JPH0264098A - Method for growth of si thin film - Google Patents

Abstract

PURPOSE:To efficiently grow an Si thin film by growing an Si layer on an opening part of a dielectric insulation film layer on a semiconductor base, depositing an silicide layer on the grown film and insulation film layers heat treating the silicide layer, separating and growing Si out of the silicide layer. CONSTITUTION:A dielectric insulation film layer 12 (e.g., oxide film) is formed on a semiconductor base 11 (e.g., Si base) and an opening part 13 is formed at the prescribed part of the insulation film layer 12. An epitaxial growth of an Si layer 14 is then carried out selectively on the opening part 13 and a silicide layer 15 (e.g., tungsten silicide film) is then deposited on the insulation film layer 12 and the Si epitaxial growth film 14. The silicide layer 15 is subsequently subjected to heat treatment to separate Si 16 out of the silicide layer 15. The separated Si 16 is subjected to solid phase epitaxial growth from the part in contact with the Si epitaxial growth film 14 in the horizontal direction, thus obtaining the objective Si thin film 17.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming a semiconductor film, and more particularly to Si epitaxial lateral overgrowth.

(Prior art) As a method of forming a Si single crystal film on a dielectric insulating film,
A method is known in which polycrystalline Si is deposited on an oxide film and a heat treatment is performed from the seed portion to grow a Si single crystal laterally on the oxide film. (Applied Physics Association Lecture Proceedings 1988 Spring 2nd Minute Np, 5822
8p-M-2: Solid-phase epitaxial growth of CVD Si film [Engineering]) (Problem to be solved by the invention) In the conventional technology, when growing polycrystalline Si by solid-phase epitaxial growth, it is difficult to grow polycrystalline Si on a dielectric insulating film. Since the crystalline silicon begins to grow nuclei at the same time, the lateral solid-phase epitaxial growth stops when the epitaxial growth layer that extends laterally from the seed part contacts the part where the nuclei have grown.

An object of the present invention is to provide a method for growing a Si thin film that solves this problem.

(Means for Solving the Problems) A step of forming a dielectric insulating layer on a semiconductor substrate, a step of forming an opening in a predetermined portion of the dielectric insulating layer, and a step of forming a Si layer selectively in the opening. a step of epitaxially growing a silicide layer, a step of depositing a silicide layer on the dielectric insulating film edge layer and the Si epitaxial growth, and a step of applying heat treatment to the silicide layer to epitaxially grow Si from the silicide layer from a portion in contact with the Si epitaxial growth. This invention provides a method for growing a distinctive Si thin film.

(Function) Physical growth methods such as sputtering and vapor deposition generally allow the formation of a film of a compound having a composition that deviates from the stoichiometric composition. The film thus formed undergoes phase separation through subsequent heat treatment into an equilibrium layer having a thermodynamically stable stoichiometric composition and the remaining precipitated phase. At this time, the amount of substances that are to become precipitates contained in the film with a composition that deviates from the stoichiometric composition is lower than that which would result in solid phase three-dimensional nucleation at a specific heat treatment temperature, but the solid phase The inventors have discovered that when the amount is sufficient for epitaxial growth, it is possible to cause epitaxial overgrowth only in a predetermined portion, leading to the present invention. That is, in the present invention, S
A silicide having an i-rich composition is formed, and then this silicide is heat-treated to precipitate Si. This precipitated Si is used to cause epitaxial overgrowth.

(Example) [Example] A p-type 5i (100) substrate 11 was thermally oxidized at 950°C to form an oxide film layer 12 of 500 OA. An opening 13 exposing the substrate Si was formed in a predetermined portion of the oxide film layer 12 by photolithography. Next, selective epitaxial growth was performed at 850°C, 5 pressures, 30 Torr, and H2120.
1/min, 5iH2C12300cc/min,
The Si epitaxial growth film 14 was formed to almost the same height as the oxide film layer 12 under the condition of HCI 300 cc/min. FIG. 1(a) shows a schematic cross-sectional view at that time. Subsequently, a tungsten silicide film 15 was deposited to a thickness of ~lpm by sputtering. A schematic cross-sectional view at this time is shown in FIG. 1(b). In film formation by this sputtering method, the composition of the target was WiSi=1:x (2<x≦4). If the value of When the value exceeds 4, three-dimensional nucleation of Si occurs from the tungsten silicide film in the subsequent heat treatment, and similarly, a large aspect ratio with a large growth rate in epitaxial lateral overgrowth cannot be obtained. Furthermore, the substrate temperature during film formation by sputtering was in the range of room temperature to 300°C.

