Rapid annealing heat treatment method for optimizing contact between p-GaN and ITO in Micro-LED device

Abstract

The invention discloses a rapid annealing heat treatment method for optimizing contact between p-GaN and ITO (Indium Tin Oxide) in a Micro-LED (Light Emitting Diode) device. According to the method, rapid heat treatment (RTP) is carried out in a specific atmosphere, and annealing is carried out at 550 DEG C for 1 minute and 5 minutes respectively, so that the contact performance between p-GaN and ITO is improved. Experimental results show that the current density of a single Micro-LED pixel reaches 0.4624 A / cm < 2 > and the light transmittance is 80.33% when annealing is carried out for 1 minute in an O2 atmosphere. Under the optimized RTP annealing condition, the forward turn-on voltage of a single pixel of the blue light Micro-LED is about 3V, the peak value of the emission wavelength is 449.87 nm, the dominant wavelength is 455.11 nm, and the half width is 17.75 nm. The side wall of a single pixel shows a good appearance after RTP optimization, and no ITO chippings are attached, which indicates that the method effectively reduces the problems of side wall damage and electric leakage channel caused by ITO etching.

Description

Technical Field

[0001] The present invention relates to an annealing contact optimization method based on ITO (indium tin oxide) and p-type gallium nitride (p-GaN) during the preparation process of a Micro-LED device P electrode, so as to improve the photoelectric performance thereof. Background Art

[0002] Micro-LED technology has high brightness, high reliability and nanosecond response time, but it faces many challenges in the manufacturing process. In particular, achieving excellent p-type electrode contact is a key issue in the current manufacture of Micro-LED devices. In conventional processes, ITO needs to be selectively etched after being deposited at high temperature, which can cause ITO debris to adhere to the GaN sidewalls, leading to current leakage and even short circuit problems. ITO grown at room temperature can avoid this problem through annealing and subsequent removal processes, but post-process high-temperature annealing is still required to optimize the P-type contact effect to further optimize the device's optoelectronic performance. Summary of the invention

[0003] Purpose of the invention: The present invention aims to provide a rapid thermal treatment method for optimizing the ohmic contact between ITO and p-GaN to improve the electrical performance of Micro-LED devices.

[0004] Technical solution: The rapid thermal treatment method for optimizing the contact between p-GaN and ITO in Micro-LED devices described in the present invention is specifically: depositing an ITO film on p-GaN by electron beam evaporation, and then performing rapid thermal treatment (RTP) in an oxygen or nitrogen atmosphere, and annealing at 550°C for 1 to 5 minutes.

[0005] When annealed in an O2 atmosphere for 1 minute, the current density of a single Micro-LED pixel is 0.4624A / cm 2 , the transmittance is 80.33%.

[0006] Among them, the steps of the rapid annealing process include: the first step, increasing the atmosphere gas flow rate in the annealing furnace to 10SCPM; the second step, heating the annealing furnace to 200°C and maintaining the N2 rate at 4SCPM; the third step, gradually heating the annealing furnace to 550°C and maintaining it for 1 minute to 5 minutes to complete the annealing procedure; the fourth step, cooling the annealing furnace, maintaining the N2 gas flow rate at 10SCPM for 3 minutes, and completing the annealing process after the temperature in the furnace drops below 130°C.

[0007] The specific procedure of the rapid thermal treatment includes gas pressurization, heating and cooling steps to ensure the stability and effectiveness of the annealing process.

[0008] Wherein, the thickness of the ITO film is 75nm.

[0009] Under optimized RTP annealing conditions, a single pixel of the blue light Micro-LED has a forward turn-on voltage of approximately 3V, a peak emission wavelength of 449.87nm, a main wavelength of 455.11nm, and a half-width of 17.75nm.

[0010] The sidewall of the single pixel shows a good appearance after RTP optimization, and no ITO debris is attached, indicating that this method effectively reduces the sidewall damage and leakage channel problems caused by ITO etching.

[0011] The principle of the present invention is: by performing RTP annealing in an oxygen atmosphere to fill the oxygen vacancies and defects in the ITO film, a more stable material ratio of InO3 to SnO2 is formed of about 9:1, which significantly improves its conductivity. At the same time, oxygen reacts with the Mg-H complex to increase the hole concentration in p-GaN, further improving the ohmic contact performance. During the high-temperature short-time treatment process, the doping and defects inside the material are activated, and the redistribution of carriers enhances the interface conductivity. In addition, in the case of annealing in a nitrogen atmosphere, the low-oxygen environment reduces the formation of oxides, keeps the interface clean, and helps to optimize the contact performance. However, the annealing temperature must be carefully controlled to prevent separation between InO3 / SnO2 and p-GaN and avoid increased contact resistance due to high temperature. Therefore, the present invention provides a significant improvement in electrical performance for Micro-LED devices by effectively repairing defects, enhancing hole conductivity, and controlling interface reactions under optimized RTP annealing conditions.

