Diffusion Bonding Performance of Copper Target for 300mm Integrated Circuit

Ultra-pure copper sputtering target is a key material widely used in large-scale integrated circuits with 90-28 nm feature size. The copper target for 300 mm integrated circuit requires a reliable diffusion bonding between the ultra-pure copper target and the copper alloy backplate. The bonding ratio and bonding strength of diffusion bonding should reach over 99% and 80 MPa respectively. In this paper, the ascendant structure of electron beam welding united diffusion bonding with high quality was designed. The ultra-pure copper target and the C18000 copper alloy backplate were machined to coordinating size, meanwhile the backplate underwent surface treatment of toothed/smooth, ion cleaning, magnetron sputtering coating, then the combination of target and the backplate was proceeded electron beam welding and diffusion bonding. Metallographic microscope, scanning electron microscope (SEM), mechanical tensile machine, C-scan flaw detector were used to analyze the bonding properties including interface microstructure, bonding strength and bonding ratio. The results show that the bonding ratio of copper target was above 99%, and the bonding strength was up to 80-160 MPa.

An FEA based study of thermal behaviour of ultrasonically welded phosphor bronze sheets

The ultrasonic joining of phosphor bronze sheets is analyzed using a 3-D finite element model for the study and prediction of the thermal profiles at the weld interface. The heat fluxes are calculated and assigned as boundary conditions during the thermal simulation. The forecast of temperature is done under various welding conditions. The maximum temperature obtained by transient simulation at the weld interface is 366.74℃. The continuous reduction in the temperature is observed towards the extremes of the weld metal. The sonotrode and the anvil achieve a lower temperature in comparison to the weld interface. The effect of clamping force and bonding ratio on the interface temperature is observed as positive. The model is validated with an error of 1.576% between the observed and predicted temperature results and a correlation co-efficient 0.96 is established between the simulated temperature results and the weld strength. Sufficiently strong joints were obtained at the optimum welding conditions with 74% joint efficiency. It is evident that the interface temperature has a strong linear relationship with joint strength and is a major deciding factor for achieving strong joints.

Hybrid Lubricant Film With High Bonding Ratio and High Coverage

The frictional properties of a hybrid lubricant film composited from perfluoropolyether (PFPE) lubricant (Moresco DDOH) with single end group and PFPE film deposited from HT170 (Solvay) via photoelectron-assisted chemical vapor deposition (PACVD) were evaluated using a pin-on-disk tester and compared with that of a Z-tetraol dip-coated film. The frictional coefficient of only the HT170 film deposited via PACVD was considerably high; however, the hybrid lubricant film without the mobile fraction showed a friction coefficient equivalent to that of the Z-tetraol film with a mobile fraction of 40%.

Diffusion Equation for Spreading and Replenishment in Submonolayer Lubricant Film

It is important to evaluate the lubrication and replenishment effects of the submonolayer mobile lubricant in hard disk drives because increased recording density can only be achieved through near-contact or surfing recording without head wear. It is known that the minimum friction coefficient can be obtained at a specific bonding ratio [1]. In recent times, the lubricant thickness has been reduced to one monolayer and the thickness of the mobile lubricant layer, to less than 0.3 nm to reduce lubricant pickup on the head surface. Matthes et al. [2] shown that a certain fraction of the layer of currently used mobile lubricants with multiple polar groups is important for reducing head wear. Canchi and Bogy [3] experimentally studied the depletion caused by thermal flying height control (TFC) head contact and reflow speed for various lubricants. Although the diffusion characteristics of perfluoropolyalkylether (PFPE) lubricants layers with a thickness of a few nanometers can be evaluated by a diffusion equation based on continuum mechanics [4], the validity of the conventional equation in the submonolayer lubricant region is not clear. Mate [5] showed that the spreading of a pancake-shaped Z-dol lubricant layer with subnanometer thickness can be quantitatively evaluated by a diffusion equation based on continuum mechanics. Ono [6] showed that the replenishment process of a depleted groove generated by slider touchdown operation can be fairly evaluated by the conventional diffusion equation if the effective ratio of the Hamaker constant to the lubricant viscosity is properly chosen. However, the identified effective viscosity is too high to be estimated from other experimental data [5, 7]. Moreover, the validity of the diffusion equation based on continuum mechanics remains unclear in the submonolayer region.

CHARACTERISTICS OF DLC FILMS INCORPORATED HMDS BY RF PECVD

Silicon incorporated diamond-like carbon films up to 6.2 at. % (DLC- Si ) were deposited onto a high speed steel samples by using a radio frequency plasma-enhanced chemical vapor deposition method. The influence of silicon doping on chemical composition, bonding structure, hardness, and adhesion of DLC films was investigated. Hexamethyldisilane ( HMDS ) gas was used as a silicon source with Ar carrier gas ranging from 0 to 15 sccm. Also, the mixtures of methane ( CH 4) and Ar gases were used as precursor gases. The addition of silicon into the DLC film was found to lead an increase of bonding ratio ( sp 3/ sp 2), hardness and critical adhesion