JP7145740B2 - Etching method - Google Patents

Description

The present disclosure relates to etching methods for etching SiGe-based materials.

In recent years, silicon germanium (referred to as SiGe) has been known as a new semiconductor material other than silicon (hereinafter referred to as Si). A material obtained by selectively etching a Si layer and a material obtained by selectively etching a Si layer with respect to a SiGe layer are desired.

Techniques for selectively etching SiGe with respect to Si include those using ClF ₃ and XeF ₂ as etching gases (Patent Document 1), those using HF (Patent Document 2), NF ₃ gas and O ₂ gas. (Patent Document 3) is known that uses mixed gas plasma such as. As a technique for selectively etching Si with respect to SiGe, there is known a technique for etching by adding a germanium-containing gas to an etching gas containing SF ₆ or CF ₄ (Patent Document 4).

Further, Patent Document 5 describes that selective etching of SiGe with respect to Si and selective etching of Si with respect to SiGe _are possible by changing the ratio of F2 gas and _NH3 gas.

Japanese translation of PCT publication No. 2009-510750 JP-A-2003-77888 Japanese Patent No. 6138653 JP 2013-225604 A JP 2016-143781 A

By the way, all of the above techniques only etch SiGe selectively with respect to Si or selectively etch Si with respect to SiGe. Etching one of the layers with respect to the other with a high selectivity is also being demanded, and the above technique cannot sufficiently cope with such etching.

Therefore, the present disclosure provides an etching method capable of etching one of SiGe-based materials having different Ge concentrations with respect to the other with a high selectivity.

An etching method according to an aspect of the present disclosure supplies an etching gas to an object to be processed having a first SiGe-based material and a second SiGe-based material having Ge concentrations different from each other, and removes the first SiGe-based material. and one of the first SiGe-based material and the second SiGe-based material with respect to the other by utilizing the difference in incubation time until the second SiGe-based material is etched by the etching gas In the etching method, the first SiGe-based material is a first film made of a SiGe film having a Ge concentration of 20 to 50 at %, and the second SiGe-based material is Ge A second film made of a SiGe film having a concentration of 0 to 20 at % (excluding 0 at %), and as an etching gas, at least one selected from the group consisting of _ClF3 gas, F2 gas, and _{IF7 gas} . The first film is selectively etched with respect to the second film using a gas containing a fluorine-containing gas .

An etching method according to another aspect of the present disclosure supplies an etching gas to an object to be processed having a first SiGe-based material and a second SiGe-based material having Ge concentrations different from each other, and removes the first SiGe The first SiGe-based material and the second SiGe-based material are repeatedly etched at an etching time at which one of the SiGe-based material and the second SiGe-based material is etched and the other is not substantially etched, and the purging of the processing space is repeated multiple times to remove the first SiGe-based material and the second SiGe-based material. An etching method for selectively etching one of the second SiGe-based materials with respect to the other, wherein the first SiGe-based material is a first film made of a SiGe film having a Ge concentration of 20 to 50 at %. and the second SiGe-based material is a second film made of a SiGe film having a Ge concentration of 0 to 20 at % (excluding 0 at %), and etching gases include ClF ₃ gas, F ₂ gas, The first film is selectively etched with respect to the second film using a gas containing at least one fluorine-containing gas selected from the group consisting of IF7 _gases .

An etching method according to still another aspect of the present disclosure supplies an etching gas in a low temperature range to an object to be processed having a first SiGe-based material and a second SiGe-based material having Ge concentrations different from each other, and An etching method for selectively etching one of a first SiGe-based material and a second SiGe-based material with respect to the other, wherein the first SiGe-based material is a SiGe film having a Ge concentration of 20 to 50 at %. and the second SiGe-based material is a second film made of a SiGe film having a Ge concentration of 0 to 20 at % (excluding 0 at %), and the etching gas is ClF ₃ The first film is selectively etched with respect to the second film using a gas containing at least one fluorine-containing gas selected from the group consisting _of gas, F2 gas, and IF7 _gas .

According to the present disclosure, one of the first SiGe-based material and the second SiGe-based material can be etched at a high selectivity without substantially etching the other.

