TW201742100A - Plasma processing apparatus and method capable of increasing the dissociation degree of the cleaning gas in the edge area, thereby increasing the concentration of the cleaning plasma in the edge area - Google Patents

Abstract

The present invention provides a plasma processing apparatus and method for processing a substrate in a plasma processing apparatus. The plasma processing apparatus comprises a reaction chamber in which an upper electrode and a lower electrode are disposed. According to this invention, a hollow insulating ring is disposed around the lower electrode, and a radio frequency (RF) coil is disposed in the hollow insulating ring. By applying RF power to the radio frequency coil during the cleaning process, it can increase the dissociation degree of the cleaning gas in the edge area, thereby increasing the concentration of the cleaning plasma in the edge area. The high concentration of the cleaning plasma can ensure the cleaning effect on those components in the edge area. In the etching process, setting the RF coil to be grounded can effectively prevent the RF power applied to the lower electrode from generating discharge in the radio frequency coil.

Description

Plasma processing device and method

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

Plasma reactors are widely used in the manufacturing process of integrated circuits, such as deposition, etching, and the like. Among them, the commonly used plasma etching reaction device includes a capacitive coupling type plasma reaction device CCP and an inductive coupling type plasma device ICP. The principle of the plasma reaction device mainly uses the RF power to dissociate the reaction gas input into the reaction device into a plasma. The plasma is used to perform plasma etching treatment on the substrate placed inside the substrate. Different substrate etching processes require different reaction gases, and different reaction by-products are generated, and some reaction by-products occur between each other. The reaction, deposited on the inner sidewalls of the reaction chamber or other components, affects the subsequent reaction process.

In order to ensure the stable process environment of each substrate, after a substrate etching process is completed and removed from the reaction chamber, the inside of the reaction chamber needs to be cleaned to remove the deposition of reaction by-products in the etching process of the previous substrate. The cleaning process inside the reaction chamber is usually to pass clean gas into the reaction chamber, apply RF power to the reaction chamber, dissociate the cleaning gas into clean plasma, and clean the sidewalls and internal components in the reaction chamber with clean plasma. . In the cleaning process, the concentration distribution of the clean plasma is an important factor affecting the cleanliness of the reaction chamber. In the capacitive coupling type plasma reactor, since the cleaning plasma is generated by the electric field between the upper electrode and the lower electrode, the edge region is caused by the uneven distribution of the electric field lines between the upper electrode and the lower electrode. The generated plasma concentration is lower than the plasma concentration generated in the central region, thus resulting in poor cleaning of the components in the edge region of the reaction chamber, reducing the cleaning efficiency of the device, and it is difficult to ensure a uniform process environment for each substrate.

In order to solve the above technical problem, the present invention provides a plasma processing apparatus including a reaction chamber in which an upper electrode and a lower electrode are disposed, and an electrostatic chuck for supporting the fixed substrate is disposed above the lower electrode. A hollow insulating ring is disposed around the electrostatic chuck, and a RF coil is disposed in the hollow insulating ring. The RF coil is connected to an RF power source during the cleaning process and grounded during the etching process.

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

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

Preferably, the radio frequency coil is connected to a lifting drive device, and the lifting drive device controls the radio frequency coil to move up and down within the hollow insulating ring.

Preferably, the lifting drive comprises at least two lifting rods and a control member connected to the lifting rod.

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

Preferably, the grounding structure is a recess or a protrusion provided on the radio frequency coil.

Preferably, a bottom wall of the reaction chamber is disposed in the reaction chamber, and a protrusion or a recess corresponding to the ground structure is disposed on the bottom wall of the reaction chamber corresponding to the ground structure of the RF coil, and the ground structure is When lowered, the recessed portion or the raised portion on the radio frequency coil and the convex portion or the recessed portion on the bottom wall of the reaction chamber are mutually engaged to realize grounding of the radio frequency coil.

Preferably, a grounding element is disposed in the hollow insulating ring, and the grounding element is vertically adjustable in the hollow insulating ring.

