Mesa sidewall passivation method for type-II superlattice infrared detectors and infrared detectors

Abstract

This application provides a method for mesa sidewall passivation for a type-II superlattice infrared detector and an infrared detector in the field of semiconductor manufacturing. It solves the problem of high interface state density and large dark current caused by the Sb₂O₅-rich natural oxide layer formed on the sidewall of an aluminum antimony compound or aluminum arsenide antimony compound barrier layer due to atmospheric exposure. The method includes the following steps: cleaning and drying the type-II superlattice infrared detector chip with completed mesa etching, and then loading it into the sample chamber of an ALD device; evacuating and heating; introducing high-purity hydrogen into a remote plasma source, activating the remote plasma source, and selectively reducing the unstable natural oxide layer on the chip barrier layer sidewall surface to a volatile gas using hydrogen plasma, which is then removed by the vacuum system; after hydrogen plasma treatment, switching the gas path to an ALD precursor to form a passivation film on the barrier layer sidewall; cooling and wafer removal; this application is applied to infrared detectors.

Description

Technical Field

[0001] This application relates to the field of semiconductor device manufacturing technology, and in particular to a method for passivating the mesa sidewalls of a type II superlattice infrared detector and the infrared detector itself. Background Technology

[0002] Mid-wave infrared (MWIR) detectors typically cover wavelengths between 3 and 5 µm. Type II superlattice (T2SL) MWIR detectors from group III-V offer advantages such as low-cost substrates and fabrication processes, greater flexibility in bandgap tuning, better material uniformity, and superior device performance, providing a solid foundation for the development of high-performance MWIR detectors. In the field of superlattice MWIR detectors, compared to InAs / GaSb T2SLs, Ga-atom-free InAs / InAsSb T2SLs exhibit a longer Shockley Read Hall (SRH) recombination lifetime, greater defect state tolerance, and a simpler growth process, and are widely considered the next-generation Type II superlattice infrared detection material system after InAs / GaSb. In these devices, the barrier layer composed of wide-bandgap materials (such as AlSb and AlAsSb) plays a crucial role in suppressing dark currents, especially diffusion currents. The nBn barrier-type mid-wave infrared detector structure aims to impede the flow of majority carriers while allowing minority carriers to flow freely through a rational band structure design. Its epitaxial structure is as follows: Figure 1 As shown.

[0003] However, after the mesa etching process forms individual detector pixels, the sidewalls of the barrier layer are exposed to the environment. Aluminum antimony compounds are chemically reactive, and their sidewalls rapidly form a non-stoichiometric, defect-state-rich native oxide layer (mainly Sb₂O₃ and Al₂O₃). These interface states become carrier generation-recombination centers, forming surface leakage channels and increasing the device's dark current, thus significantly degrading the detector's signal-to-noise ratio, uniformity, and reliability. Therefore, effective passivation of the barrier layer sidewalls is a key technological bottleneck in realizing the high-performance nBn barrier-type mid-wave infrared detector T2SL.

[0004] Currently, the industry commonly uses a combination of wet chemical cleaning and atomic layer deposition (ALD) dielectric layer for passivation. A typical pretreatment process involves immersing the etched mesa in a hydrochloric acid (HCl)-based solution (e.g., HCl:H2O=1:X) to remove the natural oxide layer on the surface. After cleaning with deionized water and organic solvents (e.g., isopropanol) and drying, the mesa is then sent to an ALD device to deposit a passivation layer such as alumina (Al2O3).

[0005] Although this method is currently the mainstream approach, it suffers from a series of inherent and difficult-to-overcome drawbacks:

[0006] 1. Secondary contamination and oxidation issues: After wet cleaning, the sample must be exposed to the atmosphere for transport before being loaded into the ALD reaction chamber. This process inevitably leads to the re-oxidation and adsorption of contaminants on the cleaned surface, fundamentally limiting the interface quality of subsequent ALD deposition and resulting in a persistently high interface state density.

[0007] 2. Surface morphology damage risk: Wet chemical etching with HCl solution is isotropic, which poses a potential risk of undercutting the delicate mesa sidewalls, potentially introducing micro-roughness or even damaging the device structure. This is particularly detrimental to small-pixel, highly integrated focal plane arrays.

