Preparation method of six-dimensional force sensor

Abstract

The invention belongs to the technical field of sensors, and discloses a preparation method of a six-dimensional force sensor, which comprises the following steps: S11, providing a substrate; s12, forming an insulating layer on the upper surface of the substrate; s13, forming a strain layer above the insulating layer; s14, forming the strain layer into a resistor strip with a required shape based on a photoetching and etching semiconductor preparation process; s15, thinning the lower surface of the substrate to a specified thickness; s21, cleaning the surface of the elastic beam; s22, printing glass slurry on the surface of the elastic beam by using a silk-screen printing technology; and S23, putting a strain gauge on the glass slurry, enabling the strain gauge to be embedded into the glass slurry in a semi-molten state, and enabling the strain gauge to be completely attached to the elastic beam during stress relief annealing. The six-dimensional force sensor prepared by the invention can be suitable for a high-temperature environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and particularly relates to a preparation method of a six-axis force sensor. Background Art

[0002] A six-axis force sensor is a high-precision sensor that can simultaneously measure forces and torques in a three-dimensional space. Its core principle is based on the conversion of the deformation of an elastic body and the electrical signal of a strain gauge, and the decoupling algorithm is combined to achieve the separate measurement of multi-dimensional forces / torques. The structural composition of a six-axis force sensor mainly includes elastic beams, strain gauges, and signal acquisition circuits. With high-precision and high-sensitivity mechanical measurements, it has a wide range of applications in industrial robots, medical treatment, aerospace, automotive testing, sports scientific research, and other fields.

[0003] In a six-axis force sensor, a strain gauge is a sensing element used to measure the force applied to an object and is usually pasted or fixed on the sensor structure; when the stress gauge is subjected to a force, strain occurs inside it, resulting in a change in the resistance value; by measuring the change in the resistance value, the magnitude of the force can be indirectly measured. Therefore, the preparation and fixed connection of the strain gauge are crucial to the performance of the six-axis force sensor. Currently, the widely used strain gauge is a metal foil strain gauge, which has good temperature stability and high linearity, but has the following deficiencies in preparation and fixed connection:

[0004] (1) The thickness of the strain gauge directly affects its resistance value. Currently, for metal foils prepared by methods such as rolling or electrolysis, the uniformity of the prepared metal thickness is poor, making it difficult to achieve uniform strain gauge thickness.

[0005] (2) The base material of the metal foil strain gauge generally uses an organic material with good insulation performance. In a long-term harsh environment, its material properties degrade, resulting in a decline in device performance.

[0006] (3) When the strain gauge and the elastic beam are fixedly connected, they are connected together by a fixing adhesive. In a high-temperature environment, the fixing adhesive will melt, causing the position of the strain gauge to move, affecting the device accuracy.

[0007] In summary, the current device has poor high-temperature stability and preparation process uniformity. It is necessary to optimize the preparation process of the strain gauge and the fixed connection process between the strain gauge and the elastic beam to prepare a six-axis force sensor with excellent temperature stability under high-temperature conditions. Summary of the Invention

[0008] In order to prepare a six-axis force sensor applicable to a high-temperature environment, the present invention provides a preparation method of a six-axis force sensor.

[0009] A preparation method of a six-axis force sensor provided by the present invention includes:

[0010] S1 Prepare a strain gauge, including the steps:

[0011] S11: Provide a substrate, where the substrate material is silicon, silicon-based compound, silicon wafer, SOI, polysilicon on SiO2 / Si, glass wafer or sapphire wafer;

[0012] S12: Form an insulating layer on the upper surface of the substrate, where the insulating layer material is one or more composite layers of silicon oxide and its composites, silicon nitride, or aluminum oxide;

[0013] S13: Form a strain layer above the insulating layer, where the strain layer is an alloy material composed of one or more of gold, platinum, copper, silver, nickel, aluminum, and chromium, or a metal oxide or a semiconductor material;

[0014] S14: Based on the semiconductor lithography and etching preparation process, form a resistor bar with the desired shape on the strain layer;

[0015] S15: Thinning the lower surface of the substrate to a specified thickness;

[0016] S2 Connect the strain gauge to the elastic beam, including the steps of:

[0017] S21: Clean the surface of the elastic beam;

[0018] S22: Use screen printing technology to print glass paste on the surface of the elastic beam;

[0019] S23: Place the strain gauge on the glass paste, embed the strain gauge in the semi-molten glass paste, and while performing stress-relieving annealing, make the strain gauge fully adhere to the elastic beam.

