蓝宝石衬底与GaN外延层中缺陷与杂质的研究
摘要
本文用化学腐蚀法对CZ法生长的φ50mm蓝宝石单晶中的位错和缺陷进行了分析研究，并采用金相显微镜和SEM对其进行了显微观察和分析。进行了不同温度、不同的试剂以及不同的腐蚀时间条件下的缺陷显示实验。发现，用熔融的KOH腐蚀剂在290℃下腐蚀15分钟时，显示的位错最为清晰、准确，效果最佳。
利用原子力显微镜(AFM)观察了蓝宝石衬底和GaN外延层中缺陷形貌以及衬底与外延之间生长界面的情况，发现在蓝宝石衬底上外延GaN，当蓝宝石中的位错密度小于10~5／cm~2时，GaN中的位错密度增值到10~8～10~9／cm~2。且GaN外延层中的位错密度与蓝宝石衬底中的位错密度没有线性关系。用扫描电镜(SEM)、XPS、电子探针和紫外荧光光谱仪测量了蓝宝石衬底和GaN外延层中的Mo杂质的含量，发现蓝宝石衬底中含有Mo杂质，含量约为10~(-4)(质量含量)；而在外延层GaN中没有检测到Mo杂质，即Mo杂质含量小于ppm级。由此可见，在目前的器件产业工艺要求下用廉价的Mo坩锅生长蓝宝石单晶是可行的。
In this paper, the dislocation in Φ50mm CZ sapphire crystal had been observed by chemical etching with metallograph and SEM. Comparing the results which were obtained when the reagent and temperature and time varied ,we found the dislocation was displayed very clearly and accurately when we etch with KOH at 290℃ for fifteen minutes,which was the best condition.
The defect and interface in sapphire and GaN were observed by AFM.We found that when the dislocation density in sapphire was lower thanl05/cm2, the dislocation density in GaN was 108~109/cm2and not linear with the dislocation in sapphire.The impurity of Mo in sapphire and GaN was measured by SEM XPS EPMA and UVF we found the Mo content in sapphire was 10-4,and the Mo content in GaN was lower than ppm. So it was concluded that low-cost Mo crucible is viable.
利用原子力显微镜(AFM)观察了蓝宝石衬底和GaN外延层中缺陷形貌以及衬底与外延之间生长界面的情况，发现在蓝宝石衬底上外延GaN，当蓝宝石中的位错密度小于10~5／cm~2时，GaN中的位错密度增值到10~8～10~9／cm~2。且GaN外延层中的位错密度与蓝宝石衬底中的位错密度没有线性关系。用扫描电镜(SEM)、XPS、电子探针和紫外荧光光谱仪测量了蓝宝石衬底和GaN外延层中的Mo杂质的含量，发现蓝宝石衬底中含有Mo杂质，含量约为10~(-4)(质量含量)；而在外延层GaN中没有检测到Mo杂质，即Mo杂质含量小于ppm级。由此可见，在目前的器件产业工艺要求下用廉价的Mo坩锅生长蓝宝石单晶是可行的。
In this paper, the dislocation in Φ50mm CZ sapphire crystal had been observed by chemical etching with metallograph and SEM. Comparing the results which were obtained when the reagent and temperature and time varied ,we found the dislocation was displayed very clearly and accurately when we etch with KOH at 290℃ for fifteen minutes,which was the best condition.
The defect and interface in sapphire and GaN were observed by AFM.We found that when the dislocation density in sapphire was lower thanl05/cm2, the dislocation density in GaN was 108~109/cm2and not linear with the dislocation in sapphire.The impurity of Mo in sapphire and GaN was measured by SEM XPS EPMA and UVF we found the Mo content in sapphire was 10-4,and the Mo content in GaN was lower than ppm. So it was concluded that low-cost Mo crucible is viable.
