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of the sample was measured at each wavelength and used to correct the signal due to probe light transmitted through the photoexcited sample. In addition, since the samples in this study did undergo photodecomposition over extended periods of time, repeat measurements were made at regular intervals throughout the data acquisition period and used to calculate a geometric progression correction for sample photodecomposition. The net sample decomposition was kept small (<15%) by switching to fresh solutions as needed, generally after 2 h. Given the low concentrations (<1W M) required to maintain the absorbance below 2.0 and the sensitivity to oxygen, the samples were remarkably robust. 9ArF (Ar = C6H4-m-Me), 140875-94-1; 9ArF (Ar = C6H,-m-C1), 73872-45-4; 9ArF (Ar = C6H4-p-C1), 42730-13-2; 9ArF (Ar = C6H4-m-OMe), 140875-95-2.The supersonic molecular beam technique is used to investigate the dynamics of photochemical gassurface reactions of C12 with polycrystalline A1 surface irradiated by 355-and 1064-nm laser photons. The mass and velocity distributions of desorbed reaction products are measured by time-resolved mass spectrometry. Results show that the main products are Al+ and AlCl, (x = 1, 2, 3) produced with the irradiation at 355 nm; only A1C13 is produced under 1064-nm laser irradiation. The yields of the main products increase with translational energy of incident C12 molecules and with laser fluence. Different fluence thresholds exist for the two laser wavelengths. Thermal desorption of the surface reaction products is proposed for the 1064-nm irradiation, and nonthermal processes exist for the 355-nm irradiation. IntroductionStudies of the laser-enhanced reaction of A1 with C1, have also Lasers can promote localized photochemical gas-surface reactions and are thus being applied to chemical etching of semiconductors and metals. Since aluminum is widely used in microelectronic devices, the chemical etching of the A1 surface is particularly attractive. It has been shown that A1 can be etched successfully in a wet chemical solution with laser irradiation.',2 However, dry chemical etching of A1 surface with C12 assisted by pulsed lasers3s4 seems to offer an important advantage of combining a spontaneous gas-surface reaction with laser-stimulated desorption to remove the reaction products rapidly. Recently, the thermal reaction of the Al<12 system has been in~estigated.~?~ These studies showed that rapid spontaneous reaction took place even at room temperature, while the A1 surface was exposed to the C12 atmospheree6 The reaction probability of C12 with A1 was found to be

Laser-induced chemical reaction of semiconductor with halogen and halogen compounds has attracted much attention in recent years due to its potential application in fabrication of microelectronic devices. We have reported UV and visible laser-induced reactions of Si and GaAs surfaces with chlorine using a CW molecular beam technique coupled with time-resolved mass spectrometry(1,2,). This paper will present recent studies in our laboratory on laser-induced reactions of Ge(111), Si(111), GaAs(100) and lnP(100) surfaces with chlorine molecules under 355-, 560-, and 1064-nm laser irradiations. We are particularly interested in the use of near infrared (1064-nm) laser photons as well as the promotion of reaction by raising the incident chlorine molecules’ translational energy. The objective is to achieve a better understanding of the mechanism of laser-induced reaction and its potential application in the chemical etching of semiconductor.