Surface roughening in ion implanted 4H-silicon carbide
Surface roughening in ion implanted 4H-silicon carbide
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DOI：
10.1007/s11664-999-0016-z
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发表时间：
1999-03-01
影响因子：
2.1
通讯作者：
Walker, DE
中科院分区：
文献类型：
--
作者：
Capano, MA;Ryu, S;Walker, DE
碳化硅（SiC）器件有潜力生产功能能力远远超过硅器件的新组件。通过离子注入对SiC进行选择性掺杂是一种重要的制造技术，如果要实现SiC器件的潜力，就必须完全理解这种技术。离子注入SiC的一个主要问题是在激活注入的受体离子硼或铝所需的高温下退火SiC导致的表面粗糙化。本文探讨了注入和退火4 H-SiC表面粗糙化的原因和可能的解决方案。样品由4 H-SiC衬底上的n型外延层（5 × 10（15）cm（-3），4 μ m厚）组成，分别注入B或Al，总剂量为4 × 10（14）cm（-2）或2 × 10（15）cm（-2）。粗糙度测量使用原子力显微镜。从均方根（rms）粗糙度与退火温度的变化，表观活化能为粗糙化后注入Al和B分别为1.1和2.2 eV，在氩气中退火时。随时间变化的激活和表面形态分析表明，植入物激活对时间的次线性依赖;激活百分比后5分钟退火硼注入后约为一个因素的两个小于40分钟退火后。均方根表面粗糙度保持相对恒定-在氩气中在1750摄氏度退火的时间。该温度下的粗糙度值约为8.0 nm。在不同的气氛中进行的退火实验证明了使用硅烷的好处，以保持良好的表面形态。当硼或铝注入物在硅烷中在1100 ℃下退火时，粗糙度为1.0 nm（rms），但当在氩气中在相同温度下退火时，B和Al分别为约8 nm和11 nm。
Silicon carbide (SiC) devices have the potential to yield new components with functional capabilities that far exceed components based on silicon devices. Selective doping of SiC by ion implantation is an important fabrication technology that-must be completely understood if SiC devices are to achieve their potential. One major problem with ion implantation into SiC is the surface roughening that results from annealing SiC at the high temperatures which are needed to activate implanted acceptor ions, boron or aluminum. This paper examines the causes and possible solutions to surface roughening of implanted and annealed 4H-SiC. Samples consisting of n-type epilayers (5 x 10(15) cm(-3), 4 mu m thick) on 4H-SiC substrates were implanted with B or Al to a total dose of 4 x 10(14) cm(-2) or 2 x 10(15) cm(-2), respectively. Roughness measurements were made using atomic force microscopy. From the variation of root mean square (rms) roughness with annealing temperature, apparent activation energies for roughening following implantation with Al and B were 1.1 and 2.2 eV, respectively, when annealed in argon. Time-dependent activation and surface morphology analyses show a sublinear dependence of implant-activation on time; activation percentages after a 5 min anneal following boron implantation are about a factor of two less than after a 40 min anneal. The rms surface roughness remained relatively constant-with time for anneals in argon at 1750 degrees C. Roughness values at this temperature were approximately 8.0 nm. Annealing experiments performed in different ambients demonstrated the benefits of using silane to maintain good surface morphology. Roughnesses were 1.0 nn (rms) when boron or aluminum implants were annealed in silane at 1100 degrees C, but were about 8 and 11 nm for B and Al, respectively, when annealed in argon at the same temperature.