This section provides background information related to current based test technology and the application of it.
As long as manufacturing processes for the fabrication of integrated circuits (ICs) are not perfect, defects due to manufacturing imperfections will affect the ICs made and there will be a need for test to discriminate the good from the bad devices. Manufacturing defects can be categorized either as random defects or as structural defects. Random defects are due to material imperfections and cannot be avoided. They can be minimized by improving the process conditions and the processing materials used but can never be fully eliminated. Structural defects can be eliminated by root cause analysis and process adaptations as well as by making design rules more stringent.
Defects, whether random or structural, affect both the functional and parametric behavior of the devices that carry them.
For digital circuits, most manufacturing defects cause an increase in the quiescent supply current (so called IDDQ or ISSQ) drawn by the circuit or they cause a change in the switching current behavior (IDDT). Data to support this has been published and presented at various international forums. The figures presented in these papers typically show the efficiency of a given test strategy of identifying defective parts.
For analog circuits, fabrication defects either affect the DC or the AC current behavior. Aging also affects a devices supply current behavior.
Q-Star Test as a solution provider, offers total and customer-adapted solutions to implement and execute a supply or ground current based test strategy for analogue and digital Integrated Circuits in the most optimal way. Q-Star Test has experience in developing measurement modules and solutions which are applicable in a production test environment.
Q-Star Test owns a number of different supply current measurement technologies, covered by a set of strategic patents. These technologies allow the creation of high speed, high accuracy supply current measurement modules, with the unique characteristic that they are virtually transparent to the device under test.
This unique characteristic is important:
- to guarantee the test conditions
- to minimize the overall test slip-through
- to minimize false rejects
- to improve defect detection
Our products are a materialization of these measurement technologies.