Key points
- " Claim 1 of the main request reads as follows: "Method for generating a design model with an improved characterization of a standard cell with adaptive body biasing in a circuit design process of said cells in digital circuits fabricated in a foundry, whereby the cell is defined by subject to variations due to the fabrication process P of said foundry, a supply voltage VDDnom and an operating temperature T, the method comprising the following steps: considering static deviations in the supply voltage VDDnom ..."
- " The board considers that, in the current case, the result of the calculations effected by the method steps of claim 1 is a design model with an "improved" characterisation that is obtained by simulation (see characterising part of claim 1, for example) of a standard cell which [design model (?)] is provided in a library file. Such a library file is, at least according to the description, used by customers in later stages of the overall design process [] but the method of claim 1 does not contain steps specifying the use of the produced library file in later design or manufacturing steps. A use of the design model in a manufacturing step would have been particularly relevant since the Enlarged Board of Appeal considered the inclusion of a manufacturing step to be an argument in favour of patentability (see point 134 of decision G 1/19)."
- " The board is aware that claim 1 ... specifies the ultimate aim of using the improved design model of a standard cell for fabricating integrated chips (digital circuits) in a foundry. However, the manufacturing of a designed digital circuit using the improved design model is neither specified as being part of the method of claim 1 nor implied by specifying the ultimate aim of the design process. Since the result of the method of claim 1 is calculated data for an improved design that is obtained using simulation, it follows from points 97, 98 and 138 of decision G 1/19 that the improved design does not contribute to inventive step since no "further" technical effect, such as controlling a machine in the foundry during a manufacturing process, is derivable."
Main request
4. Inventive step
4.1 The examining division considered that, even assuming that storing results in a library file implied the use of technical means, the method of claim 1 of the current main request lacked an inventive step for the following reasons: first, it was well known to store cell characterisation data in library computer files (see document D1, columns 17 and 18). Second, the further steps corresponded to non-technical user requirements that, according to the COMVIK approach (see decision T 641/00), were part of the objective technical problem (see contested decision, point 2).
4.2 In its statement of grounds of appeal, pages 4 to 8, the appellant submitted that the method of claim 1 was not a mental act as such but rather used a design tool as technical means. The claimed method generated a design model with improved characterisation of a standard cell. The results of said characterisation were stored in a library file containing library corners or so-called PVT corners. These data were used in the simulation process of standard cells for highly integrated semiconductor components by the customers and were needed to simulate how a designed circuit might work later (see description, page 3, starting at line 16).
The appellant argued that, according to decision T 154/04 and in view of the objective of the invention and the proposed solution, the claimed procedure could not be reduced to the mere collection of data, e.g. in a database, for the purpose of analysing design parameters of said cells. Referring to decision T 1227/05, the appellant argued that the method had a technical character as it concerned the technical field of chip manufacturing. Since the method was implemented by design tools, this added to the technical character in view of decision T 914/02. A direct use of controllable natural forces was not necessary for an invention (see statement of grounds of appeal, page 5, first and second full paragraphs).
4.3 Regarding the issue of whether steps of the claimed method encompass mere mental acts, the board accepts the appellant's argument that the skilled person would interpret the method of claim 1 as being computer-implemented, since the method is specified as being part of a circuit design process of a standard cell in digital circuits fabricated in a foundry, i.e. it aims to improve a design model for cells of a microchip. The skilled person will understand that such a design, at the filing date, was generated using computer-implemented design tools. Consequently, the skilled person would not interpret the steps of the method according to claim 1 as encompassing merely mental activities.
4.4 The board considers that the cited decision T 1227/05, which concerned computer-implemented methods for the numerical simulation of electronic circuits, is no longer relevant to the present case in view of the more recent decision G 1/19, which reconsidered the general approach for assessing the technical character of computer-implemented methods for simulation and design (see point 133). Consequently, decision G 1/19 is the essential case law that has to be considered when assessing inventive step in the current case, and the board summarises some relevant aspects of this decision below.
4.4.1 According to point 97 of G 1/19, "calculated technical effects should be distinguished from potential technical effects which, for example when a computer program or a control signal for an image display device is put to its intended use, necessarily become real technical effects".
Moreover, according to point 98 of the decision, "[c]alculated status information or physical properties concerning a physical object are information which may reflect properties possibly occurring in the real world. However, first and foremost, they are mere data which can be used in many different ways. There may exist exceptional cases in which such information has an implied technical use that can be the basis for an implied technical effect. Still, in general, data about a calculated technical effect is just data, which may be used, for example, to gain scientific knowledge about a technical or natural system, to take informed decisions on protective measures or even to achieve a technical effect."
Point 128 of decision G 1/19 summarised that calculated data "reflecting the physical behaviour of a system modelled in a computer usually cannot establish the technical character of an invention in accordance with the COMVIK approach, even if the calculated behaviour adequately reflects the behaviour of a real system underlying the simulation. Only in exceptional cases could such calculated effects be considered implied technical effects (for example, if the potential use of such data is limited to technical purposes, see point E.I.f above)". Point E.I.f comprises points 97 and 98.
