JPH06163474A - Dry etching method - Google Patents

Abstract

PURPOSE:To enable a layer of silicon compound such as SiO2 or the like to be quickly dry-etched high in selectivity and low in damage and contamination. CONSTITUTION:An SiO2 interlayer insulating film 3 is etched with mixed gas of C3O2 (tricarbon dioxide)/SF6. Carbonic polymer derived from decomposition products of a resist mask 4 grows high in etching resistance taking in C-O bonds and carbonyl groups derived from C3O2 even if it deposits small. As a result, ions necessary for sputtering a resist mask 4 can be lessened in impinging energy, and an etching process can be improved in selectivity. An etching process can be executed at a high speed by using mixed gas of C3O2 and CHF3 as etching gas. If C3O2 is used in combination with S2F2, free S(sulfur) can be used as deposits in place of carbonic polymer, so that an etching process can be lessened in contamination. N2O or SO2 other than C3O2 can be utilized.

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 applied in the field of manufacturing semiconductor devices, etc., and particularly to any one of resist selectivity, silicon underlayer selectivity, high speed, low damage and low contamination. The present invention also relates to a dry etching method of a silicon compound layer, which is also excellent.

[0002]

2. Description of the Related Art With the recent progress in high integration and high performance of semiconductor devices as seen in VLSI, ULSI, etc., dry etching of silicon compound layers typified by silicon oxide (SiO ₂ ) has also been performed. Technical requirements are becoming more and more stringent.

First, the area of device chips is expanded due to high integration, the diameter of the wafer is increased, the pattern to be formed is highly miniaturized, and uniform processing within the wafer surface is required. The mainstream of the dry etching apparatus is shifting from the conventional batch type to the single-wafer type because of the demand for high-mix low-volume production represented by ASIC. At this time, in order to maintain the same productivity as the conventional one, it is necessary to greatly improve the etching rate per wafer.

Further, in the situation where the junction depth of the impurity diffusion region is shallow and the various material layers are thin in order to increase the speed and miniaturization of the device, the selectivity to the underlayer is more excellent than before. Etching technology with less damage is required. For example, a PM used as an impurity diffusion region formed in a semiconductor substrate or a resistance load element of SRAM.
An example is etching of a SiO ₂ interlayer insulating film, which is performed using a silicon substrate or a polycrystalline silicon layer as a base when a contact is to be formed in the source / drain region of an OS transistor.

Further, improving the selection ratio with respect to the resist is also an important issue. This is because submicron devices have become unacceptable for producing slight dimensional conversion differences due to resist receding.

Conventionally, the etching of the SiO ₂ type material layer is performed in a mode in which the ionicity is strengthened in order to break the strong Si—O bond. Typical etching gas is CHF ₃ , CF _4, etc., and the incident energy of CF _x ⁺ generated from these is used. However, in order to perform high-speed etching, it is necessary to increase this incident ion energy, and since the etching reaction is close to the physical sputtering reaction, there is a need for high speed and high selectivity and low damage. The demand was always in conflict.

Therefore, usually, H ₂ or a depositing hydrocarbon gas is added to the etching gas to obtain an apparent C / F ratio (ratio of the number of carbon atoms and the number of fluorine atoms) of the etching reaction system. High selectivity is achieved by increasing and promoting the deposition of carbon-based polymer that occurs in competition with the etching reaction.

[0008]

By the way, in the conventional method, in order to obtain sufficiently high selectivity, it was necessary to deposit the carbon-based polymer to a certain thickness. But,
Increasing the deposition amount of the carbon-based polymer causes new problems such as a decrease in etching rate and an increase in particle contamination. In recent years, single-wafer processing has become the mainstream in dry etching, so that the time required for etching per wafer is extended, or the frequency of maintenance for cleaning the etching chamber is high It causes a serious obstacle to the economy.

Therefore, an object of the present invention is to provide a dry etching method for a silicon compound layer which is excellent not only in high selectivity and low damage but also in high speed and low contamination.

