WO2023061235A1 - 基于选区离子注入的新型碳化硅基横向pn结极紫外探测器及制备方法 - Google Patents

基于选区离子注入的新型碳化硅基横向pn结极紫外探测器及制备方法 Download PDF

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WO2023061235A1
WO2023061235A1 PCT/CN2022/122521 CN2022122521W WO2023061235A1 WO 2023061235 A1 WO2023061235 A1 WO 2023061235A1 CN 2022122521 W CN2022122521 W CN 2022122521W WO 2023061235 A1 WO2023061235 A1 WO 2023061235A1
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epitaxial layer
doped epitaxial
ion implantation
low
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陆海
王致远
周东
徐尉宗
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南京大学
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    • H—ELECTRICITY
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    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
    • H01L31/103—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the PN homojunction type
    • H01L31/1037—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the PN homojunction type the devices comprising active layers formed only by AIVBVI compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H—ELECTRICITY
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    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0256—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
    • H01L31/0264—Inorganic materials
    • H01L31/0312—Inorganic materials including, apart from doping materials or other impurities, only AIVBIV compounds, e.g. SiC
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
    • H01L31/103—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the PN homojunction type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • H01L31/1812—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table including only AIVBIV alloys, e.g. SiGe
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the invention relates to a novel silicon carbide (SiC)-based lateral PN junction extreme ultraviolet (EUV) detector based on selective ion implantation and a preparation method thereof, belonging to the technical field of semiconductor device photodetection.
  • SiC silicon carbide
  • EUV extreme ultraviolet
  • EUV detection technology has broad application prospects in many scientific research and production fields such as integrated circuit lithography below 7nm process, plasma physics, astrophysics, high-energy physics, and satellite space environment monitoring. Extreme ultraviolet detection technology is mainly used to detect short-wavelength, high-energy ultraviolet light with a wavelength range between 10-200nm. It has the characteristics of shallow penetration depth and high photon energy. These special properties of EUV photons limit the development of EUV detectors, and this has become a key factor restricting the development of EUV detection technology. First of all, EUV photons have a large absorption coefficient in semiconductor materials such as silicon (Si), and the penetration depth is generally lower than 10nm.
  • Incident EUV photons are easily absorbed by non-active areas such as ohmic contact layers and passivation layers on the detector surface. , which leads to extremely low detection efficiency of the device; secondly, the energy of extreme ultraviolet photons is high, and the irradiation of high-energy photons leads to defect states in the device, which brings a series of additional effects such as heat accumulation and noise level rise, which leads to the detector The performance of the device is degraded; at the same time, the extreme ultraviolet detector needs to face the harsh working environment. Taking the extreme ultraviolet lithography as an example, the extreme ultraviolet detector as the core component needs to withstand the irradiation of high-energy photons with a cumulative intensity of up to 1MJ/ cm2 . The reliability and long-range stability of EUV detectors are challenged.
  • the detectors used in the conventional ultraviolet band generally cannot meet the requirements of long-term efficient and stable work in the extreme ultraviolet band.
  • Si-based detectors are limited by the narrow band gap, low critical displacement energy, and low thermal conductivity of Si materials, and have the defects of high noise level, poor radiation resistance, and poor temperature stability.
  • the wide bandgap semiconductor material 4H-SiC has the characteristics of large bandgap, high critical displacement energy, high thermal conductivity and good chemical stability, and has significant advantages in the preparation of photodetector devices working in the ultraviolet band. Material performance advantages.
  • SiC-based Schottky junction detectors are prone to positive electric vacancies under the irradiation of high-energy EUV photons, resulting in the height of the Schottky barrier due to the image force effect
  • the leakage current of the device is reduced, which in turn leads to an increase in the leakage current of the device; while the non-active region on the surface of the silicon carbide-based traditional structure PN junction detector forms a strong absorption of EUV photons, resulting in extremely low detection efficiency of the device in the EUV band. It can be seen that how to effectively improve the detection efficiency and device stability of EUV detectors is one of the key scientific issues faced in the design and fabrication of 4H-SiC-based EUV detectors.
  • the invention provides a novel silicon carbide-based lateral PN junction extreme ultraviolet detector based on selective ion implantation and a preparation method thereof, so as to solve the problems of low detection efficiency of the detector in the extreme ultraviolet band, poor device stability and long-range reliability.
  • a novel SiC-based lateral PN junction EUV detector based on selective area ion implantation including an N-type ohmic contact bottom electrode, an N-type substrate, and a low-doped epitaxial layer connected sequentially from bottom to top.
  • the low-doped epitaxial layer is N-type low-doped epitaxial layer or P-type low-doped epitaxial layer; when it is an N-type low-doped epitaxial layer, the surface of the N-type low-doped epitaxial layer forms a P-type well region by selective ion implantation, and a P-type well region is provided on the P-type well region.
  • the ohmic contact upper electrode, the P-type ohmic contact upper electrode is provided with a metal conductive electrode along the periphery; when it is a P-type low-doped epitaxial layer, the surface of the P-type low-doped epitaxial layer forms an N-type well region by selective ion implantation, and the N-type well region
  • An N-type ohmic contact upper electrode is arranged on the top, and metal conductive electrodes are arranged along the periphery of the N-type ohmic contact upper electrode.
  • the above-mentioned P-type or N-type ohmic contact upper electrode and the P-type or N-type well region formed by selective ion implantation on the N-type or P-type silicon carbide low-doped epitaxial layer are used to form ohmic contacts; N-type or P-type silicon carbide
  • the non-ion-implanted region in the low-doped epitaxial layer is the structural layer that receives incident photons, and the lower doping concentration enables the device to obtain a wider laterally widened depletion region at a low bias voltage; metal conductive electrodes can effectively improve
  • the current expansion and carrier collection capabilities of the device are used for packaging and bonding, and for grounding during testing.
  • the lower electrode of the N-type ohmic contact is connected to the positive electrode during the test; while when the low-doped epitaxial layer is a P-type low-doped epitaxial layer, the lower electrode of the N-type ohmic contact is connected to the positive electrode during the test. Connect to the negative pole during the test.
