Etching mask optimization of InAs/GaSb superlattice mid-wavelength infared 640×512 focal plane array

• Published in: Chinese physics B 2017-04, Vol.26 (4), p.411-414
• Main Author: 郝宏玥 向伟 王国伟 徐应强 韩玺 孙瑶耀 蒋洞微 张宇 廖永平 魏思航 牛智川
• Format: Article
• Language: English
• Subjects: ICP刻蚀; 中波; 优化; 掩模技术; 电感耦合等离子体; 红外焦平面阵列; 蚀刻; 超晶格
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/26/4/047303

In this paper we focused on the mask technology of inductively coupled plasma（ICP） etching for the mesa fabrication of infrared focal plane arrays（FPA）.By using the SiO_2 mask,the mesa has higher graphics transfer accuracy and creates less micro-ripples in sidewalls.Comparing the IV characterization of detectors by using two different masks,the detector using the SiO_2 hard mask has the R_0A of 9.7×10~6 Ω·cm~2,while the detector using the photoresist mask has the R_0A of3.2 × 10~2 Ω·cm~2 in 77 K.After that we focused on the method of removing the remaining SiO_2 after mesa etching.The dry ICP etching and chemical buffer oxide etcher（BOE） based on HF and NH4 F are used in this part.Detectors using BOE only have closer R_0A to that using the combining method,but it leads to gaps on mesas because of the corrosion on AlSb layer by BOE.We finally choose the combining method and fabricated the 640×512 FPA.The FPA with cutoff wavelength of 4.8 μm has the average R_0A of 6.13 × 10~9 Ω·cm~2 and the average detectivity of 4.51 × 10~9 cm·Hz~（1/2）.W~（-1）at 77 K.The FPA has good uniformity with the bad dots rate of 1.21%and the noise equivalent temperature difference（NEDT） of 22.9 mK operating at 77 K.