Plasma etching equipment and etching method

Abstract

The invention provides plasma etching equipment and an etching method, which are applied to the technical field of plasma etching.The plasma etching equipment comprises a reaction cavity, and a pair of upper electrode and lower electrode is arranged at the top and the bottom of the reaction cavity in parallel; the upper electrode comprises a gas spraying area and an edge area, the gas spraying area is used for spraying gas downwards, the edge area surrounds the gas spraying area, a plurality of magnetic field generating parts distributed in the circumferential direction are arranged above the edge area, the magnetic field generating parts are used for generating a magnetic field, and the magnetic field can penetrate through the edge area to enter the reaction cavity; a rotating part is further arranged above the upper electrode and used for driving the magnetic field generating parts to synchronously move in the circumferential direction of the edge area. According to the invention, the plasma with higher density can be excited at the edge of the wafer, so that the etching rate of the edge of the wafer is improved, and the etching uniformity of the central region and the edge of the wafer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma etching, and in particular to a plasma etching device and an etching method. Background Art

[0002] At present, the dry etching process using plasma for etching has become the mainstream etching process because it can effectively control the size of the etching opening. In existing plasma etching equipment, radio frequency signals are usually used to form plasma, and radio frequency signals are used to form a bias voltage on the substrate to be processed so that the plasma can bombard the substrate to be processed, thereby achieving etching of the substrate to be processed. Among them, capacitively coupled plasma (CCP) etching equipment has been widely used in the field of dry etching due to its simple structure and relatively low cost.

[0003] Figure 1 The reaction chamber of the existing capacitively coupled plasma etching equipment is shown, and a pair of flat upper electrodes 10' and lower electrodes 20' are arranged in parallel at the top and bottom of the reaction chamber. After the wafer to be etched is placed between the upper electrode and the lower electrode, at least one radio frequency source is connected to the lower electrode 20', and the upper electrode 10' is grounded, so that a radio frequency electric field can be generated to ionize the reaction gas entering the reaction chamber and generate plasma for etching. However, when etching the wafer, it is easy to cause the plasma density at the edge of the wafer to be relatively low, so that the processing rate on the center area of ​​the wafer is faster, while the processing rate on the edge area of ​​the wafer is slower, resulting in different performances of semiconductor devices formed in different areas on the wafer, so it is necessary to adjust the uniformity of plasma etching. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a plasma etching device and an etching method to improve the uniformity of wafer etching.

[0005] In order to achieve the above purpose, the present invention adopts the above technical solution: In a first aspect, the present invention provides a plasma etching device, the etching device comprising a reaction chamber, a pair of upper electrodes and a lower electrode are arranged in parallel at the top and bottom of the reaction chamber, the upper electrode comprises a gas spraying area for spraying gas downward and an edge area surrounding the gas spraying area, wherein: A plurality of magnetic field generating components distributed in the circumferential direction are provided above the edge region, and 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; A rotating component is also provided above the upper electrode, and the rotating component is used to drive each of the magnetic field generating components to move synchronously along the circumferential direction of the edge area.

[0006] Furthermore, 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.

[0007] Furthermore, the magnetic field generating component is an electromagnetic coil.

[0008] Furthermore, the rotating component comprises: A plurality of mounting plates disposed above the edge region, the magnetic field generating components being mounted on the mounting plates in a one-to-one correspondence; A rotating bracket is arranged above the gas spraying area, the rotating bracket is connected to the plurality of mounting plates, and is used to drive the plurality of mounting plates to synchronously move circumferentially along the edge area.

[0009] 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.

[0010] Furthermore, a lifting mechanism for driving the rotating component to rise and fall is provided above the upper electrode.

