Plasma etching device and etching method

Abstract

This invention provides a plasma etching apparatus and method, applicable to the field of plasma etching technology. The etching apparatus includes a reaction chamber, with a pair of upper and lower electrodes arranged parallel to each other at the top and bottom. The upper electrode includes a gas spraying area for spraying gas downwards and an edge area surrounding the gas spraying area. Above the edge area are several circumferentially distributed magnetic field generating components, which generate magnetic fields that can penetrate the edge area and enter the reaction chamber. Above the upper electrode is a rotating component that drives each magnetic field generating component to move synchronously along the circumferential direction of the edge area. This invention can generate higher density plasma at the wafer edge, thereby increasing the etching rate at the wafer edge and improving the uniformity of etching in the wafer center and at the edge.

Description

Technical Field

[0001] This invention relates to the field of plasma etching technology, and more particularly to a plasma etching apparatus and etching method. Background Technology

[0002] Currently, dry etching using plasma has become the mainstream etching process due to its ability to effectively control the size of the etching openings. Existing plasma etching equipment typically uses radio frequency (RF) signals to generate plasma and apply a bias voltage to the substrate, enabling the plasma to bombard the substrate and thus etch it. Among these, capacitively coupled plasma (CCP) etching equipment is widely used in the dry etching field due to its simple structure and relatively low cost.

[0003] Figure 1 The diagram illustrates the reaction chamber of a conventional capacitively coupled plasma etching (CAPE) apparatus. A pair of planar upper electrodes 10' and lower electrodes 20' are arranged parallel to each other at the top and bottom of the reaction chamber. After placing the wafer to be etched between the upper and lower electrodes, at least one radio frequency (RF) source is connected to the lower electrode 20' while the upper electrode 10' is grounded. This generates an RF electric field to ionize the reactive gas entering the reaction chamber and generate etching plasma. However, during wafer etching, the plasma density at the wafer edges tends to be relatively low. This results in a faster processing rate in the wafer center and a slower processing rate at the wafer edges, leading to different performance characteristics of semiconductor devices formed in different areas of the wafer. Therefore, it is necessary to adjust the uniformity of the plasma etching process. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a plasma etching apparatus and etching method to improve the uniformity of wafer etching.

[0005] To achieve the above objectives, the present invention adopts the above technical solution:

[0006] In a first aspect, the present invention provides a plasma etching apparatus, the etching apparatus comprising a reaction chamber, wherein a pair of upper electrodes and lower electrodes are arranged parallel to each other at the top and bottom of the reaction chamber, the upper electrode comprising a gas spraying zone for spraying gas downwards and an edge zone surrounding the gas spraying zone, wherein:

[0007] Above the edge region are several magnetic field generating components distributed circumferentially. The magnetic field generating components are used to generate a magnetic field, and the magnetic field can pass through the edge region and enter the reaction chamber.

[0008] A rotating component is also provided above the upper electrode, which is used to drive each of the magnetic field generating components to move synchronously along the circumferential direction of the edge region.

[0009] Furthermore, the magnetic field generating component is a permanent magnet, wherein the N pole and S pole of adjacent permanent magnets are arranged opposite each other.

[0010] Furthermore, the magnetic field generating component is an electromagnetic coil.

[0011] Furthermore, the rotating component includes:

[0012] Several mounting plates are disposed above the edge region, and the magnetic field generating components are mounted on the mounting plates one by one.

[0013] A rotating bracket is disposed above the gas spray area. The rotating bracket is connected to several mounting plates and is used to drive the several mounting plates to move synchronously along the circumferential direction of the edge area.

[0014] Furthermore, the top surface of the rotating bracket is higher than the top surface of the mounting plate, so that the rotating bracket and the mounting plate form a step.

[0015] Furthermore, a lifting mechanism for driving the rotating component to rise and fall is provided above the upper electrode.

[0016] Secondly, the present invention provides a plasma etching method, which is implemented based on a plasma etching apparatus. The etching apparatus includes a reaction chamber, and a pair of upper and lower electrodes are arranged parallel to each other at the top and bottom of the reaction chamber. The upper electrode includes a gas spraying area for spraying gas downwards and an edge area surrounding the gas spraying area. The etching method includes:

[0017] Several magnetic field generating components are arranged circumferentially above the edge region, wherein the magnetic field generating components are used to generate a magnetic field and the magnetic field can pass through the edge region and enter the reaction chamber;

[0018] The wafer is placed inside the reaction chamber;

[0019] Etching parameters are set, and etching gas is introduced into the reaction chamber through the gas spray zone to etch the wafer according to the etching parameters. During the etching process, each of the magnetic field generating components moves synchronously along the circumferential direction of the edge region under the drive of the rotating component. The etching parameters include the target rotation speed of the rotating component.

[0020] Furthermore, the magnetic field generating component is a permanent magnet, wherein the N poles and S poles of adjacent permanent magnets are arranged opposite each other; or,

[0021] The magnetic field generating component is an electromagnetic coil.

[0022] Furthermore, the method further includes: providing a lifting mechanism above the upper electrode for driving the rotating component to rise and fall, wherein the etching parameters include the target lifting height of the rotating component.

[0023] Furthermore, during the etching process, one of the upper electrode and the lower electrode is grounded, and the other is connected to an RF power source. The etching parameters include the frequency and power of the RF power source.

[0024] By adopting the above technical solution, the present invention has the following beneficial effects:

[0025] The present invention provides several magnetic field generating components arranged circumferentially above the edge region. The magnetic field generated by each magnetic field generating component can pass through the edge region and enter the reaction chamber, and can move circumferentially with it under the action of the rotating component. The circumferentially moving magnetic field can deflect the charged ions generated by capacitive coupling near the upper electrode edge region inside the reaction chamber to assist in the dissociation of plasma. Therefore, it can excite a higher density plasma at the wafer edge, thereby improving the etching rate at the wafer edge and enhancing the uniformity of etching in the wafer center region and edge region. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a traditional capacitively coupled plasma etching device.

[0027] Figure 2A This is a schematic diagram of the plasma etching apparatus according to Embodiment 1 of the present invention;

[0028] Figure 2B This is a schematic diagram of the layout of the permanent magnet in Embodiment 1 of the present invention;

[0029] Figure 2C This is a schematic diagram of the magnetic field lines of the magnetic field generated in Embodiment 1 of the present invention;

[0030] Figure 3A This is a schematic diagram of the layout of an electromagnetic coil in Embodiment 2 of the present invention;

[0031] Figure 3B This is a schematic diagram of another layout of the electromagnetic coil in Embodiment 2 of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 10, 10', Upper electrode; 11, Gas inlet; 20, 20', Lower electrode; 30, Wafer; 40, Magnetic field generating component; 50, Rotating component; 51, Mounting plate; 52, Rotating support; 60, Gas buffer chamber; S1, Gas spray zone; S2, Edge zone. Detailed Implementation

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0036] As mentioned earlier, when using existing capacitively coupled plasma (CCP) etching equipment for wafer etching, it is easy to cause the relatively low plasma density at the wafer edge. This results in a faster processing rate in the wafer center area and a slower processing rate in the wafer edge area, leading to different performance of semiconductor devices formed in different areas of the wafer.

[0037] Based on this, the present invention provides an improved plasma etching apparatus and etching method to increase the etching rate at the wafer edge, thereby improving the uniformity of wafer etching.

[0038] Example 1

[0039] This embodiment provides a plasma etching apparatus, such as... Figure 2A As shown, the etching apparatus includes a reaction chamber, and a pair of upper electrodes 10 and lower electrodes 20 are arranged parallel to each other at the top and bottom of the reaction chamber. Both the upper electrode 10 and the lower electrode 20 are circular electrode plates, coaxially arranged within the reaction chamber. During etching, the wafer 30 is coaxially positioned above the lower electrode 20.

