T 0363/91 08-06-1995

I. European patent application No. 86 102 365.3, Publication No. 194 495, (a divisional application based on the earlier application No. 81 901 098.4, filed on 6. April 1981) claiming a priority date of 10 April 1980 derived from US Application No. 138 891, was refused by a decision of the Examining Division dated 31 October 1990. That decision was based on a set of 11 claims filed with a letter of 8 August 1988, and a further Claim 12 filed with a letter of 15 November 1989. Claim 1 is as follows:

"1. A method of producing thin films of essentially single crystal material, including the steps of:

a) forming a crystal growth mask on a crystallisation substrate such that the mask exposes areas of the substrate for growth thereat; and

b) depositing crystalline material at the exposed areas of the substrate under conditions which enable lateral growth of crystalline material over the said mask, the exposed areas being for example provided by slits in the mask; and characterised by the steps of:

c) continuing laterial overgrowth until a thin film of essentially single crystal material having desired dimensions has formed;

d) bonding a new preexisting substrate comprised of different material from the substrate to the film of essentially single crystal material;

e) separating the new substrate and the essentially single crystal material from the crystallisation substrate; and

f) optionally reusing the crystallisation substrate to produce additional thin films of essentially single crystal material."

II. The ground for the refusal was that the alleged invention lacked any inventive step having regard to the combined effect of the disclosures of documents:

(1) US-A-3 364 150 and

(2) US-A-3 370 980.

The Examining Division held that the alleged invention related to forming a film of an essentially crystalline material through and on a growth mask, which mask was on a crystallisation substrate. A second substrate was then attached to the grown material, so that the grown material, together with the second substrate, could be separated from the crystallisation substrate, which could be reused in subsequent film production. Such a method of growing a thin film was disclosed in document (1), which disclosed steps a) to c) and f) of Claim (1) in suit, but lacked the separation step, which entailed bonding a preexisting substrate of a material different from the deposited crystal onto that crystal. In that respect, document (2), which was concerned with the same technical field, was relevant. It disclosed the deposition of a single crystal film on a growth substrate, and the deposition of a second substrate onto the desired deposited film to aid in the separation of the deposited film from the growth substrate.

The Examining Division accepted that document (2) did not disclose the use of a preexisting substrate, but it regarded the alternatives of the deposition of a substrate, as compared with the bonding of a preexisting substrate, as being simply a matter of choice of one of a number of alternatives which the skilled worker would make without the exercise of any inventive skill. The age of the citations was not material because the application in suit at page 7 lines 9 to 24 referred to the demand for solar cells which have great potential for both space and terrestial applications. That demand was, however, of recent rather than long standing origin.

III. An appeal against that decision was filed on 3 January 1991, the appeal fee was paid on 8 January 1991, and the statement of grounds of appeal was filed on 27 February 1991. In that statement, the Appellant contended essentially that the skilled worker confronted with the problem of separating the film, and seeking an alternative to that diclosed in document (1) would, if confronted with document (2), adopt the method of separation there proposed, of making use of a further deposited layer, for the sake of giving additional strength to the desired deposit, rather than thinking of still other ways of effecting separation, such as by the use of a preexisting substrate as proposed by the application. The distinct ideas contained in documents (1) and (2) had not been combined in the twenty years that these two documents had been available to the public, and it was only through the use of hindsight that the Examining Division had combined their respective teachings, and then added the further step of suggesting that it was obvious to use a preformed second substrate.

IV. The Appellant's main request is to set aside the decision of the Examining Division, and for the patent to be granted on the basis of the claims and description considered by the Examining Division. As an auxiliary request it seeks a more restricted form of Claim 1, in which steps a) to f) are as in Claim 1 in accordance with the main request, subject to the modification that the full stop in feature (f) after the final words, "crystal material." is replaced by a comma, and the further words added:

"characterised by the step of;

g) at least partially fabricating an electronic device in or on the thin-film of essentially single crystal material before bonding the new preexisting substrate thereto."