JP2002299332A - Plasma-enhanced film forming method and plasma- enhanced cvd apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma-enhanced film forming method and a plasma- enhanced CVD apparatus which forms an oxide film, without causing reduction deterioration of device elements. SOLUTION: The method comprises applying a high frequency power of 500 W or more per total mass flow rate of 100 SCCM of a material gas and an oxidative gas, setting a mass flow rate ratio of the oxidative gas to a material gas to 3 or more to 1 and setting the film forming temperature to a range of 100-300 deg.C, thus forming an oxide film. For forming the oxide film, a protective (oxide) film of 500 Åor more is formed, without applying a bias, then an embedded film formation is conducted with an applied bias, and finally a high-speed film forming is conducted without bias. Oxidative gas feed nozzles are disposed above material gas feed nozzles and are located alternately in the circumferential direction of a film-forming chamber in a plan view.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma film forming method and a plasma CVD apparatus, and more particularly to a method useful for manufacturing a semiconductor device using a ferroelectric substance.

[0002]

2. Description of the Related Art At present, in the production of semiconductor devices, film formation using a plasma CVD (Chemical Vapor Deposition) apparatus is known. In a plasma CVD apparatus, a raw material gas serving as a raw material of a film is introduced into a film forming chamber in a container to be in a plasma state, and active particles (excited atoms or molecules) in the plasma cause a chemical reaction on a substrate (wafer) surface. This is a device that promotes the film formation. The container is provided with an electromagnetic wave transmitting window, and power is supplied from a high frequency power supply to a power supply antenna disposed outside the container, and the electromagnetic wave enters the film forming chamber through the electromagnetic wave transmitting window, so that the energy of the electromagnetic wave (high frequency The gas in the film forming chamber is brought into a plasma state by power.

In such a plasma CVD apparatus, when forming an SiO _x film (SiO ₂ film or the like) which is an oxide film (insulating film) for insulating elements or wirings from each other, SiH ₄ is used as a source gas. Or Si (OC ₂ H ₅ ) ₄ (TE
OS: tetraethoxysilane) and O ₂ or N ₂ O as an oxidizing gas.

[0004]

[SUMMARY OF THE INVENTION However, in the production of semiconductor devices using a ferroelectric, when forming the SiO _X film by the conventional plasma CVD apparatus, the raw material gas SiH ₄ and Si (OC ₂ H ₅ ) Since ₄ contains a large amount of hydrogen, ferroelectrics undergo hydrogen reduction degradation.

More specifically, a ferroelectric memory has recently attracted attention as a semiconductor device using a ferroelectric, and has been put to practical use. This ferroelectric memory uses a ferroelectric PZT.
(Lead, zinc, tantalum) and SBT (strontium, bismuth, tantalum) and other metal oxide films sandwiched between Pt electrodes and Ir electrodes.
(Large Scale Integration) It is built into a memory, and by using the remanent polarization characteristics of this ferroelectric capacitor, it can be operated as a non-volatile memory that can retain information even when power is turned off. Things.

[0006] In the manufacture of such a ferroelectric memory, when forming the SiO _X film by the conventional plasma CVD apparatus, SiH ₄ and Si source gas (OC ₂ H
₅ ) Since ₄ contains a large amount of hydrogen, the metal oxide film (PZT film, SBT film) is reduced by the hydrogen gas (hydrogen ions) generated by decomposition of these source gases, and Of oxygen is removed as OH (it escapes). For this reason, the characteristics of the ferroelectric capacitor are degraded (residual polarization is reduced).

This is more remarkable when a bias is applied for the purpose of attracting + ions. That is, when the SiO _X film is formed on the substrate, the SiO _X is buried in the gap between the elements and the wirings on the substrate. At this time, the gap is, for example, 0.35 μm to 0.25 μm. In a very narrow case, by applying a bias to the substrate side with a bias power supply, ions for sputter etching such as Ar are drawn into the substrate side, and the oxide film deposited on the corners of the element or wiring is sputter-etched. Before the SiO _x film is embedded in the entire gap, the entrance of the gap is SiO
_It is necessary to prevent the _X film from being blocked.

For example, in FIG. 12, a ferroelectric capacitor (PZT capacitor) 103 having a structure in which a PZT 101 is sandwiched between Pt electrodes 102 is formed on a substrate (Si wafer) 100. If the gap 104 is very narrow, (without sputter etching) without applying a bias when an attempt is made to form a SiO _X film, the corners of the ferroelectric capacitor 103 as shown by a chain line in FIG. 12 SiO _X film is deposited in the gap 10
4 is blocked, and SiO _x
The film cannot be embedded. Therefore, in addition to the raw material gas and the oxidizing gas, an inert gas such as Ar was supplied, and a bias was applied to the substrate side to draw in Ar ions, thereby depositing on the corners of the ferroelectric capacitor 103. Gap 1 by sputter etching SiO _x film
Expand the 04 entrance.

However, at this time, since hydrogen ions are also attracted at the same time, a hydrogen ion attack occurs on the ferroelectric capacitor 103 as shown in FIG. 12, and the hydrogen ion concentration near the wafer also increases.
Hydrogen reduction deterioration of the ferroelectric capacitor 103 becomes more remarkable.

Accordingly, an object of the present invention is to provide a plasma film forming method and a plasma CVD apparatus capable of forming an oxide film without causing reduction deterioration of the device in view of the above problems.

[0011]

Means for Solving the Problems A first method for solving the above problems is described below.
The plasma film forming method of the present invention forms an oxide film on a substrate by applying a high-frequency power to a raw material gas and an oxidizing gas supplied under a low-pressure environment, and utilizing a chemical reaction by plasma generated thereby. In the plasma film forming method, a high frequency power is applied for the purpose of sufficiently separating and decomposing the reducing gas in the raw material gas, and the amount of the oxidizing gas with respect to the raw material gas is oxidized. By reacting the oxidizing gas with a reducing gas generated by decomposition of a source gas by making the amount larger than that required for forming a film, deterioration of the reduction reaction of the element on the substrate by the reducing gas is suppressed. And

The plasma film forming method according to a second aspect of the present invention is the plasma film forming method according to the first aspect, wherein a high frequency power of 500 W or more is applied per 100 SCCM total mass flow rate of the raw material gas and the oxidizing gas, The mass flow ratio of the oxidizing gas to the gas is three times or more, and the film forming temperature range is 100 ° C. to 300 ° C. to form the oxide film.

