Computer-aided design and analysis of circuits and semiconductor – Nanotechnology related integrated circuit design
Reexamination Certificate
1997-10-08
2001-06-05
Smith, Matthew (Department: 2825)
Computer-aided design and analysis of circuits and semiconductor
Nanotechnology related integrated circuit design
C716S030000, C716S030000
Reexamination Certificate
active
06243848
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the analysis of complex physical structures such as, for example, integrated circuits. This analysis is particularly useful for identifying the constituents of a structure, for ensuring the conformance of a structure to its original specification, for regenerating a structure in accordance with technological developments and for comparing a structure to another known structure.
DESCRIPTION OF PRIOR ART
A manufacturer of electric circuits must sometimes ensure the supply of its products for fairly long periods, for example as spare parts for expensive equipment. Keeping circuits of this type in stock is not economical; moreover, stored circuits can age and it is preferable to have new spare parts available as needed. On the other hand, maintaining an overabundant stock for the maintenance of this equipment may be unnecessary. That is why a manufacturer sometimes has to re-manufacture circuits it developed in the past. For integrated circuits, it uses archived computer files describing masks, which it retransmits to a semiconductor materials founder. However, these masks may be obsolete for various reasons having to do with technological development. In this case, it is necessary to generate masks that can be used with the current technologies. The current CAD (computer aided design) tools make it possible to generate descriptions from formal specifications. These formal specifications, stored in computer files, describe the expected functional behavior of the circuits to be produced.
A problem which the manufacturer is subject to is that it does not necessarily have formal specifications that can be directly used by current CAD tools to re-manufacture circuits whose behavior would be identical to that of the initial circuits. The reasons are manifold: the descriptive language may not be adapted to the available CAD tools, the formally described behavior may not exactly correspond to that of the circuit produced due to human intervention in various stages of the design of the masks, or in optimizations or modifications after testing. For these various reasons, mask description files represent the circuits produced more reliably, both structurally and functionally. However, they do not make it possible to directly generate new mask descriptions that can be used by the current manufacturing technologies at the time of a production rerun. On the other hand, mask descriptions present problems in understanding the functionalities of the circuit produced. This understanding may be necessary to adapt the circuit to current technology. In this case, a formal description facilitates analysis of the circuit produced.
The manufacturer may have in its archives connection lists (netlists) which enumerate the various elements of the circuit along with their interconnections and possibly also their physical position as they appear in the mask description files. These connection lists have often been generated in parallel with the generation of the existing masks. If the manufacturer does not have any connection lists, certain tools known as extractors make it possible to generate connection lists from mask description files. However, these connection lists represent complex structures which are difficult, is not impossible, to understand and analyze directly using known means.
It is therefore useful to be able to generate structural and behavioral descriptions from an existing circuit, in the form of a formal specification for use by CAD tools as well as for facilitating a functional understanding of the existing circuit.
A manufacturer may also wish to expand the performance of a circuit belonging to it by modifying some of its functions or the technology of some of its elements. The jumble, of different components of the circuit necessitates certain precautions to prevent the modifications from having harmful consequences on the global behavior of the circuit. It is therefore advantageous for the manufacturer to have the use of a circuit recognition process for generating new masks. The manufacturer may also wish to include in an existing circuit certain components of other circuits which belong to it and whose effects it knows. In this case, it is advantageous to have the use of a circuit recognition process for locating these components in the other existing circuits in order to generate new masks.
Complex structures are found not only in the field of integrated circuits but also in other technical fields such as, for example, organic chemistry. Complex molecules can result from production by man, but also from natural processes such as biological ones. It is now possible to list in computer files numerous nucleotide and amino acid sequences, some of whose effects are known. When faced with representations of sequences which are unknown, but for which the effects of certain sub-sequences may be known, it is advantageous to use the invention to recognize new sequences. In this case, the connection list is represented by the sequence representation in order to obtain a specification of effects produced by this sequence.
French patent application 9410260 filed Aug. 24, 1994 assigned to the assignee of the subject application and its U.S. counterpart Ser. No. 08/515,572, filed Aug. 16, 1995, now U.S. Pat. No. 5,734,572, the subject matter of which is hereby incorporated by reference, describes a tool that automatically produces an abstract specification of a physical system from a concrete description defining the structure of this system.
However, in analyzing the structure of a physical system, it is not necessarily desirable to obtain an abstract specification of the entire physical structure, but only to obtain a part of it, in accordance with specific interests. It is often difficult to extract a part of a structure whose complexity results in a confusion of its elements, both in their locations and in their interactions. For a complex structure comprising a considerable number of elements, the concrete description is presented in the form of a computerized data set.
OBJECT OF THE INVENTION
In order to eliminate this problem, a process for analyzing a computerized data set containing a connection list for describing a physical structure is provided which is characterized in that the process comprises a first step for executing set-based operations on subsets of the computerized data set and producing a display of these subsets in statistical, structural, schematic, electric or functional form.
However, it is possible for a part of a structure, even a limited one, to retain a high level of complexity. It is also possible for a structural description to be insufficient to achieve a technological migration which requires a functional specification.
In order to eliminate these additional problems, the invention also provides an analysis process characterized in that it comprises a first structural and functional abstraction step for generating a set of functional and structural computer data.
On the other hand, while regenerating a physical structure using only manual and intellectual methods is difficult, doing it in a purely automatic way risks creating problems of conformance between the structure produced and the structure expected. An automatic procedure does not allow the production of certain structures.
For this reason, the inventive process makes it possible, during analysis, to create a division between that which can be produced automatically and that which requires manual intervention. The invention also an analysis process characterized in that the first step controls an automatic synthesis step which generates, from the set of abstract computer data, a set of concrete computer data for regenerating a physical structure.
The knowledge required to produce a functional and structural abstraction of a physical structure that is unknown a priori is not always available.
For this reason, the invention also provides an analysis process characterized in that the first step generates a computerized data set which contains the knowledge for
Barbier Denis
Guignet Jean-Bruce
Bull S.A.
Garbowski Leigh Marie
Kondracki Edward J.
Miles & Stockbridge P.C.
Smith Matthew
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