FIG. 4 is a diagram for schematically explaining the etching method according to the first example of the first embodiment; FIG. 4 is a diagram showing the relationship between the etching time and the etching amount for Si-10% Ge film and Si-30% Ge film at 80° C., 100° C., and 120° C.; It is a figure which expands and shows a part of FIG. It is a figure for demonstrating roughly the etching method based on the 1st example of 2nd Embodiment. FIG. 4 is a diagram showing the temperature dependence of the etching amount when a Si film with a Ge concentration of 0% is etched with ClF ₃ gas. FIG. 4 is a diagram showing the temperature dependence of the etching amount when a SiGe film with a Ge concentration of 30 at % (Si-30% Ge film) is etched with ClF ₃ gas. Etching of Si-30% Ge film with respect to Si-10% Ge film when etching Si-10% Ge film and Si-30% Ge film at 35 ° C. which is a low temperature range and 120 ° C. which is a high temperature range It is a figure which shows a selection ratio. 1 is a schematic cross-sectional view showing a first example of a structure of an object to be processed to which the first and second embodiments are applied, and showing a state before etching; FIG. FIG. 2 is a schematic cross-sectional view showing a first example of the structure of an object to be processed to which the first and second embodiments are applied, and shows a state after etching; FIG. 5 is a schematic cross-sectional view showing a second example of the structure of the object to be processed to which the first and second embodiments are applied, and showing a state before etching; FIG. 5 is a schematic cross-sectional view showing a second example of the structure of the object to be processed to which the first and second embodiments are applied, and showing a state after etching; 1 is a schematic configuration diagram showing an example of a processing system equipped with an etching apparatus used for carrying out the first embodiment and the second embodiment; FIG. 1 is a cross-sectional view showing an example of an etching apparatus for carrying out a first example etching method of the first and second embodiments; FIG. It is a figure which shows an example of the etching apparatus for enforcing the etching method of the 2nd example of 1st and 2nd embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
First, the first embodiment will be described.
In the present embodiment, an etching gas, for example, a fluorine-containing gas is supplied to a substrate to be processed having a first SiGe-based material and a second SiGe-based material having Ge concentrations different from each other. The first SiGe-based material and the second SiGe-based material are separated from each other by using the incubation time difference at a temperature at which there is a difference in the incubation time until the etching gas starts to etch the material and the second SiGe-based material. Etch one selectively with respect to the other. In this embodiment, the SiGe-based material includes a case where Ge is 0% (that is, a case of Si).

A first example of the present embodiment includes a first film made of SiGe having a relatively high Ge concentration as a first SiGe-based material and a film having a relatively high Ge concentration as a second SiGe-based material. An object to be processed having a low SiGe film or a second film made of a Si film containing 0% Ge is prepared, and a fluorine-containing gas is supplied as an etching gas to the object to be processed to convert the first film into a second film. Etching selectively with respect to the film. Inert gas such as Ar gas may be supplied in addition to the fluorine-containing gas. At this time, it is preferable that the second film is hardly etched and the selection ratio of the first film to the second film is 5 or more.

As the fluorine _- containing gas, _ClF3 gas, F2 gas, _IF7 gas, or the like can be used.

At this time, if a fluorine-containing gas as described above is used as an etching gas, the first film having a high Ge concentration is more likely to be etched than the second film having a low Ge concentration. Although it is possible to selectively etch the first film with respect to the second film, especially in a high-temperature range, the second film is also etched by etching that simply utilizes the difference in chemical reactivity due to the etching gas. I don't like it.

On the other hand, in this example, selective etching is performed in a predetermined temperature range, particularly in a high temperature range as described later, by utilizing the difference in the incubation times of the etching reactions of the first film and the second film. The incubation time is the time from the supply of the etching gas to the actual start of the etching reaction. As shown in FIG. It is longer than the incubation time (T1) of the first film with high Ge concentration. By utilizing this incubation time difference (ΔT), etching of the first film is performed while sufficiently suppressing etching of the second film, and etching with high selectivity is performed.

The reason why such an incubation time difference (ΔT) exists is that the SiO ₂ film as a natural oxide film that is difficult to etch with a fluorine-containing gas is formed more on the surface of the second film than on the first film. It is considered to be

The incubation time can be adjusted by the temperature of the object to be processed (etching temperature) during etching, and etching is performed so that a sufficient incubation time difference (ΔT) is formed between the first film and the second film. It is preferred to set the temperature. At this time, it is more preferable that the time required for etching the first film is equal to or less than the incubation time (T2) of the second film, that is, the incubation period. As a result, the first film can be etched at a high selectivity with respect to the second film while hardly etching the second film.

In this example, as described above, a 0% Ge Si film is allowed as the low Ge concentration second film, but the effect is more pronounced when both the first film and the second film are SiGe films. As a specific numerical value, the Ge concentration of the high Ge concentration first film is preferably in the range of 20 to 50 at %, more preferably 25 to 35 at %, for example 30 at %. The second film preferably has a Ge concentration in the range of 0 to 20 at % (not including 20 at %), more preferably 5 to 15 at %, for example 10 at %.

In this embodiment, the etching temperature is preferably in a high temperature range of 100.degree. C. or higher, more preferably 100 to 125.degree. Most preferred is 120°C. SiGe films tend to be more easily etched at lower temperatures when etched with a fluorine-containing gas such as ClF ₃ gas, and natural oxide films are also easily etched. Although it depends on the quality of the SiGe film, at around 80° C., the natural oxide film on the surface of the SiGe film with a low Ge concentration is likely to be etched, the incubation time is short, and it is difficult to obtain a difference in the incubation time. On the other hand, in a high temperature range of 100° C. or higher, the etching rate of the natural oxide film on the surface of the SiGe film and the film itself decreases, and in the SiGe film with a low Ge concentration, the natural oxide film also becomes difficult to etch. The incubation time of the second film with low Ge concentration can be lengthened, and the incubation time difference can be lengthened. In particular, at around 120° C., the SiGe film containing 10 at % of Ge can be sufficiently long incubating time of about 10 minutes, and the second film with a low Ge concentration is hardly etched until the etching time is about 10 minutes. For example, the first film with a high Ge concentration of 30 at % can be etched with a high selectivity. However, if the etching temperature is 130° C. or higher, it becomes difficult to etch even the first film with a high Ge concentration.

The pressure during etching is preferably in the range of 10 to 1000 mTorr (1.33 to 133 Pa), for example 120 mTorr (16 Pa).

