Title :
A novel method for a smooth interface at poly-SiOx/SiO2 by employing selective etching
Author :
Jeon, Jae-Hong ; Yoo, Juhn-Suk ; Park, Cheol-Min ; Choi, Hong-Seok ; Han, Min-Koo
Author_Institution :
Sch. of Electr. Eng., Seoul Nat. Univ., South Korea
fDate :
4/1/2000 12:00:00 AM
Abstract :
We have investigated the excimer laser recrystallization of slightly oxygen-added amorphous silicon (a-SiO/sub x/) films for the application to the active layer of thin film transistors. We also propose a new method to reduce the surface roughness of poly-SiO/sub x/ films by etching the grain boundaries selectively. SEM images show that the Si-O bonds are well segregated into the poly-Si grain boundaries after laser crystallization and the surface morphology is remarkably improved after the selective buffered oxide etchant (BOE) etching of the grain boundaries. The electrical conductivity measurement shows that the activation energies of poly-SiO/sub x/ and poly-Si films have an identical value of 0.52 eV. This may confirm that oxygen-induced defects do not cause any difference in the electrical performance even at the oxygen concentration of 0.18 at.%. Moreover, the electrical mobility and subthreshold slope of poly-SiO/sub x/ TFTs are considerably improved by employing the proposed method, which smooths the poly-SiO/sub x//SiO/sub 2/ interface.
Keywords :
MOSFET; dielectric thin films; etching; grain boundaries; interface roughness; laser materials processing; recrystallisation; semiconductor-insulator boundaries; silicon compounds; surface topography; thin film transistors; Si-O bonds; SiO-SiO/sub 2/; TFT fabrication; activation energies; active layer; amorphous SiO films; buffered oxide etchant; electrical conductivity measurement; electrical mobility; excimer laser recrystallization; grain boundaries; interface smoothing; oxygen-induced defects; poly-SiO/sub x//SiO/sub 2/ interface; polysilicon TFTs; selective BOE etching; selective etching; smooth interface; subthreshold slope; surface morphology improvement; surface roughness reduction; thin film transistors; Amorphous silicon; Crystallization; Etching; Grain boundaries; Rough surfaces; Semiconductor films; Surface emitting lasers; Surface morphology; Surface roughness; Thin film transistors;
Journal_Title :
Electron Device Letters, IEEE
