An uncooled infrared detector functional layer and its fabrication method

Abstract

This invention belongs to the field of functional material preparation technology, specifically relating to an uncooled infrared detector functional layer and its preparation method. The functional layer of this invention, from bottom to top, comprises a first dielectric layer, a second dielectric layer, a thermistor layer, a first protective layer, and a second protective layer; the first and second dielectric layers, and the first and second protective layers are all silicon nitride, and the thermistor layer is vanadium oxide; the first dielectric layer is formed by plasma-enhanced chemical vapor deposition (PECVD) with a thickness of 0–1000 Å; the second dielectric layer is formed by physical vapor deposition (PEVD) with a thickness of 400–1400 Å; the thermistor layer is formed by PEVD with a thickness of 600–1000 Å; the first protective layer is formed by PEVD with a thickness of 400–1400 Å; and the second protective layer is formed by plasma-enhanced chemical vapor deposition (PECVD) with a thickness of 0–1000 Å. The uncooled infrared detector functional layer of this invention exhibits high TCR performance.

Description

Technical Field

[0001] This invention belongs to the field of functional material preparation technology, specifically relating to an uncooled infrared detector functional layer and its preparation method. Background Technology

[0002] The thermistor material in uncooled infrared detectors mainly uses materials such as amorphous silicon and vanadium oxide. The temperature coefficient of resistance (TCR) of the thermistor material is crucial to the detection performance of uncooled infrared detectors, and this should be given priority when selecting the thermistor layer material, as it directly affects the sensitivity of the infrared detector.

[0003] In existing technologies, vanadium oxide is commonly used as the thermistor layer for uncooled infrared detectors. Vanadium oxide is a semiconductor material with a high temperature coefficient of resistance. The technology for preparing vanadium oxide has matured over many years, with magnetron sputtering being the most commonly used method and fully compatible with the detector fabrication process.

[0004] The fabrication process of the functional layer of existing uncooled infrared detectors generally includes, in sequence, a silicon nitride dielectric layer, a vanadium oxide thermistor layer, and a silicon nitride protective layer. For example, invention patent application number CN201610422054.6 discloses a broadband uncooled infrared detector and its fabrication method. The specific process is as follows: PVD is used to deposit electrodes; electrode patterns are etched using photolithography and etching methods; a low-stress Si3N4 dielectric layer is deposited using PECVD; the thickness is such that a portion of the protective Si3N4 layer is etched away from the electrode passivation layer using photolithography, forming contact holes between the electrode and the thermistor layer. Since the electrode thickness is relatively thin, endpoint monitoring (EPD) is used to monitor the end of the etching reaction to prevent the electrode from being completely etched away; after etching the contact holes, a thermistor film is immediately deposited. The thermistor layer material is a VOx film, grown using ion beam deposition or physical vapor deposition. After etching the thermistor film, a low-stress Si3N4 protective layer is deposited using PECVD, and then the protective layer pattern is formed by photolithography. Each Si3N4 film layer is etched to prepare for the release of the sacrificial layer.

