TW201946084A - Capacitive coupled plasma processing system with adjustable electrode pitch and method thereof capable of avoiding asymmetric etching caused by slit door and effectively constraining plasma at slit door - Google Patents

Abstract

The present invention discloses a capacitive coupled plasma processing system with adjustable electrode plate pitch and a method thereof. The system comprises: an upper electrode, a lower electrode, a bridge ring, an outer ring guiding rail, a ground ring, and a slit door. The lower electrode is connected to the outer ring guiding rail through the bridge ring so as to form a lower electrode system. The outer ring guiding rail moves up and down along the inner wall of the etching chamber and is disposed with a ground ring at a specific position, so as to fix the outer ring guiding rail onto the ground ring to complete the grounding state. At this time, the outer ring guiding rail may completely block and shield the slit door. The system of the present invention may overcome the defects in the prior art, such as the asymmetric issue in etching process caused by being unable to avoid the slit door and the invalid constraint of the plasma at the slit door while the etching process requires a relatively large electrode plate gap.

Description

Capacitively coupled plasma processing system with adjustable electrode plate spacing and method thereof

Plasma etching, plasma confinement system.

The distance between the plates of a conventional capacitively coupled plasma etching machine cannot be adjusted online in real time, which greatly limits the process range of the etching machine and the compatibility with different processes. The basic idea of a plasma etching machine with adjustable plate spacing is to adjust the plate spacing by fixing the lower electrode or adjusting the lower electrode by fixing the upper electrode. Taking the latter as an example, the process of adjusting the gap between the plates by moving the lower electrode (Lower Cathode) is described with reference to the drawings:

As shown in FIG. 1, the lower electrode 2 is moved below the Slit door 5 to complete the wafer 3 introduction process; at this time, the electrode plate spacing is h1.

As shown in FIG. 2, the lower electrode 2 is moved up to the required position of the process to complete the etching process; at this time, the electrode plate spacing is h2.

Move the lower electrode 2 down again to a position where the plate spacing is h1. As shown in FIG. 1, the wafer 3 transfer process is completed.

A basic logical idea of the above operation process is to realize a wide range of adjustment of the electrode plate spacing through a simple lower electrode movement. During the movement of the lower electrode 2, in order to ensure the unblocking of the RF path and the reliability of the plasma confinement system to the plasma confinement, it is necessary to use a bridge ring 4 (such as copper or aluminum wire material) composed of multiple low-impedance metal conductors. The plasma confinement system 11 surrounding the lower electrode 2 is connected to the cavity. The plasma confinement system 11 includes a conductor. Finally, the lower electrode 2 is connected to the ground of the side wall of the reaction chamber through the conductor and the bridge ring in the plasma confinement system. Only the length of the bridge ring 4 in this path is affected by the vertical movement of the lower electrode. The limitation cannot be shortened, and eventually the inductance on this path is large, and the impedance of high-frequency RF power flow is also large. The impedance of the bridge loop 4 determines the patency of the entire cavity RF circuit, thereby affecting the confinement effect of the plasma. Obviously, when the moving range of the lower electrode 2 is increased, the length and impedance of the bridge loop 4 are increased accordingly, thereby weakening the confinement effect of the plasma. Typically, the larger length of the bridged loop 4 has a greater impedance to the plasma source frequency (60 MHz), and therefore more affects the restraint ability of the 60 MHz plasma.

In addition, the above operation process has two relatively large defects. The first is that it can avoid the Slit door 5 and the asymmetry of the etching process caused by the asymmetry of the cavity. The second is that when the electrode plate spacing required by the etching process is large, the plasma confinement system 11 reaches the pass. An effective loop cannot be formed between the gates 5, and the problem of the plasma ineffective constraint becomes very obvious. Based on this, the present invention proposes a capacitively-coupled plasma etching system with adjustable electrode plate spacing and a method thereof.

The present invention proposes a capacitively-coupled plasma processing system with adjustable electrode plate pitch for the adjustable electrode plate pitch etching mechanism, which overcomes the problem of asymmetry of etching process and etching caused by the unregulated pass gate in the traditional technical solution. Defects such as ineffective plasma confinement at the pass gate when the electrode plate spacing required for the etching process is large.

In order to achieve the above objective, the present invention is achieved by the following technical solutions:

Provided is a capacitively-coupled plasma processing system with adjustable electrode plate spacing. The system includes: a cavity, an upper electrode, a lower electrode, a bridged ring, an outer ring guide, a slide gate, and a ground ring.

