JPH04132212A - Manufacture of semiconductor film - Google Patents

Abstract

PURPOSE:To form a good-quality semiconductor film on a glass substrate by a method wherein an amorphous Si film is formed so as to cover a single domain nucleus, a heat treatment is executed within a temperature range which is higher than the melting point of amorphous Si and which is lower than the melting point of crystal Si and the whole amorphous Si film is changed to polycrystalline Si. CONSTITUTION:An excimer laser beam is irradiated from the upper part of a glass substrate 1 to execute a heat treatment. When the glass substrate 1 is cooled and a liquid phase is changed to a solid phase, single-domain nuclei 2b composed of single crystals are formed. An amorphous Si film 3 is formed on the glass substrate 1 so as to cover the single-domain nucleui. An excimer laser beam is irradiated from the upper part of the glass substrate 1 to execute a heat treatment. When the heat treatment is executed, the energy density of the laser beam is controlled so as to be within a temperature range which is higher than the melting point of amorphous Si and which is lower than the melting point of crystal Si. A plurality of domains 3a are solid-grown around the individual single-domain nuclei 2b which exist in a solid phase. A large grain 4 having the domains 3a is formed; and the whole amorphous Si film 3 is changed to polycrystalline Si.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to the formation of a polycrystalline Si thin film that will become a semiconductor active layer when manufacturing electronic devices by integrating elements such as thin film transistors on an insulating substrate. It relates to a manufacturing method for.

(Prior art) Conventionally, as a manufacturing method for forming a polycrystalline Si thin film on an insulating substrate, an amorphous Si thin film is deposited on the insulating substrate, and heat treatment such as a furnace annealing method or a laser annealing method is performed. Accordingly, a method is used in which the amorphous Si thin film undergoes spontaneous solid-phase growth centering around nuclei contained in the amorphous Si thin film to become polycrystalline. However, since the above method uses spontaneous solid-phase growth, it is difficult to control the position and number of polycrystalline grains, and it is difficult to form large grains due to the poor crystallinity of the grains. Met.

Therefore, in recent years, heat treatment has been applied to Si thin films separated into multiple parts.
A method has been proposed in which a nucleus is formed by crystallization through an aggregation reaction, and a polycrystal is grown around this nucleus.

In this method, a Si thin film deposited on an insulating substrate is finely patterned into a plurality of separated dot shapes, then heat treated to form crystalline Si nuclei through an agglomeration reaction, and then CVD using individual crystalline Si as nuclei. This method uses vapor phase growth to grow polycrystals around the crystals. This method has the advantage that the number and position of crystalline Si nuclei can be easily controlled and large grains can be formed.

(Problem to be solved by the invention) However, according to the above method, during vapor phase growth,
A high-temperature process is required to varnish the insulating substrate at a high temperature (700 to 1000°C). In large-area devices such as liquid crystal displays, glass substrates that cannot be subjected to high-temperature processes are used as insulating substrates, so the above method has the problem of not being able to form polycrystalline Si thin films on glass substrates. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a semiconductor film that can form a polycrystalline Si thin film consisting of a large grain aggregate on a glass substrate.

(Means for Solving the Problems) In order to solve the problems of the conventional example described above, a method for manufacturing a semiconductor film according to the present invention is characterized by comprising the following steps.

In the first step, a Si thin film deposited on an insulating substrate is finely patterned into a plurality of separated dot shapes, and a single domain composed of crystalline Si is formed by agglomeration reaction caused by heat treatment.

As a second step, amorphous lsi is deposited to cover the single domain core.

As the third step, crystalline Si is heated to a temperature higher than the melting point of amorphous Si.
Heat treatment is performed in a temperature range lower than the melting point of the amorphous Si by solid phase growth centered on the single domain nucleus.
The entire film is made of polycrystalline Si.

(Function) According to the method of the present invention, the melting points of amorphous Si and crystalline Si are different, and an amorphous Si film deposited to cover a single domain nucleus is The heat treatment is performed in a temperature range higher than the melting point of crystalline Si and lower than the melting point of crystalline Si. Through this process, when the Si, which has temporarily become a liquid phase, becomes the same phase, it grows in a solid phase centered on the single domain nucleus that remains in the solid phase, and the entire amorphous Si film is grown into large grains. It is also possible to use polycrystalline Si having the following properties.

(Example) An example of the method for manufacturing a semiconductor film of the present invention will be described with reference to FIGS. 1 and 2.

