JP2006339523A - Cleaning method for semiconductor processing apparatus and etching method for high dielectric constant oxide film - Google Patents

Abstract

When cleaning a deposit made of a high dielectric constant oxide deposited in a chamber of a semiconductor processing apparatus or etching a high dielectric constant oxide film formed on a substrate, the deposit or the high dielectric constant oxidation is performed. The film can be efficiently removed or etched, and deterioration of members constituting the remote plasma generator can be suppressed.
At least one of a non-reactive gas such as argon, an oxygen atom supply gas such as oxygen, and an oxidizing gas such as nitrogen oxide is activated in a remote plasma generator 12 to obtain a gas containing active species. This gas is introduced into the chamber 1 together with a halogen-based gas such as boron trichloride.
[Selection] Figure 1

Description

  The present invention relates to a method for cleaning a chamber of a semiconductor processing apparatus for forming a high dielectric constant oxide film and a method for etching a high dielectric constant film on a silicon substrate.

An attempt has been made to reduce the driving current by using a high dielectric constant film having a higher relative dielectric constant than a conventional silicon oxide film as a gate insulating film of a field effect transistor, and reducing the thickness of the gate insulating film. .
Specifically, SiON has been widely used as such a gate insulating film. However, miniaturization of device processing size is progressing for higher performance of transistors, and accordingly, the thickness of the gate insulating film is reduced. At present, the thickness of the gate insulating film is several nanometers or less, which is a limit film thickness that maintains the insulating property. Recently, examples of high-permittivity insulating films that are effective include those containing hafnium such as HfO ₂ , HfSi _x O _y , HfAl _x O _y , and HfSiAl _y O _z .

  These high dielectric constant films are formed on the substrate by chemical vapor deposition (CVD), atomic layer deposition (ALD), or the like. However, it is sufficient that a high dielectric constant film is formed only on a substrate disposed at a predetermined position in a chamber of a semiconductor processing apparatus. Actually, however, the inner wall surface of the chamber or the periphery of a substrate holder on which the substrate is placed, etc. High dielectric constant film adheres or deposits.

As a result, the deposits are peeled off by rolling up due to gas flow or the like and become particles, which adheres to the substrate during film formation, leading to defects in the device product or failure of the semiconductor device.
For this reason, the chamber of the semiconductor processing apparatus must be periodically cleaned.

As a cleaning method for this purpose, there is a method of scraping off deposits, which is not preferable because it takes time and labor and may damage the inner wall surface of the chamber.
Japanese Patent Application Laid-Open No. 2004-146787 discloses the following chamber cleaning method.

That is, in this prior invention, a remote plasma generator is placed at a position away from the chamber of the semiconductor processing apparatus, and an oxygen atom supply gas such as O ₂ and a chlorine-based gas such as BCl ₃ are introduced into the remote plasma generator. In this method, active species are generated by plasma, and a gas containing the active species is sent into the chamber to remove deposits adhering to the chamber.

However, there is a problem that the active species generated in the remote plasma generator are inactivated until the active species arrive in the chamber, the active species are reduced, and the deposit removal efficiency is insufficient.
In addition, since the chlorine-based gas is introduced into the remote plasma generator and activated, members such as a reaction tube of the remote plasma generator may be deteriorated by the active species of the chlorine-based gas.

On the other hand, when etching a high dielectric constant oxide film formed on a substrate, oxygen atom supply gas such as O ₂ and chlorine gas such as BCl ₃ are introduced into the remote plasma generator, Active species are generated, and a gas containing the active species is sent into the chamber to etch the high dielectric constant oxide film. In this case as well, the etching efficiency is insufficient and the remote plasma generator may be deteriorated. there were.
JP 2004-146787 A

  Therefore, an object of the present invention is to remove deposits when cleaning deposits made of high dielectric constant oxide deposited in a chamber of a semiconductor processing apparatus or etching a high dielectric constant oxide film formed on a substrate. Alternatively, the high dielectric constant oxide film can be efficiently removed or etched, and deterioration of members constituting the remote plasma generator can be suppressed.

