Moveable edge coupling ring for edge process control during semiconductor wafer processing

A substrate processing system includes a processing chamber. A pedestal is arranged in the processing chamber. An edge coupling ring is arranged adjacent to the pedestal and around a radially outer edge of the substrate. An actuator is configured to selectively move a first portion of the edge coupling ring relative to the substrate to alter an edge coupling profile of the edge coupling ring.

FIELD

The present disclosure relates to substrate processing systems, and more particularly to edge coupling rings of substrate processing systems.

BACKGROUND

Substrate processing systems may be used to perform etching and/or other treatment of substrates such as semiconductor wafers. A substrate may be arranged on a pedestal in a processing chamber of the substrate processing system. For example during etching in a plasma enhanced chemical vapor deposition (PECVD) process, a gas mixture including one or more precursors is introduced into the processing chamber and plasma is struck to etch the substrate.

Edge coupling rings have been used to adjust an etch rate and/or etch profile of the plasma near a radially outer edge of the substrate. The edge coupling ring is typically located on the pedestal around the radially outer edge of the substrate. Process conditions at the radially outer edge of the substrate can be modified by changing a position of the edge coupling ring, a shape or profile of an inner edge of the edge coupling ring, a height of the edge coupling ring relative to an upper surface of the substrate, a material of the edge coupling ring, etc.

Changing the edge coupling ring requires the processing chamber to be opened, which is undesirable. In other words, an edge coupling effect of the edge coupling ring cannot be altered without opening the processing chamber. When the edge coupling ring is eroded by plasma during etching, the edge coupling effect changes. Correcting erosion of the edge coupling ring requires the processing chamber to be opened in order to replace the edge coupling ring.

Referring now toFIGS.1-2, a substrate processing system may include a pedestal20and an edge coupling ring30. The edge coupling ring30may include a single piece or two or more portions. In the example inFIGS.1-2, the edge coupling ring30includes a first annular portion32arranged near a radially outer edge of a substrate33. A second annular portion34is located radially inwardly from the first annular portion below the substrate33. A third annular portion36is arranged below the first annular portion32. During use, plasma42is directed at the substrate33to etch the exposed portions of the substrate33. The edge coupling ring30is arranged to help shape the plasma such that uniform etching of the substrate33occurs.

InFIG.2, after the edge coupling ring30has been used, an upper surface of a radially inner portion of the edge coupling ring30may exhibit erosion as identified at48. As a result, plasma42may tend to etch a radially outer edge of the substrate33at a faster rate than etching of radially inner portions thereof as can be seen at44.

SUMMARY

A substrate processing system includes a processing chamber. A pedestal is arranged in the processing chamber. An edge coupling ring is arranged adjacent to the pedestal and around a radially outer edge of the substrate. An actuator is configured to selectively move a first portion of the edge coupling ring relative to the substrate to alter an edge coupling profile of the edge coupling ring.

In other features, a gas delivery system is configured to deliver process gas and carrier gas to the processing chamber. A plasma generator is configured to create plasma in the processing chamber to etch the substrate. The actuator moves the first portion of the edge coupling ring without requiring the processing chamber to be opened.

In other features, the edge coupling ring further comprises a second portion. The actuator is configured to move the first portion of the edge coupling ring relative the second portion of the edge coupling ring. The actuator includes a piezoelectric actuator. The actuator includes a stepper motor actuator. The actuator includes a pneumatic drive actuator.

In other features, a controller is configured to move the edge coupling ring in response to erosion of a plasma-facing surface of the edge coupling ring. The controller automatically moves the edge coupling ring after the edge coupling ring is exposed to a predetermined number of etching cycles. The controller automatically moves the edge coupling ring after the edge coupling ring is exposed to a predetermined period of etching.

In other features, the actuator moves the first portion of the edge coupling ring vertically relative to the substrate. The actuator moves the first portion of the edge coupling ring horizontally relative to the substrate. A sensor is configured to communicate with the controller and to detect the erosion of the edge coupling ring.

In other features, a robot is configured to communicate with the controller and to adjust a position of the sensor. The sensor includes a depth gauge. The sensor includes a laser interferometer. The actuator selectively tilts the edge coupling ring relative to the substrate. The actuator is located outside of the processing chamber. A rod member connects the actuator to the edge coupling ring through a wall of the processing chamber.

