激光剥离对4H-SiC衬底应力及面型的影响研究

doi:10.16553/j.cnki.issn1000-985x.2025.0225

摘要/Abstract

摘要： 在第三代半导体快速发展和8英寸（1英寸=2.54 cm）4H-SiC大尺寸、低翘曲衬底需求持续攀升的背景下，传统多线切割存在材料损耗大、残余应力及面型难以精细控制等问题，而现有激光剥离研究多集中于小尺寸或半绝缘4H-SiC，对导电型8英寸4°离轴晶锭在工程条件下的“工艺参数-残余应力-晶圆面型”关联缺乏系统认识。本文以8英寸导电N型4°离轴4H-SiC晶锭为对象，采用1 064 nm皮秒激光内改质结合超声剥离工艺，系统调节扫描速度（50~400 mm/s），并通过SEM/TEM/SAED、拉曼深度剖面、高分辨XRD-Stoney方程、晶格应力分析及全口径面型测试，构建从微观改质层到整片晶圆翘曲的多尺度评价链路。本文清晰地阐明了皮秒激光对SiC裂纹沿［11 $2 ˉ$ 0］的形成机制及延伸机制，从微观及宏观角度揭示了激光扫描速度对8英寸SiC衬底剥离效果、应力情况及面型质量的影响。为8英寸4H-SiC晶圆的高质量激光剥离制备提供了理论支撑与工艺优化路径，也为基于激光改质层实现SiC衬底面型可控调控提供了可借鉴的研究思路。

关键词: 4H-SiC晶圆; 皮秒激光剥离; 等效残余应力; 晶圆面型; 翘曲度

Abstract: Under the background of the rapid development of third-generation semiconductors and the growing demand for large-size， low-warp 8-inch （1 inch=2.54 cm） 4H-SiC substrates， the traditional multi-wire sawing suffers from large material loss and limited capability in precisely controlling residual stress and wafer shape. However， the existing laser slicing studies are mostly focused on small-size or semi-insulating 4H-SiC， and a systematic understanding of the correlation among process parameters， residual stress， and wafer shape for conductive 8-inch 4° off-axis ingots under engineering conditions is still lacking. In this work， the 8-inch conductive N-type 4° off-axis 4H-SiC ingots are used as the research object. Internal modification is introduced by 1 064 nm picosecond laser irradiation combined with ultrasonic slicing， while the scanning speed （50~400 mm/s） is systematically varied. By means of SEM/TEM/SAED， Raman depth profiling， high-resolution XRD combined with the Stoney equation， lattice stress analysis and full-aperture wafer-shape measurements， a multi-scale evaluation chain is established from the microscopic modified layer to the macroscopic warp of the whole wafer. This paper clarifies the nucleation and propagation mechanism of SiC cracks along the ［11 $2 ˉ$ 0］ crystallographic direction induced by picosecond laser irradiation， and reveals influence of laser scanning speed on the slicing efficiency， stress distribution and wafer shape quality of 8-inch SiC substrates from both micro- and macro-perspectives. The paper provides theoretical support and process-optimization pathways for high-quality laser slicing fabrication of 8-inch 4H-SiC wafers， and offers a reference research idea for achieving controllable wafer shape tuning of SiC substrates based on laser-modified layers.

Key words: 4H-SiC wafer; picosecond laser slicing; equivalent residual stress; wafer shape; Warp

中图分类号:

O786

胡浩林, 李齐治, 佘文婧, 邹兴, 卢致涛, 陈刚, 王映德, 万玉喜. 激光剥离对4H-SiC衬底应力及面型的影响研究[J]. 人工晶体学报, 2026, 55(3): 378-386.

HU Haolin, LI Qizhi, SHE Wenjing, ZOU Xing, LU Zhitao, CHEN Gang, WANG Yingde, WAN Yuxi. Effect of Laser Slicing on Stress and Wafer Shape of 4H-SiC Substrates[J]. Journal of Synthetic Crystals, 2026, 55(3): 378-386.

