First, the currently developing momentum of the LED industry is relatively good.
Since the first red LED in the 1960s, to the historic GaN blue LED technology in the 1990s to make a huge breakthrough, so that LED white lighting can be achieved; due to the obvious benefits of LED lighting production, countries around the world are in the government's strong financial support to accelerate the pace of LED lighting to replace traditional lighting, Japan, the United States, the European Union, South Korea, Taiwan, China and Chinese government have formulated corresponding development plans.
The Chinese government from 2005 approved five semiconductor lighting industry bases in Dalian, Xiamen, Shanghai, Nanchang, Shenzhen, etc., and then in 2007 and 2008 approved two semiconductor lighting industry bases in Shijiazhuang, Yangzhou, etc., to give long-term support in policy, tax and funding.
With a strong expectation of the future market amount, and at the same time have the active cooperation of government policies at all levels, in is regarded as China's LED industry "soft rib" of the upstream epitaxial and chip manufacturing sector, attracted a large number of funds into. Local enterprises Sanan, Blue, Huachan, etc. have expanded production or construction of new plants; LED giants outside the mainland have also changed their caution, accelerating the layout in mainland China. Taiwan's many LED majors, such as Crystal Power, Ding Yuan and the United States of Cree, SemiLEDs and other global giants have been or plan to build factories in mainland China. Mainland China has become the fastest growing region in the world for LED upstream capacity.
In the process of continuous adjustment and optimization of China's LED industry structure, the scale of Chinese epitaxial and chip enterprises will also be further expanded in the coming years. By August 2010, China has 69 LED epitaxial and chip enterprises (including more than 20 under construction or planned). Among the enterprises already in production or under construction, 48 are involved in LED core link epitaxial and chip manufacturing, and more than 10 are focused on LED chip manufacturing.
From the top 10 LED chip companies in China, the sales of LED epitaxial chips of the top 7 companies in 2009 all exceeded RMB 100 million, and the sales of the top 5 all exceeded RMB 150 million.
Second, what are the enterprises in LED industry? --LED industry chain
LED industry chain can be roughly divided into five parts: raw materials, LED upstream industry, LED midstream industry, LED downstream industry, test instruments and production equipment.
The raw materials of LED light-emitting materials and devices include substrate materials such as GaAs single crystal and aluminum nitride single crystal. Most of them are III-V compound semiconductor single crystals with relatively mature production process, and other materials include metal high purity gallium. The purity of raw materials should be above 6N in general.
LED upstream industry mainly refers to LED light-emitting materials epitaxial manufacturing and chip manufacturing. Due to the high development of epitaxial process, the main structure of the device such as light-emitting layer, limiting layer, buffer layer, reflective layer, etc. have been completed in the epitaxial process, chip manufacturing is mainly to do positive and negative electrodes and complete split detection.
LED midstream industry refers to the LED device packaging industry. In the semiconductor industry, LED packaging industry and other semiconductor device packaging industry is different, it can be used for reality, lighting, communications and other different occasions, packaging a variety of different colors, different shapes of LED light-emitting devices.
LED downstream industry is the industry formed after the application of LED display or lighting devices. In terms of LED applications, the surface should be broader, should also include those in home appliances, meters, light industrial products in the information display, but these are not enough to support the LED downstream industry. Among the main application industries are LED display, LED traffic signal, solar cell LED beacon lights, liquid crystal backlight, LED car lights, LED landscape lighting, LED special lighting, etc.
The main testing instruments are: ray double crystal diffractometer, fluorescence spectrometer, Rutherford backscatter channel spectrometer for epitaxial materials, etc. LED photoelectricity characteristic tester and spectrum analyzer for chip and device testing instruments. The main test parameters are forward and reverse voltage, current characteristics, normal phase light intensity, light intensity distribution, luminous flux, peak wavelength, main wavelength, color coordinates, and color rendering index.
Production equipment includes MOCVD equipment, liquid phase external plating furnace, lithography machine, scribing machine, automatic solid crystal machine, gold wire ball soldering machine, silicon and aluminum wire ultrasonic pressure soldering machine, glue filling machine, vacuum oven, chip counter, chip detector, film reversing machine, optical color point automatic sorting machine, etc.
