Sensor chip and manufacturing method thereof
By using materials such as titanium or aluminum, titanium and silicon nitride as absorption layers, the problem of low absorption rate of traditional thermopile infrared detectors is solved, and the absorption rate and testing accuracy of infrared light are improved.
Patent Information
- Application Number
- CN202311088753.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-28
- Publication Date
- 2025-03-04
AI Technical Summary
The absorption layer of the traditional thermopile infrared detector has a low absorption rate of infrared light, resulting in a decrease in test accuracy.
Materials such as titanium or aluminum, titanium and silicon nitride are used as the absorption layer, and the absorption performance of the absorption layer is improved through deposition and etching processes.
The absorption rate of infrared light of the sensor chip is improved, thereby improving the testing accuracy and sensitivity.
Smart Images
Figure CN119555218A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of sensor chips, and specifically relates to a sensor chip and a method for manufacturing the same. Background Art
[0002] As the earliest thermal infrared detector, the thermopile infrared detector initially used the vacuum coating method, but the device size was large and difficult to mass produce. With the investment in MEMS technology, silicon-based thermopile infrared detectors with closed membrane structures made by micro-machines have emerged. Due to their low cost, suitable for mass production, large output signal, high sensitivity, small size, and easy packaging, they have quickly become a research hotspot.
[0003] In the related art, the main defect of the traditional thermopile infrared detector is the low absorption rate of the absorption layer to infrared light. Summary of the invention
[0004] The purpose of the present application is to provide a sensor chip and a method for manufacturing the same.
[0005] The sensor chip provided in the present application comprises a wafer substrate, a supporting layer and an absorption layer for absorbing infrared light; the supporting layer is connected to the wafer substrate, and the absorption layer is at least partially covered on the supporting layer; the sensor chip has a cavity, and the cavity is at least partially located in the wafer substrate, and along the thickness direction of the chip, the absorption layer and the cavity are located on both sides of the supporting layer; the material of the absorption layer is selected from titanium, or the material of the absorption layer includes at least two of aluminum, titanium and silicon nitride.
[0006] The inventors found that the material of the absorption layer is an important factor leading to the low absorption rate of infrared light. In the present application, the material of the absorption layer is selected from titanium, or the material of the absorption layer includes at least two of aluminum, titanium and silicon nitride. Since titanium, or at least two of aluminum, titanium and silicon nitride as absorption materials have good absorption performance for infrared light, the absorption rate of the sensor chip to infrared light is improved.
[0007] The present application also provides a method for manufacturing a sensor chip, the method comprising the following steps:
[0008] depositing a support layer on a surface of a wafer substrate;
[0009] Depositing a first thermocouple layer on a portion of the surface of the support layer, depositing an isolation layer on at least a portion of the surface of the first thermocouple layer, and depositing a second thermocouple layer on at least a portion of the surface of the isolation layer;
[0010] Depositing an absorption layer on a portion of the surface of the support layer, with a gap between the absorption layer and the first thermocouple layer, the isolation layer and the second thermocouple layer, wherein the material of the absorption layer is selected from titanium, or the material of the absorption layer includes at least two of aluminum, titanium and silicon nitride;
[0011] A hole is etched in a surface of at least one of the support layer and the absorption layer, and a cavity is etched in the wafer substrate through the hole.
[0012] In the manufacturing method of the present application, the material of the absorption layer is selected from titanium, or the material of the absorption layer includes at least two of aluminum, titanium and silicon nitride. Since titanium, or at least two of aluminum, titanium and silicon nitride as absorption materials have good absorption performance for infrared light, the absorption rate of the sensor chip to infrared light is improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 is a cross-sectional view of a sensor chip;
[0014] Figure 2 is a top view schematic diagram of a sensor chip;
[0015] Figure 3 for Figure 1 A is an enlarged schematic diagram. DETAILED DESCRIPTION
[0016] The formation and use of the currently preferred embodiments are discussed in detail below. However, it should be appreciated that the present application provides many applicable inventive concepts that can be specifically implemented in a variety of specific contexts. The specific embodiments discussed merely illustrate specific ways to form and use the present application and do not limit the scope of the present application. In order to more fully understand the present application and its advantages, it is now described in conjunction with the accompanying drawings.
