Apparatus for measuring thickness profile and refractive index distribution of multiple layers of thin films by means of two-dimensional reflectometry and method of measuring the same

Abstract

The present invention relates to a non-contact, non-destructive measuring apparatus that measures thickness profile and refractive index distribution of a single or multiple layers of thin films by means of the principle of reflectometry. According to the present invention, by employing more than one narrow band-pass optical filters and a two-dimensional array of CCD sensors, and by finding an optimal solution for the nonlinear functional relationship between the thickness of said thin film or thin films and the corresponding refractive indexes by using an iterative numerical computation method, said apparatus simultaneously measures local area-wise thickness profile and refractive index distribution among others of said a single layer or multiple layers of thin films on a substrate.

Description

technical field [0001] The present invention relates to the technique of measuring the thickness profile and refractive index distribution of multi-layer thin films by using a two-dimensional reflectometer. Background technique [0002] The process of measuring the thickness profile and associated refractive index profile of multilayer thin films on substrates as part of the thin film coating process in the manufacture of semiconductors, displays such as LCDs, etc. Screening out defective products and monitoring thin film formation on substrates during the early stages of the cycle play an important role in reducing processing costs. [0003] A widely used device for measuring film thickness and refractive index in the semiconductor industry is a reflectometer-based measurement tool. In a broad sense, a reflectometer called a "thin film layer measurement system" is a non-contact, non- Destructive measuring device. [0004] Figures 1a and 1b show a schematic diagram of the...

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Problems solved by technology

Additionally, currently existing spectroscopes are not suitable for measuring film thickness profiles over relatively large areas or for measuring film thickness distributions at many adjacent points at the same time

Of course, it is quite possible to measure the film thickness distribution by repeatedly measuring the thickness while gradually moving the sample substrate in the four X-Y directions, but this operation requires delicate micromanipulators and is very time-consuming

In addition, in order to obtain the film thickness distribution, an accurate substrate moving platform should be used and capable of moving with a synchronous resolution better than 0.1 μm, therefore, the whole measurement device becomes very complicated and expensive in terms of function and structure

In this case, more expensive supermicro manipulators can be used, but are not practical from an economic point of view

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