[0020] Further, after thinning the lower surface of the substrate to a specified thickness in step S15, the preparation method further includes:

[0021] S16: Perform a resistance test on the strain gauge, and use laser cutting technology or mechanical thinning technology to engrave the resistance film of the strain gauge to adjust the resistance value of the strain gauge.

[0022] Further, in step S12, forming an insulating layer on the upper surface of the substrate, where the insulating layer material is one or more composite layers of silicon oxide and its composites, silicon nitride, or aluminum oxide; specifically:

[0023] Form silicon oxide by thermally oxidizing the substrate silicon wafer, or

[0024] Form a silicon nitride layer or an aluminum oxide layer on the upper surface of the substrate by deposition or sputtering methods;

[0025] The thickness of the insulating layer is 0.2 to 3 um.

[0026] Preferably, the thickness of the insulating layer is 0.5 um to 2 um.

[0027] Further, a strain layer is formed above the insulating layer in step S13; specifically:

[0028] The strain layer is formed above the insulating layer by deposition or sputtering.

[0029] Further, the thickness of the strain layer is 0.2 um to 3 um.

[0030] Further, in step S15, the lower surface of the substrate is thinned to a specified thickness; specifically:

[0031] The lower surface of the substrate is thinned to a specified thickness by thinning, etching or polishing, and the specified thickness is 5 um to 50 um.

[0032] Further, in step S21, the surface of the elastic beam is cleaned; specifically:

[0033] The surface of the elastic beam is cleaned using an inorganic solution, and the inorganic solution is an acidic, alkaline or acid-base composite solution.

[0034] Further, the surface of the elastic beam is cleaned using a mixed solution of concentrated sulfuric acid and hydrogen peroxide.

[0035] Further, in step S22, the glass paste is printed onto the surface of the elastic beam using screen printing technology; specifically:

[0036] The glass paste is coated on the mesh holes of the screen and pressed, so that the glass paste is evenly applied to the surface of the elastic beam through the mesh holes, and the printing thickness is 30 - 300 um.

[0037] Further, in step S23, the heating temperature of the glass paste is 300 °C to 600 °C.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] (1) The substrate of the present invention is a hard material and can withstand high temperatures; by using the strain gauge preparation process provided by the present invention, the obtained strain layer has high quality, good thickness uniformity, good adhesion to the substrate, and this process method is easy for large-scale preparation.

[0040] (2) The present invention uses a laser cutting process or a mechanical thinning process to engrave the resistance film of the strain gauge, thereby adjusting the resistance value of the strain gauge; the laser cutting process or the mechanical thinning process can precisely control the resistance value of the strain gauge to make the strain gauge reach the required resistance value range.

[0041] (3) The present invention realizes the tight fitting connection between the elastic beam and the strain gauge through the process of coating glass paste, solving the problems of the glue pasting process in the traditional fixing method, such as poor thermal stability, the temperature range that the colloid can withstand is usually lower than 200 °C, and the performance of the sensor will deteriorate sharply outside this temperature range, even causing the failure of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0043] Figure 1 It is a flowchart of a preparation method for a six - dimensional force sensor provided by an embodiment of the present invention;

[0044] Figure 2 It is a schematic structural diagram of a strain gauge provided by an embodiment of the present invention;

[0045] Figure 3 It is a schematic structural diagram of a six - dimensional force sensor provided by an embodiment of the present invention.