[0005] Currently, the fabrication process of the functional layer of an uncooled infrared detector generally includes a silicon nitride dielectric layer, a vanadium oxide thermistor layer, and a silicon nitride protective layer. The silicon nitride dielectric layer and the silicon nitride protective layer are typically obtained by PECVD deposition. However, the PECVD deposition of silicon nitride involves the reaction of two precursor compounds, silane and ammonia: 3SiH4(g) + 4NH3(g) → Si3N4(s) + 12H2(g). Therefore, the Si3N4 film obtained by this PECVD reaction inevitably contains a small amount of hydrogen atoms. During the deposition of the vanadium oxide film, hydrogen elements in the silicon nitride dielectric layer and the subsequent silicon nitride protective layer will inevitably be released and diffuse, undergoing a reduction reaction with the vanadium oxide film. This leads to the transfer of VOx to the metal phase, significantly reducing the film's TCR performance and ultimately causing a decrease in the responsivity of the uncooled infrared detector. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an uncooled infrared detector functional layer and its fabrication method. The uncooled infrared detector functional layer of this invention sequentially comprises a first silicon nitride dielectric layer deposited by CVD, a second silicon nitride dielectric layer deposited by PVD, a vanadium oxide thermistor layer, a first silicon nitride protective layer deposited by PVD, and a second silicon nitride protective layer deposited by CVD. By adding a second silicon nitride dielectric layer between the first silicon nitride dielectric layer and the vanadium oxide thermistor layer, and between the vanadium oxide thermistor layer and the second silicon nitride protective layer, and by using silicon and nitrogen reactive sputtering to prepare the second silicon nitride dielectric layer, which itself does not contain hydrogen and therefore does not affect the vanadium oxide layer, the following benefits are achieved. Furthermore, the dense PVD-deposited silicon nitride dielectric layer film can block the diffusion of hydrogen elements from the CVD-deposited silicon nitride dielectric layer, significantly reducing the reduction of vanadium oxide by hydrogen atoms, ensuring the stability of the vanadium oxide film, and improving its TCR performance.

[0007] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows:

[0008] In a first aspect, embodiments of the present invention provide a functional layer for an uncooled infrared detector, which, from bottom to top, comprises a first dielectric layer, a second dielectric layer, a thermistor layer, a first protective layer, and a second protective layer.

[0009] 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.

[0010] The first dielectric layer was formed by plasma-enhanced chemical vapor deposition and has a thickness of 0~1000 Å.

[0011] The second dielectric layer was formed by physical vapor deposition and has a thickness of 400~1400 Å.

[0012] The thermistor layer is formed by physical vapor deposition and has a thickness of 600~1000 Å.

[0013] The first protective layer was formed by physical vapor deposition and has a thickness of 400~1400 Å.

[0014] The second protective layer is formed using plasma-enhanced chemical vapor deposition and has a thickness of 0–1000 Å.

[0015] Secondly, embodiments of the present invention provide a method for fabricating a functional layer of an uncooled infrared detector, comprising the following steps:

[0016] Step S1: Preparation of the first dielectric layer: The substrate temperature is maintained at 150~250℃, the chamber pressure is 2.0~5.0 Torr, the reaction gases include silane, ammonia and nitrogen, the frequency of the high-frequency radio frequency is 13~40MHz, the power is set to 500~1500W, and plasma-enhanced chemical vapor deposition is performed for 0~10 s to obtain the first dielectric layer.

[0017] Step S2, Preparation of the second dielectric layer: Set the substrate temperature to 150~300℃, and maintain the cavity vacuum degree at ≤5.0×10⁻⁶. -8 Torr, using a sputtering power of 500~6000W, pre-sputter the target for 1~10 minutes;

[0018] The substrate is transferred to a DC magnetron sputtering vacuum chamber, and argon gas with a flow rate of 20~100 sccm and nitrogen gas with a flow rate of 20~100 sccm are introduced. The chamber reaction pressure is 3.0~12.0 mTorr, the target input power is 500~6000W, and the sputtering time is 0.5~4min, forming a second dielectric layer on the first dielectric layer.

[0019] Step S3, Thermistor layer fabrication: Set the substrate temperature to 30~200℃, and maintain the cavity vacuum level at ≤5.0×10⁻⁶. -8 Torr, using a sputtering power of 1000~3000W, pre-sputter the target for 1~10 minutes;

[0020] The substrate is transferred to a DC magnetron sputtering vacuum chamber, and argon gas with a flow rate of 15~30 sccm and oxygen gas with a flow rate of 1.0~5 sccm are introduced. The chamber reaction pressure is 1.0~3.0 mTorr, the target input power is 50~3000W, and the sputtering time is 6~10min, forming a thermistor layer on the second dielectric layer.

