| 摘要 |
<p>An improved means and method for forming junction isolated device regions is described wherein there is provided a semiconductor substrate (50) in which has been etched a tub (52) corresponding to the desired location and depth of the device. In a preferred embodiment, the tub is filled with three successive epitaxial layers. The first layer (53), of opposite conductivity type and more lightly doped than the substrate, conformally coats the bottom (52a) and sidewalls (52b) of the tub (52). A second layer (54), generally doped to the solid solubility limit, is formed conformally within the first layer (53). This serves as a buried collector region and provides a surface accessible contact to the buried collector. The third epitaxial layer (55) fills the tub (52) and acts as the device forming region. Higher breakdown voltages, lower isolation junction capacitance, and a more economical manufacturing process result.</p> |
