Method for manufacturing a bipolar transistor

A method for manufacturing a bipolar transistor in a single-crystal substrate of a first conductivity type, comprising the steps of:

• growing on the substrate at least one first semiconductor layer of the second conductivity type;
• depositing at least one encapsulation layer selectively etchable with respect to the underlying semiconductor layer;
• forming a sacrificial block at the location where the base-emitter junction of the transistor is to be formed;
• forming lateral spacers around the block;
• exposing the first semiconductor layer around the block on either side of the lateral spacers;
• growing by selective epitaxy a second heavily-doped semiconductor layer of the second conductivity type;
• growing by selective epitaxy a third semiconductor layer selectively etchable with respect to the second semiconductor layer, the encapsulation layer and the lateral spacers, the sum of the thicknesses of the second semiconductor layer and the sacrificial layer being substantially equal to the sum of the thicknesses of the encapsulation layer and the sacrificial block;
• selectively removing the block and the underlying encapsulation layer to expose the first semiconductor layer;
• depositing and etching a fourth heavily-doped semiconductor layer of the first conductivity type;
• removing the third semiconductor layer;
• and
• depositing and anisotropically etching an insulating layer to maintain it in place on the lateral walls of the emitter and between said emitter and the second semiconductor layer.