JPS61247680A - Soi crystal growth process - Google Patents

Abstract

PURPOSE:To grow easily a SOI CRYSTAL by forming an insulated SOI sample to have a structure that a polysilicon film doped with oxygen is inserted between oxidized films and allowing the heat conductivity of a seed to approach a heat conductivity of the insultated SOI sample. CONSTITUTION:After forming an oxidized film 2 on a Si (100) substrate 1, the oxidized film 2 is patterned by forming a polysilicon film 3 doped with oxygen by carrying out vapor growth reaction between SiH4 gas and N2O gas. The film 3 is then oxidized to form an oxidized film 4. Then, a seed part 8 is formed by causing growth of monocrystalline Si; thereafter, a polysilicon film 5, oxidized film 6, and a nitrided film 7 are deposited and heat-treated to obtain thus a SOI sample having a seed. The sample is then irradiated with linear electron beam to cause growth of SOI crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming SOI crystals by melting an amorphous or polycrystalline film deposited on a surface.

[Conventional technology]

When a laser, an electron beam, or other heat source is used to melt and crystallize an amorphous or polycrystalline semiconductor thin film attached to the surface of an SOI structure sample having a sheet, the sheet part and the SOI structure part are separated. In comparison, SOI
The structure usually has an insulating film such as an oxide film or a nitride film, so
163rd 5ociety M, which has poor thermal conductivity and is known to melt at a lower incident power than the sheet part.
ceting+Extended Abstracts
vol, 83-1 p 574゜ [Problems to be solved by the invention] Therefore, in order to transmit the information of the substrate and equipment from the sheet part to the SOI part and crystallize 5OIi, it is necessary to
Both parts of the I part must be melted at the same time, and the SOI film must be crystallized on the SOI part under conditions where there is no scattering of the semiconductor thin film, which poses the problem that the optimal melting range is limited. be. Furthermore, the cooling rate at the time of assimilation differs between the sheet part and the SOI part due to the difference in thermal mass coefficient, as in the case of two series, and when an oxide film or nitride film is used as an insulator, For cooling, SOI
The solidification rate is fast near the sheet, and the further away from the sheet, the slower the solidification rate. Therefore, when crystals are grown completely in one direction from the sheet portion, the solidification rate changes depending on the distance from the bead portion, which is not desirable from the point of view of crystal growth.

An object of the present invention is to solve all of the conventional problems, relax the growth conditions for growing SOIO crystals, and provide a method for easily growing SOIO crystals.

[Means to solve all problems]

The present invention provides an SOIO material having a sheet, in which the insulator forming the SO structure is formed into a structure in which a fully oxygen-doped polysilicon film is sandwiched between oxide films, and the thermal conductivity of the insulator is This is a sor crystal growth method characterized by making the thermal conductivity as close as possible to that of the sheet portion.

[Principle/effect]

The SOIO material insulator is doped with semi-insulating oxygen (approximately 30
%), the range of growth conditions during SOI crystal growth can be relaxed by making the thermal conductivity of the sheet portion and the insulator close to each other.

However, the oxygen-doped polysilicon film has insufficient electrical characteristics at the interface, and in order to completely improve the interface characteristics, a structure is used in which the oxygen-doped polysilicon film is sandwiched between oxide films.

〔Example〕

Hereinafter, the present invention will be described in detail based on this embodiment and with reference to the drawings. FIG. 1 shows a cross-sectional view of the sample used in this example. St (100) 1 Oxide film 2- on substrate
After forming by thermal oxidation to a thickness of <500×, Si
By a vapor phase growth reaction of H4 gas and N20 gas, polysilicon i 3 having an oxygen concentration of 30 to 36 cm was formed to a thickness of 0.9 μm. After patterning, the polysilicon film 3 was oxidized in an oxygen atmosphere to form an oxide film 4 <500X.

Next, single-crystal silicon was grown as the sheet portion 8 by selective epitaxial growth to reduce the level difference between the sheet portion 8 and the insulating film of the SOI structure portion.

Next, a 0.5 μm thick oxide film 6 and a 1.0 μm thick nitride film 7 are formed on the polysilicon film 5 using the CVD method.
After adhesion, the film was finally heat treated at 1000° for 20 minutes in nitrogen gas. SOIO crystal was grown on such a sample using linear electrons and a one-mole annealing device.

The annealing condition for the linear electron beam is an accelerating voltage of 15 kV.

Beam current 80-90ml, scanning speed 70-90crn
/ degree, and the substrate temperature was 600°C. Further, the size of the linear beam was about 4 pots long and about 0.3 nm wide.

When annealing was performed under these conditions, the sheet portion 8
The melting conditions for the polysilicon 5 in the SO tank structure region were almost the same, and there was little difference in the minimum incident power for starting melting. Note that when only an oxide film is used as an insulator, the difference in the minimum incident power for melting the polysilicon film between the sheet part and the SOI structure part is approximately 2.
It was 0%.

〔Effect of the invention〕

According to the method of the present invention, when the SOIO crystal is melted and grown, the melting conditions of the polysilicon layer in the sheet portion and the SOI structure portion become close, and the conditions for SOIO crystal growth are relaxed.
Also, the change in the solidification rate of melted polysilicon near the sheet part is also reduced, making it easier to grow SOIO crystals. It is something that you have.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view of the SOIO fabricated sample used in this example. tI:'・・Seat part.

Claims (1)

[Claims] (1) In an SOI sample having a sheet, the insulator forming the SOI structure is formed into a structure in which an oxygen-doped polysilicon film is sandwiched between oxide films, and the thermal conductivity of the insulator is An SOI crystal growth method characterized by making the thermal conductivity as close as possible to that of .