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

Abstract

The present invention discloses an Al2O3 extreme ultraviolet detector capable of detecting wavelengths up to 13.5 nm, as well as its preparation method and application. The Al2O3 extreme ultraviolet detector comprises, arranged from bottom to top, a substrate, a Si-doped Al2O3 epitaxial layer, and interdigital electrodes located at both ends of the Si-doped Al2O3 epitaxial layer. The substrate is a sapphire substrate; the Si-doped Al2O3 epitaxial layer has a thickness of 100 to 5000 nm, and the Si doping concentration is 1×10 16 ~1×10 20 cm ‑3 Compared with other extreme ultraviolet detectors, the present invention achieves high quantum efficiency for 13.5 nm wavelength light detection, visible light blindness, low dark current and radiation resistance.

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 evolves to process nodes below 7 nm, extreme ultraviolet (EUV, 13.5 nm wavelength) lithography has become a key core technology. Highly sensitive and stable EUV detectors are essential components for real-time energy monitoring and beam alignment in lithography machines. Furthermore, the EUV band is indispensable in astronomical observations (such as solar flare monitoring) and high-energy physics experiments (such as plasma diagnostics).

[0003] Currently, mainstream EUV detectors are primarily based on silicon (Si) and silicon carbide (SiC) material systems, but their performance is limited. Silicon's narrow bandgap (1.12 eV) makes it sensitive to visible light, requiring additional filters to suppress background noise. Furthermore, its high dark current requires active cooling (such as thermoelectric cooling), resulting in high system complexity. The crystal lattice is easily damaged by irradiation with high-energy particles (such as protons), leading to significant quantum efficiency (QE) degradation, making it difficult to meet the requirements of long-term space missions. SiC single-crystal substrates are significantly more expensive than silicon, and the heteroepitaxial growth process is complex, resulting in device costs that are more than five times that of silicon-based substrates. SiC's wide bandgap (~3.26 eV) results in a lower absorption coefficient than silicon in the EUV band, requiring the use of thick absorber layers (on the micrometer scale) to compensate for this efficiency, resulting in a limited dynamic response speed (on the microsecond scale).

[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 fields such as lithography machines and space science. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the existing technology by providing an Al2O3 extreme ultraviolet (EUV) detector capable of detecting light at a wavelength of 13.5 nm, as well as its preparation method and application. This invention utilizes Si-doped Al2O3 as an epitaxial layer on a sapphire substrate, and then deposits metal thereon to create a metal-semiconductor-metal (MSM) structure. By utilizing high-concentration doping to control carrier mobility, interdigitated electrodes to optimize photocurrent collection efficiency, and a fully visible-light-blind structure design, this device successfully achieves a high-performance, low-cost EUV detector. Compared to other EUV detectors, this device achieves high quantum efficiency for 13.5 nm wavelength detection, visible-light-blind properties, low dark current, and radiation resistance.

[0006] To achieve the above purpose, the technical solution designed by the present invention is as follows:

[0007] The present invention provides an Al2O3 extreme ultraviolet detector with a 13.5 nm wavelength detection capability. The Al2O3 extreme ultraviolet detector comprises a substrate, a Si-doped Al2O3 epitaxial layer, and interdigital electrodes respectively located at both ends of the Si-doped Al2O3 epitaxial layer, which are sequentially arranged from bottom to top.

[0008] Furthermore, the substrate is a sapphire substrate or a Si substrate;

[0009] 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 .

[0010] Furthermore, the substrate is a sapphire substrate;

[0011] The thickness of the Si-doped Al2O3 epitaxial layer is 700 nm, and the Si doping concentration is 1×10 18 cm -3 .

[0012] Furthermore, the interdigital electrodes are Ni and Au metal layers arranged sequentially from bottom to top, and the thickness ratio of Ni to Au is 1:2-4;

[0013] 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.

[0014] Furthermore, the thickness ratio of Ni to 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.

[0015] The present invention also provides a method for preparing an Al2O3 extreme ultraviolet detector with a 13.5 nm wavelength detection capability, comprising the following steps:

[0016] S1: ultrasonic cleaning of the substrate;

[0017] S2: Prepare Si-doped Al2O3 epitaxial layer on the substrate surface;

[0018] S3: Using photolithography technology, define the interdigital electrode area on the surface of the Si-doped Al2O3 epitaxial layer, and perform exposure and development;

[0019] S4: etching the interdigital electrode region using a photolithography technique to form an interdigital electrode pattern, and treating residual adhesive in the interdigital electrode pattern using oxygen plasma;

[0020] S5: sequentially depositing Ni and Au metal layers on the interdigital electrode pattern region by electron beam evaporation technology or physical vapor deposition technology to form a Ni / Au metal layer;

[0021] S6: The photoresist is washed away, and interdigital electrodes are formed on the surface of the Si-doped Al2O3 epitaxial layer to obtain an Al2O3 extreme ultraviolet detector with a detection capability of 13.5 nm wavelength.

