Measurement and characterization of die temperature sensor

Die temperature sensor (DTS) is an electrical circuit in a silicon chip/ Die to measure its temperature while testing the device at various temperatures for its functionality before being shipped to the customer. DTS reading beyond the specification will lead to device being declared as failed for thermal test in production and scrapped after retest. Inaccuracy of the die temperature sensor may lead to scrapping of good devices. As temperature measurement through die temperature sensor is the only mode of measurement of temperature of the die, a characterization method has been developed to measure its accuracy by comparing with the package surface temperature. A study was performed on a low profile quad flat package (LQFP) and the results revealed DTS accuracy to be out of specification for some of the devices that failed during testing and for new products before introducing into production. This method has been established to check DTS failing potentiality of the devices and has resulted in significant saving of good devices being scrapped after testing and in optimizing calibration at wafer level for the devices with marginal failures.