TW201941283A - Etching method - Google Patents

Abstract

There is provided an etching method which includes: supplying an etching gas to a workpiece including a first SiGe-based material and a second SiGe-based material having different Ge concentrations; and selectively etching the first SiGe-based material and the second SiGe-based material with respect to the other using a difference in incubation time until the first SiGe-based material and the second SiGe-based material begin to be etched by the etching gas.

Description

   Etching method   

This disclosure relates to an etching method for etching SiGe-based materials.

In recent years, as a new semiconductor material other than silicon (hereinafter referred to as Si), a type of silicon germanium (hereinafter referred to as SiGe) is known. As a semiconductor element using this SiGe, a Si layer and a SiGe layer are laminated after being laminated. It is required to selectively etch the SiGe layer with respect to the Si layer or to selectively etch the Si layer with respect to the SiGe layer.

As a technique for selectively etching SiGe with respect to Si, it is known to use ClF ₃ and XeF ₂ as an etching gas (Patent Document 1), HF (Patent Document 2), and use NF ₃ gas and O ₂ gas. Plasma of mixed gas (Patent Document 3). Further, as a technique for selectively etching Si with respect to SiGe, a technique is known in which a gas containing germanium is added to an etching gas containing SF ₆ or CF ₄ and etching is performed (Patent Document 4).

Further, Patent Document 5 describes a technique that enables selective etching of SiGe to Si and selective etching of Si to SiGe by changing the ratio of F ₂ gas and NH ₃ gas.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Publication No. 2009-510750

Patent Document 2: Japanese Patent Application Laid-Open No. 2003-77888

Patent Document 3: Japanese Patent No. 6138653

Patent Document 4: Japanese Patent Application Publication No. 2013-225604

Patent Document 5: Japanese Patent Application Publication No. 2016-143781

In addition, all of the above-mentioned techniques are only selective etching of SiGe with respect to Si or selective etching of Si with SiGe, but recently, it has been gradually required that SiGe-based materials can be etched with high selectivity relative to the other There is a difference in Ge concentration, and the above-mentioned technique cannot sufficiently correspond to such etching.

Therefore, the present disclosure provides an etching method that can etch one of the SiGe-based materials with a different Ge concentration than the other with a high selectivity.

This aspect of the present invention relates to an etching method in which an etching gas is supplied to a subject having a first SiGe-based material and a second SiGe-based material that are different in Ge concentration from each other. The second SiGe-based material selectively etches one of the first SiGe-based material and the second SiGe-based material relative to the other due to a difference in latency between the etching time caused by the etching gas.

The present disclosure discloses another aspect of an etching method in which an etching gas is supplied to a subject having a first SiGe-based material and a second SiGe-based material that are different in Ge concentration from each other, to etch the first SiGe-based material and the second SiGe-based material. One of the 2SiGe-based materials is repeatedly etched several times without substantially etching the other etching time and the cleaning of the processing space, and the 1SiGe-based material is selectively etched with respect to the other One of the second SiGe-based materials.

Another aspect of the present disclosure relates to an etching method that supplies an etching gas in a low temperature region to a subject having a first SiGe-based material and a second SiGe-based material that are different in Ge concentration from each other. To selectively etch one of the first SiGe-based material and the second SiGe-based material.

According to the present disclosure, it is possible to etch one of the first SiGe-based material and the second SiGe-based material with a high selectivity while hardly etching the other.

1. 21‧‧‧ semiconductor substrate

11‧‧‧High Ge concentration SiGe film

12‧‧‧Low Ge concentration SiGe film

13‧‧‧ Etching Mask

30‧‧‧ layered structure

31‧‧‧High Ge concentration SiGe film

32‧‧‧Si film

33‧‧‧ Etching Mask

41‧‧‧Insulation film (Low-k film)

42‧‧‧Low Ge concentration SiGe film

43‧‧‧High Ge concentration SiGe film

100‧‧‧treatment system

105、105’‧‧‧Etching device

143, 143’‧‧‧‧ processing gas supply mechanism

175‧‧‧Fluorine gas supply source

W‧‧‧Semiconductor wafer (object to be processed)

FIG. 1 is a diagram schematically illustrating an etching method according to a first example of the first embodiment.