[0012] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention adopts the ITO solution grown at room temperature to achieve metal-semiconductor contact. By optimizing the annealing process to connect the subsequent process steps, the problems of poor metal-semiconductor contact and leakage channels caused by high-temperature growth can be avoided. By optimizing the RTP annealing conditions, the electrical properties of the Micro-LED device are significantly improved, especially in terms of current density and transmittance. At the same time, the method achieves good ohmic contact by effectively filling oxygen vacancies and enhancing hole conductivity, ensuring the stability and reliability of the Micro-LED device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the electrical performance IV curve of the blue light Micro-LED array after preparation in Example 1;

[0014] Figure 2 This is the luminescence spectrum of the blue light Micro-LED array in Example 1 after preparation under EL test with a current of 15mA;

[0015] Figure 3 15×15 μm as described in Example 12 Pixel SEM electron microscope morphology;

[0016] Figure 4 The diagrams are of the luminescence of the array after annealing is completed, wherein (a)-(d) are diagrams of the luminescence of the array after annealing is completed in Examples 1-4, respectively. DETAILED DESCRIPTION

[0017] Example 1

[0018] The present invention is a rapid heat treatment method for optimizing the contact between p-GaN and ITO in a Micro-LED device, which specifically comprises the following steps:

[0019] (1) Place a small sample with a 75 nm ITO thin film as the P electrode metal deposited at room temperature by electron beam evaporation on an 8-inch annealing silicon wafer pad, and then place them together in an RTP rapid annealing furnace for annealing;

[0020] (2) Operate the annealing furnace to prepare for the experimental process of gas pressurization and temperature increase, and continuously maintain the annealing temperature at 550°C. The specific procedures are as follows: Step 1, execute the gas flow delay program for 1 minute, increase the O2 gas flow rate to 10SCPM (standard cubic centimeters per minute), and create an oxygen atmosphere; Step 2, execute a rapid temperature increase to 200°C, and maintain the O2 rate at 4SCPM; Step 3, gradually increase the temperature to 550°C and maintain for 1 minute to complete the annealing program; Step 4, execute the cooling program, maintain the O2 gas flow rate at 10SCPM for 3 minutes, and wait for cooling. After the temperature in the furnace drops below 130°C, you can end the program and open the furnace door. After cooling, take out the sample to complete the annealing process;

[0021] (3) The electrical performance of the pixels after annealing was tested using a probe station. Combining the measured current and pixel size, the current density under the annealing condition was calculated to be 0.4624 A / cm 2 The transmittance of ITO was measured using Lambda 750 equipment, and the transmittance of ITO under the annealing condition was found to be 80.33%.

[0022] Example 2

[0023] The present invention is a rapid heat treatment method for optimizing the contact between p-GaN and ITO in a Micro-LED device, which specifically comprises the following steps:

[0024] (1) Place a small sample with a 75 nm ITO thin film as the P electrode metal deposited at room temperature by electron beam evaporation on an 8-inch annealing silicon wafer pad, and then place them together in an RTP rapid annealing furnace for annealing;

[0025] (2) In an O2 atmosphere, operate the annealing furnace to prepare for the experimental process of gas pressurization and temperature increase, and continuously maintain the annealing temperature at 550°C. The specific procedures are as follows: the first step is to execute the gas flow delay program for 1 minute and increase the O2 gas flow rate to 10SCPM; the second step is to execute a rapid temperature increase to 200°C and maintain the O2 rate at 4SCPM; the third step is to gradually increase the temperature to 550°C and maintain it for 5 minutes to complete the annealing program; the fourth step is to execute the cooling program, maintain the O2 gas flow rate at 10SCPM for 3 minutes, and wait for cooling. After the temperature in the furnace drops below 130°C, the program can be ended and the furnace door can be opened. After cooling, the sample can be taken out to complete the annealing process;

[0026] (3) The electrical performance of the pixels after annealing was tested using a probe station. Combining the measured current and pixel size, the current density under the annealing condition was calculated to be 0.2431 A / cm 2 The transmittance of ITO was measured using Lambda 750 equipment, and the transmittance of ITO under the annealing condition was 78.91%.

