LED用图形化蓝宝石衬底的干法刻蚀工艺

Dry Etching Process of the Patterned Sapphire Substrate for LED

近年来,图形化蓝宝石衬底(PSS)作为GaN基LED外延衬底材料被广泛应用。采用感应耦合等离子体(ICP)技术对涂覆有光刻胶阵列图案的蓝宝石衬底进行刻蚀。通过研究及优化不同ICP刻蚀工艺参数对刻蚀速率和选择比的影响,分别成功制备出蒙古包形和圆锥形图形化蓝宝石衬底片,并在其表面完成InGaN/GaN多量子阱外延及芯片工艺。借助光致发光和电致发光等手段测试其LED器件的光电学性能。实验结果发现圆锥形的图形化蓝宝石衬底拥有更强的光功率和更窄的半峰宽,说明这种形貌的衬底在GaN外延时有效减少了晶格失配造成的缺陷,提高了晶体质量,从而更有效地增加LED出光效率。

In recent years, the patterned sapphire substrate （PSS） have been widely applied as the epitaxial substrate material for GaN-based LED. Using the inductively coupled plasma （ICP） technology, the sapphire substrate with photoresist pattern array was etched. By studying and optimizing the effects of different ICP process parameters on the etch rate and selectivity, the dome-and cone-shaped patterned sapphire substrates were prepared successfully, and epitaxial growth of the InGaN/GaN multiple-quantum well on the surface of the PSS and the chip process were completed. The photoelectronic properties of the LED chips were tested by photolumines- cence （PL） and electroluminescence （EL） methods. The experimental results show that the light output power and full width at half maximum （FWHM） of the cone-shaped PSS is better than those of the dome one, showing that in the process of epitaxial growth, the cone-shaped PSS can effectively reduce the lattice mismatch defects and improve the crystal quality, and then in- crease the LED luminous efficiency.