Tsukuru Suzuki

Influence of Organic Contaminant on Breakdown Characteristics of MOS Capacitors with Thin SiO2

The feasibility of practical application of a plastic wafer box with a UV/photoelectron cleaning unit has been investigated. The total ion chromatogram spectra showed a dramatic decrease of the organic contaminant adsorbed on Si wafers stored in the newly developed plastic box made of polyether sulfone (PES) to which the UV/photoelectron cleaning unit is attached. We also found that the organic contaminant on the Si surface strongly enhances the appearance of a soft breakdown of oxide films of metal-oxide-semiconductor (MOS) capacitors, resulting in a decreased reliability of the gate oxide. However, the injected charge at which the gate oxide undergoes the final hard breakdown is significantly improved by attaching the UV/photoelectron cleaning unit to the PES wafer box.

Evaluation of 300 mm wafer boxes with UV/photoelectron cleaning capability

New plastic wafer boxes with cleaning capability for gaseous contamination harmful to LSI fabrication processes have been developed. The contamination gases are effectively reduced by attaching a UV/photoelectron cleaning unit to the conventional polycarbonate plastic box. The performance of the wafer boxes has been verified by a reliability test of thin gate oxides fabricated on Si wafers stored in the boxes. It is also shown that a newly developed plastic material is superior to polycarbonate in terms of the organic molecule contaminants.

Removal Rate Simulation of Dissolution-Type Electrochemical Mechanical Polishing

A new method for simulating the Cu removal rate in electrochemical mechanical polishing (ECMP) based on the dissolution-type polishing mechanism was developed. The effect of a protective layer on the Cu removal rate was considered in this method because the protective layer is a key element in the dissolution-type polishing mechanism. This method was used to simulate the removal rate in a rotary-type ECMP system. The simulations accurately provided the dependence of the Cu removal rate on the aperture ratio. Furthermore, the dependence of the Cu removal rate on the aperture ratio was described with respect to changes in the average protective layer amount with time. Regarding the dependence of the Cu removal rate on the aperture diameter, however, a discrepancy was observed between the simulation and experimental results because this method did not take into account the effect of the aperture diameter on the electrolyte-filling ratio in apertures.