A method for improving the cleaning efficiency in a CCP reaction chamber

Abstract

The present invention discloses a method for improving the cleaning efficiency in a CCP reaction chamber, comprising: providing a reaction chamber, wherein a base is provided in the reaction chamber; providing an auxiliary component, wherein the upper surface area of ​​the auxiliary component is larger than the upper surface area of ​​the base; placing the auxiliary component on the base so that the lower surface of the auxiliary component contacts the upper surface of the base; introducing a cleaning gas to form a plasma to remove polymers deposited in the reaction chamber. The present invention provides a method that does not require opening the chamber to wipe the polymers deposited on the surface of the pole, and can enhance the bombardment of the pole by plasma during the cleaning process, thereby improving the cleaning efficiency of the pole.

Description

Technical Field

[0001] The invention relates to the field of semiconductors, and in particular to a plasma cleaning process. Background Art

[0002] In the CCP etching process, in order to make the etching rate of the etching gas on the process layer greater than the etching rate on the mask layer and ensure a sufficiently high etching selectivity, the method of depositing polymer gas is usually used to protect the sidewalls of the etched aperture. The polymer will not only be deposited on the surface of the wafer, but also on the inner wall of the cavity, polluting the environment in the cavity, making the environment of each wafer different, resulting in different etching results; under the action of the radio frequency field, the deposited polymer will also bring the risk of discharge and sparking between different components.

[0003] Usually, O is introduced into the cavity 2 CF 4 Or Ar plasma is used to clean polymers. However, due to the specific structure of the plasma chamber, polymers are not easy to be cleaned off. For example, in a 12-inch chamber, the area ratio of the ground electrode to the cathode is about 3:1. When using the same chamber to etch an 8-inch wafer, the area ratio of the ground electrode to the cathode is about 6:1. Their common feature is that the area of ​​the ground electrode is larger than the area of ​​the cathode. Due to the electrical neutrality of the plasma, the ion flux of the plasma to the ground electrode and the cathode is equivalent. When the area of ​​the ground electrode and the cathode on both sides of the plasma is relatively large, the ion bombardment energy on the ground electrode is much less than that of the cathode, so that the existing cleaning process is not efficient for cleaning polymers deposited on the ground electrode, and it is often necessary to open the chamber for manual cleaning. Summary of the invention

[0004] The purpose of the present invention is to reduce the area ratio of the ground electrode to the cathode through auxiliary components, enhance the bombardment of the ground electrode by plasma during the cleaning process, and improve the cleaning efficiency of the ground electrode.

[0005] In order to achieve the above object, the present invention provides a method for improving the cleaning efficiency in a CCP reaction chamber, comprising:

[0006] Providing a reaction chamber, wherein a base is arranged in the reaction chamber;

[0007] providing an auxiliary component, wherein the upper surface area of ​​the auxiliary component is larger than the upper surface area of ​​the base;

[0008] placing the auxiliary component on the base so that the lower surface of the auxiliary component contacts the upper surface of the base;

[0009] A cleaning gas is introduced to form plasma to remove the polymer deposited in the reaction chamber.

[0010] Optionally, the auxiliary component includes a circular bottom with an area greater than or equal to the upper surface area of ​​the base and a circular top with an area greater than the area of ​​the circular bottom; placing the auxiliary component on the base includes making the lower surface of the circular bottom contact with the upper surface of the base and then fixing the auxiliary component.

[0011] Optionally, direct current is supplied to the base to generate electrostatic adsorption of the round bottom to fix the auxiliary component.

[0012] Optionally, the auxiliary component is fixed by mechanical means.

[0013] Optionally, an upper electrode opposite to the base is provided in the reaction chamber, the auxiliary component is placed on the base, and the dome is relatively parallel to the upper electrode.

[0014] Optionally, an upper grounding ring and a moving ring surrounding the upper electrode are further provided in the reaction chamber, and the auxiliary component is used to improve the cleaning efficiency of the polymer on the upper electrode, the upper grounding ring and the moving ring.

[0015] Optionally, the round bottom is made to have the same shape as the wafer to be processed by the base, and the round top is made to have the same shape as the wafer whose area is larger than the base.

[0016] Optionally, the dome and the dome bottom are integrally formed.