[0011] In a second aspect, the present invention provides a plasma etching method, which is implemented based on a plasma etching device, wherein the etching device includes a reaction chamber, a pair of upper electrodes and a lower electrode are arranged in parallel at the top and bottom of the reaction chamber, and the upper electrode includes a gas spraying area for spraying gas downward and an edge area surrounding the gas spraying area, and the etching method includes: A plurality of magnetic field generating components distributed along the circumferential direction are arranged 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; placing a wafer in the reaction chamber; Etching parameters are set, and etching gas is introduced into the reaction chamber through the gas spray area to etch the wafer according to the etching parameters. During the etching process, each of the magnetic field generating components is driven by the rotating component to move synchronously along the circumferential direction of the edge area, and the etching parameters include the target rotation speed of the rotating component.

[0012] Further, 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; or, The magnetic field generating component is an electromagnetic coil.

[0013] Furthermore, the method further comprises: arranging a lifting mechanism above the upper electrode for driving the rotating component to move up and down, and the etching parameters comprise a target lifting height of the rotating component.

[0014] Furthermore, during the etching process, one of the upper electrode and the lower electrode is grounded, and the other is connected to a radio frequency power source, and the etching parameters include the frequency and power of the radio frequency power source.

[0015] By adopting the above technical solution, the present invention has the following beneficial effects: The present invention arranges a plurality of circumferentially distributed magnetic field generating components above the edge region. The magnetic field generated by each magnetic field generating component can pass through the edge region into the reaction chamber, and can move circumferentially therewith under the action of the rotating component. The circumferentially moving magnetic field can deflect the charged ions generated by capacitive coupling near the edge region of the upper electrode inside the reaction chamber to assist in the dissociation of plasma, thereby being able to excite a higher density plasma at the edge of the wafer, thereby increasing the etching rate at the edge of the wafer and improving the uniformity of etching in the center region and at the edge of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of a conventional capacitively coupled plasma etching device; Figure 2A It is a schematic structural diagram of a plasma etching device according to Embodiment 1 of the present invention; Figure 2B Schematic diagram of the layout of the permanent magnets in Example 1 of the present invention; Figure 2C Schematic diagram of magnetic flux lines of the magnetic field generated in Example 1 of the present invention; Figure 3A A schematic diagram of the layout of the electromagnetic coil in Example 2 of the present invention; Figure 3B This is another schematic diagram of the layout of the electromagnetic coil in Example 2 of the present invention.

[0017] Description of reference numerals: 10, 10', upper electrode; 11, air inlet; 20, 20', lower electrode; 30, wafer; 40, magnetic field generating component; 50, rotating component; 51, mounting plate; 52, rotating bracket; 60, gas buffer chamber; S1, gas spraying area; S2, edge area. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with 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.

[0019] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The singular forms "a", "the" and "the" used in the present disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0020] As mentioned above, when using existing capacitively coupled plasma (CCP) etching equipment to etch wafers, it is easy to cause the problem of relatively low plasma density at the edge of the wafer, which will make the processing rate in the center area of ​​the wafer faster and the processing rate in the edge area of ​​the wafer slower, resulting in different performance of semiconductor devices formed in different areas of the wafer.

[0021] Based on this, the present invention provides an improved plasma etching device and etching method to increase the etching rate of the wafer edge, thereby improving the uniformity of wafer etching.

[0022] Example 1 This embodiment provides a plasma etching device, such as Figure 2A As shown, the etching device 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 and the lower electrode 20 are both circular electrode plates, and the two are coaxially arranged in the reaction chamber. When etching is performed, the wafer 30 is coaxially arranged above the lower electrode 20.

[0023] See also Figure 2A and Figure 2B As shown, the upper electrode 10 in this embodiment includes a circular gas spraying area S1 located in the central area thereof and an annular edge area S2 surrounding the gas spraying area S1, wherein the gas spraying area S1 is used for spraying gas downward.

[0024] Different from traditional CCP etching equipment, Figure 2A to Figure 2C As shown, in this embodiment, a plurality of magnetic field generating components 40 distributed circumferentially (preferably evenly distributed) are provided above the edge region S2 of the upper electrode 10, and the 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 into the interior of the reaction chamber, and the intensity near the edge region S2 will be the strongest.

