Uncooled infrared detector functional layer and preparation method thereof

Abstract

The invention belongs to the technical field of functional material preparation, and particularly relates to an uncooled infrared detector functional layer and a preparation method thereof. The functional layer sequentially comprises a first dielectric layer, a second dielectric layer, a thermistor layer, a first protective layer and a second protective layer from bottom to top, the first dielectric layer, the second dielectric layer, the first protective layer and the second protective layer are silicon nitride, and the thermistor layer is vanadium oxide; the first dielectric layer is formed by adopting a plasma enhanced chemical vapor deposition method, and the thickness of the first dielectric layer is 0-1000; the second dielectric layer is formed by adopting a physical vapor deposition method, and the thickness of the second dielectric layer is 400-1400; the thermistor layer is formed by adopting a physical vapor deposition method, and the thickness of the thermistor layer is 600-1000; the first protective layer is formed by adopting a physical vapor deposition method, and the thickness of the first protective layer is 400-1400; and the second protective layer is formed by adopting a plasma enhanced chemical vapor deposition method, and the thickness of the second protective layer is 0-1000. The uncooled infrared detector functional layer provided by the invention has relatively high TCR performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional material preparation, and particularly relates to a functional layer of a non-refrigeration infrared detector and a preparation method thereof. BACKGROUND

[0002] The thermal sensitive material part of the non-refrigeration infrared detector mainly uses amorphous silicon, vanadium oxide and other materials. Among them, the temperature coefficient of resistance (TCR) of the thermal sensitive material is of great significance to the detection performance of the non-refrigeration infrared detector, and this needs to be considered first when selecting the thermal sensitive layer material of the detector, which will directly affect the sensitivity of the infrared detector.

[0003] In the prior art, vanadium oxide is often used as the thermal sensitive layer of the non-refrigeration infrared detector. Vanadium oxide is a semiconductor material with a relatively high temperature coefficient of resistance, and the technology for preparing vanadium oxide has been relatively mature after years of development. Magnetron sputtering is the most commonly used method, and is fully compatible with the preparation process of the detector.

[0004] Regarding the preparation process of the functional layer of the existing non-refrigeration infrared detector, it generally includes a silicon nitride medium layer, a vanadium oxide thermal sensitive layer and a silicon nitride protective layer in sequence. For example, the invention patent with the application number CN201610422054.6 discloses a wide-band non-refrigeration infrared detector and a preparation method thereof, and the specific process is as follows: an electrode is deposited by using PVD; an electrode pattern is etched by using photolithography and etching, a low-stress Si3N4 medium layer is deposited by using PECVD, part of the protective layer Si3N4 is etched off on the electrode passivation layer by using photolithography and etching to form a contact hole of the electrode and the thermal sensitive layer, the electrode is relatively thin, and end point monitoring EPD is used to monitor the etching reaction to prevent the electrode from being etched completely; after the Contact hole is etched, a thermal sensitive film is deposited, the thermal sensitive layer material uses a VOx film, is grown by using ion beam deposition or physical vapor deposition, after the thermal sensitive film is etched, a low-stress Si3N4 film protective layer is deposited by using PECVD, then a protective layer pattern is formed by photolithography, and each layer of Si3N4 film is etched to prepare for the release of the sacrificial layer.

[0005] At present, the preparation process of the functional layer of the uncooled infrared detector generally comprises a silicon nitride medium layer, a vanadium oxide thermal sensitive layer and a silicon nitride protective layer in sequence. The silicon nitride medium layer and the silicon nitride protective layer are generally obtained by PECVD deposition. However, the silicon nitride is obtained by the reaction of silane and ammonia in the PECVD deposition method, that is, 3SiH4(g)+4NH3(g)→Si3N4(s)+12H2(g). Therefore, the Si3N4 film obtained by the PECVD reaction is inevitably doped with a small amount of hydrogen atoms. When the vanadium oxide film is deposited, the hydrogen elements in the silicon nitride medium layer and the silicon nitride protective layer deposited later will be released and diffused, and will react with the vanadium oxide film to cause the vanadium oxide to transfer to the metal phase, thereby significantly reducing the TCR performance of the film and finally reducing the response rate of the uncooled infrared detector. SUMMARY

[0006] The present application aims to overcome the deficiencies in the prior art and provides an uncooled infrared detector functional layer and a preparation method thereof. The uncooled infrared detector functional layer comprises a first silicon nitride medium layer obtained by CVD deposition, a second silicon nitride medium layer obtained by PVD deposition, a vanadium oxide thermal sensitive layer, a first silicon nitride protective layer obtained by PVD deposition and a second silicon nitride protective layer obtained by CVD deposition in sequence. The second silicon nitride medium layer is obtained by sputtering by the reaction of silicon and nitrogen and does not contain hydrogen, so as not to affect the vanadium oxide layer. In addition, the PVD-deposited silicon nitride medium layer film is dense and can block the diffusion of hydrogen elements in the CVD-deposited silicon nitride medium layer, thereby greatly reducing the reduction of the vanadium oxide by hydrogen atoms, ensuring the stability of the vanadium oxide film and improving the TCR performance thereof.

[0007] To achieve the above technical purposes, the technical solutions adopted by the embodiments of the present application are as follows: In a first aspect, the embodiments of the present application provide a functional layer of an uncooled infrared detector, which comprises a first medium layer, a second medium layer, a thermal resistance layer, a first protective layer and a second protective layer in sequence from bottom to top. The first medium layer, the second medium layer, the first protective layer and the second protective layer are all silicon nitride, and the thermal resistance layer is vanadium oxide. The first medium layer is formed by plasma enhanced chemical vapor deposition and has a thickness of 0-1000 Å. The second medium layer is formed by physical vapor deposition and has a thickness of 400-1400 Å. The thermal resistance layer is formed by physical vapor deposition and has a thickness of 600-1000 Å. The first protective layer is formed by physical vapor deposition and has a thickness of 400-1400 Å. The second protective layer is formed by plasma enhanced chemical vapor deposition, and the thickness is 0-1000 angstroms.