图/表 4

图1 8英寸4H-SiC晶锭及激光改质几何示意图。（a）激光从C面入射，在晶锭内部形成等间距改质点的示意图；（b）4°离轴4H-SiC晶体的微观台阶结构示意图，其中改质点沿［112ˉ0］方向排布，并相对于物理水平面呈约4°的夹角

Fig.1 Schematic diagrams of 8-inch 4H-SiC ingot and internal laser modification geometry. （a） Schematic diagram of laser incident from C-face and generating equally spaced modified sites inside the ingot；（b） schematic diagram of 4° off-axis 4H-SiC microscopic step structure， where modified sites are aligned along ［112ˉ0］ direction and tilted by about 4° with respect to physical horizontal plane

图2 激光改质层及裂纹的微观结构表征。（a）在扫描速度v=300?mm/s、未进行超声剥离条件下，沿［112ˉ0］方向制备的横截面SEM照片；（b）图2（a）中局部区域放大；（c）晶圆截面的低倍TEM照片（单脉冲能量提高至50 μJ）；（d）改质层（A区）与未改质基体（B区）交界处的高倍TEM照片；（e）A区的选区电子衍射（SAED）图样；（f）B区的SAED图样；（g）超声剥离后、改质面朝上的衬底截面SEM照片；（h）在改质面朝上的截面上，距离表面0、1.3、2.6、3.9 和10 μm处的显微拉曼谱

Fig.2 Microstructural characterization of laser-modified layer and crack network. （a） Cross-sectional SEM image prepared along ［112ˉ0］ direction at a scanning speed of v=300?mm/s without ultrasonic slicing；（b） magnified view of boxed region in Fig.2 （a）；（c） low-magnification TEM image of wafer cross-section （single-pulse energy increased to 50 μJ）；（d） high-magnification TEM image of interface between modified layer （region A） and unmodified substrate （region B）；（e） selected-area electron diffraction （SAED） pattern from region A；（f） SAED pattern from region B；（g） cross-sectional SEM image of substrate after ultrasonic slicing with modified surface facing upward；（h） micro-Raman spectra acquired on cross-section with modified surface facing upward at distances of 0， 1.3， 2.6， 3.9 and 10 μm from surface

图3 基于XRD的平均曲率半径表征。（a）X射线几何示意图；（b）在每片剥离晶圆的改质面上，从中心向边缘以固定步长选取多个径向位置R，逐点测量δ；（c）基于Stoney模型的力学示意图；200~400 mm/s（d）和50~100 mm/s（e）下样品δ-δˉ随径向坐标R的变化，虚线为线性拟合结果，用于提取平均曲率半径Rafter

Fig.3 Characterization of the average curvature radius based on XRD. （a） Schematic diagram of X-ray diffraction geometry；（b） on modified surface of each separated wafer， several radial positions R are selected from center to edge with a fixed step， and δ is measured point by point；（c） mechanical schematic diagram based on Stoney model； variation of sample δ-δˉ with radial coordinate R at 200~400 mm/s （d） and 50~100 mm/s （e）. The dashed lines are linear fits used to extract average curvature radius Rafter

图4 不同扫描速度下曲率、等效平均双轴应力及晶圆面型的变化。（a）剥离晶圆在［112ˉ0］方向上的Rafter及由Stoney方程计算得到的等效平均双轴应力σeff随扫描速度v的变化；（b）由晶格应力分析仪得到的典型面内应力分布图；（c）8英寸剥离晶圆的Warp指标随扫描速度v的变化；（d）8英寸剥离晶圆的Bow指标随扫描速度v的变化

Fig.4 Variation of curvature， equivalent average biaxial stress and wafer shape under different scanning speeds. （a） Variation of Rafter of separated wafers along ［112ˉ0］ direction and equivalent average biaxial stress?σeff calculated from Stoney equation with scanning speed v；（b） representative in-plane stress distribution maps obtained using a lattice stress analyzer；（c） variation of Warp index of 8-inch separated wafers with scanning speed v；（d） variation of Bow?index of 8-inch separated wafers with scanning speed v

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