Reaction chamber and capacitively coupled plasma equipment

Abstract

The present disclosure provides a reaction chamber and a capacitively coupled plasma device, wherein the reaction chamber comprises a bottom wall, an inner liner, a support assembly and a magnetic assembly. The inner liner is arranged in the chamber body, including a bottom liner located above the bottom wall of the chamber body; the support assembly is arranged in a process area surrounded by the bottom liner, and is used to support a wafer; the magnetic assembly is arranged outside the process area, and is used to form a magnetic field, so as to reduce the difference in etching rate between the edge area and the central area of ​​the wafer.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor manufacturing technology, and in particular to a reaction chamber and a capacitively coupled plasma device. Background Art

[0002] In the semiconductor etching process, the etching uniformity of the wafer is an important technical indicator. Figure 1 This is a structural schematic diagram of a common capacitively coupled plasma (CCP) precleaning chamber. The chamber is generally cylindrical and consists of a chamber body 1, a liner (upper liner 2, lower liner 3), a lower electrode structure and other parts. The lower electrode structure is mainly composed of a support plate 7, an insulating base 11, a radio frequency matcher 9, and a radio frequency power supply 10. The chamber body 1 is also provided with a vacuum port 4, from which the reaction gas and etching byproducts are discharged. The gas uniformizing plate 6 makes the gas entering the reaction chamber from the air inlet (not shown in the figure) more evenly distributed. The support plate 7 is usually metal, and its diameter L is slightly smaller than the wafer. The insulating base 11 insulates the support plate 7 from the lower liner 3. The bellows 8 can drive the support plate 7 to rise and fall within a certain range. The entire reaction chamber is in good contact with the ground except for the support plate 7.

[0003] In order to prevent the support plate from being etched and thus contaminating the wafer, the size of the lower electrode of the plasma etching equipment is usually smaller than the wafer size. Therefore, there is an electric field at the edge of the wafer that is much higher than that in the center, resulting in a higher plasma density in the edge area and a large ion flux reaching the edge of the wafer, causing a high etching rate at the edge of the wafer, which seriously affects the etching uniformity of the wafer. This effect is called the edge electric field effect, which is particularly serious in the etching equipment of capacitively coupled plasma (CCP). Sometimes the etching rate at the edge of the wafer is even more than twice that of the center area. Figure 2 shown.

[0004] At present, the edge electric field effect problem is mainly solved by a focus ring with a specific structure. Figure 3 As shown, the diameter D of the focusing ring 5 is slightly larger than the wafer. The dielectric constant of the focusing ring 5 should be as large as possible, and quartz crystal or ceramic is usually used. The selected material should be compatible with the etching process. The focusing ring of this structure can improve the distribution of the edge electric field, and the ion flux reaching the edge of the wafer can be limited by adjusting the height H and inner diameter D of the focusing ring 5, thereby reducing the etching rate at the edge of the wafer.

[0005] However, in the process of implementing the present disclosure, the applicant discovered that the prior art has the following defects:

[0006] In capacitively coupled plasma etching equipment, the edge electric field effect is very strong. Increasing the height H of the focusing ring and adjusting the inner diameter D of the focusing ring are difficult to effectively solve the problem of excessive edge etching rate. Moreover, if the height H of the focusing ring is too large, etching by-products are easily deposited on the inner side of the focusing ring, thereby affecting the stability of the process. Summary of the invention

[0007] The present disclosure aims to at least partially solve the technical problems existing in the prior art, and proposes a reaction chamber and a capacitively coupled plasma device.

[0008] According to one aspect of the present disclosure, a reaction chamber is provided, comprising: a chamber body, including a bottom wall; a liner, arranged in the chamber body, including a bottom liner located above the bottom wall of the chamber body; a support assembly, arranged in a process area surrounded by the bottom liner, for supporting a wafer; and a magnetic assembly, arranged outside the process area, for forming a magnetic field to reduce the difference in etching rate between an edge area and a central area of ​​the wafer.