FIG. 2 is a diagram showing a relationship between an etching time and an etching amount of a Si-10% Ge film and a Si-30% Ge film at 80 ° C, 100 ° C, and 120 ° C.

FIG. 3 is an enlarged view of a part of FIG. 2.

FIG. 4 is a diagram schematically illustrating an etching method according to a first example of the second embodiment.

FIG. 5 is a graph showing the temperature dependence of the amount of etching when a Si film having a Ge concentration of 0% is etched with ClF ₃ gas.

FIG. 6 is a graph showing the temperature dependence of the etching amount when a SiGe film (Si-30% Ge film) having a Ge concentration of 30 at% is etched with ClF ₃ gas.

Figure 7 shows that when Si-10% Ge film and Si-30% Ge film are etched at 35 ° C in the low temperature region and 120 ° C in the high temperature region, the Si-30% Ge film is relative to the Si-10% Ge film. The etching selection ratio of the film is compared to the pattern.

FIG. 8A is a schematic cross-sectional view showing a first example of the structure of an object to be treated to which the first and second embodiments are applied, and is a view showing a state before etching.

FIG. 8B is a schematic cross-sectional view showing a first example of the structure of the object to be treated to which the first and second embodiments are applied, and is a view showing a state after etching.

FIG. 9A is a schematic sectional view showing a second example of the structure of the object to be treated to which the first and second embodiments are applied, and is a view showing a state before etching.

FIG. 9B is a schematic cross-sectional view showing a second example of the structure of the object to be treated to which the first and second embodiments are applied, and is a view showing a state after etching.

FIG. 10 is a schematic configuration diagram showing an example of a processing system equipped with an etching apparatus for implementing the first embodiment and the second embodiment.

11 is a cross-sectional view showing an example of an etching apparatus for performing an etching method according to the first example of the first and second embodiments.

FIG. 12 is a diagram showing an example of an etching apparatus for performing an etching method according to a second example of the first and second embodiments.

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 this embodiment, an etching gas (for example, a gas containing a fluorine-containing gas) is supplied to a substrate to be processed having a first SiGe-based material and a second SiGe-based material that differ in Ge concentration from each other, and the first SiGe Materials and the second SiGe-based materials have different temperatures between the latency time to the start of etching by the etching gas, and use the difference in latency to selectively etch the first SiGe-based material and the second SiGe-based material relative to the other. One of the materials. In this embodiment, the SiGe-based material also includes a case where Ge is 0% (that is, a case of Si).

The first example of this embodiment is to prepare a processing object having a first film and a second film, supply a fluorine-containing gas as an etching gas to the processing object, and selectively etch the first film with respect to the second film. The first film system is composed of SiGe which is a first SiGe-based material with a relatively high Ge concentration, and the second film system is composed of a SiGe film which is a second SiGe-based material with a relatively low Ge concentration or Si with 0% Ge Made of film. In addition to a fluorine-containing gas, an inert gas such as an Ar gas may be supplied. At this time, the second film is hardly etched, but the selection ratio of the first film to the second film is preferably 5 or more.

The fluorine-containing gas system may use ClF ₃ gas, F ₂ gas, IF ₇ gas, and the like.

At this time, when the above-mentioned fluorine-containing gas is used as the etching gas, the first film having a higher Ge concentration is easier to be etched than the second film having a lower Ge concentration, and therefore the chemically reactive The difference is that the first film is selectively etched relative to the second film, but especially in high temperature regions, the second film is also etched in the etching using only the difference in the chemical reactivity of the etching gas. Not good.