[0010]

The dry etching method of the present invention is proposed in order to achieve the above-mentioned object, and is at least one inorganic oxide selected from carbon oxide, nitric oxide, and sulfur oxide. And a fluorine compound are used to etch the silicon compound layer.

The present invention also comprises at least one inorganic oxide selected from carbon oxide, nitric oxide and sulfur oxide,
The silicon compound layer is etched using an etching gas containing a fluorocarbon compound represented by the general formula CH _x F _4-x (where x represents an integer of 0 to 3).

The present invention also includes a just etching step of etching the silicon compound layer using the etching gas to a depth that does not substantially exceed the layer thickness thereof,
The content ratio of the inorganic oxide in the etching gas is set to be higher than that in the just etching step to overetch the silicon compound layer.

The present invention further comprises just etching using an etching gas containing the above-mentioned inorganic oxide and a fluorine-based compound, or an inorganic oxide and a fluorocarbon-based compound, and then S ₂ F ₂ , SF ₂ , SF ₄ , S ₂ F
Overetching is performed using an etching gas containing at least one kind of sulfur fluoride selected from ₁₀ and the inorganic oxide.

In the present invention, the above-mentioned inorganic oxide is
Used as a constituent of etching gas
Therefore, considering handling, it is a gas under normal temperature and pressure.
Or it is necessary to select a compound that can be easily vaporized.
There is. From this point of view, as a highly practical carbon oxide,
Is CO (carbon monoxide), CO ₂(Carbon dioxide), C₃
O₂(Tricarbon dioxide, boiling point 7 ° C)
It Besides carbon oxide, the number of carbon atoms in the molecule is
The compound called carbon suboxide, which has more than the number of elementary atoms,
It is well known that when performing a silent discharge in carbon monoxide
Generated substances with inconsistent composition, pentacarbon dioxide, and 9-acid
There are 12 carbon atoms (mellitic anhydride) and the like.

Further, as highly practical nitric oxide, N
₂ O (dinitrogen oxide), NO (nitric oxide), N ₂ O
₃ (dinitrogen trioxide), NO ₂ (nitrogen dioxide), NO
₃ (nitric oxide) can be mentioned. Other known nitric oxides are N ₂ O ₅ (dinitrogen pentoxide).
And N ₂ O ₆ (dinitrogen hexaoxide), the former has a sublimation point of 3
2.4 ° C. (1 atm) solid, the latter is an unstable solid.

Further, as highly practical sulfur oxide
Is SO (sulfur monoxide), SO₂(Sulfur dioxide)
Can be mentioned. In addition to this, several kinds of sulfur oxide
It is known that, at room temperature, complex phases and
Many are present as a mixture with composition. for example
For example, S₂O₃(Di sulfur trioxide) is heated to S, S
O, SO₂It is a solid that decomposes into. SO₃(Io trioxide
C) is a liquid near room temperature, or an α type with a different melting point,
It is a solid that takes either β-type or γ-type. S₂O₇
(Sulfur heptoxide) is a solid with a melting point of 0 ° C and a sublimation point of 10 ° C.
is there. Furthermore, SO _Four(Sulfur tetraoxide) is a solid with a melting point of 3 ° C.
Although it is a body, it generates oxygen and decomposes it, and
To generate.

[0017]

The point of the present invention is that by strengthening the film quality of the carbon-based polymer itself, a sufficiently high resist selectivity and underlayer selectivity can be achieved even if the amount of deposition thereof is reduced. To achieve damage. In the present invention, at least one of carbon oxide, nitric oxide and sulfur oxide is used as a constituent of the etching gas. These inorganic oxides have multiple bonds between different atoms in the molecule and exist as a resonance hybrid of some polarization structures. However, some of these polarization structures have high polymerization promoting activity. Have. As a result, the degree of polymerization of the carbon-based polymer derived from the decomposition products of the etching gas and the decomposition products of the organic material pattern used as the etching mask is increased, and the etching resistance is improved.

