Characterization of materials and film stacks for accurate surface topography measurement using a white-light optical profiler (original) (raw)
Related papers
2006
In vertical scanning white-light interferometry, two peaks appear in the interference waveform if a transparent film exists on the surface to be measured. We have developed an algorithm that is able to detect the position of these peaks quickly and accurately, and have put into practical use a film profiler that is able to simultaneously measure the profiles of both the front and back surfaces and the thickness distribution of a transparent film. This technique is applicable to transparent films with an optical thickness of approximately 1 μm or greater, and it is used effectively in the semiconductor and LCD manufacturing processes.
Optomechatronic Sensors, Instrumentation, and Computer-Vision Systems, 2006
In vertical scanning white-light interferometry, two peaks appear in the interference waveform if a transparent film exists on the surface to be measured. We have developed an algorithm that is able to detect the position of these peaks quickly and accurately, and have put into practical use a film profiler that is able to simultaneously measure the profiles of both the front and back surfaces and the thickness distribution of a transparent film. This technique is applicable to transparent films with an optical thickness of approximately 1 m or greater, and it is used effectively in the semiconductor and LCD manufacturing processes.
Thin film thickness measurements using Scanning White Light Interferometry
Thin Solid Films, 2014
Scanning White Light Interferometry is a well-established technique for providing accurate surface roughness measurements and three dimensional topographical images. Here we report on the use of a variant of Scanning White Light Interferometry called coherence correlation interferometry which is now capable of providing accurate thickness measurements from transparent and semi-transparent thin films with thickness below 1 μm. This capability will have many important applications which include measurements on optical coatings, displays, semiconductor devices, transparent conducting oxides and thin film photovoltaics. In this paper we report measurements of thin film thickness made using coherence correlation interferometry on a variety of materials including metal-oxides (Nb 2 O 5 and ZrO 2 ), a metal-nitride (SiN x :H), a carbon-nitride (SiC x N y :H) and indium tin oxide, a transparent conducting oxide. The measurements are compared with those obtained using spectroscopic ellipsometry and in all cases excellent correlation is obtained between the techniques. A key advantage of this capability is the combination of thin film thickness and surface roughness and other threedimensional metrology measurements from the same sample area.
3D profiling of a transparent film using white-light interferometry
SICE 2004 Annual Conference , 2004
In the vertical scanning white-light interferometry, two peaks appear in the interference waveform if a transparent film exists on the surface to be measured. An algorithm has been developed that can detect the position of those peaks quickly and accurately, and a "film profiler" has been put into practical use, which is able to measure both the profiles of front and back surfaces and the thickness distribution of a transparent film simultaneously. This technique is applicable to transparent films with the optical thickness of approximately 1 /spl mu/m or greater, and it is used effectively in semiconductor and LCD manufacturing processes.
Spectrally resolved white-light interferometry for 3D inspection of a thin-film layer structure
Applied Optics, 2009
We describe an improved scheme of spectrally resolved white-light interferometry, which provides 3D visual inspection of a thin-film layer structure with nanometer level resolutions. Compared to the authors' previous method [Appl. Phys. Lett. 91, 091903 ], 3D tomographic information of thin films can be obtained by decoupling the film thickness and top surface profile, which is embodied by inducing spectral carrier frequency to the reference arm and applying a low-pass filter to the interferogram instead of two troublesome measurement steps of activating and deactivating a mechanical shutter. We test and verify our proposed method by measuring a patterned thin-film layer structure as well as standard specimens of thin films with various thicknesses.
Proc. of JSPE Autumn Meeting, 2007
We propose a new method for simultaneous measurement of refractive index and geometric thickness of transparent films by use of an interferometric surface profiler. It is based on a combination of two techniques, which we have proposed recently. Firstly, the target film is inserted into the measuring optical path, and the surface height change of a back-mirror surface is measured. Then the optical thickness is measured from the two peak positions in the interferogram. From these two measurements, we can obtain the refractive index and thickness of the film separately. The experimental results verify the feasibility of this method.
3-D Shape Measurement of a Transparent Film by White Light Interferometry
2020
In vertical scanning white-light interferometry, two peaks appear in the interference waveform when a transparent film exists on the surface to be measured. We developed an algorithm to detect these peaks with high speed and accuracy, and developed a film profiler that can simultaneously measure the surface and back surface profiles of the transparent film and the thickness distribution of the film. This system is applicable to transparent films with an optical thickness of more than 1 μm and has been used effectively in the manufacturing process of semiconductors and LCDs.
Abstract： In the optical interferometric surface profiling methods represented by the white-light interferometry, if the measurement target is covered with a transparent film, the backside reflected light becomes a disturbance and accurate measurement cannot be performed. In addition, the optical film thickness measurement methods such as spectroscopy are slow due to single-point measurement, and their spatial resolution is limited. We propose a simultaneous measurement algorithm for surface profile and film thickness distribution using the three-wavelength interferometry. A three-wavelength interferogram obtained from a three-wavelength illumination system and a color camera is waveform-separated to estimate the surface height, backside height and film thickness of each pixel. The proposed method is validated through computer simulations and experiments.
Thin film thickness profile measurement using an interferometric surface profiler
2007
The technique of surface profile measurement using white-light interferometry is widely used in industry. However, its application to transparent thin films has been limited to date because the reflection signals from the front and back surfaces are mixed and must be separated in order to obtain correct measurements. This paper introduces four of our recent developments in this application field: 1) profiling of a thick transparent film, 2) profiling of a thin transparent film, 3) thickness profiling of a freestanding film, and 4) simultaneous measurement of the thickness and refractive index of a freestanding film.
2009
We have developed a scanning white-light interference microscope that offers two complementary modes of operation on a common metrology platform. The first mode measures the topography and the second mode measures the complex reflectivity of an object surface over a range of wavelengths, angles of incidence and polarization states. This second mode characterizes material optical properties and determines film thickness in multi-layer film stacks with an effective measurement spot size typically smaller than 10 μm. These data compensate for material and film effects in the surface topography data collected in the first mode. We illustrate the application of this dual-mode technology for post-CMP production-line metrology for the data storage industry. Our tool concurrently measures critical layer thickness and step height for this application. The accuracy of the latter measurement is confirmed by correlation to AFM measurements.