Advanced Micro Devices Corporation

Globalfoundries Inc.

Matthew L Thayer

Jeffrey David Birdsley

Ronald M Potok

A memory device is disclosed that includes multiple bit cells, whereby each bit cell is capable of being programmed to more than two states. A value stored at the memory device is determined by comparing the information stored at three or more of the bit cells. In an embodiment, the bit cell includes a silicon-on-insulator (SOI) metal oxide semiconductor field effect transistor (FET) device, and the information stored at the bit cell can be represented by a corresponding level of charge stored in the body of the device.

Memory device and methods thereof

According to an example embodiment, a semiconductor device having a back side and a circuit side opposite the back side is analyzed. The semiconductor device includes bulk silicon in the back side and also includes epitaxial silicon. An ion gas comprising SF and N is directed at a target region in the back side. Using the ion gas, the target region in the back side is selectively etched using reactive ion etching (RIE) and an exposed region is formed. The etching is selective to the bulk silicon. When the etching process encounters the epitaxial silicon, the etch rate slows and is used as an endpoint indicator of the selective etching process. Once the etching process is stopped, the circuitry is accessed via the exposed region.

Selective back side reactive ion etch

Current reactive ion etching (RIE) techniques are not applicable to back side etching of semiconductor devices. According to an example embodiment, the present invention is directed to a method for analyzing a semiconductor device having a back side and a circuit side opposite the back side. An ion gas including SF,and N,is directed at a target region in the back side. Using the ion gas, the target region is etched using reactive ion etching (RIE). An exposed region is formed, and circuitry in the device is accessed via the exposed region. The use of the ion gas enables back side RIE that is capable of producing an etched surface that is usable for back side access.

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Matthew L Thayer