Frank Stubhan

Moisture-resistant properties of SiNx films prepared by PECVD

The barrier properties of silicon nitride films prepared by plasma-enhanced chemical vapor deposition (PECVD) against moisture penetration were studied, with emphasis on the correlation of deposition parameters and moisture permeation rate. The moisture resistance of films have been characterized using infrared spectroscopy and determination of water vapor permeation (WVP) rate. Our results indicate that the gas flux ratio and discharge frequency are the most important factors in controlling the moisture resistance of these films. The best moisture-resistant property in terms of WVP and stability of the film is found in the film deposited in a low frequency (LF) process with lower ratio of silane to ammonia although the general trend is toward decreased WVP with a higher ratio of silane to ammonia in the films deposited freshly by both high and low frequency processes. Too high a ratio of silane to ammonia in LF processes leads to instability of the film after long exposure in a high humidity environment.

a-SiCx :H films deposited by plasma-enhanced chemical vapor deposition at low temperature used for moisture and corrosion resistant applications

Abstract Amorphous hydrogenated silicon carbide (a-SiC x :H) films were fabricated via plasma-enhanced chemical vapor deposition (PECVD) at a low substrate temperature. The properties of the film and their correlation with the deposition parameters were investigated with emphasis on moisture and corrosion resistance. The films can be deposited with good uniformity and repeatability. The moisture resistance is mostly influenced by the reactant gas flow ratio; increasing the silane flow enhances the moisture barrier ability of the film. The deposited film is chemically inert, is not oxidized by moisture at 85°C, and remained unattacked after 2 months immersion in water at room temperature. The film is pinhole-free, and has excellent corrosion resistant properties. Thus this material is deemed a good candidate film for moisture and corrosion resistant applications.

Moisture barrier properties of plasma enhanced chemical vapor deposited SiCxNy films on polyethylene naphthalate sheets and epoxy molding compound

Abstract Ternary Si–C–N films were produced in a radiofrequency plasma enhanced chemical vapor deposition reactor applying the precursor gases silane, methane, and nitrogen or ammonia. The properties of the films to function as external moisture barrier layers were investigated with emphasis on the correlation of deposition parameters and moisture permeation rate. The moisture penetration through the films has been investigated in water vapor permeation experiments and capacitance measurements from humidity sensors in plastic packages. The moisture resistance is mainly influenced by the stress in the films with best results for those samples exhibiting no or low compressive stress.

SILICON NITRIDE THIN FILMS PACKAGING FOR FLEXIBLE ORGANIC LIGHT EMITTING DEVICES

We present a simple thin film encapsulation technique for organic light emitting devices (OLEDS), for use in flexible flat panel displays (FPDs). We systematically studied the moisture-resistant properties of silicon nitride thin films prepared by plasma-enhanced chemical vapor deposition (PECVD) and found that silicon nitride thin films have a low water vapor permeation (WVP) rate even deposited at low substrate temperature (20°C). Then OLEDs prototypes were successfully packaged by depositing silicon nitride thin films on them. Based on the analysis of the degradation of the OLEDs, we found the lifetime of the encapsulated devices was increased by more than two orders of magnitude over that of the unencapsulated ones. Our results demonstrated the feasibility of thin film packaging for OLEDs and the possibility to realize the flexible FPDs.