Silicon is a tetravalent, gray colored, brittle chemical element. It is the most abundant element in nature, making up to 27.8% of the earth's crust. Silicon is the main component of materials like glass, cement, and bricks. All the mainstream microchips and semiconductors are built on Silicon. It is found in a variety of materials like quartz, flint, agate, etc. Silicon is a great semiconductor material which can take on dopant precisely making it good semiconductor material.
In semiconductor wafer manufacturing, silicon has to be transformed into a wafer. A silicon single crystal is a solid composed of atoms arranged in a three-dimensional pattern. This pattern extends throughout the material and process begins with the formation of the silicon ingot.
Manufacturing a Silicon semiconductor wafers.
Silicon ingot growth may require several days, from one week to approximately one month. Ingot growth depends on upon many factors including quality, size, and material specification. Czechralski (CZ) method is used for the production of more than 75% of Si wafers. CZ ingot growth requires polycrystalline silicon to be added to the starting material. These chunks are placed in a quartz crucible along with small quantities of departs. The added dopants give the desired electrical properties for the grown ingot. Depending on which dopant is used, the ingot becomes either P-type Silicon Wafers or N type.
The materials are then heated around 1420 degree Celsius of temperature, above the melting point of silicon. Now, the polycrystalline and dopant combination are liquefied and a single crystal called as seed, is positioned on top of the melt. To attain doping consistency, the seed crystal, and molten silicon is appositely rotated. Growth begins with a rapid pulling of the seed crystal to minimize the number of crystal defects. When the desired diameter is obtained, the growth conditions are stabilized to maintain the diameter. After this cooling occurs and the atom in melted orient themselves to the crystal structure.
When the ingot is grown completely a rough size diameter of the finished silicon wafer is produced. The ingot her attains a flat orientation. After passing seine inspections, the ingot is then sliced into wafers. Due to the property of hardness of silicon a diamond cutting edge saw is used to slice the wafers precisely to maintain the desired thickness level. The diamond saw helps to maintain the desired thickness level, minimize wafer damage and minimize bow and warp defects.
Finally, the semiconductor wafers are sorted and inspected under high-intensity laser-scanning systems. This removes the unwanted particles or other defects. All wafers types of wafers produced weather P-type Silicon Wafers, or N type is packaged in cassettes and sealed with tape. Then placed in an air tight foil outer bag to ensure that moisture or particles enter the cassette.
Semiconductors are crystalline solids with unique electrical properties. They offer high resistance, and their conducting properties may be altered by the deliberate adding impurities ("doping") into the crystal structure. This lowers the resistance and allows the formation of semiconductor junctions. The charge carriers include electrons and holes at the junctions of Semiconductor devices.
Semiconductor devices can display many useful properties:
- Passing current in one direction
- Showing variable resistance
- Sensitivity to light or heat
Their electrical properties are modified by doping, or by the application of electrical fields. The devices containing semiconductors are used for amplification, switching, and energy conversion.
The modern doping techniques increase the number of charge carriers within the crystal. When a doped semiconductor contains a free hole, it is called p-type, and when it contains more free electrons, it is known as the n-type semiconductor.
The semiconductor materials used in electronic devices are doped under precise conditions. This is necessary to control the concentration of their p- and the n-type dopant. A semiconductor single crystal can have many p- and n-type sections. The p-n junctions between these regions are formed of Silicon Wafer and are responsible for the electronic behavior.
Essential Properties of Semiconductor:
1. Variable conductivity:
Due to doping or gating techniques, silicon semiconductor materials behave like conducting materials. The n-type and p-type modifications are responsible for these significant outcomes. Unbalanced electrons or holes cause current to flow through Semi-Conductors.
2. Hetero-Junctions
Hetero-junctions occur when two differently doped semiconductors are joined. This results in an exchange of electrons and holes. This results in the production of the electric field.