[0040] See Figure 2A and Figure 2B As shown, the upper electrode 10 in this embodiment includes a circular gas spraying area S1 located in its central region and an annular edge area S2 surrounding the gas spraying area S1, wherein the gas spraying area S1 is used to spray gas downwards.

[0041] Unlike traditional CCP etching equipment, such as Figures 2A-2CAs shown, in this embodiment, a plurality of magnetic field generating components 40 are provided above the edge region S2 of the upper electrode 10, which are distributed circumferentially (preferably uniformly). These magnetic field generating components 40 are used to generate a magnetic field. It should be understood that the generated magnetic field can pass through the edge region S2 of the upper electrode 10 and enter the interior of the reaction chamber, and the intensity will be strongest near the edge region S2.

[0042] Specifically, in this embodiment, the magnetic field generating component 40 is implemented using permanent magnets, wherein the N poles (i.e., north poles) and S poles (i.e., south poles) of adjacent permanent magnets are arranged opposite each other to generate magnetic field lines pointing from the N poles to the opposite S poles (see...). Figure 2C The resulting magnetic field lines can extend through the edge region S2 of the upper electrode 10 into the interior of the reaction chamber, and the direction of the magnetic field lines will not change.

[0043] In an optional embodiment, the area of ​​the gas spray region S1 is greater than 80% of the area of ​​the wafer 30. The permanent magnets are generally square and their length direction preferably extends radially along the upper electrode 10. The number of permanent magnets n is preferably an even number, and n / 2 is preferably an integer greater than 2, or n / 4 is preferably an integer greater than 2. Of course, the permanent magnets can also be constructed into any other suitable shape, and this embodiment does not impose any specific limitations on this.

[0044] Furthermore, in this embodiment, a rotating component 50 is provided above the upper electrode 10 to drive each magnetic field generating component 40 to move synchronously along the circumferential direction of the edge region S2. It should be understood that when the magnetic field generating component 40 rotates, the magnetic field it generates will also rotate. The rotating magnetic field will deflect the charged ions generated by capacitive coupling near the edge region S2 inside the reaction chamber to assist in the dissociation of plasma, thereby exciting a higher density plasma. The higher density plasma can produce a faster etching rate at the edge of the wafer 30.

[0045] exist Figure 2A In the illustrated embodiment, the rotating component 50 includes several mounting plates 51 circumferentially disposed above the edge region S2 of the upper electrode 10, for each magnetic field generating component 40 to be mounted on a corresponding mounting plate 51. Furthermore, the rotating component 50 also includes a rotating bracket 52 disposed above the gas spray region S1. This rotating bracket 52 is connected to each mounting plate 51 to drive each mounting plate 51 to move synchronously along the circumferential direction of the edge region S2, thereby driving each magnetic field generating component 40 to rotate along the edge region S2. Preferably, the rotating bracket 52 rotates under the drive of a motor.

[0046] See again Figure 2A As shown, a gas buffer chamber is formed above the gas spray zone S1 of the upper electrode 10. This gas buffer chamber is connected to an external gas supply device (not shown) to provide etching gas. The etching gas includes, but is not limited to, Cl2, BCl3, and A.r One or more of N2 are used. At the same time, the gas spray zone S1 is uniformly provided with a number of air inlets 11 that communicate with the gas buffer chamber 60, so that the etching gas in the gas buffer chamber 60 can enter the reaction chamber through these air inlets 11 and generate plasma under the action of magnetic and electric fields.

[0047] In this embodiment, the rotating bracket 52 is disposed above the gas buffer chamber 60, and its circumferential edge extends downward to connect with the mounting plate 51. That is, the top surface of the rotating bracket 52 is higher than the top surface of the mounting plate 51, so that the rotating bracket 52 and the mounting plate 51 form a step. In this way, the mounting plate 51 will be closer to the upper electrode 10 relative to the rotating bracket 52. That is, the magnetic field generating component 40 is relatively closer to the upper electrode 10, thereby ensuring the magnetic field strength entering the reaction chamber.