  • a P-type or N-type well region refers to a P-type well region or an N-type well region, and other similar expressions have similar meanings.
  • the above-mentioned new silicon carbide-based EUV detectors use selected ion implantation technology to form a lateral PN junction on the surface of the device, and the active region of the device is in the reverse direction.
  • the lateral broadening occurs in the bias mode, so that the incident EUV photons can directly enter the active absorption region between the device surface and the P-type or N-type well region, thereby effectively avoiding the thick ohmic contact layer of the EUV photons on the surface of the traditional device.
  • the detector adopts a PN junction structure working in a reverse bias state, compared with Schottky
  • the built-in electric field strength and leakage current level of the device are less affected by the high-energy photon irradiation and the temperature change of the working environment, which effectively improves the anti-irradiation performance of the device and the ability to work under extreme temperature conditions.
  • a P-type high-doped epitaxial layer is provided between the P-type low-doped epitaxial layer and the N-type substrate.
  • the P-type or N-type well regions are distributed at intervals on the surface of the N-type or P-type low-doped epitaxial layer, and the filling factor (the filling factor is the sum of the surface areas of all P-type or N-type well regions) relative to selective ion implantation
  • the proportion of the surface area of the previous N-type or P-type low-doped epitaxial layer) is 10-90%; preferably, the filling factor is 40%.
  • a lateral PN junction is formed between the P-type or N-type well region formed by ion implantation and the N-type or P-type region without ion implantation, and the electron-hole pairs generated by the incident extreme ultraviolet photons act together on the built-in electric field and the drift electric field in the PN junction Under the separation and formation of photoresponsive current, thereby realizing the detection of extreme ultraviolet photons.
  • the P-type or N-type well region is in the shape of grid strips, grids or rings.
  • the material of the N-type substrate is silicon carbide; the material of the N-type or P-type low-doped epitaxial layer is silicon carbide.
  • the doping concentration of the N-type silicon carbide substrate is 1 ⁇ 10 18 cm -3 to 1 ⁇ 10 20 cm -3 , more preferably 1 ⁇ 10 19 cm -3 ; N-type or P-type silicon carbide low-doped
  • the doping concentration of the epitaxial layer is lower than 1 ⁇ 10 16 cm -3 , more preferably 1 ⁇ 10 14 cm -3 to 1 ⁇ 10 16 cm -3 , more preferably 3 ⁇ 10 14 cm -3 ; formed by ion implantation
  • the doping concentration of the P-type or N-type well region is higher than 1 ⁇ 10 17 cm -3 , more preferably 1 ⁇ 10 17 cm -3 to 1 ⁇ 10 19 cm -3 , more preferably 3 ⁇ 10 18 cm -3 .
  • the thickness of the N-type or P-type silicon carbide low-doped epitaxial layer is greater than 1 ⁇ m, more preferably 5 ⁇ m, and the depth of the P-type or N-type well region is less than 1 ⁇ m, more preferably 200 nm.
  • the material of the P-type or N-type ohmic contact upper electrode is a mixture of one or more than two of nickel, titanium, aluminum, gold and other materials in any proportion, preferably nickel with a thickness of 100-300nm layer
  • the material of the N-type ohmic contact lower electrode is a mixture of one or more than two kinds of nickel, titanium, aluminum, gold and other materials in any proportion, preferably, a nickel layer, a titanium layer, and Aluminum layer and gold layer, wherein, the thickness of the nickel layer is 30-40nm, the thickness of the titanium layer is 40-60nm, the thickness of the aluminum layer is 90-110nm, the thickness of the gold layer is 90-110nm; the total thickness of the metal conductive electrode is at least 1 ⁇ m, preferably, the metal conductive electrode is composed of a titanium layer and a gold layer, the thickness of the titanium layer is 450-550nm, and the thickness of the gold layer is 450-550nm; the metal conductive electrode includes
  • the device forms a non-completely filled P-type or N-type well region by selective ion implantation technology in the N-type or P-type low-doped epitaxial layer on the device surface, and the P-type or N-type well region and the non-implanted
  • a lateral PN junction is formed between N-type or P-type low-doped epitaxial layers, and the depletion region of the PN junction expands laterally and pinches off under reverse bias voltage.
  • the active absorption region of the device in the extreme ultraviolet band is N Type or P-type low-doped epitaxial layer without ion-implanted regions.
  • the incident EUV photons can directly enter the active region of the device without passing through any structure, which greatly reduces the ineffective absorption of EUV photons.
  • the electron-hole pairs generated by the incident EUV photons are separated under the action of the electric field in the junction region, and the electrons and holes are collected by the negative and positive electrodes of the device respectively to form a photocurrent, thereby realizing the detection of EUV photons.
  • the above-mentioned preparation method of the novel silicon carbide-based lateral PN junction EUV detector based on selective area ion implantation comprises the following steps connected in sequence:
  • PECVD plasma enhanced chemical vapor deposition
  • LPCVD low-pressure chemical vapor deposition
  • RIE reactive ion etching
  • Selective ion implantation is performed on the surface of the N-type or P-type low-doped epitaxial layer, and thermal annealing is performed to activate the impurities; preferably, multiple ion implantations are performed to obtain a uniform doping concentration curve in the implanted region;
  • N-type ohmic contact electrodes on the lower surface of the substrate, and anneal at high temperature to form N-type ohmic contacts; preferably, the N-type ohmic contact electrodes are deposited by physical vapor deposition (PVD);
  • the conductive metal electrodes are deposited by physical vapor deposition (PVD).
  • the temperature of the thermal annealing treatment is preferably 1600-1650° C., and the time is 20-30 minutes.
  • the temperature of high temperature annealing is preferably 800-850° C., and the time is preferably 2-3 minutes.
  • step 1) when the low-doped epitaxial layer is a P-type low-doped epitaxial layer, first epitaxially grow a P-type high-doped epitaxial layer on the upper surface of the N-type substrate , and then epitaxially grow a P-type low-doped epitaxial layer on the P-type high-doped epitaxial layer.
