Photoelastic Characterization of Residual Strain Distribution in Commercial Off-Axis SiC Substrates
Photoelastic Characterization of Residual Strain Distribution in Commercial Off-Axis SiC Substrates
复制标题
商用离轴 SiC 衬底中残余应变分布的光弹性表征
DOI：
10.1007/s11664-020-08211-w
复制
发表时间：
2020
影响因子：
2.1
通讯作者：
Kanamoto Kazuki
中科院分区：
文献类型：
--
作者：
Fukuzawa Masayuki;Kanamoto Kazuki
利用自行研制的成像偏光镜，对商用4°离轴4 H-碳化硅（SiC）单晶片的应变双折射二维分布进行了选择性表征。单轴晶体中常见的自然双折射现象，通过优化光的入射角，使光在晶体中平行于光轴传播，从而消除了这种现象。消除的自然双折射至少是应变引起的双折射的两倍，这证明了消除过程的有效性。最佳入射下的延迟图显示了应变诱导双折射的各种分布，例如由于晶体结构缺陷引起的局部集中以及由于晶体生长和冷却过程中的热应力引起的逐渐增加或减轻。最大延迟为0.28，对应于应变项的7.6 × 10− 5和应力项的30 MPa。由于其足够的敏感性，应变诱导的双折射和消除能力的自然双折射，它的结论是，我们的技术是有用的，以表征商业离轴SiC衬底中的残余应变分布。
Two-dimensional distribution of strain-induced birefringence has been selectively characterized in commercial 4° off-axis wafers of 4H-silicon carbide (SiC) crystal by using an originally-developed imaging polariscope. The natural birefringence, which is often observed in uniaxial crystals, was eliminated by optimizing the light incident angle so that the light propagates parallel to thec-axis inside the crystal. The eliminated natural birefringence was at least twice as large as that of the strain-induced ones, which demonstrates the validity of the elimination process. A typical retardation map under optimal incidence revealed various distributions of strain-induced birefringence, such as local concentrations due to the structural crystal defects and gradual increase or relief due to the thermal stress during the crystal growth and cooling processes. The maximum retardation was 0.28, which corresponds to 7.6 × 10−5in strain terms, and 30 MPa in stress terms. Because of its sufficient sensitivity to the strain-induced birefringence and elimination capability in the natural birefringence, it is concluded that our technique is useful to characterize the residual strain distribution in commercial off-axis SiC substrates.