[0009] In some embodiments of the present disclosure, the support component is disposed on the upper surface of the substrate, and the magnetic component is disposed on the lower surface of the substrate and corresponds to the edge portion of the support component. The magnetic field formed by the magnetic component is distributed at the edge portion of the support component to reduce the etching rate of the edge area of ​​the chip.

[0010] In some embodiments of the present disclosure, the magnetic assembly includes: inner magnets and outer magnets distributed in a radial direction; the inner magnets have opposite polarities to the outer magnets.

[0011] In some embodiments of the present disclosure, the inner magnet and the outer magnet are annular structures.

[0012] In some embodiments of the present disclosure, the annular structure is formed by a plurality of cylindrical magnets arranged at equal intervals.

[0013] In some embodiments of the present disclosure, the annular structure is formed by a plurality of arc-shaped magnets arranged at equal intervals.

[0014] In some embodiments of the present disclosure, the annular structure is an annular magnet.

[0015] In some embodiments of the present disclosure, the support assembly includes: an insulating base and a support plate, which are stacked in sequence on the upper surface of the substrate, and the support plate is used to support the chip; a focusing ring, which is arranged on the upper surface of the substrate and surrounds the insulating base and the support plate; the magnetic field is distributed on the support plate, the edge portion of the insulating base and the focusing ring.

[0016] In some embodiments of the present disclosure, the diameter of the inner magnet is greater than the diameter of the wafer, and the radial spacing between the inner magnet and the outer magnet is equal to the vertical spacing between the upper surface of the support plate and the lower surface of the substrate.

[0017] In some embodiments of the present disclosure, the radial distance between the inner magnet and the outer magnet is less than 30 mm.

[0018] In some embodiments of the present disclosure, the material of the magnetic component is N38SH or N40SH.

[0019] According to another aspect of the present disclosure, a capacitively coupled plasma device is provided, comprising the above-mentioned reaction chamber.

[0020] In some embodiments of the present disclosure, the capacitively coupled plasma equipment is a capacitively coupled plasma pre-cleaning equipment.

[0021] The present invention discloses that by setting a magnetic component corresponding to the edge portion of the support component, the etching rate at the edge of the wafer can be effectively reduced, and the difference in etching rate with the center area of ​​the wafer can be narrowed, thereby improving the etching uniformity of the wafer, solving the problem of edge electric field effect, and preventing etching by-products from being deposited on the inner side of the focusing ring, thereby ensuring long-term stability of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0023] Figure 1 is a schematic structural diagram of a capacitively coupled plasma pre-cleaning chamber in the prior art;

[0024] Figure 2 yes Figure 1 Radial curve of wafer etch rate in the capacitively coupled plasma pre-cleaning chamber shown;

[0025] Figure 3 yes Figure 1 A schematic cross-sectional view of the lower electrode structure of the capacitively coupled plasma pre-cleaning chamber shown;

[0026] Figure 4 is a schematic structural diagram of a reaction chamber according to an embodiment of the present disclosure;

[0027] Figure 5 is a bottom view of a reaction chamber magnetic assembly according to an embodiment of the present disclosure;

[0028] Figure 6 is a magnetic field distribution diagram of a reaction chamber of an embodiment of the present disclosure;

[0029] Figure 7FIG. 4 is a bottom view of a reaction chamber magnetic assembly according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0031] The present disclosure provides a reaction chamber which is applied to a capacitively coupled plasma device, in particular a capacitively coupled plasma pre-cleaning device, such as Figure 4 As shown, the reaction chamber is a cylindrical structure, including: a chamber body 1, an inner lining and a lower electrode structure.

[0032] The chamber body 1 comprises a side wall 11 and a bottom wall 12 . The bottom wall 12 is provided with a gas extraction port 4 for discharging process gas and etching by-products.

[0033] The liner is arranged in the chamber body 1 to prevent the chamber body from being contaminated and corroded by plasma, and includes: a top liner 2 and a bottom liner 3. The top liner 2 and the bottom liner 3 together surround a process area to form a process environment. A gas distribution plate 6 is arranged on the top surface of the top liner 2 to make the gas entering the process environment from the gas inlet (not shown in the figure) more evenly distributed. The bottom liner 3 is located above the bottom wall 12 of the chamber body, and includes: a side surface 31 opposite to the side wall 11 of the chamber body, and a bottom surface 32 opposite to the bottom wall 12 of the chamber body.

