JP2003142470A - Method and apparatus for depositing silicon nitride film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of depositing silicon nitride which can reduce the contamination of wafer with Al from a stage formed of an Al-group material. SOLUTION: First, a process for cleaning a silicon nitride film deposited on the internal wall of a chamber and a stage is performed (S201). Next, a process for covering the stage with the SiO2 film is performed (S202). In this process, SiH4 gas and N2 O gas are used and the stage is covered with the SiO2 film (S203). Subsequently, the wafer is carried into the chamber and then placed on the stage (S204). Thereafter, a process for depositing the silicon nitride film on the wafer is performed. In this process, N2 gas and the SiH4 gas are used. Moreover, a stage temperature is kept at 550 deg.C. Accordingly, the silicon nitride film is formed on the wafer. Finally, the wafer is carried out from the inside of the chamber 21a (S205).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deposition method and a deposition apparatus for depositing a silicon nitride film on a wafer.

[0002]

2. Description of the Related Art A plasma CV is used for depositing a silicon nitride film.
The D device is widely used. In the plasma CVD apparatus, since the stage is cleaned with a gas containing fluorine such as NF ₃ , it is made of an aluminum (Al) -based material having excellent fluorine resistance. As an Al-based material, alumina (Al ₂ O ₃ ) or aluminum nitride (Al
N) is selected.

[0003]

A large amount of hydrogen from raw material gases such as silane gas and ammonia is taken into the silicon nitride film deposited by the plasma CVD apparatus. For example, when hydrogen in the silicon nitride film diffuses into the gate oxide film, electron traps are formed in the gate oxide film, which may adversely affect the characteristics of the transistor. In order to reduce the hydrogen concentration in the silicon nitride film, it is advisable to increase the wafer temperature when depositing the silicon nitride film. However, according to the knowledge of the present inventor, when the stage is heated to a temperature of, for example, more than 500 ° C., sublimation of Al occurs and Al atoms are easily desorbed from the Al-based material. According to the experiment by the inventor, 1 × 1
It was found that as many as 0 ¹⁴ / cm ² or more of Al atoms are adsorbed on the back surface of the wafer placed on the stage.

When Al atoms are adsorbed on the back surface of the wafer, the following problems occur, for example, in the subsequent wet clean process. Since the wet clean process is performed in a batch process, Al atoms adsorbed on the back surface of the wafer are dissolved in the cleaning liquid, and the dissolved Al atoms are adsorbed on the surface of the wafer. When Al atoms are adsorbed on the wafer surface, the constituent elements of the semiconductor device such as a semiconductor integrated circuit formed on the wafer surface are contaminated with Al, which may adversely affect the circuit characteristics of the semiconductor device.

Al atoms from the stage of the plasma CVD apparatus can also be released into the chamber atmosphere during film formation. Such Al atoms are adsorbed on the wafer surface when the wafer is transferred into the chamber. This cause also causes the above-mentioned problem of contamination.

In order to solve such a problem, the present inventor tried to coat the stage with a silicon nitride film before transferring the wafer into the chamber. However, if the stage is covered with a silicon nitride film, A
The number of l atoms could not be reduced sufficiently. Therefore, the present inventor has earnestly studied and arrived at the present invention.

It is an object of the present invention to provide a silicon nitride film deposition method and deposition apparatus capable of reducing the contamination of a wafer by the constituent elements of the material forming the stage.

[0008]

A method for depositing a silicon nitride film according to the present invention is a method for depositing a silicon nitride film on a substrate, wherein (a) a stage in a chamber is covered with a silicon oxide film. And (b) mounting the substrate on the stage, and (c) depositing a silicon nitride film on the substrate. With this configuration, the stage is covered with the silicon oxide film before the substrate is placed on the stage.
Therefore, even if the constituent elements of the material forming the stage are detached from the stage, contamination of the back surface of the substrate with the constituent elements is reduced.