[0022] Furthermore, in step S1, the specific steps of ultrasonic cleaning are: placing the substrate in acetone, anhydrous ethanol, and water in sequence for ultrasonic cleaning for 5 to 6 minutes, and then placing it in piranha solution for ultrasonic cleaning for 3 to 4 minutes.

[0023] Furthermore, in step S2, the method for preparing the Si-doped Al2O3 epitaxial layer is to use any one of metal organic chemical vapor deposition technology, hydride vapor phase epitaxy technology, spray chemical vapor deposition technology and pulsed laser deposition technology, using silane as a silicon source and trimethylaluminum as an aluminum oxide source, to prepare the Si-doped Al2O3 epitaxial layer under hydrogen or nitrogen protection;

[0024] In step S4, the radio frequency power of the oxygen plasma treatment is 40-45 W, and the treatment time is 2-3 min.

[0025] Furthermore, 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 ;

[0026] The thickness ratio of the Ni and Au metal layers is 1:2-4;

[0027] 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.

[0028] The present invention also provides an application of the Al2O3 extreme ultraviolet detector in the preparation of a semiconductor lithography machine.

[0029] Principle of the present invention:

[0030] Aluminum oxide (Al2O3) is an ultra-wide bandgap material with a bandgap of 9 eV. Its theoretical absorption coefficient for photons with a wavelength of 13.5 nm is extremely high, which can reduce carrier recombination in the material and improve quantum efficiency (QE). With a cutoff wavelength of 140 nm, Al2O3 is completely transparent to light with wavelengths greater than 140 nm (such as visible light and infrared), completely suppressing UV-visible light crosstalk without the need for external filters, exhibiting full-band visible light blindness. Al2O3 has a melting point of 2054°C and maintains a low defect density even at high temperatures, preventing device performance degradation due to thermal stress. Furthermore, Al2O3 has a chemical bond energy of 512 kJ / mol and an atomic displacement threshold of 25 eV, far exceeding the 12 eV of Si and 21 eV of SiC. This makes it resistant to bombardment by high-energy particles (such as protons and electrons), and it has great potential for application in electrical and optical devices. Therefore, by combining the comprehensive characteristics of ultra-wide bandgap, strong light absorption and resistance to extreme environments, the Al2O3 extreme ultraviolet detector can simultaneously achieve a deep fusion of high performance (high QE, low noise) and robustness (radiation resistance, high temperature resistance), providing key device support for advanced manufacturing and cutting-edge scientific research.

[0031] Beneficial effects of the present invention:

[0032] 1. The present invention adopts epitaxial growth of 50-1000 nm thick Si doping concentration 1×10 16 ~1×10 20 cm -3 Al2O3 epitaxial layer, SiH4 is introduced as silicon source in the process, by adjusting the Si 4+ Replace Al 3+ The ratio of Si to Si is reduced to form a shallow donor energy level. Through controllable Si doping, the on-state carrier concentration can be adjusted, which significantly improves the carrier mobility.

[0033] 2. The Al2O3 extreme ultraviolet detector prepared by the present invention can efficiently absorb photons through a strong internal photoelectric effect. The absorption coefficient (at a wavelength of 13.5 nm) is 3 times that of Si and 30 times that of SiC, thereby reducing carrier recombination in the body and improving quantum efficiency (QE).

[0034] 3. The Al2O3 extreme ultraviolet detector prepared by the present invention has a good response to 13.5 nm extreme ultraviolet light and has a full-band visible light blindness characteristic. It can completely suppress ultraviolet-visible light crosstalk without adding external filters. It is particularly suitable for pure EUV signal detection in complex spectral environments (such as stray light sources in lithography machines or multi-band radiation in solar observations).

[0035] 4. The Al2O3 extreme ultraviolet detector prepared by the present invention can still maintain a low defect density at high temperatures (>500°C) to avoid device performance degradation due to thermal stress, and can resist bombardment by high-energy particles (such as protons and electrons), significantly extending the service life of the device.

