A method for prolonging the service life of c-direction sapphire substrate polishing fluid

Abstract

The invention relates to a method for prolonging the service life of a C-direction sapphire substrate polishing solution. The method specifically comprises the following steps: 1) in the process thatC-direction sapphire is subjected to chemical mechanical polishing, measuring potential by using a Zeta potential analyzer with a C-direction sapphire substrate polishing solution, and monitoring Zetapotential variation situations of the C-direction sapphire substrate polishing solution; 2) when monitoring that the Zeta potential of the C-direction sapphire substrate polishing solution is not greater than 20mv, directly adding a nonionic surfactant into the C-direction sapphire substrate polishing solution which is used at the moment, when a Zeta potential absolute value of the C-direction sapphire substrate polishing solution is not less than 30.0mv, stopping adding the nonionic surfactant, monitoring the Zeta potential every other 0.5-1.5 hours, and repeating the process, wherein the nonionic surfactant is one or a mixture of more of lauryl sodium sulfate, isomerism decanol polyoxyethylene ether and nonyl phenol polyoxyethylene ether. By adopting the method, the service life of thepolishing solution is remarkably prolonged for more than 12 hours, and the use cost of the polishing solution is reduced by 30% or greater.

Description

technical field [0001] The invention relates to the technical field of sapphire substrate polishing, in particular to a method for prolonging the service life of a C-directed sapphire substrate polishing solution by controlling the Zeta potential. Background technique [0002] With the development of LED substrate technology, sapphire wafers have grown from 4 inches to 6 inches or even larger. When the wafer size is 4 inches, by growing a transition layer on the ultra-smooth wafer surface (general surface roughness Ra≤0.2nm), it can overcome the Al 2 o 3 The problem of lattice mismatch during substrate growth, but with the development of wafers to 6 inches or larger, and the higher requirements for device flatness (surface roughness Ra≤0.1nm), how to reduce the surface of sapphire substrate Improving the wafer polishing rate and the service life of the polishing fluid while improving the roughness has become an urgent problem to be solved. [0003] At present, the chemica...

AI Technical Summary

Problems solved by technology

[0004] The sapphire polishing liquid uses silica sol as the abrasive. During the process of polishing C-direction sapphire substrate, the colloidal stability will gradually decrease during the use of the C-direction sapphire substrate polishing liquid. The chemical mechanical polishing process gradually reduces consumption; 2. The exothermic reaction of chemical mechanical polishing and the continuous friction and heat release between the polishing pad and the sapphire wafer under a certain pressure lead to an increase in the temperature of the polishing solution, and the increase in temperature also causes the colloidal solution to a certain extent Reduced stability

The reduction of colloidal stability directly promotes the aggregation of particles in the polishing liquid to increase the number of agglomerated large particles. The particles are agglomerated together, which reduces the effective contact area between the particle surface and the wafer surface during the polishing process, reduces the polishing efficiency, and seriously affects the polishing liquid. service life; at the same time, agglomeration of large particles may also cause scratches on the wafer surface, resulting in a decrease in yield