4.4.2 Finally, the Enlarged Board of Appeal saw no difference regarding the technicality of a simulated physical system in the event that the computer-implemented simulation was claimed as part of a design process, in particular for verifying a design (see decision G 1/19, point 138 and order, point 3).
4.5 The board considers that, in the current case, the result of the calculations effected by the method steps of claim 1 is a design model with an "improved" characterisation that is obtained by simulation (see characterising part of claim 1, for example) of a standard cell which is provided in a library file. Such a library file is, at least according to the description, used by customers in later stages of the overall design process (see description of the published application, page 5, lines 12 to 17 and page 10, lines 3 to 11), but the method of claim 1 does not contain steps specifying the use of the produced library file in later design or manufacturing steps. A use of the design model in a manufacturing step would have been particularly relevant since the Enlarged
Board of Appeal considered the inclusion of a manufacturing step to be an argument in favour of patentability (see point 134 of decision G 1/19).
4.5.1 The board is aware that claim 1 refers to "a circuit design process of said cells in digital circuits fabricated in a foundry" and thus specifies the ultimate aim of using the improved design model of a standard cell for fabricating integrated chips (digital circuits) in a foundry. However, the manufacturing of a designed digital circuit using the improved design model is neither specified as being part of the method of claim 1 nor implied by specifying the ultimate aim of the design process.
4.5.2 Since the result of the method of claim 1 is calculated data for an improved design that is obtained using simulation, it follows from points 97, 98 and 138 of decision G 1/19 that the improved design does not contribute to inventive step since no "further" technical effect, such as controlling a machine in the foundry during a manufacturing process, is derivable.
4.5.3 The board is aware that a "further" technical effect relating to the internal operation of the computer system could also be achieved by the claimed method. However, the only feature of the claimed method that concerns details of its implementation in a computer system is that results are provided in a library file, i.e. that result data are stored in a file. However, the examining division considered that it was well known to store such data in a file (see point 2.8 of the contested decision), and the appellant did not dispute this finding. Moreover, since the data is as such non-technical, only the storing of the data in a file could be regarded as being technical, but this is known in the context of a notorious general-purpose computer and cannot be the basis for an inventive step.
4.5.4 Consequently, the steps of the claimed method, apart from their straightforward implementation by means of a computer, do not contribute to inventive step, but rather represent a non-technical algorithm underlying the method of claim 1.
4.6 In response to the board's line of argument against inventive step based on decision G 1/19, the appellant argued that the current invention was "an 'exceptional case' in the sense of decision G 1/19 for which the calculated behaviour of components (standard cells) of a physical system (microchip), exclusively for the purpose of manufacturing the microchip is the basis for a technical contribution" (letter of 2 June 2023, page 5, fourth full paragraph). The properties of standard cells calculated during characterisation were specifically and exclusively calculated, provided and used for production purposes. While this was not explicitly stated in the claims, this followed from the context of microchip fabrication and the skilled person's common general knowledge.
The appellant also argued that the library file contained data that was used by the machines in the foundry. For example, the layout of a standard cell was later used as part of the overall layout of the digital circuit that was produced. At the oral proceedings, the appellant explained that the customers assembled digital circuits using the standard cells as building blocks. The information contained in the library files was important for the resulting chip layout. For example, the timing information for the standard cells contained in the library file directly influenced the later "Timing Driven Place and Route" design step. The claimed invention solved the problem of improving the data in the library files provided to the customer. The improved data allowed the customer to produce a design of a microchip using a lesser silicon area for the production of the microchip and to reduce energy consumption during operation of the microchip. Consequently, the library file was an indispensable input for optimising the microchip.
The data in the library files was not directly used to control the machines for the microchip production, and further human input was still needed to specify the design goals, which were then implemented using the library file. However, there was no intermediate step where a human judged the provided design model or library file as being good or bad, for example. While there were further intermediate steps before the microchip manufacturing step, these intermediate steps were straightforward.
4.7 Regarding the appellant's argument that the claimed invention was an exceptional case according to points 98 and 128 of decision G 1/19, it is important to consider whether the design produced by the method has a potential technical effect in the sense of point 97 of decision G 1/19 (e.g. because the design is produced as a computer program or a television control signal). The exceptional cases mentioned in points 98 and 128 of decision G 1/19 are to be understood only as cases where the simulation and/or design result, when put to its intended use, without any further human interaction, achieves a technical effect such as controlling a technical device. Such a strict approach is desirable to establish legal certainty by drawing a clear line for the technicality of design processes producing a design. A design consisting merely of geometrical data such as a layout mask cannot be said to have a potential technical effect in the sense of decision G 1/19.
Since the library file is not directly used to control the machines in the foundry and even further human input is necessary before its use in a manufacturing step, the library file produced by the method of claim 1 cannot be considered to have an implied technical effect. In this context, the board also observes that the Enlarged Board of Appeal considered that the decision to build or not build a prototype is a business decision made by humans (see point 123 of G 1/19). Similarly, the decisions on whether and how to use the layout data in the library file and whether or not to manufacture a digital circuit are human decisions.
Consequently, the board is not convinced that the current case is an "exceptional case" in the sense of decision G 1/19.
4.8 From the above reasoning, it follows that the method of claim 1 lacks an inventive step (Article 56 EPC).
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