Robert W. Bower

Last updated
Robert W. Bower
Born (1936-06-12) June 12, 1936 (age 87)
Santa Monica, California
Died (2024-01-26) January 26, 2024 (age 6 days)
Haiku, HI
Alma mater University of California at Berkeley
The California Institute of Technology
Known forSelf-aligned-gate MOSFET
Awards National Inventors Hall of Fame, 1997
National Academy of Engineering, 1999
Scientific career
Fields Applied Physics

Robert W. Bower (June 12, 1936) is an American applied physicist. Immediately after receiving his Ph.D. from The California Institute of Technology in 1973, he worked for over 25 years in many different professions: engineer, scientist, professor at University of California, Davis, and as president and CEO of Device Concept Inc. He also served as the president of Integrated Vertical Modules, which focused on three-dimensional, high-density structures. His most notable contribution, however, is his field-effect device with insulated gates—also known as a self-aligned-gate MOSFET (metal–oxide–semiconductor field-effect transistor), or SAGFET. Bower patented this design in 1969 while working at the Hughes Research Laboratories in Malibu, California.

Contents

He has also published over 80 journals and articles, patented over 28 inventions, and authored chapters in 3 different books.

Biography

Life and education

Bower was born in Santa Monica, California, in 1936. He remained in California throughout his life, except for 1954–1958 when he enlisted in the Air Force. After his service with the Air Force, he enrolled in UC Berkeley, and in 1962, earned his A.B. in physics while working at the Lawrence Radiation Laboratory. One year later, he earned his M.S. in electrical engineering from Caltech. In 1965, he worked in Malibu, California with Hughes Research Laboratories, which specializes in aerospace and defense operations. He later returned to Caltech and received his Ph.D. in Applied Physics in 1973. Currently, Dr. Bower is Professor Emeritus at the University of California, Davis, where he has been teaching for over 14 years.

Primary accomplishments

At the Hughes Research Laboratories in the late 1960s, Bower strove to find the ideal element to integrate in all circuits. In 1920, Lilienfeld conceived of the basic design for this idea but had no platform to build or test his device. In the late 1950s, McCaldin and Hornoi devised of the silicon planar process and Kilby and Noyce established an Integrated circuit (IC) that could serve as a basic platform for Lilienfeld's design. In 1963, Steven Hofstein and Frederic Heiman compiled the ideas from all previous scientists and were able to describe the fundamental nature of the MOSFET on a silicon planar process platform; however, they lacked one key asset that would power the MOSFET. In 1965, Bower conceived of the self-aligned-gate ion-implanted MOSFET which was the key to advances in integrated circuits. [1]

Self-aligned-gate ion-implanted MOSFET

The MOSFET (metal–oxide–semiconductor field-effect transistor) is a device that amplifies or switches electronic signals. However, without the self-aligned gate, the MOSFET lacked a proper source to improve the accuracy of the entire fabrication process. Dr. Bower therefore established a small self-aligned gate designed to arrange a highly doped gate as a mask of the source and drain around it. His patent (U.S. 3,472,712) was filed on October 27, 1966 and issued to him on October 14, 1969.

Patent controversy

Bower's invention underwent much controversy when Kerwin, Klein, and Sarace argued that they were the actual inventors of the self-aligned gate transistors. In 1966, Bower and Dill presented the first publication the self-aligned gate transistor at the International Electron Device Meeting in Washington, D.C. That IEDM publication described the self-aligned gate transistor fabricated with both metal and polysilicon as the gate material and using both ion implantation and diffusion to form the source and drains. This was presentation 16.6 of this IEDM meeting. To Bower and to the attorneys who litigated the Bower U.S. 3,472,712 patent it was determined in the courts that his patent covered the general principal of using a gate as mask for both metal and polysilicon gates using ion implantation to establish the source and drain regions. Bower does not acknowledge the statement "Although Bower believed he was first in using aluminum as the gate and later developed the device using polysilicon as the gate, he was unable to prove it to the courts and the patent was awarded to Kerwin, Klein, and Sarace (U.S. 3,475,234)" is true. Actually it was the Hans G. Dill patent U.S. 3,544,3999, filed on October 26, 1966, that described the formation of the polysilicon gate self-aligned gate FET using diffusion of the source and drain that was disputed by the Kerwin et al. patent, not the Bower patent. It was also determined in a number of court cases that the vast majority of self-aligned gate FETs were made using ion implantation rather than diffusion to introduce the dopants into the source-drain regions. Bower conferred with the attorneys who litigated these cases and they confirmed that the statement "The US patent system grants the patent to the first developer of the invention, not the first one to be issued a patent." is not a valid statement of patent law.