[0048] It should be understood that by adjusting the rotation speed of the rotating support 52, the intensity of the magnetic field dissociation plasma can be adjusted, thereby adjusting the etching rate of the edge of the wafer 30.

[0049] In one feasible embodiment, a lifting mechanism (not shown) is provided above the upper electrode 10 to drive the rotating component 50 up and down. The lifting mechanism, for example, driven by a cylinder or motor, drives the rotating component 50 up and down, thereby causing the entire magnetic field generating component 40 to rise and fall accordingly, thus adjusting the magnetic field strength entering the reaction chamber. Specifically, when moving downwards, the magnetic field induction can be enhanced; when moving upwards, the magnetic field induction can be reduced, thereby adjusting the etching rate at the edge of the wafer 30.

[0050] As can be seen, this embodiment provides several circumferentially distributed magnetic field generating components 40 above the edge region S2. Since the magnetic field generated by each magnetic field generating component 40 can pass through the edge region S2 and enter the reaction chamber, it can move circumferentially under the action of the rotating component 50. The circumferentially moving magnetic field can deflect the charged ions generated by capacitive coupling near the edge region S2 of the upper electrode 10 inside the reaction chamber to assist in the dissociation of plasma. Therefore, it can excite a higher density plasma at the edge of the wafer 30, improve the etching rate at the edge of the wafer 30, and thus improve the uniformity of etching in the central region and edge of the wafer 30. Moreover, the structure is simple and the cost is low, which is conducive to large-scale application in the semiconductor industry.

[0051] Example 2

[0052] This embodiment provides a plasma etching apparatus, which differs from Embodiment 1 in that... Figure 3A and Figure 3B As shown, the magnetic field generating component 40 in this embodiment is implemented using an electromagnetic coil instead of a permanent magnet.

[0053] It should be understood that the magnetic field generated by the energized electromagnetic coil can also penetrate the edge region S2 and enter the reaction chamber. Under the action of the rotating component 50, it can move circumferentially. This circumferentially moving magnetic field deflects the charged ions generated by capacitive coupling near the edge region S2 of the upper electrode 10 inside the reaction chamber, assisting in the dissociation of the plasma. This allows for the generation of a higher density plasma at the edge of the wafer 30, thereby increasing the etching rate at the edge of the wafer 30. Figure 3A and Figure 3B The arrow in the diagram indicates the rotation direction of the rotating component 50, which is also the rotation direction of the magnetic field.

[0054] In one feasible embodiment, the electromagnetic coil is generally square, and its length or width can extend radially along the upper electrode 10 (e.g., Figure 3A As shown), it can also not extend radially along the upper electrode 10 (i.e., form a certain angle with the radial direction, such as...). Figure 3B (As shown). The number of electromagnetic coils, n, is an even number, and n / 2 is preferably an integer greater than 2, or n / 4 is preferably an integer greater than 2. Of course, the electromagnetic coils can also be constructed into any other suitable shape (such as a circle), and this embodiment does not impose any specific restrictions on this.

[0055] Example 3

[0056] This embodiment provides a plasma etching method for etching wafer 30 using a plasma etching apparatus. Wherein, as... Figure 2A As shown, the etching apparatus includes a reaction chamber, and a pair of upper electrodes 10 and lower electrodes 20 are arranged in parallel at the top and bottom of the reaction chamber. The upper electrode 10 includes a gas spraying zone S1 for spraying gas downward and an edge zone S2 surrounding the gas spraying zone S1.

[0057] The etching method in this embodiment specifically includes the following steps:

[0058] Step 1: Several magnetic field generating components 40 distributed circumferentially are arranged above the edge region S2 of the upper electrode 10. The magnetic field generating components 40 are used to generate a magnetic field and the magnetic field can pass through the edge region S2 and enter the reaction chamber.

