Stripper photoresist

It is necessary to prebake the PI film to 200°C to improve its resistance towards negative photoresist with a commercial stripper. After baking, remove the photoresist with a commercial stripper which is usually composed of phenol, strong mineral acids and solvents. 11) Neutralization and rinse. 12) final cure. Typical schedules are 30 min. at 350°C or 15 min. at 400°C. 10)PIasma,chemically etching) or physically (roughening) treat the polyimide surface to improve adhesion for next level metal. 

The last step involves the removal of the photoresist layer using chemical strippers or by volatilizing it. If the photoresist adheres too well, then it can pose a problem in its removal. 

Striptron Stripper. [Dow] Inhibited methylene chloride with additives solvent stri] for dry film photoresist and screen inks. 

Vander Mey, Phenol free and chlorinated hydrocarbon free photoresist stripper comprising surfactant and hydrotropic aromatic sulfonic acids, U.S. Patent No. 4,165,294. 

E.J. Turner, Photoresist stripper composition and process of use, World Int. Property Organiz ation. Patent Application, WO/1987/005314 (1987). 

Uses Photoresist stripper, solvent in electronics applies, incl. semiaq. 

By using photoresist as a sacrificial layer or structure, further processes, etching, ion implantation, molding, lift-off, and so on, may be performed. When patterned photoresist finish its roles, it is better to be removed from substrate. There are two kinds of methods to remove photoresist layer, wet type and dry type. Wet type photoresist removal process requires the chemical, PR remover or PR stripper, which can dissolve photoresist. Alternatively, plasma ashing process may remove photoresist This process is called dry process and uses oxygen plasma which oxidizes photoresist layer. 

Two masks were prepared to define the nichrome and gold patterns. Using standard photolithography, the Au leads and contact patterns were formed in a photoresist layer. The residual gold was removed with a solution of 4 g KI 1 g I2 40 mL H2O. The KI-I2 solution was chosen because it etches the gold film but not the NiCr. The photoresist was then removed using photoresist stripper and rinsed in DI water. 

This is well known in the semiconductor industry. It is necessary to heat silicon wafers to about 230 C to get rapid oxidative removal of photoresist in down-stream strippers. In this equipment there is a high concentration (10% or more) of ground state O at the wafer but there are no ions or VUV. The stripping rate follows a typical first order Arrhenius reaction. 

For positive photoresists, the UV light does not penetrate deeply into the film causing no change to the solubility of the photoresist deep in the layer (Ottow et al. 1996). Unexposed positive resist is not removed by developer. It can be removed by a stripper or solvent, but this also removes the patterned photoresist layer. This restricts processes to only thin PS films or requires long exposure times which leads to poor feature resolution. 

N-Methyi-2-Pyrroiidone Alcohols, glycol ethers, ketones, and aromatic/chlorinated hydrocarbons (surfactants) Photoresist stripper, defluxing, graffiti remover... 

Nonaqueous Waste Resists. One of the most exciting waste minimization techniques currently being tested is the elimination of the need for rinsing from both photoresist developing and stripping operations. This new process may eliminate spent developer wastes and wiU eliminate the spent resist stripper bath dnmp. 

The exposure potential from the use of NMP in paint stripping is completely different from its use in semiconductor processing as a photoresist stripper. In fab use, NMP is isolated from the fab worker in processing equipment that is a closed system. The low vapor pressure of NMP (0.342 mm Hg at 25°C) limits the saturated vapor concentration to about 450 ppm at room temperature. It has been reported that hydrolysis in air at relative humidities of 40-60% (a typical level found in a semiconductor fab area) can reduce maximum concentrations to approximately 130 ppm.1 1 The potential inhalation exposure hazard is low, but NMP is readily absorbed through the skin, and repeated or prolonged skin contact with the liquid can cause severe dermatitis. 

Sato, M. Dry-film photoresists formulated based on expected swelling of their patterns in developers or in strippers. Jpn. Kokai Xokkyo Koho JP 2006292889, 2006 Chem. Abstr. 2006, 145, 446293. 

High concentrations of ozone (10-20%) are attained in ozone strippers. In these machines, ozone is created in a corona or arc discharge at atmospheric pressure. These strippers are used in the semiconductor industry to remove photoresists at rates of up to one micron per minute in a chamber heated to 300°C. It has been shown that UV assists in the stripping operation perhaps by forming radical sites in the resist. 

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