Electronic device structure based on weak junction characteristics and method of fabrication
By preparing YBCO thin films with tilted grain orientation and designing structures for high-resistivity, low-resistivity, and electrode regions, the problem of difficult-to-control grain boundary properties of polycrystalline materials was solved, enabling the development of special functions and performance regulation of electronic devices.
Patent Information
- Application Number
- CN202211299779.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2021-11-12
- Filing Date
- 2022-10-24
- Publication Date
- 2026-01-20
- Estimated Expiration
- 2042-10-24
AI Technical Summary
Existing technologies have difficulty effectively controlling the grain boundary properties of polycrystalline materials and their device performance, which limits the application of grain boundaries in electronic devices.
By preparing YBCO thin films with tilted grain orientation, and utilizing specific structural designs of high-resistivity, low-resistivity, and electrode regions, the weak grain boundary connectivity characteristics can be effectively controlled. Deposition, etching, and electrode setup processes are then employed to form a device structure to regulate the current direction.
It achieves full utilization of grain boundary structure features, improves the functional diversity and performance controllability of electronic devices, and is suitable for the development of special functional electronic devices.
Smart Images
Figure CN115633540B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of electronic information materials and components. BACKGROUND
[0002] For crystalline solid materials, according to the classical classification, it can be roughly divided into single crystal and polycrystal, and the interface between the grains in the polycrystal is usually treated as a defect, so whether it is material property measurement or functional device development, the first choice of people is single crystal material, but as a defect, the grain boundary also has its value, and the extreme embodiment is quantum dot nanomaterial. In quantum dot nanomaterial, the grain size is nanoscale, and the grain boundary accounts for a large proportion, and many of its properties are mainly defined by the grain boundary, and special grain boundary structure design is used to play an important role in the development of catalysts.
[0003] Although the grain boundary of quantum dot nanomaterial plays an important role in the field of catalysis, people almost avoid this defect in the field of electronic devices, or develop transistors and circuits based on single crystals and epitaxial materials, such as using single crystal silicon and epitaxial thin film to develop integrated circuits, using single crystal gallium arsenide and epitaxial material to develop semiconductor lasers, using single crystal silicon carbide and epitaxial material to develop power devices and high-frequency devices, or developing thin film transistors and integrated circuits based on amorphous materials, such as using amorphous silicon or amorphous InGaZnO thin film to develop thin film field effect transistors.
[0004] Single crystal materials are good, but functional materials are diverse and each has its own use, not all materials can be prepared into high-quality single crystals, and amorphous materials have thermal stability problems, which restrict the development of electronic devices for extreme environment applications using amorphous materials, how to develop grain boundary characteristics to meet the needs of special application scenarios has become a real problem that people need to solve.
[0005] In the prior art, the main consideration for avoiding polycrystalline materials to develop electronic devices is that it is difficult to effectively control the grain boundary characteristics and device performance of polycrystalline materials, and if this problem can be effectively solved, it is possible to effectively utilize the grain boundary to develop electronic devices with special functions. The current main method is: first cut the single crystal along a certain direction, then reassemble and combine the assembly surface through diffusion by pressing and sintering to form a bicrystal, and finally epitaxially grow a thin film with special functions on the surface of the bicrystal material, so as to introduce a special grain boundary into the thin film, which is usually called "bicrystal grain boundary".
[0006] Although the twin grain boundary is a reliable method to control the characteristics of the grain boundary, the density of the grain boundary that can be introduced is limited due to the process of cutting and splicing, and due to the strict epitaxial relationship between the epitaxial film and the single crystal substrate, although the epitaxial films on both sides of the grain boundary region have different orientation characteristics, the result of the grain boundary region is more embodied in the form of dislocation, and from the atomic level, the connection characteristics are still relatively tight, and it is difficult to effectively control the connection strength characteristics, therefore, although the twin grain boundary has a certain value, it is difficult to develop many special functional devices by using the twin grain boundary. SUMMARY
[0007] The technical problem to be solved by the present application is to provide an electronic device structure and a preparation method capable of effectively controlling the current direction of the device and fully utilizing the structure characteristics of the grain boundary.
[0008] The technical solution adopted by the present application to solve the technical problem is an electronic device structure based on the weak connection characteristics of the grain boundary, characterized in that it comprises a first electrode region connected to one end of a high resistance region and a second electrode region connected to the other end of the high resistance region.
[0009] In the first electrode region and the second electrode region, at least one electrode region is connected to the high resistance region through a low resistance region; the low resistance region, the high resistance region, the first electrode region and the second electrode region are all composed of YBCO film with tilted grain orientation.
