Technology node

Explain why the requirement of CMP slurries become more stringent with the advancement in technology node. 

The chemical component of CMP slurry creates porous unstable oxides or soluble surface complexes. The slurries are designed to have additives that initiate the above reactions. The mechanical component of the process removes the above-formed films by abrasion. In most planarization systems the mechanical component is the rate-limiting step. As soon as the formed porous film is removed, a new one is formed and planarization proceeds. Therefore, the removal rate is directly proportional to the applied pressure. To achieve practical copper removal rates, pressures greater than 3 psi are often required. These pressures should not create delamination, material deformation, or cracking on dense or relatively dense dielectrics used in silicon microfabrication on conventional dielectrics. However, the introduction of porous ultra-low-fc (low dielectric constant) materials will require a low downpressure (< 1 psi) polishing to maintain the structural integrity of the device [7-9]. It is expected that dielectrics with k value less than 2.4 will require a planarization process of 1 psi downpressure or less when they are introduced to production. It is expected that this process requirement will become even more important for the 45-nm technology node [10]. 

Ong P, Ponoth S, Economikos L, Sakamoto A, Flong DPI, Chae M, Rhee SH, Nicholson LM, Landers W, Werking J, Li B, Chen F, Sankaran S. Cu CMP with direct polish on ultra-low-k dielectric film k 2.4) for 45 nm technology node. ICPT Oct 2006. 

Suggest a formula hnking a certain technology node to the maximum allowable post-CMP nonplanarity for this node. 

Perhaps the most crucial component of the transistor structure is the gate oxide, which serves as the insulator between the gate and channel. Ideally, the oxide layer should be as thin as possible to increase the channel conductivity when the transistor is on, and reduce subthreshold leakage when the transistor is off. Since the first MOSFETs were demonstrated, the gate length has steadily decreased to a current size of less than 30 nm (Figure4.13). For the current 65 nm technology node, ... 

Figure 4.13. Scaling of transistor size. The top line indicates the technology node, whereas the bottom line indicates the physical size of the gate. It should be noted that the technology node no longer refers to physical dimensions of the transistor, but is rather an industry term related to a new fabrication process every 2 years, in accord with Moore s Law. By definition, the technology node refers to half the distance (half-pitch) between cells in a DRAM memory chip. It is noteworthy that the gate length, L, officially moved into the nanoregime in the year 2000. Reproduced with permission from Intel Corporation (http //www.intel.com).

Figure 1.16 Typical production ramp curve illustrating technology node timing.21...

Fig. 15.17. The number of implant steps per wafer as a function of technology node (as defined by the International Technology Roadmap for Semiconductors)...

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