Other works

Aside from his large contributions in the advancement of MOSFET, Bower has published over 80 journals and articles, patented over 28 inventions, and authored chapters in 3 different books. He has recently been working with Integrate Vertical Modules to focus on three-dimensional, high-density solid structures.

Recent patents

Awards and recognition

Bower was recognized with many awards. Most notably was his induction into the National Inventors Hall of Fame in 1997 for his invention of the self-aligned gate ion implanted MOSFET. In 1999, he was elected as a member of the National Academy of Engineering, one of the highest professional distinctions granted to an engineer. Other awards granted include the Distinguished Senior Fellow Award, Alexander von Humbold Research Award, Ronald H. Brown American Innovator Awards, and Distinguished Alumni Award. These awards were granted for his contributions as an alumnus and his accomplishments as an inventor.

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An integrated circuit, also known as a microchip or IC, is a small electronic device made up of multiple interconnected electronic components such as transistors, resistors, and capacitors. These components are etched onto a small piece of semiconductor material, usually silicon. Integrated circuits are used in a wide range of electronic devices, including computers, smartphones, and televisions, to perform various functions such as processing and storing information. They have greatly impacted the field of electronics by enabling device miniaturization and enhanced functionality.

<span class="mw-page-title-main">Transistor</span> Solid-state electrically operated switch also used as an amplifier

A transistor is a semiconductor device used to amplify or switch electrical signals and power. It is one of the basic building blocks of modern electronics. It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more in miniature form are found embedded in integrated circuits. Because transistors are the key active components in practically all modern electronics, many people consider them one of the 20th century's greatest inventions.

<span class="mw-page-title-main">Semiconductor device</span> Electronic component that exploits the electronic properties of semiconductor materials

A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state, rather than as free electrons across a vacuum or as free electrons and ions through an ionized gas.

<span class="mw-page-title-main">MOSFET</span> Type of field-effect transistor

The metal–oxide–semiconductor field-effect transistor is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. The term metal–insulator–semiconductor field-effect transistor (MISFET) is almost synonymous with MOSFET. Another near-synonym is insulated-gate field-effect transistor (IGFET).

<span class="mw-page-title-main">CMOS</span> Technology for constructing integrated circuits

Complementary metal–oxide–semiconductor is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. CMOS technology is used for constructing integrated circuit (IC) chips, including microprocessors, microcontrollers, memory chips, and other digital logic circuits. CMOS technology is also used for analog circuits such as image sensors, data converters, RF circuits, and highly integrated transceivers for many types of communication.

<span class="mw-page-title-main">Insulated-gate bipolar transistor</span> Type of solid state switch

An insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device primarily forming an electronic switch. It was developed to combine high efficiency with fast switching. It consists of four alternating layers (P–N–P–N) that are controlled by a metal–oxide–semiconductor (MOS) gate structure.

Frank Marion Wanlass was an American electrical engineer. He is best known for inventing CMOS logic with Chih-Tang Sah in 1963. CMOS has since become the standard semiconductor device fabrication process for MOSFETs.

<span class="mw-page-title-main">Fin field-effect transistor</span> Type of non-planar transistor

A fin field-effect transistor (FinFET) is a multigate device, a MOSFET built on a substrate where the gate is placed on two, three, or four sides of the channel or wrapped around the channel, forming a double or even multi gate structure. These devices have been given the generic name "FinFETs" because the source/drain region forms fins on the silicon surface. The FinFET devices have significantly faster switching times and higher current density than planar CMOS technology.

<span class="mw-page-title-main">Power MOSFET</span> MOSFET that can handle significant power levels

A power MOSFET is a specific type of metal–oxide–semiconductor field-effect transistor (MOSFET) designed to handle significant power levels. Compared to the other power semiconductor devices, such as an insulated-gate bipolar transistor (IGBT) or a thyristor, its main advantages are high switching speed and good efficiency at low voltages. It shares with the IGBT an isolated gate that makes it easy to drive. They can be subject to low gain, sometimes to a degree that the gate voltage needs to be higher than the voltage under control.