The upper electrode is in the upper part of the cavity, and the lower electrode is in the pedestal carrying the wafer in the lower part of the cavity;

The outer ring guide moves up and down along the cavity wall; the lower electrode moves up and down in the cavity; a bridge ring is provided between the lower electrode and the outer ring guide;

A wafer transfer gate is opened on one side of the cavity wall, so that the wafer is introduced into the cavity through the wafer transfer gate and placed at the lower electrode moved to the first position, or the wafer is transferred from the lower position of the first position through the wafer transfer gate. The electrode is transmitted outside the cavity;

When the lower electrode is moved to the second position, the outer ring guide moves upward to a grounding position that is electrically connected to the ground ring, so that the lower electrode is grounded through the bridge ring, the outer ring guide, and the ground ring;

When the lower electrode is moved to a third position higher than the second position, the position required for processing is reached, and during movement of the lower electrode between the second position and the third position, the outer ring guide is maintained and grounded. Ground connection for electrical connection of the ring.

Preferably, when the lower electrode moves up and down in the cavity, the position of the upper electrode is fixed.

Preferably, the bridge ring is deformed during the movement of the lower electrode between the second position and the third position.

Preferably, the outer ring guide rail moved to the grounding position is sufficient to completely cover the film transfer door.

Preferably, the grounding position of the outer ring guide is an upper limit position where the outer ring guide moves along the cavity wall.

Preferably, the outer ring guide rail is in electrical contact with a ground ring provided on the cavity wall at a grounded position.

Preferably, the outer ring guide rail is in electrical contact with the ground ring through a washer provided on the upper ring rail.

Preferably, when the lower electrode is in the first position, the lower electrode, the outer ring guide and the bridge ring are respectively located below the wafer transfer gate, so that the wafer can be transferred into or out of the cavity.

A capacitively coupled plasma processing method with adjustable electrode plate spacing, the steps include:

S1. Move the lower electrode and the outer ring guide below the wafer transfer gate, introduce the wafer into the cavity and place it at the lower electrode;

S2. Move the lower electrode and the outer ring guide until the outer ring guide reaches the grounded position, and the film transfer door is completely blocked by the outer ring guide;

S3. Move the lower electrode until it reaches the position required for the process and keep the outer ring guide in its grounded position. By applying the power of the RF source to the lower electrode or one of the upper electrodes, the reactive gas introduced into the cavity is excited to form a plasma. Body to process wafers.

Preferably, after the wafer processing is completed, the method further includes the following processes:

S4. Move the lower electrode, return the lower electrode to the position at step S2, and keep the outer ring guide in its grounded position during the movement of the lower electrode;

S5. Move the lower electrode and the outer ring guide, return the lower electrode and the outer ring guide to the position at step S1, and perform the wafer transfer operation through the wafer transfer gate.

Preferably, the outer ring guide rail is in electrical contact with the ground ring on the cavity wall at its grounding position.

Preferably, the distance between the upper electrode and the lower electrode is h1 in step S1, the distance between the upper electrode and the lower electrode is h2 in step S2, and the distance between the upper electrode and the lower electrode is h3 in step S3, where h1> h2> h3.

Preferably, the frequency of the power of the RF source is 60 MHz or more.

A capacitively-coupled plasma processing system with adjustable electrode plate spacing, the system includes: a cavity, an upper electrode, a lower electrode, a bridged ring, an outer ring guide, a slide gate and a ground ring;

The upper electrode is in the upper part of the cavity, and the lower electrode is in the pedestal carrying the wafer in the lower part of the cavity;

The outer ring guide moves up and down along the cavity wall; the lower electrode moves up and down in the cavity; a bridge ring is provided between the lower electrode and the outer ring guide;

The first driving device drives the lower electrode to move between the first position and the second position, and the second driving device drives the outer ring guide to move between the third position and the fourth position, wherein the moving range of the lower electrode is greater than A moving range of the outer ring guide rail;

A wafer transfer gate is opened on one side of the cavity wall, so that the wafer is introduced into the cavity through the wafer transfer gate and placed at the lower electrode moved to the first position, or the wafer is transferred from the lower position of the first position through the wafer transfer gate. The electrode is transmitted outside the cavity;

When the outer ring guide moves upward from the third position to the fourth position, it is electrically connected to the ground ring, so that the lower electrode is grounded through the bridge ring, the outer ring guide, and the ground ring; the lower electrode moves further upward When the outer ring guide stays at the fourth position, the bridge ring deforms and extends, and maintains the electrical connection between the outer ring guide and the lower electrode.

