KR101297711B1

KR101297711B1 - Plasma processing apparatus and plasma processing method

Info

Publication number: KR101297711B1
Application number: KR1020070013900A
Authority: KR
Inventors: 황태형; 장홍영
Original assignee: 한국과학기술원; 삼성디스플레이 주식회사
Priority date: 2007-02-09
Filing date: 2007-02-09
Publication date: 2013-08-20
Also published as: CN101267708A; TW200850078A; KR20080074587A; JP2008198601A; CN101267708B; TWI452945B; JP5465835B2

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus and a processing method, and more particularly, to a plasma processing apparatus and a processing method capable of generating a uniform plasma and uniformly processing a large area substrate.

The plasma processing apparatus according to the present invention includes a vacuum chamber, a lower electrode disposed inside the vacuum chamber, a lower electrode formed of a plurality of blocks, an upper electrode disposed above the inside of the vacuum chamber, grounded, and a process gas inside the vacuum chamber. Process gas supply unit for supplying the source, source power supply unit connected to the lower electrode to apply a source power (source power), individually connected to each block of the lower electrode to apply a bias power (bias power) to each block independently And a control unit for calculating a bias power to be applied to each block of the lower electrode and controlling the bias power supply unit.

Description

Plasma processing apparatus and plasma processing method {PLASMA PROCESSING APPARATUS AND PLASMA PROCESSING METHOD}

1 is a longitudinal sectional view showing a structure of a plasma processing apparatus according to an embodiment of the present invention.

2 is a cross-sectional view showing the structure of a plasma processing apparatus according to an embodiment of the present invention.

3 is a partial perspective view illustrating a structure of a lower electrode according to an exemplary embodiment of the present invention.

4A is a graph illustrating plasma density values for respective blocks measured by the plasma tomography unit according to an exemplary embodiment of the present invention.

4B is a graph showing correction values for respective blocks according to an embodiment of the present invention.

4C is a graph illustrating a bias power value for each block according to an embodiment of the present invention.

5 is a block diagram illustrating each process in the plasma processing method according to an embodiment of the present invention.

Description of the Related Art

1: plasma processing apparatus according to an embodiment of the present invention

10 vacuum chamber 20 upper electrode

30: lower electrode 40: process gas supply unit

50: source power supply 60: bias power supply

70: plasma tomography unit 80: control unit

90: electrostatic chuck S: substrate

BACKGROUND OF THE INVENTION Many plasma processing apparatuses for treating a surface of a substrate using plasma have been used in manufacturing processes such as semiconductor devices and liquid crystal display devices. Examples of such a plasma processing apparatus include a plasma etching apparatus for etching a substrate, a plasma CVD apparatus for performing chemical vapor deposition (CVD), and the like.

This plasma processing apparatus includes two flat plate electrodes facing each other in parallel up and down. Plasma is generated in a state where the substrate is mounted between the electrodes, and the substrate is subjected to a constant treatment.

However, as the size of the substrate to be processed in the plasma processing apparatus increases, it becomes difficult to obtain a uniform plasma for all parts of the substrate to be processed. In particular, when the size of the substrate to be processed exceeds 2, 3m, such as a liquid crystal display device, there is a problem that it is difficult to secure the process conditions due to the uneven plasma density varies depending on each part of the substrate.

The technical problem to be achieved by the present invention is to provide a plasma processing apparatus and a plasma processing method capable of forming a uniform plasma by reflecting the plasma density of each zone in real time.

In accordance with another aspect of the present invention, a plasma processing apparatus includes a vacuum chamber, a lower electrode disposed inside the vacuum chamber, a lower electrode formed of a plurality of blocks, and an upper electrode disposed above the vacuum chamber and grounded. A process gas supply unit supplying a process gas into the vacuum chamber, a source power supply unit connected to the lower electrode to apply a source power, and individually connected to each block of the lower electrode independently of each block And a control unit for calculating a bias power to be applied to each block of the lower electrode and controlling the bias power supply.

Further, it is preferable to further include an insulator disposed between each block of the lower electrode and to insulate each block, so that the source power or the bias power can be differently applied to each block.

It is preferable that the insulator has a double stepped structure, and each block in contact with the insulator has a stepped structure, since it can prevent the penetration of plasma.

