CN102520376B - Cross current type three-axis vector magnetic sensor - Google Patents

Abstract

The invention relates to the field of MEMS magnetic sensors, in particular to a cross current type three-axis vector magnetic sensor. The invention aims to solve the problems of low precision and poor sensitivity of the existing magnetic sensor. A cross-current type three-axis vector magnetic sensor, comprising a GaAs substrate, two RTD-based vertical current Hall devices, and a HEMT-based horizontal current Hall device; it is manufactured by a preparation method comprising the following steps : making substrate; forming two trapezoidal RTD mesa and HEMT mesa; preparing two vertical current Hall devices based on RTD; preparing horizontal current Hall device based on HEMT. The magnetic sensor of the invention has high precision and good sensitivity, and can be widely used in various navigation systems.

Description

Cross current type three-axis vector magnetic sensor

technical field

The invention relates to the field of MEMS magnetic sensors, in particular to a cross current type three-axis vector magnetic sensor.

Background technique

As a passive autonomous navigation method, geomagnetic navigation technology has the characteristics of good concealment, strong anti-interference ability and low cost, especially the emergence of magnetic sensors based on the Hall effect, which has made it develop rapidly. The low accuracy and poor sensitivity of geomagnetic navigation technology have always been only applicable to ordinary navigation systems, and have little contribution to tactical and strategic navigation systems.

The traditional Hall magnetic sensor uses Si material as the Hall semiconductor, and then due to the high electron mobility of GaAs material, the Hall sensor based on GaAs material is also born accordingly, and then with the emergence of high electron mobility HEMT devices, making At present, Hall magnetic sensors based on high electron mobility heterojunctions have become a research hotspot, but their accuracy and sensitivity still cannot meet the requirements of tactical and strategic navigation systems.

Contents of the invention

In order to solve the problems of low precision and poor sensitivity of the existing magnetic sensor, the present invention provides a cross current type three-axis vector magnetic sensor.

The present invention is realized by adopting the following technical solutions: a cross current type three-axis vector magnetic sensor, comprising a GaAs substrate, two vertical current Hall devices based on RTD and a horizontal current Hall device based on HEMT; it is Prepared by a preparation method comprising the following steps:

(1) In an ultra-vacuum environment, the HEMT (High Electron Mobility Transistor) thin film material, self-stop corrosion layer, and RTD (Resonance Tunneling Diode) film material; Obtain substrate;

Table 1

(2), apply a layer of photoresist on the substrate, and use photolithography and etching techniques to form three trapezoidal RTD mesas; to protect two of the trapezoidal RTD mesas, use gas SiCl ₄ /SF ₆ as 3:1 Dry etching technology etches the third trapezoidal RTD mesa to the HEMT thin film material to form the HEMT mesa; thus realizing the monolithic integration of RTD and HEMT, forming the device basis of the cross current;

(3) The preparation of two RTD-based vertical current Hall devices, the following operations are performed on the two trapezoidal RTD mesa:

Step 1: lead the collector of the RTD thin film material to the self-stop corrosion layer through leads, around the junction of the emitter on the upper surface of the trapezoidal RTD table and the self-stop corrosion layer with the leads from the RTD thin film material collector The metal alloy Ni/Au/Ge/Ni/Au mixed in any ratio with an average sputtering thickness of 350nm, and then on the emitter on the upper surface of the trapezoidal RTD mesa and on the self-stop corrosion layer and from the collector of the RTD thin film material The Ni/Au/Ge/Ni/Au metal alloy layers around the connection of the leads are all processed by deposition and lift-off method to form an RTD ohmic contact layer, and then at 460°C and N ₂ : H ₂ ratio of 80:20 Anneal in nitrogen and hydrogen environment for 30s;

Step 2: Coat a layer of photoresist on the substrate, and use photolithography and etching techniques to form the total mesa of the emitter and collector;

Step 3: Inject B ⁺ with a concentration of 10 ¹³ cm ^-3 into the total mesa of the emitter and collector to isolate the total mesa of the emitter and collector from the self-stop corrosion layer;

Step 4: Deposit a layer of Si ₃ N ₄ passivation layer on both sides of the total mesa of the emitter and collector using a plasma deposition platform to form an isolation insulating layer;