These different types of enterprises and their products, as long as the correspondence is easy to distinguish, especially in the exhibition, participated in the semiconductor or light fair colleagues may have a more direct impression, in the exhibition as long as a little attention can easily distinguish these enterprises and products, the following is the LED industry manufacturing process chart, we can put the different enterprises and products, with the chart correspondence, it is easy to understand LED industry some basic situation.
Third, which companies are our customers? What products do they need.
From what we know so far, our customers are mainly concentrated in LED upstream and midstream enterprises, mainly substrate processing enterprises and chip manufacturing enterprises, the specific application is in the epitaxial wafer growth before the substrate grinding and polishing and chip manufacturing process grinding stage.
1, epitaxial wafer growth before the substrate grinding and polishing
We contact the end-use customers (mainly polycrystalline micropowder-related customers) is part of the sapphire substrate processing companies, first, we need to understand the sapphire substrate, in 1993, Japanese scientists Shuji Nakamura developed the first blue light-emitting diode on GaN substrates, to achieve high brightness and indirectly achieve white light, since then it has become the most widely used light-emitting semiconductor materials. Can be used for GaN substrate materials are mainly sapphire (Al2O3), SiC, Si, ZnO, GaN, but only the first two have been a larger commercial application, and can provide products of very few companies. Japan's Nichia has monopolized the supply of most sapphire substrates, while the U.S. Cree is the only company that can provide commercial SiC substrates. The use of Si as a substrate to grow GaN-based LEDs is a technology path that the industry has high hopes for, but because of the existence of material mismatch caused by cracking, low luminous efficiency, high operating voltage, poor reliability and many other insurmountable difficulties, has not been truly commercialized. Sapphire is currently the mainstream substrate material, but its hardness is very high (second only to diamond), the process of drilling, cutting, grinding process is difficult and inefficient, and because the sapphire substrate sheet requires a surface finish above the nanometer level, grinding is particularly difficult.
The above determines the huge increase of sapphire substrate material usage in the rapid development of semiconductor lighting, especially white LEDs, and also determines the best-selling of polycrystalline products that have a greater advantage in sapphire rough polishing.
The processing process of sapphire substrate generally includes: lattice directional cutting OD grinding (mostly with grinding wheel, diamond micro powder may be used); slicing (wire saw or cutting blade); chamfering (grinding wheel); grinding (one or more channels, mostly with polycrystalline micro powder, depending on the final substrate grinding requirements 6um, 3um, 1um, etc.); polishing (silica polishing solution, black skin polishing pad).
In addition to sapphire materials, GaN blue LED substrate and SiC materials such as the Chinese Academy of Sciences Institute of Physics Tianke Heda, also need similar to the sapphire substrate research and polishing materials.
In addition, in addition to blue LED there are GaAs red, GaP green LED, their substrate materials are GaAs and GaP, these substrate materials are easier to process compared to sapphire, the general use of alumina micronized grinding, polishing and polishing pad of silicon dioxide polishing solution, can be.
2, chip manufacturing process of grinding process
GaN blue LED chip (microstructure schematic diagram below) after the end of the wiring inspection, in order to solve the problem of heat dissipation of sapphire, but also to facilitate the scribing, the need for a grinding process, which is to reduce the thickness of the sapphire substrate, the thickness from about 450um to about 100um
This we often say the LED chip backside thinning, grinding chip mainly has two steps: first in the lateral thinning machine, with 50-70um grinding wheel grinding to grind away the thickness of about 300um; and then use polishing machine (show and, NTS, WEC, etc.) for different grinding disc (tin / copper disc), using the appropriate diamond polishing solution (water / oil) on the back of the chip polishing, remove the loss of about 20um damage layer, that is, to complete the work of the grinding chip. There are also individual requirements for higher chip products will also use silica polishing solution and then fine polishing.
Fourth, the end.
The above is my brief introduction to the LED industry, I hope that colleagues understand our product applications and customer background to help, and then to give you some help in the development of work. I know less and shallower things, I hope we will strengthen communication in the future work, learn together, interoperability, mutual assistance, together to open the door to the LED market.