[0013] The plasma film deposition method of the third invention, in the plasma film forming method of the first or second invention, the frequency of the high frequency power, characterized in that the range of 400kH _Z ~3GH _Z.

The plasma film forming method according to a fourth invention is the plasma film forming method according to the first, second or third invention, wherein the source gas is SiH ₄ , the oxidizing gas is O ₂ , and the oxide film is SiO _X
It is characterized by being.

A fifth aspect of the present invention is the plasma deposition method according to the first, second or third aspect, wherein the source gas is SiH ₄ , the oxidizing gas is N ₂ O, and the oxide film is SiO 2.
Characterized in that it is a _X N _y.

Further, in the plasma film forming method according to the sixth aspect of the present invention, a high frequency power is applied to a source gas and an oxidizing gas supplied under a low pressure environment, and a chemical reaction by a plasma generated by the high frequency power is used. In a plasma film forming method for forming an oxide film on a substrate, an oxide film covering elements on the substrate is formed without applying a bias for the purpose of attracting + ions to the substrate side. A first film forming step as a protective film against hydrogen ion attack, and after forming the protective film in the first film forming step, a bias is applied to the substrate side for drawing in + ions for sputter etching,
A second film forming step of embedding an oxide film in a minute gap between elements or wirings.

According to a seventh aspect of the present invention, in the plasma deposition method according to the sixth aspect, after the oxide film is buried in the second deposition step, + ions are drawn into the substrate side. A third film forming step for forming an oxide film without applying a bias for the purpose is provided.

According to an eighth aspect of the present invention, in the plasma deposition method of the sixth or seventh aspect, the protective film has a thickness of 500 Å or more.

The ninth aspect of the present invention is the plasma deposition method according to the sixth, seventh, or eighth aspect, wherein the oxidization is performed based on the deposition conditions of the first, second, or third aspect. The method is characterized in that a film is formed.

Further, a plasma film forming method according to a tenth aspect of the present invention
In the sixth, seventh, eighth or ninth aspect of the present invention, the source gas is SiH ₄ , the oxidizing gas is O ₂ , and the oxide film is SiO _X.

[0021] The plasma film forming method of the eleventh invention is characterized in that:
In the sixth, seventh, eighth, or ninth aspect of the present invention, the source gas is SiH ₄ , the oxidizing gas is N ₂ O, and the oxide film is SiO _X N _y .

Further, the plasma film forming method according to the twelfth invention is characterized in that
In the plasma deposition method according to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, or eleventh inventions, a film is formed from above a film formation chamber by a feeding antenna. A high-frequency power is supplied to the room, and a plurality of source gas supply nozzles and a plurality of oxidizing gas supply nozzles are arranged such that the oxidizing gas supply nozzle is at the top and the source gas supply nozzle is at the bottom, and
The raw material gas supply nozzles and the oxidizing gas supply nozzles are arranged so as to be alternately arranged in the circumferential direction of the film forming chamber in plan view, and the raw material gas is supplied into the film forming chamber by the raw material gas supply nozzle, and the oxidizing gas is The oxidizing gas is supplied into the film forming chamber by the oxidizing gas supply nozzle.

The plasma CVD apparatus according to the thirteenth aspect of the present invention comprises a film forming chamber, a power supply antenna for supplying high frequency power from above the film forming chamber to the film forming chamber, and a plurality of power supply antennas for supplying a source gas into the film forming chamber. In a plasma CVD apparatus provided with a source gas supply nozzle and a plurality of oxidization gas supply nozzles for supplying an oxidizing gas into a film formation chamber, the source gas supply nozzle and the oxidization gas supply nozzle are placed above the oxidization gas supply nozzle. And the source gas supply nozzle is disposed below, and the source gas supply nozzle and the oxidizing gas supply nozzle are disposed alternately in the circumferential direction of the film forming chamber in plan view. I do.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a configuration of a plasma CVD apparatus according to an embodiment of the present invention. As shown in FIG.
A cylindrical aluminum container 2 is provided on the upper side, and the inside of the container 2 is a film forming chamber 3. A circular ceiling plate 4 serving as an electromagnetic wave transmission window is provided on the upper part of the container 2, and a substrate support 5 is provided inside the container 2 (in a film forming chamber). The substrate support table 5 has a disk-shaped substrate mounting portion 7 for electrostatically holding a substrate 100 of a semiconductor element by suction. The substrate mounting portion 7 is supported by a support shaft 8.

The substrate 100 is a disk-shaped Si wafer,
As is well known, those with φ150 mm (6 inches) and φ20
There are various sizes such as 0 mm (8 inches). A bias power supply 12 is connected to the substrate mounting unit 7 via a matching unit 10 and a capacitor 11 for performing impedance matching. That is, the substrate mounting portion 7 also functions as a bias electrode. Further, an electrostatic power supply 13 is also connected to the substrate mounting section 7. When a voltage of a high frequency (e.g., 2 MH _Z) is supplied from a bias power source 12, a bias is applied to the substrate platform 7 (substrate 100). DC power is supplied from the electrostatic power supply 13, and the substrate 100 is attracted to the substrate mounting portion 7 by electrostatic force generated in the substrate mounting portion 7. In addition, the substrate support 5
The height of the substrate 100 in the vertical direction can be adjusted to an optimum height by making the whole movable up and down or making the support shaft 8 extendable.

A heater 25 is provided in the substrate mounting section 7 as a film forming temperature setting means. A heater power supply 26 is connected to the heater 25, and by appropriately adjusting the power supplied from the heater power supply 26 to the heater 25, the temperature of the substrate 100 (film formation temperature) can be appropriately adjusted. ing. The film forming temperature setting means is not necessarily limited to a heater. For example, a fluid such as a gas is supplied to the substrate mounting unit 7 and the film forming temperature is adjusted by adjusting the temperature of the fluid such as the gas. May be adjusted appropriately. The film forming temperature setting means adjusts the film forming temperature based on film forming conditions (film forming temperature range) described later.

