Laser irradiation method and laser irradiation system

Patent metadata

Field	Value
Publication number	US-2020266105-A1
Application number	US-202016855427-A
Country	US
Kind code	A1
Filing date	Apr 22, 2020
Priority date	Dec 21, 2017
Publication date	Aug 20, 2020
Grant date	—

Abstract

A laser irradiation method of irradiating, with a pulse laser beam, an irradiation object in which an impurity source film is formed on a semiconductor substrate includes: reading fluence per pulse of the pulse laser beam with which a rectangular irradiation region set on the irradiation object is irradiated and the number of irradiation pulses the irradiation region is irradiated, the fluence being equal to or larger than a threshold at or beyond which ablation potentially occurs to the impurity source film when the irradiation object is irradiated with pulses of the pulse laser beam in the irradiation pulse number and smaller than a threshold at or beyond which damage potentially occurs to the surface of the semiconductor substrate; calculating a scanning speed Vdx; and moving the irradiation object at the scanning speed Vdx relative to the irradiation region while irradiating the irradiation region with the pulse laser beam at the repetition frequency f.

First claim

What is claimed is:

1 . A laser irradiation method of irradiating an irradiation object in which an impurity source film containing at least an impurity element as a dopant is formed on a semiconductor substrate with a pulse laser beam having photon energy larger than the bandgap energy of the semiconductor substrate, the laser irradiation method comprising:
reading, as a first irradiation condition for laser doping, first fluence that is fluence per pulse of a pulse laser beam with which an irradiation region having a rectangular shape and set on the irradiation object is irradiated and a first irradiation pulse number that is the number of irradiation pulses the irradiation region is irradiated, the number being equal to or larger than two, the first fluence being equal to or larger than a threshold at or beyond which ablation potentially occurs to the impurity source film when the irradiation object is irradiated with the pulse laser beam in the same number of pulses as the first irradiation pulse number and smaller than a threshold at or beyond which damage potentially occurs to a surface of the semiconductor substrate; calculating a first scanning speed Vdx based on Expression (a) below when Bx represents a width of the irradiation region in a scanning direction, Nd represents the first irradiation pulse number, and f represents a repetition frequency of the pulse laser beam; and moving the irradiation object at the first scanning speed Vdx relative to the irradiation region while irradiating the irradiation region with the pulse laser beam at the repetition frequency f.
Vdx=f·Bx/Nd   (a)

2 . The laser irradiation method according to claim 1 , wherein By satisfies Expression (b) below when By represents a width of the irradiation region in a direction orthogonal to the scanning direction
By=n·Cy   (b)
where n represents an integer equal to or larger than one, and Cy represents a dicing pitch of the semiconductor substrate in the direction orthogonal to the scanning direction.

3 . The laser irradiation method according to claim 1 , wherein By/Bx satisfies Expression (c) below when By represents a width of the irradiation region in a direction orthogonal to the scanning direction
10 ≤By/Bx≤ 1000  (c)

4 . The laser irradiation method according to claim 1 , wherein the semiconductor substrate is made of SiC, and the pulse laser beam has a central wavelength equal to or shorter than 270 nm.

5 . The laser irradiation method according to claim 4 , wherein the impurity source film is an aluminum metal film, and the first fluence is 1.5 J/cm 2 to 10 J/cm 2 inclusive.

6 . The laser irradiation method according to claim 4 , wherein the impurity source film has a thickness of 50 nm to 450 nm inclusive.

7 . The laser irradiation method according to claim 6 , wherein the first irradiation pulse number is 5 to 40 inclusive.

8 . The laser irradiation method according to claim 4 , wherein the impurity source film is a SiN film, and the first fluence is 1.2 J/cm 2 to 10 J/cm 2 inclusive.

9 . The laser irradiation method according to claim 8 , wherein the impurity source film has a thickness of 20 nm to 300 nm inclusive.

10 . The laser irradiation method according to claim 9 , wherein the first irradiation pulse number is 5 to 40 inclusive.

