Wet cleaning

1. Improved RCA cleaning method

RCA cleaning method has become the basis of a variety of FREOL cleaning process, most manufacturers use the improved RCA method at present. The original RCA method depend on the solvent, acid, surfactant and water, in the case of without damaging the surface of the wafer features injection, purification, oxidation and etching and dissolved contaminants on the surface of the wafer, organic compounds and metal ions pollution. And improved RCA method by adding surfactants and HF, and USES the dilution RCA process to improve the cleaning effect.

2. Diluted chemical method

On the basis of the improved RCA cleaning method, standard cleaning fluid SC for 1-2-1 and 2 standard cleaning fluid SC mixed solvent dilution chemical method, not only can save lots of chemical reagents and deionized water, and SC - 2 the H2O2 in the mixed solvent can completely cleared away. Dilute the APM SC-2 mixed solvent (1:1:50) can effectively from the chip surface to remove particles and hydrocarbons, strongly diluted HPM mixed solution (1:1:6 0) and dilute hydrochloric acid (1:100) in the removal of metal can like SC - 2 effective as solvent. With dilute hydrochloric acid (HCL) solution of another advantage is that under the low concentration of HCL precipitation particles will not, because the pH within 2 ~ 2.5 silicon and silicon oxide is equipotential, pH value is higher than that point, the surface of the wafer with a net negative charge; Below that point, the surface of the wafer with a net positive charge. That when pH > 2 ~ 2.5, the solution of both particles and silicon surface with the same charge, electrostatic shielding, formed between particles and silicon surface of silicon was blocked during soaking in solution and prevent particle deposition from solution to the silicon surface. But when pH < 2, silicon surface is positively charged, and the particles with negative charge, so that it does not have shielding effect. Thus effectively control the concentration of HCL, can prevent particle deposition in the solution to the surface of a wafer.

3. The single wafer cleaning method

Because of the large diameter wafer cleaning is not easy to complete the cleaning process, the above methods usually adopts single wafer cleaning method. Cleaning process is repeated use of DI - O 3 at room temperature and dilute hydrofluoric acid (DHF) cleaning fluid, DI water (DI H2O - O3) produce silicon oxide, dilute DHF etching silicon oxide, removal of particles and metal pollutants at the same time. According to the demand of etching and oxidation can be obtained with shorter spray time good cleaning effect, and cross contamination does not occur. The final rinse DI H2O can be used, can also be the DI H2O - O3. In order to avoid water damage, enrichment can be used a large amount of nitrogen isopropyl alcohol (IPA) for dry processing. Single wafer cleaning is better than the improved RCA cleaning method, the effect of cleaning process usually recycling DI H2O and DHF, in order to reduce the consumption of chemicals, at the same time improve the cost effectiveness of wafer.