Advanced Superthin Polysilicon Film Obtained by Si+ Implantation and Subsequent Annealing

Abstract

The random solid‐phase grain growth behavior of Si+‐implanted very thin silicon films and its related electronic properties have been investigated. Si+‐implanted disordered silicon films showed variable range hopping conduction and high electron spin resonance (ESR) center density of more than 1019/cm3. Two‐dimensional dendritic crystal grains grew with subsequent furnace annealing at 600°C. Nucleation time retarded for the increase of Si+ dose. Maximum grain size of 5 μm was obtained. Moreover, remarkable photoconductivity was seen and films changed to activated type of conduction after polycrystallization. We have fabricated a superthin film transistor using these films and obtained field effect electron mobility more than 100 cm2/V · s. Mobility value depended on grain size, i.e., the Si+ dose that corresponded to the ESR center density in disordered Si+‐implanted films.

Photoconductivity of Si films after blue multi-laser diode annealing for photosensor applications

“…This result indicates that the conduction mechanism was speculated to change from hopping conduction to activated conduction of crystal Si. 26) For the as-deposited Si films deposited by sputtering without hydrogen, the conduction mechanism was considered to be variable-range hopping conduction. After the BLDA, as a result of crystallization, a band gap was clearly formed and the density of defects inside the gap decreased drastically, and the conduction mechanism changes to a rather activated conduction in spite of the non-occurrence of hydrogenation.…”

“…In general, the conductivity for the variable-range hopping conduction of undoped a-Si is higher than that for the activated conduction of undoped poly-Si at room temperature. 26) Figure 2(b) shows the photocurrents of the Si films before and after the BLDA. The I-V characteristics are measured under white light exposure of 100 mW/cm 2 .…”

Amorphous Silicon Film Deposition by Low Temperature Catalytic Chemical Vapor Deposition (<150 °C) and Laser Crystallization for Polycrystalline Silicon Thin-Film Transistor Application

“…The crystallinity of the a-Si films were evaluated by using an optical microscope and UV-reflectance spectroscopy. 12,13) The grain size was measured by using a scanning electron microscopy (SEM) and transmission electron microscope (TEM). Prior to the SEM analysis, the Secco etching was performed to enhance the visibility of the grain boundary.…”

Effective annealing and crystallization of si film for advanced TFT system

“…can be obtained [11]. By performing subsequent high-temperature annealing or thermal oxidation for the films with dendrite grains, the electronic properties were further improved as a result of the decrease in the defects density of the grains, without enlarging the grain size [2].…”

“…Solid phase crystallization (SPC) at around 600˚C heating has been actively studied for the Si films as a lowtemperature process on glass, before the trial of ELA or excimer laser crystallization (ELC) because it allows large grains to be obtained while maintaining the smoothness of the Si surface [1,2]. Subsequently, an LTPS TFT on lowcost glass was applied to an LCD panel via the ELC technique, and it is expected to be developed into a highly functional system-on-glass (SoG) [3].…”