US-20260130171-A1 - PRESSURE CONTROL SYSTEM FOR A BEVEL EDGE ETCH CHAMBER IMPLEMENTING SUBSTRATE FRONTSIDE AND BACKSIDE PRESSURE CONTROL

US20260130171A1US 20260130171 A1US20260130171 A1US 20260130171A1US-20260130171-A1

Abstract

A pressure control system for a bevel edge etch chamber. The pressure control system includes a first sensor, a second sensor, at least one valve, and a controller. The first sensor is configured to detect a frontside pressure within the bevel edge etch chamber. The frontside pressure is indicative of a downforce on a substrate disposed on a substrate support within the bevel edge etch chamber. The second sensor is configured to detect a backside pressure on a backside of the substrate. The controller is configured to implement an etch process in the bevel edge etch chamber, and, based on the frontside pressure and the backside pressure, to control the at least one valve to maintain the frontside pressure at a pressure greater than the backside pressure at least one of during the etch process and for a period subsequent to the etch process.

Inventors

Songqi Gao
Goon Heng WONG
Jack Chen

Assignees

LAM RESEARCH CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251231

Claims (20)

1 . A pressure control system for a bevel edge etch chamber, the pressure control system comprising: a first sensor configured to detect a frontside pressure within the bevel edge etch chamber, wherein the frontside pressure is indicative of a downforce on a substrate disposed on a substrate support within the bevel edge etch chamber; a second sensor configured to detect a backside pressure on a backside of the substrate; at least one valve; and a controller configured to implement an etch process in the bevel edge etch chamber, and, based on the frontside pressure and the backside pressure, to control the at least one valve to maintain the frontside pressure at a pressure greater than the backside pressure at least one of during the etch process and for a period subsequent to the etch process.
2 . The pressure control system of claim 1 , wherein the period is from an end of the etch process to when a gas distribution plate of the bevel edge etch chamber has transitioned to being in an up position.
3 . The pressure control system of claim 1 , wherein the period is from when a gas distribution plate of the bevel edge etch chamber has transitioned to being in an up position to at least when lift pins for lifting the substrate have transitioned to being in up positions.
4 . The pressure control system of claim 1 , wherein the controller is configured to permit the frontside pressure to drop below the backside pressure subsequent to the etch process, a gas distribution plate transitioning to an up position, and lift pins lift up the substrate.
5 . The pressure control system of claim 1 , wherein: the at least one valve comprises an evacuation valve; and the controller is configured to control the evacuation valve to remove gas from a frontside of the substrate to reduce the frontside pressure of the bevel edge etch chamber, and during the removal of the gas from the frontside of the substrate and based on the frontside pressure and the backside pressure, regulate an opening of the evacuation valve such that the frontside pressure does not drop below the backside pressure.
6 . The pressure control system of claim 5 , wherein the controller is configured to: compare the frontside pressure to the backside pressure to provide a pressure differential value; transition the evacuation valve from a first open state to a second open state when at least one of a rate of change of the pressure differential value exceeds a first threshold or the pressure differential value is less than or equal to a second threshold, wherein the second open state is a more closed state than the first open state; and transition the evacuation valve from the first open state to a third open state, when at least one of the rate of change of the pressure differential value does not exceed the first threshold or the pressure differential value is greater than the second threshold, wherein the third open state is a more open state than the first open state.
7 . The pressure control system of claim 5 , wherein the controller is configured to close the evacuation valve when the frontside pressure is less than or equal to the backside pressure.
8 . The pressure control system of claim 5 , wherein the controller is configured to: during the removal of gas from the frontside of the substrate, determine whether the frontside pressure is less than a predetermined pressure; and when the frontside pressure is less than the predetermined pressure, actuate lift pins to lift the substrate off a top surface of a body of the substrate support.
9 . The pressure control system of claim 8 , wherein the predetermined pressure is 4-5 Torr.
10 . The pressure control system of claim 1 , wherein the controller is configured to: determine whether the frontside pressure is less than a first predetermined pressure; in response to determining that the frontside pressure is less than the first predetermined pressure, moving lift pins of the substrate support up to lift the substrate; determine whether the frontside pressure is at least one of less than a second predetermined pressure and equal to a base pressure; and in response to the frontside pressure being at least one of less than the second predetermined pressure and equal to the base pressure, transferring the substrate from the substrate support.
11 . The pressure control system of claim 1 , wherein the controller is configured to: determine whether a gas distribution plate of the bevel edge etch chamber is in an up position; and in response to the gas distribution plate being in an up position, perform gas distribution plate homing including homing to zero position of a stepper motor used to move the gas distribution plate, and move lift pins up to lift the substrate and overcome downward pressure remaining on the substrate.
12 . The pressure control system of claim 1 , wherein the controller is configured to: determine whether the frontside pressure is less than a predetermined pressure associated with substrate movement; and in response to determining that the frontside pressure is less than the predetermined pressure, moving lift pins of the substrate support up to lift and transfer the substrate.
13 . The pressure control system of claim 1 , wherein: the at least one valve comprises a backside valve and an evacuation valve; and the controller is configured, during the etch process, to open the backside valve to continuously draw gas from the backside of the substrate and to open the evacuation valve to draw gas from a frontside of the substrate.
14 . The pressure control system of claim 1 , wherein the controller is configured to regulate the at least one valve to maintain at least a safety margin between the frontside pressure and the backside pressure.
