JPH06216047A - Microwave plasma cvd film formation and device therefor - Google Patents

Abstract

PURPOSE:To provide a microwave plasma CVD film forming method and a device, wherein a film can be formed high in efficiency through a CVD method, and a sputtering etching plasma process can be efficiently carried out. CONSTITUTION:A plasma CVD forming device is equipped with a plasma generating chamber 2 and a processing chamber 4, microwave power introducing means 5, 6, and 8 and a magnetic field applying means 10 are provided inside the plasma generating chamber 2 where a plasma material gas inlet system 20 is connected, a chemical reaction material gas inlet system 22 is connected to the processing chamber 4, and an RF power inlet 18 is connected to a specimen pad 14. A control device 27 is provided to modulate electric powers for the microwave power generating source 8 and an RF power generating source 18. An RF power and a microwave power are modulated synchronizing with each other, and a condition that the formation of a film has priority and another condition that sputtering etching has priority are alternately repeated to form a CVD film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave in which a raw material in a gas state is introduced and various materials are deposited by utilizing the action of plasma to form a thin film in the production of a semiconductor electronic device or the like. The present invention relates to a plasma CVD film forming method and apparatus.

[0002]

2. Description of the Related Art Electron cyclotron resonance (hereinafter referred to as E
A thin film forming method using plasma (abbreviated as CR) can form a high quality thin film at room temperature and is already well-established as a method excellent in fine processing. In particular, by applying RF power to the substrate material as the sample, the film quality of the thin film can be further improved, the step coverage for performing multi-layer wiring can be improved, and further, the insulating film is formed. At the same time, it has been noted that the thin film can be planarized by simultaneously performing etching. EC like this
A microwave plasma CVD film forming method for forming a thin film by plasma using R is ECR plasma CVD
It is called a film forming method.

By the way, in recent years, with the high integration of VLSIs, it has become essential to miniaturize the wiring pattern and to make the wiring multi-layered. For this reason, the technique of flattening the interlayer insulating film between the wirings is important. Has been done. Usually, when a silicon oxide insulating film is formed on a substrate having an uneven pattern, the insulating film surface reflects the unevenness of the underlying pattern as it is. If wiring is formed again on it, cracks etc. may occur and cause disconnection,
The focus position (depth) of pattern exposure changes, which makes lithography difficult.

As a method for flattening this concavo-convex structure, when forming a thin film, argon gas is added to oxygen gas as a plasma source gas, monosilane gas is introduced as a chemical reaction material, and RF power is further applied to the sample substrate. An additive bias ECR plasma CVD method has been proposed.

This bias ECR plasma CVD method is
It utilizes the fact that deposition of an insulating film and sputter etching due to argon ions occur simultaneously by adding argon gas and applying RF power to the sample substrate. In the flat pattern portion, the deposition rate is higher than the sputter etching rate. The film formation progresses about 4 times, while the sputter etching rate is about 1.6 at the side sloped part of the pattern.
The feature is that the inclined side wall recedes without forming a film, and as a result, the insulating film can be flattened and embedded in one process.

[0006]

By the way, the bias E
In the CR plasma CVD method, it is generally known that increasing the microwave power amount improves the film formation rate, and increasing the RF power amount improves the sputter etching rate. Further, it is appropriate to introduce oxygen gas as a plasma raw material and silane (SiH4) gas as a chemically reactive material during film formation, and to introduce only argon gas as a plasma raw material during sputter etching.

However, in the conventional bias ECR plasma CVD method, microwave power, RF power, plasma raw material gas type and flow rate, chemical reaction material gas type and flow rate are fixed and used during flattening thin film formation. Under these conditions, the film formation rate and the sputter etching rate are canceled out, and as a result, the planarization thin film formation rate is reduced.

If the flattening thin film forming rate is reduced, the number of sample substrates (throughput) on which the microwave plasma CVD film forming apparatus forms a CVD film per unit time is reduced, and the microwave plasma CVD is performed. This is a factor that reduces the economic value of the film forming apparatus.

[0009]

The present invention has been made in view of the problems as described above, and a microwave plasma CVD film forming method capable of efficiently performing CVD film formation and sputter etching plasma treatment. And to provide a device.

A microwave plasma CVD film forming method of the present invention which achieves the above object comprises a plasma generation chamber and a processing chamber provided with a sample stage for placing a sample, and in the plasma generation chamber, a plasma raw material, A plasma is formed by the interaction between the microwave power and the magnetic field, and the plasma drawn out from the plasma generation chamber is used. A chemically reactive material is supplied to the processing chamber, and RF power is applied to the sample. A microwave plasma CVD film forming method for promoting thin film formation by promoting physical and chemical reactions that occur near the surface is characterized in that the RF power and the microwave power are modulated in synchronization with each other.

