US 6,190,936 B1 · Interconnect passivation and metallization process optimized to maximize reflectance

Abstract

A metal surface having optimized reflectance is created utilizing the following process steps alone or in combination: 1) performing alloy/sintering of the metal-silicon interface prior to a chemical mechanical polish of the intermetal dielectric before the reflective metal electrode is formed; 2) chemical-mechanical polishing the intermetal dielectric layer again after vias are formed; 3) forming a metal adhesion layer composed of collimated titanium over the underlying dielectric; 4) depositing metal upon the adhesion layer at as low a temperature as feasible to maintain small grain size; 5) depositing at least the first layer of the reflectance enhancing coating on top of the freshly deposited metal prior to etching the metal; and 6) depositing the initial layer of the reflective enhancing coating at a temperature as close as possible to the temperature of formation of the metal electrode layer in order to suppress hillock formation in the metal. Deposition of the REC serves two distinct purposes. First, the REC coats the freshly deposited metal layer immediately following deposition, preserving the metal in its highly reflective state. Second, the REC generates constructive interference of light reflected by the metal layer. This constructive interference can generate reflectivity greater than that of the bare metal surface.

Claims23

Dependent claims

A process for forming a reflective electrode comprising the steps of:

forming a highest interconnect metallization layer over a silicon substrate having silicon-metal contacts;
forming a highest intermetal dielectric layer on top of the highest interconnect metallization;
heating the highest intermetal dielectric in the presence of hydrogen to alloy the silicon-metal contacts;
planarizing the highest intermetal dielectric after the heating step;
creating a via in the highest intermetal dielectric;
lining the walls of the via with a liner layer;
filling the via with an electrically conductive material;
forming an electrode adhesion layer on top of the highest level intermetal dielectric and the via;
forming an electrode layer on top of the electrode adhesion layer;
and
forming a reflectance enhancing coating on top of the electrode layer, the reflectance enhancing coating generating constructive interference of light waves reflected by the electrode layer.

8 more elements

A process for forming a reflective metal surface comprising the steps of:

providing a supporting surface having metal/semiconductor;
heating the supporting surface in presence of hydrogen to alloy the metal-semiconductor contacts;
chemical mechanical polishing the supporting surface after the heating step;
forming an adhesion layer;
depositing a metal layer on top of the adhesion layer at a first temperature, the first temperature as low as possible such that the grain size of the deposited metal layer is minimized;
depositing a reflectance enhancing coating immediately following deposition of the metal layer, the reflectance enhancing coating including a first dielectric film deposited on top of the metal layer at a second temperature as close as possible to the first temperature to suppress hillock formation in the metal layer, wherein the reflectance enhancing coating generates constructive interference of light waves reflected by the metal layer.

3 more elements

A process for forming a liquid crystal light valve having a plurality of reflective pixel electrodes, the process comprising the steps of:

forming a highest interconnect metallization layer over a silicon substrate having silicon-metal contacts;
forming a highest intermetal dielectric layer on top of the highest interconnect metallization;
heating the highest intermetal dielectric in the presence of hydrogen to alloy the silicon-metal contacts;
planarizing the highest intermetal dielectric after the heating step;
creating a via in the highest intermetal dielectric;
lining the walls of the via with a liner layer;
filling the via with an electrically conducting material;
forming an electrode adhesion layer on top of the highest level intermetal dielectric and the via;
forming an electrode layer on top of the electrode adhesion layer;
forming a reflectance enhancing coating on top of the electrode layer, the reflectance enhancing coating generating constructive interference of light waves reflected by the electrode layer;
and
defining a plurality of electrically isolated reflective pixel electrodes by etching the reflectance enhancing coating, the electrode layer, and the pixel adhesion layer in selected regions.

9 more elements

Dependencies are inferred from the claim text.

Interconnect passivation and metallization process optimized to maximize reflectance

Life of this patent

Interconnect passivation and metallization process optimized to maximize reflectance

Life of this patent

Abstract

Claims23