Al2O3 extreme ultraviolet detector with 13.5 nm wavelength detection capability and preparation method and application thereof

Abstract

The invention discloses an Al2O3 extreme ultraviolet detector with 13.5 nm wavelength detection capability as well as a preparation method and application of the Al2O3 extreme ultraviolet detector. The Al2O3 extreme ultraviolet detector comprises a substrate, a Si-doped Al2O3 epitaxial layer and interdigital electrodes, wherein the substrate, the Si-doped Al2O3 epitaxial layer and the interdigital electrodes are sequentially arranged from bottom to top, and the interdigital electrodes are located at the two ends of the Si-doped Al2O3 epitaxial layer respectively. The substrate is a sapphire substrate; the thickness of the Si-doped Al2O3 epitaxial layer is 100-5000 nm, and the Si doping concentration is 1 * 10 < 16 >-1 * 10 < 20 > cm <-3 >. Compared with other extreme ultraviolet detectors, high quantum efficiency, visible light blind characteristic, low dark current and radiation resistance of 13.5 nm wavelength light detection are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic devices, and in particular to an Al2O3 extreme ultraviolet detector with 13.5 nm wavelength detection capability, a preparation method thereof and applications thereof. Background Art

[0002] As semiconductor lithography technology evolves to process nodes below 7 nm, extreme ultraviolet (EUV, 13.5 nm wavelength) lithography has become a key core technology, and highly sensitive and stable EUV detectors are the core components of real-time energy monitoring and beam calibration of lithography machines. At the same time, the EUV band is indispensable in astronomical observations (such as solar flare monitoring) and high-energy physics experiments (such as plasma diagnosis).

[0003] At present, mainstream EUV detectors are mainly based on silicon (Si) and silicon carbide (SiC) material systems, but their performance has the following limitations: the narrow bandgap of silicon (1.12 eV) makes it sensitive to visible light, requiring additional filters to suppress background noise, and the high dark current requires active cooling (such as thermoelectric cooling), which makes the system complex. The lattice is easily damaged under the irradiation of high-energy particles (such as protons), and the quantum efficiency (QE) decays significantly, making it difficult to meet the needs of long-term space missions. The price of SiC single crystal substrates is much higher than that of silicon, and the heteroepitaxial process is complex, with the device cost being more than 5 times that of silicon. The wide bandgap of SiC (~3.26 eV) causes the absorption coefficient to be lower than that of silicon in the EUV band, and it is necessary to rely on a thick absorption layer (micrometer level) to compensate for the efficiency, and the dynamic response speed is limited (microsecond level).

[0004] Existing EUV detectors have the pain points of being unable to achieve both quantum efficiency and visible light suppression, and being difficult to balance radiation resistance and cost. Therefore, there is an urgent need for an EUV detector based on a new material system and preparation process that takes into account high response, low noise, radiation resistance and low manufacturing cost to meet the high-end needs of lithography machines, space science and other fields. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an Al2O3 extreme ultraviolet detector with 13.5 nm wavelength detection capability and its preparation method and application. The present invention uses Si-doped Al2O3 on a sapphire substrate as an epitaxial layer, and evaporates metal thereon to prepare a metal-semiconductor-metal (MSM) structure, and successfully realizes a high-performance, low-cost extreme ultraviolet detector by regulating carrier mobility through high-concentration doping, optimizing photocurrent collection efficiency through interdigital electrodes, and designing a fully visible light blind structure. Compared with other extreme ultraviolet detectors, the present invention achieves high quantum efficiency, visible light blind characteristics, low dark current, and radiation resistance for 13.5 nm wavelength light detection.

[0006] To achieve the above object, the technical solution designed by the present invention is as follows: The present invention provides an Al2O3 extreme ultraviolet detector with a detection ability of 13.5 nm wavelength. The Al2O3 extreme ultraviolet detector includes a substrate, a Si-doped Al2O3 epitaxial layer arranged successively from bottom to top, and interdigital electrodes located at both ends of the Si-doped Al2O3 epitaxial layer respectively.

