576
6 Reverse Engineering of Microcircuits
formalized at all. Until recently, solving these problems was usually the exclusive
prerogative of the engineer, who used the entire set of theoretical knowledge and
experience for that. Problems of automation of processing bitmap topological multilayered images in some cases turn out to be far from trivial [15]; therefore, at the
moment of publication of this book, the task of automating the process of recovery
of an electrical circuit based on its bitmap topology image has been solved only for
certain general cases, and this process currently requires human interference at early
stages. When recovering an electrical circuit, it is necessary to solve two tasks: the
task of arranging circuit elements and the task of tracing the circuit, i.e., arranging the
conductors. Element arrangement process is the most important and difficult task, as
the automation of this stage helps minimize the time required for circuit recovery.
However, the task of arranging elements itself also has two ways of solution:
vectorization of the bitmap topology image or direct recovery of the electrical circuit.
In case of bitmap image vectoring, the bitmap image analysis results in vector description of the topology (vector rectangles), which are transmitted to specialized software
means, and the electrical circuit is generated with their help. Direct recovery of the
circuit results in an electrical circuit that can be further transferred to standard design
systems (CAD).
Any method can be used to obtain an electrical circuit; however, restoration of the
circuit through topology vectoring is the most labor-intensive task, since it requires
drawing all technological layers, even the ones that are invisible on the original
bitmap images. All features of the presented method of circuit reproduction shall be
taken into account when creating automation systems.
Software support for arrangement of circuit elements on a bitmap image suggests
creating specialized software and databases of topology images of image elements
(element library); moreover, the database shall contain both single elements (transistors, resistors, inductances, etc.) and logic elements (AND, NAND, OR, etc.)
and functional blocks (amplifiers, generators, etc.). When creating such element
libraries, it is necessary to include information that is not only readable by computing
devices (computers, servers) but also convenient for use by the developing engineer.
Creation of optimized element libraries makes it possible to reduce the load on the
reverse-engineering system operator.
In topology analysis, images of microstructures obtained with the help of optical
or scanning electronic microscopes are most commonly used as source material;
therefore, information about various topology elements that are later included in the
library is usually presented in bitmap form. However, bitmap image alone is often
not enough, since topological images of elements often differ insignificantly and are
indistinguishable at first sight. In order to identify such non-obvious features of the
elements of topology, it is necessary to provide auxiliary information (vector drawing
of the topology) to the operator. In such cases, topology description coincides with
the description used in CAD programs. It is also necessary to ensure the possibility
to view the bitmap image separately from its vector description. Another necessary
condition is the possibility to rotate images and rescale them arbitrarily. It is also
necessary to take into account the fact that various IC manufacturers use seemingly
equivalent elements with unique design and technological solution; therefore, when
6 Reverse Engineering of Microcircuits
formalized at all. Until recently, solving these problems was usually the exclusive
prerogative of the engineer, who used the entire set of theoretical knowledge and
experience for that. Problems of automation of processing bitmap topological multilayered images in some cases turn out to be far from trivial [15]; therefore, at the
moment of publication of this book, the task of automating the process of recovery
of an electrical circuit based on its bitmap topology image has been solved only for
certain general cases, and this process currently requires human interference at early
stages. When recovering an electrical circuit, it is necessary to solve two tasks: the
task of arranging circuit elements and the task of tracing the circuit, i.e., arranging the
conductors. Element arrangement process is the most important and difficult task, as
the automation of this stage helps minimize the time required for circuit recovery.
However, the task of arranging elements itself also has two ways of solution:
vectorization of the bitmap topology image or direct recovery of the electrical circuit.
In case of bitmap image vectoring, the bitmap image analysis results in vector description of the topology (vector rectangles), which are transmitted to specialized software
means, and the electrical circuit is generated with their help. Direct recovery of the
circuit results in an electrical circuit that can be further transferred to standard design
systems (CAD).
Any method can be used to obtain an electrical circuit; however, restoration of the
circuit through topology vectoring is the most labor-intensive task, since it requires
drawing all technological layers, even the ones that are invisible on the original
bitmap images. All features of the presented method of circuit reproduction shall be
taken into account when creating automation systems.
Software support for arrangement of circuit elements on a bitmap image suggests
creating specialized software and databases of topology images of image elements
(element library); moreover, the database shall contain both single elements (transistors, resistors, inductances, etc.) and logic elements (AND, NAND, OR, etc.)
and functional blocks (amplifiers, generators, etc.). When creating such element
libraries, it is necessary to include information that is not only readable by computing
devices (computers, servers) but also convenient for use by the developing engineer.
Creation of optimized element libraries makes it possible to reduce the load on the
reverse-engineering system operator.
In topology analysis, images of microstructures obtained with the help of optical
or scanning electronic microscopes are most commonly used as source material;
therefore, information about various topology elements that are later included in the
library is usually presented in bitmap form. However, bitmap image alone is often
not enough, since topological images of elements often differ insignificantly and are
indistinguishable at first sight. In order to identify such non-obvious features of the
elements of topology, it is necessary to provide auxiliary information (vector drawing
of the topology) to the operator. In such cases, topology description coincides with
the description used in CAD programs. It is also necessary to ensure the possibility
to view the bitmap image separately from its vector description. Another necessary
condition is the possibility to rotate images and rescale them arbitrarily. It is also
necessary to take into account the fact that various IC manufacturers use seemingly
equivalent elements with unique design and technological solution; therefore, when