In contrast, in this example, in a predetermined temperature range, particularly in a high-temperature region as described below, selective etching is performed by using a difference in latency between the etching reactions of the first film and the second film. The latency time refers to the time after the etching gas is supplied until the etching reaction actually starts. As shown in Figure 1, the latency time (T2) of the second film with a low Ge concentration is higher than the latency time of the first film with a Ge concentration. (T1) To be long. By using this latency difference (ΔT), the etching of the second film can be sufficiently suppressed, and the first film can be etched to perform highly selective etching.

Such a difference in latency (ΔT) exists because the SiO ₂ film, which is a natural oxide film that is difficult to be etched by a fluorine-containing gas, is formed more on the surface of the second film than the first film. .

The latency time can be adjusted by the temperature of the object to be processed (etching temperature) at the time of etching, and is preferably set so that a sufficient latency time difference (△ T) can be formed between the first film and the second film. Etching temperature. The time required for the etching of the first film is more preferably equal to or less than the latency (T2) of the second film, that is, the latency period. This makes it possible to etch the first film with little selectivity and to etch the first film with respect to the second film with a high selectivity.

In this example, as described above, although the second film having a low Ge concentration allows a Si film of 0% Ge, it is more effective when both the first film and the second film are SiGe films. In addition, as a specific numerical value, the Ge concentration of the first film having a high Ge concentration is preferably in a range of 20 to 50 at%, more preferably 25 to 35 at%, and for example, 30 at%. The Ge concentration of the second film is preferably in the range of 0 to 20 at% (excluding 20 at%), more preferably 5 to 15 at%, and is, for example, 10 at%.

In this embodiment, the etching temperature is preferably a high temperature range of 100 ° C or higher, and more preferably 100 to 125 ° C. The optimal temperature is 120 ° C. When the SiGe film is etched with a fluorine-containing gas such as ClF ₃ gas, the lower the temperature, the easier it is to be etched, and the natural oxide film is also easily etched. Although it is different due to the quality of the SiGe film, near 80 ° C, in the SiGe film with a low Ge concentration, the natural oxide film on the surface will also be easily etched, and the latency will be shorter, making it difficult to find the difference in latency. In contrast, in the high temperature region above 100 ° C, the natural oxide film on the surface of the SiGe film and the etching rate of the film itself will decrease, and even the natural oxide film in the SiGe film with a low Ge concentration is difficult to be etched. The latency of the second film with a low Ge concentration is increased, and the latency difference is lengthened. In particular, at around 120 ° C, a SiGe film system with 10at% Ge can sufficiently extend the latency to 10min, and until the etching time is about 10min, the second film with a low Ge concentration is hardly etched, and high selection is possible. For example, the first film having a high Ge concentration of 30 at% is etched. However, when the etching temperature is 130 ° C or higher, the first film having a high Ge concentration also becomes difficult to be etched.

The pressure during etching is preferably in the range of 10 to 1000 mTorr (1.33 to 133 Pa), and is, 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 an etching gas, and a SiGe film (Si-10% Ge film) with a Ge concentration of 10at% and a SiGe film (Si-30% Ge film) with a Ge concentration of 30at% will be used. The relationship between the etching time and the etching amount was determined by changing the etching temperature to 80 ° C, 100 ° C, and 120 ° C. The results are shown in FIG. 2. FIG. 3 is a diagram showing an enlarged portion of FIG. 2.

As shown in these figures, it is known that any one of the Si-10% Ge film and the Si-30% Ge film will etch more at 80 ° C. At any temperature, the Si-30% Ge film The amount of etching will be more than that of Si-10% Ge film. In addition, it was learned that at 80 ° C, the latency time of either the Si-10% Ge film or the Si-30% Ge film will be short, and the Si-10% Ge film will also begin to etch in a short time, at 600sec ( The etching amount of the Si-10% Ge film of 10 min) is 10 nm or more. On the other hand, it was found that at an etching temperature of 100 ° C., the latency time of the Si-10% Ge film was 100sec, and etching using the difference between the latency time of the Si-30% Ge film and the Si-30% Ge film was performed. In addition, when the etching time is 600 sec (10 min), the etching amount of the Si-10% Ge film is about 3nm, and the etching of the Si-10% Ge film can be suppressed to etch the Si-30% Ge film. In addition, at an etching temperature of 120 ° C, the latency time of the Si-10% Ge film is 600sec (10min). It is confirmed that the selectivity ratio to the Si-10% Ge film can be infinitely large over a long period of 600sec. To etch a Si-30% Ge film. In addition, at an etching temperature of 120 ° C., even if the etching time is 1200 sec, the etching amount of the Si-10% Ge film is still about 5 nm less.