Preferably, the grounding element is in contact with the radio frequency coil when it is raised to a certain position, and the radio frequency coil is grounded.

Preferably, the grounding element is a grounded liftable bar.

Further, the present invention also discloses a method for processing a substrate in a plasma processing apparatus, wherein 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 a substrate to be processed, the electrostatic chuck comprising a hollow insulating ring, and a radio frequency coil is disposed in the hollow insulating ring, the method comprising the following steps:

In the etching step, a substrate to be processed is moved into the reaction chamber, an etching gas is introduced into the reaction chamber, at least one RF power is applied to the lower electrode, and the etching gas is dissociated into an etching plasma to realize treatment. An etching process of the substrate, wherein the RF coil is grounded during the etching step;

a cleaning step of removing the etched substrate, introducing a cleaning gas into the reaction chamber, respectively applying RF power to the RF coil and the lower electrode, dissociating the cleaning gas into a cleaning plasma, and cleaning the reaction chamber step.

Preferably, the RF coil is connected to a lifting drive device. In the etching step, the lifting drive device drives the RF coil to be lowered, and the RF coil is in contact with a grounding component in the reaction chamber to realize the Grounding of the RF coil.

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

Preferably, the radio frequency coil is connected to a lifting drive device, in the cleaning step, the lifting drive device drives the radio frequency coil position at the top of the hollow insulating ring and the radio frequency coil has not been in any reaction chamber Move between the locations where the grounding elements touch.

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

Specific embodiments of the present invention will be described below with reference to the drawings. The technology disclosed in the present invention is applicable to a variety of plasma processing devices, and is particularly suitable for capacitively coupled plasma processing devices.

Figure 1 is a schematic view showing the structure of an ion processing apparatus to which the method of the present invention is applied. In this embodiment, the plasma processing device is a capacitive coupling type plasma processing device, and the capacitive coupling type plasma processing device includes a reaction chamber 100. The reaction chamber 100 includes a substantially cylindrical reaction chamber sidewall 101 made of a metal material and The reaction chamber bottom wall 102, the reaction chamber side wall 101 and the reaction chamber bottom wall 102 and the upper wall of the reaction chamber 100 enclose a structure of the reaction chamber 100 which can be evacuated. The upper electrode 110 is disposed at the upper position inside the reaction chamber 100, and the upper electrode 110 is simultaneously As a gas showerhead that supplies a process gas into the reaction chamber 100, the gas supply device 112 uniformly delivers the process gas into the reaction chamber by a gas showerhead. A lower electrode 120 is disposed under the upper electrode 110, and the RF power source 121 is connected to the lower electrode 120, and RF power is applied to the lower electrode 120 as needed to form a radio frequency electric field between the upper electrode 110 and the lower electrode 120. The process gas into 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 for supporting the fixed substrate 10 in an etching process. The plasma 20 contains a large number of active particles such as electrons, ions, excited atoms, molecules and radicals, and the active particles can undergo various physical and chemical reactions with the surface of the substrate to be treated, so that the surface morphology of the substrate occurs. Change and complete the process. An exhaust device 150 is generally disposed below the reaction chamber 100 for evacuating the reaction chamber 100 and discharging by-products from the process to the reaction chamber 100.

Before the etching process begins, the substrate 10 is moved into the reaction chamber 100 by a robot (not shown) and placed on the electrostatic chuck. The DC electrode 30 disposed inside the electrostatic chuck generates electrostatic attraction, and the substrate is clamped. Hold on the surface of the electrostatic chuck. After the etching process begins, the gas supply device 112 supplies an etching reaction gas to the reaction chamber 100 by the gas shower head 110. The RF power source 121 provides RF power to the lower electrode 120, and in specific implementation, is applied to the lower electrode 120. The number of the RF power sources 121 is greater than or equal to one, and a matching device such as a radio frequency matching network is further disposed between the RF power source 121 and the lower electrode 120. Since this feature is not an invention to be emphasized by the present invention, the present invention is simplified for the sake of brevity. An RF power source 121 is exemplarily applied to the lower electrode 120. In this embodiment, the upper electrode 110 is grounded. When the RF power source 121 is applied to the lower electrode 120, a radio frequency electric field is formed between the upper electrode 110 and the lower electrode 120, and the etching gas entering the reaction chamber 100 through the upper electrode 110 is in the RF electric field. The inner dissociation forms an etch plasma 20, and the etch plasma 20 completes the etching process for the substrate 10 in accordance with process requirements.