The base 1 is provided with an exhaust port 22.
The exhaust port 22 is connected to a vacuum exhaust system (not shown). Accordingly, the gas in the film forming chamber 3 is exhausted to the vacuum exhaust system through the exhaust port 22. Also, the container 2 has a substrate 100
The loading / unloading port (not shown) is provided, and loading and unloading of the substrate 100 is performed with a transfer chamber (not shown).

On the other hand, a spiral feeding antenna 14 is installed on the ceiling plate 4.
4 is a matching device 1 for performing impedance matching.
A high-frequency power supply 16 is connected via the terminal 5. Therefore,
By applying a high-frequency (for example, 13.56 MHz) power from the high-frequency power supply 16 to the power supply antenna 14, the electromagnetic wave 24 is incident on the film formation chamber 3 from the power supply antenna 14 via the ceiling plate 14. That is, by the feeding antenna 14,
Electromagnetic energy (high-frequency power) is supplied into the film formation chamber 3 from above the film formation chamber 3. The high-frequency power supply 16 adjusts the high-frequency power based on film formation conditions (high-frequency power) described later.

The container 2 is provided with a plurality of source gas supply nozzles 17 leading into the film forming chamber 3 and a plurality of oxidizing gas supply nozzles 18. Source gas supply nozzle 17
Is connected to a source gas supply system (not shown) via an MFC (Mass Flow Controller) 21. Therefore, the source gas supplied from the source gas supply system is supplied into the film forming chamber 3 through the MFC 21 and the source gas supply nozzle 17. At this time, the mass flow rate of the source gas supplied to the film forming chamber 3 is controlled to a predetermined mass flow rate by the MFC 21. SiH ₄ is used as a source gas for the SiO _X film.

The oxidizing gas supply nozzle 18 is connected to an oxygen gas supply system (not shown) via an MFC 19,
It is also connected to a sputter etching gas supply system via C20. Therefore, the oxidizing gas supplied from the oxidizing gas supply system is supplied to the MFC 19 and the oxidizing gas supply nozzle 18.
Is supplied into the film forming chamber 3 through the At this time, the film forming chamber 3
The mass flow rate of the oxidizing gas supplied to the inside is controlled by the MFC 19 to a predetermined mass flow rate. O ₂ as oxidizing gas
Is used. The MFCs 19 and 21 respectively control the mass flow rate of the oxidizing gas and the mass flow rate of the source gas based on film formation conditions (gas mass flow rate ratio) described later.

The sputter etching gas supplied from the sputter etching gas supply system is supplied into the film forming chamber 3 through the MFC 20 and the oxidizing gas supply nozzle 18. At this time, the mass flow rate of the sputter etching gas supplied into the film forming chamber 3 is controlled by the MFC 20 to a predetermined mass flow rate. Ar as a sputter etching gas
Is used. Note that an auxiliary gas such as NF ₃ for cleaning is also supplied into the film forming chamber 3 from the oxidizing gas supply nozzle 18. That is, the oxidizing gas supply nozzle 18 in the illustrated example is a common auxiliary gas nozzle for supplying various auxiliary gases.

The source gas supply nozzle 17 and the oxidizing gas supply nozzle 18 are arranged so that the oxidizing gas supply nozzle 18 is at the top and the source gas supply nozzle 17 is at the bottom, as shown in FIG. As shown in FIG. 2, the raw material gas supply nozzles 17 and the oxidizing gas supply nozzles 18 are arranged alternately in the circumferential direction of the film forming chamber 3 in plan view.

The reason why the oxidizing gas supply nozzle 18 is set to the upper side and the source gas supply nozzle 17 is set to the lower side is to form an oxide film (SiO _X film) efficiently as is well known. That is, the feeding antenna 14 is raised with the oxidizing gas supply nozzle 18 raised.
By supplying O ₂ near the, first, SiH by the O ₂ and in the plasma state, to collide The generated O ₂ radicals (active particles) to SiH _4
This is because the SiO ₂ film can be formed more efficiently by decomposing ₄ to react Si and O ₂ .

In addition, in the present embodiment, the source gas supply nozzles 17 and the oxidizing gas supply nozzles 18 are arranged alternately in the circumferential direction of the film forming chamber 3 in plan view. As a result, the source gas supply nozzle 17
And the oxidizing gas supplied from the oxidizing gas supply nozzle 18 are efficiently mixed in the center of the film forming chamber 3. That is, in order to form a uniform oxide film, the oxidizing gas supplied from the oxidizing gas supply nozzle 18 into the film forming chamber 3 and the source gas supplied from the source gas supplying nozzle 17 into the film forming chamber 3 It is better to mix as much as possible in the central part of the film forming chamber 3. However, simply disposing the oxidizing gas supply nozzle 18 on the upper side and the source gas supply nozzle 17 on the lower side will cause the oxidizing gas and the source gas to be mixed. They are mixed immediately after entering the film forming chamber 3.

On the other hand, when the source gas supply nozzles 17 and the oxidizing gas supply nozzles 18 are alternately arranged in the circumferential direction of the film forming chamber 3, the source gas and the oxidizing gas are deposited as described above. Mixing is efficiently performed at the center of the chamber 3.
This is effective in forming a uniform oxide film, and is also effective in suppressing hydrogen reduction deterioration since the reaction between hydrogen and oxygen in the gas phase can be performed efficiently.

