World Abstracts on Microelectronics and Reliability important, and the payback in improved yield or reduced turnaround time is large.
Microfabrication with ion beams. A. J. MURAY and J. J. MURAY. Vacuum 35(10-11), 467 (1985). This paper covers recent research and development of new technologies-sometimes referred to as "directed (or focused) ion beam techniques (FIB)" or "ion engineering"--where ion beams in vacuum or ions in plasma play the central role. The technologies are characterized by the action of accelerated ions which enhance surface or bulk chemical activities in the target (substrate) material. These include ion-beam lithography, ion-assisted etching and deposition and structure diagnosis with ion beams. The paper also covers the physical and engineering aspects of FIB technologies, including an evaluation of the fabrication techniques used to build threedimensional microstructures and micromechanical devices.
Formation of buried insulating layers by high dose oxygen implantation under controlled temperature conditions. M. BRUEL, J. MARGAIL, J. STOEMENOS, P. MARTIN and C. JAUSSAUD. Vacuum 35(12), 589 (1985). A specially designed sample holder was used to form SOI structures by high dose oxygen implantation under controlled temperature conditions. This system uses a layer of molten tin to provide a good thermal contact between the silicon wafer and a resistively heated support. The layers formed under these conditions were characterized by RBS and XTEM. After annealing at 1150°C for 2h the only remaining defects in the top silicon layer are dislocations with a density of less than l0 Tcm- 2 and SiO 2 precipitates. Annealing at 1185°C for 6h does not change the density of dislocations but leads to the formation of a 200 nm thick silicon layer free of SiO 2 precipitates, suitable for VLSI processing without growing an epitaxial layer.
As2-ambient activation and alloyed-ohmic-contact studies of Si÷-ion-implanted AIg3Ga0.7 As/GaAs modulation-doped structures. S. D. MUKHERJEE, P. ZWICKNAGL, H. LEE, L. RATHBUN and L. F. EASTMAN.Solid-St. Electron. 29(2), 181 (1986). The behavior of Si+-ion-implanted A10.3Ga07As/ GaAs MODFET structures annealed in an As2 environment created by the decomposition of InAs has been studied. Contact studies were made using AuGeNiAg alloyed contacts. The best activation of Si + ions of around 409/0 is achieved for a peak Si concentration of ~ 2 x 10 is Si ions/ cm 3 situated close to the A1GaAs/GaAs interface for annealing temperatures above 9000C. the optimum implantation parameters for a MODFET structure having an A1GaAs layer of thickness ~500-600A are: 80keV 5 x 1013Si+ ions/cm2 with 915°C 15min annealing, yielding sheet resistances ~< 200ohms/Tq, corresponding to an activation of ~ 30~o and a peak Si ion concentration of about 5x1018cm -3. A record specific transfer resistance of 0.05 + 0.03 ohm. mm was achieved for transient alloying of a Ni/AuGe/Ag/Au metallization with a rise time ~ 100 sec to a maximum temperature of ~ 600*C.
Repair of clear photomask defects by laser-pyrolytic deposition. MODESTM. OPRYSKO,MARKW. BERANEK,DALE E. EWBANK and ARTHUR C. TITUS. Semiconductor int., 90 (January 1986). Laser technique deposits metal to repair both clear and opaque defects in photomasks.
The influence of pulse shape on the dynamics of pulsed laser annealing of GaAs. PtOTR EDELMAN and ANDRZEJ M.
KONTKIEWlCZ. Electron Technol., Warsaw 17(3/4), 13 (1984). Based on the thermal model, temperature profiles inside the layer were calculated as well as the melting depth and the time during which the GaAs layer annealed with the ruby laser (2 = 694.3 nm) is molten. The influence of the laser pulse shape on the dynamics of the process was studied.
Determination of threshold power for semiconductor melting during laser annealing. PIOTR EDELMAN and ANDRZEJ M. KONTKIEWICZ.Electron Technol., Warsaw 17 (3/4), 25 (1984). Based on the thermal model of laser annealing, the threshold power for semiconductor melting was calculated as a function of laser pulse length. Temperature profiles inside the layer and temperature changes during heating and cooling were also determined. The results of calculations are presented for the ruby laser (2 = 694.3nm) and gallium aresnide.
The effects of a sacrificial oxide process on metal-oxidesemiconductor field effect transistors fabricated with ionbeam-nitridation technology. HAN-SH~NG LEE. Solid-St. Electron. 29(1), 25 (1986). Direct ion-bean nitridation was used to form a thin nitride layer on the surface of silicon wafers. When this nitride layer was used as a mask in the field oxide-growth step, the lateral encroachment of the resulting field oxide was much smaller than the encroachment produced by using the conventional local-oxidation-ofsilicon method. It is desirable to reduce the lateral encroachment of the oxide, since it is a wasted region in the integratedcircuit layout. However, we found that the transistors fabricated with the ion-beam nitridation step displayed poor device performance, such as degradation of electron field effect mobility, junction leakage current and even the quality of the gate oxide. In this paper we show that the growth and removal of a sacrificial oxide prior to the gate oxide growth can improve the device performance of the transistors fabricated with ion-beam nitridation. The lateral encroachment of the sacrificial-oxide-treated sample is still small. We believe that the consumption of the damaged silicon and the additional thermal annealing associated with the sacrificialoxide treatment are responsible for the improvements in device properties. Early applications of laser direct patterning: direct writing and excimer projection. D. J. EHRLICH. Solid St. Technol., 81 (December 1985). In the last few years there has been vigorous research activity in laser processing for microfabrication. These new techniques are motivated by possibilities ranging from that of developing a 0.25/~m optical lithography to that of developing an entirely nonlithographic laser-direct-writing technology for post-fabrication (final step) processing and circuit prototyping. The former would provide a simpler, faster, and less expensive alternative to xray, electron, or ion-beam lithography for next-generation VLSI. The latter would make available methods for highaccuracy trimming wafer-scale integration, and interactive circuit design.
Electron beam probing of integrated circuits. E. MENZELand R. BUCHANAN. Solid St. Technol., 63 (December 1985). Design verification, function control, and failure analysis of integrated circuits by using an electron beam probe has become a well established technique. The physics of electron beam voltage measurements is outlined. The electron beam prober and examples of IC internal measurements are described.