A method for reducing the number of impurity particles in metal layer sputtering process

Abstract

The invention provides a method for decreasing the number of impurity particulates in the bumping metal layer sputtering process in the semiconductor packaging field. The method comprises the steps that (1) a microwave power supply and a radio-frequency power supply are turned on, and plasma etching is carried out on the surface of a wafer and the surface of a metal pad; (2) a sputtering machine carries out metal layer sputtering on the wafer; (3) the controlled upper limit parameter of the number of the particulates is set, and the sputtering machine is halted to clear the inner wall of a plasma etching cavity once the number of the particulates exceeds the controlled upper limit parameter. The metal layer sputtering process in the step (2) comprises a normal procedure and a plasma etching clearing procedure. By adopting the technical scheme, the number of the particulates is decreased, and the service life of the plasma etching cavity is prolonged, so that the maintenance frequency is reduced, and the labor cost and material cost are lowered; the generation rate of the impurity particulates in the bumping metal layer sputtering process is decreased by 60%, and the productivity of the sputtering machine is improved by 150%.

Description

technical field [0001] The invention relates to a metal layer sputtering process in a bump process in the field of semiconductor packaging, in particular to a method for reducing the number of impurity particles in the metal layer sputtering process. Background technique [0002] The production of tin-lead and tin-silver bumps is a necessary part of advanced semiconductor packaging (FC flip-chip packaging). Sputtering of the metal layer is usually the first step in the bumping process. The process flow of metal layer sputtering is to undergo plasma etching (or dry etching) before sputtering the metal layer. The purpose is to remove the oxide layer (aluminum pad or copper pad) on the opening of the long bump ( aluminum oxide or copper oxide), otherwise the contact resistance between the sputtered metal layer and the aluminum pad (or copper pad) will be too high and cause poor electrical properties. Plasma etching is to remove a layer of the wafer surface by plasma electric ...

AI Technical Summary

Problems solved by technology

Although this method is feasible, it seriously affects the production capacity of the sputtering machine, and at the same time increases the cost of manpower and materials. It can be seen that the operation of frequently stopping operations for cleaning has become a major technical problem that limits the increase in production capacity.

[0004] Chinese patent 03123734.7 discloses a sputtering device and a method for manufacturing a metal layer / metal compound layer using the device, which can reduce the difference in temperature distribution in the reaction chamber, increase the adhesion between metal titanium and titanium nitride, and It can reduce the accumulation of titanium nitride particles; Chinese patent 200510070055.0 discloses a crystal seat design of a sputtering cleaning chamber and a method of metallization manufacturing process using the design. The method of this patent can avoid the increase of the wafer temperature and improve the aluminum The ability to add holes to metal wires; however, none of the above patents mentions the reduction in the yield of metal bumps caused by the deposition of attachments during the metal sputtering process and the method to solve this problem, let alone how to deal with frequent stoppages The large technical problem of limiting the increase in production capacity due to cleaning operations

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