[0021] Step S4, Preparation of the first protective layer: Set the substrate temperature to 150~300℃, and maintain the cavity vacuum degree at ≤5.0×10⁻⁶. -8Torr, using a sputtering power of 500~6000W, pre-sputter the target for 1~10 minutes;

[0022] The substrate is transferred to a DC magnetron sputtering vacuum chamber, and argon gas with a flow rate of 20~100 sccm and nitrogen gas with a flow rate of 20~100 sccm are introduced. The chamber reaction pressure is 3.0~12.0 mTorr, the target input power is 500~6000W, and the sputtering time is 0.5~4min, forming a first protective layer on the thermistor layer.

[0023] Step S5: Preparation of the second protective layer: The substrate temperature is maintained at 150~250℃, the chamber pressure is 2.0~5.0 Torr, the reaction gases include silane, ammonia and nitrogen, the frequency of the high-frequency radio frequency is 13.56~40MHz, the power is set to 500~1500W, and plasma-enhanced chemical vapor deposition is performed for 0~10s to form the second protective layer on the first protective layer.

[0024] Furthermore, in step S1, before formal deposition, NH3 with a flow rate of 300~600 sccm is used for pretreatment for 10~50s with a power of 500~3000W.

[0025] Furthermore, in step S2, a silicon target is selected as the target material, with a target diameter of 320~321mm and a distance of 40~60mm between the target material and the substrate stage.

[0026] Furthermore, in step S3, a vanadium target is selected as the target material, with a target diameter of 320~321mm and a distance of 90~150mm between the target material and the substrate stage.

[0027] Furthermore, in step S4, a silicon target is selected as the target material, with a target diameter of 320~321mm and a distance of 40~60mm between the target material and the substrate stage.

[0028] Furthermore, in step S5, before formal deposition, NH3 is used for pretreatment for 10-50 s at a flow rate of 300-600 sccm and a power of 500-3000 W.

[0029] Furthermore, in steps S1 and S5, the gas flow rates are: SiH4 = 500~1000 sccm, NH3 = 200~500 sccm, and N2 = 10000~20000 sccm, respectively.

[0030] Thirdly, embodiments of the present invention provide an uncooled infrared detector, including the functional layer described in the first aspect.

[0031] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0032] The uncooled infrared detector functional layer of this invention sequentially comprises a first silicon nitride dielectric layer deposited by CVD, a second silicon nitride dielectric layer deposited by PVD, a vanadium oxide thermistor layer, a first silicon nitride protective layer deposited by PVD, and a second silicon nitride protective layer deposited by CVD. By adding the second silicon nitride dielectric layer and the first silicon nitride protective layer, a "five-layer sandwich" structure is formed. The PVD deposition of the second silicon nitride dielectric layer is achieved through reactive sputtering of silicon and nitrogen, which itself does not contain hydrogen and therefore does not affect the vanadium oxide layer. Furthermore, the dense material of the PVD-deposited second silicon nitride dielectric layer and the first silicon nitride protective layer can block the diffusion of hydrogen elements from the CVD-deposited first and second silicon nitride dielectric layers, significantly reducing the reduction of vanadium oxide by hydrogen atoms, ensuring the stability of the vanadium oxide film, and improving its TCR performance. In addition, the partial retention of the CVD-deposited silicon nitride significantly reduces the total stress of the functional film. The sum of the thicknesses of the CVD-deposited silicon nitride dielectric layer and the PVD-deposited silicon nitride dielectric layer is the same as the commonly used thickness of the CVD-deposited silicon nitride dielectric 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.

[0033] In addition, as a special case, the fabrication process of the uncooled infrared detector of the present invention sequentially includes: PVD deposition of a silicon nitride dielectric layer, a vanadium oxide thermistor layer, and PVD deposition of a silicon nitride protective layer. The PVD deposition of the silicon nitride dielectric layer is achieved through reactive sputtering of silicon and nitrogen, and it does not contain hydrogen. When it comes into direct contact with the vanadium oxide thermistor layer, it will not reduce the vanadium oxide thermistor layer, thus not affecting the vanadium oxide layer, ensuring the stability of the vanadium oxide film layer, and improving its TCR performance. Attached Figure Description

[0034] Figure 1 The resistance-temperature change curve of the functional layer of the uncooled infrared detector prepared in Embodiment 1 of the present invention.

