SEM Cleaning for Improving Imaging in the Semiconductor Industry

By AZoNano

Table of Contents

Introduction
SEM Cleaning Equipment – The GV10x DS Asher
Case Study
Conclusion
About IBSS Group

Introduction

There has been a tremendous growth in the field of nanotechnology in the past few decades and the semiconductor industry is advancing towards smaller and smaller components. This has resulted in the need for more resolution and magnification. Scanning electron microscopes or SEMs are used extensively to observe surface features at magnifications in the range of 200,000x. A key reason for not being able to increase magnification and resolution in SEM imaging is because of hydrogen contamination in the SEM vacuum chamber. The settling of contamination on the analyte surface causes polymerization because of interaction with the electron beam and a non-conductive layer is formed that when imaged looks like a black rectangle and does not permit consistent measurements.

SEM Cleaning Equipment – The GV10x DS Asher

The GV10x Downstream (DS) Asher 2009 was introduced by ibss and it is employed by the semiconductor industry to remove hydrocarbon contamination from review SEMs and CD-SEMs. As the SEMs are designed for studying large semiconductor wafers, the size of their vacuum chamber is more than that of standard SEMs. So the industry needed a better technique for hydrocarbon cleaning and the same was fulfilled in the GV10x DS Asher.

The equipment has a novel patented design and can operate at pressures below other commercially available contamination removal systems. Hence it is possible to remove hydrocarbons effectively and uniformly from large chambers. According to ibss, the GV10x DS Asher can effectively clean standard SEMs as well as clean the large chambers of review SEMs and CD-SEMs. As the equipment has high-efficiency, the system downtime is considerably reduced. The GV10x cleaning cycle involves the time taken by the user to prepare the SEM for cleaning, cleaning of the SEM and allowing the SEM to return to its normal operation mode. This cleaning cycle is considerably substantially reduced as the GV10x operates at pressures safe for turbo molecular pump operation.

Case Study

The GV10x was used by Gerald Neumann at Infineon in Munich, Germany to remove carbon from his SEM, which he uses for the study of semiconductor components. If the GV10x is not used, just 1 minute of scanning at 200,000x magnification will cause hydrocarbon contamination that will completely block the surface being studied.

After 10 minute cleaning it was observed that 1-2 minute scans at 200,000x magnification can be done without any contamination effects seen. According to Mr Neumann the GV10x has very rapid and effective cleaning. With active turbo pumps, cleaning can be performed and begins without venting the chamber.

Figure 1. SEM Images taken at 200,000x magnification with scan time = 1 minute. The left image was taken before GV10x cleaning and the right image (different section of sample) was taken after a 5 minute clean. (Courtesy Infineon Technologies)

The GV10x was also used by Pierre Hovington in Hydro Québec in Canada where he studied particles using the SEM. According to him, in case samples were studied for a longer period the image contrast on his SEM reduced. Also in cases of high magnification examination, the tell-tale dark areas, indicative of hydrocarbons, will be seen on the sample. After the SEM is cleaned with the GV 10x, the contrast loss was no longer seen and the sample’s dark area was also removed.

The ibss GV10x DS plasma cleaning system was very good for cleaning hydrocarbon contamination in the scanning electron microscope. It will be very important for in-situ analyses and the system can be used at relatively high vacuum, enabling decontamination in situ samples without cooling/reheating of the objective aperture.

Figure 2. EM images taken during 2 hour examination before (left) and after (right) a 30 minute GV10x cleaning. (Courtesy Hydro- Québec)

Conclusion

The ibss Group has introduced a novel and more efficient method of removing hydrocarbon contamination from SEMs and other analytical systems with the GV10x. The case studies prove that the GV10 x is a highly efficient tool for SEM cleaning and will help in obtaining improved resolution and magnification of the SEM.

About IBSS Group

Vince Carlino founded ibss Group, Inc. in 2002, to turn brilliant ideas into affordable tools. In 2007 ibss Group began cooperating with an inventor of a unique, patented plasma source. ibss Group developed and produced the GV10x, a new paradigm in situ downstream plasma asher. Competitively priced, the GV10x Downstream Asher reduces carbon & hydrocarbon contamination 10 to 20 times more effectively than traditional methods at vacuum pressure safe for TMP operation.

Competitively priced, the GV10x Downstream Asher reduces carbon & hydrocarbon contamination 10 to 20 times more effectively than traditional methods at vacuum pressures safe for turbo molecular pump (TMP) operation. Artifacts in SEM images are gone; the microscope maintains high resolution and beam stability. Black scan squares are eliminated in SEM images. Carbon contamination in FIB and TEM systems can be controlled as well.

The GV10x, when coupled to the Gentle Asher™ Chamber, can clean specimens prior to examination. Reports from customers claim that this combination mitigates carbon on TEM holders/specimens and SEM samples with less damage and at less than ½ the cost of typical 'plasma cleaners'.

This information has been sourced, reviewed and adapted from materials provided by IBSS Group

For more information on this source, please visit IBSS Group.

Date Added: May 15, 2013 | Updated: Jun 11, 2013
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