Metal silicide channel stoppers for integrated circuits and method for making the same
AssigneeInternational Business Machines Corporation
InventorsGeorge R. Goth, Thomas A. Hansen, Robert T. Villetto, Jr.
Life of this patent
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Abstract
Disclosed is the use of metal silicide (e.g. Pt-Si) contacts in boron lightly doped P.sup.- type silicon between two contiguous but not adjacent N.sup.+ type regions instead of employing the usual P.sup.+ implanted or diffused channel stoppers. The invention finds a particularly interesting application in polyimide filled deep trench isolated integrated circuits. The trench sidewalls are coated with an insulating material which is removed from the trench bottom at the all contact etch step. The Pt-Si is formed at the bottom of the trenches at the same time that the device contacts are made.
Claims12
The method of forming a channel stopper at the bottom of an insulating trench formed through a N type conductivity layer into a lightly doped P.sup.- silicon substrate in an integrated circuit comprising the steps of
- coating said trench with an insulating layer;
- removing said layer at least from the bottom of said trench;
- and
- forming a channel stopper solely by depositing an appropriate metal at the bottom of said trench where said insulating layer was removed and sintering said metal with said silicon substrate to form a metal silicide rectifying contact.
In a method of forming deep trench isolated devices, according to which isolation trenches are formed through a passivated N type conductivity layer into a lightly doped P.sup.- substrate, defining isolated pockets containing active and/or passive devices, the improvement comprising the steps of:
- coating the sidewalls and bottoms of said trenches with a thermally grown SiO.sub.2 layer;
- etching all contact openings, at the areas where a contact with the silicon substrate is needed, including said bottoms of trenches;
- blanket depositing a layer of an appropriate metal on said areas;
- sintering said metal with silicon to form metal silicide rectifying contacts at least at the bottom of the trenches, whereby channel stoppers are formed solely by said deposited and sintered metal;
- and
- removing unreacted metal silicide.
Dependencies are inferred from the claim text.