[0059] In one feasible manner, such as Figure 2B and Figure 2C As shown, the magnetic field generating component 40 is implemented using permanent magnets, wherein the N poles and S poles of adjacent permanent magnets are arranged opposite each other to generate magnetic field lines pointing from the N pole to the opposite S pole. It should be understood that the generated magnetic field lines can extend through the edge region S2 of the upper electrode 10 into the interior of the reaction chamber, and the direction of the magnetic field lines does not change.

[0060] Preferably, such as Figure 2BAs shown, the permanent magnet is generally square and its length direction preferably extends radially along the upper electrode 10, but this embodiment does not impose any specific restrictions on this.

[0061] In another feasible approach, such as Figure 3A and Figure 3B As shown, the magnetic field generating component 40 is implemented using an electromagnetic coil. The magnetic field generated by the energized electromagnetic coil can also pass through the edge region S2 and enter the interior of the reaction chamber.

[0062] Preferably, the electromagnetic coil is generally square, and its length or width can extend radially along the upper electrode 10 (e.g., Figure 3A As shown), it can also not extend radially along the upper electrode 10 (i.e., form a certain angle with the radial direction, such as...). Figure 3B (As shown). Of course, the electromagnetic coil can also be constructed into any other suitable shape (such as a circle), and this embodiment does not impose any specific limitations on this.

[0063] Furthermore, in this embodiment, a rotating component 50 is provided above the upper electrode 10 to drive each magnetic field generating component 40 to move synchronously along the circumferential direction of the edge region S2. It should be understood that when the magnetic field generating component 40 rotates, the magnetic field it generates will also rotate. The rotating magnetic field will deflect the charged ions generated by capacitive coupling near the edge region S2 inside the reaction chamber to assist in the dissociation of plasma, thereby exciting a higher density plasma. The higher density plasma can produce a faster etching rate at the edge of the wafer 30.

[0064] Step 2: Place the wafer 30 inside the reaction chamber, specifically by fixing it above the lower electrode 20 using a base such as an electrostatic chuck.

[0065] Step 3: Set the etching parameters and introduce etching gas into the reaction chamber through the gas spray zone S1 to etch the wafer 30 according to the etching parameters. During the etching process, each magnetic field generating component 40 is driven by the rotating component 50 to move synchronously along the edge region S2 to generate a rotating magnetic field. One of the upper electrode 10 and the lower electrode 20 is grounded, and the other is connected to an RF power source, thereby generating an RF electric field between the upper electrode 10 and the lower electrode 20. This ionizes the etching gas introduced into the reaction chamber to form plasma, which then etches the wafer 30 placed between the upper electrode 10 and the lower electrode 20 and supported by the base.

[0066] The etching parameters set include, but are not limited to, the frequency and power of the radio frequency power source, the cavity pressure of the reaction chamber, the type and flow rate of the etching gas, etc. In addition, the etching parameters also include the target rotation speed of the rotating component 50. By adjusting the target rotation speed, the intensity of the magnetic field dissociation plasma can be adjusted, thereby adjusting the etching rate at the edge of the wafer 30.

[0067] In one feasible embodiment, the etching method further includes: a lifting mechanism above the upper electrode 10 for driving the rotating component 50 to move up and down. This lifting mechanism, for example, driven by a cylinder or motor, drives the rotating component 50 to move up and down, thereby causing the magnetic field generating component 40 to move up and down accordingly, thus adjusting the magnetic field strength entering the reaction chamber. Specifically, downward movement enhances the magnetic field induction, while upward movement reduces the magnetic field induction, thereby adjusting the etching rate at the edge of the wafer 30. Furthermore, the aforementioned etching parameters also include a target lifting height of the rotating component 50. By adjusting this target lifting height, the intensity of the magnetic field dissociation plasma can be adjusted, thereby adjusting the etching rate at the edge of the wafer 30.

