【Semiconductor】🧭 07. The Essence of the Post-CFET Era

— A Design World Where SystemDK Is the Premise

topics: [“Semiconductor”, “CFET”, “Chiplet”, “SystemDK”, “Design Methodology”]

🧭 Introduction: “What Comes After CFET” Is Not a Device

In discussions after CFET,
the following question is often raised:

“What is the next transistor structure after CFET?”

However, as organized in the previous chapter,
the realistic answer toward 2040 is not
a continuous invention of new device structures.

Instead, the core question shifts to:

Not how to fabricate devices,
but how far a design can be made to work as a system

This article organizes:

The SystemDK-oriented design methodology that becomes inevitable in the Post-CFET era
The chiplet-centric worldview that underpins it

🧱 After CFET, Monolithic Integration Hits a Structural Wall

CFET represents the extreme convergence of:

Electric-field control (GAA)
Area efficiency (vertical stacking)
Power architecture (BPR)

As a consequence, the following constraints become structurally unavoidable:

Blocked thermal dissipation paths
Asymmetric process-temperature constraints
Sharp reduction in yield and design freedom
Exploding interconnect and verification costs

This is not because the technology is immature, but because of:

The fundamental limit of the idea that “everything must fit inside a single chip”

In other words:

After CFET, the assumption of doing everything within one chip collapses

🧩 Chiplets Are the Answer — and They Are Not an Escape

The realistic response to these constraints is:

Chiplets
3D integration
Heterogeneous integration

Crucially, chiplets are not:

A fallback because scaling failed
but
A necessary evolution to preserve design feasibility

Through chiplet-based architectures, we gain:

Thermal source separation
Asynchronous process-node optimization
Function-level specialization
Improved reuse and scalability

At the same time, design problems fundamentally change into a world where:

“What is placed where” determines performance and reliability

Handling this exploding design-space complexity requires
a SystemDK-style framework.

(See details →
https://samizo-aitl.github.io/Edusemi-v4x/f_chapter2a_systemdk/)

🔌 Why “Circuit Design Alone” Is No Longer Sufficient

Traditional design flows centered on:

Devices
Circuits
Interconnects
Timing

In the chiplet era, however, the following become primary design variables from the start:

Thermal coupling
Power-domain separation and IR drop
Mechanical stress and strain
Noise (SI / PI / EMI)
Package structure

These are no longer:

Items to be “evaluated later”
but
Constraints that must be embedded at the earliest design stage

This is where the SystemDK (System Design Kit) mindset becomes indispensable.
(See the dedicated SystemDK chapter →
https://samizo-aitl.github.io/Edusemi-v4x/f_chapter2a_systemdk/)

🗺 SystemDK Is a “Map for Design”

SystemDK is not merely a collection of tools.

It is a framework that treats:

Devices
Circuits
Packaging
Thermal, stress, power, and noise effects

within a single, unified design space.

SystemDK assumes a design stance of:

Not “analyzing after the fact”
But selecting configurations that do not break from the beginning

In the Post-CFET era:

Designs without SystemDK collapse at the initial stage

This is not an exaggeration.

👤 The Role Required of Designers in the Post-CFET Era

What designers are expected to provide is no longer:

Finer transistor-level expertise
but rather
The ability to aggregate constraints and make decisions

Specifically, value lies in being able to judge early:

“This structure will fail thermally”
“This placement will collapse the power network”
“This integration will not yield”

Such judgments must be made at the earliest design phase.

This role is no longer that of:

A circuit designer,
nor a device engineer

but that of a System designer.

📝 Summary: The Protagonist of the Post-CFET Era Is Design Philosophy

After CFET, monolithic on-chip integration reaches its limit
The solution lies in chiplets and heterogeneous integration
But this does not reduce design difficulty
SystemDK-style design is mandatory
The essence of Post-CFET is not “structure,” but design methodology

The Post-CFET era is:

Not a time to wait for the next device,
but a time to be tested on whether design can keep up

This question will continue to confront
design, manufacturing, and education alike.

This article is organized based on the following educational materials and design concepts:

Edusemi-v4x: Structural evolution up to CFET
https://samizo-aitl.github.io/Edusemi-v4x/f_chapter1_finfet_gaa/
Special Chapter: Thermal, Stress, and Noise Constraints in SystemDK
https://samizo-aitl.github.io/Edusemi-v4x/f_chapter2a_systemdk/

All of these are grounded in the same question:

Not “can it be built,”
but “can it be made to truly work.”