JPH05144779A - Dry etching method for silicon oxide film - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide a dry etching method for a silicon oxide film, which eliminates the drawback that a deposited film of a reaction product is deposited on the inner wall of a chamber and causes the generation of foreign matter. .. [Configuration] At least plasma is generated by using at least a C, F-based gas or a mixed gas of C, F, H-based gas and a gas containing halogen other than F, which are used in dry etching of a silicon oxide film, to generate silicon. A step of etching the oxide film to a desired amount, and the C, F-based gas or C, F,
By improving the quality of the deposition film by the step of etching the remaining silicon oxide film using only H-based gas,
The foreign substances generated during etching are reduced. [Effects] In dry etching of a silicon oxide film, foreign substances attached to a substrate during etching can be reduced. Therefore, by etching the silicon oxide film using this method, it is possible to improve the yield of semiconductor devices to be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching method for a silicon oxide film used for manufacturing semiconductor devices and the like.

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor device or the like, when a foreign matter (generally called dust or particles) adheres to a substrate, a pattern defect of a target semiconductor element (for example, between individual element elements in an LSI) It will cause the wiring to short circuit and will not function properly.)
This causes a decrease in yield in the manufacturing process.

Furthermore, in recent years, in semiconductor devices and the like,
Since miniaturization (line width of 1 μm or less) and high density have been promoted, the size of problematic foreign matter is becoming smaller year by year, and it is required to extremely reduce the number thereof.

On the other hand, in a dry etching apparatus for a silicon oxide film, generally anisotropic etching or Si of the underlying layer is performed.
C, F-based gas or C, F, H-based gas (for example, CHF
₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , CH ₂ F
₂ ) and an additive gas such as He, Ar, O ₂ , N ₂ and H ₂ gas is used, so that the etching gas is decomposed and combined in the plasma, and the etching side generated by the silicon oxide film etching is used. The product forms a deposited film (a thin film containing C, F, Si, O, H, etc., hereinafter referred to as a deposition film) on the inner wall of the chamber. Since this deposition film mainly contains a large amount of C and F, the film itself is weak and easily peels off. Therefore, when the number of processed films increases and the deposition film becomes thicker, it partially peels off and adheres to the substrate. It becomes a foreign substance.

Conventionally, in order to prevent an increase of the foreign matter, and reduced as much as possible the amount of deposited film at the stage where a certain amount of deposition layer is formed, the plasma by the cleaning gas such as O ₂ and SF ₆ or NF ₃ Was used to remove (dry cleaning), or the chamber was opened and wiped with alcohol or the like (wet cleaning).

Further, after cleaning, particles (foreign matter) remaining on the surface of the chamber material or the inner wall of the chamber are peeled off (flying) to prevent foreign matter from adhering to the substrate, and dummy etching is performed to stabilize the etching state. (Use the dummy substrate to perform the same etching process as usual to form a deposition film in the chamber to some extent), and then perform the etching (treatment) of the target substrate with the silicon oxide film. , Stable dry etching with few foreign substances was performed.

[0007]

However, the above-mentioned method of dry etching a silicon oxide film has the following problems.

(1) The deposition film prevents foreign substances in the chamber from flying to the substrate. However, since the deposition film formed mainly of etching gas components C, F, and H is brittle or weak, The deposition film deposited on the inner wall of the chamber is easily peeled off during etching, the effect of suppressing foreign matters is small, and even when the number of processed wafers is small, a minute area is peeled off, and the peeled film itself flies and becomes foreign matter.

(2) During the silicon semiconductor process, S generated from the back surface of the substrate or the like which is brought into contact with the carrier system or the like
Although there are many foreign substances of i, it is difficult to reactively remove the foreign substances of Si because the etching selectivity to Si is usually enhanced by using a gas containing C.

(3) The gas for etching the silicon oxide film is usually an F-based gas, and the F-based gas reactively removes metallic foreign substances such as Al that are often used for chambers and chamber internal parts. Is difficult to do.

An object of the present invention is to provide a dry etching method for a silicon oxide film, which eliminates the above-mentioned conventional drawbacks.

[0012]

In order to solve the above problems, the method of the present invention comprises: At least a C, F-based gas or C, F, H-based gas that is usually used for etching a silicon oxide film and a gas containing halogen other than F are used to generate plasma to etch the silicon oxide film to a desired amount. And the step of etching the remaining silicon oxide film using only the C, F based gas or the C, F, H based gas.

