CIFRE - Advanced Research M/F

Topic description

STMicroelectronics is one of the world's largest semiconductor companies with net revenues of US$ 16 billions in . Our technology is found everywhere : microelectronics makes a positive contribution to people's lives and we are continuously investing in our footprint as an independent device manufacturer.

The company operates in various markets, including automotive, industrial, personal electronics, and communications offering a wide range of semiconductor products, including microcontrollers, sensors, power management, and digital ICs.

STMicroelectronics is the leader in microcontroller market, offering a wide range of applications from low cost to very high performances solution.

More specifically, STMicroelectronics is a leading actor for microcontroller products in different technologies. Indeed, floating gates memories followed recently by proprietary embedded Phase Change Memory (ePCM) technology allows STM to be at the leading edge for process and product on embedded Non-Volatile Memory (eNVM) technology.

STM proprietary ePCM technology is the current eNVM benchmark thanks to its best-in-class reliability and small cell size, largely due to the specific GST material composition.

ePCM technology is now in production at the 28 nm node, and under qualification at the 18 nm node.

For future eNVM PCM nodes, a smaller footprint as well as a programming current reduction is requested to keep the leading edge with respect to competing memories (MRAM, and OxRAMs).

Those optimizations imply a physical reduction of the ePCM memory dimensions in three directions. In the X direction : a reduction of the heater width will decrease the consumption.

In the Y direction, a decrease of the metal zero (M0) space will improve the disturb between cells. Finally, in the Z direction, new integration is required to move to advanced nodes technology.

Historically, the physical shrink has shown a degradation of the retention properties of the PCM cell, not understood yet.

In this context, the subject of the PhD is to study and help to better understand the ePCM improvements path for physical shrink of the ePCM cell with our partner.

STM Crolles for integration possibilities to acquire statistical data, STM Agrate (in Italie) for electrical measurement facilities and expertise and CNRS CEMES (Toulouse) for physical analysis, modelization capabilities and expertise to understand the root cause of the ePCM cell retention degradation with dimensions reduction.

P28 and P18 technology (28 nm and 18 nm technology nodes respectively) will be used to explore the cell dimensions reduction by adapting process and technologies using qualified ePCM designs.

Statistical data will be acquired within this mature environment, that will allow us to asses distinctly the electrical parameters.

Electrical results will be put regarding the process splits and physical analysis will be launched to understand these results.

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