Chih-Tang Sah's Ashes Return to Fujian, Bringing Home a Pioneer of Modern Chips

A homecoming for the scientist behind a defining chip idea

The ashes of Chih-Tang Sah, who helped introduce the semiconductor technology used in about 99 percent of integrated circuits by 2011, have been brought from the United States to Fujian in southeastern China for burial. Born in Beijing in 1932 and raised in the distinguished Fuzhou Sah family, he died on July 5 at the age of 92.

Sah was an honorary professor at Xiamen University, which marked his death and his long connection to the academic community. His return to his ancestral province brings together two parts of his life: his roots in China and a scientific career developed through research, industry and teaching in the United States.

At Fairchild Semiconductor in 1963, Sah and colleague Frank Wanlass jointly proposed complementary metal oxide semiconductor logic, known as CMOS. Their idea paired two different types of tiny electronic switches so that a circuit could perform calculations while using very little power when its state stayed unchanged.

That approach helped make increasingly complex chips practical. Its reach extends from phones and computers to aircraft electronics, spacecraft controls and the accelerators used to train artificial intelligence. The figure of about 99 percent comes from High-Frequency Integrated Circuits, a book by Sorin Voinigescu of the University of Toronto, and describes the share of semiconductor integrated circuits produced with CMOS technology by 2011.

Sah's ashes have returned to Fujian for burial, but no burial date or precise location was given. His scientific legacy is already present across laboratories, classrooms and factories around the world, wherever engineers use complementary switches to build compact, efficient electronic systems.

From Beijing to American research laboratories

Sah pursued engineering in the United States, earning two bachelor's degrees at the University of Illinois before completing his master's degree and doctorate at Stanford University. His education placed him in the field of solid state electronics as silicon devices were moving from physics research into industrial production.

Solid state electronics uses the electrical properties of materials such as silicon to control current. Sah entered the industry in 1956 and soon joined Fairchild Semiconductor, where scientific understanding of those materials had to meet the practical demands of making working devices.

Fairchild played a major role in the growth of Silicon Valley. Its scientists and engineers developed processes and components that helped integrated circuits gain an early foothold. An integrated circuit brings electronic components together on a chip, allowing many operations to take place within a small space.

Sah worked across device theory, manufacturing and circuit design. That combination later shaped his teaching: understanding what a transistor should do was connected to understanding how a manufactured transistor actually behaved.

His career developed across several institutions and decades:

• 1932: Sah was born in Beijing and grew up in the Fuzhou Sah family.
• 1956: He entered the solid state electronics industry before joining Fairchild Semiconductor.
• 1962 to 1988: He served as a professor at the University of Illinois.
• 1963: He and Frank Wanlass presented the CMOS concept at Fairchild.
• After his Illinois appointment: He continued his work at the University of Florida.
• July 5: Sah died at the age of 92. His ashes were subsequently brought from the United States to Fujian for burial.

How two tiny switches changed circuit design

CMOS uses complementary pairs of metal oxide semiconductor field effect transistors, or MOSFETs. A transistor is a tiny switch that controls electrical current. In the simplest CMOS arrangement, the two switches respond in opposite ways to the same input.

The transistor described as p type conducts when the input is low, while the transistor described as n type conducts when the input is high. Working together, they can produce a reliable output while limiting the steady flow of current through the circuit.

A CMOS inverter, the simplest example, turns a low input into a high output and a high input into a low output. When the input is low, the p type transistor turns on and connects the output toward the power supply. The n type transistor is off. When the input is high, the n type transistor turns on and pulls the output toward ground, while the p type transistor is off.

For either valid, steady input, one transistor is off. That arrangement limits current flowing continuously from the power supply to ground. It also gives CMOS strong resistance to electrical noise, helping circuits maintain dependable logic states despite unwanted electrical disturbances.

Sah and Wanlass presented the principle in 1963. Its value grew as engineers sought to place more electronic functions on each chip: less power consumed while resting meant less heat, while complementary switching provided a practical foundation for increasingly dense circuits.

