Correlation between nanometers and GHz speeds in modern silicon chips and moore's law

The correlation between nanometer (nm) size and GHz speed in modern chips is no longer a simple, direct relationship, as it was in the early days of Moore's Law.

Below I explain the relationship, why the correlation has weakened, and how this all relates to Moore's Law.

1. The Original Correlation: Moore's Law

In the past (until around 2005), there was a strong, almost direct correlation between shrinking the nanometer size and increasing the clock speed:

Parameter	Impact of Shrinking
Nanometer Size (nm)	Decreases. (This is the geometric scaling).
Transistor Density	Increases. (More transistors fit on the same chip, the essence of Moore's Law).
Clock Speed (GHz)	Increases. (Transistors are closer together, shortening the electron travel distance, allowing the frequency to increase).
Power Consumption	Decreases. (The smaller transistors required less energy to switch).

In short: Smaller transistors were faster and consumed less power. This was the basis for the first four decades of Moore's Law, which stated that the number of transistors doubles every two years.

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2. The Weakened Correlation: Thermal Walls

Around the mid-2000s, this direct correlation largely ceased. This was caused by the so-called Power Wall and Thermal Wall.

The Problem: Leakage Current

As transistors shrank below approximately 65 nm, the insulating layers (gate oxides) became so thin that electrons began to "leak" (quantum tunneling).

1. Higher Clock Speed $\to$ More Heat: To further increase the clock speed (GHz), the voltage on the chip had to be increased.

2. Leakage Current + Higher Voltage $\to$ Exponential Heat: The combination of existing leakage current and higher voltage led to an uncontrollable rise in power consumption and heat generation. The chips became too hot to cool efficiently.

Since this point, the clock speed of high-end processors has largely stalled around $3.0$ to $5.0\text{GHz}$.

The Current Correlation (Post-2010)

Today, nanometers and GHz speeds relate as follows:

Parameter	Relationship to Clock Speed (GHz)
Nanometer Size (nm)	Indirect. The nm size primarily determines energy efficiency and transistor density (Moore's Law).
Clock Speed (GHz)	Rarely directly affected. A smaller process (e.g., 5 nm to 3 nm) mainly improves efficiency, allowing the chip to sustain a higher frequency without overheating, but the focus is on cores and efficiency. TSMC and Samsung are currently manufacturing 2nm chips. Intel will also have 1.8nm chips ready by early 2026 and is working on a 1.4nm chip. According to Intel, the 18A (1.8nm) is said to be 25% faster than the 3nm chips.

Conclusion: Smaller nanometers now primarily result in more energy-efficient and denser chips, not necessarily a higher top speed in GHz.

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3. Moore's Law and the Shift in Focus

Moore's Law (the doubling of the number of transistors) is not yet dead, but the way we achieve performance gains has shifted:

A. From Clock Speed to Parallelism

Because clock speed (GHz) stalled, chip manufacturers had to find another way to increase performance. The focus has shifted from:

$$\text{Performance}\approx \text{Speed}\times \text{Number of Transistors}$$

To:

$$\text{Performance}\approx \text{Number of Cores}\times \text{Efficiency per Core}$$

This explains why modern CPUs now have 8, 16, or even 64 cores, instead of a single core running at 10 GHz.

B. The Meaning of 'Nanometer'

Furthermore, the term "nanometer" on modern chips (e.g., 3 nm or 5 nm) is no longer a strict physical measurement of a transistor component's dimension (like the gate length).

• It is now more of a commercial designation or a generation name representing a certain level of technological refinement and transistor density.

• The actual dimensions can vary between manufacturers, but the smaller "nm" generation always means higher transistor density and better energy efficiency.

In summary, the nanometer size still affects Moore's Law (density), but it has lost its direct influence on the GHz clock speed due to fundamental thermal limitations.