Preferably, when the outer ring guide rail is in the fourth position, the film transfer door is completely blocked.

The invention proposes a capacitively-coupled plasma etching system with adjustable electrode plate spacing and a method thereof in accordance with an adjustable electrode plate spacing etching mechanism. The system and method have the following advantages:

Through the flexible grounding process of the outer ring guide rail, the length of the bridge ring can be reduced to the greatest extent, and the ability of the etching system to restrain high-frequency plasma such as 60 MHz can be enhanced;

The grounded outer ring guide can be used for effective shielding and masking of the film transfer door at the same time, thereby eliminating many problems introduced by the etching machine's film transfer door, such as asymmetry of the etching process, plasma leakage constraints, and polymer (Polymer ) Particle problems caused by deposition.

The present invention will be further described below in detail with reference to the accompanying drawings by explaining a preferred specific implementation case in detail.

As shown in FIG. 4, the present invention proposes a capacitively-coupled plasma processing system and a method capable of adjusting the distance between the plates according to an adjustable mechanism for the distance between the plates. The system includes an etching cavity and an upper electrode 1. , Lower electrode 2, bridge ring 4, outer ring guide 6, sheet transfer door 5, ground ring 8, washer 7.

The upper electrode 1 is in the upper part of the cavity, and the lower electrode 2 is in the pedestal carrying the wafer 3 in the lower part of the cavity. A slide door 5 is set on one side of the cavity wall. The lower electrode 2 is connected to an outer ring guide 6 through a bridge 4. The position of the upper electrode 1 is fixed, the lower electrode 2 moves up and down in the etching cavity, the outer ring guide 6 moves up and down along the cavity wall, and the bridge ring 4 moves together with the lower electrode 2 and the outer ring guide 6. A washer 7 is provided on an upper portion of the outer ring guide 6, and a ground ring 8 is provided at an upper limit position of the outer ring guide 6, so that the outer ring guide 6 contacts the ground ring 8 through the washer 7 to complete a grounding state. When the outer ring guide 6 is in the upper limit position and is in contact with the ground ring, it can completely cover the sheet transfer door 5.

The lower electrode 2 has three positions. As shown in FIG. 4, when the outer ring guide 6 is at a position below the wafer transfer gate 5, the lower electrode 2 is also at a position below the wafer transfer gate 5 to perform operations such as wafer 3 ingress and egress. As shown in FIG. 5, when the outer ring guide 6 is in a position that completely covers the sheet transfer door 5, the lower electrode 2 also moves to a position where the top of the lower electrode 2 is flush with the upper part of the outer ring guide 6; in this example, the outer ring The moving speed of the guide rail 6 and the lower electrode 2 remains the same, and the bridge ring 4 is also deformed. As shown in FIG. 6, the outer ring guide rail 6 completely covers the film transfer door 5 and stops moving, and the lower electrode 2 continues to move to the required position in the manufacturing process. At this time, the bridge ring 4 is deformed.

The bridge ring 4 and the lower electrode 2 are driven by two independent sets of driving mechanisms, which can be lifted or unsynchronized. The bridge ring 4 is deformed during the asynchronous lift, and the relative position between the outer ring guide 6 and the lower electrode 2 It will change. The outer ring guide 6 is a barrel-shaped conductor that can move up and down the entire inner wall of the reaction chamber, so that the airflow and electric field distribution in the reaction chamber have better uniformity.

The specific implementation method implements the electrode plate spacing adjustment process through the following steps:

S1. Move the lower electrode and the outer ring guide below the wafer transfer gate to carry out the wafer transfer operation. In this example, the top of the lower electrode and the top of the outer ring guide are on a horizontal line, and the distance between the electrode plates is h1.

S2. Move the lower electrode and the outer ring guide until the outer ring guide moves to the position of the ground ring (GND ring), and make the outer ring guide contact the ground ring through the gasket (Gasket) to complete the grounding state. At this time, the electrode plate spacing is h2; In this process, the lower electrode and the outer ring guide move at the same rate at the same time, and the bridge ring is not deformed at the same time. At the same time, the grounded outer ring guide realizes the blocking and shielding function of the film transfer door.

S3. Move the lower electrode up to the required position of the process and perform the etching process. At this time, the electrode plate spacing is h3. During this process, the outer ring guide stops and one end is stretched with the bridge ring moving up the lower electrode.

