| 摘要 |
<p>PURPOSE:To positively and easily perform the separation of the good chips from the bad and to obtain the higher reliable chips by a device wherein a shield layer is formed through the medium of an insulative layer on a high pressure-resistant MOS circuit region such as PLA and given bias voltage is applied to a pad connected to the shield layer. CONSTITUTION:In IC having PLA formed of a P channel MOS, for examle, an Al wiring 7 is provided on the circumstance of ROM including peripheral circuits 31, 32 such as decoders and a shield Al film 6 is formed on the main ROM. The Al film 6 is connected to a pad 5a via a cross-under wiring 9, while a pad 5b is led out from the wiring 7. For the probing test, vias voltage several V than the given Vth is applied to the pad 5a and the pad 5b is grounded, thereby to perform the selection test for deciding whether there exists a partially lowered point of Vth (parasitic channel) in a field film or not. As to the good chips, the pads 5a, 5b are connected to the ground level for purpose of reducing an influence due to charges. In this manner, the working efficiency can be improved and higher reliability can be obtained.</p> |