Further, it is preferable to further include a step of cleaning the inside of the chamber with a gas containing a fluorine element, prior to the above-mentioned coating step. By performing the cleaning step, among particles formed on the substrate, particles generated from the silicon nitride film deposited in the chamber can be reduced. Further, even if the material forming the stage is exposed on the surface of the stage by cleaning, since the stage is covered with the silicon oxide film after the cleaning step, the back surface of the substrate is a constituent element of the material forming the stage. The pollution by

Furthermore, it is preferable that silane gas and dinitrogen monoxide gas be used in the coating step. By using these gases, the stage can be surely covered with the silicon oxide film. Furthermore, it is advantageous if the stage is maintained at a temperature above 500 ° C. in the deposition step. With such a temperature, the hydrogen concentration in the silicon nitride film deposited on the substrate can be reduced. Moreover, even at such a temperature, since the stage is covered with the silicon oxide film, the back surface of the substrate is less contaminated with the constituent elements of the material forming the stage.

A silicon nitride film deposition apparatus according to one aspect of the present invention is a deposition apparatus in which a substrate is placed on a stage in a chamber and a silicon nitride film is deposited on the substrate. This apparatus includes (1) a stage on which a substrate is placed, (2) a temperature adjustment unit that adjusts the temperature of the stage, and (3) a substrate transfer unit that transfers the substrate into the chamber and places it on the stage. And (4) a gas supply unit for supplying a gas containing silicon, a gas containing an oxygen element, and a gas containing a nitrogen element into the chamber, and (5) controlling a temperature adjustment unit, a gas supply unit, and a substrate transfer unit. And a control unit for controlling. The control unit outputs (A) a command signal for operating the gas supply unit so that the gas containing silicon and the gas containing oxygen element are supplied into the chamber and the stage is covered with the silicon oxide film. Means and (B) second means for outputting a command signal for operating the substrate transfer unit so that the substrate is carried into the chamber and placed on the stage;
(C) A command signal for operating the gas supply unit and the temperature adjustment unit is output so that the gas containing silicon and the gas containing nitrogen element are supplied into the chamber and the silicon nitride film is deposited on the substrate. 3 means are included. According to such a deposition apparatus, the substrate is placed on the stage covered with the silicon oxide film, and the silicon nitride film is deposited on the substrate. Therefore, the back surface of the substrate is prevented from being contaminated with the constituent elements of the material forming the stage.

A silicon nitride film deposition apparatus according to another aspect of the present invention is a silicon nitride film deposition apparatus for depositing a silicon nitride film on a substrate, which is covered with a member made of silicon oxide. Of the silicon nitride film and the gas supply unit for supplying each of the gas containing silicon and the gas containing nitrogen element into the chamber at a predetermined flow rate, and controlling at least the gas supply unit to deposit a silicon nitride film on the substrate. Control unit to
Equipped with. The above member is preferably a silicon oxide film formed from a gas containing a silicon element and a gas containing an oxygen element. Further, the above member is preferably a plate that covers the stage. In the above deposition apparatus, the stage is covered with a member made of silicon oxide. Therefore, when the substrate is placed on the stage and the silicon nitride film is deposited on the substrate, the back surface of the substrate is less contaminated with the constituent elements of the material forming the stage.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a silicon nitride film deposition method and deposition apparatus according to the present invention will be described below with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

First, a preferred embodiment of a silicon nitride film deposition apparatus according to the present invention will be described. FIG. 1 is a schematic view showing a preferred embodiment of a silicon nitride film deposition apparatus according to the present invention. In FIG. 1, a plasma CVD apparatus 20
Are chambers 21a and 21b in which the wafer W is housed,
A gas supply source 23 for supplying a predetermined gas to the chambers 21a, 21b, a wafer transfer mechanism 24 for loading / unloading the wafers into / from the chambers 21a, 21b, and chambers 21a, 21b.
A high frequency power supply 25 for generating plasma inside, and an exhaust unit 26 for exhausting gas supplied to the chambers 21a and 21b.
And a control unit 27 for automatically controlling the procedure for forming the silicon nitride film.
With. The chambers 21a and 21b have substantially the same structure. When forming a silicon nitride film on a plurality of wafers, these two chambers 21a and 21b can be used simultaneously. In the following, for simplicity, the chamber 21a will be mainly described.

