In this blog post, we’ll take a step-by-step look at the history and operating principles of transistors, the evolution of miniaturization technology, and the latest semiconductor structures and technological advancements.

The Emergence of the Transistor and the Miniaturization of Electronic Devices

The term “wafer,” which frequently appears in articles about semiconductors, refers to a disk on which numerous semiconductor chips are integrated onto a silicon substrate. Each chip contains tens of billions to as many as hundreds of billions of transistors, and the performance, size, and power efficiency of the electronic devices we use today are determined by the integration density of these tiny components.
Transistors took over the role previously played by vacuum tubes, leading to the rapid miniaturization of electronic devices and improved reliability. While vacuum tubes were large, vulnerable to impact, and required warm-up time, transistors are much smaller, highly durable, and operate stably even at low power. Thanks to these characteristics, electronic devices have become smaller and lighter since the advent of transistors, and their performance and reliability have greatly improved.
The first practical transistors were made using germanium, but they had limitations such as heat sensitivity and poor stability. Subsequently, silicon—which offers superior thermal stability and advantages in the manufacturing process—became the primary material, laying the foundation for the modern semiconductor industry. The invention of the transistor is regarded as one of the most important innovations in the history of electronics, and the researchers who contributed to its development were awarded the 1956 Nobel Prize in Physics.
The miniaturization of transistors led to the development of integrated circuits (ICs), which are mass-produced in high density on wafers. The technology for integrating more transistors into the same area is still considered a core competitive advantage of the semiconductor industry today.
The phenomenon of the number of transistors integrated onto a chip continuously increasing has commonly been explained by “Moore’s Law.” Although the rate of increase has not been as consistent as in the past, the semiconductor industry continues to achieve higher integration densities and performance improvements through new processes and structural innovations.

Basic Structure and Operating Principles of Transistors

To understand transistors, one must first understand the two types of semiconductors: n-type and p-type. An n-type semiconductor contains many free electrons, allowing electrons to move easily, while a p-type semiconductor contains many holes—vacancies left by electrons that have moved away—which play a crucial role in current conduction.
Combining these two types of semiconductors creates structures such as pnp or npn junctions, and their electrical characteristics vary depending on the movement of electrons and changes in voltage. In the region where they meet, an electric field is formed due to the movement of charges, and the flow of current is controlled by the voltage applied from the outside.
Taking a simple bipolar junction transistor (BJT) as an example, its operating mode is determined by the voltage applied between its three terminals: the emitter, base, and collector. Applying a forward bias between the base and emitter causes current to flow, whereas applying a reverse bias significantly suppresses the current flow.
These operational characteristics give rise to the two key functions of a transistor. The first is the switching function. By applying a small signal to the base, a large current at the collector can be controlled; computers use this to process digital signals consisting of 0s and 1s. The second is the amplification function. Because it can amplify a small input signal into a larger output signal, it plays a crucial role in audio equipment, communication devices, and various electronic circuits. These two functions form the fundamental principles of modern computers and information processing systems.

From 2D to 3D: Tri-Gate and the Latest Semiconductor Technology

Traditional transistors for integrated circuits have long been manufactured using a planar (2D) structure. While miniaturization was pursued by continuously reducing the width and length of the channel (the path through which current flows), various physical limitations—such as increased leakage current and degraded performance—began to emerge as the manufacturing process reached the nanometer scale.
To address these issues, Intel commercialized the Tri-Gate transistor, a three-dimensional structure in which the channel is stacked vertically and the gate wraps around three sides. This concept subsequently evolved into FinFET technology across the industry and is currently used in most high-performance processors. Controlling the channel from multiple sides allows for the implementation of smaller devices within the same area, reduces leakage current, and improves both performance and power efficiency.
Recently, as semiconductor miniaturization has progressed further, GAA (Gate-All-Around) transistors—the next-generation architecture following FinFET—are being commercialized in earnest. Because the gate surrounds the channel on all sides, GAA offers superior current control capabilities and plays a crucial role in addressing various challenges associated with advanced process nodes. Currently, major semiconductor companies are expanding the application of GAA-based processes as a core technology for the next generation.
Electron microscope images of the transistor structure reveal that the three-dimensional design is engineered to control the channel more effectively than conventional planar structures. These structural changes are serving as a crucial foundation for semiconductor development, enabling higher integration while simultaneously delivering high performance and low power consumption.
Although the increase in integration predicted by Moore’s Law is no longer proceeding at the same pace as in the past, the semiconductor industry continues to improve performance through new architectures and advanced manufacturing processes. New structures such as 3D transistors and GAA go beyond simply increasing chip speed; they are becoming the core foundation enabling next-generation information technologies such as artificial intelligence, high-performance computing, autonomous driving, and mobile devices. Structural innovations in transistors will continue in the future, leading to the development of smaller, faster, and more energy-efficient electronic devices.