CN101718801B - Micro-accelerometer based on high electron mobility transistor (HEMT) - Google Patents

Abstract

The invention relates to the field of micro-accelerometers, in particular to a micro-accelerometer based on high electron mobility transistor HEMT. It adapts to the needs of high-sensitivity micro-accelerometers in the application field of micro-accelerometers, and realizes the application of high electron mobility transistor HEMT force-electricity conversion mechanism on micro-accelerometers. The micro-accelerometers are manufactured by the following steps: 1. Apply molecular Beam epitaxy technology grows thin films with the material layer structure shown in Table 1 on the GaAs substrate; 2. Apply MEMS device processing technology to process high electron mobility transistor HEMT on the film; 3. Apply MEMS device processing technology to process micro Accelerometer structure. Effective use of the force-to-electricity conversion mechanism of the high electron mobility transistor HEMT realizes the application of the high electron mobility transistor HEMT in the micro-accelerometer, with high sensitivity and good linearity, which can fully meet the actual needs of the micro-accelerometer application field.

Description

Microaccelerometer Based on High Electron Mobility Transistor HEMT

technical field

The invention relates to the field of micro-accelerometers, in particular to a micro-accelerometer based on high electron mobility transistor HEMT.

Background technique

Most of the existing micro-accelerometers are silicon piezoresistive accelerometers, which are realized based on the piezoresistive effect of silicon piezoresistive devices, and use the linear response of silicon piezoresistive devices to external pressure to realize detection, because of their simple structure, mature technology, and wide operating frequency band And many other advantages, it has become one of the research hotspots in the field of micro-inertial devices. However, due to the limitation of the piezoresistive coefficient of silicon piezoresistive devices, it is difficult to further improve the response sensitivity; in addition, the resistivity change of silicon piezoresistive devices is greatly affected by temperature, and rapidly decreases with the increase of temperature. Application of silicon piezoresistive devices in high-sensitivity sensors.

Therefore, in order to meet the urgent need for high-sensitivity micro-accelerometers in the application field of micro-accelerometers, in recent years, scientists from various countries have begun to apply field-effect transistors to the research of micro-mechanical sensing structures. The feasibility of applying transistors to micro-accelerometers has verified the high sensitivity characteristics of micro-accelerometers using field-effect transistors. According to relevant reports at home and abroad, the current research directions of scientists from various countries are mostly focused on metal-semiconductor field-effect transistors (Metal-Semiconductor Field-Effect Transistor, MESFET), metal-oxide layer-semiconductor-field-effect transistors ( Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET). There is no relevant research on the application of high electron mobility transistors in micro accelerometers.

The high electron mobility transistor (High Electronic Mobility Transistor, referred to as HEMT) was developed in the early 1980s and is a new type of transistor based on modulation doping. High electron mobility transistor HEMT adopts a modulated doping structure. The side of the heterojunction narrow-bandgap semiconductor material is not doped, and the side of the wide-bandgap semiconductor material is doped with donor impurities, so that the ionization of the donor impurities generates electrons and positively charged The donor ionizes the impurity centers. In the high electron mobility transistor HEMT, the Fermi level of the n-type doped wide bandgap semiconductor material is close to the conduction band, while the Fermi level of the narrow bandgap semiconductor material is basically in the middle of the forbidden band. The position of the Fermi level of the material is different, and the electrons will be transferred from the side of the wide bandgap material with a relatively high Fermi level to the side of the lower narrow bandgap material, so that the electrons in the channel and the donor ionized impurities are spatially separated. Two-dimensional electron gas (2DEG) is formed in the channel. At the same time, a strong electric field is established by the space charge, and under the action of the strong electric field, the energy band near the heterojunction interface is bent. Under the action of an external electric field, the energy band bending increases, so that a narrow inversion layer potential well can be formed, and a quantum well can be formed in the channel. Since the width of the quantum well is comparable to the wavelength of the De Broglie wave of the electron, the energy is quantized in the z direction perpendicular to the heterojunction interface, and the movement of the 2DEG in the z direction loses the degree of freedom, only in the X and Y directions parallel to the interface. can move freely. 2DEG has many attractive features, and its electron mobility μ is much higher than that of bulk materials. By growing an undoped isolation layer between the doped layer and the channel, the 2DEG is further spatially separated from the donor ionized impurity center, which reduces the impact of ionized impurity scattering and further improves the mobility. At low temperature, the impact of ionized impurity scattering is reduced, and the electron transport properties of 2DEG are more superior.

Compared with ordinary field effect transistors, the channel transmission of HEMTs utilizes the quantum size effect. Since the electrons are confined in the one-dimensional direction by using the band edge energy difference of the heterojunction, the energy of the electrons moving in the longitudinal direction is quantized, and a high concentration two-dimensional electron gas (2DEG) is formed. The movement of 2DEG in the lateral direction in the channel is not restricted, and the channel electrons and donor ions are spatially separated from each other, so the channel electrons are hardly affected by the scattering of impurity ions during lateral transport, so they have high mobility. However, the channel conductance of HEMT strongly depends on the concentration of 2DEG in the channel. When the material in the channel is subjected to stress, the energy band structure of the semiconductor material changes accordingly, which will lead to a change in the confinement effect and affect the concentration of 2DEG in the channel. If the nanometer effect is used to realize electromechanical conversion, the detection sensitivity of the microsensor can be greatly improved.

Contents of the invention

In order to meet the needs of high-sensitivity micro-accelerometers in the application field of micro-accelerometers, and to realize the application of the force-to-electricity conversion mechanism of high-electron-mobility transistor HEMTs in micro-accelerometers, the present invention provides a micro-accelerometer based on high-electron mobility transistor HEMTs. Accelerometer.

The present invention is realized by adopting the following technical scheme: the micro accelerometer based on the high electron mobility transistor HEMT is processed and manufactured by the following steps:

1. Apply molecular beam epitaxy to grow a thin film with the material layer structure shown in Table 1 below on the GaAs substrate:

Table 1

2. Apply micro-electromechanical device processing technology to process high electron mobility transistor HEMT according to the following steps:

a. According to the layout of the micro-accelerometer structure to be processed, remove all the films on the GaAs substrate except the film at the HEMT position where the high electron mobility transistor needs to be processed by etching process; for example: process a micro-accelerometer with a four-sided four-beam structure , you need to reserve four thin films for processing high electron mobility transistor HEMT, and the film retention positions are distributed in a "cross" shape on the GaAs substrate (that is, the thin film retention positions are distributed at the four ends of a "cross" shape above); while processing a single cantilever beam structure, only a single film can be reserved on the GaAs substrate;

b. Processing high electron mobility transistor HEMT at each reserved thin film on the GaAs substrate:

厚的Au/Ge/Ni覆盖层，最后经剥离清洗后，以400℃高温在60s内快速合金，实现晶体管HEMT的源极、漏极金属化，使晶体管HEMT的源极、漏极与所述薄膜的欧姆接触层n-GaAs表面之间形成良好的欧姆接触，其中，高电子迁移率晶体管HEMT的源极为分离设置，即由两分离源极构成，且两分离源极的排列方向与漏极平行；b1. On the surface of the ohmic contact layer n-GaAs of the film, the ohmic contact patterns of the source and drain electrodes of the high electron mobility transistor HEMT are first processed by photolithography, and then the ohmic contact layer n- GaAs surface formation

The thick Au/Ge/Ni covering layer, after peeling and cleaning, is quickly alloyed at a high temperature of 400°C within 60s to realize the metallization of the source and drain of the transistor HEMT, so that the source and drain of the transistor HEMT are connected to the A good ohmic contact is formed between the surfaces of the thin-film ohmic contact layer n-GaAs, wherein the source of the high electron mobility transistor HEMT is separated, that is, it is composed of two separated sources, and the arrangement direction of the two separated sources is the same as that of the drain. parallel;

厚的Ti/Pt/Au覆盖层，以剥离法在栅槽处形成栅极，实现晶体管HEMT的栅极金属化，使晶体管HEMT的栅极与所述薄膜的肖特基接触层n-AlGaAs之间形成良好的肖特基势垒；b2. A groove parallel to the drain and running through the entire film is processed on the film between the source and drain by an etching process, and the groove uses the n-AlGaAs surface of the Schottky contact layer of the film as the bottom surface of the groove Then process the gate groove along the direction of the groove in the middle of the bottom of the groove by photolithography, and detect the saturation current between the source and drain poles in real time during the process of gate groove processing until the saturation current between the source and drain poles reaches the required value, Obtain the required grid groove, and then use the electron beam evaporation process to form on the surface of the groove and in the grid groove

Thick Ti/Pt/Au capping layer, form the gate at the gate groove by lift-off method, realize the gate metallization of the transistor HEMT, make the gate of the transistor HEMT and the Schottky contact layer n-AlGaAs of the film A good Schottky barrier is formed between them;

厚的Si₃N₄钝化层，然后以光刻工艺刻蚀所述Si₃N₄钝化层，使Si₃N₄钝化层区域仅覆盖在源极和漏极之间、以及源极和漏极正对侧的边沿处；b3. Use the PECVD deposition method to deposit at 230°C on the film that has processed the source, drain, and gate of the high electron mobility transistor HEMT

Thick Si ₃ N ₄ passivation layer, and then etch the Si ₃ N ₄ passivation layer by photolithography, so that the Si ₃ N ₄ passivation layer area only covers between the source and drain, and the source and the edge on the side opposite to the drain;

厚的TiAu或TiW双元金属层；②、在TiAu或TiW双元金属层表面涂敷光刻胶，再次应用光刻工艺在两分离源极正上方形成以TiAu或TiW双元金属层为槽底面的桥形凹槽，然后采用电镀工艺在TiAu或TiW双元金属层上电镀2～5μm厚的Au层；③、用有机溶剂溶解TiAu或TiW双元金属层上方的光刻胶，然后腐蚀掉Au层下方TiAu或TiW双元金属层外的所有TiAu或TiW双元金属层，最后用有机溶剂溶解所述薄膜上残余的光刻胶，即得到所述空气桥，完成所述薄膜上的高电子迁移率晶体管HEMT加工；b4. Process the air bridge connecting the two separated sources between the two separated sources: ①. Coat photoresist on the thin film covered with Si ₃ N ₄ passivation layer, and apply photolithography technology on the two separated sources Two pier-shaped grooves with the upper surface of the two separated source electrodes as the bottom surface of the groove are formed directly above, and then the surface of the photoresist and the pier-shaped groove are covered by an electron beam evaporation process or a sputtering process.

Thick TiAu or TiW binary metal layer; ②. Coating photoresist on the surface of TiAu or TiW binary metal layer, and then applying photolithography process to form grooves with TiAu or TiW binary metal layer directly above the two separated sources The bridge-shaped groove on the bottom surface, and then use the electroplating process to electroplate a 2-5 μm thick Au layer on the TiAu or TiW binary metal layer; ③, dissolve the photoresist above the TiAu or TiW binary metal layer with an organic solvent, and then etch Remove all TiAu or TiW binary metal layers outside the TiAu or TiW binary metal layer under the Au layer, and finally dissolve the remaining photoresist on the film with an organic solvent to obtain the air bridge and complete the film on the film. High electron mobility transistor HEMT processing;

3. Apply micro-electromechanical device processing technology to process the micro-accelerometer structure according to the following steps:

The GaAs substrate is etched into a micro-accelerometer structure consisting of a peripheral base, a cantilever beam, and a mass block suspended in the center of the peripheral base through the cantilever beam by using an etching process, and the processing has high electron mobility The thin film of the transistor HEMT is located at the junction of the cantilever beam and the peripheral base.

In addition, the processing of the micro-accelerometer also includes the processing of the lead-out pads corresponding to the high electron mobility transistor HEMT source, drain, and gate respectively, and the specific processing of the corresponding lead-out pads is well known to those skilled in the art , so it is not described in the processing steps of the present invention.

When the micro-accelerometer of the present invention feels the acceleration movement, the mass block will shift, which will cause the cantilever beam to be twisted or bent, which will cause stress changes in the channel of the high electron mobility transistor HEMT arranged at the root of the cantilever beam. The energy band structure of the HEMT will change accordingly, resulting in a change in the confinement of the two-dimensional electron gas 2DEG, affecting the concentration of 2DEG in the channel, and finally reflecting the change in the I-V characteristics of the HEMT (as shown in Figure 7). This change can be converted into a measurable signal, such as output in the form of voltage, current, etc. After calibration, the relationship between the output signal and the measured acceleration can be established to measure the external acceleration. The molecular beam epitaxy technology described in the present invention, the etching technology, the photolithography technology, the PECVD deposition method and the like in the micro-electromechanical device processing technology are all well-known and mature processing technologies.

A series of test experiments as shown below have been carried out respectively for the micro-accelerometer of the present invention and the high electron mobility transistor HEMT provided thereon:

1. Conduct semiconductor parameter testing experiments on the high electron mobility transistor HEMT set on the micro accelerometer: use the semiconductor parameter characteristic analyzer Agilent 4156C to analyze the electrical characteristics of the high electron mobility transistor HEMT, V _GS is -2.3 ~ 0.7V, step by step As long as 0.5V, the output characteristic curve and transfer characteristic curve of high electron mobility transistor HEMT are shown in Fig. 3 and Fig. 4 respectively. The test results show that the high electron mobility transistor HEMT set on the micro accelerometer has good performance, and its threshold voltage is about -2.8V, which meets the design requirements;

2. Conduct static pressure experiments on the micro-accelerometer to verify the changes of the micro-accelerometer's I-V characteristics and transfer characteristics under static pressure conditions. The output characteristic curves and transfer characteristic curves before and after pressurization are shown in Fig. 7 and Fig. 8, respectively.

It can be seen from Figure 7 that the I-V characteristic curve shifts up after pressurization, and the area where the change is more obvious is the saturation region, and the larger the gate voltage is, the more obvious the upward shift of the curve is; it can be seen from Figure 8 that the transfer characteristic after pressurization The slope of the curve becomes larger, and the change trend of the curve is consistent with the change trend of the I-V characteristic curve.

3. Piezoresistive gravity gravity experiment on the micro accelerometer: use the Agilent 4156C semiconductor characteristic analyzer to test the high electron mobility transistor HEMT when the micro accelerometer is parallel to the growth direction of the high electron mobility transistor HEMT (Z direction) and the acceleration is ±1g The comparison chart of the IV characteristic curve, in which, the gate-source voltage is from -2.3 to 0.7V, and the step size is 0.6V, as shown in Figure 5, which shows that the current of the high electron mobility transistor HEMT changes at ±1g; the application of the Polytec microsystem The analyzer measures the real size of the micro-accelerometer micro-cantilever beam-mass structure of the present invention, and the data is brought into ANSYS software to carry out stress simulation analysis where the acceleration in the Z direction is 1g, and the maximum stress of the cantilever beam is estimated, according to the piezoresistive coefficient formula $\mathrm{\π}=\frac{\mathrm{\ΔI}}{\mathrm{I\σ}}=(1.72\±0.33)\×{10}^{-7}{\mathrm{Pa}}^{-1},$ Among them, σ is the stress, I is the current value, and ΔI is the change value of the current.

In addition, after analysis and verification, the relationship between the drain voltage of the high electron mobility transistor HEMT and the piezoresistive coefficient is drawn as shown in Figure 6, which shows that the piezoresistive coefficient of the high electron mobility transistor HEMT is different under different bias voltages, and the change ratio in the saturation region is linear The region is obvious, and the maximum piezoresistive coefficient of GaAs material HEMT is three orders of magnitude higher than that of SI (silicon) material piezoresistor, indicating that high electron mobility transistor HEMT is very beneficial in highly sensitive and adjustable resistance micro/nano machine applications on voltage resistive devices.

In addition, the micro accelerometer of the present invention was connected to the peripheral circuit, and the static pressurization trigger experiment was carried out, and the trigger output recorded by the oscilloscope is shown in Figure 9, which shows that the micro accelerometer has a better response and is relatively stable.

It fully demonstrates that the high electron mobility transistor HEMT arranged on the micro accelerometer of the present invention has obvious electromechanical conversion characteristics.

4. Carry out sensitivity characteristic experiments on the micro-accelerometer: fix the micro-accelerometer on the vibration table of the VR8500 vibration table test system, apply a sinusoidal excitation signal through the vibration table, and test the output signal of the micro-accelerometer as shown in Figures 10 and 11 , Figure 10 is the voltage output signal before filtering, and Figure 11 is the voltage output signal after filtering; and the linear fitting relationship between the micro-accelerometer voltage output and acceleration is obtained, as shown in Figure 12, it can be found that: the micro-accelerometer output The test points all swing near the linear fitting line, showing good linearity, and the sensitivity of the micro accelerometer after fitting is 10.68mV/g. It fully demonstrates that the micro-accelerometer of the present invention can realize high-sensitivity detection.

The present invention effectively utilizes the electromechanical conversion mechanism of the high electron mobility transistor HEMT, and realizes the application of the high electron mobility transistor HEMT on the micro-accelerometer, and the micro-accelerometer of the present invention shows high sensitivity, linear Good accuracy and other characteristics, can fully adapt to the actual needs of the micro-accelerometer application field.

Description of drawings

Fig. 1 is a processing and manufacturing process flow chart of the present invention;

Fig. 2 is the scanning electron micrograph of high electron mobility transistor HEMT on the micro accelerometer of the present invention;

Fig. 3 is the output characteristic curve of high electron mobility transistor HEMT on the micro accelerometer of the present invention;

Fig. 4 is the transfer characteristic curve of high electron mobility transistor HEMT on the micro accelerometer of the present invention;

Fig. 5 is the comparison chart of the I-V characteristic curve when the high electron mobility transistor HEMT on the micro accelerometer of the present invention is when the acceleration in the Z direction is ± 1g;

Fig. 6 is the relationship diagram (grid voltage is-1.7V) of high electron mobility transistor HEMT drain voltage and piezoresistive coefficient on the micro accelerometer of the present invention;

Fig. 7 is the comparison chart of I-V characteristic curve before and after micro-accelerometer pressurization of the present invention;

Fig. 8 is a comparison diagram of transfer characteristic curves before and after pressurization of the micro accelerometer according to the present invention;

Fig. 9 is the trigger output figure that the micro-accelerometer of the present invention carries out static pressure trigger experiment and obtains;

Fig. 10 is the voltage output signal diagram before filtering of the micro accelerometer of the present invention;

Fig. 11 is the voltage output signal diagram after filtering of the micro-accelerometer of the present invention;

Fig. 12 is the linear fitting relationship diagram of micro-accelerometer voltage output and acceleration according to the present invention;

In the figure: 1-GaAs substrate; 2-film; 3-drain; 4-source; 5-groove; 6-gate; 7-Si ₃ N ₄ passivation layer; 8-photoresist; 9 - binary metal layer; 10 - photoresist; 11 - bridge groove; 12 - Au layer; 13 - air bridge; 14 - peripheral base; 15 - cantilever beam; 16 - mass block; 17 - high electron mobility rate transistor HEMT.

Detailed ways

Microaccelerometers based on high electron mobility transistor HEMTs are manufactured using the following steps:

(1) A thin film 2 with the material layer structure shown in Table 1 is grown on the GaAs substrate 1 by molecular beam epitaxy technology: as shown in c in Figure 1

Table 1

(2) Apply the micro-electromechanical device processing technology to process the high electron mobility transistor HEMT according to the following steps:

a. According to the layout of the micro-accelerometer structure to be processed, remove all the films on the GaAs substrate 1 except the film 2 at the position of the high electron mobility transistor HEMT that needs to be processed by etching process; For the accelerometer, it is necessary to reserve four thin films for processing the high electron mobility transistor HEMT, and the thin film retention positions are distributed in a "cross" shape on the GaAs substrate (that is, the thin film retention positions are distributed in four "cross" shaped end), as shown in a in Figure 1; while processing a single cantilever beam structure, only a single film can be reserved on the GaAs substrate;

b. Process the high electron mobility transistor HEMT at each reserved thin film on the GaAs substrate 1:

厚的Au/Ge/Ni覆盖层，最后经剥离清洗后，以400℃高温在60s内快速合金，实现晶体管HEMT的源极4、漏极3金属化，使晶体管HEMT的源极4、漏极3与所述薄膜的欧姆接触层n-GaAs表面之间形成良好的欧姆接触，其中，高电子迁移率晶体管HEMT的源极为分离设置，即由两分离源极4构成，如图1中b4-1所示，且两分离源极4的排列方向与漏极3平行，如图1中b1-2所示，图1中b4-1为b1-2的右视图；b1. On the surface of the ohmic contact layer n-GaAs of the thin film, the ohmic contact pattern of the source electrode 4 and the drain electrode 3 of the high electron mobility transistor HEMT is first processed by a photolithography process, as shown in b1-1 in Fig. 1, Then the electron beam evaporation process is used to form the ohmic contact layer n-GaAs surface

The thick Au/Ge/Ni covering layer, after peeling and cleaning, is quickly alloyed at a high temperature of 400°C within 60s to realize the metallization of the source 4 and drain 3 of the transistor HEMT, so that the source 4 and drain of the transistor HEMT 3 form a good ohmic contact with the n-GaAs surface of the ohmic contact layer of the thin film, wherein the source of the high electron mobility transistor HEMT is separated, that is, it is composed of two separated sources 4, as shown in b4- 1, and the arrangement direction of the two separated source electrodes 4 is parallel to the drain electrode 3, as shown in b1-2 in Figure 1, and b4-1 in Figure 1 is the right view of b1-2;

厚的Ti/Pt/Au覆盖层，以剥离法在栅槽处形成栅极6，实现晶体管HEMT的栅极金属化，如图1中b2-2所示，使晶体管HEMT的栅极与所述薄膜的肖特基接触层n-AlGaAs之间形成良好的肖特基势垒；b2. A groove 5 parallel to the drain electrode and running through the entire film is processed on the thin film between the source electrode 4 and the drain electrode 3 by an etching process, and the groove 5 is formed by the Schottky contact layer n-AlGaAs of the thin film The surface is the bottom of the groove, as shown in b2-1 in Figure 1; then, the gate groove is processed along the direction of the groove 5 in the middle of the bottom of the groove 5 by photolithography, and the gap between the source and drain electrodes is detected in real time during the processing of the gate groove. Saturation current until the saturation current between the source and drain reaches the required value, and the required grid groove is obtained, and then the electron beam evaporation process is used to form on the surface of the groove and in the grid groove

Thick Ti/Pt/Au covering layer, form the gate 6 at the gate groove by the lift-off method, realize the gate metallization of the transistor HEMT, as shown in b2-2 in Figure 1, make the gate of the transistor HEMT and the described A good Schottky barrier is formed between the Schottky contact layer n-AlGaAs of the film;

厚的Si₃N₄钝化层7，如图1中b3-1所示，然后以光刻工艺刻蚀所述Si₃N₄钝化层7，使Si₃N₄钝化层7区域仅覆盖在源极4和漏极3之间、以及源极4和漏极3正对侧的边沿处，如图1中b3-2所示；b3. Use the PECVD deposition method to deposit at 230°C on the thin film that has processed the source 4, drain 3, and gate 6 of the high electron mobility transistor HEMT

thick Si ₃ N ₄ passivation layer ₇ , _{as shown in} b3-1 in Fig. Covering between the source electrode 4 and the drain electrode 3, and at the edge of the side directly opposite the source electrode 4 and the drain electrode 3, as shown in b3-2 in FIG. 1;

厚的TiAu或TiW双元金属层9，如图1中b4-2所示；②、在TiAu或TiW双元金属层9表面涂敷光刻胶10，再次应用光刻工艺在两分离源极正上方形成以TiAu或TiW双元金属层为槽底面的桥形凹槽11，如图1中b4-3所示，然后采用电镀工艺在TiAu或TiW双元金属层9上电镀2～5μm厚的Au层12，如图1中b4-4所示；③、用有机溶剂溶解TiAu或TiW双元金属层9上方的光刻胶10，然后腐蚀掉Au层下方TiAu或TiW双元金属层9外的所有TiAu或TiW双元金属层，最后用有机溶剂溶解所述薄膜上残余的光刻胶8，即得到所述空气桥13，如图1中b4-5所示，完成所述薄膜上的高电子迁移率晶体管HEMT加工；b4. Process the air bridge 13 between the two separated source electrodes 4 to connect the two separated source electrodes: ①. Apply a photoresist 8 on the film covered with the Si ₃ N ₄ passivation layer 7, and apply a photolithography process on the Two pier-shaped grooves are formed directly above the two separated source electrodes 4, with the upper surface of the two separated source electrodes 4 as the bottom surface of the groove, and then the surface of the photoresist and the pier-shaped groove are covered by electron beam evaporation or sputtering.

Thick TiAu or TiW binary metal layer 9, as shown in b4-2 in Figure 1; ②, coating photoresist 10 on the surface of TiAu or TiW binary metal layer 9, and applying photolithography process again to separate the source A bridge-shaped groove 11 with the TiAu or TiW binary metal layer as the bottom surface of the groove is formed directly above, as shown in b4-3 in Figure 1, and then the TiAu or TiW binary metal layer 9 is electroplated with a thickness of 2 to 5 μm by using an electroplating process Au layer 12, as shown in b4-4 in Figure 1; ③, dissolve the photoresist 10 above the TiAu or TiW binary metal layer 9 with an organic solvent, and then etch away the TiAu or TiW binary metal layer 9 below the Au layer All the TiAu or TiW binary metal layers outside, and finally dissolve the remaining photoresist 8 on the film with an organic solvent to obtain the air bridge 13, as shown in b4-5 in Figure 1, and complete the film on the film. HEMT processing of high electron mobility transistors;

(3), apply the micro-electromechanical device processing technology to process the micro-accelerometer structure according to the following steps: as shown in d in Figure 1, the GaAs substrate 1 is etched into a peripheral base 14, a cantilever beam 15, and The micro accelerometer structure is formed by the mass block 16 suspended in the center of the peripheral base 14 by the cantilever beam 15 , and the thin film processed with the high electron mobility transistor HEMT17 is located at the junction of the cantilever beam 15 and the peripheral base 14 .

Claims (1)

1. job operation based on the micro-acceleration gauge of high electron mobility transistor (HEMT) is characterized in that adopting the following steps processing and manufacturing:

(1), use molecular beam epitaxy technique grows material layer structures as shown in table 1 below on GaAs substrate (1) film (2):

Table 1

(2), use the micro electro mechanical device process technology and process high electron mobility transistor (HEMT) as follows:

A, according to the layout of micro-acceleration gauge structure to be processed, remove GaAs substrate (1) with etching technics and go up all films except that required processing high electron mobility transistor (HEMT) position film (2);

B, on GaAs substrate (1), respectively keep the film place and process high electron mobility transistor (HEMT) respectively:

B1, at first adopt photoetching process to process the source electrode (4) of high electron mobility transistor (HEMT) and the Ohmic contact figure of drain electrode (3) on the ohmic contact layer n-GaAs surface of described film, adopt electron beam evaporation process to form then on ohmic contact layer n-GaAs surface

Thick Au/Ge/Ni overlayer, after after peeling off cleaning, with 400 ℃ of high temperature quick alloy in 60s, realize source electrode (4), drain electrode (3) metallization of transistor HEMT, make between the ohmic contact layer n-GaAs surface of source electrode (4), drain electrode (3) and described film of transistor HEMT and form good Ohmic contact, wherein, the source electrode of high electron mobility transistor (HEMT) is provided with for separating, promptly constitute, and the orientation of two separated source (4) is parallel with drain electrode (3) by two separated source (4);

B2, process on the film between (3) at source electrode (4) and drain electrode and drain parallel and run through the groove (5) of whole film, and groove (5) is a groove bottom with the schottky contact layer n-AlGaAs surface of film with etching technics; In the middle of groove (5) bottom land, process the grid groove with photoetching process then along groove (5) direction, and in grid groove process, detection resources is leaked the saturation current of two interpolars in real time, the saturation current that leaks two interpolars until the source reaches required value, obtain required grid groove, adopt electron beam evaporation process in groove surfaces, grid groove, to form subsequently

Thick Ti/Pt/Au overlayer forms grid (6) to peel off method at grid groove place, realize the gate metalized of transistor HEMT, the good Schottky barrier of formation between the grid that makes transistor HEMT and the schottky contact layer n-AlGaAs of described film;

B3, with the PECVD sedimentation on the film that processes high electron mobility transistor (HEMT) source electrode (4), drain electrode (3), grid (6) with 230 ℃ of temperature deposits Thick Si ₃N ₄Passivation layer (7) is then with the described Si of photoetching process etching ₃N ₄Passivation layer (7) makes Si ₃N ₄Passivation layer (7) zone only covers between source electrode (4) and the drain electrode (3) and the source electrode (4) and (3) edge over against side that drains;

1., covering Si b4, processing connects the air bridges (13) of two separated source between two separated source (4): ₃N ₄Apply photoresist (8) on the film of passivation layer (7), and to use that photoetching process forms directly over two separated source (4) be two bridge pier shape grooves of groove bottom with two separated source (4) upper surface respectively, adopts electron beam evaporation process or sputtering technology to cover in the surperficial and bridge pier shape groove at photoresist then

Thick TiAu or TiW double base metal level (9); 2., at TiAu or TiW double base metal level (9) surface applied photoresist (10), using once more that photoetching process forms directly over two separated source with TiAu or TiW double base metal level is the bridge connected in star (11) of groove bottom, adopts electroplating technology to go up at TiAu or TiW double base metal level (9) then and electroplates the thick Au layer (12) of 2～5 μ m; 3., with the photoresist (10) above organic solvent dissolution TiAu or the TiW double base metal level (9), erode Au layer below TiAu or outer all TiAu or the TiW double base metal level of TiW double base metal level (9) then, use photoresist (8) remaining on the described film of organic solvent dissolution at last, promptly obtain described air bridges (13), finish high electron mobility transistor (HEMT) (17) processing on the described film;

(3), use the micro electro mechanical device process technology and process the micro-acceleration gauge structure as follows:

Use etching technics and GaAs substrate (1) is etched into by peripheral pedestal (14), semi-girder (15) and by semi-girder (15) is suspended from the micro-acceleration gauge structure that the mass (16) of peripheral pedestal (14) central authorities constitutes, and make the described film that is processed with high electron mobility transistor (HEMT) (17) be positioned at the junction of semi-girder (15) and peripheral pedestal (14).

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