Method of making a transitor

Abstract

The invention relates to a method for manufacturing a transistor comprising the preparation of a stack of layers of the semiconductor on insulator type comprising at least one substrate on which an insulating layer and an initial semiconductor layer are successively disposed. The method includes the formation of at least one oxide pad extending from a top face of the insulating layer, the formation of an additional layer made from semiconductor material covering the oxide pad and intended to form a channel for the transistor, the formation of a gate stack above the oxide pad, and the formation of a source and drain on either side of the gate stack.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention concerns in general transistors of the metal oxide semiconductor field effect (MOSFET) type and more particularly the reduction of parasitic elements limiting the operating speed thereof.PRIOR ART[0002]In a MOSFET transistor a current is made to flow between a “source” electrode and a “drain” electrode under the control of a control “gate”, which creates a conduction channel between source and drain as soon as a sufficient voltage is applied thereto. The maximum switching speed of a MOSFET transistor depends on the speed with which it is possible to effectively establish the conduction current and make it disappear. It depends among other things on many physical parameters particular to the materials used, such as for example the mobility of the carriers of the semiconductor material used and the levels and type of doping of the various regions defining the electrodes. The switching speed also depends largely on the geometr...

AI Technical Summary

Benefits of technology

The present invention is suitable for preserving the thickness of an initial insulating layer on semiconductor on insulator substrates, such as silicon on insulator, without the need for etching the initial BOX layer to obtain a buried source and drain. This invention is compatible with substrates that integrate a thin or thick BOX layer. The technical effect is the improvement of the manufacturing process of MOSFET transistors where an initial cavity is formed in the semiconductor layer without the need for etching the initial BOX layer.

Problems solved by technology

Replacing the nitride does however significantly complicate the standard method for manufacturing MOSFET transistors.

This material does however lend itself much less well than nitride to the production of spacers and there does not currently exist any industrially reliable method that allows direct replacement of nitride.

This so-called “faceted epitaxy” technique is however particularly difficult to master.

Thus there are disparities in thickness between wide and narrow devices that may cause malfunctioning such as total siliconising and the appearance of leakage current that serious impairs the reliability of the devices.

From this brief presentation of the known methods for producing MOSFET transistors, it is clear that there do not exist any simple and reliable methods that make it possible to reduce both the access resistance of the source and drain electrodes and the stray capacitance between these electrodes and the control gate.

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