Silicon-based photomultiplier
By setting electrode areas on both sides of shallow trench isolation of the silicon-based photomultiplier tube and setting quenching resistors on the top of the isolation, the problem of limited cost and photon detection efficiency of existing silicon-based photomultiplier tubes is solved, and area savings, integration improvements and cost reductions are achieved.
Patent Information
- Application Number
- CN202311196022.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-15
- Publication Date
- 2025-03-25
AI Technical Summary
The cost and photon detection efficiency of existing silicon-based photomultiplier tubes are limited by the quenching resistors and electrodes occupied by additional area.
The Geiger mode avalanche photodiode is formed by providing the first and second electrode regions on both sides of the shallow trench isolation of the silicon substrate and a quenching resistor on the isolated top surface, reducing the extra area occupation.
Area savings, integration improvements, cost reductions and photon detection efficiency improvements have been achieved.
Smart Images
Figure CN119698084A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a semiconductor integrated circuit, in particular to a silicon-based photomultiplier tube (silicon photomultiplier, SiPM). Background Art
[0002] There is a huge demand for photomultiplier tubes. Compared with traditional photomultiplier tubes (PMTs), silicon-based photomultiplier tubes are cheaper, more integrated, and more competitive in the market.
[0003] In existing silicon-based photomultiplier tubes, an electrode is usually set on the front and back sides of the silicon substrate, and the quenching resistor needs to occupy additional area. All of these limit the cost and photon detection efficiency of existing silicon-based photomultiplier tubes. Summary of the invention
[0004] The technical problem to be solved by the present invention is to provide a silicon-based photomultiplier tube, which can save area, improve integration, reduce costs, and improve photon detection efficiency.
[0005] In order to solve the above technical problems, the unit structure of the silicon-based photomultiplier tube provided by the present invention includes:
[0006] Silicon substrate.
[0007] Shallow trench isolation is formed on the silicon substrate.
[0008] A first electrode region heavily doped with a first conductivity type is located on the surface of the silicon substrate at a first side of the shallow trench isolation.
[0009] A second electrode region heavily doped with a second conductivity type is located on the surface of the silicon substrate at the second side of the shallow trench isolation.
[0010] A quench resistor is located on the top surface of the shallow trench isolation.
[0011] A photosensitive layer is formed in the silicon substrate at the bottom of the first electrode region.
[0012] The first electrode region, the photosensitive layer and the second electrode region form a Geiger mode avalanche photodiode.
[0013] The first end of the quenching resistor is connected to the first electrode region through a first metal interconnection structure.
[0014] The second end of the quenching resistor is connected to the first electrode.
[0015] The second electrode region is connected to the second electrode.
[0016] The first electrode and the second electrode are both located on the front side of the silicon substrate, and photons enter the photosensitive layer from the front side of the first electrode region to realize photosensitization.
[0017] A further improvement is that a silicon epitaxial layer is also formed on the silicon substrate, and the photosensitive layer, the first electrode region, the shallow trench isolation and the second electrode region are all formed in the silicon epitaxial layer.
[0018] A further improvement is that the photosensitive layer includes a deep photodiode region of the first conductivity type.
[0019] The first electrode region is located in a surface region of the deep photodiode region.
[0020] The deep photodiode region is located in a deep well region of the second conductivity type.
[0021] A unit well region of the second conductivity type is located in the deep well region, and the second electrode region is located in a surface region of the unit well region.
[0022] The deep photodiode region and the unit well region are in contact with or have a spacing at the side of the bottom of the shallow trench isolation.
[0023] A further improvement is that the first conductivity type is N type and the second conductivity type is P type; or the first conductivity type is P type and the second conductivity type is N type.
[0024] A further improvement is that the quenching resistor is composed of a polysilicon resistor.
[0025] A further improvement is that the first metal interconnect structure includes a first contact hole formed at the top of the first end of the quenching resistor, a second contact hole formed at the top of the first electrode region, and a first metal wire connecting the first contact hole and the second contact hole.
[0026] A further improvement is that the deep photodiode region, the deep well region and the unit well region are all formed by ion implantation.
[0027] A further improvement is that the silicon-based photomultiplier tube is formed by connecting a plurality of the unit structures in parallel.
[0028] The first electrodes of the unit structures are connected together and the second electrodes of the unit structures are connected together.
[0029] A further improvement is that the voltage between the first electrode and the second electrode is tens of volts.
[0030] A further improvement is that the number of the unit structures connected in parallel in the silicon-based photomultiplier tube is from tens to tens of thousands.
[0031] A further improvement is that the magnitude of the quenching resistor is in the range of tens of Ω to thousands of Ω.
[0032] The present invention makes a special arrangement for the unit structure of the silicon-based photomultiplier tube by arranging the first electrode region and the second electrode region on both sides of the shallow trench isolation and arranging the quenching resistor on the top surface of the shallow trench isolation. Since the quenching resistor is located on the top surface of the shallow trench isolation, the quenching resistor does not need to occupy additional chip area, thereby saving area, improving integration and reducing costs.
