JPH02170543A - Manufacture of thin film transistor - Google Patents

Abstract

PURPOSE:To contrive the simplification of the process for manufacturing a thin film transistor by a method wherein a laser beam is applied and the impurity in silicon oxide layers is diffused and activated in second and first semiconductor layers on source and drain regions. CONSTITUTION:Impurity-containing silicon oxide layers 6 are respectively left insularly on source and drain regions 4 and 5, a laser beam 7 is applied to melt first and second semiconductor layers 2 and 3 and the impurity in the layers 6 is diffused and activated in the layers 2 and 3 on the regions 4 and 5. Moreover, at the same time, the layer 3 on a channel region 1a is melted by the irradiation of this laser beam 7 and the region 1a is recrystallized, whereby a recrystallized semiconductor film having a large crystal particle diameter is obtained. Moreover, a low-resistance ohmic contact layer 8 and a recrystallized semiconductor film 16 on the recrystallized channel region 1a are constituted. Thereby, the irradiation of the energy beam is reduced to one time only and the manufacture of a thin film transistor is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a thin film transistor on an insulating substrate.

[Prior Art] As a conventional technique, there is one described in Japanese Patent Application Laid-Open No. 136623/1983. As shown in FIG. 2 (C+, , ), after a first semiconductor film 14 is formed on an insulating substrate 13, an energy beam 15 is irradiated to recrystallize the first semiconductor film 14, and a recrystallized semiconductor film 16 is formed. Then, as shown in FIG. 2(b), the second semiconductor film 17 and the insulating film 18 with low resistance are left on the source and drain electrodes, and the energy beam is irradiated again to activate the second semiconductor film 17 and make it low resistance. do. Next, as shown in FIG. 2(C), a gate insulating film 9 is deposited, and after depositing a low resistance third semiconductor film 19, a gate electrode 10. This was a method for manufacturing a thin film transistor in which a source electrode 11 and a drain electrode 12 are formed.

[Problems to be Solved by the Invention] However, the conventional thin plate transistor manufacturing method has the following problems:
In order to uniformly recrystallize the first semiconductor film 14 that will become the channel region and form the recrystallized semiconductor film 16, the energy beam 15 is irradiated once, and then the second semiconductor film 1 having a low resistance is further irradiated with the energy beam 15.
It was necessary to irradiate the energy beam 15 again to activate the film 7 and make it a film with lower resistance. Furthermore, the first semiconductor film 14 that will become the channel region and the low-resistance second semiconductor film 17 that will become the ohmic contact layer have different film-forming conditions.
Therefore, in order to solve these conventional problems, the present invention involves recrystallization of the semiconductor layer in the channel region and formation of a low-resistance ohmic contact layer. A method for manufacturing a thin film transistor that simplifies the manufacturing method by requiring only one energy beam irradiation for configuration and using the same film-forming conditions for the semiconductor layer in the channel region, the semiconductor layer in the source region, and the semiconductor layer in the drain region. The purpose is to provide

[Means for Solving the Problems] In order to solve the above problems, the method for manufacturing a thin film transistor of the present invention includes depositing a first semiconductor layer on an insulating substrate, and depositing a first semiconductor layer on a source region and a drain region using an IJ method. a step of leaving the first semiconductor layer in an island shape; a step of depositing a second semiconductor layer and leaving it in an island shape on the first semiconductor layer in the source region and the drain region and in the channel region by photolithography; A step of leaving silicon oxide containing impurities in the form of islands in the source region and drain region where the first semiconductor layer and the second semiconductor layer are laminated by photolithography, and irradiating the source region and the drain region with a laser beam. Diffusing and activating the impurity in the silicon oxide into the second semiconductor and first semiconductor layer to form an ohmic contact layer;
recrystallizing the second semiconductor layer in the channel region;
The process of depositing a gate insulating film and configuring a gate electrode,
The method is characterized by a process of forming contact holes in the source and drain regions to fabricate the source and drain electrodes.

