Solid state imaging device with improved heat radiation
View Patent ↗Formed on a semiconductor substrate is a CCD image sensor. The CCD image sensor has photodiodes arranged in a matrix form, a transfer path for transferring signal charges generated by the photodiodes, and an output amplifier for amplifying and outputting the signal charges. The transfer path and the output amplifier are covered with a light shielding film. This light shielding film has integral radiation fins.
1. A solid state imaging device comprising:
a semiconductor substrate;
an image sensor formed on said semiconductor substrate, said image sensor having a plurality of light receiving elements arranged in a matrix form;
a light shield covering a part of said image sensor for light protection; and
radiation fins formed integrally on said light shield,
wherein the plurality of light receiving elements is formed on said semiconductor substrate, wherein said image sensor is a CCD image sensor which includes:
vertical transfer electrodes for transferring signal charges accumulated in said light receiving elements in a vertical direction;
horizontal transfer electrodes connected perpendicular to said vertical transfer electrodes, for transferring said signal charges transferred from said vertical transfer electrodes in a horizontal direction; and
an output amplifier for amplifying and outputting said signal charges transferred from said horizontal transfer electrodes,
wherein said light shield is formed according to the positions of said horizontal transfer path and said output amplifier so as to cover said horizontal transfer electrodes and said output amplifier, whereas said radiation fins are formed above said output amplifier.
2. A solid state imaging device as claimed in claim 1 , wherein said radiation fins are also formed above said horizontal transfer electrodes.
3. A solid state imaging device as claimed in claim 1 , wherein said image sensor is a CMOS image sensor which includes:
pixel amplifiers for amplifying signal charges accumulated in said light receiving elements on a pixel basis and outputting said amplified signal charges as image signals;
pixel selectors for selectively reading out said image signals sequentially on a pixel basis; and
the output amplifier for amplifying said image signals read out by said pixel selectors.
4. A solid state imaging device as claimed in claim 3 , wherein said CMOS image sensor further includes:
a converter for converting said image signals from said output amplifier into digital data,
wherein said light shield also covers said converter, whereas said radiation fins are also formed above said converter.
5. A solid state imaging device as claimed in claim 3 , wherein said CMOS image sensor further includes:
a noise reduction processor for applying a noise reduction process to said image signals out of said output amplifier; and
a converter for converting said image signals after said noise reduction process into digital data,
wherein said light shield also covers said noise reduction processor and said converter, whereas said radiation fins are also formed above said noise reduction processor and said converter.
6. A solid state imaging device as claimed in claim 1 , wherein said radiation fins are of rectangular column shape and aligned parallel to each other at a regular interval.
7. A solid state imaging device as claimed in claim 6 , wherein said interval P (mm) satisfies the following equation
P
=
5
×
(
H
Δ
T
)
0.25
wherein H (mm) represents the height of said radiation fin, whereas ΔT (° C.) represents an average temperature rise of said light shield.
8. A solid state imaging device as claimed in claim 1 , wherein said radiation fins are of rectangular column shape and arranged in a spiral form.
9. A solid state imaging device as claimed in claim 1 , wherein said radiation fins are of cylindrical shape.
10. A solid state imaging device as claimed in claim 1 , wherein the radiation fins are formed directly above the part of said image sensor covered by the light shield for light protection.
11. A solid state imaging device as claimed in claim 1 , wherein the radiation fins are formed above the part of said image sensor covered by the light shield for light protection.
12. A solid state imaging device as claimed in claim 1 , wherein the radiation fins are formed on the light shield above said image sensor.
13. A solid state imaging device as claimed in claim 1 , wherein the light shield covering the part of said image sensor is provided on the same side as a light reception area of the image sensor.
14. A solid state imaging device as claimed in claim 1 , wherein the plurality of light receiving elements, the vertical transfer electrodes, the horizontal transfer electrodes and the output amplifier are formed directly on said semiconductor substrate.
15. A solid state imaging device as claimed in claim 1 , wherein the radiation fins are integrally formed on the light shield such that heat from heat generating components provided on the image sensor is dissipated individually.
16. A solid state imaging device as claimed in claim 1 , wherein the radiation fins are integrally formed on the light shield such that heat from a first heat generating component provided on the image sensor is dissipated independent of a heat dissipation of another component the image sensor.
17. A solid state imaging device as claimed in claim 1 , wherein said radiation fins are formed only directly above said output amplifier.
18. A solid state imaging device as claimed in claim 1 , wherein said light shield is formed only in areas of said horizontal transfer path and said output amplifier.