Scientists at the Motorola Laboratories, which serves as the advanced research arm of the Motorola Inc., focusing on leading edge technologies for future products and product enhancements, have solved a problem that was vexing the semiconductor industry for the last thirty years. This discovery paves the way to transform the economics of the communications and semiconductor industries.

Motorola scientists have successfully combined the best properties of the workhorse silicon technology with the speed and optical capabilities of high-performance compound semiconductors that are known as the III-V materials.

The discovery opens the door to significantly less expensive optical communications, high-frequency radio devices and high-speed microprocessor-based subsystems by potentially eliminating the current cost barriers holding back many advanced applications.

The greatest beneficiaries are the consumers who should be able to get smarter electronic products that cost less, perform better and have exciting new features. It is expected that the new technology will change the economics and accelerate the development of new applications, such as broadband "fibre" cable to the home, streaming video to cell phones and automotive collision avoidance systems.

According to scientists at the Labs, other potential markets include data storage, lasers for such consumer products as DVD players, medical equipment, radar, automotive electronics, lighting, and photovoltaics. Until now, there has been no way to combine light-emitting semiconductors with silicon integrated circuits on a single chip, and the need to use discrete components has compromised the cost, size, speed and efficiency of high-speed communications equipment and devices.

Motorola's announcement specifically impacts the semiconductor industry by:

• increasing substrate size, reducing substrate cost and processing costs for III-V manufacturing
• integrating the superior electrical and optical performance of III-V semiconductors with mature silicon technology to create a new industry based on integrated semiconductor circuits
• extending the life of silicon and existing capital investments
• improving cost effectiveness for higher performance applications such as optical communications Enabling larger scales of integration

Terming this as one of the most significant achievements of recent years, Dennis Robertson, senior vice president and chief technology officer of Motorola said that, when fully commercialised, this discovery would transform the industry in a way that is similar to the transition from discrete semiconductors to integrated circuits.

Several industry experts have stated that this discovery could well be the turning point for the semiconductor industry.

The Technology

Until now it has been virtually impossible to grow semiconductor materials on a silicon substrate. The discovery by Motorola enables very thin layers of so-called III-V semiconductor materials (which include gallium arsenide, indium phosphide, gallium nitride and other high performance / light-emitting compounds) to be grown on a silicon substrate.

Previous industry attempts to combine the underlying crystalline structures of silicon and
the various III-V compounds have failed since the material mis-match always resulted in dislocations or "cracks" in the material. Motorola scientists have solved the key to the problem by introducing an intermediate layer of material between the silicon and the III-V material. The solution was found in discovering exactly the right "recipe" for a material that would easily bond with both silicon and other compounds, reducing the strain between the two target materials in the process.

Motorola Labs' scientist, Dr. Jamal Ramdani, originally developed the idea. Developing and proving the exact recipe and process grew out of work done by a broad team of scientists and engineers, alongwith Dr. Ravi Droopad, principal staff scientist. Motorola Labs is now working on developing the optimum intermediate layer for indium phosphide and other materials. 

Motorola has selected a dedicated team to commercialise the discovery, under the leadership of Padmasree Warrier, corporate vice president, who has worked in all aspects of the semiconductor segment, including device technology, research and development, process engineering, manufacturing and pilot line operations.

Changing the Economics of Optical Communications

Until now, the industry has been dependent on costly gallium arsenide (GaAs) and indium phosphide (InP) wafers for optical and high performance applications. Because of their brittle nature, no one has previously been able to create commercial GaAs wafers larger than 6 inches or InP wafers larger than 4 inches. Scientists have also been unable to combine light-emitting semiconductors with silicon integrated circuits on a single chip.

According to Robert Merritt, vice president of Semico Research Corporation, with more than 90 percent of the existing fiber optic cable still unused and underutilized, the new technology could be the switch that eventually turns on those communications channels.

Another industry first

Motorola Labs scored another first when scientists at the Labs created the world's first 8" GaAs on silicon wafer and worked with epitaxial wafer manufacturer IQE to create the world's first 12-inch GaAs on silicon wafers and a variety of other wafer sizes. Motorola then made working power amplifiers from GaAs on silicon wafers and successfully completed numerous wireless calls using those devices in several phones over the past few months. In addition, a light-emitting device was created to demonstrate the optical characteristics.

According to Dr. Jim Prendergast, vice president and director, Physical Sciences Research Lab at Motorola, this is just the first step and has created a baseline
technology for extending our research to other materials systems. He states that the next goal is to complete the task of growing indium phosphide on silicon. This technology should support chip clock speeds of more than 70GHz and long-wavelength lasers that are critical to fiber-optic communications.