[0008] In a second aspect, the present application provides a preparation method of a functional layer of a uncooled infrared detector, comprising the following steps: Step S1, first medium layer preparation: the substrate temperature is kept at 150-250 DEG C, the cavity pressure is 2.0-5.0 Torr, the reaction gas includes silane, ammonia and nitrogen, the frequency of high-frequency radio frequency is 13-40 MHz, the power is set to 500-1500 W, the plasma enhanced chemical vapor deposition is 0-10 s, and the first medium layer is prepared; Step S2, second medium layer preparation: the substrate temperature is set to 150-300 DEG C, the cavity vacuum degree is kept at ≤5.0*10 -8 Torr, a sputtering power of 500-6000 W is used, and the target material is pre-sputtered for 1-10 min; The substrate is transmitted into a direct-current magnetron sputtering vacuum cavity, argon with a flow rate of 20-100 sccm and nitrogen with a flow rate of 20-100 sccm are introduced, the cavity reaction pressure is 3.0-12.0 mTorr, the target input power is 500-6000 W, and the sputtering time is 0.5-4 min, so that the second medium layer is formed on the first medium layer; Step S3, thermistor layer preparation: the substrate temperature is set to 30-200 DEG C, the cavity vacuum degree is kept at ≤5.0*10 -8 Torr, a sputtering power of 1000-3000 W is used, and the target material is pre-sputtered for 1-10 min; The substrate is transmitted into a direct-current magnetron sputtering vacuum cavity, argon with a flow rate of 15-30 sccm and oxygen with a flow rate of 1.0-5 sccm are introduced, the cavity reaction pressure is 1.0-3.0 mTorr, the target input power is 50-3000 W, and the sputtering time is 6-10 min, so that the thermistor layer is formed on the second medium layer; Step S4, first protective layer preparation: the substrate temperature is set to 150-300 DEG C, the cavity vacuum degree is kept at ≤5.0*10 -8 Torr, a sputtering power of 500-6000 W is used, and the target material is pre-sputtered for 1-10 min; The substrate is transmitted into a direct-current magnetron sputtering vacuum cavity, argon with a flow rate of 20-100 sccm and nitrogen with a flow rate of 20-100 sccm are introduced, the cavity reaction pressure is 3.0-12.0 mTorr, the target input power is 500-6000 W, and the sputtering time is 0.5-4 min, so that the first protective layer is formed on the thermistor layer; Step S5, second protective layer preparation: the substrate temperature is kept at 150-250 DEG C, the cavity pressure is 2.0-5.0 Torr, the reaction gas includes silane, ammonia and nitrogen, the frequency of high-frequency radio frequency is 13.56-40 MHz, the power is set to 500-1500 W, the plasma enhanced chemical vapor deposition is 0-10 s, and the second protective layer is formed on the first protective layer.

[0009] Further, in step S1, before formal deposition, NH3 with a flow rate of 300-600 sccm is used for pretreatment for 10-50 s, and the power is 500-3000 W.

[0010] Further, in step S2, the target material is selected as a silicon target, the target material has a diameter of 320-321 mm, and the distance between the target material and the substrate carrier is 40-60 mm.

[0011] Further, in step S3, the target material is selected as a vanadium target, the target material has a diameter of 320-321 mm, and the distance between the target material and the substrate carrier is 90-150 mm.

[0012] Further, in step S4, the target material is selected as a silicon target, the target material has a diameter of 320-321 mm, and the distance between the target material and the substrate carrier is 40-60 mm.

[0013] Further, in step S5, before formal deposition, NH3 with a flow rate of 300-600 sccm is used for pretreatment for 10-50 s, and the power is 500-3000 W.

[0014] Further, in step S1 and step S5, the gas flow rates are as follows: SiH4= 500-1000 sccm, NH3= 200-500 sccm, and N2= 10000-20000 sccm.

[0015] In a third aspect, an embodiment of the present application provides a non-refrigeration infrared detector, which comprises the functional layer of the first aspect.

[0016] The technical scheme provided by the embodiment of the present application has the following beneficial effects: The functional layer of the non-refrigeration infrared detector of the present application comprises, in sequence, a first CVD-deposited silicon nitride medium layer, a second PVD-deposited silicon nitride medium layer, a vanadium oxide thermal sensitive layer, a first PVD-deposited silicon nitride protective layer, and a second CVD-deposited silicon nitride protective layer. The second silicon nitride medium layer and the first silicon nitride protective layer are added to form a "five-layer sandwich" structure. The second PVD-deposited silicon nitride medium layer is prepared by sputtering of silicon and nitrogen, and does not contain hydrogen, thus not affecting the vanadium oxide layer. Moreover, the second PVD-deposited silicon nitride medium layer and the first silicon nitride protective layer are dense in material, and can block the diffusion of hydrogen in the first CVD-deposited silicon nitride medium layer and the second CVD-deposited silicon nitride protective layer, greatly reducing the reduction of vanadium oxide by hydrogen atoms, ensuring the stability of the vanadium oxide film layer, and improving the TCR performance. In addition, the total stress of the functional film can be significantly reduced due to the partial retention of CVD-deposited silicon nitride. The sum of the thicknesses of the CVD-deposited silicon nitride medium layer and the PVD-deposited silicon nitride medium layer is the same as the commonly used thickness of the CVD-deposited silicon nitride medium layer in the prior art, and the sum of the thicknesses of the CVD-deposited silicon nitride protective layer and the PVD-deposited silicon nitride protective layer is the same as the commonly used thickness of the CVD-deposited silicon nitride protective layer in the prior art.

