Yield and Quality Engineer
Engineers who raise the share of good chips per wafer (yield) by tracking down the causes of failures through data and analysis, and turn them into process improvements and stable quality.
What the job involves
Yield and quality engineers raise yield, the share of good chips from each wafer, and keep quality stable. They combine wafer test results, data from defect inspection systems, metrology from each step and tool processing history to find where and why failures were created. For example, if failing chips cluster in one region of the wafer, a particular tool or step becomes a suspect. Once the candidates are narrowed down, they confirm the cause with physical analysis and agree on countermeasures with the owners of the steps involved. In volume production, another key role is using SPC (statistical process control) to catch process shifts early and build systems that prevent failures.
Who they work with and what they handle
Most causes lie in the process or the tools, so they investigate together with process engineers, equipment engineers and integration engineers. They also work with test engineers, who own the test results, failure analysis teams, who do the physical analysis, and quality assurance, who handle customers when problems appear after shipment. What they handle is large amounts of data: the distribution of failures across the wafer (wafer maps), defect locations and images, control charts and lot processing histories. Physical analysis includes, for example, cutting a cross-section with an FIB (focused ion beam) and imaging it with an SEM or TEM (transmission electron microscope).
Knowledge and skills
Statistics and data analysis are at the center. You need to be comfortable with variation, with telling correlation from causation, and with control charts and the process capability index (Cpk). Because the data volumes are large, some workplaces use database queries and programming languages for analysis in addition to spreadsheets. On top of that, understanding each process step and the structure of transistors and wiring lets you connect a data anomaly to a physical cause. When the cause is not obvious, persistence in forming hypotheses and checking them one at a time is essential.
Where to start
Start with the “Yield and quality control” field to learn how yield is defined, how defect density relates to chip area, and quality tools such as control charts. Ways to confirm a failure's cause are in “Metrology and analysis”, how test results are produced is in “Testing and inspection”, and the failure mechanisms that matter after shipment are in “Reliability”. For the process itself, take the “The fabrication process” course; for test and reliability in the back end, take “Back end, quality and safety”. “Lithography” and “Etching” come up especially often when thinking about pattern defects.
Fields to learn
Yield and quality control 50 questions Metrology and analysis 50 questions Testing and inspection 51 questions Reliability 51 questions Lithography 52 questions Etching 50 questions
10 starter questions for this role
Ten basic questions from the fields this role uses
Recommended courses
The fabrication processFollow the front-end process in order: wafers, cleanrooms, oxidation, lithography, etching, deposition, interconnects, metrology and yield.Back end, quality and safetyLearn what it takes to deliver chips as products: packaging and advanced packaging, testing, reliability, environment and safety, and industry trends.
Key terms
Yield Killer defect Systematic defect Poisson yield model Defect inspection system SPC (statistical process control) Control chart Process capability index (Cpk) Pareto chart FMEA (failure mode and effects analysis) FIB (focused ion beam) TEM (transmission electron microscope)
FAQ
Can I become a yield and quality engineer without a technical background or industry experience?
Statistics and data analysis are central to this role, so people with quality control or data analysis experience from other industries can find their skills useful. On the other hand, linking a data anomaly to a cause in the process takes knowledge of semiconductor processes and devices. Hiring requirements differ by company and change over time, but learning basic statistics and the process flow makes the role easier to enter from either side.
How is it different from quality assurance?
In general, yield and quality engineers focus on reducing failures inside the fab and stabilizing the process. Quality assurance guarantees that products meet specifications and customer requirements, and when problems appear after shipment, it often handles explanations to customers and coordinates the prevention of recurrence. The two are closely linked, and the titles and division of roles vary by company.
Do I need any license or certification?
In general, no specific license or certification is required for this role. Some people use certificates in quality control or statistics as a study goal, but how much they count in hiring differs by company. In practice, experience in tracking down causes from data and working with others to deliver improvements usually counts most.