掺Ge氧化硅薄膜波导制备工艺与应力研究
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摘要
采用等离子体化学气相沉积法在硅基底上沉积氧化硅薄膜,研究在不同工艺条件下薄膜的应力变化情况和折射率分布规律.利用应力测试仪测定晶圆在镀膜前后的形变量进而获得应力值,并用棱镜耦合仪测试薄膜折射率.在其他条件相同的情况下,SiH_4与N_2O的流量比分别设为24、27.6和30时,在1 539nm波长下薄膜平均折射率分别为1.466 7、1.459 2和1.455 7,对应的晶圆应力向着压应力增加,分别为-50MPa、-200MPa和-430MPa.掺入8.3×10~(-7) m~3/s GeH_4后,SiH_4与N_2O的流量比分别设为22.6、24和27.6时,薄膜平均折射率分别为1.475 8、1.471 4和1.463 3,对应的晶圆应力分别为25MPa、-210MPa和-270 MPa,是从拉应力向压应力变化的过程.结果表明,SiH_4与N_2O的流量比相同时,掺入GeH_4后折射率和对应的压应力明显增加.因此,通过对工艺条件的合理选择,可制备出折射率稳定的氧化硅波导薄膜,从而提高器件在整个晶片上的成品率.
Silica films were deposited on a silicon substrate by aplasma enhanced chemical vapor deposition method to study the stress variation and the refractive index distribution at different process conditions.The stress tester was used to measure the deformation of the wafer before and after coating,allowing the calculation of the film stress,and the prism coupler was used to measure the refractive index distribution.Under the same condition,when the flow ratio of SiH_4 to N_2O is set to 24,27.6 and 30,the average refractive index of the film are 1.466 7,1.459 2 and 1.455 7,respectively,at the wavelength of 1 539 nm,and the correspoonding compressive stress of the film are-50 MPa,-200 MPa,and-430 MPa,respectively.When the flow ratio of SiH_4 to N_2O is set to 22.6,24,and 27.6 after minxing 8.3×10-7 m3/s GeH_4,the average refractive indices are 1.4758,1.4714 and 1.4633,respectively,and the corresponding wafer stresses are 25 MPa,-210 MPa and-270 MPa,respectively,which is a changing process from the tensile stress to the compressive stress.The result show that at the same flow ratio of SiH_4 to N_2O,GeH_4 diffusion increases the refractive index and the compressive stress of the film.It turns out that with the reasonable selection of the process conditions,a refractive index stabilized silicon oxide waveguide film can be prepared,thereby improving the yield of the device over the entire wafer.
Silica films were deposited on a silicon substrate by aplasma enhanced chemical vapor deposition method to study the stress variation and the refractive index distribution at different process conditions.The stress tester was used to measure the deformation of the wafer before and after coating,allowing the calculation of the film stress,and the prism coupler was used to measure the refractive index distribution.Under the same condition,when the flow ratio of SiH_4 to N_2O is set to 24,27.6 and 30,the average refractive index of the film are 1.466 7,1.459 2 and 1.455 7,respectively,at the wavelength of 1 539 nm,and the correspoonding compressive stress of the film are-50 MPa,-200 MPa,and-430 MPa,respectively.When the flow ratio of SiH_4 to N_2O is set to 22.6,24,and 27.6 after minxing 8.3×10-7 m3/s GeH_4,the average refractive indices are 1.4758,1.4714 and 1.4633,respectively,and the corresponding wafer stresses are 25 MPa,-210 MPa and-270 MPa,respectively,which is a changing process from the tensile stress to the compressive stress.The result show that at the same flow ratio of SiH_4 to N_2O,GeH_4 diffusion increases the refractive index and the compressive stress of the film.It turns out that with the reasonable selection of the process conditions,a refractive index stabilized silicon oxide waveguide film can be prepared,thereby improving the yield of the device over the entire wafer.
引文
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[15] FENG Hang.Study the key process of microphotonic integrated chip[D].Changchun:Changchun University of Science and Technology of China,2014:36-40.冯航.微光子集成芯片的关键工艺研究[D].长春:长春理工大学,2014:36-40.
[16] TAMULEVICIUS.Stress and strain in the vacuum deposited thin films[J].Vacuum,1998,51(2):127-139.
