US-12626889-B2 - Plasma processing method and apparatus

US12626889B2US 12626889 B2US12626889 B2US 12626889B2US-12626889-B2

Abstract

An embodiment plasma processing apparatus includes a plasma generation source, a nozzle in a plasma chamber, the nozzle being able to direct plasma from the plasma generation source to a wafer that is to be processed, the plasma having the form of a plasma stream at an exit of the nozzle, an outer annulus disposed in the plasma chamber and over the wafer, the outer annulus surrounding the nozzle, a gas exhaust disposed between inner sidewalls of the outer annulus and outer sidewalls of the nozzle, and a first vacuum pump connected to the gas exhaust between the inner sidewalls of the outer annulus and the outer sidewalls of the nozzle.

Inventors

Derek William Bassett
Jeffrey Lauerhaas
Lance Van Elsen

Assignees

TOKYO ELECTRON LIMITED

Dates

Publication Date: 20260512
Application Date: 20230602

Claims (20)

1 . A plasma processing apparatus comprising: a plasma generation source; a nozzle in a plasma chamber, the nozzle being able to direct plasma from the plasma generation source to a wafer that is to be processed, the plasma having the form of a plasma stream at an exit of the nozzle; a gas shroud disposed in the plasma chamber and over the wafer, the gas shroud surrounding the nozzle; a gas exhaust disposed between inner sidewalls of the gas shroud and outer sidewalls of the nozzle, wherein a plurality of orifices is disposed in sidewalls of the gas shroud, and wherein each orifice of the plurality of orifices allows for a flow of gas between the gas exhaust and the plasma chamber; and a first vacuum pump connected to the gas exhaust between the inner sidewalls of the gas shroud and the outer sidewalls of the nozzle.
2 . The plasma processing apparatus of claim 1 , further comprising a second vacuum pump connected to the plasma chamber, the second vacuum pump being configured to maintain the plasma chamber at a second pressure, the first vacuum pump being configured to maintain the gas exhaust at a first pressure.
3 . The plasma processing apparatus of claim 2 , wherein the second pressure is higher than the first pressure.
4 . The plasma processing apparatus of claim 2 , wherein a ratio of the second pressure to the first pressure is in a range from 10:1 to 20:1.
5 . The plasma processing apparatus of claim 2 , wherein the first pressure is in a range from 0 torr to 2 torr, and the second pressure is in a range from 1 torr to 100 torr.
6 . The plasma processing apparatus of claim 1 , wherein an outer diameter of the nozzle is in a range from 6 mm to 25 mm, and an outer diameter of the gas shroud is in a range from 8 mm to 40 mm.
7 . The plasma processing apparatus of claim 1 , wherein bottom surfaces of the gas shroud are below bottom surfaces of the nozzle.
8 . The plasma processing apparatus of claim 1 , wherein an outer diameter of the gas shroud varies vertically along an axis of the gas shroud.
9 . An apparatus comprising: a plasma source; a gas shroud disposed over a wafer to be processed in a processing chamber, the gas shroud having a concave shape with a flat center portion; a nozzle extending through a first opening in the flat center portion, the nozzle being configured to deliver plasma from the plasma source to an outer surface of the wafer; and a plurality of exhaust outlets extending from second openings in the flat center portion, the plurality of exhaust outlets being radially disposed around the nozzle, wherein each exhaust outlet of the plurality of exhaust outlets is oriented at an angle of 30° to 60° relative to a vertical axis of the nozzle.
10 . The apparatus of claim 9 , wherein the flat center portion is lower than edges of the gas shroud.
11 . The apparatus of claim 9 , wherein a height between a top surface of the wafer and a bottom surface of the flat center portion is in a range from 2 mm to 30 mm.
12 . The apparatus of claim 9 , further comprising: a first vacuum pump connected to the plurality of exhaust outlets, the first vacuum pump being configured to maintain a first pressure in each of the plurality of exhaust outlets; and a second vacuum pump connected to the processing chamber, the second vacuum pump being configured to maintain a second pressure in the processing chamber, wherein the first pressure and the second pressure are different.
13 . The apparatus of claim 12 , wherein a ratio of the second pressure to the first pressure is in a range from 10:1 to 20:1.
14 . A plasma processing apparatus comprising: a nozzle in a processing chamber, the nozzle being configured to direct plasma from a plasma generation source to a surface of a wafer in the processing chamber; a sleeve fitted around and in physical contact with outer sidewalls of the nozzle, wherein the sleeve comprises a first material, the nozzle comprises a second material, and the first material is different from the second material; a gas shroud disposed over the wafer and surrounding the outer sidewalls of the nozzle; a gas exhaust disposed between inner sidewalls of the gas shroud and the outer sidewalls of the nozzle, wherein a plurality of orifices is disposed in sidewalls of the gas shroud, and wherein the plurality of orifices allows for a flow of gas between the gas exhaust and the processing chamber; a first vacuum pump connected to the gas exhaust, the first vacuum pump being configured to maintain a first pressure in the gas exhaust; and a second vacuum pump connected to the processing chamber, the second vacuum pump being configured to maintain a second pressure in the processing chamber, wherein the first pressure and the second pressure are different.
15 . The plasma processing apparatus of claim 14 , wherein the gas shroud comprises: a first portion of the gas shroud that has a first outer diameter that is constant along an axis of the first portion of the gas shroud; a second portion of the gas shroud that has an outer diameter that varies along an axis of the second portion of the gas shroud; and a third portion of the gas shroud that has a second outer diameter that is constant along an axis of the third portion of the gas shroud, wherein the second portion of the gas shroud is disposed between and connects the first portion of the gas shroud to the third portion of the gas shroud.
16 . The plasma processing apparatus of claim 15 , wherein the second outer diameter is larger than the first outer diameter.
17 . The plasma processing apparatus of claim 14 , wherein the second pressure is higher than the first pressure.
18 . The plasma processing apparatus of claim 17 , wherein a ratio of the second pressure to the first pressure is in a range from 10:1 to 20:1.
19 . The plasma processing apparatus of claim 14 , wherein the second material of the nozzle comprises sapphire, tungsten, or a ceramic, and the first material of the sleeve comprises stainless steel.
20 . The plasma processing apparatus of claim 14 , wherein bottommost surfaces of the gas shroud are below bottommost surfaces of the nozzle.