[0010] The grain boundary lines of the YBCO film in the high resistance region and the grain boundary lines of the YBCO film in the low resistance region are in the same direction.
[0011] The axis of the high resistance region is perpendicular to the grain boundary line of the YBCO film, and the axis of the low resistance region is parallel to the grain boundary line of the YBCO film.
[0012] The first electrode region and the second electrode region are both provided with electrodes.
[0013] Further, the first electrode region and the second electrode region are each connected to the high resistance region through a low resistance region.
[0014] The electrode of the first electrode region is in circuit connection with all the grain strips in the first electrode region, and the electrode of the second electrode region is in circuit connection with all the grain strips in the second electrode region.
[0015] The grain boundary lines of the YBCO films of the first electrode region, the second electrode region and the high resistance region are in the same direction.
[0016] The present application also provides a preparation method of an electronic device structure based on the weak connection characteristics of the grain boundary, comprising the following steps:
[0017] (1) Obtain the YBCO film with the tilted grain orientation by deposition process, the angle between the grain growth direction of the YBCO film and the film normal is a preset value greater than 0;
[0018] (2) Etch the YBCO film under the mask to form the high resistance area, the low resistance area, the first electrode area and the second electrode area; in the first electrode area and the second electrode area, at least one electrode area is connected to the high resistance area through the low resistance area;
[0019] (3) Set the metal electrode on the first electrode area and the second electrode area.
[0020] The present application realizes the effective control of the grain boundary characteristics of the polycrystalline film by the growth of the fibrous grain tilted film from the film growth control, and realizes the effective control of the current flow direction of the device through the optimization of the device structure design and manufacturing process technology, so as to fully utilize the structural characteristics of the grain boundary and provide more possibilities for the development of special functional electronic devices. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 is a schematic diagram of the preparation method of the tilted grain film;
[0022] Figure 2 is a schematic diagram of the high index surface step generated by surface reconstruction;
[0023] Figure 3 is a schematic diagram of the electronic device structure of the present application;
[0024] Figure 4 is a schematic diagram of the electrode arrangement of example 1 (four-terminal electronic device);
[0025] Figure 5 is a schematic diagram of the electrode arrangement of example 2 (two-terminal electronic device);
[0026] Figure 6 is a preparation process flow of the present application;
[0027] Figure 7 is a micrograph of the cross-sectional structure of the film material with close combination between the tilted grains;
[0028] Figure 8 is a micrograph of the cross-sectional structure of the film material with relatively loose combination between the tilted grains;
[0029] Figure 9 is a micrograph of the cross-sectional structure of the film material with combination between the tilted grains in a state between close and loose. DETAILED DESCRIPTION
[0030] I. Embodiment of the device:
[0031] The electronic device structure based on the weak connection characteristics of the grain boundary is shown in Figure 3 , which comprises a first electrode area 34 connected to one end of the high resistance area 33 and a second electrode area 35 connected to the other end of the high resistance area 33.
[0032] At least one of the first electrode area and the second electrode area is connected to the high resistance area through a low resistance area; the low resistance area, the high resistance area, the first electrode area and the second electrode area are all composed of the YBCO film with tilted grain orientation. Figure 3 In the embodiment shown in
[0033] The grain boundary line of the YBCO film in the high resistance area and the grain boundary line of the YBCO film in the low resistance area are in the same direction; the top end of the arrow marked as 36 is a grain boundary line, Figure 3 In the embodiment shown in
[0034] The axis of the high resistance area is perpendicular to the grain boundary line of the YBCO film, and the axis of the low resistance area is parallel to the grain boundary line of the YBCO film; the direction of the axis of the high resistance area is consistent with the direction of the arrow marked as 32 (the current direction).
[0035] The first electrode area and the second electrode area are both provided with electrodes 31.
[0036] Further, the first electrode area and the second electrode area are each connected to the high resistance area through a low resistance area.
[0037] The electrode of the first electrode area is in circuit connection with all the grain strips in the first electrode area, and the electrode of the second electrode area is in circuit connection with all the grain strips in the second electrode area.
[0038] The grain boundary lines of the YBCO films of the first electrode area, the second electrode area and the high resistance area are in the same direction.
