Browse Prior Art Database

Read Only Storage Masterslice

IP.com Disclosure Number: IPCOM000086310D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Balasubramanian, PS: AUTHOR [+3]

Abstract

A read-only storage (ROS) masterslice technique is described for personalizing an array of field-effect transistor (FET) devices, which have been previously formed on a semiconductor substrate.

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Read Only Storage Masterslice

A read-only storage (ROS) masterslice technique is described for personalizing an array of field-effect transistor (FET) devices, which have been previously formed on a semiconductor substrate.

Fig. 1 illustrates the cross-sectional view of a single FET device in a masterslice array of a large number of such devices, which have been stockpiled after fabrication for subsequent personalization. The device is formed on the P- type substrate 2 with source and drain diffusions 4 and 6 over which lies a layer 8 of silicon dioxide, over which lies a layer of aluminum 10 over the channel region 12 of the FET device.

Fig. 2 illustrates the state of the FET device of Fig. 1, which has been selected for deletion from the array of FET devices in the desired personalized ROS array. A suitable photolithographic mask is formed which isolates the aluminum gate layer 10 on the FET device of interest, so that the aluminum layer 10 may be removed by chemical etching techniques.

Fig. 3 illustrates the step of compensating the channel region 12 for a possible charge inversion with the subsequent formation of the glass layer 16 in Fig. 4, by ion implanting P-type ions such as boron through the gate oxide 14 into the channel region 12. This step is not necessary where the subsequently deposited insulating layer 16 does not accumulate a surface charge, such as for example polyimide.

Fig. 4 illustrates the final step forming a thick layer of glass or polyimi...