Single photon Si-APD detector and manufacturing method thereof

文档序号：1615953 发布日期：2020-01-10 浏览：22次中文

阅读说明：本技术 一种单光子Si-APD探测器及其制造方法 (Single photon Si-APD detector and manufacturing method thereof ) 是由郭安然雷仁方李睿智高建威向华兵于 2019-10-10 设计创作，主要内容包括：本发明提出了一种单光子Si-APD探测器,包括：吸收区、P+接触区、N+接触区、雪崩区、介质层,所述P型衬底表面中部设置吸收区,所述吸收区下方设置P+接触区,所述P+接触区下方设置有下电极；所述吸收区上部的两端位置设置有截止环；所述吸收区的上部的中间位置设置雪崩区,且雪崩区由P型杂质和N型杂质补偿掺杂形成；所述雪崩区之上设置N+接触区；所述雪崩区两侧各设有一个保护环,所述保护环上方设置有上电极；所述N+接触区上方设置介质层。该单光子Si-APD探测器具有较宽的雪崩区且制造过程引入缺陷很少,可实现高探测效率低暗计数的器件性能。(The invention provides a single photon Si-APD detector, which comprises: the semiconductor device comprises an absorption region, a P + contact region, an N + contact region, an avalanche region and a dielectric layer, wherein the absorption region is arranged in the middle of the surface of a P-type substrate, the P + contact region is arranged below the absorption region, and a lower electrode is arranged below the P + contact region; stopping rings are arranged at the two ends of the upper part of the absorption area; an avalanche region is arranged in the middle of the upper part of the absorption region and is formed by compensating doping of P-type impurities and N-type impurities; an N + contact region is arranged above the avalanche region; two sides of the avalanche region are respectively provided with a protective ring, and an upper electrode is arranged above the protective rings; and a dielectric layer is arranged above the N + contact region. The single photon Si-APD detector has a wider avalanche region, few defects are introduced in the manufacturing process, and the device performance with high detection efficiency and low dark count can be realized.)

1. A single photon Si-APD detector comprising: p-type substrate, absorption region, P⁺Contact region, N⁺A contact region, an avalanche region and a dielectric layer, wherein an absorption region is arranged in the middle of the surface of the P-type substrate, and a P is arranged below the absorption region⁺Contact region of the P⁺A lower electrode is arranged below the contact area; stopping rings are arranged at the two ends of the upper part of the absorption area; an avalanche region is arranged in the middle of the upper part of the absorption region and is formed by compensating doping of P-type impurities and N-type impurities; n is arranged above the avalanche region⁺A contact zone; two sides of the avalanche region are respectively provided with a protective ring, and an upper electrode is arranged above the protective rings; said N is⁺A dielectric layer is disposed over the contact region.

2. The single photon Si-APD detector of claim 1 in which the P-type and N-type impurities of the compensation doping avalanche region are formed by ion implantation and high temperature re-diffusion; the implantation dosage of the P-type impurity is larger than that of the N-type impurity, the diffusion depth of the P-type impurity is larger than that of the N-type impurity, an impurity peak with the peak concentration in the device and the net doping concentration of the P-type impurity is formed, and the net doping peak concentration range is 5E15cm^-3-1E17cm^-3The net doping peak depth range is 0.5 μm to 3 μm.

3. The single photon Si-APD detector of claim 1 wherein said absorption region is lightly doped intrinsic or P-type with bulk concentration ≤ 5E15cm^-3。

4. A single photon Si-APD detector as claimed in claim 1 in which the guard rings are formed by N-type doping and have a bulk concentration in the range 5E15cm^-3-5E17cm^-3。

5. A single photon Si-APD detector as claimed in claim 1 in which the stop ring is formed by heavy P-type doping with a bulk concentration in the range 1E18cm^-3-1E20cm^-3。

6. A single photon Si-APD detector as claimed in claim 1 in which the P-type impurity is elemental boron and/or elemental gallium.

7. A single photon Si-APD detector as claimed in claim 1 in which the N-type impurity is elemental phosphorus and/or elemental arsenic.

8. The single photon Si-APD detector of claim 1 in which the P-type substrate is an epitaxial or monocrystalline silicon wafer.

