JPH02283073A - Semiconductor device and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an MO8 type transistor having a channel layer made of amorphous Si.

[Prior art] In recent years, MO8 type TFTs (Th
The device is
They are now being mass-produced as display devices using liquid crystals and one-dimensional image sensor devices. However, in the display devices mentioned above, in order to cope with larger display sizes and higher definition, and also in -dimensional image sensor devices, in order to cope with higher density, the electrical characteristics of TPT elements have to be improved. is required.

Means for improving the electrical characteristics of a TPT element include a low-temperature solid-phase growth technique that increases the grain size of amorphous Si that becomes a channel layer, and a laser annealing technique. It is also a well-known fact that the thinner the channel layer, the better the electrical characteristics of TPT. However, it is known that the thicker the amorphous Si film is to a certain extent, the more large grains will grow during the solid phase growth or laser annealing. Therefore, in the conventional manufacturing of TPT elements, a single layer of amorphous Si film of an appropriate thickness has been used as the channel layer.

[Problems to be solved by the invention] In the conventional TPT structure, the amorphous SL film that becomes the channel layer and source/drain regions is formed in one layer.
The increase in grain size of the amorphous Si film, which is a feature of laser annealing technology and solid phase growth technology, did not sufficiently contribute to improving the electrical characteristics of TPT.

In other words, there is a demand to reduce the thickness of the amorphous Si film that becomes the channel layer in order to improve the electrical characteristics of TPT, and
In order to increase the grain size, there is a problem in that it is not possible to simultaneously satisfy the demand for increasing the thickness of the amorphous Si film to a certain extent.

Therefore, the present invention is intended to solve these problems, and its purpose is to provide a TPT element in which the amorphous Si film serving as the channel layer has large crystal grains even if it is thin, and a method for manufacturing the same. .

[Means for Solving the Problems] In the present invention, the means for solving the problems are as follows: (1) A first amorphous Si film to be a source and a drain, and a channel are formed on an insulating substrate or an insulating film. In a semiconductor device comprising a second amorphous Si film serving as a layer, a gate insulating film, and a gate electrode, the first amorphous Si film has a thickness of 1000 Å or more, and the second amorphous Si film The film is characterized in that the film thickness is 1000 Å or less.

(2) A step of forming a first amorphous Si film that will become a source and a drain on an insulating substrate or an insulating film, and a step of forming a second amorphous S1 film that will become a channel layer over the entire surface of the substrate. Then, a step of laser annealing the entire surface of the substrate, a step of forming the second amorphous Si film in a desired pattern, a step of forming a gate insulating film, and a step of forming a gate electrode. It is characterized by comprising the steps of:

(3) In the laser annealing, the wavelength of the laser is 4
It is characterized by having a diameter of 00 nm or less.

(4) Instead of the laser annealing, 600±50°C
It is characterized by performing heat treatment at a temperature of 3 hours or more.

【Example] The details of the invention will be explained below by way of examples.

1 and 2 show a part of a cross-sectional view of TPT for explaining an embodiment according to the present invention. FIG. 1 is a cross-sectional view of a process of performing laser annealing and solid phase growth at a low temperature. FIG. 2 shows the cross-sectional structure of the TPT element including electrode wiring.

In FIG. 1, 101 is a glass substrate, 102 is a first amorphous Si that becomes the source/drain of TPT, and 10
3 is a second amorphous Si serving as a channel layer. The first amorphous Si is battened corresponding to the source/drain regions, but the second amorphous Si is deposited on the entire surface of the substrate and is in a state before battening. In-phase growth at low temperature and laser annealing are performed under the conditions shown in FIG. The thickness of the first amorphous Si film 5iii is approximately 1000 mm, and the thickness of the second amorphous Si film is 200 to 300 mm. During laser annealing, the energy of the laser annealing is easily absorbed in regions where the amorphous Si film is thick, so the temperature is higher than in other regions where the film thickness is thin, and recrystallization begins earlier. In the region where the film thickness is thin, recrystallization starts slowly,
Under the influence of the early recrystallized region, the crystal grain size of the second amorphous Si film eventually becomes the same as that of the first amorphous Si film.
It is larger than the case where there is no i-film and the second amorphous Si film layer is used.

3 to 5 show a part of the TPT manufacturing process according to the prior art. FIG. 3 shows a state in which amorphous 5iff 302 is deposited on the entire surface of the substrate, and laser annealing and solid phase growth are normally performed in this state. Continuing from FIG. 3, FIG. 4 shows that the amorphous Si film is slammed into regions that are to become sources, drains, and channels (402). FIG. 5 shows that following FIG. 4, a gate insulating film 504 is formed, then a gate electrode 505 is formed, and finally an electrode wiring 507 is formed.
A cross-sectional view of the is shown. The electrical characteristics of TPT are determined by the crystal grain size of the Si channel portion. In the prior art, the channel portion Si is as shown in FIG. 3 302, FIG. 4 402, or FIG. 5 502.
In the present invention, it is 103 in FIG. 1 or 203 in FIG. 2. The crystal grain size of both channel portions Si is related to the difference in the cross-sectional structure of the device when laser annealing or in-phase growth is performed. That is, this is the difference between FIG. 1 and FIG. 3.

Regarding the difference in the crystal grain size of the channel portion Si, the laser annealing has already been described above. In the case of in-phase growth, in the state of the prior art shown in FIG.
Since the thickness of the film 302 is uniform, in-phase growth occurs randomly, but in the case of FIG. 1 according to the present invention, the amorphous Si film 102
Crystal growth starts from the thick region where 102 is present, and crystallization progresses in the channel region where only the amorphous 5ifi 103 exists due to the crystal growth that started at 102 above. Therefore, the final crystal grain size of the channel portion Si is larger in FIG. 1 or FIG. 2 according to the present invention than in FIGS. 3 to 5 according to the prior art.

[Effect of the invention] According to the present invention, about 200 to 300 thin amorphous S
Even in the case of an i-film, a larger grain size can be obtained using laser annealing technology or solid phase growth technology, and therefore a TPT element with excellent electrical characteristics can be manufactured.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of the TPT according to the present invention. 3 to 5 are cross-sectional views of TPT according to the prior art. 101.201.301.401 , 501 ・ ・
・Glass substrate 102.202.302.402.502...Amorphous 5
i 103.203...Amorphous 5i 204.504...Gate insulating film and above Applicant Seiko Epson Corporation Attorney Kizobu Tsuchi Suzuki (and 1 other person)

Claims (4)

[Claims] (1) A semiconductor consisting of a first amorphous Si film to serve as a source and a drain, a second amorphous Si film to serve as a channel layer, a gate insulating film, and a gate electrode on an insulating substrate or insulating film. A semiconductor device, wherein the first amorphous Si film has a thickness of 1000 Å or more, and the second amorphous Si film has a thickness of 1000 Å or less. (2) A step of forming a first amorphous Si film to become a source and a drain on an insulating substrate or an insulating film, and a step of forming a second amorphous Si film to become a channel layer over the entire surface of the substrate. Next, a step of laser annealing the entire surface of the substrate, a step of forming the second amorphous Si film in a desired pattern, a step of forming a gate insulating film, and a step of forming a gate electrode. A method for manufacturing a semiconductor device, comprising the steps of: (3) In the laser annealing, the wavelength of the laser is 4
3. The method of manufacturing a semiconductor device according to claim 2, wherein the thickness is 00 nm or less. (4) Instead of the laser annealing, 600±50°C
3. The method of manufacturing a semiconductor device according to claim 2, wherein the heat treatment is performed at a temperature of 3 hours or more.