A surface treatment method for a deposition surface inside an etching chamber of a metal etcher

Abstract

The present invention discloses a surface treatment method for the internal deposition surface of an etching chamber of a metal etcher, comprising: processing the inner surface of a ceramic dielectric window, so that the roughness of the inner surface of the ceramic dielectric window directly facing the chamber is increased to Ra5-Ra6, and the roughness of the sealing surface between the ceramic dielectric window and the chamber cover is reduced to below R0.4; adding a heat source on the outer surface of the ceramic dielectric window, so that the ceramic dielectric window maintains its own temperature above 80°C during wafer processing. The present invention combines two auxiliary schemes of increasing roughness and high temperature assistance, so that the time during which the deposited film can continue to not break during the process of the reaction chamber of the metal etcher is extended to more than 180 RF hours, thereby reducing the cavity opening cleaning cycle and increasing production capacity.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor dry etching, and in particular to a surface treatment method for a deposition surface inside an etching chamber of a metal etcher. Background Art

[0002] In the semiconductor dry etching process, according to the different materials to be etched, it can be divided into metal etching, dielectric etching and silicon etching. Metal etching can be further divided into metal aluminum etching, metal tungsten etching and titanium nitride etching. At present, metal aluminum is still widely used as a wiring material in memories such as DRAM and flash, as well as logic products above 0.13um.

[0003] At present, the etching chamber of the metal etcher widely adopts a dual RF power source design. The bias power is used to accelerate positive ions and provide vertical physical bombardment, and the source power is used to increase the concentration of the plasma in the reaction chamber. This dual-power design can achieve independent control of the energy and concentration of the ions, expanding the process window and performance of the etching process. The etching chamber of the metal etcher mainly includes four parts: the pre-vacuum chamber, the etching chamber, the gas supply system and the vacuum system. Among them, the etching chamber is the core structure of the plasma etcher, which has a direct impact on the etching rate, the verticality of the etching and the roughness. Figure 1 As shown, the main components of the etching chamber are: RF coil 001, ceramic dielectric window 002, chamber cover 003, gas inlet nozzle 004, shielding cover 008, excitation RF power supply 011, matching network 010, gas source 012, bias electrode 020, plasma reaction chamber 022, bias RF power supply 021, matching network 025, pressure control valve 023, vacuum pump 024 pre-pumping pipeline 029, pre-pumping valve 026, fore valve 027, fore pipeline 030, dry pump 028, etc. The inside of the etching chamber is a vacuum chamber, which is in a vacuum state during the process, and the inner wall of the vacuum chamber is composed of multiple parts. During the process of the metal etcher etching chamber, a large amount of reaction products will be generated in the vacuum chamber, most of which will be pumped away by the vacuum pump 024, but some of the reaction products will be deposited around the reaction chamber, including the ceramic dielectric window 002 in the vacuum, the surface of the reaction chamber 022 in the vacuum, and the surface of the bias electrode in the vacuum. These reaction products form a deposited film on the inner wall of the reaction chamber, especially the thickest film product deposited on the ceramic dielectric window 002 just above the electrode. This part of the deposited film breaks due to stress, temperature and other reasons after a period of time, and eventually falls to various places in the chamber. Some broken film layers fall onto the wafer, which will affect the process results and even damage the wafer. In this case, production must be stopped and the chamber must be opened for cleaning. Therefore, the time that the deposited layer of an ordinary metal etcher continues to break determines how long the etching chamber can be kept from stopping production.

[0004] The invention with patent number KR1020070006326A also proposed that the surface roughness can be controlled at 120uinch (3um) or above. Furthermore, the invention with patent number US20060086458A1 proposed a method for controlling the surface roughness of a ceramic lining, in which the ceramic lining is treated by an abrasion process to change the surface roughness to 140±40μinch (3.5±1um), so that the polymer formed by the plasma gas reaction adheres to the ceramic lining. The invention also points out that if the surface is too smooth (<100μinch, i.e. <2.5um), then if the surface is too rough (>180μinch, i.e. >4.5um), the polymer will not adhere again because the surface is too brittle, so 140±40μinch is a more reasonable roughness choice. The above two inventions increase the adsorption force of the polymer by increasing the surface roughness within the allowable range, thereby extending the single use time of the chamber. However, it has been proven in practice that the aforementioned roughness has limited effect on extending the single-time use time of the chamber. Due to the chamber environment, ordinary chambers can generally only maintain the process for less than 100 hours, affecting customer production capacity.