Next, a second example of this embodiment will be described. The second example is to prepare a processing object having a first film and a second film, supply a fluorine-containing gas and an NH ₃ gas as etching gases to the processing object, and selectively etch the second film with respect to the first film. The first film is composed of SiGe, which is a first SiGe-based material with a relatively high Ge concentration, and the second film is a SiGe film, which is a second SiGe-based material with a relatively low Ge concentration, or 0% Ge. It is composed of a Si film. That is, in contrast to the first example, the second film having a lower Ge concentration is selectively etched relative to the first film having a higher 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.

In this way, by adding NH ₃ gas as an etching gas, the difference in Ge concentration is reversed because by adding NH ₃ gas to a fluorine-containing gas, SiO _{2 with} a natural oxide film on the surface can be easily etched. The reason. Like the first example, a fluorine-containing gas can be ClF ₃ gas, F ₂ gas, IF ₇ gas, or the like. The ratio of the fluorine-containing gas to the NH ₃ gas is preferably in the range of 1/500 to 1.

In this example, the Ge concentration of the first film and the second film is the same as that of the first example, and is different only on the etched side. The same applies to the etching temperature, preferably 100 ° C or higher, more preferably 100 to 125 ° C, and most preferably 120 ° C.

<Second Embodiment>

Next, a second embodiment will be described.

In the present embodiment, an etching gas (for example, a gas containing a fluorine-containing gas) is supplied to a subject having a first SiGe-based material and a second SiGe-based material that differ in Ge concentration from each other to etch the first SiGe system. One of the materials and the second SiGe-based material, and the etching process and the cleaning of the processing space are repeated several times without substantially etching the other etching time, and the 1SiGe-based material is selectively etched with respect to the other One of the second SiGe-based materials. In this embodiment, the SiGe-based material also includes a case where Ge is 0% (that is, a case of Si).

The first example of this embodiment is to prepare a processed body having a first film and a second film. The first film is made of SiGe, which has a relatively high Ge concentration as the first SiGe material. The second film is made of SiGe. As the second SiGe-based material, a SiGe film having a relatively low Ge concentration or a Si film having 0% Ge is formed. As shown in FIG. 4, a fluorine-containing gas is supplied as an etching gas to the object to etch the first The film is subjected to a predetermined number of etching steps (S1) and a cleaning step (S2) of the processing space that are repeated for substantially no etching time of the second film. The cleaning step (S2) of the processing space can be performed by evacuating a processing container that is divided out of the processing space. An inert gas, which is a flush gas, may be supplied to the processing space together with evacuation. In this manner, by repeating the predetermined etching step (S1) and the cleaning step (S2), the second film can be hardly etched, and the first film can be etched at a high selectivity with respect to the second film. 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.

The single etching step (S1) is preferably performed during the second film latency period, and is completed during the period during which the first film is etched. Thereby, even if the etching step (S1) is repeated, the natural oxide film on the second surface is hardly etched, and only the first film can be etched repeatedly to achieve a desired etching amount. Therefore, in this example, even if the difference in latency between the first film and the second film is small, since the first film can still be etched substantially by a desired amount, the temperature limit is wider than in the first example.

Similar to the first embodiment, the fluorine-containing gas can be ClF ₃ gas, F ₂ gas, IF ₇ gas, or the like. In addition to the fluorine-containing gas, an inert gas such as an Ar gas may be supplied.