Why CMOS saves power, and still produces heat

A MOSFET controls current through an electric field. It has a channel in a semiconductor, with terminals called the source and drain at its ends. A gate electrode sits above the channel, separated from it by a thin insulating oxide.

A voltage applied to the gate changes the charge carriers in the channel. Once the required threshold voltage is reached, a conductive path forms and current can flow. Below that threshold, the path closes, although tiny leakage currents can remain.

CMOS logic uses this behavior to consume nearly zero static power in its steady states. Static power means the power used while a circuit holds its state rather than switching. Most of the intended power use comes as the circuit changes state, charging and discharging tiny capacitances, which act as small stores of electrical charge.

Engineers therefore distinguish between dynamic power, used during switching, and leakage power, caused by small currents that flow even when transistors are off. Leakage becomes more prominent as devices shrink. A chip performing many operations still consumes energy and produces heat, even though its basic logic is designed to avoid unnecessary current at rest.

The reduction in static power helped support longer battery life in portable devices and higher densities of components on chips. It also gave designers a way to increase circuit complexity without power consumption rising in direct proportion to every added component.

Engineers manage power through clock gating, which stops unnecessary switching in parts of a circuit, dynamic voltage scaling, which adjusts operating voltage, and careful layout. Improved transistor structures also help control current and reduce leakage as chips become smaller and more complex.

From a 1963 proposal to the dominant chip platform

RCA produced the first CMOS integrated circuits in the late 1960s, giving the technology commercial momentum after its introduction at Fairchild. By the 1980s, CMOS had overtaken other logic families, the different circuit arrangements used to carry out digital operations.

The 2011 figure cited in Voinigescu's textbook illustrates how far that adoption went: about 99 percent of semiconductor integrated circuits were produced with CMOS technology. A design principle presented in 1963 had become the manufacturing basis for almost the entire field measured by that figure.

CMOS is used in microprocessors, which execute software instructions; microcontrollers, which control functions inside equipment; static RAM, a form of electronic memory; and image sensors, which capture pictures. It also supplies the control logic used in countless other systems.

Modern manufacturing has changed the physical shape of transistors while retaining complementary logic. FinFET structures and structures whose gates surround the channel are replacing earlier planar designs. These newer arrangements improve control over the channel, reduce leakage and support further reductions in device size.

Many chips also stack components in three dimensions and use advanced packaging to connect them. Those changes concern how devices are built and assembled, while the complementary switching principle remains central to their logic.

A teaching career that carried the science further

Sah served at the University of Illinois from 1962 to 1988 and later continued his academic work at the University of Florida. Across his career, he published about 280 journal articles, mentored doctoral students and advanced the device physics underlying CMOS design and fabrication.

His work joined theory, devices and systems, earning recognition across industry and academia. At Illinois, his teaching helped students develop a rigorous understanding of silicon devices and their behavior, preparing them to design and manufacture later generations of chips.

The University of Illinois Holonyak Micro and Nanotechnology Lab places Sah alongside John Bardeen and Nick Holonyak Jr. in its account of the campus's semiconductor research heritage. The laboratory's semiconductor research history connects the transistor era with the development of modern integrated circuits.

The laboratory describes the contribution of Sah and his fellow researchers in these words:

The lab's researchers are part of a historic semiconductor legacy that began with engineering giants John Bardeen, Nick Holonyak Jr., and Chih-Tang Sah, whose groundbreaking work helped launch and advance today's information technology revolution.

That history links foundational research with work continuing in laboratories today. Sah's experience at Fairchild brought manufacturing and design concerns into the classroom, while his students and publications carried knowledge of semiconductor behavior into subsequent research and industry work.

Academic research and collaboration with industry helped CMOS grow from an idea into a nearly universal platform. Sah's contribution therefore extended beyond the original proposal to the explanations, models and training that engineers needed to use the technology effectively.

Phones, flight controls and artificial intelligence

CMOS techniques support the digital logic that executes instructions, memory arrays that store data, sensors that capture images and radio circuits that connect devices. Their everyday applications place Sah's scientific influence inside phones, on desks and throughout the equipment people depend on.