[0035] Figure 2 The resistance-temperature variation curve of the functional layer of the uncooled infrared detector prepared in Embodiment 2 of the present invention.

[0036] Figure 3 The resistance-temperature variation curve of the functional layer of the uncooled infrared detector prepared in Comparative Example 1 of this invention. Detailed Implementation

[0037] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "inner" and "outer", "upper" and "lower", "left" and "right" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention.

[0038] A functional layer of an uncooled infrared detector, from bottom to top, includes a first dielectric layer, a second dielectric layer, a thermistor layer, a first protective layer, and a second protective layer;

[0039] 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.

[0040] The first dielectric layer is formed using plasma-enhanced chemical vapor deposition, with a thickness ranging from 0 to 1000 Å. The thickness can be 0 Å, 5 Å, 10 Å, 20 Å, 50 Å, 100 Å, 150 Å, 200 Å, 250 Å, 300 Å, 350 Å, 400 Å, 450 Å, 500 Å, 550 Å, 600 Å, 650 Å, 700 Å, 750 Å, 800 Å, 850 Å, 900 Å, 950 Å, 1000 Å, etc.

[0041] The second dielectric layer is formed by physical vapor deposition and has a thickness of 400~1400 Å. The thickness can be 400 Å, 450 Å, 500 Å, 550 Å, 600 Å, 650 Å, 700 Å, 750 Å, 800 Å, 900 Å, 1000 Å, 1100 Å, 1200 Å, 1300 Å, 1400 Å, etc.

[0042] The thermistor layer is formed by physical vapor deposition and has a thickness of 600~1000Å. The thickness can be 600Å, 650Å, 700Å, 750Å, 800Å, 850Å, 900Å, 950Å, 1000Å, etc.

[0043] The first protective layer is formed by physical vapor deposition and has a thickness of 400~1400 Å. The thickness can be 400 Å, 450 Å, 500 Å, 550 Å, 600 Å, 650 Å, 700 Å, 750 Å, 800 Å, 900 Å, 1000 Å, 1100 Å, 1200 Å, 1300 Å, 1400 Å, etc.

[0044] The second protective layer is formed using plasma-enhanced chemical vapor deposition, with a thickness ranging from 0 to 1000 Å. The thickness can be 0 Å, 5 Å, 10 Å, 20 Å, 50 Å, 100 Å, 150 Å, 200 Å, 250 Å, 300 Å, 350 Å, 400 Å, 450 Å, 500 Å, 550 Å, 600 Å, 650 Å, 700 Å, 750 Å, 800 Å, 850 Å, 900 Å, 950 Å, 1000 Å, etc.

[0045] Secondly, embodiments of the present invention provide a method for fabricating a functional layer of an uncooled infrared detector, comprising the following steps:

[0046] Step S1: Preparation of the first dielectric layer: The substrate temperature is maintained at 150~250℃ (values ​​can be 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, etc.), and the cavity pressure is 2.0~5.0 Torr (values ​​can be 2.0 Torr, 2.5 Torr, 3.0 Torr, 3.5 Torr, 4.0 Torr, 4.5 Torr, 5.0 Torr). Torr, etc.), the reaction gases include silane SiH4, ammonia NH3 and dilution nitrogen N2, the high frequency radio frequency is 13~40MHz (values ​​can be 13MHz, 15MHz, 20MHz, 25MHz, 30MHz, 35MHz, 40MHz, etc.), the power is set to 500~1500W (values ​​can be 500W, 550W, 600W, 650W, 700W, 800W, 900W, 990W, 1000W, 1100W, 1200W, 1300W, 1400W, 1500W, etc.), plasma-enhanced chemical vapor deposition is performed for 0~10 s (values ​​can be 0s, 1s, 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s), and the first dielectric layer is obtained;

[0047] Step S2, Preparation of the second dielectric 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 -8Torr 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).

