Kinik (Taiwan)

A proliferation of pad materials in recent years, coupled with the increasing complexity of process integration and limited resources available for process development, has highlighted the need for a more in depth understanding of conditioning interactions and better predictive tools for process and consumable design. We have previously noted a range of conditioning response as illustrated in Figure 1. As the figure illustrates, on some materials the surface height distribution imparted by the pad conditioner is shifted to the left relative to the exponential signature of the pad native porosity which is used as a reference. Denoted regime 1, these surfaces are characterized by the prevalence of “eyelid” features which obscure the line-of-sight path to the bottoms of the pores. In regime 2, the surface height distribution is more balanced, with a smooth transition between the exponential porosity signature and the conditioning signature. In regime 3, there is an abrupt disconnect between the exponential porosity signature and the conditioner signature. Such surfaces are characterized by deep gouges.We are investigating pad material tensile properties as a proxy to help understand and predict these conditioning responses. Figure 2 illustrates the range of typical tensile behavior for polymers. While Figure 2 invokes temperature as the variable that drives these behaviors, note that strain rate can also drive tensile behavior across this range with high temperature being analogous to low strain rate and vice versa.Figure 3 and Table 1 summarize some results from our testing of IC1000, VP5000, VP6000, IK4250H and IK4350L. We have determined that grooved pad materials at their nominal dimensions are adequate for testing according to ASTM D638: Standard Test Method for Tensile Properties of Plastics. Typical delivered pad thickness is within the specifications for sample thickness, and as long as the grooves are oriented to be substantially parallel with the strain axis (pulling direction) reproducible results can be obtained. A range of properties spanning at least about 2x is observed in these pads.Figure 4 gives one example of how this information can be directly applied. The figure illustrates a manifestation of the threshold behavior that is typically observed when conditioning with a pad conditioner with uniform tip height, where all the cutting points are controlled within a height range of about 10 µm. As opposed to a conventional conditioning platform, where there is a much wider range of tip heights, the uniform height-controlled conditioner exhibits a threshold behavior where no measurable cutting occurs below a limiting condition down-force (cdf). Figure 4 illustrates the disconnect between a high down-force, accelerated cutting test, using 14 lbs cdf and designed to return the “CR” value for a conditioner, and typical process cdf levels, in the range of 5 lbs cdf. Note that CR values are generally about an order of magnitude higher than comparable polishing tool level pad wear rates. Whereas conventional platforms yield a linear response between CR and tool level pad wear rates, the uniform height design exhibits an offset, such that at low CR levels, low pad wear rates are observed. The position of this threshold is a function of pad type. These data suggest that this threshold can be correlated with the mechanical strength of the pad material, as determined by the tensile test results.We have also explored the effect of strain rate on tensile response. Strain rates in a typical CMP process may be as high as 105 s-1, and as shown in Figure 2, strain rate can have a significant effect on material behavior. Figure 5 illustrates typical results, illustrating the extremes of response for this group of pads, and Figure 6 shows the normalized response of offset yield and tensile strength as a function of strain rate. Of these materials, only IK4350L exhibits a divergent response, and as shown in Figure 7, IK4350L typically exhibits the most abrupt transition between the exponential porosity signature and the conditioner cutting signature, indicating a tendency towards the gross over-conditioning behavior characteristic of regime 3.Over the range of strain rates explored here, all of these materials can be characterized as “rubbery”. This rubbery behavior can be understood in the context of reported property measurements of CMP pads, which indicate distinct glass transitions related to the soft and hard phases of the polyurethane from which the pad is made. This analysis suggests that pad behavior is dominated by the “rubbery plateau” of the soft segment of the polymer, with the glass transition of the hard segment occurring above typical polishing temperatures. Figure 1

Thin film solar cells have emerged in recent years, in particular, those made of amorphous silicon or CIGS (copper indium gallium sellenide). By tendon of boron doped amorphous diamond with phosphorus doped amorphous silicon, the conversion efficiency may rival that of crystalline silicon. On the other hand, the CdS top layer for CIGS is not only poisonous, but also UV degradable. Amorphous diamond coating with N doping can replace CdS to boost CIGS's efficiency also. Nanodiamond may be sputtered from diamond grit or diamond film as target. The PVD formed nanodiamond layer can be located at the interface between P and N types. In this case, the quantum well effect can allow the production of multiple electrons per incident photon. In addition, the output voltage may be increased due to the wide band gap of nanodiamond.