The chamber 21a is provided with a shower head 28 connected to the gas supply source 23 and a wafer support portion 29 on which the wafer W is placed. The shower head 28 and the wafer support portion 29 are arranged so as to face each other, as shown in the drawing. The shower head 28 has a hollow disk shape. Also, the shower head 28 is
The gas supply port 28a is provided at approximately the center of the upper wall. Further, the shower head 28 is provided with gas distribution plates 28b and 28c having a plurality of through holes. Gas is supplied from the gas supply source 23 to the shower head 28 through the gas supply port 28a. The gas supplied to the shower head 28 reaches the wafer through the through holes of the gas distribution plates 28b and 28c. Since the gas reaches the wafer through the plurality of through holes, it is uniformly distributed on the wafer surface.

The shower head 28 includes a high frequency power source 25.
Are connected. The high frequency power supply 25 supplies high frequency power having a frequency of 13.56 MHz to the shower head 28. That is, the shower head 28 includes a gas distributor that evenly distributes the gas supplied from the gas supply source 23 on the wafer W, and the high frequency power supply 25.
It also serves as an electrode to which higher-frequency power is supplied.

The gas supply source 23 is configured to supply silane (SiH ₄ ) gas, ammonia (NH ₃ ) gas, dinitrogen monoxide (N ₂ O) gas, and nitrogen (N ₂ ) gas to the chamber 21a. ing. Further, from the gas supply source 23, nitrogen trifluoride (NF ₃ ) gas and argon (Ar) gas are also supplied to the chamber 21a. The gas supply 23 includes
A flow rate adjusting unit 23a that adjusts the flow rate of each gas is provided. The flow rate adjusting unit 23a can include, for example, a mass flow controller (MFC) or an air-operated valve (AV). The flow rate adjusting unit 23a operates the MFC and AV based on the command signal from the control unit 27 and supplies a predetermined gas to the chamber 21a at an appropriate flow rate. Flow rate adjusting unit 23a
A microwave chamber 31 provided with a microwave generation source 30 is provided between the microwave chamber 31 and the chamber 21a. The microwave generation source 30 and the microwave chamber 31 are used in the cleaning process as described later.

The wafer support 29 is provided in the chamber 21a in an airtight manner and is vertically movable by a movable mechanism (not shown). By vertically moving the wafer support portion 29, the distance between the wafer W and the shower head 28 is arbitrarily adjusted. The wafer supporting unit 29 has a disc-shaped stage 29a made of AlN and a substantially columnar holding unit 29b for holding the stage 29a. Stage 29
A heater 29c is built in a. The heater 29c is connected to a temperature adjusting unit 32 that also serves as a power supply source. Electric power appropriately controlled by the temperature adjusting unit 32 is supplied to the heater 29c, and the stage 29a is maintained at a predetermined temperature.

An exhaust port 22 is provided in the chamber 21a. The gas supplied to the chamber 21a is exhausted by the exhaust unit 26 through the exhaust port 22. Also,
Between the chamber 21 a and the exhaust unit 26, the chamber 21 a
A pressure adjusting unit 33 that adjusts the internal pressure is provided.
The pressure adjusting unit 33 can include, for example, a throttle valve. When adjusting the pressure, the pressure in the chamber 21a is monitored by the pressure gauge 34 provided in the chamber 21a.

Next, the wafer transfer section 24 will be described. FIG. 2 is a schematic view of the plasma CVD apparatus 1 viewed from an angle different from that of FIG. As shown in FIG. 2, the wafer transfer unit 24 has a transfer chamber 24a, a transfer robot 24b provided in the transfer chamber 24a, and a drive unit 24c for operating the transfer robot 24a. The wafer transfer unit 24 is in contact with the chamber 21a via the gate valve G. Further, the drive unit 24c is connected to the control unit 27. Control unit 27
When a command signal is output from the drive unit 24c to the drive unit 24c, the drive unit 24c drives the transport robot 24a according to the command signal. As a result of driving the transfer robot 24a, for example,
The wafer is loaded into the chamber 21a and the stage 29a
Placed on top. The gate valve G is opened and closed by the drive unit 2
4c can be controlled.

