TWI614792B - Plasma processing device and plasma processing method - Google Patents

Abstract

The invention provides a plasma processing apparatus and method for improving the uniformity of the plasma distribution. The apparatus includes: a reaction chamber; a slide table located in the reaction chamber for placing a substrate to be processed; A plurality of inductive coupling coils for plasmatizing the gas in the reaction chamber, including first and second inductive coupling coils; a radio frequency power source; a power distributor connected between the radio frequency power source and the plurality of inductive coupling coils Between, for distributing the power of the RF power source to each inductive coupling coil, the power splitter has at least two working states:-a first state and a second state, the power of the first inductive coupling coil in the first state Less than its power in the second state, the power of the second inductive coupling coil in the first state is greater than its power in the second state; the controller is connected to the power splitter and is used to Switch control.

Description

Plasma processing device and method

The invention relates to the technical field of semiconductor manufacturing, in particular to a plasma processing device and a plasma processing method.

Plasma processing devices are widely used in the manufacturing process of integrated circuits, such as deposition, etching, etc. Among them, inductively coupled plasma (ICP) devices are one of the mainstream technologies in plasma processing devices, and their principles It mainly uses RF power to drive the inductive coupling coil to generate a strong high-frequency alternating magnetic field, so that the low-pressure reaction gas is ionized to generate plasma. The plasma contains a large number of active particles such as electrons, ions, excited atoms, molecules, and free radicals. The above-mentioned active particles can undergo a variety of physical and chemical reactions with the surface of the wafer to be processed, resulting in a change in the topography of the wafer surface. That is, the etching process is completed; in addition, the above-mentioned active ions are more active than conventional gaseous reactants, and can promote the chemical reaction between the reactive gases, that is, plasma enhanced chemical vapor deposition (PECVD) can be achieved.

FIG. 1 is a schematic cross-sectional structure diagram of an inductively coupled plasma processing device of the conventional technology, including: a reaction chamber 10; a stage 11 located in the reaction chamber 10 for carrying and fixing a wafer 14; An inductive coupling coil 12 on the top of the reaction chamber 10; a power source 13 connected to the inductive coupling coil 12 is configured to provide radio frequency power to the inductive coupling coil 12.

When the inductive coupling plasma processing device is in operation, the power source 13 can be switched between on and off, so as to provide radio frequency power to the inductive coupling coil 12 so that the inductive coupling coil 12 can Generate a magnetic field. The reaction gas input into the reaction chamber 10 is ionized by a magnetic field generated by the inductive coupling coil 12 to form a plasma. Taking the etching process as an example, when a bias voltage is applied to the wafer stage 11, the plasma is bombarded to the wafer 14 by the bias of the wafer stage 11 to perform the etching process.

However, in the conventional inductively coupled plasma processing apparatus, the plasma distribution is uneven, resulting in uneven plasma processing results.

The problem solved by the present invention is to provide a plasma processing device and a plasma processing method, so that the plasma distribution in the plasma processing device is more uniform and the effect of the plasma processing is better.

To solve the above problems, the present invention provides a plasma processing device, which includes:

Reaction chamber

A slide table located in the reaction chamber, the slide table is used to place a substrate to be processed;

A plurality of inductive coupling coils arranged concentrically on the top of the reaction chamber, the inductive coupling coils are opposite to the stage, and are used for plasmatizing the gas in the reaction chamber; It includes at least a first inductive coupling coil and a second inductive coupling coil located in the first inductive coupling coil, and the first inductive coupling coil surrounds the second inductive coupling coil;

RF power source;

A power divider is connected between the radio frequency power source and the plurality of inductive coupling coils, and is used to distribute the power of the radio frequency power source to each inductive coupling coil. The power divider has at least two working states:- The first state and the second state, the power of the first inductive coupling coil in the first state is less than that in the second state, and the power of the second inductive coupling coil in the first state is greater than the power in the second state; and

A controller is connected to the power splitter and is configured to control switching between working states of the power splitter.

Preferably, the plurality of inductive coupling coils further include a third inductive coupling coil, and the third inductive coupling coil is disposed between the first inductive coupling coil and the second inductive coupling coil.

Preferably, the structure of the inductive coupling coil is a planar spiral structure or a spiral tube structure.

Preferably, the plurality of inductive coupling coils can be moved in a vertical direction.

Preferably, the movement of each inductive coupling coil is independent of each other.