9. A method of manufacturing single photon Si-APD detectors according to any of claims 1 to 4 comprising the steps of:

(1) growing an oxidation medium layer by adopting a clean P-type substrate;

(2) forming a stop ring pattern by photoetching and etching the dielectric layer, and injecting boron element into the stop ring pattern to form a stop ring;

(3) forming a protective ring pattern by photoetching and etching the dielectric layer, and injecting a proper amount of phosphorus element into the protective ring pattern to form a protective ring;

(4) and (3) avalanche region P-shaped impurity implantation: forming an avalanche region pattern by photoetching and etching the dielectric layer, injecting a proper amount of boron element and/or gallium element into one side of the avalanche region, and diffusing the boron element and/or the gallium element into the silicon wafer by a high-temperature process;

(5) and (3) avalanche region N-shaped impurity implantation: injecting a proper amount of phosphorus and/or arsenic to the other side of the avalanche region, and diffusing the phosphorus and/or arsenic into the silicon wafer through a high-temperature process so as to be doped with boron complementarily;

(6) forming N by photoetching and etching the dielectric layer⁺Patterning the contact region and forming N by implanting phosphorus element⁺A contact zone;

(7) depositing metal aluminum above the substrate, and forming an upper electrode by photoetching and etching;

(8) the metal aluminum is formed under the substrate to form the bottom electrode.

10. The manufacturing method of claim 9, wherein the substrate resistivity of the P-type epitaxial silicon wafer is 0.01 Ω cm to 0.05 Ω cm, and the epitaxial layer resistivity is equal to or greater than 100 Ω cm.

Technical Field

The invention relates to the field of photoelectric detector chips, in particular to a single photon Si-APD detector and a manufacturing method thereof.

Background

Single photon detection is used as a detection technology of extremely weak light signals, has wide application prospects in the fields of quantum communication, astronomical photometry, medical imaging, radar detection and the like, and becomes one of hot spots in the current photoelectric detection field in view of huge scientific research value and strategic position. The single-photon detector is used as a core component of the detection system and determines performance parameters of the whole single-photon detection system, so that the design of the single-photon detector with high detection efficiency and low dark count is one of the key problems which are urgently needed to be solved at present.

A single photon silicon avalanche diode Si-APD is a special photodiode operating in Geiger mode with about 10⁶The single photon detection can be realized by the internal gain of magnitude. Detection efficiency and dark count are the most important performance indexes of single photon Si-APD. The detection efficiency represents the probability of the device generating an avalanche current signal when receiving a photon, and is equal to the quantum efficiency multiplied by the avalanche probability. The dark count represents the frequency at which the device generates an avalanche current signal in the absence of light, and is primarily affected by internal defects in the device. The structure and preparation method of the avalanche region of the Si-APD are crucial to the detection efficiency and dark count. The traditional preparation method of the avalanche region comprises diffusion and high-energy implantation. The width of the avalanche region prepared by the diffusion method is very narrow, and the avalanche region is required to have higher electric field intensity when the device works to reach high avalanche probability, as shown in fig. 5, and the higher electric field intensity causes band-to-band tunneling and defect-assisted tunneling, so that the dark count is increased. The avalanche region prepared by the high-energy implantation method has wider width and lower electric field intensity of the avalanche region, as shown in fig. 6, but the bombardment of the silicon wafer by high-energy impurity ions in the high-energy implantation can damage silicon lattices, cause defects and also increase dark counts.

Disclosure of Invention

In order to solve the problems, the invention provides a single photon Si-APD detector with high detection efficiency and low dark count and a manufacturing method thereof.

A single photon Si-APD detector comprising: p-type substrate, absorption region, P⁺Contact region, N⁺Contact region, avalancheThe middle part of the surface of the P-type substrate is provided with an absorption region, and a P is arranged below the absorption region⁺Contact region of the P⁺A lower electrode is arranged below the contact area; stopping rings are arranged at the two ends of the upper part of the absorption area; an avalanche region is arranged in the middle of the upper part of the absorption region and is formed by compensating doping of P-type impurities and N-type impurities; n is arranged above the avalanche region⁺A contact zone; two sides of the avalanche region are respectively provided with a protective ring, and an upper electrode is arranged above the protective rings; said N is⁺A dielectric layer is disposed over the contact region.

Furthermore, the P-type impurity and the N-type impurity of the compensation doping avalanche region are formed through ion implantation and high-temperature re-diffusion, the implantation dosage of the P-type impurity is larger than that of the N-type impurity, the diffusion depth of the P-type impurity is larger than that of the N-type impurity, so that a peak value concentration is formed in the device, the net doping concentration is a P-type impurity peak, and the net doping peak value concentration range is 5E15cm^-3-1E17cm^-3The net doping peak depth range is 0.5 μm to 3 μm.

