Solid-state imaging device
View Patent ↗In a solid-state imaging device, N regions serving as photoelectric conversion diodes are formed on outer peripheries of P regions in upper portions of island-shaped semiconductors formed on a substrate, and P + regions connected to a pixel selection line conductive layer are formed on top layer portions of upper ends of the island-shaped semiconductors so as to adjoin the N regions and the P regions. In the P + regions, a first P + region has a thickness less than a second P + region, and the second P + region has a thickness less than a third P + region.
1. A solid-state imaging device including a plurality of pixels which are formed of island-shaped semiconductors, the plurality of pixels being two-dimensionally arranged in a pixel region, comprising:
first semiconductor regions formed on a substrate;
base semiconductor regions formed on the first semiconductor regions, the base semiconductor regions forming the island-shaped semiconductors;
second semiconductor regions formed on outer peripheries of the base semiconductor regions which are spaced away from the first semiconductor regions, the second semiconductor regions forming diodes together with the base semiconductor regions; and
third semiconductor regions formed above the second semiconductor regions so as to adjoin the base semiconductor regions, the third semiconductor regions having a conductivity type opposite to a conductivity type of the second semiconductor regions, wherein
the third semiconductor region includes a sufficient quantity of acceptor or donor impurities that signal charges generated by absorption of incident light incident on top surfaces of upper ends of the island-shaped semiconductors in the third semiconductor regions are recombined and disappear in the third semiconductor regions,
the island-shaped semiconductors are formed to include the third semiconductor regions having at least two different thicknesses,
in the island-shaped semiconductors, a color filter of a primary color or a complementary color is formed over the third semiconductor region of a first island-shaped semiconductor including the third semiconductor region having the smallest thickness or a second island-shaped semiconductor including the third semiconductor region having the second smallest thickness, and light transmitted through the color filter includes a light wavelength component which undergoes light absorption and accumulation of signal charges in the diode region in the first island-shaped semiconductor or second island-shaped semiconductor located below the color filter, and
the solid-state imaging device performs an imaging operation which includes
a photoelectric conversion operation for absorbing light incident on the top surfaces of the upper ends of the island-shaped semiconductors, in diode regions formed by the second semiconductor regions and the base semiconductor regions, and generating signal charges,
a signal charge accumulating operation for accumulating the generated signal charges in the diode regions,
an accumulated signal charge quantity read operation for sensing the quantity of signal charges accumulated in the diode regions by detecting a source-drain current flowing through junction field-effect transistors, the junction field-effect transistors having sources or drains which are defined by the first semiconductor regions or the third semiconductor regions, gates which are defined by the second semiconductor regions, and channels which are defined by the base semiconductor regions surrounded by the second semiconductor regions, and
a signal charge discharging operation for discharging the signal charges accumulated in the diode regions to the first semiconductor regions.
2. The solid-state imaging device according to claim 1 , wherein
the first island-shaped semiconductor has the third semiconductor region that transmits blue wavelength light, green wavelength light, and red wavelength light which are incident on the top surfaces of the upper ends of the island-shaped semiconductors,
the second island-shaped semiconductor has the third semiconductor region that absorbs blue wavelength light which is incident on the top surfaces of the upper ends of the island-shaped semiconductors,
the island-shaped semiconductors further include a third island-shaped semiconductor having the third semiconductor region that absorbs blue wavelength light and green wavelength light which are incident on the top surfaces of the upper ends of the island-shaped semiconductors,
the first island-shaped semiconductor, the second island-shaped semiconductor, and the third island-shaped semiconductor are formed so that
in the diode region in the first island-shaped semiconductor, photoelectric conversion is performed on the blue wavelength light, green wavelength light, and red wavelength light which are incident on the top surface of the upper end of the first island-shaped semiconductor, and signal charges obtained by the photoelectric conversion are accumulated,
in the diode region in the second island-shaped semiconductor, photoelectric conversion is performed on green wavelength light and red wavelength light which are incident on the top surface of the upper end of the second island-shaped semiconductor, and signal charges obtained by the photoelectric conversion are accumulated, and
in the diode region in the third island-shaped semiconductor, photoelectric conversion is performed on red wavelength light which is incident on the top surface of the upper end of the third island-shaped semiconductor, and signal charges obtained by the photoelectric conversion are accumulated, and
the first island-shaped semiconductor, the second island-shaped semiconductor, and the third island-shaped semiconductor are formed so that
the third semiconductor region of the first island-shaped semiconductor has a thickness less than the third semiconductor region of the second island-shaped semiconductor, and the third semiconductor region of the second island-shaped semiconductor has a thickness less than the third semiconductor region of the third island-shaped semiconductor, and
the first island-shaped semiconductor, the second island-shaped semiconductor, and the third island-shaped semiconductor are adjacent to one another.
