As the semiconductor industry marches toward ever-smaller nodes and higher performance targets, Gate-All-Around (GAA) transistors have emerged as a promising architecture for pushing Moore’s Law forward. Offering significant improvements in electrostatic control, reduced short-channel effects and better scalability than FinFETs, GAA is on the edge to become the foundation for next-generation chips.

Yet, while GAA holds the key to advancing performance and efficiency, it also presents a new frontier of challenges—particularly in managing atomic-level defects and contamination. These seemingly minuscule imperfections can have massive impacts on device reliability, power consumption and overall manufacturing yield, directly influencing the business viability of GAA-based products.

Why GAA is a game-changer

GAA transistors offer a fundamental architectural shift by surrounding the channel with gate material on all sides, enabling superior electrostatic control over the channel, enhanced current drive with stacked nanosheets or nanowires, lower leakage current, leading to improved energy efficiency and more predictable scaling to sub-3nm nodes and beyond.

For chip designers and process engineers, GAA opens a path to higher logic density and better performance-per-watt—essential for mobile, AI, and high-performance computing applications.

The contamination challenge: Atomic-level defects in focus

With their ultra-thin, high aspect-ratio structures, GAA transistors are more sensitive than ever to atomic-level impurities. These defects can originate from residues from wet or plasma etching processes, oxygen or carbon contamination during epitaxial growth or deposition, metallic impurities introduced during ALD or PVD steps or vacuum process instability, leading to unintended reactions.

These impurities manifest as interface traps, charge scattering centers or non-uniform doping, which lead to critical issues:

Performance degradation: Atomic defects disrupt carrier mobility in nanosheet channels, reducing drive current and increasing variability across dies.

Power inefficiency: Charge traps and leakage pathways cause static power loss, counteracting one of GAA’s key benefits: low standby power.

Yield and reliability loss: Defect-driven variability and early-life failures result in lower wafer yields and necessitate costly redundancy or rework, impacting TTM (time-to-market) and ROI.

Business implications: Yield is the new KPI

For semiconductor businesses, atomic-level defects are not just technical nuisances—they’re strategic threats: As defect density drives down functional yield, unit cost per chip increases, threatening margins. Lower binning ratios reduce the availability of top-performance SKUs. Time-to-yield delays in high-volume ramp-ups can jeopardize contracts and customer confidence. Reliability concerns may hinder adoption in safety-critical or high-performance applications (automotive, data centers).

As a result, process control and material purity are now boardroom issues, not just cleanroom concerns.

Current mitigation methods—and their limitations

Semiconductor fabs are deploying a variety of strategies to address these atomic-level challenges:

1. Advanced cleaning techniques

Selective wet cleans and atomic-layer etches target particle and residue removal at the nanoscale.

  • Application: Post-etch, post-deposition cleans.
  • Challenge: Aggressiveness can damage fragile nanosheets; hard to achieve uniformity at <3nm scale.

2. High-purity precursors

Utilizing ultra-clean precursors in ALD, CVD and epitaxy reduces introduction of contaminants.

  • Application: Gate oxide formation, channel deposition.
  • Challenge: Purity must be maintained throughout delivery; costly to implement.

3. In-situ process monitoring

Optical, electrical and spectroscopic tools detect contamination during deposition and etch.

  • Application: Inline metrology, endpoint detection.
  • Challenge: Needs integration with high-throughput tools; data complexity increases exponentially.

4. Material stack engineering

Interface passivation, barrier layers or alternative materials can suppress defect formation.

  • Application: High-k/metal gate integration, channel interfaces.
  • Challenge: Complex material interactions can create new defect modes.

While these techniques are essential, they are often reactive—addressing defects after they’ve been introduced, rather than preventing them altogether.

The promise of ultra-high vacuum and low-temperature technologies

A more proactive approach lies in ultra-high vacuum (UHV), low-temperature processing technologies. These environments dramatically reduce the risk of contamination at the source, enabling cleaner interfaces and more controlled deposition conditions. Benefits for GAA manufacturing include:

  1. Reduced oxygen and hydrocarbon exposure: UHV minimizes ambient gas interactions, preventing native oxide growth or carbon incorporation during sensitive steps.
  2. Cleaner epitaxial growth and ALD: Low-temperature, high-vacuum deposition allows atomic-level control without activating unwanted surface reactions or diffusion.
  3. Improved interface integrity: By limiting defect formation at the gate-channel or channel-substrate interfaces, UHV processes support higher mobility and more consistent transistor behavior.
  4. Compatibility with fragile 3D structures: Lower thermal budgets reduce stress, deformation and dopant diffusion in delicate nanosheets or nanowires.

Application areas of the UHV low-temperature technologies include epitaxial nanosheet growth, high-k/metal gate integration, channel and gate oxide interface engineering and in-situ surface treatment and passivation.

Business impact: Turning purity into profit

By integrating UHV, low-temperature technologies into the GAA process flow, fabs and IDMs can realize tangible business gains:

  • Higher yields through reduced atomic-level defects.
  • Better binning due to tighter performance distributions.
  • Lower power profiles, unlocking premium mobile and data center markets.
  • Faster time-to-market by avoiding defect-related delays.
  • Longer product lifecycles due to improved reliability.

These improvements translate directly to stronger gross margins, customer satisfaction, and market differentiation—critical in an industry where a single yield point can sway billions in revenue.

Final thoughts: Clean at the core

As the semiconductor industry transitions to GAA at scale, success will increasingly hinge on our ability to manage the invisible. Atomic-level contamination, once a secondary concern, is now a primary limiter of performance and profitability.

By embracing ultra-high vacuum and low-temperature solutions like the SisuSemi one, forward-looking organizations can move beyond legacy constraints and unlock the full promise of GAA—delivering not just better chips, but better business outcomes.

Contact us to learn more