Technical Aspects Of Semiconductor Wafer Manufacturing

Whenever people look at electronic items, they usually come across integrated circuits which are imperative to the workings of the various gadgets. A wafer, also known as a substrate or slice is a slice of semiconductor material that used to fabricate integrated photovoltaics and circuits for traditional, solar cells that are water-based.

Materials used to make Semiconductor Wafers
Typically, wafers are made using pure silicon grown into monocrystalline cylindrical ingots (boules) up to 300 into in diameter. That is when you use the Czochralski process. A point to note is that wafers are usually in rods that are in specific diameters. The silicon used for making wafers is often derived from sand. Some of the attributes if silicon that make it ideal for this job is that is readily available and environmentally friendly as well.

Manufacturing Process of Semiconductor Wafers

The Process
The steps in semiconductor wafer manufacturing are divided into four categories namely deposition, removal, patterning as well as modification.

Deposition
This is the process of growing, coating or transferring materials onto a wafer. The available technologies for this include electrochemical deposition ([CD), chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD) molecular beam epitaxy (MBE).

Removal
This is the process of removing materials from the silicon wafer, and this includes etch processes which may be dry or wet as well as the chemical-mechanical planarization (CMP).

Patterning
This entails the altering or shaping of the deposited materials and is normally referred to as lithography. In traditional lithography, a chemical called photoresist is used for coating the wafer and a machine known as a stepper is used to focus, align and move a mask. This helps to expose some parts of the wafers to short wavelength light. The exposed parts are simply washed away using a developer solution. A plasma ashing will be used to remove any remaining photoresist after the process of etching or any other similar process.

Modification
Historically, the process of modifying electrical properties involved doping transistor drains and sources (originally through diffusion furnaces and ion implantation). Furnace annealing comes after these doping processes. If the device is advanced, the rapid thermal annealing will follow the doping processes (RTA). Annealing activates the dopants which are implanted. Modifying electrical properties also extends to reducing the dielectric constant in materials found in low-k insulators through the introduction of ultraviolet light in UV processing (UVP).Modern chips have about eleven levels of metals that are produced in more than 300 processing steps that are sequenced.

Building foundation for Wafers (Wafers)
After extracting silicon from the sand, it undergoes a purification process that entails heating it until it becomes a high-purity liquid. It then solidifies into an ingot through methods such as the Floating zone process or Czochralski (chokh-RAL-skee).The latter method makes use of a tiny piece of well done solid silicon that is put in polycrystalline or molten silicon and brought in a rotation. This is done as the liquid becomes a cylindrical ingot. This is the reason why the complete wafers have round disc shapes.

Wafer Thin
Before it completely cools down, the ends of the ingot which are cone-shaped are then cut off as the body of the silicon is cut into gaunt wafers. At this point, the wafers have a uniform thickness and entail diamond sharp saw blades. This is the reason why the diameter of the ingot determines the wafers size. Previously, the manufacturers had only three-inch diameters. Things have since changed as diameters are increasing in size because there are now larger wafers. People who have larger wafers enjoy higher productivity and more chips. At the moment, the biggest diameter in the semiconductor industry is 300mm or 12 inches.

Polishing and Lapping
You should prep sliced wafers first to ensure they are production-ready. One way of doing this is to polish them, and you can do this using abrasive machines and chemicals on the uneven surfaces for a mirror —smooth finish. A flawless surface will allow circuit patterns to form well on the surface of the wafer during the process of lithography.

Parts of a Semiconductor Wafer

Chip
This entails a small silicon piece with some electronic patterns.
Scribe Lines
These are non-functional, thin spaces found between functional pieces that allow a saw to safely cut your wafer without having to damage the circuits.
TEG
(Test Element Group) is an elaborate prototype that shows the real chip characteristics (transistors, circuits, capacitors, diodes and resistors) to make it easier to know if they were working as expected.
Edge Die
The chips (dies) found at the wafer edge is commonly seen as a production loss. Normally, larger wafers would have fairly less loss of chips.
Flat Zone
The flat zone at the end of the wafer is cut off and that is to aid in identifying the type and orientation of the wafer.