Plasma Enhanced ALD System

Abstract

An improved Plasma Enhanced Atomic Layer Deposition (PEALD) system and related operating methods are disclosed. A vacuum reaction chamber includes a vacuum system that separates a first outflow from the reaction chamber, comprising unreacted first precursor, from a second outflow from the reaction chamber, comprising second precursor and any reaction by products from the reaction of the second precursor with the coating surfaces. A trap, including trap material surfaces, is provided to remove first precursor from the first outflow when the first precursor reacts with the trap material surfaces. When the second precursor includes a plasma generated material, the second precursor is not passed through the trap. An alternate second precursor source injects a suitable second precursor into the trap to complete a material deposition layer onto the trap surfaces thereby preparing the trap material surfaces to react with the first precursor on the next material deposition cycle.

1 . An atomic layer deposition method comprising:
 supporting one or more substrates in a reaction chamber for a deposition run wherein the deposition run comprises performing a plurality of material deposition coating cycles;   for each deposition coating cycle—
 delivering a first precursor into the reaction chamber to react with the exposed surfaces of the one or more substrates; 
 removing a first outflow from the reaction chamber wherein the first outflow includes unreacted first precursor; 
 passing the first outflow through an ALD trap wherein the ALD trap comprises trap material surfaces suitable for reacting with the unreacted first precursor; and 
 passing an alternate second precursor through the ALD trap wherein the alternate second precursor is suitable to react with the trap material surfaces in a manner that renders the trap material surfaces able to react with and remove unreacted first precursor from the first outflow of a next coating cycle and wherein the alternate second precursor is not withdrawn from the reaction chamber. 
   
     
     
         2 . The method of  claim 1  wherein the reaction between the first precursor and the exposed surfaces of the one or more substrates occurs at a reaction temperature, further comprising the step of maintaining the trap material surfaces at the reaction temperature. 
     
     
         3 . The method of  claim 2  wherein the step of removing the first outflow from the reaction chamber comprises operating a main vacuum pump to draw the first outflow through a first vacuum conduit that includes the ALD trap. 
     
     
         4 . The method of  claim 3  further comprising:
 for each deposition coating cycle after removing the first outflow from the reaction chamber—
 delivering a second precursor comprising free radicals into the reaction chamber to react with the exposed surfaces of the one or more substrates; 
 removing a second outflow from the reaction chamber; 
 wherein the second outflow is not passed through the ALD trap. 
 
 
     
     
         5 . The method of  claim 4  wherein the step of removing a second outflow from the reaction chamber comprises operating the main vacuum pump to draw the second outflow through a second vacuum conduit. 
     
     
         6 . The method of  claim 5  wherein the step of passing the alternate second precursor through the ALD trap and delivering the second precursor comprising free radicals into the reaction chamber are performed simultaneously. 
     
     
         7 . The method of  claim 6  wherein the step of passing the alternate second precursor through the ALD trap occurs after removing the unreacted first precursor from the first outflow and before delivering the first precursor into the reaction chamber to initiate a next coating deposition cycle. 
     
     
         8 . The method of  claim 4  further comprising prior to removing the second outflow from the reaction chamber closing a first vacuum valve disposed along the first vacuum conduit between the ALD trap and the reaction chamber, opening a vacuum gate valve to provide access to remove the second outflow through a turbo molecular vacuum pump in fluid communication with a second vacuum conduit extending between the turbo molecular vacuum pump and the main vacuum pump and opening a second vacuum valve disposed along the second vacuum conduit. 
     
     
         9 . The method of  claim 4  further comprising prior to removing the first outflow from the reaction chamber closing a vacuum gate valve to prevent access to remove the first outflow through a turbo molecular vacuum pump in fluid communication with a second vacuum conduit extending between the turbo molecular vacuum pump and the main vacuum pump and closing a second vacuum valve disposed along the second vacuum conduit between the reaction chamber and the main vacuum pump. 
     
     
         10 . An atomic layer deposition cycle comprising the steps of:
 exposing exposed surfaces of one or more substrates supported in a reaction chamber to a first non-plasma precursor;   operating a main vacuum pump to withdraw a first outflow from the reaction chamber wherein the first outflow includes substantially all of the unreacted first precursor remaining in the reaction chamber;
 wherein the first outflow is drawn through a first vacuum conduit that extends between the reaction chamber and the main vacuum pump; 
 wherein an ALD trap comprising trap material surfaces reactive with the unreactive first precursor is disposed along the first vacuum conduit to remove substantially all of the unreacted first precursor from the first outflow; 
   exposing the exposed surfaces to a second, plasma excited precursor, that includes free radicals;   operating a turbo molecular vacuum pump to withdraw a second outflow from the reaction chamber wherein the second outflow purges substantially all of the second precursor from the reaction chamber;
 wherein the second outflow is drawn through the turbo molecular vacuum pump and through a second vacuum conduit that extends between the turbo molecular vacuum pump and the main vacuum pump wherein the second outflow is not drawn though the ALD trap; and 
   delivering an alternate second precursor into the ALD trap to react with the trap material surfaces,
 wherein the alternate second precursor is suitable to react with the trap material surfaces in a manner that renders the trap material surfaces able to react with and remove unreacted first precursor from the first outflow.