As described above, although the second film having a low Ge concentration allows a Si film of 0% Ge, it is more effective when both the first film and the second film are SiGe films. In addition, as a specific numerical value, the Ge concentration of the first film having a high Ge concentration is preferably in a range of 20 to 50 at%, more preferably 25 to 35 at%, and for example, 30 at%. The Ge concentration of the second film is preferably in the range of 0 to 20 at% (excluding 20 at%), more preferably 5 to 15 at%, and is, for example, 10 at%.

Although the limit of the etching temperature is wider than that of the first embodiment as described above, the etching temperature in this example is preferably 100 ° C or higher, and more preferably 100 to 125 ° C. The optimal temperature is 120 ° C.

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

Next, a second example of this embodiment will be described. The second example is to prepare a processing object having a first film and a second film, and supply a fluorine-containing gas and an NH ₃ gas as an etching gas to the processing object to etch the second film, and perform a predetermined number of iterations substantially. An etching process that does not etch the etching time of the first film and a process of cleaning the processing space. The first film is made of SiGe, which is a first SiGe-based material, and the Ge concentration is relatively high. It is composed of a SiGe film of 2SiGe-based material and a relatively low Ge concentration or a Si film with 0% Ge. That is, in contrast to the first example, the second film having a lower Ge concentration is selectively etched relative to the first film having a higher 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.

In this manner, the difference in Ge concentration is reversed by adding NH ₃ gas as an etching gas, and using the same principle as in the second example of the first embodiment.

<Third Embodiment>

Next, a third embodiment will be described.

In this embodiment, an etching gas (for example, a gas containing a fluorine-containing gas) is supplied to a subject having a first SiGe-based material and a second SiGe-based material that have different Ge concentrations from each other in a low temperature region, and One of the first SiGe-based material and the second SiGe-based material is selectively etched compared to the other. This embodiment is different from the first embodiment in which the difference in latency is used, and the selectivity is ensured by the difference between the etching amounts of the two. In addition, in this embodiment, the SiGe-based material system includes a case where Ge is 0% (that is, a case of Si).

The first example of this embodiment is to prepare a processing object having a first film and a second film, supply a fluorine-containing gas as an etching gas to the processing object, and selectively etch the first film with respect to the second film. The first film system is composed of SiGe which is a first SiGe-based material with a relatively high Ge concentration, and the second film system is composed of a SiGe film which is a second SiGe-based material with a relatively low Ge concentration or Si with 0% Ge Made of film. In addition to a fluorine-containing gas, an inert gas such as an Ar gas may be supplied. 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.

The fluorine-containing gas system may use ClF ₃ gas, F ₂ gas, IF ₇ gas, and the like.

At this time, when the above-mentioned fluorine-containing gas is used as the etching gas, the first film having a higher Ge concentration is easier to be etched than the second film having a lower Ge concentration, and thus the difference in chemical reactivity can be taken into account. To selectively etch the first film with respect to the second film.

The pressure during the etching is preferably in a 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 region, preferably 60 ° C or lower, and more preferably in a range of 0 to 60 ° C.

The reason will be described below based on FIG. 5 and FIG. 6 in which the relationship between the temperature and the etching amount is actually grasped.

FIG. 5 is a graph showing the temperature dependence of the amount of etching when a Si film having a Ge concentration of 0% is etched with a ClF ₃ gas containing fluorine, and shows the etching time at each temperature of 20 to 120 ° C. The etching amount tends to be 30 sec. The etching conditions of the Si film are 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 the figure, the etching amount of the Si film is not linear with respect to temperature, but there is a tendency that the etching amount in the middle temperature range around 80 ° C is large, and the etching amount tends to be less in the temperature range of 60 ° C or lower and 100 ° C or higher. In particular, the etching amount of the Si film becomes smaller at 60 ° C or lower. This tendency should be due to the strong influence of the chemisorption characteristics during the Si film etching under ClF ₃ gas. This tendency should also be the same in a SiGe film with a small amount of Ge (for example, a Si-10% Ge film).

