3D HIGH RESOLUTION X-RAY SENSOR WITH INTEGRATED SCINTILLATOR GRID
Various embodiments of a 3D high resolution X-ray sensor are described. In one aspect, an indirect X-ray sensor includes a silicon wafer that includes an array of photodiodes thereon with each of the photodiodes having a contact on a front side of the silicon wafer and self-aligned with a respective grid hole of an array of grid holes that are on a back side of the silicon wafer. Each of the grid holes is filled with a scintillator configured to convert beams of X-ray into light. The indirect X-ray sensor also includes one or more silicon dies with an array of photo-sensing circuits each of which including a contact at a top surface of the one or more silicon dies. Contact on each of the photodiodes is aligned and bonded to contact of a respective photo-sensing circuit of the array of photo-sensing circuits of the one or more silicon dies.
1 . A direct X-ray sensor, comprising:
a direct X-ray sensing substrate comprising:
a photoconductor with a common electrode on a first side of the photoconductor and a pixel electrode on a second side of the photoconductor such that a voltage applied to the common electrode and the pixel electrode creates an electric field in the photoconductor; and
a contact on a surface of a wafer of the substrate connected to the pixel electrode on the second side of the photoconductor; and
a charge sensing structure comprising:
a capacitor with a first electrode, connected to a contact on a surface of the charge-sensing structure, and a second electrode connected to ground; and
a sensing transistor,
wherein a contact on the X-ray sensing substrate is aligned and bonded to the contact on the surface of the charge sensing structure,
wherein beams of X-ray incident on the photoconductor is converted into electron-hole pairs drifting to the pixel electrode and altering a charge on a pre-charged electrode of the capacitor of the charge sensing structure, and
wherein the transistor and supporting circuits in the charge sensing structure convert the charge into a signal voltage.
2 . The direct X-ray sensor of claim 1 , wherein the photoconductor comprises a single-crystal semiconductor.
3 . The direct X-ray sensor of claim 2 , wherein the photoconductor comprises silicon, selenium, or CdTe.
4 . The direct X-ray sensor of claim 1 , wherein the pixel electrode is implanted with n dopants.
5 . The direct X-ray sensor of claim 4 , wherein the pixel electrode forms a part of a PN junction of a PN diode.
6 . The direct X-ray sensor of claim 5 , wherein the PN diode is reverse biased with a depletion layer near the pixel electrode.
7 . The direct X-ray sensor of claim 1 , wherein a Schottky diode is formed in the photoconductor with the pixel electrode comprising metal.
8 . The direct X-ray sensor of claim 7 , wherein the metal comprises platinum.
9 . The direct X-ray sensor of claim 7 , wherein the metal is pre-charged, and wherein beams of X-ray incident on the photoconductor generate electrons to discharge the pixel electrode proportional to an intensity of X-ray.
10 . A direct X-ray sensor, comprising:
a direct X-ray sensing substrate comprising:
a photoconductor with a common electrode on a first side of the photoconductor;
a PN junction on a second side of the photoconductor; and
a contact on a surface of a wafer of the substrate connected to the PN junction on the second side of the photoconductor such that a voltage applied to the common electrode and a side of the PN junction close to the contact on the photoconductor creates an electric field in the photoconductor; and
a charge sensing structure comprising:
a capacitor with a first electrode, connected to a contact on a surface of the charge sensing structure, and a second electrode connected to ground; and
a sensing transistor,
wherein the contact on the X-ray sensing substrate is aligned and bonded to the contact on the surface of charge sensing structure;
wherein beams of X-ray incident on the photoconductor is converted into electron-hole pairs drifting to the PN junction and altering a charge on a pre-charged electrode of the capacitor of the charge sensing structure, and
wherein the transistor and supporting circuits of the charge sensing structure convert the charge into a signal voltage.
11 . The direct X-ray sensor of claim 10 , wherein the photoconductor comprises a single-crystal semiconductor.
12 . The direct X-ray sensor of claim 11 , wherein the photoconductor comprises silicon, selenium, or CdTe.
13 . The direct X-ray sensor of claim 10 , wherein the second side of the photoconductor comprises a pixel electrode as a part of the PN junction and implanted with n dopants.
14 . The direct X-ray sensor of claim 13 , wherein the PN junction is reverse biased with a depletion layer near the pixel electrode.
15 . The direct X-ray sensor of claim 10 , wherein a Schottky diode is formed in the photoconductor with the second side of the photoconductor comprising metal.
16 . The direct X-ray sensor of claim 15 , wherein the metal comprises platinum.
17 . The direct X-ray sensor of claim 16 , wherein the metal is pre-charged, and wherein beams of X-ray incident on the photoconductor generate electrons to discharge the pixel electrode proportional to an intensity of X-ray.
18 . A direct X-ray sensor, comprising:
a direct X-ray sensing substrate comprising:
a photoconductor with a common electrode on a first side of the photoconductor;
a Schottky junction on a second side of the photoconductor; and
a contact on a surface of a wafer of the substrate connected to the Schottky junction on the second side of the photoconductor such that a voltage applied to the common electrode and one side of the Schottky junction close to the contact on the photoconductor creates an electric field in the photoconductor; and
a charge sensing structure comprising:
a capacitor with a first electrode connected to a contact on a surface of the charge sensing structure; a sensing transistor; and
a second electrode connected to ground,
wherein the contact on the X-ray sensing substrate is aligned and bonded to the contact on the surface of the charge sensing structure;
wherein beams of X-ray incident on the photoconductor are converted into electron-hole pairs drifting to the Schottky junction and altering a charge on a pre-charged electrode of the capacitor of the charge sensing structure, and
wherein the transistor and supporting circuits of the charge sensing structure convert the charge into a signal voltage.
19 . The direct X-ray sensor of claim 18 , wherein the photoconductor comprises a single-crystal semiconductor.
20 . The direct X-ray sensor of claim 19 , wherein the photoconductor comprises silicon, selenium, or CdTe.
21 . The direct X-ray sensor of claim 18 , wherein the second side of the photoconductor comprises metal.
22 . The direct X-ray sensor of claim 21 , wherein the metal comprises platinum.
23 . The direct X-ray sensor of claim 21 , wherein the metal is pre-charged, and wherein beams of X-ray incident on the photoconductor generate electrons to discharge the pixel electrode proportional to an intensity of X-ray.