[0008] 3. Poor process consistency and repeatability: The cleaning effect is highly dependent on the concentration, temperature, soaking time of the solution and the operator's experience, making it difficult to achieve high uniformity at the wafer level and batch-to-batch repeatability, which becomes an obstacle to improving production yield.

[0009] 4. Fragmented process flow: Wet cleaning and dry ALD deposition are two completely separate process steps, which not only increases the complexity, time consumption and cost, but also introduces the risk of particulate contamination caused by multiple manual operations.

[0010] In summary, existing wet chemical pretreatment methods have become a key technological obstacle restricting further performance improvement and mass production of nBn type-II superlattice infrared detectors. There is an urgent need in this field for a novel pretreatment technology capable of obtaining clean, stable, and non-destructive barrier layer sidewall surfaces that can be seamlessly integrated with subsequent ALD passivation processes. This would fundamentally improve the passivation interface quality and ultimately achieve a breakthrough improvement in the device's dark current characteristics. Summary of the Invention

[0011] To address the issues of high interface state density and large dark current in type-II superlattice infrared detectors with nBn or XBn structures, caused by the formation of a Sb₂O₅-rich natural oxide layer on the sidewalls of the aluminum antimony bide (AlSb) or aluminum arsenide antimony bide (AlAsSb) barrier layer due to exposure to the atmosphere, this application proposes a mesa sidewall passivation method and an infrared detector for type-II superlattice infrared detectors. This method is an in-situ pretreatment and passivation process for the sidewalls of the aluminum antimony bide (AlSb) or aluminum arsenide antimony bide (AlAsSb) barrier layer in nBn or XBn structure devices.

[0012] The technical solution adopted in this application is: a method for passivating the mesa sidewalls of a type-II superlattice infrared detector, comprising the following steps:

[0013] Step 1: Sample preparation and loading: After cleaning and drying the type II superlattice infrared detector chip with completed mesa etching, load it into the sample chamber of an atomic layer deposition device equipped with a remote plasma source.

[0014] Step 2: After evacuating the sample chamber, heat the sample stage inside the chamber to a suitable temperature and maintain the temperature stable.

[0015] Step 3: In-situ hydrogen plasma pretreatment: High-purity hydrogen gas is introduced into the remote plasma source through the hydrogen gas path, the remote plasma source is started, and the unstable natural oxide layer on the sidewall surface of the chip barrier layer is selectively reduced into volatile gas by hydrogen plasma, which is then removed by the vacuum system.

[0016] Step 4: Atomic layer deposition to grow passivation layer: After the hydrogen plasma treatment is completed, immediately shut down the plasma source and hydrogen gas path. Without disrupting the vacuum of the chamber, switch the gas path to atomic layer deposition precursor to form a passivation film on the sidewall of the chip barrier layer.

[0017] Step 5: Cooling and removing the film.

[0018] Furthermore, the type II superlattice infrared detector chip is an nBn type or XBn type mid-wave type II superlattice detector chip.

[0019] Furthermore, the chip barrier layer is an aluminum antimony barrier layer.

[0020] Furthermore, the vacuum level after evacuation of the chamber in step two is ≤1.0×10⁻⁶. -5 Torr heats the sample stage to 150-250℃ and keeps it stable.

[0021] Furthermore, in step three, the flow rate of high-purity hydrogen is controlled at 50-200 sccm, and an appropriate amount of argon is introduced into the chamber at the same time as hydrogen is introduced, while maintaining the chamber pressure at 20-100 mTorr.

[0022] Furthermore, in step three, a remote plasma source is activated, and radio frequency energy of 50-300W is applied to generate high-density hydrogen radicals and active ions. Through the selective reduction reaction of hydrogen radicals and active ions with the unstable natural oxide layer on the chip barrier layer surface for 30-120 seconds, a hydrogen-terminated surface is formed on the sidewall of the chip barrier layer.

[0023] Furthermore, in step four, an atomic layer deposition process using trimethylaluminum and H2O as precursors is employed to deposit a passivation film.

[0024] Furthermore, the unstable native oxide layer on the surface of the chip barrier layer includes Sb2O3 and Sb2O5.

[0025] Furthermore, the volatile gases obtained from the in-situ hydrogen plasma pretreatment in step three are hydride gases and water vapor.

[0026] An infrared detector was obtained using a mesa sidewall passivation method for a type II superlattice infrared detector.