An amorphous Si film 2 is formed on a glass substrate 1 using the LPCVD method.
is deposited to a thickness of 200A (Fig. 1(a)).

Figure 2(a)). Next, the amorphous Si thin film 2 is finely patterned by photolithography into a shape in which a plurality of dot separation parts 2a each having a size of 3×3 μm are lined up in multiple rows at a pitch of 5 μm (Fig. 1(b), Fig. 2(b)). b)).

When heat treatment is performed by irradiating excimer laser light (KrF, wavelength 248 nm, energy density 400 mJ/cm') from above the glass substrate 1, the dot separation portions 2a are dissolved and become a liquid phase. At this time, since the volume of each liquid phase is small, they aggregate due to surface tension, and when the liquid phases are cooled from the glass substrate 1 side, when the liquid phases become the same phase, a single domain nucleus consisting of a single crystal with a diameter of 0.7 μm or less 2b (Fig. 1(C), Fig. 2(C)). The dot separation part 2a before heat treatment is amorphous, but after heat treatment and cooling, since the volume is small, it becomes a single domain nucleus composed of single crystal Si.

Next, an amorphous Si film 3 is deposited to a thickness of 1 on the glass substrate 1 using the LPCVD method so as to cover the single domain nucleus 2b.
00OA film is deposited (Fig. 1(d)).

Figure 2(d)).

Heat treatment is performed by irradiating the glass substrate 1 with excimer laser light (KrF, wavelength 248 nm, energy density 350 mJ/cm') from above. This heat treatment lowers the melting point of crystalline Si (168' K) higher than the melting point of amorphous S1 (1350' K).
3@K) Control the energy density of the laser beam so that it is in a lower temperature range. Through this process, only the amorphous Si film 3 is melted without melting the single domain core 2b, and - when the Si, which has temporarily become a liquid phase, is cooled from the glass substrate 1 side and becomes a solid phase, A plurality of domains 3a grow in a solid phase around a six single domain core 2b that remains in a solid phase. And 2~ having multiple domains 3a
By forming large grains 4 of 4 μm, polycrystalline Si can be formed over the entire amorphous Si film 3 (FIGS. 1(e) and 2(e)).

The laser light used in the heat treatment of the semiconductor film manufacturing method described above reaches only the deposited amorphous Si film portion, so even if the amorphous Si film portion reaches a high temperature, the glass substrate will not cause thermal damage. Therefore, a polycrystalline Si thin film can be formed on the glass substrate 1 without deteriorating the glass substrate 1. Further, instead of the laser annealing method, a flash annealing method in which light from a halogen lamp is focused and irradiated may be used.

(Effects of the Invention) According to the method of the present invention, the melting points of amorphous Si and crystalline Si are different, and an amorphous Si film deposited to cover a single domain nucleus is The heat treatment is performed within a temperature range higher than the melting point of pure Si and lower than the melting point of crystalline Si. Through this process, when Si, which temporarily becomes a liquid phase, becomes a solid phase, it grows in a solid phase centering on the single domain nucleus that remains in the same phase, so it can attach to a glass substrate that cannot be subjected to high-temperature processes. The entire amorphous Si film is
It can be polycrystalline Si with large grains. Therefore, a high quality semiconductor film can be manufactured on a glass substrate.

[Brief explanation of the drawing]

Fig. 1 Ca) to (e) are cross-sectional explanatory diagrams of the manufacturing process of a semiconductor film according to an embodiment of the method of the present invention, and Fig. 2 (a) to (e)
FIG. 2 is a plan view illustrating a semiconductor film manufacturing process according to an embodiment of the method of the present invention. l...Glass substrate 2...Amorphous Si film 2a...Dot separation section 2b-Single domain nucleus 3...Amorphous Si film 3a... ...Domain 4...Grain Applicant Fuji Xerox Co., Ltd. Representative Patent Attorney Kiyotaka Sakamoto Representative Patent Attorney Nobuhiro Funatsu Figure 1

Claims (1)

[Scope of Claims] A step of finely patterning a Si thin film deposited on an insulating substrate into a plurality of separated dot shapes, and forming a single domain nucleus made of crystalline Si through an agglomeration reaction by heat treatment; Amorphous Si covers single domain core
and heat treatment at a temperature higher than the melting point of amorphous Si and lower than the melting point of crystalline Si, and the entire film of amorphous Si is grown by solid phase growth centered on the single domain nucleus. Polycrystalline S
A method for manufacturing a semiconductor film, comprising a step of i.