The present invention also provides a plasma processing method using the device as described above, which includes:

Setting the substrate to be processed on the surface of the stage;

Introducing gas into the reaction chamber;

Make the power splitter work in the first state for a period of time and then switch it to work in the second state, or make the power splitter work in the second state for a period of time and then switch it to work in the first state; and the power splitter The connected inductive coupling coils plasma the gas in the reaction chamber to form a plasma;

The plasma to be processed is processed using the plasma.

Preferably, the plurality of inductive coupling coils further include a third inductive coupling coil, and the third inductive coupling coil is disposed between the first inductive coupling coil and the second inductive coupling coil.

Preferably, the structure of the inductive coupling coil is a planar spiral structure or a spiral tube structure.

Preferably, the plurality of inductive coupling coils can be moved in a vertical direction.

Preferably, the movement of each inductive coupling coil is independent of each other.

As described in the background art, in the conventional inductively coupled plasma processing apparatus, the plasma is distributed unevenly, resulting in uneven plasma processing results.

After research, please continue to refer to Figure 1. Since the reaction gas input into the reaction chamber 10 is ionized by the magnetic field generated by the inductive coupling coil 12 to form a plasma, the distribution of the magnetic field generated by the inductive coupling coil 12 will affect Plasma distribution. Wherein, since the inductive coupling coil 12 is usually a spiral coil or a spiral coil, the closer it is to the center of the circle of the inductive coupling coil 12, the stronger the magnetic field intensity generated by the inductive coupling coil 12 is. . The inductive coupling coil 12 is disposed opposite to the stage 11, so that the area near the center of the inductive coupling coil 12 and the stage 11 in the reaction chamber 10 is high in plasma density and close to the stage. The plasma density in the areas around the edges of the inductive coupling coil 12 and the stage 11 is low.

In order to improve the uniformity of the plasma density distribution in the reaction chamber, the present invention provides a plasma processing device, as shown in FIG. 2, which includes a reaction chamber 10, a plurality of inductive coupling coils, a radio frequency power source, a power distributor and Controller, etc. Wherein, the reaction chamber 10 has a wafer stage 11, and a surface of the wafer stage 11 is used to place a substrate (such as a wafer) 14 to be processed. The plurality of inductive coupling coils are disposed on the top of the reaction chamber 10 and are concentrically distributed, and are opposite to the stage 11, and are used to plasmatify the gas in the reaction chamber. In this embodiment, there are two inductive coupling coils: an outer coil (first inductive coupling coil) 17 and an inner coil (second inductive coupling coil) 15. The outer coil 17 is located around the inner coil 15 and Surrounding the inner coil 15.

A radio frequency power source is used to provide radio frequency energy to the plurality of inductively coupled coils. A power divider is connected between the radio frequency power source and the plurality of inductive coupling coils, and is used to distribute the power of the radio frequency power source to each inductive coupling coil. The power divider has at least two working states-the first In one state and the second state, the power of the outer coil (first inductive coupling coil) 17 in the first state is less than that in the second state, and the power of the inner coil (second inductive coupling coil) 15 in the first state Greater than its power in the second state. A controller is connected to the power splitter and is used to control switching between working states of the power splitter.

FIG. 3 is a diagram showing the power (power distribution) of the inner coil 15 as a function of time. From 0 to T1, the power splitter is in the first state. In this state, the power of the inner coil accounts for 75% of the total power (the output power of the aforementioned RF power source), and the power of the outer coil only accounts for 25% of the total power. This makes the plasma density in the central region of the substrate to be processed significantly higher than the plasma density in the edge region of the substrate to be processed, which in turn makes the processing speed in the central region greater than the edge region. From the time T1 to the time T2, the power splitter is in the second state. In this state, the power of the inner coil accounts for 40% of the total power, and the power of the outer coil only accounts for 60% of the total power. This makes the plasma density in the central region of the substrate to be processed significantly smaller than the plasma density in the edge region of the substrate to be processed, and further makes the processing speed in the central region smaller than the edge region. The alternate execution of the first state and the second state makes the processing speed of the central region and the edge region tend to be equal.

The power allocation scheme shown in Figure 3 is just one example of the possible schemes. In other embodiments, additional power allocation methods may be adopted. For example, if the processing speed of the central area is too fast (relative to the edge area), the central area can be reduced by reducing the power (the proportion of power) of the inner coil in the first state and / or the second state. The processing speed of the central region can also be reduced by shortening the duration of the first state and / or increasing the duration of the second state. The adjustment of the processing speed of the edge area is similar to that, and will not be described again.

