Tools for analysis of thin film

Tools for analysis of thin film

Both spectroscopic ellipsometers and reflectometers are extremely useful for thin film analysis. At omt, our goal is to provide our customers with the optimized device for their needs, to simplify the handling of these devices, and to make state-of-the-art measurement analysis using the easiest procedures available.

In general, ellipsometry is a technique that is incorporated in highly sophisticated R&D laboratories for determining n&k for multilayer systems and thicknesses of very thin films. Reflectometry, on the other hand, is used for more common laboratory applications and because of its ruggedness, short acquisition times and insensitivity to sample positioning, for online industrial applications. However the choice of the proper device is very application dependent and often requires expert background knowledge.

To determine which device best satisfies your needs, use the table given below.
For further assistance and to identify the proper device for your application, please contact omt.


 

Ellipsometer

Reflectometer

Parameters

Film thickness

Band gap measurement

Analysis of sheet resistance

Moisture content

Color

 

0 - 10 µm (1)

yes

yes

not recommended

not recommended

 

20 nm - 10 µm (1)

yes

yes

yes (2)

yes

Sample material

Very thin (below 20 nm)

Known coating on unknown matrix

Unknown coating on unknown matrix

Rough material

Multi-layer (e.g. CIGS, TiO2/SiO2/glass)

 

yes

yes

yes

not recommended

yes

 

no

yes (3)

no

yes

yes

Measurement

Requirement of n/K values

Requirement of known reference

Measurement and analysis speed

Sensitive to birefringence

Sample adjustment


Spot size

 

no

no (8)

10 - 20 sec (4)

yes

Tolerance:
   Height: ± 1 mm
   Angle: ± 0.5° (AOI)

2 x 4 mm
Microspot 200x100µm; 200x400µm

 

yes (5)

yes (8)

about 16x faster then ellipsometer

no

Tolerance:
   Height: ± 5 mm
   Angle: ± 10°

2 - 10 mm (selectable)
Microspot 300µm

Application

Harsh environment

Online process control

R&D

 

not recommended

yes (6)

yes

 

yes (7)

yes

yes

Expandability

possible
(e.g. scanner unit, imaging)

easy and inexpensive
(e.g. transmission measurement, scanner unit, imaging)

Notes:

(1) values depends on material and matrix (thickness parameters given here are for SiO2 on Si)

(2) IR range required

(3) n/k values must be known

(4) for SiO2 on Si

(5) for unknown n/k values please contact omt for support

(6) NOTE: the alignment of sample is important

(7) device supports usage in environments such as in-situ vacuum, extremely humid conditions, sputtering chambers, etc.

(8) omt distinguishes between calibration of measurement system and reference measurement for the sample