Charge storage depletion region discharge protection
USH569H · kind H · statutory invention registration
Assignee
Inventors
Key dates
| Filing date | — |
| Grant date | Jan 3, 1989 |
| Priority date | — |
| Expiry date | — |
Classification
- Technology area (CPC —)General
Abstract
A means and method is described for shielding semiconductor charge storage devices from the effects of particles or ionizing radiation absorbed within the bulk of the semiconductor substrate, by providing a free carrier shield consisting of a buried layer of very low lifetime in the undisturbed material below the depletion regions associated with the charge storage devices. The very low lifetime layer is obtained by ion implantation of a super-saturated zone of impurities such as oxygen which provide deep recombination centers and which react chemically with the substrate material so as to provide thermally stable complexes which do not anneal away during post implant heating cycles. Concentrations of lifetime killing impurities significantly exceeding the solid solubility limit are achieved so that the lifetime reduction in the carrier shield region greatly exceeds that obtainable by prior art methods. Partial shielding is also provided against carriers injected by nearby junctions or introduced by charge pumping during circuit operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.