Description

TECHNICAL FIELD The present invention relates generally to plasma processing, and, in particular embodiments, a plasma processing method and apparatus. BACKGROUND Semiconductor fabrication processes may involve various manufacturing techniques including formation, patterning and removing a number of layers over a substrate. Plasma processes are commonly used in various steps of semiconductor fabrication processes. For example, reactive ion etching (RIE), plasma-enhanced CVD (PECVD) and plasma-enhanced atomic layer deposition (PEALD) are common process steps in the fabrication of semiconductor devices. Semiconductor wafer die fabrication processes may also include a variety of processes that are used for wafer thinning and planarization. Chemical mechanical planarization (CMP) is a process that can be used for thinning and planarizing an entire wafer, but is not very capable of controllably thinning localized regions of the wafer. A localized or partial plasma etch can be used to remove material in a specific region of a wafer using a plasma, while leaving behind material in other surrounding regions of the wafer. As the plasma processes in the semiconductor industry further advance, there is a need to improve the existing plasma etching processes. These improvements are needed to lower etch damage from uncontrolled plasma flows to the surrounding regions of the wafer during the localized or partial plasma etch. Improvements are also needed to allow for better control of etching across the surface of the wafer resulting in improved uniformity across the wafer. SUMMARY In accordance with an embodiment, a plasma processing apparatus comprises a plasma generation source, a nozzle in a plasma chamber, the nozzle being able to direct plasma from the plasma generation source to a wafer that is to be processed, the plasma having the form of a plasma stream at an exit of the nozzle, an outer annulus disposed in the plasma chamber and over the wafer, the outer annulus surrounding the nozzle, a gas exhaust disposed between inner sidewalls of the outer annulus and outer sidewalls of the nozzle, and a first vacuum pump connected to the gas exhaust between the inner sidewalls of the outer annulus and the outer sidewalls of the nozzle. In accordance with an embodiment, a method of plasma processing comprises generating a plasma from a plasma source, directing the plasma into a processing chamber and to an outer surface of a wafer using a nozzle, the plasma exiting at an end of the nozzle disposed above the outer surface of the wafer, the plasma exiting in the form of a plasma stream, the nozzle extending through a gas shroud that surrounds the nozzle and that is disposed over the wafer, a gas exhaust being disposed between inner sidewalls of the gas shroud and outer sidewalls of the nozzle, maintaining a first pressure in the gas exhaust using a first vacuum pump; and maintaining a second pressure in the processing chamber using a second vacuum pump, the first pressure and the second pressure being different. In accordance with an embodiment, an apparatus comprises a plasma source, and a gas shroud disposed over a wafer to be processed in a processing chamber, the gas shroud having a concave shape with a flat center portion, a nozzle extending through a first opening in the flat center portion, the nozzle being configured to deliver plasma from the plasma source to an outer surface of the wafer, and a plurality of exhaust outlets extending from second openings in the flat center portion, the plurality of exhaust outlets being radially disposed around the nozzle. The foregoing has outlined rather broadly the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described herein, which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: FIG. 1 illustrates a block diagram of a plasma processing system, in accordance with various embodiments of the present disclosure; FIG. 2 illustrates a cross-sectional view of a region of the plasma processing system that was shown in FIG. 1, in accordance with various embodiments of the present disclosure; FIG. 3 illustrates a block diagram of a plasma processi