ROTATING-ELEMENT ELLIPSOMETER AND METHOD FOR MEASURING PROPERTIES OF THE SAMPLE USING THE SAME

• US 20140313511A1
• Filed: 07/03/2014
• Published: 10/23/2014
• Est. Priority Date: 08/17/2011
• Status: Abandoned Application

• Current Assignee: Korea Research Institute of Standards and Science
• Original Assignee: Korea Research Institute of Standards and Science
• Inventors: CHO, Yong Jai, CHO, Hyun Mo, CHE GAL, Won
• Application Number:
  US14/322,966
• Publication Number:
  US 20140313511A1
• Time in Patent Office: Days
• US Class Current: 356/364
• CPC Class Codes: G01N 2021/213 Spectrometric ellipsometry
• CPC Class Codes: G01N 21/211 Ellipsometry optical thickness measurement G01B11/06
• CPC Class Codes: G06F 17/141 Discrete Fourier transforms

Abstract

Provided is a real-time spectroscopic ellipsometer capable of obtaining information on properties of a sample, a nano pattern shape, and the like, in real time by measuring and analyzing, for a plurality of wavelengths, a change in a polarization state of incident light generated while being reflected or transmitted due to the sample when light having a specific polarization component is incident to the sample. The real-time spectroscopic ellipsometer according to the exemplary embodiment of the present invention have the improved structure and function to solve problems such as polarization dependency of a light source and a photometric detector, wavelength dependency of a compensator, a limitation of a change in integration time due to a fixing of a measuring frequency of exposure, in a rotating-element multichannel spectroscopic ellipsometers of the related art, thereby measuring more accurately, precisely, and rapidly measuring the characteristics of the sample than the related art.

Claims

1. An ellipsometer including a light source, a polarization modulating unit, a sample stage, a polarization analysis unit, and a photometric detector, the ellipsometer comprising:

a digital signal modulating apparatus connected to an optical element unit rotating at constant velocity of the polarization modulating unit or the polarization analysis unit to control a measuring frequency of exposure of the photometric detector,

the integration time and the measuring frequency of exposure of the photometric detector are controlled according to the intensity of light irradiated to the photometric detector.

2. The ellipsometer of claim 1, further comprising:

an operator acquiring a plurality of values of exposure for a waveform of the intensity of light at a predetermined interval for any multiple of the period from the photometric detector and performing discrete Fourier transform on the plurality of values of exposure to determine a plurality of Fourier coefficients and average value component for the waveform of the intensity of light,

wherein the intensity of light may be changed at a predetermined period over time.

3. The ellipsometer of claim 2, wherein the value of exposure S_j is measured by S_j=∫

_(j-1)pT/M+Td^{(j-1)pT/M+Td+Ti}I(t)dt, (j=1, 2, 3, . . . , M) and

non-normalized Fourier coefficients A_2n and B_2n of waveform of intensity of light and average value I_dc of intensity of light each are obtained by

4. The ellipsometer of claim 3, wherein properties for the sample of interfacial characteristic, a thin film thickness, a complex refractive index, a nano shape, anisotropic characteristic, surface roughness, a composition ratio, crystallinity are analyzed from the Fourier coefficients (I_dc/I₀₀, A_2n/I₀₀, B_2n/I₀₀;

n=1, 2, 3, . . . ) or (I_dc/I₀₀, A_2n/I_dc, B_2n/I_dc;

n=1, 2, 3, . . . )

5. The ellipsometer of claim 3, wherein ellipsometric functions are obtained by limitedly selecting a part of the Fourier coefficients I_dc, A_2n, B_2n;

n=1, 2, 3, . . . ).

6. The ellipsometer of claim 1, wherein the ellipsometer is any one of rotating-element ellipsometers.

7-20. -20. (canceled)