11 . The laser irradiation method according to claim 1 , further comprising:
reading, as a second irradiation condition for post annealing, second fluence that is fluence per pulse of the pulse laser beam with which the irradiation region is irradiated and a second irradiation pulse number that is the number of irradiation pulses the irradiation region is irradiated, the number being equal to or larger than two, the second fluence being equal to or larger than a fluence threshold at or beyond which defects in the semiconductor substrate are potentially repaired when the irradiation object is irradiated with the pulse laser beam in the same number of pulses as the second irradiation pulse number and smaller than a threshold at or beyond which damage occurs to the surface of the semiconductor substrate; calculating a second scanning speed Vpx based on Expression (d) below when Np represents the second irradiation pulse number; and moving the irradiation object at the second scanning speed Vpx relative to the irradiation region while irradiating the irradiation region with the pulse laser beam at the repetition frequency f
Vpx=f·Bx/Np   (d)

12 . The laser irradiation method according to claim 11 , wherein the first irradiation pulse number Nd and the second irradiation pulse number Np satisfy a relation of Nd<Np.

13 . The laser irradiation method according to claim 11 , wherein the scanning direction at laser doping and the scanning direction at post annealing are identical to each other.

14 . The laser irradiation method according to claim 11 , wherein the scanning direction at laser doping and the scanning direction at post annealing are opposite to each other.

15 . A laser irradiation system comprising:
a stage configured to move, in at least one scanning direction, an irradiation object in which an impurity source film containing at least an impurity element as a dopant is formed on a semiconductor substrate; a laser apparatus configured to generate a pulse laser beam having photon energy larger than the bandgap energy of the semiconductor substrate; an optical system through which the pulse laser beam is shaped to have a rectangular beam shape and incident on an irradiation region having a rectangular shape and set on the irradiation object; and a laser irradiation control unit configured to control the stage and the laser apparatus and perform processing of; reading, as a first irradiation condition for laser doping, first fluence that is fluence per pulse of the pulse laser beam with which the irradiation region is irradiated and a first irradiation pulse number that is the number of irradiation pulses the irradiation region is irradiated, the number being equal to or larger than two, the first fluence being equal to or larger than a threshold at or beyond which ablation occurs to the impurity source film when the irradiation object is irradiated with the pulse laser beam in the same number of pulses as the first irradiation pulse number and smaller than a threshold at or beyond which damage occurs to a surface of the semiconductor substrate; calculating a first scanning speed Vdx based on Expression (e) below when Bx represents a width of the irradiation region in a scanning direction, Nd represents the first irradiation pulse number, and f represents a repetition frequency of the pulse laser beam; and moving the irradiation object at the first scanning speed Vdx relative to the irradiation region while irradiating the irradiation region with the pulse laser beam at the repetition frequency f.
Vdx=f·Bx/Nd   (e)

16 . The laser irradiation system according to claim 15 , wherein the laser irradiation control unit further performs processing of:
reading, as a second irradiation condition for post annealing, second fluence that is fluence per pulse of the pulse laser beam with which the irradiation region is irradiated and a second irradiation pulse number that is the number of irradiation pulses the irradiation region is irradiated, the number being equal to or larger than two, the second fluence being equal to or larger than a fluence threshold at or beyond which defects in the semiconductor substrate are repaired when the irradiation object is irradiated with the pulse laser beam in the same numbe

Assignees

• Gigaphoton Inc
• Univ Kyushu Nat Univ Corp

Inventors

• Ikenoue Hiroshi
• Wakabayashi Osamu
• Oizumi Hiroaki
• Suwa Akira

Classifications

• H10P72/0436

  mainly by radiation · CPC title

• H10P72/0428

  Apparatus for mechanical treatment or grinding or cutting · CPC title

• H10P54/00

  Cutting or separating of wafers, substrates or parts of devices · CPC title

• H10P34/42

  with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20) · CPC title

• H10P32/171

  being group IV material · CPC title