Aircraft flight computers, car control systems and spacecraft electronics also use CMOS. Designers choose it for energy efficiency, reliability and the ability to accommodate increasing numbers of components and functions.

Cloud computing and artificial intelligence draw on the same technological foundation. Nvidia's H200 accelerator, a prominent example of hardware used for artificial intelligence, is built with advanced CMOS process technology. Accelerators carry out the intensive calculations needed for tasks such as training artificial intelligence systems.

Controls on exports of such powerful chips have become a point of tension between the United States and China. The political dispute concerns access to advanced computing hardware, while the underlying technology still rests on the complementary switching principle Sah and Wanlass helped introduce.

CMOS also supports precision analog functions, which handle signals that vary continuously, rather than only digital high and low states. Its uses extend to image sensing and radio circuits for 5G, as well as research toward 6G. These applications connect the same device principles to communications, measurement and computing.

Keeping smaller devices efficient and reliable

Engineers working with CMOS must manage both power consumption and reliability. As devices shrink, tighter control of the transistor channel helps keep unwanted current down. FinFET designs and gates that surround the channel address that need while preserving the complementary operation of the circuit.

Protection structures guard chips against electrostatic discharge, the sudden release of accumulated electrical charge. Designers also account for stress that can cause metal lines inside a chip to degrade over time. Efficient logic and durable electrical connections must work together for a device to remain dependable.

New materials and device types are also being explored for analog functions, memory and neuromorphic computing. Neuromorphic computing seeks to organize computation in ways inspired by nervous systems.

A recent perspective in the journal Materials argued that CMOS remains the dominant base for digital systems, while those newer approaches are being investigated on the condition that they can fit into manufacturing compatible with CMOS. Compatibility matters because it allows new functions to connect with an established production platform.

The continued use of CMOS reflects the maturity of the technology Sah helped set in motion. Transistor shapes, materials and packaging can change while engineers retain the complementary logic that makes large collections of switches practical.

Fujian homecoming amid China's chip ambitions

Fujian is Sah's ancestral province, and the return of his ashes carries both family and scientific meaning. His life connected Beijing, American universities and industrial laboratories, while his honorary professorship at Xiamen University maintained a link with China's academic community.

China is investing heavily in semiconductor education, research and manufacturing. The concepts Sah advanced, including complementary logic and careful control of device physics, remain central to those efforts to develop chip capabilities.

Export controls, changes in supply chains and competition to produce smaller, faster and more efficient chips have placed semiconductors at the center of national strategies. Sah's career also illustrates the international reach of the scientific knowledge behind those industries.

Engineers in Beijing, Taipei, Hsinchu, Seoul, Austin and Dresden study and apply similar methods and models of transistor behavior. CMOS provides a shared technical language across those locations, even as governments and companies compete over production capacity and access to advanced technology.

Xiamen University is among the institutions remembering Sah's impact. His burial in Fujian acknowledges his personal roots, while his broader legacy continues through students, scientific papers and products built around the ideas he helped develop.

From Fairchild's laboratories to lecture halls and manufacturing clean rooms, the reach of CMOS connects Sah's early work with present computing. His ashes have returned to China; his scientific contribution remains embedded in the chips used across the world.

Key Points

• Chih-Tang Sah's ashes were brought from the United States to Fujian for burial. No burial date or precise location was given.
• Born in Beijing in 1932, Sah died on July 5 at the age of 92 and was an honorary professor at Xiamen University.
• Sah and Frank Wanlass jointly proposed CMOS at Fairchild Semiconductor in 1963.
• CMOS pairs complementary transistors to limit steady current flow, helping chips use less power while at rest.
• RCA produced the first CMOS integrated circuits in the late 1960s, and CMOS overtook other logic families by the 1980s.
• By 2011, about 99 percent of semiconductor integrated circuits used CMOS technology, according to Sorin Voinigescu's textbook.
• Sah taught at Illinois from 1962 to 1988, later worked at Florida and published about 280 journal articles.
• CMOS supports phones, aerospace controls, image sensors, communications and artificial intelligence hardware such as Nvidia's H200.
• New transistor structures and packaging retain complementary logic while addressing power, density and reliability.