Semiconductor photosensor
A photoelectric sensor, semiconductor technology, applied in the direction of semiconductor devices, instruments, circuits, etc., can solve the problem that the short-wave band has not been improved
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no. 1 example
[0026] FIG. 1 shows a circuit configuration of a semiconductor photosensor according to a first embodiment of the present invention. The semiconductor photosensor has photodiode sections 1 and 2 , amplifiers 3 , 4 and 5 , and an output circuit 6 .
[0027] FIG. 2A shows a longitudinal cross-sectional structure of photodiode sections 1 and 2 .
[0028] Photodiode portion 1 is formed of n-type epitaxial layer 8 formed on p-type semiconductor substrate 7 and p-type diffusion layer 9 formed on the surface of n-type epitaxial layer 8 . A short-wave cut filter 10a is formed on top of the final structure via insulating films 204 and 205, wherein the filter 10a cuts light in the short-wave region.
[0029] The photodiode section 2 has the same photodiode structure as the photodiode section 1 . In addition, an infrared transmission filter 11 and a short-wave cut filter 10b are stacked on top of the final structure via insulating films 204 and 205 . The infrared transmission filter 1...
no. 3 example
[0069] A semiconductor photosensor according to a third embodiment of the present invention will be described below with reference to FIG. 9 showing the arrangement of the photosensor. The semiconductor photosensor includes photodiode sections 1 and 2 , amplifiers 3 , 18 and 19 , a reference voltage generator 20 , a comparison voltage generator 21 , a comparator 22 , and a logic circuit 23 .
[0070] As in the first embodiment, the amplifier 3 subtracts the photocurrent of the photodiode section 1 from the photocurrent of the photodiode section 2, thereby matching characteristics to visual sensitivity.
[0071] Thereafter, the output of amplifier 3 is amplified by amplifiers 18 and 19 and input to comparator 22 .
[0072] The reference voltage generator 20 generates a reference voltage such as a bandgap constant voltage. The comparison voltage generator 21 generates a comparison voltage on the basis of the reference voltage generated by the reference voltage generator 20 . T...
no. 4 example
[0076] 10A shows a cross-sectional structure of a photodiode in a semiconductor photosensor according to a fourth embodiment of the present invention. In the first embodiment described above, the infrared transmission filter 11 and the short-wave cut filter 10b are laminated on top of the photodiode section 2 through the insulating films 204 and 205 in this order.
[0077] However, in the fourth embodiment, the short-wave cut filter 10 b and the infrared transmission filter 11 are stacked sequentially over the insulating film 205 .
[0078] In the photodiode section 2 using this filter stacking order of the fourth embodiment, the short-wave cut filter 10b is formed so as to be close to the epitaxial layer 8 in which the photodiode is formed, as in the photodiode section 1 . Therefore, unlike the first embodiment, light obliquely incident from above photodiode portion 2 passes through short-wave cut filter 10 b under the same conditions as light obliquely incident from above p...
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