  • step 3 according to the photolithography pattern obtained by exposure and development, the mask layer on the N-type or P-type low-doped epitaxial layer is etched away at intervals, so that some areas on the N-type or P-type low-doped epitaxial layer remain
  • the mask layer is used as an ion implantation mask, and the rest of the area is exposed silicon carbide material.
  • step 4 P-type or N-type ion implantation is performed on the N-type or P-type low-doped epitaxial layer etched away from the mask layer to form P-type or N-type well regions distributed in intervals, and N-type or P-type
  • the region where the mask layer is reserved on the surface of the low-doped epitaxial layer is an active absorption region, thereby realizing the preparation of P-type or N-type well regions distributed at intervals.
  • the novel SiC-based lateral PN junction EUV detector based on selective ion implantation in the present invention effectively avoids the strong absorption of EUV photons by the non-active area on the surface of the traditional structure PN junction detector, and effectively improves the detector’s performance in the EUV. At the same time, it effectively avoids the hidden dangers of Schottky junction detectors in radiation stability and temperature stability when they are applied in strong radiation and high temperature environments; effectively avoids the epitaxial memory effect and cavity contamination
  • the resulting device performance fluctuates, and at the same time, there is no need to undergo etching-surface treatment and other processes that affect the device interface characteristics during the device preparation process, and the process window is wide, which is conducive to industrial production.
  • Fig. 1 is a flow chart of the preparation method of a novel silicon carbide-based lateral PN junction EUV detector based on selective ion implantation in Example 1 of the present invention
  • FIG. 2 is a schematic cross-sectional structure diagram of a novel silicon carbide-based lateral PN junction EUV detector based on selective ion implantation in Embodiment 1 of the present invention
  • Fig. 3 is the current-voltage characteristic curve of the novel silicon carbide-based lateral PN junction EUV detector based on selective area ion implantation in Example 1 of the present invention
  • Fig. 4 is the quantum efficiency curve in the wavelength range of 50-100nm of the new silicon carbide-based lateral PN junction extreme ultraviolet detector based on selective area ion implantation and the traditional structure PN junction ultraviolet detector in embodiment 1 of the present invention;
  • Fig. 5 is the quanta of the new silicon carbide-based lateral PN junction extreme ultraviolet detector based on selective area ion implantation in the embodiment 1 of the present invention under the bias voltages of 0V, -10V, -20V and -40V, within the wavelength range of 5-100nm efficiency curve;
  • Fig. 6 is the dark current curves of the novel SiC-based lateral PN junction EUV detector based on selective area ion implantation and the Schottky junction EUV detector of the same size before and after irradiation in Example 1 of the present invention;
  • Fig. 7 is the dark current curves of the novel silicon carbide-based lateral PN junction EUV detector based on selective area ion implantation and the Schottky junction EUV detector of the same size at different operating temperatures in Example 1 of the present invention;
  • 1 is the N-type ohmic contact lower electrode
  • 2 is the N-type silicon carbide substrate
  • 3 is the N-type silicon carbide low-doped epitaxial layer
  • 4 is the P-type well region
  • 5 is the P-type ohmic contact upper electrode
  • Metal conductive electrode 7 is SiO 2 passivation layer.
  • the novel SiC-based lateral PN junction EUV detector based on selective area ion implantation includes an N-type ohmic contact lower electrode 1, an N-type SiC substrate 2 and an N-type SiC
  • the ohmic contact upper electrode 5 is provided with a metal conductive electrode 6 along the periphery, and the metal conductive electrode 6 is provided with a SiO 2 passivation layer 7 along the periphery.
  • the well width of the P-type well region 4 is 5 ⁇ m, the well spacing is 5 ⁇ m, the well depth is about 200 nm, and the filling factor (the sum of the surface areas of all P-type well regions accounts for the ratio of the total surface area of the N-type low-doped epitaxial layer before the selective ion implantation) 40%;
  • the P-type ohmic contact upper electrode 5 is in the shape of a grid strip composed of strip electrodes, the width of the strip electrodes is 3 ⁇ m, and the distance between the strip electrodes is 7 ⁇ m.
  • Step 101 on the N-type silicon carbide substrate 2 with a doping concentration of 1 ⁇ 10 19 cm -3 and a thickness of 350 ⁇ m, epitaxially grow N-type silicon carbide substrate 2 with a thickness of 5 ⁇ m by metal organic compound chemical vapor deposition (MOCVD).
  • MOCVD metal organic compound chemical vapor deposition
  • the silicon low-doped epitaxial layer 3 has a doping concentration of 3 ⁇ 10 14 cm -3 .
  • Step 102 depositing a SiO2 mask layer with a thickness of 1500 nm on the surface of the N-type silicon carbide low-doped epitaxial layer 3 by plasma-enhanced chemical vapor deposition (PECVD), and then spin-coating photoresist on the surface of the mask layer, And forming a photoresist pattern through exposure and development to define the ion implantation mask area;
  • PECVD plasma-enhanced chemical vapor deposition
  • Step 103 using the photoresist pattern formed in step 102 as an etching mask, using reactive ion etching (RIE) to etch the SiO2 mask layer deposited in step 102 at intervals, until the remaining SiO2 is masked
  • RIE reactive ion etching
  • BOE buffered oxide etching solution
  • Step 104 perform multiple selective area ion implantation (Al ions) on the surface of the N-type silicon carbide low-doped epitaxial layer 3 to obtain a uniform doping concentration curve, perform thermal annealing treatment (1650°C, 30min) to activate impurities, and standard cleaning to remove the epitaxial layer
  • Al ions selective area ion implantation
  • Step 105 using the physical vapor deposition (PVD) method to sequentially deposit metal Ni/Ti/Al/Au on the back of the N-type silicon carbide substrate 2, the thickness of which is about 35/50/100/100nm in sequence, and after depositing the metal
  • PVD physical vapor deposition
  • Step 106 deposit a SiO2 passivation layer with a thickness of 500nm on the surface of the epitaxial wafer by plasma enhanced chemical vapor deposition (PECVD), define the optical window by photolithography, and remove the SiO2 passivation in the window area by wet etching Layer, forming SiO 2 passivation layer 7;
  • PECVD plasma enhanced chemical vapor deposition
  • Step 107 using physical vapor deposition (PVD) to deposit metal Ni on the surface of the P-type well region 4 with a thickness of about 200nm, and place the deposited epitaxial wafer in an annealing furnace for high temperature annealing at 850°C for 3min under vacuum conditions , thereby forming a P-type ohmic contact upper electrode 5;
  • PVD physical vapor deposition
  • Step 108 using the physical vapor deposition (PVD) method to sequentially deposit metal Ti/Au on the edge of the P-type ohmic contact upper electrode 5, the thickness of which is about 500/500nm, thereby forming the metal conductive electrode 6;
  • PVD physical vapor deposition
  • Step 109 slitting, dividing the epitaxial wafer into individual devices, bonding and packaging the finished device on the TO socket, and performing further electro-optic testing, the N-type ohmic contact lower electrode 1 is connected to a positive voltage during the test, and the metal conductive electrode 6 Grounding.