As a result of evaluating the crystallinity of the formed film using an electron beam, it was found that amorphous tungsten silicide was formed when the substrate temperature was below 100°C, and polycrystalline tungsten silicide was formed when the substrate temperature exceeded 100°C. Substrate temperature is 300°
Above C, a precipitated layer of Si was found, and phase separation had already progressed. When a tungsten silicide film formed by such a sputtering method is heat-treated, grain growth occurs using existing Si particles as nuclei, which hinders epitaxial overgrowth. Therefore, the substrate temperature should be increased from room temperature to 300°C.
This was done within the range of The sputtering gas is Ar, and the pressure is 5X.
Film formation was performed at 10-'' Torr.

The substrate with the tungsten silicide film formed as described above was heat-treated under N2 atmosphere at 600°C.
By performing the heat treatment for 30 minutes, a Si precipitate 16 is formed at the interface between the Si and the tungsten silicide film 15, and then the temperature is raised to 80,000°C and heat treatment is performed for 5 hours, resulting in ~3,000°C.
An epitaxially grown film 17 was obtained in the lateral direction of the person. A schematic cross-sectional view at this time is shown in FIG. 1(C,).

In the heat treatment at 600°C, excess Si precipitates very slowly, and the diffusion distance of Si atoms in the tungsten silicide film is small, so that the Si single crystal surface in the opening formed by selective epitaxial growth is almost always deposited. Only when epitaxial growth occurs. As a result, a temperature distribution of solid solution Si is formed in the tungsten silicide film around the opening. The gradient of this temperature distribution depends on the heat treatment temperature and heat treatment time; the lower the temperature, the steeper the temperature distribution, and the longer the heat treatment time, the wider the formation. In the case of 30 minutes at 600°C, phase separation occurs into WSi2 and Si in the longitudinal direction of the opening, and there is no concentration distribution of excess Si in solid solution. but,
A change in the concentration of excess Si was detected by SIMS analysis over a one-dimensional range of ~1 μm in the lateral direction from the opening. Next, when the heat treatment temperature was raised to 800° C., diffusion of S into the tungsten dinoside film was promoted, and this -dimensional temperature distribution was expanded and epitaxial overgrowth occurred. By heat treatment for 5 hours, a single crystal film with a thickness of 3000 mm and a width of ~8 μm in the lateral direction was obtained on the oxide film.

[Example 2] In Example 1, the heat treatment process was carried out in two stages, but the temperature was increased from 600 °C to 800 °C in 30 minutes at a temperature increase rate of 6 °C/min, and then 5 A similar effect can be obtained by time heat treatment.

[Example 3] The silicide used in Examples 1 and 2 was used as the tungsten silicide film 15, but other elements that can form silicide (for example, Ti, Zr, Hf, V, N
b, Ta.

Mo, Co, Ni, Pb, Pt, K, Ca
, Sc, Rh, Cu, As, Se, Br,
P.

CI, Rb, Sr, Y, Ba, La, Te
, J, Ce, Pr, Nd, Sm, Gd,
Dy.

Er, Yb, Lu, Th, U, Np, Pu
), epitaxial overgrowth is also possible.

(Effects of the Invention) When the present invention is applied, grain growth using Si particles as nuclei can be suppressed since lateral growth is performed from silicide having a Si-rich composition. Since epitaxial lateral overgrowth is not stopped due to nuclear growth, lateral growth can be performed satisfactorily.

[Brief explanation of the drawing]

FIGS. 1(a) to 1C) are schematic cross-sectional views of semiconductor films according to the present invention. In the figure

Claims (1)

[Claims] A step of forming a dielectric insulating layer on a semiconductor substrate, a step of forming an opening in a predetermined portion of the dielectric insulating layer, a step of epitaxially growing a Si layer selectively in the opening, and a step of forming a dielectric insulating film. A step of depositing a silicide layer on the edge layer and the Si epitaxial growth film, and a step of applying heat treatment to the silicide layer to solid-phase epitaxially grow Si from the silicide layer from a portion in contact with the Si epitaxial growth film. Featured S
iThin film growth method.