Evaluation of MEMS Device Materials by WDXRF

Evaluation of MEMS device materials by X-ray fluorescence spectrometers for thin films 

Rigaku Journal 36(1), 28-32, 2020 

Introduction

In the manufacturing process of semiconductor products, thin film inspection methods vary depending on the purpose. For example, optical such as ellipsometers, sheet resistance film thickness meters, step meters, and cross-sectional scanning electron microscopes (SEM) are used for film thickness management. For analysis of composition, X-ray photoelectron spectroscopy (XPS) or other techniques are used.

Among these techniques, X-ray fluorescence (XRF) spectrometers are used in many processes due   to the capability to perform simultaneous film thickness/ composition analysis non-destructively, with no contact and no sample preparation. The method is applicable to opaque films (metals or nitride films, etc.) and has excellent reproducibility. Special features of wavelength dispersive XRF (WDX; Wavelength Dispersive XRF) analysis are shown below;

  1. Analysis of light elements such as B, N and Al
  2. Sub-nm (A) level ultra-thin film analysis
  3. Analysis of layered and compound films

Due to these advantages, the use of WDXRF instruments has been increasing in recent years.

 

Applications of WDXRF to MEMS Device Materials

MEMS (Micro Electro Mechanical Systems) devices belong to the subject of the active research and investment in the semiconductor and electronic device fields. Their usage has been increasing for sensors in smartphones, game consoles, automobiles, actuators in printer heads and many others. Areas in which Rigaku WDX products contribute to their characterization include thickness analyses of Al processes for RF devices (SAW/BAW filters; Surface/Bulk Acoustic Wave), and simultaneous thickness and composition analyses of lead zirconate titanate (PZT) processes used as actuator materials. This paper introduces analysis examples of those materials.

 

 

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