Next, experimental results of the first example of the first embodiment will be described.
Here, ClF ₃ gas is used as the etching gas, and the etching temperature is set to was changed to 80° C., 100° C., and 120° C., and the relationship between the etching time and the etching amount was obtained. The results are shown in FIG. Moreover, FIG. 3 is a figure which expands and shows a part of FIG.

As shown in these figures, both the Si-10%Ge film and the Si-30%Ge film show a large amount of etching at 80° C., and the Si-30%Ge film has a higher Si-10% at any temperature. It can be seen that the amount of etching is larger than that of the %Ge film. At 80° C., the incubation time was short for both the Si-10% Ge film and the Si-30% Ge film, and the etching of the Si-10% Ge film was started in a short time. It can be seen that the etching amount of the %Ge film is 10 nm or more. On the other hand, when the etching temperature is 100° C., the incubation time of the Si-10%Ge film is 100 sec, and it is possible to etch using the incubation time difference from the Si-30%Ge film. Also, even if the etching time is 600 sec (10 min), the etching amount of the Si-10% Ge film is about 3 nm, and the Si-30% Ge film can be etched while suppressing the etching of the Si-10% Ge film. rice field. In addition, when the etching temperature is 120° C., the incubation time of the Si-10% Ge film is 600 sec (10 min), and the selectivity of the Si-30% Ge film to the Si-10% Ge film is infinite for a long period of 600 sec. It was confirmed that etching can be performed with Also, when the etching temperature was 120° C., the etching amount of the Si-10% Ge film was as small as about 5 nm even when the etching time was 1200 sec.

Next, a second example of this embodiment will be described. A second example is a first film made of SiGe with a relatively high Ge concentration as the first SiGe-based material, and a SiGe film with a relatively low Ge concentration as the second SiGe-based material, or A second film made of a Si film containing 0% Ge is prepared, and a fluorine-containing gas and NH ₃ gas are supplied as etching gases to the object to be processed, so that the second film is formed on the first film. Etching selectively with respect to the film. That is, contrary to the first example, the second film having a low Ge concentration is selectively etched with respect to the first film having a high Ge concentration. At this time, it is preferable that the second film is hardly etched and the selection ratio of the second film to the first film is 5 or more.

The reason why the difference in Ge concentration is reversed by adding _NH3 gas as an etching gas in this way is that the addition of _NH3 gas to the fluorine-containing gas makes it easier to etch _SiO2 , which is the natural oxide film on the surface. This is because it is easier for As the fluorine _- containing gas, _ClF3 gas, F2 gas, _IF7 gas, etc. can be used as in the first example. The ratio of the fluorine-containing gas and the NH ₃ gas is preferably in the range of 1/500-1.

Also in this example, the Ge concentrations of the first film and the second film are the same as in the first example, and only the side to be etched is different. The same applies to the etching temperature, which is preferably 100.degree. C. or higher, more preferably 100 to 125.degree. C., and most preferably 120.degree.

<Second embodiment>
Next, a second embodiment will be described.
In this embodiment, an etching gas, for example, a gas containing fluorine-containing gas is supplied to a substrate to be processed having a first SiGe-based material and a second SiGe-based material having Ge concentrations different from each other to form a first SiGe. The etching process with an etching time at which one of the SiGe-based material and the second SiGe-based material is etched while the other is not substantially etched, and the purging of the processing space are repeated multiple times to obtain the first SiGe-based material and the second SiGe-based material. , one of the SiGe-based materials is selectively etched with respect to the other. Also in this embodiment, the SiGe-based material includes the case where Ge is 0% (that is, the case of Si).

A first example of the present embodiment includes a first film made of SiGe having a relatively high Ge concentration as a first SiGe-based material and a film having a relatively high Ge concentration as a second SiGe-based material. An object to be processed having a low SiGe film or a second film made of a Si film with 0% Ge is prepared, and as shown in FIG. The etching step (S1) for an etching time during which one film is etched and the second film is not substantially etched, and the processing space purge step (S2) are repeated a predetermined number of times. The purging step (S2) of the processing space can be performed by evacuating the processing container that defines the processing space. An inert gas may be supplied as a purge gas to the processing space along with evacuation. By repeating the etching step (S1) and the purge step (S2) a predetermined number of times in this manner, the first film is etched at a high selectivity with respect to the second film while hardly etching the second film. can do. At this time, it is preferable that the second film is hardly etched and the selection ratio of the first film to the second film is 5 or more.

One etching step (S1) is preferably completed in a period during which the first film is etched while the second film is etched within the incubation period. As a result, even if the etching step (S1) is repeated, the natural oxide film on the surface of the second film is hardly etched, and only the first film can be repeatedly etched to obtain a desired etching amount. Therefore, in this example, even if the incubation time difference between the first film and the second film is small, substantially only the first film can be etched by a desired amount, so the temperature margin is greater than in the first example. is wide.

As the fluorine _- containing gas, _ClF3 gas, F2 gas, _IF7 gas, etc. can be used as in the first embodiment. In addition to the fluorine-containing gas, an inert gas such as Ar gas may be supplied.

As described above, a 0% Ge Si film is acceptable as the second film with a low Ge concentration, but the effect is more pronounced when both the first film and the second film are SiGe films. As a specific numerical value, the Ge concentration of the high Ge concentration first film is preferably in the range of 20 to 50 at %, more preferably 25 to 35 at %, for example 30 at %. Also, the second film preferably has a Ge concentration in the range of 0 to 20 at % (not including 20 at %), more preferably 5 to 15 at %, for example 10 at %.

