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On October 22, 2008, the Intellectual Property High Court upheld the decision of the Board of Appeal that the invention should be rejected under the Japanese Patent Law Article 29(2) [inventive step requirement] because a person skilled in the art would have deducted the invention from the disclosures of the cited documents in view of well known technologies.
The invention is directed to a method for etching an oxidation layer on a substrate. The only difference between the present invention and the cited prior is that the invention uses a plasma gas including C2H2F4 for etching the oxidation layer on the substrate while the prior art uses a plasma gas including a mixture gas of CH3, H2, and N2. The court ruled that it would have been conducted easily by a person skill in the art to employ C2H2F4 in place of CH3 because (1) it was widely known to use fluorohydrocarbon gas as plasma etching gas, (2) the cited prior arts disclose to use C2H2F4 as plasma etching gas, (3) the technical innovation in this field is so rapid, and (4) the advantages derived from using C2H2F4 would have been expected by a person skilled in the art.