Poly-Si TFT fabricated by laser-induced in-situ fluorine passivation and laser doping

Abstract

A new poly-Si TFT has been fabricated by employing laser-induced in-situ fluorine passivation and laser-doping method. With only one excimer laser annealing, we have successfully fabricated the device using one step to crystallize, passivate and dope simultaneously. Although any additional plasma post-passivation was not performed, the on-state and the off-state leakage properties of TFTs with fluorine passivation were improved compared with those without fluorine passivation. The device with in-situ fluorine passivation has the maximum transconductance of 13.3 A/V for a C 2 F 6 flow rate of 100 sccm, while the device without fluorine passivation has that of 8.4 A/V. The device reliability under electrical stress was remarkably improved in the in-situ fluorine-passivated devices due to the fluorine passivation effects of trap states in the poly-Si channel and SiO 2 /poly-Si interface.

Interface passivation and trap reduction via hydrogen fluoride for molybdenum disulfide on silicon oxide back-gate transistors

“…There have been previous reports of applying HF passivation to SiO 2 or high-k oxide to form an H-terminated surface [20][21][22][23][24][25]. In this work, with HF-dipping treatment prior to the MoS 2 growth, the introduced H to the interface region would presumably satisfy the SiO 2 dangling bonds and cleave the MoS 2 /SiO 2 interface bonds.…”

Performance Improvement of Low-Temperature Polycrystalline Silicon Thin-Film Transistors with Fluorinated Silicate Glass Drive-In Masking Layer

“…[4][5][6][7][8] Fluorine incorporation has been used to improve the electrical characteristics of LTPS TFTs by eliminating trap states. 5,[9][10][11][12][13][14] Fluorine incorporation can break strained bonds to cause local strain relaxation and reduce the interface states, to form Si-F bonds at the Si/SiO 2 interface. These strong Si-F bonds are stable against hot-carrier stressing than weak Si-H bonds because the bonding energy of the Si-F bond is greater than that of the Si-H bond.…”

Increased Lateral Crystallization Width during Nickel Induced Lateral Crystallization of Amorphous Silicon Using Fluorine Implantation

“…The crystallization of amorphous silicon ͑␣-Si͒ has been intensively investigated for application in active-matrix flat-panel displays and three-dimensional ͑3D͒ electronics. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Solid phase crystallization was originally used to produce polysilicon from amorphous silicon, and can be typically achieved using a 20 h anneal at a temperature around 600°C. 1,2 The disadvantages of solid phase crystallization ͑SPC͒ are a small grain size, typically 0.5-1 m, and a lack of control over grain boundary locations.…”

“…These include excimer laser crystallization ͑ELC͒ 11,12 and nickel induced lateral crystallization ͑NILC͒. 13,14 Fluorination of the film prior to, 15 during ͑in situ͒ 16,17 or after 18 excimer laser annealing ͑ELA͒ has been shown to improve the performance of TFTs due to passivation of grain boundary traps and the formation of strong Si-F bonds in the poly-Si channel and at the SiO 2 /poly-Si interface. 5,[15][16][17] The NILC technique is extremely popular as the catalytic effects of metals like nickel ͑Ni͒ lead to large grain polysilicon with good control over the location of the grains 13,14 at a lower thermal budget.…”