Decomposition products of these inorganic oxides are carbon-based polymers having a carbonyl group (> C = O), a nitrosyl group (-N = O), a nitrile group (-NO ₂ ), a thionyl group> S. = O), it can be introduced polar groups such as sulfuryl group (-SO _2). When such a polar group is introduced into the carbon-based polymer, the chemical and physical stability may be increased as compared with the conventional carbon-based polymer which is simply composed of a repeating structure of —CX ₂ — (X represents a halogen atom). , Recent research has revealed. The rationale for the reason for this phenomenon is roughly the following two points.

One of them is C—O bond (1077 kJ
/ Mol), C-N bond (770 kJ / mol), N-
O bond (631 kJ / mol), C—S bond (713 k)
J / mol) has an interatomic bond energy of C-
The fact is that it is larger than the C-bond (607 kJ / mol). Another is that the introduction of the above-mentioned functional group increases the polarity of the carbon-based polymer and increases the electrostatic attraction force to the wafer being etched, which is negatively charged.

As described above, since the film quality of the carbon-based polymer itself is strengthened and it becomes highly resistant to incident ions, the selectivity is improved with respect to the organic material pattern as the etching mask and the underlying material layer. In addition, the occurrence of damage to the base material layer is reduced. In addition, since the amount of carbon-based polymer that is required to achieve high selectivity can be relatively reduced, particle contamination can be reduced as compared with the conventional technique.

The above-mentioned inorganic oxide also contributes to speeding up the etching. That is, the above can be generated from the functional groups _{^{CO *, SO *, SO 2}} *, radicals NO ^* such has a strong reducing action, it is possible to pull out the O atoms in the SiO _2. This is because the interatomic bond energy calculated from the heat of formation of a diatomic molecule is 1 for a C—O bond.
076 kJ / mol, 523 kJ / mo for SO bond
It can also be understood from the fact that it is 632 kJ / mol for l, N—O bond, which is larger than 465 kJ / mol for Si—O bond in the crystal. The Si atom after the O atom is extracted is quickly removed in the form of a halide by bonding with F ^* (fluorine radical) which is the main etching species present in the etching reaction system.

That is, according to the present invention, the breaking of the Si--O bond, which has heretofore mainly depended on the physical sputtering action, can be performed by utilizing the chemical action. Moreover, the inorganic oxide used in the present invention has no significant effect on the resist material and the underlying Si-based material, and the etching rate of these materials is kept low.

Further, in the present invention, it is proposed to use a fluorocarbon compound in addition to the above-mentioned inorganic oxide in order to further increase the etching speed and selectivity. This fluorocarbon compound CH _x F _4-x not only releases F ^* , which is the main etching species of the silicon compound layer, but also produces ions such as CHF ⁺ , CF ^{+ and the} like, and these ions are sputtered at high speed. Enables etching. Further, when this fluorocarbon-based compound is used, the carbon-based polymer can be supplied from the gas phase, and it is not necessary to rely on the resist decomposition product to secure the underlayer selectivity. Therefore, the incident ion energy can be further reduced, and the resist selectivity can be improved.

The present invention is based on the above idea, but proposes a method aiming at higher selection, lower pollution and lower damage. One is to divide the etching of the silicon compound layer into two steps, a just etching step until just before the underlying material layer is exposed, and an overetching step after that, and in the latter half overetching step, the inorganic oxide in the etching gas is divided. Is to be larger than in the just etching process. According to this method, etching in the vicinity of the interface with the base in the SiO ₂ -based material layer proceeds by a mechanism that reduces F ^* and promotes O atom abstraction reaction and polymer strengthening. Is achieved.

Alternatively, etching during over-etching
Gas composition, S₂F₂, SF ₂, SF_Four, S₂F
_TenAt least one kind of sulfur fluoride selected from the above and
It may be a mixed system with an inorganic oxide. That is, over
Since high speed is not required at the time of etching,
Do not use Orocarbon compounds
It eliminates any deposits.

