Method and apparatus for securing integrated circuits from unauthorized copying and use
US4766516A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 24, 1987 |
| Grant date | Aug 23, 1988 |
| Priority date | — |
| Expiry date | Sep 24, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/0002
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A security system and method for IC circuits has at least one additional circuit element that does not contribute toward the IC's circuit function, but inhibits proper functioning of the IC in case of an attempted copying or other unauthorized use. The identity of the additional circuit elements is disguised by forming them with the visible appearance of an apparent element but with a physical modification which is not readily visible but causes them to function in a different manner, by providing different ICs with unique control codes, or both. Physical modifications not readily visible to a copyist include very narrow open circuit cuts in metallized connection lines, preferably with a focused ion beam (FIB) or laser beam; and/or disordering the lattice structure or changing the doping level of a semiconductor region, preferably with a FIB; and/or injecting electrical charge into a semiconductor region, preferably with an electron beam. The additional elements can be formed into a control code subcircuit for the IC, with the code disguised by the use of apparent elements. ICs can be grouped into an operational ring in which control codes are transmitted serially through the ring,…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.