[0046] The meanings of the reference numerals in the drawings are as follows:

[0047] 1 - substrate; 2 - insulating layer; 3 - strain layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0049] Please refer to Figure 1 , a preparation method for a six - dimensional force sensor provided by an embodiment of the present invention includes two major steps:

[0050] S1 Prepare a strain gauge;

[0051] S2 Connect the strain gauge to the elastic beam.

[0052] Among them, the structural layers of the strain gauge are as shown in Figure 2 , and the structure of the six - dimensional force sensor is as shown in Figure 3 .

[0053] S1 Prepare a strain gauge, including the following steps:

[0054] S11: Provide a substrate, the substrate material being silicon or a silicon-based compound or others (such as a silicon wafer, SOI, polysilicon on SiO2 / Si, a glass wafer or a sapphire wafer).

[0055] S12: Form an insulating layer on the upper surface of the substrate, the insulating layer material being one or more composite layers of silicon oxide and its composites, silicon nitride, aluminum oxide, etc.

[0056] In this embodiment, silicon oxide is formed by thermally oxidizing the substrate silicon wafer, and the thickness of the silicon oxide is 0.2 to 3 um. Preferably, the thickness of the silicon oxide is 0.5 um to 2 um.

[0057] In other embodiments, a silicon nitride layer or an aluminum oxide layer may also be formed on the upper surface of the substrate by deposition or sputtering methods.

[0058] S13: Form a strain layer above the insulating layer, the strain layer being an alloy material composed of one or more of gold, platinum, copper, silver, nickel, aluminum, chromium, etc., or a metal oxide or a semiconductor material.

[0059] Alloy materials such as beryllium bronze alloy, iron-chromium-aluminum alloy, platinum-iridium alloy, etc. Metal oxide materials such as ruthenium oxide (RuO2), iridium oxide (IrO2), etc. Semiconductor materials such as single crystal silicon, tantalum nitride, etc.

[0060] Specifically, the strain layer is formed above the insulating layer by deposition or sputtering or other suitable methods.

[0061] In this embodiment, a platinum electrode is formed on the insulating layer by sputtering, and preferably the thickness of the platinum electrode is 0.2 um to 3 um.

[0062] S14: Based on the semiconductor manufacturing processes of photolithography and etching, form a resistance bar of the desired shape on the strain layer.

[0063] This step is based on the semiconductor manufacturing processes of photolithography and etching in the prior art and will not be elaborated in detail here.

[0064] S15: Thin the lower surface of the substrate to a specified thickness.

[0065] The lower surface of the substrate can be thinned to the specified thickness by thinning, etching or polishing methods. Preferably, the thickness of the thinned substrate is 5 um to 50 um.

[0066] S16: Perform a resistance test on the strain gauge.

[0067] In this embodiment, a laser cutting process is used to engrave the resistance film of the strain gauge to adjust the resistance value of the strain gauge. In other embodiments, a mechanical thinning process may also be used to engrave the resistance film of the strain gauge to adjust the resistance value of the strain gauge. It is a preferred step to adjust the resistance value of the strain gauge by using a laser cutting process or a mechanical thinning process to achieve the required resistance value.

[0068] S2 Connect the strain gauge to the elastic beam, including the following steps:

[0069] S21: Clean the surface of the elastic beam; specifically, clean the surface of the elastic beam with an inorganic solution, and the inorganic solution is an acidic, alkaline or acid-base composite solution.

[0070] In this embodiment, a mixed solution of concentrated sulfuric acid and hydrogen peroxide is used to clean the surface of the elastic beam to remove impurities such as oxides, organic substances, dirt and particulate debris on the surface of the elastic beam, clean the surface of the elastic beam and improve its adhesiveness.

[0071] S22: Use screen printing technology to print glass paste onto the surface of the elastic beam.

[0072] Specifically, coat the glass paste on the mesh holes of the screen and press the glass paste so that the glass paste is evenly applied to the surface of the elastic beam through the mesh holes. Preferably, the printing thickness is 30 - 300 um.