The RF power and the microwave power have a modulation waveform of, for example, a rectangular wave, but may have a sine waveform or a composite waveform of a plurality of sine waves.

Further, the supply amounts and types of the plasma raw material and the chemically reactive material may be changed in synchronization with the modulation of the RF power and the microwave power.

On the other hand, the microwave plasma CVD of the present invention
The film forming apparatus includes a plasma generation chamber and a processing chamber provided with a sample table on which a sample is placed. In the plasma generation chamber, a microwave power introduction unit and a magnetic field application unit are installed, and a plasma source gas. In the microwave plasma CVD film forming apparatus, an introduction system is connected, a chemical reaction material gas introduction system is connected to the processing chamber, and RF power introduction means is connected to the sample stage. The microwave power generation source and the RF power generation source are characterized in that a control device for modulating each power is installed.

It is also possible to add a control valve to the plasma raw material introduction system and the chemically reactive material gas introduction system, which is provided with a control valve for switching the introduction and interruption of gas and for changing the flow rate and controlling the control valve by the control device. it can.

[0015]

In the present invention, the RF power applied to the sample on which the CVD film is formed is modulated, and the microwave power is modulated in synchronization with the modulation of the RF power.

By this method, the RF power amount is periodically changed (modulated) to reduce the microwave power amount when the RF power amount is large, and conversely, when the RF power amount is small. It is possible to set to increase the amount. As a result, it becomes possible to alternately increase the sputter etching rate and the film forming rate, and it becomes possible to efficiently proceed each physical or chemical reaction independently.

[0017]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 shows a cross-sectional view of an apparatus embodying the present invention. This ECR plasma CVD film forming apparatus includes a plasma generation chamber 2 and a processing chamber 4. A microwave generation source 8 is connected to the plasma generation chamber 2 as a microwave introduction means via a microwave introduction window 5 and a microwave waveguide 6. The microwave source is
For example, a magnetron with a frequency of 2.45 GHz can be used.

A magnetic coil 10 for applying a magnetic field is installed on the outer periphery of the plasma generating chamber 2.
The strength of the magnetic field generated by
It is determined that the CR condition is satisfied inside the plasma generation chamber 2. For example, for microwaves with a frequency of 2.45 GHz, this condition is 875 Gauss.

The processing chamber 4 is connected to the plasma generation chamber 2 through a plasma extraction window 11 formed by an opening. Inside the processing chamber 4, a sample 12 on which a CVD film is formed and a sample table 14 holding the sample 12 are installed. Further, when viewed from the plasma generation chamber 2, a columnar high magnetic permeability member 16 and a permanent magnet 17 are sequentially arranged behind the sample table 14. A high frequency power source 1 for introducing RF power is provided to the sample table 14 and the high magnetic permeability member 16.
8 is connected.

Two gas introduction systems are prepared. The first gas introduction system 20 is for supplying the plasma raw material to the plasma generation chamber 2 and the second gas introduction system 2 is provided.
Reference numeral 2 is for supplying a chemical reaction material for film formation to the processing chamber 4.

The processing chamber 4 is connected to a vacuum exhaust system 24, and the processing chamber 4 and the plasma extraction window 11 are connected.
The plasma generation chamber 2 can be evacuated via the.

As the magnetic field inside the plasma generation chamber 2, a divergent magnetic field is adopted in the direction of the plasma extraction window 11 so that the strength of the magnetic field is weakened, so that the plasma can be efficiently moved. Further, the magnetic field is configured to reach the processing chamber 4, and the intensity of the magnetic field inside the processing chamber 4 decreases from the plasma extraction window 11 toward the sample stage 14 with a more appropriate divergence. A magnetic field is created.

The control valve 25 provided in the high-frequency power source 18, the microwave generation source 8, the first gas introduction system 20, and the control valve 26 provided in the second gas introduction system 22 are control lines of the control device 27. 28 is connected so that the control device 27 can control the amount of electric power of high frequency and microwave, the output timing, the opening and closing of the control valves 25 and 26 of the first and second gas introduction systems, and the control of the gas flow rate. Configured.

Next, a case of forming a flattened silicon oxide thin film on the sample 12 using the ECR plasma CVD film forming apparatus shown in FIG. 1 will be described.

