Thin-film silicon: Preparation, properties, and device applications

Abstract

This paper will review the properties of thin silicon films deposited on sapphire (SOS) and magnesium aluminate spinel by the pyrolysis of silane in the temperature range WO-1200'C.Variations of carrier mobility, free-carrier concentration, minority carrier lifetime, crystalline perfection, and surface quality will be discussed as a function of substrate crystal and growth parameters. M O S transistors exhibiting field-effect mobility close to that obtained with bulk silicon have been fabricated and a complementary M O S transistor memory cell bas been constructed with a WRITE-READ delay of 6 ns. The standby power for the cell is typically 10 p W . Other C M O S circuits display a pair-delay of 1.5-2.0 no. All-epitaxial bipolar transistors with a current gain of 5 and f r of 350 M H z have been made in which all layers are sequentially deposited during one hightemperature operation. Recent improvements in bipolar fabrication techniques have lead t o current gains as high as 25 at 1 0 mA. I. INIXODUCTION E PITAXIAL SILICON layers are routinely deposited [l ] on silicon during the manufacture of monolithic integrated circuits. However, the deposition of highquality single-crystal silicon on an insulator is a much more difficult problem and places rigid demands on the insulator. Very few insulators fulfill all the necessary conditions and allow the growth of high-mobility silicon.The selection of sapphire as a film substrate was a natural one because of its mechanical and chemical properties and because a lattice plane could be selected that was a close match to that of silicon. Single-crystal films grown from SiCl, were first announced in 1963, and later described in a letter published in 1964 [2]. Mueller and Robinson described singlecrystal silicon grown from SiH, and the first MOS transistors made from it in 1964 [3].The orientation relationship of the substrate and the silicon films have been studied extensively [4], [5]. Although the lattice match between the silicon film and the sapphire substrate is not good on any sapphire plane, the long range order in the aluminum-oxygen sites in the substrate appears to allow epitaxy to take place. Two of the more frequently studied orientation relationships have been (1 1 1 ) and (100) silicon grown on (0001) and (1i02) sapphire, respectively.Spinel (various ratios of MgO : A1,0,) is closely related to sapphire but has a cubic structure and consequently provides a simpler crystallographic match to silicon. A con-

Comprehensive Raman study of epitaxial silicene-related phases on Ag(111)

“…The fact that the intensity of the L(T)O phonon mode gets higher for deposition at 350 °C demonstrates that the sizes of the crystallites enlarge with increasing deposition temperatures. However, this temperature is still low compared to the growth temperature of crystalline Si, which usually exceeds 1000 °C [ 30 ]. Such a low crystallization temperature is surprising, but it can be explained by metal mediation.…”

The Technology of Microwave Integrated Circuits

“…Epitaxial silicon layers have been grown on sapphire (5,6) and spinel substrates while GaAs has been grown on spinel. Epitaxial silicon layers have been grown on sapphire (5,6) and spinel substrates while GaAs has been grown on spinel.…”

Vacuum Deposited Silicon Devices on Fused Silica Substrates

“…Diborane and phosphene were used as gaseous diffusion sources. The films were subjected to the following steps: (i) oxidation at 1000~ in dry O~ for 3 As in the simple doping experiments, the times and temperatures were less than those usually used since higher diffusion coefficients were expected for the films (16). The oxidation steps were designed to result in less than the normal oxide thickness so that the silicon films would not be consumed in the formation of the various required oxide layers.…”

“…A goal for many years in the field of microelectronics has been the achievement of active devices from vacuum deposited films on amorphous insulating substrates (1). All of the currently successful thin film devices, in contrast, are formed epitaxially onto singlecrystal substrates (2,3). Thin film majority carrier field-effect transistors were produced some time ago from vacuum deposited germanium (4), tellurium (5), and various chalcogenides (6, 7) onto glassy substrates.…”