Semiconductor device and method of manufacturing same

A semiconductor device, comprising:

• a semiconductor substrate having a main surface;
• a buried impurity layer formed in the semiconductor substrate;
• a p type epitaxial layer formed over the buried impurity layer;
• and
• a first photoelectric conversion element formed in the p type epitaxial layer,
• wherein the buried impurity layer and the p type epitaxial layer each have silicon, and
• the buried impurity layer has a p type impurity concentration higher than that of the p type epitaxial layer.

A method of manufacturing a semiconductor device, comprising the steps of:

• providing a semiconductor substrate having a main surface;
• forming a first p type epitaxial layer over the main surface;
• forming a second p type epitaxial layer so as to cover an upper surface of the first p type epitaxial layer;
• forming a first photoelectric conversion element in the second p type epitaxial layer;
• and
• forming a first p type impurity region in the second p type epitaxial layer,
• wherein the first and second p type epitaxial layers each have silicon,
• wherein the first p type epitaxial layer has a p type impurity concentration higher than that of the second p type epitaxial layer, and
• wherein the first p type impurity region has a p type impurity concentration different than that in the second p type epitaxial layer.