In the plasma CVD apparatus of the present embodiment, in order to form the oxide film while suppressing the hydrogen reduction deterioration of the ferroelectric element, the details will be described later. The process (control sequence) is set. The film forming conditions are three conditions of a gas mass flow ratio, a high frequency power, and a film forming temperature range. The film forming process is performed by turning on / off the MFCs 19, 20, 21 based on a predetermined control sequence by a controller 30 having a microcomputer.
FF control, ON / OFF control of the high frequency power supply 16, ON / OFF control of the bias power supply 12, etc. are performed to start and stop the supply of the source gas, the oxidizing gas and the sputter etching gas, and to start and stop the supply of the high frequency power. This is performed by controlling the timing, the timing of starting and stopping the application of bias power, and the like. The controller 30 also performs power supply timing control of the electrostatic power supply 13 and power supply timing control of the heater power supply 26.

<Film formation conditions> In order to suppress the hydrogen reduction reaction by sufficiently decomposing the raw material gas and reacting the hydrogen in the gas phase (in the plasma) with the oxidizing gas to exhaust as water, It is necessary to perform film formation by setting the following three conditions (gas mass flow rate ratio, high frequency power, film formation temperature) within a predetermined range.

(1) Gas Mass Flow Rate The gas mass flow rate is defined as the oxidizing gas O _{2 with} respect to the mass flow rate (SCCM) of SiH ₄ of the source gas supplied to the film forming chamber 3.
Is the ratio of the mass flow rate (SCCM). Conventionally, SiH ₄
It has been shown that the gas mass flow ratio of O _{2 to} the gas is about 1.5 times the best from the viewpoint of the film quality and the embedding property. However, it is necessary to make the gas flow rate 3 times or more from the influence on the device damage.

That is, the amount of the oxidizing gas with respect to the source gas is made larger than the amount required for forming the SiO _x film, that is, by increasing the ratio of the oxidizing gas to generate a large amount of oxygen ions, The hydrogen in the gas phase is removed as H ₂ O by reacting the ions with the hydrogen gas (reducing gas) in the gas phase generated by the decomposition of the source gas. Incidentally, in the conventional ordinary plasma film forming process, the gas mass flow ratio is twice or less especially when SiH ₄ is used as a source gas and oxygen is used as an oxidizing gas. Note that the upper limit of the gas mass flow ratio may be appropriately set (for example, six times) not from the viewpoint of hydrogen reduction degradation but from the viewpoint of the film quality of the oxide film and the performance of the device.

[0041] For reference, in FIG. 3 shows the results of measurement of the hydrogen ion current value by changing the gas mass flow rate ratio (O ₂ / SiH _4), in FIG. 4 gas mass flow ratio (O ₂ / Si
The result of measuring the hydrogen content in the film while changing H ₄ ) is shown. FIG. 3 shows that the hydrogen ion current value decreases as the gas mass flow ratio increases. That is, it is understood that the hydrogen gas in the gas phase is reduced. From FIG.
It can be seen that the hydrogen content decreases as the gas mass flow ratio increases. A small hydrogen content in the film means that there is little hydrogen reduction degradation.

FIG. 5 shows the gas mass flow ratio (O ₂
/ SiH ₄ ) is shown, and the result of measuring the residual polarization of the ferroelectric capacitor is shown. The remanent polarization is a remnant polarization (corresponding to a residual charge amount) when a voltage applied to a ferroelectric capacitor (PZT capacitor or the like) becomes 0 (V). In FIG. 5, the remanent polarization when the ferroelectric capacitor is not deteriorated (before the oxide film is formed) is set to 100 (%), and the ratio (%) of the remanent polarization of the ferroelectric capacitor after the oxide film is formed to the remanent polarization is shown. ing. From the figure, it is understood that the gas mass flow ratio needs to be three times or more.

FIG. 6 shows an example of the gas mass flow ratio (O
₂ / SiH ₄ ) is shown as a result of measuring the polarization with respect to the applied voltage of the ferroelectric capacitor before and after forming the oxide film by 5 times. From the figure, it can be seen that when the gas mass flow ratio is increased by 5, the characteristics of the ferroelectric capacitor are hardly deteriorated even after the oxide film is formed, as compared with before the oxide film is formed.

When the ferroelectric capacitor is deteriorated by hydrogen reduction during the formation of the oxide film, the interval between the positive and negative polarizations at an applied voltage of 0 (V) becomes very narrow, so that the determination of the bit 1,0 is made. (Determined as 1 for a positive charge equal to or more than a predetermined value and 0 for a negative charge equal to or more than a predetermined value). Further, the polarization (charge) at the saturation point of the ferroelectric capacitor deteriorated by hydrogen reduction also decreases. That is, it does not function as a ferroelectric capacitor.

(2) High-frequency power FIG. 7 shows a change in ion current value when the high-frequency power is changed. FIG. 7 shows that the hydrogen ion current value decreases as the high frequency power increases.

The required high-frequency power for suppressing the incorporation of hydrogen was determined from the characteristic deterioration of the ferroelectric capacitor. By applying a high frequency power of 500 W or more per 100 SCCM total mass flow rate of the source gas and the oxidizing gas, it is possible to suppress the characteristic deterioration of the ferroelectric capacitor. For example, SiH ₄ gas 50
1500 W for SCCM and 250 SCCM oxygen gas
What is necessary is just to supply the above high frequency power. By injecting high-frequency high power into the film forming chamber 3, the decomposition of the following source gas is promoted. The upper limit of the high-frequency power may be appropriately set not from the viewpoint of hydrogen reduction deterioration but from the viewpoint of device performance such as insulation. SiH ₄ → Si, H

(3) Film forming temperature range Even if the gas mass flow rate ratio and the high frequency power are within the above-mentioned set range, if the temperature is not lower than 300 ° C., the ferroelectric material is deteriorated by hydrogen reduction. That is, when the film formation temperature is high, even if there is only a small amount of hydrogen in the gas phase, hydrogen reduction degradation occurs. On the other hand, from the viewpoint of suppressing hydrogen reduction degradation of the ferroelectric, it is desirable to form the film as low as possible, but from the viewpoint of the insulating properties of the oxide film as the insulating film, the lower limit of the film forming temperature is set to 100 ° C. .

In other words, if the gas mass flow ratio and the high frequency power are set within the above-mentioned ranges, a good film quality can be obtained even when the film forming temperature is as low as 300 ° C. or less.