The sulfur fluoride used here is the one that the applicant of the present invention previously described in Japanese Patent Application No. 2-198045.
It is a compound proposed for etching a SiO ₂ -based material layer and produces etching species such as SF _x ⁺ and F ^* . Further, the sulfur fluoride has a large S / F ratio (ratio of the number of S atoms and the number of F atoms in one molecule) compared to SF ₆ which has been practically used as an etching gas, and it is under discharge dissociation conditions. Free S (sulfur) can be released into the plasma. Depending on the conditions, this S is deposited on the surface of the wafer if the temperature of the wafer is controlled below room temperature. At this time, on the surface of the SiO ₂ -based material layer, S is removed in the form of SO _{x in} response to the supply of O atoms.
It is deposited as it is on the surface of the system material or on the side wall of the pattern and contributes to the achievement of high selectivity and high anisotropy.

Moreover, the deposited S easily sublimes when the wafer is heated to approximately 90 ° C. or higher after etching, and the sulfur nitride compound is decomposed or sublimated at approximately 130 ° C. or higher, so that no particle contamination is caused on the wafer. Do not leave. Therefore, it is possible to perform etching that is excellent in high speed, high selectivity, low contamination, and low damage.

When this sulfur fluoride is used in combination with nitric oxide, S produced from sulfur fluoride and N produced from this nitric oxide are combined to form polythiazyl (SN).
_A sulfur nitride compound mainly composed of _x is produced. This sulfur nitride-based compound exerts a more effective surface protection action than S alone.

[0029]

EXAMPLES Specific examples of the present invention will be described below.

Example 1 This example is an example in which the present invention is applied to contact hole processing and a SiO ₂ interlayer insulating film is etched using a C ₃ O ₂ / SF ₆ mixed gas. This process is illustrated in Figure 1.
Will be described with reference to. The wafer used as a sample in this example is, as shown in FIG.
The SiO ₂ interlayer insulating film 3 is formed on the single crystal silicon substrate 1 on which the impurity diffusion region 2 is formed in advance, and the Si 2
A resist mask 4 is formed as an etching mask for the O ₂ interlayer insulating film 3. The resist mask 4 has an opening 4a.

The above wafer was set on the wafer mounting electrode of a magnetron RIE (reactive ion etching) apparatus. Here, the wafer mounting electrode has a built-in cooling pipe, by supplying a refrigerant to the cooling pipe from a cooling equipment such as a chiller connected to the outside of the apparatus to circulate the cooling pipe,
It is possible to control the wafer temperature during etching to be room temperature or lower. As an example, SiO under the following conditions
_{2 The} interlayer insulating film 3 was etched.

C₃O₂Flow rate 20 SCCM SF₆Flow rate 30 SCCM Gas pressure 2.0 Pa RF power density 2.2 W / cm²(1
3.56 MHz) Magnetic field strength 1.50 × 10^-2 T (= 150
G) Wafer temperature -30 ° C (alcohol-based
Refrigerant used) In this etching process, Si exposed in the opening 4a
O₂On the surface of the interlayer insulating film 3, SF₆Raw in large quantities
F to make^*Si atom abstraction reaction by C, and C₃O
₂CO generated from^*O atom abstraction reaction by
F_x ⁺, CO_x ⁺SiO etc.₂Spatter / etch
At an etching rate of about 250 nm / min.
The hatching has progressed.

On the other hand, the carbon-based decomposition products supplied from the resist mask 4 by ion sputtering are
A strong carbon-based polymer was formed while incorporating a C—O bond and a carbonyl group into the structure. This carbon-based polymer exhibited high etching resistance even in a small amount, and significantly reduced the etching rate on the surface of the resist mask 4 and the single crystal silicon substrate 1. Further, since the wafer is cooled at a low temperature, the radical reaction due to F ^* is suppressed, and the etching rate of the resist material or silicon-based material that is mainly etched in the radical mode is Si.
It was relatively lower than that of the O ₂ based material.

