Reduce the cost of high brightness LED wafer bonding and testing

Including the main purpose of high brightness LED lights, lights, and backlit display, etc. Although the high cost of high brightness LED, its superiority to make the LED application is acceptable. High brightness LED also has the potential for general illumination. To reduce the cost of high brightness LED to can be used in the bedroom, office and the parking lot, it is necessary to improve the production efficiency of high brightness LED manufacturing to achieve the goal of lowering the cost of single bit lumens. Such high brightness leds can replace now also in the production of incandescent lamp and all kinds of fluorescent lamp. A significant advantage of high brightness LED is its life is measured by decades.

a variety of high brightness LED photon emission in all directions, including to the direction of the base board below. If substrate have LED area smaller band gap, substrate absorb about half of the reflected light, this greatly reduces the light output. If a piece of wafer bonding containing leds to a high reflectivity on the surface of the substrate on the wafer, the substrate wafer can also heat dissipation, toward the substrate of light will be reflected back to and through the launch pad, this greatly improves the total light output.

many materials such as silicon, gallium arsenide and gallium nitride, gallium phosphide, and sapphire, etc. , can be used to make the LED. Grow on the compound semiconductor photonic layer and transfer to the silicon or similar material support on the wafer, and the back of the wafer is exposed. Now only large compound semiconductor to 4 inches. This limits the LED wafer and wafer is the combination of the size of only 2 to 4 inches in diameter. Another problem is that the two need to bonding crystal different thermal

original expansion coefficient caused by bonding process is very slow. Because each time only one wafer pair bonding, this limits the high brightness LED, the productivity of unit cost is high. These limits can be through the use of the new development of SUSS wafer bonding devices to breakthrough, this device can realize more for wafer bonding of synchronization.

with gallium nitride as the raw material of high brightness LED production have two kinds of methods: gold - namely Gold hot pressing and jinxi eutectic bonding. In gold - Gold hot-pressing bonding process, a 1 to 3 microns thick layer of gold and cut off bonding layer is coated on each piece of wafer. In order to eliminate surface contamination affects solid diffusion mechanism, require several steps of cleaning, Ultraviolet ozone or chemical wet process) 。 When bonding temperature is 250 ° to400 °, pressure is 1 to 7 mpa, from several minutes to several hours. For additional time and pressure when in low temperature. If time and pressure is not enough, usually between wafer and wafer only partial combination.

Sikkim eutectic method is formed by the spread of the solid and liquid metal alloy combination between to bond. A wafer coated with a layer of a text, while the other wafers coated with a layer of jinxi thickness up to 5 microns. Painted the diffusion barrier layer when necessary. In order to avoid tin oxidation at high temperature, wafer bonding should be carried out in gas, such as in hydrogen nitrogen mixture ( 95%N2,5%H2） In the. This method only need low voltage and with a bit higher than the melting point temperature, it can be finished in a few minutes bonding.