[0036] 5. The MSM structure of the Al2O3 extreme ultraviolet detector prepared by the present invention greatly shortens the transit time of photogenerated carriers to achieve high-speed response. In addition, the process is simple and does not require complex doping processes of PN junctions (such as diffusion or ion implantation). The device can be prepared only by photolithography and metal deposition. It adapts to the flat surface characteristics of the alumina MOCVD homoepitaxial layer, reduces manufacturing costs and process complexity, and facilitates batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the structure of the Al2O3 extreme ultraviolet detector with 13.5 nm wavelength detection capability;

[0038] In the figure, 1, substrate; 2, Si-doped Al2O3 epitaxial layer; 3, interdigitated electrodes;

[0039] Figure 2 Schematic diagram of the relationship between the external quantum efficiency of the Al2O3 extreme ultraviolet detector with 13.5 nm wavelength detection capability at 0 V and wavelength in the wavelength range of 5 to 140 nm in Example 2;

[0040] Figure 3 Schematic diagram of different interdigital electrode spacings in Example 3;

[0041] Figure 4 Schematic diagram of the dark current variation with voltage of Al2O3 extreme ultraviolet detectors with different interdigital electrode spacings;

[0042] Figure 5 Schematic diagram of the dark current variation with voltage of Al2O3 extreme ultraviolet detectors with different Si doping concentrations;

[0043] Figure 6 Transmission electron microscope (TEM) image of homoepitaxial Si-doped Al2O3 on sapphire substrate;

[0044] Figure 7 Schematic diagram of the low-frequency noise power spectrum at 0 V of the Al2O3 extreme ultraviolet detector with 13.5 nm wavelength detection capability in Example 2. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below with reference to specific embodiments so that those skilled in the art can understand.

[0046] Example 1

[0047] This embodiment provides an Al2O3 extreme ultraviolet detector with 13.5 nm wavelength detection capability, combined with Figure 1 As shown, the Al2O3 extreme ultraviolet detector includes a substrate 1, a Si-doped Al2O3 epitaxial layer 2 and interdigital electrodes 3 respectively located at both ends of the Si-doped Al2O3 epitaxial layer, which are arranged in sequence from bottom to top.

[0048] 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 arranged sequentially from bottom to top, with a thickness ratio of Ni to Au of 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.

[0049] 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 and 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.

[0050] Example 2

[0051] like Figure 1 As shown, this embodiment provides a method for preparing an Al2O3 extreme ultraviolet detector with a 13.5 nm wavelength detection capability, comprising the following specific steps:

[0052] S1. An m-plane sapphire substrate 1 is placed in acetone, anhydrous ethanol, and water for ultrasonic cleaning for 5 minutes, and then placed in piranha solution for ultrasonic cleaning for 3 minutes.

[0053] 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 -3Silane (SiH4) was used as the silicon source and triethylaluminum (TMAl) as the aluminum source. Metal organic chemical vapor deposition (MOCVD) was used under hydrogen or nitrogen protection to deposit the Si-doped Al2O3 epitaxial layer 2 to a thickness of 700 nm. TEM analysis of the Si-doped Al2O3 epitaxial layer 2 showed the following results: Figure 6 As shown, only very few dislocations were observed in the cross-sectional TEM, and the single crystal diffraction spots shown by selected area electron diffraction (SAED) showed no polycrystalline rings or twin spots, verifying that the epitaxial layer was a single crystal with high crystalline quality.

[0054] S3. Based on integrated circuit process technology, photoresist is applied on the Si-doped Al2O3 epitaxial layer 2 to define the interdigital electrode region, a mask is covered on the region outside the interdigital electrode region, and exposure and development steps are performed in the interdigital electrode region.

[0055] S4. Etching the interdigital electrode region by EUV lithography to form an interdigital electrode pattern, and removing residual adhesive from the interdigital electrode pattern by oxygen plasma treatment. The treatment conditions are: RF power of 40 W, and treatment time of 2 to 3 minutes.

[0056] S5. Ni and Au metal layers are sequentially deposited on the interdigital electrode pattern region by electron beam evaporation technology or physical vapor deposition technology, with a thickness ratio of Ni to Au being 1:2, to form a 700 nm Ni / Au metal layer.

[0057] S6. The photoresist is washed away, and an interdigital electrode 3 is formed on the surface of the Si-doped Al2O3 epitaxial layer 2. The interdigital width of the interdigital electrode 3 is 5 μm, the interdigital spacing is 40 μm, and the number of interdigital pairs is 5, thereby obtaining an Al2O3 extreme ultraviolet detector with a detection capability of 13.5 nm wavelength.

[0058] The relationship between the current and wavelength of the Al2O3 extreme ultraviolet detector of this embodiment under extreme ultraviolet light irradiation is analyzed, and the results are as follows: Figure 2 As shown, in the short wavelength range, the quantum efficiency of the detector increases as the wavelength decreases, and the final 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 of this embodiment in the field of EUV detection.

[0059] The low-frequency noise power of the Al2O3 extreme ultraviolet detector of this embodiment at 0 V is analyzed, and the results are as follows: Figure 7 As shown in the figure, the noise power density spectrum of the Al2O3 extreme ultraviolet detector conforms to the 1 / f noise characteristics, and it also shows that the detector has good noise performance and high detection rate for extreme ultraviolet signals.