[0017] Optionally, the dome and the dome bottom are formed by bonding two different wafers together.

[0018] Optionally, the auxiliary component is a semiconductor material.

[0019] Optionally, after the cleaning gas is introduced, source radio frequency is applied to excite the plasma, and bias radio frequency is applied to enhance the bombardment intensity of the plasma.

[0020] Optionally, the source radio frequency is applied to the base or the upper electrode, and the bias radio frequency is applied to the base.

[0021] Optionally, the frequency of the source radio frequency is greater than 40 MHz, and the frequency of the bias radio frequency is less than 20 MHz.

[0022] Optionally, the cleaning gas includes carbon fluorine gas, oxidizing gas and protective gas.

[0023] Optionally, the auxiliary component is sent into the reaction chamber by a conveying mechanism and placed on the base; after cleaning, the auxiliary component is moved out of the reaction chamber by the conveying mechanism.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The method for improving the cleaning efficiency in a CCP reaction chamber provided by the present invention does not need to open the chamber to wipe the polymer deposited on the surface of the ground pole when a reaction chamber originally designed for etching a wafer with a larger area is used to etch a wafer with a smaller area. An auxiliary component consisting of a round bottom and a round top is placed on a base to strengthen the bombardment of the ground pole by plasma during the cleaning process, thereby improving the cleaning efficiency of the ground pole and enhancing the operability of the method for improving the utilization rate of the reaction chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for improving the cleaning efficiency in a CCP reaction chamber provided by the present invention.

[0027] Figure 2 This is a schematic diagram of the CCP reaction chamber structure provided by the present invention.

[0028] Figure 3 A schematic structural diagram of the auxiliary components provided by the present invention.

[0029] In the figure, 1-reaction chamber, 2-base, 3-confinement ring, 4-gas shower head, 5-upper grounding ring, 6-moving ring, 7-auxiliary component, 71-round bottom, 72-dome, 8-polymer. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] Capacitively coupled plasma (CCP) etching equipment is a device that generates plasma in a reaction chamber through capacitive coupling by applying a radio frequency power supply to an electrode plate and is used for etching.

[0034] For the etching process with high etching selectivity, in order to protect the sidewalls of the etched holes, a polymer is deposited in the reaction chamber so that the polymer is deposited on the surface of the etched wafer and also on the inner wall of the reaction chamber. 2 CF 4 Or Ar plasma method to clean polymers.

[0035] In some process flows, there are situations where the area ratio of the ground electrode to the cathode has to be increased. For example, in order to improve the utilization rate of CCP etching equipment, the reaction chamber originally designed for etching larger wafers can be used to etch smaller wafers. The reaction chamber originally designed for etching 12-inch wafers can be directly used to etch 8-inch wafers without changing the ground electrode of the reaction chamber. Therefore, only the cathode is changed to adapt to the small-sized wafer. At this time, because the area of ​​the cathode becomes smaller, the area ratio of the ground electrode to the cathode becomes larger, which in turn makes the cleaning effect of the chamber worse. For another example, in the process of etching with a high aspect ratio, it is necessary to strengthen the bombardment of the wafer, so the area ratio of the ground electrode to the cathode is increased. In addition, in this type of process, because the process gas that protects the sidewalls of the deep holes and the mask on the wafer is used, more polymer deposition is caused, which further increases the difficulty of cleaning.

[0036] In summary, due to the increase in the ground electrode and cathode area ratio caused by the original design of the chamber or the later modification plan, the cleaning effect has deteriorated. In order to maintain the process cleanliness of the chamber, the reaction chamber needs to be opened for manual cleaning. The opening of the chamber requires breaking the vacuum and then evacuating the vacuum. These processes have greatly delayed the normal production process and reduced the production efficiency of semiconductor devices.

[0037] In view of the above problems, the present invention provides a method for improving the cleaning efficiency in a CCP reaction chamber.

[0038] like Figure 1 As shown, the method provided by the present invention comprises:

[0039] S1, providing a reaction chamber, wherein a base is arranged in the reaction chamber.