[0007] Further, the substrate is a sapphire substrate or a Si substrate; The thickness of the Si-doped Al2O3 epitaxial layer is 100 - 5000 nm, and the Si doping concentration is 1×10 16 ~1×10 20 cm -3 。

[0008] Still further, the substrate is a sapphire substrate; The thickness of the Si-doped Al2O3 epitaxial layer is 700 nm, and the Si doping concentration is 1×10 18 cm -3 。

[0009] Still further, the interdigital electrode is a Ni and Au metal layer arranged successively from bottom to top, and the thickness ratio of Ni and Au is 1∶2 - 4; The thickness of the interdigital electrode is 50 - 1000 nm, the interdigital width is 5 - 20 μm, the interdigital spacing is 5 - 40 μm, and the number of interdigital pairs is 5 - 20.

[0010] Still further, the thickness ratio of Ni and Au is 1∶2; the thickness of the interdigital electrode is 700 nm, the interdigital width is 5 μm, the interdigital spacing is 40 μm, and the number of interdigital pairs is 5.

[0011] The present invention also provides a preparation method for an Al2O3 extreme ultraviolet detector with a detection ability of 13.5 nm wavelength, including the following steps: S1: Ultrasonically clean the substrate; S2: Prepare a Si-doped Al2O3 epitaxial layer on the surface of the substrate; S3: Use lithography technology to define the interdigital electrode region on the surface of the Si-doped Al2O3 epitaxial layer, and perform exposure and development; S4: Etch in the interdigital electrode region using lithography technology to form an interdigital electrode pattern, and treat the residual glue of the interdigital electrode pattern with oxygen plasma; S5: Evaporate Ni and Au metal layers successively in the interdigital electrode pattern region by electron beam evaporation technology or physical vapor deposition technology to form a Ni / Au metal layer; S6: Wash away the photoresist, form interdigital electrodes on the surface of the Si-doped Al2O3 epitaxial layer, and obtain an Al2O3 extreme ultraviolet detector with a detection ability at a wavelength of 13.5 nm.

[0012] Further, in the step S1, the specific steps of ultrasonic cleaning are as follows: Place the substrate in acetone, absolute ethanol, and water in sequence and ultrasonically clean for 5 - 6 minutes, and then place it in a piranha solution and ultrasonically clean for 3 - 4 minutes.

[0013] Still further, in the step S2, the method for preparing the Si-doped Al2O3 epitaxial layer is to use any one of metalorganic chemical vapor deposition technology, hydride vapor epitaxy technology, spray chemical vapor deposition technology, and pulsed laser deposition technology, use silane as the silicon source and trimethylaluminum as the alumina source, and prepare the Si-doped Al2O3 epitaxial layer under the protection of hydrogen or nitrogen; In the step S4, the radio frequency power of the oxygen plasma treatment is 40 - 45 W, and the treatment time is 2 - 3 min.

[0014] Still further, the substrate is a sapphire substrate or a Si substrate; the thickness of the Si-doped Al2O3 epitaxial layer is 100 - 5000 nm, and the Si doping concentration is 1×10 16 ~1×10 20 cm -3 ; The thickness ratio of the Ni and Au metal layers is 1∶2 - 4; The thickness of the interdigital electrodes is 50 - 1000 nm, the interdigital width is 5 - 20 μm, the interdigital spacing is 5 - 40 μm, and the number of interdigital pairs is 5 - 20.

[0015] The present invention also provides an application of the above-mentioned Al2O3 extreme ultraviolet detector in the preparation of a semiconductor lithography machine.

[0016] The principle of the present invention: Aluminum oxide (Al2O3), as an ultra-wide bandgap material with a bandgap width of 9 eV, theoretically has an extremely high absorption coefficient for photons with a wavelength of 13.5 nm, which can reduce the recombination of carriers in the body and improve the quantum efficiency (QE); the cut-off wavelength of Al2O3 is 140 nm, and it is completely transparent to light with a wavelength > 140 nm (such as visible light and infrared), and can completely suppress ultraviolet-visible light crosstalk without adding an external filter, having the characteristic of being blind to visible light in the whole wavelength range; the melting point of Al2O3 is as high as 2054 °C, and it can still maintain a low defect density at high temperatures, avoiding the decline of device performance due to thermal stress. In addition, the chemical bond binding energy of Al2O3 is as high as 512 kJ / mol, and the atomic displacement threshold is 25 eV, far higher than 12 eV of Si and 21 eV of SiC, and can resist the bombardment of high-energy particles (such as protons and electrons), having great application potential in electrical and optical devices. Therefore, by combining the comprehensive characteristics of ultra-wide bandgap, strong light absorption and resistance to extreme environments, based on the Al2O3 extreme ultraviolet detector, the deep integration of high performance (high QE, low noise) and robustness (radiation resistance, high temperature resistance) can be achieved simultaneously, providing key device support for advanced manufacturing and cutting-edge scientific research.

[0017] Advantages of the present invention: 1. In the present invention, an Al2O3 epitaxial layer with a thickness of 50 - 1000 nm and a Si doping concentration of 1×10 16 ~1×10 20 cm -3 is epitaxially grown on an m-plane sapphire substrate. SiH4 is introduced as a silicon source in the process, and by adjusting the ratio of Si 4+ substituting Al 3+ in the Al2O3 lattice, a shallow donor energy level is formed, and the on-state carrier concentration can be adjusted by controllable Si doping, significantly improving the carrier mobility.

[0018] 2. The Al2O3 extreme ultraviolet detector prepared by the present invention can efficiently absorb photons through the strong internal photoelectric effect, and the absorption coefficient (at a wavelength of 13.5 nm) is 3 times that of Si and 30 times that of SiC, thereby reducing the recombination of carriers in the body and improving the quantum efficiency (QE).

[0019] 3. The Al2O3 extreme ultraviolet detector prepared by the present invention has a good response to extreme ultraviolet light with a wavelength of 13.5 nm, and has the characteristic of being blind to visible light in the whole wavelength range, and can completely suppress ultraviolet-visible light crosstalk without adding an external filter, and is especially suitable for the detection of pure EUV signals in complex spectral environments (such as stray light sources in lithography machines or multi-band radiation in solar observations).

[0020] 4. The Al2O3 extreme ultraviolet detector prepared by the present invention can still maintain a low defect density at high temperatures (>500 °C), avoiding the degradation of device performance caused by thermal stress, and can resist the bombardment of high-energy particles (such as protons and electrons), significantly extending the service life of the device.

[0021] 5. The MSM structure of the Al2O3 extreme ultraviolet detector prepared by the present invention greatly shortens the transit time of photo-generated carriers to achieve high-speed response, and the process is simple without the complex doping process of PN junctions (such as diffusion or ion implantation). The device can be fabricated only by photolithography and metal deposition, adapting to the flat surface characteristics of the alumina MOCVD homoepitaxial layer, reducing the manufacturing cost and process complexity, and facilitating batch preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 FIG. is a schematic structural diagram of an Al2O3 extreme ultraviolet detector with a detection ability of 13.5 nm wavelength; In the figure, 1 is a substrate; 2 is an Si-doped Al2O3 epitaxial layer; 3 is an interdigital electrode; Figure 2 FIG. is a schematic diagram of the relationship between the external quantum efficiency and wavelength of the device at 0 V of the Al2O3 extreme ultraviolet detector with a detection ability of 13.5 nm wavelength in Example 2 within the wavelength range of 5-140 nm; Figure 3 FIG. is a schematic diagram of different interdigital electrode spacings in Example 3; Figure 4 FIG. is a schematic diagram of the dark current change with voltage of the Al2O3 extreme ultraviolet detector with different interdigital electrode spacings; Figure 5 FIG. is a schematic diagram of the dark current change with voltage of the Al2O3 extreme ultraviolet detector with different Si doping concentrations; Figure 6 FIG. is a transmission electron microscope (TEM) image of homoepitaxial Si-doped Al2O3 on a sapphire substrate; Figure 7 FIG. is a schematic diagram of the low-frequency noise power spectrum of the Al2O3 extreme ultraviolet detector with a detection ability of 13.5 nm wavelength in Example 2 at 0 V. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention will be further described in detail below with reference to specific embodiments for the understanding of those skilled in the art.

