Petz - Re: "Resistivity is a fundamental property of the element, you can't change it if you go to Mars."
You must have never sputtered or deposited a metallic or alloy thin film. The sheet resistance varies dramatically with deposition techniques. It is further altered by subsequent thermal treatments - annealing, passivation deposition, etc.
The resistivity values quoted in textbooks generally refer to a specific material of a specific composition prepared in a specific manner - minor impurities on the order of parts per million - can have significant effects on resistivity - and these "impurities" are very difficult to eliminate in Physical deposition techniques, let alone any kind of chemical plating deposition.
Further, trapped vacancies (empty lattice sites) can have a first order effect on resistivity. The vacancy concentration is greatly effected by specific thermal processing, annealing, etc.
For example, copper is quoted as having a resistivity of 1.72(Micro-ohm CM) for annealed copper and 1.77 for hard-drawn copper - (CRC Handbook of Chemistry and Physics).
One thing most thin film process enegineers learn (the hard way) is NOT TO MEASURE the sheet resistivity of sputtered metal films until AFTER annealing them (in hyrdrogen or nitrogen ambients).
Life in a wafer fab or process development environement is NEVER as simple as one would like to believe.
One other point to consider - Gordon Moore (whom you quoted regarding the copper resistivity) is no fool. He was a founder of Fairchild and head of R & D, presiding over the INVENTION of the integrated circuit - invented by Bob Noyce. Gordon and Bob Noyce founded Intel 9 years later where they presided over the invention of the microprocessor.
When Gordon Moore describes something about semiconductor process development, you should best listen very carefully. He may not ride in a shareholder provided chauffeured limousine, but chances are, he knows exactly what he is talking about concerning wafer fab processing details.
Paul |