[0017] In addition, as a special case, the preparation process of the non-refrigeration infrared detector of the present application comprises, in sequence, PVD-deposited silicon nitride medium layer, vanadium oxide thermal sensitive layer, and PVD-deposited silicon nitride protective layer. The PVD-deposited silicon nitride medium layer is prepared by sputtering of silicon and nitrogen, and does not contain hydrogen. When directly contacting with the vanadium oxide thermal resistance layer, it does not reduce the vanadium oxide thermal resistance layer, thus not affecting the vanadium oxide layer, ensuring the stability of the vanadium oxide film layer, and improving the TCR performance. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The resistance temperature change curve of the functional layer of the non-refrigeration infrared detector prepared in Example 1 of the present application.

[0019] Figure 2 The resistance temperature change curve of the functional layer of the non-refrigeration infrared detector prepared in Example 2 of the present application.

[0020] Figure 3 The resistance temperature change curve of the functional layer of the non-refrigeration infrared detector prepared in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0021] In the description of the present application, it should be understood that the orientation words such as "inner", "outer", "upper", "lower", "left", "right" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the scope of protection of the present application.

[0022] A functional layer of a non-refrigeration infrared detector, comprising from bottom to top a first dielectric layer, a second dielectric layer, a thermistor layer, a first protective layer and a second protective layer; The first dielectric layer, the second dielectric layer, the first protective layer and the second protective layer are all silicon nitride, and the thermistor layer is vanadium oxide; The first dielectric layer is formed by plasma-enhanced chemical vapor deposition, and the thickness is 0-1000 angstroms, which can be 0 angstrom, 5 angstrom, 10 angstrom, 20 angstrom, 50 angstrom, 100 angstrom, 150 angstrom, 200 angstrom, 250 angstrom, 300 angstrom, 350 angstrom, 400 angstrom, 450 angstrom, 500 angstrom, 550 angstrom, 600 angstrom, 650 angstrom, 700 angstrom, 750 angstrom, 800 angstrom, 850 angstrom, 900 angstrom, 950 angstrom, 1000 angstrom, etc.

[0023] The second dielectric layer is formed by physical vapor deposition, and the thickness is 400-1400 angstroms, which can be 400 angstrom, 450 angstrom, 500 angstrom, 550 angstrom, 600 angstrom, 650 angstrom, 700 angstrom, 750 angstrom, 800 angstrom, 900 angstrom, 1000 angstrom, 1100 angstrom, 1200 angstrom, 1300 angstrom, 1400 angstrom, etc.

[0024] The thermistor layer is formed by physical vapor deposition, and the thickness is 600-1000 angstroms, which can be 600 angstrom, 650 angstrom, 700 angstrom, 750 angstrom, 800 angstrom, 850 angstrom, 900 angstrom, 950 angstrom, 1000 angstrom, etc.

[0025] The first protective layer is formed by physical vapor deposition, and the thickness is 400-1400 angstroms, which can be 400 angstrom, 450 angstrom, 500 angstrom, 550 angstrom, 600 angstrom, 650 angstrom, 700 angstrom, 750 angstrom, 800 angstrom, 900 angstrom, 1000 angstrom, 1100 angstrom, 1200 angstrom, 1300 angstrom, 1400 angstrom, etc.

[0026] The second protective layer is formed by a plasma enhanced chemical vapor deposition method, and has a thickness of 0-1000 angstroms. The thickness can be 0 angstrom, 5 angstrom, 10 angstrom, 20 angstrom, 50 angstrom, 100 angstrom, 150 angstrom, 200 angstrom, 250 angstrom, 300 angstrom, 350 angstrom, 400 angstrom, 450 angstrom, 500 angstrom, 550 angstrom, 600 angstrom, 650 angstrom, 700 angstrom, 750 angstrom, 800 angstrom, 850 angstrom, 900 angstrom, 950 angstrom, 1000 angstrom, etc.

