Inside the Intel Ivy Bridge Microarchitecture

The 22-nm Manufacturing Process

While CPUs based on the Sandy Bridge microarchitecture are manufactured using a 32-nm process, processors based on the Ivy Bridge microarchitecture will use a new 22-nm process. (Read our “How Chips are Manufactured” tutorial for a better understanding of the subject.) However, instead of simply shrinking down the size of the parts inside the chip (namely, the transistors), the new Intel 22-nm manufacturing process uses a completely new approach using three-dimensional transistors.

In Figure 1, you can see how a traditional field-effect transistor (FET) works. This is the kind of transistor traditionally used inside CPUs. It is comprised of a channel, where current flows from one of its ends (called a “source”) to the other (called a “drain”). A third terminal, called a “gate,” controls the amount of current that flows through the channel. In CPUs, transistors work as switches, allowing current to flow when no current is applied to their gate, and blocking current from flowing when current is applied to their gate.

Figure 1: How traditional transistors work

In the tri-dimensional approach, the channel was moved sideways, as you can see in Figure 2. This way, the channel is now thinner but taller. This physical appearance of the channel is called the “fin.” Several fins can now be added to increase the amount of current supported by the transistor. See Figure 3.

Figure 2: The 3D transistor

Figure 3: Multiple fins for higher current

This design also allows the transistor to spend less power. According to Intel, this new approach allows a 37% performance increase (i.e., faster switching speed) when using low voltage (0.7 V) and a 50% power reduction.