Semiconductor wafer cleaning system

An improved method for cleaning semiconductor wafers using a concentration of active cleaning components which is less than that used in conventional RCA cleaning techniques, comprising the steps of:

• positioning one or more wafers in a cleaning tank;
• cleaning said wafers by sequentially introducing one or more diluted cleaning solutions into said tank, each of said cleaning solutions comprising an active component selected from the group consisting of ammonium hydroxide, hydrogen peroxide, and hydrochloric acid, wherein the active component of each of the solutions is diluted with deionized water at ratios greater than 200 to 1;
• allowing said one or more diluted cleaning solutions to flow out of the tank at a level above the wafers in said solutions;
• dumping each of said solutions after said solutions have been introduced into said tank and allowed to flow out of the tank;
• rinsing said wafers with deionized rinsing water after said solutions have been dumped;
• flowing clean deionized water through the tank;
• and
• applying megasonic energy to the solutions or water in the tank when said solutions or water are in the tank.

An improved method for cleaning semiconductor wafers using a concentration of H.sub.2 O.sub.2 and NH.sub.4 OH which is less than that used in conventional RCA cleaning techniques, comprising the steps of:

• positioning one or more wafers in a cleaning tank having a volume of about 16 liters;
• flowing hot deionized water into a lower portion of the tank at a rate of about 16 liters per minute for about a minute and a half, allowing said hot deionized water to overflow an upper portion of the tank to carry contaminants out of the tank;
• simultaneously with introducing water into the tank, injecting a dilute surfactant into the tank for about one minute at a rate to dilute further the surfactant with the deionized water flowing into the tank;
• simultaneously with introducing said hot deionized water and said surfactant, injecting into the tank ammonium hydroxide for about a minute and a half at a flow rate of about 50 cc/min;
• injecting hydrogen peroxide into the tank for about 25 seconds after injecting the ammonium hydroxide at a flow rate of about 100 cc/min,
• whereby a cleaning solution comprising H.sub.2 O, H.sub.2 O.sub.2, and NH.sub.4 OH in a ratio of approximately 300:2:1 is produced in said tank.

A method of cleaning semiconductor wafers comprising:

• in a first cleaning cycle, applying a cleaning solution to said wafers in a tank while applying megasonic energy to the solution to remove organic residues and particles from said wafers;
• in a second cleaning cycle, introducing a diluted hydrofluoric acid solution to said wafers to strip oxide and remove metals from said wafers and rinsing the acid solution from the wafers and the tank;
• and
• in a first step of a third cycle, introducing a third solution to the tank by flowing at a high rate cold deionized water through the tank while injecting H.sub.2 O.sub.2 and surfactant into said cold deionized water and allowing the solutions to overflow.

An improved method of cleaning semiconductor wafers using a concentration of ammonium hydroxide and hydrogen peroxide which is less than that used in conventional RCA cleaning techniques, comprising:

• positioning one or more wafers in a tank flowing deionized water into the tank at a high flow rate and allowing it to overflow an upper portion of the tank;
• injecting surfactant into the deionized water flowing into the tank;
• injecting hydrogen peroxide into the deionized water flowing into the tank, wherein the ratio of hydrogen peroxide to the deionized water is about one part hydrogen peroxide to about 200-400 parts deionized water;
• and
• stopping the high flow rate of deionized water into the tank, while permitting a low flow rate of deionized water into the tank to allow some overflow of contaminants at the upper portion of the tank.

An improved method for cleaning semiconductor wafers using a concentration of ammonium hydroxide and hydrogen peroxide which is less than that used in conventional RCA cleaning techniques, comprising:

• positioning one or more wafers in a cleaning tank, said tank having walls;
• cleaning the wafers by filling the tank with a dilute cleaning solution
• comprising one part ammonium hydroxide, two parts hydrogen peroxide and about 300-600 parts deionized water;
• and
• applying megasonic energy to the cleaning solution in the tank.