COPs/particles discrimination using an automated surface inspection tool

Abstract

An automated surface inspection system, KLA -Tencor SP1-TBI, was used to investigate the surface defectivity of three different sets of bare silicon wafers, in order to test the capability of the tool to distinguish between particles (removable defects) and pits, generally called COPs (Crystal Originated Particles). Two different type of MEMC products have been investigated: The Advanta wafers characterized by a low density of COPs and with an annular region at the edge of the wafer that is "free" of any agglomerated defect; A standard P100 polished material in which the COP defects are present on a large portion of the wafer surface almost with the same density. When the SP1-TBI discrimination algorithm is applied, real time defect classification (RTDC) is performed and the resulting wafer map displays simultaneously but differently particles and COPs due to their different scattering behavior. The validation of the SP1-TBI scan results has been performed in two ways. The first one making a pre to post cleaning comparison and the second one by Optical and Atomic Force Microscope investigation. In both cases the confidence level of the algorithm is depending on the material investigated but is generally greater then 90% allowing considering the SP1-TBI algorithm as a good system to distinguish particles from COPs.

Development of multi-stage optical variable attenuator system and its control method for wafer inspection system

“…2.1 System overview An overview of the optical wafer inspection system [2][3][4][5][6][7][8][9][10][11] is shown in Fig. 1.…”

“…Various inspection systems have been developed for each semiconductor manufacturing process [1]. Optical inspection systems for unpatterned wafers [2][3][4][5][6][7][8][9][10][11] are used to measure surface defects of silicon wafers as the pre-shipment inspection in wafer manufactures and the acceptance inspection in device manufactures. In order to inspect the entire wafer surface at high speed, this system rotates and moves the wafer to irradiate a laser beam onto the wafer in a spiral shape and detects the scattered light from defects.…”

Classification and Size Estimation of Wafer Defects by Using Scattered Light Distribution

“…Therefore, in this investigation we examined methods of estimating the types and sizes of wafer defects using various scattering distribution patterns obtained from numerical simulations by the discrete dipole approximation (DDA) method . If the detection of defects in the scattered laser light inspection is limited to only two types (foreign particles and crystal defects), the detection accuracy is greater than 90% . However, since there are no publications dealing with the detection of three or more types of defects, in this paper we address the problem of estimating multiple types of defects.…”