US 4,732,865 AGranted

Self-aligned internal mobile ion getter for multi-layer metallization on integrated circuits

AssigneeTektronix, Inc.

InventorsDavid R. Evans, James S. Flores, Susan S. Dottarar

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Abstract

A multi-layer metallization method and structure that permits the use of sodium-ion contaminated titanium-tungsten (Ti:W) as a barrier metal with gold conductor metal on a silicon substrate, without significant degradation of device characteristics. After depositing the barrier and conductor metal layers, a layer of phosphorous-silicate glass (PSG) is anisotropically-etched to expose the field oxide and top surface of the conductor metal but leave PSG layer on each sidewall of the metallization structure. The circuit is then annealed at 400.degree. C. for 30 minutes. Then, an adhesion layer (Si.sub.3 N.sub.4) and an insulative layer (SiO.sub.2) are deposited over the metallization structure and field oxide, with the adhesion layer in contact with the top surface of the conductor metal and the gettering composition. The resultant circuit has a field threshold voltage shift comparable to devices made without a metal-ion-contaminated barrier layer and the resultant structure reliably retains the PSG layers in contact with the metallization sidewalls.

Claims15

Dependent claims

In an integrated circuit fabrication process, a method of making a multi-layer metallization structure including a conductor metal and a barrier metal comprising a composition of titanium-tungsten which includes an amount of contaminant sodium ions, the method comprising:

depositing a layer of the barrier metal on a surface of a semiconductor substrate;
depositing a layer of the conductor metal on the barrier metal layer, the barrier metal layer separating the conductor metal from said surface;
patterning the conductor and barrier metal layers to define said structure along the substrate surface as a predetermined pattern of conductive interconnects and gate contacts having a pair of opposite sidewalls;
depositing a layer of a gettering composition over the substrate including in contact with each of the sidewalls of the metallization structure, the gettering composition being selected to react with and bind any of the contaminant sodium ions coming in contact therewith;
selectively removing a portion of the gettering composition layer to expose a top surface of the conductor metal layer while leaving a sidewall portion of the gettering composition layer contacting the substrate along each of the sidewalls of the metallization structure;
removing a portion of the contaminant sodium ions from the barrier metal so as to reduce the amount of said ions available to contaminate the semiconductor substrate;
and
depositing and adhering a layer of an insulative material onto the exposed conductor metal and the sidewall layers of the gettering composition.

5 more elements

depositing a layer of the barrier metal on a surface of a semiconductor substrate;
depositing a layer of the conductor metal on the barrier metal layer, the barrier metal layer separating the conductor metal from said surface;
patterning the conductor and barrier metal layers to define said structure along the substrate surface as a predetermined pattern of conductive interconnects and gate contacts having a pair of opposite sidewalls;
depositing a layer of a gettering composition over the substrate including in contact with each of the sidewalls of the metallization structure, the gettering composition being selected to react with and bind any of the contaminant sodium ions coming in contact therewith;
selectively removing a portion of the gettering composition layer to expose a top surface of the conductor metal layer while leaving a sidewall portion of the gettering composition layer contacting the substrate along each of the sidewalls of the metallization structure;
annealing the circuit to mobilize said sodium ions and caues a migration thereof into contact with the gettering composition sidewall portions so as to reduce the amount of sodium ions available to contaminate the semiconductor substrate;
and
depositing and adhering a layer of an insulative material onto the exposed conductor metal and the sidewall portions of the gettering composition.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/915,303Filed 3 Oct 1986
Granted: 22 Mar 1988
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H10W 74/43
Characterised by their materials: comprising oxides, nitrides or carbides, e.g. ceramics or glasses
H10P 14/412
Of conductive or resistive materials: deposition of metallic or metal-silicide materials
H10W 20/063
Of conductive parts of the interconnections: by forming conductive members before forming protective insulating material
H10W 20/064
Of conductive parts of the interconnections: by modifying the conductivity of conductive parts, e.g. by alloying