# US 7,071,035 B2 · Apparatus and method for laser radiation

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- Number: US 7,071,035 B2
- Document ID: US7071035B2
- Status: Granted
- Kind: B2
- Application number: 10/443,267
- Filed: 2003-05-21
- Published: 2003-10-30
- Granted: 2006-07-04
- Earliest claimed: 1996-02-06
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Shunpei Yamazaki; Satoshi Teramoto; Naoto Kusumoto; Koichiro Tanaka
- Web page: https://patentgrep.com/patent/US7071035B2

## CPC

- G02B 19/0057: {in the form of a laser diode array, e.g. laser diode bar (semiconductor laser arrays with beam combining arrangement H01S5/4012)}
- B23K 26/0613: {having a common axis (B23K26/0619 takes precedence)}
- B23K 26/067: Dividing the beam into multiple beams, e.g. multi-focusing
- B23K 26/0738: {into a linear shape}
- G02B 19/0014: {at least one surface having optical power}
- G02B 19/0095: {for use with ultraviolet radiation}
- G02B 27/09: Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for {(adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005)}
- G02B 27/0905: {Dividing and/or superposing multiple light beams}
- G02B 27/0927: {Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat}
- G02B 27/0961: {Lens arrays (lens arrays per se G02B3/0006)}
- G02B 27/0966: {Cylindrical lenses (cylindrical lenses per se G02B3/06)}
- H10D 86/0229: {characterised by control of the annealing or irradiation parameters}
- H10D 86/0251: {characterised by increasing the uniformity of device parameters}
- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10P 14/3806: {using crystallisation-enhancing elements}
- H10P 14/381: {Beam shaping, e.g. using a mask}
- H10P 14/3816: {Pulsed laser beam}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

There is provided an improvement on homogeneity of annealing performed utilizing radiation of a laser beam on a silicon film having a large area. In a configuration wherein a linear laser beam is applied to a surface to be irradiated, optimization is carried out on the width and number of cylindrical lenses forming homogenizers 103 and 104 for controlling the distribution of radiation energy density in the longitudinal direction of the linear beam. For example, the width of the cylindrical lenses forming the homogenizers 103 and 104 is set in the range from 0.1 mm to 5 mm, and the number of the lenses is chosen such that one lens is provided for every 5 mm–15 mm along the length of the linear laser beam in the longitudinal direction thereof. This makes it possible to improve homogeneity of the radiation energy density of the linear laser in the longitudinal direction thereof.

## Claims

### Claim 1

A method for forming a semiconductor device comprising:
forming a semiconductor film comprising silicon to become at least a channel formation region over a substrate;
splitting a linear laser light by cylindrical lenses;
irradiating said linear laser light to said semiconductor film; and
forming a gate electrode adjacent to said semiconductor film with a gate insulating film therebetween,
wherein the number y of said cylindrical lenses and the length x (mm) of said linear laser light on said semiconductor film satisfy a formula: (43/600)x−(1/6)≦y ≦(x/5).

### Claim 2

A method for forming a semiconductor device comprising:
forming a semiconductor film comprising silicon to become at least a channel formation region over a substrate;
splitting a linear laser light by cylindrical lenses; and
irradiating said linear laser light to said semiconductor film,
wherein the number y of said cylindrical lenses and the length x (mm) of said linear laser light on said semiconductor film satisfy a formula: (43/600)x−(1/6)≦y ≦(x/5).

### Claim 3 (depends on 1)

A method according to claim 1 wherein said laser light is selected from the group consisting of a KrF excimer laser light and a XeCI excimer laser light.

### Claim 4 (depends on 1)

A method according to claim 1 further comprising the step of crystallizing said semiconductor film by heat treatment to form the crystallized semiconductor film wherein crystallinity of said crystallized semiconductor film is improved by the irradiation of said linear laser light.

### Claim 5 (depends on 1)

A method according to claim 1 further comprising the step of crystallizing said semiconductor film by heat treatment to form the crystallized semiconductor film wherein said crystallized semiconductor film is annealed by the irradiation of said linear laser light.

### Claim 6 (depends on 2)

A method according to claim 2 wherein said laser light is selected from the group consisting of a KrF excimer laser light and a XeCl excimer laser light.

### Claim 7 (depends on 2)

A method according to claim 2 further comprising the step of crystallizing said semiconductor film by heat treatment to form the crystallized semiconductor film wherein crystallinity of said crystallized semiconductor film is improved by the irradiation of said linear laser light.

### Claim 8 (depends on 2)

A method according to claim 2 further comprising the step of crystallizing said semiconductor film by heat treatment to form the crystallized semiconductor film wherein said crystallized semiconductor film is annealed by the irradiation of said linear laser light.

### Claim 9 (depends on 1)

A method according to claim 1, wherein the linear laser light is split in a longitudinal direction of the irradiated linear laser light.

### Claim 10 (depends on 2)

A method according to claim 2, wherein the linear laser light is split in a longitudinal direction of the irradiated linear laser light.