[0025] Specifically, the magnetic field generating component 40 in this embodiment is implemented by a permanent magnet, wherein the N pole (i.e., the north pole) and the S pole (i.e., the south pole) of adjacent permanent magnets are arranged opposite to each other to generate magnetic flux lines from the N pole to the opposite S pole (see Figure 2C ), the magnetic flux lines generated can pass through the edge area S2 of the upper electrode 10 and extend to the inside of the reaction chamber, and the direction of the magnetic flux lines will not change.

[0026] In an optional embodiment, the area of ​​the gas spraying zone S1 is greater than 80% of the area of ​​the wafer 30. The permanent magnet is substantially square and its length direction preferably extends along the radial direction of the upper electrode 10. The number n of the permanent magnets 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 magnet can also be configured into any other suitable shape, and this embodiment does not impose any specific restrictions on this.

[0027] In addition, a rotating component 50 is further provided above the upper electrode 10 in this embodiment, so as to drive each magnetic field generating component 40 to synchronously move in the circumferential direction along the edge area S2 through the rotating component 50. It should be understood that when the magnetic field generating component 40 rotates, the magnetic field generated by it will also rotate accordingly, and the rotating magnetic field will deflect the charged ions generated by capacitive coupling near the edge area S2 inside the reaction chamber to assist in the dissociation of plasma, thereby exciting a higher density plasma, and a higher density plasma can produce a faster etching rate for the edge of the wafer 30.

[0028] exist Figure 2A In the illustrated embodiment, the rotating component 50 includes a plurality of mounting plates 51 circumferentially disposed above the edge region S2 of the upper electrode 10, so that the magnetic field generating components 40 are mounted one by one on each mounting plate 51. In addition, the rotating component 50 also includes a rotating bracket 52 disposed above the gas spraying region S1, and the rotating bracket 52 is connected to each mounting plate 51 to drive each mounting plate 51 to synchronously move circumferentially along 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.

[0029] See again Figure 2A As shown, a gas buffer chamber is formed above the gas spraying area S1 of the upper electrode 10, and the gas buffer chamber is connected to an external gas supply device (not shown) to provide etching gas through the external gas supply device. The etching gas includes but is not limited to Cl 2 , BCl 3 , A r 、N 2 At the same time, the gas spraying area S1 is evenly provided with a plurality of gas inlet holes 11 connected with the gas buffer chamber 60, so that the etching gas in the gas buffer chamber 60 can enter the reaction chamber through these gas inlet holes 11 and generate plasma under the action of the magnetic field and the electric field.

[0030] In this embodiment, the rotating bracket 52 is arranged above the gas buffer chamber 60, and its circumferential edge extends downward to be connected 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, so that 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.

[0031] It should be understood that by adjusting the rotation speed of the rotating support 52 , the intensity of the magnetic field dissociating plasma can be adjusted, and thus the etching rate of the edge of the wafer 30 can be adjusted.

[0032] In an operative manner, the present embodiment further provides a lifting mechanism (not shown) for driving the rotating component 50 to move up and down above the upper electrode 10. The lifting mechanism, for example, drives the rotating component 50 to move up and down under the drive of a cylinder or a motor, thereby causing the magnetic field generating component 40 to move up and down as a whole, thereby adjusting the magnetic field strength entering the reaction chamber. Specifically, when moving downward, the induction of the magnetic field can be enhanced, and when moving upward, the induction of the magnetic field can be reduced, thereby adjusting the etching rate of the edge of the wafer 30.

[0033] It can be seen that in this embodiment, a plurality of circumferentially distributed magnetic field generating components 40 are arranged above the edge region S2. Since the magnetic field generated by each magnetic field generating component 40 can pass through the edge region S2 into the reaction chamber, and can move circumferentially therewith 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 the plasma, thereby being able to excite a higher density plasma at the edge of the wafer 30, thereby improving the etching rate of the edge of the wafer 30, and further improving the uniformity of etching in the central area and edge of the wafer 30. In addition, the structure is simple and the cost is low, which is conducive to large-scale application in the semiconductor industry.