[0017] Since factors such as the thickness of the absorption layer in the sensor chip, the roughness of the surface of the absorption layer, and the material used for the absorption layer have a certain influence on the absorption rate of infrared light, after a large number of experimental operations, the inventors found that the material of the absorption layer is an important factor leading to the low absorption rate of infrared light, which leads to a decrease in the test accuracy of the sensor chip. Based on this technical problem, the present application provides a sensor chip and a method for manufacturing the same.
[0018] The sensor chip in the present application comprises a wafer substrate 1, a support layer 2 and an absorption layer 4 for absorbing infrared light; the support layer 2 is connected to the wafer substrate 1, and the absorption layer 4 is at least partially covered on the support layer 2; the sensor chip has a cavity 5, and the cavity 5 is at least partially located in the wafer substrate 1. Along the thickness direction Z of the chip, the absorption layer 4 and the cavity 5 are located on both sides of the support layer 2, as shown in detail. Figure 1 shown.
[0019] In some embodiments, the material of the absorption layer 4 is selected from titanium, or the material of the absorption layer 4 includes at least two of aluminum, titanium and silicon nitride. Titanium, or at least two of aluminum, titanium and silicon nitride are selected as the material of the absorption layer, because titanium, or at least two of aluminum, titanium and silicon nitride as the absorption material have good absorption performance for infrared light, which improves the absorption rate of the sensor chip to infrared light, thereby improving the test accuracy of the sensor chip.
[0020] In some embodiments, the thickness of the absorption layer 4 is 0.05 to 1.5 μm; if the absorption layer 4 is too thick, it will cause more heat dissipation, and if it is too thin, it will affect the absorption of infrared light, thereby affecting the performance of the sensor chip. Therefore, using an absorption layer structure with an appropriate thickness can have a good absorption effect on infrared light while avoiding the degradation of test performance caused by excessive heat dissipation, thereby improving the test sensitivity of the sensor chip.
[0021] The sensor chip of the present application can also be used to make a temperature sensor.
[0022] In some embodiments, the absorption layer 4 includes a first absorption layer 43 and a second absorption layer 42; the first absorption layer 43 is at least partially covered on the support layer 2, and the second absorption layer 42 is connected to the first absorption layer 43, and along the thickness direction Z of the chip, the second absorption layer 42 is away from the support layer 2 relative to the first absorption layer 43.
[0023] In some embodiments, the material of the first absorption layer 43 is selected from aluminum, and the material of the second absorption layer 42 is selected from titanium or silicon nitride; or, the first absorption layer 43 is selected from silicon nitride, and the second absorption layer 42 is selected from titanium. Aluminum is used as the first absorption layer 43, i.e., the reflective layer, and titanium or silicon nitride is used as the second absorption layer 42, i.e., the infrared absorption layer. The infrared light passes through the second absorption layer 42, part of the infrared light is absorbed by the second absorption layer 42, and part of the infrared light is reflected by the first absorption layer 43 and returns to the second absorption layer 42, and is further absorbed by the second absorption layer 42, thereby improving the absorption rate of the absorption layer 4 to infrared light. Alternatively, silicon nitride is used as the first absorption layer 43, and titanium is used as the second absorption layer 42. The infrared light passes through titanium with good transmission performance, i.e., the second absorption layer 42, part of the infrared light is absorbed by the second absorption layer 42, and part of the infrared light is further absorbed by silicon nitride, i.e., the first absorption layer 43, thereby improving the absorption performance of the absorption layer 4 to infrared light.
