Pressure sensing device based on field effect transistor and manufacturing method thereof

Abstract

The invention discloses a pressure sensing device based on a field effect transistor and a manufacturing method thereof, the pressure sensing device based on the field effect transistor comprises an SOI substrate, a silicon germanium epitaxial layer is arranged above the SOI substrate, an SGOI substrate is formed through oxidation concentration, a grid electrode is formed on the SGOI substrate through photoetching, two sides of the grid electrode are respectively provided with a metal source end and a metal drain end, and the metal source end and the metal drain end are connected with the SOI substrate. Contact electrodes are respectively arranged on the metal source end and the metal drain end and are connected with leads, so that the metal source end and the metal drain end are respectively used as a source electrode and a drain electrode, and a groove is etched on the back surface of the SGOI substrate and is used as a pressure sensing point. According to the pressure sensing device based on the field effect transistor and the manufacturing method of the pressure sensing device, under the pressure state, the silicon-germanium back face is subjected to tensile stress, the carrier mobility changes, so that the magnitude of source-drain output current changes, the silicon-germanium field effect transistor with the reverse initial strain can delay stress release, and therefore the reliability of the pressure sensing device is improved. Quantitative calibration of the pressure value is achieved, and meanwhile the measurement range is enlarged.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to a pressure sensor device based on a (oxidized concentrated silicon germanium) field effect transistor and a manufacturing method of a pressure sensor device based on a (oxidized concentrated silicon germanium) field effect transistor. Background Art

[0002] With the advancement of science and technology, pressure sensors play an important role in the fields of automobiles, manufacturing, aerospace, etc. The development of microelectronic devices has also prompted the transformation of pressure sensors to miniaturization. In the 1960s, MEMS-based sensors were born. They were made by processing materials with the help of microelectronics and micromechanical technology, but MEMS pressure sensors are large in size, which is not conducive to improving system integration.

[0003] Today's pressure sensors are mainly divided into piezoresistive sensors, capacitive sensors, inductive sensors, piezoelectric sensors, strain sensors, etc. according to their working modes.

[0004] The principle of capacitive sensors is that pressure causes the electrode plate to displace, thereby changing the capacitance. Although the size of capacitive sensors has been successfully reduced, their input and output are nonlinear, which makes signal processing difficult and has low sensitivity. Inductive sensors are based on the principle of electromagnetic induction and are easily affected by the electromagnetic field in the environment when working, making them difficult to use in complex environments. Field effect transistor pressure sensors utilize the characteristics of transistors to adjust the conductive path by controlling the gate electric field, thereby achieving pressure measurement. This makes field effect transistor pressure sensors have higher sensitivity and faster response speed.

[0005] Field effect transistor pressure sensor is a kind of strain type pressure sensor, which uses pressure to generate strain to change carrier mobility, thereby changing output current and threshold voltage. It has the advantages of small size, high sensitivity, and compatibility with integrated circuit manufacturing process. However, when the working pressure exceeds a certain range, excessive strain will cause stress release, and the pressure sensor device cannot work normally.

[0006] Therefore, further improvements are made to the above problems. Summary of the invention

[0007] The main purpose of the present invention is to provide a pressure sensor device based on a field effect transistor and a manufacturing method thereof. The field effect transistor of oxidized concentrated silicon germanium is used as a pressure sensor. By changing the pressure, the output voltage and current are changed to sense the pressure value. This is a feasible solution to break through the performance bottleneck of traditional field effect pressure sensors. Under pressure, the back of silicon germanium is subjected to tensile stress, and the change in carrier mobility causes the source-drain output current to change. The silicon germanium field effect transistor with reverse initial strain can delay the release of stress, realize quantitative calibration of pressure value, and increase the measurement range at the same time.

[0008] To achieve the above objectives, the present invention provides a pressure sensor device based on a field effect transistor, comprising an SOI substrate, a silicon germanium epitaxial layer is arranged on the SOI substrate, and an SGOI substrate is formed by oxidation and concentration, a gate is photoetched on the SGOI substrate, a metal source terminal and a metal drain terminal are respectively arranged on both sides of the gate, contact electrodes are respectively arranged on the metal source terminal and the metal drain terminal and connected to leads, so as to serve as a source and a drain respectively, and a groove is etched on the back side of the SGOI substrate as a pressure sensing point.