[0027] In a second aspect, an embodiment of the present application provides a method for preparing a functional layer of a uncooled infrared detector, comprising the following steps: In step S1, a first medium layer is prepared. The substrate temperature is kept at 150-250 DEG C (which can be 150 DEG C, 160 DEG C, 170 DEG C, 180 DEG C, 190 DEG C, 200 DEG C, 210 DEG C, 220 DEG C, 230 DEG C, 240 DEG C, 250 DEG C, etc.), the cavity pressure is 2.0-5.0 Torr (which can be 2.0 Torr, 2.5 Torr, 3.0 Torr, 3.5 Torr, 4.0 Torr, 4.5 Torr, 5.0 Torr, etc.), the reaction gas includes silane SiH4, ammonia NH3 and dilution gas nitrogen N2, the frequency of high-frequency radio frequency is 13-40 MHz (which can be 13 MHz, 15 MHz, 20 MHz, 25 MHz, 30 MHz, 35 MHz, 40 MHz, etc.), the power is set to 500-1500 W (which can be 500 W, 550 W, 600 W, 650 W, 700 W, 800 W, 900 W, 990 W, 1000 W, 1100 W, 1200 W, 1300 W, 1400 W, 1500 W, etc.), the plasma enhanced chemical vapor deposition is performed for 0-10 s (which can be 0 s, 1 s, 2 s, 3 s, 4 s, 5 s, 6 s, 7 s, 8 s, 9 s, 10 s), and the first medium layer is prepared. In step S2, a second medium layer is prepared. The substrate temperature is set to 150-300 DEG C (which can be 150 DEG C, 160 DEG C, 170 DEG C, 180 DEG C, 190 DEG C, 200 DEG C, 210 DEG C, 220 DEG C, 230 DEG C, 240 DEG C, 250 DEG C, 260 DEG C, 270 DEG C, 280 DEG C, 290 DEG C, 300 DEG C, etc.), the cavity vacuum degree is kept at ≤5.0*10 -8Torr, using a sputtering power of 500~6000W (which can be 500W, 550W, 600W, 650W, 700W, 800W, 900W, 1000W, 1500W, 2000W, 2500W, 3000W, 3500W, 4000W, 4500W, 5000W, 5500W, 6000W), pre-sputtering the target material for 1~10min (which can be 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min); The substrate is transferred into a direct current magnetron sputtering vacuum cavity, argon gas with a flow rate of 20~100sccm (which can be 20sccm, 30sccm, 35sccm, 40sccm, 45sccm, 50sccm, 55sccm, 60sccm, 65sccm, 70sccm, 80sccm, 90sccm, 100sccm, etc.) and nitrogen gas with a flow rate of 20~100sccm (which can be 20sccm, 30sccm, 35sccm, 40sccm, 45sccm, 50sccm, 55sccm, 60sccm, 65sccm, 70sccm, 80sccm, 90sccm, 100sccm, etc.) are introduced, the cavity reaction pressure is 3.0~12.0mTorr (which can be 3.0mTorr, 4.0mTorr, 4.5mTorr, 5.0mTorr, 6.0mTorr, 7.0mTorr, 8.0mTorr, 9.0mTorr, 10.0mTorr, 11.0mTorr, 12.0mTorr), the target input power is 500~6000W (which can be 500W, 550W, 600W, 650W, 700W, 800W, 900W, 1000W, 1500W, 2000W, 2500W, 3000W, 3500W, 4000W, 4500W, 5000W, 5500W, 6000W), the sputtering time is 0.5~4min (which can be 0.5min, 1.0min, 1.5min, 2.0min, 2.5min, 3.0min, 3.5min, 4.0min), and a second dielectric layer is formed on the first dielectric layer; Step S3, thermistor layer preparation: the substrate temperature is set to 30~200℃ (which can be 30℃, 50℃, 100℃, 150℃, 200℃), the cavity vacuum degree is kept ≤5.0×10 -8Torr uses a sputtering power of 1000~3000W (values ​​can be 1000W, 1500W, 2000W, 2500W, 3000W, etc.) and pre-sputters the target for 1~10 minutes (values ​​can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min). The substrate is transferred to a DC magnetron sputtering vacuum chamber, and argon gas is introduced at a flow rate of 15~30 sccm (values ​​can be 15 sccm, 20 sccm, 25 sccm, 30 sccm, etc.), and oxygen gas at a flow rate of 1.0~5 sccm (values ​​can be 1.0 sccm, 1.5 sccm, 2.0 sccm, 2.5 sccm, 3.0 sccm, 3.5 sccm, 4.0 sccm, 4.5 sccm, 5 sccm, etc.). The chamber reaction pressure is 1.0~ The sputtering time is 3.0 mTorr (can be 1.0 mTorr, 1.5 mTorr, 1.6 mTorr, 2.0 mTorr, 2.5 mTorr, 3.0 mTorr), the target input power is 500~3000W (can be 500W, 550W, 600W, 650W, 700W, 800W, 900W, 1000W, 1500W, 2000W, 2500W, 3000W), and the sputtering time is 6~10 min (can be 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min, 10 min), and a thermistor layer is formed on the second dielectric layer; Step S4, Preparation of the first protective layer: Set the substrate temperature to 150~300℃ (values ​​can be 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, etc.), and maintain the cavity vacuum degree ≤5.0×10 -8 Torr uses a sputtering power of 500~6000W (values ​​can be 500W, 550W, 600W, 650W, 700W, 800W, 900W, 1000W, 1500W, 2000W, 2500W, 3000W, 3500W, 4000W, 4500W, 5000W, 5500W, 6000W) and pre-sputters the target material for 1~10 minutes (values ​​can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min). The substrate is transported into a direct current magnetron sputtering vacuum cavity, argon gas with a flow rate of 20-100 sccm (which can be 20 sccm, 30 sccm, 35 sccm, 40 sccm, 45 sccm, 50 sccm, 55 sccm, 60 sccm, 65 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, etc.) and nitrogen gas with a flow rate of 20-100 sccm (which can be 20 sccm, 30 sccm, 35 sccm, 40 sccm, 45 sccm, 50 sccm, 55 sccm, 60 sccm, 65 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, etc.) are introduced, the cavity reaction pressure is 3.0-12.0 mTorr (which can be 3.0 mTorr, 4.0 mTorr, 4.5 mTorr, 5.0 mTorr, 6.0 mTorr, 7.0 mTorr, 8.0 mTorr, 9.0 mTorr, 10.0 mTorr, 11.0 mTorr, 12.0 mTorr), the target input power is 500-6000 W (which can be 500 W, 550 W, 600 W, 650 W, 700 W, 800 W, 900 W, 1000 W, 1500 W, 2000 W, 2500 W, 3000 W, 3500 W, 4000 W, 4500 W, 5000 W, 5500 W, 6000 W), the sputtering time is 0.5-4 min (which can be 0.5 min, 1.0 min, 1.5 min, 2.0 min, 2.5 min, 3.0 min, 3.5 min, 4.0 min), and a first protective layer is formed on the thermistor layer. Step S5, second protective layer preparation: the substrate temperature is kept at 150-250°C (which can be 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, etc.), the cavity pressure is 2.0-5.0 Torr (which can be 2.0 Torr, 2.5 Torr, 3.0 Torr, 3.5 Torr, 4.0 Torr, 4.5 Torr, 5.0 Torr), the reaction gas includes silane (SiH4), ammonia (NH3) and dilution gas nitrogen (N2), the frequency of high-frequency radio frequency is 13.56-40 MHz (which can be 13.56 MHz, 15 MHz, 20 MHz, 25 MHz, 30 MHz, 35 MHz, 40 MHz, etc.), the power is set to 500-1500 W (which can be 500 W, 550 W, 600 W, 650 W, 700 W, 800 W, 900 W, 990 W, 1000 W, 1100 W, 1200 W, 1300 W, 1400 W, 1500 W, etc.), plasma-enhanced chemical vapor deposition for 0-10 s (which can be 0 s, 1 s, 2 s, 3 s, 4 s, 5 s, 6 s, 7 s, 8 s, 9 s, 10 s), and a second protective layer is formed on the first protective layer.