[0040] like Figure 2 As shown, a susceptor 2 for placing a wafer is provided in a reaction chamber 1 of a CCP etching device, serving as a lower electrode of the reaction chamber 1, and a gas shower head 4 is provided in parallel with the susceptor 2, serving as an upper electrode of the reaction chamber 1. The gas shower head 4 is used to transport a reaction gas to the reaction chamber 1. A reaction region is formed between the upper electrode and the lower electrode.

[0041] A confinement ring 3 is arranged around the base 2, and an exhaust channel is provided on the confinement ring 3, which can confine the plasma in the reaction area between the upper and lower electrodes to prevent the plasma from crossing the reaction area and entering the exhaust pump.

[0042] An upper grounding ring 5 and a moving ring 6 are provided around the gas shower head 4. The upper grounding ring 5 can improve the etching uniformity, increase the area of ​​the ground pole, enhance the plasma bombardment on the wafer, and improve the plasma etching efficiency on the wafer. A notch is provided on the side wall of the reaction chamber 1 for the wafer to enter and exit. The wafer is sent into the reaction chamber 1 through the notch, and the movement of the moving ring 6 is controlled to cover the notch, and radio frequency is applied to the base 2 and / or the gas shower head 4 to form plasma.

[0043] In the reaction chamber 1, at least a confinement ring 3, a gas shower head 4, an upper grounding ring 5 and a moving ring 6 form the inner wall of the reaction chamber 1, and the confinement ring 3, the gas shower head 4, the upper grounding ring 5 and the moving ring 6 are all grounded. When plasma etching is performed, the polymer 8 formed by the reaction will be deposited on the surface of the grounded component. Excessive deposition of the polymer 8 has the risk of falling off, which will cause surface defects on the wafer, so it needs to be cleaned regularly.

[0044] S2, providing an auxiliary component, wherein the upper surface area of ​​the auxiliary component is larger than the upper surface area of ​​the base.

[0045] Auxiliary components such as Figure 2 and Figure 3As shown. The auxiliary component 7 is made of semiconductor material, such as single crystal silicon, silicon carbide, silicon germanium, etc. The auxiliary component 7 consists of a round bottom 71 and a round top 72. The area of ​​the round bottom 71 is greater than or equal to the upper surface area of ​​the base 2, and the area of ​​the round top 72 is greater than the upper surface area of ​​the base 2. In some other embodiments, the auxiliary component can also adopt bottom and top surfaces of other shapes. The area ratio of the dome 72 to the round bottom 71 is (1-3): 1, and the area ratio of the dome 72 to the round bottom 71 is not 1:1. The dome 72 with an area greater than the upper surface area of ​​the base 2 is stacked on the round bottom 71, so that the area of ​​the lower electrode is expanded from the upper surface area of ​​the base 2 to the area of ​​the dome 72, thereby reducing the area ratio of the ground electrode to the cathode when the ground electrode area remains unchanged. The round bottom 71 can be fixed to the upper surface of the base 2 by electrostatic attraction, and the round bottom 71 has a certain thickness, which can adapt to the structure of the components around the base, so that the dome 72 can be unobstructed.

[0046] In a preferred embodiment, the round bottom 71 and the round top 72 are the same shape as a standard wafer, and the round bottom 71 is the same shape as the wafer to be processed by the current process base 2, and the round top 72 is the same shape as a wafer larger than the round bottom 71. The round bottom 71 and the round top 72 are connected together in parallel and fixedly, and can be integrally processed, for example, a wafer with a thickness greater than or equal to the auxiliary component 7 and an area greater than or equal to the round top 72 is polished and engraved to obtain the auxiliary component 7; or two wafers can be bonded together to form, for example, using polytetrafluoroethylene adhesive to directly bond wafers that meet the size and shape requirements of the round bottom 71 and the round top 72 together to form the auxiliary component 7; if the auxiliary component 7 formed by bonding still does not meet the requirements, the component can be further processed by grinding and engraving until it meets the design requirements.

[0047] S3, placing the auxiliary component on the base so that the lower surface of the auxiliary component contacts the upper surface of the base.

[0048] After the auxiliary component 7 is placed on the base 2, the round bottom 71 faces the upper surface of the base 2, and the round top 72 faces the gas shower head 4 and is relatively parallel to the gas shower head 4. After the round bottom 71 of the auxiliary component 7 contacts the base 2, the step of fixing the auxiliary component 7 on the base 2 may be further included. Since the auxiliary component 7 is a semiconductor material, direct current can be passed through the base 2 to fix the auxiliary component 7 by electrostatically adsorbing the round bottom 71; or the auxiliary component 7 can be fixed by mechanical means.

