TWI633573B - Plasma processing device and method - Google Patents

Abstract

The invention provides a plasma processing device and a method for processing a substrate in the plasma processing device. The plasma processing device includes a reaction chamber, and an upper electrode and a lower electrode are arranged in the reaction chamber. The present invention sets a hollow insulation ring around the periphery of the lower electrode, and sets a radio frequency coil in the hollow insulation ring, by applying radio frequency to the radio frequency coil during the cleaning process The power can increase the degree of dissociation of the cleaning gas in the edge area, thereby increasing the concentration of the cleaning plasma in the edge area; a high concentration of cleaning plasma is helpful to ensure the cleaning effect of the components in the edge area. In the etching process, by setting the RF coil ground, it is possible to effectively prevent the RF power applied to the lower electrode from generating a discharge on the RF coil.

Description

Plasma processing device and method

The invention provides the field of semiconductor manufacturing, and in particular, a technical field of internal cleaning of a plasma processing apparatus.

Plasma reaction devices are widely used in the manufacturing process of integrated circuits, such as deposition and etching. Among them, the commonly used plasma etching reaction device includes a capacitive coupling plasma reaction device CCP and an inductive coupling plasma device ICP. The principle of the plasma reaction device mainly uses radio frequency power to dissociate the reaction gas input into the reaction device into a plasma By using the plasma to perform plasma etching treatment on the substrates placed inside, different substrates require different reaction gases for the etching process, and different reaction by-products will also be generated. Some reaction by-products occur between each other. The reaction is deposited on the inner side wall or other components of the reaction chamber, which affects the subsequent reaction process.

In order to ensure the stable process environment of each substrate, after a substrate etching process is completed and the reaction chamber is removed, the inside of the reaction chamber needs to be cleaned to remove the deposition of reaction byproducts in the previous substrate etching process. The cleaning process for the inside of the reaction chamber is usually to pass a cleaning gas into the reaction chamber, apply radio frequency power to the reaction chamber, dissociate the cleaning gas into a cleaning plasma, and use the cleaning plasma to clean the side walls and internal components in the reaction chamber. . In the cleaning process, the concentration distribution of the cleaning plasma is an important factor affecting the degree of cleanliness in the reaction chamber. In the capacitive coupling plasma reaction device, the cleaning plasma is generated by the electric field between the upper electrode and the lower electrode, and the edge area is caused by the uneven distribution of the electric field lines between the upper electrode and the lower electrode. The plasma concentration is lower than that in the center area Concentration, which results in poor cleaning of parts in the edge region of the reaction chamber, reduces the cleaning efficiency of the equipment, and makes it difficult to ensure a consistent process environment for each substrate.

In order to solve the above technical problems, the present invention provides a plasma processing apparatus, which includes a reaction chamber, wherein an upper electrode and a lower electrode are disposed in the reaction chamber, and an electrostatic chuck for supporting and fixing a substrate is disposed above the lower electrode. A hollow insulating ring is arranged around the periphery of the electrostatic chuck, and a radio frequency coil is arranged in the hollow insulating ring. The radio frequency coil communicates with a radio frequency power source in a cleaning process and is grounded in an etching process.

Further, the hollow insulating ring is made of quartz material, and the bottom of the hollow insulating ring is kept in communication with the region inside the reaction chamber.

Preferably, the radio frequency coil includes an opening or a section of insulating material is disposed on the radio frequency coil.

Preferably, the radio frequency coil is connected to a lifting driving device, and the lifting driving device controls the radio frequency coil to move up and down in the hollow insulation ring.

Preferably, the lifting driving device includes at least two lifting rods and a control component connected to the lifting rods.

Preferably, a grounding structure is provided on the radio frequency coil, and the grounding structure is grounded when the position of the radio frequency coil is lowered.

Preferably, the ground structure is a concave portion or a convex portion provided on the radio frequency coil.

