An embedded thin film sensor

Abstract

The present invention discloses an embedded thin film sensor, including a metal substrate layer, a substrate adhesive layer, an insulating layer, an upper adhesive layer, a seed layer, and a packaging layer connected in sequence, wherein the sensor circuit layer is embedded in the insulating layer, and the pads of the sensor circuit are exposed for connection. The present invention adopts an embedded structure to fully protect the sensor and meet the use under more severe conditions; the composite structure of the insulating layer not only solves the problem that aluminum oxide deposited by electron beam evaporation alone cannot achieve the insulating function as the insulating layer, but also solves the problem that silicon nitride deposited by plasma enhanced chemical vapor deposition alone is easy to react with the metal substrate under high temperature conditions and cause insulation failure, but also solves the problem of a large amount of time and cost spent on depositing a certain thickness of insulating layer by atomic layer deposition in response to high temperature conditions, and the atomic layer deposition of aluminum oxide with a thickness of 10-500nm is within the normal range; the protective layer manufacturing process is simple, time-saving, cost-effective, and high-strength.

Description

Technical Field

[0001] The invention relates to an embedded thin film sensor, which is mainly used in harsh environments and belongs 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. On the one hand, 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. Therefore, thin film sensors came into being. With their small size and fast response, they can provide higher spatial resolution and time resolution, 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. In order to cope with damage such as scratches and wear in the external environment, the sensors need to be protected. The usual method is to use physical vapor deposition or chemical vapor deposition processes to deposit a protective layer on the sensor.

[0004] However, due to process limitations, the deposited protective layer is very thin and the types of materials for the protective layer are limited. It takes a lot of time and cost to deposit a protective layer with a certain thickness and sufficient strength.

[0005] Diffusion bonding is a method of achieving metallized packaging. It requires heating the metal to be welded to a temperature of 60%-80% of its melting point, while applying pressure to the packaging components to achieve contact between the two surfaces. In order to reduce oxidation, it is also necessary to operate in a vacuum environment, and the process time is relatively long, resulting in a lot of time consumption and cost. Higher temperatures may damage or reduce the performance of the sensor circuit and the metal substrate. Summary of the invention

[0006] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a structure and manufacturing process for embedding a sensor into metal, thereby achieving insulation of a thin film sensor based on a metal substrate, while achieving effective protection of the sensor at a relatively low cost, and being able to cope well with various harsh conditions.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: an embedded thin film sensor, including a metal base layer, a base adhesive layer, an insulating layer, an upper adhesive layer, a seed layer, and a packaging layer connected in sequence, the sensor circuit layer is embedded in the insulating layer, and the pads of the sensor circuit layer are exposed for connection.

[0008] Furthermore, the substrate bonding layer is a 5-50 nm metal titanium layer deposited on the metal substrate by a sputtering process, so as to improve the bonding between the insulating layer and the metal substrate.

[0009] Furthermore, the insulating layer is a first insulating layer of aluminum oxide with a thickness of 0.2 to 5 um deposited on the base adhesive layer by electron beam evaporation process;

[0010] A second insulating layer of silicon nitride with a thickness of 0.5 to 5 μm is deposited on the first insulating layer of aluminum oxide by a plasma enhanced chemical vapor deposition process;

[0011] or a second aluminum oxide insulating layer with a thickness of 10 to 500 nm deposited on the first aluminum oxide insulating layer by an atomic layer deposition process;

[0012] A 0.2-5 um thick aluminum oxide third insulating layer is deposited on the silicon nitride second insulating layer or the aluminum oxide second insulating layer by electron beam evaporation process.

[0013] Furthermore, the sensor circuit layer is embedded in the insulating layer, which means: the sensor circuit layer is deposited on the aluminum oxide third insulating layer by photolithography, sputtering, and stripping processes;

[0014] With the help of a metal mask, a 0.2-5 um aluminum oxide fourth insulating layer is deposited on the area except the sensor circuit pad by electron beam evaporation process.

