Stress generated in polyimide by excimer‐laser irradiation

Stress transients are generated in polyimide by irradiation with excimer‐laser pulses at radiant exposures between 3×10−3 and 102 J/cm2. The duration and peak stress of these transients are measured using piezoelectric film transducers. For all the wavelengths tested (193, 248, 308, 351 nm) we determine three ranges of radiant exposure within which different physical mechanisms govern the stress generation. The scaling of stress with radiant exposure depends on wavelength only in the low fluence regime. In this regime the stresses observed are attributed to subsurface thermal decomposition at 351 and 308 nm and to photodecomposition at 248 and 193 nm. At higher radiant exposure the stress generation is governed either by the thermal expansion of the gaseous ablation products or by the formation and expansion of a dense plasma. The boundary between these two regimes is identified from the variation of the mechanical coupling coefficient with radiant exposure. The results also indicate that heat conduction ...

[1]  Gerald J. Diebold,et al.  Photoacoustic effect in strongly absorbing fluids , 1991 .

[2]  Ronald S. Dingus,et al.  Grüneisen-stress-induced ablation of biological tissue , 1991, Photonics West - Lasers and Applications in Science and Engineering.

[3]  M. Geis,et al.  Self‐developing UV photoresist using excimer laser exposure , 1983 .

[4]  P. Dyer,et al.  Ablative and acoustic response of pulsed UV laser‐irradiated vascular tissue in a liquid environment , 1988 .

[5]  P E Dyer,et al.  Far‐ultraviolet laser ablation of the cornea: Photoacoustic studies , 1987, Lasers in surgery and medicine.

[6]  J. Marshall,et al.  An ultrastructural study of corneal incisions induced by an excimer laser at 193 nm. , 1985, Ophthalmology.

[7]  R. D. Griffin,et al.  Interferometric studies of the pressure of a confined laser‐heated plasma , 1986 .

[8]  R. F. Harrison,et al.  Impulse coupling to targets in vacuum by KrF, HF, and CO2 single‐pulse lasers , 1988 .

[9]  Rangaswamy Srinivasan,et al.  Nanosecond photoacoustic studies on ultraviolet laser ablation of organic polymers , 1986 .

[10]  P. H. Key,et al.  Direct etching of polymeric materials using a XeCl laser , 1983 .

[11]  Raghavan Srinivasan,et al.  Ultraviolet laser ablation of polyimide films , 1987 .

[12]  P. Dyer,et al.  Excimer laser ablation and thermal coupling efficiency to polymer films , 1985 .

[13]  S L Jacques,et al.  Laser‐induced photoacoustic injury of skin: Effect of inertial confinement , 1991, Lasers in surgery and medicine.

[14]  T J Flotte,et al.  Biological effects of laser-induced shock waves: structural and functional cell damage in vitro. , 1993, Ultrasound in medicine & biology.

[15]  A. D. Zweig,et al.  A thermo-mechanical model for laser ablation , 1991 .

[16]  Heinz Schmidt-Kloiber,et al.  Time-resolved investigations of laser-induced shock waves in water by use of polyvinylidenefluoride hydrophones , 1988 .

[17]  C. Otis,et al.  On single‐photon ultraviolet ablation of polymeric materials , 1992 .

[18]  Bodil Braren,et al.  The significance of a fluence threshold for ultraviolet laser ablation and etching of polymers , 1990 .

[19]  Peter E. Dyer,et al.  Transient photoacoustic studies of laser tissue ablation , 1990, Photonics West - Lasers and Applications in Science and Engineering.

[20]  C. Fotakis,et al.  Spectroscopic studies of ArF laser photoablation of PMMA , 1985 .

[21]  F Hillenkamp,et al.  Excimer laser ablation of the cornea and lens. Experimental studies. , 1985, Ophthalmology.

[22]  P. Ballard,et al.  Physical study of laser-produced plasma in confined geometry , 1990 .

[23]  S. J. Thomas,et al.  Momentum Transfer Produced by Focused Laser Giant Pulses , 1966 .

[24]  S. Babu,et al.  Excimer laser induced ablation of polyetheretherketone, polyimide, and polytetrafluoroethylene , 1992 .

[25]  D. J. McCloskey,et al.  Thermoelastic Stress Production in Solids , 1968 .

[26]  R. Srinivasan,et al.  Ablation of polymers and biological tissue by ultraviolet lasers. , 1986, Science.

[27]  J. Brannon,et al.  Excimer laser etching of polyimide , 1985 .

[28]  S. Trokel,et al.  Evolution of excimer laser corneal surgery , 1989, Journal of cataract and refractive surgery.

[29]  Bodil Braren,et al.  Ultrafast imaging of ultraviolet laser ablation and etching of polymethylmethacrylate , 1989 .

[30]  A. D. Zweig,et al.  Shock waves generated by confined XeCl excimer laser ablation of polyimide , 1992 .

[31]  C. Puliafito,et al.  Corneal endothelial injury in rabbits following excimer laser ablation at 193 and 248 nm. , 1986, Archives of ophthalmology.

[32]  S L Jacques,et al.  Putative photoacoustic damage in skin induced by pulsed ArF excimer laser. , 1988, The Journal of investigative dermatology.

[33]  P. Dyer,et al.  Spectroscopic and fast photographic studies of excimer laser polymer ablation , 1988 .

[34]  M. Sigrist Laser generation of acoustic waves in liquids and gases , 1986 .