[0024] In some embodiments, the absorption layer 4 includes a third absorption layer; the first absorption layer 43 is connected to the support layer 2; the second absorption layer 42 is connected to the first absorption layer 43; the third absorption layer 41 is connected to the second absorption layer 42, along the thickness direction Z of the chip, the second absorption layer 42 is far away from the support layer 2 relative to the first absorption layer 43, and the third absorption layer 41 is far away from the first absorption layer 43 relative to the second absorption layer 42, specifically as follows Figure 3 shown.
[0025] In some embodiments, the material of the first absorption layer 43 is selected from aluminum; the material of the second absorption layer 42 is selected from silicon nitride; and the material of the third absorption layer 41 is selected from titanium. Aluminum is used as the first absorption layer 43, i.e., the reflective layer, and titanium is used as the third absorption layer 41, i.e., the transmission layer. The infrared light passes through the third absorption layer 41, is absorbed by the second absorption layer 42, and is reflected by the first absorption layer 43, and returns to the second absorption layer 42 and the third absorption layer 41, and is further absorbed by silicon nitride and titanium, thereby improving the absorption rate of the absorption layer 4 to the infrared light.
[0026] Further, in some embodiments, the thickness of the first absorption layer 43 is 50-500 nm, preferably 100-500 nm; the thickness of the second absorption layer 42 is 50-300 nm, preferably 100-300 nm; the thickness of the third absorption layer 41 is 50-500 nm, preferably 100-500 nm. The absorption layer with a specific thickness has a good absorption effect on infrared light and can stably exist on the support layer.
[0027] In some embodiments, the sensor chip further comprises a thermocouple element 3; the thermocouple element 3 is connected to the support layer 2, and along the thickness direction Z of the chip, the thermocouple element 3 and the absorption layer 4 are on the same side of the support layer 2; wherein the inner end 8 of the thermocouple element 3 is close to the absorption layer 4, the outer end 9 of the thermocouple element 3 is connected to the metal pad, and there is a distance between the thermocouple element 3 and the absorption layer 4; specifically, Figure 1 and Figure 2 shown.
[0028] It should be noted that the "inner end" mentioned here is the part of the thermocouple element 3 close to the absorption layer 4, that is, the hot end, and the part of the thermocouple element 3 away from the absorption layer 4 is the "outer end", that is, the cold end, and the pads are connected using metal wires.
[0029] In some embodiments, the thermocouple element 3 includes a first thermocouple layer 31, an isolation layer 33 and a second thermocouple layer 32; the first thermocouple layer 31 is connected to the support layer 2; the isolation layer 33 is at least partially covered on the first thermocouple layer 31; the second thermocouple layer 32 is at least partially covered on the isolation layer 33; along the thickness direction Z of the chip, the isolation layer 33 is away from the support layer 2 relative to the first thermocouple layer 31, and the second thermocouple layer 32 is away from the first thermocouple layer 31 relative to the isolation layer 33; specifically, Figure 1 shown.
[0030] In some embodiments, the material of the first thermocouple layer 31 is selected from P-type polysilicon or platinum, preferably P-type polysilicon; the material of the second electric double layer 32 is selected from N-type polysilicon or aluminum, preferably aluminum; and the material of the isolation layer 33 is selected from silicon nitride. Using materials with large differences in Seebeck coefficients as the first electric double layer 31 and the second electric double layer 32 in the thermocouple element 3, the induced voltage is generated due to the temperature difference, further improving the test accuracy of the sensor chip; and the isolation layer 33 has a good stress matching effect with the support layer 2, avoiding the occurrence of more residual stress, so that it has good temperature shock resistance, can withstand rapid temperature changes, and thus has a longer service life.
