Photolithography is a process used in microfabrication to transfer geometric patterns to a film or substrate.April 24, 2019 Industrial Services
Photolithography is a process used in microfabrication to transfer geometric patterns to a film or substrate. The importance of lithography can be appreciated in two ways. First, due to a large number of lithography steps needed in IC manufacturing, lithography typically accounts for about 30 percent of the cost of manufacturing. Second, lithography tends to be the technical limiter for further advances in feature size reduction and thus transistor speed and silicon area. Although lithography is certainly not the only technically important and challenging process in the IC manufacturing flow, historically, advances in lithography have gated advances in IC cost and performance.
Optical lithography is basically a photographic process by which a light-sensitive polymer, called a photoresist, is exposed and developed to form three-dimensional relief images on the substrate. In general, the ideal photoresist image has the exact shape of the designed or intended pattern in the plane of the substrate, with vertical walls through the thickness of the resist. Thus, the final resist pattern is binary: Parts of the substrate are covered with resist while other parts are completely uncovered. This binary pattern is needed for pattern transfer since the parts of the substrate covered with resist will be protected from etching, ion implantation, or other pattern transfer mechanism.
The general sequence of processing steps for a typical photolithography process is as follows: substrate preparation, photoresist spin coat, prebake, exposure, post-exposure bake, development, and post-bake. Spinning the resist on the sample is done to create a uniform layer. Thus coating and baking the resist are crucial steps in a lithography process.
The main core of any lithography device is its exposure system. Because the minimum feature size that can be transferred with high fidelity to a resist film on the surface of the wafer is highly related to the wavelength of the light source. In this product, the UV lamp is used to expose the photoresist. Our company offers a product for integrating exposure system, spinner and heater in one device and enables customers to realize significantly reduced fabrication costs.