What is DFT?

Design for testability is a design technique that modifies a chip such that the testing process becomes easier and more cost-effective by adding extra circuitry to the chip. With the help of DFT techniques, the controllability and observability of the internal fault nodes are improved.

This is where the industry needs test engineers who can generate test vectors after the design is completed. But this approach will consume a substantial amount of time and effort that could be avoided if testing is considered at an early phase in the design flow (i.e.) Integration of design & test called DFT (Design for testability).

Why is DFT important?

Due to development in technology, billions of transistors are being tightly packed in a small tiny chip giving rise to additional challenges, so the chances of defects are also more. Testing is required to ensure the quality of the product. During the fabrication process, several types of defects may exist which may result in the destruction of some of the transistors on the chip.

It is necessary to test each and every chip for its performance and functionality before it is shipped.

How to prepare for the DFT Interviews?

DFT interviews are based on the DFT concepts and DFT tool knowledge.

After you are trained with the DFT concepts, you need to make sure that you have more hands-on experience with the different DFT tools.

Hands-on knowledge in DFT topics like ATPG flow, Scan chain flow, and MBIST flow is highly ne

What is expected from the DFT Interviews?

The interviewer checks your DFT concepts in ATPG, Scan chain, Boundary scan, MBIST, etc. They also expect you to be hands-on with the DFT tools. You should be aware of the following test scenarios:

DRC violations analysis and fixing the same
Simulation mismatch debugging
Test coverage improvem

Learning programs for DFT

DFT Verilog Interview Questions and answers

Conclusion

It’s good to be trained in both Design and testing that is what we call Design for Testability where you learn how to fix RTL design issues and also integrate the DFT techniques into the RTL for making the chip testing easier after the chips are manufactured. We make sure that only good chips are shipped to the customer.

More VLSI interview questions

System Verilog

SystemVerilog is the most transformative technology in EDA since the birth of logic synthesis. It is commonly used in the semiconductor and electronic design industry as an evolution of Verilog.

Physical Design

VLSI physical design is the process of creating the layout of the IC, and VLSI verification is the process of checking that the IC functions correctly.

UVM

UVM is a Standard Verification Methodology that uses System Verilog constructs based on which a fully functional testbench can be built to verify the functional correctness of the Design Under Test(DUT).

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