As described above, the margin of the etching temperature is wider than in the first embodiment. Also in this example, the etching temperature is preferably 100.degree. C. or higher, more preferably 100 to 125.degree. Most preferred is 120°C.

In this example, the time for one etching step (S1) is preferably 1 to 10 sec, and the time for one purge step (S2) is preferably 5 to 30 sec. Also, the pressure during etching is preferably in the range of 10 to 1000 mTorr (1.33 to 133 Pa), for example, 120 mTorr (16 Pa).

Next, a second example of this embodiment will be described. A second example is a first film made of SiGe with a relatively high Ge concentration as the first SiGe-based material, and a SiGe film with a relatively low Ge concentration as the second SiGe-based material, or preparing an object to be processed having a second film made of a Si film containing 0% Ge, and supplying a fluorine-containing gas and _NH3 gas as etching gases to the object to be processed to etch the second film; The etching process for an etching time during which the first film is not substantially etched and the process space purging process are repeated a predetermined number of times. That is, contrary to the first example, the second film having a low Ge concentration is selectively etched with respect to the first film having a high Ge concentration. At this time, it is preferable that the second film is hardly etched and the selection ratio of the second film to the first film is 5 or more.

By adding NH ₃ gas as the etching gas in this manner, the difference in Ge concentration is reversed on the same principle as in the second example of the first embodiment.

<Third Embodiment>
Next, a third embodiment will be described.
In the present embodiment, an etching gas, for example, a fluorine-containing gas is supplied in a low temperature range to a substrate to be processed having a first SiGe-based material and a second SiGe-based material having Ge concentrations different from each other. one of the SiGe-based material and the second SiGe-based material is selectively etched with respect to the other. In this embodiment, unlike the first embodiment that utilizes the incubation time difference, the selectivity is ensured by the difference in etching amount between the two. In this embodiment, the SiGe-based material includes a case where Ge is 0% (that is, a case of Si).

A first example of the present embodiment includes a first film made of SiGe having a relatively high Ge concentration as a first SiGe-based material and a film having a relatively high Ge concentration as a second SiGe-based material. An object to be processed having a low SiGe film or a second film made of a Si film containing 0% Ge is prepared, and a fluorine-containing gas is supplied as an etching gas to the object to be processed to convert the first film into a second film. Etching selectively with respect to the film. Inert gas such as Ar gas may be supplied in addition to the fluorine-containing gas. At this time, it is preferable that the second film is hardly etched and the selection ratio of the first film to the second film is 5 or more.

As the fluorine _- containing gas, _ClF3 gas, F2 gas, _IF7 gas, or the like can be used.

At this time, if a fluorine-containing gas as described above is used as an etching gas, the first film having a high Ge concentration is more likely to be etched than the second film having a low Ge concentration. One film can be selectively etched with respect to the second film.

The pressure during etching is preferably in the range of 10 to 1000 mTorr (1.33 to 133 Pa), for example 120 mTorr (16 Pa).

In this embodiment, the etching temperature is in a low temperature range, preferably 60° C. or less. It is more preferably in the range of 0 to 60°C.

The reason for this will be explained below with reference to FIGS.

FIG. 5 is a diagram showing the temperature dependence of the etching amount when a Si film with a Ge concentration of 0% is etched with ClF ₃ gas, which is a fluorine-containing gas. It shows the tendency of the etching amount when the etching is performed at 30 seconds. The etching conditions for the Si film were ClF ₃ gas flow rate: 20 to 500 sccm, Ar gas flow rate: 100 to 1000 sccm, and pressure: 500 to 3000 mTorr. As shown in this figure, the etching amount of the Si film does not have linearity with temperature, and there is a tendency that the etching amount is large in the middle temperature range around 80° C., and is small at 60° C. or lower and 100° C. or higher. . In particular, at 60° C. or lower, the etching amount of the Si film is smaller. Such a tendency is considered to be due to the fact that the Si film etching with ClF ₃ gas is strongly affected by chemical adsorption characteristics. This tendency is considered to be the same for SiGe films with a small amount of Ge (eg, Si-10% Ge film).

On the other hand, FIG. 6 is a diagram showing the temperature dependence of the etching amount when a SiGe film with a Ge concentration of 30 at % (Si-30% Ge film) is etched with ClF ₃ gas. It shows the amount of etching when the temperature is set to 30 sec for the etching time. The etching conditions for the Si-30% Ge film were ClF ₃ gas flow rate: 1 to 100 sccm, Ar gas flow rate: 100 to 1000 sccm, and pressure: 10 to 1000 mTorr. From this figure, it seems that the etching of the Si-30% Ge film has a strong physical adsorption characteristic, and the etching amount has linearity with respect to temperature, and there is a tendency that the etching amount increases as the temperature decreases.

