Plasma processing method for substrates
View Patent ↗A substrate placement process uses a tray in which a plurality of substrate receiving holes are provided to receive substrates and which has substrate support portions protruding from inner walls of the substrate receiving holes. The tray is placed onto a tray support portion of a substrate stage and places substrates onto substrate holding portions, respectively, so that edge portions of the substrates projected beyond end edges of the substrate holding portions and are apart from the substrate support portions. The first plasma processing process reduces internal pressure of a chamber and supplies a process gas thereto to fulfill plasma processing for the individual substrates. A second plasma processing process with the tray and the individual substrates placed on the substrate stage, reduces the internal pressure of the chamber and supplies a process gas to fulfill plasma processing so that by-products stuck to edge portions of the substrates and the substrate support portions due to the first plasma processing process are removed. By the removal of by-products stuck to the edge portions of the substrates and the tray during plasma processing, product quality is improved.
1. A plasma processing method, comprising:
carrying substrates into a chamber using a tray, wherein the tray has a plurality of substrate receiving holes that receive and carry the substrates, respectively, and wherein the substrate receiving holes have substrate support portions which protrude from inner walls of the substrate receiving holes and which support edge portions of the substrates;
placing the tray onto a tray support portion of a substrate stage in the chamber and placing the substrates onto respective substrate holding portions protruding upwardly from the tray support portion so that the edge portions of the substrates, projecting beyond end edges of the substrate holding portions, are apart from the substrate support portions;
first plasma processing comprising absorbing and holding the substrates on the substrate holding portions by electrostatic absorption using a first electrostatic absorption drive voltage, supplying a process gas into the chamber, adjusting internal pressure of the chamber and, while cooling the substrates with a cooling gas that is supplied at a specified pressure to between the substrates and the substrate holding portions, performing plasma processing for the substrates;
second plasma processing comprising, after said first plasma processing and with the tray and the individual substrates placed on the substrate stage, holding the substrates on the substrate holding portions by electrostatic absorption by changing to a second electrostatic absorption drive voltage that is lower than the first electrostatic absorption drive voltage used in said first plasma processing, supplying a process gas into the chamber, adjusting the internal pressure of the chamber and performing plasma processing so as to remove by-products from said first plasma processing that are stuck to the edge portions of the substrates and the substrate support portions; and
after completion of said second plasma processing, carrying the tray with the substrates out of the chamber while supporting the substrates with the substrate support portions.
2. The plasma processing method as claimed in claim 1 , wherein after completion of said first plasma processing, process gas is changed over to a process gas different in type from the process gas of said first plasma processing in execution of said second plasma processing, and said second plasma processing is performed with a pressure higher than the pressure of the first plasma processing process.
3. The plasma processing method for substrates as claimed in claim 1 , wherein in execution of said second plasma processing, a process-gas pressure is lower than the cooling gas pressure of said first plasma processing.
4. The plasma processing method for substrates as claimed in claim 3 , wherein the second electrostatic absorption drive voltage used during said second plasma processing, and a differential pressure between the internal pressure of the chamber and the cooling-gas pressure in the second plasma processing process, are equal to zero.
5. The plasma processing method for substrates as claimed in claim 1 , wherein sapphire substrates are used as the substrates, and said first plasma processing comprises forming a minor concavo-convex structure on surfaces of the sapphire substrates with said plasma processing.
6. The plasma processing method for substrates as claimed in claim 5 , wherein
BCl 3 is used as the process gas in said first plasma processing, and
O 2 /CF 4 is used as the process gas in said second plasma processing.
7. The plasma processing method for substrates as claimed in claim 1 , wherein after completion of said second plasma processing, a charge-eliminating plasma is generated and a charge elimination process reducing residual electrostatic absorption force between the substrates and the substrate holding portions is executed.
8. The plasma processing method for substrates as claimed in claim 1 , wherein by-products removed in the second plasma processing process are accumulated on side surfaces of the substrate holding portions.