Transverse zn o nanowire uv detector array readout electrode structure and preparation method

Abstract

The application discloses a transverse ZnO nanowire ultraviolet detector array readout electrode structure and a preparation method thereof, and belongs to the field of semiconductor microelectronics.The structure is as follows: a longitudinal electrode and a transverse electrode form a grid structure as a whole, an adhesion layer and an isolation layer are arranged between a laminated lapping part of the longitudinal electrode and the transverse electrode, and one ZnO ultraviolet detector is arranged in each grid.The thickness of the longitudinal electrode is d1, the thickness of a ZnO seed layer of the device is d2, and the thickness of a Ti / Au electrode layer of the device is d3, and the following requirements are met: d3 > d1 > d2, 150 nm < d1 < 200 nm, 100 nm < d2 < 150 nm, and 200 nm < d3 < 250 nm.The stable readout electrode structure can be obtained by avoiding signal crosstalk between the devices, realizing stable connection between the device and the electrode, and realizing isolation between the hierarchical electrodes.

Description

TECHNICAL FIELD

[0001] The application relates to a readout electrode structure process for bridging a ZnO nanowire ultraviolet detector array and a preparation method thereof, and belongs to the field of semiconductor microelectronics. BACKGROUND

[0002] In recent years, ultraviolet (UV) detectors have been increasingly widely applied in multiple fields, and the ultraviolet detection technology is becoming more and more important, especially in the aspects of environmental monitoring, space exploration, radiation monitoring, safety detection and medical diagnosis. The ultraviolet detector has key functions such as detecting ultraviolet light sources, monitoring air quality and measuring ultraviolet radiation intensity. Therefore, developing an ultraviolet detector with high sensitivity, fast response and high integration has always been the research focus of researchers and engineering technicians.

[0003] The third-generation semiconductor material zinc oxide (ZnO) has great application potential in the field of ultraviolet detection due to its strong photoelectric performance, wide band gap and good thermal stability. The ZnO nanowire device has a wide band gap, high electron mobility, low carrier scattering rate and high surface area, and can realize high-sensitivity and high-response-speed ultraviolet detection, thus becoming an important research direction in the field of ultraviolet light detectors.

[0004] At present, the ultraviolet detector based on ZnO nanowires has attracted wide attention and research. However, the existing ZnO nanowire ultraviolet detector still faces some challenges in practical application, especially in the aspects of device array and integration. The traditional electrode structure often cannot effectively solve the requirements of device array on signal reading efficiency and stability. How to avoid signal crosstalk between devices, realize stable connection between devices and electrodes and isolation between hierarchical electrodes and other problems is still a difficulty in current research. SUMMARY

[0005] In order to solve the above problems, the purpose of the present application is to provide a stable detector array readout electrode structure, by controlling the etching time of the isolation layer, the thickness of the seed layer of the detector, the thickness of the electrode layer of the detector and the thickness of the readout electrode and other parameters to obtain a high-uniformity and high-stability readout electrode structure.

[0006] The present application provides a detector array readout electrode structure process based on a ZnO ultraviolet detector array, which is demonstrated and verified by a ZnO nanowire ultraviolet detector array. Referring to Figure 1 From the top view of part of the readout electrode structure, the structure comprises: a longitudinal electrode Ti / Au (101), an adhesion layer Ti (102), an isolation layer SiO2 (103), a transverse electrode Ti / Au (104) and a device array structure ZnO / Ti / Au (105);

[0007] Depositing a plurality of strip-shaped, parallel and independent Ti / Au films on the substrate as longitudinal electrodes (101), and depositing a layer of block-shaped Ti layer on part of the longitudinal electrodes as an adhesion layer (102); depositing a layer of SiO2 film on the surface of the substrate, and performing patterning on the SiO2 film by wet etching, leaving the SiO2 film on the adhesion layer and larger than the adhesion layer as an isolation layer (103), that is, the isolation layer (103) and the longitudinal electrodes (101) completely cover the adhesion layer (102), and the cross-sectional structure of the isolation layer is as shown in Figure 2 . The etching progress of the isolation layer (103) is required to be not too large, so that over-etching phenomenon does not occur, and the longitudinal and horizontal electrodes are linked together, and the cross-sectional structure of the isolation layer with excessive etching is as shown in Figure 3 . The optimal etching progress is under-etching.