[0015] Furthermore, on the aluminum oxide fourth insulating layer, a 0.5-5 um silicon nitride fifth insulating layer is deposited on the aluminum oxide fourth insulating layer by a plasma enhanced chemical vapor deposition process with the aid of a metal mask; or a 10-500 nm aluminum oxide fifth insulating layer is deposited on the aluminum oxide fourth insulating layer by an atomic layer deposition process.

[0016] Furthermore, on the silicon nitride fifth insulating layer or the aluminum oxide fifth insulating layer, a 0.2-5 um thick aluminum oxide sixth insulating layer is deposited on the silicon nitride fifth insulating layer or the aluminum oxide fifth insulating layer by electron beam evaporation process with the aid of a metal mask.

[0017] Furthermore, the upper bonding layer is a titanium metal layer with a thickness of 5 to 50 nm deposited on the aluminum oxide insulating layer by a sputtering process.

[0018] Furthermore, the seed layer is a nickel metal layer with a thickness of 10 to 500 nm deposited on the upper bonding layer by a sputtering process, and the nickel metal layer serves as a seed layer for the electroplating process.

[0019] Furthermore, the packaging layer is a metal layer with a thickness of 1 to 5000 um deposited by an electroplating process, thereby completing the embedded packaging of the sensor.

[0020] Furthermore, the packaging layer is one of the electroplatable metals such as nickel, copper, nickel-cobalt, etc.

[0021] The production method thereof includes the following steps:

[0022] The metal substrate is prepared by cleaning with acetone, isopropanol and deionized water and drying with nitrogen gas;

[0023] A 5-50 nm titanium layer is deposited on the metal substrate by sputtering process;

[0024] A 0.2-5 um aluminum oxide insulating layer is deposited on the metal titanium layer by electron beam evaporation process;

[0025] Depositing a 0.5-5 μm silicon nitride insulating layer on the aluminum oxide insulating layer by a plasma enhanced chemical vapor deposition process; or depositing a 10-500 nm aluminum oxide insulating layer on the aluminum oxide insulating layer deposited in the previous step by an atomic layer deposition process;

[0026] Depositing a 0.2-5 um aluminum oxide insulating layer on the silicon nitride insulating layer or the aluminum oxide insulating layer by electron beam evaporation process;

[0027] Depositing a sensor circuit layer on the aluminum oxide insulating layer by photolithography, sputtering, stripping and other processes;

[0028] With the help of a metal mask, an aluminum oxide insulating layer of 0.2 to 5 um is deposited on the area except the sensor circuit pad by electron beam evaporation process;

[0029] With the help of a metal mask, a 0.5-5 um silicon nitride insulating layer is deposited on the aluminum oxide insulating layer by a plasma enhanced chemical vapor deposition process; or a 10-500 nm aluminum oxide insulating layer is deposited on the aluminum oxide insulating layer deposited in the previous step by an atomic layer deposition process. The pads of the sensor circuit should be exposed and not covered by the silicon nitride / aluminum oxide insulating layer;

[0030] With the help of a metal mask, a 0.2-5 um aluminum oxide insulating layer is deposited on the silicon nitride insulating layer / aluminum oxide insulating layer by electron beam evaporation process. The pads of the sensor circuit should be exposed and not covered by the aluminum oxide insulating layer.

[0031] A titanium layer of 5 to 50 nm and a nickel layer of 10 to 500 nm are deposited on the alumina insulating layer by sputtering. The pads of the sensor circuit should be exposed and not covered by the sputtered metal layer.

[0032] Then, a metal layer with a thickness of 1-5000 um is deposited through the electroplating process to complete the embedded packaging of the sensor. The pads of the sensor circuit should be exposed and not covered by the electroplated metal layer.

