SEMICONDUCTOR DEVICE WITH TEST STRUCTURE AND SEMICONDUCTOR DEVICE TEST METHOD

摘要

The invention relates to a semiconductor device comprising a test structure (100) for detecting variations in the structure of the semiconductor device, the test structure (100) comprising a first supply rail (110), a second supply rail (120), a ring oscillator (130) coupled between the first supply rail (110) and second supply rail (120), the ring oscillator (130) having an output (132) for providing a test result signal, and an array (140) of individually controllable transistors (142) coupled in parallel between the first supply rail (110) and the ring oscillator (130). Variations in the current output of the respective transistors (142) in the array (140) lead to variations in the respective output frequencies of the ring oscillator (130). This gives a qualitative indication of the aforementioned structural variations. More accurate results can be obtained by inclusion of a reference current source (160) for calibrating the ring oscillator (130) prior to the measurement of the current output of the individual transistors (142).