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Increased Transfer Efficiency for CCD Structures

IP.com Disclosure Number: IPCOM000078659D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Chang, WH: AUTHOR [+2]

Abstract

This technique using ion implantation to compensate the surface concentration of the region between adjacent electrodes in charge-coupled devices (CCD), increases transfer efficiency without further reducing the electrode spacing, and also provides design compatibility for integration of C:CD and field-effect transistors (FET's).

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Increased Transfer Efficiency for CCD Structures

This technique using ion implantation to compensate the surface concentration of the region between adjacent electrodes in charge-coupled devices (CCD), increases transfer efficiency without further reducing the electrode spacing, and also provides design compatibility for integration of C:CD and field-effect transistors (FET's).

Fig. 1 shows a portion of a CCD including semiconductor substrate 1, insulating material 2 and phase electrodes 3. For a given substrate doping level, the normal approach for increasing the transfer efficiency of CCD's is to reduce the separation between adjacent electrodes 3 to a minimum, set by mask and etching tolerances. Such an approach invites difficulties, such as, shorts between electrodes, poor reproducibility, and extra process steps, etc.

The use of ion implanted regions 4 between adjacent electrodes to compensate, or to effectively lower, the surface concentration in the region between electrodes, allows the lowering and tailoring of the surface potential barrier in such a way as to enhance the charge transfer. The result is an increase in the transfer efficiency, without further reducing the interelectrode spacing.

The use of intrinsic compensation, allows the use of higher substrate doping levels required by enhancement mode FET's on the same integrated circuit chip and, therefore, allows both types of devices to be used together. Fig. 2 shows the surface potential in the sem...