[0033] The beneficial technical effects of the present invention are as follows: the embedded structure completely embeds the sensor into the metal, so that the sensor is completely protected and can meet the use under more severe conditions; the insulating layer composite structure not only solves the problem that pinholes are prone to appear in the aluminum oxide deposited by electron beam evaporation as the insulating layer and the insulating function cannot be realized, but also solves the problem that silicon nitride deposited by plasma enhanced chemical vapor deposition process is prone to react with the metal substrate under high temperature conditions and cause insulation failure, but also solves the problem of a large amount of time and cost spent on depositing a certain thickness of insulating layer by atomic layer deposition to meet high temperature conditions. The thickness of aluminum oxide deposited by atomic layer deposition in the present invention is 10-500nm, which is within the normal range; the manufacturing process of the protective layer is simple, the time is short, the cost is low, and the strength is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention is further described below in conjunction with the accompanying drawings.

[0035] Figure 1 It is a schematic diagram of the structure of the present invention.

[0036] In the figure: 1. Metal base layer, 2. Base bonding layer, 3. Insulating layer, 31. First insulating layer, 32. Second insulating layer, 33. Third insulating layer, 34. Fourth insulating layer, 35. Fifth insulating layer, 36. Sixth insulating layer, 4. Upper bonding layer, 5. Seed layer, 6. Packaging layer, 7. Sensor circuit layer. DETAILED DESCRIPTION

[0037] Example 1

[0038] An embedded thin film sensor includes a metal base layer 1, a base adhesive layer 2, an insulating layer 3, an upper adhesive layer 4, a seed layer 5, and a packaging layer 6 which are connected in sequence. A sensor circuit layer 7 is embedded in the insulating layer 3, and the pads of the sensor circuit layer 7 are exposed for connection.

[0039] Example 2

[0040] like Figure 1As shown, as a specific design of Example 1, the base bonding layer 2 is a 5-50 nm metal titanium layer deposited on the metal base by sputtering process, which is used to improve the adhesion between the insulating layer 3 and the metal base; metal chromium also has adhesion.

[0041] The insulating layer 3 is a first insulating layer 31 of aluminum oxide with a thickness of 0.2 to 5 um deposited on the base adhesive layer 2 by electron beam evaporation process;

[0042] A 0.5-5 um thick silicon nitride second insulating layer 32 is deposited on the aluminum oxide first insulating layer 31 by a plasma enhanced chemical vapor deposition process;

[0043] or a second aluminum oxide insulating layer with a thickness of 10 to 500 nm deposited on the first aluminum oxide insulating layer by an atomic layer deposition process;

[0044] A third aluminum oxide insulating layer 33 with a thickness of 0.2-5 um is deposited on the silicon nitride second insulating layer 32 or the aluminum oxide second insulating layer by electron beam evaporation process.

[0045] The sensor circuit layer 7 is embedded in the insulating layer 3, which means that the sensor circuit layer is deposited on the third insulating layer 33 of aluminum oxide by photolithography, sputtering and stripping processes;

[0046] With the help of a metal mask, a 0.2-5 um aluminum oxide fourth insulating layer 34 is deposited on the area except the sensor circuit pad by electron beam evaporation process.

[0047] On the aluminum oxide fourth insulating layer 34, a 1-5 um silicon nitride fifth insulating layer 35 is deposited on the aluminum oxide fourth insulating layer 34 by plasma enhanced chemical vapor deposition process with the help of a metal mask; or a 10-500 nm aluminum oxide fifth insulating layer is deposited on the aluminum oxide fourth insulating layer 34 by atomic layer deposition process.

[0048] On the silicon nitride fifth insulating layer 35 or the aluminum oxide fifth insulating layer, a 0.2-5 um thick aluminum oxide sixth insulating layer 36 is deposited on the silicon nitride fifth insulating layer 35 or the aluminum oxide fifth insulating layer by electron beam evaporation process with the aid of a metal mask.

[0049] The upper bonding layer 4 is a titanium metal layer with a thickness of 5-50 nm deposited on the aluminum oxide sixth insulating layer 36 by a sputtering process.

