A composite structure of insulating layer of thin film sensor based on metal substrate

Abstract

The present invention discloses a composite structure of a thin film sensor insulating layer based on a metal substrate, comprising a metal substrate layer, an adhesive layer arranged on the metal substrate layer, a first insulating layer arranged on the adhesive layer, a second insulating layer arranged on the first insulating layer, a third insulating layer arranged on the second insulating layer, a sensor circuit layer arranged on the third insulating layer, and a protective layer covering the third insulating layer and the sensor circuit layer is arranged or not arranged on the third insulating layer. In the present invention, since the silicon nitride insulating layer does not contact the metal substrate, the possibility of it reacting with the metal substrate in a high temperature environment is eliminated; at the same time, due to the isolation of the silicon nitride insulating layer, the pinholes in the aluminum oxide insulating layer are blocked, so that a short circuit between the sensor circuit layer and the metal substrate will not be caused, thereby ensuring the insulation ability of the thin film sensor based on the metal substrate when used in a high temperature environment.

Description

Technical Field

[0001] The invention relates to a thin film sensor insulating layer composite structure based on a metal substrate in a high temperature environment, belonging to the technical field of thin film sensors. Background Art

[0002] With the industrial Internet and intelligent manufacturing industry upgrades, real-time monitoring of the manufacturing process has become increasingly important. It can not only improve product quality and production efficiency by obtaining key process parameters in the manufacturing process, but also detect problems in advance and intervene in time to avoid serious accidents. Sensors that obtain data such as key process parameters play a very important role. However, due to their large size, traditional sensors are difficult to approach the test point. Even if they are installed in different ways, they will cause great damage to the original physical field, destroying the authenticity of the detection. At the same time, due to the slow response and large hysteresis of traditional sensors, it is difficult to meet the needs of real-time monitoring on site. Thin-film sensors can provide higher spatial and temporal resolutions due to their small size and fast response, making on-site monitoring more realistic and timely. However, due to the brittleness of the substrate material and the high temperature resistance, conventional thin-film sensors based on silicon substrates are difficult to apply to high temperature, high pressure, large strain and corrosive occasions.

[0003] In order to solve the above problems, thin film sensors based on metal substrates have been developed. However, due to the special nature of metal substrates, the substrates need to be polished in a traditional processing environment with low cleanliness, and then transferred to a clean room for sensor production. It is very easy to leave various particles and other pollutants on the metal substrate, resulting in pinholes in the insulating layer produced by the electron beam evaporation (E-beam evaporation) process during the subsequent sensor production process in the clean room. Although the insulating layer produced by the plasma enhanced chemical vapor deposition (PECVD) process does not have pinholes, it will react with the metal substrate at high temperatures. Both phenomena will cause a short circuit between the sensor circuit and the metal substrate, ultimately leading to the failure of sensor production. Summary of the invention

[0004] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a composite structure of an insulating layer of a thin film sensor based on a metal substrate, which ensures the reliability of the insulating layer, thereby realizing the successful use of the thin film sensor based on the metal substrate in a high temperature environment.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: a thin film sensor insulating layer composite structure based on a metal substrate, including a metal substrate layer, an adhesive layer arranged on the metal substrate layer, a first insulating layer arranged on the adhesive layer, a second insulating layer arranged on the first insulating layer, a third insulating layer arranged on the second insulating layer, a sensor circuit layer arranged on the third insulating layer, and a protective layer covering the third insulating layer and the sensor circuit layer or not arranged on the third insulating layer.

[0006] Furthermore, the bonding layer is a metal titanium layer or a metal chromium layer with a thickness of 5 to 50 nm deposited on the metal substrate by a sputtering process, and is used to improve the bonding between the subsequent insulating layer and the metal substrate.

[0007] Furthermore, the first insulating layer is an aluminum oxide insulating layer with a thickness of 0.2 to 5 um deposited on the bonding layer by an electron beam evaporation process.

[0008] Furthermore, the second insulating layer is a silicon nitride insulating layer with a thickness of 0.5-5 um deposited on the first insulating layer by a plasma enhanced chemical vapor deposition process.

[0009] Furthermore, the third insulating layer is an aluminum oxide insulating layer with a thickness of 0.2 to 5 um deposited on the second insulating layer by an electron beam evaporation process.

[0010] Furthermore, the protection layer is an aluminum oxide layer with a thickness of 0.2 to 5 um deposited on the area except the pads of the sensor circuit layer by electron beam evaporation process with the help of a metal mask, and the aluminum oxide layer does not cover the pads of the sensor circuit layer.

