Plasma processing apparatus and plasma processing method

Abstract

A plasma processing apparatus includes a flow splitter for dividing a common gas into two common gas streams of common gas branch lines. A central introduction portion connected to one of the common gas branch lines supplies a common gas to a central portion of a substrate to be processed. A peripheral introducing portion connected to the other one of the common gas branch lines supplies the common gas to a peripheral portion of the substrate. The peripheral introducing portion has peripheral inlets arranged about a circumferential region above the substrate. An additive gas line is connected to an additive gas source to add an additive gas to at least one of the common gas branch lines. In addition, an electron temperature of a plasma in a region where the peripheral inlets are disposed is lower than that in a region where the introduction portion is disposed.

What is claimed is: 
     
         1 . A plasma processing apparatus comprising:
 a processing chamber which has a dielectric window provided at a ceiling portion thereof, and whose inside can be maintained airtightly, the dielectric window transmitting a microwave therethrough, said processing chamber including a processing space therein;   a mounting table provided inside the processing chamber to mount a substrate thereon;   a slot antenna which is provided on an upper surface of the dielectric window of the processing chamber, and through which a microwave is introduced into the processing space of the processing chamber through slots of the slot antenna;   a microwave generator which generates a microwave of a predetermined frequency;   a microwave introduction path which guides the microwave generated by the microwave generator to the slot antenna;   a processing gas introduction unit which introduces a processing gas supplied from a processing gas source into the processing chamber; and   an exhaust unit which exhausts the processing gas introduced into the processing chamber, through an exhaust port provided below an upper surface of the substrate mounted on the mounting table;   wherein the processing gas source includes a common gas source for supplying a common gas, and an additive gas source for supplying an additive gas;   wherein the processing gas introduction unit includes:   a common gas line connected to the common gas source;   a flow splitter which is provided in the common gas line to divide the common gas into two common gas streams flowing through two common gas branch lines, and which can adjust a ratio of flow rates of the two common gas streams in the common gas branch lines;   a central introduction portion which is connected to one of the common gas branch lines and which has a central inlet to supply the common gas to a central portion of the substrate mounted on the mounting table;   a peripheral introducing portion which is connected to the other one of the common gas branch lines and which has peripheral inlets arranged about a circumferential region at a location above the substrate to supply the common gas to a peripheral portion of the substrate mounted on the mounting table;   an additive gas line which is connected to the additive gas source to add the additive gas to at least one of the common gas branch lines; and   a flow control unit which is provided in the additive gas line to adjust a flow rate of the additive gas;   wherein the central inlet is disposed at a central portion of the dielectric window of the processing chamber;   wherein the peripheral inlets are disposed above the substrate mounted on the mounting table and below the dielectric window of the processing chamber; and   wherein an electron temperature of a plasma in a region where the peripheral inlets are disposed is lower than that in a region where the central inlet is disposed.   
     
     
         2 . The plasma processing apparatus of  claim 1 , further comprising a control device to control the ratio of the flow rates of the two common gas streams divided by the flow splitter, and the flow rate of the additive gas to be adjusted by the flow control unit. 
     
     
         3 . The plasma processing apparatus of  claim 1 , wherein the peripheral inlets are arranged around a flow of the processing gas injected toward the substrate by the central inlet disposed in the dielectric window, to inject the processing gas toward the flow of the processing gas injected by the central inlet. 
     
     
         4 . The plasma processing apparatus of  claim 1 ,
 wherein the common gas source includes a plasma excitation gas as the common gas, the additive gas source includes an etching gas to etch the substrate as the additive gas, and the additive gas line is connected to the common gas branch line which supplies the common gas to the peripheral inlets.   
     
     
         5 . A plasma processing apparatus comprising:
 a processing chamber;   a dielectric window which is provided at an upper portion of the processing chamber and defines a processing space;   a mounting table provided inside the processing chamber;   a slot antenna provided on an upper surface of the dielectric window;   a microwave introduction path connecting the slot antenna to a microwave generator;   an exhaust device communicating with an inside of the processing chamber;   a common gas line connected to a common gas source;   a flow splitter which is provided in the common gas line and which is configured to divide the common gas line into first and second common gas branch lines, and to adjust a ratio of flow rates of gas flowing through the first and second common gas branch lines;   a central introduction portion which is connected to the first common gas branch line and which has a central inlet located above a central portion of a substrate mounted on the mounting table;   a peripheral introduction portion which is connected to the second common gas branch line and which has peripheral inlets arranged about a circumferential region at a location above the substrate and located below the dielectric window; and   an additive gas line connecting an additive gas source to at least one of the first and second common gas branch lines.   
     
     
         6 . A plasma processing apparatus comprising:
 a processing chamber which has a dielectric window provided at a ceiling portion thereof, and whose inside can be maintained airtightly, the dielectric window transmitting a microwave therethrough, said processing chamber including a processing space therein;   a mounting table provided inside the processing chamber to mount a substrate thereon;   a slot antenna which is provided on an upper surface of the dielectric window of the processing chamber, and wherein a microwave is introduced into the processing space of the processing chamber through slots of the slot antenna;   a microwave generator which generates a microwave of a predetermined frequency;   a microwave introduction path which guides the microwave generated by the microwave generator to the slot antenna;   a processing gas introduction unit which introduces a processing gas supplied from a processing gas source into the processing chamber; and   an exhaust unit which exhausts the processing gas introduced into the processing chamber, through an exhaust port provided below an upper surface of the substrate mounted on the mounting table;   wherein the processing gas source includes a common gas source for supplying a common gas, and an additive gas source for supplying an additive gas;   wherein the processing gas introduction unit includes:   a common gas line connected to the common gas source;   two common gas branch lines branching from the common gas line;   a central introduction portion which is connected to one of the two common gas branch lines branching from the common gas line, and which has a central inlet to supply the common gas to a central portion of the substrate mounted on the mounting table;   a peripheral introducing portion which is connected to the other one of the two common gas branch lines, and which has peripheral inlets arranged about a circumferential region located above the substrate to supply the common gas to a peripheral portion of the substrate mounted on the mounting table;   an additive gas line which is connected to the additive gas source to add the additive gas to at least one of the two common gas branch lines; and   a flow control unit which is provided in the additive gas line to adjust a flow rate of the additive gas;   wherein the central inlet is disposed at a central portion of the dielectric window of the processing chamber;   wherein the peripheral inlets are disposed above the substrate mounted on the mounting table and below the dielectric window of the processing chamber; and   wherein an electron temperature of a plasma in a region where the peripheral inlets are disposed is lower than that in a region where the central inlet is disposed.   
     
     
         7 . A plasma processing apparatus comprising:
 a processing chamber;   a dielectric window which is provided at an upper portion of the processing chamber and defines a processing space;   a mounting table provided inside the processing chamber;   a slot antenna provided on an upper surface of the dielectric window;   a microwave introduction path connecting the slot antenna to a microwave generator;   an exhaust device communicating with an inside of the processing chamber;   a common gas line connected to a common gas source;   first and second common gas branch lines branching from the common gas line;   a central introduction portion which is connected to the first common gas branch line and has a central inlet located above a central portion of a substrate mounted on the mounting table;   a peripheral introduction portion which is connected to the second common gas branch line and has peripheral inlets arranged about a circumferential region located above the substrate and located below the dielectric window; and   an additive gas line connecting an additive gas source to at least one of the first and second common gas branch lines.   
     
     
         8 . The plasma processing apparatus of  claim 7 , wherein the peripheral inlets of the peripheral introduction portion are located below the central inlet of the central introduction portion.