Structure of Photoresist
Optical photoresist usually comprises the following three components:
(1) polymeric material (also referred to as a resin). The polymer material does not chemically react under the irradiation of light, and its main function is to ensure the adhesion and corrosion resistance of the photoresist film, and also determine other characteristics of the photoresist film (such as photoresist film). Thick requirements, elasticity requirements and thermal stability requirements, etc.).
(2) photosensitive material. Photosensitive materials are generally a composite substance (referred to as PAC or photoresist). The sensitizer will chemically react after being irradiated. The positive gluing sensitive agent inhibits dissolution in the unexposed region, and can slow down the dissolution speed in the developer. Taking a positive glue as an example, the positive glue in the G-ray and I ray photolithography is made of a diazine (referred to as DQ) sensitizer and phenol resin.
(3) Solvent (such as propylene glycol-methyl ether, PGME). The action of the solvent is to keep the photoresist to be liquid before coating the surface of the silicon wafer.
Characteristics Characterization
Characterization of the characteristics and performance of the photoresist, the quality parameters have the following three:
(1) Optical properties. The optical properties of the photoresist include photosensitivity and refractive index. Mechanical properties and chemical properties of
(2). The mechanical properties and chemical properties of photoresist include the solid solution, viscosity, adhesion, resistance (etching, corrosion), thermal stability, fluidity, and environmental atmosphere (such as oxygen). .
(3) Other features. Other characteristics of the photoresist include the purity of the glue, the metal content of the glue, the applicable range of the glue, the storing of the gel and the glue of the glue.
Metal peeling technique of positive photoresist
The metal stripping process of positive glue is shown to obtain a thin lighting pattern of the hard-corrosive metal than conventional photoresist masking. Superiority. This paper first compares the performance of the positive and negative photoresist in the metal stripping process. It is believed that the positive photoresist is highly resolution, which is adapted to a mask of fine graphics. It also has a graphical edge steep, and the unique properties such as depletion, which is more advantageous for metal stripping processes than the negative photoresist. The specific process conditions are then given, and the key points in the process are pointed out in accordance with the characteristics of the positive photoresist. If the adhesion of the GaAs surface is poor, this requires more stringent cleaning treatment on the surface of the film. In order to highlight the drift and accurately controlling the dimensions of the lithography pattern, strict requirements are proposed in particular in particular developing liquid temperature. Since the process is substantially unlike the corrosion process, the corrosion resistance of the film has dropped to the secondary position.
Operation process
(1) Synthesis of cresol resin. The raw material mixture and formaldehyde were given a stainless steel kettle, adding an appropriate amount of oxalic acid as a catalyst, heating reflux reaction for 5 to 6 h, then evaporamine removal of water and unreacted monomer phenol to give a cresol resin.
(2) Synthetic photosensitive agent. In the jacket reaction tank equipped with a stirrer, trihydroxybenzophenone and 215 acid chloride were first dissolved under acetone. After the completion of complete dissolution, the organic base solution was added to the catalyst, and the reaction temperature was 30 to 35. At ° C, after the dropwise addition, the reaction was continued for 1 h. The reaction liquid was tied to water, and the sensitizer was separated, centrifuged, dried.
(3) with glue. The synthetic resin, the sensitizer and the solvent and the additive are mixed with a proportion of glue, and then the indicators of the adhesive are adjusted to meet the requirements. Finally filtration, photoresist first passed through the plate frame filter, then transferred into the ultimate room (100) for ultra-clean filtration, filter aperture 0.2mm, and ultra-net filtration collapsed. Finished product.