[0033] In the present invention, the photosensitive layer is located in the bottom region directly below the first electrode region, and the photosensitive area can be changed by controlling the size of the first electrode region, thereby controlling the photon detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:
[0035] Figure 1 is a schematic diagram of a unit structure of a silicon-based photomultiplier tube according to an embodiment of the present invention;
[0036] Figure 2 is a circuit diagram of a silicon-based photomultiplier tube according to an embodiment of the present invention;
[0037] Figure 3 It is a schematic diagram of the unit structure of a silicon-based photomultiplier tube according to a preferred embodiment of the present invention. DETAILED DESCRIPTION
[0038] like Figure 1 , which is a schematic diagram of a unit structure of a silicon-based photomultiplier tube according to an embodiment of the present invention; Figure 2 , which is a circuit diagram of a silicon-based photomultiplier tube according to an embodiment of the present invention; a unit structure 202 of a silicon-based photomultiplier tube according to an embodiment of the present invention includes:
[0039] Silicon substrate 203.
[0040] A shallow trench isolation 102 is formed on the silicon substrate 203 .
[0041] A first electrode region 104 heavily doped with a first conductivity type is located on the surface of the silicon substrate 203 at the first side of the shallow trench isolation 102 .
[0042] A second electrode region 105 heavily doped with the second conductivity type is located on the surface of the silicon substrate 203 at the second side of the shallow trench isolation 102 .
[0043] A quenching resistor 103 is located on the top surface of the shallow trench isolation 102 .
[0044] In the embodiment of the present invention, the quenching resistor 103 is composed of a polysilicon resistor.
[0045] A photosensitive layer is formed in the silicon substrate 203 at the bottom of the first electrode region 104 .
[0046] The first electrode region 104, the photosensitive layer and the second electrode region 105 form a Geiger mode avalanche photodiode 204. The circuit structure of the Geiger mode avalanche photodiode 204 is shown in FIG. Figure 2 shown. Figure 1 In the embodiment, the photosensitive layer is a portion of the depletion layer 101 located between the first electrode region 104 and the second electrode region 105 , that is, a portion located directly below the first electrode region 104 .
[0047] The first end of the quenching resistor 103 is connected to the first electrode region 104 via a first metal interconnection structure.
[0048] In the embodiment of the present invention, the first metal interconnection structure includes a first contact hole 106c formed at the top of the first end of the quenching resistor 103, a second contact hole 106d formed at the top of the first electrode region 104, and a first metal line 107c connecting the first contact hole 106c and the second contact hole 106d. The first metal line 107c is formed by patterning the front metal layer.
[0049] The second end of the quenching resistor 103 is connected to the first electrode 107 a .
[0050] In the embodiment of the present invention, the second end of the quenching resistor 103 is connected to the first electrode 107a through a contact hole 106a at the top, and the first electrode 107a is formed by patterning the front metal layer.
[0051] The second electrode region 105 is connected to the second electrode 107 b .
[0052] In the embodiment of the present invention, the second electrode region 105 is connected to the second electrode 107b through a contact hole 106b at the top, and the second electrode 107b is formed by patterning the front metal layer.
[0053] The first electrode 107a and the second electrode 107b are both located on the front side of the silicon substrate 203, and photons enter the photosensitive layer from the front side of the first electrode region 104 to realize photosensitization.
[0054] In the embodiment of the present invention, a silicon epitaxial layer is further formed on the silicon substrate 203 , and the photosensitive layer, the first electrode region 104 , the shallow trench isolation 102 and the second electrode region 105 are all formed in the silicon epitaxial layer. Figure 1 The regions shown in FIG. 1 are all within the thickness range of the silicon epitaxial layer.
[0055] like Figure 2 As shown, in the embodiment of the present invention, the silicon-based photomultiplier tube 201 is formed by connecting a plurality of the unit structures 202 in parallel.
[0056] The first electrodes 107 a of the unit structures 202 are connected together and the second electrodes 107 b of the unit structures 202 are connected together.
[0057] The voltage between the first electrode 107a and the second electrode 107b is several tens of volts.
[0058] The number of the unit structures 202 connected in parallel in the silicon-based photomultiplier tube 201 is from tens to tens of thousands.
[0059] The magnitude of the quenching resistor 103 is in the range of tens of Ω to thousands of Ω.
[0060] In the embodiment of the present invention, the first conductivity type is N type, and the second conductivity type is P type. In other embodiments, the first conductivity type may be P type, and the second conductivity type may be N type.
[0061] The embodiment of the present invention makes a special arrangement for the unit structure 202 of the silicon-based photomultiplier tube 201, by arranging the first electrode region 104 and the second electrode region 105 on both sides of the shallow trench isolation 102 and arranging the quenching resistor 103 on the top surface of the shallow trench isolation 102. Since the quenching resistor 103 is located on the top surface of the shallow trench isolation 102, the quenching resistor 103 does not need to occupy additional chip area, thereby saving area, improving integration and reducing costs.
