Temperature Forcing System
The semiconductor industry chain is very long, but from the perspective of chip testing, the chip manufacturing process can be divided into several stages such as wafer manufacturing, wafer testing, chip packaging, and finished product testing. Among them, the wafer test is completed through ATE and Prober; the finished product test is completed through ATE and temperature forcing system.
First, from R&D to mass production, testing is a key and necessary link
Because chip testing accounts for a relatively small proportion of the total chip manufacturing cost, in the range of a few percent, it is usually ignored by many chip design companies. But in fact, chip testing is a key link from R&D to mass production. First of all, we guarantee the quality of the product through the dual steps of wafer testing and finished product testing. Secondly, the pros and cons of the test scheme directly affect the level of the good ratio and the size of the test cost.
Chip testing is a relatively complicated task, which involves many aspects such as test equipment, test procedures, test parameters, test conditions, test methodology, new product mass production introduction process and system, chip function and performance verification, test data analysis, etc. . In order to develop a set of high-quality test solutions, developers need to be familiar with the functions of the tested chips, the performance of the test equipment used, a sound theoretical knowledge of semiconductor testing, and rich practical experience in mass production test development.
The work of test engineering focuses on the development and execution of test plans, including three main ATE test programs: programs for reliability testing, programs for chip verification, and programs for mass production.
Second, there are different expectations for ATE test scenarios
First, Reliability Testing Expectations for ATE Test Scenarios
1. Very fast locking inspection procedure. Before and after the reliability test of the chip, we need to use the ATE program to collect the drift of the test results of the chip on key parameters. Some reliability test items take a long time to test. Only by locking the ATE QUAL test program as early as possible can the reliability test be started, so as to know whether the reliability design of the chip meets expectations as early as possible.
2. Sufficient coverage. A program without sufficient coverage will lose the monitoring of test results for some key parameters of the chip, thereby ignoring potential quality risks.
3. Precision. We need a certain accuracy to track the drift of key parameters, and the accuracy of the test should be able to quantitatively reflect the change of the trend.
4. Stability. Are the results of multiple measurements of the same parameter of the same chip consistent? Are the results consistent on different test machines? On the same machine, are the test results obtained by using different test fixtures consistent? Are the test results of different stations on the same machine and the same fixture consistent? These are the data we need to collect and analyze.
The AES series produced and developed by our company is a sophisticated temperature forcing system with a wider temperature range of -70°C to +225°C, providing very advanced temperature conversion testing capabilities. The temperature can be switched from -115°C to +225°C within 10 seconds; after long-term multi-working condition verification, it can meet the requirements of various production environments and engineering environments. AES is purely mechanical refrigeration without the need for liquid nitrogen or any other consumable refrigerants. It cooperates with ATE to conduct reliability tests such as characteristic analysis, high and low temperature temperature change test, temperature shock test, and failure analysis.
Second, verify the test’s expectations for the ATE test protocol
1. Complete coverage. CHAR test program is the largest and most complete ATE test program in one project. Its function is to do the most complete detection of each ip and parameters of the chip under different test conditions. The test results obtained by the CHAR program at different process corners, different voltages, and different temperatures help us conduct a “all-round physical examination” of the chip.
2. Very precise. We have higher expectations for the accuracy of the CHAR test results than the QUAL test procedure. Since the CHAR program is not used in mass production and is not sensitive to test time, in order to analyze the performance of the chip more accurately, we can set a more accurate measurement gear, take more sampling points for averaging, and predict Leave more wait time/setting time and other methods to achieve the most accurate results that ATE instrument can do.
3. Stability. As with the QUAL program, we also need stable ATE test results.
Finally, production test expectations for ATE test solutions
1. Minimum cost. In any mass production, production cost must be our top priority. Therefore, we need to use “the most suitable rather than the most expensive and high-end ATE test equipment” to develop mass production test solutions.
2. Very stable. Among the three ATE test procedures, the “mass production test procedure” has the highest requirement on stability. This is because the stability of the test results greatly affects the yield rate of mass production, and the yield rate is also indirectly converted into the manufacturing cost of the chip, and at the same time affects the production capacity and delivery of the product.