[0024] Example 1 This example provides an Al2O3 extreme ultraviolet detector with a detection ability of 13.5 nm wavelength, combined with Figure 1As shown, the Al2O3 extreme ultraviolet detector includes a substrate 1, a Si-doped Al2O3 epitaxial layer 2 disposed sequentially from bottom to top, and interdigital electrodes 3 located at both ends of the Si-doped Al2O3 epitaxial layer, respectively.

[0025] In the Al2O3 extreme ultraviolet detector of this embodiment, the substrate 1 is a sapphire substrate or a Si substrate; the thickness of the Si-doped Al2O3 epitaxial layer 2 is 100 - 5000 nm, and the Si doping concentration is 1×10 16 ~1×10 20 cm -3 ; the interdigital electrodes 3 are Ni and Au metal layers disposed sequentially from bottom to top, and the thickness ratio of Ni to Au is 1∶2 - 4; the thickness of the interdigital electrodes 3 is 50 - 1000 nm, the interdigital width is 5 - 20 μm, the interdigital spacing is 5 - 40 μm, and the number of interdigital pairs is 5 - 20.

[0026] Preferably, the substrate 1 is a sapphire substrate; the thickness of the Si-doped Al2O3 epitaxial layer 2 is 700 nm, and the Si doping concentration is 1×10 18 cm -3 ; the thickness ratio of Ni to Au is 1∶2; the thickness of the interdigital electrodes 3 is 700 nm, the interdigital width is 5 μm, the interdigital spacing is 40 μm, and the number of interdigital pairs is 5.

[0027] Embodiment 2 As Figure 1 shown, this embodiment provides a method for preparing an Al2O3 extreme ultraviolet detector with a detection ability of 13.5 nm wavelength, including the following specific steps: S1. Use an m-plane sapphire substrate 1, place it in acetone, absolute ethanol, and water in sequence and ultrasonically clean it for 5 minutes, and then place it in a piranha solution and ultrasonically clean it for 3 minutes.

[0028] S2. Prepare a Si-doped Al2O3 epitaxial layer 2 on the substrate 1 by MOCVD technology (it can also be prepared by hydride vapor phase epitaxy technology, spray chemical vapor deposition technology, and pulsed laser deposition technology). The Si-doped Al2O3 epitaxial layer 2 is an Al2O3 epitaxial layer doped with Si, and the Si doping concentration is 1×10 18 cm -3 , use silane (SiH4) as the silicon source and trimethylaluminum (TMAl) as the aluminum source, and deposit it by metalorganic chemical vapor deposition (MOCVD) technology under the protection of hydrogen or nitrogen, and the deposition thickness is 700 nm. Perform TEM analysis on the Si-doped Al2O3 epitaxial layer 2, and the results are as Figure 6 shown. Only very few dislocations are observed in the cross-sectional TEM, and according to the single-crystal diffraction spots shown by selected area electron diffraction (SAED), there are no polycrystalline rings or twin spots, verifying that the epitaxial layer is single crystal and has a high crystal quality.

[0029] S3. Based on integrated circuit process technology, apply photoresist on the Si-doped Al2O3 epitaxial layer 2, define the interdigital electrode region, cover a mask on the regions other than the interdigital electrode region, and perform exposure and development steps on the interdigital electrode region.

[0030] S4. Etch the interdigital electrode region through EUV lithography technology to form an interdigital electrode pattern, and use oxygen plasma treatment to remove the residual photoresist of the interdigital electrode pattern. The treatment conditions are: radio frequency power is 40 W, and the treatment time is 2 - 3 min.

[0031] S5. Sequentially deposit Ni and Au metal layers on the interdigital electrode pattern region through electron beam evaporation technology or physical vapor deposition technology. The thickness ratio of Ni to Au is 1:2 to form a 700 nm Ni / Au metal layer.