Next, a control sequence for forming an oxide film based on the above film forming conditions will be described. Hereinafter, a control sequence in the case where the protective film is not formed and a control sequence in the case where the protective film is formed will be described.

<Control Sequence: No Protective Film> FIG. 8 shows a control sequence when no protective film is formed, and FIG. 9 shows a film forming state based on the control sequence. As shown in both figures, when the protective film is not formed,
An oxide film (Si) is formed by two processes of buried film formation and high-speed film formation.
O _X film) is formed.

Specifically, first, the substrate 100 is placed on the substrate placing portion 7 and electrostatically attracted. Then, as shown in FIG. 8, at time T ₁ , the supply of the source gas (SiH ₄ ) from the source gas supply nozzle 17 is started, and the oxidizing gas (O ₂ ) from the oxidizing gas supply nozzle 18 and the sputter etching are started. The supply of gas (Ar) is also started. Subsequently, the supply of the high-frequency power from the high frequency power supply 16 (power supply antenna 14) begins at time T _2, then, starts the biasing of the substrate by the bias power source 12 at time T _3. Thus, the embedded film formation starts, then, when it becomes time T _4, i.e., the application of the bias is stopped when the predetermined padding deposition time has elapsed.

At this time, the supply of the high frequency power causes the oxidizing gas and the raw material gas in the film forming chamber 3 to be in a plasma state, and the active particles (excited atoms or molecules) in the plasma efficiently cause a chemical reaction, and the oxide film such as ₂ film (SiO _X film) is formed like between devices or between wiring (embedded). For example, in FIG. 9, a plurality of ferroelectric capacitors (PZT capacitors) 103 having a structure in which a PZT 101 is sandwiched between Pt electrodes 102 are formed on a substrate 100. In the embedded film forming process, as shown in FIG. The SiO _x film 105 is embedded in the gap 104 of the ferroelectric capacitor 103.

At this time, a bias is applied to A
By attracting r ions, the oxide film deposited on the corners of the ferroelectric capacitor 103 is sputter-etched as shown in FIG. 9A, thereby preventing the entrance of the gap 104 from being blocked. . Incidentally, the etching with Ar ions is performed on the entire oxide film. However, from the relation of the angle at which the Ar ions hit (the etching rate is higher when the ions hit obliquely), especially the etching rate of the oxide film at the corner of the ferroelectric capacitor 103 is increased. Will be higher.

The distance between the gaps 104 is relatively wide, so that the gap 1 can be formed without etching with Ar ions.
When there is no possibility that the entrance of the entry 04 will be blocked, no bias needs to be applied. On the other hand, when the bias power (electric power) is relatively small, there is not much problem. However, when it is necessary to increase the bias power in order to increase the etching rate (etching rate) by the sputter etching gas, As will be described later, since problems such as hydrogen ion attack occur, it is necessary to perform protective film formation before performing embedded film formation.

After completion of the embedded film formation, high-speed film formation is started as shown in FIG. In other words, when the burying film formation is completed and the application of the bias is stopped, sputter etching by Ar ions does not occur, so that even if the mass flow rate of the source gas or the mass flow rate of the oxidizing gas is the same,
The film formation rate (film formation rate) of the oxide film formed by the same chemical reaction as described above is increased. The high-speed film formation is started at time T _4, then, when it becomes time T _5, i.e., the raw material gas (S when a predetermined high-speed film formation time has elapsed
iH ₄ ), the supply of the oxidizing gas (O ₂ ), and the supply of the sputter etching gas (Ar) are stopped. Time T
_{At 5} , the supply of high frequency power is also stopped. Thus,
The oxide film 105 formed by burying film-forming step as shown in FIG. 9 (b), an oxide film (SiO _X film) with a thickness of the target obtained by combining the oxide film 106 formed in high-speed film formation step insulating film Is formed as

Note that Ar is not always necessary because sputter etching is not performed in high-speed film formation. However, since Ar is a gas that tends to be in a plasma state (is easily ionized), the Ar ions decompose the raw material gas. In this case, Ar is supplied even in high-speed film formation.

In FIG. 8, the mass flow rates of the source gas, the oxidizing gas, and the sputter etching gas are the same for the buried film formation and the high-speed film formation. In the case where a sufficient rate cannot be obtained, for example, although not shown, the gas mass flow rate is reduced in the embedded film forming step in which a bias is applied, and the gas mass flow rate is reduced in the high-speed film forming step in which no bias is applied. May be higher. In this case, of course, the increase in the deposition rate in the high-speed deposition becomes more remarkable.

<Control Sequence: With Protective Film> If the above three conditions (film forming conditions) are satisfied, a ferroelectric capacitor (PZT capacitor) 103 that is susceptible to hydrogen reduction degradation is attached to the substrate 100. Even when the ferroelectric capacitor 103 is formed, the ferroelectric capacitor 103 is not deteriorated by hydrogen reduction when forming an oxide film (SiO _x film) on the substrate 100.

However, as described above, in the case where a bias is applied to the substrate side to draw Ar ions (sputter etching) in the buried film formation,
As shown in FIG. 12, a hydrogen ion attack occurs on the ferroelectric capacitor 103 and the hydrogen ion concentration near the wafer also increases.
03 easily undergoes hydrogen reduction degradation. Therefore, in order to prevent a hydrogen ion attack or the like when performing a burying film formation by applying a bias, a protective film is formed without applying a bias before performing the burying film formation.

The film forming process (control sequence) at this time will be described below with reference to FIGS. FIG. 10 shows a control sequence for forming a protective film, and FIG. 11 shows a film forming state based on the control sequence. As shown in both figures, when forming a protective film,
The third step of film formation and high-speed film formation and embedded protective film formation to form an oxide film (SiO _X film).

Specifically, first, the substrate 100 is placed on the substrate placing portion 7 and electrostatically attracted. Then, as shown in FIG. 10, the supply of the raw material gas (SiH ₄₎ from the raw material gas supply nozzle 17 begins at a time T _11, also oxidizing gas from the oxidizing gas supply nozzle 18 (O ₂₎ and sputter etching The supply of gas (Ar) is also started. continue,
High frequency power source 16 at time T ₂ (the power supply antenna 14)
Start supplying high frequency power from. Thus, initiated protective film is, then, when it becomes time T _13, i.e., the protective film until the bias is applied when the predetermined protection film formation time has elapsed is continued.

