What are the eight steps involved in manufacturing semiconductors?

The word semiconductor might sound complicated and distant,wafer prober but semiconductors are already infiltrating every aspect of our lives: from smartphones and laptops to credit cards and subways, semiconductors are everywhere.

The manufacturing of semiconductor technology products in each country needs to go through hundreds of processes,probe test and the entire manufacturing development process in China can be broken down into the eight following steps: wafer processing - oxidation - lithography - etching - thin film deposition - interconnect - testing - packaging.

Taking the first step

Wafer processing

Essentially, semiconductor technology all begins with a grain of sand!wafer probing Silicon is the raw material needed to make wafers. A wafer is a round sheet cut from a silicon (Si) or gallium arsenide (GaAs) single crystal column. Among the raw materials used to fabricate wafers is silica sand, which contains up to 95 percent silica. Wafer fabrication refers to the process of creating and obtaining wafers.

One ingot is cast

The sand is first heated and the carbon monoxide and silicon are extracted and assessed. This process is then carried out multiple times until the desired outcome of ultra-high purity electronic grade silicon (EG-Si) is attained. The purified silicon is then melted and solidified into a single-crystal structure called an "ingot". This critical stage forms the basis for semiconductor material production in China. Producing silicon ingots, also known as silicon columns, necessitates meticulousness at the nanometer level and is typically achieved using the pull method.

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Two ingots are cut

Once the design for the crucial preliminary step is complete, the diamond saw will trim both ends of the ingot. The resulting sheet will then be sliced to a predetermined thickness. The diameter of the ingot wafer dictates its dimensions and allows for larger and thinner wafers to be divided into more units, ultimately leading to cost savings in production and management for businesses. In order to maintain compliance with national standards during future research stages, a "flat area" or "dent" mark must be included on the silicon wafer post-cutting.

Wafer surface polishing

Through the above cutting process, a thin sheet is obtained called a "bare chip", that is, the raw wafer. The surface of a bare wafer is uneven, which prevents circuit graphics from being printed directly on it. To obtain a clean wafer, surface defects must be removed by grinding and chemical etching, smooth surfaces must be formed by polishing, and residual contaminants must be removed by cleaning.

The second step

The inflammation process

In oxidation, a protective film forms on the wafer's surface. This film protects the wafer from chemical impurities, prevents leakage current, prevents diffusion during ion implantation, and prevents sliding during etching.

The first step of oxidation is to get rid of impurities and contaminants, which is done through a four-step procedure involving the elimination of organic matter, metals, and residual water evaporation. Once this cleansing step is completed, the wafer can withstand high temperatures ranging from 800 to 1,200 degrees Celsius. This exposure to heat triggers a reaction between oxygen or steam and the surface of the wafer, resulting in the creation of an oxide layer called "silica." As oxygen travels through this layer, it combines with silicon to create an oxide layer of various thicknesses. These thicknesses can then be measured after oxidation has taken place.

Dry and wet oxidation

The thermal oxidation process can be divided into dry oxidation and wet oxidation depending on the different oxidants used in the oxidation reaction. In the first, pure oxygen is used to create a silica layer, which is slow, but the oxide layer is thin and dense, while in the second, oxygen and water vapor are used with high solubility, resulting in rapid growth, but thin protective layers and low density.

In addition to the oxidant, the thickness of the silica layer is affected by several other factors. These include the structure analysis of the wafer, any defects on its surface, and variations in internal doping levels. Moreover, the rate of oxide layer formation using oxidation technology equipment is greatly influenced by pressure and temperature. To ensure accurate results, false wafers are employed during this process to safeguard against discrepancies caused by their placement in the unit.

The third step

Photo-etching

As a semiconductor manufacturing process, photolithography involves printing circuit patterns on wafers with light, which can be viewed as drawing plans on wafer surfaces. When the circuit pattern is more precise, advanced lithography technology must be used, as this will result in greater integration on the finished chip. A photoresist coating, exposure, and development are the three stages involved in lithography.

Coated with photoresist

The first step in drawing a circuit on a wafer is to apply photoresist to the oxide layer. In this step, you can apply a thin layer of photoresist to the wafer surface to achieve a more uniform coating and finer pattern, as it changes the chemical properties of the wafer to turn it into "photo paper."

A positive photoresist decomposes after light, leaving a pattern of the unexposed area, whereas a negative photoresist merges after light, leaving an image of the exposed area.

The second exposure

Once the wafer is covered with a photoresist film, circuit printing can be completed by controlling the light. In this process, light is selectively passed through the exposure device, and when it passes through the mask plate containing the circuit pattern, a photoresist film is applied to the chip to print the circuit pattern.

By improving the quality of the print pattern during exposure, the final chip is able to accommodate more components at the same time, thus improving the efficiency of social production management and reducing component costs for enterprises. Due to its new technology, EUV lithography has gained worldwide attention in this field.

The third development

To display the printed circuit pattern after exposure, a developer is sprayed on the wafer to remove the photoresist from the uncoated areas of the wafer. After the development process is complete, various measuring instruments and optical microscopes need to be checked in order to ensure that the circuit diagram is of high quality.

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The fourth step is etching

The circuit diagram is photoetched onto the wafer, and excess oxide film is removed through an etching process using liquid, gas, or plasma.

Etching research can mainly be divided into two categories depending on the substance used: wet etching, which uses a specific chemical solution for an analytical chemical reaction to remove oxide films, and dry etching, which uses various gases or plasmas.