Active solid-state devices (e.g. – transistors – solid-state diode – Regenerative type switching device
Reexamination Certificate
2002-01-07
2003-10-28
Dang, Phuc T. (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Regenerative type switching device
C257S140000, C438S014000
Reexamination Certificate
active
06639252
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an integrated circuit and to a method for fabricating an integrated circuit.
The complexity of integrated circuits and the speed at which they operate are continually increasing and it is primarily because of this that integrated circuits have the problem that the users of the integrated circuits, more precisely the users of the modules containing the integrated circuits, are often no longer able to identify and eliminate the causes of improper functioning of the integrated circuits and/or of the systems containing the integrated circuits.
For this reason, so-called emulators were developed for particularly complex integrated circuits such as, for example, microprocessors and microcontrollers. These emulators can be used, during normal operation of an integrated circuit, to observe and change as desired internal states and sequences in the integrated circuit (for example register contents, memory contents, and/or addresses, data, control signals transmitted via internal or external lines or buses, etc.).
During the emulation of an integrated circuit, the latter (the module containing the latter) is generally moved from the system containing it and replaced by a special circuit, this special circuit containing the integrated circuit itself that is to be tested (if the integrated circuit removed from the system is inserted into the special circuit) or a particular version of the integrated circuit (a so-called bond-out version which has additional terminals for observing internal states or operations). Such an emulation has a number of disadvantages.
One of the disadvantages is that removing the integrated circuit from the system and replacing it by a circuit of whatever configuration is either not possible at all (for example if the integrated circuit to be emulated is soldered in or difficult to access or surrounded by a Faraday cage), or is at least very complicated.
A further disadvantage is that during the emulation of the integrated circuit to be emulated, on account of the changes required for this, the system often no longer behaves exactly as in normal operation. This has two causes: firstly because the integrated circuit to be emulated is replaced by a special circuit, and secondly because the special circuit usually no longer contains the integrated circuit itself that is to be emulated, but rather a particular version (the bond-out version already mentioned) of the integrated circuit.
Furthermore, the development and fabrication of a bond-out version of integrated circuits are very complicated and expensive. Moreover, bond-out versions are often available on the market only after the standard versions of the integrated circuits are available.
In order to avoid these disadvantages, one has resorted in the meantime to equipping in particular relatively complex integrated circuits with a so-called on-chip debug support module (OCDS module) as standard. However, integrating an OCDS module into the integrated circuit makes the latter considerably larger and more expensive than would be the case without the OCDS module, and counteracts endeavors to fabricate integrated circuits which are smaller and smaller and less and less expensive. This is particularly distressing because integrated circuits with an OCDS module are generally not offered without an OCDS module, and because the OCDS module of an integrated circuit is required at most for the system development but not for the normal operation of the integrated circuit.
These disadvantages are even more pronounced if the OCDS module not only has breakpoint functionality but additionally contains measures which also enable the program flow and data accesses to be observed (trace function).
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an integrated circuit and a method of fabricating an integrated circuit which overcome the above-mentioned disadvantages of the heretofore-known integrated circuits and fabrication methods of this general type and which provide the conditions that allow emulating an integrated circuit simply and reliably under all circumstances.
With the foregoing and other objects in view there is provided, in accordance with the invention, an integrated circuit, including:
a first circuit section; and
a second circuit section operatively connected to the first circuit section, the second circuit section being configured to be necessary or useful for emulating the first circuit section.
With the objects of the invention in view there is also provided, a method for fabricating an integrated circuit, the method includes the steps of:
fabricating an integrated circuit by using exposure masks respectively including patterns for fabricating a first circuit section of the integrated circuit and patterns for fabricating a second circuit section of the integrated circuit; and
selectively covering a respective part of the exposure masks that serves for fabricating the second circuit section during a fabrication of a first variant of the integrated circuit, and leaving the respective part of the exposure masks that serves for fabricating the second circuit section uncovered during a fabrication of a second variant of the integrated circuit.
A preferred mode of the method according to the invention includes the step of using displaceable elements of a screen for covering regions of the exposure masks that are to be covered.
In other words, the object of the invention is achieved by virtue of the fact that the integrated circuit includes a first circuit section and a second circuit section, which is necessary or useful for the emulation of the first circuit section, and, respectively, by virtue of the fact that that exposure masks are used for fabricating the integrated circuit, on which masks there are respective patterns for fabricating a first circuit section of the integrated circuit and patterns for fabricating a second circuit of the integrated circuit section, and in that that part of the exposure masks which serves for fabricating the second circuit section is covered during the fabrication of a first variant of the integrated circuit, and remains uncovered during the fabrication of a second variant of the integrated circuit.
A module which contains the abovementioned second circuit section is a module which does not have to be taken from the system containing it and need not be replaced by a special circuit in order to be emulated. The emulation of such a module can therefore be carried out extremely simply and reliably under all circumstances.
Moreover, an (emulatable) module containing the first circuit section and the second circuit section is, surprisingly, not larger than a (non-emulatable) module containing only the first circuit section. This is because for quite a long time the size of a module containing an integrated circuit, more precisely the size of the housing of the module, does no longer depend on the size of the integrated circuit. What is critical for the size, rather, is the number of input and/or output terminals of the module and the mutual spacing which these input and/or output terminals must have as a minimum in order that they can still be connected to assigned contact points. In general, in particular in the case of more complex modules such as microprocessors, microcontrollers, etc., an integrated circuit contained therein can be enlarged without an accompanying enlargement of the module.
Irrespective of this, it is possible in an extremely simple manner to fabricate an emulatable and a non-emulatable version of the module. An emulatable version of the module is developed and the second circuit section is simply omitted during the fabrication of the non-emulatable version of the module.
The procedure for omitting the second circuit section may be that, during the module fabrication, the work is always carried out using an exposure mask for the emulatable module, and that that part of the exposure mask which contains the patterns for the second circuit section is simply cover
Dang Phuc T.
Greenberg Laurence A.
Infineon - Technologies AG
Locher Ralph E.
Stemer Werner H.
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