Compact film thickness monitor


Film thickness monitor with the compact fiber probe is based on the spectrophotometry.It can be used as an in-line or end-point monitor for the various multi-layered film process.

The compact probe can be installed in a small space inside the process tool.It is also possible to judge the mixture ratio of the mixed layer or the crystallinity of Poly-Silicon by using the EMA theory.

(1)Compact probe with the optical fiber

can be installed in a small space inside the process tool.
Since the probe is connected with a optical fiber , it has good durablity.

【 Note 】

It is recommended that the distance from the target surface to the probe is 1mm to 70mm. The measurement area is about 3mmΦ.

1mmΦ and 0.5mmΦ pinhole attachement is additionally prepared.

Optical fiber is 2m length. The size of the probe cover is 50 (L)x34(W)x22(H).

(2)Good repeatability of the film thickness measurement 0.1nm (3σ)


The repeatability of the film thickness is as follows. Measurement time is less than 1sec. 

The following environment is recommended.

0.1nm(3sigma) SiO2 on Si, Thickness range is 50nm to 1um

0.1%(3sigma) SiO2 on Si, Thickness range is over 1um

(3)Multilayer film thickness measurement up to 9 layers


The maximum number of layer depends on the actual film structure and wavelength range.

(4)Material analysis function

  • Evaluation of mixing ratio of the composite material using EMA 
  • Crystallinity and Analysisy of the optical constants 


Effective Medium Approximation (EMA) theory and dielectric function are available for material analysis. They become difficult in case of thin film.

Also, hundreds of optical constants are prepared in advance.

(5)Selectable light source

Light source Wavelength range (nm) Typical life time (Hours)
White color LED 430~700 >50,000
Tungsten-Halogen 400~900 10,000
Deuterium-Halogen 200~1,000 1,000


The best light source depends n the target film thickness and structure.

【Recommended system requirements】

Room temperature : 18 to 45 ℃

Long term : < ±2.0℃/24Hours

Short term: < ±1.0℃/1Hour

Humidity : 45±20% (Under no condensation)