In other features, a seal is arranged between the rod member and the wall of the processing chamber. A controller is configured to move the edge coupling ring to a first position for a first treatment of the substrate using a first edge coupling effect and then to a second position for a second treatment of the substrate using a second edge coupling effect.

A method for adjusting an edge coupling profile of an edge coupling ring in a substrate processing system includes arranging an edge coupling ring adjacent to a pedestal in a processing chamber. The edge coupling ring is arranged around a radially outer edge of the substrate. The method includes selectively moving a first portion of the edge coupling ring relative to the substrate using an actuator to alter an edge coupling profile of the edge coupling ring.

In other features, the method includes delivering process gas and carrier gas to the processing chamber. The method includes creating plasma in the processing chamber to etch the substrate. The method includes moving the first portion of the edge coupling ring using the actuator without requiring the processing chamber to be opened. The edge coupling ring further comprises a second portion. The actuator is configured to move the first portion of the edge coupling ring relative the second portion of the edge coupling ring. The actuator is selected from a group consisting of a piezoelectric actuator, a stepper motor actuator, and a pneumatic drive actuator.

In other features, the method includes moving the edge coupling ring in response to erosion of a plasma-facing surface of the edge coupling ring. The method includes automatically moving the edge coupling ring after the edge coupling ring is exposed to a predetermined number of etching cycles. The method includes automatically moving the edge coupling ring after the edge coupling ring is exposed to a predetermined period of etching. The method includes moving the first portion of the edge coupling ring vertically relative to the substrate. The method includes moving the first portion of the edge coupling ring horizontally relative to the substrate.

In other features, the method includes using a sensor to sense erosion of the edge coupling ring. The sensor is selected from a group consisting of a depth gauge and a laser interferometer. The method includes selectively tilting the edge coupling ring relative to the substrate. The actuator is located outside of the processing chamber.

In other features, the method includes moving the edge coupling ring to a first position for a first treatment of the substrate using a first edge coupling effect and moving the edge coupling ring to a second position for a second treatment of the substrate using a second edge coupling effect.

DETAILED DESCRIPTION

The present disclosure allows one or more portions of an edge coupling ring to be moved vertically and/or horizontally relative to a substrate or pedestal in a substrate processing system. The movement changes an edge coupling effect of the plasma relative to the substrate during etching or other substrate treatment without requiring the processing chamber to be opened.

Referring now toFIGS.3-5, a substrate processing system includes a pedestal20and an edge coupling ring60. The edge coupling ring60may be made of a single portion or two or more portions may be used. In the example inFIGS.3-5, the edge coupling ring60includes a first annular portion72arranged radially outside of the substrate33. A second annular portion74is located radially inwardly from the first annular portion72below the substrate33. A third annular portion76is arranged below the first annular portion72.

An actuator80may be arranged in various locations to move one or more portions of the edge coupling ring60relative to the substrate33as will be described further below. For example only, inFIG.3the actuator80is arranged between the first annular portion72of the edge coupling ring60and the third annular portion76of the edge coupling ring60. In some examples, the actuator80may include a piezoelectric actuator, a stepper motor, a pneumatic drive, or other suitable actuator. In some examples, one, two, three, or four or more actuators are used. In some examples, multiple actuators are arranged uniformly around the edge coupling ring60. The actuator(s)80may be arranged inside or outside of the processing chamber.

During use, plasma82is directed at the substrate33to etch the exposed portions of the substrate33. The edge coupling ring60is arranged to help shape the plasma electric field such that uniform etching of the substrate33occurs. As can be seen at84and86inFIG.4, one or more portions of the edge coupling ring60may be eroded by the plasma82. As a result of the erosion, non-uniform etching of the substrate33may occur near a radially outer edge of the substrate33. Normally, the process would need to be stopped, the processing chamber opened and the edge coupling ring replaced.

InFIG.5, the actuator80is used to move one or more portions of the edge coupling ring60to alter the position of the one or more portions of the edge coupling ring60. For example, the actuator80may be used to move the first annular portion72of the edge coupling ring60. In this example, the actuator80moves the first annular portion72of the edge coupling ring60in an upward or vertical direction such that an edge86of the first annular portion72of the edge coupling ring60is higher relative to the radially outer edge of the substrate33. As a result, etch uniformity near the radially outer edge of the substrate33is improved.