Graphene is the ideal material for many dream applications, such as single electron transistors, field emission sources, light through electrodes, flexible solar cells, wall paper displays, UV light emitting diodes, atomic gas sensors, DNA or antigen wafers, terra hertz surface acoustic wave (SAW) generators and filters...etc. However, a practical method to fabricate meter-sized graphene is still beyond imagination. In this research, we reported a simple technology to harvest large area graphite films by using molten alloy as the catalyst. Each film contains hundreds or thousands layers of graphene. Some stacks of graphene revealed silk-like tenderness with transparent folding lines. This liquid phase epitaxy (LPE) process appears scalable for making graphene layers measured in meter size. This paper also presented many intriguing aspects related to the growth of large graphene.

Sintered polycrystalline diamond cubicles were oriented to make CMP pad conditioners. The dressing experiments demonstrated the capability of fast pad cutting and efficient removal of glazed layer that is formed by polishing wafers with slurry on dressed pad.

This paper investigating a revolutionary design of pad conditioners is based on carving a structure out of sintered polycrystalline diamond (PCD) matrix. The PCD dresser is manufactured by wire electro discharge machining to form cutting pyramids of a specific size with a designed shape. The dressing characteristics of pad surface textures are studied by comparison with conventional diamond pad conditioner. Experimental results indicate that the PCD dresser can dress asperities of the pad more uniformly than the conventional diamond dresser due to PCD dresser having identically shaped tip and the same height diamond. In addition, the cutting rate of PCD dresser for IC1000 pad not only is reduced by about 30% and also it can dress pad more effectively than conventional diamond dresser.

Four different catalysts, nanodiamond seed, nano‐Ni, diamond powder, and mixture of nano‐Ni/diamond powder, were used to activate Si wafers for diamond film growth by hot‐filament CVD (HFCVD). Diamond crystals were shown to grow directly on both large diamond powder and small nanodiamond seed, but a better crystallinity of diamond film was observed on the ultrasonicated nanodiamond seeded Si substrate. On the other hand, nano‐Ni nanocatalysts seem to promote the formation of amorphous carbon but suppress transpolyacetylene (t‐PA) phases at the initial growth of diamond films. The subsequent nucleation and growth of diamond crystals on the amorphous carbon layer leads to generation of the spherical diamond particles and clusters prior to coalescence into continuous diamond films based on the CH3 addition mechanism as characterized by XRD, Raman, ATR/FT‐IR, XPS, TEM, SEM, and AFM techniques. Moreover, a 36% reduction in surface roughness of diamond film assisted by nano‐Ni catalyst is quite significant.

Kinik Company pioneered diamond pad conditioners protected by DLC barrier (DiaShield® Coating) back in 1999 (Sung & Lin, US Patent 6,368,198) and there has been no follower since then. Kinik's offered two varieties of DiaShield® Coatings: ultrahard tetrahedral amorphous carbon and superhard hydrogenated DLC. Kink also evaluated Cermet Composite Coating (CCC or C3, patent pending). C3 is unique that the coating composition grades from a metallic (e.g. stainless steel) under layer to a ceramic (e.g. Al2O3 or SiC) exterior. The metallic under layer can form metallurgical bond with metallic matrix on the diamond pad conditioner. The ceramic exterior is both wear and corrosion resistant. The gradational design of C3 coating will assure its strong adherence to the substrate because there is no weak boundary between coating and substrate. By dipping diamond pad conditioners of various designs in acidic solution (e.g. copper cleaning solution) for extended periods of time (e.g. 50 hours) the chemical inertness of various matrix materials are determined with the decreasing ranking as: hydrogenated DLC > C3 coating > tetrahedral amorphous carbon > sintered nichrome > brazed alloy > electroplated nickel.