Optical method for the determination of stress in thin films

Details Optical method for the determination of stress in thin films Optical method for the determination of stress in thin films

1997-07-30

1999-01-26

Hellner, Mark

Optics: measuring and testing

Velocity or velocity/height measuring

With light detector

73762, 73800, 356 32, G01P 336, G01B 1116, G01L 124

Patent

active

058643931

ABSTRACT:
A method and optical system is disclosed for measuring an amount of stress in a film layer disposed over a substrate. The method includes steps of: (A) applying a sequence of optical pump pulses to the film layer, individual ones of said optical pump pulses inducing a propagating strain pulse in the film layer, and for each of the optical pump pulses, applying at least one optical probe pulse, the optical probe pulses being applied with different time delays after the application of the corresponding optical probe pulses; (B) detecting variations in an intensity of a reflection of portions of the optical probe pulses, the variations being due at least in part to the propagation of the strain pulse in the film layer; (C) determining, from the detected intensity variations, a sound velocity in the film layer; and (D) calculating, using the determined sound velocity, the amount of stress in the film layer. In one embodiment of this invention the step of detecting measures a period of an oscillation in the intensity of the reflection of portions of the optical probe pulses, while in another embodiment the step of detecting measures a change in intensity of the reflection of portions of the optical probe pulses and determines a time at which the propagating strain pulse reflects from a boundary of the film layer.

REFERENCES:
patent: 4484820 (1984-11-01), Rosencwaig
patent: 4522510 (1985-06-01), Rosencwaig et al.
patent: 4579463 (1986-04-01), Rosencwaig et al.
patent: 4632561 (1986-12-01), Rosencwaig et al.
patent: 4636088 (1987-01-01), Rosencwaig et al.
patent: 4679946 (1987-07-01), Rosencwaig et al.
patent: 4710030 (1987-12-01), Tauc et al.
patent: 4750822 (1988-06-01), Rosencwaig et al.
patent: 4795260 (1989-01-01), Schuur et al.
patent: 4854710 (1989-08-01), Opsal et al.
patent: 4952063 (1990-08-01), Opsal et al.
patent: 4999014 (1991-03-01), Gold et al.
patent: 5042951 (1991-08-01), Gold et al.
patent: 5042952 (1991-08-01), Opsal et al.
patent: 5074669 (1991-12-01), Opsal
patent: 5270781 (1993-12-01), Singh et al.
patent: 5546811 (1996-08-01), Rogers et al.
W. Lee Smith et al. "Ion implant monitoring with thermal wave technology". Appl. Phys.Lett.4. vol. 47.No.6, Sep. 15, 1985. pp. 584-586.
J. Opsal et al. "Thermal and plasma wave depth profiling in silicon". Appl. Phys. Lett. vol. 47 No. 5, Sep. 1, 1985. pp. 498-500.
A. Rosencwaig et al. "Thin-film thickness measurements with thermal waves". Appl. Phys. Lett., vol. 43 No. 2, Jul. 15, 1983. pp. 166-168.
A. Rosencwaig et al. "Detection of thermal waves through optical reflectance". Appl. Phys. Lett., vol. 46 No. 11, Jun. 1, 1985. pp. 1013-1015.
A. Elci et al. "Physics of Ultrafast Phenomena in Solid State Plasmas". Solid-State Electronics, vol. 21, 1978, pp. 151-158.
D.H. Auston et al. "Picosecond Spectroscopy of Semiconductors". Solid-State Electronics, vol. 21, 1978, pp. 147-150.
D. H. Auston et al. "Picosecond Ellipsometry of Transient Electron-Hole Plasmas in Germanium". Physical Review Letters, vol. 32, No. 20. May 20, 1974 pp. 1120-1123.
R.J. Stoner et al. "Kapitza conductance and heat flow between solids at temperatures from 50 to 300K". Physical Review B, vol. 48, No. 22, Dec. 1, 1993 pp. 16 373-16 387.
R.J. Stoner et al. "Measurements of the Kapitza Conductance between Diamond and Several Metals". Physical Review Letters, vol. 68 No. 10, Mar. 9, 1992 pp. 1563-1566.
S. Sumie et al. "A New Method of Photothermal Displacement Measurement by Laser Interferometric Probe". Jpn. J. Appl. Phys. vol. 31 Pt. 1, No. 11, 1992 pp. 3575-3583.
S. Sumie et al. J.Appl. Phys. 76(10), Nov. 15, 1994 pp. 5681-5689.
F.E. Doany et al. "Carrier lifetime versus ion-implantation dose in silicon on sapphire". Appl. Phys. Lett. 50(8), Feb. 23, 1987 pp. 460-462.
D.A. Young et al. "Heat Flow in Glasses on a Picosecond Timescale". Dept. of Engineering, Brown University, Providence, RI. 1986. pp. 49-51.
"Third order nonlinear optical interactions in thin films of poly-p-phenylenebenzobisthiazole polymer investigated by picosecond and subpicosecond degenerate four wave mixing" by D. Narayana Rao, Jacek Swiatkiewicz, Pratibha Chopra, Suniti K. Ghoshal and Paras N. Prasad, Appl. Phys. Lett. vol. 48, No. 18, 5 May 1986.
"Picosecond transient grating studies of polymeric thin films" By D. Narayana Rao, Ryszard Burzynski, Xin Mi, and Paras N. Prasad, Appl. Phys. Lett., vol. 48, No. 6, 10 Feb. 1986.

Affiliated with

Also associated with

Rating

Optical method for the determination of stress in thin films does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Optical method for the determination of stress in thin films, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical method for the determination of stress in thin films will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1454088