Moortec Semiconductor Target Stacked DRAM Applications With Its High Accuracy On-Chip Temperature Sensor

Moortec Semiconductor, provider of high accuracy on-chip temperature sensors for advanced-node CMOS technologies, target 3D stacked Dynamic Random Access Memory (DRAM) applications supporting temperature compensated refresh rate schemes and optimised power performance. The high accuracy, high resolution temperature sensor offering extends Moortec's position as a leading provider of embedded Process, Voltage and Temperature (PVT) monitors to semiconductor customers worldwide.

DRAM has become essential to the fabric of memory systems within modern electronic products. The nature of DRAM technology requires each memory cell to be periodically refreshed to prevent loss of data. However, memory retention decreases with higher die temperatures requiring increased refresh rates. Several factors compound the issue of temperature dependant data retention. Two such factors are due to heating caused by the increased cell, and therefore power, densities possible with advanced node CMOS technologies (28nm down to 10nm) and also due to higher speeds of data transfer. For planar CMOS technologies leakage also increases with temperature and there are examples where the refresh rate of DDR2 SDRAM chips, to be JEDEC compliant, must double if temperatures exceed 85°C (185°F). In addition, increased refresh rates lead to increased activity and hence increased temperature. To further compound thermal dissipation issues DRAM is often part of 3D stacked configurations, which may also include a controller System on Chip (SoC).

“For memory developers there is a well-understood need to optimise power performance to remain competitive,” said Stephen Crosher, Managing Director of Moortec Semiconductor. “Thermal sensing and management is now a key element to advanced node device performance and to give our customers the edge we are able to offer high accuracy on-chip temperature sensing. The optimisation of DRAM Memory stacked with a controller SoC is another application where Moortec believes it has the most compelling and commercially available thermal monitoring IP solution,” Crosher continued to add.

With an uncalibrated accuracy of +/-3C and a calibrated accuracy of +/-1C, across the temperature range of -40C to 125C, the high accuracy temperature from Moortec also offers a resolution of 0.06C. The sensor IP has a single point calibration scheme and also interfacing that allows easy access for bench testing as well as production testing. With accurate thermal monitoring applied to each device, and when considering the greater process variability in the manufacture of advanced node devices, developers are able to deploy performance optimisation schemes, such as Dynamic Voltage and Frequency Scaling (DVFS), with a greater sensitivity.

Beyond DRAM optimisation, other applications for the temperature sensor include device security, critical temperature alerts and device characterisation. Moortec also offer on-chip Voltage Monitoring IP for both steady state and transient core supply monitoring to customers world-wide. To provide the complete on-chip PVT monitoring solution, Moortec are currently developing their Process Detector IP for delivery in Q3 2014.

By providing a complete PVT monitoring solution, Moortec believe that each and every advanced node device manufactured in the future can be performance optimised and be statistically analysed for device variability on a scale not seen before. Moortec believe that PVT harvested data from in-chip monitors will significantly assist the development of strategies to help mitigate the wider process variability seen on advanced node technologies.