Methods and devices to reduce defects in dielectric stack structures

Abstract

A variety of techniques may be employed alone or in combination to reduce the incidence of defects arising in dielectric stack structures formed by chemical vapor deposition (CVD). Incidence of a first defect type attributable to reaction between an unreacted species of a prior CVD step and reactants of a subsequent CVD step, is reduced by exposing a freshly-deposited dielectric layer to a plasma before any additional layers are deposited. Incidence of a second defect type attributable to the presence of incompletely vaporized CVD liquid precursor material, is reduced by exposing the freshly-deposited dielectric layer to a plasma, and/or by continuing the flow of carrier gas through an injection valve for a period beyond the conclusion of the CVD step.

1 - 7 . (canceled) 
   
   
       8 . A method of reducing incidences of defects in a stack of dielectric layers, the method comprising:
 depositing a first dielectric layer by chemical vapor deposition;   exposing the freshly deposited dielectric layer to a plasma generated in a chemically reactive gas to remove from a surface-of the freshly deposited dielectric layer at least one of an incompletely vaporized liquid precursor material and an incompletely reacted material; and   depositing a second dielectric layer over the first dielectric layer following exposure of the freshly deposited dielectric layer to the plasma.   
   
   
       9 . The method of  claim 8  wherein the chemically reactant gas comprises a gas utilized during deposition of the first dielectric layer. 
   
   
       10 . The method of  claim 8  wherein the plasma is already present in a processing chamber as a result of deposition of the first dielectric layer. 
   
   
       11 . The method of  claim 8  wherein the plasma is introduced into a processing chamber after completion of deposition of the first layer. 
   
   
       12 . The method of  claim 8  wherein the plasma is introduced by generation within a processing chamber. 
   
   
       13 . The method of  claim 8  wherein the plasma is introduced by generation remote from the processing chamber followed by flowing into the processing chamber. 
   
   
       14 . The method of  claim 8  wherein the plasma is formed from a gas comprising ammonia. 
   
   
       15 . The method of  claim 8  wherein:
 depositing the first layer comprises,   flowing a liquid precursor material to an injection valve,   vaporizing the liquid precursor material with a carrier gas flowed through the injection valve, and   causing a reaction involving the vaporized liquid precursor material to deposit the first dielectric layer; and   the method further comprises,   halting the flow of liquid precursor material to the injection valve at a first time, and   halting the flow of carrier gas to the injection valve at a second time after the first time.   
   
   
       16 . The method of  claim 15  wherein the plasma is formed in the carrier gas. 
   
   
       17 . A substrate processing apparatus comprising:
 a processing chamber;   a gas distribution system including an injection valve in fluid communication with a liquid precursor source and in fluid communication with a carrier gas source, the injection valve configured to deliver a flow of liquid precursor vaporized in the carrier gas to the processing chamber;   an RF power system configured to apply RF energy to generate a plasma in a gas in fluid communication with the processing chamber;   a controller configured to control the gas delivery system and the RF power system; and   a memory, coupled to the controller, comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of the substrate processing apparatus, the computer-readable program including:   (i) a first set of instructions for halting a flow of the liquid precursor material to the injection valve at the conclusion of a deposition step involving the vaporized liquid precursor material, and   (ii) a second set of instructions for causing the RF power system to introduce the plasma into the processing chamber after the flow of liquid precursor to the injection valve has been halted.   
   
   
       18 . The apparatus of  claim 17  wherein the second set of instructions cause the RF power system to generate the plasma in ammonia gas. 
   
   
       19 . A substrate processing apparatus comprising:
 a processing chamber;   a gas distribution system including an injection valve in fluid communication with a liquid precursor source and in fluid communication with a carrier gas source, the injection valve configured to deliver a flow of liquid precursor vaporized in the carrier gas to the processing chamber;   a controller configured to control the gas delivery system; and   a memory, coupled to the controller, comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of the substrate processing apparatus, the computer-readable program including:   (i) a first set of instructions for halting a flow of the liquid precursor material to the injection valve at the conclusion of a deposition step involving the vaporized liquid precursor material, and   (ii) a second set of instructions for halting a flow of the carrier gas material to the injection valve after the flow of liquid precursor material to the injection valve has been halted.   
   
   
       20 . The apparatus of  claim 19  wherein the second set of instructions cause the flow of carrier gas to flow to the injection valve for a period of between about 1-10 seconds after the flow of the precursor material to the injection valve has been halted.