3. The solid-state imaging device according to claim 2 , wherein
the color filter of a primary color or a complementary color is further formed on the top of the first island-shaped semiconductor or on the top of the second island-shaped semiconductor, and light transmitted through the color filter includes a light wavelength component which undergoes light absorption and accumulation of signal charges in the diode region in the first island-shaped semiconductor or second island-shaped semiconductor located below the color filter.
4. The solid-state imaging device according to claim 1 , wherein
the first island-shaped semiconductor having on the top thereof a color filter that transmits blue wavelength light, and the first island-shaped semiconductor not having on the top thereof the color filter that transmits the blue wavelength light are formed in the pixel region, and a white signal current including a blue wavelength light component, a green wavelength light component, and a red wavelength light component is obtained from the first island-shaped semiconductor not having on the top thereof the color filter that transmits the blue wavelength light.
5. The solid-state imaging device according to claim 1 , wherein
the island-shaped semiconductors include
a fourth island-shaped semiconductor having a diode region where photoelectric conversion is performed on blue wavelength light, green wavelength light, and red wavelength light transmitted through the third semiconductor region and signal charges obtained by the photoelectric conversion are accumulated, and
a fifth island-shaped semiconductor having a diode region where photoelectric conversion is performed on either or both of green wavelength light and red wavelength light transmitted through the third semiconductor region and signal charges obtained by the photoelectric conversion are accumulated,
the third semiconductor region of the fifth island-shaped semiconductor has a thickness greater than or equal to the third semiconductor region of the fourth island-shaped semiconductor,
a sixth island-shaped semiconductor having a structure similar to the second semiconductor region and the third semiconductor region in the fourth island-shaped semiconductor and the fifth island-shaped semiconductor is formed in the pixel region,
a color filter of a primary color or a complementary color is formed on the top of the sixth island-shaped semiconductor, and
the fourth island-shaped semiconductor, the fifth island-shaped semiconductor, and the sixth island-shaped semiconductor are formed adjacent to one another.
6. The solid-state imaging device according to claim 1 , wherein
the island-shaped semiconductors include
a seventh island-shaped semiconductor having a diode region where photoelectric conversion is performed on blue wavelength light, green wavelength light, and red wavelength light transmitted through the third semiconductor region and signal charges obtained by the photoelectric conversion are accumulated, and
an eighth island-shaped semiconductor having a diode region where photoelectric conversion is performed on green wavelength light and red wavelength light transmitted through the third semiconductor region and signal charges obtained by the photoelectric conversion are accumulated,
the third semiconductor region of the eighth island-shaped semiconductor has a thickness greater than the third semiconductor region of the seventh island-shaped semiconductor,
a ninth island-shaped semiconductor having a structure similar to the second semiconductor region and the third semiconductor region in the seventh island-shaped semiconductor and the eighth island-shaped semiconductor is formed in the pixel region,
a color filter of a primary color or a complementary color is formed on the top of the ninth island-shaped semiconductor, and
the seventh island-shaped semiconductor, the eighth island-shaped semiconductor, and the ninth island-shaped semiconductor are formed adjacent to one another.
7. The solid-state imaging device according to claim 1 , wherein
an insulating layer that transmits light is formed between the substrate and the first semiconductor regions, and the thickness of the insulating layer is set so that, of light rays incident on the top surfaces of the upper ends of the island-shaped semiconductors, a light ray returning from the insulating layer to the diode regions in the island-shaped semiconductors has more red wavelength component than green wavelength component.
8. The solid-state imaging device according to claim 1 , wherein
in the pixel region, the island-shaped semiconductors including the third semiconductor regions having at least two different thicknesses are arranged in a zigzag or staggered manner.