[0028] Further, in step S1, before formal deposition, NH3 with a flow rate of 300-600 sccm (which can be 300 sccm, 350 sccm, 400 sccm, 450 sccm, 500 sccm, 550 sccm, 600 sccm, etc.) is used for pretreatment for 10-50 s (which can be 10 s, 15 s, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s), and the power is 500-3000 W (which can be 500 W, 550 W, 600 W, 650 W, 700 W, 800 W, 900 W, 1000 W, 1500 W, 2000 W, 2500 W, 3000 W), so as to activate the substrate surface, remove adsorbed oxygen and moisture, form a preliminary nitride passivation layer, and improve the interface bonding quality.

[0029] Further, in step S2, the target material is selected to be a silicon target, the target material diameter is 320-321 mm (which can be 320 mm, 320.5 mm, 321 mm), and the distance between the target material and the wafer substrate stage is 40-60 mm (which can be 40 mm, 45 mm, 50 mm, 55 mm, 60 mm).

[0030] Furthermore, in step S3, a vanadium target is selected as the target material, with a target diameter of 320~321mm (which can be 320 mm, 320.5 mm, 321mm, etc.), and the distance between the target material and the substrate stage is 90~150mm (which can be 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, 150 mm, etc.).

[0031] Furthermore, in step S4, a silicon target is selected as the target material, with a target diameter of 320~321mm (which can be 320 mm, 320.5 mm, 321mm, etc.), and the distance between the target material and the substrate stage is 40~60mm (which can be 40 mm, 45 mm, 50 mm, 55 mm, 60mm, etc.).

[0032] Furthermore, in step S5, before formal deposition, NH3 is used for pretreatment for 10-50 seconds (values ​​can be 10s, 15s, 20s, 25s, 30s, 35s, 40s, 450s, 500s, 550s, 600s, etc.) at a flow rate of 300-600 sccm (values ​​can be 300s, 35s, 40s, 45s, 50s) and a power of 500-3000 W (values ​​can be 500W, 550W, 600W, 650W, 700W, 800W, 900W, 1000W, 1500W, 2000W, 2500W, 3000W) to activate the substrate surface and remove adsorbed oxygen and moisture, while forming a preliminary nitriding passivation layer to improve the interfacial bonding quality.

[0033] Further, in steps S1 and S5, the gas flow rates are respectively: SiH4 = 500~1000 sccm (values ​​can be 500sccm, 550sccm, 600sccm, 650sccm, 700sccm, 750sccm, 800sccm, 850sccm, 900sccm, 950sccm, 1000sccm, etc.), NH3 = 200~500 sccm (values ​​can be 200sccm, 250sccm, 300sccm, 350sccm, 400sccm, 450sccm, 470sccm, 500sccm, etc.), N2 = 10000~20000 sccm (10000sccm, 11000sccm, 12000sccm, 13000sccm, 14000sccm, 15000sccm, 16000sccm, 17000sccm, 18000sccm, 19000sccm, 20000sccm).

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] Example 1 A method for fabricating a functional layer of an uncooled infrared detector includes the following steps: Step S1: CVD deposition of silicon nitride dielectric layer Plasma-enhanced chemical vapor deposition (PECVD) was employed. Before formal deposition, the wafers were pretreated with NH3 at a flow rate of 400 sccm (30 s, 1000 W) to activate the wafer surface and remove adsorbed oxygen and moisture, while simultaneously forming a preliminary nitride passivation layer to improve the interfacial bonding quality.

[0036] During the formal deposition process, the wafer temperature was maintained at 180°C, the chamber pressure at 3.5 Torr, and the heater spacing was set to 8 mm. The reactant gases included silane (SiH4), ammonia (NH3), and diluent nitrogen (N2), with flow rates of SiH4 = 650 sccm, NH3 = 470 sccm, and N2 = 18000 sccm, respectively. The high-frequency radio frequency power was set to 990 W, the frequency to 15 MHz, and the reaction time to 9 s, resulting in a first silicon nitride dielectric layer with a thickness of 1000 Å.

[0037] Step S2: PVD deposition of silicon nitride dielectric layer Based on the SJI-SEMI Depommerits P188 Pro PVD system, a silicon target with a purity of 99.9999% and a diameter of 320 mm was selected. The distance between the target and the wafer stage was 50 mm. First, the wafer temperature was set to 200°C, and the cavity vacuum was maintained at 5.0 × 10⁻⁶. -8 The sputtering process was performed at a power of 2000W for 1 minute. Next, the wafer was transferred to a DC magnetron sputtering vacuum chamber, which was purged with argon gas at a flow rate of 50 sccm and nitrogen gas at a flow rate of 40 sccm. The chamber reaction pressure was 4.5 mTorr, the target input power was 2000W, and the sputtering time was 1 minute, resulting in a second silicon nitride dielectric layer with a thickness of 400 Å.