From FIGS. 5 and 6, in the low temperature range of 60° C. or less where the etching amount of the Si-30% Ge film increases and the etching amount of the Si film decreases, the Si-30% Ge film is more effective than the high temperature range. The etching selectivity can be increased, and it is understood that the value tends to increase as the temperature decreases. As shown in FIG. 7, which will be described later, the etching selectivity of the Si-30%Ge film shows a high value of 20 or more with respect to the Si-10%Ge film showing an etching tendency similar to that of the Si film. 5 and 6 only show data up to 20°C, but from the tendencies of these figures, it is considered that a high selectivity can be obtained up to at least 0°C. In this way, the first film made of SiGe with a relatively high Ge concentration is formed at a low temperature range of preferably 60° C. or lower, more preferably 0 to 60° C., and further 20 to 60° C. ( The second film made of SiGe (including 0%) can be etched with an extremely high selectivity without using the incubation time difference.

Incidentally, since the etching amount of the Si-30% Ge film decreases as the temperature increases, the etching selection ratio of the Si-30% Ge film to the Si film is adversely affected. The etching amount of the Si film is reduced. Therefore, even in a high temperature range of 100° C. or higher, the etching selectivity of the Si-30% Ge film relative to the Si film can be made relatively high without using the incubation time difference. However, as described in the first embodiment, the first film can be etched with higher selectivity with respect to the second film by utilizing the incubation time difference in the high temperature range.

Next, experimental results of the first example of the third embodiment will be described.
First, using ClF ₃ gas as an etching gas, a SiGe film with a Ge concentration of 10 at % (Si-10% Ge film) and a SiGe film with a Ge concentration of 30 at % (Si-30% Ge film) were etched in a low-temperature region. Etching was performed at 35° C., which is a high temperature range, and 120° C., which is a high temperature range. In FIG. 7, the horizontal axis represents the amount of etching of the Si-30% Ge film, and the vertical axis represents the amount of etching of the Si-10% Ge film. It is a diagram of The etching conditions at this time were ClF ₃ gas flow rate: 1 to 100 sccm, Ar gas flow rate: 100 to 1000 sccm, and pressure: 10 to 1000 mTorr. As shown in this figure, the etching selectivity of the Si-30%Ge film to the Si-10%Ge film was 24.6 at 35.degree. C. and 11.2 at 120.degree. From these results, it was confirmed that a high etching selectivity of 20 or more was obtained in the low temperature range, and that an etching selectivity of 10 or more was obtained in the high temperature range, though not as low as in the low temperature range.

<Structure example of object to be processed to which first and second embodiments are applied>
Next, structural examples of the object to be processed to which the first and second embodiments are applied will be described. An object to be processed is typically a semiconductor wafer (hereinafter simply referred to as a wafer).

8A and 8B are diagrams showing a first example of the structure of the object to be processed.
In this example, as shown in FIG. 8A, on a semiconductor substrate 1 such as a Si substrate, a high Ge concentration SiGe film (for example, 30 at % Ge concentration) 11 as a first film to be etched and a second film are formed. A laminated structure with a low-Ge-concentration SiGe film (for example, Ge-concentration 10 at %) 12 is formed. Specifically, a low-Ge-concentration SiGe film 12 and a high-Ge-concentration SiGe film 11 are sequentially laminated on the semiconductor substrate 1, and the uppermost stage is the low-Ge-concentration SiGe film 12. For example, SiO ₂ film is formed thereon. An etching mask 13 made of a film is formed. The low Ge concentration SiGe film 12 and the high Ge concentration SiGe film 11 may be laminated one or more times.

In this state, the object to be processed is held at a predetermined temperature, and a fluorine-containing gas such as ClF ₃ gas is supplied as in the first example of the first embodiment, or the first By repeating the supply and purge of the fluorine-containing gas, the high-Ge-concentration SiGe film 11 is etched as in the example of FIG. 8B, for example. At this time, the low-concentration GeSiGe film 12 is hardly etched. In FIG. 8B, part of the high-Ge concentration SiGe film 11 is etched, but the whole may be etched. Also, a Si film may be used instead of the low-concentration GeSiGe film 12 .

9A and 9B are diagrams showing a second example of the structure of the object to be processed.
In this example, as shown in FIG. 9A, a high Ge concentration SiGe film (for example, Ge A laminated structure 30 is formed of a concentration of 30 at %) 31 and a Si film 32, and an insulating film 41 such as a Low-k film is placed on both sides of the laminated structure 30 at portions corresponding to the source and drain of the semiconductor substrate 21. , which functions as a protective layer and has a low Ge concentration SiGe film (for example, 10 at % Ge concentration) 42 serving as a second film, and a high Ge concentration SiGe film (for example, 30 at % Ge concentration) 43 provided outside thereof. . In the laminated structure 30, a Si film 32 and a high-Ge-concentration SiGe film 31 are laminated in order on a semiconductor substrate 21, the uppermost layer being the Si film 32, and an etching mask 33 made of, for example, a _SiO2 film thereon. is formed.

In this state, the object to be processed is held at a predetermined temperature, and a fluorine-containing gas such as ClF ₃ gas is supplied as in the first example of the first embodiment, or the first By repeating the supply and purge of the fluorine-containing gas, the high-Ge-concentration SiGe film 31 is etched as in the example of FIG. 9B, for example. At this time, the low-concentration GeSiGe film 42 is hardly etched and functions as a protective layer to prevent the high-Ge-concentration SiGe film (eg, 30 at % Ge concentration) 43 from being etched.

In the above two structural examples, in the case of the first embodiment and the second example of the second embodiment, the high Ge concentration SiGe film and the low Ge concentration SiGe film (or Si film) are reversed. becomes.

