CRYSTAL GROWTH TECHNIQUES
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This document discusses techniques for growing silicon single crystals, specifically the Bridgman and Czochralski (CZ) techniques. It provides details on the process and equipment used for each technique. The CZ technique is considered preferable for growing silicon single crystals over the Bridgman technique. CZ crystals have fewer dislocations and allow for better control over the crystal growth process and ambient conditions compared to Bridgman. While more complex, CZ produces higher quality silicon single crystals.
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Crystal growth techniques
This document discusses and compares two techniques for growing single crystal silicon: the Bridgman technique and the Czochralski (CZ) technique. It states that while the Bridgman technique is simpler, involving a quartz ampoule, boat, heater and temperature profile, crystals grown with this method contain many dislocations. The CZ technique is more complex but can produce higher quality crystals. It involves controlling a furnace, crystal pulling rate, ambient conditions and system. The document concludes that the CZ technique is preferable for growing single crystal silicon due to producing crystals with fewer defects.
Float Zone, Bridgman Techniques--ABU SYED KUET
The document discusses various crystal growth techniques including Czochralski (CZ), float zone, and Bridgman techniques. It describes the limitations of the CZ method including impurities introduced from the quartz crucible. The float zone technique produces very pure silicon crystals but allows for smaller wafer sizes. The Bridgman technique employs a temperature gradient to slowly cool a melt contained in a crucible to produce a single crystal ingot.
Oxidation--ABU SYED KUET
Thermal oxidation is commonly used to grow a thin layer of silicon dioxide (SiO2) on a silicon wafer. There are two main types of thermal oxidation - dry oxidation, which uses oxygen gas, and wet oxidation, which uses water vapor. Dry oxidation grows oxide slower but produces higher quality oxide with better electrical characteristics. Thermal oxidation involves heating cleaned silicon wafers to high temperatures (1000-1200°C) in an oxygen or steam environment to allow a chemical reaction that forms SiO2. The grown oxide layer serves many important functions in integrated circuits like passivation, doping masking, and as the gate dielectric in transistors.
Single crystal casting
The document discusses various methods for casting and solidifying materials, including single crystal casting techniques. Single crystal casting of turbine blades involves directional solidification where a single crystal grows longitudinally through a ceramic mold for increased strength. For microelectronics, the Czochralski method pulls a seed crystal from molten material to form long single crystal ingots. Rapid solidification involves cooling molten material at over 106 K/s to form non-crystalline metallic glasses without grain growth. Roll casting is a common rapid solidification technique where molten material is spun against a chilled roll to rapidly solidify into amorphous ribbons or sheets.
Wafer Fabrication, CZ Method--ABU SYED KUET
Crystal structures can be single crystal, polycrystalline, or amorphous. Single crystal silicon is used to manufacture solar cells and semiconductors due to its precise electronic properties. The Czochralski method is commonly used to grow large single crystal silicon ingots from melted, purified silicon in quartz crucibles. The ingots are sliced, polished, and cleaned to produce thin round wafers for semiconductor fabrication. Larger diameter wafers allow more chips to be produced from each wafer, increasing manufacturing efficiency.
Zone melting
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FLOAT ZONE MELTING
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Cements are made by mixing lime and clay, calcinating, and grinding into a fine powder which bonds through chemical hydration reactions when water is added, forming a strong structural material. Powder processing involves grinding materials into particles, pressing and sintering to densify, with sintering using heat to encourage diffusion and reduce pores without grain growth. Single crystal growth involves melting materials in a crucible and slowly extracting a seed crystal to grow a large, pure single crystal for applications such as semiconductors.
Vapor Phase Deposition Techniques
Vapor phase deposition is a technique used to prepare pure optical glasses. It involves vaporizing inorganic compounds and dopants and depositing them as thin films on a substrate through chemical reactions, forming a porous soot preform. The preform is then consolidated through heating to become a solid glass cylinder that can be drawn into an optical fiber. Common vapor deposition methods include outside vapor phase oxidation, vapor axial deposition, modified chemical vapor deposition, and plasma-activated chemical vapor deposition. These processes allow producing silica-based fibers with very low light attenuation and optimal optical properties.
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Crystal growth techniques
This document discusses and compares two techniques for growing single crystal silicon: the Bridgman technique and the Czochralski (CZ) technique. It states that while the Bridgman technique is simpler, involving a quartz ampoule, boat, heater and temperature profile, crystals grown with this method contain many dislocations. The CZ technique is more complex but can produce higher quality crystals. It involves controlling a furnace, crystal pulling rate, ambient conditions and system. The document concludes that the CZ technique is preferable for growing single crystal silicon due to producing crystals with fewer defects.
Float Zone, Bridgman Techniques--ABU SYED KUET
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Oxidation--ABU SYED KUET
Thermal oxidation is commonly used to grow a thin layer of silicon dioxide (SiO2) on a silicon wafer. There are two main types of thermal oxidation - dry oxidation, which uses oxygen gas, and wet oxidation, which uses water vapor. Dry oxidation grows oxide slower but produces higher quality oxide with better electrical characteristics. Thermal oxidation involves heating cleaned silicon wafers to high temperatures (1000-1200°C) in an oxygen or steam environment to allow a chemical reaction that forms SiO2. The grown oxide layer serves many important functions in integrated circuits like passivation, doping masking, and as the gate dielectric in transistors.
Single crystal casting
The document discusses various methods for casting and solidifying materials, including single crystal casting techniques. Single crystal casting of turbine blades involves directional solidification where a single crystal grows longitudinally through a ceramic mold for increased strength. For microelectronics, the Czochralski method pulls a seed crystal from molten material to form long single crystal ingots. Rapid solidification involves cooling molten material at over 106 K/s to form non-crystalline metallic glasses without grain growth. Roll casting is a common rapid solidification technique where molten material is spun against a chilled roll to rapidly solidify into amorphous ribbons or sheets.