2. Using a dummy substrate, introducing a gas capable of forming a Si-based deposited film on the inner wall of the chamber, and generating plasma to decompose the gas to form the deposited film; The substrate with an oxide film is achieved by a step of introducing at least a C, F-based gas or a C, F, H-based gas and generating plasma to etch the silicon oxide film.

3. F using a dummy silicon substrate
A gas containing halogen other than the above to generate plasma to etch the dummy silicon substrate and form a deposited film on the inner wall of the chamber by the etching by-product, This is accomplished by introducing at least a C, F based gas or a C, F, H based gas into the substrate and generating plasma to etch the silicon oxide film.

[0015]

According to the present invention, with the above-described structure, the quality of the deposit film deposited on the inner wall of the chamber is improved, the foreign substance suppressing effect is enhanced even with a thin film, and the deposit film is prevented from peeling and becoming foreign substances. That is, in the initial etching that does not require a selection ratio with respect to the base, a gas containing a halogen other than F is added to reduce the C and F components of the deposition film, and a halogen other than F is reacted with Si to react with silicon halogen. The film quality of the deposition film is improved by forming a compound (reactants other than F have a low vapor pressure and are easily deposited on the inner wall of the chamber).

Further, by using a gas containing halogen other than F, the selection ratio is lowered to remove Si in the chamber reactively, or halogen other than F reacts with a metal such as Al. Foreign matter can be reduced by utilizing the high vapor pressure.

Therefore, by the above-mentioned operation, it is possible to reduce the foreign matter due to the deposit film and the foreign matter remaining in the chamber, and to reduce the foreign matter generated (adhered) during the etching of the silicon oxide film.

[0018]

Embodiments of the dry etching method for a silicon oxide film according to the present invention will be described below in detail with reference to the drawings.

First Embodiment FIG. 1 is a schematic sectional view of a substrate for explaining a first embodiment of the present invention. In FIG. 1, 11 is a silicon substrate, 12 is a silicon oxide film formed by CVD or the like,
Reference numeral 13 is a photoresist having an opening in a desired region. FIG. 2 is a schematic cross-sectional view of a commonly used parallel plate type reactive ion etching apparatus for explaining the first embodiment of the present invention. In FIG. 2, 21 is a chamber for etching, 22 is a cathode electrode, and 23 is a cathode electrode.
Is a substrate guide for placing the substrate in a predetermined position, 24 is a gas introduction pipe for introducing an etching gas into the etching chamber, and 27 is an exhaust port for keeping the inside of the chamber at a constant vacuum degree.

First, a substrate (for example, the film thickness of the silicon oxide film 2 is 1000 nm) as shown in FIG.
As shown in Fig. 3, the C,
CHF ₃ and CF ₄ are used as F and H-based gases, Ar is used as an additive gas for controlling the etching shape, and SiCl ₄ is used as a gas containing a halogen other than F. After being introduced into the chamber, high frequency power is applied to the cathode electrode 22 by the 13.56 MHz high frequency power source 10 to generate plasma,
As shown in FIG. 1B, etching is performed until the silicon oxide film 12 is slightly left (for example, about 10% of the initial film thickness of the silicon oxide film 12 is left). At this time, since the underlying silicon substrate 11 is not exposed, etching selectivity is not required, and since SiCl ₄ gas is added, SiC
Since l ₄ is decomposed in plasma to form a deposition film of Si, the flow rates of CHF ₃ gas and CF ₄ which have conventionally been used to form an etching side wall protective film for achieving anisotropy may be small. Therefore, the deposition film quality deposited on the inner wall of the chamber contains a large amount of Si, and a film that is difficult to peel off can be formed, so that the increase of foreign substances generated during etching can be suppressed.

Next, CHF is used as a C, F, H-based gas.
After introducing a mixed gas of only ₃ , CF ₄ and Ar, plasma is generated to etch the silicon oxide film 12 up to FIG. 1C, and the silicon oxide film 1 in the opening of the resist 13 is etched.
Etch 2. At this time, in order to completely etch the silicon oxide film 12, overetching is necessary in consideration of film thickness uniformity, etching uniformity, etc., and the underlying silicon substrate 11 is exposed during etching. Since the silicon substrate 11 is not etched, high etching selectivity is required.
Mixed gas not containing ₄ gases (CHF ₃ , CF ₄ and Ar)
Need to be used. However, even if 10% over etching of the silicon oxide film 12 thickness is performed, CHF ₃
Etching with only CF ₄ and Ar is only about 20% of the whole, and the increase of foreign matter during etching can be made very small.

