Etching of silicon nitride and silica deposition control in 3d nand structures

A method of etching a substrate, the method comprising:

• providing an etching solution in a tank of an etch processing system, the etch processing system configured to control temperature of the etching solution, a concentration of the etching solution, and flow of the etching solution within the tank;
• submerging a substrate in the etching solution, the substrate containing micro-fabricated structures that have alternating layers of a first material and a second material, the etching solution including an acid that etches the first material;
• initiating etching of the first material at a first etch rate, etching of the first material resulting in an etch product to be moved from the substrate;
• monitoring a concentration of the etch product within the etching solution;
• and
• in response to identifying that the concentration of the etch product falls below a predetermined value, increasing the first etch rate to a second etch rate.

A method of etching a substrate, the method comprising:

• providing an etching solution in a tank of an etch processing system, the etch processing system configured to control temperature of the etching solution, a concentration of the etching solution, and flow of the etching solution within the tank;
• submerging a substrate in the etching solution, the substrate containing micro-fabricated structures that have alternating layers of a first material and a second material, the etching solution including an acid that etches the first material;
• initiating etching of the first material at a first etch rate, etching of the first material resulting in an etch product to be moved from the substrate;
• monitoring a concentration of the etch product within the etching solution;
• and
• maintaining the concentration of the etch product within the etching solution below a predetermined value to prevent deposition of the etch product on the second material in an amount that blocks etching of the first material by the etching solution.