[0068] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A plasma etching apparatus, the etching apparatus comprising a reaction chamber, wherein a pair of upper electrodes and lower electrodes are arranged parallel to each other at the top and bottom of the reaction chamber, the upper electrode comprising a gas spraying zone for spraying gas downwards and an edge zone surrounding the gas spraying zone, characterized in that, Above the edge region are several magnetic field generating components distributed circumferentially. The magnetic field generating components are used to generate a magnetic field, and the magnetic field can pass through the edge region and enter the reaction chamber. The magnetic field is strongest near the edge region. A rotating component is also provided above the upper electrode. The rotating component is used to drive each of the magnetic field generating components to move synchronously along the circumferential region of the edge area. The circumferentially moving magnetic field deflects the charged ions generated by capacitive coupling near the edge area of ​​the upper electrode inside the reaction chamber to assist in the dissociation of plasma and to excite a higher density plasma at the wafer edge, thereby improving the etching rate of the wafer edge.

2. The plasma etching apparatus according to claim 1, characterized in that, The magnetic field generating component is a permanent magnet, wherein the N pole and S pole of adjacent permanent magnets are arranged opposite each other.

3. The plasma etching apparatus according to claim 1, characterized in that, The magnetic field generating component is an electromagnetic coil.

4. The plasma etching apparatus according to claim 1, characterized in that, The rotating component includes: Several mounting plates are disposed above the edge area, and the magnetic field generating components are mounted on the mounting plates one by one. A rotating bracket is disposed above the gas spray area. The rotating bracket is connected to several mounting plates and is used to drive the several mounting plates to move synchronously along the circumferential direction of the edge area.

5. The plasma etching apparatus according to claim 4, characterized in that, The top surface of the rotating bracket is higher than the top surface of the mounting plate, so that the rotating bracket and the mounting plate form a step.

6. The plasma etching apparatus according to claim 1, characterized in that, Above the upper electrode, there is also a lifting mechanism for driving the rotating component to rise and fall.

7. A plasma etching method, the method being implemented using a plasma etching apparatus, the etching apparatus comprising a reaction chamber, wherein a pair of upper and lower electrodes are arranged parallel to each other at the top and bottom of the reaction chamber, the upper electrode comprising a gas spraying zone for spraying gas downwards and an edge zone surrounding the gas spraying zone, characterized in that, The etching method includes: Several magnetic field generating components are arranged circumferentially above the edge region, wherein the magnetic field generating components are used to generate a magnetic field and the magnetic field can pass through the edge region and enter the reaction chamber, and the magnetic field is strongest near the edge region; The wafer is placed inside the reaction chamber; Etching parameters are set, and etching gas is introduced into the reaction chamber through the gas spray zone to etch the wafer according to the etching parameters. During the etching process, each of the magnetic field generating components moves synchronously along the circumferential region of the edge area under the drive of the rotating component. The circumferentially moving magnetic field deflects the charged ions generated by capacitive coupling near the edge area of ​​the upper electrode inside the reaction chamber to assist in the dissociation of plasma. Therefore, a higher density plasma can be excited at the edge of the wafer, thereby improving the etching rate of the wafer edge. The etching parameters include the target rotation speed of the rotating component.

8. The plasma etching method according to claim 7, characterized in that, The magnetic field generating component is a permanent magnet, wherein the N poles and S poles of adjacent permanent magnets are arranged opposite to each other; Alternatively, the magnetic field generating component may be an electromagnetic coil.

9. The plasma etching method according to claim 7, characterized in that, The method further includes: providing a lifting mechanism above the upper electrode for driving the rotating component to rise and fall, wherein the etching parameters include the target lifting height of the rotating component.

10. The plasma etching method according to claim 7, characterized in that, During the etching process, one of the upper and lower electrodes is grounded, and the other is connected to an RF power source. The etching parameters include the frequency and power of the RF power source.

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