What is the project and purpose of "chip testing"?

Chip testing is an important part of the chip manufacturing process to ensure chip quality. Through comprehensive testing of chips, defects in the manufacturing process can be discovered and corrected, improving product yield and reducing production costs. The traditional meaning of chip testing is divided into wafer testing (referred to as intermediate testing) and finished product testing (referred to as final testing), both of which aim to ensure an increase in the yield rate of end products.

The process of chip testing is mainly divided into three stages: pre process testing, post process testing, and pre shipment testing.

Pre process testing: In each step of the chip manufacturing process, various parameters of the chip are tested. This includes multiple processes such as wafer preparation, mask lithography, etching, diffusion, annealing, and chemical mechanical polishing. Each process requires corresponding parameter testing of the chip to ensure that the quality and performance of the chip meet the requirements. The main testing items include wafer surface morphology, transistor electrical parameters, MOS gate quality, etc.

Post process testing: Various parameter tests performed on the chip during the final few steps of the chip manufacturing process. This includes multiple processes such as bonding, cutting, polishing, film deposition, and metalization. Each process requires corresponding parameter testing of the chip to ensure that the quality and performance of the chip meet the requirements. The main testing items include metal wire width, metal wire spacing, and uniformity of metal wire layers.

Pre shipment inspection: The final inspection conducted after the completion of chip production. The main task is to comprehensively test the various parameters of the chip to ensure that the quality and performance of the chip meet the requirements. The main testing items include electrical parameters, packaging quality, reliability, etc.

For the relevant indicators of chip testing, there is no unified testing indicator because different types and functions of chips have different testing items. Generally speaking, the indicators for chip testing may include testing stability, testing efficiency, defect coverage, false alarm rate, false alarm rate, etc. These indicators will be customized and optimized based on specific chip types and testing requirements.

1、 Test purpose

The purpose of chip testing is to verify whether the produced chips meet the original design requirements (spec requirements), screen and classify the chips through testing, sort out some defective products, promote good products to the market, and keep bad ones for subsequent analysis and processing, in order to improve the design or processing technology, and thereby increase the yield of the entire chip.

2、 Testing process

Wafer Probe

After the wafer fabrication is completed, thousands of bare DIEs (unpackaged chips) are regularly distributed throughout the entire Wafer. Due to the lack of wafer packaging, all pins of the chip are exposed, and these extremely small pins need to be connected to the testing machine through finer probes. The CP test is performed by connecting the exposed chip to the testing machine through a probe on the entire Wafer that has not been sliced and packaged.

Final Test

Final testing, also known as packaging testing, is carried out after the chip is packaged. The machine used is a testing machine (ATE) and a sorting machine (Handler). The chips that pass the test will be classified according to the test results, which is called BIN processing.

3、 Test indicators

Stability testing: The testing system can conduct stable testing to ensure the reliability of the test results.

Testing efficiency: The testing system can quickly complete testing and improve production efficiency.

Defect coverage: The testing system can detect as many defects as possible, improving the yield rate of the product.

False alarm rate: The testing system can accurately identify qualified and defective products, reducing false alarm rates.

Misreporting rate: The testing system can minimize the occurrence of missing defective products and improve product quality.

4、 Test content

Functional testing: Verify whether the functions of the chip meet the design requirements, and conduct comprehensive testing of all functions of the chip.

Performance testing: Verify whether the performance of the chip meets the design requirements, and conduct comprehensive testing on all aspects of the chip's performance.

Reliability and lifespan testing: Verify whether the reliability and lifespan of the chip meet the design requirements, and conduct tests on the chip under harsh conditions such as long-term operation, high temperature, and low temperature.

Packaging and appearance inspection: Verify whether the packaging and appearance of the chip meet the design requirements, and inspect the appearance and packaging quality of the chip.

In short, chip testing is an important part of ensuring chip quality. Through comprehensive testing of chips, defects in the manufacturing process can be discovered and corrected, improving product yield and reducing production costs. Meanwhile, by analyzing and mining test data, it can provide strong support for improving design or manufacturing processes, further enhancing the yield and performance of the entire chip.