Abstract: Embodiments of the present invention provide an improved contact and method of fabrication. A dielectric layer is formed over transistor structures which include gates and source/drain regions. A first etch, which may be a reactive ion etch, is used to partially recess the dielectric layer. A second etch is then used to continue the etch of the dielectric layer to form a cavity adjacent to the gate spacers. The second etch is highly selective to the spacer material, which prevents damage to the spacers during the exposure (opening) of the source/drain regions.

Abstract: A SiGe heterojunction bipolar transistor is fabricated by etching an epitaxially-formed structure to form a mesa that has a collector region, a cap region, and a notched SiGe base region that lies in between. A protective plug is formed in the notch of the SiGe base region so that thick non-conductive regions can be formed on the sides of the collector region and the cap region. Once the non-conductive regions have been formed, the protective plug is removed. An extrinsic base is then formed to lie in the notch and touch the base region, followed by the formation of isolation regions and an emitter region.

Abstract: A SiGe heterojunction bipolar transistor is fabricated by etching an epitaxially-formed structure to form a mesa that has a collector region, a cap region, and a notched SiGe base region that lies in between. A protective plug is formed in the notch of the SiGe base region so that thick non-conductive regions can be formed on the sides of the collector region and the cap region. Once the non-conductive regions have been formed, the protective plug is removed. An extrinsic base is then formed to lie in the notch and touch the base region, followed by the formation of isolation regions and an emitter region.

Abstract: A single, controlled etch step can be used to form a sharp tip feature along a sidewall of an etch feature. An etch process is used that is selective to a layer of tip material relative to the substrate upon which the layer is deposited. A lag can be created in the etch, such that the etch rate is slower near the sidewall. The sharp tip feature is formed from the same layer of material used to create the etch feature. The sharp tip feature can be used to decrease the minimum critical dimension of an etch process, such as may be due to the minimum resolution of a photolithographic process. The novel tip feature also can be used for other applications, such as to create a microaperture for a photosensitive device, or to create a micromold that can be used to form objects such as microlenses.