At this time, the supply of the high frequency power causes the oxidizing gas and the raw material gas in the film forming chamber 3 to be in a plasma state, and the active particles (excited atoms or molecules) in the plasma efficiently cause a chemical reaction, and the oxide film such as ₂ film (SiO _X film) is formed like element or between wires and between these surfaces. This oxide film is used as a protective film for protecting the device from a hydrogen ion attack. For example, in FIG. 11, a ferroelectric capacitor (PZT capacitor) 10 having a structure in which a PZT 101 is sandwiched between Pt electrodes 102 is shown.
3 are formed on the substrate 100. In the protective film forming step, as shown in FIG. 11A, a protective film (SiO 2) is formed on the gap 104 of the ferroelectric capacitor 103 and the surface of the ferroelectric capacitor 103. _X film) 107 is formed.

The thickness of this protective film 107 is set to 500 Å or more. Table 1 shows the dependency on the protective film thickness, that is, the PZT capacitor of the Pt electrode type and the PZT of the Ir electrode type.
The results of evaluating the peeling of the electrode and the deterioration of the characteristics of the ferroelectric capacitor after the burying film formation (details will be described later) with respect to the thickness of the protective film for the T capacitor are shown. This [Table 1]
It can be seen from the results that the thickness of the protective film is desirably 500 Å or more.

[0064]

[Table 1]

Gap 104 between ferroelectric capacitors 103
Is very narrow, for example, 0.35 μm to 0.25 μm, if the film is formed to about 500 angstroms, the entrance of the gap 104 is made of an oxide film without applying a bias (even without performing sputter etching). Thus, the protective film 107 can be reliably formed even in the gap 104.

After the completion of the protection film formation, the embedded film formation is started as shown in FIG. In other words, by starting the application of a bias to the substrate side by the bias power source 12 at time T _13, the buried film formation is started. This to the buried film formation at time T _14, i.e., is continued until the elapse of the predetermined padding deposition time. This allows the oxide film by the same chemical reactions and the (SiO _X film)
Are formed (embedded) between elements and between wirings.
For example, as shown in FIG. 11B, the SiO _x film 105 is embedded in the gap 104 of the ferroelectric capacitor 103.

At this time, by applying a bias to pull in Ar ions, the oxide film deposited on the corners of the ferroelectric capacitor 103 is sputter-etched as shown in FIG. Prevents the entrance from being blocked. As described above, the etching rate of the oxide film by the Ar ions is particularly high at the corners of the ferroelectric capacitor 103.

At this time, as shown in FIG. 11A, hydrogen ions are also attracted by the bias, causing a hydrogen ion attack and increasing the hydrogen ion concentration near the wafer. Since the traps 107 are made, deterioration of the ferroelectric capacitor 103 by hydrogen reduction can be suppressed. For this reason, the buried film can be formed even between extremely narrow elements or between wirings where a bias must be applied to perform sputter etching without causing reduction deterioration of the elements.

After completion of the embedded film formation, high-speed film formation is started as shown in FIG. That is, when the bias film formation is completed and the application of the bias is stopped, sputter etching by Ar ions does not occur. Therefore, even when the mass flow rate of the source gas and the mass flow rate of the oxidizing gas are the same, the same as above. The film forming rate (film forming rate) of the oxide film formed by the chemical reaction of (1) increases.

This high-speed film formation is performed at time T₁₄Started with
Then, at time T₁₅, That is, a predetermined high-speed film formation
After the passage of time, the raw material gas (SiH_Four), Oxidizing gas
(O _Two) And supply of sputter etching gas (Ar)
Continued until stopped. Time T₁₅At high frequency
The supply of power is also stopped. Thus, as shown in FIG.
Film (oxide film) 107 formed in the protective film forming step as described above.
And the oxide film 105 formed in the embedded film forming process,
Target thickness including oxide film 106 formed in the film forming process
Oxide film (SiO_XFilm) is formed as an insulating film.

Note that Ar is not always necessary because sputter etching is not performed in high-speed film formation. However, since Ar is a gas that tends to be in a plasma state (is easily ionized), the Ar ions decompose the raw material gas. In this case, Ar is supplied even in high-speed film formation.

In FIG. 10, the mass flow rates of the source gas, the oxidizing gas, and the sputter etching gas are the same for the protective film, the buried film formation, and the high-speed film formation. In the case where a sufficient power (etching rate) cannot be obtained, the illustration is omitted. However, in the embedded film forming step of applying a bias, the gas flow rate is reduced, and a protective film forming step in which a bias is not applied or a high-speed film forming step is performed. In the step, the gas mass flow rate may be increased. In this case, of course, the increase in the deposition rate in the high-speed deposition becomes more remarkable.

In the above description, the case where O ₂ is used as the oxidizing gas has been described. However, the present invention is not limited to this, and N ₂ O may be used as the oxidizing gas. N
_{When 2} O is used, an SiO _X N _y film is formed as an oxide film. In this case, too, the same film forming conditions (gas mass flow rate ratio, high frequency power, film forming temperature range) and film forming conditions are used. A membrane process (control sequence) can be applied.

[0074]

As described above in detail with the embodiments of the present invention, the plasma film forming method of the first invention applies a high frequency power to a source gas and an oxidizing gas supplied under a low pressure environment. In a plasma film forming method that forms an oxide film on a substrate by utilizing the chemical reaction of the plasma generated by this, the reducing gas in the source gas is sufficiently separated from the high frequency power required for film formation. A high frequency power is applied for the purpose of decomposition, and the amount of the oxidizing gas with respect to the source gas is made larger than the amount required for forming the oxide film. By reacting, degradation of the reduction reaction of the device on the substrate by the reduction gas is suppressed.

