What is Gate-All-Around (GAA) and What Are Its Advantages?

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Samsung Gate All Around1. Evolution of Transistor Architecture

Transistors have evolved to reduce manufacturing costs while improving circuit performance by continuously scaling feature size as guided by Moore’s Law.

Conventional planar transistors are formed by placing the gate electrode on top of the channel region, thus effectively making the device conduct in a two-dimensional plane. This, however, limits the gate controllability of the channel charge as the gate length scales. The FinFET architecture was thus introduced to further allow feature-size scaling. In FinFETs, three sides of the channel are surrounded by gate electrodes.

By enhancing gate controllability of the channel charge, improved performance, reduced leakage current, and gate length scaling were achieved at even smaller footprints. Due to these advantages, FinFETs have allowed successful scaling of technology from the 14nm and beyond. However, further scaling of operating voltage has been extremely challenging. To overcome this limitation, Gate-All-Around (GAA) transistors which feature gate electrode on all four sides of the channel have been introduced.

This allows for significant improvements in performance with reduced operating power, leading to an evolution of new CMOS based technology.

2. Samsung Gate All Around Transistor, MBCFETTM

MBCFETTM is Samsung’s unique, patented, version of GAA. Conventional GAA requires a larger number of stacks due to the small nanowire format of the channel, which increases the process complexity. However, Samsung’s MBCFETTM channel is formed as a nanosheet, so that a larger current per stack is achievable, enabling simpler device integration.

3. Advantage of MBCFETTM

  1. Most Power-Efficient Technology: For the past few years, the industry has been working on reducing operating voltage. Lower operational voltage equates to better power efficiency. Reducing operating voltage below 0.75V with FinFET architecture has proven to be extremely difficult. However, with MOSFET’s better on-off behavior, further reduction of operating voltage is possible.
  2. Flexible Design Optimization: Depending on product requirements, either high performance or low power can be obtained by modulating the device channel width. In a FinFET structure, it is necessary to modulate the number of devices, fins, in a discrete way. Meanwhile, in MBCFETTM the nanosheet width can be flexible, just like planar-type devices, so that circuit performance can be optimized with better utilization of area at the design stage. Furthermore, MBCFETTM has greater potential, compared to FinFET, to improve performance in the same area by stacking additional nanosheets vertically.
  3. Compatible to Existing Process: Samsung defined MBCFETTM to be compatible with the existing FinFET process. This means MBCFETTM technology shares the same mature process tools and manufacturing methodology. This leads to a cost-effective platform and a fast ramp-up of customer’s products.

4. Power, Performance, and Area Benefits

7nm FinFETvs advanced node MBCFETTM In terms of PPA, designers can expect up to 50% lower power consumption, around 30% better performance, and 45% less area when compared to 7nm process technology.

Lauren Author

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