bi ltd

Picometer Ellipsometer: Specifications

Light Source
Single wavelength: He/Ne laser, laser diode; Spectroscopic: quartz halogen lamp (> 400 nm) or Hg/Xe lamp (> 200 nm).
Polarisers
UV-grade Polaroid (depending on required wavelength range).
Birefringence Modulator
3 component high stability design, susprasil optical element with transmission to 200 nm, 50 kHz modulation frequency.

Detector
End-on photomultiplier or UV enhanced high sensitivity silicon photodiode.

Beam Size
1 mm or larger depending upon light source. Focussing optics available for 10 µm beam size with laser source.

Table
Ultra high rigidity table with incident and reflection arms in vertical plane. Arms separately driven by stepping motors with angular resolution of 1/20 degrees.Table allows rotation of arms through 360°. Closest angle between arms 20°. 140 mm free diameter in center of table. XYZ adjustable sample mount.

Electronics
Dual analog lock-in amlifier at 50 kHz and 100 kHz frequencies provides simultaneous reading of Re(r) and Im(r).

Sensitivity
Im(r), Re(r) < 10^-5 at 1 s response time (reflection from glass). Sensitivity is reduced at shorter time constants (variation is roughly proportional to t^-1/2).

Speed
Fastest response time is 1 ms.

Computer Control
Software implemented as extension to the IgorPro data analysis package by WaveMetrics running on WindowsNT. A Microcontroller acts as hardware interface and data logger for true real-time operation. The control software allows simultaneous instrument control and on-line data analysis.
A notebook computer can be used as the host without additional hardware.
Contact us for information on support of Macintosh PowerPC systems.

Data Analysis
Simulations of ellipticity are provided for layers on substrates, as a function of angle of incidence, layer thickness, substrate and film optical anisotropy.

Special Features

Photomultiplier gain control can be set to track a preset DC current for large intensity variations.
Analyser can be switched at 1.5 kHz to eliminate offsets.
Automatic tracking of the Brewster angle.
Modular design for easy modification and upgrades.

Options

Focussing optics for 10µm beam (with laser light source)
Scanning sample stage under computer control
Normal Incidence Option for RAS/RDS measurements; see additional information sheet
Installation and training

Contact us if your application requires a custom configuration. In most cases, the modular design of the Picometer Ellipsometer allows us to implement non-standard setups without extra charge.