To solve this problem,
The invention according to claim 1 is a cleaning method for removing deposits made of a high dielectric constant oxide generated in a chamber of a semiconductor processing apparatus.
It is characterized in that at least one of a non-reactive gas, an oxygen atom supply gas and an oxidizing gas is activated in a remote plasma generator to be a gas containing active species, and this gas is introduced into a chamber together with a halogen-based gas. A method for cleaning a semiconductor processing apparatus.

According to a second aspect of the present invention, there is provided a cleaning method for a semiconductor processing apparatus according to the first aspect, wherein a gas containing active species and a halogen-based gas are mixed and introduced into the chamber.
According to a third aspect of the present invention, there is provided the semiconductor processing apparatus cleaning method according to the first aspect, wherein the gas containing the active species and the halogen-based gas are separately introduced into the chamber.

  According to a fourth aspect of the present invention, there is provided the semiconductor processing apparatus cleaning method according to the first aspect, wherein the semiconductor processing apparatus is formed by a CVD method or an atomic layer deposition method. It is.

The invention according to claim 5 is a method for etching a high dielectric constant oxide film formed on a substrate.
It is characterized in that at least one of a non-reactive gas, an oxygen atom supply gas and an oxidizing gas is activated in a remote plasma generator to be a gas containing active species, and this gas is introduced into a chamber together with a halogen-based gas. This is a method for etching a high dielectric constant oxide film.

The invention according to claim 6 is the method for etching a high dielectric constant oxide film according to claim 5, wherein a gas containing active species and a halogen-based gas are mixed and introduced into the chamber.
The invention according to claim 7 is the method of etching a high dielectric constant oxide film according to claim 5, wherein the gas containing the active species and the halogen-based gas are separately introduced into the chamber.

  According to an eighth aspect of the present invention, in the semiconductor processing apparatus, the high dielectric constant oxide film according to the fifth aspect is formed by a CVD method or an atomic layer deposition method. This is an etching method.

  In the present invention, an active species having a long active life is generated by introducing any one of a non-reactive gas, an oxygen atom supply gas, and an oxidizing gas into the remote plasma generator. For this reason, the decrease in activity during the introduction of the active species having a long active lifetime into the chamber is reduced. Then, in the chamber or immediately before it, the halogen-based gas is activated in contact with the halogen-based gas in a highly active state, and the deposit or the oxide film comes into contact with the active species at a high concentration. Therefore, the deposit cleaning or etching can be efficiently performed.

  Furthermore, since no halogen-based gas is introduced into the remote plasma generator, the components of the remote plasma generator are not deteriorated.

FIG. 1 shows an example of an apparatus used in the cleaning method of the present invention. In FIG. 1, reference numeral 1 denotes a chamber (reaction chamber) of a semiconductor processing apparatus.
A susceptor 3 that is rotated by a rotating shaft 2 is provided in the chamber 1, and a wafer tray 4 is provided on the susceptor 3. A substrate 5 such as silicon is placed on the wafer tray 4. A heater 6 is built in the susceptor 3 so that the substrate 5 is heated to a predetermined temperature.

  In the upper part of the chamber 1, a supply unit 7 is provided for sending a film forming gas, a gas containing active species, and a halogen-based gas into the chamber 1. The supply unit 7 includes a supply port 8 having a shape expanding in a trumpet shape so that these gases are uniformly fed into the chamber 1.

Further, one end of a tube 9 is connected to the side wall of the chamber 1, and the other end is connected to a halogen-based gas supply source 10, so that the halogen-based gas from the halogen gas supply source 10 is sent into the chamber 1. ing.
One end of a tube 11 is connected to the supply unit 7, and the other end is connected to a remote plasma generator 12.

  The remote plasma generator 12 is supplied with a non-reactive gas, an oxygen atom donating gas, and an oxidizing gas from an excitation gas supply source 13 through a tube 14 where plasma is excited to generate active species. A gas containing active species flows through the tube 11 into the chamber 1.

  As the remote plasma generator 12, for example, one disclosed in Japanese Patent Application Laid-Open No. 2004-165345 is used. For example, a discharge tube in which a high frequency coil is wound around the outer periphery of a ceramic reaction tube is used. For example, an excited gas is allowed to flow, high frequency power is applied to a high frequency coil, and plasma is generated in a reaction tube to generate active species.