[0011] Furthermore, a second protective layer is provided on the protective layer. The second protective layer is a silicon nitride layer with a thickness of 0.5 to 5 um deposited on the protective layer by plasma enhanced chemical vapor deposition process with the aid of a metal mask. The silicon nitride layer does not cover the pads of the sensor circuit layer.

[0012] Furthermore, a third protective layer is provided on the second protective layer. The third protective layer is an aluminum oxide layer with a thickness of 0.2 to 5 um deposited on the second protective layer by electron beam evaporation process with the aid of a metal mask. The aluminum oxide layer does not cover the pads of the sensor circuit layer.

[0013] The process steps for preparing the composite structure of the thin film sensor insulation layer based on the metal substrate are as follows:

[0014] Step 1: Clean the metal substrate with acetone, isopropanol and deionized water, and blow dry with nitrogen to complete the substrate preparation;

[0015] Step 2: depositing a 5-50 nm thick titanium layer on the metal substrate by sputtering;

[0016] Step 3: depositing a 0.2-5 um aluminum oxide insulating layer on the metal titanium layer by electron beam evaporation process;

[0017] Step 4: depositing a 0.5-5 um silicon nitride insulating layer on the aluminum oxide insulating layer by plasma enhanced chemical vapor deposition process;

[0018] Step 5: depositing a 0.2-5 um aluminum oxide insulating layer on the silicon nitride insulating layer by electron beam evaporation process;

[0019] Step 6: depositing a sensor circuit layer on the aluminum oxide insulating layer by photolithography, sputtering, and stripping;

[0020] Step 7: With the help of a metal mask, deposit a 0.2-5 um aluminum oxide protective layer on the area except the pad of the sensor circuit layer by electron beam evaporation process, and the aluminum oxide protective layer does not cover the pad of the sensor circuit;

[0021] Step 8: Using a metal mask, a 0.5-5 um silicon nitride protective layer is deposited on the aluminum oxide protective layer by a plasma enhanced chemical vapor deposition process, and the silicon nitride protective layer does not cover the pads of the sensor circuit;

[0022] Step 9: With the help of a metal mask, a 0.2-5 um aluminum oxide protective layer is deposited on the silicon nitride protective layer by electron beam evaporation process. The aluminum oxide protective layer does not cover the pads of the sensor circuit.

[0023] The beneficial technical effect of the present invention is that since the silicon nitride insulating layer does not contact the metal substrate, the possibility of it reacting with the metal substrate in a high temperature environment is eliminated; at the same time, although there will be pin holes in the aluminum oxide insulating layer, the pin holes are blocked due to the isolation of the intermediate silicon nitride insulating layer, thereby not causing a short circuit between the sensor circuit layer and the metal substrate, thereby ensuring the insulation capability of the thin film sensor based on the metal substrate when used in a high temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further described below in conjunction with the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the structure of Embodiment 5 of the present invention;

[0026] Figure 2 It is a top view schematic diagram of embodiment 5 of the present invention.

[0027] In the figure: 1. Metal base layer, 2. Adhesive layer, 3. First insulating layer, 4. Second insulating layer, 5. Third insulating layer, 6. Protective layer, 7. Sensor circuit layer, 8. Second protective layer, 9. Third protective layer, 10. Pad. DETAILED DESCRIPTION

[0028] Example 1

[0029] A thin film sensor insulating layer composite structure based on a metal substrate comprises a metal substrate layer 1, an adhesive layer 2 arranged on the metal substrate layer 1, a first insulating layer 3 arranged on the adhesive layer 2, a second insulating layer 4 arranged on the first insulating layer 3, a third insulating layer 5 arranged on the second insulating layer 4, and a sensor circuit layer 7 arranged on the third insulating layer 5.

[0030] Example 2

[0031] Preferably, the bonding layer 2 is a metal titanium layer or a metal chromium layer with a thickness of 5 to 50 nm deposited on the metal substrate by a sputtering process, and is used to improve the adhesion between the subsequent insulating layer and the metal substrate.

[0032] The first insulating layer 3 is an aluminum oxide insulating layer with a thickness of 0.2-5 um deposited on the adhesive layer by electron beam evaporation process.

[0033] The second insulating layer 4 is a silicon nitride insulating layer with a thickness of 0.5-5 um deposited on the first insulating layer by a plasma enhanced chemical vapor deposition process.

[0034] The third insulating layer 5 is an aluminum oxide insulating layer with a thickness of 0.2-5 um deposited on the second insulating layer by electron beam evaporation process.

[0035] Example 3

[0036] Preferably, a protection layer 6 covering the third insulating layer 5 and the sensor circuit layer 7 is provided on the third insulating layer 5 .

