In
a semiconductor production environment, it is mandatory to know if the produced
products are according specifications. With Automated Test Equipment, the semiconductor
industry products are tested, and decided if it failed or pass.
During the test process a lot of data is collected and saved for statistical
analysis. By analysing the data production errors can be detected at an early
stage and corrected accordingly.
With SEDana it is possible to do statistical analysis on data, which is generated
by Automated Test Equipment. SEDana is a stand alone aplication which can be
used by Engineers on the work floor.
This document informs you about the usabilitiy of SEDana and how this application can be used for statistical analysis of ATE tester data.
SEDana uses methods which are part of Statistical
Process Control (SPC).
SPC is a widely used set of methods for analysing production information and
using them for production control.
The combination of reading and analysing ATE tester data, combined with SPC
analysis, makes SEDana the ideal combination for the ATE industry.
Click here to read more about SPC
Using
SEDana for statistical analysis
When Automatic Test Equipment is used, a lot of
measured values and other information is stored for later analysis. In the early
days, only binning information was stored, it was time consuming to store more
information because of the cost and speed of info storage.
Nowadays it is much more easier and cheaper to store data. More and more complete
datasets of measurement data is stored for later analysis.
In combination with the improved calculation power of modern computers and SEDana,
application Engineers have the possibility to do this analysis 'real-time' on
the test floor.
SEDana is the connection between ATE data and
a complete printed or catchy digital report.
Just load raw data into SEDana, create a report with the tables, graphics and
diagrams you need and within minutes you can start analysing.
SEDana uses STDF
or CSV formatted input.
The STDF format is a standard format which is specified by Teradyne. The STDF
format is a de-facto standard widely used in the ATE industry.
CSV is known as comma separated file format. It could be handled by most spreadsheet
programs.
When a dataset is selected
and loaded into SEDana this data is visible in the raw data table. |
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| Statistical analysis starts with validating available data. Validating data means that the engineer can say something about the stability of the process and the usability of the data for further analysis.
In the Capability table all necessary information is displayed to give these
answers.
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| The variability of the measurements obtained by one appraiser
while measuring the same part repeatedly is called the repeatability of
a gage. This is also considered the 'inherent variability' of the gage.
The repeatability is commonly expressed as an index representing the width
of an interval containing 99% of the measurements. Assuming a normal distribution, 99% of the area under the probability density function is contained between -2.575 and +2.575 standard deviations. In the Repeatability table the engineer could see the variation of each test. The parameters for calculating the repeatability are typical values for the ATE industry. If needed these parameters can be changed. |
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Reproducibility is the variation in the average of measurements made by different appraisers, using the same instrument, measuring the identical characteristics on the same part. SEDana has the possibility for analysing multiple files. With this feature it is possible to combine different appraisers and show the results into a reproducibility table or reproducibility plot. |
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The Range Method is a gage study that will provide a quick approximation of measurement variability. This method will only provide the overall picture of the measurement variability. It does not decompose the variability into repeatability and reproducibility. Due to the fact that it's quick, the Range Method is to be used during the first iterations in optimizing GR&R during test program development. The range methods in SEDana are practical solutions to analyse the data of the used appraisers. When needed, it is possible to change limits, to see what the effects are on calculated results. The multiple Plots window gives one overview of the most important diagrams:
If needed, diagrams can be enlarged or shown in separate windows. |
At the end of each test, the binning gives the information about which device has passed and which one has failed. The Bin Pareto gives a clear view about how the devices binned. The 3-D Wafermap Presentation of the binning is possible when Wafer coördinate information is available. |
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Create
customized statistical reports with SEDana
SEDana is a quick and easy toolbox for statistical analysis of ATE data.After the analysis is done, it is important to get a report for further use and information of the measured data and the conclusions which are connected to it. The report generator adds all selected tables and graphs to one report. With this generator it is possible to create both digital and printed reports. The layout of the report is customizable. It is possible to save a report layout and use the same settings for other datasets. The Project option of SEDana creates a user friendly environment with predefined tables and graphs of actual raw data. This makes SEDana also a valid tool for people who don't have the knowledge for statistical analysis. |
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SEDana bridges the gap between raw tester data and statistical reports, which could be used for SPC analysis.
The power of SEDana is speed, simplicity and improved effciency. It brings 'real time' statistical analyis direct on the test floor.
With SEDana test engineers and production engineers have better tools for process analysis, process control and quality improvement.
SEDana is a product of Salland Engineering the Netherlands. Click here for SEDana product information.
