A transistor integrated circuit particularly for use in transaction cards such as credit cards or payment cards comprises conductive film zones on the surface of the circuit having a shape and layout which makes it difficult or impossible to determine the layout of the circuit. Additional metal zones may be formed at the level or below the level of the transistor connection strips, which cannot be eliminated without eliminating the strips. Alternatively, instead of strips, metal zones extended in two dimensions are used whereby their junction to an underlying transistor may not be easily located by observing their surface by microscopic means.
A monolithically integrated semiconductor circuit assembly includes a silicon substrate, an active layer with active electrical structures in a semiconductor circuit disposed on the silicon substrate, a passivating layer disposed on the active layer, at least one electrically conducting protective layer disposed on the passivating layer at least above the active electrical structures, and a casing disposed above the protective layer.
A method for detecting the presence of a passivation layer on an integrated circuit comprises sending out a train of pulses of different widths at one end of a line of metal that winds on the surface of the integrated circuit beneath the protection layer of the integrated circuit. The line of metal and the dielectric layer of the integrated circuit form an RC filter. The number of pulses received at the other end of the line of metal is counted and compared with at least one characteristic reference value of the filter.
A semiconductor chip with a surface covering includes circuits which are produced in at least one layer of a semiconductor substrate and disposed in at least one group. Supply and signal lines extend in at least one interconnect plane over at least one circuit group and have a maximum width so that a distance between each two lines is at a minimum.
The invention relates to a thick-film circuit arrangement having an electronic circuit which is constructed on a surface (17) of a ceramic substrate plate (3) and which consists of conductor paths (5), resistors, capacitors and components, in particular integrated switching circuits without a housing, formed according to thick-film technique. This structure has between the electrically conductive structures (5) a sintered, nonconductive paste substantially filling the intermediate spaces between them and both the structures and the interposed pastes are covered by a sintered insulating paste. For concealing the thick-film circuit arrangement from unauthorized access, the following covering construction is carried out: 1. the paste in the intermediate spaces fills the same between the electrically active thick-film conductor structures in such a manner that the tops of the electrically active structures and the insulating filling layer (7) formed from an insulating paste and filling the intermediate spaces between them are situated substantially in one plane, and 2. the insulating paste is provided over the combined conductor/filling layer (11) in a covering and smoothing manner to form at least one insulating first thick-film anti-access layer (13) which, by additional observation-impeding inclusions (dyes, particles) impedes an optical recognition of the underlying structures, especially when the first thick-film anti-access layer or layers is or are not succeeded by further anti-access layers.
A device for neutralizing the access to an integrated-circuit zone to be protected. A fuse section providing a connection between an access terminal and an integrated circuit zone to be protected is connected by means of the fuse end portion located nearest the zone to be protected to a junction obtained at the intersection of a layer of a conductivity type opposite to the conductivity type in which the substrate of the integrated circuit is formed. This junction is reverse-biased during normal utilization of the circuit and forward-biased only when it is desired to melt the fuse, thus making the zone to be protected irreversibly inaccessible.
