T 387/05 - An ‘Exotic’ Feature is Considered Non Distinguishing

The question arises whether the resistance that the blank mould opposes to high energy DUV radiation – which is expressed in claim 1 by the condition that the reduction of transmission under the specified test conditions is at most 0.1 % per cm of thickness – can be used to distinguish the claimed subject-matter from the prior art. The appellant has answered this question in the negative and submitted that this feature only states the technical problem. The patentee has asserted that this criterion corresponds to a quantitative statement on an essential material property that is suitable to distinguish the claimed blank mould from the prior art. He admitted that the test conditions specified in claim 1 differ from usual methods by a higher number of laser shots together with a lower energy density, but according to him, this difference is necessary in order to have reliable indications with respect to the long term behaviour of the blank mould. [4.7]

The Board considers the explanations of the patentee to be plausible. However the question remains whether they are sufficient to distinguish the claimed blank mould from the prior art. Indeed the test conditions according to claim 1 (i.e. a number of laser shots of 1.1·10^9 and an energy density of 10 mJ/cm² at a wavelength of 248 nm and a laser shot frequency of 300 Hz …) differ so strongly from the usual conditions used in the prior art (D2 has a number of laser shots of 1.1·10^6 and an energy density of 400 mJ/cm² at a wavelength of 248 nm …) that no reasonable and meaningful comparison of the test results is possible. Therefore, it is not possible to establish whether the blank mould according to claim 1 has higher resistance to high energy DUV radiation – or a lower reduction of transmission, respectively – than the blank moulds of the prior art, and in particular the blank moulds of D2. The patentee, who in this case carries the burden of proof, has not produced any appropriate evidence. Therefore, the Board comes to the conclusion that in the present case the reduction of transmission cannot be considered as a distinguishing feature. [4.7.1]

To read the whole decision (in German), click here.