Sapphire, silicon carbide two strong conflicting outcome undecided, the silicon substrate GaN substrate may affect the global industry situation A new force suddenly rises. LED

Las Vegas LightFair International 2012 lighting exhibition in the U.S. Jason just pull the curtain, vice president of marketing BridgELux Posselt publicity the company has realized GaN LED production 8 inch silicon substrate.

Jason Posselt pointed out that the company has previously created 135 lumens per watt GaN-On-Silicon LED on silicon substrate on the growth, the significance of this method is to reduce the cost of the largest, large size wafer in the production of LED at the same time, the price must be lower than the silicon substrate sapphire substrate prices. Over the years, the technology has not been too much emphasis on the reasons for the yield, cost and technical barriers. Today, the company has successfully created a competitive product, but also access to many market customers. Bridgelux's latest release, 614mW, <3.1V@350mA's 1.1mm size LED, is currently the highest efficiency of 8 inch silicon LED products, the company stressed that the future will continue to publish the progress and development in this regard. In capacity, the silicon substrate is the semiconductor industry the most common substrate materials, including 8 inch wafer plant equipment is old, the silicon substrate LED can easily use the original production capacity. Bridgelux strategy is to cooperate with the Japanese giant Toshiba, the two companies will be based on Toshiba in Asia, a 8 inch wafer plant capacity, the collocation of modified GaN-On-Silicon's technique, mass production of 8 inch silicon substrate LED, the 2013 production may not be small, can be expected to reduce the cost of 75%. LEDinside think this development actually affects the majority of the existing LED chip industry to sapphire based technology progress, originally expected by the market is not so fast, but the breakthrough Bridgelux is likely to change the existing pattern of competition, fierce confrontation caused by different paths of technological progress. Substrate material technology is the cornerstone of the development of semiconductor lighting industry. Different substrate materials require different epitaxial growth technology, chip processing technology and device packaging technology. The choice of substrate materials depends mainly on the following nine aspects: [1] structure properties, crystal structure of epitaxial material and the substrate of the same or similar, the lattice constant mismatch of small, good performance, small crystal defect density; [2] interface characteristics, is conducive to epitaxial nucleation and strong adhesive property; [3] good chemical stability. It is not easy to break down and corrosion in the epitaxial growth temperature and atmosphere; [4] thermal properties, including thermal conductivity and thermal mismatch of small [5]; good conductivity, can be made on the structure of [6]; good optical performance, making the emitted light is absorbed [7] substrate; good mechanical properties and devices easy processing, including thinning, polishing and cutting; [8] low price; [9] large size, generally require a diameter of not less than 2 inches.

Sapphire /Al2O3 currently used the most common substrate for GaN growth is Al2O3, the utility model has the advantages of good chemical stability, do not absorb visible light, moderate price, manufacturing technology is relatively mature; although many deficiencies, but be overcome, such as the large lattice mismatch by transition layer growth technology to overcome and the poor conductive property through the ipsilateral P and N electrodes to overcome poor mechanical properties, easy cutting by laser scribing is overcome, the thermal mismatch epitaxial layer formed compressive stress and without cracking. However, the poor thermal conductivity of the device does not show obvious deficiencies in the small current operation, but the problem is very prominent in the large current operation of power devices.

With the flip chip parts manufacturers (flip-chip) to prepare the power devices to overcome this problem. In the international market, the research and development task of Al2O3 substrate is to grow large diameter Al2O3 single crystal, to the direction of 4-6 inch, as well as reduce impurity pollution and improve the quality of surface polishing. The current mainstream sapphire substrate manufacturers are able to achieve 6 inches bulk delivery. Han factory Samsung LED has turned most of the production capacity of 6 inches. However, the current mainstream of China's chip factory or 2 inch chip, mainly based on cost considerations.

According to the current market price of the substrate LEDinside:

4 inches in size is only about 2 inches, but the price is close to 2 inches of the film 7 times. SiC /SiC in addition to the Al2O3 substrate, the substrate for GaN growth is SiC, its market share ranked second, it has many advantages, such as good chemical stability, good electrical conductivity, good thermal conductivity, does not absorb visible light, but also very insufficient prominent, such as the price is too high, the crystal quality is difficult to achieve Al2O3 and Si so good, mechanical processing performance is poor. In addition, the SiC substrate absorbs less than 380 nm of ultraviolet light, is not suitable for the development of nm under 380 LED.

As SiC substrate excellent electrical conductivity and thermal conductivity, not like the Al2O3 substrate power type gallium nitride LED device using flip chip technology to solve the heat problem, instead of using the electrode structure, can solve the power type gallium nitride LED device with good heat dissipation problems, so in the development of semiconductor lighting technology the field occupies an important position. The SiC substrate can provide high-quality commercial manufacturers only the United States CREE company, Cree company announced on April 12, 2012, the white power type LED light effect LED industry once again hit a record, up to 254 lm/W. This record than the Al2O3 substrate to achieve the highest luminous efficiency record of nearly a hundred lm. The research and development of SiC substrate is to reduce manufacturing cost and improve crystal quality. Silicon /Si on silicon substrate preparation is the ability of light emitting diode