[0038] Step S3: Prepare vanadium oxide thermistor layer The SJI-SEMI-based Depo 188 Pro PVD device was used, and a vanadium target with a purity of 99.995% and a diameter of 320 mm was selected. The distance between the target and the wafer carrier was 150 mm. First, the wafer temperature was set to 150°C, and the chamber vacuum was maintained at 5.0 x 10 -8 Torr. A pre-sputtering target was performed for 1 min at a sputtering power of 3000 W. Then, the wafer was transferred to a direct current magnetron sputtering vacuum chamber, and argon gas with a flow rate of 15 sccm and oxygen gas with a flow rate of 1.5 sccm were introduced. The chamber reaction pressure was 1.6 mTorr, the target input power was 500 W, and the sputtering time was 10 min to prepare a vanadium oxide thermistor layer.

[0039] Step S4, PVD deposition of a silicon nitride protective layer The SJI-SEMI-based Depo 188 Pro PVD device was used, and a silicon target with a purity of 99.9999% and a diameter of 320 mm was selected. The distance between the target and the wafer carrier was 50 mm. First, the wafer temperature was set to 200°C, and the chamber vacuum was maintained at 5.0 x 10 -8 Torr. A pre-sputtering target was performed for 1 min at a sputtering power of 2000 W. Then, the wafer was transferred to a direct current magnetron sputtering vacuum chamber, and argon gas with a flow rate of 50 sccm and nitrogen gas with a flow rate of 40 sccm were introduced. The chamber reaction pressure was 4.5 mTorr, the target input power was 2000 W, and the sputtering time was 1 min to prepare a first silicon nitride protective layer with a thickness of 400 Å.

[0040] Step S5, CVD deposition of a silicon nitride protective layer Plasma enhanced chemical vapor deposition (PECVD) was used. Before formal deposition, the wafer was pretreated with NH3 at a flow rate of 400 sccm for 30 s at a power of 1000 W to activate the wafer surface, remove adsorbed oxygen and moisture, and form a preliminary nitride passivation layer to improve interface bonding quality.

[0041] During the formal deposition process, the wafer temperature was maintained at 180°C, the chamber pressure was 3.5 Torr, and the reaction spacing (Heater Spacing) was set to 8 mm. The reaction gases included silane (SiH4), ammonia (NH3), and dilution gas nitrogen (N2) with flow rates of SiH4 = 650 sccm, NH3 = 470 sccm, and N2 = 18000 sccm, respectively. The high-frequency radio frequency power was set to 990 W, the frequency was 15 MHz, and the reaction time was 9 s to prepare a second silicon nitride protective layer with a thickness of 1000 Å.

[0042] Finally, the temperature coefficient of resistance (TCR) of the uncooled infrared detector functional layer obtained in Example 1 was measured using the four-probe measurement method. The resistance-temperature curve is shown below. Figure 1 As shown. The testing instruments used were a Changzhou Xinyang CXT2665 four-probe sheet resistance tester and a Shenzhen Xinhaomai X4040TBD constant temperature heating stage.

[0043] The stress of the functional layer of the uncooled infrared detector was tested using a Rayphy SV300 stress meter, and the data is recorded in Table 1.

[0044] Example 2 A method for fabricating a functional layer of an uncooled infrared detector includes the following steps: Step S1: PVD deposition of silicon nitride dielectric layer Based on the SJI-SEMI Depommerits P188 Pro PVD equipment, a silicon target with a purity of 99.9999% was selected, the target diameter was 320mm, and the distance between the target and the wafer stage was 50mm.

[0045] First, the wafer temperature is set to 200℃, and the cavity vacuum level is maintained at 5.0 × 10⁻⁶. -8 The sputtering process was performed at a power of 2000W for 1 minute. Next, the wafer was transferred to a DC magnetron sputtering vacuum chamber, with argon gas at a flow rate of 50 sccm and nitrogen gas at a flow rate of 40 sccm. The chamber reaction pressure was 4.5 mTorr, the target input power was 2000W, and the sputtering time was 3.5 minutes, resulting in a silicon nitride dielectric layer with a thickness of 1400 Å.

[0046] Step S2: Prepare vanadium oxide thermistor layer Based on the SJI-SEMI Depommerits P188 Pro PVD system, a vanadium metal target with a purity of 99.995% and a diameter of 320 mm was selected. The distance between the target and the wafer stage was 150 mm. First, the wafer temperature was set to 150°C, and the cavity vacuum was maintained at 5.0 × 10⁻⁶. -8 The sputtering power was 3000W, and the target was pre-sputtered for 1 minute. Then, the wafer was transferred to a DC magnetron sputtering vacuum chamber, and argon gas with a flow rate of 15 sccm and oxygen gas with a flow rate of 1.5 sccm were introduced. The chamber reaction pressure was 1.6 mTorr, the target input power was 500W, and the sputtering time was 10 minutes.

[0047] Step S3: PVD deposition of silicon nitride protective layer Based on the SJI-SEMI Depommerits P188 Pro PVD equipment, a silicon target with a purity of 99.9999% was selected, the target diameter was 320mm, and the distance between the target and the wafer stage was 50mm.

[0048] First, the wafer temperature is set to 200℃, and the cavity vacuum level is maintained at 5.0 × 10⁻⁶. -8 Torr. The target was pre-sputtered for 1 minute using a sputtering power of 2000 W. Next, the wafer was transferred to a DC magnetron sputtering vacuum chamber, with argon gas flow rate of 50 sccm and nitrogen gas flow rate of 40 sccm. The chamber reaction pressure was 4.5 mTorr, the target input power was 2000 W, and the sputtering time was 3.5 minutes, resulting in a silicon nitride protective layer with a thickness of 1400 Å.