For these reasons, the resist mask 4
And extremely high selectivity was achieved for the single crystal silicon substrate 1. In particular, since the shape of the resist mask 4 is maintained well, the contact hole 5 having a good anisotropic shape is formed without causing a dimensional conversion difference as shown in FIG. 1B. We were able to.

Example 2 This example is the same as in the contact hole processing.
This is an example of etching the SiO ₂ interlayer insulating film using a NO / SF ₆ mixed gas. The wafer used as the etching sample in this example is the same as that shown in FIG. The same applies to each embodiment described later.

An example of etching conditions is shown below. NO flow rate 20 SCCM SF ₆ flow rate 30 SCCM gas pressure 2.0 Pa RF power density 2.2 W / cm ² (1
3.56 MHz) Magnetic field strength 1.50 × 10 ^-2 T (= 150
G) Wafer temperature −30 ° C. (using alcohol-based refrigerant) The etching mechanism that proceeds under the above conditions is almost the same as in Example 1, but here the carbon-based polymer is a C—N bond or a nitrosyl group. Was enhanced by the introduction of.

Embodiment 3 In this embodiment, the same SiO ₂ interlayer insulating film 3 is formed with SO ₂ / S.
Etching was performed using an F ₆ mixed gas. An example of etching conditions is shown below. SO ₂ flow rate 20 SCCM SF ₆ flow rate 30 SCCM Gas pressure 2.0 Pa RF power density 2.2 W / cm ² (1
3.56 MHz) Magnetic field strength 1.50 × 10 ^-2 T (= 150
G) Wafer temperature −30 ° C. (using alcohol-based refrigerant) The etching mechanism that proceeds under the above conditions is almost the same as in Example 1, but here, the carbon-based polymer is a C—S bond or a sulfuryl group, It was strengthened by the introduction of a thionyl group and the like.

Embodiment 4 In this embodiment, the same interlayer insulating film 3 is formed by C ₃ O ₂ / CHF ₃
Etching was performed using a mixed gas. An example of etching conditions is shown below. C ₃ O ₂ flow rate 20 SCCM CHF ₃ flow rate 30 SCCM Gas pressure 2.0 Pa RF power density 2.0 W / cm ² (1
3.56 MHz) Magnetic field strength 1.50 × 10 ^-2 T (= 150
G) Wafer temperature -30 ° C (using alcohol refrigerant)

In this example, since an ion-assisted reaction due to CF _x ⁺ can be expected, the etching rate was greatly increased as compared with Example 1 and was about 450 nm / min.
In addition, since carbonaceous polymer is also generated in the vapor phase by using CHF ₃ which has a deposition property, the resist mask 4
The amount of decomposition products to be supplied can be small. That is, the incident ion energy can be lowered and the sputtering of the resist mask 4 can be suppressed as compared with the previous embodiments. In this embodiment, the resist mask 4
Almost no decrease in the film thickness, receding of the pattern edge, or destruction of the shallow junction due to overetching was observed. The selection ratio to resist was about 5, and the selection ratio to silicon was about 25.

Moreover, the relative content of CHF ₃ is lowered by the addition of C ₃ O ₂ to the etching gas, and the absolute amount of the carbon-based polymer produced is much smaller than that in the conventional process. The frequency of maintenance required to clean the etching chamber can be reduced,
The throughput is greatly improved.

Even when etching is performed under the same conditions except that N ₂ O or SO ₂ is used instead of C ₃ O ₂ described above, high speed, high selection and low contamination etching can be similarly performed. did it.

Embodiment 5 This embodiment is the same as the contact hole processing,
Etching of the SiO ₂ interlayer insulating film 3 using a C ₃ O ₂ / CHF ₃ mixed gas is divided into two stages, a just etching process and an overetching process, and in the latter process, C ₃ O _{2 is used.}
This is an example in which the content ratio of is relatively increased to further improve the selectivity. This process will be described with reference to FIG. 2 and FIG. 1 above.