The plasma film forming method according to the second invention is the plasma film forming method according to the first invention, wherein a high frequency power of 500 W or more is applied per 100 SCCM of the total mass flow rate of the source gas and the oxidizing gas, The mass flow ratio of the oxidizing gas to the gas is three times or more, and the film forming temperature range is 100 ° C. to 300 ° C. to form the oxide film.

[0076] The plasma film deposition method of the third invention, in the plasma film forming method of the first or second invention, the frequency of the high frequency power, characterized in that the range of 400kH _Z ~3GH _Z.

The plasma film forming method according to the fourth invention is the plasma film forming method according to the first, second or third invention, wherein the source gas is SiH ₄ , the oxidizing gas is O ₂ , and the oxide film is SiO _X
It is characterized by being.

The plasma film forming method according to the fifth invention is the plasma film forming method according to the first, second or third invention, wherein the source gas is SiH ₄ , the oxidizing gas is N ₂ O, and the oxide film is SiO 2.
Characterized in that it is a _X N _y.

Therefore, according to the plasma film forming method of the first, second, third, fourth or fifth invention, the reducing gas contained in the source gas efficiently reacts with the oxidizing gas and is removed. Therefore, an oxide film can be formed without causing reduction degradation of the element. In addition, by forming a film at a low temperature of 300 ° C. or lower, the film forming speed can be improved, and the apparatus configuration can be simplified.

In the plasma film forming method of the sixth invention, a high-frequency power is applied to a source gas and an oxidizing gas supplied under a low-pressure environment, and a chemical reaction by the plasma generated thereby is used. In a plasma film forming method for forming an oxide film on a substrate, an oxide film covering elements on the substrate is formed without applying a bias for the purpose of attracting + ions to the substrate side. A first film forming step as a protective film against hydrogen ion attack, and after forming the protective film in the first film forming step, a bias is applied to the substrate side for drawing in + ions for sputter etching,
A second film forming step of embedding an oxide film in a minute gap between elements or wirings.

The plasma film forming method according to a seventh aspect of the present invention is the plasma film forming method according to the sixth aspect, wherein after the oxide film is buried in the second film forming step, + ions are drawn into the substrate side. A third film forming step for forming an oxide film without applying a bias for the purpose is provided.

The plasma film forming method according to the eighth invention is characterized in that, in the plasma film forming method according to the sixth or seventh invention, the thickness of the protective film is 500 Å or more.

The ninth aspect of the present invention is the plasma deposition method according to the sixth, seventh or eighth aspect of the present invention, wherein the oxidization is performed based on the deposition conditions of the first, second or third aspect. The method is characterized in that a film is formed.

The plasma film forming method according to the tenth aspect of the present invention
In the sixth, seventh, eighth or ninth aspect of the present invention, the source gas is SiH ₄ , the oxidizing gas is O ₂ , and the oxide film is SiO _X.

The plasma film forming method according to the eleventh aspect of the present invention
In the sixth, seventh, eighth, or ninth aspect of the present invention, the source gas is SiH ₄ , the oxidizing gas is N ₂ O, and the oxide film is SiO _X N _y .

Therefore, according to the sixth, seventh, eighth, ninth, tenth, or eleventh plasma deposition method of the present invention, the protective film can prevent hydrogen ion attack on the element, and the like. When applying a bias,
An oxide film can be formed without causing reduction degradation of the element. That is, buried film formation can be performed even between extremely narrow elements or between wirings where a bias must be applied to perform sputter etching without causing reduction deterioration of the elements.

Further, the plasma film forming method according to the twelfth aspect of the present invention
In the plasma deposition method according to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, or eleventh inventions, a film is formed from above a film formation chamber by a feeding antenna. A high-frequency power is supplied to the room, and a plurality of source gas supply nozzles and a plurality of oxidizing gas supply nozzles are arranged such that the oxidizing gas supply nozzle is at the top and the source gas supply nozzle is at the bottom, and
The raw material gas supply nozzles and the oxidizing gas supply nozzles are arranged so as to be alternately arranged in the circumferential direction of the film forming chamber in plan view, and the raw material gas is supplied into the film forming chamber by the raw material gas supply nozzle, and the oxidizing gas is The oxidizing gas is supplied into the film forming chamber by the oxidizing gas supply nozzle.

The plasma CVD apparatus according to the thirteenth aspect of the present invention comprises a film forming chamber, a power supply antenna for supplying high frequency power from above the film forming chamber to the film forming chamber, and a plurality of power supply antennas for supplying a source gas into the film forming chamber. In a plasma CVD apparatus provided with a source gas supply nozzle and a plurality of oxidization gas supply nozzles for supplying an oxidizing gas into a film formation chamber, the source gas supply nozzle and the oxidization gas supply nozzle are placed above the oxidization gas supply nozzle. And the source gas supply nozzle is disposed below, and the source gas supply nozzle and the oxidizing gas supply nozzle are disposed alternately in the circumferential direction of the film forming chamber in plan view. I do.

Therefore, according to the plasma deposition method or the plasma CVD apparatus of the twelfth or thirteenth aspect, the source gas and the oxidizing gas are efficiently mixed in the center of the deposition chamber. This is effective in forming a uniform oxide film, and is also effective in suppressing hydrogen reduction deterioration since the reaction between hydrogen and oxygen in the gas phase can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a plasma CVD apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a graph showing a result of measuring a hydrogen ion current value while changing a gas mass flow ratio.

FIG. 4 is a graph showing the result of measuring the hydrogen content in the film while changing the gas mass flow ratio.

FIG. 5 is a graph showing the results of measuring the remanent polarization of a ferroelectric capacitor while changing the gas mass flow ratio.

FIG. 6 is a graph showing a result of measuring polarization with respect to an applied voltage of a ferroelectric capacitor before and after forming an oxide film by increasing a gas mass flow ratio by five times.

FIG. 7 is a graph showing a change in an ion current value when a high frequency power is changed.

FIG. 8 is a control sequence diagram when a protective film is not formed.

FIG. 9 is an explanatory diagram showing a film formation state based on the control sequence.