First, oxygen gas as a plasma source gas is supplied from the first gas introduction system 20 to the plasma generation chamber 2, while silane gas (SiH) is used as a chemically reactive material gas.
4) is supplied from the second gas introduction system 22 to the processing chamber 4 by opening the control valves 25 and 26, respectively.

The ratio of the introduced amounts of oxygen gas and silane gas is
It is 2 to 1, and the pressure inside the plasma generation chamber 2 is about 1 mTo
At a pressure of rr, ECR plasma (oxygen plasma) is generated (a microwave is applied and a magnetic field is applied), and a chemical reaction between silane gas and oxygen ions is caused in the vicinity of the sample 12 to cause a chemical reaction on the sample 12. A thin film of silicon oxide is formed on.

Here, the control unit 26 controls the high frequency power source 1
8 and the microwave generation source 8 are controlled to modulate the RF power output and the microwave power output, respectively, so as to be modulated into a rectangular wave output as shown in FIG. That is, the RF power is 0 W from t = 0 to t = T1.
And the microwave power is 1000 W. Also, t =
From T1 to t = T2, the RF power is 1000 W and the microwave power is 500 W. Thus, R
By setting the F power output and the microwave power output in the rectangular wave state, film formation proceeds between t = 0 and t = T1, and sputter etching is controlled between t = T1 and t = T2. You can make progress.

Next, the dependence of the film formation rate and the sputter etching rate on the RF power output and the microwave power output will be shown.

FIG. 3 shows the relationship between the incident angle a and the film forming rate and the sputter etching rate, where the normal direction of the sample and the ion incident angle are a (see FIG. 3B). . The film forming rate has a peak at a = 0 ° and monotonically decreases as the angle increases. On the other hand, the sputter etching rate is a certain angle (about 45
Maximum). In the case of a = 0 °, the film formation speed is higher than the sputter etching speed, so that the film formation proceeds, but in the oblique portion with an angle larger than a = 0 °, the film is scraped off without forming the film. .

FIG. 4 shows the relationship between the angle a and the film forming rate and the sputter etching rate when the RF power is 500 W and the microwave power is 1000 W and when the RF power is 1000 W and the microwave power is 500 W. . Focusing on the sputter etching rate, at the angle where the speed takes the maximum (around 45 °),
In the case of "F power 1000 W, microwave power 500 W", "RF power 500 W, microwave power 1000
Compared with the case of "W", the sputter etching rate is improved about twice. The film forming rates tend to be almost the same in both cases.

FIG. 5 shows the relationship between the angle a and the film forming rate and the sputter etching rate when the RF power is 500 W and the microwave power is 1000 W, and when the RF power is 0 W and the microwave power is 1000 W. . Focusing on the film formation rate, "RF power 0
W, microwave power 1000W "," RF
Compared with the case of 500 W of electric power and 1000 W of microwave electric power, it is improved by 1.2 times over the entire angle a.
Also, focusing on the sputter etching rate,
In the case of F power of 0 W and microwave power of 1000 W, the angle is almost 0 over the entire angle a, and sputter etching hardly progresses.

As described above, by controlling the RF power output and the microwave power output, it is possible to prioritize film formation or sputter etching. Under the power modulation conditions shown in FIG. 2, from t = 0 to t = T1
Between the above-mentioned conditions, the film formation proceeds, and t = T
From 1 to t = T2, the above conditions are satisfied, and sputter etching predominantly proceeds.

Therefore, by using the method of modulating the RF power and the microwave power, the sputter etching time can be doubled, and the sputter etching time can be doubled.
It is possible to shorten the time to 0%, and it is possible to shorten the film forming time by about 20%, and as a result, it is possible to shorten the time to form the planarized silicon oxide thin film.

The result of actually forming a flattened silicon oxide thin film such as a chain line 31 on the pattern of width 0.5 × height 1.0 μm on the silicon semiconductor shown in FIG. 6 by using this method. Describe.

When a flattened silicon oxide thin film having a film thickness of 0.5 μm was formed on the pattern by the conventional method, the time required was 15 minutes.

The film forming conditions at this time are as follows: microwave power 1
000W, RF power 500W, Silane gas flow rate 10scc
m and the flow rate of oxygen gas were 20 sccm.

In contrast to this result, the time required for forming a flattened silicon oxide thin film having a film thickness of 0.5 μm on the same pattern by the method of the present invention could be shortened to 11 minutes. .

The film forming conditions at this time are a rectangular wave state with a period of 3 seconds in which "microwave power 1000 W, RF power 0 W" is 1.6 seconds and "microwave power 500 W, RF power 1000 W" is 1 second. It was output. The silane gas flow rate was 10 sccm and the oxygen gas flow rate was 20 sccm.

