Wafer thickness measuring method and measuring device

Abstract

The invention provides a wafer thickness measuring method and measuring device. An automatic focusing distance measurement principle is used, the zero point position of a motor arranged on a measuringlens in the Z direction is calibrated by measuring a standard wafer with a known thickness. When the thickness of a to-be-measured wafer is measured, the position of the motor in the Z direction is adjusted on the basis of the zero point position so as to adjust the focal length of the test lens, automatic focusing is completed, and the thickness of the to-be-measured wafer is indirectly calculated through the change of the position of the motor in the Z direction. The wafer thickness measurement method provided by the invention can realize non-contact thickness measurement of the heavily doped wafer, especially the thickness measurement of the heavily doped wafer, reduce the wafer damage rate in the measurement process, and the measurement precision is less than 1% and the repeatabilityis less than 0.1%. The device meets the mass production requirement and facilitates automatic production and improves the production efficiency.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method and device for measuring the thickness of a wafer. Background technique [0002] In the integrated circuit manufacturing process, a silicon single wafer heavily doped with arsenic (As) and phosphorus (P) is an ideal epitaxial substrate material because it can overcome the inherent latch-up effect and α in the device structure. Parasitic effects such as particle soft failure are widely used in integrated circuits and high-end power devices. Unlike ordinary polished wafers and lightly doped wafers, heavily doped wafers have a very high impurity concentration. When the resistivity is reduced to about 1mohm / cm, the impurity concentration is close to the limit of As or P in single crystal silicon. Solid solubility, the concentration of As reaches 1E20 atom / cm3, and the concentration of P reaches 6E19 atom / cm3. At this time, the properties of the wafer hav...

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Problems solved by technology

This method is more suitable for opaque wafers with normal thickness, but for thinned wafers, especially wafers with Taiko rings, when the wafer thickness is less than 200 μm, the warpage of the wafer is particularly Large, the through-beam distance measurement method uses a suspended test, and the wafer is difficult to support. At the same time, because the warpage of the wafer is particularly large, usually reaching 3-5mm, the reflected signal of the light will be interfered, resulting in inaccurate test results and accurate testing. poor repeatability

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