Method of making charge coupled device image sensor

Abstract

A method of making a charge coupled device image sensor comprising forming n.sup.+ type impurity regions for light receiving element and charge transfer element over a p type well of a n type substrate, forming an oxide film for insulating a gate over the substrate, forming a nitride film over the oxide film, the nitride film serving as an etch stopper, forming an insulating film such as a LTO film or BPSG film, forming a p.sup.+ type third impurity region in the p type well, forming an electrode over the third impurity region, and forming a PECVD LTO film. The PECVD LTO film and insulating film are removed by a wet etching method or a CDE method, so as to expose partially the nitride film. The wet etching is carried out under the condition that the nitride film is used as an etch stopper, thereby capable of solving the problem of a damage of substrate caused by a dry etching and thus avoiding generations of dark current and white defect. The thickness of the oxide film disposed beneath the nitride film can be easily adjusted to avoid a smear phenomenon.