[0039] II. Embodiment of the preparation method:
[0040] Step 1: Preparation of the film with tilted grain orientation
[0041] According to the directional characteristics of the atomic, molecular and ion beam flow in the film deposition process, the present application provides two preparation methods of the film with tilted grain orientation,
[0042] The first method is shown in Figure 1 , which is mainly aimed at the atomic, molecular and ion beam flow with good directionality in the film deposition process, so that the microstructure of the deposited film can be controlled by adjusting the angle α between the direction of the beam source and the normal direction of the substrate surface, thereby realizing the controllable preparation of the film with tilted grain orientation. From the perspective of film preparation technology, this method is suitable for preparing the film with tilted grain orientation by using techniques such as thermal evaporation, electron beam evaporation and molecular beam epitaxy.
[0043] Figure 1 In the diagram, 11 represents the mechanism that generates atomic, molecular, and ion beam sources during thin film deposition; 12 represents the directional atomic, molecular, and ion beam sources generated during thin film deposition; 13 represents the normal direction of the substrate surface used for thin film deposition; 14 represents the substrate used for thin film deposition; and 15 represents the center direction of the atomic, molecular, and ion beam sources generated during thin film deposition.
[0044] The second method is as follows: Figure 2 As shown, when atoms, molecules, and ion beams do not possess good directionality during thin film deposition, a high-index surface step structure can be formed through substrate surface reconstruction. This high-index surface step structure can be used to control the microstructure of the deposited thin film, thereby preparing grain-oriented films. From the perspective of thin film fabrication technology, this method is applicable to the preparation of grain-oriented films using techniques such as DC sputtering, RF sputtering, magnetron sputtering, ion plating, chemical vapor deposition, and metal-organic chemical vapor deposition.
[0045] Figure 2 In the diagram, 21 represents a single-crystal substrate; 22 represents a high-index step on the surface of the single-crystal substrate, and the direction of the dashed arrow indicates the tilt direction.
[0046] Step 2: Device structure design based on grain boundary weak connectivity characteristics
[0047] In order to optimize the electrical performance parameters of the device, in addition to effectively controlling the weak connection characteristics of the grain boundaries in thin film, it is also necessary to design the device structure so that the current / voltage signals of the device reflect the weak connection characteristics of the grain boundaries as much as possible.
[0048] Therefore, the present invention adopts Figure 3 The device structure shown uses microfabrication technology to etch a high-resistivity region into the thin film along the grain tilt direction. Figure 3 The area marked by the elliptical dashed line is designed so that when current (in the direction shown by the arrow) flows through this high-resistivity region, the current must pass through a series of weakly connected grain boundary regions in series, so that the output of the device mainly reflects the weakly connected grain boundary characteristics.
[0049] Furthermore, two typical electrode structures can be adopted for the two types of typical output signal characteristics:
[0050] a. When a device requires a certain applied bias voltage or bias current to generate a signal output, in order to minimize the impact of electrode contact resistance on the output signal, the following should be adopted: Figure 4 The diagram shows a four-terminal electrode structure. In the figure, 41 represents the external metal electrode; 42 represents the effective operating region of the grain boundary weakly connected device.
[0051] b、When the device output exhibits a "self-bias" characteristic, i.e. the device can respond to external input signals and produce certain current or voltage signal outputs without an externally applied bias voltage or bias current, a two-terminal electrode structure as shown in Fig. 2 can be used to reduce the number of electrode leads. 51 represents an external metal electrode, and 52 represents the effective working area of the grain boundary weakly connected device. Figure 5
[0052] Step 3: Overall device manufacturing
[0053] According to the device structure shown in Fig. 1, the present application uses the process flow shown in Fig. 2 to complete device manufacturing, and the specific process flow is as follows: Figure 3 Figure 6
[0054] (1) A layer of positive photoresist is applied to the surface of the deposited grain-tilted YBCO film, followed by pre-baking.
[0055] (2) The pre-baked photoresist is exposed using a photolithography machine with a photomask, followed by development of the exposed photoresist.
[0056] (3) The developed photoresist is etched using a phosphoric acid solution. In addition to etching the YBCO into a long strip of a certain length and width, a certain width and length of YBCO film is also left on both sides of the long strip in the length direction as an electrode lead area. The long strip is then used as the fabrication area of the corresponding device. The size of the long strip and the electrode lead area is adjusted according to device design.
[0057] (4) A layer of negative photoresist is applied to the surface of the etched film, followed by pre-baking.
[0058] (5) The pre-baked photoresist is exposed for a second time using a photolithography machine with a photomask, followed by further post-baking.
[0059] (6) The post-baked photoresist is subjected to flood exposure, followed by development, to define the electrode pattern deposition area of the device.