By the two-step etching as described above,
As compared with the conventional method, it is possible to reduce the amount of foreign matter generated during dry etching of the silicon oxide film to 1/2 or less.

Second Embodiment FIG. 3 is a schematic sectional view of a commonly used parallel plate type reactive ion etching apparatus for explaining the second, third and fourth embodiments of the present invention. is there. In FIG. 3, 31 is a chamber for etching, 32 is a cathode electrode, 33 is a substrate guide for placing a substrate at a predetermined position, 34 is a gas introduction pipe for introducing an etching gas into the etching chamber, and 37 is a chamber. Is an exhaust port that maintains a constant vacuum degree. First, as shown in FIG. 3A, a dummy silicon substrate 38 as a dummy substrate is introduced into the dry etching apparatus, and S is deposited on the inner wall of the chamber.
As a gas capable of forming an i-based deposited film, Si is used.
Cl ₄ gas and O ₂ gas are introduced into the chamber 31 through the gas introduction pipe 34, and high frequency power is applied to the cathode electrode 32 from the high frequency power supply 10 of 13.56 MHz to generate plasma, and the dummy silicon substrate 38 is etched. To do. At this time, SiCl ₄ is decomposed by plasma and C
l reacts with Si of the dummy silicon substrate 38 to produce S
It produces i-Cl and its polymeric materials. The reaction product, Si-Cl, partially reacts with O decomposed by plasma to form a substance such as Si-O system or Si-Cl-O system. On the other hand, by the decomposition of SiCl ₄ by plasma, Si
And a polymer material of Si-Cl is formed. S from the above substrate
The i-based material and the Si-based material due to the decomposition of the gas have a low vapor pressure and are deposited in the chamber to form a deposition film. The deposit film can suppress the generation of foreign matter. After that,
As shown in FIG. 3 (b), a target substrate with a silicon oxide film (FIG. 1a) is introduced into a dry etching apparatus,
After introducing CHF ₃ and CF ₄ as C, F, and H-based gases and Ar as an additive gas for controlling the etching shape, high-frequency power is applied to generate plasma and the substrate with a silicon oxide film is etched. The etching of the substrate with the silicon oxide film is repeated a plurality of times continuously, depending on the amount of dummy etching.

As described above, after the Si-based deposition film is formed using the dummy silicon substrate, the silicon oxide film is dry-etched to reduce the amount of foreign matter generated during the etching to less than half that of the conventional one. It becomes possible to do.

Third Embodiment Similar to the second embodiment, the dummy silicon substrate 38 is introduced into the dry etching apparatus, HBr gas is introduced as a gas containing halogen other than F, and then the cathode electrode. A high frequency power is applied to 32 to generate plasma to etch the dummy silicon substrate 38. At this time, a reaction product of Si-Br type substance is formed, and a deposition film for suppressing the generation of foreign matter is formed on the inner wall of the chamber. Then, as shown in FIG. 3 (b), the target substrate with a silicon oxide film (FIG. 1a) is introduced into the dry etching apparatus, and CHF ₃ and CF ₄ are added as C, F, H-based gases,
After introducing Ar as an additive gas for controlling the etching shape, high frequency power is applied to generate plasma to etch the substrate with the silicon oxide film. The etching of the substrate with the silicon oxide film is repeated a plurality of times continuously, depending on the amount of dummy etching.

As described above, after the Si-based deposition film is formed using the dummy silicon substrate, the silicon oxide film is dry-etched to reduce the amount of foreign matter generated during the etching to 1/2 or less of the conventional level. It becomes possible to do.

