Solid-state imaging device, manufacturing method of solid-state imaging device, and imaging system

A manufacturing method of a solid-state imaging device having a pixel in which a photoelectric conversion unit configured to accumulate electric charges generated by photoelectrically converting incident light, a transfer transistor of an MOS type configured to transfer the electric charges from the photoelectric conversion unit to a floating diffusion unit, and an outputting unit configured to output a signal corresponding to an amount of electric charges transferred to the floating diffusion unit are arranged in a well region of a second conductivity type, comprising the steps of:

• forming a first isolating region of the second conductivity type in which impurity concentration of the second conductivity type is higher than that of the well region into a deep region of a first semiconductor region of the well region;
• injecting impurities of a first conductivity type into the first semiconductor region from an upper surface of the first semiconductor region to a depth position where impurity concentration of the first conductivity type of the photoelectric conversion unit becomes a peak, thereby forming a counter dope region of the first conductivity type;
• forming a drain region of the first conductivity type in which impurity concentration of the first conductivity type is higher than that of the counter dope region into the counter dope region;
• forming a second isolating region of the second conductivity type in which impurity concentration of the second conductivity type is higher than that of the well region into a deep region of a second semiconductor region extending in a direction which perpendicularly crosses the first semiconductor region when seen as a plan view;
• and
• forming a plurality of transistors over the second isolating region and forming a buried channel region of the first conductivity type into channel regions of the plurality of transistors,
• wherein the step of forming the counter dope region and the step of forming the buried channel region are executed by using different photomasks.

An imaging system having a solid-state imaging device and a signal processing unit configured to process a signal which is output from the solid-state imaging device, wherein:

• the solid-state imaging device has a pixel in which a photoelectric conversion unit configured to accumulate electric charges generated by photoelectrically converting incident light, a transfer transistor of an MOS type configured to transfer the electric charges from the photoelectric conversion unit to a floating diffusion unit, and an outputting unit configured to output a signal corresponding to an amount of electric charges transferred to the floating diffusion unit are arranged in a well region of a second conductivity type;
• a first semiconductor region of the well region includes
• a first isolating region of the second conductivity type which is formed in a deep region below a drain region of a first conductivity type of the transfer transistor and in which impurity concentration of the second conductivity type is higher than that of the well region and
• a counter dope region of the first conductivity type which is formed in a region from an upper surface of the first semiconductor region to a depth position where impurity concentration of the first conductivity type of the photoelectric conversion unit becomes a peak so as to surround the drain region and in which the impurity concentration of the first conductivity type is lower than that of the drain region;
• a second semiconductor region extending in a direction which perpendicularly crosses the first semiconductor region when seen as a plan view includes
• a buried channel region of the first conductivity type formed in channel regions of a plurality of transistors which the outputting unit has and
• a second isolating region of the second conductivity type which is formed in a deep region below the buried channel region and in which impurity concentration of the second conductivity type is higher than that of the well region;
• and
• a depth position of a lower surface of the counter dope region is higher than a depth position of a lower surface of the buried channel region.