The Art of Sapphire – Ensuring High Quality Sapphire Wafers

You might think from the title of this post that we’re talking about gems or jewelry, but we’re not. We’re talking about commercial sapphire – the type that is used to make LEDs. Not all commercial sapphire is high quality. In fact, the quality of the sapphire crystal impacts the quality of the sapphire wafer and the resulting LED. Sapphire producers must go through a qualification process in order for LED manufacturers to select the vendor. What are they looking for? Raja Parvez, President and CEO of Rubicon Technology shared information about what LED manufacturers look for when they come to Rubicon.

Rubicon Technology shared information about what LED manufacturers look for when they come to Rubicon.

Flatness: When a sapphire wafer is not flat it will become like a potato chip during processing. This prevents the wafer from being processed properly. The key tolerance for 6-inch and 8-inch is the flatness across the wafer. Thickness is not standardized yet and can range anywhere from 1-2 mm. The greater thickness also uses a larger amount of sapphire, but we’ll get to that in a later post.

Cleanliness: Surface morphology of the wafer needs to be clean and presents a uniform surface before depositing the epitaxial layer. The particulate count on the polished surface is very important too. A dirty wafer will cause issues when depositing the epitaxial layer. In addition, if impurities have been introduced in crystal development, colorization will be introduced rendering a colored crystal. This has a negative effect on commercial sapphire quality in contrast to gem quality sapphire that depend on impurities for their color such as red (with chromium impurities) for rubies and blue (with titanium and iron impurities) for sapphire. For example, commercial sapphire crystals with impurities result in pink wafers that interfere with LED performance.

Stress: LED manufacturers need stress-free wafers. Sapphire crystals go through temperature cycles of up to 1200ºC. That causes stress that can create cracks in the wafers and reduce yield. Rubicon’s ES2 technology produces almost stress-free crystals. During the crystal growth cycle, 50 percent of the time is taken to grow our crystal, and 50 percent is taken to cool down the crystal. During cooling, stresses are automatically released. Other wafer technologies introduce significant stress, so it’s common to put those wafers through an annealing furnace to reduce stress. This adds operational costs and time to production.

LED Lighting Drives Growth in Global Lighting Market

A new research report from IMS Research in July 2011 states that LED lighting is driving growth in the global lighting market. Previously stagnant, the lighting market is experiencing new growth. IMS Research Lighting Market Analyst, Philip Smallwood, states that “Growth is stemming from advancements in LEDs which are increasing their efficiency, while decreasing their overall price. Currently, LEDs make up 10% of the total lighting market ($US), but by 2015, this is expected to increase to 46%.”

According to IMS, the new LED market is bringing new entrants to a rather stagnant lighting market that was dominated by the same global lighting suppliers for decades. Innovations in LED technologies have opened the door for these new suppliers to develop different niches within the lamp (light bulb) and luminaire (lighting fixture) markets. This creates a great growth environment.

The Rise of the LED

With EISA of 2007, Congress set forth the rise of the LED. The new standards launched a paradigm shift within the residential lighting market. The incandescent technology in the U.S. will be phased out, and, as per the standards, there are only three alternatives to fill the empty sockets in every American home and business: CFLs, halogen and LEDs.

Each alternative has its good and bad points. CFLs, while more energy efficient than incandescents, also contain harmful mercury. Not many people want to take out an EPA certified disposal kit to clean up a light bulb (yes, you actually have to and can pick up the kits at many home and hardware stores). Then, halogen bulbs tend to cost the same as CFLs, but don’t last any longer. LEDs have improved over the years. LEDs last about 50,000 hours (compared to 1,000 for an incandescent) and are about 30% more energy efficient. They still cost a pretty penny, but the costs are expected to come down to more reasonable levels. Home Depot now offers a proprietary brand of LEDs under the EcoSmart name, including a bulb that retails for $19.97 and is a 40W equivalent.

By 2015, IMS analyst Phillip Smallwood “expects LED lamp replacement installations will greatly increase. Technological breakthroughs will make these lamps look more like general incandescent lamps, all while being cost competitive with CFLs. At the same time, concerns over the mercury contained in CFL lamps and their shorter life will make them less and less appealing to consumers. More rebate programs will be established for LEDs leading to even more replacements being installed.” Here’s what he thinks the market will look like.

Incandescent Bulbs Days are Numbered

In order to figure out the impact of the LED on the general lighting market, IMS Research created a global installed base model of incandescent, CFL, linear fluorescent HID and halogen lamps, divided by region in 2010. The graphic below shows that there are approximately; 3.9 billion incandescent, 1.75 billion CFL, 1.75 billion linear fluorescent, 50 million HID and 550 million Halogen lamps installed in the United States alone.

Incandescent bulbs have enjoyed long dominance since the days of Thomas Edison. According to IMS analyst Phillip Smallwood, “the main reason behind this is that incandescent lamps are extremely cheap with an average selling price of approximately $0.43 cents. Add an average cost of electricity of $0.11/kWh to the equation, and you get a large group of consumers that base their lamp purchasing decision solely on the initial cost of the lamp.”

Unfortunately for consumers, Congress enacted The Energy Independence and Security Act (EISA) of 2007. That act created higher efficiency standards targeting 40–100W incandescent and halogen general-service lamps. Starting in 2012, 100W lamps will be required to be 28% more efficient, 75W lamps in 2013 and 40-60W lamps in 2014. According to Smallwood, the new efficiency standards effectively ban most current incandescent technologies from being purchased after the block out date.