The control unit 27 includes a CPU 27a and a memory 2
7b. The memory 27b stores a program for managing the procedure for forming the silicon nitride film of this embodiment. This program may have a sub-program that can realize a step of cleaning the inside of the chamber 21a, a step of covering the stage 29a with a SiO ₂ film, a step of loading the wafer W, and a step of forming a silicon nitride film. it can. That is, the memory 27b is provided with storage means for storing the subprogram. Also, CP
U27a can execute the program stored in the memory 27b. The control unit 27 includes a gas supply source 23 and a high frequency power source 2
5, the temperature adjustment unit 32, the microwave generation source 30, and the pressure adjustment unit 33 are connected via a control line. On the other hand, the controller 27 outputs a command signal to realize the above steps.

As shown in FIG. 4, the control unit 27 has at least five means called first means 271 to fifth means 275. The first means 271 is the gas supply unit 23.
On the other hand, a command signal for coating the stage 29a with a SiO ₂ film is output. The gas supply unit 23 operates according to this command signal. The operation of the gas supply unit 23 is (1) SiH
Starting the supply of ₄ gas and N ₂ O gas into the chamber, (2) adjusting the flow rates of these gases to predetermined values, and (3) stopping the supply of these gases. Can be included. The first means 271 can also output a command signal for coating the stage 29a with the SiO ₂ film to the high frequency power supply 25, the pressure adjusting unit 33, and the temperature adjusting unit 32. The high frequency power supply 25 can supply high frequency power to the shower head 28 according to the command signal. The pressure adjusting unit 33 can adjust the pressure inside the chamber 21a to a predetermined value according to the command signal. Further, the temperature adjusting unit 32 can also maintain the temperature of the stage 29a at a predetermined value according to the command signal. Each of the above-mentioned adjustment units or power supplies is the first means 271.
The stage 29a is covered with the SiO ₂ film by operating in accordance with the command signal from.

Further, the second means 272 outputs a command signal to the wafer transfer section 24 for transferring the wafer into the chamber 21a and mounting it on the stage 29a. According to this command signal, the wafer transfer unit 24 places the wafer on the stage.

The third means 273 outputs a command signal for depositing a silicon nitride film on the wafer to the gas supply section 23 and the temperature adjusting section 32. The gas supply unit 23
It operates according to this command signal. The operation of the gas supply unit 23 is (1) starting supply of SiH ₄ gas and N ₂ gas into the chamber, (2) adjusting the flow rates of these gases to predetermined values, and (3 ) It may include stopping the supply of these gases. In addition, the temperature adjustment unit 32
Operates according to the command signal and can maintain the stage 29a at a temperature of 550 ° C., for example. The third means 273 further includes the high frequency power supply 25 and the pressure adjusting unit 3.
A command signal is also output to 3. The high frequency power supply 25 is
High frequency power can be supplied to the shower head 28 according to the command signal. The pressure adjusting unit 33 can adjust the pressure inside the chamber 21a to a predetermined value according to the command signal. A silicon nitride film is deposited on the wafer by the operation of these adjusting units or power supplies.

Further, the fourth means 274 outputs a command signal for cleaning the inside of the chamber using a gas containing a fluorine element to at least the gas supply unit 23 and the microwave generation source 30. The gas supply unit 23 and the microwave generation source 30 operate according to the command signal, activate the gas containing the fluorine element by the microwave, and supply the gas into the chamber 21a. The third means 273 also outputs a command signal to the pressure adjusting unit 33 and the temperature adjusting unit 32, and the pressure adjusting unit 33 and the temperature adjusting unit 32 operate according to this command signal. By these operations, the inside of the chamber 21a is cleaned.

Further, the fifth means 275 includes first to fourth means.
The means 271 to 274 of the first means 271 to the fourth
Output a control signal for controlling 274 of. This control signal controls, for example, the timing of each command signal output from the first to fourth means 271 to 274. By the function of the fifth means, a step of cleaning the inside of the chamber 21a, a step of coating the stage 29a with a SiO ₂ film,
The step of loading the wafer W and the step of forming the silicon nitride film are sequentially performed. Further, after each of these steps is sequentially performed, each step may be performed again in the same order.

