Analysis Of Factors Affecting Gravity-Induced Deflection For Large And Thin Wafers In Flatness Measurement Using Three-Point-Support Method

Liu, Haijun; Dong, Zhigang; Kang, Renke; Zhou, Ping; Gao, Shang

doi:10.1515/mms-2015-0052

Cited by 12 publications

(7 citation statements)

References 20 publications

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“…It is necessary to further explore the method of quantitative evaluation of the processing technology with good repeatability. In our previous studies [18][19][20], we found that the overall deformation measurement results of silicon wafers show excellent repeatability although the microstructure of the silicon material in the subsurface damage layer does not have geometrical continuity and uniformity. The global wafer deformation is the macroscopic performance of its internal microstructure characteristics and has the potential to evaluate the polishing-induced subsurface damage.…”

Section: Introductionmentioning

confidence: 87%

Evaluation of polishing-induced subsurface damage based on residual stress distribution via measured global surface deformation for thinned silicon wafers

Liu¹,

Zhou²,

Han³

et al. 2021

Surf. Topogr.: Metrol. Prop.

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Polishing is widely used to obtain smooth thinned wafer surfaces and the process-induced subsurface damage is often evaluated by scanning electron microscope or transmission electron microscope images. However, the difference of microscope images is very slight and subtle between wafers and affected by the location selection of the measured points. In this study, we explored the method of evaluating the polishing-induced subsurface damage based on residual stress distribution via measured global surface deformation. The surface deformation was first measured and then the polishing-induced residual stress distribution was calculated from the surface topography data by solving the system of linear equations. The polishing-induced subsurface damage could be evaluated independent of the dimension of the silicon wafer by the proposed method. How the thinned silicon wafer was supported during measurement process greatly affected polishing-induced wafer deformation and gravity-induced deformation should be separated from the measured data. Regularization method should be introduced in the calculation of residual stress to reduce the errors caused by the multi-collinearity of the system of linear equations. The calculated residual stress distribution was found to be an obvious centrosymmetric figure and exhibited a quasi-axisymmetric pattern with the axis of symmetry correlated with certain crystalline directions, indicating the effect of anisotropy of monocrystalline silicon in the polishing process. The proposed method could also be used in the evaluation of polishing-induced subsurface damage of other large and thin substrate plates.

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Section: Introductionmentioning

confidence: 87%

Evaluation of polishing-induced subsurface damage based on residual stress distribution via measured global surface deformation for thinned silicon wafers

Liu¹,

Zhou²,

Han³

et al. 2021

Surf. Topogr.: Metrol. Prop.

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“…Residual stress of the ground monocrystalline wafers was measured using an indirect method relying on the deformation of the wafer induced by the stress. The warping profile of the wafers after grinding was measured using a device developed in our laboratory [15]. The deformation of both sides of the wafer was measured from three support points, and then, the measured results were subtracted from one another to eliminate the effect of gravity-induced deformation.…”

Section: Residual Stressmentioning

confidence: 99%

Sensitivity analysis of the surface integrity of monocrystalline silicon to grinding speed with same grain depth-of-cut

et al. 2020

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Mechanisms for removal of materials during the grinding process of monocrystalline silicon have been extensively studied in the past several decades. However, debates over whether the cutting speed significantly affects the surface integrity are ongoing. To address this debate, this study comprehensively investigates the effects of cutting speed on surface roughness, subsurface damage, residual stress, and grinding force for a constant grain depth-of-cut. The results illustrate that the changes in the surface roughness and subsurface damage relative to the grinding speed are less obvious when the material is removed in ductile-mode as opposed to in the brittle-ductile mixed mode. A notable finding is that there is no positive correlation between grinding force and surface integrity. The results of this study could be useful for further investigations on fundamental and technical analysis of the precision grinding of brittle materials.

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“…A detailed study of the warpage process of wafers is caused by the growing requirements for the characteristics of structures and the need to ensure sufficient strength for their functioning. Uneven stress and deformation, significant influence of the method and area of wafer attachment, the influence of gravity [3] becomes much more pronounced for wafers with a diameter of 300 mm [4], for thinned wafers [5], including when creating wafer assemblies [6]. Separately, it should be noted that with a decrease in the thickness of the wafers, an asymmetric (cylindrical, saddleshaped) bend begins to be observed [4,7,8], this process is currently poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Technique for investigation of the shape changes of wafers and thin-film membranes by using geomorphometric approaches

2022

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We discuss a technique for investigating changes in complex topography and shape of structures using geomorphometric methods to study surfaces of wafers and membranes formed by the Bosch process. The wafers were analyzed before and after the deposition of the SiO2 layer. The membranes were analyzed during the bulge testing. The study was carried out using maps of the catchment area and principal curvatures taking into account artifacts of the approximation of experimental data. We found a correspondence between the distribution of lines connecting the highest surface areas before and after the deposition of the SiO2 layer on the wafers. For membranes with structure: Al(0.8 μm)/SiO2(0.6 μm)/Al(1.1 μm), pSi*(0.8 μm)/SiNx(0.13 μm)/SiO2, Al(0.6 μm) we also found that features of membrane boundaries are mainly caused by their initial shape rather than change under the action of an applied pressure. The advantages of geomorphometric methods for studying changes in the shape of wafers and thin-film membranes in technological processes for the manufacturing of microelectronic devices are shown in comparison with traditional methods for analyzing surface topography maps. Keywords: thin films, membrane, defect, mechanical characteristics, mechanical stresses, deformation, deflection, strain, microelectromechanical systems, MEMS, circular membrane, silicon substrate, optical profilometry, overpressure, geomorphometry, Gaussian curvature, warpage, principal curvatures, wafer, bulge testing, bulging method, thin-layer coating, digital elevation models, DEM, surface, topography.

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Analysis Of Factors Affecting Gravity-Induced Deflection For Large And Thin Wafers In Flatness Measurement Using Three-Point-Support Method

Cited by 12 publications

References 20 publications

Evaluation of polishing-induced subsurface damage based on residual stress distribution via measured global surface deformation for thinned silicon wafers

Evaluation of polishing-induced subsurface damage based on residual stress distribution via measured global surface deformation for thinned silicon wafers

Sensitivity analysis of the surface integrity of monocrystalline silicon to grinding speed with same grain depth-of-cut

Technique for investigation of the shape changes of wafers and thin-film membranes by using geomorphometric approaches

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