<Processing system>
Next, an example of a processing system equipped with an etching apparatus used for carrying out the first embodiment and the second embodiment will be described.
FIG. 10 is a schematic configuration diagram showing an example of a processing system. This processing system 100 includes a loading/unloading unit 102 for loading/unloading a wafer W as an object to be processed having the structure shown in the structural example above, two load lock chambers 103 provided adjacent to the loading/unloading unit 102, Heat treatment equipment 104 for performing heat treatment on the wafer W provided adjacent to each load lock chamber 103, and etching equipment for performing etching on the wafer W provided adjacent to each heat treatment equipment 104. 105 and a control unit 106 .

The loading/unloading section 102 has a transfer chamber 112 in which a first wafer transfer mechanism 111 for transferring the wafer W is provided. The first wafer transfer mechanism 111 has two transfer arms 111a and 111b that hold the wafer W substantially horizontally. A mounting table 113 is provided on a side portion in the longitudinal direction of the transfer chamber 112. To this mounting table 113, for example, three carriers C such as FOUPs for accommodating a plurality of wafers W can be connected. ing. An alignment chamber 114 for aligning the wafer W is provided adjacent to the transfer chamber 112 .

In the loading/unloading section 102, the wafer W is held by the transport arms 111a and 111b, and driven by the first wafer transport mechanism 111 to move straight in a substantially horizontal plane and to move up and down to a desired position. Then, the transfer arms 111a and 111b move forward and backward with respect to the carrier C on the mounting table 113, the alignment chamber 114, and the load lock chamber 103, respectively, so that they are carried in and out.

Each load lock chamber 103 is connected to the transfer chamber 112 with a gate valve 116 interposed therebetween. A second wafer transfer mechanism 117 for transferring the wafer W is provided in each load lock chamber 103 . Moreover, the load lock chamber 103 is configured to be able to be evacuated to a predetermined degree of vacuum.

The second wafer transfer mechanism 117 has an articulated arm structure and has a pick that holds the wafer W substantially horizontally. In the second wafer transfer mechanism 117, the pick is positioned in the load lock chamber 103 with the articulated arm contracted. It is possible to reach the etching device 105 and transfer the wafer W between the load lock chamber 103 , the heat treatment device 104 and the etching device 105 .

The control unit 106 typically consists of a computer, and includes a main control unit having a CPU that controls each component of the processing system 100, an input device (keyboard, mouse, etc.), an output device (printer, etc.), a display device ( display, etc.) and a storage device (storage medium). The main control unit of the control unit 106 causes the processing system 100 to execute a predetermined operation based on a processing recipe stored in, for example, a storage medium built in a storage device or a storage medium set in the storage device. .

In such a processing system 100 , a plurality of wafers W having the above structure are accommodated in the carrier C and transferred to the processing system 100 . In the processing system 100, one wafer W is transferred from the carrier C of the loading/unloading section 102 to the load lock chamber 103 by one of the transfer arms 111a and 111b of the first wafer transfer mechanism 111 while the gate valve 116 on the atmosphere side is open. , and transferred to the pick of the second wafer transfer mechanism 117 in the load lock chamber 103 .

After that, the gate valve 116 on the atmosphere side is closed to evacuate the load lock chamber 103 , the gate valve 154 is opened, the pick is extended to the etching device 105 , and the wafer W is transferred to the etching device 105 .

After that, the pick is returned to the load lock chamber 103, the gate valve 154 is closed, and the high Ge concentration SiGe film, for example, is etched in the etching apparatus 105 by the etching method described above.

After the etching process is completed, the gate valves 122 and 154 are opened, and the wafer W after the etching process is transported to the heat treatment apparatus 104 by the pick of the second wafer transport mechanism 117, and the etching residue and the like are removed by heating.

After the heat treatment in the heat treatment apparatus 104 is completed, the wafer is returned to the carrier C by one of the transfer arms 111 a and 111 b of the first wafer transfer mechanism 111 . This completes the processing of one wafer.

If there is no need to remove the etching residue or the like, the heat treatment apparatus 104 may not be provided. The wafer is retracted to the chamber 103 and returned to the carrier C by one of the transfer arms 111 a and 111 b of the first wafer transfer mechanism 111 .

<Etching device>
Next, an example of the etching apparatus 105 for carrying out the etching method of the first example of the first and second embodiments will be described in detail.
FIG. 11 is a cross-sectional view showing an example of the etching apparatus 105. As shown in FIG. As shown in FIG. 11, the etching apparatus 105 includes a sealed chamber 140 as a processing container that defines a processing space. A mounting table 142 is provided. The etching apparatus 105 also includes a gas supply mechanism 143 that supplies etching gas to the chamber 140 and an exhaust mechanism 144 that exhausts the inside of the chamber 140 .

The chamber 140 is composed of a chamber main body 151 and a lid portion 152 . The chamber main body 151 has a substantially cylindrical side wall portion 151 a and a bottom portion 151 b , and has an opening at the top, which is closed with a lid portion 152 . Side wall portion 151a and lid portion 152 are sealed by a sealing member (not shown) to ensure airtightness in chamber 140 .

The lid portion 152 has a lid member 155 that constitutes the outside, and a shower head 156 that is fitted inside the lid member 155 and provided to face the mounting table 142 . The shower head 156 has a body 157 having a cylindrical side wall 157 a and a top wall 157 b and a shower plate 158 provided at the bottom of the body 157 . A space 159 is formed between the main body 157 and the shower plate 158 .