[0049] S4, introducing a cleaning gas to form a plasma to remove the polymer deposited in the reaction chamber.

[0050] The clean gas is excited into plasma by applying source radio frequency. The source radio frequency can be applied to the base 2 as the lower electrode, or to the gas shower head 4 as the upper electrode. The frequency of the source radio frequency is greater than 40MHz. Further, bias radio frequency is applied to enhance the bombardment intensity of the plasma, and the bias radio frequency can be applied to the base 2 as the lower electrode. The frequency of the bias radio frequency is less than 20MHz.

[0051] The cleaning gas includes a carbon fluoride gas, an oxidizing gas and a protective gas. The carbon fluoride gas includes at least carbon tetrafluoride; the oxidizing gas includes at least oxygen; and the protective gas is an inert gas, preferably argon.

[0052] Even if the area of ​​the ground electrode and the area of ​​the base 2 are designed for etching wafers of different sizes, since the auxiliary component 7 placed on the base 2 expands the area of ​​the cathode, that is, reduces the area ratio of the ground electrode to the cathode, the plasma is stimulated to clean the polymer 8 deposited on the ground electrode, which can also significantly improve the cleaning efficiency of the polymer 8 deposited on the ground electrode.

[0053] In some embodiments, the movable ring 6 is controlled to expose the gap in the side wall of the reaction chamber 1, and the auxiliary component 7 is sent into the reaction chamber 1 through the conveying mechanism and placed on the base 2, and the movable ring 6 is controlled to close the gap; after cleaning, the movable ring 6 is controlled again to open the gap, and the auxiliary component 7 is moved out of the reaction chamber 1 through the conveying mechanism.

[0054] Take the reaction chamber originally designed for etching 12-inch wafers as an example. Without increasing the ground electrode and only replacing the base, it is used to etch 8-inch wafers. When the reaction chamber etches 12-inch wafers, the area ratio of the ground electrode to the cathode is about 3:1; when the reaction chamber is modified to etch 8-inch wafers, the area ratio of the ground electrode to the cathode is 6:1.

[0055] S1, providing a reaction chamber, wherein a base is arranged in the reaction chamber.

[0056] The pedestal for placing 8-inch wafers serves as the lower electrode of the reaction chamber; the gas shower head arranged parallel to the pedestal serves as the upper electrode of the reaction chamber and is used to deliver reaction gas to the reaction chamber. A confinement ring is arranged around the pedestal; an upper grounding ring and a moving ring are arranged around the gas shower head. The confinement ring, the gas shower head, the upper grounding ring and the moving ring form the inner wall of the reaction chamber, and the confinement ring, the gas shower head, the upper grounding ring and the moving ring are all grounded. The polymer to be cleaned is deposited on the grounded component surface.

[0057] S2, providing an auxiliary component, wherein the upper surface area of ​​the auxiliary component is larger than the upper surface area of ​​the base.

[0058] The auxiliary components include a round bottom and a round top. The round bottom is an 8-inch wafer, and the round top is a 12-inch wafer. The round bottom and the round top are bonded together using polytetrafluoroethylene adhesive so that the round bottom and the round top are parallel and fixedly connected to form an auxiliary component. The reaction chamber is used to etch 8-inch wafers. The area of ​​the round bottom is equal to the upper surface area of ​​the base, and the area of ​​the round top is larger than the upper surface area of ​​the base. The upper surface area of ​​the base is enlarged to the area of ​​the dome. The ground pole of the reaction chamber was originally designed for etching 12-inch wafers, so at this time, the area ratio of the upper surface area of ​​the base to the ground pole of the reaction chamber is restored from 6:1 to 3:1.

[0059] S3, placing the auxiliary component on the base so that the lower surface of the auxiliary component contacts the upper surface of the base.

[0060] The moving ring is controlled to expose the gap in the side wall of the reaction chamber. After the auxiliary component is sent into the reaction chamber through the conveying mechanism, the moving ring is controlled to close the gap. The round bottom of the auxiliary component is placed toward the base, and the dome is placed toward the gas shower head, and the dome is parallel to the gas shower head. Direct current is passed to the base to fix the auxiliary component on the base by electrostatic adsorption.

