Testing semiconductor devices

Abstract

Abstract 1469486 Testing semi-conductor devices INTERNATIONAL BUSINESS MACHINES CORP 1 May 1974 [25 June 1973] 19037/74 Heading G 1 U [ Also in Division H1] In the manufacture of a semi-conductor device, such as an IGFET, having a phosphosilicate glass (PSG) film on an oxide layer to trap contaminants a test procedure is carried out to determine whether the amount of PSG present in the film is sufficient to trap all the contaminants present. The procedure comprises (1) determining the initial flat-band potential VFB across the film from a measurement of the capacitance-voltage characteristic C-V; (2) applying a fixed stress potential across the film for a time sufficient to polarize the film and at a temperature insufficient to cause drift of contaminants, up to 150‹C, but preferably room temperature; (3) remeasuring the flat-band voltage to determine the polarization of the film; (4) using the polarization value to determine the amount of PSG in the film, the Specification states that these parameters are directly proportional; (5) using the initial VFB and the polarization to calculate the amount of contaminant present, the formula for this calculation is given; and (6) comparing the amounts calculated in steps (4) and (5) to determine whether the former is sufficient to trap the latter. Wafers for which this is not so are discarded. In practice, since the only measurements made are of initial VFB and of polarization after application of the stress voltage the pass-fail decision can be based upon a single graph such as that shown in Fig. 7. Test MOS capacitors are preferably located in the kerf areas of wafers to be divided.

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