A gas introduction path 161 is formed through the lid member 155 and the upper wall 157b of the main body 157 to the space 159, and a fluorine-containing gas supply pipe 171 of a gas supply mechanism 143, which will be described later, is connected to the gas introduction path 161. It is

A plurality of gas discharge holes 162 are formed in the shower plate 158, and the gas introduced into the space 159 through the gas supply pipe 171 and the gas introduction path 161 is discharged from the gas discharge holes 162 into the space inside the chamber 140. .

A loading/unloading port 153 for loading/unloading the wafer W to/from the heat treatment apparatus 104 is provided in the side wall portion 151a.

The mounting table 142 has a substantially circular shape in plan view and is fixed to the bottom portion 151 b of the chamber 140 . A temperature adjuster 165 for adjusting the temperature of the mounting table 142 is provided inside the mounting table 142 . The temperature adjuster 165 includes, for example, a conduit through which a temperature adjusting medium (such as water) circulates. is adjusted, and the temperature of the wafer W on the mounting table 142 is controlled.

The gas supply mechanism 143 has a fluorine-containing gas supply source 175 for supplying a fluorine-containing gas such as ClF ₃ gas and an inert gas supply source 176 for supplying an inert gas such as Ar gas. One ends of a fluorine-containing gas supply pipe 171 and an inert gas supply pipe 172 are connected. The fluorine-containing gas supply pipe 171 and the inert gas supply pipe 172 are provided with a flow rate controller 179 for opening/closing the flow path and controlling the flow rate. The flow controller 179 is composed of, for example, an on-off valve and a mass flow controller. The other end of the fluorine-containing gas supply pipe 171 is connected to the gas introduction path 161 as described above. Also, the other end of the inert gas supply pipe 172 is connected to the fluorine-containing gas supply pipe 171 .

Therefore, the fluorine-containing gas is supplied from the fluorine-containing gas supply source 175 through the fluorine-containing gas supply pipe 171 into the shower head 156 , and the inert gas is supplied from the inert gas supply source 176 to the inert gas supply pipe 172 and the fluorine-containing gas supply pipe 172 . These gases are supplied to the shower head 156 through the containing gas supply pipe 171 and are discharged toward the wafer W in the chamber 140 from the gas discharge holes 162 of the shower head 156 .

Among these gases, the fluorine-containing gas is the reactive gas, and the inert gas is used as the diluent gas and the purge gas. A desired etching performance can be obtained by supplying a fluorine-containing gas alone or by supplying a mixture of a fluorine-containing gas and an inert gas.

The exhaust mechanism 144 has an exhaust pipe 182 connected to an exhaust port 181 formed in the bottom portion 151 b of the chamber 140 , and an automatic pressure regulator provided in the exhaust pipe 182 for controlling the pressure in the chamber 140 . It has a control valve (APC) 183 and a vacuum pump 184 for evacuating the chamber 140 .

Two capacitance manometers 186 a and 186 b are provided on the side wall of the chamber 140 as pressure gauges for measuring the pressure inside the chamber 140 so as to be inserted into the chamber 140 . The capacitance manometer 186a is for high pressure, and the capacitance manometer 186b is for low pressure. A temperature sensor (not shown) for detecting the temperature of the wafer W is provided in the vicinity of the wafer W mounted on the mounting table 142 .

In the etching apparatus 105 as described above, the wafer W having the structure described above is loaded into the chamber 140 and mounted on the mounting table 142 . Then, the pressure in the chamber 140 is set in the range of 10 to 1000 mTorr (1.33 to 133 Pa), for example, 120 mTorr (16 Pa), and the temperature controller 165 of the mounting table 142 heats the wafer W to preferably 100° C. or more, more preferably , 100-125°C, most preferably 120°C.

Then, when etching is performed according to the first example of the first embodiment, a fluorine-containing gas such as ClF ₃ gas is preferably supplied into the chamber 140 at a flow rate of 1 to 100 sccm to obtain high Ge concentration SiGe. Etch the film. As a result, the high Ge concentration SiGe film can be etched at a high selectivity with respect to the low Ge concentration SiGe film or the Si film, without substantially etching them. At this time, an inert gas such as Ar gas may be supplied at a flow rate of, for example, 100 to 1000 sccm together with the fluorine-containing gas. After the etching is finished, the chamber 140 is purged with an inert gas, and the wafer W is unloaded from the chamber 140 .

When performing etching according to the first example of the second embodiment, a fluorine-containing gas such as ClF ₃ gas is preferably supplied into the chamber 140 at a flow rate of 1 to 100 sccm to etch the high Ge concentration SiGe film. and the purge step of purging the processing space in the chamber 140 by vacuuming or by vacuuming and supplying an inert gas are repeated to etch the high-Ge-concentration SiGe film by a desired etching amount. . As a result, the high Ge concentration SiGe film can be etched at a high selectivity with respect to the low Ge concentration SiGe film or the Si film, without substantially etching them. At this time, in the etching process, an inert gas such as Ar gas may be supplied at a flow rate of, for example, 100 to 1000 sccm together with the fluorine-containing gas. After the etching is finished, the chamber 140 is purged with an inert gas, and the wafer W is unloaded from the chamber 140 .