引文
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[2] 顾忠良．GaN半导体研究与进展．半导体情报，1999，36(4)：11—14．
[3] 梁春广，张冀．GaN—第三代半导体的曙光．半导体学报，1999，20(2)：89—99．
[4] 范建兴，陈起秀．金刚石薄膜器件．半导体情报，1998，35(5)：30—31．
[5] 李玉增．Ⅲ—Ⅴ族氮化物半导体材料研究概述．稀有金属，1997，21(1)：53—57．
[6] 杨银堂．炭化硅半导体技术新进展．西安电子科技大学学报，1998，25(4)：478—482．
[7] 宋登元．GaN材料系列的研究进展．微电子学，1998，28(2)：125—126．
[8] 彭英才．GaN基监色发光材料与器件．半导体杂志，1997，22(3)：23—26．
[9] Sang-Woo Kim, Ji-Myonlee. Reactivation of Mg acceptor in Mg-doped GaN by nitrogen plasma treatment [J]. Appl phys lett, 2000, 76(21): 3079-3081.
[10] Chen J S. Stability of Rhenium thin films on single crystal(001) beta-SiC [J] Appl phys 1994,75:897-901.
[11] Shalish I, Yoram Shapira. Thermal Stability of Re Schottky Contacts to 6H-SiC[J].IEEE Electron Devices Lett, 2000, 21(12): 1-3.
[12] Shalish I, CEM de Oliverrea. Thermal Stability of Pt Schottky contacts to 4H-SiC. J Appl phys, 2000, 88(10): 5724-5728.
[13] 宋登元．GaN器件的某些关键工艺及其进展．半导体情报，1997，34(4)：32-33．
[14] 刘海涛，陈启秀．宽禁带半导体功率器件．半导体技术，1999，24(2)：1-3．
[15] 党冀萍．今日SiC电子学．半导体情报，1999，36(2)：9-12．
[16] Vassilevdki KV. Eletrical characteristics and structural properties of ohmic contacts to p-type 4H-SiC epitaxial layers. Semiconductor, 1999, 33(11): 1206-1211.
[17] Vssilebski KV. Study of annealing conditions on the formation of ohmic contacts on p~+4H-SiC layers grown by CVD and LPE. Master Sci Eng, 1999, B61-2: 296-300.
[18] Vassilevski K. Fabrication and electrical characerization of 4H-SiC p~+-n-n~+ diodes with low differential resistance.Solid-State Electronics,2000,44:1173-1177.
[19] 赵红，何伟全．监绿光半导体光电子器件的研究与发展现状．半导体光电，2000，21(Supplement)：1-4．
[20] 张玉明．SiC、GaAs和Si的高温特性比较．固体电子学研究与进展，1997，17(3)：305-309．
[21] 尚也淳．SiC抗辐照特性的分析．西安电子科技大学学报，1999，26(6)：807-810．
[22] 张德恒．GaN蓝光材料及其应用．山东大学，1998，23(4)：22-23．
[23] 李晋闽．SiC材料及器件研制的进展．物理，2000，29(8)：481-485．
[24] 任学民．SiC单晶生长技术及器件研究进展．半导体情报，1998，35(4)：8-10．
[25] 杨克武，潘静，杨银堂．SiC半导体材料及其研究应用．半导体情报．2000，37(2)：13-15．
[26] 邓志杰．SiC晶体生长和应用．半导体技术，1998，23(5)：14-15．
[27] Perner, B., Kvapil, Ji., Kvapil, Jo and Plestil, Z.,J. Czochralski growth of YAG: Ce inreducing protective atmosphere. Cryst. Growth, 1981,52(2):552-556.
[28] Cockayne, B., Chesswas, M and Gasson, D.B.,J. Czochralski-grownproustite and related compounds, Mater.Sci.1967,2(1): 7-11.
[29] Zhang Shou-Qing, Tang Liang-an, Wang wen LE Shou-Hong. The relationship between growth orientation and grain boundary generation in sapphire plate crystals growth. Journal of crystal growth 1980,501: 659-662.
