Semiconductor image sensors

• US 4,377,817 A
• Filed: 03/17/1980
• Issued: 03/22/1983
• Est. Priority Date: 03/19/1979
• Status: Expired due to Term

• Current Assignee: Semiconductor Research Foundation
• Original Assignee: Semiconductor Research Foundation
• Inventors: Ohmi, Tadahiro, Nishizawa, Jun-ichi
• Primary Examiner(s): Edlow, Martin H.
• Application Number:
  US06/130,775
• Time in Patent Office: 1,100 Days
• Field of Search: 357/22, 357/41, 357/30
• US Class Current: 257/258
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14679 Junction field effect transistor [JFET] imagers; static induction transistor [SIT] imagers
• CPC Class Codes: H01L 31/1126 the device being a field-effect phototransistor

Abstract

This invention relates to a semiconductor image sensors and more particularly, to a back-illuminated-type static induction transistor image sensors.

FIGS. 4A to 4C show the back illuminated type SIT image sensors operating in the electron depletion storing mode, where the n⁺ buried floating region 23 serves as storage region.

Claims

1. A semiconductor image sensor including a multiplicity of photo-sensor elements disposed in a matrix of rows and columns in a semiconductor body having first and second principal surfaces, each photo-sensor element comprising:

a transistor comprising a first current terminal region including a first low resistivity semiconductor region of a first conductivity type disposed in said first principal surface, a second current terminal region including a second low resistivity semiconductor region of said first conductivity type disposed in said semiconductor body below and separated away from said first current terminal region, a current path region including a first high resistivity semiconductor region disposed between said first and second current terminal region, and a control terminal region disposed adjacent to said current path region, said second current terminal region being electrically floated;

a third low resistivity semiconductor region of said first conductivity type disposed in said second principal surface; and

a photo-sensing semiconductor region disposed between said second and third low resistivity semiconductor regions.

2. A semiconductor image sensor according to claim 1, wherein:

said first high resistivity semiconductor region has said first conductivity type and said transistor is a unipolar transistor.

3. A semiconductor image sensor according to claim 1, wherein:

said first high resistivity semiconductor region has said second conductivity type.

4. A semiconductor image sensor according to claim 1, wherein:

said second high resistivity semiconductor region has a substantially intrinsic conductivity type.

5. A semiconductor image sensor according to claim 1, wherein:

said second high resistivity semiconductor region has said first conductivity type.

6. A semiconductor image sensor according to claim 1, wherein:

said second high resistivity semiconductor region has said second conductivity type.

7. A semiconductor image sensor according to claim 2, wherein:

said first high resistivity semiconductor region has such a short length between said first and second low resistivity semiconductor regions, and such a low impurity concentration that said transistor constitutes a static induction transistor providing unsaturating I-V characteristics.

8. A semiconductor image sensor according to claim 1, further comprising:

a subsidiary current terminal region including a fourth low resistivity semiconductor region of said second conductivity type disposed in said first principal surface;

a third high resistivity semiconductor region disposed between said barrier semiconductor region and said subsidiary current terminal region; and

another control terminal region disposed adjacent to said third high resistivity semiconductor region.

9. A semiconductor image sensor according to claim 1, 2 or 3, comprising a second high resistivity semiconductor region (22) adjacent said third low resistivity region (21) and wherein a barrier semiconductor region (31) is disposed between said second high resistivity semiconductor region (22) and said second current terminal region (23), said barrier semiconductor region having a relatively low resistivity and a relatively thin thickness compared to said second high resistivity semiconductor region, said barrier semiconductor region being electrically floated.

10. A semiconductor image sensor including a multiplicity of photo-sensor elements disposed in a matrix of rows and columns in a semiconductor body having first and second principal surfaces, each photo-sensor element comprising:

a transistor comprising a first current terminal region including a first two resistivity semiconductor region (25) of a first conductivity type disposed in said first principal surface, a second current terminal region comprising a second low resistivity semiconductor region (23) of said first conductivity type disposed in said semiconductor body below and separated away from said first current terminal region, a current path region including a first high resistivity semiconductor region (24) disposed between said first and second low resistivity semiconductor regions, and a control terminal region (26 or

     31) disposed adjacent to said current path region, said second current terminal region being electrically floated;

a third low resistivity semiconductor region (41) of a second conductivity type opposite to said first conductivity type disposed in said second principal surface;

a transparent electrode (41'"'"') disposed on said third low resistivity region, and

a photo-sensing high resistivity semiconductor region (22 or

     32) disposed between said second and third low resistivity semiconductor regions.