  • the novel silicon carbide-based lateral PN junction EUV detector provided in the above-mentioned embodiment 1 effectively avoids the generation of EUV photons when they penetrate the passive regions such as the ohmic contact layer and the passivation layer on the surface of the traditional structure PN junction detector. loss, thereby effectively improving the detection efficiency of the detector in the extreme ultraviolet band; and compared with the traditional Schottky junction extreme ultraviolet
  • the PN junction extreme ultraviolet detector has good temperature stability and strong radiation resistance, and has the potential to work stably for a long time in strong radiation and high temperature environments.
  • the new silicon carbide-based lateral PN junction extreme ultraviolet detector on the one hand, the two structures are completely different and belong to completely different
  • the former is a lateral junction device formed by selective ion implantation, while the latter is a vertical structure device, so the carrier collection methods of the two are completely different, and the latter has a large lateral series resistance; on the other hand, the above detection
  • the device can effectively avoid device performance fluctuations caused by the epitaxial memory effect and cavity contamination.
  • the device does not need to undergo etching-surface treatment and other processes that affect the device interface characteristics during the device preparation process.
  • the process window is wide and is conducive to industrial production.
  • the leakage current of the novel silicon carbide-based lateral PN junction EUV detector based on selective area ion implantation provided in the above-mentioned embodiment 1 is 0.5pA (active region area) at room temperature and at a reverse bias voltage of -40V. 2.5 ⁇ 2.5mm 2 , the current density is about 8pA/cm 2 ), the device has an extremely low noise level and is suitable for the detection of weak signals.
  • Fig. 4 is the quantum efficiency curve (bias voltage is 40V). It can be seen from Figure 4 that the quantum efficiency of the novel SiC-based lateral PN junction EUV detector based on selective ion implantation is much higher than that of the traditional structure PN junction detector in the above-mentioned wavelength band where the photon penetration depth is about 10-33nm. The feasibility of the lateral PN junction structure formed by the selective area ion implantation in the above-mentioned embodiment 1 in reducing the loss of extreme ultraviolet photons in the non-active area of the device surface and improving the detection efficiency of the device in the extreme ultraviolet band is proved.
  • Fig. 5 is the quanta of the novel silicon carbide-based lateral PN junction extreme ultraviolet detector based on selective area ion implantation provided in the above-mentioned embodiment 1 under the bias voltages of 0V, -10V, -20V and -40V, within the wavelength range of 5-100nm efficiency curve. It can be seen from Fig. 5 that the quantum efficiency of the above-mentioned novel SiC-based lateral PN junction EUV detector based on selective area ion implantation gradually increases with the increase of bias voltage and finally tends to saturation, which is mainly due to the With the increase of the set voltage, the electric field intensity in the junction region of the device gradually increases, and the carrier collection efficiency also increases.
  • the depletion region of the device expands at the same time, and the increase in the area of the active region of the device also promotes the improvement of the quantum efficiency of the device.
  • the fill factor of the novel SiC-based lateral PN junction EUV detector based on selective area ion implantation provided in the above-mentioned embodiment 1 is 40%, and its quantum efficiency is about 692.5%@13.5nm.
  • the fill factor of the above-mentioned detector is 10% At 13.5nm, its quantum efficiency can be as high as 1038.75%@13.5nm, which is close to the theoretical value of 1177.59% at 13.5nm.
  • Figure 6 shows the continuous irradiation of the new SiC-based lateral PN junction EUV detector based on selective area ion implantation and the Schottky junction EUV detector of the same size (202010309443.4) provided in the above-mentioned Example 1 under a 13.5nm wavelength EUV light source Dark current curves before and after 12 hours. It can be seen from Fig. 6 that after being irradiated with extreme ultraviolet light with a wavelength of 13.5nm for 12 hours, the dark current of the Schottky junction detector rises from the order of 10-12 to the order of 10-9 .
  • the leakage current of the implanted novel SiC-based lateral PN junction EUV detector is still on the order of 10 -12 , which proves that the novel SiC-based lateral PN junction EUV detector based on selective ion implantation of the present invention has good irradiation stability.
  • Figure 7 shows the dark current curves of the novel SiC-based lateral PN junction EUV detector based on selective area ion implantation provided in the above-mentioned Example 1 and the Schottky junction EUV detector of the same size (202010309443.4) at different operating temperatures.

