FR-basic: In situ non-destructive characterization of thin and thick films

Specifications*
Thickness	10nm – 300μm
Wavelength range	400-1100nm
Accuracy	0.5 %
Precision	0.02nm
Spot size	0.5mm
Sample size	10 - 150mm
Detector type	3648 pixels linear CCD array, 16bit A/D
Light source	Regulated Tungsten - Halogen
Lamp life	~ 4000h
Computer requirements	PC with Windows XP/Vista and a USB port available
Power requirements	110V/240V AC
Dimensions (WxLxH)	320mm x 360mm x 345mm
Weight	11.2Kgr

Description

FR-Basic is a table-top optical instrument for non-destructive measurement of film thickness and optical constants (n & k) of stacked transparent and semi-absorbing films over substrates. Its principle of operation is based on White Light Reflectance Spectroscopy (WLRS). In WLRS, the interference signal, at the VIS/NIR spectrum, from the reflectance of the top and bottom surfaces of the film(s) is measured. The reflectance spectrum is then fitted with the multi-layer reflectance equation to derive the thickness and optical constants of the film(s). The tool is controlled by a specially developed Windows program, performing the data acquisition and film thickness and optical constants calculations.

A materials database is included and can easily be expanded by the user. The entire system (hardware – software) is shipped ready for measurements: light source, spectrometer, reflectance probe optical fiber, sample stage, and Windows™ software (Fig.2). The only additional part needed is a computer with a free USB port running Windows XP™ or Vista™ (Fig.1). The system can be easily used by anyone with basic computer skills without any deep knowledge of optics.

FR-Bacic is designed and manufactured with Anodized Aluminum profile supplied by item Industrietechnik GmbH and ensures an elegant and robust construction. All necessary components as Light Source, Spectrometer, Power Supply, Electronics etc. are included in a compact unit. Through the special design of the unit it can be opening (e.g. to change Lamp) with no need of any tools. More over while the construction is 100% modular it can be redesign according the special customer needs, with out any additional cost.

Fig.3 The FR-Basic manual movement mechanism allows for the positioning over a 150mm X 150mm area and the height adjustment over a 60mm region. The movement is smooth and stable through a ball bearing liner guide. The reflection probe can be mounted either vertically or horizontally providing further flexibility in the samples to be measured. In the horizontal position the tool is also used for measurements in liquid environments (see FR-Liquid).

IIn addition, a patterned 4inch Si wafer is provided as a reference. This wafer is covered in the 1st quarter area with thick SiO2 film, in the 2nd quarter with a thin Si3N4 on thick SiO2 layer stack, in the 3rd quarter with a poly-Si/Si3n4/SiO2 layer stack, while the 4rth quarter is blank Si (Fig.4). All areas have been characterized by spectroscopic ellipsometry and a measurement sheet with film thicknesses and optical constants is provided.

The FR-Basic tool can handle layer stacks consisted of numerous layers and two quantities can be calculated simultaneously in real time e.g. the thicknesses of two films or the thickness and n & k of one film etc.
The optical source of the FR-Basic is a white light Halogen lamp, with an especially designed stable power supply and soft-start circuit ensuring very long and stable operation. There are six predefined power settings from 5W to 20W, to choose the most suitable for each application. The light source’s lamp is replaced without the need of any tools.
FR-Basic allows for measurements over the whole sample’s area by X-Y-Z manual movement of the optical fiber holder (Fig.3). FR-Basic is shipped with a top cover and is equipped with a gas inlet for measurement under controlled environmental conditions. Furthermore, the system is able for real time monitoring of film properties under dynamically changing environmental conditions.
FR-Basic has been successfully applied for the measurement of various smooth, transparent or lightly absorbing films over total or partially reflecting substrates.

Applications
Semiconductor
non Metal Films
In-Situ Measurements
Optical Coating
Hardcoats
Polymer Characterization
Biomedical