[0060] (7) Ti / Au electrode films are deposited using electron beam evaporation technology to fabricate electrode leads.
[0061] (8) Ion beam etching technology is used to etch the device structure shown in Fig. 3 in the fabricated long strip area. The device size can be adjusted according to design needs.
[0062] Based on the technology of the present application, taking the multi-oxide YBa2Cu3O7 (hereinafter referred to as YBCO) as a carrier, through the specific implementation of the grain tilt-oriented YBCO thin film case, two kinds of electronic functional devices utilizing the weak connection characteristics of the YBCO thin film grain boundary are developed, including a thin film heat flow sensor and a grain boundary weak connection type Josephson junction device, which not only provides device support for the combustion state parameter measurement and monitoring of the turbine parts of an aero-engine, but also provides an alternative technical path for extremely weak magnetic field measurement.
[0063] Embodiment 1: Thin film heat flow sensor
[0064] By using the method of the present application, several typical weak connection characteristic YBCO thin films are prepared, such as Figure 7 、 Figure 8 、 Figure 9 corresponding to Figure 1 different beam source direction and normal line angle α values of the substrate surface, when the α value is small, the connection of the grain boundary is relatively tight, and with the increase of the α value, the connection between the grain boundaries is more relaxed.
[0065] On the basis of realizing the control of the weak connection characteristics of the grain boundary, the present application uses the YBCO thin film with relatively relaxed grain boundary as shown in Figure 8 to develop a thin film heat flow sensor, and the device and electrode structure adopts the structure shown in Fig. 5. Its working principle can be equivalent to the series connection of a series of vertically arranged thermocouples. When the heat flow sweeps the surface of the device to cause the temperature difference of the thin film along the thickness direction, based on the thermoelectric potential effect, an electric potential output is generated. Since the grain boundary of the thin film is relatively relaxed, it is equivalent to the series connection of many thermocouples, so that a large enough output voltage signal is obtained, showing good response characteristics to the heat flow, and has been applied to the parameter measurement of the combustion state of the turbine parts of an aero-engine.
[0066] Embodiment 2: Grain boundary weak connection type Josephson junction device
[0067] On the basis of realizing the control of the weak connection characteristics of the grain boundary, the present application also uses the YBCO thin film with relatively tight grain boundary as shown in Figure 7 to develop a grain boundary weak connection type Josephson junction device, and the device and electrode structure adopts the structure shown in Figure 4 . Unlike the working principle of the thin film heat flow sensor, when the grain boundary is relatively tight, the current can directly flow through the grain boundary, which is equivalent to the series connection of many grain boundary weak connection type Josephson junctions. Test results show that the device has excellent Josephson effect and good technical value in weak magnetic field measurement.
Claims
1. An electronic device structure based on the weak grain boundary connectivity characteristics, characterized in that, It includes a first electrode region connected to one end of the high-resistivity region and a second electrode region connected to the other end of the high-resistivity region; In the first electrode region and the second electrode region, at least one electrode region is connected to the high-resistivity region through the low-resistivity region; the low-resistivity region, the high-resistivity region, the first electrode region, and the second electrode region are all composed of YBCO thin films with tilted grain orientation; The grain boundary lines of the YBCO thin film in the high-resistivity region are in the same direction as those of the YBCO thin film in the low-resistivity region. The axis of the high-resistivity region is perpendicular to the grain boundary line of the YBCO thin film, while the axis of the low-resistivity region is parallel to the grain boundary line of the YBCO thin film. Electrodes are provided in both the first electrode region and the second electrode region; The first electrode region and the second electrode region are each connected to the high-resistance region through a low-resistance region. The electrodes of the first electrode region are connected to all the grain strips within the first electrode region to form a circuit, and the electrodes of the second electrode region are connected to all the grain strips within the second electrode region to form a circuit. The grain boundaries of the YBCO thin films in the first electrode region, the second electrode region, and the high-resistivity region are in the same direction.
2. A method for fabricating an electronic device structure based on the weak grain boundary connectivity characteristics as described in claim 1, characterized in that, Includes the following steps: (1) A YBCO thin film with tilted grain orientation is obtained by deposition process, wherein the angle between the grain growth direction of the YBCO thin film and the film normal is a preset value greater than 0. (2) The YBCO thin film is etched under the mask to form a high-resistivity region, a low-resistivity region, a first electrode region and a second electrode region; at least one of the first electrode regions and the second electrode region is connected to the high-resistivity region through the low-resistivity region. (3) Metal electrodes are placed on the first electrode region and the second electrode region.