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Abstract

本发明公开了一种基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，包括从下到上依次相接的N型欧姆接触下电极、N型衬底和低掺外延层，低掺外延层为N型低掺外延层或P型低掺外延层；当为N型低掺外延层时，N型低掺外延层表面通过选区离子注入形成P型阱区域，P型阱区域上设有P型欧姆接触上电极，P型欧姆接触上电极沿周边设有金属导电电极；当为P型低掺外延层时，P型低掺外延层表面通过选区离子注入形成N型阱区域，N型阱区域上设有N型欧姆接触上电极，N型欧姆接触上电极沿周边设有金属导电电极。本发明有效提升了探测器在极紫外波段的探测效率，同时显著提高了辐照稳定性以及温度稳定性。

Description

基于选区离子注入的新型碳化硅基横向PN结极紫外探测器及制备方法 技术领域
本发明涉及一种基于选区离子注入的新型碳化硅(SiC)基横向PN结极紫外(EUV)探测器及其制备方法，属于半导体器件光电探测技术领域。
背景技术
极紫外(EUV)探测技术在集成电路7nm以下工艺制程光刻以及等离子体物理、天文物理、高能物理、卫星空间环境监测等诸多科研和生产领域具有广阔的应用前景。极紫外探测技术主要用于探测波长范围位于10-200nm之间的短波长、高能量紫外光，相较于可见光波段(400-760nm)与常规紫外波段(200-400nm)，极紫外光子具有穿透深度浅、光子能量高的特点。极紫外光子的这些特殊性质限制了极紫外探测器的研发，而这也成为了制约极紫外探测技术发展的关键因素。首先，极紫外光子在硅(Si)等半导体材料中吸收系数大、穿透深度普遍低于10nm，入射极紫外光子极易被探测器表面的欧姆接触层、钝化层等非有源区吸收，由此导致器件探测效率极低；其次，极紫外光子能量较高，高能光子辐照导致器件中产生缺陷态，并带来热累积、噪声水平抬升等一系列附加效应，由此导致探测器器件性能发生退化；同时，极紫外探测器需要面临恶劣的工作环境，以极紫外光刻为例，作为核心部件的极紫外探测器需要经受累计强度高达1MJ/cm 2的高能光子辐照，这对极紫外探测器的可靠性和长程稳定性提出了挑战。
现阶段用于常规紫外波段的探测器普遍无法满足在极紫外波段长时间高效稳定工作的要求。Si基探测器受限于Si材料禁带宽度窄、临界位移能低、热导系数低的影响具有噪声水平高、抗辐照性能差、温度稳定性差的缺陷。相较而言，宽禁带半导体材料4H-SiC具备禁带宽度大、临界位移能高、热导系数高以及化学稳定性好的特性，在制备工作于紫外波段的光电探测器件方面具有显著的材料性能优势。然而，现有的碳化硅基紫外探测器仍存在很多缺陷：碳化硅基肖特基结探测器在高能极紫外光子辐照下容易产生正电空位，导致肖特基势垒高度因镜像力效应降低，进而导致器件漏电流升高；而碳化硅基传统结构PN结探测器表面的非有源区对极紫外光子形成强吸收，导致器件在极紫外波段的探测效率极低。由此可见，如何有效提高极紫外探测器的探测效率和器件稳定性，是4H-SiC基极紫外探测器设计和制备所面临的关键科学问题之一。
发明内容
本发明提供一种基于选区离子注入的新型碳化硅基横向PN结极紫外探测器及其制备方法，以解决探测器在极紫外波段探测效率低、器件稳定性和长程可靠性差的问题。
为解决上述技术问题，本发明所采用的技术方案如下：
一种基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，包括从下到上依次相接的N型欧姆接触下电极、N型衬底和低掺外延层，低掺外延层为N型低掺外延层或P型低掺外延层；当为N型低掺外延层时，N型低掺外延层表面通过选区离子注入形成P型阱区域，P型阱区域上设有P型欧姆接触上电极，P型欧姆接触上电极沿周边设有金属导电电极；当为P型低掺外延层时，P型低掺外延层表面通过选区离子注入形成N型阱区域，N型阱区域上设有N型欧姆接触上电极，N型欧姆接触上电极沿周边设有金属导电电极。
上述P型或N型欧姆接触上电极以及在N型或P型碳化硅低掺外延层上通过选区离子注入形成的P型或N型阱区域用于形成欧姆接触；N型或P型碳化硅低掺外延层中的非离子注入区域为接收入射光子的结构层，较低的掺杂浓度使得器件在低偏置电压下便能获得较宽的横向展宽耗尽区；金属导电电极可以有效提高器件的电流扩展和载流子收集能力，用于封装打线，测试中接地极。当低掺外延层为N型低掺外延层时，上述N型欧姆接触下电极在测试中接正极；而当低掺外延层为P型低掺外延层时，上述N型欧姆接触下电极在测试中接负极。
本申请P型或N型阱区域，指P型阱区域或N型阱区域，其它类似表达含义类似。
区别于面向常规紫外波段的传统结构PN结探测器以及肖特基结构探测器，上述新型碳化硅基极紫外探测器采用选取离子注入技术在器件表面形成横向PN结，器件有源区在反向偏置模式下发生横向展宽，使得入射极紫外光子可以直接进入位于器件表面、P型或N型阱区域之间的有源吸收区，从而有效规避了极紫外光子在传统器件表面厚欧姆接触层以及过渡层中的强吸收，进而有效提升了器件在极紫外波段尤其是真空紫外波段的探测效率；此外，该探测器采用工作在反向偏置状态的PN结结构，相较于肖特基结构，器件内建电场强度和漏电流水平受高能光子辐照和工作环境温度变化的影响较小，有效提升了器件的抗辐照性能和在极端温度条件下工作的能力。
为了避免穿通，当为P型低掺外延层时，P型低掺外延层和N型衬底之间设有P型高掺外延层。
为了进一步提高量子效率，P型或N型阱区域在N型或P型低掺外延层表面呈间隔 性分布，填充因子(填充因子为所有P型或N阱区域的表面积之和相对选区离子注入前的N型或P型低掺外延层表面积的占比)为10～90％；优选，填充因子为40％。离子注入形成的P型或N型阱区域与无离子注入的N型或P型区域间形成横向PN结，入射极紫外光子产生的电子空穴对在PN结内建电场和漂移电场的共同作用下分离并形成光响应电流，由此实现对极紫外光子的探测。进一步优选，P型或N型阱区域为栅条状、网格状或环状。
为了进一步提高器件性能，N型衬底的材料为碳化硅；N型或P型低掺外延层的材料为碳化硅。进一步优选，N型碳化硅衬底的掺杂浓度为1×10 18cm -3～1×10 20cm -3，更优选为1×10 19cm -3；N型或P型碳化硅低掺外延层的掺杂浓度低于1×10 16cm -3，进一步优选为1×10 14cm -3～1×10 16cm -3，更优选为3×10 14cm -3；离子注入形成的P型或N型阱区域的掺杂浓度高于1×10 17cm -3，进一步优选为1×10 17cm -3～1×10 19cm -3，更优选为3×10 18cm -3。N型或P型碳化硅低掺外延层的厚度大于1μm，更优选为5μm，P型或N型阱区域的深度低于1μm，更优选为200nm。