In the etching process, in addition to etching the substrate to complete the etching requirements, the undissociated etching gas and the etching plasma 20 not participating in the reaction are also deposited on the exposed parts and sidewalls in the reaction chamber 100. To form polymer deposits, these polymers will fall off during subsequent processes and produce particulate contaminants. Therefore, between the etching processes of the two substrates, a one-step cleaning step is required to ensure that the processing environment of each substrate is uniform.

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 uniformly transports the cleaning gas into the reaction chamber 100 through the upper electrode 110 which also serves as the gas shower head. At the same time, the RF power source 121 applies RF power that meets the cleaning process requirements to the lower electrode 120 to achieve 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 capacitive coupling plasma processing device, the distribution law of the plasma 20 concentration is that the central region is higher than the edge region, so the cleaning effect of the central region of the reaction cavity of the capacitive coupling plasma processing device is better than that of the edge region. However, a plurality of components including the quartz cover ring 140 and the reaction chamber side wall 101 are provided in the edge region of the reaction chamber 100. If the cleaning effect of the above components is not good, the cleaning effect of the entire reaction chamber 100 is greatly reduced.

In order to adjust the uniform concentration distribution of the cleaning plasma 20 in the reaction chamber 100, the present invention provides a technical means to increase the RF electrode in a region where the concentration of the plasma 20 is low, and the RF electrode is additionally generated in the cleaning process by applying RF power. The slurry 20 is used to achieve a uniform distribution of the cleaning plasma 20.

2 is a schematic vertical cross-sectional view of a hollow insulating ring 132. In the illustrated structure, a hollow insulating ring 132 is disposed around the outer edge of the electrostatic chuck 130, below the quartz cover ring 140, and an opening 135a is provided at the bottom thereof to make the hollow The inner space of the insulating ring 132 is in communication with the inner region of the reaction chamber 100. In this embodiment, the hollow insulating ring 132 is selected from a quartz material, which is obtained by cutting on an integral quartz material or by other means. The inner space of the hollow insulating ring 132 communicates with the vacuum area in the reaction chamber 100, so as to ensure that the exhaust device 150 vacuums the inner space of the hollow insulating ring 132 when vacuuming the reaction chamber 100, thereby avoiding the inside of the hollow insulating ring 132. Gas retention causes internal discharge, causing damage to the structure of the reaction chamber 100. A radio frequency coil 135 is disposed 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 high edge region concentration in the reaction chamber 100. The low cleaning plasma 20 is distributed at this time. 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 in the edge region of the electrostatic chuck 130. concentration. It is ensured that the concentration of the cleaning plasma 20 in the reaction chamber 100 is evenly distributed. After the cleaning process is finished, the reaction chamber 100 is moved into the substrate 10 to be processed and placed above the electrostatic chuck 130. At this time, the upper electrode 110 transports the etching process gas to above the electrostatic chuck 130. In order to prevent the RF coil 135 from dissociating the etching process gas, the uniformity of the etching process in the reaction chamber 100 is changed. In the etching process, the application of the RF power to the RF coil 135 is stopped, and further, in order to avoid the RF applied to the lower electrode 120. Power is generated on the RF coil 135, and the RF coil 135 is grounded during the etching process.

