# US 9,437,638 B2 · Photodetector for imaging system

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- Number: US 9,437,638 B2
- Document ID: US9437638B2
- Status: Granted
- Kind: B2
- Application number: 12/602,954
- Filed: 2008-06-04
- Published: 2010-08-12
- Granted: 2016-09-06
- Earliest claimed: 2007-06-04
- Assignees: Detection Technology Oy
- Applicants: Fan Ji; Mikko Juntunen; Iiro Hietanen
- Inventors: Fan Ji; Mikko Juntunen; Iiro Hietanen
- Web page: https://patentgrep.com/patent/US9437638B2

## CPC

- H10F 39/189: {X-ray, gamma-ray or corpuscular radiation imagers}
- A61B 6/035: {Mechanical aspects of CT}
- A61B 6/4233: {using matrix detectors}
- H10F 39/809: {of hybrid image sensors}
- H10W 20/023: {the interconnections being through-semiconductor vias}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

There is disclosed a substrate including at least one photodetector, the photodetector having a first active area on a first surface of the substrate and a second active area on a second surface of the substrate, wherein the photodetector is provided with a conductive via electrically isolated from the substrate, said conductive via extending through the photodetector from the first surface of the substrate to the second surface of the substrate for connecting the first active area to the second surface of the substrate, the second surface providing electrical connections for the first and second active areas of the photodetector.

## Claims

### Claim 1

A substrate comprising:
a plurality of photodetectors;
a first active area on a first surface of the substrate; and
a second active area on a second surface of the substrate,
wherein the plurality of photodetectors are each provided with a conductive via electrically isolated from the substrate, each conductive via extending through its corresponding photodetector from the first surface of the substrate to the second surface of the substrate for connecting the first active area to the second surface of the substrate, and each conductive via being fully and continuously filled with a conductive material, and having no joints;
each conductive via having: a first portion entirely of a first width extending from the first surface into the substrate by a first depth, the first portion not extending perpendicularly from the first surface such that an extrapolation of the first portion to the second surface does provide an opening of the first width at the second surface which does not align with an opening of the first portion of the first width at the first surface; and a second portion entirely of a second width extending from the second surface into the substrate by a second depth to abut the first portion, wherein the first width is smaller than the second width and the first depth is larger than the second depth;
an oxide layer formed over the second surface and having openings aligned with the openings of the first portion of the plurality of conductive vias at the first surface, the openings in the oxide layer exposing only the conductive material filling of the second portion at the second surface; and
the second surface comprising electrical connections for the first and second active areas.

### Claim 2 (depends on 1)

The substrate according to claim 1 wherein the second portion of the second width is formed proximate the second surface and the first portion of the first width extends from the second portion of the second width to the first surface.

### Claim 3 (depends on 1)

The substrate according to claim 1 wherein each conductive via extends through the first active area.

### Claim 4 (depends on 1)

The substrate according to claim 1 wherein there is provided a further conductive element on the second surface of the substrate connected to each conductive via.

### Claim 5 (depends on 4)

The substrate according to claim 4 wherein the further conductive element on the second surface of the substrate is for making an off-chip connection to the first active area via each conductive via.

### Claim 6 (depends on 4)

The substrate according to claim 4 wherein the further conductive element is an aluminum contact element.

### Claim 7 (depends on 1)

The substrate according to claim 1 wherein the plurality of photodetectors are photodiodes of a medical imaging system.

### Claim 8 (depends on 7)

The substrate according to claim 7 wherein the medical imaging system is a computed tomography system.

### Claim 9 (depends on 7)

The imaging system according to claim 7 wherein the medical imaging system has an X-ray radiation source.

### Claim 10

A method of manufacturing photodetector devices comprising:
forming a first active area of each photodetector device on a first surface of a substrate;
forming a second active area on a second surface of the substrate;
forming a plurality of conductive vias electrically isolated from the substrate, each of the plurality of conductive vias extending through its corresponding photodetector device from the first surface of the substrate to the second surface of the substrate, each of the plurality of conductive vias having: a first portion of entirely a first width, the first portion not being formed perpendicular from the first surface such that an extrapolation of the first portion to the second surface does provide an opening of the first width at the second surface that does not align with an opening of the first portion of the first width at the first surface, and extending to abut a second portion of entirely a second width, the second width being greater than the first width and a depth of the first portion being greater than a depth of the second portion;
fully and continuously filling the plurality of conductive vias with a conductive material, the plurality of conductive vias having no joints;
forming an oxide layer over the second surface;
forming openings in the oxide layer aligned with the openings of the first portion of the plurality of conductive vias at the first surface, the openings in the oxide layer exposing only the conductive material filling of the second portion at the second surface; and
connecting each first active area respectively to each one of the plurality of conductive vias such that the first active area is connected to the second surface of the substrate.

### Claim 11 (depends on 10)

The method according to claim 10 further comprising forming the second portion of the second width proximate the second surface and forming the first portion of the first width extending from the second portion of the second width to the first surface.

### Claim 12 (depends on 10)

The method according to claim 10 further comprising forming each conductive via extending through the first active area.

### Claim 13 (depends on 10)

The method according to claim 10 further comprising the step of providing a further conductive element on the second surface of the substrate connected to the conductive via.

### Claim 14 (depends on 13)

The method according to claim 13 wherein the further conductive element on the second surface of the substrate is provided for making an off-chip connection to the first active area via the conductive via.