Evolution of lattice distortions in 4H-SiC wafers with varying doping
Evolution of lattice distortions in 4H-SiC wafers with varying doping
复制标题
不同掺杂的 4H-SiC 晶片中晶格畸变的演变
DOI：
10.1038/s41598-020-67900-y
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发表时间：
2020
影响因子：
4.6
通讯作者：
G. Ruland
中科院分区：
文献类型：
--
作者：
N. Mahadik;H. Das;S. Stoupin;R. Stahlbush;P. Bonanno;Xueping Xu;V. Rengarajan;G. Ruland
采用同步辐射X射线摇摆曲线映射（RCM）技术对4H碳化硅（SiC）单晶片的晶格畸变（LD）进行了定量分析，并将其分解为两个分量：晶格应变（Δ d/d）和晶面曲率（LPC）。这些LD的演变进行了研究的三个连续的基板从同一梨，其中之一是基板的参考，和其他两个具有10 μ m厚，1 × 1017和4 × 1014 cm-3 n型掺杂外延层。最低掺杂晶片的晶格应变Δ d/d最高，这是由于与衬底晶片的失配较高。在外延层生长之后，晶片上的LPC变化增加了2倍，与掺杂无关。LPC图表明晶格平面中存在扭曲，该扭曲在外延生长后增加。LPC分量对晶片形状变化具有较高影响，这会降低器件良率。晶格应变分量主要影响基面位错（BPD）的滑移，从而降低器件的可靠性。从峰宽的分析，确定在外延层生长之后，晶片的顶部6微米中的穿透位错增加。
Lattice distortions (LD) in 4H-silicon carbide (SiC) wafers were quantified using synchrotron X-ray rocking curve mapping (RCM), and were resolved into their two components of lattice strain (Δd/d) and lattice plane curvature (LPC) for 150 mm diameter wafers. The evolution of these LDs were investigated for three sequential substrates from the same boule, one of which was the substrate reference, and the other two had a 10 µm thick, 1 × 1017and 4 × 1014cm-3n-type doped epitaxial layer. The lattice strain, Δd/d, was highest for the lowest doped wafer due to higher mismatch with the substrate wafer. After epitaxial layer growth, the LPC variation across the wafer increases by a factor of 2, irrespective of doping. The LPC maps indicate presence of a twist in the lattice planes that increases after epitaxial growth. The LPC component has higher influence on wafer shape change, which can reduce device yields. The lattice strain component predominantly affects the glide of basal plane dislocations (BPDs), thereby reducing device reliability. From analysis of peak widths, it was determined that threading dislocations in the top 6 microns of the wafer increase after epitaxial layer growth.