[30] 沈玲瑜，生长蓝宝石炉内气氛分析，《全国晶体生长与材料会议论文集》1979．
[31] P.I. Antonov, S.I.Bakholdin, E.A. Tropp, V.S.Yu ferev. An experimental and theoretical study of temperature distribution in sapphire crystals growth from the melt by stepanov's method. Journal of crystal growth 1980,50: 62-68.
[32] 王崇鲁，提拉法生长蓝宝石单晶的温场的研究，《全国晶体生长与材料会议论文集》1982．
[33] Kazumi and Wada. An original apparatus allows the growth of sapphire single crystalswith complicated forms. J.cryst.Growth,1980 50(1) 151.
[34] 王崇鲁，蓝宝石单晶中的气泡和空穴，《硅酸盐通报》第一期，1983．
[35] 秦友兰，倪宗祥．提拉法生长监宝石晶体的工艺特征及晶体质量检测．重庆大学学报．1994，17(6)．129-132．
[36] Kazumi WADA Keigohoshi Kswa. Growth and characterization of sapphire ribbonn crystals. Journal of Grystal Growth 1980,50:151-159.
[37] H.E.Labelle, Jr.EFG, the invention and application to sapphire growth.USA.Journai of Gr4ystal Growth 1980,50:8-17.
[38] A.B.Dreeben, K.M.Kim, A.Schujko. Measurement of meniscus angle in laser heated float zone growth of constant diameter sapphire crystals. Journal of Grystal Growth 1980,50:126-132.
[39] R.E.Novak, R.Matzl, A.Dreeben, S.Berbman. The productionn of EFG sapphire ribbon for heteroepitaxial silicon substrates. Journal of Grystal Growth 1980,50:143-150.
[40] E.R.Doerovinskaya, L.A.Litvinov, V.V.Pishchik. Morphology and structural perfection of shaped sapphire. Journal of Grystal Growth 1980,50:341-344.
[41] T.Ueki, M.Itsumi and T. Takeda, Analysis of Side-Wall Structure of Grown-in Twin-Type Octahedral Defects in Czochralski Silicon. Jpn J. Appl. Phys. 1998,37:1667.
[42] T.Ueki, M.Itsumi and T. Takeda et al. Jpn J. Physical Model of Paths of Microdefects Nucleation When the crystals diameter is increased the growth condition are changed. Appl. Phys. 1998,37:771.
[43] 王崇鲁，白宝石单晶，天津科学技术出版社，1983
[44] 邹蒙，范志达等，坩埚下降法生长白宝石晶体的研究，2000，29(1)42-44．
[45] kurlov V N, Epelbaum B M. EFG growth of sapphire tubes upto 85mm in diameter. J Crastal Growth, 1998,187:107-110.
[46] 周国清，徐科等 温梯法生长φ110mm×80mm蓝宝石晶体位错的化学腐蚀形貌分析。硅酸盐学报，1999，27(6)：78．
[47] Ki-Sung Kim, Kyoung-Bo Kim, Seon-Hyo Kim. Nitridation mechanism of sapphire and its influence on the growth and properties of GaN overlayers. Crystal Growth 2001,233:167-176.
[48] P. Vennegues, B. Beaumont, M. Vaille, P. Gibart. Mocrostructure of GaN epitaxial films at different stages of the growth process on sapphire(0001). Crystal Growth 1997,173:249-259.
[49] 周均铭等，氮化镓基发光二极管产业化中的材料物理问题，物理，2002 31(7)：450
[50] Kazuhide Kusakabe, Katsumi Kishino, Akihiko Kikuchi, Takayuki Yamada, Daisuke Sugihara, Shinich Nakamura. Reduction of thread dislocations in migration enhanced epitaxy growth GaN with N-polarity by use of AlN multiple interlayer Crystal Growth 2001,230:387-391.