为了确保器件的综合性能，P型或N型欧姆接触上电极的材料为镍、钛、铝、金等材料中一种或两种以上任意配比的混合物，优选为厚度为100-300nm的镍层；N型欧姆接触下电极的材料为镍、钛、铝、金等材料中一种或两种以上任意配比的混合物，优选为，从下到上依次相接的镍层、钛层、铝层和金层，其中，镍层的厚度为30～40nm，钛层的厚度为40～60nm，铝层的厚度为90～110nm，金层的厚度为90～110nm；金属导电电极的总厚度为至少1μm，优选为，金属导电电极由钛层和金层构成，钛层的厚度为450～550nm，金层的厚度为450～550nm；金属导电电极包括用于引线键合的Pad区域以及用于导电的线条区域，其中优选，Pad区域边长为90～110μm，线条区域宽度为25～35μm，这样方便器件的封装、能更好地兼顾导电性和器件有源区面积。
上述方案原理如下：该器件在器件表面的N型或P型低掺外延层内通过选区离子注入技术形成非完全填充的P型或N型阱区域，P型或N型阱区域与没有注入的N型或P型低掺外延层之间形成横向PN结，PN结耗尽区在反向偏置电压下横向扩展并发生夹断，此时器件在极紫外波段的有源吸收区即为N型或P型低掺外延层中没有离子注入的区域。由此入射极紫外光子无需经过任何结构即可直接进入器件有源区，这大幅减少了极紫外光子的无效吸收。入射极紫外光子产生的电子空穴对在结区电场的作用下发生分离，电子和空穴分别为器件负极和正极所收集并形成光电流，由此实现对极紫外光子的探测。
上述基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的制备方法，包括顺 序相接的如下步骤：
1)在N型衬底上表面外延生长N型低掺外延层或依次外延生长P型高掺外延层和P型低掺外延层；优选，采用高温化学气相沉积(CVD)方式在衬底上表面外延生长N型或P型高掺、低掺外延层；
2)在外延片上淀积掩模层，进而在掩模层上旋涂光刻胶，并通过曝光显影形成光刻胶图案定义离子注入掩模区域；优选，采用等离子体增强化学气相沉积(PECVD)或低压化学气相沉积(LPCVD)的方法在所述外延片上淀积掩模层；
3)以光刻胶图案为掩模刻蚀掩模层，在N型或P型低掺外延层表面形成离子注入掩模；优选，采用反应离子刻蚀(RIE)和湿法腐蚀的方法在外延片表面进行刻蚀；
4)在N型或P型低掺外延层表面进行选区离子注入，进行热退火处理激活杂质；优选，多次离子注入以在注入区域获得均匀的掺杂浓度曲线；
5)在衬底下表面淀积N型欧姆接触电极，高温退火，形成N型欧姆接触；优选，N型欧姆接触电极采用物理气相沉积(PVD)方式沉积；
6)在N型或P型低掺外延层表面旋涂光刻胶，依据曝光显影得到的光刻图形，在选区离子注入形成的P型或N型阱区域淀积P型或N型欧姆接触上电极，高温退火，形成P型或N型欧姆接触；优选，P型或N型欧姆接触上电极采用物理气相沉积(PVD)方式沉积；
7)在P型或N型欧姆接触上电极边缘位置淀积金属导电电极，完成基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的制备。优选，金属导电电极采用物理气相沉积(PVD)方式沉积。
步骤4)中，热退火处理的温度优选为1600～1650℃，时间为20～30min。步骤6)中，高温退火的温度优选为800～850℃，时间优选为2～3min。
为制备呈间隔性分布的P型或N型阱区域：步骤1)中，当低掺外延层为P型低掺外延层时，先在N型衬底上表面外延生长P型高掺外延层，再在P型高掺外延层上外延生长P型低掺外延层。步骤3)中，依据曝光显影得到的光刻图形，间隔性地刻蚀掉N型或P型低掺外延层上的掩模层，使N型或P型低掺外延层上的部分区域保留掩模层作为离子注入掩模，其余区域为裸露的碳化硅材料。步骤4)中，在刻蚀掉掩模层的N型或P型低掺外延层上经P型或N型离子注入形成呈间隔性分布的P型或N型阱区域，N型或P型低掺外延层表面保留掩模层的区域为有源吸收区，由此实现呈间隔性分布的P型或N型阱区域的制备。
本发明未提及的技术均参照现有技术。
本发明基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，有效规避了传统结构PN结探测器表面的非有源区对极紫外光子的强吸收，有效提升了探测器在极紫外波段的探测效率；同时有效规避了肖特基结探测器在应用于强辐射、高温环境中时在辐照稳定性以及温度稳定性方面存在的隐患；有效规避了外延记忆效应以及腔体沾污造成的器件性能波动，同时器件制备过程中无需经历刻蚀-表面处理等影响器件界面特性的工序，工艺窗口较宽、有利于产业化生产。
附图说明
图1为本发明实施例1中基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的制备方法流程图；
图2为本发明实施例1中基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的剖面结构示意图；
图3为本发明实施例1中基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的电流-电压特性曲线；
图4为本发明实施例1中基于选区离子注入的新型碳化硅基横向PN结极紫外探测器以及传统结构PN结紫外探测器在50-100nm波长范围内的量子效率曲线；
图5为本发明实施例1中基于选区离子注入的新型碳化硅基横向PN结极紫外探测器在0V、-10V、-20V以及-40V偏置电压下、在5-100nm波长范围内的量子效率曲线；
图6为本发明实施例1中基于选区离子注入的新型碳化硅基横向PN结极紫外探测器以及同等尺寸的肖特基结极紫外探测器在辐照前后的暗电流曲线；
图7为本发明实施例1中基于选区离子注入的新型碳化硅基横向PN结极紫外探测器以及同等尺寸的肖特基结极紫外探测器在不同工作温度下的暗电流曲线；
图中，1为N型欧姆接触下电极；2为N型碳化硅衬底；3为N型碳化硅低掺外延层；4为P型阱区域；5为P型欧姆接触上电极；6为金属导电电极；7为SiO 2钝化层。
具体实施方式
为了更好地理解本发明，下面结合实施例进一步阐明本发明的内容，但本发明的内容不仅仅局限于下面的实施例。
实施例1
