Interconnects pitch

Figure 6.12 Dependence of removal rate on interconnect pitch.5...

The immensity of the number of devices to be interconnected in the BEOL requires a complex nonplanar multilevel wiring scheme that physically towers over the silicon substrate, quite analogous to a multistory apartment complex, except that the feature sizes are at the nanolevel. Indeed, the minimum interconnect pitch, which is the sum of the wiring thickness and space between a pair of wires, is only 52 nm and dropping, while the number of wiring levels, analogous to the number of floors in the complex, is over 14 in some current devices. 

Automated soldering operations can subject the mol ding to considerable heating, and adequate heat deflection characteristics ate an important property of the plastics that ate used. Flame retardants (qv) also ate often incorporated as additives. When service is to be in a humid environment, it is important that plastics having low moisture absorbance be used. Mol ding precision and dimensional stabiUty, which requites low linear coefficients of thermal expansion and high modulus values, ate key parameters in high density fine-pitch interconnect devices. 

What we really are is a web of interconnections, the summation of all of our relationships, all the people we know and those we are still to meet. It s not that we are in the web, the web is what we are. Vowel sounds change the colors pitch and tone alter the shape of the enclosing... 

The invention of US-A-4989067 relates to interconnections from an HgCdTe detector chip to a silicon read-out chip. A beam lead interconnect formed on a silicon chip is used to provide connections with a finer pitch than is achievable when wire-bonding is used. 

Spiesshoefer S, Schaper L, Burkett S, Vangara G, Rahman Z, Arunasalam P. Z-Axis interconnects using fine pitch, nanoscale through-silicon vias process development. Proceedings of the IEEE Electronic Component and Technology Conference 2004. p 466-471. 

A 2 urn pitch triple-level metal process using two levels of tungsten interconnect was reported by Bonifield et al.144. The third metal level was still Al-Cu(2%) driven by the requirements of wire bonding. For the vias between metal 2 and metal 3 a selective tungsten process was used. 

The 3D molded interconnect is uniquely shaped to provide specific mechanical features. As shown in Figure 8, three individual circuit traces (plated pads) function as three separate switches whose pitch is such that for documents containing holes, even if one or two traces coincided with a hole, at least one circuit trace would still detect a document presence. Trying to package three optical sensors that close together would be difficult or nearly impossible.( 6)... 

ACC-4 still has about 3-4% voids and fissures, which are detrimental to the performance of the material. In its use as a missile nose cone or rocket nozzle, the extremely hot gas environment can result in rapid degradation of the part because the chemically reactive gases can rapidly permeate the structure via the interconnecting fissures and voids and attack the carbon fibers. Furthermore, in the bow shock wave of a missile nose cone that reenters the ionosphere, the atomic oxygen that is formed can similarly permeate and attack the fibers. Further densification of ACC-4 by another PIC cycle (to reduce the voids to below the 3% level) is virtually impossible because the resin or pitch cannot be forced into the microcracks and pores of the composite even under extremely high hydrostatic pressure of 700-1,500 bar, because of viscosity and surface tension considerations. 

---