[0005] The invention with patent number CN109671607A proposes a workpiece processing method and process chamber, and proposes a new concept for the processing method of the dielectric window. First, the surface of the intermediate semi-finished product of the dielectric window is sandblasted, and the surface of the intermediate semi-finished product after sandblasting is soaked in an acidic solution to maintain the surface roughness value of the dielectric window between Ra6.3 and Ra12.5. Therefore, the surface of the dielectric window can absorb more process by-products, and prevent the process by-products from falling off the surface of the dielectric window to form particulate impurities, thereby improving the processing rate of the wafer. However, the processing process requires sandblasting and acid solution soaking at the same time, and the processing process is quite complicated and the parameters are difficult to control. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a surface treatment method for the deposition surface inside the etching chamber of a metal etcher, which combines two auxiliary schemes, namely, increasing the roughness and high-temperature assistance, so that the time during which the deposition film can continue to remain unbroken during the process in the reaction chamber of the metal etcher is extended to more than 180 radio frequency hours (RFh), thereby reducing the cavity opening cleaning cycle and increasing production capacity.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The embodiment of the present invention provides a surface treatment method for a deposition surface inside an etching chamber of a metal etcher, the surface treatment method comprising the following steps:

[0009] The inner surface of the ceramic dielectric window is processed so that the roughness of the inner surface of the ceramic dielectric window directly facing the chamber is increased to Ra5-Ra6, and the roughness of the sealing surface between the ceramic dielectric window and the chamber cover is reduced to below R0.4;

[0010] A heat source is added to the outer surface of the ceramic dielectric window so that the ceramic dielectric window maintains its own temperature above 80° C. during wafer processing.

[0011] Furthermore, the process of processing the inner surface of the ceramic dielectric window includes the following steps:

[0012] A preliminary semi-finished ceramic dielectric window is obtained by firing a ceramic mold blank having a thickness ranging from 20 mm to 30 mm;

[0013] The overall size is finely processed on the machine tool to reduce the roughness of the ceramic dielectric window to below Ra0.8 and maintain the thickness within the range of 15mm to 25mm;

[0014] A first inner surface area where the ceramic dielectric window contacts the cavity cover is covered with a cow paper film;

[0015] Using 60-80 mesh quartz sand or ceramic sand to sandblast the second inner surface area of ​​the ceramic medium window directly facing the chamber, so that the roughness of the second inner surface area is increased to Ra5-Ra6;

[0016] The kraft paper film is removed, and the first inner surface region is polished to reduce the roughness of the first inner surface region to below R0.4, thereby obtaining a final ceramic dielectric window product.

[0017] Furthermore, the process of processing the inner surface of the ceramic dielectric window also includes:

[0018] The ceramic media window was mounted on a rotating table and sandblasted;

[0019] During the sandblasting process, the angle between the ceramic medium window and the ground is controlled within the range of 70° to 80°, and the rotation speed of the rotary table is maintained at 150 to 200 revolutions per minute.

[0020] Furthermore, the control parameters of the sandblasting process are: compressed air pressure is 0.6-0.8Mpa, and the sandblasting distance is 6-8 meters.

[0021] Furthermore, the surface treatment method further comprises:

[0022] A silica gel template heating device is detachably mounted on the outer surface of the ceramic dielectric window to maintain the temperature of the ceramic dielectric window greater than 80°C.

[0023] Furthermore, the surface treatment method further comprises:

[0024] The workpiece is used to press the silicone template heating device directly onto the outer surface of the ceramic dielectric window.

[0025] Furthermore, during wafer processing, the temperature of the ceramic dielectric window is maintained in the range of 80° C. to 120° C.

[0026] The present invention also mentions an etching chamber for a metal etcher, the etching chamber comprising a plasma reaction chamber and a ceramic dielectric window, the ceramic dielectric window covers the plasma reaction chamber and forms a closed cavity with the plasma reaction chamber, and the ceramic dielectric window is manufactured by the aforementioned method.

[0027] The beneficial effects of the present invention are:

[0028] The surface treatment method for the internal deposition surface of the etching chamber of a metal etcher proposed in the present invention uses high temperature assistance to control the roughness of the ceramic dielectric window within the range of Ra5 to 6, thereby greatly improving the time that the deposited film in the process chamber can continue to remain unbroken, reducing the cavity opening and cleaning cycle, and increasing production capacity. At the same time, it simplifies the entire processing flow and improves the parameter control accuracy during the processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the structure of the etching chamber of a metal etcher.

[0030] Figure 2 The present invention is a flow chart of a surface treatment method for a deposition surface inside an etching chamber of a metal etcher according to an embodiment of the present invention.

[0031] Figure 3 Schematic diagram of the clamping state of the ceramic dielectric window according to an embodiment of the present invention.

[0032] Figure 4 Schematic diagram of the shedding of the deposited film on the ceramic dielectric window without sandblasting.

[0033] Figure 5 Schematic diagram of the roughness of the ceramic dielectric window according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The present invention will now be described in further detail with reference to the accompanying drawings.

[0035] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0036] Embodiment 1

[0037] Figure 2 This is a flow chart of a method for treating a deposition surface in an etching chamber of a metal etcher according to an embodiment of the present invention. Figure 2 , the surface treatment method comprises the following steps:

[0038] The inner surface of the ceramic dielectric window 002 is processed so that the roughness of the inner surface of the ceramic dielectric window 002 directly facing the chamber is increased to Ra5-Ra6, and the roughness of the sealing surface between the ceramic dielectric window 002 and the chamber cover 003 is reduced to below R0.4. A heat source is added to the outer surface of the ceramic dielectric window 002 so that the ceramic dielectric window 002 maintains its own temperature above 80°C during wafer processing.

[0039] The ceramic dielectric window 002 directly affects the yield rate of the wafer processing technology due to the particularity of its installation position. Figure 4 This is a schematic diagram of the deposition film falling off when the ceramic dielectric window is not sandblasted. Figure 4 In the process, the vacuum inner wall surface of the ceramic dielectric window 002 on the plasma reaction chamber of the etching chamber of the metal etcher is relatively smooth, Ra < 0.8; the temperature of the ceramic dielectric window 002 is between 25 and 40°C (in the traditional wafer etching process, no heat source is usually set on the outside of the ceramic dielectric window 002, or a low-temperature heat source is set). After testing, the deposited film can continue to not break during the process for less than 40RFh.

[0040] However, simply increasing the roughness of the inner surface of the ceramic dielectric window 002 to Ra5-6 cannot further increase the accumulation time of the deposited film. It is necessary to simultaneously add a heat source to the upper surface of the ceramic dielectric window 002 to make the temperature of the ceramic dielectric window 002 greater than 80°C, and preferably between 80°C and 120°C. High temperature can effectively reduce the amount of products deposited each time a single wafer is processed, and the by-products that are not deposited can be promptly pumped away by the vacuum pump 024. Under the premise of combining the above two solutions, the deposited film in the process of the metal etching machine reaction chamber can continue to be unbroken for more than 180 radio frequency hours (RFh), thereby reducing the cavity cleaning cycle and increasing production capacity.

[0041] Illustratively, the present embodiment uses a silicone membrane heating device as a heat source, which is different from the conventional polyimide paste heating; the polyimide paste is directly attached to the ceramic dielectric window 002 and cannot be removed, and a separate cleaning jig is required when repairing and cleaning the ceramic dielectric window 002; the silicone membrane plate is directly pressed against the surface of the ceramic dielectric window 002 by the workpiece, and can be directly disassembled and assembled on site.

[0042] As a preferred example, the process of processing the inner surface of the ceramic dielectric window 002 includes the following steps:

[0043] S11, the ceramic mold blank is fired to obtain a preliminary semi-finished ceramic dielectric window 002. In order to ensure the subsequent sandblasting effect and heat transfer effect, and to ensure a suitable processing allowance, the thickness of the ceramic mold blank is preferably within the range of 20 to 30 mm.

[0044] S12, performing overall size finishing on a machine tool to reduce the roughness of the ceramic dielectric window 002 to below Ra0.8 and maintain the thickness within the range of 15 mm to 25 mm.

[0045] S13, using a kraft paper film to cover the first inner surface area of ​​the ceramic medium window 002 in contact with the cavity cover 003. In order to prevent the sealing surface between the ceramic medium window 002 and the cavity cover 003 from being damaged during the sandblasting process, a special kraft paper film is required to cover the sealing surface, and then a separate polishing process is performed after sandblasting.

[0046] S14, using 60-80 mesh quartz sand or ceramic sand to sandblast the second inner surface area of ​​the ceramic medium window 002 directly facing the chamber, so that the roughness of the second inner surface area is increased to Ra5-Ra6, which can better adsorb byproducts such as photoresist in the groove with larger roughness. Quartz sand is preferably used as the sandblasting medium.

[0047] S15, removing the kraft paper film, and polishing the first inner surface area to reduce the roughness of the first inner surface area to below R0.4, thereby ensuring the sealing effect, thereby obtaining the final finished product of the ceramic dielectric window 002. Figure 5 Schematic diagram of the roughness of the ceramic dielectric window according to an embodiment of the present invention.

[0048] The ceramic medium window 002 of this embodiment is sandblasted by a pressure-type sandblasting process, which uses compressed air to form a high-speed jet beam. In order to achieve the above-mentioned roughness requirements and avoid impact damage to the entire sandblasting surface, the compressed air pressure needs to be controlled within 0.6-0.8Mpa, and the sandblasting distance needs to be controlled within the range of 6-8 meters, which can improve the processing yield and reduce the manufacturing cost. Figure 3 As shown, in order to prevent the quartz sand or ceramic sand after sandblasting from rebounding and reducing the new gravel to act on the ceramic surface, the ceramic medium window 002 can be installed on the rotating table with the angle between the ground and the ground controlled at 70-80° and the rotation speed at 150-200 rpm.

[0049] Embodiment 2

[0050] This embodiment also mentions an etching chamber for a metal etcher, the etching chamber comprising a plasma reaction chamber and a ceramic dielectric window, the ceramic dielectric window covers the plasma reaction chamber and forms a closed cavity with the plasma reaction chamber, and the ceramic dielectric window is manufactured by using any one of the surface treatment methods in Embodiment 1.

[0051] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A surface treatment method for a deposition surface inside an etching chamber of a metal etcher, characterized in that: The surface treatment method comprises the following steps: The inner surface of the ceramic dielectric window is processed so that the roughness of the inner surface of the ceramic dielectric window directly facing the chamber is increased to Ra5-Ra6, and the roughness of the sealing surface between the ceramic dielectric window and the chamber cover is reduced to less than R0.4; Add a heat source on the outer surface of the ceramic dielectric window to keep the temperature of the ceramic dielectric window above 80°C during wafer processing; The process of processing the inner surface of the ceramic dielectric window comprises the following steps: A preliminary semi-finished ceramic dielectric window is obtained by firing a ceramic mold blank having a thickness ranging from 20 mm to 30 mm; The overall size is finely processed on the machine tool to reduce the roughness of the ceramic dielectric window to below Ra0.8 and maintain the thickness within the range of 15mm to 25mm; A first inner surface area where the ceramic dielectric window contacts the cavity cover is covered with a cow paper film; performing sandblasting on a second inner surface area of ​​the ceramic dielectric window directly facing the chamber, so that the roughness of the second inner surface area is increased to Ra5-Ra6; The kraft paper film is removed, and the first inner surface region is polished to reduce the roughness of the first inner surface region to below R0.4, thereby obtaining a final ceramic dielectric window product.

2. The surface treatment method for the deposition surface inside the etching chamber of a metal etcher according to claim 1, characterized in that: The second inner surface area of ​​the ceramic medium window directly facing the chamber is sandblasted with quartz sand or ceramic sand.

3. The surface treatment method for the deposition surface inside the etching chamber of a metal etcher according to claim 2, characterized in that: The second inner surface area of ​​the ceramic medium window directly facing the chamber is sandblasted using 60-80 mesh quartz sand or ceramic sand.

4. The surface treatment method for the deposition surface inside the etching chamber of a metal etcher according to claim 1, characterized in that: The process of processing the inner surface of the ceramic dielectric window also includes: The ceramic media window was mounted on a rotating table and sandblasted; During the sandblasting process, the angle between the ceramic medium window and the ground is controlled within the range of 70° to 80°, and the rotation speed of the rotary table is maintained at 150 to 200 revolutions per minute.

5. The surface treatment method for the deposition surface inside the etching chamber of a metal etcher according to claim 4, characterized in that: The control parameters of the sandblasting process are: compressed air pressure is 0.6-0.8Mpa, and the sandblasting distance is 6-8 meters.

6. The surface treatment method for the deposition surface inside the etching chamber of a metal etcher according to claim 1, characterized in that: The surface treatment method further comprises: A silica gel template heating device is detachably mounted on the outer surface of the ceramic dielectric window to maintain the temperature of the ceramic dielectric window greater than 80°C.

7. The surface treatment method for the internal deposition surface of the etching chamber of a metal etcher according to claim 1, characterized in that: The surface treatment method further comprises: The workpiece is used to press the silicone template heating device directly onto the outer surface of the ceramic dielectric window.

8. The surface treatment method for the internal deposition surface of the etching chamber of a metal etcher according to claim 1, characterized in that: During wafer processing, the temperature of the ceramic dielectric window is maintained in the range of 80°C to 120°C.

9. An etching chamber for a metal etcher, the etching chamber comprising a plasma reaction chamber and a ceramic dielectric window, the ceramic dielectric window covering the plasma reaction chamber and forming a closed chamber with the plasma reaction chamber, characterized in that: The ceramic dielectric window is manufactured by the method according to any one of claims 1 to 8.

Images