Next, a preferred embodiment of the method for depositing a silicon nitride film according to the present invention will be described. In this embodiment, the plasma CVD device 20 is used. Figure 3
FIG. 4 is a flow diagram illustrating a method for depositing a silicon nitride film according to this embodiment.

(Cleaning Step) The wafer is the chamber 2
The cleaning step is performed before the sheet is loaded into the la 1a. This cleaning process is performed to remove the silicon nitride film deposited on the inner wall of the chamber 21a and the stage 29a. The cleaning process can include a plurality of sub-processes. Hereinafter, a case including two sub-steps will be described. First, in the first sub-step, only Ar gas is used. Ar gas is activated by microwaves in the microwave chamber 31 and introduced into the chamber 21a. The silicon nitride film is removed by the activated Ar gas. The silicon nitride film left unremoved in the first sub-step is removed in the second sub-step. In the second sub-step, not only Ar gas but also NF ₃ gas is used. These gases are activated by microwaves in the microwave chamber 31 and introduced into the chamber 21a. The silicon nitride film is sufficiently removed by the activated NF ₃ gas. Therefore, particles caused by the silicon nitride film deposited on the inner wall of the chamber 21a and the stage 29a are reduced.

The main conditions of the first sub-process are exemplified below.・ Ar gas supply: 2800 sccm ・ Chamber pressure: 5.3 × 10 ² Pa ・ Microwave power: 1 W ・ Stage temperature: 550 ° C. ・ Cleaning time: 4 seconds Also, the main condition of the first sub-step is , Can be as follows:・ Ar gas supply: 2800 sccm ・ NF ₃ gas supply: 1400 sccm ・ Chamber pressure: 5.3 × 10 ² Pa ・ Microwave power: 1 W ・ Stage temperature: 550 ° C ・ Cleaning time: 20 seconds or more The cleaning process ends (S201).

(SiO ₂ Film Covering Step) Subsequent to the cleaning step, the stage 29a is covered with silicon oxide (SiO ₂ )
The step of coating with a film is performed. This step is performed by the control unit 2
CPU 27 is a subprogram included in the memory 27b of No. 7
a can be performed and implemented. After cleaning, silane (SiH ₄ ) gas and dinitrogen monoxide (N
₂ O) gas is supplied into the chamber 21a, and the inside of the chamber 21a is adjusted to a predetermined pressure. Examples of conditions such as gas supply amount and pressure are as follows. · SiH ₄ gas: 260sccm · N ₂ O gas: 3900sccm.・ Chamber pressure: 3.6 × 10 ² Pa ・ Stage temperature: 550 ° C

After the flow rate of each gas and the pressure inside the chamber 21a are stabilized, a high frequency power of, for example, 300 W is supplied from the high frequency power supply 25 to the shower head 28. Plasma is generated inside the chamber 21a by the high frequency power, the SiH ₄ gas and the N ₂ O gas are decomposed by the plasma, and the SiO ₂ film is deposited on the stage 29a. The SiO ₂ film is deposited not only on the surface of the stage 29a but also on the side surfaces thereof. Further, the SiO ₂ film is used not only on the surface and side surface of the stage 29a,
It is also deposited on the back surface of a. In this way, stage 2
9a is covered with a SiO ₂ film. After the deposition is performed for a predetermined time and the SiO ₂ film has an appropriate thickness, the high frequency power supply is stopped and the supply of each gas is stopped. With the above procedure, the step of covering the stage 29a with the SiO ₂ film is completed (S202).

(Wafer Loading Step) Subsequently, the wafer W is loaded into the chamber 21a. Plasma CV for loading
A wafer transfer mechanism (not shown) provided in the D device 20 is used. The wafer transfer mechanism operates according to a subprogram for loading the wafer, which is stored in the controller 27, and places the wafer W on the stage 29a (S20).
3).