[0073] S23: Place the strain gauge on the glass paste, embed the strain gauge into the semi-molten glass paste, and at the same time of stress relief annealing, make the strain gauge completely adhere to the elastic beam.

[0074] Preferably, the heating temperature of the glass paste is 300 °C to 600 °C.

[0075] The above has introduced in detail a preparation method of a six-axis force sensor disclosed in an embodiment of the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A preparation method of a six - dimensional force sensor, characterized in that: including S1 fabricate a strain gauge, including the steps of: S11: Provide a substrate, the substrate material being silicon, silicon-based compound, silicon wafer, SOI, polysilicon on SiO2 / Si, glass sheet or sapphire sheet; S12: Form an insulating layer on the upper surface of the substrate, the insulating layer material being one or more composite layers of silicon oxide and its composites, silicon nitride, or aluminum oxide; S13: Form a strain layer above the insulating layer, the strain layer being an alloy material composed of one or more of gold, platinum, copper, silver, nickel, aluminum, chromium, or a metal oxide or semiconductor material; S14: Based on the semiconductor manufacturing processes of photolithography and etching, form a resistance strip of the desired shape on the strain layer; S15: Thin the lower surface of the substrate to a specified thickness; S2 Connect the strain gauge to the elastic beam, including the steps of: S21: Clean the surface of the elastic beam; S22: Use screen printing technology to print glass paste onto the surface of the elastic beam; S23: Place the strain gauge on the glass paste, embed the strain gauge into the semi-molten glass paste, and while performing stress relief annealing, make the strain gauge tightly adhere to the elastic beam.

2. The preparation method of a six - dimensional force sensor according to claim 1, characterized in that, After step S15: Thin the lower surface of the substrate to a specified thickness, the fabrication method further includes: S16: Perform a resistance test on the strain gauge, and use a laser cutting process or a mechanical thinning process to engrave the resistance film of the strain gauge to adjust the resistance value of the strain gauge.

3. The preparation method of a six-axis force sensor according to claim 1, characterized in that, In step S12: Form an insulating layer on the upper surface of the substrate, the insulating layer material being one or more composite layers of silicon oxide and its composites, silicon nitride, or aluminum oxide; specifically: Form silicon oxide by thermally oxidizing the substrate silicon wafer, or Form a silicon nitride layer or an aluminum oxide layer on the upper surface of the substrate by deposition or sputtering methods; The thickness of the insulating layer is 0.2 to 3 um.

4. The preparation method of a six-axis force sensor according to claim 3, characterized in that The thickness of the insulating layer is 0.5 um to 2 um.

5. The preparation method of a six-axis force sensor according to claim 1, characterized in that, In step S13: Form a strain layer above the insulating layer; specifically: Form a strain layer above the insulating layer by deposition or sputtering methods.

6. The preparation method of a six-axis force sensor according to claim 5, characterized in that, The thickness of the strain layer is 0.2 um to 3 um.

7. The manufacturing method of a six-axis force sensor according to claim 1, characterized in that, In step S15: Thin the lower surface of the substrate to a specified thickness; specifically: Thin the lower surface of the substrate to a specified thickness by thinning, etching, or polishing methods, the specified thickness being 5 um to 50 um.

8. A method for preparing a six-axis force sensor according to claim 1, characterized in that In step S21: Clean the surface of the elastic beam; specifically: Clean the surface of the elastic beam using an inorganic solution, the inorganic solution being an acidic, basic, or acid-base composite solution.

9. The preparation method of a six-axis force sensor according to claim 1, characterized in that, In step S22: Use screen printing technology to print glass paste onto the surface of the elastic beam; specifically: Coat glass paste on the mesh holes of the screen, and press the glass paste to make the glass paste evenly spread onto the surface of the elastic beam through the mesh holes, and the printing thickness is 30 - 300 um.

10. The preparation method of a six - dimensional force sensor according to claim 1, characterized in that, In step S23, the heating temperature of the glass paste is 300 °C to 600 °C.

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