Partnerships and DHM® users



Height measurement of SiO2 staircase on Si wafer is a common need especially for semiconductor applications.

DHM Reflectometry Analysis enables to retrieve the true profile of transparent steps in contrary to alternative optical profilometer. Within 200 μm vertical range, multiple steps up to 15 μm height can be measured without any scanning.

The presented sample is a test target composed of five different steps of nominal heights (10nm, 100nm, 1µm, 2µm and 4µm). Both each step thickness and material refractive indices are re

  • Layer 0 (air): search for refractive index: N
  • Layer one (SiO2): thickness: 0 nm, uncertainty: 0nm, search for refractive index: Y
  • Layer two (Si): search for refractive index: N
  • Deposit min: -10nm; deposition max: 4200nm; increment: 1nm
  • Refractive index interval: 0.02, RI increment 0.001

Precision of DHM Reflectometry has been proven by comparative measurements with different methods (mechanical profilometer, AFM). Moreover steps edges are better highlighted with DHM optical acquisition while with a mechanical profilometer, the edges are rounded because of the radius of the scanning tip.

DHM Reflectometry retains DHM subnanometric resolution and large vertical measurement range capability and enables fast and complete 3D representation of the staircase.


Quality control to detect defect due to saw marks on solar wafer. Challenges of this measurement are listed bellow :

  • High throughput is strict requirement for this application. On flight measurement  is possible thanks to unrivaled acquisition speed of DHM
  • Solar wafer has a rough surface that produces speckle. A specific optical configuration allows DHM to extract precise profile cut
  • Measurement in production environment : presence of vibrations due to other
  • Enviroment de production -> seul systeme 3D qualifiable en prod

1 wafer 150mmx5mm en 0.7 secondes

Material and methods


remote TCP/IP control

Longueur d’onde synthétique : 30um ?? ou 60??

poids / dim ?

sample on conveyor / disp speed

measurement trig by optical barrier ->  fast stiching 50 images

Decision go/nogo based on topography


Belle image de profil

QC at highthroughput de 1 wafer /sec