Furthermore, the absorption region is used for absorbing incident photons to generate current carriers, intrinsic or P-type light doping is arranged in the absorption region, and the bulk concentration of the absorption region is less than or equal to 5E15cm^-3。

Further, the guard ring is formed by N-type doping, and the body concentration range of the guard ring is 5E15cm^-3-5E17cm^-3And the guard ring functions to prevent the avalanche region from edge breakdown ahead of time.

Further, the stop ring is formed by heavily doping P type, and the concentration range of the body of the stop ring is 1E18cm^-3-1E20cm^-3And the function of the cutoff ring is to suppress the dark current of the device.

Further, the P-type impurity is boron and/or gallium.

Further, the N-type impurity is phosphorus and/or arsenic.

Furthermore, the P-type substrate is an epitaxial silicon wafer or a monocrystalline silicon wafer.

A method of manufacturing the single photon Si-APD detector comprising the steps of:

(1) growing an oxidation medium layer by adopting a clean P-type substrate;

(2) forming a stop ring pattern by photoetching and etching the dielectric layer, and injecting boron element into the stop ring pattern to form a stop ring;

(3) forming a protective ring pattern by photoetching and etching the dielectric layer, and injecting a proper amount of phosphorus element into the protective ring pattern to form a protective ring;

(6) forming N by photoetching and etching the dielectric layer⁺Patterning the contact region and forming N by implanting phosphorus element⁺A contact zone;

(7) depositing metal aluminum on the front surface, and forming an upper electrode by photoetching and etching;

(8) and depositing metal aluminum on the back surface to form a lower electrode.

Furthermore, the substrate resistivity of the P-type epitaxial silicon wafer is 0.01-0.05 omega cm, and the epitaxial layer resistivity is more than or equal to 100 omega cm.

The invention has the beneficial effects that:

1. the single photon Si-APD detector has novel structure: the invention is provided with an absorption region, an avalanche region, a P + contact region, an N + contact region, a dielectric layer, a protection ring and a stop ring in a P-type substrate, and has great breakthrough in structure.

2. The single photon Si-APD detector has the advantages of high detection efficiency and low dark count; the avalanche region is formed by compensating doping of P-type impurities and N-type impurities, which are formed by ion implantation and high temperature re-diffusion. Wherein the implantation dosage of the P-type impurity is greater than that of the N-type impurity, and the diffusion depth of the P-type impurity is greater than that of the N-type impuritySo as to form an impurity peak with the peak concentration in the device, the net doping concentration is P type, and the net doping peak concentration range is 5E15cm^-3～1E17cm^-3The depth range of the net doping peak value is 0.5-3 mu m. The single photon Si-APD detector manufactured in the way has wider avalanche region width, the electric field intensity of the avalanche region required by the device to reach high avalanche probability is relatively lower, band-to-band tunneling and defect-assisted tunneling cannot be caused, and the detection efficiency can be improved; and moreover, the avalanche region is manufactured by adopting a diffusion process instead of high-energy injection, so that the defects caused by damage to silicon lattices are avoided. The photon detection efficiency of the device exceeds 70% at the temperature of 243K, and meanwhile, the dark count is less than 1kcps, which belongs to the international first-class level.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a cross-sectional view of a single photon Si-APD structure according to an embodiment of the present invention;

FIG. 2 is a graph of an avalanche region impurity concentration profile for an embodiment of the present invention;

FIG. 3 is a flow chart of a single photon Si-APD process fabrication according to an embodiment of the present invention;

FIG. 4 is a flow chart of another single photon Si-APD process fabrication of an embodiment of the present invention;

FIG. 5 is a prior art Si-APD doping concentration and electric field;

FIG. 6 is another prior art Si-APD doping concentration and electric field;

fig. 7 is a graph showing the result of the avalanche region impurity concentration distribution test according to the embodiment of the present invention;

FIG. 8 is a graph of the detection efficiency and dark count test results for single photon Si-APDs in accordance with an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, a single photon Si-APD detector includes: p-type substrate, absorption region, P⁺Contact region, N⁺A contact region, an avalanche region, a dielectric layer, an absorption region arranged at the middle part of the surface of the P-type substrate, and a P arranged below the absorption region⁺Contact region of the P⁺A lower electrode is arranged below the contact area; stopping rings are arranged at the two ends of the upper part of the absorption area; an avalanche region is arranged in the middle of the upper part of the absorption region and is formed by compensating doping of P-type impurities and N-type impurities; n is arranged above the avalanche region⁺A contact zone; two sides of the avalanche region are respectively provided with a protective ring, and an upper electrode is arranged above the protective rings; said N is⁺A dielectric layer is disposed over the contact region.