如图2所示，基于选区离子注入的新型碳化硅基横向PN结极紫外探测器包括从下到上依次相接的N型欧姆接触下电极1、N型碳化硅衬底2和N型碳化硅低掺外延层3，N型碳化硅低掺外延层3表面通过选区离子注入形成栅条状的P型阱区域4，P型阱区域4上设有P型欧姆接触上电极5，P型欧姆接触上电极5沿周边设有金属导电电极6，金属导电电极6沿周边设有SiO 2钝化层7。P型阱区域4的阱宽为5μm，阱间距为5μm，阱深约为200nm，填充因子(所有P型阱区域的表面积之和占选区离子注入前N型低掺外延层总表面积的比例)为40％；P型欧姆接触上电极5呈由条形电极组成的栅条状，条形电极宽度为3μm，条形电极间距为7μm。
如图1所示，上述器件制备流程如下：
步骤101，在掺杂浓度为1×10 19cm -3、厚度为350μm的N型碳化硅衬底2上，采用金属有机化合物化学气相沉淀(MOCVD)的方法外延生长厚度为5μm的N型碳化硅低掺外延层3，掺杂浓度为3×10 14cm -3。
步骤102，在N型碳化硅低掺外延层3表面采用等离子体增强化学气相沉积(PECVD)的方法淀积厚度为1500nm的SiO 2掩模层，进而在掩模层表面旋涂光刻胶，并通过曝光显影形成光刻胶图案定义离子注入掩模区域；
步骤103，以步骤102中形成的光刻胶图案作为刻蚀掩模，采用反应离子刻蚀(RIE)方法间隔性地刻蚀步骤102中淀积的SiO 2掩模层，待剩余SiO 2掩模层厚度约为100nm时，改用缓冲氧化物刻蚀液(BOE)将表面裸露部分的SiO 2掩模层腐蚀干净，再使用丙酮、乙醇等有机溶剂去除外延片表面的光刻胶，由此在N型碳化硅低掺外延层3表面形成离子注入掩模；
步骤104，在N型碳化硅低掺外延层3表面进行多次选区离子注入(Al离子)，获得均匀的掺杂浓度曲线，进行热退火处理(1650℃，30min)激活杂质，标准清洗去除外延片表面的碳膜、离子注入掩模层等结构，由此形成栅条状的P型阱区域4，其掺杂浓度约为3×10 18cm -3；
步骤105，采用物理气相沉积(PVD)方法在N型碳化硅衬底2背部依次淀积金属Ni/Ti/Al/Au，其厚度依次约为35/50/100/100nm，将淀积金属后的外延片放入退火炉中在氮气氛围下850℃高温退火3min，从而形成N型欧姆接触下电极1；
步骤106，采用等离子体增强化学气相沉积(PECVD)的方法在外延片表面淀积厚度为500nm的SiO 2钝化层，通过光刻显影定义光学窗口，湿法腐蚀去除窗口区域的SiO 2钝化层，形成SiO 2钝化层7；
步骤107，采用物理气相沉积(PVD)方法在P型阱区域4表面淀积金属Ni，其厚度约为200nm，将淀积金属后的外延片放入退火炉中真空条件下850℃高温退火3min，从而形成P型欧姆接触上电极5；
步骤108，采用物理气相沉积(PVD)方法在P型欧姆接触上电极5边缘位置依次淀积金属Ti/Au，其厚度依次约为500/500nm，从而形成金属导电电极6；
步骤109，裂片，将外延片划分为单个器件，将成品器件打线封装在TO管座上，进行进一步的电学光学测试，N型欧姆接触下电极1在测试中接正电压，金属导电电极6接地极。
上述实施例1提供的新型碳化硅基横向PN结极紫外探测器，有效规避了极紫外光子在穿透传统结构PN结探测器表面的欧姆接触层、钝化层等无源区中时产生的损耗，从而有效提升了探测器在极紫外波段的探测效率；而相较于传统肖特基结极紫外探测器探测性能易受肖特基势垒高度变化影响的缺陷，上述新型碳化硅基横向PN结极紫外探测器温度稳定性好、抗辐射能力强，具备在强辐射、高温环境中长时间稳定工作的潜力。
上述施例1提供的新型碳化硅基横向PN结极紫外探测器，相比于碳化硅超薄n型欧姆接触层n-i-p型极深紫外探测器，一方面，二者结构完全不同，属于完全不同的方案，前者为选区离子注入形成的横向结器件，而后者则是垂直结构器件，因此二者的载流子收集方式完全不同，后者存在较大的横向串联电阻；另一方面，上述探测器可以有效规避外延记忆效应以及腔体沾污造成的器件性能波动，同时器件制备过程中无需经历刻蚀-表面处理等影响器件界面特性的工序，工艺窗口较宽、有利于产业化生产。
由图3可见，上述实施例1提供的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器在室温条件、-40V反向偏置电压下的漏电流为0.5pA(有源区面积2.5×2.5mm 2，电流密度约为8pA/cm 2)，该器件具备极低的噪声水平，适用于微弱信号的探测。
图4为上述实施例1提供的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器以及碳化硅基传统结构PN结探测器在50-100nm波长范围内的量子效率曲线(偏置电压为40V)。由图4可见，在光子穿透深度约为10-33nm的上述波段，基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的量子效率远高于传统结构PN结探测器，这验证了上述实施例1中选区离子注入形成的横向PN结结构在减少极紫外光子在器件表层非有源区内的损耗、提升器件在极紫外波段的探测效率方面的可行性。
图5为上述实施例1提供的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器在0V、-10V、-20V以及-40V偏置电压下、在5-100nm波长范围内的量子效率曲线。 由图5可见，上述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的量子效率随偏置电压增加而逐渐增大并最终趋于饱和，这主要是由于随着反向偏置电压的增大，器件结区电场强度逐渐增大，载流子收集效率也随之提高，此外，器件耗尽区同时发生扩展，器件有源区面积的增加也促使器件的量子效率得到提升。上述实施例1提供的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的填充因子为40％，其量子效率约为692.5％@13.5nm，当上述探测器的填充因子为10％时，其量子效率可高达1038.75％@13.5nm，接近13.5nm处的量子效率理论值1177.59％。
图6为上述实施例1提供的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器以及同等尺寸肖特基结极紫外探测器(202010309443.4)在13.5nm波长极紫外光源下连续辐照12小时前后的暗电流曲线。由图6可见，在经过13.5nm波长极紫外光辐照12小时后，肖特基结探测器的暗电流由10 -12量级上升至10 -9量级，而本发明中的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的漏电流仍保持在10 -12量级，这证明本发明基于选区离子注入的新型碳化硅基横向PN结极紫外探测器具备良好的辐照稳定性。