In addition, the insulator is preferably made of ceramic or alumina (Al ₂ O ₃ ) because it is resistant to plasma and does not generate particles.

In addition, an electrostatic chuck may be further provided on the upper portion of the block, since it is possible to stably fix the substrate during the process to ensure uniformity of the process.

Meanwhile, the insulator may further include a cooling gas passage passage for cooling the electrostatic chuck.

In addition, it is preferable to further include a plasma tomography unit for tomography the plasma density for each zone in which the space between the upper electrode and the lower electrode is virtually divided, and to provide the control unit with data on the plasma density of each zone photographed.

The tomography unit may include a plurality of first photographing means for photographing a space between the upper electrode and the lower electrode in one direction parallel to the upper surface of the lower electrode, and a plurality of second photographing means for photographing a different direction from the first photographing means. It is preferable to include a photographing means.

In addition, the control unit may include any one of a PID feedback scheme, a neutral network, or a fuzzy control system to calculate a bias power value reflecting plasma density for each column in real time.

On the other hand, the plasma processing method according to the present invention for achieving the above technical problem, the step of bringing the substrate into the vacuum chamber; Forming a plasma inside the vacuum chamber; Photographing the plasma density for each zone in the vacuum chamber; Calculating bias power for each zone in consideration of the photographed plasma density; Applying the calculated bias power for each zone; And removing the substrate to the outside of the vacuum chamber.

The photographing of the plasma density may include photographing the plasma density of one zone in two or more different directions, and combining them to calculate the plasma density for each column.

In the calculating of the bias power, a PID feedback scheme is used, wherein the PID feedback scheme uses the plasma density of each zone photographed as an input variable, and the bias power for each zone is an output variable. .

Hereinafter, a specific embodiment of the present invention will be described in detail with reference to the accompanying drawings. By the present embodiment will be more clearly understood the problem and configuration of the present invention.

First, a plasma processing apparatus according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 3. 1 is a longitudinal cross-sectional view showing the structure of a plasma processing apparatus according to an embodiment of the present invention, Figure 2 is a cross-sectional view showing the structure of a plasma processing apparatus according to an embodiment of the present invention. 3 is a partial perspective view illustrating a structure of a lower electrode according to an exemplary embodiment of the present invention.

As shown in FIGS. 1 and 2, the plasma processing apparatus 1 according to the present embodiment includes a vacuum chamber 10, an upper electrode 20, a lower electrode 30, a process gas supply unit 40, and a source power supply unit. 50, a bias power supply unit 60, a plasma tomography unit 70, and a control unit 80.

First, the vacuum chamber 10 has a constant volume therein, and has a sealed structure to make the internal space into a vacuum state. Here, the vacuum state refers to an air pressure state lower than an atmospheric pressure state, and does not mean a complete vacuum state.

The vacuum chamber 10 generally has a shape similar to that of a substrate to be processed, and a rectangular parallelepiped vacuum chamber is used in a plasma processing apparatus that processes a rectangular substrate such as a liquid crystal display substrate.

On the other hand, as the size of the substrate to be processed has recently increased, the size of the vacuum chamber has also increased dramatically. Therefore, one vacuum chamber is not made integrally, but is manufactured by being separated into various pieces and then assembled and used as one.

In addition, the vacuum chamber 10 is provided with an exhaust pump (not shown) for discharging the gas inside the chamber to lower the pressure in the chamber. This exhaust pump has a larger capacity as the pressure inside the chamber is lower or the volume inside the vacuum chamber is larger. As such an exhaust pump, a TMP pump, cryopump, or the like may be used. In addition, one such exhaust pump may be installed in one vacuum chamber, and a plurality of exhaust pumps may be provided in one vacuum chamber.

In addition, the vacuum chamber 10 may further include a venting pump (not shown) for injecting nitrogen gas or an inert gas into the chamber to increase the pressure in the chamber. The process of carrying in and out of the substrate is repeated in the vacuum chamber 10. In the process of carrying out the substrate, the pressure inside the chamber should be the same as the outside pressure, so a bending operation is required to increase the pressure inside the chamber in a vacuum state.