Further, the avalanche region is formed by compensating doping of a P-type impurity and an N-type impurity. The P-type impurity and the N-type impurity are formed by ion implantation and high-temperature re-diffusion. The implantation dosage of the P-type impurity is larger than that of the N-type impurity, the diffusion depth of the P-type impurity is larger than that of the N-type impurity, so that a peak concentration is formed in the device instead of on the surface, the net doping concentration is a P-type impurity peak, and the net doping peak concentration range is 5E15cm^-3-1E17cm^-3The net doping peak depth ranges from 0.5 μm to 3 μm, as shown in FIG. 2. The avalanche region of the single-photon Si-APD detector manufactured in the way is wide in width, the electric field intensity of the avalanche region required by the device to reach high avalanche probability is relatively low, and band-to-band tunneling and defect-assisted tunneling cannot be caused; and moreover, the avalanche region is manufactured by adopting a diffusion process instead of high-energy injection, so that the defects caused by damage to silicon lattices are avoided. Therefore, the single-photon Si-APD has the advantages of high detection efficiency and low dark count.

Furthermore, the absorption region is used for absorbing incident photons to generate current carriers, intrinsic or P-type light doping is adopted in the absorption region, and the bulk concentration of the absorption region is less than or equal to 5E15cm^-3。

Further, the guard ring functions to prevent an avalanche region from edge breakdown in advance, formed by N-type doping, with a bulk concentrationIn the range of 5E15cm^-3-5E17cm^-3。

Further, the stop ring has the function of inhibiting dark current of the device, is formed by P-type heavy doping, and has the body concentration range of 1E18cm^-3-1E20cm^-3。

Further, the P-type impurity is boron and/or gallium.

Further, the N-type impurity is phosphorus and/or arsenic.

Furthermore, the P-type substrate is an epitaxial silicon wafer or a monocrystalline silicon wafer.

As shown in FIG. 3, in one embodiment of the present invention, the specific process flow of the single photon Si-APD comprises:

(1) preparing a clean P-type epitaxial silicon wafer, wherein the resistivity of the P-type epitaxial silicon wafer is 0.01-0.05 omega cm, and the resistivity of an epitaxial layer is 100-150 omega cm;

(2) growing a silicon oxide medium layer;

(3) forming a stop ring pattern by photoetching and etching the dielectric layer, and implanting a high-dose boron element into the stop ring pattern to form a stop ring, wherein the concentration of the implanted boron element is 1E14cm^-2～1E15cm^-2；

(4) Forming a guard ring pattern by photoetching and etching the dielectric layer, and forming a guard ring by implanting a proper amount of phosphorus element into the guard ring pattern, wherein the concentration of the implanted phosphorus element is 2E12cm^-2～2E13cm^-2；

(5) And (3) avalanche region P-shaped impurity implantation: forming an avalanche region pattern by photoetching and etching the dielectric layer, injecting a proper amount of boron element and/or gallium element into one side of the avalanche region, and diffusing the boron element and/or the gallium element into the silicon wafer by adopting a high-temperature process of a high-temperature annealing furnace;

(6) and (3) avalanche region N-shaped impurity implantation: injecting a proper amount of phosphorus and/or arsenic to the other side of the avalanche region, and diffusing the phosphorus and/or arsenic into the silicon wafer through a high-temperature process so as to be doped with boron complementarily;

(7) forming N by photoetching and etching the dielectric layer⁺Patterning the contact region and forming N by implanting a high dose of phosphorus element⁺Contact withRegion, concentration of implanted phosphorus element is 1E14cm^-2～1E15cm^-2；

(8) Depositing metal aluminum on the front surface by a sputtering or thermal evaporation method, and forming an upper electrode by photoetching and etching;

(9) and depositing metal aluminum on the back surface to form a lower electrode.