There are various 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 insulating ring 132. Specifically, the RF coil 135 is connected to the elevation driving device 131, and the RF driving coil 135 is driven to rise or fall in the hollow insulating ring 132 by the lifting driving device 131. In the cleaning process step, the lifting driving device 131 drives the RF coil 135 to rise. To a position above the hollow insulating ring 132, the RF power source 122 applies RF power to the RF coil 135, so that the RF coil 135 is dissociated from the cleaning gas; in the etching process step, the lifting drive 131 drives the RF coil 135 to drop in position. A grounding structure 133 is disposed on the RF coil 135. When the position of the RF coil 135 is lowered, the grounding structure 133 on the RF coil 135 is in contact with a grounding component in the reaction chamber 100 to ground the RF coil 135. The RF coil 135 is prevented from being discharged within the hollow insulating ring 132. The lifting drive device 131 includes at least one lifting rod 1311 and a control device 1312 connected to the lifting rod 1311. In order to ensure smooth movement of the RF coil 135, the lifting driving device 131 includes two or more lifting 1311 rods. Since the RF coil 135 cannot be a closed coil, the normal operation of the RF coil 135 is achieved by providing a section of the opening 135a on the RF coil 135 or providing a segment of insulating material at a certain position of the RF coil 135. In the embodiment shown in FIG. 3, the RF coil 135 is provided with a segment opening 135a. The two sides of the opening 135a are respectively provided with a lifting rod 1311 and a control device 1312 connected to the lifting rod 1311, and are evenly disposed in another area of the RF coil 135. Two lifting rods 1311 and a control device 1312 connected to the lifting rod 1311 ensure smooth movement of the RF coil 135.

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

In the technical means of the present invention, the position of the radio frequency coil 135 can be moved up and down at the position between the top of the hollow insulating ring 132 and the contact between any grounding elements in the reaction chamber 100 during the cleaning process. 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. The cleaning effect on the components above the hollow insulating ring 132, such as the quartz cover ring 140, is better, while the cleaning effect on the more edged components, such as the reaction chamber sidewall 101, is slightly worse. The lifting drive device 131 is controlled to lower the position of the RF coil 135 at the hollow insulating ring 132. As the position of the RF coil 135 decreases, the area of the RF coil 135 is increased, so that the area of the cleaned gas that can be dissociated increases accordingly. Cleaning of the components of the more marginal regions within the reaction chamber 100 is achieved. It should be noted that when the RF coil 135 is lifted, the contact of the RF coil 135 with the grounding component is avoided to cause the grounding of the RF coil 135.

In other embodiments, the position of the RF coil 135 can also be set to be constant, and the grounding of the RF coil 135 can be achieved by providing a grounded liftable bar in the hollow insulating ring 132. The manner in which the grounding element and the radio frequency coil 135 are grounded in this embodiment can be referred to the above description.

Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the description Various modifications and alterations of the present invention will become apparent to those skilled in the <RTIgt; Therefore, the scope of the invention should be defined by the appended claims.

10‧‧‧ substrates
20‧‧‧ Plasma
30‧‧‧DC electrode
100‧‧‧reaction chamber
101‧‧‧Reaction chamber sidewall
102‧‧‧The bottom wall of the reaction chamber
110‧‧‧Upper electrode
112‧‧‧ gas supply unit
120‧‧‧ lower electrode
121‧‧‧RF power source
122‧‧‧RF power source
130‧‧‧Electrostatic chuck
131‧‧‧ Lifting drive
1311‧‧‧ Lifting rod
1312‧‧‧Control device
132‧‧‧ hollow insulating ring
133‧‧‧ Grounding structure
135‧‧‧RF coil
135a‧‧‧ openings
140‧‧‧Quartz Covered Ring
150‧‧‧Exhaust device

Fig. 1 is a view showing the structure of a plasma processing apparatus of the present invention.

Fig. 2 is a schematic view showing a vertical sectional structure of a hollow insulating ring.

Fig. 3 is a perspective view showing the structure of the radio frequency coil and its elevation driving device.

Fig. 4 is a view showing the structure of a radio frequency coil.