Thus, using the method of the present invention,
It was found that the time for forming the flattening thin film can be shortened.

In the above embodiment, the types and flow rates of the plasma raw material gas and the chemically reactive material gas in forming the flattening thin film were not modulated in synchronization with the RF power. Therefore, the control valves 25 and 26 of the device shown in FIG. 1 and the functional parts for the control valves 25 and 26 provided in the control device 27 can be eliminated. On the other hand, in the apparatus of FIG. 1, t = 0 to t = T1
During the film formation progress period between the two, oxygen gas as a plasma raw material gas and silane gas as a chemical reaction gas are introduced, and t
= T1 to t = T2, the argon gas having a high sputter etching efficiency by the plasma source gas is introduced (therefore, the control valve 26 also has a switching function) and the chemical reaction gas is used. If a certain silane gas is not introduced, the sputter etching efficiency can be further improved, and the flattening thin film formation time can be further shortened.

Further, in the above embodiment, the RF power and the microwave power are modulated with a rectangular waveform, but by modulating with a sine waveform or a composite waveform of a plurality of sine waveforms, for example, at the start of RF discharge or at a microwave. The effect of preventing abnormal discharge at the start of discharge can also be obtained.

[0043]

According to the present invention, the RF power applied to the sample on which the CVD film is formed is modulated, and the microwave power is modulated in synchronization with the modulation of the RF power. Therefore, it is possible to efficiently perform film formation and sputter etching plasma treatment. as a result,
There is an effect that it is possible to provide a method and apparatus for forming a microwave plasma CVD film, which can shorten the flattening thin film formation time and have excellent work efficiency.

[Brief description of drawings]

FIG. 1 is a front sectional view of an embodiment of the present invention.

FIG. 2 is also a time chart of the operation of the embodiment.

3A is a graph showing the relationship between the incident angle of ions and the film forming rate and the sputter etching rate, and FIG. 3B is an explanatory diagram of the incident angle of ions.

FIG. 4 RF power 500 W, microwave power 1000 W
3 is a graph showing the relationship between the incident angle of ions and the film formation rate and sputter etching rate when RF power is 1000 W and microwave power is 500 W.

FIG. 5: RF power 500W, microwave power 1000W
2 is a graph showing the relationship between the incident angle of ions and the film formation rate and sputter etching rate when RF power is 0 W and microwave power is 1000 W.

FIG. 6 is an enlarged cross-sectional view of a silicon semiconductor flattened in an example.

[Explanation of symbols]

 2 Plasma generation chamber 4 Processing chamber 5 Microwave introduction window 6 Microwave waveguide 8 Microwave generation source 10 Electromagnetic coil 11 Plasma extraction window 12 Sample 14 Sample stage 18 High frequency power source 20 First gas introduction system 22 Second gas introduction System 24 Vacuum exhaust system 25, 26 Control valve 27 Control device

Claims (5)

[Claims] 1. A plasma generation chamber, and a processing chamber provided with a sample stage for arranging a sample, wherein plasma is formed by interaction between a plasma raw material, microwave power, and a magnetic field in the plasma generation chamber, While using plasma drawn from the plasma generation chamber, a chemically reactive material is supplied to the sample chamber and RF power is applied to the sample to promote physical and chemical reactions that occur near the sample surface to form a thin film. A microwave plasma CVD film forming method, wherein the RF power and the microwave power are modulated in synchronization with each other. 2. The microwave plasma CVD film forming method according to claim 1, wherein the RF power and the microwave power have a modulation waveform of a rectangular waveform, a sine waveform, or a composite waveform of a plurality of sine waves. 3. The microwave plasma CVD film forming method according to claim 1, wherein the supply amount and type of the plasma raw material and the chemically reactive material are changed in synchronization with the modulation of the RF power and the microwave power. 4. A plasma generating chamber and a processing chamber provided with a sample stage for arranging a sample. The plasma generating chamber is provided with a microwave power introducing means and a magnetic field applying means, and a plasma source gas. In the microwave plasma CVD film forming apparatus, an introduction system is connected, a chemical reaction material gas introduction system is connected to the processing chamber, and RF power introduction means is connected to the sample stage. A microwave plasma CVD film forming apparatus, wherein a control device for modulating the electric power of each of the microwave power generation source and the RF power generation source is installed. 5. A control valve for introducing and shutting off gas and changing a flow rate in a plasma source gas introduction system and a chemically reactive material gas introduction system, each control valve being controlled by a control device, The microwave plasma CVD film forming apparatus according to claim 4, which is interposed.