Preferably, in embodiments of the invention, the cutoff ring concentration range is 1E18cm^-3～1E20cm^-3。

Preferably, in embodiments of the invention, the guard ring concentration range is 5E15cm^-3～5E17cm^-3。

Preferably, in the embodiment of the invention, the implantation dosage of the P-type impurity in the avalanche region is 4E 12-1E 13cm^-2。

Preferably, in the embodiment of the invention, the implantation energy of the P-type impurity in the avalanche region is 30 to 150 KeV.

Preferably, in the embodiment of the invention, the diffusion temperature of the P-type impurity in the avalanche region is 1100-1200 ℃.

Preferably, in the embodiment of the invention, the diffusion and diffusion time of the P-type impurity in the avalanche region is 2-20 hours.

Preferably, in the embodiment of the invention, the implantation dosage of the N-type impurity in the avalanche region is 2E 12-8E 12cm^-2。

Preferably, in the embodiment of the invention, the implantation energy of the N-type impurity in the avalanche region is 30 to 150 KeV.

Preferably, in the embodiment of the invention, the diffusion temperature of the N-type impurity in the avalanche region is 1100-1200 ℃.

Preferably, in the embodiment of the present invention, the diffusion and diffusion time of the N-type impurity in the avalanche region is 1 to 20 hours.

As shown in fig. 4, it is a specific process flow of a single photon Si-APD according to another embodiment of the present invention, and the specific steps include:

(1) preparing a clean P-type monocrystalline silicon wafer, wherein the resistivity of the clean P-type monocrystalline silicon wafer is more than or equal to 250 omega cm;

(2) growing a silicon oxide medium layer;

(3) forming a cut-off by photoetching and etching the dielectric layerRing pattern and forming a stop ring by high dose boron element implantation, wherein the concentration of implanted boron element is 1E14cm^-2～1E15cm^-2；

(4) Forming a guard ring pattern by photolithography and etching the dielectric layer, and forming a guard ring by implanting an appropriate amount of phosphorus element at a concentration of 2E12cm^-2～2E13cm^-2；

(6) and (3) avalanche region N-shaped impurity implantation: injecting a proper amount of phosphorus element and/or arsenic element into the other side of the avalanche region, and diffusing the phosphorus element and/or the arsenic element into the silicon wafer through a high-temperature process so as to form the avalanche region by being doped with the boron element and/or the gallium element in a complementary manner;

(7) forming N by photoetching and etching the dielectric layer⁺Patterning the contact region and forming N by high dose phosphorus implantation⁺Contact region in which phosphorus element is implanted at a concentration of 1E14cm^-2～1E15cm^-2；

(8) Depositing metal aluminum on the front surface, and forming an upper electrode by photoetching and etching;

(9) thinning the P-type monocrystalline silicon wafer from the back surface to a designed thickness by using mechanical grinding and wet etching;

(10) implanting a high dose of boron element under the absorption region to form P⁺Contact region in which the concentration of implanted boron element is 1E14cm^-2～1E15cm^-2；

(11) And depositing metal aluminum below the P + contact region by a sputtering or thermal evaporation method to form a lower electrode.

As shown in fig. 5, the avalanche region prepared by the simple diffusion method has a narrow width, and when the high photon detection efficiency is achieved, the peak electric field intensity of the avalanche region of the device is extremely high, so that valence band electrons directly transition to a conduction band to generate band-to-band tunneling, and the dark count is sharply increased.

As shown in fig. 6, although the avalanche region prepared by the high-energy implantation method has a wider width and a lower electric field strength, the high-energy impurity ions in the high-energy implantation bombard the silicon wafer to damage the silicon lattice, which causes defects and also increases the dark count.

FIG. 7 shows the result of the diffusion resistance process (SRP) measurement of the single-photon Si-APD avalanche region in another example, in which the impurity peak depth is 2.6 μm and the impurity peak concentration is 8E15cm^-3. The avalanche region is formed by compensating doping of N-type and P-type impurities and using a diffusion process, so that damage to silicon materials is reduced; meanwhile, the width of an avalanche region can be ensured to be wider due to the impurity distribution, the electric field intensity of the avalanche region is relatively low under the condition of high photon detection efficiency, and band-to-band tunneling cannot be caused. Thus, the dark count of the device is reduced.

FIG. 8 is a real graph of detection efficiency versus dark count at 850nm wavelength for a single photon Si-APD in another embodiment. At the temperature of 243K, the photon detection efficiency of the device exceeds 70 percent, and the dark count is less than 1kcps, which belongs to the international first-class level.