Bell Telephone Laboratories

At&t Bell Laboratories

Shyam P Murarka

Hyman J Levinstein

Ashok K Sinha

Robert B Marcus

James A Cooper, Jr

David B Fraser

Arthur C Adams

Dawon Kahng

Chuan C Chang

Richard S Wagner

Cesar D Capio

David S Williams

Moshe Eizenberg

It has been found that stress in X-ray transparent films used to form masks for X-ray lithography also cause distortions of the film and of the high-resolution X-ray-absorptive pattern formed thereon. A method is disclosed which anneals boron nitride films for use in X-ray masks in such a way as to control stress.

Boron nitride X-ray masks with controlled stress

Annealing a titanium-rich carbide film deposited on silicon produces, in a single processing step, both a stable titanium silicide contact and a titanium carbide diffusion barrier between the silicide and a subsequently formed overlying layer of aluminum. Reliable low-resistance contacts to VLSI devices are thereby provided in a cost-effective fabrication sequence. Other metallization systems, comprising a silicide and a diffusion barrier to aluminum formed in a single processing step, are also described.

Forming low-resistance contact to silicon

In order to form MOSFET structures, a cobalt layer (16) is deposited and sintered, at about 400.degree. C. to 500.degree. C., on a patterned semiconductor wafer having exposed polycrystalline (14) or monocrystalline (11) silicon portions, as well as exposed oxide (15 or 25) portions. The cobalt reacts with exposed surfaces of the silicon portions and forms thereat such compounds as cobalt monosilicide (CoSi) or di-cobalt silicide (C0.sub.2 Si), or a mixture of both. The unreacted cobalt is selectively removed, as by selective etching in a suitable acid bath. A heat treatment at about 700.degree. C. or more, preferably in an oxidizing ambient which contains typically about 2 percent oxygen, converts the cobalt compound(s) into relatively stable cobalt disilicide (CoSi.sub.2). Subsequently, deposition of an in situ doped layer (33) of polycrystalline silicon (polysilicon) on the cobalt disilicide contacting the monocrystalline silicon portions--followed by gettering, deposition of a layer (34) of aluminum, and standard etch-patterning of the aluminum and polysilicon layers--completes the metallization of the desired MOSFET structures on the silicon wafer.

Cobalt silicide metallization for semiconductor integrated circuits

Silicon-rich silicides of titanium and tantalum have been found to be suitable for use as the gate metal in semiconductor integrated circuits replacing polysilicon altogether. Such silicon-rich silicides, formed by sintering a cosputtered alloy with silicon to metal ratio of three as in deposited film, are stable even on gate oxide. The use of these compounds leads to stable, low resistivity gates and eliminates the need for the high resistivity polysilicon gate.

Silicon rich refractory silicides as gate metal

The compounds TiSi.sub.2 and TaSi.sub.2 have been found to be suitable substitutes for polysilicon layers in semiconductor integrated circuits. Suitable conducting properties of the compounds are ensured by providing a relatively thin substrate of polysilicon.

Method for making integrated semiconductor circuit structure with

A method for making a MOSFET device (20) in a semiconductor body (10) includes the step of forming source and drain contact electrodes (12.1, 12.2) prior to growth of the gate oxide (10.3) and after formation of a high conductivity surface region (10.5). The exposed mutually opposing sidewall edges of each of the contact electrodes (12.1, 12.2) are coated with a sidewall silicon dioxide layer (15.1, 15.2), and the then exposed surface of the semiconductor body (10) between these sidewalls is etched to depth beneath the high conductivity surface region (10.5) in order to separate it into the source and drain regions (10.1, 10.2). Formation of the high conductivity region may be omitted by using Schottky barrier or impurity doped material for the contact electrodes (12.1, 12.2).

Method of fabricating MOS field effect transistors

Integrated semiconductor circuit structure and method for making it

Many of the stacking faults which occur after oxidation of silicon wafers are substantially eliminated by the use of an argon-hydrochloric anneal of the wafers just prior to oxidation. This anneal, which is carried out in the same chamber in which oxidation is carried out, removes impurities from the surface of the wafers and thereby limits the sites at which stacking faults form after oxidation.

Method of limiting stacking faults in oxidized silicon wafers

Disclosed is a method and structure for protecting circuit components from the ambient and in particular for protecting the contact metal from the adverse effects of moisture. A first layer of amorphous silicon is deposited over the circuit including the metal contacts. A second layer which may be silicon nitride or silicon dioxide is then deposited over the amorphous silicon. The amorphous silicon layer reduces cracking in the second layer and prevents cracks in the second layer from propagating to the circuit components.

Growing community of inventors

New Providence, NJ, United States of America

Shyam P Murarka