I. Main types of semiconductor materials
Semiconductor materials can be classified according to chemical composition, and then amorphous and liquid semiconductors with special structures and properties can be classified into one category separately. According to this classification method, semiconductor materials can be divided into elemental semiconductors, inorganic compound semiconductors, organic compound semiconductors and amorphous and liquid semiconductors.
1. elemental semiconductors: There are 1 1 semiconductor materials distributed in groups Ⅲ a to ⅶ A of the periodic table of elements. The black box in the table below is this 1 1 element semiconductor, where c stands for diamond. Carbon, phosphorus and selenium have two forms: insulator and semiconductor. B, Si, Ge and Te are semi-conductive; Tin, arsenic and antimony have two forms: semiconductor and metal. The melting point and boiling point of P are too low, and the vapor pressure of I is too high, which is easy to decompose and of little practical value. The stable states of arsenic, antimony and tin are metals, but semiconductors are unstable. B, C and Te have not been utilized due to the difficulties in preparation and performance limitations. So in 1 1 elemental semiconductors, only Ge, Si, Se? Three elements are used. Germanium and silicon are still the two most widely used semiconductor materials.
(semiconductor material)
2. Inorganic compound semiconductors: divided into binary system, ternary system and quaternary system. ? Binary system includes: ① Ⅳ-Ⅳ families: SiC and Ge-Si alloys have sphalerite structure. ② Ⅲ-ⅴ: It consists of Ⅲ elements Al, Ga, In and V elements P, As and Sb in the periodic table, with GaAs as the typical representative. They all have sphalerite structure, which is second only to Ge and Si in application and has great development prospects. ③ Ⅱ-ⅵ family: the compounds formed by Ⅱ elements of zinc, cadmium and mercury and ⅵ elements of sulfur, selenium and tellurium are some important photoelectric materials. ZnS, CdTe and HgTe have sphalerite structure. ④ Ⅰ-ⅶ family: Ⅰ elements copper, silver, gold and? Compounds formed by group VII elements Cl, Br and I, in which CuBr and CuI have sphalerite structure. ⑤-⑤: ⑤ group elements As, Sb, Bi, ⑤ group elements? Compounds formed by sulfur, selenium and tellurium, such as Bi2Te3, Bi2Se3, Bi2S3 and As2Te3, are important thermoelectric materials. ⑥ Group B and transition group elements Cu,? Oxides of zinc, scandium, titanium, vanadium, chromium, manganese, iron, cobalt and nickel are the main thermistor materials. ⑦ Some rare earth elements? Compounds formed by Sc, y, Sm, Eu, Yb, Tm and group v elements n, As or group VI elements s, Se and Te. ? In addition to these binary compounds, there are solid solution semiconductors between elements or between elements, such as Si-AlP, Ge-GaAs, InAs-InSb, AlSb-GaSb, InAs-InP, GaAs-GaP and so on. Studying these solid solutions can play a great role in improving some properties of single materials or opening up new application fields.
(Element Structure Diagram of Semiconductor Materials)
semiconductor material
Ternary system includes: family: this is composed of one group II and one group IV atom instead of two group III atoms in group III-V, such as ZnSiP2, ZnGeP2, ZnGeAs2, CdGeAs2, CdSnSe2, etc. Group: It consists of one group I and one group III atom, instead of two group II atoms in groups II-VI. Like what? CuGaSe2, AgInTe2, AgTlTe2, CuInSe2, CuAlS2, etc. This is composed of a group I atom and a group V atom instead of two group III atoms in the group, such as Cu3AsSe4, Ag3AsTe4, Cu3bbsb4, Ag3bbsb4 and so on. In addition, there are quaternary systems whose structures are basically sphalerite (such as Cu2FeSnS4) and more complex inorganic compounds.
3. Organic compound semiconductors: There are dozens of known organic semiconductors, such as naphthalene, anthracene, polyacrylonitrile, phthalocyanine and some aromatic compounds, which have not been used as semiconductors.
4. Amorphous and liquid semiconductors: The biggest difference between these semiconductors and crystalline semiconductors is that they have no strict periodic crystal structure.
Second, the practical application of semiconductor materials
The preparation of different semiconductor devices has different morphological requirements for semiconductor materials, including slicing, grinding, polishing, thin film and so on. Different forms of semiconductor materials require different processing techniques. Commonly used semiconductor material preparation processes include purification, single crystal preparation and thin film epitaxial growth.
Semiconductor materials All semiconductor materials need to purify raw materials, and the purity is required to be greater than 6 "9s" and the highest is greater than11"9s". Purification methods can be divided into two categories. One is the purification without changing the chemical composition of the material, which is called physical purification. The other is to convert elements into compounds for purification, and then reduce the purified compounds into elements. This method is called chemical purification. Physical purification methods include vacuum evaporation, regional purification, crystal pulling purification and so on. And regional refining is the most widely used one. The main methods of chemical purification include electrolysis, complexation, extraction and rectification. Rectification is the most widely used. Because each method has certain limitations, several purification methods are often combined to obtain qualified materials.