(Step of Depositing Silicon Nitride Film) Next, the wafer W
A step of depositing a silicon nitride film thereon is performed. Examples of conditions in this step are as follows.・ N ₂ gas supply amount: 9000 sccm ・ SiH ₄ gas supply amount: 100 sccm ・ Chamber pressure: 8.0 × 10 ² Pa ・ Stage temperature: 550 ° C. ・ High-frequency power: 423 W A silicon oxide film is formed. After the thickness of the silicon nitride film on the wafer W reaches a desired value, the supply of high frequency power is stopped and the supply of N ₂ gas and SiH ₄ gas is stopped to form a silicon nitride film. To finish. With the above, the silicon nitride film deposition step is completed (S204).

(Wafer Unloading Step) After the silicon nitride film deposition step is completed, the wafer W is unloaded from the chamber 21a. Similar to the wafer loading process, a wafer transport mechanism (not shown) is used for unloading (S205). Thus, the deposition method for depositing the silicon nitride film on the wafer W is completed.

In the method for depositing a silicon nitride film of this embodiment, after the stage 29a is covered with the SiO ₂ film,
A wafer is placed on the stage 29a, and a silicon nitride film is deposited on the wafer. During the above steps, the stage 29a is heated to 550 ° C. When AlN forming the stage 29a is heated to such a temperature, AlN is converted to Al.
The atoms are detached. However, the stage 29a is
Since it is covered with the iO ₂ film, contamination of the back surface of the wafer with Al is reduced. Further, the number of Al atoms released to the atmosphere inside the chamber 21a is also reduced.

According to the research results of the present inventor, stage 2
Compared with the case where 9a is covered with a silicon nitride film, the SiO ₂ film can reduce the contamination with Al. The present inventor estimates the reason for this, although not limited thereto, as follows. It is estimated that Al becomes ions such as Al ^{3+ and} is desorbed from the stage 29a.
The Al ions desorbed from the stage 29a are transferred to the stage 29
It diffuses in the SiO ₂ film covering a. At this time, Al
Ions, for easy compound and oxygen atoms in the SiO ₂ film, and captured in the SiO ₂ film. Therefore,
Most of Al ions cannot reach the back surface of the wafer W. Further, during the cleaning process, the atmosphere in the chamber is an oxidizing atmosphere containing a large number of oxygen molecular species activated by plasma. Therefore, the chamber 21
The Al ions released into the atmosphere in a are easily oxidized. This oxidation produces an Al oxide such as Al ₂ O ₃ . Since Al oxide is more stable than Al alone, the contamination of the wafer by Al is reduced. That is, since Al ions are easily combined with oxygen atoms, if the stage 29a is covered with a SiO ₂ film, Al contamination by Al can be reduced as compared with the case where the stage 29a is covered with a silicon nitride film.

The present inventor has also found that the plasma CVD apparatus 2
Instead of the stage 29a of 0, the surface is several μm
It is speculated that an AlN stage coated with a SiO ₂ film of about 100 μm thick may be used. With the plasma CVD apparatus having such a stage, after the cleaning step, the wafer is loaded without performing the SiO ₂ film coating step,
A silicon nitride film may be deposited on the wafer. Since the AlN stage is covered with the SiO ₂ film, the Al on the backside of the wafer
Pollution is reduced. Moreover, since it is not necessary to perform the SiO ₂ film coating step every time, the throughput can be improved.
However, when the cleaning process is performed, the SiO ₂ film is also etched and the thickness thereof is reduced. Therefore, Si
When the thickness of the O ₂ film is reduced to a predetermined value, the stage needs to be replaced. Also, instead of replacing, Si
The SiO ₂ film may be appropriately deposited when the thickness of the O ₂ film is reduced to a predetermined value. Further, even if the stage 29a is covered with, for example, a SiO ₂ plate instead of coating the AlN stage with a SiO ₂ film to a thickness of several μm, the Al contamination on the back surface of the wafer from the stage 29a can be reduced. Expects.

