Charge-coupled device and process of making the device

Claim 1

A method of making a charge-coupled device, said method comprising the steps of: implanting a buried channel of a first conductivity type on a substrate of a second conductivity type; growing a gate oxide on the substrate over the buried channel; depositing successive layers of polysilicon, silicon nitride, and silicon dioxide over said gate oxide; defining a first gate electrode area by means of photoresist and removing the nitride and oxide layers in these areas to expose the polysilicon layers; implanting a material of said first conductivity type through the exposed polysilicon and through the gate oxide; defining a stepped potential region under said first gate electrode areas by means of photoresist; implanting a material of said second conductivity type in said stepped potential region; locally oxidizing exposed polysilicon and then etching to form a first gate electrode; defining a second stepped potential region adjacent said first gate electrode; implanting a material of said second conductivity type in said second stepped potential region; depositing a second polysilicon layer over said second stepped potential region to form a second gate electrode; and electrically connecting the first and second gate electrodes together.

Claim 2

A method of making a charge-coupled device, said method comprising the steps of: implanting a buried channel of a first conductivity type on a substrate of a second conductivity type; growing a gate oxide on the substrate over the buried channel; depositing successive layers of polysilicon, silicon nitride, and silicon dioxide over said gate oxide; defining a first gate electrode area by means of photoresist and removing the nitride and oxide layers in these areas to expose the polysilicon layers; implanting a material of said first conductivity type through the exposed polysilicon and through the gate oxide; defining a stepped potential region under said first gate electrode areas by means of photoresist; implanting a material of said second conductivity type in said stepped potential region; locally oxidizing exposed polysilicon and then etching to form a first gate electrode; defining a second stepped potential region adjacent said first gate electrode; implanting a material of said second conductivity type in said second stepped potential region; depositing a second polysilicon layer over said second stepped potential region to form a second gate electrode; and electrically connecting the first and second gate electrodes together.