To explain, in addition to the two described above, the number of inductive coupling coils may be more, for example, three. Specifically, a third inductive coupling coil may be provided between the first inductive coupling coil (the outermost coil) and the second inductive coupling coil (the innermost coil). In addition, the structure of each inductive coupling coil may be a planar spiral structure or a spiral tube structure.

Not only that, each inductive coupling coil can be set to move vertically (both upward and downward). Moreover, it is preferable that the movement of each inductive coupling coil can be performed independently of each other. Since the height of the inductive coupling coil from the top of the reaction chamber also has a significant effect on the uniformity of the plasma distribution, setting each inductive coupling coil to be movable up and down will also be beneficial to the uniformity of the processing speed in each area.

The method for performing the plasma treatment of each device described above may generally include the following steps:

Setting the substrate to be processed on the surface of the stage;

Introducing gas into the reaction chamber;

Make the power splitter work in the first state for a period of time and then switch it to work in the second state, or make the power splitter work in the second state for a period of time and then switch it to work in the first state; and the power splitter The connected inductive coupling coils plasma the gas in the reaction chamber to form a plasma;

The plasma to be processed is processed using the plasma.

Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

10‧‧‧ reaction chamber
11‧‧‧ film stage
12‧‧‧ inductive coupling coil
13‧‧‧ Power
14‧‧‧ wafer
15‧‧‧Inner coil
17‧‧‧ outer coil

FIG. 1 is a schematic cross-sectional structure diagram of an inductively coupled plasma processing apparatus of the conventional technology.

FIG. 2 is a schematic cross-sectional structure diagram of an embodiment of a plasma processing apparatus according to the present invention.

Fig. 3 is a schematic diagram of the power of the inner coil over time.

10‧‧‧ reaction chamber

11‧‧‧ film stage

14‧‧‧ wafer

15‧‧‧Inner coil

17‧‧‧ outer coil

Claims (10)

A plasma processing device includes: a reaction chamber; a wafer stage located in the reaction chamber, the wafer stage is used to place a substrate to be processed; a plurality of inductive coupling coils arranged concentrically on the top of the reaction chamber Distributed, the inductive coupling coil is opposite to the stage, and is used for plasmaizing the gas in the reaction chamber, the plurality of inductive coupling coils include at least a first inductive coupling coil and are located in the first inductive coupling coil A second inductive coupling coil, the first inductive coupling coil surrounds the second inductive coupling coil; a radio frequency power source; a power splitter connected between the radio frequency power source and the plurality of inductive coupling coils, for The power of the RF power source is distributed to each of the inductive coupling coils. The power splitter has at least two working states: a first state and a second state. The power of the first inductive coupling coil in the first state is less than Its power in the second state, the power of the second inductive coupling coil in the first state is greater than its power in the second state; and a controller, and Power divider is connected, for controlling the switching between the operation state of each of the power splitter. The plasma processing device according to item 1 of the patent application scope, wherein the plurality of inductive coupling coils further include a third inductive coupling coil, the third inductive coupling coil is disposed between the first inductive coupling coil and the second inductor. Coupling between coils. The plasma processing device according to item 1 of the scope of the patent application, wherein the structure of the inductive coupling coil is a planar spiral structure or a spiral tube structure. The plasma processing apparatus according to item 1 of the scope of patent application, wherein the plurality of inductive coupling coils can be moved in a vertical direction. The plasma processing device according to item 4 of the scope of patent application, wherein the movements of the inductive coupling coils are independent of each other. A method for performing plasma processing using the device described in item 1 of the scope of patent application, comprising: setting a substrate to be processed on a surface of a stage; introducing gas into a reaction chamber; and distributing power The device works in a first state for a period of time, and then switches to a second state, or makes the power splitter work in the second state for a period of time, and then switches it to the first state to work; and the The plurality of inductive coupling coils connected to the power splitter plasma the gas in the reaction chamber to form a plasma; and use the plasma to process the substrate to be processed. The method according to item 6 of the scope of patent application, wherein the plurality of inductive coupling coils further include a third inductive coupling coil, and the third inductive coupling coil is disposed between the first inductive coupling coil and the second inductive coupling coil. between. The method according to item 6 of the scope of patent application, wherein the structure of the inductive coupling coil is a planar spiral structure or a spiral tube structure. The method according to item 6 of the patent application scope, wherein the plurality of inductive coupling coils are movable in a vertical direction. The method according to item 9 of the scope of patent application, wherein the movements of the inductive coupling coils are independent of each other.