[0050] The seed layer 5 is a nickel metal layer, a copper metal layer, or a nickel-cobalt metal layer with a thickness of 10 to 500 nm deposited on the upper bonding layer by a sputtering process, and serves as a seed layer for the electroplating process.

[0051] The packaging layer 6 is a metal layer with a thickness of 1 to 5000 um deposited by an electroplating process, which completes the embedded packaging of the sensor.

[0052] The packaging layer 6 is a metal layer with a thickness of 1-5000 um deposited by electroplating process, which completes the embedded packaging of the sensor. The packaging layer is one of the electroplatable metals such as nickel, copper, nickel-cobalt, etc.

[0053] Example 3

[0054] As the specific preparation method of Examples 1 and 2, the steps are as follows:

[0055] The metal substrate was prepared by cleaning (acetone, isopropyl alcohol, and deionized water) and drying with nitrogen;

[0056] A 5-50 nanometer (nm) titanium (Ti) layer is deposited on the metal substrate by sputtering to improve the adhesion between the subsequent insulating layer and the metal substrate;

[0057] Deposit a 0.2-5 micron (um) aluminum oxide (Al2O3) insulating layer on the metal titanium (Ti) layer by electron beam evaporation (E-beam evaporation);

[0058] Depositing a 0.5-5 micron (um) silicon nitride (Si3N4) insulating layer on the aluminum oxide (Al2O3) insulating layer by plasma enhanced chemical vapor deposition (PECVD); or depositing a 10-500 nanometer (nm) aluminum oxide (Al2O3) insulating layer on the aluminum oxide (Al2O3) insulating layer deposited in the previous step by atomic layer deposition (ALD);

[0059] Depositing a 0.2-5 micron (um) aluminum oxide (Al2O3) insulating layer on the silicon nitride (Si3N4) insulating layer or the aluminum oxide (Al2O3) insulating layer by electron beam evaporation (E-beam evaporation);

[0060] The sensor circuit layer is deposited on the aluminum oxide (Al2O3) insulating layer by photolithography, sputtering, stripping and other processes;

[0061] Using a metal mask, a 0.2-5 micron (um) aluminum oxide (Al2O3) insulating layer is deposited on the area except for the sensor circuit pads by electron beam evaporation (E-beam evaporation);

[0062] With the help of a metal mask, a 0.5-5 micron (um) silicon nitride (Si3N4) insulating layer is deposited on the aluminum oxide (Al2O3) insulating layer by plasma enhanced chemical vapor deposition (PECVD); or a 10-500 nanometer (nm) aluminum oxide (Al2O3) insulating layer is deposited on the aluminum oxide (Al2O3) insulating layer deposited in the previous step by atomic layer deposition (ALD); (the pads of the sensor circuit should be exposed and not covered by the silicon nitride / aluminum oxide insulating layer)

[0063] With the help of a metal mask, deposit a 0.2-5 micron (um) aluminum oxide (Al2O3) insulating layer on the silicon nitride (Si3N4) insulating layer / aluminum oxide (Al2O3) insulating layer through electron beam evaporation (E-beam evaporation) (the pads of the sensor circuit should be exposed and not covered by the aluminum oxide insulating layer);

[0064] A titanium layer (Ti) of 5-50 nanometers (nm) and a nickel layer (Ni) of 10-500 nanometers (nm) are deposited on the aluminum oxide insulating layer by sputtering, wherein the titanium layer acts as a bonding agent between the insulating layer and the metal nickel layer (Ni), and the nickel layer (Ni) is used as a seed layer for the electroplating process; (the pads of the sensor circuit should be exposed and not covered by the sputtered metal layer);

[0065] Then, a metal layer is deposited through an electroplating process with a thickness of 1-5000 um to complete the embedded packaging of the sensor; the pads of the sensor circuit should be exposed and not covered by the electroplated metal layer.