[0061] S4, introducing a cleaning gas to form a plasma to remove the polymer deposited in the reaction chamber.

[0062] O is introduced into the reaction chamber. 2 , C.F. 4 A cleaning gas composed of Ar and Ar. A source radio frequency of 60MHz is applied to the gas shower head to excite the cleaning gas into plasma, which corrodes the polymer deposited on the surface of the earth and the upper surface of the auxiliary components. A bias radio frequency of 2MHz is applied to the base to accelerate the positive ions in the plasma, provide activation energy for the plasma to corrode the polymer, and accelerate the cleaning process of the polymer. After the cleaning is completed, the moving ring is controlled to open the gap, and the auxiliary components are moved out of the reaction chamber through the conveying mechanism.

[0063] In summary, the present invention provides a method for improving the cleaning efficiency in a CCP reaction chamber, by placing an auxiliary component consisting of a round bottom and a round top on a base to strengthen the bombardment of the plasma on the ground pole during the cleaning process, thereby improving the cleaning efficiency of the ground pole. When a reaction chamber originally designed for etching a larger area of ​​wafers is used to etch a smaller area of ​​wafers, there is no need to open the chamber to wipe the polymer deposited on the surface of the ground pole, thereby enhancing the operability of this method of improving the utilization rate of the reaction chamber.

[0064] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A method for improving the cleaning efficiency in a CCP reaction chamber, characterized in that: include: A reaction chamber is provided, wherein a base is arranged in the reaction chamber; an upper electrode opposite to the base is arranged in the reaction chamber, and the upper electrode is grounded; Providing an auxiliary component, the upper surface area of ​​the auxiliary component is larger than the upper surface area of ​​the base; the auxiliary component comprises a circular bottom with an area greater than or equal to the upper surface area of ​​the base and a circular top with an area greater than the area of ​​the circular bottom; the auxiliary component is a semiconductor material; placing the auxiliary component on the base so that the lower surface of the auxiliary component contacts the upper surface of the base; A cleaning gas is introduced to form plasma to remove the polymer deposited in the reaction chamber.

2. The method according to claim 1, characterized in that Placing the auxiliary component on the base includes making the lower surface of the round bottom contact with the upper surface of the base and then fixing the auxiliary component.

3. The method according to claim 2, characterized in that Direct current is supplied to the base to generate static electricity to adsorb the round bottom so as to fix the auxiliary component.

4. The method according to claim 2, characterized in that The auxiliary component is fixed by mechanical means.

5. The method according to claim 1, characterized in that The auxiliary component is placed on the base, with the dome relatively parallel to the upper electrode.

6. The method according to claim 1, characterized in that An upper grounding ring and a moving ring surrounding the upper electrode are also provided in the reaction chamber, and the auxiliary component is used to improve the cleaning efficiency of the polymer on the upper electrode, the upper grounding ring and the moving ring.

7. The method according to claim 2, characterized in that The round bottom is made to have the same shape as the wafer to be processed by the base, and the round top is made to have the same shape as the wafer whose area is larger than the base.

8. The method according to claim 2, characterized in that The dome and the dome bottom are integrally formed.

9. The method according to claim 2, characterized in that The dome and the dome bottom are formed by bonding two different wafers together.

10. The method according to claim 5, characterized in that After the cleaning gas is introduced, source radio frequency is applied to excite plasma, and bias radio frequency is applied to enhance the bombardment intensity of the plasma.

11. The method according to claim 10, characterized in that The source radio frequency is applied to the susceptor or the upper electrode, and the bias radio frequency is applied to the susceptor.

12. The method according to claim 10, characterized in that The frequency of the source radio frequency is greater than 40 MHz, and the frequency of the bias radio frequency is less than 20 MHz.

13. The method according to claim 1, characterized in that The cleaning gas includes carbon fluorine gas, oxidizing gas and protective gas.

14. The method according to claim 1, wherein: The auxiliary component is sent into the reaction chamber through a conveying mechanism and placed on the base; after cleaning, the auxiliary component is moved out of the reaction chamber through the conveying mechanism.

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