[0048] The substrate is transferred to a DC magnetron sputtering vacuum chamber, and argon gas and nitrogen gas are introduced at a flow rate of 20~100 sccm (values ​​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.). The chamber reaction pressure is 3.0~12.0 mTorr (values ​​can be...). The sputtering times are 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, and 12.0 mTorr, respectively. The target input power is 500~6000W (can be 500W, 550W, 600W, 650W, 700W, 800W, 900W, 1000W, 1500W, 2000W, 2500W, 3000W, 3500W, 4000W, 4500W, 5000W, 5500W, and 6000W), and the sputtering time is 0.5~4 min (can be 0.5 min, 1.0 min, 1.5 min, 2.0 min, and 2.5 min). (3.0 min, 3.5 min, 4.0 min), forming a second dielectric layer on the first dielectric layer;

[0049] Step S3, Thermistor layer fabrication: Set the substrate temperature to 30~200℃ (values ​​can be 30℃, 50℃, 100℃, 150℃, 200℃), and maintain the cavity vacuum degree ≤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).

[0050] 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;

[0051] 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).

[0052] The substrate is transferred to a DC magnetron sputtering vacuum chamber, and argon gas and nitrogen gas are introduced at a flow rate of 20~100 sccm (values ​​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.). The chamber reaction pressure is 3.0~12.0 mTorr (values ​​can be...). The sputtering times are 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, and 12.0 mTorr, respectively. The target input power is 500~6000W (can be 500W, 550W, 600W, 650W, 700W, 800W, 900W, 1000W, 1500W, 2000W, 2500W, 3000W, 3500W, 4000W, 4500W, 5000W, 5500W, and 6000W), and the sputtering time is 0.5~4 min (can be 0.5 min, 1.0 min, 1.5 min, 2.0 min, and 2.5 min). (min, 3.0 min, 3.5 min, 4.0 min), forming a first protective layer on the thermistor layer;

[0053] Step S5, Preparation of the second protective layer: The substrate temperature is maintained at 150~250℃ (values ​​can be 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, etc.), and the cavity pressure is 2.0~5.0 Torr (values ​​can be 2.0 Torr, 2.5 Torr, 3.0 Torr, 3.5 Torr, 4.0 Torr, 4.5 Torr, 5.0 Torr). Torr), the reaction gases include silane (SiH4), ammonia (NH3) and dilution nitrogen (N2), the frequency of the high-frequency radio frequency is 13.56~40MHz (can be 13.56MHz, 15MHz, 20MHz, 25MHz, 30MHz, 35MHz, 40MHz, etc.), the power is set to 500~1500W (can be 500W, 550W, 600W, 650W, 700W, 800W, 900W, 990W, 1000W, 1100W, 1200W, 1300W, 1400W, 1500W, etc.), plasma-enhanced chemical vapor deposition is 0~10 s (can be 0s, 1s, 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s), and a second protective layer is formed on the first protective layer.

[0054] Furthermore, in step S1, before formal deposition, NH3 is used for pretreatment for 10-50 s (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.

[0055] Furthermore, in step S2, a silicon target is selected as the target material, with a target diameter of 320~321mm (which can be 320 mm, 320.5 mm, or 321mm), and the distance between the target material and the wafer substrate stage is 40~60mm (which can be 40 mm, 45 mm, 50 mm, 55 mm, or 60mm).

[0056] 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.).

[0057] 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.).

[0058] 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.

[0059] 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).

[0060] 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.

[0061] Example 1

[0062] A method for fabricating a functional layer of an uncooled infrared detector includes the following steps:

[0063] Step S1: CVD deposition of silicon nitride dielectric layer

[0064] 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.

[0065] 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.

[0066] Step S2: PVD deposition of silicon nitride dielectric layer

[0067] 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.

[0068] Step S3: Prepare vanadium oxide thermistor layer

[0069] 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 Torr. A 3000W sputtering power was used for 1 minute of target pre-sputtering. Next, the wafer was transferred to a DC magnetron sputtering vacuum chamber, through which argon gas at a flow rate of 15 sccm and oxygen gas at 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, resulting in a vanadium oxide thermistor layer.