[0009] As a further preferred technical solution of the above technical solution, the SOI substrate includes a silicon substrate, a buried oxide layer and a top silicon layer, the buried oxide layer is located between the silicon substrate and the top silicon layer, the buried oxide layer has a thickness of 200 nanometers to 800 nanometers, and the top silicon layer is low-concentration p-type doped with a thickness of 10 nanometers to 30 nanometers.

[0010] As a further preferred technical solution of the above technical solution, the silicon germanium epitaxial layer with low germanium concentration is grown on the side of the top silicon layer away from the buried oxide layer, the germanium fraction of the silicon germanium epitaxial layer is 0.1 to 0.25, and the thickness is 30 nanometers to 80 nanometers.

[0011] As a further preferred technical solution of the above technical solution, for the formation of the SGOI substrate, oxidation concentration technology is used to perform oxidation at high temperature, and the germanium in the silicon germanium epitaxial layer diffuses downward, so that silicon is selectively oxidized, and the top silicon layer and the silicon germanium epitaxial layer with low germanium concentration thereon are transformed into silicon germanium with high germanium concentration, and compressive strain is retained, thereby forming the SGOI substrate as a whole.

[0012] As a further preferred technical solution of the above technical solution, the gate includes a gate oxide layer and a gate contact electrode, and the gate contact electrode is located on a side of the gate oxide layer away from the SGOI substrate.

[0013] As a further preferred technical solution of the above technical solution, the groove on the back side of the SGOI substrate corresponds to the gate on the front side, and the range of the groove is larger than the range of the gate.

[0014] To achieve the above objectives, the present invention also provides a method for manufacturing a pressure sensor device based on a field effect transistor, comprising the following steps:

[0015] Step S1: providing an SOI substrate, epitaxially growing a silicon germanium epitaxial layer with a low germanium content on the surface of the SOI substrate, and selectively oxidizing at high temperature to form a SGOI substrate with compressive strain;

[0016] Step S2: depositing a gate oxide layer on the surface of the SGOI substrate, and preparing a gate contact electrode on the gate oxide layer, and using it as a gate after photolithography;

[0017] Step S3: depositing metal nickel on one side of the SGOI substrate with the gate, annealing at high temperature to form a NiSiGe / p-SiGe Schottky junction as a metal source terminal and a metal drain terminal, and removing the metal nickel, depositing metal on the metal source terminal and the metal drain terminal to form an ohmic contact and make electrode leads, thereby serving as a source electrode and a drain electrode respectively;

[0018] Step S4: etching a groove on the back side of the SGOI substrate to expose the buried oxide layer as a contact point for applying external pressure.

[0019] The beneficial effects of the present invention are:

[0020] 1) High sensitivity: The pressure acts directly on the surface of the silicon germanium sensor, and the response speed is fast;

[0021] 2) Large measurement range: The silicon germanium field effect transistor prepared by oxidation concentration has an initial compressive strain, which can delay the energy accumulation and release of tensile strain and increase the working range of the device;

[0022] 3) Small size: CMOS size has been reduced to tens of nanometers and is still shrinking, which is much smaller than the size of MEMS sensors;

[0023] 4) It is compatible with integrated circuit manufacturing process technology and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 (a) is a schematic diagram of the structure of a P-type SOI substrate, and (b) is a schematic diagram of growing a silicon germanium epitaxial layer on a SOI substrate;

[0025] Figure 2 Schematic diagram of the structure of the SGOI substrate formed after oxidation concentration;

[0026] Figure 3 is a schematic diagram of the formation of a gate;

[0027] Figure 4 is a schematic diagram of the metal source / drain terminal area;

[0028] Figure 5Schematic diagram of etching the pressure groove area on the back side of the SGOI substrate;

[0029] Figure 6 This is the wiring diagram for the pressure sensor device.

[0030] The reference numerals include: silicon substrate 10 , buried oxide layer 11 , top silicon layer 12 , silicon germanium epitaxial layer 13 , high germanium concentration silicon germanium 20 , gate oxide layer 30 , gate contact electrode 31 , metal source / drain terminal 40 , and groove 50 . DETAILED DESCRIPTION

[0031] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0032] In the preferred embodiments of the present invention, those skilled in the art should note that the grounding and the like involved in the present invention may be regarded as prior art.

[0033] Preferred embodiments.