[0034] The lower electrode structure includes: a supporting component, a radio frequency component and a magnetic component.

[0035] The support assembly is arranged in the process area surrounded by the substrate 3. Specifically, the support assembly is arranged on the upper surface of the substrate 3, that is, the upper surface of the substrate bottom surface 32, for supporting the wafer, and includes: a focusing ring 5, a support plate body 7 and an insulating base 15.

[0036] The insulating base 15 and the supporting plate 7 are sequentially stacked on the upper surface of the substrate 3, that is, the insulating base 15 is arranged on the upper surface of the substrate bottom surface 32, and the supporting plate 7 is arranged on the upper surface of the insulating base 15. The supporting plate 7 is used to place the wafer, and the insulating base 15 insulates the supporting plate 7 from the substrate 3. The focusing ring 5 is arranged on the upper surface of the substrate bottom surface 32 and surrounds the insulating base 15 and the supporting plate 7, and the three are arranged concentrically. The focusing ring 5 prevents the wafer from sliding out of the supporting plate 7 and confines the plasma above the lower electrode structure, which plays a role in suppressing the edge electric field effect.

[0037] The lower electrode structure also includes a bellows 8, which is disposed between the bottom wall 12 of the chamber body and the bottom surface 32, and is used to support the lower liner 3, and can drive the lower liner 3 and the supporting assembly to rise and fall as a whole.

[0038] The support plate 7 is made of metal, usually aluminum. To prevent the metal support plate 7 from being etched by plasma and contaminating the wafer, the size of the support plate 7 is slightly smaller than the wafer, that is, the diameter of the support plate 7 is smaller than the diameter of the wafer. The insulating base 15 can be made of insulating materials such as ceramics. Except for the support plate 7, all other components are in good contact with the ground.

[0039] The radio frequency component includes a radio frequency matcher 9 and a radio frequency power supply 10, which are electrically connected to the support component and are used to provide radio frequency voltage to the support component.

[0040] See also Figure 4 , the lower electrode structure of this embodiment also includes a magnetic component, which is arranged outside the process area surrounded by the substrate 3, and is used to form a magnetic field to reduce the difference in etching rate between the edge area and the central area of ​​the wafer. Specifically, the magnetic component is arranged on the lower surface of the substrate 3, that is, the lower surface of the substrate bottom surface 32, and corresponds to the position of the edge portion of the support component to reduce the etching rate of the edge area of ​​the wafer. The magnetic component includes: an inner magnet 13 and an outer magnet 14 distributed in the radial direction. Since the support disk body 7 and the insulating base 15 are generally disc-shaped structures, the focusing ring 5 is a circular ring structure, and the support component as a whole is also a disc-shaped structure, the shapes of the inner magnet 13 and the outer magnet 14 should correspond to the support component, so it is also a ring structure as a whole.

[0041] like Figure 5 As shown, in this embodiment, the inner magnet 13 and the outer magnet 14 are multiple ( Figure 5 The inner magnet 13 has a cylindrical magnet 14, and the inner magnet 13 has a cylindrical magnet 14, and the inner magnet 13 has a cylindrical magnet 14, and the outer magnet 14 has a cylindrical magnet 14. The inner magnet 13 and the outer magnet 14 form a magnetic circuit. In one example, the inner magnet 13 has a cylindrical magnet with an S pole facing upward and fixed to the lower surface of the bottom substrate 32, and the N pole facing downward to the bottom wall 12 of the chamber body; the outer magnet 14 has a cylindrical magnet with an S pole facing downward to the bottom wall 12 of the chamber body, and the N pole facing upward to the lower surface of the bottom substrate 32. In another example, the above situation may be reversed, that is, the inner layer magnet 13 has its N pole facing upward and its S pole facing downward, and the outer layer magnet 14 has its N pole facing downward and its S pole facing upward.

