Laastotestejä

Laastotestejä, often translated as "chip tests" or "wafer tests" in English, refers to the process of testing semiconductor chips while they are still integrated on a silicon wafer. This is a crucial step in the semiconductor manufacturing process, occurring after the fabrication of numerous individual chips on a single wafer but before the wafer is diced into individual components. The primary goal of laastotestejä is to identify and reject defective chips at an early stage, thereby saving costs associated with further processing and packaging of faulty units.

During laastotestejä, automated test equipment (ATE) is used to probe each die on the wafer. Electrical signals are applied to the input/output pins of the chip, and the resulting outputs are measured and compared against expected values. Various types of tests are performed, including functional tests to verify the chip's intended operation, parametric tests to measure electrical characteristics like voltage and current, and sometimes memory tests or other application-specific checks.

Chips that fail these tests are marked, typically by placing a small dot of ink or by recording their location in a digital map. This ensures that these defective chips are not sent for dicing and packaging. The data gathered from laastotestejä is also invaluable for process engineers, as it helps identify recurring manufacturing issues and improve the overall yield and quality of the fabrication process. Efficient and accurate laastotestejä is therefore essential for the economic viability of semiconductor production.