TW201724166A - Plasma processing device and plasma processing method including a reaction chamber, a substrate carrier, a plurality of inductively coupled coils, a radio frequency power source, a power distributor, and a controller - Google Patents

Abstract

The present invention provides a plasma processing device and method for improving distribution uniformity of plasma. The device includes a reaction chamber; a substrate carrier located in the reaction chamber for placing a substrate to be processed; a plurality of inductively coupled coils concentrically distributed for processing gas in the reaction chamber into plasma, and including a first inductively coupled coil and a second inductively coupled coil; a radio frequency power source; a power distributor connected between the radio frequency power source and the plurality of inductively coupled coils for distributing power of the radio frequency power source to each of the inductively coupled coils, wherein the power distributor has at least two working states, i.e., a first state and a second state, the power of the first inductively coupled coil in the first state is less than the power of the first inductively coupled coil in the second state, the power of the second inductively coupled coil in the first state is greater than the power of the second inductively coupled coil in the second state; and a controller connected to the power distributor for controlling the switch between working states of the power distributor.

Description

Plasma processing device and plasma processing method

The present invention relates to the field of semiconductor manufacturing technology, and in particular, to a plasma processing apparatus and a plasma processing method.

The plasma processing device is widely used in the manufacturing process of the integrated circuit, such as deposition, etching, etc., wherein the inductively coupled plasma (ICP) device is one of the mainstream technologies in the plasma processing device, and the principle thereof The main purpose is to use 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 radicals. The active particles can undergo various physical and chemical reactions on the surface of the wafer to be processed, and the surface morphology of the wafer changes. That is, the etching process is completed; in addition, the above-mentioned active ions have higher activity than the conventional gaseous reactants, and can promote the chemical reaction between the reaction gases, that is, plasma enhanced chemical vapor deposition (PECVD) can be realized.

1 is a cross-sectional structural view of an inductively coupled plasma processing apparatus of the prior art, comprising: a reaction chamber 10; a wafer stage 11 located in the reaction chamber 10 for carrying and fixing the wafer 14; An inductive coupling coil 12 at the top of the reaction chamber 10; a power source 13 connected to the inductive coupling coil 12 for supplying radio frequency power to the inductive coupling coil 12.

When the inductively coupled plasma processing apparatus is in operation, the power source 13 can be switched between on and off, thereby providing RF power to the inductive coupling coil 12, such that the inductive coupling coil 12 can Generate a magnetic field. The reaction gas input to the reaction chamber 10 is ionized by the magnetic field generated by the inductive coupling coil 12, and plasma can be formed. Taking an etching process as an example, in the case where a bias is applied to the stage 11, the plasma is bombarded by the wafer 14 by the bias of the stage 11 to perform an etching process.

However, in the conventional inductively coupled plasma processing apparatus, the distribution of the plasma is not uniform, resulting in uneven plasma processing results.

The problem to be solved by the present invention is to provide a plasma processing apparatus and a plasma processing method, which make the plasma distribution in the plasma processing apparatus more uniform and the plasma processing effect is better.

In order to solve the above problems, the present invention provides a plasma processing apparatus comprising:

Reaction chamber

a film stage located in the reaction chamber, the film stage for placing a substrate to be treated;

a plurality of inductive coupling coils disposed concentrically disposed at the top of the reaction chamber, the inductive coupling coil being opposite to the wafer stage for plasmaizing gas in the reaction chamber, the plurality of inductive coupling coils Include at least a first inductive coupling coil and a second inductive coupling coil located within the first inductive coupling coil, the first inductive coupling coil surrounding the second inductive coupling coil;

RF power source;

And a power splitter connected between the RF power source and the plurality of inductive coupling coils for distributing power of the RF power source to each of the inductive coupling coils, the power splitter having at least two working states: a first state and a second state, the power of the first inductively coupled coil in the first state is less than the power in the second state, and the power of the second inductively coupled coil in the first state is greater than the power in the second state;

And a controller coupled to the power splitter for controlling switching between operating states of the power splitter.

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

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

Preferably, the plurality of inductive coupling coils are movable in a vertical direction.

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

The present invention also provides a method of plasma treatment using the apparatus as described above, comprising:

Positioning the substrate to be treated on the surface of the stage;

Passing a gas into the reaction chamber;

Having the power splitter operate in the first state for a period of time, then switching it to the second state, or operating the power splitter for a period of time in the second state, and then switching it to the first state to operate; and the power splitter a plurality of connected inductive coupling coils plasma the gas in the reaction chamber to form a plasma;

The substrate to be treated is treated with the plasma.

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

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

Preferably, the plurality of inductive coupling coils are movable in a vertical direction.

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

As described in the background art, in the conventional inductively coupled plasma processing apparatus, the distribution of the plasma is not uniform, resulting in uneven plasma processing results.

After research, it is found that, referring to FIG. 1 , since the reaction gas input to 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 may affect. The distribution of plasma. Wherein, since the inductive coupling coils 12 are generally spiral coils or spiral coils, the closer to the center of the inductive coupling coil 12, the stronger the magnetic field strength generated by the inductive coupling coil 12. . The inductive coupling coil 12 is disposed opposite to the wafer stage 11, such that the plasma density in the region near the center of the inductive coupling coil 12 and the wafer stage 11 in the reaction chamber 10 is relatively high, and close to the The area of the edge of the inductive coupling coil 12 and the stage 11 is low in plasma density.