[0034] Example 2 This embodiment provides a plasma etching device, which is different from the first embodiment in that Figure 3A and Figure 3B As shown, the magnetic field generating component 40 in this embodiment is implemented by an electromagnetic coil instead of a permanent magnet.

[0035] It should be understood that the magnetic field generated by the electromagnetic coil being energized can also pass through the edge area S2 into the reaction chamber, and can move circumferentially with the rotating component 50. The circumferentially moving magnetic field will deflect the charged ions generated by capacitive coupling near the edge area S2 of the upper electrode 10 in the reaction chamber to assist in the dissociation of plasma, thereby exciting 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 direction of the arrow in φ indicates the rotation direction of the rotating component 50 , that is, the rotation direction of the magnetic field.

[0036] In one practicable manner, the electromagnetic coil is substantially square, and its length or width direction may extend along the radial direction of the upper electrode 10 (eg Figure 3A As shown), it is also possible not to extend along the radial direction of the upper electrode 10 (i.e., to form a certain angle with the radial direction, such as Figure 3B As shown). The number n of the electromagnetic coils 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 configured into any other suitable shape (such as a circle, etc.), and this embodiment does not impose any specific limitation on this.

[0037] Example 3 This embodiment provides a plasma etching method, which uses a plasma etching device to etch the wafer 30. Figure 2A As shown, the etching device 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 area S1 for spraying gas downward and an edge area S2 surrounding the gas spraying area S1.

[0038] The etching method of this embodiment specifically includes the following steps: Step 1: A plurality of circumferentially distributed magnetic field generating components 40 are arranged above the edge region S2 of the upper electrode 10 , wherein the magnetic field generating components 40 are used to generate a magnetic field and the magnetic field can pass through the edge region S2 into the reaction chamber.

[0039] In one practicable manner, if Figure 2B and Figure 2C As shown, the magnetic field generating component 40 is implemented by a permanent magnet, wherein the N poles and S poles of adjacent permanent magnets are arranged opposite to each other to generate magnetic flux lines pointing from the N pole to the relative S pole. It should be understood that the generated magnetic flux lines can extend through the edge area S2 of the upper electrode 10 to the inside of the reaction chamber, and the direction of the magnetic flux lines will not change.

[0040] Preferably, if Figure 2B As shown, the permanent magnet is substantially square and its length direction preferably extends along the radial direction of the upper electrode 10, but this embodiment does not impose any specific limitation on this.

[0041] In another practicable manner, if Figure 3A and Figure 3B As shown, the magnetic field generating component 40 is implemented by an electromagnetic coil, and the magnetic field generated by the electromagnetic coil being energized can also pass through the edge area S2 and enter the interior of the reaction chamber.

[0042] Preferably, the electromagnetic coil is substantially square, and its length or width direction may extend along the radial direction of the upper electrode 10 (eg Figure 3A As shown), it is also possible not to extend along the radial direction of the upper electrode 10 (i.e., to form a certain angle with the radial direction, such as Figure 3B Of course, the electromagnetic coil can also be configured into any other suitable shape (such as a circle, etc.), and this embodiment does not impose any specific limitation on this.

[0043] In addition, in this embodiment, a rotating component 50 is further provided above the upper electrode 10, so as to drive each magnetic field generating component 40 to synchronously move in the circumferential direction along the edge area S2 through the rotating component 50. It should be understood that when the magnetic field generating component 40 rotates, the magnetic field generated by it will also rotate accordingly, and the rotating magnetic field will deflect the charged ions generated by capacitive coupling near the edge area S2 inside the reaction chamber to assist in the dissociation of plasma, thereby exciting a higher density plasma, and a higher density plasma can produce a faster etching rate for the edge of the wafer 30.

[0044] Step 2: Place the wafer 30 in the reaction chamber, and fix it above the lower electrode 20 by a base such as an electrostatic chuck.