[0034] like Figure 1-6 As shown, the present invention discloses a pressure sensor device based on a field effect transistor, including an SOI substrate, a silicon germanium epitaxial layer 13 is arranged on the SOI substrate, and an SGOI substrate is formed by oxidation and concentration, and a gate is photoetched on the SGOI substrate, and a metal source terminal and a metal drain terminal (i.e., Figure 4-5 A metal source / drain terminal 40 is provided on the metal source terminal and the metal drain terminal, respectively, and contact electrodes are provided and connected to leads, so as to serve as a source and a drain, respectively. A groove 50 is etched on the back side of the SGOI substrate as a pressure sensing point (the groove is trapezoidal, and the back side etching method is reactive plasma etching or solution etching).

[0035] Specifically, the SOI substrate includes a silicon substrate 10, a buried oxide layer 11 and a top silicon layer 12, the buried oxide layer 11 is located between the silicon substrate 10 and the top silicon layer 13, the buried oxide layer 11 has a thickness of 200 nanometers to 800 nanometers, and the top silicon layer 12 is low-concentration p-type doped with a thickness of 10 nanometers to 30 nanometers.

[0036] More specifically, the silicon germanium epitaxial layer 13 with low germanium concentration is grown on the side of the top silicon layer 12 away from the buried oxide layer 11 . The germanium fraction of the silicon germanium epitaxial layer 13 is 0.1 to 0.25 and the thickness is 30 nanometers to 80 nanometers.

[0037] Furthermore, for the formation of the SGOI substrate, oxidation concentration technology is used to perform oxidation at high temperature (oxidation temperature is 900 degrees Celsius to 1100 degrees Celsius), and the germanium in the silicon germanium epitaxial layer 13 diffuses downward, so that silicon is selectively oxidized, and the top silicon layer 12 and the silicon germanium epitaxial layer 13 with low germanium concentration thereon are transformed into high germanium concentration silicon germanium 20, and compressive strain is retained, thereby forming the SGOI substrate as a whole.

[0038] Furthermore, the gate includes a gate oxide layer 30 and a gate contact electrode 31, and the gate contact electrode 31 is located on a side of the gate oxide layer 30 away from the SGOI substrate. The gate oxide layer 30 is made of aluminum oxide or hafnium oxide with a thickness of 2 nanometers to 10 nanometers; the gate contact electrode 31 is made of metal such as tungsten, aluminum, nickel, etc., with a thickness of tens to hundreds of nanometers.

[0039] Preferably, the groove 50 on the back side of the SGOI substrate corresponds to the gate on the front side, and the range of the groove 50 is larger than that of the gate.

[0040] Preferably, the metal of the metal source / drain terminal is nickel, and the Schottky junction of the source / drain terminal is NiSiGe / p-SiGe.

[0041] The electrode lead materials of the source and drain are aluminum, nickel or copper.

[0042] The present invention also discloses a method for manufacturing a pressure sensor device based on a field effect transistor, comprising the following steps:

[0043] Step S1: providing an SOI substrate, epitaxially growing a silicon germanium epitaxial layer 13 with a low germanium content on the surface of the SOI substrate, and selectively oxidizing at high temperature to form a SGOI substrate with compressive strain;

[0044] Step S2: depositing a gate oxide layer 30 on the surface of the SGOI substrate, and preparing a gate contact electrode 31 on the gate oxide layer 30, and using it as a gate after photolithography;

[0045] Step S3: depositing metal nickel on one side of the SGOI substrate with the gate, annealing at high temperature to form a NiSiGe / p-SiGe Schottky junction as a metal source terminal and a metal drain terminal, and removing the metal nickel, depositing metal on the metal source terminal and the metal drain terminal to form an ohmic contact and make electrode leads, thereby serving as a source electrode and a drain electrode respectively;

[0046] Step S4: etching a groove 50 on the back side of the SGOI substrate to expose the buried oxide layer 11 as a contact point for applying external pressure.

[0047] In step S1, epitaxial silicon germanium is prepared by molecular beam epitaxy or chemical vapor deposition;

[0048] In step S3, the thickness of the deposited metal nickel is 20 nanometers to 40 nanometers, and the annealing method for forming the source and drain terminals (i.e., the metal source / drain terminals 40) includes thermal annealing, microwave annealing, or laser annealing, and different annealing temperatures form different Schottky junction barrier heights. Ohmic contact metal deposition is performed on the SGOI substrate of the metal source / drain terminals 40, and the electrode lead material of the metal source / drain terminals is aluminum, nickel, or copper, and the deposition method can be magnetron sputtering or thermal oxidation.