[0031] In some embodiments, the number of thermocouple elements 3 is 50 to 80 groups, and the cold end 9 of the thermocouple element 3 is connected with a metal wire 7, which sequentially connects the first electric couple layer 31 of a thermocouple element 3 with the second electric couple layer 32 of another adjacent thermocouple element 3, and the first electric couple layer 31 of the thermocouple element 3 connected first and the second electric couple layer 32 of the thermocouple element 3 connected last are respectively connected to the positive and negative electrodes of the metal pad, and the metal wire 7 is preferably an aluminum wire, wherein the thermocouple element 3 is arranged in a circular, square or rectangular manner around the absorption layer 4, preferably in a circular manner. The thermocouple element 3 is arranged in a circular form around the absorption layer 4, which can reduce the stress concentration of the thermocouple element 3 and avoid the chip from breaking, and at the same time has a good effect of withstanding rapid temperature changes. In addition, multiple groups of thermocouple elements 3 are distributed around the absorption layer 4, which can concentrate more heat, transmit signals through the thermocouple element 3, and thus improve the test accuracy of the sensor chip.
[0032] In some embodiments, the shape of the cavity 5 in the sensor chip can be circular, square, rectangular, etc.
[0033] The present application also provides a method for manufacturing a sensor chip, which comprises the following steps:
[0034] Step 1: depositing the support layer 2 on the surface of the wafer substrate 1 by a deposition process;
[0035] Step 2: depositing the first thermocouple layer 31 on a portion of the surface of the support layer 2 by a deposition process, depositing the isolation layer 33 on at least a portion of the surface of the first thermocouple layer 31 by a deposition process, and depositing the second thermocouple layer 32 on at least a portion of the surface of the isolation layer 33 by a deposition process;
[0036] Step 3, depositing an absorption layer 4 on a portion of the surface of the support layer 2 by a deposition process, with a spacing between the absorption layer 4 and the first thermocouple layer 31, the isolation layer 33 and the second thermocouple layer 32, wherein the material of the absorption layer 4 is selected from titanium, or the material of the absorption layer 4 includes at least two of aluminum, titanium and silicon nitride;
[0037] Step 4: etching a hole on the surface of at least one of the support layer 2 and the absorption layer 4, and etching a cavity 5 in the wafer substrate 1 through the hole.
[0038] The present application uses a deposition process to deposit an absorption layer on part of the surface of the support layer. Different deposition processes can be selected according to the different materials of the absorption layer, and different etching processes can be used according to the requirements of the shape of the absorption layer to obtain the required shape of the absorption layer, thereby improving the accuracy of the absorption layer deposition and thereby improving the sensor chip's absorption rate of infrared light.
[0039] Specifically, in some embodiments of step one, after cleaning the wafer substrate 1, the wafer substrate 1 is selected from single crystal silicon, and a support layer 2 is deposited on the surface of the wafer substrate 1; wherein the support layer 2 is selected from silicon dioxide, and has a thickness of 100 to 300 nm, preferably 200 to 300 nm.
[0040] Specifically, in some embodiments of step 2, a first thermocouple layer 31 is deposited on a portion of the surface of the support layer 2, and dry etching is performed after the pattern is defined by photolithography. The material of the first thermocouple layer 31 is selected from P-type polysilicon, N-type polysilicon, platinum or aluminum, preferably P-type polysilicon or N-type polysilicon, and the thickness is 400-800nm, preferably 500-800nm; an isolation layer 33 is deposited on a portion of the surface of the first thermocouple layer 31, and dry etching is performed after the pattern is defined by photolithography. The material of the isolation layer 33 is selected from silicon nitride, and the thickness is 100-300nm, preferably 200-300nm; a second thermocouple layer 32 is deposited on at least a portion of the surface of the isolation layer 33, and patterning is defined using photolithography, dry etching technology or stripping technology. The material of the second thermocouple layer 32 is selected from P-type polysilicon, N-type polysilicon, platinum or aluminum, preferably platinum or aluminum, and the thickness is 200-500nm, preferably 300-500nm. The present application uses photolithography and dry etching technology to etch the first electric double layer 31 to obtain the first electric double layer 31 of the desired shape with high precision; similarly, an isolation layer 33 is deposited on a portion of the surface of the first electric double layer 31, and then the photolithography and dry etching technology are used to perform graphic definition to obtain the isolation layer 33 of the desired shape, and then the second electric double layer 32 is deposited on a portion of the surface of the isolation layer 33, and the photolithography, dry etching technology or stripping technology is used to perform graphic definition to obtain the second electric double layer 32 of the desired shape and high precision.