Further, a film forming gas supply source 16 is connected to the supply unit 7 of the chamber 1 via a pipe 15, and a film forming gas supplied from the film forming gas supply source 16 is sent into the chamber 1. It is like that.
The chamber 1 is connected to an exhaust device (not shown) for maintaining the internal pressure at a predetermined pressure.

Next, a cleaning method using this apparatus will be described.
Prior to cleaning, a high dielectric constant oxide film is formed on the substrate 5. This oxide film is formed by a CVD method or an ALD method (atomic layer deposition method).
In the CVD method, the substrate 5 is heated to 450 to 600 ° C., for example, and a source gas such as Hf (DPM) ₄ , Hf (MMP) ₄ , argon, and oxygen are supplied from the film forming gas supply source 16 to a predetermined pressure. Then, it is introduced into the chamber 1 and an oxide film such as HfO ₂ is formed by a CVD reaction.

In the ALD method, the substrate 5 is heated to 350 to 500 ° C., for example, and a trace amount of hydrolyzable hafnium compound such as [(CH ₃ ) ₂ N] Hf and HfCl ₄ and water is supplied from the film forming gas supply source 16. The film is alternately supplied into the chamber 1 one by one to form one atomic layer. During this film formation, an oxide film is simultaneously deposited as an deposit on the inner wall portion of the chamber 1, the wafer tray 4, and the like.

The high dielectric constant oxide forming this deposit is, for example, HfO ₂ , ZrO ₂ , Al ₂ O ₃ , HfSi _x O _y , HfAl _x O _y , ZrSi _x O _y , ZrAl _x O _y (where, x, y Is a number greater than 0) and nitrogen content of these compounds (eg HfO _x N _y , HfSi _x O _y N _z , HfAl _x O _y N _z ) (where x, y, z are numbers greater than 0) These oxides are also formed on the substrate 5 as an insulating film.

Next, the substrate 5 is taken out of the chamber 1 and the deposits are cleaned.
First, non-reactive gas (Ar, N ₂ , He, Kr, Xe), oxygen atom donating gas (O ₂ , O ₃ , H ₂ O, H ₂ O ₂ , CO _x , SO _{x, NO x),} oxidizing gas _(NF 3, _{N 2} O, etc.) (wherein, X is a number greater than 0) of at least one or two or more kinds of mixed gas remote plasma generator via a tube 14 It is sent to the device 12 to generate active species. This active species has a long active lifetime, and is less likely to be deactivated while being sent to the chamber 1.

The gas containing the active species is sent into the chamber 1 from the tube 11, and at the same time, BCl ₃ , HCl, Cl ₂ , SiCl ₄ , HBr, BBr, Br from the halogen-based gas supply source 10 through the tube 9. _A halogen-based gas composed of at least one kind or two or more kinds of mixed gases is fed into the chamber 1.

  In the chamber 1, the active species from the remote plasma generator 12 react with the halogen-based gas, the halogen-based gas is activated to become an active species, and the active species of the halogen-based gas immediately react with the deposit, and the deposit As a volatile compound. This volatile compound is discharged out of the system. At this time, the reaction may be accelerated by heating the chamber 1.

By the way, the active species of the halogen-based gas reacts well with the high dielectric constant oxide to form a volatile compound and exhibits a good cleaning effect, but has a short active life.
For this reason, in the cleaning method of the present invention, active species of a halogen-based gas having a short active lifetime is generated in the chamber 1 (in-situ) so that the activity is effectively used.

In addition, non-reactive gas, oxygen atom donating gas, oxidizing gas supplied to the remote plasma generator, and CF gas such as CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₆ , A PFC gas of ClF ₃ , F ₂ , SF ₆ , COF ₂ can also be added.
In particular, by adding these gases, it becomes very effective for cleaning and etching of high dielectric constant oxide films containing silicon such as HfSi _x O _y , ZrSi _x O _y , and these nitrogen-containing compounds.

