Integrated Circuit

Integrated circuit (IC), also known as microelectronic circuit, microchip or chip, is an assembly of electronic components manufactured as a single unit. It refers to the use of a certain process to interconnect the transistors, diodes, resistors, capacitors, inductors and other components and wires required in a circuit, and make them on a small piece or a few small pieces of ceramics, glass or semiconductor material (typically silicon).

Finally, these components are packaged together to become a tiny electronic device that can perform certain circuit functions. As a semiconductor device, ICs have received widespread attention in the semiconductor industry.

ICs are the basic building blocks of all modern electronic devices, with the advantages of small size, light weight, long life, low cost, and good performance. Besides being widely used in industry, agriculture, household appliances, ICs are also widely used in the military, science, education, communication, transportation, and finance.

For the production and replication of circuit patterns in IC chips, photolithography is the most critical technology. It uses the characteristics of photoresist to resist corrosion through photochemical reactions under light, and transfers the pattern on the mask onto the processed surface. Therefore, as a key material in photolithography, photoresist is indispensable in IC manufacturing.

How photoresist is involved in IC manufacturing?

Photoresist mainly participates in IC manufacturing through photolithography process and the specific steps of photolithography are as follows.

• Typically, the silicon wafer must be cleaned, pre-baked, and vaporized with a primer before being coated with a compound to increase photoresist adhesion.
• Through coating, a photoresist film with uniform thickness and good adhesion is formed on the surface of the silicon wafer.
• Through a series of subsequent photolithography steps, including soft baking, alignment, exposure, development, hard baking, etching or ion implantation, and photoresist removal, functional ICs are finally manufactured.

Photoresist for IC manufacturing: What are their key indicators?

In the IC process, the role of the photoresist layer is to protect the material covered by the photoresist during the etching or ion implantation process. Selected areas are then etched or ion implanted to form the circuit structure. In order to manufacture better ICs, high-performance photoresists need to be developed. The practical application performance indicators of photoresists in ICs mainly include resolution, sensitivity, etching resistance and standing wave effect.

• Resolution

As a useful performance indicator, photoresist resolution is partly related to its absorption spectrum, but is more dependent on the light source system of exposure equipment.

• Sensitivity

Sensitivity is the minimum energy that is required to generate a well-defined feature in the photoresist on the substrate. It is reflected in the contrast curve of the photoresist.

• Etching resistance

If the photoresist has strong etching resistance, the etching solution will be able to etch the exposed pattern according to the desired selection ratio and better reflect the device performance. There are two main etching resistances of photoresist in the IC manufacturing process: corrosion resistance and plasma etching resistance.

• Standing wave effect

During photolithography, the incident light and the reflected light interfere due to the reflection effect of the substrate surface, resulting in a standing wave effect occurring. For fabricating finer and smaller linewidth ICs, the standing wave effect should be reduced.

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