[0037] The protection layer 6 is an aluminum oxide layer with a thickness of 0.2-5 um, which is deposited on the area except the pads of the sensor circuit layer by electron beam evaporation process with the help of a metal mask. The aluminum oxide layer does not cover the pads of the sensor circuit layer.

[0038] The function of the protective layer 6 is to protect the sensor circuit layer from damage such as scratches and wear from the outside, while also providing a certain degree of insulation capability.

[0039] Example 4

[0040] As a preference for Example 3, a second protective layer 8 is further provided on the protective layer 6. The second protective layer 8 is a silicon nitride layer with a thickness of 0.5 to 5 um deposited on the protective layer 6 by a plasma enhanced chemical vapor deposition process with the aid of a metal mask. The silicon nitride layer does not cover the pads of the sensor circuit layer.

[0041] The function of the second protective layer 8 is to cover the pinholes in the protective layer 6 so that when the sensor protective layer contacts the metal, there will still be no short circuit between the sensor circuit and the metal, while also increasing the mechanical strength of the entire protective layer.

[0042] Example 5

[0043] like Figure 1 , 2 As shown, a third protective layer 9 is further provided on the second protective layer 8. The third protective layer 9 is an aluminum oxide layer with a thickness of 0.2 to 5 um deposited on the second protective layer 8 by electron beam evaporation process with the aid of a metal mask. The aluminum oxide layer does not cover the pads of the sensor circuit layer.

[0044] The function of the third protective layer 9 is to further increase the insulation capacity and mechanical strength of the protective layer to cope with the harsh external conditions.

[0045] Example 6

[0046] The process steps for preparing the composite structure of the thin film sensor insulation layer based on the metal substrate are as follows:

[0047] Step 1: Clean the metal substrate with acetone, isopropanol and deionized water, and blow dry with nitrogen to complete the substrate preparation;

[0048] Step 2: Depositing a 5-50 nm titanium (Ti) layer on the metal substrate by sputtering to improve the adhesion between the subsequent insulating layer and the metal substrate;

[0049] Step 3: Deposit a 0.2-5 um aluminum oxide (Al2O3) insulating layer on the metal titanium (Ti) layer by electron beam evaporation (E-beam evaporation);

[0050] Step 4: Deposit a 0.5-5 um silicon nitride (Si3N4) insulating layer on the aluminum oxide (Al2O3) insulating layer by plasma enhanced chemical vapor deposition (PECVD) process;

[0051] Step 5: Deposit a 0.2-5 um aluminum oxide (Al2O3) insulating layer on the silicon nitride (Si3N4) insulating layer by electron beam evaporation (E-beam evaporation);

[0052] Step 6: Deposit the sensor circuit layer on the aluminum oxide (Al2O3) insulating layer through processes such as photolithography, sputtering, and stripping;

[0053] Step 7: With the help of a metal mask, a 0.2-5 um aluminum oxide (Al2O3) protective layer is deposited on the area except for the sensor circuit layer pad by electron beam evaporation (E-beam evaporation);

[0054] Step 8: With the help of a metal mask, deposit a 0.5-5 um silicon nitride (Si3N4) protective layer on the aluminum oxide protective layer by plasma enhanced chemical vapor deposition (PECVD) (the pads of the sensor circuit should be exposed and not covered by the silicon nitride protective layer);

[0055] Step 9. With the help of a metal mask, deposit a 0.2-5 um aluminum oxide protective layer on the silicon nitride protective layer through electron beam evaporation (the pads of the sensor circuit should be exposed and not covered by the aluminum oxide protective layer).

[0056] This structure not only solves the problem that aluminum oxide (Al2O3) deposited solely by electron beam evaporation (E-beam evaporation) is prone to pinholes and cannot achieve the insulation function as an insulating layer, but also solves the problem that silicon nitride (Si3N4) deposited solely by plasma enhanced chemical vapor deposition (PECVD) technology is prone to react with the metal substrate under high temperature conditions and cause insulation failure.

[0057] The selection of materials for the insulating layers in the composite structure, such as aluminum oxide (Al2O3) and silicon nitride (Si3N4), must meet two requirements: (1) strong insulation capability, that is, high breakdown field strength, otherwise it is easy to cause the insulation performance to degrade or even lose the insulation performance under high temperature conditions; (2) the thermal expansion coefficient of the insulating layer must be close to that of the metal substrate, and the difference should not be too large. At the same time, the thermal expansion coefficients of each other must also be close, otherwise it will cause cracks in the insulating layer under high temperature conditions, reducing its insulation performance.