15 . The pressure control system of claim 1 , wherein the controller is configured to: determine whether the frontside pressure is more than a predetermined amount greater than the backside pressure; in response to the frontside pressure being more than the predetermined amount greater than the backside pressure, depressurizing the bevel edge etch chamber at a depressurization rate, the depressurization rate being based on the frontside pressure and the backside pressure; and in response to the frontside pressure being less than the predetermined amount greater than the backside pressure, at least one of ceasing depressurization of the bevel edge etch chamber and reducing rate of depressurization of the bevel edge etch chamber.
16 . The pressure control system of claim 1 , wherein the controller is configured to, during removal of gas from a frontside of the substrate, maximize an opening of one of the at least one valve to maximize a depressurization rate of the bevel edge etch chamber while at least one of preventing the frontside pressure from dropping below the backside pressure or maintaining at least a safety margin between the frontside pressure and the backside pressure.
17 . The pressure control system of claim 1 , wherein the controller is configured to: pressurize the bevel edge etch chamber to provide a first frontside pressure; process the substrate according to a first portion of a recipe; remove gas from the bevel edge etch chamber to provide a second frontside pressure that is less than the first frontside pressure; and process the substrate according to a second portion of the recipe.
18 . The pressure control system of claim 17 , wherein the first frontside pressure is greater than 4-5 Torr.
19 . The pressure control system of claim 1 , wherein: the substrate support is void of mechanical and electrical components to hold the substrate in place on the substrate support; and the controller is configured to prevent the substrate from moving on the substrate support by pressuring the bevel edge etch chamber.
20 . The pressure control system of claim 1 , wherein: the substrate support is implemented as an electrostatic chuck; and the controller is configured to, during removal of gas from a frontside of the substrate, cease electrostatic clamping of the substrate prior to lifting the substrate off a top surface of a body of the substrate support.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. application Ser. No. 18/013,091, filed on Dec. 27, 2022, which is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/US2022/032456, filed Jun. 7, 2022, which claims the benefit of U.S. Provisional Application No. 63/210,444, filed on Jun. 14, 2021. The entire disclosures of the applications referenced above are incorporated herein by reference. FIELD The present disclosure relates to generally to substrate processing systems and more particularly to pressure control systems for preventing substrate movement. BACKGROUND The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. Substrate processing systems may be used to deposit, etch, ash, clean or otherwise perform treatment of film on a substrate such as a semiconductor wafer. The substrate processing systems typically include a processing chamber, a gas distribution device, and a substrate support assembly. During processing, the substrate is arranged on the substrate support assembly. Different gas mixtures may be introduced into the processing chamber. Radio frequency (RF) plasma and/or heat may be used to activate chemical reactions. Prior to processing, the substrate is transferred into the processing chamber and disposed on lift pins of a substrate support. The lift pins are then lowered to place the substrate on a body of the substrate support. The processing chamber is pressurized according to a process recipe. Subsequent to processing, the substrate is lifted from the substrate support via the lift pins and then the processing chamber is depressurized. The substrate is removed from the processing chamber after depressurization. SUMMARY A pressure control system is provided and includes a first sensor, a second sensor, an evacuation valve and a controller. The first sensor is configured to detect a frontside pressure within a processing chamber. The frontside pressure is indicative of a downforce on a substrate disposed on a substrate support within the processing chamber. The second sensor is configured to detect a backside pressure on a backside of the substrate. The controller is configured to: control the evacuation valve to remove gas from and reduce the frontside pressure of the processing chamber; and during the removal of gas from and reduction in the frontside pressure of the processing chamber and based on the frontside pressure and the backside pressure, regulate an opening of the evacuation valve such that the frontside pressure does not drop below the backside pressure. In other features, the controller is configured to: during the removal of gas from and reduction in frontside pressure of the processing chamber, compare the frontside pressure to the backside pressure to provide a pressure differential value; transition the evacuation valve from a first open state to a second open state when at least one of a rate of change of the pressure differential value exceeds a first threshold or the pressure differential value is less than or equal to a second threshold, wherein the second open state is a more closed state than the first open state; and transition the evacuation valve from the first open state to a third open state, when at least one of the rate of change of the pressure differential value does not exceed the first threshold or the pressure differential value is greater than the second threshold, wherein the third open state is a more open state than the first open state. In other features, the controller is configured to close the evacuation valve when the frontside pressure is less than or equal to the backside pressure. In other features, the controller is configured to remove gas from the processing chamber and regulate the opening of the evacuation valve at least one of during or subsequent to processing the substrate. In other features, the pressure control system further includes a backside valve. The controller is configured to open the backside valve to continuously draw gas from the backside of the substrate during processing and removal of gas from the processing chamber. In other features, the controller is configured to regulate the evacuation valve to maintain at least a safety margin between the frontside pressure and the backside pressure. In other features, the controller is configured to, during the removal of gas from and reduction in the frontside pressure of the processing chamber, maximize an opening of the evacuation valve to maximize a depressurization rate of the processing chamber while at least one of preventing the frontside pressure fro