[Examples] Examples of the present invention will be described below based on the drawings. In FIG. 1(α), the first semiconductor layer 2 formed on the insulating substrate 1 is left in the form of islands in the source region 4 and drain region 5 by photolithography. Next, as shown in FIG. 1(b), the second semiconductor layer 3 is stacked and left in the form of an island. The first semiconductor layer 2 and the second semiconductor layer 6 may be formed under different film formation conditions (or, films having the same film quality may be formed under the same film formation conditions. 1 CC), silicon oxide 6 containing impurities is left in an island shape on the source region 4 and drain region 5, and the first semiconductor layer 2 and the second semiconductor layer 6 are irradiated with a laser beam 7. It is melted, and the impurities in the silicon oxide 6 are diffused into the first semiconductor layer 2 and the second semiconductor layer 5 on the source region 4 and drain region 5, and activated. At the same time, the second semiconductor layer 6 on the channel region 6 is melted and recrystallized by the irradiation with the laser beam 7, thereby making it possible to obtain a recrystallized semiconductor film having a large crystal grain size. As a result, after removing the silicon oxide 6, as shown in FIG. 1(d), the silicon oxide 6 removed in the previous step is
A low-resistance ohmic contact layer 8 made of more diffused impurities and a recrystallized semiconductor film 16 on the recrystallized channel region 6 are constructed. A gate insulating film 9 is formed on the ohmic contact layer 8 and the recrystallized semiconductor film 16. next,
As shown in FIG. 1 (It), a gate electrode 10 is formed, a contact hole is formed in the gate insulating film 9 by photolithography, and a source electrode 11 and a drain electric fence 12 are formed so as to fill the contact hole to form a thin film transistor. is completed.

[Effect of invention, co.

As explained above, the method for manufacturing a thin film transistor of the present invention includes recrystallizing the semiconductor layer in the channel region of the N-film transistor and forming a low-resistance ohmic contact layer containing impurities using a single laser beam. This can be achieved by irradiation with irradiation, which simplifies the process and also improves the performance of thin film transistors by recrystallizing the semiconductor layer. In addition, the structure of the low-resistance ohmic contact layer
Since this is possible through diffusion and activation by a beam, it is also possible to configure the semiconductor layers of the channel region, source region, and drain region as films having the same physical properties under the same film formation conditions, simplifying the manufacturing method. This has the effect that it is easy to use.

[Brief explanation of the drawing]

FIGS. 1(α) to 1(1) are cross-sectional views for explaining the process order of an embodiment of the method for manufacturing a thin film transistor of the present invention. FIGS. 2(α) to 2(c) are cross-sectional views 1 for explaining the process order of a conventional thin film transistor manufacturing method.
...Insulating base 2...First semiconductor layer 5...Second semiconductor layer 4...Source region 5... ......Drain region 6...Silicon oxide 7...Laser beam 8...Ohmic contact layer 9...・・・
...Gate insulating film 0...Gate electrode 1...Source electrode 2...Drain electrode 6... ...Insulating substrate 4...First semiconductor film 5...Energy beam 6...
. . . Recrystallized semiconductor film 7 . . . Second semiconductor film 8 . . . Insulating film 19 . . . Third semiconductor film or higher

Claims (1)

[Claims] (1) A step of depositing a first semiconductor layer on an insulating substrate and leaving the first semiconductor layer in an island shape in the source region and drain region by photolithography, and depositing a second semiconductor layer and leaving the first semiconductor layer in the source region and drain region. a step of leaving an island shape on the first semiconductor layer in the region and the channel region by photolithography;
A step of leaving silicon oxide containing impurities in the form of islands in the source region and drain region where the first semiconductor layer and the second semiconductor layer are laminated by photolithography, and irradiating the source region and the drain region with a laser beam. Diffusing and activating the impurity in the silicon oxide into the second semiconductor layer and the first semiconductor layer to form an ohmic contact layer, recrystallizing the second semiconductor layer in the channel region, and forming a gate insulating film. 1. A method for manufacturing a thin film transistor, comprising a step of depositing a gate electrode, and a step of forming a source electrode and a drain electrode by forming a gate electrode and forming contact holes in a source region and a drain region.