Vapour phase decomposition ICP-MS

Vapour Phase Decomposition - Inductively Coupled Plasma - Mass spectrometry (VPD-ICP-MS) is a combined sample preparation and analysis technique which is used in the semiconductor industry to determine the concentration of metallic contaminants on the surface of silicon wafers and thin films. It allows for the extraction and quantification of metal contaminants at ultra trace levels.

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What is VPD-ICP-MS and how does it work?

Vapour Phase Decomposition (VPD) is a sample preparation method which dissolves and condenses any metallic impurities on a smooth surface into a droplet of solution. This allows for the extraction of said impurities, making them far easier to detect and identify, even when only present in ultra trace amounts.

The VPD process begins by exposing the surface of the substrate, usually a silicon wafer, to hydrofluoric acid vapour. This removes the layer of silicon oxide on the surface of the wafer, and dissolves any metallic impurities. The surface of the wafer is then scanned with a droplet of scanning solution. This effectively picks up the impurities into a single droplet.

The next step of the analysis is done using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). ICP-MS is an effective analytical technique that gathers data on the chemical constituents in a sample. The liquid sample gathered from the VPD of the silicon is injected into the mass spectrometer. Here, the sample is decomposed and ionized by plasma, before being passed into a vacuum chamber. The ions accelerate along the length of the chamber, where they are separated by their respective charges and masses. Once they reach the end of the chamber, they are detected and data is recorded. This allows the impurities to be separated, detected and identified, giving an insight into any contamination of the semiconductor.

What is VPD-ICP-MS used for?

VPD-ICP-MS is used to analyse the surfaces of silicon wafers and thin films in order to detect trace amounts of metal contamination. Metal contamination of semiconductors can severely impact their usability, hence this is an essential technique for monitoring and controlling wafer quality.

VPD is a very powerful technique because it extracts a wide range of contaminants from the surface of a semiconductor material. These are likely to include unwanted metals, and can have an impact on the functionality of the wafer. VPD condenses these trace elements so that they can be effectively analysed. This works well in conjunction with ICP-MS, which itself is ideal for detecting and quantifying very small amounts of metal impurities.

VPD-ICP-MS vs ICP-MS - what's the difference?

ICP-MS is a universal technique that can be used to analyse a wide variety of subject matter. It is particularly useful when it comes to detecting and identifying trace levels of elements, and has applications across biological, chemical and material industries. 

VPD refers more specifically to the process that prepares a material surface, such as silicon wafer, by decomposing and extracting any contaminants so that they can be analysed. This analysis can then be done through ICP-MS, hence creating a combined extraction-analysis method which is referred to as VPD-ICP-MS.

Sample requirements and preparation

In order for the VPD to be effective, the oxide layer of the silicon wafer is removed with hydrofluoric acid, and the impurities are collected with a droplet of scan solution. This means that the surface of the wafer must dissolve readily in the hydrofluoric acid vapour. In most cases, the surface of the wafer is composed of a sacrificial oxide layer, so this is no issue. 

Once the VPD has been completed, the sample is analysed through ICP-MS. This is a highly responsive technique which can be used on a wide range of subject matter. In terms of contaminants, most metals and some metalloids and nonmetals can be analyzed.

Need a VDP-ICP-MS analysis?

Measurlabs offers VDP ICP MS analysis services of high quality with fast results and affordable prices. If you have any questions about your sample or it’s suitability for the method, our experts are always happy to help. You can contact us through the form below or by emailing us at info@measurlabs.com

Suitable sample matrices

  • Silicon wafers
  • Thin films
  • Semiconductors
  • Solid materials
  • Materials contaminated with trace amounts of metals

Ideal uses of VPD-ICP-MS

  • Testing of silicon wafers for metal contaminants
  • Identifying issues which affect the quality of semiconductors
  • Detecting trace levels of metals

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Frequently asked questions

What is VPD-ICP-MS commonly used for?

VPD-ICP-MS is used to analyse the surfaces of silicon wafers and thin films in order to detect trace amounts of metal contamination. Metal contamination of semiconductors can severely impact their usability, hence this is an essential technique for monitoring and controlling wafer quality.

What kind of samples can be analysed with VPD-ICP-MS?

Suitable samples for VPD-ICP-MS-analysis are solid samples like silicon wafers, thin films and semiconductors with an oxide layer that can be removed with hydrofluoric acid. Only solid samples can be analyzed with this method.

What is Measurlabs?

Measurlabs offers a variety of laboratory analyses for product developers and quality managers. We perform some of the analyses in our own lab, but mostly we outsource them to carefully selected partner laboratories. This way we can send each sample to the lab that is best suited for the purpose, and offer high-quality analyses with more than a thousand different methods to our clients.

How does the service work?

When you contact us through our contact form or by email, one of our specialists will take ownership of your case and answer your query. You get an offer with all the necessary details about the analysis, and can send your samples to the indicated address. We will then take care of sending your samples to the correct laboratories and write a clear report on the results for you.

How do I send my samples?

Samples are usually delivered to our laboratory via courier. Contact us for further details before sending samples.

Vapour Phase Decomposition - Inductively Coupled Plasma - Mass spectrometry (VPD-ICP-MS) is a combined sample preparation and analysis technique which is used in the semiconductor industry to determine the concentration of metallic contaminants on the surface of silicon wafers and thin films. It allows for the extraction and quantification of metal contaminants at ultra trace levels.