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AssigneeU.S. Philips Corporation
InventorsJohannes J. M. Joosten, Cornelis L. M. van der Klauw
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Integrated circuits are arranged in a regular pattern on a semiconductor wafer. The circuits are separated from one another by kerf areas. These kerf areas are used to accommodate test structures from which process parameters can be derived. Because the surface area of these kerf areas is comparatively small, it is necessary to minimize the number of bonding pads or connection terminals for these test structures. The test system is extended with a multiplex circuit whereby a test structure can be selected from the test system and which connects one of the various test structures to always the same connection terminals. Furthermore, using one stimulus which is applied to a connection terminal and which is also the stimulus for the test structure whose response is to be measured, the desired test structure is selected. This is because the multiplex circuit detects on which connection point the stimulus is received and decodes the test structure to be connected to the connection terminals on the basis of the connection pin number.
A test system integrated on a substrate, for at least one of measuring and testing of parameters of respective test structures, the system having externally-accessible connection terminals coupled to the respective test structures via respective switches, for passing a test stimulus from the connection terminals to stimulate a selectable one of the test structures, the system comprising a multiplex circuit having amplifiers having the inputs coupled to said connection terminals and their outputs coupled for controlling closing and opening of the respective switches, the connection terminals being connected concurrently both to the respective test structures and to input terminals of the multiplex circuit for directing the multiplex circuit in controlling closing and opening of the respective switches, and the test stimulus on the connection terminals serving to select one of the test structures.
Dependencies are inferred from the claim text.