FIG. 10 is a control sequence diagram when a protective film is formed.

FIG. 11 is an explanatory diagram showing a film formation state based on the control sequence.

FIG. 12 is an explanatory diagram showing a structure of a ferroelectric capacitor and a state of a hydrogen ion attack.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 2 Container 3 Film-forming chamber 4 Ceiling plate 5 Substrate support 7 Substrate mounting part 8 Support shaft 10 Matching device 11 Capacitor 12 Bias power supply 13 Electrostatic power supply 14 Feeding antenna 15 Matching device 16 High frequency power supply 17 Source gas supply nozzle 18 Oxidizing gas supply nozzle 19, 20, 21 MFC 22 Exhaust port 24 Electromagnetic wave 25 Heater 26 Heater power supply 30 Controller 100 Substrate 101 Ferroelectric (PZT) 102 Pt electrode 103 Ferroelectric capacitor (PZT capacitor) 104 Gap 105 Oxide film 106 Oxidation Film 107 Protective film (oxide film)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masahiko Inoue 1-1-1, Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. 1-1-1 Wadazakicho Mitsubishi Heavy Industries, Ltd.Kobe Shipyard (72) Inventor Sadahiro Kishi 4-1-1, Kamioda, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Shinji Miyagaki Kanagawa Prefecture 4-1-1 Kamioda, Nakahara-ku, Kawasaki-shi F-term in Fujitsu Limited (reference) 4K030 AA06 AA14 AA24 BA35 BA42 BA44 EA06 FA04 HA01 JA05 JA06 JA10 JA16 JA18 KA20 LA01 LA15 5F045 AA08 AB31 AB32 AC00 AC01 AC11 AD05 AD06 BB04 DP04 EF02 EF04

Claims (13)

[Claims] 1. A high-frequency power is applied to a raw material gas and an oxidizing gas supplied under a low-pressure environment, and a plasma reaction for forming an oxide film on a substrate by utilizing a chemical reaction caused by the generated plasma. In the film method, a high-frequency power is applied for the purpose of sufficiently separating and decomposing the reducing gas in the raw material gas, and the amount of the oxidizing gas with respect to the raw material gas is further increased to a value higher than the high-frequency power required for film formation. A plasma reaction characterized by suppressing the reduction reaction deterioration of the element on the substrate by the reducing gas by reacting the oxidizing gas with the reducing gas generated by the decomposition of the raw material gas by making the amount larger than that required for the plasma. Film formation method. 2. The plasma film forming method according to claim 1, wherein a high frequency power of 500 W or more is applied per 100 SCCM total mass flow rate of the raw material gas and the oxidizing gas, and a mass flow ratio of the oxidizing gas to the raw material gas is adjusted. A plasma film forming method, wherein the oxide film is formed by setting the film forming temperature to at least three times and setting the film forming temperature range to 100 ° C. to 300 ° C. 3. A plasma film forming method according to claim 1 or 2, the frequency of the high frequency power, 400kH _Z ~3GH _Z
A plasma film forming method characterized by having the following range. 4. The method according to claim 1, wherein the source gas is SiH ₄ , the oxidizing gas is O ₂ , and the oxide film is SiO.
_X is a plasma deposition method. 5. The plasma film forming method according to claim 1, wherein the source gas is SiH ₄ , the oxidizing gas is N ₂ O, and the oxide film is Si.
Plasma film forming method which is a O _X N _y. 6. A high-frequency power is applied to a source gas and an oxidizing gas supplied under a low-pressure environment, and a plasma reaction for forming an oxide film on a substrate by utilizing a chemical reaction of the generated plasma. In the film method, an oxide film covering an element or the like on a substrate is formed without applying a bias for the purpose of attracting + ions to the substrate side, and this oxide film is used as a protective film against a hydrogen ion attack. After forming a protective film in the film forming step and the first film forming step, a bias is applied to the substrate side for the purpose of attracting + ions for sputter etching, and minute gaps between elements and between wirings are applied. A second film forming step of embedding an oxide film in the film. 7. The plasma film forming method according to claim 6, wherein after the oxide film is buried in the second film forming step, no bias is applied for the purpose of attracting + ions to the substrate side. And a third film forming step for further forming an oxide film. 8. The plasma deposition method according to claim 6, wherein the thickness of the protective film is 500 Å or more. 9. The plasma film forming method according to claim 6, 7 or 8, wherein the oxide film is formed based on the film forming conditions according to claim 1, 2, or 3. Film formation method. 10. The plasma film forming method according to claim 6, wherein the source gas is SiH ₄ , the oxidizing gas is O ₂ , and the oxide film is SiO.
_X is a plasma deposition method. 11. The plasma film forming method according to claim 6, wherein the source gas is SiH ₄ , the oxidizing gas is N ₂ O, and the oxide film is Si.
Plasma film forming method which is a O _X N _y. 12. The method of claim 1, 2, 3, 4, 5, 6, 7,
In the plasma film forming method described in 8, 9, 10, or 11, high frequency power is supplied from an upper portion of the film forming chamber into the film forming chamber by a power feeding antenna, and a plurality of source gas supply nozzles and a plurality of oxidizing gas supply nozzles are formed. The oxidizing gas supply nozzle is arranged so that the oxidizing gas supply nozzle is at the top, and the source gas supply nozzle is at the bottom. A plasma film forming method, wherein the source gas is supplied into the film forming chamber by the source gas supply nozzle, and the oxidizing gas is supplied into the film forming chamber by the oxidizing gas supply nozzle. 13. A film forming chamber, a feed antenna for supplying high frequency power from above the film forming chamber to the film forming chamber, a plurality of source gas supply nozzles for supplying a source gas into the film forming chamber,
In a plasma CVD apparatus provided with a plurality of oxidizing gas supply nozzles for supplying an oxidizing gas into a film forming chamber, a source gas supply nozzle and an oxidizing gas supply nozzle Plasma CVD, wherein the source gas supply nozzles and the oxidizing gas supply nozzles are alternately arranged in the circumferential direction of the film forming chamber in plan view.
apparatus.