Furnace and rapid thermal crystallization of amorphous GexSi1−x and Si for thin film transistors

Abstract

The crystallization behavior of polycrystalline silicon (Si) and germanium-silicon alloys (GexSil-x) from Sill4 and GeH4, where x is in the range of 0-0.32, has been investigated for thin film transistor (TFT) applications. Furnace anneals as well as rapid thermal anneal (RTA) and combinations of these two techniques have been used to crystallize amorphously deposited thin ( _< 100 nm) films. The effects of time and temperature for the furnace anneals and time, temperature and pulse rate for the RTA have been investigated. Smooth Si and Ge~Sii_x layers with a surface roughness <0.6 nm have been obtained using an initial Si layer for the Ge;~Si, _x material, since GexSi~_x shows a nucleation problem on oxide surfaces which influences the resulting surface roughness and grain size. For TFT applications the optimaI film properties cannot be obtained with a single crystallization anneal. Conventional furnace crystallization results in smooth layers with Si furnace crystallized films exhibiting small grains with many intra-grain defects. An average grain size of approximately 300 nm for Ge0.~Sio.75 and slightly larger grains for Geo.3aSio.6a with less defects is obtained at lower temperature. RTA results for Si and Ge~Si~ -x in fine grained material with lower defect density. © 1997 Elsevier Science S.A.

Kinetics of Phase Transformation of Indium in the Presence of Polytetrafluoroethylene: Implications for DSC Measurements on Polymers and Their Composites

“…As shown below, the same type of information can be obtained in absence of PTFE only by further processing of DSC data according to Avrami. It is worth observing that the slowdown of crystallization by using a polymer sheet may be an ingenious contrivance to achieve higher perfection of solids for particular applications, since rapid crystallization often leads to many dislocations and defects [25].…”

Rapid thermal oxidation of radio frequency sputtered polycrystalline silicon germanium films

“…The potential of such films is mainly for thin film transistor applications. [1][2][3][4] It is also possible to obtain polycrystalline Si 1Ϫx Ge x films by annealing the rf sputtered films. [5][6][7] Whatever the deposition technique, it has been widely recognized that the use of polycrystalline Si 1Ϫx Ge x films in thin film transistors is severely limited by the lack of suitable insulator gate materials.…”

Deposited inter-polysilicon dielectrics for nonvolatile memories

“…In the last decade deposited dielectric layers have been investigated as a very promising alternative, since these dielectric layers are deposited on the polysilicon layer without silicon surface consumption, contrary to thermal oxidation. low-temperature oxides (LTO) [33] deposited in a rapid thermal processing (RTP) system [34] or in a conventional low pressure chemical vapor deposition (LPCVD) system [35] have resulted in useful layers for thin film transistors [36]. Although post deposition treatments have been applied (see for instance [37]- [45]), the electrical properties are too poor for EEPROM application.…”