Photoelectric conversion element and manufacturing method of photoelectric conversion element

A photoelectric conversion element, comprising:

• a photoelectric conversion layer including stacked layers of a first semiconductor layer, a second semiconductor layer and a third semiconductor layer;
• the first semiconductor layer containing an impurity element of one conductivity type, on a conductive layer,
• the second semiconductor layer formed on the first semiconductor layer, and
• the third semiconductor layer containing an impurity element of an opposite conductivity type to that in the first semiconductor layer, on the second semiconductor layer,
• wherein a side surface of the photoelectric conversion layer includes
• a surface with a first taper angle and
• a surface with a second taper angle,
• wherein the surface with the first taper angle includes a side surface of the first semiconductor layer and a part of a side surface of the second semiconductor layer,
• wherein the surface with the second taper angle includes another part of the side surface of the second semiconductor layer and a side surface of the third semiconductor layer, and
• wherein the surface with the first taper angle has a larger taper angel than the surface with the second taper angle.

A method for manufacturing a photoelectric conversion element, comprising:

• forming a conductive layer over a substrate;
• forming a first semiconductor layer containing an impurity element of one conductivity type, on the conductive layer;
• forming a second semiconductor layer on the first semiconductor layer;
• forming a third semiconductor layer containing an impurity element of an opposite conductivity type to that in the first semiconductor layer, on the second semiconductor layer;
• selectively forming a resist having a tapered shape over the first to third semiconductor layers;
• conducting a first dry etching to remove a part of the third semiconductor layer and a part of the second semiconductor layer with use of the resist;
• conducting a second dry etching to remove a part of the third semiconductor layer and a part of the second semiconductor layer with use of a gas containing O2 and having an etching rate of the second semiconductor layer lower than a gas used in the first dry etching, wherein an oxide layer is formed on the third semiconductor layer due to the second dry etching, and
• conducting a third dry etching to remove the oxide layer with use of a gas having an etching rate of the oxide layer higher than that of the second semiconductor layer.

A method for manufacturing a photoelectric conversion element, comprising:

• forming a conductive layer over a substrate;
• forming a protective layer on the conductive layer;
• forming a first semiconductor layer containing an impurity element of one conductivity type, on the conductive layer;
• forming a second semiconductor layer on the first semiconductor layer;
• forming a third semiconductor layer containing an impurity element of an opposite conductivity type to that in the first semiconductor layer, on the second semiconductor layer;
• selectively forming a resist having a tapered shape over the first to third semiconductor layers;
• conducting a first dry etching to remove a part of the third semiconductor layer and a part of the second semiconductor layer with use of the resist;
• conducting a second dry etching to remove a part of the third semiconductor layer and a part of the second semiconductor layer with use of a gas containing O2 and having an etching rate of the second semiconductor layer lower than a gas used in the first dry etching, wherein an oxide layer is formed on the third semiconductor layer due to the second dry etching, and
• conducting a third dry etching to remove the oxide layer with use of a gas having an etching rate of the oxide layer higher than that of the second semiconductor layer.