[0008] At this time, further depositing a plurality of strip-shaped, parallel and independent Ti / Au films on the substrate as horizontal electrodes (104), the horizontal electrodes being perpendicular to the longitudinal electrodes, the horizontal electrodes (104) being stacked on the longitudinal electrodes (101) to form a complete readout electrode structure, and the longitudinal electrodes (101) and the horizontal electrodes (104) forming a grid structure as a whole, and the stacked adhesion layer (102) and the isolation layer (103) being between the stacked and overlapped parts of the longitudinal electrodes (101) and the horizontal electrodes (104).

[0009] Testing the readout electrode structure (1V voltage test is adopted, and the isolation effect of the isolation layer is best when the current is 0 during the test, and the isolation effect is judged according to the current size), and testing the isolation effect of the isolation layer. If most of the isolation layers have poor effects, it may be due to the over-etching phenomenon caused by the excessive etching time of the isolation layer, and thus it is necessary to start from the substrate to re-produce. If most of the isolation layers have good effects, and only part or even individual isolation layers have poor isolation effects, it may be due to the non-uniform deposition of the SiO2 layer, and holes are formed. The cross-sectional structure of the isolation layer with holes is as shown in Figure 4 . The holes are deposited with some impurities (401) during the preparation process, and some electrode materials also enter the holes during the preparation of the horizontal electrodes, and then the problem of poor isolation effect occurs. Repairing the isolation layer with holes by applying a large voltage (applying a voltage of 5-10V to the horizontal electrodes and the longitudinal electrodes of the readout electrode structure for repair), that is, performing an aging process step, so that the impurities reach a state similar to breakdown and burnout, and the isolation effect is restored, as shown in Figure 5 . It is ensured that each isolation layer (103) between the longitudinal electrodes and the horizontal electrodes has good isolation effect, so that crosstalk and other problems do not occur between the read and write circuits.

[0010] ZnO ultraviolet detector array is prepared on the readout electrode structure, that is, one ZnO ultraviolet detector is prepared in each grid formed by the longitudinal electrode (101) and the transverse electrode (104), or ZnO ultraviolet detectors are prepared in different grids as required; the ZnO ultraviolet detector comprises: two parallel symmetrical and independent ZnO film layers are deposited as seed layers, one seed layer is parallel to the longitudinal electrode and connected together in contact, and the other seed layer is perpendicular to the transverse electrode, the transverse electrode is provided with a side protrusion or extension and connected together in contact with the other seed layer; a metal electrode layer is deposited on the ZnO seed layer; ZnO nanowires are grown on the opposite two sides of the ZnO seed layer, and a complete bridging ZnO nanowire ultraviolet detector array structure is formed. The cross-sectional structure of the area where the detector array intersects with the longitudinal and transverse electrodes is shown in Figure 6 , and the part intersecting with the longitudinal electrode is taken as an example, and the part intersecting with the transverse electrode is the same, and the dashed line in the figure is the position of the cross section.

[0011] Requirements are proposed for the thickness (601) of the electrode, the thickness (602) of the seed layer and the thickness of the longitudinal electrode (101) below the seed layer of the traditional device array in which the seed layer is used to grow nanowires, so that an absolutely stable and reliable connection between the readout electrode structure and the device is realized. The requirement is not only applicable to the bridging ZnO nanowire ultraviolet detector array, but also has universality for other device arrays in which the seed layer is used to grow nanowires. The thickness of the longitudinal electrode (101) and the transverse electrode is the same.

[0012] The requirement is shown in Figure 7 , the thickness of the longitudinal electrode is d1, the thickness of the ZnO seed layer of the device is d2, and the thickness of the Ti / Au electrode layer of the device is d3, and the requirement is d3>d1>d2, and the thickness range is 150nm

[0013] The application also provides a manufacturing method of a readout electrode structure process based on a zinc oxide ultraviolet detector device array.

[0014] Step 1: after the glass substrate is cleaned, a required pattern is obtained by using a photolithography method;

[0015] Step 2: a longitudinal electrode is obtained by sputtering Ti / Au by using a magnetron sputtering method;

[0016] Step 3: the photoresist is removed by using a stripping process, and a longitudinal electrode with a required shape is obtained;

[0017] Step 4: an adhesion layer is obtained by sputtering Ti by using a magnetron sputtering method;

[0018] Step 5: removing photoresist by using stripping process to obtain an adhesive layer with a desired shape;

[0019] Step 6: sputtering SiO2 by using PECVD method to obtain an isolation layer;

[0020] Step 7: removing excess SiO2 by using wet etching process to obtain an isolation layer with a desired shape;

[0021] Step 8: sputtering Ti / Au by using magnetron sputtering method to obtain a lateral electrode;

[0022] Step 9: removing photoresist by using stripping process to obtain a lateral electrode with a desired shape, thereby forming a readout electrode structure;

[0023] Step 10: testing the readout electrode structure to ensure that there is no crosstalk between the readout electrodes and the like;

[0024] Step 11: sputtering ZnO thin film and Ti / Au by using magnetron sputtering method to obtain a device structure;

[0025] Step 12: removing photoresist by using stripping process to obtain a ZnO seed layer with a desired shape and an electrode to form a device structure;

[0026] Step 13: floating the sample pattern downward in the prepared culture solution to grow ZnO nanowires by using hydrothermal method;

[0027] Step 14: linking peripheral circuit and testing the performance of the obtained detector array by using test equipment.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] The present application proposes requirements for the design of a readout electrode structure based on a device array, and specifies parameters such as etching time of an isolation layer, thickness of a seed layer of a device, thickness of an electrode layer of a device, and thickness of an electrode of a readout electrode, so that crosstalk between signals of each device can be avoided, stable connection between a device and an electrode can be achieved, isolation between hierarchical electrodes can be achieved, and a stable readout electrode structure can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A lateral ZnO nanowire ultraviolet detector array readout electrode structure and a partial area amplification schematic diagram of the present application

[0031] Figure 2 A cross-sectional view of an isolation layer of the present application

[0032] Figure 3 A cross-sectional view of an excessively etched isolation layer of the present application

[0033] Figure 4Cross-sectional view of the hole-containing isolation layer of the present application

[0034] Figure 5 Repairing diagram of the hole-containing isolation layer of the present application

[0035] Figure 6 Cross-sectional view of the intersection area between the device array and the longitudinal electrode of the present application (the dotted line is the position of the cross-section)

[0036] Figure 7 Cross-sectional view of the intersection area between the required device array and the longitudinal electrode of the present application

[0037] Figure 8 Preparation flow chart of the ultraviolet detector array of the present application

[0038] Figure 9 Partial area light microscope view of the finished ultraviolet detector array provided by Example 1 of the present application

[0039] Figure 10 Schematic diagram of the ultraviolet detector array linked to the peripheral circuit and tested provided by Example 1 of the present application

[0040] Figure 11 Device test performance chart (light-dark current contrast chart) provided by Example 1 of the present application DETAILED DESCRIPTION

[0041] The present application will be further described below in conjunction with examples, but the present application is not limited to the following examples. The present application provides a stable manufacturing process of a readout electrode structure of a detector array, which is exemplarily verified by a ZnO nanowire ultraviolet detector. The preparation flow is shown in Figure 8 The present application provides a stable manufacturing process of a readout electrode structure of a detector array, which is exemplarily verified by a ZnO nanowire ultraviolet detector. The preparation flow is shown in

[0042] The present application also provides a manufacturing method of a readout electrode structure process based on a zinc oxide ultraviolet detector array, which adopts the following technical scheme and includes the following steps:

[0043] Step 1: After cleaning the glass substrate, the required pattern is obtained by using photolithography;

[0044] Step 2: sputter Ti / Au to get longitudinal electrodes by magnetron sputtering;

[0045] Step 3: remove photoresist by stripping process to get longitudinal electrodes with desired shape;

[0046] Step 4: sputter Ti to get adhesion layer by magnetron sputtering;

[0047] Step 5: remove photoresist by stripping process to get adhesion layer with desired shape;

[0048] Step 6: sputter SiO2 to get isolation layer by PECVD;

[0049] Step 7: remove excess SiO2 by wet etching process to get isolation layer with desired shape;

[0050] Step 8: sputter Ti / Au to get transverse electrodes by magnetron sputtering;

[0051] Step 9: remove photoresist by stripping process to get transverse electrodes with desired shape, thereby forming readout electrode structure;

[0052] Step 10: test readout electrode structure to ensure that there is no crosstalk between readout electrodes and other problems;

[0053] Step 11: sputter ZnO thin film and Ti / Au to get device structure by magnetron sputtering;

[0054] Step 12: remove photoresist by stripping process to get ZnO seed layer and electrode with desired shape, thereby forming device structure;

[0055] Step 13: float sample pattern face down in prepared culture solution, and grow ZnO nanowires by hydrothermal method;

[0056] Step 14: link peripheral circuit, and test performance of obtained detector array by test equipment.

[0057] The magnetron sputtering power is preferably 150W-250W;

[0058] The solution used for growing ZnO nanowires by hydrothermal method is a culture solution composed of zinc salt and hexamethylene tetramine, and the molar ratio of corresponding reagents is 1:1-1:2;

[0059] The preferred concentration of zinc salt in the culture solution is 0.5-1mmol, and the preferred concentration of hexamethylene tetramine is 0.5-2mmol;

[0060] The preferred temperature of the hydrothermal reaction is 70-90 degrees Celsius, and the duration is 7-15 hours.

[0061] Example 1

[0062] Glass sheet is used as substrate, and the substrate is cleaned with acetone, ethanol and deionized water for two times respectively. The pattern of the required readout electrode structure is photoetched on the substrate by using ultraviolet photoetching technology.

[0063] The 15 / 150 nm Ti / Au is sputtered on the photoetched pattern as longitudinal electrode by using radio frequency magnetron sputtering method. It is noted that the sputtering target needs to be rotated and tilted by 60 degrees. The photoresist on the substrate is stripped by acetone immersion ultrasonic stripping, and only the required longitudinal electrode shape is left.

[0064] The 15 nm Ti is sputtered on the photoetched pattern as adhesion layer by using radio frequency magnetron sputtering method. It is noted that the sputtering target needs to be rotated and tilted by 60 degrees. The photoresist on the substrate is stripped by acetone immersion ultrasonic stripping, and only the required adhesion layer shape is left.

[0065] The 300 nm SiO2 is sputtered on the substrate at this time by using PECVD, and the excess SiO2 is etched by wet etching, leaving the SiO2 film on the adhesion layer and larger than the adhesion layer as an isolation layer.

[0066] The 15 / 150 nm Ti / Au is sputtered on the photoetched pattern as transverse electrode by using radio frequency magnetron sputtering method. It is noted that the sputtering target needs to be rotated and tilted by 60 degrees. The photoresist on the substrate is stripped by acetone immersion ultrasonic stripping, and only the required transverse electrode shape is left.

[0067] The readout electrode structure is tested to ensure the isolation effect of the isolation layer.

[0068] The 100 nm zinc oxide seed layer and 15 / 200 nm electrode are sputtered on the photoetched pattern respectively by using radio frequency magnetron sputtering method. It is noted that the sputtering target needs to be rotated and tilted by 60 degrees. The photoresist on the substrate is stripped by acetone immersion ultrasonic stripping, and only the required probe device shape is left.

[0069] Zinc nitrate hexahydrate and hexamethylenetetramine are selected to configure the nanowire culture solution in a ratio of 1:1, 1 mmol and 1 mmol are dissolved in 1 L deionized water respectively, and the magnetic stirring rod is used for stirring for 2 hours.

[0070] The prepared nanowire culture solution is poured into a container, the patterned SiO2 substrate is placed in the culture solution with the patterned surface facing down, and is placed in a constant temperature box for growth at 80℃ for 8 hours to grow nanowires and form a complete probe array structure, as shown in Figure 9

[0071] ​The peripheral circuit is linked, the performance of the detector device array is tested, a Keithley 4200 semiconductor parameter tester is used, a Faraday dark box and a probe station are connected, and the probe is linked to the readout electrode port of the device array to test, as shown in Figure 10 The test uses a 365nm wavelength 10mw / cm 2 UV lamp, the test voltage is -1.0V to 1.0V, the dark current and the photocurrent are tested respectively, the dark current of the device is 2.20E-5, the photocurrent is 7.07E-3, and the test result is as shown in Figure 11 .

