Why transistor structures changed
Planar MOSFETs face leakage, short-channel effects, and threshold-control problems as they shrink. FinFETs improve gate control by wrapping the gate around vertical fin sidewalls. GAAFET / nanosheet structures go further by surrounding stacked nanosheet channels, improving electrostatic control and design flexibility.
Process challenges
FinFET and GAAFET flows require more complex selective etching, epitaxy, stress engineering, high-k metal gates, spacers, and source/drain contacts. The more 3D the structure becomes, the harder morphology control gets. Nanometer-level shifts can change drive current, leakage, and threshold distribution.
Why GPUs care
A GPU repeats tens of billions of transistors across huge parallel arrays. Transistor density, switching speed, leakage, and operating voltage affect compute-unit count, clock speed, power, and thermals. Whether an advanced GPU can add compute within a power envelope starts with transistor-level efficiency.