[0066] The present invention adopts an embedded structure to completely embed the sensor into the metal, so that the sensor is completely protected and can meet the use under more severe conditions; the composite structure of the insulating layer not only solves the problem that pinholes are prone to appear in the aluminum oxide deposited by electron beam evaporation as the insulating layer and the insulating function cannot be realized, but also solves the problem that silicon nitride deposited by plasma enhanced chemical vapor deposition process is prone to react with the metal substrate under high-temperature use conditions to cause insulation failure, but also solves the problem of a lot of time and cost spent on depositing a certain thickness of insulating layer by atomic layer deposition to meet high-temperature conditions. The thickness of aluminum oxide deposited by atomic layer deposition in the present invention is 10-500nm, which is within the normal range; the manufacturing process of the protective layer is simple, the time is short, the cost is low, and the strength is high.

[0067] 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. An embedded thin film sensor, characterized in that: The method comprises connecting a metal base layer, a base adhesive layer, an insulating layer, an upper adhesive layer, a seed layer, and a packaging layer in sequence, wherein the sensor circuit layer is embedded in the insulating layer, and the pads of the sensor circuit are exposed for connection; the base adhesive layer is a 5-50 nm metal titanium layer or a metal chromium layer deposited on the metal base by a sputtering process to improve the adhesion between the insulating layer and the metal base; the insulating layer is a 0.2-5 um thick aluminum oxide first insulating layer deposited on the adhesive layer by an electron beam evaporation process; A second insulating layer of silicon nitride with a thickness of 0.5 to 5 um is deposited on the first insulating layer of aluminum oxide by a plasma enhanced chemical vapor deposition process; Or a second aluminum oxide insulating layer with a thickness of 10 to 500 nm is deposited on the first aluminum oxide insulating layer by an atomic layer deposition process; a third aluminum oxide insulating layer with a thickness of 0.2 to 5 um is deposited on the second silicon nitride insulating layer or on the second aluminum oxide insulating layer by an electron beam evaporation process; the sensor circuit layer is embedded in the insulating layer means: the sensor circuit layer is deposited on the third aluminum oxide insulating layer by photolithography, sputtering, and stripping processes; With the help of a metal mask, a 0.2-5 um aluminum oxide fourth insulating layer is deposited on the area except the sensor circuit pad by electron beam evaporation process; the seed layer is a nickel metal layer or copper metal layer or nickel-cobalt metal layer with a thickness of 10-500 nm deposited on the upper bonding layer by sputtering process, which serves as the seed layer of the electroplating process.

2. The embedded thin film sensor according to claim 1, characterized in that: On the aluminum oxide fourth insulating layer, a 0.5-5 um silicon nitride fifth insulating layer is deposited on the aluminum oxide fourth insulating layer by plasma enhanced chemical vapor deposition process with the help of a metal mask; or a 10-500 nm aluminum oxide fifth insulating layer is deposited on the aluminum oxide fourth insulating layer by atomic layer deposition process.

3. The embedded thin film sensor according to claim 1, characterized in that: On the silicon nitride fifth insulating layer or the aluminum oxide fifth insulating layer, a 0.2-5 um thick aluminum oxide sixth insulating layer is deposited on the silicon nitride fifth insulating layer or the aluminum oxide fifth insulating layer by electron beam evaporation process with the aid of a metal mask.

4. The embedded thin film sensor according to claim 1, characterized in that: The upper bonding layer is a metal titanium layer or a metal chromium layer with a thickness of 5 to 50 nm deposited on the aluminum oxide insulating layer by a sputtering process.

5. The embedded thin film sensor according to claim 1, characterized in that: The packaging layer is a metal layer with a thickness of 1 to 5000 um deposited by an electroplating process, which completes the embedded packaging of the sensor.

6. The embedded thin film sensor according to claim 5, characterized in that: The encapsulation layer is a type of electroplated metal, including nickel, copper, and nickel-cobalt.

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