LED用GaAs抛光片清洗技术研究

Research on Cleaning Process of GaAs Polished Wafer for LED

伴随着LED照明产业的迅猛发展,高质量的GaAs抛光片需求量日益增大。研究了一种有效的直径5.08cm低阻GaAs免洗抛光片的清洗技术,采用异丙醇低温超声去蜡结合兆声湿法清洗工艺,使晶片表面达到了低表面颗粒度、极低表面金属离子浓度,并形成了较薄的富As氧化层表面。表面颗粒度通过Tencor6220测试大于0.3μm的颗粒少于10个,通过TXRF测试表面金属离子个数均控制在9×1010/cm2以内;通过台阶仪测量表面粗糙度为0.8nm,通过偏振光椭圆率测量仪测得均一的2nm厚表面氧化层。

With the quick development of LED industry, high quality of GaAs polished wafers are demanded increasingly. An effective cleaning process of 5.08 cm GaAs wafer with lower resistance was investigated. Isopropyl alcohol ultrasonic cleaning was used to remove the backside wax. Wet chemical megasonics cleaning was used to remove particulate and metallic contaminants for controlling the components of oxide layer. The particle-free, metal-free and thin As rich surface were achieved. Particulate contamination is tested by Tencor6220, the particle counts greater than 0.3 μm are less than 10. Metal contamination is analyzed by total reflection X-ray fluorescence spectroscopy, the concentration of metal contaminants is within 9 ×10^10/cm^2. Surface morphology and thickness of oxide layer are observed by Tencor-AS-500 and ellipsometer, which show very flat surface roughness of 0.8 nm, and uniform oxide thickness is about 2 nm respectively.