On the other hand, FIG. 6 is a graph showing the temperature dependence of the etching amount when the SiGe film (Si-30% Ge film) having a Ge concentration of 30 at% is etched with ClF ₃ gas, and it is shown in the range of 20 to 120. The etching amount at the time of etching at each temperature of 30 degreeC was 30sec. In addition, the etching conditions of the Si-30% Ge film are 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 can be observed that the Si-30% Ge film system has strong physical adsorption characteristics, and the etching amount is linear with respect to temperature, and it can be observed that the lower the temperature, the more the etching amount tends to increase.

From Figs. 5 and 6, it can be understood that the etching amount of Si-30% Ge film will increase, and the etching amount of Si film will decrease. At low temperature below 60 ℃, compared with high temperature The Si-30% Ge film's etching selection ratio relative to Si can be increased, and its value will tend to be lower as the temperature decreases. As shown in FIG. 7 below, the etching selectivity ratio of the Si-30% Ge film to the Si-10% Ge film showing a similar tendency to the etching of the Si film is a high value of 20 or more. Although figures 5 and 6 only have data up to 20 ° C, from the tendency of these figures, a high selection ratio should be obtained at least up to 0 ° C. In this way, at a low temperature range of preferably 60 ° C, more preferably 0 to 60 ° C, and further 20 to 60 ° C, it can be compared with SiGe, which has a relatively low Ge concentration (also contains 0%). The second film formed does not use the latency difference, but etches the first film made of SiGe having a relatively high Ge concentration with a very high selection ratio.

In addition, although the temperature of the Si-30% Ge film will decrease as the temperature becomes higher, which will have an adverse effect on the etching selection ratio of the Si-30% Ge film relative to the Si film, the etching amount of the Si film is at 100 ° The above will be lower than around 80 ℃. Therefore, even in a high-temperature region of 100 ° C. or higher, the etching selection of the Si-30% Ge film can be made higher than that of the Si film without using the latency difference. However, as described in the first embodiment, the first film can be etched with higher selectivity than the second film by using a difference in latency in a high temperature region.

Next, the experimental results of the first example of the third embodiment will be described.

First, a ClF ₃ gas is used as an etching gas. For a SiGe film (Si-10% Ge film) with a Ge concentration of 10 at% and a SiGe film (Si-30% Ge film) with a Ge concentration of 30 at%, Etching is performed at 35 ° C in a low temperature region and 120 ° C in a high temperature region. FIG. 7 shows the case where the etching amount of the Si-30% Ge film at this time is taken as the horizontal axis, and the etching amount of the Si-10% Ge film is taken as the vertical axis, and the etching is performed at 35 ° C and at 120 ° C. Schematic of the case where etching is performed. The etching conditions at this time are 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 the figure, the etching selectivity ratio of the Si-30% Ge film to the Si-10% Ge film is 24.6 at 35 ° C and 11.2 at 120 ° C. From this result, it was confirmed that a high etching selectivity ratio of 20 or more was obtained in the low temperature region, and an etching selectivity ratio of 10 or more was obtained in the high temperature region, although not as high as in the low temperature region.

<Structural example of a to-be-treated body to which the first and second embodiments are applied>

Next, an example of the structure of the object to be processed to which the first and second embodiments are applied will be described. The 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, a SiGe film (for example, a Ge concentration of 30 at%) 11 having a high Ge concentration as a first film as an etching target is formed on a semiconductor substrate 1, such as a Si substrate, as a first film. A two-layer structure with a low Ge concentration of a SiGe film (eg, a Ge concentration of 10 at%) 12. Specifically, the low-Ge-concentration SiGe film 12 and the high-Ge-concentration SiGe film 11 are sequentially laminated on the semiconductor substrate 1, and the uppermost layer is the low-Ge-concentration SiGe film 12, and for example, SiO ₂ An etching mask 13 made of a film. The number of laminations of the low Ge concentration SiGe film 12 and the high Ge concentration SiGe film 11 may be one or more.

