How to make semiconductor chip
1. Cleanup
The silicon wafers that serve as the semiconductor's foundation are cleaned. Defects in the circuit might result from even the smallest amount of wafer contamination. In order to eliminate all contaminants, including ultra-fine particles, minuscule amounts of organic or metallic residues produced during manufacture, and undesired natural oxide layers produced as a result of contact to air, chemical agents are used.
2. The Deposit of Film
On the wafer, thin film layers of metals like as silicon oxide, aluminum, and others that will be used as circuit materials are created. There are several methods for forming these thin films, including "sputtering," which involves bombarding a target material, such as aluminum or another metal, with ions, which knocks off atoms and molecules that are then deposited on the wafer surface, "electrodeposition," which is used to form copper wire layers (copper interconnect), and chemical vapor deposition (CVD), which involves mixing special gases to cause a chemical reaction that produces a vapor containing the desired material.
3. Cleaning After Deposition
Brushes or Nanospray with deionized water, or other physical cleaning procedures, are used to remove minute particles sticking to the wafer following film deposition.
4. Coating Resistant
The resist is applied on the wafer surface (photosensitive chemical). The wafer is then spun, producing centrifugal force to generate a homogeneous layer of resist on the wafer surface.
5. Exposed
The wafer is subjected with short wavelength deep ultraviolet light projected through a mask that contains the circuit pattern. Only the portions of the resist layer that are exposed to light undergo structural change, allowing the pattern to be transferred to the wafer. Steppers, which expose numerous chips at once, and scanners, which expose the wafer using a slit through which light is transmitted onto the wafer, are two types of exposure units.
6. Development
The wafer is sprayed with developer, which dissolves the portions exposed to light and reveals the thin coating on the wafer surface. The remaining resist portions that are not exposed at this time serve as the mask for the subsequent etching process, and the resist pattern becomes the pattern on the layer below.
7. Etching
Wet etching dissolves and removes the exposed thin coating on the surface layer using chemicals such as hydrofluoric acid or phosphoric acid. This creates the pattern. There is also a dry etching process that involves bombarding the wafer surface with ionized atoms to remove the film layer.
8. Impurity Implantation
Impurities such as phosphor or boron ions are implanted in wafers to give the silicon substrate semiconducting characteristics.
9. Activation
To activate the doped ions deposited in the wafer, heat processing is performed using flash lamps or laser radiation. The tiny transistors on the substrate require instantaneous activation.
10. Resist Stripping
WResist can be stripped off in a wet station, which employs chemicals to remove the resist, or by ashing, which utilizes gases to induce a chemical reaction that removes the resist.
Following the ashing, the wafer is cleaned.
11. Assembly
The wafer is divided into individual chips (dicing), and the chips are wire-bonded to a metal frame called a lead frame. The wafer is then enclosed in epoxy resin material (packaging).
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