HV AC-LED的制作工艺及结温测试

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HV/AC-LED 的制作工艺及结温测试

摘要

目前应用于照明的 LED 主要由低压直流驱动，这种驱动器有其固有弊端：驱

动器的成本高，尺寸大、电路复杂、不稳定。随着 LED 芯片技术的发展以及

LED 模具可靠性的提高，LED 器件中的转换器逐渐成为系统设计的瓶颈。使用高

压驱动的 HV-LED 或直接使用交流电驱动的 AC-LED 有更高效率、更高可靠性和

更低成本等优势。

第一部分，重新审视现有高功率 LED 技术和 LED 的驱动方式。分析 HV-

LED 和AC-LED 的工作原理以及优势。第二部分，制作表征新型 HV-LED。论文

描述了 HV-LED 芯片制作的关键设备和工艺流程，包含对 ICP 深刻蚀、侧壁绝缘

保护、电极桥连等关键技术进行的优化。针对电流扩展效果差的问题，设计制作

了15 种不同的 p型金属电极结构，经过对比分析，选择叉指结构，可最大限度使

电流均匀分布，提高了芯片的发光效率。第三部分，针对传统 AC-LED 结温测试

方法遇到的困难，根据 AC-LED 的工作特性及结温与正向电压的关系，提出了一

种新的 AC-LED 结温测试方法--阈值电压法。

叉指结构 p型金属电极 HV-LED 的实验结果表明，这种电流扩展结构将能将

出光效率提高 12%。该做法只需修改相应步骤的掩模板，不需修改工艺步骤；不

需增加材料成本，在生产成本不变的情况下就可以提高 LED 的发光效率。使用阈

值电压法测试 AC-LED 结温，经过分析当参考阈值电流为 1mA 时,测试误差可以

降低为±2.5℃。阈值电压法测试结果比现有的测试方法为精确，应用范围更广，

更适用于工业测试。

关键词：HV-LED AC-LED 芯片制作结温测试

ABSTRACT

LEDs for lighting application are conventionally powered by Direct Current (DC)

sources with DC-DC converters or Alternating Current (AC) sources with AC-DC

converters. DC-DC converters and AC-DC converters are well understood but have

disadvantages of driver cost, size, electrical circuits’ complexity and reliability. With

the development of LEDs technology and enhancement of LEDs dies reliability, the

reliability of the converters is becoming the bottleneck of the lighting system. Direct

HV/AC powering LEDs have advantages of higher efficiency, enhanced reliability,

reduced cost and ready tore place existing lighting fixture due to the elimination of AC-

DC converter. At present, the measurement techniques of LED junction temperatures

are mainly developed for direct current LEDs (DC-LEDs). With the advent of AC-LED

technology it is essential to have a method that would be able to characterize the

junction temperature of the AC-LEDs with high efficiency and accuracy.

In the first part of this work, existing LED technologies including high power and

driver are reviewed. Advanced analysis of HV-LED and AC-LED are performed. In the

second part of this work, a fabrication and characterization of gallium nitride based HV-

LED is presented. Firstly, it is described that the key equipment and processes of HV-

LED chip production. Secondly, a fabrication process was developed for creating a GaN

HV-LED, and the key technology is optimized in deep etching of ICP, sidewall

insulation, the bridging and so on. Thirdly, 15 different p-type metal electrode structure

designed to solve the problem of the poor effect of current spreading, and through

comparative analysis the interdigital structure is selected, so that the current can be

evenly distributed to maximize and improve the luminous efficiency of the chip. In the

third part of this work, threshold voltage method of measuring alternating current LED

(AC-LED) junction temperature is reported to exhibit high efficiency and accuracy. In

this method, a threshold current Ith is first confirmed to a constant value as reference.

When AC-LED is at normal state, the selected forward voltage is instantaneous. An

AC-LED starts working when its current reaches threshold current Ith. The voltage

driving AC-LED at this moment is threshold voltage, which is found decreases along

with the junction temperature risen. Between threshold voltages and junction

temperatures, a good linear relationship is found. Temperature sensitive parameter

(TSP) between threshold voltage and junction temperature is confirmed. This method

consists of two parts, calibration measurement, and the actual junction-temperature

measurement.