[2] ZHAO Fei,YANG Wen,MO Jing-hui,et al.Influence of pulse sputtering power on the structural and optical properties of SiCxthin films containing silicon quantum dots[J].Acta Photonica Sinica,2017,46(12):1231002.赵飞,杨雯,莫镜辉,等.脉冲溅射功率对含硅量子点SiCx薄膜的结构和光学特性的影响[J].光子学报,2017,46(12):1231002.
[3] HUANG M.Analytical solutions for thermal stresses in buried channelwaveguides[J].IEEE Journal of Quantum Electronics,2004,40(11):1562-1568.
[4] CHASON E,KARLSON M,COLIN J,et al.A kinetic model for stress generation in thin films grown from energetic vapor fluxes[J].Journal of Applied Physics,2016,119:145307.
[5] SUN De-gui,SUN Qing-yu,XING Wen-chao,et al.Investigation for the structural stress of SiO2thin films and its distribution on the large-wafer created by plasma enhanced chemical vapor deposition[J].AIP Advances,2018,8(8):085217.
[6] ZHANG Le-tian,WU Yuan-da,XING Hua,et al.Fabrication of Si-based silica waveguide material applied in AWG[J].Journal of Optoelectonics·Laser,2012,13(8):868-871.张乐天,吴远大,邢华,等.AWG用Si基SiO2波导材料的制备[J].光电子·激光,2012,13(8):868-871.
[7] PAN Yong-qiang.Properties of silicon nitride films deposited by radio frequency plasma enhanced chemical vapor deposition[J].Acta Photonica Sinica,2007,36(6):1097-1101.潘永强.射频等离子体增强化学气相沉积SiNx薄膜的研究[J].光子学报,2007,36(6):1097-1101.
[8] SHAO Shu-ying,TIAN Guang-lei,FAN Zheng-xiu,et al.Influences of the deposition parameters and aging time on the residual stress of SiO2films[J].Acta Optica Sinica,2005,25(1):126-130.邵淑英,田光磊,范正修,等.沉积参量及时效时间对SiO2薄膜残余应力的影响[J].光学学报,2005,25(1):126-130.
[9] SHEN Yan-ming,HE Hong-bo,SHAO Shu-ying,et al.Influences of deposition temperature on residual stress of HfO2films prepared by electron beam evaporation[J].Chinese Journal of Lasers,2006,33(6):827-831.申雁鸣,贺洪波,邵淑英,等.沉积温度对电子束蒸发HfO2薄膜残余应力的影响[J].中国激光,2006,33(6):827-831.
[10] LUO Hai-han,CAI Qing-yuan,LI Yao-peng,et al.Study on the optical characteristic of silicon dioxide thin films deposited in different temperatures[J].Acta Optica Sinica,2014,34(s2):s231001.罗海翰,蔡清元,李耀鹏,等.不同沉积温度下单纯蒸镀二氧化硅薄膜的光学特性研究[J].光学学报,2014,34(s2):s231001.
[11] GUAN D,BRUCCOLERI A,HEILMANN R,et al.Stress control of plasma enhanced chemical vapor deposited silicon oxide film from tetraethoxysilane[J].Journal of Micromechanics and Microengineering,2013,24(2):027001.
[12] PERALTA L,BERNUSSI A,TEMKIN H,et al.Silicon-dioxide waveguides with low birefringence[J].IEEE Journal of Quantum Electronics,2003,39(7):874-879.
[13] TUYAERTS R,PONCELET O,RASKIN J,et al.Internal stress and opto-electronic properties of ZnO thin films deposited by reactive sputtering in various oxygen partial pressures[J].Journal of Applied Physics,2017,122:155306.
[14] ZHOU Li-bin.Silica-on-silicon array waveguides gratings[D].Wuhan:Huazhong University of Science and Technology of China,2005:103-116.周立兵.硅基二氧化硅型阵列波导光栅的研制[D].武汉:华中科技大学,2005:103-116.
[15] FENG Hang.Study the key process of microphotonic integrated chip[D].Changchun:Changchun University of Science and Technology of China,2014:36-40.冯航.微光子集成芯片的关键工艺研究[D].长春:长春理工大学,2014:36-40.
[16] TAMULEVICIUS.Stress and strain in the vacuum deposited thin films[J].Vacuum,1998,51(2):127-139.