And one sidewall of the vacuum chamber 10 is formed with a substrate entrance 12 that uses the substrate as a passage for carrying in and out. The substrate entrance 12 is preferably formed as small as possible for pressure management inside the vacuum chamber 10. Therefore, it is sufficient that the substrate entrance 12 has a size that allows the substrate S to be processed in the vacuum chamber 10 to pass through.

In front of the substrate entrance and exit 12, an opening and closing means 14 for opening and closing the substrate entrance and exit is provided. The opening and closing means 14 opens the substrate entrance and exit 12 in the process of carrying out the substrate, and closes the substrate entrance and exit 12 in the plasma processing of the substrate. In order to easily form a vacuum inside the vacuum chamber 10, the opening and closing means 14 should be in close contact with the chamber outer wall. Therefore, a sealing means (not shown in the figure) may be further provided on the inner wall of the opening and closing means 14 to maintain the airtight near the substrate entrance and exit 12.

Next, two electrodes of the upper electrode 20 and the lower electrode 30 are provided in the vacuum chamber 10 to form an electric field for plasma formation. First, as shown in FIG. 1, the upper electrode 20 is disposed above the inside of the vacuum chamber 10. In this embodiment, this upper electrode 20 is grounded.

The lower electrode 30 is disposed below the vacuum chamber 10. As shown in FIG. 1, since the substrate S is mounted on the upper surface of the lower electrode 30, the lower electrode 30 may also be referred to as a substrate mounting table.

Source power for forming an electric field is applied to the lower electrode 30. Radio frequency power (RF) may be used as the source power, and the frequency thereof is preferably about 13.56 MHz.

In the present embodiment, the lower electrode 30 has a structure in which several blocks 32 are assembled as shown in FIG. 2. In addition to the source power described above, the bias power is applied to the lower electrode 30 according to the present embodiment. In this case, a different bias voltage may be applied to the lower electrode 32 according to the present exemplary embodiment. Therefore, each block 32 of the lower electrode is assembled insulated from each other.

The number of blocks 32 constituting the lower electrode 30 may be configured in various ways and preferably coincides with the number of liquid crystal display substrates obtained by chamfering the substrate S processed by the plasma processing apparatus. That is, in the case where the 16 chamfered substrates obtain 16 liquid crystal display substrates from the substrate processed by the plasma processing apparatus, the lower electrode 30 is preferably composed of 16 blocks 32, as shown in FIG.

An insulator 34 is further provided between the blocks 32 of the lower electrode to insulate the blocks from each other. Since the insulator 34 must withstand the plasma environment inside the vacuum chamber 10, the insulator 34 is preferably made of a plasma resistant material. Therefore, in this embodiment, the insulator 34 can be made of ceramic or alumina. Meanwhile, the insulator may be made of heat resistant plastic.

And each block 32 of the lower electrode is assembled with a stepped shape, as shown in FIG. Therefore, the insulator 34 disposed between each block 32 has a double stepped structure. The double stepped structure refers to a structure in which the stepped shape is overlapped as shown in FIG. 3. In this way, if each block 32 of the lower electrode has a stepped shape, it is possible to prevent plasma from penetrating into the seam of the block 32. When the plasma penetrates into the seam of the block, the inside of the block is etched or damaged, and there are problems such as generation of particles. However, since the plasma has a straightness, as described above, when the stepped structure is introduced at the seam of the block 32, the path through which the plasma passes changes to the stepped path. Therefore, the plasma having straightness cannot easily penetrate into the seam of the block 32.

After all, by introducing such a stepped structure, although the lower electrode 30 according to the present embodiment is not an integral structure, there is an advantage that the plasma does not penetrate the inside.

An electrostatic chuck 90 may be further provided on the lower electrode 30 according to the present embodiment. The electrostatic chuck 90 is a component that absorbs the substrate S by using electrostatic force. That is, by applying a high voltage DC voltage to the electrostatic chuck 90, a large coulomb force is generated between the substrate S and the electrostatic chuck 90 to fix the substrate S to the electrostatic chuck 90. will be. Using the electrostatic chuck 90 as described above has the advantage of being able to closely adhere the substrate S to the lower electrode during the plasma treatment process.