[2] 顾忠良．GaN半导体研究与进展．半导体情报，1999，36(4)：11—14．
[3] 梁春广，张冀．GaN—第三代半导体的曙光．半导体学报，1999，20(2)：89—99．
[4] 范建兴，陈起秀．金刚石薄膜器件．半导体情报，1998，35(5)：30—31．
[5] 李玉增．Ⅲ—Ⅴ族氮化物半导体材料研究概述．稀有金属，1997，21(1)：53—57．
[6] 杨银堂．炭化硅半导体技术新进展．西安电子科技大学学报，1998，25(4)：478—482．
[7] 宋登元．GaN材料系列的研究进展．微电子学，1998，28(2)：125—126．
[8] 彭英才．GaN基监色发光材料与器件．半导体杂志，1997，22(3)：23—26．
[9] Sang-Woo Kim, Ji-Myonlee. Reactivation of Mg acceptor in Mg-doped GaN by nitrogen plasma treatment [J]. Appl phys lett, 2000, 76(21): 3079-3081.
[10] Chen J S. Stability of Rhenium thin films on single crystal(001) beta-SiC [J] Appl phys 1994,75:897-901.
[11] Shalish I, Yoram Shapira. Thermal Stability of Re Schottky Contacts to 6H-SiC[J].IEEE Electron Devices Lett, 2000, 21(12): 1-3.
[12] Shalish I, CEM de Oliverrea. Thermal Stability of Pt Schottky contacts to 4H-SiC. J Appl phys, 2000, 88(10): 5724-5728.
[13] 宋登元．GaN器件的某些关键工艺及其进展．半导体情报，1997，34(4)：32-33．
[14] 刘海涛，陈启秀．宽禁带半导体功率器件．半导体技术，1999，24(2)：1-3．
[15] 党冀萍．今日SiC电子学．半导体情报，1999，36(2)：9-12．
[16] Vassilevdki KV. Eletrical characteristics and structural properties of ohmic contacts to p-type 4H-SiC epitaxial layers. Semiconductor, 1999, 33(11): 1206-1211.
[17] Vssilebski KV. Study of annealing conditions on the formation of ohmic contacts on p~+4H-SiC layers grown by CVD and LPE. Master Sci Eng, 1999, B61-2: 296-300.
[18] Vassilevski K. Fabrication and electrical characerization of 4H-SiC p~+-n-n~+ diodes with low differential resistance.Solid-State Electronics,2000,44:1173-1177.
[19] 赵红，何伟全．监绿光半导体光电子器件的研究与发展现状．半导体光电，2000，21(Supplement)：1-4．
[20] 张玉明．SiC、GaAs和Si的高温特性比较．固体电子学研究与进展，1997，17(3)：305-309．
[21] 尚也淳．SiC抗辐照特性的分析．西安电子科技大学学报，1999，26(6)：807-810．
[22] 张德恒．GaN蓝光材料及其应用．山东大学，1998，23(4)：22-23．
[23] 李晋闽．SiC材料及器件研制的进展．物理，2000，29(8)：481-485．
[24] 任学民．SiC单晶生长技术及器件研究进展．半导体情报，1998，35(4)：8-10．
[25] 杨克武，潘静，杨银堂．SiC半导体材料及其研究应用．半导体情报．2000，37(2)：13-15．
[26] 邓志杰．SiC晶体生长和应用．半导体技术，1998，23(5)：14-15．
[27] Perner, B., Kvapil, Ji., Kvapil, Jo and Plestil, Z.,J. Czochralski growth of YAG: Ce inreducing protective atmosphere. Cryst. Growth, 1981,52(2):552-556.
[28] Cockayne, B., Chesswas, M and Gasson, D.B.,J. Czochralski-grownproustite and related compounds, Mater.Sci.1967,2(1): 7-11.
[29] Zhang Shou-Qing, Tang Liang-an, Wang wen LE Shou-Hong. The relationship between growth orientation and grain boundary generation in sapphire plate crystals growth. Journal of crystal growth 1980,501: 659-662.