When performing etching according to the second example of the first and second embodiments, etching is performed by an etching apparatus 105' shown in FIG. The etching apparatus 105' has a gas supply mechanism 143' having a fluorine-containing gas supply source 175, an inert gas supply source 176, and an _NH3 gas supply source 177 instead of the gas supply mechanism 143 of the etching apparatus 105 of FIG. Use what you have. One end of an NH ₃ gas supply pipe 173 is connected to the NH ₃ gas supply source 177 . The other end of the NH ₃ gas supply pipe 173 is connected to the fluorine-containing gas supply pipe 171 . The NH ₃ gas supply pipe 173 is provided with a flow rate controller 179 like the fluorine-containing gas supply pipe 171 and the inert gas supply pipe 172 .

With such an etching apparatus 105', the two structural examples shown in FIGS. , fluorine-containing gas and _NH3 gas, the low Ge concentration SiGe film (or Si film) can be etched with high selectivity to the high Ge concentration SiGe film.

<Other applications>
Although the embodiments have been described above, the embodiments disclosed this time should be considered as examples and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

For example, the structural example of the object to be processed in the above embodiment is merely an example, and the object to be processed has a first SiGe-based material and a second SiGe-based material (including the case where Ge is 0%) having different Ge concentrations. Any object to be processed can be applied. Further, the structures of the above-described processing system and individual devices are merely examples, and the etching method of the present invention can be implemented by systems and devices having various configurations.

1, 21; semiconductor substrate 11; high Ge concentration SiGe film 12; low Ge concentration SiGe film 13; etching mask 30; laminated structure 31; high Ge concentration SiGe film 32; k film)
42; low Ge concentration SiGe film 43; high Ge concentration SiGe film 100; processing system 105, 105'; etching apparatus 143, 143'; processing gas supply mechanism 175;

Claims (13)

An etching gas is supplied to an object to be processed having a first SiGe-based material and a second SiGe-based material having Ge concentrations different from each other, and the first SiGe-based material and the second SiGe-based material are etched. An etching method in which one of the first SiGe-based material and the second SiGe-based material is selectively etched with respect to the other by utilizing a difference in incubation time until etching by gas is started, ,
The first SiGe-based material is a first film made of a SiGe film having a Ge concentration of 20 to 50 at%, and the second SiGe-based material has a Ge concentration of 0 to 20 at% (excluding 0 at%). ), and is etched using a gas containing at least one fluorine _- containing gas selected from the group consisting of _ClF3 gas, F2 gas, and IF7 gas as an etching gas _. 1. An etching method characterized by selectively etching the first film with respect to the second film. An etching gas is supplied to an object to be processed having a first SiGe-based material and a second SiGe-based material having Ge concentrations different from each other, and one of the first SiGe-based material and the second SiGe-based material is supplied. is etched and the other is not substantially etched, and the purging of the processing space is repeated multiple times to etch one of the first SiGe-based material and the second SiGe-based material to the other. An etching method for selectively etching with respect to
The first SiGe-based material is a first film made of a SiGe film having a Ge concentration of 20 to 50 at%, and the second SiGe-based material has a Ge concentration of 0 to 20 at% (excluding 0 at%). ), and is etched using a gas containing at least one fluorine _- containing gas selected from the group consisting of _ClF3 gas, F2 gas, and IF7 gas as an etching gas _. 1. An etching method characterized by selectively etching the first film with respect to the second film. 3. The etching method according to claim 2, wherein one time of said etching treatment is 1 to 10 sec, and one time of said purge is 5 to 30 sec. 4. The etching method according to claim 1, wherein the etching temperature is 100[deg.] C. or higher. 5. The etching method according to claim 4, wherein the etching temperature is 100 to 125.degree. An etching gas is supplied in a low temperature range to an object to be processed having a first SiGe-based material and a second SiGe-based material having Ge concentrations different from each other, and the first SiGe-based material and the second SiGe-based material are formed. An etching method for selectively etching one of with respect to the other,
The first SiGe-based material is a first film made of a SiGe film having a Ge concentration of 20 to 50 at%, and the second SiGe-based material has a Ge concentration of 0 to 20 at% (excluding 0 at%). ), and is etched using a gas containing at least one fluorine _- containing gas selected from the group consisting of _ClF3 gas, F2 gas, and IF7 gas as an etching gas _. 1. An etching method characterized by selectively etching the first film with respect to the second film. 7. The etching method according to claim 6, wherein the etching temperature is 60[deg.] C. or less. 8. The etching method according to claim 7, wherein the etching temperature is 0 to 60.degree. 9. The etching method according to any one of claims 1 to 8, wherein the etching gas further comprises NH3 _gas . 10. The method according to any one of claims 1 to 9, wherein the object to be processed is formed by laminating the first film and the second film one or more times on a substrate. Etching method described. The object to be processed includes, on a substrate, a structure portion having the first film as an etching target, and a non-etching target SiGe having a Ge concentration equivalent to that of the first film provided outside the structure portion. and the second film provided as a protective layer for the film not to be etched is formed between the structure portion and the SiGe film not to be etched. The etching method according to any one of . 12. The etching method according to any one of claims 1 to 11 , wherein the etching pressure is 1.33 to 133 Pa. 13. The method according to claim 1, wherein the first film has a Ge concentration of 25-35 at %, and the second film has a Ge concentration of 5-15 at %. etching method.

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