Referring now toFIG.6, as can be appreciated, the actuator may be arranged in one or more other locations and may move in other directions such as horizontal, diagonal, etc. Horizontal movement of the portion of the edge coupling ring may be performed to center the edge coupling effect relative to the substrate. InFIG.6, an actuator110is arranged radially outside of the edge coupling ring60. In addition, the actuator110moves in a vertical (or an up/down) direction as well as in a horizontal (or side to side) direction. Horizontal repositioning may be used when etching of the substrates shows a horizontal offset of the edge coupling ring relative to the substrates. The horizontal offset may be corrected without opening the processing chamber. Likewise, tilting of the edge coupling ring may be performed by actuating some of the actuators differently than others of the actuators to correct or create side-to-side asymmetry.

Rather than locating the actuator110between annular portions of the edge coupling ring, the actuator110may also be attached to a radially outer wall or other structure identified at114. Alternately, the actuator110may be supported from below by a wall or other structure identified at116.

Referring now toFIG.7-8, another example of an edge coupling ring150and a piezoelectric actuator154is shown. In this example, the piezoelectric actuator154moves the edge coupling ring150. The piezoelectric actuator154is mounted in the first annular portion72and the third annular portion76of the edge coupling ring150. InFIG.8, the piezoelectric actuator154moves the first annular portion72of the edge coupling ring150to adjust a position of an edge156of the first annular portion72.

Referring now toFIG.9, an example of a substrate processing chamber500for performing etching using RF plasma is shown. The substrate processing chamber500includes a processing chamber502that encloses other components of the substrate processing chamber500and contains the RF plasma. The substrate processing chamber500includes an upper electrode504and a pedestal506including a lower electrode507. An edge coupling ring503is supported by the pedestal506and is arranged around the substrate508. One or more actuators505may be used to move the edge coupling ring503. During operation, a substrate508is arranged on the pedestal506between the upper electrode504and the lower electrode507.

For example only, the upper electrode504may include a showerhead509that introduces and distributes process gases. The showerhead509may include a stem portion including one end connected to a top surface of the processing chamber. A base portion is generally cylindrical and extends radially outwardly from an opposite end of the stem portion at a location that is spaced from the top surface of the processing chamber. A substrate-facing surface or faceplate of the base portion of the showerhead includes a plurality of holes through which process gas or purge gas flows. Alternately, the upper electrode504may include a conducting plate and the process gases may be introduced in another manner. The lower electrode507may be arranged in a non-conductive pedestal. Alternately, the pedestal506may include an electrostatic chuck that includes a conductive plate that acts as the lower electrode507.

An RF generating system510generates and outputs an RF voltage to one of the upper electrode504and the lower electrode507. The other one of the upper electrode504and the lower electrode507may be DC grounded, AC grounded or floating. For example only, the RF generating system510may include an RF voltage generator511that generates the RF voltage that is fed by a matching and distribution network512to the upper electrode504or the lower electrode507. In other examples, the plasma may be generated inductively or remotely.

A gas delivery system530includes one or more gas sources532-1,532-2, . . . , and532-N (collectively gas sources532), where N is an integer greater than zero. The gas sources supply one or more precursors and mixtures thereof. The gas sources may also supply purge gas. Vaporized precursor may also be used. The gas sources532are connected by valves534-1,534-2, . . . , and534-N (collectively valves534) and mass flow controllers536-1,536-2, . . . , and536-N (collectively mass flow controllers536) to a manifold540. An output of the manifold540is fed to the processing chamber502. For example only, the output of the manifold540is fed to the showerhead509.

A heater542may be connected to a heater coil (not shown) arranged in the pedestal506. The heater542may be used to control a temperature of the pedestal506and the substrate508. A valve550and pump552may be used to evacuate reactants from the processing chamber502. A controller560may be used to control components of the substrate processing chamber500. The controller560may also be used to control the actuator505to adjust a position of one or more portions of the edge coupling ring503.

A robot570and a sensor572may be used to measure erosion of the edge coupling ring. In some examples, the sensor572may include a depth gauge. The robot570may move the depth gauge in contact with the edge coupling ring to measure erosion. Alternately, a laser interferometer (with or without the robot570) may be used to measure erosion without direct contact. The robot570may be omitted if the laser interferometer can be positioned with a direct line of sight to the edge coupling ring.