S4. Move the lower electrode down to the ground ring. At this time, the distance between the plates is h2. In this process, the ground outer ring guide remains unchanged.

S5. Move the lower electrode, bridge ring, and outer ring guide below the wafer transfer door to complete the wafer transfer operation. At this time, the electrode plate spacing is h1. In this process, the outer ring guide is separated from the ground ring, and the lower electrode and the The relative position of the outer ring guide remains unchanged, and the bridge ring is not deformed.

In this example, the relationship between the distance between the plates is h1> h2> h3. However, in other examples, the electrode plate spacing required by the etching process may be large. To this end, the lower electrode can be moved downward in S3, so that the electrode plate spacing is increased compared to S2.

The washer may be an elastic conductor ring surrounded by a metal conductor like a spring, so that the ground ring and the outer ring guide rail are stably electrically connected.

The above-mentioned method for adjusting the distance between the plates has the following advantages:

(1) Through the flexible grounding process of the outer ring guide, the length of the bridge ring depends on the difference between the distances between the plates h2 to h3. The length of the bridge ring can be minimized to reduce the impedance and enhance the etching system. Restraint ability of high frequency plasma above 60MHz.

(2) The grounded outer ring guide can be used for effective shielding and masking of the film transfer door at the same time, thereby eliminating many problems introduced by the film transfer door of the etching machine, such as asymmetry of the etching process, plasma leakage constraints, and polymerization Particle pollution caused by polymer deposition.

Although the content of the present invention has been described in detail through the above-mentioned preferred embodiments, it should be recognized that the above description should not be considered as limiting the present invention. After reading the above content by a person having ordinary knowledge in the art, various modifications and alternatives to the present invention will be apparent. Therefore, the protection scope of the present invention should be defined by the scope of the attached patent application.

1‧‧‧up electrode

11‧‧‧ Plasma confinement system

2‧‧‧ lower electrode

3‧‧‧ wafer

4‧‧‧Bridge Link

5‧‧‧ pass

6‧‧‧ outer ring guide

7‧‧‧ washer

8‧‧‧ ground ring

FIG. 1 is a schematic diagram of a conventional capacitor-coupled plasma processing machine with adjustable electrode plate spacing;

FIG. 2 is a schematic diagram of a process of adjusting a plate gap in a conventional capacitor-coupled plasma processor with adjustable plate gap;

FIG. 3 is a flowchart of a capacitive coupling plasma processing method with adjustable electrode plate spacing;

FIG. 4 is a schematic diagram of a completed wafer transfer operation of a capacitively-coupled plasma processing system with adjustable electrode pitch;

5 is a schematic diagram of an outer ring guide rail of a capacitively-coupled plasma processing system with adjustable electrode spacing and grounding through a washer;

FIG. 6 is a schematic diagram of moving a lower electrode system of a capacitively-coupled plasma processing system with adjustable electrode spacing to a position required for a manufacturing process.

Claims (15)