When the substrate S is not in close contact with the lower electrode 30 during the plasma treatment process, a portion of the substrate may be spaced apart from the lower electrode. When a portion of the substrate S is spaced apart from the lower electrode 30, the gap between the substrate S and the upper electrode 20 is not kept constant, which makes it impossible to uniformly process the substrate.

On the other hand, when the electrostatic chuck 90 is disposed above the lower electrode 30, a cooling gas must be passed through the electrostatic chuck to be cooled. However, since each block 32 constituting the lower electrode 30 is made of a metal such as aluminum, it is difficult to form a flow path for allowing the cooling gas to pass therethrough. However, since the insulator 34 is not made of metal, it is easy to form a flow path for passing the cooling gas. Therefore, in the present embodiment, as shown in FIG. 3, the cooling gas flow path 36 is formed in the insulator 34.

In addition, the plasma processing apparatus 1 may be provided with an internal elevating pin (not shown) and an external elevating bar (not shown) to assist a process of carrying in or carrying out a substrate into the processing apparatus. At this time, the internal elevating pin is formed through the edge of the lower electrode 30, and is driven up and down through the through hole formed in the lower electrode 30.

The external elevating bar is separately provided outside the lower electrode 30. That is, it is provided in a space formed between the sidewall of the lower electrode 30 and the sidewall of the plasma processing apparatus, and has a structure capable of driving up and down. Of course, in some cases, the board | substrate S can also be conveyed without using an external lifting bar.

Next, the process gas supply unit 40 is a component for supplying a process gas for plasma formation into the vacuum chamber 10. In this embodiment, this process gas supply part 40 is comprised by the shower head. That is, as shown in FIG. 1, the showerhead 40 having a size corresponding to the size of the front surface of the substrate is configured to uniformly supply the process gas to the entire surface of the substrate S mounted on the lower electrode 30. . In the present embodiment, the shower head 40 is provided in the upper electrode 20 and is composed of multiple diffusion plates 42 and 44 and diffusion holes 46 and 48. The process gas supplied to the one point in the vacuum chamber 10 by the process gas supply pipe 41 is uniformly diffused by the diffusion plates 42 and 44 and the diffusion holes 46 and 48. Therefore, a process gas having a uniform density is supplied between the upper electrode 20 and the lower electrode 30. Process gas supplied with such a uniform density is essential to form a uniform plasma.

Next, the source power supply unit 50 is connected to the lower electrode 30 to apply source power to the lower electrode 30. As source power, RF power (Radio Frequency Power) is used as described above, so that the source power supply unit 50 supplies the RF power having a specific frequency to the lower electrode 30. This source power may be supplied differently for each block 32 constituting the lower electrode, but may be supplied to all blocks 32 at the same value.

The source power supplied by the source power supply unit 50 is coupled to the ground voltage of the upper electrode 20 to form an electric field between the upper electrode 20 and the lower electrode 30. The process gas supplied from the shower head 40 is ionized by this electric field to form plasma.

Next, the bias purge supply unit 60 is individually connected to each block 32 of the lower electrode 30 to apply bias power to each block 32 independently. In this embodiment, the bias power is applied to each block 32 independently. That is, a bias value of a different value is supplied to each block 32. Accordingly, the bias power supply unit 60 is separately connected to each block 32 constituting the lower electrode.

The bias power supplied by this bias power supply unit 60 directs the plasma generated in the space between the upper electrode 20 and the lower electrode 30 to increase the plasma processing efficiency. That is, the plasma is attracted toward the lower electrode 30 on which the substrate is mounted to increase the processing speed by the plasma. The larger the bias power, the larger the processing speed by the plasma, and the smaller the bias power, the smaller the processing speed by the plasma.

In this embodiment, RF power is used as this bias power. However, the frequency of this bias power is different from the frequency of the source power mentioned above.

Next, the plasma tomography unit 70 tomograms the plasma density for each region in which the space between the upper electrode 20 and the lower electrode 30 is virtually divided. The plasma tomography unit 70 is for accurately measuring the characteristics of the plasma generated between the upper electrode 20 and the lower electrode 30 for each zone.

As described above, as the size of the substrate S processed by the plasma processing apparatus 1 increases, the vacuum chamber 10, the lower electrode 20, and the upper electrode 30 are expanded. Therefore, the area where plasma is generated is also expanding. Plasma generated in a narrow area can be said to have a uniform density as a whole, but plasma generated in a wide area has a different density for each area due to various factors such as the difference in density of the process gas, the difference in speed of movement of the process gas, the potential difference, and the temperature difference. Will have

The density difference for each region of the plasma generated as described above causes a difference in the degree of processing of the substrate and serves as a cause for which a uniform process result cannot be obtained. Therefore, it is very important to ensure uniformity of the process by measuring the accurate plasma density in each zone and reflecting it in real time to obtain a uniform plasma.

The plasma tomography unit 70 according to the present exemplary embodiment includes a first photographing means 72 and a second photographing means 74, as shown in FIG. 2, in order to measure an accurate plasma density for each zone. The first photographing means 72 photographs the space between the upper electrode 20 and the lower electrode 30 in one direction parallel to the upper surface of the lower electrode 30, and the second photographing means 74 includes the The space between the upper electrode and the lower electrode is photographed in a direction parallel to the upper surface of the lower electrode, but is photographed in a direction different from the photographing direction of the first photographing means 72.

Here, the first photographing means 72 and the second photographing means 74 are each provided in plural. In this case, the number of the first photographing means 72 and the second photographing means 74 provided is sufficient to form at least one photographing line for each block 32 of the lower electrode, as shown in FIG. 2. It should be provided in number.

Thus, the plasma density of each zone can be known by combining the data photographed in different directions. For example, as shown in FIG. 2, the first photographing means 72 photographs in a direction perpendicular to the long side of the lower electrode 30, and the second photographing means 74 is located at the short side of the lower electrode 30. Shoot in the vertical direction. Since the data photographed in two directions is collected about the part where the photographing line 76 of the first photographing means 72 and the photographing line 78 of the second photographing means 74 intersect, these two data are combined. The plasma density at the intersection region of the imaging line can be known.

Next, the controller 80 calculates a bias power to be applied to each block 32 based on the data on the plasma density for each region obtained by the plasma tomography unit 70 and controls the bias power supply unit 60. . That is, the controller 80 calculates a bias power value to be supplied for each zone as an output value using data on the plasma density for each zone as an input value. The bias power supply unit 60 is controlled to supply the calculated bias power value for each block 32.

In particular, the control unit 80 should calculate the bias power value by reflecting the data on the plasma density for each area obtained by the plasma tomography unit 70 in real time. Therefore, in the present embodiment, the control unit 80 may include any one of a PID feedback scheme, a neutral network, or a fuzzy control system.

For example, when the controller 80 has a PID feedback scheme, the data on the plasma density for each zone obtained by the plasma tomography unit 70 is used as an input variable, and the bias power value for each zone is an output variable. To operate the system.

Hereinafter, a plasma processing method according to an embodiment of the present invention will be described with reference to FIG. 5. 5 is a block diagram illustrating each process of the plasma processing method according to an embodiment of the present invention.

First, the substrate S to be processed is loaded into the vacuum chamber 10 (S 10). Since the substrate has a very thin thickness and a large area, a certain portion of the substrate sags downward in the transportation process. Therefore, after a part of the substrate is supported by the robot or the like so as not to sag downward, the vacuum chamber 10 enters into the vacuum chamber 10 and is mounted on the lower electrode 30.

In this case, the substrate S may be brought into close contact with the lower electrode 30 using the electrostatic chuck 90. When the electrostatic chuck 90 is used as described above, the substrate S is in close contact with the electrostatic chuck while the substrate S is completely seated on the upper portion of the electrostatic chuck 90.

Next, plasma is formed in the vacuum chamber 10 (S 20). Specifically, the source gas is applied to the lower electrode 30 while the process gas is supplied into the vacuum chamber 10 using the shower head 40 to ionize the process gas and generate a plasma.

Next, the plasma density is photographed for each zone in the vacuum chamber 10 (S 30). At this time, it is preferable that each zone for photographing the plasma density coincides with each block 32 of the lower electrode 30. In the step of photographing the plasma density, it is preferable to photograph the plasma density of one zone in two or more different directions to obtain an accurate plasma density of the specific zone.

For example, the plasma density value D for each zone measured in this step can be shown, as shown in FIG. 4A. That is, each zone has a different value.

Next, the bias power for each zone is calculated in consideration of the photographed plasma density (S40). That is, the bias power value B to be applied for each block is calculated based on the plasma density value D for each zone obtained in the previous step.

For example, as shown in FIG. 4B, a correction value C having a constant size is required to have the same plasma density in each zone. The correction value C is calculated, and the corresponding bias power value B is calculated to cover the correction value for each zone. The calculated bias power value B for each zone has a size opposite to the plasma density value for each zone, as shown in FIG. 4C. That is, the bias power value B is small in the region where the plasma density value D is large, and the bias power value B is large in the region where the plasma density value D is small.

Next, the calculated bias power value B is supplied to each block 32 to form a uniform plasma (S 50).

Then, the substrate is processed using the uniform plasma thus formed (S 60). In the process of processing the substrate, photographing is continuously performed on the plasma density of each zone. When a difference occurs in the plasma density, the bias power value is changed to secure the plasma uniformity in real time.

Next, the processed substrate S is carried out (S 70). When the substrate is in close contact with the lower electrode using the electrostatic chuck 90, the DC power applied to the electrostatic chuck is first cut off to remove the electrostatic power, and then the substrate is taken out. If the substrate is taken out before the electrostatic force is completely removed, there is a risk of breaking the substrate.

According to the present invention, it is possible to form a uniform plasma by applying a different bias power value for each block of the lower electrode by reflecting the plasma density value measured for each zone in real time using a tomography technique.

Claims

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A vacuum chamber;

A lower electrode disposed under the vacuum chamber and formed of a plurality of blocks;

An insulator disposed between each block of the lower electrode and insulating the blocks;

An upper electrode disposed above the vacuum chamber and grounded;

A process gas supply unit supplying a process gas into the vacuum chamber;

A source power supply connected to the lower electrode to apply source power;

A bias power supply unit connected to the respective blocks of the lower electrode to apply a bias power to each of the blocks independently; And

A control unit for calculating a bias power to be applied to each of the blocks of the lower electrode and controlling the bias power supply unit,

Wherein each block has a stepped shape at the seam of the blocks, and the insulator has a double stepped structure between the blocks to block the plasma from penetrating into the seam.

The method of claim 3,

The insulator is a plasma processing apparatus, characterized in that made of ceramic.

The method of claim 3,

And the insulator is made of alumina.

The method of claim 3,

The insulator is a plasma processing apparatus, characterized in that made of a heat-resistant plastic.

The method of claim 3,

And an electrostatic chuck further provided on the block.

The method of claim 7, wherein

The insulator further comprises a cooling gas passage passage for cooling the electrostatic chuck.

The method of claim 3,

And a plasma tomography unit for capturing the plasma density for each zone in which the space between the upper electrode and the lower electrode is virtually divided, and providing the control unit with data on the plasma density for each zone. Processing unit.

10. The method of claim 9,

The tomography unit,

A plurality of first photographing means for photographing a space between the upper electrode and the lower electrode in one direction parallel to the upper surface of the lower electrode;

And a plurality of second photographing means for photographing in a direction different from the first photographing means.

The method of claim 3,

The control unit includes a PID feedback scheme, a neutral network system or a fuzzy control system any one of the plasma processing apparatus.

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Bringing the substrate into the vacuum chamber;

Forming a plasma inside the vacuum chamber;

Photographing the plasma density for each zone in the vacuum chamber;

Calculating bias power for each zone in consideration of the photographed plasma density;

Applying the calculated bias power to each block of the lower electrode consisting of blocks one-to-one corresponding to each zone; And

Taking the substrate out of the vacuum chamber;

Photographing the plasma density,

Plasma processing method characterized in that the imaging of the plasma density of one zone in each of two or more different directions.

14. The method of claim 13,

The step of calculating the bias power,

Plasma processing method characterized by using a PID feedback scheme.

The method of claim 14,

The PID feedback scheme uses plasma density of each zone photographed as an input variable and bias power of each zone as an output variable.

14. The method of claim 13,

Importing the substrate,

And adhering the substrate to the lower electrode.

17. The method of claim 16,

In the step of adhering the substrate to the lower electrode,

And the substrate is in close contact with the lower electrode using electrostatic power.