[0049] In steps S2 and S3, the preparation method used for preparing the metal such as the electrode is electron beam evaporation, magnetron sputtering or chemical vapor deposition.

[0050] like Figure 6 As shown in the figure, when pressure is applied to the groove etched on the back, tensile stress deformation will occur on the surface. One end of the test electrode is connected to a negative voltage (i.e., an external voltage) and the other end is grounded. By measuring the change in the threshold voltage (i.e., the test voltage) of the gate contact electrode, the strain is calculated to infer the pressure value.

[0051] For the present invention, when pressure is applied to the silicon germanium channel (i.e., the groove), the crystal structure produces a strain opposite to the initial strain, the carrier mobility in the channel changes, the output current changes, and the pressure value is sensed. The sensor of the present invention has the advantages of small size, high sensitivity, fast response speed, large pressure measurement range, and compatibility with integrated circuit process technology, and has broad application prospects.

[0052] It is worth mentioning that the technical features such as grounding involved in the patent application of this invention should be regarded as the prior art. The specific structure, working principle and possible control method and spatial layout method of these technical features can be selected by conventional methods in the field, and should not be regarded as the inventive point of this patent. This patent will not be further elaborated.

[0053] For those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pressure sensor device based on a field effect transistor, characterized in that: The invention comprises an SOI substrate, a silicon germanium epitaxial layer is arranged on the SOI substrate, and an SGOI substrate is formed by oxidation and concentration. A gate is photoetched on the SGOI substrate, a metal source terminal and a metal drain terminal are arranged on both sides of the gate, contact electrodes are arranged on the metal source terminal and the metal drain terminal and connected with leads, so as to serve as a source and a drain respectively, and a groove is etched on the back side of the SGOI substrate as a pressure sensing point.

2. A field effect transistor-based pressure sensor device according to claim 1, characterized in that: The SOI substrate comprises a silicon substrate, a buried oxide layer and a top silicon layer. The buried oxide layer is located between the silicon substrate and the top silicon layer. The buried oxide layer has a thickness of 200 nanometers to 800 nanometers. The top silicon layer is low-concentration p-type doped and has a thickness of 10 nanometers to 30 nanometers.

3. A field effect transistor-based pressure sensor device according to claim 2, characterized in that: The silicon germanium epitaxial layer with low germanium concentration is grown on the side of the top silicon layer away from the buried oxide layer. The germanium fraction of the silicon germanium epitaxial layer is 0.1 to 0.25 and the thickness is 30 nanometers to 80 nanometers.

4. A field effect transistor-based pressure sensor device according to claim 3, characterized in that: For the formation of the SGOI substrate, oxidation is performed at high temperature using oxidation concentration technology, and the germanium in the silicon germanium epitaxial layer diffuses downward, so that silicon is selectively oxidized, and the top silicon layer and the silicon germanium epitaxial layer with low germanium concentration thereon are transformed into silicon germanium with high germanium concentration, and compressive strain is retained, thereby forming the SGOI substrate as a whole.

5. A field effect transistor-based pressure sensor device according to claim 4, characterized in that: The gate includes a gate oxide layer and a gate contact electrode, and the gate contact electrode is located on a side of the gate oxide layer away from the SGOI substrate.

6. The field effect transistor-based pressure sensor device according to claim 5, characterized in that: The groove on the back side of the SGOI substrate corresponds to the gate on the front side, and the range of the groove is larger than that of the gate.

7. A method for manufacturing a pressure sensor device based on a field effect transistor, applied to a pressure sensor device based on a field effect transistor according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1: providing an SOI substrate, epitaxially growing a silicon germanium epitaxial layer with a low germanium content on the surface of the SOI substrate, and selectively oxidizing at high temperature to form a SGOI substrate with compressive strain; Step S2: depositing a gate oxide layer on the surface of the SGOI substrate, and preparing a gate contact electrode on the gate oxide layer, and using it as a gate after photolithography; Step S3: depositing metal nickel on one side of the SGOI substrate with the gate, annealing at high temperature to form a NiSiGe / p-SiGe Schottky junction as a metal source terminal and a metal drain terminal, and removing the metal nickel, depositing metal on the metal source terminal and the metal drain terminal to form an ohmic contact and make electrode leads, thereby serving as a source electrode and a drain electrode respectively; Step S4: etching a groove on the back side of the SGOI substrate to expose the buried oxide layer as a contact point for applying external pressure.

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