Ion Filter

Abstract

The present invention provides a method for using ion filtering to adjust the number of ions delivered to a substrate. The method comprising a process chamber being provided that is operatively connected to a plasma source. The substrate is provided on a substrate support that is provided within the process chamber. An electrical bias source is provided that is operatively connected to an aperture plate that is provided in the process chamber. The substrate on the substrate support is processed using a plasma generated using the plasma source. A variable bias voltage from the electrical bias source is applied to the aperture plate during the plasma processing of the substrate. The plasma processing of the substrate can further comprise exposing the substrate to a plasma time division multiplex process which alternates between deposition and etching on the substrate.

Description

CROSS REFERENCES TO RELATED APPLICATIONS[0001]This application claims priority from and is related to commonly owned U.S. Provisional Patent Application Ser. No. 62 / 424,360 filed Nov. 18, 2016, entitled: ION FILTER, this Provisional Patent Application incorporated by reference herein.FIELD OF THE INVENTION[0002]Invention relates to the field of charged particle sources including plasma sources for direct etching and deposition, broad-beam ion sources for ion beam deposition and etching, and electron sources for surface modification.BACKGROUND OF THE INVENTION[0003]Plasma processing apparatus used to etch silicon wafers and other substrates or to deposit a variety of materials on to various substrates can be very effective for the production of semiconductor devices and other related systems. In its basic form, plasma is generated in a source region from appropriate precursor gases forming positive ions of the gas, electrons and neutral radicals. At the wafer, for an etch process, th...

AI Technical Summary

Benefits of technology

The patent is about a process called the Bosch DRIE process. The invention aims to increase the selectivity of the process by reducing the number of ions that damage the mask used to create patterns on the wafer. This is done by adjusting the bias applied to the aperture plate during the deposition and etching steps. By balancing the number of ions with the wafer, the process becomes more effective and efficient. This invention can be applied to any process that requires a time variation in the number of ions reaching the wafer.

Problems solved by technology

It is frequently the case that the plasma produced while being usable for the required purpose, does not have the ideal ratio of numbers of ions to numbers of chemically reactive radicals to achieve the most effective plasma processing of the wafer.

It is particularly the case as requirements become stronger to etch material at ever faster rates that simply increasing the flow of gas to the plasma source and the level of power used to dissociate and ionize the gas, results in a plasma where there are too many ions in relation to the number of neutral radicals and as the etching process proceeds the excess numbers of ions may cause damage to the structures being etched.

The magnet based techniques are limited in the pressure range where they may be used as with increasing pressure there is an increased probability that electrons will not remain trapped on the magnetic field lines because they suffer collisions with neutral gas atoms or molecules and randomly walk across the field lines.

At pressures above 10 to 20 mTorr, the technique becomes less effective.

Ion loss will be greater if the transparency of the grid is reduced.

As the aperture aspect ratio increases, charged species passing through an aperture have increased probability of contacting the side wall of the aperture and being lost.

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