Yield Improvement = Increased Profit
How successful is the yield improvement in your company? Do you have multi-disciplinary teams working together on the same data to prove the true root cause and fix the issues that return the most for the invested time? If so then well done, keep it up and speak with us about how we can help to accelerate that process. If you are constantly “firefighting” (dealing with today’s issues) you will not have time to fix the long term issues that can increase profit the most. yieldHUB can help.
yieldHUB and the team at MFG Vision can help you to set-up or improve your yield improvement. We recommend the following steps:
1. Identify which are the long term issues (e.g. Bin Pareto of 10,000 wafers is a good place to start)
2. Rule out as many causes as possible (e.g. Run automated ANOVA to compare variation from many sources, including tester, subcon, final test lot, fab lot, wafer number…)
3. Focussing on the 1 or 2 key items check re-test data to see retest pass rate.
4. Focussing on the 1 or 2 key items check the stability of the testing
5. Correlate the final test data to probe and to Fab
6. Share the results instantly with colleagues across the team to understand what can be done to fix the issue.
7. Record the improvement in the same system to build a knowledge base and speed up the next improvement.
Quality Improvement = Compliance & Increased Reputation
Improving yield will directly impact on quality. With yieldHUB historical data is all online for RMA analysis. And then MFG Vision can help you go further. Preventative yield management controls the long term yield not only reacting to today’s issues. MFG Vision can also support you to work to automotive standards including “Part Average Testing” and to aerospace standards including “Lot-to-lot, Lot Norm” and “Within Lot, Lot Norm”. Other well known statistical methods can be implementing such as Statistical Bin Limits and Statistical Yield Limits. Focusing on true maverick material and not the noise of common failure modes will help to focus your effort and improve your quality.
Cost Saving = Yield Management
The biggest cost savings are when you move beyond yield improvement into yield management. Yield improvement by its very name states that yield needs to be improved therefore loss has already taken place. Yield management is about preventative action to maintain high yields and maximise yield and therefore gross margin.
yieldHUB is a system developed with yield management at its core. Automated reports provide the information about trends and status of last week, last month etc… Updated Paretos on these charts point to the long term key issues. Alongside these are automated alerts, set by your engineers without the need to write scripts. Your engineers can set escalation levels for alerts to react to shifts in parameters, increases in failure modes and decreases in yields. Automation of the commonly carried out analysis means that engineers are freed up to work on the chronic issues and preventative measures.
Time Saving = Greater Efficiency
Following traditional methods and using stand alone tools in order to improve or manage yield is a time consuming process. Huge amounts of engineering time are put into moving data around in order to find the issues and more effort to understand the issues. With MFG Vision systems taking care of the data management our customers tell us that more than 20% of an engineer’s time can be saved.
The other type of time saving that MFG support our customers on is test time reduction. Understanding how to quickly analyze the data from your test program in order to assess any change quickly means that test times can be reduced. Analysis of “tests that never fail” can help to identify where over testing occurs. And support for analysis of multi-site testing will help you achieve the greatest efficiencies on the test floor.
Ramp up, faster yield stabilization = greater profits
A key time in the life of any product is the ramp-up phase. As a product ramps it is also the time when the selling price is the highest and the yield is typically the lowest. The earlier in the ramp-up phase that yield is stabilized the more profit will be increased.
The yield of the product is dependent upon a number of things. Each of these can be taken in isolation if the problems can be traced to one of these.
1. Design – careful characterization of the design before ramp-up will help to stabilize yield more quickly.
2. Fab Process Control – This may be our of your hands, or your key responsibility, either way correlation of data from final test and wafer sort back to the fab will prove the relationship between fab process and product yield.
3. Testing – The testing itself can be a key factor in product yield. Assessing the test facility before production is a major step towards stabilizing the yield quickly. gageHUB is a system developed and used specifically for this purpose. Eliminate the false fails and focus on the real issues.