Source: IMS Research

Bringing Down the Cost of LED Lighting

In LEDs Magazine, Financial analyst Jed Dorsheimer of Canaccord Genuity estimates the LED portion of the Bill of Materials (BOM) at $25. Jed argues that number needs to drop to $4 to enable a $10 retail price for a 1000 lm bulb. He says the cost is critical because he estimates the current payback time for an LED bulb to be 11 years in residential applications. Estimates on the industry are that LED light bulbs will last about 50,000 hours (more than 2000 days if lit 24 hours a day) versus 1,000 hours for the typical incandescent bulb.

Dorsheimer sees a move to larger diameter sapphire wafers necessary to the success of LED lighting. He says migrating from 2-inch wafer to 4- or 6-inch diameter wafers offer better thermal stability and ultimately better yield. Dorsheimer stated, “Yield trumps all in this industry.” He said that lighting could consume more than 100 billion additional LEDs by 2020.

LED light bulb

Haitz’s Law – Moore’s Law for LEDs

Haitz’s Law is an observation/prediction about the steady improvement over the years of light-emitting diodes – LEDs. It states that every decade, the cost per lumen (unit of useful light emitted) falls by a factor of 10, the amount of light generated per LED package increases by a factor of 20, for a given wavelength (color) of light.

It is considered the LED counterpart to Moore’s Law, which states that the number of transistors in a given integrated circuit doubles every 18 to 24 months.

Silicon vs. Sapphire? Silicon is not ready for prime time.

Sapphire is used for LEDs much like the computer industry uses silicon as a foundation for computer chips. Roughly 80% of the LED market uses sapphire for a foundation. Bridgelux has made some noise about building a larger diameter wafer out of silicon. Bridgelux contends that leveraging silicon would bring down costs by using existing automated semiconductor lines. However, the company admits that a number of the processes used to produce LEDs would have to be modified because some materials used are incompatible with silicon substrate manufacturing.

Bridgelux maintains that have to work 12 to 24 months to catch up with the sapphire companies. Rubicon Technology is already in volume production of 6 inch and 8 inch sapphire wafers for LED manufacturing. Others like Monocrystal and STC have been working to produce larger diameter sapphire wafers as well.

In an interview with Efficien’Si Magazine, Rubicon Technology CEO Raja Parvez says that LED manufacturers “want 8-inch production because it is more cost effective and re-utilises the current infrastructure available to them.” He says that a company like Rubicon can help companies move to larger diameter “through specification alignment and participation in customer design-of-experiments for process optimization. Many of our engineers are from the optoelectronics and semiconductor industries. Since we have this experience, and work with many LED chip companies, we can reduce the cycle time at the R&D level and reduce the trial period so they can move to production faster.”

More Better MOCVD Reactors Are a Win-Win for All

Recently, LEDs Magazine featured an article by analyst Tom Hausken, Director of the Components Practice, at Strategies Unlimited about the recent bump in MOCVD reactor sales. MOCVD reactors are used to manufacture LED chips. According to Tom, the LED world needs more, better reactors. But, the likelihood is that this new generation of reactors will be used for high-end LEDs – the hardest to make.

On the surface, many industry observers reacted to the shopping spree in reactors negatively. Many think it is a bubble, but Tom thinks otherwise. What’s behind all this new interest in reactors? Subsidies from the China government have been encouraging a new “LED Valley” in China. The new investment is drawing in investment from Taiwan and Korea to build joint venture plants in this new “LED Valley.” Again, this is just at the surface. These reactors are likely to contribute to low-end cheap LEDs.

His rationale is that high-end LEDs need experts to run the MOCVD reactors. There are only so many of these guys for hire in China and they are paid very handsomely for that expertise, like CEOs and rock stars, at as much as $250,000 a year. Tom writes “…none of this is likely to impact the market for high-end LEDs, which are the most difficult to make. The high-end suppliers know their process well, and are likely to expand capacity regardless of subsidies.”

Who wins? According to Tom, “the end-user gains, no matter what. China gains some experience that it didn’t have, and more domestic production to serve its vision for a greener future. If overcapacity leads to a glut of LEDs, the most pressure will be on lower-tier LED suppliers.”

Sapphire Substrates for LED: The Big Move Toward 6″ Has Already Started

Recently, market research firm Yole Developpement put on a webcast about the sapphire substrate market for LEDs. The webcast featured Yole analyst Philippe Roussel and Rubicon Technology president and CEO, Raja Parvez.

During the webcast Yole’s Roussel shared market data about the significant progress six inch sapphire wafers are making into the LED market. By 2020, Yole expects six inch large diameter sapphire to dominate the market with a 70% market share.

Source: Yole Development

Rubicon’s Parvez walked through Rubicon’s approach to making large diameter sapphire. Parvez highlighted the high barrier to entry to the large diameter market and the need to grow sapphire in an unconstrained environment to maintain quality to maximize yield and throughput to produce the commercial volumes needed to support the high growth LED lighting industry.

Rubicon Technology Sapphire Boules

You can view the Webcast archive here: Sapphire Substrates for LED: The Big Move Toward 6″ Has Already Started

NASCAR Premiers World’s Largest LED TV

We want our LED TV! NASCAR premiered the world’s largest LED TV at the NASCAR All-Star Race on May 21st at Charlotte Motor Speedway. The display stands 110 ft. above the race track centered along the backstretch giving the crowd a great view of the racing action. It took Panasonic 11,000 man hours over four months to build the 16,000-square-foot screen using 158 panels made with LEDs. The 332-and-a-half-ton structure is the largest HDTV in the world. The screen is made up of 158 panels illuminated by nine million LED lamps.

Dale Earnhardt Jr., NASCAR’s most popular driver, took the HDTV for a test drive that showed him taking virtual laps around the legendary 1.5-mile track using an iRacing simulation. Click this link for the video.

Dale Earnhardt, Jr. gets a sneak peek at the world's largest LED TV.