A capacitively coupled plasma processing system with adjustable electrode plate spacing, wherein the capacitively coupled plasma processing system with adjustable electrode plate spacing includes: a cavity, an upper electrode, a lower electrode, a bridged ring, and an outer ring guide rail , A pass gate, a ground ring; The upper electrode is in an upper part of the cavity, and the lower electrode is in a base for carrying a wafer in a lower part of the cavity; The outer ring guide moves up and down along a cavity wall; the lower electrode moves up and down in the cavity; the bridge ring is provided between the lower electrode and the outer ring guide; One side of the cavity wall is provided with the wafer transfer gate, so that the wafer is introduced into the cavity through the wafer transfer gate and placed at the lower electrode moved to a first position, or the crystal is passed through the wafer transfer gate. A circle is transmitted from the lower electrode in the first position to the outside of the cavity; When the lower electrode moves to a second position, the outer ring guide moves upward to a grounding position that is electrically connected to the ground ring, so that the lower electrode is grounded through the bridge ring, the outer ring guide, and the ground ring. ; When the lower electrode moves to a third position higher than the second position and reaches a position required for processing, and the lower electrode moves between the second position and the third position, the outer ring guide stays with The ground position of the electrical connection of the ground ring. The capacitively-coupled plasma processing system with adjustable electrode plate spacing as described in item 1 of the patent application scope, wherein the position of the upper electrode is fixed when the lower electrode moves up and down in the cavity. The capacitively-coupled plasma processing system with adjustable electrode spacing as described in item 1 of the patent application scope, wherein the bridge ring is deformed during the movement of the lower electrode between the second position and the third position. The capacitively-coupled plasma processing system with adjustable electrode spacing as described in item 1 of the scope of patent application, wherein the outer ring guide rail moved to the grounding position is sufficient to completely cover the film transfer door. The capacitively-coupled plasma processing system with adjustable electrode space as described in item 4 of the scope of patent application, wherein the grounding position of the outer ring guide is the upper limit position of the outer ring guide moving along the cavity wall. The capacitively-coupled plasma processing system with adjustable electrode spacing as described in the first or fourth or fifth aspect of the patent application scope, wherein the outer ring guide rail is electrically connected to the ground ring provided on the cavity wall at a grounded position. contact. The capacitively-coupled plasma processing system with adjustable electrode spacing as described in item 6 of the scope of patent application, wherein the outer ring guide rail is in electrical contact with the ground ring through a washer provided on the outer ring guide rail. The capacitively-coupled plasma processing system with adjustable electrode spacing according to item 1 of the scope of patent application, wherein when the lower electrode is in the first position, the lower electrode, the outer ring guide and the bridge ring are respectively located The position below the wafer transfer gate allows the wafer to pass into or out of the cavity. A method for capacitively-coupled plasma processing with adjustable electrode spacing, including the following steps: S1. Move the lower electrode and an outer ring guide below a wafer transfer gate, introduce a wafer into a cavity, and place it at the lower electrode; S2. Move the lower electrode and the outer ring guide until the outer ring guide reaches a grounded position, and completely shield the slide door through the outer ring guide; S3. Move the lower electrode until it reaches the position required for processing and keep the outer ring guide in its grounded position; by applying power of the RF source to the lower electrode or one of the upper electrodes, the The reaction gas is excited to form a plasma, and the wafer is processed. The capacitively-coupled plasma processing method with adjustable electrode spacing as described in item 9 of the scope of patent application, wherein after the wafer is processed, the method further includes the following steps: S4. Move the lower electrode, return the lower electrode to the position at step S2, and keep the outer ring guide in its grounded position during the movement of the lower electrode; S5. Move the lower electrode and the outer ring guide, return the lower electrode and the outer ring guide to the positions at step S1, and perform the wafer transfer operation through the wafer transfer gate. As described in item 9 of the scope of the patent application, the method for capacitively-coupled plasma processing with adjustable electrode spacing is provided, wherein the outer ring guide rail is in electrical contact with a grounding ring on a cavity wall at its grounding position. As described in item 9 or 10 of the scope of the patent application, the method for capacitively-coupled plasma processing with adjustable electrode spacing is described, wherein the distance between the upper electrode and the lower electrode is h1 in step S1, and the upper electrode and the electrode are in step S2. The distance between the lower electrodes is h2. In step S3, the distance between the upper electrode and the lower electrode is h3, where h1> h2> h3. As described in item 9 of the scope of the patent application, the method for capacitively-coupled plasma processing with adjustable electrode spacing is characterized in that the frequency of the power of the RF source is 60 MHz or more. A capacitively-coupled plasma processing system with adjustable electrode plate spacing, wherein the system includes: a cavity, an upper electrode, a lower electrode, a bridge ring, an outer ring guide, a slide gate, and a ground ring; The upper electrode is in an upper part of the cavity, and the lower electrode is in a base for carrying a wafer in a lower part of the cavity; The outer ring guide moves up and down along a cavity wall; the lower electrode moves up and down in the cavity; the bridge ring is provided between the lower electrode and the outer ring guide; A first driving device drives the lower electrode to move between a first position and a second position, and a second driving device drives the outer ring guide to move between a third position and a fourth position, where the lower The moving range of the electrode is larger than the moving range of the outer ring guide; One side of the cavity wall is provided with the wafer transfer gate, so that the wafer is introduced into the cavity through the wafer transfer gate and placed at the lower electrode moved to the first position, or the crystal is transferred through the wafer transfer gate. A circle is transmitted from the lower electrode in the first position to the outside of the cavity; When the outer ring guide is moved upward from the third position to the fourth position, electrical connection with the ground ring is achieved, so that the lower electrode is grounded through the bridge ring, the outer ring guide, and the ground ring; the lower electrode When moving further upward and the outer ring guide stays in the fourth position, the bridge ring deforms and extends, maintaining the electrical connection between the outer ring guide and the lower electrode. The capacitively-coupled plasma processing system with adjustable electrode spacing as described in item 14 of the scope of patent application, wherein the outer ring guide rail completely covers the film transfer door in the fourth position.