[0027] Example 3

[0028] The present invention is a rapid heat treatment method for optimizing the contact between p-GaN and ITO in a Micro-LED device, which specifically comprises the following steps:

[0029] (1) Place a small sample with a 75 nm ITO thin film as the P electrode metal deposited at room temperature by electron beam evaporation on an 8-inch annealing silicon wafer pad, and then place them together in an RTP rapid annealing furnace for annealing;

[0030] (2) In N2 atmosphere, operate the annealing furnace to prepare for the experimental process of gas pressurization and temperature increase, and continuously maintain the annealing temperature at 550°C. The specific procedures are as follows: the first step is to execute the gas flow delay program for 1 minute and increase the N2 gas flow rate to 10SCPM; the second step is to execute a rapid temperature increase to 200°C and maintain the N2 rate at 4SCPM; the third step is to gradually increase the temperature to 550°C and maintain it for 1 minute to complete the annealing program; the fourth step is to execute the cooling program, maintain the N2 gas flow rate at 10SCPM for 3 minutes, and wait for cooling. After the temperature in the furnace drops below 130°C, the program can be ended and the furnace door can be opened. After cooling, the sample can be taken out to complete the annealing process;

[0031] (3) Use a probe station to test the electrical performance of the annealed pixel. Combined with the measured current and pixel size, the current density under the annealing condition is calculated to be 0.016 A / cm 2 The ITO transmittance was measured using Lambda 750 equipment, and the ITO transmittance under the annealing condition was 78.05%.

[0032] Example 4

[0033] The present invention is a rapid heat treatment method for optimizing the contact between p-GaN and ITO in a Micro-LED device, which specifically comprises the following steps:

[0034] (1) Place a small sample with a 75 nm ITO thin film as the P electrode metal deposited at room temperature by electron beam evaporation on an 8-inch annealing silicon wafer pad, and then place them together in an RTP rapid annealing furnace for annealing;

[0035] (2) In N2 atmosphere, operate the annealing furnace to prepare for the experimental process of gas pressurization and temperature increase, and continuously maintain the annealing temperature at 550°C. The specific procedures are as follows: the first step is to execute the gas flow delay program for 1 minute and increase the N2 gas flow rate to 10SCPM; the second step is to execute a rapid temperature increase to 200°C and maintain the N2 rate at 4SCPM; the third step is to gradually increase the temperature to 550°C and maintain it for 5 minutes to complete the annealing program; the fourth step is to execute the cooling program, maintain the N2 gas flow rate at 10SCPM for 3 minutes, and wait for cooling. After the temperature in the furnace drops below 130°C, the program can be ended and the furnace door can be opened. After cooling, the sample can be taken out to complete the annealing process;

[0036] (3) The electrical performance of the pixels after annealing was tested using a probe station. Combining the measured current and pixel size, the current density under the annealing condition was calculated to be 0.0098 A / cm 2 The transmittance of ITO was measured using Lambda 750 equipment, and the transmittance of ITO under the annealing condition was 77.07%.

Claims

1. A rapid annealing heat treatment method for optimizing the contact between p-GaN and ITO in Micro-LED devices, characterized in that: An ITO film is deposited on a p-GaN epitaxial wafer at room temperature using an electron beam evaporation method, and then the p-GaN epitaxial wafer is annealed using a rapid annealing process.

2. The rapid annealing heat treatment method according to claim 1, characterized in that: The atmosphere of the rapid annealing process is O2 or N2.

3. The rapid annealing heat treatment method according to claim 1, characterized in that: In the rapid annealing process, the annealing temperature is 550° C., and the annealing time is 1 minute to 5 minutes.

4. The rapid annealing heat treatment method according to claim 1, characterized in that: The steps of the rapid annealing process include: the first step is to increase the atmosphere gas flow rate in the annealing furnace to 10SCPM; the second step is to heat the annealing furnace to 200°C and maintain the N2 rate at 4SCPM; the third step is to gradually heat the annealing furnace to 550°C and maintain it for 1 minute to 5 minutes to complete the annealing procedure; the fourth step is to cool the annealing furnace and maintain the N2 gas flow rate at 10SCPM for 3 minutes, and the annealing process is completed after the temperature in the furnace drops below 130°C.

5. The rapid annealing heat treatment method according to claim 1, characterized in that: The rapid annealing process includes annealing at 550° C. for 1 minute in an O 2 atmosphere.

6. A method for preparing a Micro-LED device, characterized in that: The rapid annealing heat treatment method according to any one of claims 1 to 5 is adopted.

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