[0032] S6. Wash off the photoresist, and form an interdigital electrode 3 on the surface of the Si-doped Al2O3 epitaxial layer 2. The finger width of the interdigital electrode 3 is 5 μm, the finger spacing is 40 μm, and the number of finger pairs is 5, obtaining an Al2O3 extreme ultraviolet detector with the detection ability of a 13.5 nm wavelength.

[0033] Analyze the relationship between the current and wavelength of the Al2O3 extreme ultraviolet detector in this embodiment under extreme ultraviolet light irradiation. The results are as Figure 2 shown. In the short wavelength range, the quantum efficiency of the detector increases as the wavelength decreases, and finally the quantum efficiency can exceed 100%. This is because high-energy EUV photons generate multiple electron-hole pairs, demonstrating the feasibility of the Al2O3 extreme ultraviolet detector in this embodiment in the EUV detection field.

[0034] Analyze the low-frequency noise power of the Al2O3 extreme ultraviolet detector in this embodiment at 0 V. The results are as Figure 7 shown. The noise power density spectrum of the Al2O3 extreme ultraviolet detector conforms to the 1 / f noise characteristic, and at the same time indicates that the detector has good noise performance and high detection rate for extreme ultraviolet signals.

[0035] Example 3 This embodiment provides a preparation method for an Al2O3 extreme ultraviolet detector with the detection ability of a 13.5 nm wavelength. Its preparation steps are the same as those in Example 2, except that the interdigital electrode spacing is different. For example, Figure 3As shown, the different interdigital electrode spacings are 5 μm, 10 μm, 20 μm, and 30 μm respectively. An Al2O3 extreme ultraviolet detector with an interdigital electrode spacing of 5 μm, an Al2O3 extreme ultraviolet detector with an interdigital electrode spacing of 10 μm, an Al2O3 extreme ultraviolet detector with an interdigital electrode spacing of 20 μm, and an Al2O3 extreme ultraviolet detector with an interdigital electrode spacing of 30 μm are obtained in sequence.

[0036] The dark currents of the above-mentioned Al2O3 extreme ultraviolet detectors with different interdigital electrode spacings and the Al2O3 extreme ultraviolet detector of Example 2 were analyzed with respect to the change with voltage. The results are as Figure 4 shown. The dark current of the Al2O3 extreme ultraviolet detector of the present invention decreases as the interdigital electrode spacing increases. When the interdigital electrode spacing is 40 μm and an external bias voltage of 100 V is applied, the dark current is lower than 5×10 13 A.

[0037] Example 4 This example provides a method for preparing an Al2O3 extreme ultraviolet detector with a detection ability at a wavelength of 13.5 nm. The preparation steps are the same as those of Example 2, except that the Si-doped Al2O3 epitaxial layer 2 has different Si doping concentrations, which are 1×10 19 cm -3 and 1×10 20 cm -3 respectively. An Al2O3 extreme ultraviolet detector (E19) with a Si doping concentration of 1×10 19 cm -3 and an Al2O3 extreme ultraviolet detector (E20) with a Si doping concentration of 1×10 20 cm -3 are obtained in sequence.

[0038] The dark currents of the above-mentioned Al2O3 extreme ultraviolet detectors with different Si doping concentrations and the Al2O3 extreme ultraviolet detector (E18) of Example 2 were analyzed with respect to the change with voltage. The results are as Figure 5 shown. The dark current of the prepared Al2O3 extreme ultraviolet detector with a detection ability at a wavelength of 13.5 nm decreases as the Si doping concentration increases. When the doping concentration increases, the increase in intrinsic impurities or defects leads to a decrease in current.

[0039] Other parts not described in detail are all prior arts. Although the above examples have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. People can also obtain other embodiments without creative efforts based on this example, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An Al2O3 extreme ultraviolet detector with a detection ability of 13.5 nm wavelength, characterized in that: The Al2O3 extreme ultraviolet detector includes a substrate (1), an Si-doped Al2O3 epitaxial layer (2), and interdigital electrodes (3) located at both ends of the Si-doped Al2O3 epitaxial layer, which are arranged in sequence from bottom to top.