[0045] Step 3: Set the etching parameters, and introduce the etching gas into the reaction chamber through the gas spray area 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 synchronously move along the edge area S2 to generate a rotating magnetic field, and one of the upper electrode 10 and the lower electrode 20 is grounded, and the other is connected to the radio frequency power source, so that a radio frequency electric field is generated between the upper electrode 10 and the lower electrode 20 to ionize the etching gas introduced into the reaction chamber to form plasma, and then the wafer 30 placed between the upper electrode 10 and the lower electrode 20 and supported by the base is etched.

[0046] The set etching parameters include, but are not limited to, the frequency and power of the RF power source, the chamber pressure of the reaction chamber, the type of etching gas and its flow rate, etc. In addition, the etching parameters also include a 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, and then the etching rate of the edge of the wafer 30 can be adjusted.

[0047] In an operative manner, the etching method of the present embodiment further includes: a lifting mechanism for driving the rotating component 50 to rise and fall is provided above the upper electrode 10, and the lifting mechanism drives the rotating component 50 to move up and down, for example, under the drive of a cylinder or a motor, and then causes the magnetic field generating component 40 to rise and fall accordingly, so that the strength of the magnetic field entering the reaction chamber can be adjusted. Specifically, when moving downward, the induction of the magnetic field can be enhanced, and when moving upward, the induction of the magnetic field can be reduced, and then the etching rate of the edge of the wafer 30 can be adjusted. On this basis, the aforementioned etching parameters also include a target lifting height of the rotating component 50. By adjusting the target lifting height, the strength of the magnetic field dissociation plasma can be adjusted, and then the etching rate of the edge of the wafer 30 can be adjusted.

[0048] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A plasma etching device, comprising a reaction chamber, wherein a pair of upper electrodes and a lower electrode are arranged in parallel at the top and bottom of the reaction chamber, wherein the upper electrode comprises a gas spraying area for spraying gas downward and an edge area surrounding the gas spraying area, wherein: A plurality of magnetic field generating components distributed in the circumferential direction are provided above the edge region, and 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; A rotating component is also provided above the upper electrode, and the rotating component is used to drive each of the magnetic field generating components to move synchronously along the circumferential direction of the edge area.

2. The plasma etching equipment according to claim 1, 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.

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

4. The plasma etching equipment according to claim 1, characterized in that: The rotating component comprises: A plurality of mounting plates disposed above the edge region, the magnetic field generating components being mounted on the mounting plates in a one-to-one correspondence; A rotating bracket is arranged above the gas spraying area, the rotating bracket is connected to the plurality of mounting plates, and is used to drive the plurality of mounting plates to synchronously move circumferentially along the edge area.

5. The plasma etching equipment 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 equipment according to claim 1, characterized in that: A lifting mechanism for driving the rotating component to move up and down is also provided above the upper electrode.

7. A plasma etching method, which is implemented based on a plasma etching device, wherein the etching device comprises a reaction chamber, wherein a pair of upper electrodes and a lower electrode are arranged in parallel at the top and bottom of the reaction chamber, wherein the upper electrode comprises a gas spraying area for spraying gas downward and an edge area surrounding the gas spraying area, wherein: The etching method comprises: A plurality of magnetic field generating components distributed along the circumferential direction are arranged 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; placing a wafer in the reaction chamber; Etching parameters are set, and etching gas is introduced into the reaction chamber through the gas spray area to etch the wafer according to the etching parameters. During the etching process, each of the magnetic field generating components is driven by the rotating component to move synchronously along the circumferential direction of the edge area, and 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 is an electromagnetic coil.

9. The plasma etching method according to claim 7, characterized in that: The method further includes: arranging a lifting mechanism above the upper electrode for driving the rotating component to move up and down, and the etching parameters include a 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 electrode and the lower electrode is grounded, and the other is connected to a radio frequency power source, and the etching parameters include the frequency and power of the radio frequency power source.

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