Preferably, a bottom wall of the reaction chamber is provided in the reaction chamber, and a convex portion or a recessed portion matching the ground structure is provided on the bottom wall of the reaction chamber corresponding to the ground structure of the radio frequency coil, and When the grounding structure is lowered, the recessed portion or the protruding portion on the radio frequency coil and the protruding portion or the recessed portion on the bottom wall of the reaction chamber are fitted to each other to realize the grounding of the radio frequency coil.

Preferably, a grounding element is provided in the hollow insulation ring, and the grounding element is adjustable in the hollow insulation ring.

Preferably, when the grounding element rises to a certain position, the grounding element is in contact with the radio frequency coil to achieve grounding of the radio frequency coil.

Preferably, the grounding element is a grounded liftable contact rod.

Further, the present invention also discloses a method for processing a substrate in a plasma processing apparatus. The method is performed in a reaction chamber. An upper electrode and a lower electrode are disposed in the reaction chamber, and a lower electrode is disposed above the lower electrode. An electrostatic chuck for supporting and fixing a substrate to be processed. The electrostatic chuck includes a hollow insulating ring, and a radio frequency coil is arranged in the hollow insulating ring. The method includes the following steps: an etching step, a substrate to be processed The wafer is moved into the reaction chamber, an etching gas is passed into the reaction chamber, at least one radio frequency power is applied to the lower electrode, and the etching gas is dissociated into an etching plasma to realize an etching process of the substrate to be processed. In the step, the RF coil is grounded; in the cleaning step, the etched substrate is removed, a cleaning gas is passed into the reaction chamber, and RF power is applied to the RF coil and the lower electrode to dissociate the cleaning gas into clean electricity. Slurry to achieve a cleaning step in the reaction chamber.

Preferably, the radio frequency coil is connected to a lifting driving device. In the etching step, the lifting driving device drives the position of the radio frequency coil to descend, and the radio frequency coil is in contact with a grounding element in the reaction chamber to achieve the Grounding of the RF coil.

Preferably, a grounding element in the reaction chamber is connected to a lifting driving device. In the etching step, the lifting driving device drives the position of the grounding element to rise, and the grounding element is in contact with the radio frequency coil to realize the Grounding of the RF coil.

Preferably, the radio frequency coil is connected with a lifting driving device. In the cleaning step, the lifting driving device drives the radio frequency coil at the top of the hollow insulation ring and the radio frequency coil is not yet connected to any of the reaction chambers. Move between the positions where the grounding element is in contact.

An advantage of the present invention is that the present invention is provided with a hollow insulation ring around the periphery of the lower electrode, and a radio frequency coil is provided in the hollow insulation ring. The edge area can be improved by applying radio frequency power to the radio frequency coil during the cleaning process. The degree of dissociation of the cleaning gas further increases the concentration of the cleaning plasma in the edge region; a high concentration of cleaning plasma is beneficial to ensure the cleaning effect of the components in the edge region. In the etching process, by setting the RF coil ground, it is possible to effectively prevent the RF power applied to the lower electrode from generating a discharge on the RF coil.

10‧‧‧ substrate

20‧‧‧ Plasma

30‧‧‧DC electrode

100‧‧‧ reaction chamber

101‧‧‧ side wall of reaction chamber

102‧‧‧ bottom wall of reaction chamber

110‧‧‧up electrode

112‧‧‧Gas supply device

120‧‧‧ lower electrode

121‧‧‧RF Power Source

122‧‧‧RF Power Source

130‧‧‧electrostatic chuck

131‧‧‧ Lifting Drive

1311‧‧‧Lift

1312‧‧‧Control

132‧‧‧ hollow insulating ring

133‧‧‧ Ground Structure

135‧‧‧RF coil

135a‧‧‧open

140‧‧‧Quartz Cover Ring

150‧‧‧Exhaust

FIG. 1 is a schematic structural diagram of a plasma processing apparatus according to the present invention.

FIG. 2 is a schematic structural diagram of a vertical section of a hollow insulating ring.

FIG. 3 is a schematic diagram of the three-dimensional structure of the radio frequency coil and its lifting driving device.