[0041] It should be noted that in the present application, the material of the first electric double layer 31 is different from the material of the second electric double layer 32 .
[0042] Specifically, in some embodiments of step three, an absorption layer 4 is deposited on a portion of the surface of the support layer 2, and there is a gap between the absorption layer 4 and the first electric double layer 31, the isolation layer 33 and the second electric double layer 32, wherein the material of the absorption layer 4 is selected from titanium, or the material of the absorption layer 4 includes at least two of aluminum, titanium and silicon nitride; since titanium, or at least two of aluminum, titanium and silicon nitride as absorption materials have good absorption performance for infrared light, the absorption rate of the absorption layer to infrared light is improved.
[0043] It should be noted that after the absorption layer 4 is deposited, a subsequent process selected from photolithography, dry etching technology or stripping technology is used to perform graphic definition to obtain a desired shape.
[0044] In some embodiments, the material of the absorption layer 4 in the sensor chip of the present application is patterned and defined by stripping technology or photolithography or dry etching technology, and then deposited on the support layer 2. The absorption layer 4 of the present application can be selected from a single layer material, such as titanium; or a composite layer, such as a titanium and aluminum composite absorption layer, a titanium and silicon nitride composite absorption layer, an aluminum and silicon nitride composite absorption layer, and a titanium, silicon nitride and aluminum composite absorption layer.
[0045] In some embodiments, the method for manufacturing the absorption layer 4 includes: depositing a first absorption layer 43 on at least a portion of the surface of the support layer 2, and using photolithography, dry etching technology or stripping technology to perform graphical definition to obtain a desired shape, and then depositing a second absorption layer 42 on at least a portion of the surface of the first absorption layer 43, and using photolithography, dry etching technology or stripping technology to perform graphical definition to obtain a desired shape.
[0046] In some embodiments, the method for manufacturing the absorption layer 4 includes: depositing a first absorption layer 43 on at least a portion of the surface of the support layer 2, and using photolithography, dry etching technology or stripping technology to perform graphical definition to obtain a desired shape, then depositing a second absorption layer 42 on at least a portion of the surface of the first absorption layer 43, and using photolithography, dry etching technology or stripping technology to perform graphical definition to obtain a desired shape, and finally depositing a third absorption layer 41 on at least a portion of the surface of the second absorption layer 42, and using photolithography, dry etching technology or stripping technology to perform graphical definition to obtain a desired shape.
[0047] In one embodiment of the present application, the absorption layer 4 is more preferably a composite absorption layer of titanium, silicon nitride and aluminum, that is, aluminum is used as the first absorption layer 43 , silicon nitride is used as the second absorption layer 42 , and titanium is used as the third absorption layer 41 .
[0048] Specifically, in some embodiments of step four, CeF2 gas is used to dry-etch holes 6 on the surface of at least one of the support layer 2 and the absorption layer 4, and the holes are evenly distributed in the support layer 2 and the absorption layer 4. The etched absorption layer 4 finally stops on the surface of the wafer substrate 1, and passes through the hole 6 and uses CeF2 gas to etch a cavity 5 in the wafer substrate 1; the cavity depth is 100 to 150 μm; it has a good thermal insulation effect, can avoid the loss of heat in the absorption layer, and thus improve the accuracy of the sensor.
[0049] In some embodiments, the deposition process of the support layer 2, the first electric double layer 31, the second electric double layer 32, the isolation layer 33 and the absorption layer 4 in the present application is selected from one of LPCVD, APCVD, PECVD and PVD.
[0050] It should be noted that the P-type polysilicon and P-type polysilicon used in the present application are prepared by ion implantation process.