(Example) As an example, the present inventor
By the method for depositing a silicon nitride film according to the embodiment,
The film was deposited. That is, as described above,
Process, SiO ₂Film coating process, wafer loading process, chipping
The silicon film deposition step and the wafer unloading step were sequentially performed.
SiO₂In the film coating process, SiO₂Set the film deposition time to 1
0 seconds, about 170 nm of SiO on the stage 29a₂film
Was deposited. Also, in the embodiment, the bare made of silicon is used.
A wafer was used. For convenience of explanation, in the examples,
A wafer on which a silicon oxide film is deposited is called wafer A.

Comparative Example As a comparative example, the present inventor tried to cover the stage 29a with a silicon nitride film instead of the SiO ₂ film. That is, after the cleaning step, N ₂ gas and SiH ₄ gas were supplied into the chamber, and high frequency power was supplied to the shower head to cover the stage 29a with a silicon nitride film. At this time, the deposition time was set to 30 seconds, and a silicon nitride film having a thickness of about 350 nm was deposited. Then, the wafer loading process, the silicon nitride film, and the wafer unloading process were performed according to the same procedure and conditions as in the example. The wafer on which the silicon nitride film is deposited in this manner is referred to as wafer B.

For further comparison, the stage 29a
The procedure and conditions for depositing the silicon nitride film on the wafer B were the same except that the thickness of the silicon nitride film covering the film was 700 nm, and the silicon nitride film was deposited on the wafer.
This wafer is called wafer C.

Further, the present inventors set the temperature of the stage 29a to 400 ° C. instead of 550 ° C., and deposited the silicon nitride film under the same procedure and conditions as the wafer B. The wafer thus obtained is called wafer D.

(Evaluation Results of Examples and Comparative Examples) Inductively Coupled Plasm
a Spectrometry: ICP spectroscopy)
The concentration of Al atoms adsorbed on the back surface of D was measured. The result is shown in FIG. FIG. 5 shows an IC for each of the wafers A to D.
It is a table which shows a P spectroscopy analysis result. From the result of wafer D,
When the stage temperature is 400 ° C., even if the stage is covered with a silicon nitride film, the concentration of Al atoms adsorbed on the back surface of the wafer can be suppressed to a low value of about 2 × 10 ¹¹ / cm ² . However, as can be seen from the result of the wafer B, the concentration of Al atoms increases to about 2.5 × 10 ¹² atoms / cm ² at 550 ° C., which is suitable for depositing the silicon nitride film. Also,
Comparing the results of wafer B and wafer C, even if the thickness of the silicon nitride film covering the stage is 350 nm, it is 70
It can be seen that there is no change in the concentration of Al atoms adsorbed on the back surface of the wafer even at 0 nm.

However, in the wafer A according to the embodiment, the stage temperature is 550 ° C., and the thickness of the silicon oxide film coating the stage 29a is only 17 degrees.
Even if it is 0 nm, the Al atom concentration on the back surface of the wafer is about 1 ×.
It can be reduced to 10 ¹² pieces / cm ² . From the above results,
The effect of the silicon nitride film deposition method according to the embodiment is understood.

Although the method and apparatus for depositing a silicon nitride film according to the present invention have been described above with reference to the embodiments and examples, the present invention is not limited to this and various modifications are possible. Is. For example, stage 2
9a may be composed of not only AlN but also other Al-based materials. Al-based materials include AlN and A
There are materials such as l ₂ O ₃ , mullite (3Al ₂ O ₃ .2SiO ₂ ) or spinel (MgO.Al ₂ O ₃ ). Also, in the cleaning process, NF ₃ gas is added to the chamber 2.
1a, and high frequency power may be applied to the shower head 28 to clean the inside of the chamber 21a.

[0045]

As described above, in the method and apparatus for depositing a silicon nitride film according to the present invention, the stage is covered with the silicon oxide film before the wafer is placed on the stage. Therefore, according to the present invention, there is provided a silicon nitride film deposition method and deposition apparatus capable of reducing the contamination of the wafer by the constituent elements of the material forming the stage.

[Brief description of drawings]

FIG. 1 is a schematic view showing a preferred embodiment of an apparatus for depositing a silicon nitride film according to the present invention.