Figure 4 shows a schematic diagram of the structure of a radio frequency coil.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The technology disclosed by the present invention is applicable to a variety of plasma processing devices, and is particularly applicable to a capacitively coupled plasma processing device.

FIG. 1 is a schematic structural diagram of an ion processing apparatus to which the method according to the present invention is applied. In this embodiment, the plasma processing device is a capacitive coupling type plasma processing device, and a capacitive coupling type plasma processing device is used. The processing device includes a reaction chamber 100. The reaction chamber 100 includes a substantially cylindrical reaction chamber side wall 101 and a reaction chamber bottom wall 102 made of a metal material. The reaction chamber side wall 101 and the reaction chamber bottom wall 102 and the upper wall of the reaction chamber 100 surround The reaction chamber 100 can be evacuated. An upper electrode 110 is provided at an upper position inside the reaction chamber 100. The upper electrode 110 also serves as a gas shower head for supplying process gas into the reaction chamber 100. The gas supply device 112 borrows the process gas. The gas shower head is uniformly delivered into the reaction chamber. Corresponding to the upper electrode 110, a lower electrode 120 is provided. A radio frequency power source 121 is connected to the lower electrode 120, and when required, radio frequency power is applied to the lower electrode 120 to form a radio frequency electric field between the upper electrode 110 and the lower electrode 120. The process gas entering the reaction chamber 100 is dissociated under the action of a radio frequency electric field to form a plasma 20 for an etching process or a cleaning process. An electrostatic chuck 130 is disposed above the lower electrode 120. The electrostatic chuck is used to support and fix the substrate 10 during the etching process. Plasma 20 contains a large number of active particles such as electrons, ions, excited atoms, molecules, and free radicals. The above-mentioned active particles can undergo various physical and chemical reactions with the surface of the substrate to be treated, so that the topography of the substrate surface occurs. Change and complete the process. An exhaust device 150 is usually provided below the reaction chamber 100, for evacuating the reaction chamber 100 and discharging by-products in the process.

Before the etching process starts, the substrate 10 is first moved into the reaction chamber 100 by a robot (not shown) and placed on the electrostatic chuck. The DC electrode 30 provided inside the electrostatic chuck generates electrostatic attraction and clamps the substrate. Hold on the surface of the electrostatic chuck. After the etching process is started, the gas supply device 112 supplies the etching reaction gas into the reaction chamber 100 through the gas shower head 110, and the RF power source 121 supplies the RF power to the lower electrode 120. In specific implementation, the gas applied to the lower electrode 120 The number of radio frequency power sources 121 is greater than or equal to one, and a matching device such as a radio frequency matching network is further provided between the radio frequency power source 121 and the lower electrode 120. Since this feature does not belong to the invention point to be emphasized in the present invention, for simplicity of description, the present invention An exemplary RF power source 121 is applied to the lower electrode 120 by way of example. In this embodiment, the upper electrode 110 is grounded. When an RF power source 121 is applied to the electrode 120, a radio frequency electric field is formed between the upper electrode 110 and the lower electrode 120. The etching gas that enters the reaction chamber 100 through the upper electrode 110 dissociates in the radio frequency electric field to form an etching plasma 20. The etching plasma 20 is The process requires the etching process of the substrate 10 to be completed.

In the etching process, in addition to the etching plasma 20 acting on the substrate to complete the etching requirements, the undissociated etching gas and the etching plasma 20 not participating in the reaction will also perform deposition reactions on the exposed components and sidewalls in the reaction chamber 100 Polymer deposits are formed, and these polymers will fall off during subsequent processes to generate particulate pollutants. Therefore, a cleaning step needs to be added between the etching processes of the two substrates to ensure that the processing environment of each substrate is consistent.

The cleaning process occurs after the substrate is removed from the reaction chamber 100. At this time, the gas supply device 112 delivers the cleaning gas to the upper electrode 110, and the cleaning gas is uniformly delivered into the reaction chamber 100 via the upper electrode 110, which also serves as a gas shower head. At the same time, the RF power source 121 applies RF power that meets the requirements of the cleaning process to the lower electrode 120 to realize the step of dissociating the cleaning gas into the cleaning plasma 20. In the cleaning process, the concentration distribution of the cleaning plasma 20 is an important factor affecting the cleaning effect. In the capacitively coupled plasma processing device, the concentration distribution of the plasma 20 is such that the central region is higher than the edge region. Therefore, the cleaning effect of the central region of the reaction chamber of the capacitively coupled plasma processing device is better than that of the edge region. However, a plurality of components including a quartz covering ring 140 and a reaction chamber side wall 101 are provided in an edge region of the reaction chamber 100. If the above-mentioned components have poor cleaning effects, the cleaning effect of the overall reaction chamber 100 will be greatly reduced.

In order to adjust the concentration distribution of the cleaning plasma 20 in the reaction chamber 100 to be uniform, the present invention provides a technical means to add radio frequency electrodes in the area where the plasma plasma 20 has a low concentration, and by applying radio frequency power, the radio frequency electrodes generate additional electricity during the cleaning process. Slurry 20 to achieve a uniform distribution of the clean plasma 20.

FIG. 2 is a schematic diagram of a vertical sectional structure of a hollow insulating ring 132. In the illustrated structure, the hollow insulating ring 132 is arranged around the outer edge of the electrostatic chuck 130 and is located below the quartz cover ring 140. An opening 135a is provided at the bottom of the hollow insulation ring 132 so that the internal space of the hollow insulating ring 132 and the area inside the reaction chamber 100 are kept in communication. In this embodiment, the hollow insulating ring 132 is made of quartz material, and is obtained by cutting on a solid quartz material or by other methods. The internal space of the hollow insulating ring 132 communicates with the vacuum area in the reaction chamber 100, which can ensure that the exhaust device 150 evacuates the internal space of the hollow insulating ring 132 together when evacuating the reaction chamber 100, and avoids the inside of the hollow insulating ring 132. The gas retention causes internal discharge and damages the structure of the reaction chamber 100. A radio frequency coil 135 is provided inside the hollow insulating ring 132, and the radio frequency coil 135 is connected to the radio frequency power source 122. In the cleaning step, the radio frequency power source 121 applies radio frequency power to the lower electrode 120 to form a central region concentration and a high edge region concentration in the reaction chamber 100. Low cleaning plasma 20 is distributed. At the same time, the RF power source 122 applies RF power to the RF coil 135, and the RF coil 135 dissociates the cleaning gas above it to improve the cleaning plasma 20 in the edge area of the electrostatic chuck 130. concentration. Ensure that the concentration of the clean plasma 20 in the reaction chamber 100 is uniform. After the cleaning process is completed, the substrate 100 to be processed is moved into the reaction chamber 100 and placed above the electrostatic chuck 130. At this time, the upper electrode 110 sends an etching process gas to the electrostatic chuck 130. In order to prevent the RF coil 135 from dissociating the etching process gas, and to change the uniformity of the etching process in the reaction chamber 100, during the etching process, stop applying RF power to the RF coil 135, and further, to avoid RF applied to the lower electrode 120 The power generates a discharge on the RF coil 135, and the RF coil 135 is grounded during the etching process.

