U.S. Philips Corporation

Leonardus J Van Roozendaal

Reinier De Werdt

Rene G Penning De Vries

Samuel J Nagalingam

A semiconductor device (1) includes a circuit having at least one transistor Tr1 and first and second electrodes (30) and (32). A protection element (20) having a device region (21) forming a pn junction (23) within the semiconductor body (10) and covered by an electrode layer (21c) is connected via an electrode (27) to one (30) of the first and second electrodes for providing a conductive path between the first and second electrodes (30) and (32) when a voltage above a threshold voltage is applied to the first electrode (30). The electrode layer (21c) forms with at least part (21a) of the device region (21) a potential barrier (B) for causing the conductive path provided by the protection element (20) to pass from the electrode (27) to the pn junction (23) at least partly via the device region (21) of the protection element (20) thereby increasing the resistance of the path to the pn junction (23).

ESD protection element for CMOS integrated circuit

The invention relates to an integrated circuit connected via a first connection conductor (61) to a first contact area. Between the first connection conductor (61) and a second connection conductor (63), a protection element (8) is connected, which protects the circuit especially from electrostatic discharges. The protection element (8) comprises an active zone (81), which is covered with metal silicide (15) and forms a pn junction (86) with the adjoining part (83) of the semiconductor body (10). On the metal silicide (15), the active zone (81) is provided with an electrode (16), through which the zone (81) is connected to the first connection conductor (61). The use of metal silicide in the integrated circuit in itself has great advantages, but in the protection element the metal silicide layer is found to give rise to a considerably lower reliability. The invention has for its object to obviate this disadvantage without it being necessary to modify the manufacturing process. According to the invention, in order to improve the uniformity of the current distribution over the pn junction (86), between the electrode (16) and the pn junction (86), a resistance element (9, 91, 92) is connected in series with the protection element (8) directly to the active zone (81) of the protection element (8), whose width is substantially equal to the width of the active zone (81). Such a resistance element can be entirely realized within the process of manufacturing the integrated circuit.

Semiconductor device provided with a protection circuit

A semiconductor device comprises a semiconductor body (1) of silicon having a monolithic integrated circuit with a field oxide pattern (2) having at least one protection element (T2) having at least one active zone (4) of a first conductivity type, which adjoins at least in part the field oxide (2) and forms with the adjoining silicon region (5) of the second opposite conductivity type a pn junction (6). The active zone (4) is contacted with an electrode layer (7), which is connected to a point (G) of the semiconductor device to be protected against static discharge. The electrode layer (7) consists of a metal silicide. According to the invention, the metal silicide (7) also extends onto the field oxide (2) adjoining the active zone (4) over a certain distance, which is preferably at least 0.5 .mu.m.

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Eindhoven, Netherlands

Leonardus J Van Roozendaal