Polysilicon resistor trimming by laser link making

Author

Parker, Donald L. ; Huang, Weiling

Author_Institution

Dept. of Electr. Eng., Texas A&M Univ., College Station, TX, USA

Volume

3

Issue

2

fYear

1990

fDate

5/1/1990 12:00:00 AM

Firstpage

80

Lastpage

83

Abstract

A technique for laser trimming of polysilicon resistors has been developed. In this scheme an undoped polysilicon film is patterned lithographically, and then photoresist patterns are used to prevent doping of certain narrow areas of each resistor during the impurity implant; thus, the protected areas remain insulating after wafer processing. Subsequent laser scanning of the undoped regions can produce precise reductions in resistance by lateral diffusion of dopant impurities. Trimming can be accomplished by changing either the laser power or the position. Q-switched Nd:YAG (1.06-μm wavelength) and second-harmonic (0.53-μm wavelength) radiations have produced successful results. The process was applied to passivated resistors with negligible (perhaps zero) post-trim drift, and the temperature coefficients of resistivity (TCRs) of trimmed resistors can be matched to the TCRs of untrimmed resistors in the same film

Keywords

diffusion in solids; elemental semiconductors; integrated circuit technology; laser beam applications; resistors; silicon; 0.53 micron; 1.06 micron; IC fabrication; Q-switched laser beam; YAG:Nd; YAl5O12:Nd; dopant impurities; laser link making; lateral diffusion; passivated resistors; photoresist patterns; polycrystalline Si; polysilicon resistors; resistor trimming; second harmonic radiations; temperature coefficients of resistivity; undoped polysilicon film; undoped-region laser scanning; Conductivity; Doping; Implants; Impurities; Insulation; Power lasers; Protection; Resistors; Resists; Temperature;

fLanguage

English

Journal_Title

Semiconductor Manufacturing, IEEE Transactions on

Publisher

ieee

ISSN

0894-6507

Type

jour

DOI

10.1109/66.53190

Filename

53190