[0027] The advantages of this application over the prior art are as follows:

[0028] 1. This application completely solves the problems of secondary oxidation and contamination, achieving an atomically clean passivation interface. By performing in-situ hydrogen plasma pretreatment within the ALD reaction chamber, the sample remains in a high-vacuum environment after mesa etching, completely avoiding contact with the atmosphere. The active hydrogen species in the hydrogen plasma efficiently reduce unstable native oxide layers (such as Sb₂O₃) to volatile SbH₃ and H₂O, which are then removed, simultaneously achieving surface hydrogen terminal passivation. This fundamentally eliminates the secondary oxidation and surface hydroxyl contamination caused by atmospheric transport, which are difficult to avoid in traditional wet processes. It provides a near-ideal starting surface for subsequent ALD growth, significantly reducing the interface state density and laying a solid foundation for greatly reducing device surface leakage and improving electrical performance.

[0029] 2. The geometric integrity of the mesa structure is perfectly preserved, avoiding damage from wet chemical processes. The vapor-phase dry process used in this application exhibits excellent isotropy and uniformity. Its surface reaction mechanism is chemical reduction rather than liquid-phase corrosion, completely eliminating the potential drilling and chemical erosion risks of hydrochloric acid solution on the aluminum antimony baffle barrier layer and the sidewalls of the superlattice material. This method can perfectly preserve the original morphology of the etched surface, making it particularly suitable for pixel structures of micrometer-scale or even smaller sizes. This is of crucial importance for ensuring the yield and reliability of high-resolution focal plane arrays.

[0030] 3. This significantly improves the consistency and repeatability of the process, laying the foundation for large-scale mass production. The pretreatment process in this application is precisely controlled by digital parameters such as plasma power, hydrogen flow rate, processing time, and chamber pressure, eliminating the uncertainties caused by changes in solution concentration, temperature fluctuations, operation time, and personnel differences in wet processes. This method achieves excellent uniformity and repeatability within the wafer and between batches, significantly improving production yield and making the standardized and large-scale manufacturing of high-performance type-II superlattice detectors possible.

[0031] 4. This application achieves a fully dry, integrated process, improving production efficiency and cleanliness. Pretreatment and ALD passivation are completed continuously within the same equipment chamber, achieving a seamless connection between "passivation pretreatment and passivation." This not only simplifies the process flow and reduces production cycle time, but also completely avoids intermediate steps such as sample transfer and loading after wet processing, greatly reducing the risk of particulate contamination and mechanical damage caused by manual operation, meeting the stringent requirements of advanced semiconductor manufacturing for automation and cleanliness.

[0032] In summary, this application systematically solves the core technical challenges that have long plagued the performance and mass production of nBn type II superlattice infrared detectors through an innovative in-situ dry pretreatment technology, bringing breakthrough improvements in interface quality, structural fidelity, process consistency, production integration, and environmental friendliness. Attached Figure Description

[0033] The following description, in conjunction with the accompanying drawings, further illustrates this application:

[0034] Figure 1 The epitaxial structure of the nBn mid-wave barrier detector provided in this application embodiment is shown in the figure. The layer indicated by the arrow is the stop barrier layer, which is the mesa etching position.

[0035] Figure 2 This is a process flow diagram of the in-situ hydrogen plasma pretreatment proposed in this application;

[0036] Figure 3 This is a comparison diagram of the traditional wet deoxidation process (existing technology) and the method proposed in this application. Detailed Implementation

[0037] like Figures 1 to 3 As shown, this application provides a mesa sidewall passivation method for a type-II superlattice infrared detector. Unlike existing plasma treatments that aim to regulate the rate and profile of thin film deposition through physical bombardment or passivation effects, this application aims to thoroughly remove specific oxides from the barrier layer sidewalls through a specific chemical reduction reaction, achieving an atomically clean hydrogen-terminated surface. The mesa sidewall passivation method proposed in this application is a type-II superlattice detector passivation method based on in-situ hydrogen plasma pretreatment, targeting the unique surface chemistry problems of III-V compound semiconductors (especially aluminum antimony bromide barrier layers)—high interface state density and surface leakage caused by an unstable native oxide layer. The solution involves integrating remote hydrogen plasma into the ALD (Alternating Layer Deposition), where the hydrogen plasma removes the native oxide layer through a chemical reduction reaction, forming a hydrogen-terminated surface. This achieves a seamless, full-vacuum connection between "pretreatment-deposition" within the same ALD device, completely solving the problem of secondary contamination. Simultaneously, it effectively overcomes the inherent problems of secondary contamination and oxidation in existing wet chemical cleaning techniques, resulting in significant technological advancements.