2. The Al2O3 extreme ultraviolet detector according to claim 1, wherein: The substrate (1) is a sapphire substrate or an Si substrate; The thickness of the Si-doped Al2O3 epitaxial layer (2) is 100 to 5000 nm, and the Si doping concentration is 1×10 16 ~1×10 20 cm -3 .

3. The Al2O3 extreme ultraviolet detector according to claim 2, characterized in that: The substrate (1) is a sapphire substrate; The thickness of the Si-doped Al2O3 epitaxial layer (2) is 700 nm, and the Si doping concentration is 1×10 18 cm -3 .

4. The Al2O3 extreme ultraviolet detector according to claim 1, characterized in that: The interdigital electrode (3) is a Ni and Au metal layer arranged in sequence from bottom to top, and the thickness ratio of Ni to Au is 1:2 - 4; The thickness of the interdigital electrode (3) is 50 - 1000 nm, the interdigital width is 5 - 20 μm, the interdigital spacing is 5 - 40 μm, and the number of interdigital pairs is 5 - 20.

5. The Al2O3 extreme ultraviolet detector according to claim 4, wherein: The thickness ratio of Ni to Au is 1:2; The thickness of the interdigital electrode (3) is 700 nm, the interdigital width is 5 μm, the interdigital spacing is 40 μm, and the number of interdigital pairs is 5.

6. A method for preparing an Al2O3 extreme ultraviolet detector with a detection ability at a wavelength of 13.5 nm, characterized in that: It includes the following steps: S1: Ultrasonically clean the substrate (1); S2: Prepare the Si-doped Al2O3 epitaxial layer (2) on the surface of the substrate (1); S3: Use photolithography technology to define the interdigital electrode area on the surface of the Si-doped Al2O3 epitaxial layer (2), and perform exposure and development; S4: Etch in the interdigital electrode area using photolithography technology to form an interdigital electrode pattern, and use oxygen plasma to treat the residual glue of the interdigital electrode pattern; S5: Sequentially deposit Ni and Au metal layers in the interdigital electrode pattern area by electron beam evaporation technology or physical vapor deposition technology to form a Ni / Au metal layer; S6: Wash off the photoresist, and form interdigital electrodes (3) on the surface of the Si-doped Al2O3 epitaxial layer (2) to obtain an Al2O3 extreme ultraviolet detector with a detection ability at a wavelength of 13.5 nm.

7. The preparation method according to claim 6, characterized in that: In the step S1, the specific steps of ultrasonic cleaning are: Place the substrate (1) in acetone, absolute ethanol, and water in sequence and ultrasonically clean for 5 - 6 minutes, and then place it in a piranha solution and ultrasonically clean for 3 - 4 minutes.

8. The preparation method according to claim 6, characterized in that: In the step S2, the method for preparing the Si-doped Al2O3 epitaxial layer (2) is to use any one of metalorganic chemical vapor deposition technology, hydride vapor epitaxy technology, spray chemical vapor deposition technology, and pulsed laser deposition technology, use silane as the silicon source and trimethylaluminum as the aluminum oxide source, and prepare the Si-doped Al2O3 epitaxial layer (2) under the protection of hydrogen or nitrogen; In the step S4, the radio frequency power of the oxygen plasma treatment is 40 - 45 W, and the treatment time is 2 - 3 min.

9. The preparation method according to claim 6, characterized in that: The substrate (1) is a sapphire substrate or an Si substrate; the thickness of the Si-doped Al2O3 epitaxial layer (2) is 100 - 5000 nm, and the Si doping concentration is 1×10 16 ~1×10 20 cm -3 ; The thickness ratio of the Ni and Au metal layers is 1:2 - 4; the thickness of the interdigital electrode (3) is 50 - 1000 nm, the interdigital width is 5 - 20 μm, the interdigital spacing is 5 - 40 μm, and the number of interdigital pairs is 5 - 20.

10. Application of the Al2O3 extreme ultraviolet detector according to any one of claims 1 - 5 in the preparation of a semiconductor lithography machine.

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