Charge trap flash (CTF) is a semiconductor memory technology used in creating non-volatile NOR and NAND flash memory. It is a type of floating-gate MOSFET memory technology, but differs from the conventional floating-gate technology in that it uses a silicon nitride film to store electrons rather than the doped polycrystalline silicon typical of a floating-gate structure. This approach allows memory manufacturers to reduce manufacturing costs five ways:

  1. Fewer process steps are required to form a charge storage node
  2. Smaller process geometries can be used
  3. Multiple bits can be stored on a single flash memory cell
  4. Improved reliability
  5. Higher yield since the charge trap is less susceptible to point defects in the tunnel oxide layer

SONOS, short for "silicon–oxide–nitride–oxide–silicon", more precisely, "polycrystalline silicon"—"silicon dioxide"—"silicon nitride"—"silicon dioxide"—"silicon", is a cross sectional structure of MOSFET (metal–oxide–semiconductor field-effect transistor), realized by P.C.Y. Chen of Fairchild Camera and Instrument in 1977. This structure is often used for non-volatile memories, such as EEPROM and flash memories. It is sometimes used for TFT LCD displays. It is one of CTF (charge trap flash) variants. It is distinguished from traditional non-volatile memory structures by the use of silicon nitride (Si3N4 or Si9N10) instead of "polysilicon-based FG (floating-gate)" for the charge storage material. A further variant is "SHINOS" ("silicon"—"hi-k"—"nitride"—"oxide"—"silicon"), which is substituted top oxide layer with high-κ material. Another advanced variant is "MONOS" ("metal–oxide–nitride–oxide–silicon"). Companies offering SONOS-based products include Cypress Semiconductor, Macronix, Toshiba, United Microelectronics Corporation and Floadia.

In semiconductor electronics fabrication technology, a self-aligned gate is a transistor manufacturing approach whereby the gate electrode of a MOSFET is used as a mask for the doping of the source and drain regions. This technique ensures that the gate is naturally and precisely aligned to the edges of the source and drain.

<span class="mw-page-title-main">Multigate device</span> MOS field-effect transistor with more than one gate

A multigate device, multi-gate MOSFET or multi-gate field-effect transistor (MuGFET) refers to a metal–oxide–semiconductor field-effect transistor (MOSFET) that has more than one gate on a single transistor. The multiple gates may be controlled by a single gate electrode, wherein the multiple gate surfaces act electrically as a single gate, or by independent gate electrodes. A multigate device employing independent gate electrodes is sometimes called a multiple-independent-gate field-effect transistor (MIGFET). The most widely used multi-gate devices are the FinFET and the GAAFET, which are non-planar transistors, or 3D transistors.

<span class="mw-page-title-main">Metal gate</span>

A metal gate, in the context of a lateral metal–oxide–semiconductor (MOS) stack, is the gate electrode separated by an oxide from the transistor's channel – the gate material is made from a metal. In most MOS transistors since about the mid 1970s, the "M" for metal has been replaced by a non-metal gate material.

<span class="mw-page-title-main">PMOS logic</span> Family of digital circuits

PMOS or pMOS logic is a family of digital circuits based on p-channel, enhancement mode metal–oxide–semiconductor field-effect transistors (MOSFETs). In the late 1960s and early 1970s, PMOS logic was the dominant semiconductor technology for large-scale integrated circuits before being superseded by NMOS and CMOS devices.

A transistor is a semiconductor device with at least three terminals for connection to an electric circuit. In the common case, the third terminal controls the flow of current between the other two terminals. This can be used for amplification, as in the case of a radio receiver, or for rapid switching, as in the case of digital circuits. The transistor replaced the vacuum-tube triode, also called a (thermionic) valve, which was much larger in size and used significantly more power to operate. The first transistor was successfully demonstrated on December 23, 1947, at Bell Laboratories in Murray Hill, New Jersey. Bell Labs was the research arm of American Telephone and Telegraph (AT&T). The three individuals credited with the invention of the transistor were William Shockley, John Bardeen and Walter Brattain. The introduction of the transistor is often considered one of the most important inventions in history.

<span class="mw-page-title-main">Fujio Masuoka</span> Japanese engineer (born 1943)

Fujio Masuoka is a Japanese engineer, who has worked for Toshiba and Tohoku University, and is currently chief technical officer (CTO) of Unisantis Electronics. He is best known as the inventor of flash memory, including the development of both the NOR flash and NAND flash types in the 1980s. He also invented the first gate-all-around (GAA) MOSFET (GAAFET) transistor, an early non-planar 3D transistor, in 1988.

Polysilicon depletion effect is the phenomenon in which unwanted variation of threshold voltage of the MOSFET devices using polysilicon as gate material is observed, leading to unpredicted behavior of the electronic circuit. Because of this variation High-k Dielectric Metal Gates (HKMG) were introduced to solve the issue.

<span class="mw-page-title-main">Field-effect transistor</span> Type of transistor

The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. It comes in two types: junction FET (JFET) and metal-oxide-semiconductor FET (MOSFET). FETs have three terminals: source, gate, and drain. FETs control the flow of current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source.

References

  1. "Robert Bower – Field-Effect Device with Insulated Gate; Self Aligned Gate MOSFET". Hall of Fame / Inventor Profile. Archived from the original on 2008-12-27.