There are many ways for the RF coil 135 to be grounded. One possible implementation is to connect the RF coil 135 to the RF power source or to the ground by changing the position of the RF coil 135 in the hollow insulation ring 132. Specifically, the RF coil 135 is connected to the lifting driving device 131, and the RF driving coil 135 is driven by the lifting driving device 131 to rise or fall within the hollow insulating ring 132. During the cleaning process step, the lifting driving device 131 drives the RF coil 135 to rise in position To the position above the hollow insulating ring 132, at this time, the RF power source 122 applies RF power to the RF coil 135, so that the RF coil 135 dissociates clean gas; During the engraving process, the lifting driving device 131 drives the position of the RF coil 135 to descend. A ground structure 133 is provided on the RF coil 135. When the position of the RF coil 135 is lowered, the ground structure 133 on the RF coil 135 and a certain position in the reaction chamber 100 A grounding component contacts to ground the RF coil 135. Avoid discharging the RF coil 135 in the hollow insulation ring 132. The lifting driving device 131 includes at least one lifting rod 1311 and a control device 1312 connected to the lifting rod 1311. In order to ensure the smooth movement of the radio frequency coil 135, the lifting driving device 131 includes two or more lifting rods 1311. Since the radio frequency coil 135 cannot be a closed coil, a normal operation of the radio frequency coil 135 is achieved by providing an opening 135a in the radio frequency coil 135 or a section of insulating material at a certain position of the radio frequency coil 135. In the embodiment shown in FIG. 3, a section opening 135a is provided on the radio frequency coil 135. A lifting rod 1311 and a control device 1312 connected to the lifting rod 1311 are respectively arranged on both sides of the opening 135a, and are evenly arranged in another area of the RF coil 135 The two lifting rods 1311 and a control device 1312 connected to the lifting rods 1311 ensure smooth movement of the RF coil 135.

FIG. 4 shows a schematic structural diagram of a radio frequency coil 135. In the embodiment shown in FIG. 4, the grounding structure 133 is at least one recessed portion provided at the bottom of the radio frequency coil 135. Correspondingly, a grounding element is provided in the reaction chamber 100. A raised portion is correspondingly provided on the upper surface of the RF coil 135. When the RF coil 135 is lowered, the recessed portion of the RF coil 135 fits into contact with the raised portion of the ground element, so that the RF coil 135 is grounded. It is flexible that the grounding structure 133 of the RF coil 135 may also be provided as at least one convex portion, and a concave portion is correspondingly provided on the upper surface of the grounding element in the reaction chamber 100. When the RF coil 135 is lowered, the protrusion of the RF coil 135 is raised. The portion is in mating contact with the recessed portion of the grounding element, and the RF coil 135 is also grounded. The grounding element of the present invention can be the bottom wall 102 of the reaction chamber. Since the bottom wall 102 of the reaction chamber is always grounded, and the raised portion or the recessed portion is provided on the bottom wall 102 of the reaction chamber, the structure is simple and easy to manufacture.

In the technical means of the present invention, during the cleaning process, the position of the radio frequency coil 135 may be on the top of the hollow insulating ring 132 and between the positions which have not yet come into contact with any grounding element in the reaction chamber 100. Move down. When the RF coil 135 is located at the top of the hollow insulating ring 132, the RF coil 135 is closest to the cleaning gas in the reaction chamber 100. At this time, the area radiated by the RF coil 135 is small and the area where the cleaning gas is dissociated is also small. Therefore, The cleaning effect on the parts above the hollow insulation ring 132, such as the quartz covering ring 140, is better, while the cleaning effect on the more marginal parts, such as the side wall 101 of the reaction chamber, is slightly worse. The lifting drive device 131 is controlled to lower the position of the RF coil 135 in the hollow insulating ring 132. As the position of the RF coil 135 is lowered, the area of the area radiated by the RF coil 135 increases. Therefore, the area of the clean gas that can be dissociated increases accordingly. Cleaning of components in more marginal areas within the reaction chamber 100 is achieved. It should be noted that when raising and lowering the RF coil 135, it is necessary to prevent the RF coil 135 from being in contact with a grounded component to cause grounding of the RF coil 135.

In another embodiment, the position of the radio frequency coil 135 can also be set unchanged, and the grounding of the radio frequency coil 135 can be achieved by raising and lowering the grounded adjustable rod in the hollow insulation ring 132. For a manner of grounding the grounding element and the radio frequency coil 135 in this embodiment, reference may be made to the foregoing description.

Although the content of the present invention has been described in detail through the above-mentioned preferred embodiments, it should be recognized that the above description should not be considered as limiting the present invention. Various modifications and substitutions of the present invention will become apparent to those skilled in the art to which the present invention pertains after reading the foregoing. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (14)

A plasma processing device includes a reaction chamber. An upper electrode and a lower electrode are disposed in the reaction chamber. An electrostatic chuck for supporting and fixing a substrate is disposed above the lower electrode, and the periphery of the electrostatic chuck is arranged around A hollow insulation ring, a radio frequency coil is arranged in the hollow insulation ring, the radio frequency coil includes an opening or a section of insulating material is arranged on the radio frequency coil, the radio frequency coil communicates with a radio frequency power source in a cleaning process, and is grounded in an etching process . The plasma processing device according to item 1 of the scope of patent application, wherein the hollow insulating ring is made of quartz material, and the bottom of the hollow insulating ring is kept in communication with the area inside the reaction chamber. The plasma processing device according to item 1 of the patent application scope, wherein the radio frequency coil is connected to a lifting driving device, and the lifting driving device controls the radio frequency coil to move up and down in the hollow insulation ring. The plasma processing device according to item 3 of the patent application scope, wherein the lifting driving device includes at least two lifting rods and a control device connected to the lifting rods. The plasma processing device according to item 3 of the scope of patent application, wherein the RF coil is provided with a ground structure, and the ground structure is grounded when the RF coil position is lowered. The plasma processing device according to item 5 of the scope of patent application, wherein the ground structure is a recessed portion or a raised portion provided on the radio frequency coil. The plasma processing device according to item 6 of the scope of the patent application, wherein a bottom wall of a reaction chamber is provided in the reaction chamber, and the bottom wall of the reaction chamber is provided with the grounding structure corresponding to the grounding structure of the RF coil. When the grounding structure is lowered, the concave portion or the convex portion on the radio frequency coil and the convex portion or the concave portion on the bottom wall of the reaction chamber are fitted to each other to realize The RF coil is grounded. The plasma processing device according to item 2 of the scope of the patent application, wherein a grounding element is provided in the hollow insulation ring, and the grounding element is adjustable in the hollow insulation ring. The plasma processing device according to item 8 of the scope of the patent application, wherein the grounding element is in contact with the radio frequency coil when it is raised to a certain position, so that the radio frequency coil is grounded. The plasma processing device according to item 8 of the scope of application for a patent, wherein the grounding element is a grounding liftable contact rod. A method for processing a substrate in a plasma processing apparatus. The method is performed in a reaction chamber. An upper electrode and a lower electrode are disposed in the reaction chamber, and an electrostatic is provided above the lower electrode to support and fix a substrate to be processed. A chuck, the electrostatic chuck includes a hollow insulating ring, a radio frequency coil is arranged in the hollow insulating ring, the radio frequency coil includes an opening or a section of insulating material is arranged on the radio frequency coil, wherein the method includes the following steps: an etching step, The substrate to be processed is moved into the reaction chamber, an etching gas is passed into the reaction chamber, at least one radio frequency power is applied to the lower electrode, and the etching gas is dissociated into an etching plasma to realize the substrate to be processed. In the etching process of the wafer, in the etching step, the radio frequency coil is grounded; in the cleaning step, the etched substrate is removed, a cleaning gas is passed into the reaction chamber, and radio frequency power is applied to the radio frequency coil and the lower electrode, respectively. The cleaning gas is dissociated into a cleaning plasma to realize a cleaning step in the reaction chamber. The method according to item 11 of the scope of patent application, wherein the radio frequency coil is connected to a lifting driving device. In the etching step, the lifting driving device drives the position of the RF coil to descend, and the RF coil is grounded to the reaction chamber. The contact of the components realizes the grounding of the RF coil. The method according to item 11 of the scope of patent application, wherein a grounding element in the reaction chamber is connected to a lifting driving device, and in the etching step, the lifting driving device drives the position of the grounding element to rise, the grounding element and the radio frequency The coil contacts to ground the RF coil. The method according to item 12 of the scope of patent application, wherein the radio frequency coil is connected to a lifting driving device. In the cleaning step, the lifting driving device drives the radio frequency coil to be located on the top of the hollow insulation ring and the radio frequency coil. Move between positions that have not been in contact with any grounding element in the reaction chamber.