Solid-State Image Sensing Device with a Capacitance Switching Transistor Overlapping a Photodiode and Electronic Device Having the Same

Abstract

The present technology relates to a solid-state image sensing device capable of restricting a deterioration in photoelectric conversion characteristic of a photoelectric conversion unit, and an electronic device. A solid-state image sensing device includes: a photoelectric conversion unit formed outside a semiconductor substrate; a charge holding unit for holding signal charges generated by the photoelectric conversion unit; a reset transistor for resetting the potential of the charge holding unit; a capacitance switching transistor connected to the charge holding unit and directed for switching the capacitance of the charge holding unit; and an additional capacitance device connected to the capacitance switching transistor. The present technology is applicable to solid-state image sensing devices and the like, for example.

1 . A light detecting device, comprising:
 a photoelectric conversion unit formed above a semiconductor substrate,   wherein the photoelectric conversion unit includes an upper electrode, a lower electrode, and a photoelectric conversion film disposed between the upper electrode and the lower electrode;   a charge holding unit disposed in the semiconductor substrate and configured to accumulate signal charges generated by the photoelectric conversion unit;   a reset transistor configured to reset a potential of the charge holding unit;   a capacitance switching transistor connected to the charge holding unit and configured to switch a capacitance of the charge holding unit; and   an additional capacitance device connected to the capacitance switching transistor.   
     
     
         2 . The light detecting device according to  claim 1 , wherein the capacitance switching transistor is connected between the reset transistor and the charge holding unit. 
     
     
         3 . The light detecting device according to  claim 2 , wherein in a case where the capacitance of the charge holding unit is switched to a low capacitance by the capacitance switching transistor, the reset transistor is controlled to always be set to on. 
     
     
         4 . The light detecting device according to  claim 2 , wherein the reset transistor resets the potential of the charge holding unit at the same potential as the semiconductor substrate. 
     
     
         5 . The light detecting device according to  claim 4 , wherein the reset transistor resets the potential of the charge holding unit at ground. 
     
     
         6 . The light detecting device according to  claim 1 , wherein the additional capacitance device is configured of a metal oxide semiconductor (MOS) capacitor. 
     
     
         7 . The light detecting device according to  claim 6 , wherein a gate part of the MOS capacitor is connected to the charge holding unit. 
     
     
         8 . The light detecting device according to  claim 6 , wherein a diffusion layer of the MOS capacitor in the semiconductor substrate is connected to the charge holding unit. 
     
     
         9 . The light detecting device according to  claim 1 , wherein the reset transistor resets the potential of the charge holding unit at a power supply voltage. 
     
     
         10 . The light detecting device according to  claim 1 , wherein the capacitance switching transistor and the reset transistor are connected in series. 
     
     
         11 . The light detecting device according to  claim 1 , wherein the capacitance switching transistor and the reset transistor are connected in parallel. 
     
     
         12 . The light detecting device according to  claim 1 , further comprising a different photoelectric conversion unit above or below the photoelectric conversion unit. 
     
     
         13 . The light detecting device according to  claim 12 , wherein the different photoelectric conversion unit is a photodiode formed in the semiconductor substrate. 
     
     
         14 . The light detecting device according to  claim 1 , wherein the signal charges generated by the photoelectric conversion unit are holes. 
     
     
         15 . The light detecting device according to  claim 1 , wherein the signal charge generated by the photoelectric conversion unit is an electron. 
     
     
         16 . An electronic device, comprising:
 a light detecting device, comprising: 
 a photoelectric conversion unit formed above a semiconductor substrate, 
 wherein the photoelectric conversion unit includes an upper electrode, a lower electrode, and a photoelectric conversion film disposed between the upper electrode and the lower electrode; 
 a charge holding unit disposed in the semiconductor substrate and configured to accumulate signal charges generated by the photoelectric conversion unit; 
 a reset transistor configured to reset a potential of the charge holding unit; 
 a capacitance switching transistor connected to the charge holding unit and configured to switch a capacitance of the charge holding unit; and 
 an additional capacitance device connected to the capacitance switching transistor. 
   
     
     
         17 . The electronic device according to  claim 16 , further comprising:
 a control circuit for outputting a control signal for controlling the capacitance switching transistor.   
     
     
         18 . The electronic device according to  claim 17 , wherein the control circuit outputs a control signal for controlling the capacitance switching transistor based on an image shot by the light detecting device. 
     
     
         19 . The electronic device according to  claim 17 , wherein the control circuit outputs a control signal for controlling the capacitance switching transistor based on user-designated setting information. 
     
     
         20 . The electronic device according to  claim 16 , wherein the additional capacitance device is configured of a metal oxide semiconductor (MOS) capacitor.