Wafer Fabrication, CZ Method--ABU SYED KUET
Crystal structures can be single crystal, polycrystalline, or amorphous. Single crystal silicon is used to manufacture solar cells and semiconductors due to its precise electronic properties. The Czochralski method is commonly used to grow large single crystal silicon ingots from melted, purified silicon in quartz crucibles. The ingots are sliced, polished, and cleaned to produce thin round wafers for semiconductor fabrication. Larger diameter wafers allow more chips to be produced from each wafer, increasing manufacturing efficiency.
Zone melting
Zone melting is a technique for purification by melt crystallization.
FLOAT ZONE MELTING
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Cements are made by mixing lime and clay, calcinating, and grinding into a fine powder which bonds through chemical hydration reactions when water is added, forming a strong structural material. Powder processing involves grinding materials into particles, pressing and sintering to densify, with sintering using heat to encourage diffusion and reduce pores without grain growth. Single crystal growth involves melting materials in a crucible and slowly extracting a seed crystal to grow a large, pure single crystal for applications such as semiconductors.
Vapor Phase Deposition Techniques
Vapor phase deposition is a technique used to prepare pure optical glasses. It involves vaporizing inorganic compounds and dopants and depositing them as thin films on a substrate through chemical reactions, forming a porous soot preform. The preform is then consolidated through heating to become a solid glass cylinder that can be drawn into an optical fiber. Common vapor deposition methods include outside vapor phase oxidation, vapor axial deposition, modified chemical vapor deposition, and plasma-activated chemical vapor deposition. These processes allow producing silica-based fibers with very low light attenuation and optimal optical properties.
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2) Wafer shaping turns the ingots into wafers using multi-wire sawing, which uses hundreds of parallel wire segments to slice through the ingot.
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Zone melting is a technique for purifying materials by melting and re-solidifying sections called zones. It was developed in the 1950s to purify germanium for transistors. Zone melting involves moving a heated zone down a rod to selectively melt and re-solidify sections, leaving impurities behind in the liquid. Multiple zone passes are needed to achieve high purity. Factors like zone size, heating rate, and stirring affect the purification process and properties of the purified material.
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The document discusses nanomaterial synthesis methods. It begins with an introduction to nanotechnology and challenges in the field. It then covers bottom-up and top-down approaches to nanomaterial synthesis. Specific synthesis methods covered include evaporation and condensation growth, lithography technology, and methods for creating nano-composites. A variety of nanoparticle synthesis techniques are also discussed.
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The IC fabrication process involves numerous steps:
1) Silicon wafers are manufactured through processes like Czochralski crystal growth and then undergo oxidation, photolithography, etching, diffusion/ion implantation, and metallization.
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On the anodic reaction of the co2 corrosion process, Iron carbonate nucleatio...
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Vapor-deposited glasses with tunable liquid crystal-like order
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Solvothermal method mithibai college msc part 1 pradeep jaiswal
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Md : Obydulla Al Mamun
Id:131-29-500
9th(B)
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Gravimetric analysis is a quantitative analytical technique where the concentration of an analyte is determined by precipitating it from solution, isolating the precipitate, and weighing it. Some key aspects of gravimetric analysis are that the precipitate must be insoluble, of known composition, and pure to minimize errors from impurities. Conditions like precipitation temperature, reagent concentrations, and digestion can be adjusted to increase particle size and purity for accurate weighing and analysis.
Gravimetry
This document discusses gravimetric analysis, which is a quantitative chemical analysis method to determine the amount of a substance by directly measuring its mass. It involves converting the substance into a pure chemical compound, then weighing it. There are several techniques used for this conversion, such as precipitation, volatilization by ignition, and electrogravimetry. Gravimetric analysis is accurate, precise, and involves direct measurement of the substance. The key steps involve isolating and weighing the pure compound, which is typically done through precipitation, filtration, washing, drying, and weighing.
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CRYSTAL GROWTH TECHNIQUES
- 1. PRESENTED BY:- SHASHI KUMAR SHAW 2K13E25 UNIVERSITY OF PUNE
- 2. Introduction Types of crystal growth Bridgeman technique CZ technique Conclusion
- 3. Silicon is a most abundant material is nature It contents many impurities Defects in crystal Single crystal is the requirement
- 4. 1. Bridgman technique 2. Czochralski technique But CZ is most preferable technique for the growth of single crystal silicon over Bridgman.
- 5. It is a very simple process System for Bridgeman :- 1. Quartz ampoule 2. Quartz boat 3. Seed crystal 4. Charges 5. Heater 6. Temperature profile
- 6. Si melt Si
- 7. Bridgman growth single crystal have a lot of dislocation
- 8. CZ is also known as “liquid solid monocomponent growth system” CZ is more complex than Bridgman Requirement for CZ:- 1. Furnace 2. Crystal pulling rate 3. Ambient control 4. Control system
- 10. L dm dt k L dT dx 1 A1 k S dT dx 2 A2 L latent heat of fusion dm dt amount of freezing per unit time kL thermal conductivity of liquid dT dx1 thermal gradient at isotherm x1 kS thermal conductivity of solid dT dx 2 thermal gradient at x 2
- 11. Reaction of O2 with single crystal silicon during growth it alters the properties of grown silicon. 95% O2 will be in interstitial sites in the crystal 5% can form a complex impurity like SiO4 (donor) If the O2 concentration > 6.4*10^17/cm3 dislocation will form in the crystal.
- 12. Bridgman crystal growth technique is simple but with serious limitation. CZ is complex process but it give good quality of single crystal than Bridgman.
- 14. THANK YOU