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   - LED芯片技术及国内外差异分析

芯片,是LED的核心部件。目前国内外有很多LED芯片厂家,然芯片分类没有统一的标准,若按功率分类,则有大功率和中小功率之分;若按颜色分类,

则主要为红色、绿色、蓝色三种;若按形状分类,一般分为方片、圆片两种;若按电压分类,则分为低压直流芯片和高压直流芯片。国内外芯片技术对

比方面,国外芯片技术新,国内芯片重产量不重技术。

衬底材料和晶圆生长技术成关键,目前,LED芯片技术的发展关键在于衬底材料和晶圆生长技术。除了传统的蓝宝石、硅(Si)、碳化硅(SiC)衬底材料以外,

氧化锌(ZnO)和氮化镓(GaN)等也是当前LED芯片研究的焦点。目前,市面上大多采用蓝宝石或碳化硅衬底来外延生长宽带隙半导体氮化镓,这两种材料价格

都非常昂贵,且都为国外大企业所垄断,而硅衬底的价格比蓝宝石和碳化硅衬底便宜得多,可制作出尺寸更大的衬底,提高MOCVD的利用率,从而提高管芯

产率。所以,为突破国际专利壁垒,中国研究机构和LED企业从硅衬底材料着手研究。

但问题是,硅与氮化镓的高质量结合是LED芯片的技术难点,两者的晶格常数和热膨胀系数的巨大失配而引起的缺陷密度高和裂纹等技术问题长期以来阻碍

着芯片领域的发展。

 

无疑,从衬底角度看,主流衬底依然是蓝宝石和碳化硅,但硅已经成为芯片领域今后的发展趋势。对于价格战相对严重的中国来说,硅衬底更有成本和价

 

格优势:硅衬底是导电衬底,不但可以减少管芯面积,还可以省去对氮化镓外延层的干法腐蚀步骤,加之,硅的硬度比蓝宝石和碳化硅低,在加工方面也

可以节省一些成本。

 

目前LED产业大多以2英寸或4英寸的蓝宝石基板为主,如能采用硅基氮化镓技术,至少可节省75%的原料成本。据日本三垦电气公司估计,使用硅衬底制作大

尺寸蓝光氮化镓LED的制造成本将比蓝宝石衬底和碳化硅衬底低90%。

 

国内外芯片技术差异大

 

在国外,欧司朗、美国普瑞、日本三垦等一流企业已经在大尺寸硅衬底氮化镓基LED研究上取得突破,飞利浦、韩国三星、LG、日本东芝等国际LED巨头也

掀起了一股硅衬底上氮化镓基LED的研究热潮。其中,在2011年,美国普瑞在8英寸硅衬底上研发出高光效氮化镓基LED,取得了与蓝宝石及碳化硅衬底上顶

尖水平的LED器件性能相媲美的发光效率160lm/W;在2012年,欧司朗成功生产出6英寸硅衬底氮化镓基LED。

 

反观中国内地,LED芯片企业技术的突破点主要还是提高产能和大尺寸蓝宝石晶体生长技术,除了晶能光电在2011年成功实现2英寸硅衬底氮化镓基大功率

LED芯片的量产外,中国芯片企业在硅衬底氮化镓基LED研究上无大的突破,目前中国内地LED芯片企业还是主攻产能、蓝宝石衬底材料及晶圆生长技术,

三安光电、德豪润达、同方股份等内地芯片巨头也大多在产能上取得突破。

LED chip technology and variance analysis at home and abroad

The chip is the core component of the LED. There are a lot of the LED chip manufacturers at home and abroad, but no unified standard chip classification, classification in terms of power, there are points of high power and small power; If according to the classification of color,

Mainly for red, green, blue three; If according to the shape classification, generally divided into two kinds of square piece, wafer; If according to the classification of voltage, it is divided into low voltage dc and high voltage direct current chip. Chip technology at home and abroad

Than in terms of foreign new chip technology, heavy production not heavy domestic chip technology.

Substrate materials and wafer into key growth technology, at present, the LED chip technology substrate materials and wafer growth is the key of the development of technology. In addition to the traditional sapphire, silicon (Si), silicon carbide (SiC) substrate materials,

Zinc oxide (ZnO) and gallium nitride (GaN) is also the focus of current research LED chip. On market at present, most of sapphire and silicon carbide substrate is used to broadband gap semiconductor gallium nitride epitaxial growth, these two kinds of material price

Are very expensive, and monopoly by foreign companies, while prices of silicon substrate sapphire and silicon carbide substrate much cheaper, can produce larger substrate, improve the utilization rate of MOCVD, thus improve the tube core

Production rate. So, to break through the barriers to the international patent, research institutions and LED Chinese companies from working on silicon substrate material.

But the problem is that the high quality of silicon and gallium nitride is combined with the technical difficulties of the LED chip of lattice constant and the thermal expansion coefficient of the two huge mismatch caused by the high density of defects and cracks and other technical problem for a long time

The development in the field of chip.

There is no doubt that from the perspective of the substrate mainstream substrate is still a sapphire and silicon carbide, but silicon has become a development trend of the chip area in the future. For China's price is relatively serious, silicon substrate is more cost and price

Advantage: silicon substrate is electrically conductive substrate, not only can reduce the tube core area, you can also save on gallium nitride epitaxial layer of dry etching step, in addition, the hardness of silicon less than sapphire and silicon carbide, also in the processing

Can save some cost.

At present most of the LED industry to 2 inches or 4 inches of the sapphire substrate is given priority to, such as can use silicon technology of gallium nitride, at least 75% of the raw material cost can be saved. Sanken electric company estimated, using silicon substrate production

Size blu-ray gallium nitride LED manufacturing costs will be 90% lower than the sapphire substrate and the silicon carbide substrate.

The large difference of chip technology at home and abroad

Abroad, osram, American pury, sanken, first-class enterprise in large size silicon substrate on gallium nitride based LED research breakthrough, philips, samsung, LG, Toshiba and other international LED titans

An upsurge of gallium nitride based on silicon substrate LED the study. Among them, in 2011, the United States pury in 8 inches on silicon substrate to develop high photosynthetic efficiency gallium nitride leds, made with sapphire and silicon carbide substrate

Sharp LED device performance comparable to the level of the luminous efficiency of 160 lm/W; In 2012, osram successfully produce 6 inches silicon substrate gallium nitride-based leds.

In mainland China, the LED chip to enterprise technology breakthrough largely increase its production capacity and large size sapphire crystal growth technology, in addition to the lattice lighting in 2011 successfully 2 inches silicon substrate gallium nitride based power

Volume production of LED chip, chip Chinese companies in the silicon substrate gallium nitride LED research on no major breakthrough, the Chinese mainland LED chip companies or main production capacity, the sapphire substrate materials and wafer growth technology,

 

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