U.S. Philips Corporation

Catharina H Emons

Doede Terpstra

Cornelis Eustatius Timmering

Wiebe B De Boer

Godefridus A Hurkx

Willem Van Der Wel

The invention relates to the manufacture of a so-called differential bipolar transistor comprising a base (1A), an emitter (2) and a collector (3), the base (1A) being formed by applying a doped semiconducting layer (1) which locally borders on a monocrystalline part (3) of the semiconductor body (10) where it forms the (monocrystalline) base (1A), and which semiconducting layer (1) borders, outside said monocrystalline part, on a non-monocrystalline part (4, 8) of the semiconductor body (10) where it forms a (non-monocrystalline) connecting region (1B) of the base (1A). The non-monocrystalline part (4, 8) of the semiconductor body (10) is obtained by covering the semiconductor body (10) with a mask (20) and replacing on either side thereof a part (8) of the semiconductor body (10) by an electrically insulating region (8) and by providing this, prior to the application of the semiconducting layer (1) with a polycrystalline semiconducting layer (4). The known method, in which an aperture is etched above the collector (3) after deposition of the polycrystalline layer (4), is relatively laborious. In a method in accordance with the invention, the polycrystalline layer (4) is selectively provided on the electrically insulating region (8), in which process use is made of the mask (20) to form the electrically insulating region (8). This method is less laborious than the known method. In addition, the resultant transistors have excellent properties and their dimensions may be very small. Preferably, both in the manufacture of the insulating region (8), preferably an oxide-filled groove (8), and in the process of selectively applying the polycrystalline layer (4) to the insulating region, use is made of a deposition step followed by a chemico-mechanical polishing step.

Method of manufacturing a semiconductor device with a bipolar transistor

The invention relates to a method of manufacturing a discrete or integrated bipolar transistor comprising a base (1A), an emitter (2) and a collector (3). The base (1A) and a connecting region (1B) of the base (1A) are formed by providing a semiconductor body (10) with a doped semiconducting layer (1) which locally borders on a monocrystalline part (3) of the semiconductor body which forms the collector (3). Outside said base, the layer (1) borders on a non-monocrystalline part (4) of the semiconductor body (10) and forms a non-monocrystalline connecting region (1B) of the base (1A). By means of a mask (5), the doping concentration of the layer (1) outside the mask (5) is selectively increased, resulting in a highly conducting connection region (1B) and a very fast transistor. In the known method, an ion implantation is used for this purpose. In a method in accordance with the invention, this is achieved by bringing the semiconductor body (10) into contact with a gaseous substance (40) comprising a doping element, and heating the semiconductor body (10) in such a manner that the doping elements penetrate into the semiconducting layer (1). Such a method surprisingly results in a much faster transistor. It has been found that this enables, on the one hand, a much smaller diffusion in the thickness direction of the doping of the base (1A) to be achieved, which results in a much faster transistor, particularly, if the base (1A) contains SiGe. On the other hand, the lateral diffusion from the connecting region (1B) to the base (1A) is particularly strongly suppressed. This too has a beneficial effect on the speed of the transistor. The supply of the gaseous substance (40), for example diborane, preferably takes place at a temperature between 800 and 950.degree. C. for one to several minutes. Subsequently, a slightly longer diffusion step can be carried out, for example, at 850.degree. C.

Method of manufacturing a semiconductor device with a fast bipolar

The continuing miniaturization of integrated circuits leads to a demand for ever higher resistance values. In conventional diffused resistors or poly resistors, an increase in the resistance value also means an increase in the surface area. Such resistors, moreover, are highly dependent on the doping concentration and sensitive to temperature changes. A resistor according to the invention comprises a resistor region 18 with a length and doping concentration which are chosen such that an electric field is applied at which velocity saturation of charge carriers takes place in the envisaged range of operation. The connection regions are connected to the resistor region via rectifying junctions 21, 22. In a specific embodiment, these junctions are formed by pn junctions, so that the resistor has, for example, an npn shape. The dimensions are furthermore chosen such that, within said operational range, electrons are injected into the p-type resistor regions by punch-through between the n-type connection regions 19, 20, traversing the resistor region at the saturation velocity. Since the charge carriers supplying the current are of the type opposed to that of the resistor material, it is prevented that the resistance value becomes very low at low voltages.

Growing community of inventors

Nijmegen, Netherlands

Catharina H Emons