Rubicon Technology, Crystal Cleear

Manufacturing in Action, Source : The Manufacturer US

Rubicon Technology is growing a bright future. Jennifer Monroe sheds light on its process.

Imagine never changing another light bulb in your home, car, or office. Never again being subjected to the buzzing of a street lamp or the flickering of a failing fluorescent.

This isn’t the work of science fiction, it is the work of a blue Light Emitting Diode (LED), which, when combined with red and green LEDs, produces solid white light. First developed in the mid-1990s, blue LEDs are the next wave in illumination technology.

“It is a re-invention of the light bulb,” said Chris Moffitt, president of Rubicon Technology. Chicago-based Rubicon is a leading manufacturer of sapphire substrates that grow the other materials used in making blue LEDs. In fact, Rubicon completely changed its focus and direction in 2000 to become a part of the burgeoning LED industry.

Established in 1995 with just two employees, Rubicon Technology started as a dealer of sapphire and other high-density single crystal products. At that time, Rubicon imported its crystals primarily from Russia. As demand for the blue LED increased, Rubicon’s mission changed. The company became not only a distributor of crystals but also a grower, fabricator, and polisher of sapphire substrates.

Instead of adopting the processes used by its competitors, Rubicon decided to capitalize on its contacts in Russia. Familiar with the quality of Russian technology, the company imported Kryopoulous processes and technology to grow quality, large-diameter, high-density single crystal sapphire. “No one knew about this technology because it was hidden in Russia,” Moffitt said. With significant changes in both the process and physical components of the furnaces, Rubicon has designated the process as KYR-Plus. “We can grow crystals at a lower cost and with higher quality than our competition,” he said.

Rubicon set its sights on becoming a vertically integrated manufacturer of sapphire substrates and other forms. By the end of 2000, its manufacturing facilities in Chicago were brought on-line with researchers and furnaces imported from Russia. In May 2001, fabrication capacity increased, and Rubicon was well on its way to achieving its number one goal—becoming the industry leader in the growth and fabrication of advanced technology crystal materials.

Today Rubicon has more than 35,000 square feet dedicated to its manufacturing processes at its corporate campus in Bannockburn, Ill. The site includes a technology development center, an engineering fabrication site, and an Epi-Ready polishing facility.

The technology development center was built in 1999 to house the first phase of crystal growth, furnaces, and infrastructure. Inside the center, Rubicon scientists develop new sapphire growth and fabricating processes as well as new single crystal product lines such as rutile, langasite, and lithium niobate. The technology development center also houses Rubicon’s crystal growth operations. Currently, Rubicon grows C-, A-, and R-plane crystal orientations. Products range from six to 12 inches in diameter, with a 20-inch diameter product under development.

In manufacturing industrial sapphires, Rubicon simulates and accelerates the earth’s natural processes while producing a superior product. Most people are familiar with the basic crystal growing method from their elementary school science classes or from making rock candy. “It’s pretty much the same process,” Moffitt explained.

Raw material is placed in a crucible and heated to a molten state at temperatures in excess of 2000°C Centigrade. Rubicon runs more than 20 furnaces, each six feet by six feet by eight feet high. Prior to the furnace cooling, the top of the molten raw material is seeded with another crystal. This is then allowed to cool over a number of days.

What is the difference between an industrial sapphire and one created naturally? Two things: quality and color. “An industrial sapphire is perfect,” Moffitt said. “Mother Nature’s have faults, which accounts for the blue color. Oxygen and titanium get trapped in the crystal in the natural process. A pure sapphire is more clear than glass.”

From the furnace, the sapphire moves to the fabrication and quality facility. This building houses full-range, state-of-the-art fabrication equipment and technology, which includes equipment to core drill, slice, grind, and polish high-density crystals and materials such as sapphire. Rubicon’s crystal fabrication runs a 24-7 schedule and uses high-precision X-ray goniometers for precise orientation. Annealing is conducted in various atmospheres, including vacuum and ultrasonic and chemical cleaning devices are used to ensure optimal cleanliness of finished products.

First, the sapphire is cored and then moved into the grinding and slicing processes. Rubicon’s capabilities include double-side grinding and lapping, OD, and ID and edge grinding. The slicing machines cut the sapphire into wafers over a period of several hours. Since sapphire is the next hardest material to diamond, all of the cutting equipment must be either diamond tipped or impregnated. “It requires much tuning of feeds and speeds,” said Joseph Cox, VP of manufacturing. “Nothing cuts like sapphire cuts.”

