Surface Temperature Rise Induced by a Focused Laser Beam. Application to Laser-Induced Chemical Vapor Deposition
- PDF / 344,113 Bytes
- 7 Pages / 420.48 x 639 pts Page_size
- 104 Downloads / 224 Views
SURFACE TEMPERATURE RISE INDUCED BY A FOCUSED LASER BEAM. APPLICATION TO LASER-INDUCED CHEMICAL VAPOR DEPOSITION
TOIVO T. KODAS, THOMAS H. BAUM and PAUL B. COMITA IBM Almaden Research Center 650 Harry Road San Jose, CA 95120
ABSTRACT Surface temperatures of a laser-heated structure consisting of intersecting gold and nickel lines on an Si substrate with an Si02 surface layer were determined experimentally and theoretically. Temperatures were measured with micron-sized thin-film thermocouples formed from intersecting gold and nickel lines. Temperature profiles were calculated using a finite difference method which took into account the optical and physical properties of the thermocouple metal lines, the silicon dioxide layer and the silicon substrate. For a 0.2 am Si02 layer, maximum surface temperatures were much higher with the metal lines than without because of the lower reflectivity of the gold relative to the silicon and the limited ability of the thin metal lines to conduct heat away from the irradiated region. Calculated maximum temperatures on the metal lines depended strongly on the thicknesses of the insulating S102 layer and the metal lines. Application of these results to the dynamics of laser-induced chemical vapor deposition is discussed.
INTRODUCTION Many methods now exist for the theoretical estimation of surface temperature distributions induced by a finely focused laser beam. For continuous wave lasers, surface temperature profiles can be calculated analytically for semi-infinite homogeneous substrates and multilayer substrates. A more complicated situation arises in pyrolytic laser-induced chemical vapor deposition (LC'/D), a process in which molecules are thermally decomposed within a localized laser-heated region on a surface to form metal lines or spots. Pyrolytic LCVD can potentially be used to fabricate integrated circuits by directly writing metal or semiconductor material onto substrates. One of the most common substrates encountered in this application is a semiconductor wfth a dielectric surface layer, typically silicon with a silicon dioxide surface layer. Pyrolytic LCVD has been used to deposit micron-size lines of gold, copper, aluminum, silicon, and tungsten on this type of surface. Little information exists, however, on temperature profiles in laser-heated substrates consisting of Si covered with a layer of Si02, even in the absence of metal lines. This work reports the measurement of surface temperature distributions of laser-heated structures consisting of metal lines on semi-infinite solids
Mat. Res. Soc Symp. Proc. Vol. 75. • 1987 Materials Research Society
58
with dielectric surface layers. The method involves forming thin-film thermocouples from two intersecting micron-sized metal lines. This approach has been used to measure temperature profiles in substrates heated by finely focused electron beams [1] and to determine the time evolution of the temperature In this study, rise during irradiation of solids with pulsed lasers [2,3]. surface temperature profiles were measu
Data Loading...
