Hi

If you’ve ever wondered why we moved from planar transistors to FinFETs and now to gate-all-around, the answer starts with one core idea: short-channel effects. As transistors got smaller, the drain’s electric field began to “reach under” the gate and weaken its control of the channel. Threshold voltage dropped, leakage shot up, and reliability became harder. That single shift in device physics changed how we design CPUs, GPUs, and today’s AI chips—and it’s exactly why interviewers love to ask about it.

This blog explains the idea in plain language and invites you to learn it hands-on in our upcoming workshop. Registration closes in 1 day.

Why this concept matters (in simple words)

• In a long transistor, the gate is the boss. In a very short one, the drain starts interfering.
• Result: the transistor turns “on” too easily (lower VTV_TVT​), leaks when it should be off, and heats up more.
• The whole industry responded with better electrostatics: lightly-doped drains and halos → FD-SOI → FinFETs → gate-all-around. We also changed design styles: multicore over raw frequency, aggressive power gating, multi-VTV_TVT​ cells, new SRAM tricks, and more.

How it shaped high-speed CPUs/GPUs and AI chips

• Speed improved because devices got shorter, but power became the limiter. That’s why modern processors don’t just crank the clock—they scale out with cores, SIMD, and accelerators.
• Memory (especially SRAM) became delicate at low voltage, so caches need careful design and assist circuits—critical for AI, where on-chip memory dominates energy.
• Better transistor control (FinFET/GAAFET) gives the density and efficiency that make AI inference and training practical on today’s silicon.

The interview angle: why it’s often the first question

Hiring managers want to see you connect device → circuit → architecture:

• “What are short-channel effects?”
• “Why did we move to FinFETs?”
• “How do DIBL and subthreshold slope affect leakage, timing, and SRAM?”
  If you can answer these clearly—and show a SPICE plot or two—you stand out.

Learn it the right way: hands-on with SKY130 + SPICE

Workshop: CMOS Circuit Design & SPICE Simulation using SKY130 Technology
Register: https://www.vlsisystemdesign.com/cmos-circuit-design-spice-simulation-using-sky130-technology/

Deadline: Closes in 1 day

What you’ll do (plain and practical)

• Set up an open SKY130 environment and run ngspice simulations.
• Build understanding from MOSFET basics to CMOS logic.
• Plot and read I-V curves, transfer characteristics, rise/fall delays, and noise margins.
• See the fingerprints of short-channel behavior in the data (DIBL, subthreshold).
• Model a CMOS inverter and ring oscillator, measure delay and power, and relate it to real timing/energy trade-offs.
• Leave with a small portfolio of simulation results you can show in interviews.

Who should join

• Students and early-career engineers preparing for analog, digital, or verification roles.
• Software/embedded folks crossing into silicon and VLSI.
• Anyone who wants the “why” behind modern CPU/GPU/AI design choices.

What you’ll take away

• A clear, interview-ready explanation of short-channel effects and why they changed everything.
• The ability to prove concepts with SPICE plots, not just theory.
• Confidence to discuss how device physics affects power, performance, area, and reliability—the same PPA-R language teams use every day.

A 30-second interview script you can practice

Q: Why did the industry move from planar MOSFETs to FinFETs?
A: As channels shrank, short-channel effects (especially DIBL) reduced gate control, lowered VTV_TVT​, and increased leakage. FinFETs wrap the gate around the channel, improving electrostatics and subthreshold slope, so we can keep density and speed while containing power and variability. That directly improves timing, SRAM stability, and overall energy efficiency for CPUs/GPUs and AI accelerators.

Seats are limited and registration closes in 1 day.
If you want to answer the #1 device-physics question with confidence—and back it up with real simulations—join us now:

https://www.vlsisystemdesign.com/cmos-circuit-design-spice-simulation-using-sky130-technology/