First, using the wafer shown in FIG.
As an example, under the following conditions, SiO ₂Interlayer insulation film 3
Substantially immediately before the impurity diffusion region 2 is exposed. C₃O₂Flow rate 15 SCCM (content ratio in etching gas 30%) CHF₃Flow rate 35 SCCM Gas pressure 2.0 Pa RF power density 2.0 W / cm²(13.
56 MHz) Magnetic field strength 1.5 × 10^-2 T Wafer temperature 0 ° C

The etching mechanism in this just etching process is almost as described above in the fourth embodiment.
The end point determination was performed when the emission spectrum intensity of CO ^* at 483.5 nm or the emission spectrum intensity of SiF ^* at 777 nm started to change. This time point corresponds to when the underlying impurity diffusion region 2 starts to be exposed on a part of the wafer. However, in the other part on the wafer, as shown in FIG. 2, the contact hole 5 was formed only up to the middle part, and the residual part 3a of the SiO ₂ interlayer insulating film 3 was left at the bottom part.

Therefore, the etching conditions were switched to the following conditions as an example, and overetching for removing the residual portion 3a was performed. C ₃ O ₂ flow rate 30 SCCM (content ratio in etching gas 60%) CHF ₃ flow rate 20 SCCM gas pressure 2.0 Pa RF power density 1.2 W / cm ² (13.
56 MHz) Magnetic field strength 1.5 × 10 ^-2 T Wafer temperature 0 ° C. In this over-etching process, the RF power density is reduced to reduce incident ion energy, and the chemical O atom abstraction reaction by CO ^* is mainly used. Etching was performed. Since the content ratio of CHF ₃ was lowered,
Although the amount of carbon-based polymer produced was reduced, the strengthening was effective.

As a result, it was possible to perform good high selection, low damage and low contamination etching even though the wafer temperature was raised as compared with the fourth embodiment.

It should be noted that, during just etching, NO ₂ / C
Even when the NO ₂ or SO ₂ content ratio was increased during overetching using a HF ₃ mixed gas or a SO ₂ / CHF ₃ mixed gas, high selectivity, low damage, and low contamination etching could be similarly performed. . When SO ₂ is used, the end point of the just etching step can be determined by the change in the emission spectrum intensity of SO ^{* at} any of 306 nm, 317 nm, and 327 nm.

Example 6 In this example, CO ₂ / C was used in the just etching process.
HF ₃ / CF ₄ mixed gas, C in the over etching process
By using O ₂ / S ₂ F ₂ mixed gas, thorough pollution reduction was achieved. An example of just etching conditions is shown below.

CO ₂ flow rate 15 SCCM CHF ₃ flow rate 30 SCCM CF ₄ flow rate 5 SCCM gas pressure 2.0 Pa RF power density 2.0 W / cm ² (13.
56 MHz) Magnetic field strength 1.5 × 10 ⁻² T Wafer temperature 0 ° C. Here, non-depositing CF ₄ was used as an F ^* source for increasing the etching rate.

Then, as an example, overetching was performed under the following conditions. CO ₂ flow rate 15 SCCM S ₂ F ₂ flow rate 35 SCCM gas pressure 2.0 Pa RF power density 1.0 W / cm ² (13.
56 MHz) Magnetic field strength 1.5 × 10 ⁻² T Wafer temperature 0 ° C. In this over-etching process, the incident ion energy is reduced to promote the etching mainly by the O atom abstraction reaction, and from S ₂ F ₂ S generated by dissociation
Was deposited on the surface of the resist mask 4 and the impurity diffusion region 2. As a result, high selectivity could be achieved with almost no carbon-based polymer deposited near the interface with the impurity diffusion region 2.

The deposited S could be easily removed by sublimation or combustion when the wafer was heated to about 90 ° C. after etching or when the resist mask 4 was ashed. S deposited in the etching chamber could be similarly removed. Therefore, in this example, the reduction of pollution was further thorough. As a result, the device yield was improved and the throughput was also improved.

