Deterministic feedback blender

Abstract

Methods and systems for high precision, continuous blending of mixtures, and particularly mixtures having at least two distinct chemical components, are disclosed. More particularly, the disclosed methods and systems provide high precision, continuous blending of buffered oxide etch mixtures containing water, ammonium fluoride, and hydrofluoric acid.

We claim: 
     
         1 . An inline blending method of components that alter each other's assays, the method comprising:
 a. mixing Component A, Component B, and a solvent in an inline blender to form a mixture;   b. analyzing the mixture downstream of the inline blender to determine a concentration of Component A and a concentration of Component B;   c. maintaining a target concentration in the mixture of Component A within 0.008% w/w and maintaining a target concentration in the mixture of Component B within 0.22% w/w by adjusting a flow rate of Component A, Component B, and/or the solvent based on the concentration of Component A and the concentration of Component B.   
     
     
         2 . The inline blending method of  claim 1 , wherein the solvent is ultra purified water. 
     
     
         3 . The inline blending method of  claim 2 , wherein Component A comprises species that affect the concentration of Component B. 
     
     
         4 . The inline blending method of  claim 2 , wherein Component B comprises species that affect the concentration of Component A. 
     
     
         5 . The inline blending method of  claim 4 , wherein Component A is HF and Component B is NH 4 F. 
     
     
         6 . The inline blending method of  claim 2 , wherein Component A is NH 4 OH and Component B is H 2 O 2 . 
     
     
         7 . The inline blending method of  claim 2 , wherein Component A is HCl and Component B is H 2 O 2 . 
     
     
         8 . The inline blending method of  claim 2 , wherein Component A is H 2 SO 4  and Component B is H 2 O 2 . 
     
     
         9 . A method of mixing chemical fluids in an inline blender to produce a mixture having a concentration of the chemical fluids within 0.22% w/w of a target concentration, the method comprising:
 a. introducing a first chemical fluid into an inline blender via a first flow control device;   b. introducing a second chemical fluid into the inline blender via a second flow control device;   c. introducing a third chemical fluid into the inline blender via a third flow control device;   d. mixing the first chemical fluid, the second chemical fluid, and the third chemical fluid in a mixing zone of the inline blender to form a mixture;   e. monitoring the mixture downstream from the mixing zone for a first chemical fluid concentration and a second chemical fluid concentration;   f. adjusting the first flow control device based on the first chemical fluid concentration; and   g. adjusting the second flow control device based on the second chemical fluid concentration.   
     
     
         10 . The method of  claim 9 , wherein the first flow control device, the second flow control device, and the third flow control device is an orifice, a flow control valve, a stepper throttle, or combinations thereof. 
     
     
         11 . The method of  claim 9 , wherein the mixing zone is a tube or a pipe having an unrestricted flow path. 
     
     
         12 . The method of  claim 9 , wherein the mixing zone comprises an element to induce mixing. 
     
     
         13 . The method of  claim 12 , wherein the element to induce mixing is a static mixer, a stirrer, a vortex element, or combinations thereof. 
     
     
         14 . The method of  claim 9 , wherein the first chemical fluid concentration and the second chemical fluid concentration are monitored by combinations of a conductivity meter, a pH meter, a refractometer, a turbidity monitor, a Raman spectrometer, an infrared spectrometer, a UV/VIS spectrometer, a densitometer, an ultra-sonic meter, and a particle counter. 
     
     
         15 . The method of  claim 9 , wherein the first chemical fluid and the second chemical fluid are not water. 
     
     
         16 . The method of  claim 9 , wherein the first chemical fluid is H 2 SO 4 , HF, NH 4 OH, or HCl. 
     
     
         17 . The method of  claim 9 , wherein the second chemical fluid is H 2 O 2  or NH 4 F. 
     
     
         18 . The method of  claim 1 , wherein the third chemical fluid is water. 
     
     
         19 . The method of  claim 9 , wherein the first chemical fluid comprises ions that affect the second chemical fluid concentration. 
     
     
         20 . The method of  claim 9 , wherein the second chemical fluid comprises ions that affect the first chemical fluid concentration.