Fourth Embodiment In substantially the same manner as in the second embodiment, after introducing the dummy silicon substrate 38 into the dry etching apparatus and introducing HBr gas as a gas containing halogen other than F and O _2. ,
High frequency power is applied to the cathode electrode 32 to generate plasma, and the dummy silicon substrate 38 is etched.
At this time, HBr is decomposed by the plasma, and reacts with Si of the dummy silicon substrate 38 by Br to cause Si-Br.
And its polymeric substances. The reaction product, Si
-Br partially reacts with O decomposed by plasma to generate S
A material such as i-O type or Si-Br-O type is prepared.
These have a low vapor pressure and are deposited in the chamber to form a deposit film. The deposit film can suppress the generation of foreign matter. After that, as shown in FIG. 3B, the target substrate with a silicon oxide film (FIG. 1A) is introduced into the dry etching apparatus, and CHF ₃ gas is used as C, F, H-based gas.
After introducing CF ₄ and CF ₄ as an additive gas for controlling the etching shape, high frequency power is applied to generate plasma to etch the substrate with the silicon oxide film. The etching of the substrate with the silicon oxide film is repeated a plurality of times continuously, depending on the amount of dummy etching.

As described above, after the Si-based deposition film is formed using the dummy silicon substrate, the silicon oxide film is dry-etched to reduce the amount of foreign matter generated during the etching to less than half that of the conventional one. It becomes possible to do.

Although CHF ₃ and CF ₄ are used as the C, F-based gas or C, F, H-based gas in the description of the embodiments, these are C _2, F ₆ , C ₃ F ₈ , C
A single gas or a mixed gas of ₄ F ₈ , CH ₂ F _2, etc. may be used. Further, although Ar is used as the additive gas to be added, this may be He, O ₂ , N ₂ or H ₂ gas or may not be used. Further, SiCl ₄ and O ₂ are used as gases capable of forming a Si-based deposited film in the chamber.
However, these are SiH ₂ Cl ₂ and N
It may be H ₃ , SiH ₄ and N ₂ O. Also, F
Has been described using HBr as a gas containing halogen other than this is Br _2, Cl _2, HCl, or and the like HI.

[0030]

As will be apparent from the detailed description above,
Since the present invention can reduce foreign substances attached to a substrate during dry etching of a silicon oxide film substrate, by performing etching using this method, it is possible to improve the yield of semiconductor devices to be manufactured, and it is very effective to carry out. There is.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a substrate for explaining a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a parallel plate type reactive ion etching apparatus for explaining a first embodiment of the present invention.

FIG. 3 is a schematic sectional view of a dry etching apparatus for explaining an embodiment of the present invention.

[Explanation of symbols]

 11 Silicon Substrate 12 Silicon Oxide Film 13 Photoresist 21, 31 Chamber 22, 32 Cathode Electrode 23, 33 Substrate Guide 24, 34 Gas Inlet Pipe 27, 37 Exhaust Port 38 Dummy Silicon Substrate

Claims (4)

[Claims] 1. At least a C, F-based gas or C, F, which is usually used in dry etching of a silicon oxide film.
A step of generating plasma to etch the silicon oxide film to a desired amount using a mixed gas of an H-based gas and a gas containing a halogen other than F, and the C, F-based gas or C,
A dry etching method for a silicon oxide film, comprising the step of etching the remaining silicon oxide film using F and H based gases. 2. In dry etching, before the target substrate with a silicon oxide film is etched, a dummy substrate is used to introduce a gas capable of forming a Si-based deposited film to generate plasma. By the process of decomposing the gas to form a deposited film on the inner wall of the chamber by introducing at least C, F-based gas or C, F, H-based gas to generate plasma. A dry etching method for a silicon oxide film, comprising the step of etching the silicon oxide film. 3. In the dry etching, before the target substrate with a silicon oxide film is etched, a dummy silicon substrate is used to introduce a gas containing halogen other than F to generate plasma, whereby the dummy is produced. Of etching a silicon substrate for use and forming a deposited film on the inner wall of the chamber by the etching by-product, and introducing at least C, F-based gas or C, F, H-based gas into the target substrate with a silicon oxide film. Then, a method of dry etching a silicon oxide film, comprising the step of generating plasma and etching the silicon oxide film. 4. In the dry etching, a dummy silicon substrate is used to etch a gas containing halogen other than F and O ₂ before etching the target substrate with a silicon oxide film.
A step of etching the dummy silicon substrate by introducing a mixed gas with a gas to generate plasma and forming a deposited film on the inner wall of the chamber by the etching by-product, and a target substrate with a silicon oxide film To
A dry etching method for a silicon oxide film, comprising a step of introducing at least C, F based gas or C, F, H based gas and generating plasma to etch the silicon oxide film.