The wafers are polished to less than five microns of flatness and then sold to customers. Rubicon produces nearly 100 skews, with 20 to 50 in the LED arena and others in emerging markets. The entire process, from growth to substrate, spans three to four weeks.

As with any manufacturing process, quality is vital; but it is even more so when working with sapphire. “Quality is an issue because you are growing a sapphire, and it can have a mind of its own,” Cox explained. “You have to be able to grow it perfectly with no defects.”

Rubicon’s raw material is “five nines” pure: 99.999%. Even so, trouble can occur during growth. A sapphire can develop grain boundary or dislocation if the crystal doesn’t grow in perfect symmetry; it also can develop bubbles in the growth process. “It’s very hard, if not impossible, to see specific faults with the naked eye,” Cox noted.

To ensure a perfect product, fabrication occurs in class 100 through 10,000 clean rooms. QA is done at a dozen steps in the manufacturing process, thousands of times a day, using a range of equipment including goniometers, spectrophotometers, atomic force microscopes, electron microscopes, chemical analysis, and polarized optical microscopy. The flawed sapphire is recycled, crushed, and re-used as raw material, but only if it is free from contamination.

Since its shift to sapphire manufacturing, Rubicon has developed a diversified US and Pacific Rim customer base in four markets: opto-electronics, optical and laser, semiconductor fabrication, and telecommunication.

The classic market for industrial sapphire is optical and laser. Rubicon’s sapphire windows, viewports, and other forms are used to build encasements for infrared and laser scanning and guidance technologies. Applications range from windows, lenses, tubes, rods, boules, rodstock, blanks, and military and space optical applications. In these applications, optical transparency is combined with physical strength and resistance to impact, abrasion, heat, and chemicals. Rubicon’s capability to produce very large windows of high-optical quality and strength expands the range of applications available.

“Grocery store scanners use these windows,” Moffitt said. The windows encase and protect the laser scanning device which reads the bar codes. “Those have been around for decades.”

In the semiconductor market, sapphire’s strength allows it to replace quartz and ceramic in areas requiring high resistance to abrasion, chemical erosion, and heat, as well as superior mechanical strength. Rubicon’s large-diameter sapphire wafer carriers, shower heads, tubes, and other forms replace or augment quartz and ceramic in semiconductor fabrication equipment. Sapphire products provide higher productivity and lower maintenance costs for semiconductor customers.

For telecommunications, sapphires are used in smaller, faster, and more portable devices.

Rubicon’s large-diameter sapphire substrates are used in silicon-on-sapphire applications for cellular and fiber optic products for this market. New materials such as rutile, langasite, and lithium niobate are under development for use in other products.

Of all the sapphire market areas, LEDs are generating the biggest buzz. Rubicon recently received backing from new Series B investors for Epitaxial polishing, a necessary processing step for wafers used in making LEDs.

Full implementation of LED products will not only revolutionize lighting, but it will dramatically reduce power consumption as well. “Right now, the US uses one third of all power generated for lighting,” Moffitt said. “With LEDs, we’ll use one tenth of that,” Cox added. “Thirty percent of the current power generated will be available for other uses.”

In the future, houses built with LED will never need to change a light bulb. “We’ll be lighting walls instead of just fixtures,” he continued. “LED lasts 10 to 15 years”. Currently street lights, traffic signals, and the lighting in airports are being changed to white LEDs. Applications for homes could come within the next two to three years.

Part of Rubicon’s future includes its extensive relationship with Northwestern University. Currently, Rubicon and Northwestern collaborate on a wide range of projects and initiatives and share a commitment to the commercialization of new material science technologies. The relationship allows Rubicon’s Materials Science Engineers to have access to the Northwestern University facilities and resources for research and development projects. Likewise, Northwestern has access to Rubicon’s facilities and technology.

Another piece of the Rubicon/Northwestern partnership is the I-Tech/Kellog Association. This association provides funds for Northwestern students to intern with Rubicon management and scientists and gain on-the-job materials science industry experience. Rubicon is also recruiting the best talent from Northwestern, one of the premiere material science and business schools in the country.

These types of partnerships will help ensure Rubicon’s position in a rapidly expanding industry. Currently, only eight manufacturers are producing sapphires on any kind of scale, Moffitt says, meaning they operate more than one furnace. “But the industry is growing very rapidly, responding to new customer demand.” All of this contributes to Moffitt’s excitement about the future.

“Sapphire is to LEDs what silicon is to IC chips,” Moffitt explained. “It is a very nice industry to be in. We’re very excited about the future and being a big part of a change in illumination technology.”

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