Method of making integrated circuits using metal silicide contacts
AssigneeInternational Business Machines Corporation
InventorJacob Riseman
Life of this patent
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Abstract
A metal silicide contact to silicon devices which has broad application to almost all of the variety of silicon semiconductor devices is described. This contact with a substantial side component has particular advantage as the base contact for a bipolar transistor. However, contacts can be made to regions of any desired device regions with a variety of P+, N+, P, N, P-, N- and so forth conductivity types. Further, the contact can be an ohmic or Schottky contact.
Claims15
Method for making an electrical contact having a significant side component to a silicon semiconductor device comprising:
- forming a metal silicide contact on the surface of a silicon body;
- thermally oxidizing the surface of said metal silicide to form a silicon dioxide layer thereover and resulting in moving said metal silicide contact into said silicon body to the extent that said side contact component is formed greater than about 50 nanometers in depth;
- forming an opening in said silicon dioxide layer to said metal silicide;
- and
- making electrical contact to said metal silicide contact.
The method of forming a bipolar transistor with a highly conductive refractory metal silicide base contact having a significant side contact component, comprising:
- providing a silicon semiconductor body having a subcollector region and having on one major surface regions of monocrystalline silicond dielectrically isolated from other such regions;
- providing dielectric isolation between the emitter-base portion and collector reach-through portion of each of said regions designated to contain a bipolar transistor;
- sequentially depositing layers on said major surface of polycrystalline silicon and an insulator in that order;
- removing said layers of polycrystalline silicon and insulator and forming openings to said monocrystalline silicon above portions designated to be base contact areas and leaving said layer covering the designated emitter portion;
- forming the extrinsic base region of said bipolar transistor through said openings;
- forming a conformal insulator layer upon both the substantially horizontal regions and substantially vertical regions of said major surface;
- anisotropically etching said insulator layer to substantially remove said horizontal layer and to provide a narrow dimensioned vertical insulator on the vertical sidewalls of said monocrystalline silicon and said layers;
- depositing a layer of a refractory metal over said major surface;
- heating the structure to a temperature sufficient to cause the formation of a refractory metal silicide where said refractory metal is on said portions of monocrystalline silicon designated to be base contact;
- removing by etching the unreacted said refractory metal from over insulating layers;
- thermally oxidizing the surface of said refractory metal silicide to form a silicon dioxide layer thereover and resulting in moving said metal silicide into the said monocrystalline silicon and providing said base contact having a significant side contact component;
- reactive ion etching said major surface to remove said insulator layer covering said polycrystalline silicon layer over said designated emitter portion which leaves a portion of said silicon dioxide layer over said refractory metal silicide;
- forming the emitter region;
- nd making electrical contact to the elements of said bipolar transistor.
Dependencies are inferred from the claim text.