Lsi Logic Corporation

Rajiv L Patel

Arvind Kamath

Ravindra Manohar Kapre

Mohammad R Mirabedini

Venkatesh P Gopinath

David Chan

Ken Rafftesaeth

A method for forming shallow junctions in a substrate. The substrate is masked with a first mask to selectively cover first portions of the substrate and selectively expose second portions of the substrate. A first dopant is implanted substantially within a first depth zone through the second portions of the substrate. The first depth zone extends from a first depth to a second depth, and the first depth is shallower than the second depth. The substrate is annealed for a first time to form a noncontiguous buried insulating layer substantially within the first depth zone in the second portions of the substrate. The substrate is masked with a second mask to selectively cover third portions of the substrate and selectively expose fourth portions of the substrate. The fourth portions of the substrate at least partially overlap the second portions of the substrate. A second dopant is implanted substantially within a second depth zone through the fourth portions of the substrate. The second depth zone extends from an upper surface of the substrate to the first depth. The substrate is annealed for a second time to activate the shallow junctions formed substantially within the second depth zone in the fourth portions of the substrate. The shallow junctions have a depth that is substantially limited by the noncontiguous buried insulating layer that starts at the first depth.

Shallow junction formation

A relatively thin gate insulator of a digital switching transistor is formed from a layer of silicon oxynitride which was initially formed by implanting nitrogen atoms in a silicon substrate and oxidizing the nitrogen and silicon. It has been discovered that an outer layer of silicon dioxide is formed as a part of the silicon oxynitride layer. Removing this outer layer of silicon dioxide from the silicon oxynitride layer leaves a thin remaining layer of substantially-only silicon oxynitride as the gate insulator. Thinner gate insulators of approximately 15-21 angstroms, for example, can be formed from a grown thickness of 60 angstroms, for example. Gate insulators for digital and analog transistors may be formed simultaneously with a greater differential in thickness been possible by using conventional nitrogen implantation techniques.

METHOD OF REDUCING SILICON OXYNITRIDE GATE INSULATOR THICKNESS IN SOME TRANSISTORS OF A HYBRID INTEGRATED CIRCUIT TO OBTAIN INCREASED DIFFERENTIAL IN GATE INSULATOR THICKNESS WITH OTHER TRANSISTORS OF THE HYBRID CIRCUIT

A shallow isolating trench is formed in a semiconductor wafer between active component areas to electrically isolate the active components from each other. The isolating trench is primarily formed of an insulating material, such as an oxide, in a recess formed into the wafer. An etch resistant material, such as BTBAS nitride, is placed over the insulating material in the recess. The etch resistant material protects the insulating material from erosion due to subsequent semiconductor fabrication process steps, so the integrity of the isolating trench and the planarity of the wafer are generally maintained.

Etch resistant shallow trench isolation in a semiconductor wafer

Silicon nitride gate insulators for digital transistors and silicon dioxide gate insulators for analog transistors of a hybrid integrated circuit (IC) are formed in a single integrated fabrication process. A first area of a silicon substrate of the IC is exposed while a second area is initially covered by a silicon dioxide layer. A layer of silicon nitride is formed on the exposed first area while the initial silicon dioxide layer inhibits the formation of silicon nitride on the second area. Thereafter the initial silicon dioxide layer is removed from the second area to allow a new silicon dioxide layer to be formed there from the exposed silicon substrate. The silicon dioxide layer shields against the adverse influences from silicon nitride formation and permits the initial silicon dioxide layer to be removed by etching. The silicon nitride layer shields against the adverse influences of oxidizing new silicon dioxide layer. A slight, beneficial silicon dioxide interface is created between the silicon nitride and the silicon substrate as a result of oxidizing the new layer of silicon dioxide.

Silicon nitride and silicon dioxide gate insulator transistors and method of forming same in a hybrid integrated circuit

Water for use in wet oxidation of semiconductor surfaces may be generated by reacting ultra pure hydrogen and ultra pure gaseous oxygen without a flame. Because no flame is used, contamination due to a flame impinging on components of a &ldquo;torch&rdquo; is not a problem. Flame-free generation of water is accomplished by reacting hydrogen and oxygen under conditions that do not result in ignition. This may be accomplished by provided a diluted hydrogen stream in which molecular hydrogen is mixed with a diluent such as a noble gas or nitrogen. This use of diluted hydrogen also reduces or eliminates the danger of explosion. This can simplify the apparatus design by eliminating the need for complicated interlocks, flame detectors, etc.

Growing community of inventors

San Jose, CA, United States of America

Rajiv L Patel