Based on the same idea, NO ₂ / C
When just etching is performed using a HF ₃ / CF ₄ mixed gas and then overetching is performed using a NO ₂ / S ₂ F ₂ mixed gas, or when SO ₂ / CHF ₃ /
Even when just etching was performed using the CF ₄ mixed gas and then overetching was performed using the SO ₂ / S ₂ F ₂ mixed gas, high selection and low contamination etching could be similarly performed.

Although the present invention has been described based on the six embodiments, the present invention is not limited to these embodiments. For example, as the fluorine-based compound, NF ₃ , ClF ₃ or the like can be used in addition to SF ₆ described above. Although S ₂ F ₂ was used as the sulfur fluoride in the above-mentioned examples, the use of other sulfur fluorides limited in the present invention, that is, SF ₂ , SF ₄ , and S ₂ F ₁₀ , is basically used. Produces similar results.

In the etching gas used in the present invention, O ₂ or the like is added for the purpose of controlling the etching rate, or He, Ar or the like is used in the sense of expecting a sputtering effect, a dilution effect, a cooling effect or the like. You may add a rare gas suitably. The material layer to be etched is not limited to the above-mentioned SiO ₂ interlayer insulating film, but may be PSG, BSG, BP.
Other Si such as SG, AsSG, AsPSG, AsBSG
It may be an O ₂ -based material layer, or may be Si _x N _y or the like.

In addition, it goes without saying that the structure of the wafer, the etching apparatus used, the etching conditions, etc. can be changed as appropriate.

[0056]

As is apparent from the above description, in the present invention, by using an etching gas containing any of carbon oxide, nitric oxide, and sulfur oxide in the etching of the silicon compound layer, the carbon-based polymer of Even if the film quality is enhanced and the amount of deposition is reduced, high selectivity can be achieved. As a result, the device yield can be improved, the maintenance frequency of the etching apparatus can be reduced, and the throughput can be improved. If these inorganic oxides are mixed with a conventionally known fluorocarbon compound, the process can be sped up, and if it is used together with a sulfur compound that releases S under discharge dissociation conditions, higher selectivity can be obtained. It is possible to reduce the damage and pollution.

The present invention is extremely suitable for manufacturing a semiconductor device which is designed based on a fine design rule and which requires high integration, high performance and high reliability.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a process in which the present invention is applied to processing a contact hole in the order of steps, (a) showing a state where a resist mask is formed on a SiO ₂ interlayer insulating film, (b) ) Indicates the state where the contact holes are opened.

[FIG. 2] Another application of the present invention to the processing of contact holes
In the process example of ₂Interlayer insulation film is just
It is a schematic sectional drawing which shows the state which was etched.

[Explanation of symbols]

1 ... monocrystalline silicon substrate 2 ... impurity diffusion regions 3 ... SiO ₂ interlayer insulating film 3a ... (the SiO ₂ interlayer insulating film) remainder 4 ... resist mask 4a ... opening Part 5: Contact hole

Claims (4)

[Claims] 1. A dry etching characterized by etching a silicon compound layer using an etching gas containing at least one inorganic oxide selected from carbon oxide, nitric oxide and sulfur oxide, and a fluorine compound. Method. 2. At least one inorganic oxide selected from carbon oxide, nitric oxide, and sulfur oxide, and a general formula CH _x.
A dry etching method characterized by etching a silicon compound layer using an etching gas containing a fluorocarbon compound represented by F _4-x (where x represents an integer of 0 to 3). 3. A just etching step of using the etching gas to etch the silicon compound layer to a depth that does not substantially exceed its layer thickness, and a content ratio of the inorganic oxide in the etching gas is 3. The dry etching method according to claim 1, further comprising an over-etching step of etching the remaining portion of the silicon compound layer to a greater extent than in the just etching step. 4. A just etching step of etching a silicon compound layer to a depth which does not substantially exceed the layer thickness according to the dry etching method according to claim 1 or 2, and S ₂ F ₂ , SF ₂ , SF ₄ , S ₂ F
A dry etching method comprising: an overetching step of etching the remaining portion of the silicon compound layer using an etching gas containing at least one kind of sulfur fluoride selected from ₁₀ and the inorganic oxide.