[0049] Finally, the temperature coefficient of resistance (TCR) of the uncooled infrared detector functional layer obtained in Example 2 was measured using the four-probe measurement method. The resistance-temperature curve is shown below. Figure 2 As shown. The testing instruments used were a Changzhou Xinyang CXT2665 four-probe sheet resistance tester and a Shenzhen Xinhaomai X4040TBD constant temperature heating stage.

[0050] The stress of the uncooled infrared detector functional layer obtained in Example 2 was tested using a Rayphy SV300 stress meter. The stress data is recorded in Table 1.

[0051] Comparative Example 1 A method for fabricating a functional layer of an uncooled infrared detector includes the following steps: Step S1: CVD deposition of silicon nitride dielectric layer Plasma-enhanced chemical vapor deposition (PECVD) was employed. Before formal deposition, the wafers were pretreated with NH3 at a flow rate of 400 sccm (30 s, 1000 W) to activate the wafer surface and remove adsorbed oxygen and moisture, while simultaneously forming a preliminary nitride passivation layer to improve the interfacial bonding quality.

[0052] During the formal deposition process, the wafer temperature was maintained at 180°C, the chamber pressure at 3.5 Torr, and the heater spacing was set to 8 mm. The reactant gases included silane (SiH4), ammonia (NH3), and diluent nitrogen (N2), with flow rates of SiH4 = 650 sccm, NH3 = 470 sccm, and N2 = 18000 sccm, respectively. The high-frequency radio frequency power was set to 990 W, the frequency to 15 MHz, and the reaction time to 13 s, resulting in a silicon nitride dielectric layer with a thickness of 1400 Å.

[0053] Step S2: Prepare vanadium oxide thermistor layer The P188 Pro PVD equipment of Depo Metals based on SJI-SEMI was selected, a vanadium target with a purity of 99.995% and a diameter of 320 mm was selected, and the distance between the target and the wafer carrier was 150 mm.

[0054] Firstly, the wafer temperature was set to 150°C, and the cavity vacuum degree was kept at 5.0x10 -8 Torr. A 3000W sputtering power was used, and the target was pre-sputtered for 1 min. Then, the wafer was transferred to a direct current magnetron sputtering vacuum chamber, argon gas with a flow rate of 15 sccm and oxygen gas with a flow rate of 1.5 sccm were introduced, the cavity reaction pressure was 1.6 mTorr, the target input power was 500W, and the sputtering time was 10 min.

[0055] Step S3, CVD deposition of silicon nitride dielectric layer Plasma enhanced chemical vapor deposition (PECVD) was used. Before formal deposition, the wafer was pretreated with NH3 flow of 400 sccm (30 s, power 1000 W) to activate the wafer surface, remove adsorbed oxygen and moisture, and form a preliminary nitride passivation layer to improve the interface bonding quality.

[0056] During the formal deposition process, the wafer temperature was kept at 180°C, the cavity pressure was 3.5 Torr, and the reaction spacing (Heater Spacing) was set to 8 mm. The reaction gases included silane (SiH4), ammonia (NH3), and dilution gas nitrogen (N2), with flow rates of SiH4= 650 sccm, NH3= 470 sccm, and N2= 18000 sccm, respectively. The high-frequency radio frequency power was set to 990 W, the frequency was 15 MHz, and the reaction time was 13 s, and a silicon nitride protective layer with a thickness of 1400 Å was obtained.

[0057] Finally, the four-probe method was used to measure the resistance temperature coefficient (TCR) of the functional layer of the uncooled infrared detector obtained in Comparative Example 1, and the resistance temperature curve is shown in Figure 3 The tester uses Changzhou Xinyang CXT2665 four-probe square resistance tester and Shenzhen Xinhua Mai X4040TBD constant temperature heating table.

[0058] The stress of the functional layer of the uncooled infrared detector obtained in Comparative Example 1 was tested by using the Ruiwei Optoelectronics SV300 stress meter, and the data are recorded in Table 1.

[0059] From Figure 1 and Figure 2It can be seen that, through linear fitting of TCR, within the temperature range of 25~30℃, the TCR of the thermistor film in Example 1, which uses the sequence of "CVD deposition of silicon nitride first dielectric layer, PVD deposition of silicon nitride second dielectric layer, PVD deposition of vanadium oxide thermistor layer, PVD deposition of silicon nitride first protective layer, and CVD deposition of silicon nitride second protective layer" from bottom to top, is -2.866%. In Example 2, which uses the sequence of "PVD deposition of silicon nitride dielectric layer, PVD deposition of vanadium oxide thermistor layer, and PVD deposition of silicon nitride..." The TCR of the thermistor film in Example 1 was -2.871% when the protective layer was used, while the TCR of the thermistor film in Comparative Example 1 was -2.555% when the silicon nitride dielectric layer was deposited by CVD, the vanadium oxide thermistor layer was deposited by PVD, and the silicon nitride protective layer was deposited by CVD. The TCR performance of the vanadium oxide thermistor layer in Example 1 was significantly better than that in Comparative Example 1, and almost the same as that in Example 2. This shows that compared with the silicon nitride layer prepared by CVD, the silicon nitride layer prepared by PVD has a significant improvement in the TCR performance of the functional layer.

[0060] Depend on Figures 1-3 It can be seen that, by linear fitting of TCR, in the temperature range of 25~30℃, the TCR of the uncooled infrared detector functional layer in Example 1 and Example 2 is significantly higher than that of the functional layer in Comparative Example 1. This indicates that by replacing the preparation method of the lower silicon nitride support layer and the upper silicon nitride protective layer in contact with the vanadium oxide thermistor layer with PVD method in part or in whole, the TCR performance of the uncooled infrared detector functional layer is significantly improved.