(semiconductor material)
Most semiconductor devices are fabricated on a single wafer or an epitaxial wafer with a single wafer as the substrate. Batches of semiconductor single crystals are all made by melt growth method. Czochralski method is the most widely used method. 80% of silicon single crystals, most germanium single crystals and indium antimonide single crystals are produced by this method, and the maximum diameter of silicon single crystals has reached 300 mm The Czochralski method, which introduces a magnetic field into the melt, is called magnetron crystal pulling method, and a silicon single crystal with high uniformity has been produced by this method. Adding liquid covering agent to the surface of crucible melt is called liquid sealing pulling method, and gallium arsenide, gallium phosphide and indium phosphide are produced by this method. The melt of suspension zone melting method does not contact with the container, and high purity silicon single crystal is grown by this method. Germanium single crystal was produced by horizontal zone melting method. Horizontal directional crystallization method is mainly used to prepare gallium arsenide single crystal, and vertical directional crystallization method is used to prepare cadmium telluride and gallium arsenide. Bulk single crystals produced by various methods go through all or part of processes, such as crystal orientation, tumbling, reference plane, slicing, grinding, chamfering, polishing, etching, cleaning, testing and packaging, to provide corresponding wafers.
Growing a single crystal thin film on a single crystal substrate is called epitaxial growth. The methods of epitaxy include gas phase, liquid phase, solid phase and molecular beam epitaxy. Chemical vapor phase epitaxy is mainly used in industrial production, followed by liquid phase epitaxy. Metal-organic compounds vapor phase epitaxy and molecular beam epitaxy are used to prepare quantum wells and superlattices. Amorphous, microcrystalline and polycrystalline films are mainly prepared on glass, ceramics, metals and other substrates by different methods such as chemical vapor deposition and magnetron sputtering.
Third, the development status of semiconductor materials
Compared with the semiconductor equipment market, the semiconductor material market has been in a supporting role for a long time, but with the increase of chip shipments, the material market will continue to grow and begin to get rid of the shadow brought by the flashy equipment market. According to the sales revenue,
Semiconductor materials Japan maintains its position as the largest semiconductor material market. However, Taiwan Province Province, ROW and South Korea are also becoming important markets, and the rise of material market reflects the development of device manufacturing in these areas. Both wafer manufacturing materials market and packaging materials market have achieved growth, and the future growth will tend to be moderate, but it will still maintain the growth momentum.
(semiconductor material)
The Semiconductor Industry Association of America (SIA) predicts that the semiconductor market revenue will be close to $267 billion in 2008, which is the fifth consecutive year of growth. Coincidentally, the semiconductor material market also constantly rewrites the record of sales revenue and shipments. Both wafer manufacturing materials and packaging materials have increased, and the market revenues of these two parts are expected to be $26.8 billion and $654.38+0.99 billion respectively this year.
Japan continues to maintain its leading position in the semiconductor materials market, accounting for 22% of the total market. In 2004, Taiwan Province Province surpassed North America to become the second largest semiconductor material market. North America ranks fifth after ROW(RestofWorld) and South Korea. ROW includes Singapore, Malaysia, Thailand and other Southeast Asian countries and regions. Many new fabs have invested in these areas, and each area has a more solid packaging foundation than North America.
Chip manufacturing materials account for 60% of the semiconductor material market, most of which come from silicon wafers. The sum of silicon wafer and photomask accounts for 62% of wafer manufacturing materials. In 2007, all wafer manufacturing materials except wet chemical reagents, photomasks and sputtering targets achieved strong growth, making the wafer manufacturing materials market grow by 65,438+06%. In 2008, the wafer manufacturing materials market grew relatively gently, with a growth rate of 7%. It is estimated that in 2009 and 20 10, the growth rate will be 9% and 6% respectively.
One of the most remarkable changes in the semiconductor material market is the rise of the packaging material market. The packaging material market accounts for 33% of the 1998 semiconductor material market, and it is expected that this share will increase to 43% in 2008. This change is due to the increasing use of rolled substrates and advanced polymeric materials in ball grid array, chip-level packaging and flip-chip packaging. As the portability and functionality of products put forward higher requirements for packaging, it is expected that these materials will achieve stronger growth in the next few years. In addition, the sharp rise of gold price made the wire bonding part increase by 36% in 2007.
Similar to wafer manufacturing materials, the growth rate of semiconductor packaging materials will also slow down in the next three years, increasing by 5% in 2009 and 20 10, reaching $20.9 billion and $22 billion respectively. Excluding the gold price factor, and the rolled substrate is not included in the statistics, the actual growth rate is 2% to 3%.
Fourth, the strategic position of semiconductor materials.
In the mid-20th century, the invention of monocrystalline silicon and semiconductor transistors and the successful development of silicon integrated circuits triggered a revolution in the electronics industry. The invention of optical fiber materials and GaAs lasers in Shi Ying in the early 1970s promoted the rapid development of optical fiber communication technology, and gradually formed a high-tech industry, bringing mankind into the information age. The concept of superlattice and the successful development of semiconductor superlattice and quantum well materials have completely changed the design idea of photoelectric devices, and made the design and manufacture of semiconductor devices develop from "impurity engineering" to "energy band engineering". The development and application of nanotechnology will enable human beings to control, manipulate and manufacture powerful new devices and circuits on the atomic, molecular or nano scale, profoundly affect the world political and economic pattern and the form of military confrontation, and completely change people's lifestyle.
Tubatu Online provides you with "every decoration quotation, 1-4 local decoration companies, 3 sets of decoration design schemes" and the decoration pit avoidance strategy for free! Click this link:/Zhu Ye /zxbj-cszy.php? to8to _ from = SEO _ zhidao _ m _ jiare & amp； Wb, you can get it for free ~