Using these methods GaN based HV-LED were fabricated with new metal

electrode-interdigital structure p-type metal electrode. The light efficiency increased by

12%. In this approach, the masks of the corresponding steps are simply modified,

without modifying process steps, increasing material costs. LED luminous efficiency is

improved without extra production costs. Further analysis suggested that the error of the

threshold voltage method can be narrowed down to ±2.5 ℃ when the reference current

is chosen as ~1 mA。 It is concluded that the method of threshold voltage is accurate

and simple to implement, making it highly suitable for determining the junction

temperatures of AC-LEDs in industry.

Key Words: HV-LED, AC-LED, Fabrication of chip, Junction

Temperature Measurement

目  录
中文摘要
ABSTRACT
第一章 绪   论.......................................................1
1 LED 现状........................................................1
2 LED 的驱动方法..................................................3
3 HV-LED.........................................................4
4 AC-LED.........................................................6
5 本文的研究方向..................................................8
第二章 GaN 基 HV -LED 的制作工艺......................................10
1 氮化镓（GaN）材料..............................................10
2 关键工艺设备...................................................10
2.1 光刻 (Photo-Etching).......................................11
2.2 刻蚀(Etching)..............................................13
2.3 化学气相沉积 (Chemical Vapor Deposition；CVD)..............15
2.4 金属镀膜 (Metal Deposition)................................16
3 制作工艺流程..................................................17
4 关键技术.......................................................23
5 新型电极设计...................................................25
6 样品数据分析...................................................26
7结论...........................................................29
第三章 交流 AC-LED 的结温测试方法....................................30
1 LED 的热学参数.................................................30
1.1  结温的产生................................................30
1.2  LED 的热阻................................................31
2 结温对 LED 参数的影响...........................................31
3 LED 结温测试方法...............................................32
3.1 DC-LED 的结温测试方法......................................32
3.2 DC-LED 的结温测试方法应用到 AC-LED 结温测试当中的问题.......33
3.3 现有 AC-LED 结温测试方法....................................33
4 阈值电压法测量AC-LED 结温......................................35
4.1 结温与阈值电压的关系理论...................................35

4.2 阈值电压法中参考阈值电流的选择.............................36
4.3 阈值电压法的实验装置.......................................37
4.4 阈值电压法的流程...........................................38
4.5 数据分析...................................................39
5 结论...........................................................42
第四章 总结与展望...................................................43
1HV-LED 芯片制作.................................................43
2 阈值电压法测试 AC-LED 结温......................................43
参考文献............................................................45

第一章绪论

1.1 LED 现状

LED 即发光管二极管。它能将电能以比传统光源更高效的形式转换为光输出。

LED 用作照明具有尺寸小、寿命长、发热量低、能量效率高等的优点。LED 照明

市场近几年发展非常迅速，高功率和高亮度LED 做出了重要贡献[1]。作为光源，

LED 能源利用率高而且对环境无污染[2]。由此带来的节能效应可以减少煤炭的消

耗和温室气体的排放。图1-1 展示了一个典型的 LED 照明系统。

图1-1 LED 照明系统

典型的 LED 芯片是基于 GaN 或者AlGaInP/GaAs 半导体材料。图1-2 展

示了一个典型的 LED 封装。

图1-2 典型LED 封装

如图 1-2 所示，LED 芯片安装在子座上并且附着在基板上。基板常常由具有

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摘要：

HV/AC-LED的制作工艺及结温测试摘要目前应用于照明的LED主要由低压直流驱动，这种驱动器有其固有弊端：驱动器的成本高，尺寸大、电路复杂、不稳定。随着LED芯片技术的发展以及LED模具可靠性的提高，LED器件中的转换器逐渐成为系统设计的瓶颈。使用高压驱动的HV-LED或直接使用交流电驱动的AC-LED有更高效率、更高可靠性和更低成本等优势。第一部分，重新审视现有高功率LED技术和LED的驱动方式。分析HV-LED和AC-LED的工作原理以及优势。第二部分，制作表征新型HV-LED。论文描述了HV-LED芯片制作的关键设备和工艺流程，包含对ICP深刻蚀、侧壁绝缘保护、电极桥连等关键技术进行的...

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