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Today to discuss the growing process of LED epitaxial wafers, integrated circuits in a small early age, making thousands of chips every 6? Epitaxial wafer, now sub-micron large VLSI, each 8? Epitaxial wafer is also completed only a two hundred large chips. Although the epitaxial wafer manufacturing move? Invest tens of billions, but it is the basis for all of the electronics industry.
Czochralski silicon is grown, you first need a very high purity silicon ore into the furnace, and adding predefined metal material, so that arising out of silicon boules have the required electrical characteristics, then you need to all substances melting and then grow into single crystal silicon boules, the following will be all grown boules process do introduction:
Crystal growth main program:
1, melted (MELtDown)
This procedure is placed in a quartz crucible bulk polysilicon heating system 1420 degrees centigrade above its melting temperature, in this phase the most important parameter for the position of the crucible and the supply of heat, if compared with the use of Great power to melt the polycrystalline silicon, quartz crucible of life will deteriorate if the power is too low melting process takes too long, affecting the overall production capacity.
2, neck growth (Neck Growth)
When the silicon melting temperature of the slurry stabilized, gradually injected into the direction of the seed mixture, then the seed crystal pulled up, and down to a certain diameter (about 6mm), to maintain this diameter and stretch 10-20cm, with Elimination row difference (dislocation) seed within such zero emission difference (dislocation-free) control is mainly confined to the row difference in the growth of the neck.
3, Crystal Crown Growth (Crown Growth)
After a long neck, slowly lower the casting speed and temperature, the diameter of the neck is gradually increased to the desired size.
4, crystal growth (Body Growth)
Use of casting speed and temperature adjustment to maintain a fixed late ingot diameter, the crucible must continue to rise to maintain a constant liquid level, and from the crucible and the ingot reached the level of radiation heat will gradually increase, this will cause a radiant heat source-industry interface temperature gradient becomes smaller, it is necessary to gradually reduce the growth stage in the ingot casting speed, in order to avoid distortions of the ingot produced.
5, trailing growth (Tail Growth)
When the crystal growth to a fixed length (required), the diameter of the ingot to be gradually reduced until the separated liquid, which was to avoid thermal stress caused by the difference between the sliding surface discharge phenomenon.
Cutting:
Boule grown since you can cut a piece of it, which is the epitaxial wafer. Chips, discs, is a "chip or" substrate chip semiconductor element, stretching from high-purity silicon element grow boules (Crystal Ingot), the circular sheet called epitaxial wafers (wafer) cut out of the .
Epitaxy:
Arsenide? Epitaxy by different processes can be divided into LPE (liquid phase epitaxy), MOCVD (metal organic vapor phase epitaxy) and MBE (molecular beam epitaxy). Lower LPE technology, mainly used for general light-emitting diodes, and high levels of MBE technology, easy to grow epitaxial thin, and high purity, flatness is good, but the low production capacity, epitaxial growth rate slow. In addition to high purity MOCVD, smooth and good, the production capacity and speed Yijiao MBE epitaxial growth faster, so now it is mostly in MOCVD to produce.
First, the process is expensive GaAs substrate into the organic chemical vapor deposition furnace (Jane the MOCVD, also known as epitaxial furnace), and then passed through III, an alkyl compound of Group II metal element (methyl or ethyl compound) vapor and non-metallic (V or VI elements) hydride (or alkyls) gas at a high temperature, the pyrolysis reaction occurs to form III-V or group II-VI compound deposited on the substrate, a layer grown the compound semiconductor epitaxial layer thickness of only a few microns (1 mm = 1000 microns). Long or GaAs epitaxial layer sheet is often called epitaxial wafer. After the wafer after processing chip, power will be able to send out? Very pure monochromatic light color, such as red, yellow and so on. Different materials, different growing conditions and the different epitaxial layer structure can change the light emission? Color and brightness. In fact, in the epitaxial layer a few microns thick, the real emission also is one of only a few hundred nanometers (1 micron = 1000 nanometers) thick quantum well structure.
Reaction formula: Ga (CH3) 3 PH3 = GaP3CH4
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