Passivation Coatings on Silicon Devices

Abstract

Passivation coatings are widely used to improve the performance and reliability of silicon devices of various types, ranging from discrete mesa‐type diodes and transistors to complex planar silicon integrated circuits, and including both hermetic and plastic‐encapsulated devices. This paper reviews the materials and techniques used to apply passivation coatings to completed silicon devices. Principal production techniques used in passivation of silicon devices include thermal oxidation, high‐temperature diffusion, high‐temperature chemical vapor deposition of Si3N4 or Al2O3 , low‐temperature chemical vapor deposition of glasslike SiO2 or phosphosilicate layers (deposited at approximately 400°C), rf sputtering of SiO2 , mechanical deposition of glass frit layers which are subsequently fused, and application of organic polymer films.The effects of passivation layers on silicon device reliability are discussed, and the interrelationships among the silicon device, the passivation layer or layers used and the final encapsulation are indicated. Pertinent references on passivation and on related topics are cited in the text.

High-Voltage Temperature Humidity Bias Test (HV-THB): Overview of Current Test Methodologies and Reliability Performances

“…Passivation coatings in silicon devices are generally divided into two categories: primary and secondary passivation layers. Primary layers are generally in contact with the bulk single crystal silicon, while secondary layers are generally separated from the bulk by at least one dielectric layer [54]. Both layers are important with respect to humidity related issues, since local immobile and mobile charges at their interfaces can have great impacts on device reliability.…”

“…Both layers are important with respect to humidity related issues, since local immobile and mobile charges at their interfaces can have great impacts on device reliability. Historically, SiO 2 was generally the standard primary passivation material, grown by thermal oxidation in a dry or wet oxidizing atmosphere [54][55][56][57][58][59][60], which was generally followed by an annealing step to improve layer stability and overall electrical properties of the device [54,[60][61][62][63][64]. The deposition of secondary passivation layers can have significant impacts on the electrical characteristics of the underlying layers.…”

“…), upper organic passivation layer (polyimide, etc.) and a final capping silicone gel or epoxy in the case of power modules, or molding compound in the case of plastic packages [54].…”

“…Silicon nitride Si 3 N 4 is generally involved in the fabrication of high-reliable devices, due to its multiple advantages. In fact, silicon nitride can act both as a getter and alkali barrier [54], and at the same time have great resistance with respect to humidity. Silicon nitride layers are usually formed by the reaction of either SiH 4 or SiCl 4 in an NH 3 atmosphere at 800-900 • C, or at lower temperatures by plasma enhanced chemical vapor deposition (PECVD) or even by atomic layer deposition (ALD).…”

Laser light spot mapping of depletion in power semiconductor devices

“…Control of surface fields in order to enhance stability and breakdown voltage is a major aspect of modern device technology and techniques such as surface contouring [21] or glass passivation [22] are widely used to mininiise surface fields. Depletion spreading has been directly observed by Electron Beam Induced Current Measurements (EBIC) [23] and direct voltage probing 1241.…”