Step 5: Preparation of the Hall detection electrode: coat a layer of photoresist on the substrate, use photolithography and etching technology to open a small window on the front and rear surfaces of the trapezoidal RTD mesa structure, and use sputtering technology to sputter a layer Cover the small window with Au/Ge/Ni alloy mixed in any proportion to form RTD ohmic contact area; use wire connection technology to connect RTD ohmic contact area with self-stop corrosion layer, so that RTD external lead pad area is formed on self-stop corrosion layer ;

的金属Au；Step 6: Coat a layer of photoresist on the substrate, use photolithography and etching technology to form RTD air bridge piers on the RTD ohmic contact layer and isolation insulating layer, and use a magnetron sputtering station to sputter on the RTD air bridge piers Shoot a layer with a thickness of

metal Au;

Step 7: Coat a layer of photoresist on the substrate, and use photolithography and etching technology to form an RTD air bridge bridge deck between the trapezoidal RTD mesa and the RTD air bridge piers on the isolation insulating layer; obtain a vertical type based on RTD Current Hall device;

(4) Preparation of a HEMT-based horizontal current Hall device, the following operations are performed on the HEMT table:

的以任意比例混合的金属合金Au/Ge/Ni，在380～420℃温度下合金化60秒；Step 1: Coat a layer of photoresist on the substrate, and use photolithography and etching technology to form two HEMT ohmic contact layers on the two ends of the HEMT table top surface; perform plasma cleaning and deoxidation on the HEMT ohmic contact layer layer; then evaporate a layer of thickness on the HEMT ohmic contact layer

The metal alloy Au/Ge/Ni mixed in any proportion is alloyed at a temperature of 380-420°C for 60 seconds;

Step 2: Coat a layer of photoresist on the HEMT mesa, use photolithography and etching techniques to form an N ⁺ groove between the two HEMT ohmic contact layers, and continue etching to form a gate groove to obtain a double groove structure;

的以任意比例混合的金属合金Ti/Pt/Au，形成肖特基势垒栅；Step 3: Evaporate a layer with a thickness of

A metal alloy Ti/Pt/Au mixed in any ratio to form a Schottky barrier gate;

Step 4: use photolithography and etching technology to etch deep grooves on the HEMT ohmic contact layer at one end of the HEMT mesa, use metal evaporation and wire interconnection technology to connect the Schottky barrier gate to the GaAs substrate through the deep groove through the wire, forming a gate lead pad area on the GaAs substrate;

的Si₃N₄钝化层从而将肖特基势垒栅与欧姆接触层隔离；Step 5: Deposit a layer with a thickness of

Si ₃ N ₄ passivation layer to isolate the Schottky barrier gate from the ohmic contact layer;

Step 6: Fill the deep groove with photoresist, use photolithography and corrosion technology to form the bridge surface of the ohmic contact layer, and evaporate a layer of metal Au with a thickness of 2um on the HEMT ohmic contact layer with the deep groove;

Step 7: Preparation of the Hall detection electrode: Coat a layer of photoresist on the substrate, use photolithography and etching technology to open a small Hall electrode window on the front and back of the HEMT mesa structure, and use sputtering technology to sputter a hole. The layer is covered with a metal alloy Au/Ge/Ni in any proportion to cover the small window to form a HEMT ohmic contact area; the HEMT ohmic contact area is connected to the GaAs substrate using wire connection technology, so that the HEMT external lead pad area is formed on the GaAs substrate ;

的金属Au，再在HEMT空气桥桥面上电镀一层厚度为2～5μm的金属Au；Step 8: Apply a layer of photoresist on the substrate, and use photolithography and etching technology to form two HEMT air bridge piers on one side of the HEMT ohmic contact layer; apply a layer of photoresist on the substrate, use photolithography, The etching technology forms two HEMT air bridge decks between the two HEMT air bridge piers and the HEMT ohmic contact layer, and uses a magnetron sputtering table to sputter a layer with a thickness of

Metal Au, and then electroplate a layer of metal Au with a thickness of 2 to 5 μm on the HEMT air bridge surface;

Step 9: removing the photoresist on the substrate with an etchant, forming a HEMT-based horizontal current Hall device with an air bridge structure; obtaining a cross current type three-axis vector magnetic sensor.

As shown in Figure 14, the principle of the Hall effect is that when one direction of the semiconductor material is excited by a certain current signal, and at the same time there is a magnetic field in the other direction of the material, then in the third direction of the device A voltage signal will be generated. The present invention is based on the Hall effect principle, as shown in Figure 15, when there is a magnetic field in the vertical direction, it will cause the output of the voltage signal on the Hall detection electrode on the Hall device based on the HEMT in the horizontal current direction , when the magnetic field changes, the voltage signal also changes accordingly, so as to characterize the magnetic field signal; as shown in Figure 16, when there is a magnetic field in the horizontal X and Y directions, it will cause a vertical current direction based on RTD Hall The output of the voltage signal on the Hall detection electrode on the device, when the magnetic field changes, the voltage signal also changes accordingly, so as to realize the magnetic field detection in three dimensions.

The magnetic sensor of the invention has high precision and good sensitivity, solves the problems of low precision and poor sensitivity of the existing magnetic sensor, and can be widely used in various navigation systems.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a schematic structural view of the substrate in the first step of the present invention.

Fig. 3 is a structural schematic diagram of step 1 in the third step of the present invention.

Fig. 4 is a structural schematic diagram of step 2 in the third step of the present invention.

Fig. 5 is a schematic structural view of step 4 in the third step of the present invention (Fig. 5 is a side view of Fig. 4).

Fig. 6 is a structural schematic diagram of step 5 in the third step of the present invention.

Fig. 7 is a structural schematic diagram of step 7 in the third step of the present invention.

Fig. 8 is a schematic structural diagram of step 1 in the fourth step of the present invention.

Fig. 9 is a schematic structural diagram of step 2 in the fourth step of the present invention.

Fig. 10 is a structural schematic diagram of step 3 in the fourth step of the present invention.

Fig. 11 is a structural schematic diagram of steps 4 and 6 in the fourth step of the present invention.

Fig. 12 is a structural schematic diagram of step 5 in the fourth step of the present invention.

Fig. 13 is a schematic structural view of step 7 in the fourth step of the present invention (Fig. 13 is a side view of Fig. 12).

Fig. 14 is a schematic structural diagram of step 8 in the fourth step of the present invention.

Fig. 15 is a schematic diagram of the principle of the Hall effect.

Fig. 16 is a working principle diagram of the RTD-based vertical current Hall device of the present invention.

Fig. 17 is a working principle diagram of the HEMT-based horizontal current Hall device of the present invention.

In the figure: 1-GaAs substrate; 2-trapezoidal RTD mesa; 3-RTD ohmic contact layer; 4-total mesa of emitter and collector; 5-isolation insulating layer; 6-RTD ohmic contact area; 7-RTD air bridge Bridge pier; 8-RTD air bridge deck; 9-HEMT mesa; 10-HEMT ohmic contact layer; 11-double groove structure; 12-Schottky barrier grid; 13-HEMT ohmic contact area; 14-HEMT external leads Pad area; 15-RTD external lead pad area; 16-HEMT air bridge pier; 17-HEMT air bridge deck; 18-Si ₃ N ₄ passivation layer; 19-Horizontal current Hall device based on HEMT; 20-RTD-based vertical current Hall device; 21-deep groove; 22-gate lead pad area; 23-lead.

Detailed ways

Cross current type three-axis vector magnetic sensor, comprising GaAs substrate 1, two vertical current Hall devices 20 based on RTD and a horizontal current Hall device 19 based on HEMT; it is a preparation method comprising the following steps Made:

(1) In an ultra-vacuum environment, the HEMT film material, the self-stop corrosion layer, and the RTD film material of the parameters shown in Table 1 are sequentially grown on the GaAs substrate 1 by molecular beam epitaxy; the substrate is obtained;

Table 1

(2), apply a layer of photoresist on the substrate, and use photolithography and etching technology to form three trapezoidal RTD mesa 2; wherein two trapezoidal RTD mesa 2 are protected, using gas SiCl ₄ /SF ₆ is 3: The dry etching technology of 1 etches the third trapezoidal RTD mesa 2 to the HEMT film material to form the HEMT mesa 9; thereby realizing the monolithic integration of RTD and HEMT, forming the device basis of the cross current;

(3) Preparation of two RTD-based vertical current Hall devices, the following operations are performed on the two trapezoidal RTD mesa 2:

Step 1: lead the collector of the RTD thin film material to the self-stop corrosion layer through leads, around the junction of the emitter on the upper surface of the trapezoidal RTD table and the self-stop corrosion layer with the leads from the RTD thin film material collector The metal alloy Ni/Au/Ge/Ni/Au mixed in any ratio with an average sputtering thickness of 350nm, and then on the emitter on the upper surface of the trapezoidal RTD mesa and on the self-stop corrosion layer and from the collector of the RTD thin film material The Ni/Au/Ge/Ni/Au metal alloy layers around the connection of the leads are all processed by deposition and lift-off method to form the RTD ohmic contact layer 3, and then at 460°C and N ₂ : H ₂ ratio of 80:20 Annealed in a nitrogen-hydrogen environment for 30s;

Step 2: Coating a layer of photoresist on the substrate, using photolithography and etching techniques to form the total mesa 4 of the emitter and collector;

Step 3: injecting B ⁺ with a concentration of 10 ¹³ cm ^-3 into the total mesa 4 of the emitter and collector to isolate the total mesa 4 of the emitter and collector from the self-stop corrosion layer;

Step 4: Deposit a layer of Si ₃ N ₄ passivation layer on both sides of the total mesa 4 of the emitter and collector using a plasma deposition platform to form an isolation insulating layer 5;

Step 5: Preparation of the Hall detection electrode: coat a layer of photoresist on the substrate, use photolithography and etching technology to open a small window on the front and rear surfaces of the trapezoidal RTD mesa structure, and use sputtering technology to sputter a layer Cover the small window with Au/Ge/Ni alloy mixed in any proportion to form RTD ohmic contact area 6; use wire connection technology to connect RTD ohmic contact area 6 to the self-stop corrosion layer, so that RTD external lead welding is formed on the self-stop corrosion layer panel 15;

的金属Au；Step 6: Apply a layer of photoresist on the substrate, use photolithography and etching technology to form RTD air bridge piers 7 on the RTD ohmic contact layer 3 and isolation insulating layer 5, and use a magnetron sputtering station to form RTD air bridge piers 7 on the RTD air A layer of sputtering thickness on the bridge pier 7 is

metal Au;

Step 7: apply a layer of photoresist on the substrate, and use photolithography and etching technology to form the RTD air bridge bridge deck 8 between the RTD air bridge piers 7 on the RTD ohmic contact layer 3 and the isolation insulating layer 5; RTD vertical current Hall device;

(4) Preparation of a HEMT-based horizontal current Hall device, the following operations are performed on the HEMT table 9:

的以任意比例混合的金属合金Au/Ge/Ni，在380～420℃温度下合金化60秒；Step 1: apply a layer of photoresist on the substrate, and use photolithography and etching techniques to form two HEMT ohmic contact layers 10 on the upper surface of the HEMT table 9; perform plasma cleaning on the HEMT ohmic contact layer 10 and remove the oxide layer; then evaporate a layer of thickness on the HEMT ohmic contact layer 10

The metal alloy Au/Ge/Ni mixed in any proportion is alloyed at a temperature of 380-420°C for 60 seconds;

Step 2: Coat a layer of photoresist on the HEMT mesa 9, use photolithography and etching techniques to form an N ⁺ groove located between the two HEMT ohmic contact layers 10, and continue etching to form a gate groove, thereby obtaining a double groove Structure 11;

的以任意比例混合的金属合金Ti/Pt/Au，形成肖特基势垒栅12；Step 3: Evaporate a layer with a thickness of

A metal alloy Ti/Pt/Au mixed in any ratio to form a Schottky barrier gate 12;

Step 4: Etch a deep groove 21 on the HEMT ohmic contact layer 10 at one end of the HEMT mesa 9 using photolithography and etching technology, and use metal evaporation and wire interconnection technology to pass the Schottky barrier gate 12 through the lead 23 through the deep groove 21 Connect to the GaAs substrate 1, so that the gate lead pad area 22 is formed on the GaAs substrate 1;