[0060] Example 3

[0061] This embodiment provides a method for preparing an Al2O3 extreme ultraviolet detector with a 13.5 nm wavelength detection capability. The preparation steps are the same as those in Example 2, except that different interdigital electrode spacings are used, such as Figure 3 As shown in the figure, the different interdigital electrode spacings are 5 μm, 10 μm, 20 μm and 30 μm, respectively, and the Al2O3 extreme ultraviolet detector with an interdigital electrode spacing of 5 μm, the Al2O3 extreme ultraviolet detector with an interdigital electrode spacing of 10 μm, the Al2O3 extreme ultraviolet detector with an interdigital electrode spacing of 20 μm and the Al2O3 extreme ultraviolet detector with an interdigital electrode spacing of 30 μm are obtained in turn.

[0062] The dark current of the Al2O3 extreme ultraviolet detector with different interdigital electrode spacing and the Al2O3 extreme ultraviolet detector of Example 2 was analyzed as a function of voltage. Figure 4 As shown in the figure, the dark current of the Al2O3 extreme ultraviolet detector of the present invention decreases with the increase of the interdigital electrode spacing. When the interdigital electrode spacing is 40 μm, the dark current is less than 5×10 13 A.

[0063] Example 4

[0064] This embodiment provides a method for preparing an Al2O3 extreme ultraviolet detector with a 13.5 nm wavelength detection capability. The preparation steps are the same as those in 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 , and the Si doping concentration is 1×10 19 cm -3 Al2O3 extreme ultraviolet detector (E19) with Si doping concentration of 1×10 20 cm -3 Al2O3 extreme ultraviolet detector (E20).

[0065] The dark current of the Al2O3 extreme ultraviolet detectors with different Si doping concentrations and the Al2O3 extreme ultraviolet detector (E18) of Example 2 was analyzed as a function of voltage. Figure 5 As shown in the figure, the dark current of the prepared Al2O3 extreme ultraviolet detector with 13.5 nm wavelength detection capability decreases with the increase of Si doping concentration. When the doping concentration increases, the intrinsic impurities or defects increase, resulting in a decrease in current.

[0066] Although the above embodiments have been described in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on this embodiment without inventiveness, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. An Al2O3 extreme ultraviolet detector capable of detecting 13.5 nm wavelength, characterized by: The Al2O3 extreme ultraviolet detector is composed of a substrate (1), a Si-doped Al2O3 epitaxial layer (2), and interdigital electrodes (3) respectively located at two ends of the Si-doped Al2O3 epitaxial layer, which are arranged in sequence from bottom to top; 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 .

2. The Al2O3 extreme ultraviolet detector according to claim 1, characterized in that: The substrate (1) is a sapphire substrate or a Si substrate.

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 electrodes (3) are Ni and Au metal layers arranged sequentially from bottom to top, with a thickness ratio of Ni to Au being 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, characterized in that: The thickness ratio of Ni to Au is 1:2; The thickness of the interdigitated electrode (3) is 700 nm, the interdigitated width is 5 μm, the interdigitated spacing is 40 μm, and the number of interdigitated pairs is 5.

6. A method for preparing an Al2O3 extreme ultraviolet detector capable of detecting a wavelength of 13.5 nm, characterized in that: The following steps are involved: S1: ultrasonically cleaning the substrate (1); S2: preparing a Si-doped Al2O3 epitaxial layer (2) on the surface of the substrate (1); S3: Using photolithography technology, define the interdigitated electrode region on the surface of the Si-doped Al2O3 epitaxial layer (2), and perform exposure and development; S4: etching the interdigital electrode region using a photolithography technique to form an interdigital electrode pattern, and treating residual adhesive in the interdigital electrode pattern using oxygen plasma; S5: sequentially depositing Ni and Au metal layers on the interdigital electrode pattern region by electron beam evaporation technology or physical vapor deposition technology to form a Ni / Au metal layer; S6: Washing away the photoresist, forming interdigitated electrodes (3) on the surface of the Si-doped Al2O3 epitaxial layer (2), and obtaining an Al2O3 extreme ultraviolet detector with a detection capability of 13.5 nm wavelength; 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 .

7. The preparation method according to claim 6, characterized in that: In step S1, the specific steps of ultrasonic cleaning are: placing the substrate (1) in acetone, anhydrous ethanol, and water in sequence for ultrasonic cleaning for 5 to 6 minutes, and then placing it in piranha solution for ultrasonic cleaning for 3 to 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 metal organic chemical vapor deposition technology, hydride vapor phase epitaxy technology, spray chemical vapor deposition technology and pulsed laser deposition technology, using silane as a silicon source and trimethylaluminum as an aluminum oxide source, to prepare the Si-doped Al2O3 epitaxial layer (2) under the protection of hydrogen or nitrogen; In 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 a Si substrate; The thickness ratio of the Ni and Au metal layers 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.

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

Images