Dramatic reduction of optical crosstalk in deep-submicrometer CMOS imager with air gap guard ring

Author

Hsu, T.H. ; Fang, Y.K. ; Yaung, D.N. ; Wuu, S.G. ; Chien, H.C. ; Wang, C.S. ; Lin, J.S. ; Tseng, C.H. ; Chen, S.F. ; Lin, C.S. ; Lin, C.Y.

Author_Institution

Dept. of Electr. Eng., National Cheng Kung Univ., Tainan, Taiwan

Volume

25

Issue

6

fYear

2004

fDate

6/1/2004 12:00:00 AM

Firstpage

375

Lastpage

377

Abstract

A dielectric structure, air gap guard ring, has been successfully developed to reduce optical crosstalk thus improving pixel sensitivity of CMOS image sensor with 0.18-μm technology. Based on refraction index (RI) differences between dielectric films (RI = 1.4 /spl sim/ 1.6) and air gap (RI = 1), total internal reflection occurred at dielectric-film/air-gap interface, thus the incident light is concentrated in selected pixel. Excellent optical performances have been demonstrated in 3.0 × 3.0 μm pixel. Optical spatial crosstalk achieves 80% reduction at 20/spl deg/ incidence angle and significantly alleviates the pixel sensitivity degradation with larger angle of incident light.

Keywords

CMOS image sensors; air gaps; dielectric thin films; optical crosstalk; refractive index; 0.18 micron; CMOS image sensor; air gap guard ring; deep-submicrometer CMOS imager; dielectric films; dielectric structure; dielectric-film/air-gap interface; incidence angle; incident light; internal reflection; optical spatial crosstalk; pixel sensitivity improvement; refraction index; Air gaps; CMOS image sensors; CMOS technology; Dielectric films; Optical crosstalk; Optical films; Optical reflection; Optical refraction; Optical sensors; Pixel;

fLanguage

English

Journal_Title

Electron Device Letters, IEEE

Publisher

ieee

ISSN

0741-3106

Type

jour

DOI

10.1109/LED.2004.828995

Filename

1302231