[0070] Step S4: PVD deposition of silicon nitride protective layer

[0071] 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 Torr. A pre-sputtering target of 2000W was used for 1 minute. Next, the wafer was transferred to a DC magnetron sputtering vacuum chamber, through which argon gas at a flow rate of 50 sccm and nitrogen gas at a flow rate of 40 sccm were introduced. The chamber reaction pressure was 4.5 mTorr, the target input power was 2000W, and the sputtering time was 1 minute, resulting in a first silicon nitride protective layer with a thickness of 400 Å.

[0072] Step S5: CVD deposition of silicon nitride protective layer

[0073] 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.

[0074] During the formal deposition process, the wafer temperature was maintained at 180°C, the chamber pressure was 3.5 Torr, and the heater spacing was set to 8 mm. The reaction gases included silane (SiH4), ammonia (NH3), and dilution 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, resulting in a second silicon nitride protective layer with a thickness of 1000 Å.

[0075] Finally, the temperature coefficient of resistance (TCR) of the functional layer of the uncooled infrared detector 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.

[0076] 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.

[0077] Example 2

[0078] A method for fabricating a functional layer of an uncooled infrared detector includes the following steps:

[0079] Step S1: PVD deposition of silicon nitride dielectric layer

[0080] 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.

[0081] 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.

[0082] Step S2: Prepare vanadium oxide thermistor layer

[0083] 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.

[0084] Step S3: PVD deposition of silicon nitride protective layer

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] Comparative Example 1

[0090] A method for fabricating a functional layer of an uncooled infrared detector includes the following steps:

[0091] Step S1: CVD deposition of silicon nitride dielectric layer

[0092] 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.

[0093] 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.

[0094] Step S2: Prepare vanadium oxide thermistor layer

[0095] Based on the SJI-SEMI Depommerits P188 Pro PVD equipment, a vanadium metal target with a purity of 99.995% was selected, with a target diameter of 320 mm and a distance of 150 mm between the target and the wafer stage.

[0096] First, the wafer temperature is set to 150°C, and the cavity vacuum level is maintained at 5.0 × 10⁻⁶. -8 Torr. A sputtering power of 3000W was used for 1 minute of pre-sputtering of the target. 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.

[0097] Step S3: CVD deposition of silicon nitride dielectric layer

[0098] 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.

[0099] 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 protective layer with a thickness of 1400 Å.

[0100] Finally, the temperature coefficient of resistance (TCR) of the functional layer of the uncooled infrared detector obtained in Comparative Example 1 was measured using the four-probe measurement method. The resistance-temperature curve is shown below. Figure 3 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.

[0101] The stress of the uncooled infrared detector functional layer obtained in Comparative Example 1 was tested using a Rayphy SV300 stress meter. The data is recorded in Table 1.

[0102] Depend on Figure 1 and Figure 2 It 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.

[0103] 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.

[0104] Table 1. Stress comparison of functional layers in Examples 1-2 and Comparative Example 1

[0105]

[0106] Note that in Table 1, “﹣” represents the direction, not the magnitude. “﹣” represents compressive stress, and “+” represents tensile stress.

[0107] 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.

[0108] 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 an uncooled infrared detector, characterized in that, From bottom to top, it includes 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 has a thickness of 50~1000 Å. The second dielectric layer was formed by physical vapor deposition and has a thickness of 400~1400 Å. The thermistor layer is formed by physical vapor deposition and has a thickness of 600~1000 Å. The first protective layer was 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 has a thickness of 50~1000 Å.