[0062] In the embodiment of the present invention, the photosensitive layer is located in the bottom region directly below the first electrode region 104 , and the photosensitive area can be changed by controlling the size of the first electrode region 104 , thereby controlling the photon detection efficiency.
[0063] like Figure 3 , which is a schematic diagram of a unit structure 202a of a silicon-based photomultiplier tube according to a preferred embodiment of the present invention; in a preferred embodiment of the present invention, the photosensitive layer includes a deep photodiode region 101a of a first conductivity type.
[0064] The first electrode region 104 is located in the surface area of the deep photodiode region 101 a .
[0065] The deep photodiode region 101 a is located in a deep well region 101 c of the second conductivity type.
[0066] The second conductivity type unit well region 101 b is located in the deep well region 101 c , and the second electrode region 105 is located in the surface region of the unit well region 101 b .
[0067] Figure 2 In the embodiment, the depletion layer 101 between the first electrode region 104 and the second electrode region 105 is composed of the deep photodiode region 101a, the unit well region 101b and the deep well region 101c, and only the deep photodiode region 101a is used for photosensitivity.
[0068] When the first conductivity type is N type and the second conductivity type is P type, the N type deep photodiode region 101a is abbreviated as DNPPD, the P type deep well region 101c is abbreviated as DPW, and the P type cell well region 101b is abbreviated as CPW.
[0069] The deep photodiode region 101 a and the unit well region 101 b are in contact with each other at the bottom side of the shallow trench isolation 102 or have a gap therebetween.
[0070] The deep photodiode region 101 a , the deep well region 101 c , and the unit well region 101 b are all formed by ion implantation.
[0071] The present invention has been described in detail above through specific embodiments, but these do not constitute limitations of the present invention. Without departing from the principle of the present invention, those skilled in the art may also make many variations and improvements, which should also be considered as the protection scope of the present invention.
Claims
1. A silicon-based photomultiplier tube, characterized in that: The unit structure includes: Silicon substrate; shallow trench isolation formed on the silicon substrate; A first electrode region heavily doped with a first conductivity type located on the surface of the silicon substrate on a first side of the shallow trench isolation; A second electrode region heavily doped with a second conductivity type located on the surface of the silicon substrate at a second side of the shallow trench isolation; a quenching resistor located on a top surface of the shallow trench isolation; A photosensitive layer is formed in the silicon substrate at the bottom of the first electrode region; The first electrode region, the photosensitive layer and the second electrode region form a Geiger mode avalanche photodiode; The first end of the quenching resistor is connected to the first electrode region through a first metal interconnection structure; The second end of the quenching resistor is connected to the first electrode; The second electrode region is connected to a second electrode; The first electrode and the second electrode are both located on the front side of the silicon substrate, and photons enter the photosensitive layer from the front side of the first electrode region to realize photosensitization.
2. The silicon-based photomultiplier tube according to claim 1, characterized in that: A silicon epitaxial layer is also formed on the silicon substrate, and the photosensitive layer, the first electrode region, the shallow trench isolation and the second electrode region are all formed in the silicon epitaxial layer.
3. The silicon-based photomultiplier tube according to claim 2, characterized in that: The photosensitive layer includes a deep photodiode region of a first conductivity type; The first electrode region is located in a surface region of the deep photodiode region; The deep photodiode region is located in a deep well region of the second conductivity type; A unit well region of the second conductivity type is located in the deep well region, and the second electrode region is located in the surface region of the unit well region; The deep photodiode region and the unit well region are in contact with or have a spacing at the side of the bottom of the shallow trench isolation.
4. The silicon-based photomultiplier tube according to claim 3, characterized in that: The first conductivity type is N type, and the second conductivity type is P type; or, the first conductivity type is P type, and the second conductivity type is N type.
5. The silicon-based photomultiplier tube according to claim 1, characterized in that: The quenching resistor is composed of a polysilicon resistor.
6. The silicon-based photomultiplier tube according to claim 1, characterized in that: The first metal interconnection structure includes a first contact hole formed at the top of the first end of the quenching resistor, a second contact hole formed at the top of the first electrode region, and a first metal line connecting the first contact hole and the second contact hole.
7. The silicon-based photomultiplier tube according to claim 3, characterized in that: The deep photodiode region, the deep well region and the unit well region are all formed by ion implantation.
8. The silicon-based photomultiplier tube according to claim 4, characterized in that: The silicon-based photomultiplier tube is formed by connecting a plurality of the unit structures in parallel; The first electrodes of the unit structures are connected together and the second electrodes of the unit structures are connected together.
9. The silicon-based photomultiplier tube according to claim 8, characterized in that: The voltage between the first electrode and the second electrode is several tens of volts.
10. The silicon-based photomultiplier tube according to claim 8, characterized in that: The number of the unit structures connected in parallel in the silicon-based photomultiplier tube is from tens to tens of thousands.
11. The silicon-based photomultiplier tube according to claim 8, characterized in that: The quenching resistor has a value ranging from tens of Ω to thousands of Ω.