Preparation method of high-concentration Ti barrier layer surface chemically-mechanical polishing solution

Abstract

The invention discloses a preparation method of a high-concentration Ti barrier layer surface chemically-mechanical polishing solution, aiming at providing a method for preparing the high-concentration Ti barrier layer surface chemically-mechanical polishing solution by using a non-metal reactor and adopting negative pressure vortex stirring to prevent the gelation or the dissolution of silica sol and enhance the purity of the high-concentration Ti barrier layer surface chemically-mechanical polishing solution. The preparation method comprises the following steps of: cleaning a transparent closed reaction kettle and a feed pipeline by using ultrapure water with resistance more than 18 megohms; vacuumizing the transparent closed reaction kettle, and sucking an alkalic pH value regulator into the transparent closed reaction kettle under the action of negative pressure to form complete vortex stirring; sucking a non-ionic surface active agent into a solution under the action of the negative pressure while carrying out the complete vortex stirring, and sucking an FA / OII type chelator into the solution under the action of the negative pressure while carrying out the complete vortex stirring; and sucking the silica sol into the solution under the action of the negative pressure while carrying out the complete vortex stirring, and uniformly carrying out the complete vortex stirring to obtain the polishing solution with the pH value of 9-11.

Description

technical field [0001] The invention relates to a preparation method of a polishing liquid, in particular to a preparation method of a high-concentration Ti barrier layer surface chemical mechanical polishing liquid. Background technique [0002] The metal usually used as a barrier layer is a type of metal with a high melting point, such as titanium Ti, tungsten W, tantalum Ta, molybdenum MO, cobalt Co, platinum Pt, etc. Titanium tungsten (TiW) and titanium nitride (TiN) are two A commonly used barrier layer material, TiN induces excellent barrier properties during Al alloy interconnect processing and is widely used in the fabrication of very large scale integrated circuits. At the same time, TiN is often used as an anti-reflection layer for the AL layer. The disadvantage of TiN is that the contact resistance between TiN and silicon is relatively large. To solve this problem, a thin layer of titanium ( Typical thicknesses are tens of nanometers or less). This layer of tita...

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Problems solved by technology

After the resulting polishing solution is filtered, the yield rate further drops significantly

Secondly, the open mechanical stirring method and preparation equipment contain organic matter, metal ions, large particles and other harmful components, which will inevitably enter the polishing liquid during the stirring process. The prepared polishing liquid usually contains metal ions on the order of several ppm Above, it is impossible to prepare high-purity polishing liquid, resulting in the increase of cost in subsequent processing and the reduction of device yield

Especially when the contamination concentration of strong electrolyte metal ions such as sodium ions is too high, the silica sol will gel, causing the polishing fluid to be scrapped

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