Krishna G. Sachdev

Studies of adhesion of metal films to polyimide

Bonding of Cu/Cr films to several polyimides has been studied as a function of polymer surface modification by ion beam and chemical pretreatment. The effects of the metal deposition method and parameters have also been examined. The materials of interest include a low thermal expansion polyimide derived from 3,3’,4,4’‐biphenyl tetracarboxylic acid dianhydride‐p‐phenylene diamine (BPDA‐PDA) polyamic acid, and pyromellitic dianhydride‐4,4’‐oxydianiline (PMDA‐ODA) polyimide, formed from polyamic acid or polyamide ethyl ester precursors. The metal/polyimide adhesive strength was determined by the 90° peel test, while the interfacial regions were examined using x‐ray photoelectron spectroscopy and ellipsometry. It is found that for PMDA‐ODA systems, exposure to low energy Ar+ and/or O+2 ions improves adhesion of the metal overlayer, while for BPDA‐PDA polyimide, the role of O+2 is more significant. The fracture location is found to lie 20–300 A within the polymer, depending upon the ion beam dose and the spec...

Characterization of plasma-deposited organosilicon thin films☆

Abstract Preliminary experimental data on the chemical composition and properties of films 1200–2000 A thick from representative monomers of silanes, siloxanes and silazane are presented. Fourier transform IR spectroscopy, electron spectroscopy for chemical analysis (ESCA) and contact angle measurements were used to characterize the films as deposited at ambient temperature and after thermal treatment up to 300 °C. For an evaluation of the film integrity the relative pinhole density was determined using an electrolytic bubble trail technique. For the as-deposited films the elemental ratios derived from the ESCA study are similar to those calculated for the corresponding monomers. These analyses show that the post-deposition thermal annealing causes a significant change in the surface and bulk composition and consistently provides defect-free films.

New silicon containing positive resist and its applications for sub-half micron lithography

Abstract New silicon containing photosensitive polymers have been synthesized using poly(phydroxybenzylsilsesquioxane-co-p-methoxybenzylsilsesquioxane) resins as starting materials and partially replacing the available -OH groups with 2,1-diazonaphthoquinone sulfonyloxy moiety. Bilayer resist formulations derived from these polymers have higher sensitivity and contrast as compared to the resists based on silicon resins/PAC mixtures for sub-micron and sub-half micron I-line, DUV, and g-line lithography.

Non-Destructive Evaluation of Adhesion at Metal-Insulator Interfaces Based on Extremely-Low-Frequency Dielectric Spectroscopy

We present an application of Extremely-Low-Frequency Dielectric Spectroscopy as a non-destructive method to analyze corrosion-induced adhesion failure at metalpolymer interfaces. The Cu-Cr adhesion to polyimides (PI’s) is evaluated. Measurements are carried out in the frequency range 1 - 105 Hz as a function of temperature (308 - 623 K), moisture content (0 - 80 %) and time (up to 3 days). The dielectric response is shown to be determined by water diffusion into the PI under the metallization. A correlation between dielectric properties and the mechanical failure of the metallization is found, which is discussed in relation to potential applications in quality control.

Thermal transfer printing with heat amplification

A major advance in the field of thermal printing was the introduction of the QuietwriterR marketed by IBM which is based on resistive ribbon and utilizes the most advanced thermal printing technology. This printing technology is also termed Resistive Ribbon Thermal Transfer (R2T2) printing (1), because it is based on an electrically conductive ribbon. A recent detailed review of resistive ribbon printing is provided in ref. 2. In conventional thermal printing processes (3), the gating factor for the speed is the time it takes for the print head to cool down between cycles. Due to this limitation, the printing cycle for each successive printing element is about 2m seconds. A further drawback of this thermal printing technology, is the dependence of print quality on the type of paper used requiring very smooth paper for reasonable quality printing. This is probably due to inadequate heating of the ink resulting in high melt viscosity and consequently poor ink flow from ribbon to paper. This problem is alleviated in resistive printing where ink transfer temperatures are much higher than in the case of thermal head printing (4). In this technology the ink reaches temperatures far above the melting point of the ink. This is achieved by pumping enough energy into the ribbon to reach the necessary threshold temperature. however, there is a practical limit to the energy that the ribbon can withstand in a certain pulse without undergoing decomposition. Therefore, a need was recognized for approaches to improve thermal printing efficiency while minimizing the input energy requirement.