[30] 沈玲瑜，生长蓝宝石炉内气氛分析，《全国晶体生长与材料会议论文集》1979．
[31] P.I. Antonov, S.I.Bakholdin, E.A. Tropp, V.S.Yu ferev. An experimental and theoretical study of temperature distribution in sapphire crystals growth from the melt by stepanov's method. Journal of crystal growth 1980,50: 62-68.
[32] 王崇鲁，提拉法生长蓝宝石单晶的温场的研究，《全国晶体生长与材料会议论文集》1982．
[33] Kazumi and Wada. An original apparatus allows the growth of sapphire single crystalswith complicated forms. J.cryst.Growth,1980 50(1) 151.
[34] 王崇鲁，蓝宝石单晶中的气泡和空穴，《硅酸盐通报》第一期，1983．
[35] 秦友兰，倪宗祥．提拉法生长监宝石晶体的工艺特征及晶体质量检测．重庆大学学报．1994，17(6)．129-132．
[36] Kazumi WADA Keigohoshi Kswa. Growth and characterization of sapphire ribbonn crystals. Journal of Grystal Growth 1980,50:151-159.
[37] H.E.Labelle, Jr.EFG, the invention and application to sapphire growth.USA.Journai of Gr4ystal Growth 1980,50:8-17.
[38] A.B.Dreeben, K.M.Kim, A.Schujko. Measurement of meniscus angle in laser heated float zone growth of constant diameter sapphire crystals. Journal of Grystal Growth 1980,50:126-132.
[39] R.E.Novak, R.Matzl, A.Dreeben, S.Berbman. The productionn of EFG sapphire ribbon for heteroepitaxial silicon substrates. Journal of Grystal Growth 1980,50:143-150.
[40] E.R.Doerovinskaya, L.A.Litvinov, V.V.Pishchik. Morphology and structural perfection of shaped sapphire. Journal of Grystal Growth 1980,50:341-344.
[41] T.Ueki, M.Itsumi and T. Takeda, Analysis of Side-Wall Structure of Grown-in Twin-Type Octahedral Defects in Czochralski Silicon. Jpn J. Appl. Phys. 1998,37:1667.
[42] T.Ueki, M.Itsumi and T. Takeda et al. Jpn J. Physical Model of Paths of Microdefects Nucleation When the crystals diameter is increased the growth condition are changed. Appl. Phys. 1998,37:771.
[43] 王崇鲁，白宝石单晶，天津科学技术出版社，1983
[44] 邹蒙，范志达等，坩埚下降法生长白宝石晶体的研究，2000，29(1)42-44．
[45] kurlov V N, Epelbaum B M. EFG growth of sapphire tubes upto 85mm in diameter. J Crastal Growth, 1998,187:107-110.
[46] 周国清，徐科等 温梯法生长φ110mm×80mm蓝宝石晶体位错的化学腐蚀形貌分析。硅酸盐学报，1999，27(6)：78．
[47] Ki-Sung Kim, Kyoung-Bo Kim, Seon-Hyo Kim. Nitridation mechanism of sapphire and its influence on the growth and properties of GaN overlayers. Crystal Growth 2001,233:167-176.
[48] P. Vennegues, B. Beaumont, M. Vaille, P. Gibart. Mocrostructure of GaN epitaxial films at different stages of the growth process on sapphire(0001). Crystal Growth 1997,173:249-259.
[49] 周均铭等，氮化镓基发光二极管产业化中的材料物理问题，物理，2002 31(7)：450
[50] Kazuhide Kusakabe, Katsumi Kishino, Akihiko Kikuchi, Takayuki Yamada, Daisuke Sugihara, Shinich Nakamura. Reduction of thread dislocations in migration enhanced epitaxy growth GaN with N-polarity by use of AlN multiple interlayer Crystal Growth 2001,230:387-391.