Electromagnetic radiation detector comprising charge transport across a bonded interface
AssigneeG-ray Switzerland SA
InventorHans VON KÄNEL
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Abstract
Monolithic CMOS integrated pixel detector (10, 20, 30, 260, 470, 570), and systems and methods are provided for the detection and imaging of electromagnetic radiation with high spectral and spatial resolution. Such detectors comprise a Si wafer with a CMOS processed readout bonded to an absorber wafer in an electrically conducting covalent wafer bond. The pixel detectors, systems and methods are used in various medical and non-medical types of applications.
Claims45
A monolithic CMOS integrated pixel detector (10, 20, 30, 260, 470, 570) for the detection of electromagnetic radiation, comprising
- a. a silicon readout wafer (11, 21, 31, 41, 120, 130, 165, 215, 415, 515) with at least one layer (127, 167, 217, 417, 517) doped to have a first conduction type, the layer comprising CMOS processed readout electronics;
- b. implants for charge collectors (15, 25, 35, 45, 123, 223, 423, 523) doped to have the first conduction type, the implants communicating with the readout electronics and defining detector pixels;
- c. an absorber wafer (16, 26, 36, 46, 220, 481, 541′) made from material comprising at least a second conduction type and a metallic back contact (19, 29, 39, 49, 262, 472, 572);
- and,
- d. contact pads (124, 254, 464, 564) communicating with an external printed circuit board;
- wherein the silicon wafer and the absorber wafer are covalently bonded to form a monolithic unit;
- and wherein the monolithic unit comprises a p-n junction formed by a layer of the first conduction type and a layer of the second conduction type;
- and wherein charge collectors are disposed to receive the electrical charges crossing the bonded interface;
- and wherein registered charges are processed by a processor typically for diagnostic purposes.
The monolithic CMOS integrated pixel detector of any of the above claims, wherein the p-n junction (18) is located at the bonded interface (17, 27, 37, 237, 437, 537).
The monolithic CMOS integrated pixel detector of any of the above claims, wherein the pixel size is defined by the spacing of the implants for charge collectors.
A method for forming a monolithic CMOS integrated pixel detector for the detection of electromagnetic radiation, the method comprising the steps of:
- a. providing a silicon wafer comprising at least one doped Si layer (117, 127, 167, 217, 417, 517) doped to have a first conduction type;
- b. forming a readout wafer (120, 215, 415, 515) with a field oxide (125, 216, 416, 516) by CMOS processing a readout electronics in the at least one doped Si layer (117, 127, 167, 217, 417, 517);
- c. forming implants for charge collectors (15, 25, 35, 45, 123, 223, 423, 523) doped to have the first conduction type, the implants communicating with the readout electronics and defining detector pixels;
- d. forming contact pads (124, 254, 464, 564) to connect the readout electronics to a printed circuit board of the outside world;
- e. providing an absorber wafer (16, 26, 36, 46, 220, 381, 481, 541′) comprising at least a layer of a second conduction type;
- f. forming a low-temperature covalent bond (17, 27, 37, 47, 237, 437, 537) between the readout wafer and the absorber wafer;
- g. forming a metallic back contact (262, 472, 572) on the surface (221, 442, 543) of the absorber wafer (220, 481, 541′);
- wherein the layers of the first conduction type and the layers of the second conduction type are disposed to form a p-n junction, the depletion region of which extends across the bonding interface (17, 27, 37, 47, 237, 437, 537) when a reverse bias is applied to the metallic back contact, thereby separating electron-hole pairs into charges travelling in opposite directions when generated by electromagnetic radiation absorbed in the absorber wafer;
- and wherein the charge collectors are disposed to receive the electrical charges crossing the bonded interface;
- and wherein the readout electronics is disposed to convert said electrical charges into digital signals which can be transmitted through contact pads (124, 254, 464, 564) to an external printed circuit board and further stored, processed and displayed as images on a computer screen.
Dependencies are inferred from the claim text.