Thin film transistor, display device, and method for manufacturing the same

A technology for thin film transistors and a manufacturing method, which is applied in the manufacture of transistors, semiconductor/solid-state devices, and electric solid-state devices, etc., can solve the problems of complicated manufacturing processes, poor electrical properties of thin-film transistors, and reduced yield, and achieve superior electrical properties. Effect

CN101452961AInactive Publication Date: 2009-06-10SEMICON ENERGY LAB CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2009-06-10
Estimated Expiration
Not applicable · inactive patent

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Abstract

A thin film transistor having excellent electric characteristics, a display device including the thin film transistor, and a manufacturing method thereof are provided. In a thin film transistor in which a microcrystalline germanium film, a gate insulating film in contact with one surface of the microcrystalline germanium film, and a gate electrode overlap with one another and a display device including the thin film transistor, a buffer layer is formed over the other surface of the microcrystalline germanium film. By using a microcrystalline germanium film for a channel formation region, a thin film transistor with high field-effect mobility and high on-current can be manufactured, and by providing a buffer layer between the microcrystalline germanium film functioning as a channel formation region and a source and drain regions, a thin film transistor with low off-current can be manufactured, that is, a thin film transistor with excellent electric characteristics can be manufactured.
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Description

technical field

[0001] The present invention relates to a thin film transistor, a display device using at least the thin film transistor for a pixel portion, and a method for producing these. Background technique

[0002] In recent years, a technique of constructing a thin film transistor by using a semiconductor thin film (thickness of about several tens of nm to several hundreds of nm) formed on a substrate having an insulating surface has attracted attention. Thin film transistors are widely used in electronic devices such as ICs or electro-optical devices, especially as switching elements of image display devices, and research and development are being actively conducted.

[0003] As the switching element of the image display device, a thin film transistor using an amorphous semiconductor film, a thin film transistor using a polycrystalline semiconductor film having a crystal grain size of 100 nm or more, and the like are used. As a method of forming a polycrystalline s...

Examples

Embodiment approach 1

[0059] exist figure 1 In the thin film transistor shown, a gate electrode 51 is formed on a substrate 50, gate insulating films 52a and 52b are formed on the gate electrode 51, a microcrystalline germanium film 61 is formed on the gate insulating film 52b, and on the microcrystalline germanium film 61, a buffer layer 73 is formed, a pair of semiconductor films 72 added with an impurity element imparting one conductivity type are formed on the buffer layer 73, and wiring is formed on the pair of semiconductor films 72 added with an impurity element imparting one conductivity type. 71a to 71c. The microcrystalline germanium film 61 formed on the gate insulating film 52b functions as a channel formation region of the thin film transistor, and the buffer layer 73 functions as a high resistance region.

[0060] As the substrate 50, an alkali-free glass substrate such as barium borosilicate glass, aluminoborosilicate glass, aluminosilicate glass, etc., or a ceramic substrate manufa...

Embodiment approach 2

[0079] In this embodiment, refer to figure 2 A thin film transistor having a microcrystalline germanium film having a higher mobility than that of the first embodiment is shown.

[0080] exist figure 2 In the thin film transistor shown, a gate electrode 51 is formed on a substrate 50, gate insulating films 52a and 52b are formed on the gate electrode 51, and crystallites containing an impurity element serving as a donor are formed on the gate insulating film 52b. In the germanium film 64, a buffer layer 73 is formed on the microcrystalline germanium film 64 containing an impurity element serving as a donor, and a pair of semiconductor films 72 to which an impurity element imparting one conductivity type is added is formed on the buffer layer 73. Wirings 71a to 71c are formed on a pair of semiconductor films 72 having an impurity element imparting one conductivity type. Further, the microcrystalline germanium film 64 formed on the gate insulating film 52b serves as a channe...

Embodiment approach 3

[0086] In this embodiment, refer to image 3 A thin film transistor having a microcrystalline germanium film, which has a higher field effect mobility and an improved yield compared to the first embodiment, is shown.

[0087] exist image 3 In the thin film transistor shown, a gate electrode 51 is formed on a substrate 50, a gate insulating film 52a is formed on the gate electrode 51, and a gate insulating film 41 whose surface is uneven is formed on the gate insulating film 52a. A microcrystalline germanium film 67 is formed on the gate insulating film 41, a buffer layer 73 is formed on the microcrystalline germanium film 67, and a pair of semiconductor films 72 to which an impurity element imparting one conductivity type is added is formed on the buffer layer 73. Wirings 71a to 71c are formed on a pair of semiconductor films 72 having an impurity element imparting one conductivity type. Further, the microcrystalline germanium film 67 formed on the gate insulating film 41 s...