[0038] This application provides an in-situ hydrogen plasma pretreatment and passivation method for the sidewalls of the aluminum antimony baffle barrier layer in a type-II superlattice nBn detector. The hydrogen plasma pretreatment and atomic layer deposition are performed sequentially within the same ALD device, without disrupting the vacuum throughout the process, thus avoiding atmospheric contamination or re-oxidation of the barrier layer sidewalls during transmission. The specific operation steps are as follows:

[0039] Step 1: Sample Preparation and Loading

[0040] Provide a nBn type mid-wave type II superlattice detector chip with completed mesa etching, its barrier layer is AlSb / AlAsSb, and the mesa sidewalls are exposed.

[0041] After the chip was cleaned and dried with standard organic solvents (such as acetone and isopropanol), it was loaded into the sample chamber of an atomic layer deposition (ALD) device equipped with a remote plasma source.

[0042] Step 2: Vacuuming and Stabilization of the Chamber

[0043] Close the sample chamber door, start the vacuum system, and evacuate the chamber background vacuum to ≤1.0×10⁻⁶. -5 Torr's high vacuum state.

[0044] The sample stage temperature is heated to 150℃-250℃ (preferably 200℃) and kept stable. This temperature range ensures sufficient reaction kinetics, avoids the decomposition of AlSb material due to overheating (AlSb has poor thermal stability), and perfectly matches the subsequent ALD-Al2O3 deposition temperature, achieving true thermal integration.

[0045] Step 3: In-situ hydrogen plasma pretreatment

[0046] High-purity hydrogen gas (H2, 99.999%) is introduced into the remote plasma source, with the gas flow rate controlled at 50-200 sccm (preferably 100 sccm). Simultaneously, an appropriate amount of argon gas (Ar) is introduced into the chamber as a carrier gas to maintain the chamber pressure at 20-100 mTorr (preferably 50 mTorr).

[0047] A remote plasma source is activated, applying low-power radio frequency energy, with the power range set between 50-300W (preferably 150W). This excites the generation of high-density hydrogen radicals (H·) and active ions (H2O). + This avoids generating high-energy ions that could cause physical bombardment damage to the sample surface.

[0048] The sample surface is subjected to a short, gentle treatment lasting 30 to 120 seconds (preferably 60 seconds). During this process, hydrogen plasma selectively reduces the unstable native oxide layer (such as Sb2O3) on the sidewall surface of the barrier layer to volatile hydrogen antimonide (SbH3) and water vapor (H2O), which are then removed by a vacuum system.

[0049] The core mechanism of hydrogen plasma pretreatment in this application lies in the active hydrogen species (H·,H) + This substance can selectively reduce antimony trioxide (Sb₂O₃) on the AlSb / AlAsSb surface, generating volatile hydrogen antimony (SbH₃) and water (H₂O). This reaction effectively removes unstable Sb₂O₃ with minimal damage to the underlying superlattice functional layer. The reaction equation can be expressed as: Sb₂O₃ + 12H· → 2SbH₃↑ + 3H₂O↑. This treatment results in an aluminum-rich, hydrogen-terminated, atomically clean surface. Figure 2 This is the process flow of the in-situ hydrogen plasma pretreatment atomic layer deposition passivation technology proposed in this application.

[0050] Step 4: Atomic layer deposition to grow passivation layer

[0051] After the hydrogen plasma treatment is completed, immediately shut down the plasma source and hydrogen gas path, and switch the gas path to the ALD precursor without disrupting the chamber vacuum.

[0052] On the hydrogen-terminated surface generated by hydrogen plasma pretreatment, Al2O3 is deposited using an ALD process with TMA (trimethylaluminum) and H2O as precursors. On this hydrogen-terminated AlSb surface, the nucleation density of TMA is higher and the initial growth is faster, which helps to form an Al2O3 / AlSb interface with a lower interface state density (Dit). This effect cannot be achieved by wet cleaning or other plasma pretreatment methods.

