The effects of off-axis substrate orientation on MOSFET characteristics

Author

Chung, J. ; Chen, J. ; Levi, M. ; Ko, P.-K. ; Hu, C.

Author_Institution

Dept. of Electr. Eng. & Comput. Sci., California Univ., Berkeley, CA, USA

fYear

1989

fDate

3-6 Dec. 1989

Firstpage

633

Lastpage

636

Abstract

The effects of off-axis substrate orientation on MOSFET performance and reliability are examined. As the <100> wafer is tilted off-axis around the <011> axis, two principal effects are observed. First, for current flow normal to the axis of rotation, inversion-layer mobility is lower than for current flow in the parallel direction. This mobility difference is due to anisotropy in the inversion-layer effective mass as well as increased surface roughness in the normal direction. Second, because surface roughness enhances nonuniform oxidation, thin spots in the gate oxide are generated which increase the susceptibility of the gate oxide to defect-related failure. The performance anisotropy may possibly be alleviated by rotating substrates in the <001> direction, such that the normal and parallel directions possess equivalent inversion-layer effective mass and degrees of surface roughness. The oxide quality may possibly be improved by using a two-step oxidation procedure, where an intermediate high-temperature anneal is used to smooth the oxide.<>

Keywords

carrier mobility; insulated gate field effect transistors; reliability; substrates; <001> direction; <011> axis; <100> wafer; MOSFET characteristics; current flow; defect-related failure; gate oxide; intermediate high-temperature anneal; inversion-layer effective mass; inversion-layer mobility; nonuniform oxidation; offaxis orientation; oxide quality improvement; performance anisotropy; reliability; substrate orientation; surface roughness; two-step oxidation procedure; Anisotropic magnetoresistance; Annealing; Effective mass; Gallium arsenide; MOSFET circuits; Oxidation; Petroleum; Rough surfaces; Silicon; Surface roughness;

fLanguage

English

Publisher

ieee

Conference_Titel

Electron Devices Meeting, 1989. IEDM '89. Technical Digest., International

Conference_Location

Washington, DC, USA

ISSN

0163-1918

Print_ISBN

0-7803-0817-4

Type

conf

DOI

10.1109/IEDM.1989.74360

Filename

74360