Referring now toFIG.10, an example of a method600for operating the actuator to move the edge coupling ring is shown. At610, at least part of an edge coupling ring is positioned in a first location relative to the substrate. At614, the substrate processing system is operated. The operation may include etching or other treatment of a substrate. At618, control determines whether a predetermined period of etching or a predetermined number etching cycles have occurred. If the predetermined period or number of cycles is not exceeded as determined at618, control returns to614.

When the predetermined period or number of cycles are up, control determines at624whether a maximum predetermined etching period is up, a maximum number of etching cycles has occurred and/or a maximum # of actuator moves have occurred.

If624is false, control moves at least part of the edge coupling ring using the actuator. Movement of the edge coupling ring can be performed automatically, manually or a combination thereof without opening the processing chamber. If624is true, control sends a message or otherwise indicates that the edge coupling ring should be serviced/replaced.

Referring now toFIG.11, an example of a method700for operating the actuator to move the edge coupling ring is shown. At710, at least part of an edge coupling ring is positioned in a first location relative to the substrate. At714, the substrate processing system is operated. The operation may include etching or other treatment of a substrate. At718, control determines whether a predetermined amount of erosion of the edge coupling ring has occurred using a sensor such as a depth gauge or laser interferometer. If718is false, control returns to714.

When the predetermined amount of erosion has occurred, control determines at724whether a maximum amount of erosion has occurred. If724is false, control moves at least part of the edge coupling ring using the actuator. Movement of the edge coupling ring can be performed automatically, manually or a combination thereof without opening the processing chamber. If724is true, control sends a message or otherwise indicates that the edge coupling ring should be serviced/replaced.

In addition to the foregoing, a determination of whether or not the edge coupling ring needs to be moved may be based on inspection of etching patterns of the substrates after processing. The actuator may be used to adjust the edge coupling profile of the edge coupling ring without opening the chamber.

Referring now toFIG.12, a processing chamber800includes an edge coupling ring60arranged on a pedestal20. The edge coupling ring60includes one or more portions that are movable by one or more actuators804arranged outside of the processing chamber800. In this example, the portion72is movable. The actuators804may be connected by mechanical linkage810to the portion72of the edge coupling ring60. For example, the mechanical linkage810may include a rod member. The mechanical linkage810may pass through a hole811in a wall814of the processing chamber800. A seal812such as an “O”-ring may be used. The mechanical linkage810may pass through holes815in one or more structures such as the portion76of the edge coupling ring60.

Referring now toFIGS.13A and13B, side-to-side tilting of an edge coupling ring830is shown. Side-to-side tilting may be used to correct side-to-side misalignment. InFIG.13A, portions830-1and830-2of an edge coupling ring830on opposite sides of the substrate are arranged in a first arrangement840. The portions830-1and830-2may be generally aligned with portions832-1and832-2of the edge coupling ring830. Actuators836-1and836-2are arranged between the portions830-1and832-1and830-2and832-2, respectively.

InFIG.13B, the actuators836-1and836-2move the respective portions of the edge coupling ring830such that the edge coupling ring830moves to a second arrangement850that is different than the first arrangement840shown inFIG.13A. As can be appreciated, the substrates may be inspected after treatment and the tilt relative to the substrate may be adjusted as needed without opening the processing chamber.

Referring now toFIG.14, a method900for moving an edge coupling ring during processing of a substrate is shown. In other words, different treatments may be performed on a single substrate in the same processing chamber. The edge coupling effect of the edge coupling ring may be adjusted between the multiple treatments performed on the substrate in the same processing chamber before proceeding to a subsequent substrate. At910, a substrate is positioned on a pedestal and a position of the edge coupling ring is adjusted if needed. At914, treatment of the substrate is performed. If processing of the substrate is done as determined at918, the substrate is removed from the pedestal at922. At924, control determines whether another substrate needs to be processed. If924is true, the method returns to910. Otherwise the method ends.

If918is false and the substrate needs additional treatment, the method determines whether adjustment of the edge coupling ring is required at930. If930is false, the method returns to914. If930is true, at least part of the edge coupling ring is moved using one or more actuators at934and the method returns to914. As can be appreciated, the edge coupling ring can be adjusted between treatments of the same substrate in the same processing chamber.

The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure.