TW202228186A - Plasma processing apparatus and processing method that includes a reaction chamber that comprises a gas inlet device, a radio frequency power source, a cleaning wafer, and an electrostatic chuck having a surface covered by the cleaning wafer - Google Patents

Abstract

The present invention discloses a plasma processing apparatus and a processing method. The plasma processing apparatus comprises a reaction chamber. The reaction chamber comprises: a gas inlet device that conveys a cleaning gas toward the reaction chamber; a radio frequency power source that dissociates the cleaning gas into cleaning plasma; a cleaning wafer that has a first diameter; and an electrostatic chuck that carries the cleaning wafer and has a second diameter, a difference between the first diameter and the second diameter being less than ±0.5mm. The present invention adopts, in a cleaning step, a cleaning wafer that has a size close to the size the electrostatic chuck to cover a surface of the electrostatic chuck, so as to effectively reduce the damage of an upper surface of the electrostatic chuck caused by the cleaning plasma, and also, the cleaning wafer does not block a second upper surface of a focusing ring and a gap between the focusing ring and the electrostatic chuck, so that the cleaning plasma can effectively remove deposits on the second upper surface of the focusing ring and the gap.

Description

Plasma processing apparatus and processing method

The present invention relates to the technical field of semiconductor equipment, and in particular, to the technical field of plasma cleaning.

In the fabrication of semiconductor devices, plasma etching is a key process for processing wafers into designed patterns.

In a typical plasma etching process, process gases (such as CF ₄ , O ₂ , etc.) form plasma in a reaction chamber under the action of radio frequency (RF) excitation. These plasmas physically bombard and chemically react with the wafer surface to etch wafers with specific structures.

After the wafer is etched, the wafer is taken out by moving the manipulator. In order to ensure the uniformity of wafer processing in different batches, after the wafer is removed from the reaction chamber, it is necessary to clean the reaction chamber with plasma, and pass the flow to the reaction chamber. Enter the cleaning gas, and apply radio frequency to excite the cleaning gas into cleaning plasma. Under the action of the electric field, the cleaning plasma bombards the surface of the parts in the reaction chamber exposed to the plasma, and the parts that may be generated in the previous etching step The sediment is cleaned, and the cleaning gas and sediment particles are discharged out of the reaction chamber through a vacuum device.

With the development of the process, thick deposits will be formed on the surface of the parts during some etching processes. In the cleaning step, in order to ensure the cleaning effect of the deposits, it is necessary to apply a high-power radio frequency signal to the electrostatic chuck. Since the electrostatic chuck is exposed to the cleaning plasma, some areas may be damaged by the bombardment of the cleaning plasma, which is not conducive to the stable operation of the plasma processing device. Therefore, it is necessary to provide a plasma processing device that can work stably during the cleaning step. .

In order to solve the above technical problems, the present invention provides a plasma processing device and a processing method. Wherein, the plasma processing device includes a reaction chamber, and the reaction chamber includes: an air inlet device for delivering clean gas to the reaction chamber; a radio frequency power supply for dissociating the cleaning gas into cleaning plasma; a clean wafer, having a first diameter; and The electrostatic chuck, used for carrying the cleaning wafer, has a second diameter, and the difference between the first diameter and the second diameter is less than or equal to ±0.5mm.

Preferably, the difference between the first diameter and the second diameter is less than ±0.2 mm.

Preferably, the first diameter and the second diameter are the same.

Preferably, a focus ring is arranged around the electrostatic chuck, a first gap is arranged between the focus ring and the electrostatic chuck, and the width of the first gap is greater than or equal to 0.2 mm.

Preferably, the focus ring includes a first upper surface and a second upper surface, the first upper surface is higher than the upper surface of the cleaning wafer, and the second upper surface is lower or flat than the cleaning wafer. the lower surface of the wafer.

Preferably, when the cleaning wafer is located above the electrostatic chuck, the first gap and the second upper surface are exposed.

Preferably, an insertion ring is arranged under the focus ring, a second gap is arranged between the insertion ring and the electrostatic chuck, and the width of the second gap is less than or equal to the width of the first gap.

Preferably, the lower surface of the focus ring and the upper surface of the insertion ring are provided with steps that cooperate with each other.

Preferably, the material of the cleaning wafer includes at least one of silicon, silicon carbide and dielectric materials.

Preferably, the electrostatic chuck comprises an electrostatic adsorption layer, a base and a bonding layer connecting the electrostatic adsorption layer and the base, and a protection ring is arranged around the periphery of the bonding layer.

Further, the present invention also discloses a plasma treatment method, the method is performed in the above-mentioned plasma treatment device, and the plasma treatment method includes the following steps: The etching process is finished, and the etched wafer is removed from the reaction chamber; moving the clean wafer into the reaction chamber and placing it above the electrostatic chuck; supplying a cleaning gas into the reaction chamber, applying radio frequency power to excite the cleaning gas into a cleaning plasma, and the cleaning plasma cleans a region of the reaction chamber exposed to the plasma; and The cleaning wafer is removed.

Compared with the prior art, the technical solutions of the embodiments of the present invention have the following beneficial effects: In the present invention, in the cleaning step, a cleaning wafer with a size similar to the electrostatic chuck is used to cover the surface of the electrostatic chuck, which can effectively reduce the degree of damage caused by the cleaning plasma to the upper surface of the electrostatic chuck. The upper surface and the gap between the focus ring and the electrostatic chuck cause occlusion, so that the cleaning plasma can effectively remove the deposits in the second upper surface of the focus ring and the gap. Ensure the uniformity of the wafer processed by the plasma processing device, reduce the arc discharge phenomenon that may be caused by deposits, and improve the stability of the equipment.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those with ordinary knowledge in the technical field of the present invention without making progressive changes shall fall within the protection scope of the present invention.

FIG. 1 shows a plasma processing apparatus, which includes a reaction chamber, the reaction chamber includes an upper electrode element and a lower electrode element arranged oppositely, and the upper electrode element includes a gas shower head 120 and a gas shower head 120 arranged around the gas shower head. The upper ground ring 122 and the gas shower head 120 are used for delivering process gas or cleaning gas into the reaction chamber, and at the same time as the upper electrode of the vacuum reaction chamber. The reaction chamber also includes a lift ring 124, which surrounds the area disposed between the upper electrode element and the lower electrode element to form a uniform and stable plasma processing space. The plasma processing apparatus shown in FIG. 1 is a capacitively coupled plasma processing apparatus, and the solution described in the present invention is also applicable to an inductively coupled plasma processing apparatus.

The lower electrode element includes an electrostatic chuck 110, the electrostatic chuck 110 includes an electrostatic adsorption layer 112, a base 116, and a bonding layer 114 connecting the electrostatic adsorption layer and the base, and a protection ring is arranged around the periphery of the bonding layer 182. The guard ring 182 can protect the bonding layer from being damaged by the plasma, and at the same time, can separate the gap between the focus ring and the insertion ring and the electrostatic chuck to reduce arc discharge in the gap. The electrostatic chuck is used to carry the wafer 115 and also serves as the lower electrode of the vacuum reaction chamber, and a reaction area is formed between the upper electrode and the lower electrode. At least one radio frequency power supply 190 is applied to one of the upper electrode or the lower electrode through a matching network, and a radio frequency electric field is generated between the upper electrode and the lower electrode, so as to dissociate the reactive gas into plasma, and in the plasma, a radio frequency electric field is generated. It contains a large number of active particles such as electrons, ions, excited atoms, molecules and free radicals. The above active particles can undergo various physical and chemical reactions with the surface of the substrate to be processed, so that the morphology of the wafer surface changes, that is, the surface of the wafer is changed. The wafer is etched. An exhaust device (not shown in the figure) is also arranged below the vacuum reaction chamber, which is used to discharge the reaction by-products from the reaction chamber and maintain the vacuum environment of the reaction chamber.

An edge ring element is arranged around the periphery of the electrostatic chuck 110 . The edge ring element specifically includes a focus ring 130 , a cover ring 140 is arranged around the periphery of the focus ring 130 , and an insertion ring 150 is arranged below the focus ring 130 . The focus ring 130, the cover ring 140 and the insert ring 150 are used to adjust the electric field or temperature distribution around the wafer to improve the uniformity of the substrate processing. An isolation ring 170 is disposed below the insertion ring 150 , and the isolation ring 170 is disposed around the base 116 for controlling the temperature of the insertion ring 150 and isolating the base 116 . The edge ring element also includes a plasma confinement ring 160 disposed around the insert ring 150 and the spacer ring 170, the plasma confinement ring 160 is used to form an exhaust passage while confining the plasma within the plasma processing volume. The material of the base 116 is usually metal, and the material of the edge ring element is usually a dielectric material or a semiconductor material. In order to avoid the heat expansion of the base 116 during the manufacturing process, which squeezes the edge ring element, the electrostatic chucks 110 and 110 are installed at room temperature. When the edge ring element is used, a gap 185 is usually set between the electrostatic chuck 110 and the edge ring element, as shown in FIG. 2 . The width of the gap 185 is determined according to factors such as the material of the base and the edge ring element and the possible working temperature of the lower electrode element. OK, usually set between 0.1mm-0.5mm.

During the normal plasma treatment of the wafer 115, the wafer 115 is moved into the reaction chamber and placed above the electrostatic chuck 110, and is fixed and temperature controlled under the adsorption of the electrostatic chuck 110. In order to realize that the wafer 115 is placed on the electrostatic chuck For accurate positioning at the top, a positioning gap will be set on the edge area of the conventional wafer. In order to prevent the positioning gap from exposing part of the electrostatic chuck 110 during the etching process, the exposed area of the electrostatic chuck 110 will be damaged by plasma. The diameter dimension of 115 is generally larger than the diameter dimension of electrostatic chuck 110 .

2 shows a partial enlarged view of the area A in FIG. 1 during the etching step. According to FIG. 2 , the focus ring 130 includes a first upper surface 132 and a second upper surface 134 when the wafer 115 is placed over the electrostatic chuck 110 , the level of the first upper surface 132 is higher than the level of the upper surface of the wafer 115, and the level of the second upper surface 134 is lower than or flush with the level of the lower surface of the wafer 115, so During the etching process, the edge region of the wafer 115 at least partially covers the second upper surface 134 of the focus ring 130 and the gap between the focus ring 130 and the electrostatic chuck 110 .

However, during the etching process, while the plasma etches the topography of the surface of the wafer 115, deposits will also be formed on the surfaces of the parts exposed to the plasma, including the backside of the wafer 115, the focus The two upper surfaces of the ring 130 and the gap 185 between the focus ring 130 and the electrostatic chuck 110, the second upper surface 134 of the focus ring 130 and the black line in the gap 185 in FIG. After the etching process is completed, the wafer 115 is moved out of the reaction chamber by a mobile robot. In order to ensure the uniformity of etching of different wafers, a plasma cleaning step is performed in the reaction chamber after each etching process. Usually, no wafer is placed on the surface of the electrostatic chuck 110 , and the electrostatic chuck 110 and other surfaces exposed to the plasma processing space can remove the deposits through chemical reaction or physical bombardment under the action of the cleaning plasma.

With the development of the manufacturing process, the inventors found that some processes will generate thicker deposits during the etching process. Power means stronger plasma bombardment, which can cause more severe damage to the top surface of the electrostatic chuck exposed to the plasma. In addition, if there is deposits in the gap between the focus ring and the electrostatic chuck, since the deposits are usually loose, arc discharge is likely to occur during the etching process, causing damage to the side of the electrostatic chuck.

FIG. 3 shows a partial enlarged view of the area A in FIG. 1 during the cleaning step, a plasma processing apparatus which can be used for both the plasma etching step and the plasma cleaning step. The reaction chamber of the device includes an air inlet device, namely the gas shower head 120 described above, for delivering cleaning gas to the reaction chamber; a radio frequency power source 190 for dissociating the cleaning gas into cleaning plasma; cleaning The wafer 215 has a first diameter; the electrostatic chuck 110 is used for carrying the cleaning wafer 215 and has a second diameter, and the difference between the first diameter and the second diameter is less than or equal to ±0.5mm. In the present invention, in the cleaning step, the cleaning wafer 215 with a size similar to that of the electrostatic chuck 110 is used to cover the surface of the electrostatic chuck 110 , which can effectively reduce the damage degree of the cleaning plasma to the upper surface of the electrostatic chuck 110 . The second upper surface 134 of the focus ring 130 and the gap between the focus ring 130 and the electrostatic chuck 110 are blocked, so that the cleaning plasma can effectively remove the second upper surface 134 of the focus ring 130 and the deposits in the gap. Ensure the uniformity of the wafers processed by the plasma processing device.

The present invention defines that the difference between the first diameter and the second diameter is less than or equal to ±0.5 mm. When the first diameter of the cleaning wafer 215 is smaller than the second diameter of the electrostatic chuck 110 within 0.5 mm, the cleaning wafer 215 will not be able to touch the electrostatic chuck 110 . Most of the upper surface of the wafer 215 is covered, which can effectively protect the electrostatic chuck 110 from being bombarded by the cleaning plasma. When the first diameter of the cleaning wafer 215 is larger than the second diameter of the electrostatic chuck 110 within 0.5mm The second upper surface 134 of the focus ring 130 is blocked, so that the second upper surface 134 of the focus ring 130 can effectively remove the deposits.

Preferably, the difference between the first diameter and the second diameter is less than ±0.2mm, which can better cover the surface of the electrostatic chuck 110 and reduce the blocking of the gap between the focus ring 130 and the electrostatic chuck 110 . According to the previous knowledge, the gap between the focus ring 130 and the electrostatic chuck 110 is usually set to be between 0.1mm-0.5mm. Therefore, in order to ensure that at least part of the slit is exposed to the cleaning plasma, when the first diameter is greater than the second diameter, the difference between the first diameter and the second diameter is defined to be less than or equal to 0.2 mm. Preferably, the diameter of the cleaning wafer 215 can be set to be equal to the diameter of the electrostatic chuck 110 .

Figure 4 shows a partial enlarged view of area A after the cleaning step has been completed. It can be seen from FIG. 4 that, after using the cleaning wafer 215 of the present invention, even if a relatively large radio frequency power is applied to the reaction chamber for cleaning, the surface of the electrostatic chuck 110 will not be damaged. The diameter size is close to the diameter size of the electrostatic chuck 110 and will not cover the second upper surface 134 and the slit 185 of the focus ring 130 , so that the cleaning plasma is more effective for the second upper surface 134 and the slit 185 of the focus ring 130 . The deposited deposits are removed, avoiding arc discharge that may occur in the deposits, and ensuring the consistency of wafer processing in the reaction chamber.

According to the foregoing description, an insertion ring 150 is disposed under the focusing ring 130 , and a gap is also set between the insertion ring 150 and the electrostatic chuck 110 , and the width of the gap is equal to or smaller than the width of the gap between the focusing ring 130 and the electrostatic chuck 110 . The width of the gap between the focus ring 130 and the electrostatic chuck 110 . The gap between the edge ring element and the electrostatic chuck 110 is a high-incidence area where arc discharge occurs. Under the premise of bearing the expansion of the base, the gap 185 is set as small as possible.

In addition, the lower surface of the focus ring 130 and the upper surface of the insertion ring 150 may be provided with steps that cooperate with each other. The setting of the step can prevent the contact gap between the focus ring 130 and the insertion ring 150 from being connected to the gap 185, and prevent the arc discharge that may occur in the gap 185 from penetrating into the gap between the focus ring 130 and the insertion ring 150. 130 and insert ring 150 for protection.

The material of the cleaning wafer 215 used in the present invention can be the same as that of the conventional wafer 115. Preferably, the material of the cleaning wafer 215 includes at least one of silicon, silicon carbide and dielectric materials, so as not to be introduced in the cleaning step Pollution is the main consideration.

The present invention further discloses a plasma treatment method, which comprises the following steps:

After the etching process is completed, the etched wafer 115 is removed from the reaction chamber;

moving the cleaning wafer 215 into the reaction chamber and placing it above the electrostatic chuck 110;

supplying a cleaning gas into the reaction chamber, applying radio frequency power to excite the cleaning gas into a cleaning plasma, and the cleaning plasma cleans a region of the reaction chamber exposed to the plasma; and

The cleaning wafer 215 is removed.

Although the present invention is disclosed above, the present invention is not limited thereto. Anyone with ordinary knowledge in the technical field to which the present invention pertains does not deviate from it. Various changes and modifications can be made within the spirit and scope of the present invention, so the protection scope of the present invention should be based on the scope defined by the claims.

110: Electrostatic chuck 112: Electrostatic adsorption layer 114: Bonding Layer 115: Wafer 116: Pedestal 120: Gas sprinkler head 122: Upper ground ring 124: Lifting ring 130: Focus Ring 132: First upper surface 134: Second upper surface 140: Cover Ring 150: Insert Ring 160: Plasma Confinement Ring 170: Isolation Ring 182: Protection Ring 185: Gap 190: RF Power 215: Clean Wafer

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those with ordinary knowledge in the technical field to which the present invention pertains, other drawings can also be obtained according to the provided drawings without making progressive changes. 1 shows a schematic structural diagram of a plasma processing device; FIG. 2 shows a partial enlarged view of the area A in FIG. 1 in the etching step; FIG. 3 shows a partial enlarged view of the area A in FIG. 1 during the cleaning step; and Figure 4 shows a partial enlarged view of area A after the cleaning step has been completed.

110: Electrostatic chuck

112: Electrostatic adsorption layer

114: Bonding Layer

115: Wafer

116: Pedestal

120: Gas sprinkler head

122: Upper ground ring

124: Lifting ring

130: Focus Ring

140: Cover Ring

150: Insert Ring

160: Plasma Confinement Ring

170: Isolation Ring

190: RF Power

Claims (11)

A plasma processing device, comprising a reaction chamber, wherein: the reaction chamber comprises: an air inlet device for delivering a cleaning gas to the reaction chamber; a radio frequency power source for dissociating the cleaning gas into a cleaning plasma; a clean wafer having a first diameter; and An electrostatic chuck for carrying the cleaning wafer has a second diameter, and the difference between the first diameter and the second diameter is less than or equal to ±0.5mm. The plasma processing apparatus as set forth in claim 1, wherein: the difference between the first diameter and the second diameter is less than ±0.2 mm. The plasma processing apparatus of claim 1, wherein: the first diameter and the second diameter are the same. The plasma processing apparatus of claim 1, wherein: a focus ring is arranged around the electrostatic chuck, a first gap is arranged between the focus ring and the electrostatic chuck, and the width of the first gap is greater than or equal to 0.2 mm. The plasma processing apparatus of claim 4, wherein: the focus ring includes a first upper surface and a second upper surface, the first upper surface is higher than the upper surface of the cleaning wafer, the second upper surface below or level with the lower surface of the clean wafer. The plasma processing apparatus as set forth in claim 5, wherein: the first gap and the second upper surface are exposed when the cleaning wafer is located above the electrostatic chuck. The plasma processing apparatus as shown in claim 4, wherein: an insertion ring is arranged below the focus ring, a second gap is arranged between the insertion ring and the electrostatic chuck, and the width of the second gap is less than or equal to the first gap The width of the gap. The plasma processing device as shown in claim 7, wherein: the lower surface of the focus ring and the upper surface of the insertion ring are provided with a step that cooperates with each other. The plasma processing apparatus of claim 1, wherein: the material of the cleaning wafer includes at least one of silicon, silicon carbide and dielectric materials. The plasma processing apparatus as claimed in claim 1, wherein: the electrostatic chuck comprises an electrostatic adsorption layer, a base, and a bonding layer connecting the electrostatic adsorption layer and the base, and a circumference of the bonding layer is arranged in a circle guard ring. A plasma processing method, wherein: the method is carried out in the plasma processing apparatus according to any one of claims 1-10, and the plasma processing method comprises the following steps: After the etching process is completed, the etched wafer is removed from the reaction chamber; moving the cleaning wafer into the reaction chamber and placing it above the electrostatic chuck; supplying the cleaning gas into the reaction chamber, applying radio frequency power to excite the cleaning gas into the cleaning plasma, and the cleaning plasma cleaning the region of the reaction chamber exposed to the plasma; and Remove the cleaning wafer.

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