[0058] Since the silicon nitride insulating layer of the present invention does not contact the metal substrate, the possibility of it reacting with the metal substrate in a high temperature environment is eliminated; at the same time, although there will be pin holes in the aluminum oxide insulating layer, the pin holes are blocked due to the isolation of the intermediate silicon nitride insulating layer, thereby not causing a short circuit between the sensor circuit layer and the metal substrate, thereby ensuring the insulation ability of the thin film sensor based on the metal substrate when used in a high temperature environment.

[0059] Silicon nitride (Si3N4) can be used as an insulating layer under high temperature conditions, and insulation failure will not occur due to the reaction between the silicon nitride (Si3N4) insulating layer and the metal substrate under high temperature conditions; aluminum oxide (Al2O3) can be used as an insulating layer in a high temperature environment, and even if pin holes exist in the aluminum oxide (Al2O3) insulating layer, the structure of the present invention will not cause insulation function failure.

[0060] The above embodiments are merely used as explanations of the technical solutions of the present invention and cannot be used as limitations of the technical solutions of the present invention. Any simple improvements based on the present invention fall within the protection scope of the present invention.

Claims

1. A composite structure of a thin film sensor insulating layer based on a metal substrate, characterized in that: It includes a metal base layer, an adhesive layer arranged on the metal base layer, a first insulating layer arranged on the adhesive layer, a second insulating layer arranged on the first insulating layer, a third insulating layer arranged on the second insulating layer, a sensor circuit layer arranged on the third insulating layer, and a protective layer covering the third insulating layer and the sensor circuit layer arranged on the third insulating layer; the adhesive layer is a metal titanium layer or a metal chromium layer with a thickness of 5 to 50 nm deposited on the metal base; the first insulating layer is an aluminum oxide insulating layer with a thickness of 0.2 to 5 um deposited on the adhesive layer by an electron beam evaporation process; the second insulating layer is a silicon nitride insulating layer with a thickness of 0.5 to 5 um deposited on the first insulating layer by a plasma enhanced chemical vapor deposition process; the third insulating layer is an aluminum oxide insulating layer with a thickness of 0.2 to 5 um deposited on the second insulating layer by an electron beam evaporation process; the protective layer is an aluminum oxide layer with a thickness of 0.2 to 5 um deposited on an area other than the sensor circuit layer pad by an electron beam evaporation process with the aid of a metal mask, and the aluminum oxide layer does not cover the sensor circuit layer pad.

2. The thin film sensor insulating layer composite structure based on a metal substrate according to claim 1, characterized in that: A second protective layer is also provided on the protective layer. The second protective layer is a silicon nitride layer with a thickness of 0.5 to 5 um deposited on the protective layer by plasma enhanced chemical vapor deposition process with the aid of a metal mask. The silicon nitride layer does not cover the pads of the sensor circuit layer.

3. The thin film sensor insulating layer composite structure based on a metal substrate according to claim 2, characterized in that: A third protective layer is also arranged on the second protective layer. The third protective layer is an aluminum oxide layer with a thickness of 0.2 to 5 um deposited on the second protective layer by electron beam evaporation process with the aid of a metal mask. The aluminum oxide layer does not cover the pads of the sensor circuit layer.

4. The thin film sensor insulating layer composite structure based on a metal substrate according to claim 1, characterized in that: The preparation process steps are as follows: Step 1: Clean the metal substrate with acetone, isopropanol and deionized water, and blow dry with nitrogen to complete the substrate preparation; Step 2: depositing a 5-50 nm thick titanium layer on the metal substrate by sputtering; Step 3: depositing a 0.2-5 um aluminum oxide insulating layer on the metal titanium layer by electron beam evaporation process; Step 4: depositing a 0.5-5 um silicon nitride insulating layer on the aluminum oxide insulating layer by plasma enhanced chemical vapor deposition process; Step 5: depositing a 0.2-5 um aluminum oxide insulating layer on the silicon nitride insulating layer by electron beam evaporation process; Step 6: depositing a sensor circuit layer on the aluminum oxide insulating layer by photolithography, sputtering, and stripping; Step 7: With the help of a metal mask, deposit a 0.2-5 um aluminum oxide protective layer on the area except the pad of the sensor circuit layer by electron beam evaporation process, and the aluminum oxide protective layer does not cover the pad of the sensor circuit; Step 8: Using a metal mask, a 0.5-5 um silicon nitride protective layer is deposited on the aluminum oxide protective layer by a plasma enhanced chemical vapor deposition process, and the silicon nitride protective layer does not cover the pads of the sensor circuit; Step 9: With the help of a metal mask, a 0.2-5 um aluminum oxide protective layer is deposited on the silicon nitride protective layer by electron beam evaporation process. The aluminum oxide protective layer does not cover the pads of the sensor circuit.

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