the reaction tube at a flow rate of 50 SCCM and a SiH4 partial pressure of 10'pOrr to perform vapor phase growth of an a-84 film, and an a-Si film ( 3) is deposited (Fig. 1C).

At this time, the film thickness of the a-Si film (3) was 15 μm (
approximately 2 μm].

Finally, an annealing process is performed for 12 hours in a N2 atmosphere (atmospheric pressure) where the substrate temperature is set and maintained at 600°C. Then, solid-phase epitaxial growth is performed in the lateral direction while inheriting the crystal orientation of the seed part (1), and the a-Si film (3) becomes a single crystal, forming a single crystal 8 (3) (Fig. 1D). ).

FIG. 6 shows the seed portion uf (the width d of the opening (21) and the a-Si Membrane (3
) shows the relationship with the lateral growth distance for single crystallization. As shown in Figure 5, @d of the seed part (opening part) is 50
Above μm, the lateral growth distance is stable and good, but
When it becomes less than 50 μvz, the lateral growth distance becomes extremely poor. By setting the width d of the seed part to 50 μm or more, the surface of the seed part + This is thought to be because the -Si film is successively single-crystalized (epitaxially grown) without any time delay. In addition, the residual stress from the edge portion of the insulating film (2) in the opening (2S) that acts to inhibit growth (epitaxial growth) that inherits the crystal orientation of the seed surface is caused by the width of the seed portion d'? This is because by doing so, the a-si film will not be affected much.

Now, FIG. 4 shows the a-S
It shows the lateral growth distance at which the i-film 13) becomes a single crystal. As can be seen from FIG. 4, as the substrate temperature (growth temperature) increases, the lateral growth distance gradually becomes shorter. If the substrate temperature is high, the polycrystalline and antagonistic portions in the deposited A-8T film increase, and these polycrystalline portions grow as grain boundaries that inhibit epitaxial growth during annealing. However, by forming a high-quality a-Si film with fewer polycrystalline parts as an amorphous film, the lateral growth distance can be increased.
It will be fine if the temperature is below 0°C.

However, if the substrate temperature (growth temperature) becomes lower than 520°C, the a-Si film will hardly be deposited (the deposition rate becomes extremely slow), so the substrate temperature (growth temperature) should be 520°C or more and 550°C or less. A high quality a-Si film can be obtained by forming the a-Si film at a temperature of .

g) Effects of the invention It is clear from the above description that the present invention can be achieved by forming the opening for the seed into a line shape with a width of 50 μm or more, or by growing the crystal-Si film at a growth temperature of 520°C or more. 5
By forming the layer by the reduced-irradiation CVD at 50° C., the lateral growth distance for epitaxial growth can be extended. Therefore, it is possible to form an SOI structure with a much larger area.

[Brief explanation of the drawing]

Fig. 1 is a schematic process diagram of an embodiment of the present invention;
The figure is a top view showing the shape of the opening, Figure 5 is a diagram showing the relationship between the width of the opening and the lateral growth distance, and Figure 4 is the factor showing the relationship between the growth temperature and the lateral growth distance. . (1)...Single crystal 5 (2)...Si02 film (3)...a-Si film i-substrate (11...Seed part (insulating film) (2 pieces...Opening part ( 3S...Single crystal Si film

Claims (2)

[Claims] (1) Forming an insulating film on a single crystal Si base, selectively forming an opening in the insulating film to expose the surface of the single crystal Si base, and forming an opening on the single crystal Si base and the insulating film. amorphous S
A solid phase epitaxial growth method for forming an i-film and annealing the amorphous Si film to form a single crystal, characterized in that the opening has a line shape with a width of 50 μm or more. Method. (2) Forming an insulating film on the single crystal Si base, selectively forming an opening in the insulating film that exposes the surface of the single crystal Si base, and forming an opening on the single crystal Si base and the insulating film. amorphous S
In a solid-phase epitaxial growth method in which an i film is formed and the amorphous Si film is annealed to become a single crystal, the amorphous Si film is formed by low pressure vapor phase growth at a growth temperature of 520°C to 530°C. A solid phase epitaxial growth method characterized by: