Heterojunction bipolar transistor device with piezoelectric effect and preparation method thereof

Abstract

The invention belongs to the technical field of microelectronics and piezoelectric electronics, and relates to a heterojunction bipolar transistor device with a piezoelectric effect and a preparation method thereof, the heterojunction bipolar transistor device comprises a substrate, an insulating layer, an emitter region, a collector region and a metal electrode; the base is of a convex structure, the middle convex part of the base is marked as a base region, and the non-convex parts at the two ends of the base are marked as substrates; the insulating layers cover the substrates at the two ends of the substrate, and the emitter region and the collector region are located on the insulating layers at the two ends of the substrate respectively; the metal electrodes comprise a first metal electrode, a second metal electrode and a third metal electrode; the first metal electrode, the second metal electrode and the third metal electrode are respectively arranged on the collector region, the emitter region and the base region and are not in contact with one another, the emitter region and the collector region are both made of N-type ZnO, the substrate is made of silicon, and the technical effect of improving the stability and controllability of the piezoelectric effect is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of microelectronics and piezoelectric electronics, and in particular, relates to a heterojunction bipolar transistor device with piezoelectric effect and a preparation method thereof. Background Art

[0002] Zinc oxide (ZnO), as a wide bandgap semiconductor material with piezoelectric effect and excellent optoelectronic properties, has received widespread attention in recent years. ZnO is an N-type conductive direct bandgap semiconductor with a bandgap width of 3.37eV and a large exciton binding energy (60meV), which makes it have a strong exciton luminescence effect at room temperature. Due to its unique piezoelectric properties, ZnO has great application potential in sensors, optoelectronic devices and nanoelectronic devices. However, there are some technical drawbacks and defects in the practical application of ZnO materials, such as the relatively poor stability and controllability of its piezoelectric properties, and limited integration compatibility with existing semiconductor materials, which limits its application in high-performance electronic and optoelectronic devices.

[0003] Among the existing semiconductor materials, silicon (Si) is widely used in various electronic devices due to its excellent semiconductor properties and mature integrated circuit industry foundation. Si has stable electrical properties and mature manufacturing processes, but its piezoelectric effect is weak, which limits its application in piezoelectric sensors and energy harvesting devices. In addition, the optoelectronic properties of Si also have certain limitations compared to wide bandgap semiconductor materials such as ZnO, especially in high-frequency and high-power application scenarios.

[0004] In the research on ZnO-Si heterojunctions in the prior art, ZnO nanowires have been widely studied due to their unique piezoelectric properties. However, these studies face some challenges: first, the design requirements of the nanowire device structure are extremely strict, and the size and arrangement of the nanowires need to be precisely controlled; second, the preparation process of ZnO nanowires is relatively complex, involving precise control of growth conditions. In addition, due to the tiny nature of the ZnO nanowire structure, screening out nanowires with the desired structure is a technical challenge, requiring precise characterization and screening techniques. This limits the device research and application potential of ZnO-Si heterojunctions at different scales. In the research on ZnO-Si heterojunction structures in the prior art, although the piezoelectric properties of ZnO and the semiconductor properties of Si are publicly combined, the preparation cost of such heterojunctions in the prior art is relatively high. Summary of the invention

[0005] In view of the defects of the prior art, the present invention provides a heterojunction bipolar transistor device with piezoelectric effect and a preparation method thereof, aiming to solve the technical problems of the prior art such as difficulty in interface stability and electrical property regulation of ZnO nanowire devices and small current gain, so as to achieve the technical effect of improving the stability and controllability of the piezoelectric regulation effect, enhancing the current gain, and realizing the ability of stress to regulate electrical properties.

[0006] According to a first aspect of the present invention, there is provided a heterojunction bipolar transistor device with piezoelectric effect, the structure of which includes a substrate, an insulating layer, an emitter region, a collector region and a metal electrode; the substrate is a convex structure, the raised portion in the middle of the substrate is the base region, and the unraised portions at both ends are the substrate; the substrates at both ends of the substrate are covered with the insulating layer, and the emitter region and the collector region are respectively located on the insulating layer at both ends of the substrate; the metal electrode includes a first metal electrode, a second metal electrode and a third metal electrode; the first metal electrode, the second metal electrode and the third metal electrode are respectively arranged on the collector region, the emitter region and the base region, and are not in contact with each other, the materials of the emitter region and the collector region are both N-type ZnO, and the substrate is silicon.

[0007] Preferably, the emitter region and the collector region have the same thickness, which is 0.5-2 um.

[0008] Preferably, the materials of the first metal electrode, the second metal electrode and the third metal electrode are independently selected from a titanium-gold composite material or a titanium-aluminum composite material; when the material of the electrode is a titanium-gold composite material, its top layer is gold and its bottom layer is titanium; when the material of the electrode is a titanium-aluminum composite material, its top layer is aluminum and its bottom layer is titanium.

[0009] Preferably, the thickness of the bottom layer is 5 to 20 nm, and the thickness of the top layer is 80 to 150 nm.

[0010] Preferably, the material of the insulating layer is selected from SiO2, Si3N4, or HfO2.

[0011] According to another aspect of the present invention, a method for preparing the heterojunction bipolar transistor device with piezoelectric effect is provided, characterized in that the specific steps are:

[0012] (1) Select a substrate;

[0013] (2) etching the substrate to form a convex structure, wherein the convex portion in the middle of the substrate is referred to as the base region, and the non-convex portions at both ends are referred to as the substrate;

[0014] (3) thermally oxidizing the convex structure obtained in step (2) to form a thermal oxidation layer on the convex structure;

[0015] (4) using dry etching to remove the thermal oxide layer from the base region of the structure obtained in step (3), and the thermal oxide layer remaining on the substrate is an insulating layer;

[0016] (5) preparing an emitter region and a collector region on the insulating layer prepared in step (4) by magnetron sputtering;

[0017] (6) Depositing a first metal electrode, a second metal electrode, and a third metal electrode on the collector region, the emitter region, and the base region respectively by electron beam evaporation, and making sure that the first metal electrode, the second metal electrode, and the third metal electrode are not in contact with each other.

[0018] Preferably, the substrate in step (1) is pre-treated, and the pre-treatment specifically comprises first cleaning with acetone, then cleaning with anhydrous ethanol, then rinsing with deionized water, and finally drying with a nitrogen gun.

[0019] Preferably, the specific temperature of the thermal oxidation in step (3) is 850-1000° C., and the thermal oxidation time is 10-30 min.

[0020] Preferably, the sputtering power of the magnetron sputtering in step (5) is 180 to 300 W, and the sputtering time is 1 to 2 hours.

[0021] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0022] (1) The present invention combines N-type ZnO and P-type Si to form an efficient heterojunction structure, which combines the piezoelectric properties of ZnO with the excellent semiconductor properties of Si. It can not only achieve better current transmission, but also utilize the piezoelectric properties of ZnO to regulate its electrical properties by applying stress. It not only meets the electrical properties of bipolar transistors in structure, but also can effectively achieve electromechanical coupling through external stress to regulate the electrical properties, aiming to regulate the current gain of transistors through stress. The heterojunction structure can increase the switching speed of the device, improve the current gain, and has high sensitivity and linearity, and is suitable for high-performance electronic and optoelectronic devices.

[0023] (2) The present invention effectively isolates the direct contact between the piezoelectric material and the substrate by introducing an insulating layer, thereby avoiding longitudinal loss of current, reducing leakage, and transferring more charges between the emitter region, the base region and the collector region, thereby improving the current transmission efficiency.

[0024] (3) The present invention adopts a horizontal structural design, placing the emitter region, collector region and base region of the device on the same plane. This configuration of lateral distribution of each region is more convenient for applying stress and more sensitive to strain.

[0025] (4) The process steps of the present invention are simple and the parameters are easy to control. This innovative structure not only has excellent device characteristics, but also has broad application prospects. The built-in electric field at the heterojunction interface enables the device to operate at a low voltage, thereby reducing energy consumption. At the same time, the stable electrical characteristics provided by the heterojunction effectively prevent unnecessary charge transfer, further improving the long-term reliability of the device. In addition, the structure allows the combination of materials with multiple physical properties, providing more possibilities for the design of multi-purpose electronic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of a heterojunction bipolar transistor device with piezoelectric effect provided in Example 1 of the present invention.

[0027] Among them, 1. Collector region; 2. Metal electrode; 3. Substrate; 4. Emitter region; 5. Insulating layer. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Example 1

[0030] like Figure 1 As shown, a heterojunction bipolar transistor device with piezoelectric effect, its structure includes a substrate 3, an insulating layer 5, an emitter region 4, a collector region 1 and a metal electrode 2, the substrate 3 is a convex structure, the raised part in the middle of the substrate 3 is the base region, and the unraised parts at both ends are the substrate, the substrates at both ends of the substrate 3 are covered with the insulating layer 5, the emitter region 4 and the collector region 1 are respectively located on the insulating layer 5 at both ends of the substrate 3, the metal electrode 2 includes a first metal electrode, a second metal electrode, and a third metal electrode, the first metal electrode, the second metal electrode, and the third metal electrode are respectively arranged on the collector region 1, the emitter region 4, and the base region, and are not in contact with each other, the emitter region 4 and the collector region 1 are both N-type ZnO, and the substrate 3 is silicon. The thickness of the emitter region 4 and the collector region 1 are both 1um; the materials of the first metal electrode, the second metal electrode and the third metal electrode are titanium-aluminum composite materials, the top layer of which is aluminum and the bottom layer is titanium. The thickness of the bottom layer is 10nm and the thickness of the top layer is 90nm; the material of the insulating layer 5 is selected from SiO2.

[0031] Example 2

[0032] A method for preparing a heterojunction bipolar transistor device with piezoelectric effect is provided, the specific steps of which are:

[0033] 1. Select a P-type silicon substrate. The specific operation is as follows: first use an acetone solution to ultrasonically clean for 10 minutes to remove organic dirt; then use anhydrous ethanol to ultrasonically clean for 10 minutes to remove acetone, rinse with deionized water, and then blow dry with a nitrogen gun.

[0034] 2. Etching the emitter and collector areas: Spin-coating, exposing and developing photoresist: Spin-coat the photoresist on the P-type silicon substrate, set the spin-coating speed to 1000r / min for 10 seconds, then accelerate to 4000r / min for 30 seconds, use negative photoresist, set the temperature to 97°C, bake for 2 minutes, and the exposure time of the photolithography machine is 8 seconds. Etch; after etching, remove the photoresist residue, rinse with deionized water and blow dry with nitrogen.

[0035] 3. Preparation of insulating layer: Thermal oxidation is performed at a temperature of 950°C for 15 minutes to form a 50nm thick SiO2 insulating layer.

[0036] 4. Use negative photoresist process to dry etch to remove the oxide layer from the base area.

[0037] 5. Deposition of N-type ZnO film in the emitter area: Use positive photoresist process to prepare the target pattern. Use magnetron sputtering to deposit N-type ZnO film with a controlled thickness of 0.5μm. Sputtering parameters: power 180W, argon oxygen ratio 87.2:1.6 (sccm), sputtering time 1 hour. After sputtering, remove the photoresist according to the process steps.

[0038] 6. Deposition of N-type ZnO thin film in collector area: Use positive photoresist process to prepare target pattern. Use magnetron sputtering method to deposit N-type ZnO thin film with controlled thickness of 0.5μm. Sputtering parameters: power 180W, argon oxygen ratio 87.2:1.6 (sccm), sputtering time 1 hour. After sputtering, remove the photoresist according to the process steps.

[0039] 7. Electrode evaporation: Use negative photoresist technology to prepare electrode patterns to divide the X, Y, and Z regions, and use electron beam evaporation to evaporate electrodes in the collector area, emitter area, and base area: evaporate Ti at the bottom layer with a thickness of 10nm. Evaporate Au at the top layer with a thickness of 150nm to form the first metal electrode, the second metal electrode, and the third metal electrode respectively.

[0040] Example 3

[0041] A method for preparing a heterojunction bipolar transistor device with piezoelectric effect is provided, the specific steps of which are:

[0042] 1. Select a P-type silicon substrate. The specific operation is as follows: first use an acetone solution to ultrasonicate for 10 minutes to clean and remove organic dirt; then use anhydrous ethanol to ultrasonicate for 10 minutes to clean and remove acetone, and blow dry with a nitrogen gun;

[0043] 2. Etching the emitter and collector areas: Spin-coating, exposing and developing photoresist: Spin-coat the photoresist on the P-type silicon substrate, set the spin-coating speed to 1000r / min for 10 seconds, then accelerate to 4000r / min for 30 seconds, use negative photoresist, set the temperature to 97°C, bake for 2 minutes, use a photolithography machine, and expose for 8 seconds. Etch; after etching, remove the photoresist residue, rinse with deionized water and blow dry with nitrogen.

[0044] 3. Preparation of insulating layer: Thermal oxidation is performed at a temperature of 850°C for 30 minutes to form a 100 nm thick SiO2 insulating layer.

[0045] 4. Use negative photoresist process to dry etch to remove the oxide layer from the base area.

[0046] 5. Deposition of N-type ZnO film in the emitter area: Use positive photoresist process to prepare the target pattern. Use magnetron sputtering to deposit N-type ZnO film with a controlled thickness of 1μm. Sputtering parameters: power 180W, argon oxygen ratio 87.2:1.6 (sccm), sputtering time 2 hours. After sputtering, remove the photoresist according to the process steps described above.

[0047] 6. Deposition of N-type ZnO thin film in collector area: Use positive photoresist process to prepare target pattern. Use magnetron sputtering method to deposit N-type ZnO thin film, and control thickness to be 1μm. Sputtering parameters: power 180W, argon oxygen ratio 87.2:1.6 (sccm), sputtering time 2 hours. After sputtering, remove the photoresist according to the process steps described above.

[0048] 7. Electrode evaporation: Use negative photoresist technology to prepare electrode patterns to divide the X, Y, and Z regions, and use electron beam evaporation to evaporate electrodes in the collector area, emitter area, and base area: evaporate Ti at the bottom layer with a thickness of 50nm. Evaporate Au at the top layer with a thickness of 150nm to form the first metal electrode, the second metal electrode, and the third metal electrode respectively.

[0049] Example 4

[0050] A method for preparing a heterojunction bipolar transistor device with piezoelectric effect is provided, the specific steps of which are:

[0051] 1. Select a P-type silicon substrate. The specific operation is as follows: first use an acetone solution to ultrasonicate for 10 minutes to clean and remove organic dirt; then use anhydrous ethanol to ultrasonicate for 10 minutes to clean and remove acetone, and blow dry with a nitrogen gun;

[0052] 2. Etching the emitter and collector areas: Spin-coating, exposing and developing photoresist: Spin-coat the photoresist on the P-type silicon substrate, set the spin-coating speed to 1000r / min for 10 seconds, then accelerate to 4000r / min for 30 seconds, use AZ5214 negative photoresist, set the temperature to 97°C, bake for 2 minutes, use MA8 photolithography machine, and the exposure time is 8 seconds. Etch; after etching, remove the photoresist residue, wash with deionized water and blow dry with nitrogen.

[0053] 3. Preparation of insulating layer: Thermal oxidation is performed at a temperature of 900°C for 30 minutes to form a SiO2 insulating layer.

[0054] 4. Use negative photoresist process and dry etching to remove the oxide layer from the base area.

[0055] 5. Deposition of N-type ZnO film in the emitter area: Use positive photoresist process to prepare the target pattern. Use magnetron sputtering to deposit N-type ZnO film with a controlled thickness of about 0.8μm. Sputtering parameters: power 180W, argon oxygen ratio 87.2:1.6 (sccm), sputtering time 1.5 hours. After sputtering, remove the photoresist according to the process steps.

[0056] 6. Deposition of N-type ZnO thin film in collector area: Use positive photoresist process to prepare target pattern. Use magnetron sputtering method to deposit N-type ZnO thin film, and control thickness to be about 0.8μm. Sputtering parameters: power 180W, argon oxygen ratio 87.2:1.6 (sccm), sputtering time 1.5 hours. After sputtering, remove the photoresist according to the process steps

[0057] 7. Electrode evaporation: Use negative photoresist technology to prepare electrode patterns to divide the X, Y, and Z regions, and use electron beam evaporation to evaporate electrodes in the collector region, emitter region, and base region: evaporate Ti at the bottom layer with a thickness of 20nm. Evaporate Au at the top layer with a thickness of 80nm to form the first metal electrode, the second metal electrode, and the third metal electrode respectively.

[0058] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A heterojunction bipolar transistor device with piezoelectric effect, characterized in that: Its structure includes: A substrate (3), an insulating layer (5), an emitter region (4), a collector region (1) and a metal electrode (2); the substrate (3) is a convex structure, the raised portion in the middle of the substrate (3) is the base region, and the unraised portions at both ends are the substrate; the substrates at both ends of the substrate (3) are covered with the insulating layer (5), and the emitter region (4) and the collector region (1) are respectively located on the insulating layer (5) at both ends of the substrate (3); the metal electrode (2) includes a first metal electrode, a second metal electrode and a third metal electrode, and the first metal electrode, the second metal electrode and the third metal electrode are respectively arranged on the collector region (1), the emitter region (4) and the base region, and are not in contact with each other; the materials of the emitter region (4) and the collector region (1) are both N-type ZnO, and the substrate (3) is silicon.

2. A heterojunction bipolar transistor device with piezoelectric effect according to claim 1, characterized in that: The thickness of the emitter region (4) is the same as that of the collector region (1), and the thickness is 0.5 to 2 um.

3. The heterojunction bipolar transistor device with piezoelectric effect according to claim 1, characterized in that: The materials of the first metal electrode, the second metal electrode and the third metal electrode are independently selected from titanium-gold composite materials or titanium-aluminum composite materials; when the material of the electrode is titanium-gold composite materials, its top layer is gold and its bottom layer is titanium; when the material of the electrode is titanium-aluminum composite materials, its top layer is aluminum and its bottom layer is titanium.

4. A heterojunction bipolar transistor device with piezoelectric effect according to claim 3, characterized in that: The thickness of the bottom layer is 5 to 20 nm, and the thickness of the top layer is 80 to 150 nm.

5. The heterojunction bipolar transistor device with piezoelectric effect according to claim 1, characterized in that: The material of the insulating layer (5) is selected from SiO2, Si3N4, or HfO2.

6. A method for preparing a heterojunction bipolar transistor device with piezoelectric effect as claimed in any one of claims 1 to 5, characterized in that: The specific steps are: (1) Selecting a substrate; (2) etching the substrate to form a convex structure, wherein the convex portion in the middle of the substrate is referred to as the base region, and the non-convex portions at both ends are referred to as the substrate; (3) thermally oxidizing the convex structure obtained in step (2) to form a thermal oxidation layer on the convex structure; (4) removing the thermal oxide layer from the base region of the structure obtained in step (3) by dry etching, and retaining the thermal oxide layer on the substrate as an insulating layer; (5) preparing an emitter region and a collector region on the insulating layer prepared in step (4) by magnetron sputtering; (6) Depositing a first metal electrode, a second metal electrode and a third metal electrode on the collector region, the emitter region and the base region respectively by electron beam evaporation, and making the first metal electrode, the second metal electrode and the third metal electrode not in contact with each other.

7. The method for preparing a heterojunction bipolar transistor device with piezoelectric effect according to claim 6, characterized in that: The substrate in step (1) is pre-treated, wherein the pre-treatment is firstly cleaned with acetone, then cleaned with anhydrous ethanol, then rinsed with deionized water, and finally dried with a nitrogen gun.

8. The method for preparing a heterojunction bipolar transistor device with piezoelectric effect according to claim 6, characterized in that: The specific temperature of the thermal oxidation in step (3) is 850-1000° C., and the time of the thermal oxidation is 10-30 minutes.

9. The method for preparing a heterojunction bipolar transistor device with piezoelectric effect according to claim 6, characterized in that: The sputtering power of the magnetron sputtering in step (5) is 180 to 300 W, and the sputtering time is 1 to 2 hours.

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