Test and certification of refurbished process tools

What a test run adds to a refurbished tool

A refurbished tool has had its worn parts replaced, been cleaned and been recalibrated to the original specification. That tells you the hardware is right. It does not yet tell you what the tool does on a wafer. Test and certification closes that gap: we run the tool on a test process, measure the result and put the data in the report.

This is what separates our Certified grade from the Refurbished grade. The four grades and what each report contains are explained on how we inspect. Certification here means measured performance on an agreed test. It is not a third-party certification, and we do not present it as one.

Choosing the test

The useful test depends on the tool type and on what you will use it for. Typical examples:

• Etch and RIE tools: etch rate and within-wafer uniformity on a standard film, such as thermal oxide or silicon
• PECVD, sputter and evaporation tools: deposition rate, thickness uniformity and, where relevant, refractive index or sheet resistance
• ALD tools: growth per cycle and thickness uniformity on a known chemistry
• Furnaces and RTP: oxide thickness and uniformity, or temperature uniformity on a test wafer
• Mask aligners: intensity and uniformity across the exposure field, and resolution on a test mask
• Metrology tools: repeatability on a reference sample

We agree the process, wafer type and target values before the run. Where your recipe can be run before shipping, a test close to it gives you the most useful baseline. Some chemistries need gases or abatement that are only available at your site; in that case the test is done after installation.

Calibration first, and what happens if a result misses

Before testing, mass flow controllers, pressure gauges, temperature readings and RF delivered power are checked, so the test measures the process and not a calibration error. Safety interlocks are checked at the same time and recorded on a checklist.

After the runs, we measure the wafers with calibrated metrology and compare the results with the targets. If a result misses, we find the cause, fix it and run again. The report shows the final results and notes every rerun, so a pass on the second attempt is visible as such.

Typical downtime

On a tool we sell, testing happens before shipping and adds no downtime at your site. On your own tool, a test run is usually a short step at the end of a refurbishment or after commissioning and acceptance, and its length depends mostly on the number of runs and how long measurement takes.

What we need from you

• The process you plan to run, or the result you care about most
• Any target values from your own specification or from the tool's original acceptance data
• For tests at your site: test wafers, process gases and access to your metrology

Results and documentation

You receive the test plan, the parameter logs, the measured results and the interlock checklist, with the condition grade stated in writing. The same test, repeated after installation, gives you a direct comparison. This applies to single-wafer etch, deposition and thermal tools as well as aligners and metrology.