Ellipsometry study on silicon nitride film with uneven thickness distribution by plasma-enhanced chemical vapor deposition

Abstract

As passivation layer and anti-re ection layer, silicon nitride (SiNx) thin lm has been widely used in photovoltaic devices such as solar cells. The structure of SiNx lm with thickness gradient can make full use of different wavelengths of sunlight. In this paper, we have studied this structure for the rst time.While introducing a quartz layer by plasma-enhanced chemical vapor deposition (PECVD), we obtained a thin SiNx lm in the center and gradually thicker toward the edge. The effects of PECVD process parameters, including deposition time, RF power, dielectric layer thickness, etc. on the thickness gradient of SiNx thin lm are systematically studied. The lm composition changing in the radial direction is also analyzed by ellipsometry. This study provides an instructive method for controlling the thickness gradient of SiNx lms and plays an important role in using this structure to the solar cell application.