的Si₃N₄钝化层18从而将肖特基势垒栅12与欧姆接触层10隔离；Step 5: Deposit a layer with a thickness of

Si ₃ N ₄ passivation layer 18 to isolate the Schottky barrier gate 12 from the ohmic contact layer 10;

Step 6: fill the deep groove 21 with photoresist, use photolithography and corrosion technology to form the bridge surface of the ohmic contact layer, evaporate a layer of metal Au with a thickness of 2um on the HEMT ohmic contact layer 10 engraved with the deep groove 21;

Step 7: Preparation of the Hall detection electrode: coat a layer of photoresist on the substrate, use photolithography and etching technology to open a small Hall electrode window on the front and back of the HEMT table 9 structure, and use sputtering technology to sputter A layer of metal alloy Au/Ge/Ni mixed in any ratio covers the small window to form a HEMT ohmic contact region 13; use wire connection technology to connect the HEMT ohmic contact region 13 to the GaAs substrate 1, so that the HEMT is formed on the GaAs substrate 1 External lead pad area 14;

的金属Au，再在HEMT空气桥桥面17上电镀一层厚度为2～5μm的金属Au；Step 8: apply a layer of photoresist on the substrate, and form two HEMT air bridge piers 16 on one side of the HEMT ohmic contact layer 10 using photolithography and etching techniques; Engraving and etching technology forms two HEMT air bridge decks 17 between the two HEMT air bridge piers 16 and the HEMT ohmic contact layer 10, and uses a magnetron sputtering table to sputter a layer of thickness on the HEMT air bridge deck 17 for

metal Au, and then electroplate a layer of metal Au with a thickness of 2-5 μm on the HEMT air bridge deck 17;

Step 9: removing the photoresist on the substrate with an etchant, forming a HEMT-based horizontal current Hall device with an air bridge structure; obtaining a cross current type three-axis vector magnetic sensor.

Claims (1)

1. A method for preparing a cross current type three-axis vector magnetic sensor, the vector magnetic sensor includes a GaAs substrate (1), two RTD-based vertical current Hall devices (20) and a HEMT-based horizontal type A current Hall device (19); it is characterized in that: the preparation method of the vector magnetic sensor comprises the following steps: (1) In an ultra-vacuum environment, the HEMT thin film material, self-stop corrosion layer, and RTD thin film material with the parameters shown in Table 1 are sequentially grown on the GaAs substrate (1) by molecular beam epitaxy technology; the substrate is obtained; Table 1

(2) Apply a layer of photoresist on the substrate, and use photolithography and etching technology to form three trapezoidal RTD mesas (2); protect two of the trapezoidal RTD mesas (2), using gas SiCl ₄ /SF ₆ is 3:1 dry etching technology to etch the third trapezoidal RTD mesa (2) to the HEMT film material to form the HEMT mesa (9); thus realizing the monolithic integration of RTD and HEMT to form a cross-shaped current Device basis; (3) Preparation of two RTD-based vertical current Hall devices, the following operations are performed on the two trapezoidal RTD mesa (2): Step 1: Lead the collector of the RTD thin film material to the self-stop corrosion layer through a lead wire, and connect the lead wires that are drawn from the RTD thin film material collector on the emitter on the upper surface of the trapezoidal RTD table and on the self-stop corrosion layer The metal alloy Ni/Au/Ge/Ni/Au mixed in any ratio with a thickness of 350nm is sputtered around, and then on the emitter on the upper surface of the trapezoidal RTD mesa and on the self-stopping corrosion layer and from the collector of the RTD thin film material The Ni/Au/Ge/Ni/Au metal alloy layer around the connection of the lead is treated by deposition and lift-off method to form the RTD ohmic contact layer (3), and then at 460°C and N ₂ :H ₂ is 80 : Annealing 30s in the nitrogen-hydrogen environment of 20; Step 2: Coating a layer of photoresist on the substrate, using photolithography and etching techniques to form the total mesa of the emitter and collector (4); Step 3: Inject B ⁺ with a concentration of 10 ¹³ cm ^-3 into the emitter and collector total mesa (4) to isolate the emitter and collector total mesa (4) from the self-stop corrosion layer; Step 4: Deposit a Si ₃ N ₄ passivation layer on both sides of the total mesa (4) of the emitter and collector using a plasma deposition platform to form an isolation insulating layer (5); Step 5: Preparation of the Hall detection electrode: coat a layer of photoresist on the substrate, use photolithography and etching technology to open a small window on the front and rear surfaces of the trapezoidal RTD mesa structure, and use sputtering technology to sputter a layer The small window is covered with Au/Ge/Ni alloy mixed in any proportion to form the RTD ohmic contact area (6); the RTD ohmic contact area (6) is connected to the self-stop corrosion layer by wire connection technology, so that the self-stop corrosion layer is formed RTD external lead pad area (15); Step 6: Coat a layer of photoresist on the substrate, use photolithography and etching techniques to form RTD air bridge piers (7) on the RTD ohmic contact layer (3) and isolation insulating layer (5), and use magnetron sputtering The injection platform sputters a layer of thickness on the RTD air bridge pier (7) metal Au; Step 7: Apply a layer of photoresist on the substrate, and use photolithography and etching techniques to form an RTD air bridge between the RTD ohmic contact layer (3) and the RTD air bridge pier (7) on the isolation insulating layer (5) Bridge deck (8); obtain the vertical current Hall device based on RTD; (4) Preparation of HEMT-based horizontal current Hall device, perform the following operations on the HEMT table (9): Step 1: Coating a layer of photoresist on the substrate, using photolithography and etching techniques to form two HEMT ohmic contact layers (10) on the upper surface of the HEMT table (9); for the HEMT ohmic contact layer (10) Carry out plasma cleaning and de-oxidation layer; then evaporate a layer thickness on the HEMT ohmic contact layer (10)

The metal alloy Au/Ge/Ni mixed in any proportion is alloyed at a temperature of 380-420°C for 60 seconds; Step 2: Coat a layer of photoresist on the HEMT mesa (9), use photolithography and etching techniques to form an N ⁺ groove located between the two HEMT ohmic contact layers (10), and continue etching to form a gate groove, thereby Get the double-groove structure (11); Step 3: Evaporate a layer with a thickness of

A metal alloy Ti/Pt/Au mixed in any ratio to form a Schottky barrier (12); Step 4: Etch a deep groove (21) on the HEMT ohmic contact layer (10) at one end of the HEMT mesa (9) using photolithography and etching technology, and use metal evaporation and wire interconnection technology to place the Schottky barrier gate (12 ) is connected to the GaAs substrate (1) through the lead (23) through the deep groove (21), so that the gate lead pad area (22) is formed on the GaAs substrate (1); Step 5: Deposit a layer with a thickness of

Si ₃ N ₄ passivation layer (18) to isolate the Schottky barrier (12) from the ohmic contact layer (10); Step 6: Fill the deep groove (21) with photoresist, use photolithography and etching technology to form the bridge surface of the ohmic contact layer, and evaporate a layer thickness on the HEMT ohmic contact layer (10) with the deep groove (21) 2um metal Au; Step 7: Preparation of the Hall detection electrode: Coat a layer of photoresist on the substrate, use photolithography and etching technology to open a small Hall electrode window on the front and back of the HEMT table (9) structure, use sputtering technology Sputter a layer of metal alloy Au/Ge/Ni mixed in any proportion to cover the small window to form a HEMT ohmic contact area (13); use wire connection technology to connect the HEMT ohmic contact area (13) to the GaAs substrate (1), forming a HEMT external lead pad area (14) on the GaAs substrate (1); Step 8: Apply a layer of photoresist on the substrate, and use photolithography and etching technology to form two HEMT air bridge piers (16) on one side of the HEMT ohmic contact layer (10); apply a layer of photoresist on the substrate Glue, using photolithography and etching technology to form two HEMT air bridge decks (17) between the two HEMT air bridge piers (16) and the HEMT ohmic contact layer (10), on the HEMT air bridge deck (17) Sputter a layer with a thickness of

metal Au, and then electroplate a layer of metal Au with a thickness of 2-5 μm on the HEMT air bridge deck (17); Step 9: removing the photoresist on the substrate with an etchant, forming a HEMT-based horizontal current Hall device with an air bridge structure; obtaining a cross current type three-axis vector magnetic sensor.

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