Methods to Measure the Critical Dimension of the Bottoms of Through-Silicon Vias Using White-Light Scanning Interferometry

Abstract

Through-silicon vias (TSVs) are fine, deep holes fabricated for connecting vertically stacked wafers during three-dimensional packaging of semiconductors. Measurement of the TSV geometry is very important because TSVs that are not manufactured as designed can cause many problems, and measuring the critical dimension (CD) of TSVs becomes more and more important, along with depth measurement. Applying white-light scanning interferometry to TSV measurement, especially the bottom CD measurement, is difficult due to the attenuation of light around the edge of the bottom of the hole when using a low numerical aperture. In this paper we propose and demonstrate four bottom CD measurement methods for TSVs: the cross section method, profile analysis method, tomographic image analysis method, and the two-dimensional Gaussian fitting method. To verify and demonstrate these methods, a practical TSV sample with a high aspect ratio of 11.2 is prepared and tested. The results from the proposed measurement methods using white-light scanning interferometry are compared to results from scanning electron microscope (SEM) measurements. The accuracy is highest for the cross section method, with an error of 3.5%, while a relative repeatability of 3.2% is achieved by the two-dimensional Gaussian fitting method.

Three Degrees of Freedom Global Calibration Method for Measurement Systems with Binocular Vision

“…As the projection point o 1 is the rotation axis projected in the horizontal plane, the coordinate (h, k) of the projection point o1 is obtained from Eqs. (10), (11 14). According to the calibration processes of the coaxial position, the 3D world coordinates at different positions are reconstructed in Fig.…”

“…The coordinate (h, k) of the projection point of the rotation axis is obtained by Eqs. (10), (11). The values of ΔX and ΔY are shown by the displacement sensors that are installed on the two directions of the three-DOF calibration system.…”

“…It provides flourishing developments in motion parameters testing, measurement of machine parts, parameter detection of micro-operating systems, 3D profile reconstruction [4][5][6][7], etc. It also gradually permeates into the aerospace, robot navigation, industrial measurement and bio-medical areas [8][9][10][11][12][13]. System calibration is the basis for binocular vision to obtain 3D coordinates.…”

Electromagnetic analysis for optical coherence tomography based through silicon vias metrology

“…Works on TSV height measurement by any optical technique incorporate up to our knowledge either non-electromagnetic models for light propagation inside TSV [4][5][6][7]26] or time-consuming rigorous computations with the Rigorous Coupled Wave Analysis (RCWA) [8][9][10][11]. This paper aims at an estimate and improvement of the accuracy of TSV depth measurements by application of electromagnetic but rapid calculations.…”

Defect Inspection in Display Panel Using Concentrated Auto Encoder

“…Interferometry is used for repeated measurements of PS and inspection. A 3D height image and 2D tomographic image can be obtained from interferometry measurements [8][9][10]. e height of the PS can be measured based on the 3D height image, and the axial CD measurement and the defect of the shape itself can be inspected using the 2D tomographic image.…”