[0042] like Figure 6As shown, the magnetic assembly of this embodiment forms a magnetic field, and the magnetic field is mainly distributed in the area above and below the magnetic assembly and between the inner magnet 13 and the outer magnet 14. Since the magnetic assembly corresponds to the edge portion of the support assembly, the magnetic field above the magnetic assembly is also distributed in the edge portion of the support assembly, that is, distributed in the edge portion of the support plate 7, the insulating base 15 and the focusing ring 5. During the process, due to the presence of a magnetic field at the edge portion of the support assembly, part of the plasma will be confined to the edge area, and at the same time, it is difficult for the electric field component perpendicular to the magnetic field to be effectively coupled to the plasma, and the plasma density at the edge of the wafer is reduced. The above two factors lead to a reduction in the ion flux reaching the edge of the wafer, thereby reducing the etching rate at the edge of the wafer. At the same time, in the area far from the edge portion of the support assembly, that is, the central portion of the support assembly, the magnetic field strength decays rapidly, and has almost no effect on the etching rate of the center of the wafer, thereby improving the uniformity of wafer etching.

[0043] The cylindrical magnet of this embodiment is made of N38SH or N40SH. Magnets made of these materials can withstand high temperatures of 150°C and can be used in a vacuum environment. Both layers of magnets are located outside the process area and are not in contact with the plasma, and will not be contaminated and corroded by the plasma. The diameter W of the inner magnet 13 is slightly larger than the diameter of the wafer, and the radial spacing h between the inner magnet 13 and the outer magnet 14 is approximately the spacing between the support disk 7 and the inner magnet 13, that is, the distance a from the upper surface of the support disk 7 to the lower surface of the base substrate 32, and a is preferably less than 30 mm. Within the above-mentioned size range, the diameter W of the inner magnet 13 and the radial spacing h between the inner magnet 13 and the outer magnet 14 can be adjusted. For example, in Figure 6 In the embodiment, the inner magnet 13 is located below the edge of the support plate 7 and the insulating base 15, and the outer magnet 14 is located below the focusing ring 5. Figure 4 As shown, the inner magnet 13 is located below the focusing ring 5, and the outer magnet 14 is located outside the focusing ring 5. The diameter W of the inner magnet 13 is larger than Figure 6 In addition, magnets with different magnetic field strengths can be selected, and the etching rate of the edge of the wafer can be controlled by adjusting the diameter W of the inner magnet 13, the radial spacing h between the inner magnet 13 and the outer magnet 14, and the magnetic field strength of the magnet.

[0044] It can be seen that this embodiment, by setting a magnetic component corresponding to the edge portion of the support component, can effectively reduce the etching rate at the edge of the chip and narrow the gap with the etching rate in the central area of ​​the chip, thereby improving the etching uniformity of the chip and solving the problem of edge electric field effect. It also does not cause etching by-products to be deposited on the inside of the focusing ring 5, and can ensure long-term stability of the process.

[0045] In the following description of a reaction chamber of another embodiment of the present disclosure, for the purpose of brief description, any technical features of the above embodiments that can be used in the same application are described here, and there is no need to repeat the same description. Figure 7 As shown, the inner layer magnet 13 and the outer layer magnet 14 are concentric annular magnets, and the polarity of the inner layer annular magnet is opposite to that of the outer layer annular magnet. The S pole of the inner layer annular magnet faces upward and is fixed to the lower surface of the bottom substrate surface 32, and the N pole faces downward and faces the bottom wall 12 of the chamber body; the S pole of the outer layer annular magnet faces downward and faces the bottom wall 12 of the chamber body, and the N pole faces upward and is fixed to the lower surface of the bottom substrate surface 32, or vice versa.

[0046] The magnetic assembly of this embodiment can also improve the etching uniformity of the wafer, and compared with the form of multiple cylindrical magnets, it has fewer parts and is easier to process.

