On 6 June 2018 the District Court in The Hague gave a second ruling in an extensive patent dispute between Nikon and ASML, which comprises 11 separate infringement actions in the Netherlands.
An earlier dispute that was resolved by entering into a cross licence agreement at the end of 2014 formed the basis for the current dispute. The cross licence agreement had ended and negotiations concerning a new cross licence agreement had so far proven unsuccessful. The licence term and licence fee ASML would have to pay to Nikon turned out to be particular breaking points.
These proceedings relate to EP 2 157 480 (the Patent), owned by Nikon. The Patent relates to an exposure method and apparatus for simultaneously transferring patterns with various pitches (e.g. various relative distances in the pattern) with high resolution and contrast to a wafer.
When determining the prior art, Nikon argued that EP 470 (a patent application of Carl Zeiss) discloses merely an "aperture stop" rather than a "diffractive optical element" (DOE) within the meaning of the Patent. The District Court disagreed with Nikon and referred, amongst others, to the file history of the parent patent, in which, in a letter to the examiner, Nikon itself explained that an “aperture stop” and a DOE can be considered the same.
Nikon subsequently argued that the patent claims are restricted to the first of the five embodiments described in the Patent (with the application of a DOE), but this too was rejected by the District Court. The reason for this being that while the claim mentions a DOE, it does not appear that this phrase is restricted to a DOE as described in the first of the five embodiments. Such a restriction cannot be deduced from the patent description either.
Nikon furthermore alleged that EP 541 (a patent application by ASML), which is used in combination with the prior art referred to above (EP 470), does not disclose how specific light intensify distributions can be obtained. However, the District Court held that ASML was correct in pointing out that the Patent itself does not contain any indications as to obtaining the desired light intensity distributions either. According to the patent application this is apparently part of professional know-how on the priority date concerned and should therefore apply to EP 541.
On the basis of EP 470 combined with EP 541, the District Court ruled that a person skilled in the art would be able to implement the DOE of EP 541 in the lighting system of figure 2 of EP 470 without any issues, simply by replacing the mirror and aperture by a DOE. This is routine work not involving any inventive step.
The abovementioned attack on inventive step, combined with other documents, meant that the District Court eventually ruled that the Nikon patent is invalid and implies that it cannot be infringed by ASML. In the counterclaim proceedings the claim for nullification of the patent was awarded. Nikon was ordered to compensate ASML's legal costs of € 950.000 (both the original action and the counterclaim).