FIG. 2 shows another example of an apparatus used in the cleaning method of the present invention. The same components as those shown in FIG.
In this example, a tube 9 for flowing a halogen-based gas from a halogen-based gas supply source 10 is connected in the middle of a tube 11 for flowing a gas containing active species from a remote plasma generator 12, and after both are joined, The point of introduction into the chamber 1 is different from the previous example.

  In this case, it goes without saying that the joining point is preferably close to the supply unit of the chamber 1, and the supply unit 7 may join.

  The etching method of the present invention is basically the same as the above-described cleaning method. After a high dielectric constant oxide film is formed on the substrate 5 by the CVD method or the ALD method, a predetermined pattern is formed on the substrate 5. The drawn resist film is formed, and the same operation is performed using this resist film as an etching mask.

Specific examples are shown below.
(Example 1)
The cleaning effect was confirmed using the apparatus shown in FIG.
A silicon substrate 5 on which an HfO 2 film was formed was placed in the chamber 1. Oxygen was introduced into the remote plasma generator 12 as an oxygen atom donating gas, high frequency power with a frequency of 2.45 GHz and 600 W was applied to generate oxygen plasma, and flowed into the chamber 1. BCl ₃ was allowed to flow from the tube 9 as a halogen-based gas, joined with oxygen plasma, and introduced into the chamber 1.

The pressure in the chamber 1 was 5 mmTorr, the temperature of the substrate 5 was normal temperature, and the total flow rate of oxygen and BCl3 was 40 sccm.
When the etch rate of the HfO ₂ film on the substrate was determined by ellipsometry, it was 30 nm / min.

For comparison, when oxygen and BCl ₃ were mixed and sent to a remote plasma generator and activated to be introduced into the chamber 1, the etching rate was 10 nm / min.
As a result, it has been found that the method of the present invention has an etching action superior to that of the prior invention.

(Example 2)
In Example 1, the wafer tray 4 on which the substrate 5 was placed was heated to 200 to 600 ° C., and a similar experiment was performed to confirm the effect of promoting the etching rate by heating.
The results are shown in Table 1.

  From the results in Table 1, it can be seen that heating the substrate 5 significantly increases the etching efficiency.

It is a schematic block diagram which shows the example of the apparatus used for the cleaning method of this invention. It is a schematic block diagram which shows the other example of the apparatus used for the cleaning method of this invention.

Explanation of symbols

1 .... Chamber, 5 .... Substrate, 10 .... Halogen gas supply source, 12 .... Remote plasma generator, 13 .... Excitation gas supply source

Claims (8)

In a cleaning method for removing deposits made of a high dielectric constant oxide generated in a chamber of a semiconductor processing apparatus,
It is characterized in that at least one of a non-reactive gas, an oxygen atom supply gas and an oxidizing gas is activated in a remote plasma generator to be a gas containing active species, and this gas is introduced into a chamber together with a halogen-based gas. A method for cleaning a semiconductor processing apparatus.   2. The semiconductor processing apparatus cleaning method according to claim 1, wherein a gas containing active species and a halogen-based gas are mixed and introduced into the chamber.   2. The semiconductor processing apparatus cleaning method according to claim 1, wherein a gas containing active species and a halogen-based gas are separately introduced into the chamber.   2. The semiconductor processing apparatus cleaning method according to claim 1, wherein the semiconductor processing apparatus forms a film by any one of a CVD method and an atomic layer deposition method. In a method of etching a high dielectric constant oxide film formed on a substrate,
It is characterized in that at least one of a non-reactive gas, an oxygen atom supply gas and an oxidizing gas is activated in a remote plasma generator to be a gas containing active species, and this gas is introduced into a chamber together with a halogen-based gas. A method of etching a high dielectric constant oxide film.   6. The method for etching a high dielectric constant oxide film according to claim 5, wherein a gas containing active species and a halogen-based gas are mixed and introduced into the chamber.   6. The method of etching a high dielectric constant oxide film according to claim 5, wherein a gas containing active species and a halogen-based gas are separately introduced into the chamber. 6. The method for etching a high dielectric constant oxide film according to claim 5, wherein the semiconductor processing apparatus is formed by a CVD method or an atomic layer deposition method.

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