INTEGRATED CIRCUIT CONFIGURATION
COMPRISING A SHEET-LIKE SUBSTRATE
CROSS-REFERENCE TO RELATED
This application is a continuation of copending International Application No. PCT/DE02/00191, filed Jan. 22, 2002, which designated the United States and which was not published in English. 1°
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an integrated circuit configuration with a sheet-like substrate. An integrated circuit is formed on the sheet-like substrate, in a plurality of layers at least on one side. At least one surface of the substrate not planar in at least one propagation direction. The substrate is disposed on 20 a carrier, which imparts a curvature on the substrate.
The development costs of integrated circuits situated on a semiconductor chip are nowadays so high that it is increasingly becoming of interest for competitors to analyze them in order to copy them. Moreover, some of today's attacks on semiconductor chips, which can jeopardize their security, are based on detailed knowledge of the internal construction of these modules. Therefore, for security reasons, too, attempts are made to prevent an attacker from learning 3Q details about the construction of such a semiconductor chip. Furthermore, in the meantime, applications in which the integrated circuits have data stored in resident fashion have become customary.
A multiplicity of methods have been disclosed heretofore 35 for protecting such modules from analysis. By way of example, it is known to cover the surface of integrated circuits in such a way that they cannot readily be analyzed optically. European patent application EP 0981162 Al, for instance, describes such protection. 40
However, such protective measures can be circumvented by uncovering the covering by means of careful grindingaway, even if the surface protection is resistant to etching. By successively removing the layers and photographing the layer respectively uncovered, the construction of the inte- 45 grated circuit can subsequently be analyzed in the case of configurations of this type.
U.S. Pat. No. 5,955,766 discloses forming an integrated circuit on a spherical substrate. However, that structure cannot be produced using conventional techniques. 50
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an integrated circuit configuration with a sheet-like substrate 55 which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for an integrated circuit configuration that offers high security against analysis with a low outlay.
With the foregoing and other objects in view there is provided, in accordance with the invention, an integrated circuit configuration, comprising:
a sheet-like substrate having at least one non-planar surface in at least one propagation direction; 65
an integrated circuit formed on the substrate in a plurality of layers at least on one side of the substrate;
the substrate having a micro structure with chemical or
physical changes causing mechanical stresses imparting a
curvature defining the non-planar surface of the substrate.
By virtue of the fact that the substrate, at least in one propagation direction, is brought from the planar form to a non-planar form (i.e., it is bent), with a tenable outlay it cannot be processed by means of grinding methods in such a way that the surface can be completely removed in an analyzable manner layer by layer.
The lack of planarity (i.e., non-planarity) in a second direction increases the security specified above. The substrate is deformed by the application of a material, for example an adhesive or a curable ceramic, which generates a high mechanical stress.
The desired deformation can also be produced by mechanical stresses which arise in the substrate itself, for example through alteration of the chemical or physical microstructure of the substrate. By way of example, implantation methods, diffusion methods or thermal methods can be utilized for this purpose. Soldering and connecting methods, for instance between a plurality of substrates arranged one above the other, can likewise be used, given suitable technology, to generate mechanical stresses in the substrate in a targeted manner.
A deformed substrate generally maintains its deformed shape after a certain time. In order to prevent the substrate from being brought back to a flat, planar form by a pressure being exerted, it is also possible for partial regions to be removed at least on one surface.
By the provision of elevations on the carrier, a very complex, non-planar surface form of the integrated circuit configuration can be obtained using simple means.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an integrated circuit configuration comprising a sheet-like substrate, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic side elevation showing a basic construction of an integrated circuit configuration on a semiconductor chip;
FIG. 2 is a side view of a first exemplary embodiment of an integrated circuit configuration according to the invention on a semiconductor chip;
FIG. 3 is perspective view of the surface in the case of a modification of the first exemplary embodiment;
FIG. 4 is a side elevation of a second exemplary embodiment according to the invention;
FIG. 5 is a side elevation of a modification of the second exemplary embodiment;
FIG. 6 is a side elevation of a second modification of the second exemplary embodiment; and
FIG. 7 is a perspective view of a possible surface configuration.