2. A method for fabricating a functional layer of an uncooled infrared detector, characterized in that, Includes the following steps: Step S1: Preparation of the first dielectric layer: The substrate temperature is maintained at 150~250℃, the chamber pressure is 2.0~5.0 Torr, the reaction gases include silane, ammonia and nitrogen, the frequency of the high-frequency radio frequency is 13~40MHz, the power is set to 500~1500W, and plasma-enhanced chemical vapor deposition is performed for 0~10 s to obtain the first dielectric layer. Step S2, Preparation of the second dielectric layer: Set the substrate temperature to 150~300℃, and maintain the cavity vacuum degree at ≤5.0×10⁻⁶. -8 Torr, using a sputtering power of 500~6000W, pre-sputter the target for 1~10 minutes; The substrate is transferred to a DC magnetron sputtering vacuum chamber, and argon gas with a flow rate of 20~100 sccm and nitrogen gas with a flow rate of 20~100 sccm are introduced. The chamber reaction pressure is 3.0~12.0 mTorr, the target input power is 500~6000W, and the sputtering time is 0.5~4min, forming a second dielectric layer on the first dielectric layer. Step S3, Thermistor layer fabrication: Set the substrate temperature to 30~200℃, and maintain the cavity vacuum level at ≤5.0×10⁻⁶. - 8 Torr, using a sputtering power of 1000~3000W, pre-sputter the target for 1~10 minutes; The substrate is transferred to a DC magnetron sputtering vacuum chamber, and argon gas with a flow rate of 15~30 sccm and oxygen gas with a flow rate of 1.0~5 sccm are introduced. The chamber reaction pressure is 1.0~3.0 mTorr, the target input power is 50~3000W, and the sputtering time is 6~10min, forming a thermistor layer on the second dielectric layer. Step S4, Preparation of the first protective layer: Set the substrate temperature to 150~300℃, and maintain the cavity vacuum degree at ≤5.0×10⁻⁶. -8 Torr, using a sputtering power of 500~6000W, pre-sputter the target for 1~10 minutes; The substrate is transferred to a DC magnetron sputtering vacuum chamber, and argon gas with a flow rate of 20~100 sccm and nitrogen gas with a flow rate of 20~100 sccm are introduced. The chamber reaction pressure is 3.0~12.0 mTorr, the target input power is 500~6000W, and the sputtering time is 0.5~4min, forming a first protective layer on the thermistor layer. Step S5: Preparation of the second protective layer: The substrate temperature is maintained at 150~250℃, the chamber pressure is 2.0~5.0 Torr, the reaction gases include silane, ammonia and nitrogen, the frequency of the high-frequency radio frequency is 13.56~40MHz, the power is set to 500~1500W, and plasma-enhanced chemical vapor deposition is performed for 0~10s to form the second protective layer on the first protective layer.

3. The method for fabricating the functional layer of the uncooled infrared detector according to claim 2, characterized in that, In step S1, before formal deposition, NH3 with a flow rate of 300~600 sccm is used for pretreatment for 10~50s with a power of 500~3000W.

4. The method for fabricating the functional layer of the uncooled infrared detector according to claim 2, characterized in that, In step S2, a silicon target is selected as the target material, with a target diameter of 320~321mm and a distance of 40~60mm between the target material and the substrate stage.

5. The method for fabricating the functional layer of the uncooled infrared detector according to claim 2, characterized in that, In step S3, a vanadium target is selected as the target material, with a target diameter of 320~321mm and a distance of 90~150mm between the target material and the substrate stage.

6. The method for fabricating the functional layer of the uncooled infrared detector according to claim 2, characterized in that, In step S4, a silicon target is selected as the target material, with a target diameter of 320~321mm and a distance of 40~60mm between the target material and the substrate stage.

7. The method for fabricating the functional layer of the uncooled infrared detector according to claim 2, characterized in that, In step S5, before formal deposition, NH3 is used for pretreatment for 10-50 s at a flow rate of 300-600 sccm and a power of 500-3000 W.

8. The method for fabricating the functional layer of the uncooled infrared detector according to claim 2, characterized in that, In steps S1 and S5, the gas flow rates are: SiH4 = 500~1000 sccm, NH3 = 200~500 sccm, and N2 = 10000~20000 sccm, respectively.

9. An uncooled infrared detector, characterized in that, Includes the functional layer as described in claim 1.

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