Claims

1. A lateral ZnO nanowire UV detector array readout electrode structure, characterized in that, The structure comprises: a longitudinal electrode (101), an adhesion layer (102), an isolation layer (103), a transverse electrode (104), and a device array structure (105) composed of ZnO / Ti / Au; the isolation layer is SiO2; A plurality of strip-shaped, parallel, and independent Ti / Au films are deposited on the substrate as the longitudinal electrode (101), and a block-shaped Ti layer is deposited on part of the longitudinal electrode as the adhesion layer (102); the isolation layer (103) and the longitudinal electrode (101) completely cover the adhesion layer (102); a plurality of strip-shaped, parallel, and independent Ti / Au films are deposited on the substrate as the transverse electrode (104), which is perpendicular to the longitudinal electrode; the transverse electrode (104) is stacked on the longitudinal electrode (101) to form a complete readout electrode structure; the longitudinal electrode (101) and the transverse electrode (104) form a grid structure, and the stacked adhesion layer (102) and the isolation layer (103) are arranged between the longitudinal electrode (101) and the transverse electrode (104); A ZnO ultraviolet detector array is prepared on the readout electrode structure, and one ZnO ultraviolet detector is prepared in each grid formed by the longitudinal electrode (101) and the transverse electrode (104), or ZnO ultraviolet detectors are prepared in different grids as needed; The ZnO ultraviolet detector comprises: two parallel, symmetrical, and independent ZnO film layers are deposited as seed layers, one seed layer is parallel to and connected to the longitudinal electrode, and the other seed layer is perpendicular to the transverse electrode, and the transverse electrode is provided with a side protrusion or extension to connect and contact the other seed layer; a metal ultraviolet detector electrode layer is deposited on the ZnO seed layer; ZnO nanowires are grown on the opposite sides of the ZnO seed layer to form a complete bridging ZnO nanowire ultraviolet detector array structure.

2. The readout electrode structure of a cross-plane ZnO nanowire UV detector array according to claim 1, wherein, The thickness of the longitudinal electrode is d1, the thickness of the ZnO seed layer of the ultraviolet detector is d2, and the thickness of the ultraviolet detector electrode layer is d3, and it is required that d3>d1>d2, and the thickness range is 150nm 3. The readout electrode structure of a cross-plane ZnO nanowire UV detector array according to claim 1, wherein, The ultraviolet detector electrode layer is Ti / Au.

4. The method for fabricating a readout electrode structure of a crosswise ZnO nanowire UV detector array according to any one of claims 1-3, characterized in that, The method comprises the following steps: Step 1: After the glass substrate is cleaned, a required pattern is obtained by using photolithography; Step 2: A longitudinal electrode is obtained by sputtering Ti / Au by using a magnetron sputtering method; Step 3: The photoresist is removed by using a stripping process to obtain a longitudinal electrode with a required shape; Step 4: An adhesion layer is obtained by sputtering Ti by using a magnetron sputtering method; Step 5: The photoresist is removed by using a stripping process to obtain an adhesion layer with a required shape; Step 6: An isolation layer is obtained by sputtering SiO2 by using a PECVD method; Step 7: The excess SiO2 is removed by using a wet etching process to obtain an isolation layer with a required shape; Step 8: A transverse electrode is obtained by sputtering Ti / Au by using a magnetron sputtering method; Step 9: removing photoresist by stripping process to obtain transverse electrode with desired shape, and then forming readout electrode structure; Step 10: testing readout electrode structure to ensure that there is no crosstalk problem between readout electrodes; Step 11: sputtering ZnO seed layer and ultraviolet detector electrode layer by magnetron sputtering method to obtain device structure; Step 12: removing photoresist by stripping process to obtain ZnO seed layer and electrode with desired shape to form device structure; Step 13: floating sample pattern downward in prepared culture solution to grow ZnO nanowire by hydrothermal method.

5. The method of claim 4, wherein, Step 10 tests the readout electrode structure, including: 1v voltage test, when the current is 0, the isolation effect of the isolation layer is the best, and the isolation effect is judged according to the current size.

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