In order to improve the uniformity of the plasma density distribution in the reaction chamber, the present invention provides a plasma processing apparatus, as shown in FIG. 2, which includes a reaction chamber 10, a plurality of inductive coupling coils, a radio frequency power source, and a power divider. Controller, etc. The reaction chamber 10 has a wafer stage 11 therein, and the surface of the wafer stage 11 is used for placing a substrate (such as a wafer) 14 to be processed. The plurality of inductive coupling coils are disposed at the top of the reaction chamber 10 and are concentrically distributed, and are opposite to the wafer stage 11 for plasmaizing 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, wherein the outer coil 17 is located around the inner coil 15 and The inner ring coil 15 is surrounded.

An RF power source is used to provide RF energy to the plurality of inductively coupled coils. a power splitter connected between the RF power source and the plurality of inductive coupling coils for distributing power of a radio frequency power source to each inductive coupling coil, the power splitter having at least two operating states - In a state and a second state, the power of the outer coil (first inductive coupling coil) 17 in the first state is less than the power 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 coupled to the power splitter for controlling switching between operating states of the power splitter.

Fig. 3 is a view showing the change in power (power distribution) of the inner coil 15 with time. From 0 to time 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 above-mentioned RF power source), and the power of the outer coil only accounts for 25% of the total power. This results in a plasma density in the central region of the substrate to be treated that is significantly greater than the plasma density of the edge region of the substrate to be treated, thereby making the processing speed of 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 results in a plasma density in the central region of the substrate to be treated that is significantly less than the plasma density of the edge region of the substrate to be treated, thereby making the processing speed of the central region less than the edge region. The alternate execution of the first state and the second state causes the processing speeds of the central region and the edge region to tend to be equal.

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

To be clear, the number of inductive coupling coils may be more than two, for example, three. Specifically, a third inductive coupling coil may be disposed 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 can be either a planar spiral structure or a spiral tube structure.

Moreover, each inductive coupling coil can be arranged to move in a vertical direction (either upwards or downwards). Moreover, the movement of the respective inductive coupling coils is preferably performed independently of each other. Since the height of the inductive coupling coil from the top of the reaction chamber also has a significant influence on the uniformity of the plasma distribution, the inductive coupling coils are arranged to be movable up and down, which also contributes to the uniformity of processing speed in each region.

The method of performing plasma treatment of each of the devices described above generally includes the following steps:

Positioning the substrate to be treated on the surface of the stage;

Passing a gas into the reaction chamber;

Having the power splitter operate in the first state for a period of time, then switching it to the second state, or operating the power splitter for a period of time in the second state, and then switching it to the first state to operate; and the power splitter a plurality of connected inductive coupling coils plasma the gas in the reaction chamber to form a plasma;

The substrate to be treated is treated with the plasma.

Although the present invention has been disclosed above, the present invention is not limited thereto. Any changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be determined by the scope defined by the appended claims.

10‧‧‧Reaction chamber
11‧‧‧Sheet
12‧‧‧Inductive Coupling Coil
13‧‧‧Power supply
14‧‧‧ wafer
15‧‧‧ inner coil
17‧‧‧Outer coil

1 is a schematic cross-sectional view of an inductively coupled plasma processing apparatus of the prior art.

Fig. 2 is a schematic cross-sectional view showing an embodiment of a plasma processing apparatus of the present invention.

Figure 3 is a schematic illustration of the power of the inner coil as a function of time.

10‧‧‧Reaction chamber

11‧‧‧Sheet

14‧‧‧ wafer

15‧‧‧ inner coil

17‧‧‧Outer coil

Claims (10)

A plasma processing apparatus comprising: a reaction chamber; a wafer stage located in the reaction chamber, the wafer stage for placing a substrate to be processed; and a plurality of inductive coupling coils disposed concentrically at the top of the reaction chamber Distributing, the inductive coupling coil is opposite to the wafer stage for plasmaizing gas in the reaction chamber, the plurality of inductive coupling coils at least comprising a first inductive coupling coil, and being located in the first inductive coupling coil a second inductive coupling coil, the first inductive coupling coil enclosing the second inductive coupling coil; a radio frequency power source; a power divider connected between the RF power source and the plurality of inductive coupling coils Allocating the power of the RF power source to each of the inductive coupling coils, the power splitter having at least two operating states: a first state and a second state, the power of the first inductive coupling coil in the first state is less than The power of the second inductive coil in the first state is greater than the power in the second state; and a controller, Power divider is connected, for controlling the switching between the operation state of each of the power splitter. The plasma processing apparatus of claim 1, wherein the plurality of inductive coupling coils further comprise a third inductive coupling coil, wherein the third inductive coupling coil is disposed in the first inductive coupling coil and the second inductor Coupling between the coils. The plasma processing apparatus of claim 1, wherein the inductive coupling coil has a planar spiral structure or a spiral tube structure. The plasma processing apparatus of claim 1, wherein the plurality of inductive coupling coils are movable in a vertical direction. The plasma processing apparatus of claim 4, wherein the movement of each of the inductive coupling coils is independent of each other. A method for plasma treatment using the apparatus of claim 1, comprising: placing a substrate to be treated on a surface of a substrate; introducing a gas into a reaction chamber; and distributing a power Operating in a first state for a period of time, then switching it to a second state of operation, or causing the power splitter to operate in the second state for a period of time, and then switching it to the first state to operate; A plurality of inductive coupling coils connected to the power divider plasma the gas in the reaction chamber to form a plasma; and the substrate to be treated is processed by the plasma. The method of claim 6, wherein the plurality of inductive coupling coils further comprise a third inductive coupling coil disposed in the first inductive coupling coil and the second inductive coupling coil between. The method of claim 6, wherein the inductive coupling coil has a planar spiral structure or a spiral tube structure. The method of claim 6, wherein the plurality of inductive coupling coils are movable in a vertical direction. The method of claim 9, wherein the movement of each of the inductive coupling coils is independent of each other.