FIG. 2 is a schematic view of the deposition apparatus shown in FIG. 1 as seen from another angle.

FIG. 3 is a flowchart illustrating a method for depositing a silicon nitride film according to this embodiment.

FIG. 4 is a schematic diagram showing an example of a configuration of a control unit.

FIG. 5 is a diagram showing ICP spectroscopic analysis results for each wafer.

[Explanation of symbols]

20 ... Plasma CVD apparatus, 21a, 21b ... Chamber, 22 ... Exhaust port, 23 ... Gas supply source, 23a ... Flow rate adjusting section, 25 ... High frequency power source, 26 ... Exhaust section, 27 ... Control section, 27a ... CPU, 27b ... Memory, 28 ... Shower head, 28a ... Gas supply port, 28b, 28c ... Gas distribution plate, 29 ... Wafer support part, 29a ... Stage, 29b
... holding part, 29c ... heater, 30 ... microwave source,
31 ... Microwave chamber, 32 ... Temperature control unit, 33 ...
Pressure adjusting unit, 34 ... Pressure gauge, W ... Wafer.

Continued front page    (72) Inventor Yoichi Suzuki             14-3 Shinizumi, Narita City, Chiba Prefecture Nogedaira Industrial Park               Applied Materials Japan Co., Ltd.             Inside the company F-term (reference) 4K030 AA01 AA04 AA06 BA40 BA44                       DA06 JA10 KA41 KA47                 5F045 AA09 AB32 AB33 AC01 AC12                       AC15 AC16 AD09 AE21 BB14                       DP03 EB02 HA01                 5F058 BC08 BE10 BF08

Claims (8)

[Claims] 1. A method for depositing a silicon nitride film on a substrate, comprising: coating a stage in a chamber with a silicon oxide film; mounting the substrate on the stage; and depositing the substrate on the substrate. And a step of depositing a silicon nitride film. 2. The method for depositing a silicon nitride film according to claim 1, further comprising a step of cleaning the inside of the chamber with a gas containing a fluorine element prior to the covering step. 3. The method for depositing a silicon nitride film according to claim 1, wherein a silane gas and a dinitrogen monoxide gas are used in the coating step. 4. The process of claim 1, wherein the stage is maintained at a temperature above 500 ° C.
The method for depositing a silicon nitride film according to any one of 1. 5. A substrate is placed on a stage in the chamber,
A deposition apparatus for depositing a silicon nitride film on the substrate, comprising: a stage on which the substrate is placed; a temperature adjusting unit for adjusting the temperature of the stage; and a stage for transferring the substrate into the chamber. A substrate transfer part to be placed on the above, a gas supply part for supplying a gas containing a silicon element, a gas containing an oxygen element, and a gas containing a nitrogen element into the chamber, the temperature adjusting part, the gas supply part, And a control unit that controls the substrate transfer unit, wherein the control unit supplies the gas containing the silicon element and the gas containing the oxygen element into the chamber to cover the stage with a silicon oxide film. And a first means for outputting a command signal for operating the gas supply unit, and operating the substrate transfer unit so that the substrate is loaded into the chamber and placed on the stage. Second means for outputting a command signal to supply the gas so that the gas containing the silicon element and the gas containing the nitrogen element are supplied into the chamber to deposit a silicon nitride film on the substrate. Section and third means for outputting a command signal for operating the temperature adjusting section,
Deposition equipment. 6. A deposition apparatus for depositing a silicon nitride film on a substrate, comprising: a stage covered with a member made of silicon oxide; and a gas containing a silicon element and a gas containing a nitrogen element in the chamber. And a gas supply unit for supplying the gas containing the silicon element and the gas containing the nitrogen element into the chamber to deposit a silicon nitride film on the substrate. And a control unit including a unit that outputs a command signal for operating the adjustment unit. 7. The member is a silicon oxide film formed from a gas containing a silicon element and a gas containing an oxygen element,
The deposition apparatus according to claim 6. 8. The deposition apparatus according to claim 6, wherein the member is a plate that covers the stage.