Chemical Mechanical Planarization of Semiconductor Substrates – Inspection and Quality Control using AFM

By AZoM.com Staff Writers

Table of Content

Introduction
Application Overview – Tuning the CMP Slurry
About the P100AFM
Conclusion
About Ardic Instruments

Introduction

Chemical mechanical planarization (CMP) is a very important process in semiconductor manufacturing. The combination of mechanical abrasion and chemical etching enable polishing and flattening of wafers before the photolithography stage. This helps in avoiding the depth of field issues during illumination.

CMP has replaced processes such as borophosphosilicate glass deposition (BPSG) to become a fundamental process in the production of submicron multilevel VLSI due to its ability to produce globally planar wafers.

CMP is not just used to flatten the silicon dioxide inter-level diaelectrics (ILD), but is also used in flattening trenches filled with silicon dioxide in a technique called shallow trench isolation (STI). It is also possible to fill trenches with copper, tungsten or aluminium. Since IC designs include more layers and with nodes smaller than 10nm, the flattening process becomes even more important.

Application Overview – Tuning the CMP Slurry

A key factor in planarization quality is the composition of the CMP slurry. Working with a large chemical manufacturer, Ardic Instruments used the P100 AFM to analyze the surface roughness of wafers after planarization using a variety of their formulas.

By using the high resolution 3D data from the P100 scan, the arithmetic average of the 3D surface roughness (Sa) of each wafer was calculated. The AFM scan for sample 1 shown in Figure 1 had a surface roughness of 0.787nm, and sample 2 shown in Figure 2 had a surface roughness of 0.62nm, and sample 3 shown in Figure 3 had a surface roughness of 11nm. The surface roughness results provided to the chemical manufacturer were critical to the tuning of their CMP slurry design.

Figure 1. 2D and 3D AFM scan data of sample 1 with a surface roughness of 0.62nm

Figure 2. 2D and 3D AFM scan data of sample 2 with a surface roughness of 0.79nm

Figure 3. 2D and 3D AFM scan data of sample 3 with a surface roughness of 11nm

About the P100AFM

The P100 has a sub-nanometer Z resolution and can be used for high resolution imaging and measurement. The integrated low-noise and open-loop scanner enables quick and effective experiments up to 15µm by 15µm. The unique astigmatic optical design produces a small 0.56µm laser spot size, enabling users to experiment with smaller and faster AFM cantilevers.

Along with the P100 Ardic has a highly intuitive PSX control software, which allows the user to complete experiments with minimal training. The company’s one-click scan feature automates the setup and scan process, allowing users to quickly obtain high quality scan results. The built-in scan library management feature simplifies the flagging of scan data and allows the user easily delete or export scans.

Conclusion

The P100 AFM is a very useful tool to determine the surface roughness in the CMP application. Not only is the AFM helpful for the CMP chemical manufacturer, semiconductor process engineers can also leverage the AFM for quick and effective scans of 3D surface roughness. The P100 AFM was designed to require minimal training, enabling lab technicians to begin collecting data immediately.

About Ardic Instruments

Ardic Instruments is an analytical equipment manufacturer aiming to serve the global scientific community with the best customer experience possible. Through a transparent, accessible, and community-driven approach, Ardic Instruments fosters a direct channel of communication between the end-user and the manufacturer.

Ardic Instruments produces atomic force microscopes, MEMS analyzers, and label-free molecular diagnostic platforms for both academic and industrial applications.

This information has been sourced, reviewed and adapted from materials provided by Ardic Instruments.

For more information on this source, please visit Ardic Instruments.

 

Date Added: Sep 10, 2013 | Updated: Sep 13, 2013
Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Submit