[0051] The above implementation modes are only used to illustrate the present application and are not intended to limit the technical solutions described in the present application. The understanding of the present application should be based on the technical personnel in the relevant technical field. Although the present application has been described in detail in this specification with reference to the above implementation modes, ordinary technical personnel in the field should understand that the technical personnel in the relevant technical field can still modify or make equivalent substitutions to the present application, and all technical solutions and improvements thereof that do not depart from the spirit and scope of the present application should be included in the scope of the claims of the present application.
Claims
1. A sensor chip, characterized in that: The sensor chip comprises a wafer substrate, a support layer and an absorption layer for absorbing infrared light; the support layer is connected to the wafer substrate, and the absorption layer is at least partially covered on the support layer; the sensor chip has a cavity, and the cavity is at least partially located in the wafer substrate, and along the thickness direction of the chip, the absorption layer and the cavity are located on both sides of the support layer; The material of the absorption layer is selected from titanium, or The material of the absorption layer includes at least two of aluminum, titanium and silicon nitride.
2. The sensor chip according to claim 1, characterized in that: The absorption layer includes a first absorption layer and a second absorption layer; the first absorption layer is at least partially covered on the support layer, the second absorption layer is connected to the first absorption layer, and along the thickness direction of the chip, the second absorption layer is away from the support layer relative to the first absorption layer.
3. The sensor chip according to claim 2, characterized in that: The material of the first absorption layer is selected from aluminum, and the material of the second absorption layer is selected from titanium or silicon nitride; or, the material of the first absorption layer is selected from silicon nitride, and the material of the second absorption layer is selected from titanium.
4. The sensor chip according to claim 2, characterized in that: The absorption layer includes a third absorption layer; the third absorption layer is connected to the second absorption layer, and along the thickness direction of the chip, the third absorption layer is farther away from the first absorption layer than the second absorption layer.
5. The sensor chip according to claim 4, characterized in that: The material of the first absorption layer is selected from aluminum; the material of the second absorption layer is selected from silicon nitride; and the material of the third absorption layer is selected from titanium.
6. The sensor chip according to claim 1, characterized in that: The absorption layer has a thickness of 0.05 to 1.5 μm.
7. The sensor chip according to claim 1, characterized in that: The sensor chip further comprises a thermocouple element; the thermocouple element is connected to the support layer, and along the thickness direction of the chip, the thermocouple element and the absorption layer are on the same side of the support layer.
8. The sensor chip according to claim 7, characterized in that: The thermocouple element comprises a first thermocouple layer, an isolation layer and a second thermocouple layer, wherein the first thermocouple layer is connected to the support layer; The isolation layer at least partially covers the first electric couple layer, and the second thermocouple layer at least partially covers the isolation layer; Along the thickness direction of the chip, the isolation layer is farther away from the support layer than the first electric double layer, and the second electric double layer is farther away from the first electric double layer than the isolation layer.
9. The sensor chip according to claim 8, characterized in that: The material of the first thermocouple layer is selected from P-type polysilicon or platinum; the material of the second thermocouple layer is selected from N-type polysilicon or aluminum; and the isolation layer is selected from silicon nitride.
10. A method for manufacturing a sensor chip, characterized in that: The production method comprises the following steps: depositing a support layer on a surface of a wafer substrate; Depositing a first thermocouple layer on a portion of the surface of the support layer, depositing an isolation layer on at least a portion of the surface of the first thermocouple layer, and depositing a second thermocouple layer on at least a portion of the surface of the isolation layer; Depositing an absorption layer on a portion of the surface of the support layer, with a gap between the absorption layer and the first thermocouple layer, the isolation layer and the second thermocouple layer, wherein the material of the absorption layer is selected from titanium, or the material of the absorption layer includes at least two of aluminum, titanium and silicon nitride; A hole is etched in a surface of at least one of the support layer and the absorption layer, and a cavity is etched in the wafer substrate through the hole.