图7为上述实施例1提供的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器以及同等尺寸肖特基结极紫外探测器(202010309443.4)在不同工作温度下的暗电流曲线。由图7可见，随着工作温度由298K上升至423K，肖特基结极紫外探测器在-20V下的暗电流由5×10 -13A上升至5×10 -10A，漏电流上升了1000倍；而本发明中的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器在-40V下的漏电流仅升至2.7×10 -12A，其在473K下的漏电流值也仅为5×10 -12A，以上结果说明本实施例提供的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器具备优越的温度稳定性。

Claims (10)

  1. 一种基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，其特征在于：包括从下到上依次相接的N型欧姆接触下电极、N型衬底和低掺外延层，低掺外延层为N型低掺外延层或P型低掺外延层；当为N型低掺外延层时，N型低掺外延层表面通过选区离子注入形成P型阱区域，P型阱区域上设有P型欧姆接触上电极，P型欧姆接触上电极沿周边设有金属导电电极；当为P型低掺外延层时，P型低掺外延层表面通过选区离子注入形成N型阱区域，N型阱区域上设有N型欧姆接触上电极，N型欧姆接触上电极沿周边设有金属导电电极。
  2. 如权利要求1所述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，其特征在于：当为P型低掺外延层时，P型低掺外延层和N型衬底之间设有P型高掺外延层。
  3. 如权利要求1或2所述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，其特征在于：P型或N型阱区域的掺杂浓度高于1×10 17cm -3；P型或N型阱区域的深度低于1μm。
  4. 如权利要求1或2所述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，其特征在于：P型或N型阱区域在N型或P型低掺外延层表面呈间隔性分布；P型或N型欧姆接触上电极设在P型或N型阱区域上、且P型或N型欧姆接触上电极的宽度小于P型或N型阱区域的宽度。
  5. 如权利要求4所述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，其特征在于：P型或N型阱区域的填充因子为10～90％；P型或N型阱区域和P型或N型欧姆接触上电极呈相互对应的栅条状、网格状或环状。
  6. 如权利要求1或2所述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，其特征在于：N型或P型低掺外延层的材料为碳化硅，N型或P型低掺外延层的掺杂浓度小于1×10 16cm -3，N型或P型低掺外延层的厚度大于1μm；N型衬底的材料为碳化硅，掺杂浓度为1×10 18cm -3～1×10 20cm -3。
  7. 如权利要求1或2所述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，其特征在于：N型欧姆接触下电极的材料为镍、钛、铝或金中的至少一种；P型或N型欧姆接触上电极的材料为镍、钛、铝或金中的至少一种；金属导电电极的材料为钛或金中的至少一种，金属导电电极的总厚度至少为1μm。
  8. 如权利要求7所述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器，其特征在于：N型欧姆接触下电极包括从下到上依次相接的镍层、钛层、铝层和金层；P 型或N型欧姆接触上电极为镍层；金属导电电极包括从下到上依次相接的钛层和金层。
  9. 权利要求1-8任意一项所述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的制备方法，其特征在于：包括顺序相接的如下步骤：
    1)在N型衬底上表面外延生长N型或P型低掺外延层；
    2)在N型或P型低掺外延层上淀积掩模层，进而在掩模层上旋涂光刻胶，并通过曝光显影形成光刻胶图案定义离子注入掩模区域；
    3)以光刻胶图案为掩模刻蚀掩模层，在N型或P型低掺外延层表面形成离子注入掩模；
    4)在N型或P型低掺外延层表面进行选区离子注入形成P型或N型阱区域，热退火处理激活杂质；
    5)在N型衬底下表面淀积N型欧姆接触下电极，进行高温退火，形成N型欧姆接触；
    6)在N型或P型低掺外延层表面旋涂光刻胶，依据曝光显影得到的光刻图形，在选区离子注入形成的P型或N型阱区域淀积P型或N型欧姆接触上电极，高温退火，形成P型或N型欧姆接触；
    7)在P型或N型欧姆接触上电极边缘位置淀积金属导电电极，完成基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的制备。
  10. 如权利要求9所述的基于选区离子注入的新型碳化硅基横向PN结极紫外探测器的制备方法，其特征在于：制备呈间隔性分布的P型或N型阱区域：
    步骤1)中，当低掺外延层为P型低掺外延层时，先在N型衬底上表面外延生长P型高掺外延层，再在P型高掺外延层上外延生长P型低掺外延层；
    步骤3)中，依据曝光显影得到的光刻图形，间隔性地刻蚀掉N型或P型低掺外延层上的掩模层，使N型或P型低掺外延层上的部分区域保留掩模层作为离子注入掩模；
    步骤4)中，在刻蚀掉掩模层的N型或P型低掺外延层上经P型或N型离子注入形成呈间隔性分布的P型或N型阱区域，N型或P型低掺外延层表面保留掩模层的区域为有源吸收区；
    步骤6)中，在呈间隔性分布的P型或N型阱区域上沿P型或N型阱区域的走向淀积不超出P型或N型阱区域的P型或N型欧姆接触上电极。
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