[0047] The above is only an exemplary description. In other examples, the inner magnet 13 and the outer magnet 14 may not be complete ring magnets, but may be a ring structure formed by equidistantly arranged arc magnets. There is no limit to the number of arc magnets, which can also improve the uniformity of wafer etching.

[0048] Another embodiment of the present disclosure provides a plasma device, which includes the reaction chamber of the above embodiment. The plasma device is a capacitively coupled plasma device, and further, a capacitively coupled plasma pre-cleaning device. At the same time, the plasma device can also be an inductively coupled plasma device.

[0049] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

[0050] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure.

[0051] Unless otherwise indicated, the numerical parameters in this specification and the appended claims are approximate values ​​and can vary according to the desired properties obtained through the content of the present disclosure. Specifically, all numbers used in the specification and claims to express the content of the composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. In general, the meaning of the expression is to include a variation of ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments by a specific number.

[0052] Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0053] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., to modify the corresponding elements, do not themselves mean or represent any ordinal number of the element, nor do they represent the order of one element and another element, or the order of manufacturing methods. The use of these ordinal numbers is only used to clearly distinguish a component with a certain name from another component with the same name.

[0054] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting the following intention: the claimed disclosure requires more features than the features explicitly recited in each claim. More specifically, as reflected in the claims below, the disclosed aspects are less than all the features of the single embodiment disclosed above. Therefore, the claims that follow the specific embodiment are hereby expressly incorporated into the specific embodiment, with each claim itself serving as a separate embodiment of the present disclosure.

Claims

1. A reaction chamber, comprising: The chamber body comprises a bottom wall, wherein the bottom wall is provided with an air extraction port; An inner liner is disposed in the chamber body, including a bottom liner located above the bottom wall of the chamber body; A support assembly, disposed in a process area surrounded by the substrate, for supporting a wafer; A magnetic component is arranged outside the process area and is used to form a magnetic field to reduce the difference in etching rate between the edge area and the central area of ​​the wafer; wherein, The magnetic assembly comprises: inner magnets and outer magnets distributed radially; The polarity of the inner magnet is opposite to the polarity of the outer magnet; The magnetic field is used to confine part of the plasma to the edge area of ​​the wafer, and to make it difficult for the electric field component perpendicular to the magnetic field to be effectively coupled into the plasma; The support component is arranged on the upper surface of the substrate, and the magnetic component is arranged on the lower surface of the substrate and corresponds to the edge portion of the support component. The magnetic field formed by the magnetic component is distributed on the edge portion of the support component to reduce the etching rate of the edge area of ​​the chip.

2. The reaction chamber according to claim 1, The inner magnet and the outer magnet are annular structures.

3. The reaction chamber according to claim 2, The annular structure is formed by arranging a plurality of cylindrical magnets at equal intervals.

4. The reaction chamber according to claim 2, The annular structure is formed by a plurality of arc-shaped magnets arranged at equal intervals. The reaction chamber as claimed in claim 2 , wherein the annular structure is an annular magnet.

6. The reaction chamber according to any one of claims 2 to 5, The support assembly comprises: An insulating base and a supporting plate are sequentially stacked on the upper surface of the substrate, and the supporting plate is used to support the wafer; A focusing ring, disposed on the upper surface of the substrate and surrounding the insulating base and the supporting plate; The magnetic field is distributed on the supporting plate, the edge of the insulating base and the focusing ring.

7. The reaction chamber according to claim 6, The diameter of the inner magnet is greater than the diameter of the wafer, and the radial distance between the inner magnet and the outer magnet is equal to the vertical distance between the upper surface of the support plate and the lower surface of the substrate.

8. The reaction chamber according to claim 7, The radial distance between the inner magnet and the outer magnet is less than 30 mm.

9. The reaction chamber according to claim 1, The material of the magnetic component is N38SH or N40SH.

10. A capacitively coupled plasma device, comprising the reaction chamber according to any one of claims 1 to 9. 11 . The capacitively coupled plasma equipment according to claim 10 , wherein the capacitively coupled plasma equipment is a capacitively coupled plasma pre-cleaning equipment.

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