[0053] The ALD cycle parameters were set as follows: TMA pulse 0.015s → argon flow rate 20 sccm → H2O pulse 0.015s. The growth thickness per cycle was approximately 0.1 nm.

[0054] The ALD cycle was repeated 1485 times to finally form a dense, uniform Al2O3 film with a thickness of 150 nm, achieving high-quality passivation of the barrier layer sidewalls.

[0055] Step 5: Cooling and Removing the Film

[0056] After deposition, heating is stopped, and the sample is allowed to cool naturally to below 80°C in a vacuum environment.

[0057] High-purity nitrogen (N2) is introduced into the chamber to atmospheric pressure, the chamber is opened, and the passivated chip is removed.

[0058] Figure 3 In comparison with the traditional wet process, the core of this method lies in "surface terminalization" and "natural oxide layer removal." Unlike existing technologies that use inhibitory plasmas such as nitrogen and argon to selectively suppress deposition, the hydrogen plasma in this application does not have the function of suppressing deposition. Instead, it achieves interface optimization through surface chemical reduction reactions. Specifically, the main differences between the method of this application and conventional wet surface treatment are as follows:

[0059] 1. Fundamental difference in method and principle: Existing technology: Employs the wet chemical corrosion principle of HCl solution. Through H... + and Cl - The ions are removed through acid-base reactions and dissolution reactions with surface oxides. This is a liquid-phase reaction process. This application employs the dry chemical reduction principle of hydrogen free radicals. It utilizes active hydrogen species (H·, H) generated by plasma. + This process reduces high-valence metal oxides (such as Sb₂O₅, Sb₂O₃) to volatile hydrides (such as SbH₃) and water. This is a gas-phase reaction process.

[0060] 2. Fundamentally Different Process Objectives: There are many ALD integration processes, but they all serve different purposes. Some ALD processes use inhibitory plasmas such as nitrogen to selectively suppress deposition and control the filling morphology; they do not aim to achieve complete surface cleaning or changes in the chemical bonding state. In contrast, the purpose of using hydrogen plasma in this application is surface cleaning and passivation, i.e., reducing and removing the native oxide layer to form a hydrogen-terminated surface.

[0061] 3. Different process integration methods: Some ALD integration is an alternating and cyclical integration of "etching + deposition", which aims to realize the addition and subtraction of materials through digital control. Its etching step (such as using Cl2) is anisotropic and will physically peel off the material; this is a unidirectional and sequential integration of "pretreatment + deposition". The pretreatment is to obtain a stable interface without oxide layer and reduce leakage current on the sidewall. The alumina passivation layer is then grown, which aims to create a perfect starting interface for deposition.

[0062] The passivation method for type II superlattice detectors based on in-situ hydrogen plasma pretreatment provided in this application has significant and beneficial technical effects compared to traditional wet chemical cleaning processes, specifically in the following aspects:

[0063] 1. An ultra-low interface state density was achieved, which greatly suppressed surface leakage.

[0064] In-situ hydrogen plasma pretreatment removed the unstable native oxide layer on the sidewalls of the barrier layer and achieved an atomically clean surface with hydrogen termination, providing a near-ideal interface for subsequent ALD-Al2O3 growth. This approach fundamentally eliminates secondary oxidation and contamination caused by atmospheric exposure. The extremely low interface state density effectively suppressed the generation-recombination process of charge carriers on the surface, thereby significantly reducing the device's dark current, especially the surface leakage component.

[0065] 2. It perfectly maintains the geometric integrity of the countertop structure.

[0066] The vapor-phase dry process employed in this application utilizes low-power (50-300W) and short-duration (30-120 seconds) mild processing conditions. It is a chemical reduction process rather than liquid-phase corrosion, and its isotropic and extremely gentle nature aims to achieve chemical reduction without causing physical damage. This completely avoids the drilling and micro-roughening of the mesa sidewalls caused by wet chemical cleaning. The processed mesa sidewalls have a smooth, steep morphology, consistent with the original morphology after etching. This is crucial for ensuring the yield, performance uniformity, and long-term reliability of small-pixel, highly integrated focal plane arrays.

[0067] 3. Achieved process consistency and repeatability

[0068] The pretreatment process in this application is precisely controlled by digital parameters such as plasma power, hydrogen flow rate, and processing time, eliminating the uncertainties caused by human operation, solution concentration, and temperature fluctuations in wet processes. This scheme exhibits excellent uniformity and repeatability within the same wafer and across different process batches. The dispersion of key electrical parameters (such as dark current) can be reduced by more than 50% compared to traditional processes, significantly improving production yield and laying a solid foundation for the large-scale, standardized manufacturing of high-performance type-II superlattice detectors.

[0069] 4. The process flow has been simplified, improving production efficiency and cleanliness.

[0070] This application integrates pretreatment and ALD passivation into the same equipment cavity for continuous completion, achieving "one-click" all-dry operation. This not only simplifies the production process, reduces process steps and total time, but also completely avoids intermediate steps such as sample transfer and loading after wet processing, greatly reducing the risk of particulate contamination and mechanical damage caused by manual operation, and meeting the requirements of advanced semiconductor manufacturing for automation, high cleanliness and high reliability.

[0071] In summary, this application employs in-situ hydrogen plasma pretreatment, the purpose of which is to thoroughly remove the natural oxide layer on the sidewalls of the nBn-type barrier layer and form an atomically clean surface with hydrogen termination, thereby achieving a passivation layer with no interface states and low defect density in subsequent ALD deposition.

[0072] This application also proposes an infrared detector, the passivation layer of which is prepared by the above method.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for passivating the mesa sidewalls of a type-II superlattice infrared detector, characterized in that: Includes the following steps: Step 1: Sample preparation and loading: After cleaning and drying the type II superlattice infrared detector chip with completed mesa etching, load it into the sample chamber of an atomic layer deposition device equipped with a remote plasma source. Step 2: After evacuating the sample chamber, heat the sample stage inside the chamber to a suitable temperature and maintain the temperature stable. Step 3: In-situ hydrogen plasma pretreatment: High-purity hydrogen gas is introduced into the remote plasma source through the hydrogen gas path, the remote plasma source is started, and the unstable natural oxide layer on the sidewall surface of the chip barrier layer is selectively reduced into volatile gas by hydrogen plasma, which is then removed by the vacuum system. In step three, a remote plasma source is activated and radio frequency energy of 50-300W is applied to generate high-density hydrogen radicals and active ions. Through the selective reduction reaction of hydrogen radicals and active ions with the unstable natural oxide layer on the chip barrier layer surface for 30-120 seconds, a hydrogen-terminated surface is formed on the sidewall of the chip barrier layer. The principle of hydrogen plasma pretreatment: active hydrogen species can selectively reduce the unstable natural oxide layer on the surface of the chip barrier layer to generate volatile hydride gas and water vapor. This treatment makes the surface of the chip barrier layer present an aluminum-rich, hydrogen-terminated atomically clean state. Step 4: Atomic layer deposition to grow passivation layer: After the hydrogen plasma treatment is completed, immediately shut down the plasma source and hydrogen gas path. Without disrupting the vacuum of the chamber, switch the gas path to atomic layer deposition precursor to form a passivation film on the sidewall of the chip barrier layer. Step 5: Cooling and Removing the Film; The type II superlattice infrared detector chip is an nBn type or XBn type mid-wave type II superlattice detector chip; The chip barrier layer is an aluminum antimony barrier layer; the unstable native oxide layer on the surface of the chip barrier layer includes Sb2O3 and Sb2O5.

2. The method for passivating the mesa sidewalls of a type-II superlattice infrared detector according to claim 1, characterized in that: The vacuum level after evacuating the chamber in step two is ≤1.0×10⁻⁶. -5 Torr heats the sample stage to 150-250℃ and keeps it stable.

3. The method for passivating the mesa sidewalls of a type-II superlattice infrared detector according to claim 2, characterized in that: In step three, the flow rate of high-purity hydrogen is controlled at 50-200 sccm, and an appropriate amount of argon is introduced into the chamber at the same time as hydrogen is introduced, while maintaining the chamber pressure at 20-100 mTorr.

4. The method for passivating the mesa sidewalls of a type-II superlattice infrared detector according to claim 1, characterized in that: In step four, an atomic layer deposition process using trimethylaluminum and H2O as precursors is employed to deposit a passivation film.

5. An infrared detector obtained by using the mesa sidewall passivation method for a type II superlattice infrared detector as described in any one of claims 1-4.

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