Few key examples in the domain of the OxRAM, CBRAM and PCRAM will be provided in order to target the high temperature data retention specifications of emebedded memory market.
Some tradeoffs appears in each of the aforementioned technologies, like stability against temperature stress versus crystallization speed in PCRAM; or stability against temperature versus forming or programming voltages in CBRAM (in particular chalcogenide based CBRAM with respect to oxide based CBRAM).
In order to develop an optimized memory stack and accelerate the adoption of these new technologies, LETI offers a so-called Memory Advanced Demonstrator (MAD) that is today based on 130 nm ground rules with 4 copper metal lines. The memory module that can consist of PCM, or OxRAM, or CBRAM or MRAM technology is fabricated in the BEOL before pad level. This versatile test vehicle offers the possibility to have on the same silicon test structures spanning from simple resistors (1R), resistors with its selector transistor (1T1R), memory arrays (1kb cuts) up to complex designs allowed by the routing placed on the 4 metal levels. Such complex design may come from client designers using DK plus memory add-on provided by LETI.
All such structures are essential for a deep analysis of the memory functionality: from bulk material (with its interfaces) screening, obtained by the 1R and 1T1R; passing through statistical analysis of extrinsic bits, obtained by memory arrays; up to first validation of complex functions obtained by specific designs.
MAD offers also a benchmark opportunity between different technologies with the same test vehicle in order to extract benefits and drawback from each of them.