10‧‧‧ substrates

20‧‧‧ Plasma

30‧‧‧DC electrode

100‧‧‧reaction chamber

101‧‧‧Reaction chamber sidewall

110‧‧‧Upper electrode

112‧‧‧ gas supply unit

120‧‧‧ lower electrode

121‧‧‧RF power source

130‧‧‧Electrostatic chuck

131‧‧‧ Lifting drive

1312‧‧‧Control device

132‧‧‧ hollow insulating ring

135‧‧‧RF coil

140‧‧‧Quartz Covered Ring

150‧‧‧Exhaust device

Claims (15)

A plasma processing apparatus comprising: a reaction chamber in which an upper electrode and a lower electrode are disposed, and an electrostatic chuck for supporting and fixing a substrate is disposed above the lower electrode, wherein the electrostatic chuck is surrounded by a setting A hollow insulating ring is disposed in the hollow insulating ring. The RF coil is connected to an RF power source during the cleaning process and grounded during the etching process. The plasma processing apparatus of claim 1, wherein the hollow insulating ring is a quartz material, and a bottom of the hollow insulating ring is in communication with an inner region of the reaction chamber. The plasma processing apparatus of claim 1, wherein the RF coil comprises an opening or an insulating material is disposed on the RF coil. The plasma processing apparatus of claim 1, wherein the RF coil is coupled to a lifting drive that controls the RF coil to move up and down within the hollow insulating ring. The plasma processing apparatus of claim 4, wherein the lifting drive comprises at least two lifting rods and a control device coupled to the lifting rod. The plasma processing apparatus of claim 4, wherein the RF coil is provided with a grounding structure, and the grounding structure is grounded when the position of the RF coil is lowered. The plasma processing apparatus of claim 6, wherein the grounding structure is a recess or a raised portion disposed on the RF coil. The plasma processing apparatus of claim 7, wherein a reaction chamber is provided with a bottom wall of the reaction chamber, and the bottom wall of the reaction chamber is disposed corresponding to the ground structure of the RF coil. The raised portion or the recessed portion, when the grounding structure is lowered, the recessed portion or the raised portion on the RF coil and the raised portion or the recessed portion on the bottom wall of the reaction chamber are mutually engaged The ground of the RF coil. The plasma processing apparatus of claim 2, wherein a grounding element is disposed in the hollow insulating ring, and the grounding element is vertically adjustable in the hollow insulating ring. The plasma processing apparatus of claim 9, wherein the grounding element is brought into contact with the radio frequency coil when the grounding element is raised to a certain position, so that the radio frequency coil is grounded. The plasma processing apparatus of claim 9, wherein the grounding element is a grounded liftable rod. A method for processing a substrate in a plasma processing apparatus, wherein the method is performed in a reaction chamber, wherein an upper electrode and a lower electrode are disposed in the reaction chamber, and an electrostatic layer is disposed above the lower electrode for supporting and fixing a substrate to be processed a chuck, the electrostatic chuck comprises a hollow insulating ring, and a radio frequency coil is disposed in the hollow insulating ring, wherein the method comprises the following steps: an etching step, moving the substrate to be processed into the reaction chamber, into the reaction chamber Passing an etching gas, applying at least one RF power to the lower electrode, dissociating the etching gas into an etching plasma, and performing an etching process on the substrate to be processed, in the etching step, the RF coil is grounded; a step of removing the etched substrate, introducing a cleaning gas into the reaction chamber, respectively applying RF power to the RF coil and the lower electrode, dissociating the cleaning gas into a cleaning plasma, and realizing the reaction chamber Cleaning steps. The method of claim 12, wherein the RF coil is connected to a lifting drive device, wherein the lifting drive device drives the RF coil to be lowered in the etching step, and the RF coil and the reaction chamber are grounded. The grounding of the RF coil is achieved by component contact. The method of claim 12, wherein a grounding component in the reaction chamber is connected to a lifting drive, and in the etching step, the lifting drive drives the grounding component to rise, the grounding component and the RF The coil is contacted to achieve grounding of the RF coil. The method of claim 13, wherein the radio frequency coil is connected to a lifting drive device, and in the cleaning step, the lifting drive device drives the radio frequency coil at a position on the top of the hollow insulating ring and the radio frequency coil It has not moved between the positions in contact with any grounding elements in the reaction chamber.