Method of crystallizing semiconductor film and method of manufacturing display device

• US 20060009017A1
• Filed: 06/17/2005
• Published: 01/12/2006
• Est. Priority Date: 07/08/2004
• Status: Abandoned Application

• Current Assignee: Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Yamamoto, Shuhei, Masuda, Atsushi, Matsumura, Hideki, Suginoya, Mitsuru, Sembommatsu, Shigeru
• Application Number:
  US11/155,959
• Publication Number:
  US 20060009017A1
• Time in Patent Office: Days
• US Class Current: 438/488
• CPC Class Codes: C30B 13/24 using electromagnetic waves
• CPC Class Codes: C30B 29/06 Silicon
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02686 Pulsed laser beam

Abstract

Conventional methods of crystallizing a semiconductor film through scanning with a pulse laser have had a problem in that variation in particle diameter or shape of a crystal grain causes variation in characteristics of a thin film transistor, which lowers display quality of a liquid crystal display. In view of this, in a method of crystallizing a semiconductor film according to the present invention, after a step of performing scanning with a first pulse laser, scanning with a second pulse laser, which has a higher energy density than that of the first pulse laser, is performed in a substantially orthogonal direction to a traveling direction of scanning with the first pulse laser. With this method, the semiconductor film can be crystallized uniformly.

Claims

1. A method of crystallizing a semiconductor film in which a semiconductor film is formed into a polycrystalline semiconductor film through scanning with pulse lasers, comprising the steps of:

scanning a semiconductor film with a first pulse laser; and

scanning the semiconductor film with a second pulse laser in a substantially orthogonal direction to a scanning direction of the first pulse laser, wherein an energy density of the first pulse laser is lower than an energy density of the second pulse laser.

2. A method of crystallizing a semiconductor film according to claim 1, wherein the first pulse laser has an energy density that does not completely melt the semiconductor film.

3. A method of crystallizing a semiconductor film according to claim 1, wherein the semiconductor film is formed by a catalytic CVD method.

4. A method of crystallizing a semiconductor film according to claim 1, wherein, in the first step, dehydrogenization of the semiconductor film is performed through scanning with the first pulse laser.

5. A method of crystallizing a semiconductor film according to claim 1, wherein the semiconductor film is composed of an amorphous silicon thin film with a hydrogen content of 7 Atomic % or less.

6. A method of crystallizing a semiconductor film according to claim 1, wherein:

the second pulse laser provides a line beam having a long side in a perpendicular direction to a scanning traveling direction of the second pulse laser; and

irradiation is performed with an overlap ratio of 70% or more and a pulse energy per time, which ranges from 280 mj/cm² to 380 mj/cm².

7. A method of crystallizing a semiconductor film according to claim 6, wherein:

the first pulse laser provides a line beam having a long side in a perpendicular direction to a scanning traveling direction of the first pulse laser; and

irradiation is performed with an overlap ratio of 70% or more and a difference in energy between the first pulse laser and the second pulse laser is 150 mj/cm² or less.

8. A method of manufacturing a display device, comprising the steps of:

scanning a semiconductor film formed on a first substrate with a first pulse laser;

scanning the semiconductor film with a second pulse laser in a substantially orthogonal direction to a scanning direction of the first pulse laser;

forming a thin film transistor with the use of the semiconductor film; and

forming a display element with the use of the first substrate, wherein an energy density of the first pulse laser is lower than an energy density of the second pulse laser.