[0061] Table 1. Stress comparison of functional layers in Examples 1-2 and Comparative Example 1

[0062] Note that in Table 1, “﹣” represents the direction, not the magnitude. “﹣” represents compressive stress, and “+” represents tensile stress.

[0063] As shown in Table 1, the stress of the uncooled infrared detector functional layer in Comparative Example 1 is -9 MPa, which is significantly lower than the stress of -420 MPa in the uncooled infrared detector functional layer in Example 2. However, in Example 1, by adding CVD-prepared silicon nitride to the silicon nitride dielectric layer and the protective layer respectively, the stress of the uncooled infrared detector functional layer was optimized to -87 MPa.

[0064] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A functional layer for a uncooled infrared detector, characterized in that The first dielectric layer, the second dielectric layer, the thermal resistance layer, the first protective layer and the second protective layer are sequentially arranged from bottom to top. The first dielectric layer, the second dielectric layer, the first protective layer and the second protective layer are all silicon nitride, and the thermal resistance layer is vanadium oxide. The first dielectric layer is formed by plasma enhanced chemical vapor deposition, and the thickness is 0-1000 angstroms. The second dielectric layer is formed by physical vapor deposition, and the thickness is 400-1400 angstroms. The thermal resistance layer is formed by physical vapor deposition, and the thickness is 600-1000 angstroms. The first protective layer is formed by physical vapor deposition, and the thickness is 400-1400 angstroms. The second protective layer is formed by plasma enhanced chemical vapor deposition, and the thickness is 0-1000 angstroms.

2. A method for preparing a functional layer of a non-cooled infrared detector, characterized in that, The method comprises the following steps: In step S1, the first dielectric layer is prepared by maintaining the substrate temperature at 150-250 DEG C, setting the cavity pressure to 2.0-5.0 Torr, using a reaction gas comprising silane, ammonia and nitrogen, setting the frequency of high-frequency radio frequency to 13-40 MHz, setting the power to 500-1500 W, and performing plasma enhanced chemical vapor deposition for 0-10 s. Step S2, second medium layer preparation: the substrate temperature is set to 150-300℃, the cavity vacuum degree is kept at ≤5.0*10 -8 Torr, the sputtering power is 500-6000W, and the target material is pre-sputtered for 1-10min; In step S2, the second dielectric layer is formed on the first dielectric layer by transferring the substrate into a direct-current magnetron sputtering vacuum cavity, introducing argon with a flow rate of 20-100 sccm and nitrogen with a flow rate of 20-100 sccm, setting the cavity reaction pressure to 3.0-12.0 mTorr, setting the target input power to 500-6000 W, and sputtering for 0.5-4 min. Step S3, thermistor layer preparation: set the substrate temperature to 30-200℃, keep the cavity vacuum degree at ≤5.0*10 - 8 Torr, use a sputtering power of 1000-3000W, pre-sputter the target material for 1-10min; In step S3, the thermal resistance layer is formed on the second dielectric layer by transferring the substrate into a direct-current magnetron sputtering vacuum cavity, introducing argon with a flow rate of 15-30 sccm and oxygen with a flow rate of 1.0-5 sccm, setting the cavity reaction pressure to 1.0-3.0 mTorr, setting the target input power to 50-3000 W, and sputtering for 6-10 min. Step S4, first protective layer preparation: the substrate temperature is set to 150-300℃, the cavity vacuum degree is kept at ≤5.0*10 -8 Torr, the sputtering power is 500-6000W, and the target material is pre-sputtered for 1-10min; In step S4, the first protective layer is formed on the thermal resistance layer by transferring the substrate into a direct-current magnetron sputtering vacuum cavity, introducing argon with a flow rate of 20-100 sccm and nitrogen with a flow rate of 20-100 sccm, setting the cavity reaction pressure to 3.0-12.0 mTorr, setting the target input power to 500-6000 W, and sputtering for 0.5-4 min. In step S5, the second protective layer is formed on the first protective layer by maintaining the substrate temperature at 150-250 DEG C, setting the cavity pressure to 2.0-5.0 Torr, using a reaction gas comprising silane, ammonia and nitrogen, setting the frequency of high-frequency radio frequency to 13.56-40 MHz, setting the power to 500-1500 W, and performing plasma enhanced chemical vapor deposition for 0-10 s.

3. The method of claim 2, wherein the method further comprises: In step S1, before formal deposition, NH3 with a flow rate of 300-600 sccm is used for pretreatment for 10-50 s, and the power is 500-3000 W.

4. The method of claim 2, wherein the method further comprises: In step S2, the target is a silicon target, the target diameter is 320-321 mm, and the distance between the target and the substrate carrier is 40-60 mm.

5. The method of claim 2, wherein the method further comprises: In step S3, the target material is vanadium target, the target material diameter is 320-321 mm, and the distance between the target material and the substrate carrier is 90-150 mm.

6. The method of claim 2, wherein the method further comprises: In step S4, the target material is silicon target, the target material diameter is 320-321 mm, and the distance between the target material and the substrate carrier is 40-60 mm.

7. The method of claim 2, wherein the method further comprises: In step S5, before formal deposition, NH3 with a flow rate of 300-600 sccm is used for pretreatment for 10-50 s, and the power is 500-3000 W.

8. The method of claim 2, wherein the method further comprises: In step S1 and step S5, the gas flow rates are as follows: SiH4= 500-1000 sccm, NH3= 200-500 sccm, and N2= 10000-20000 sccm.

9. A uncooled infrared detector, comprising: The functional layer of claim 1.

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