Apparatus and process for atomic or molecular layer deposition onto particles during pneumatic transport

Abstract

The invention provides a process for depositing a coating onto particles being pneumatically transported in a tube. The process comprising the steps of providing a tube having an inlet opening and an outlet opening; feeding a carrier gas entraining particles into the tube at or near the inlet opening of the tube to create a particle flow through the tube; and injecting a first self-terminating reactant into the tube via at least one injection point downstream from the inlet opening of the tube for reaction with the particles in the particle flow. The process is suitable for atomic layer deposition and molecular layer deposition. An apparatus for carrying out the process is also disclosed.

What is claimed is: 
     
         1 . An apparatus comprising:
 (i) a tube having an inlet opening and an outlet opening;   (ii) a feeder device for feeding a carrier gas entraining the particles into the tube, thereby pneumatically transporting the particles in the tube; and   (iii) a plurality of injection points downstream from the inlet opening, for introducing two or more different reactants via different injections points of the plurality of injections points into the tube, for atomic or molecular layer deposition on the particles.   
     
     
         2 . An apparatus of  claim 1 , wherein the tube is coiled. 
     
     
         3 . The apparatus of  claim 1 , wherein the apparatus comprises a plurality of injection points spaced apart along at least a portion of the length of the tube. 
     
     
         4 . The apparatus of  claim 2 , wherein the apparatus comprises a plurality of injection points at folds of the tube. 
     
     
         5 . The apparatus of  claim 1 , wherein the tube is provided with a plurality of injection points numbered sequentially from the inlet opening of the tube; wherein odd-numbered injection points are arranged for injection of a first self-terminating reactant; and even-numbered injection points are arranged for injection of a second self-terminating reactant. 
     
     
         6 . The apparatus of  claim 1 , further comprising one or more flush points along at least part of the length of the tube for removing reaction by-products from the tube. 
     
     
         7 . The apparatus of  claim 6 , further comprising one or more flush points at folds of the tube. 
     
     
         8 . The apparatus of  claim 1 , wherein the apparatus is further configured to increase a linear velocity of the carrier gas downstream from the one or more flush points. 
     
     
         9 . The apparatus of  claim 6 , wherein one or more flush points comprise a filter to allow reaction products to be removed while keeping the particles in the tube. 
     
     
         10 . The apparatus of  claim 1 , wherein the tube has an internal diameter in the range of from 0.02 mm to 300 mm. 
     
     
         11 . The apparatus of  claim 1 , wherein the tube has a length of from 0.1 m to 500 m, and wherein the tube is folded or coiled. 
     
     
         12 . The apparatus of  claim 1 , wherein the tube is contained in a chamber provided with means for heating and/or means for cooling, wherein the chamber can be kept at a temperature in the range of from 0° C. to 1000° C., wherein different parts of the tube can be kept at different temperatures, wherein the tube is provided with a plurality of injection points numbered sequentially from the inlet opening of the tube; wherein odd-numbered injection points are arranged for injection of a first self-terminating reactant; and even-numbered injection points are arranged for injection of a second self-terminating reactant, and wherein tube segments downstream from odd-numbered injection points and upstream to even-numbered injection points are arranged to be kept at a first temperature, and tube segments downstream from even-numbered injection points and upstream to odd-numbered injection points are arranged to be kept at a second temperature.