In this state, the object to be processed is maintained 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 as in the first example of the second embodiment, by repeating The supply and flushing of the fluorine-containing gas etches the high-Ge-concentration SiGe film 11 to a state such as that shown in FIG. 8B. At this time, the low Ge concentration SiGe film 12 is hardly etched. Although a part of the high Ge concentration SiGe film 11 is etched in FIG. 8B, the entire etch may be performed. Alternatively, a Si film may be used instead of the low Ge concentration SiGe 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 SiGe film (for example, a Ge concentration) having a high Ge concentration is formed as a first film as an etching target through an insulating film (not shown) on a semiconductor substrate 21 such as a Si substrate. 30at%) 31 and the Si film 32 are laminated structures 30, on both sides of the laminated structure 30, at the portions corresponding to the source and the drain of the semiconductor substrate 21, through the insulating film 41 such as a low-k film It has a low-Ge-concentration SiGe film (for example, a Ge concentration of 10 at%) 42 serving as a protective layer, and a high-Ge-concentration SiGe film (for example, a Ge concentration of 30 at%) 43 provided on the outside thereof. The laminated structure 30 is a semiconductor film 21 in which a Si film 32 and a high Ge concentration SiGe film 31 are sequentially stacked. The uppermost layer is the Si film 32, and an etching mask made of, for example, a SiO ₂ film is formed thereon. Cover 33.

In this state, the object to be processed is maintained 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 as in the first example of the second embodiment, by repeating The supply and flushing of the fluorine-containing gas etches the high-Ge-concentration SiGe film 31, and becomes, for example, the state shown in FIG. 9B. At this time, the low Ge concentration SiGe film 42 is hardly etched, and has a function as a protective layer, so that the high Ge concentration SiGe film (for example, Ge concentration 30at%) 43 is not etched.

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

<Processing system>

Next, an example of a processing system equipped with an etching apparatus for implementing 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 and unloading a wafer W having a structure shown in the structure example described above, two loading interlocking chambers 103 provided adjacent to the loading / unloading unit 102, and adjacent installations. A heat treatment device 104 for heat-treating the wafer W in each loading interlock chamber 103; an etching device 105 adjacent to each heat treatment device 104 for etching the wafer W; and a control unit 106.

The loading / unloading unit 102 includes a transfer chamber 112 in which a first wafer transfer mechanism 111 for transferring a wafer W is provided. The first wafer transfer mechanism 111 includes two transfer arms 111 a and 111 b that hold the wafer W slightly horizontally. A mounting table 113 is provided on the side of the transfer chamber 112 in the longitudinal direction. This mounting table 113 is a carrier C to which, for example, three wafers W for storing FOUPs can be connected. An alignment chamber 114 is provided adjacent to the transfer chamber 112 to perform alignment of the wafer W.

In the loading / unloading unit 102, the wafer W is held by the transfer arms 111a and 111b, and driven by the first wafer transfer mechanism 111, the wafer W is linearly moved or lifted in a slightly horizontal plane to be transferred to a desired level. position. Then, the transfer arms 111a and 111b are moved forward and backward with respect to the carrier C, the positioning chamber 114, and the loading interlocking chamber 103 of the mounting table 113, respectively, to carry out the loading and unloading.

Each loading interlocking chamber 103 is connected to each of the transfer chambers 112 with a gate valve 116 interposed therebetween. A second wafer transfer mechanism 117 for transferring the wafer W is provided in each of the loading interlock chambers 103. The loading interlocking chamber 103 is configured to be evacuable to a predetermined vacuum degree.

The second wafer transfer mechanism 117 has a multi-joint arm structure and has a pick-up unit that holds the wafer W slightly horizontally. In this second wafer transfer mechanism 117, the picker is placed in the loading interlocking chamber 103 in a state where the multi-joint arm is contracted, and the multi-joint arm is extended to allow the picker to reach the heat treatment. The device 104 can be further extended to reach the etching device 105, and the wafer W can be transferred between the loading interlock chamber 103, the heat treatment device 104, and the etching device 105.

The control unit 106 is typically composed of a computer, and includes: a main control unit having a CPU that controls each constituent unit of the processing system 100; an input device (keyboard, mouse, etc.); an output device (printer, etc.); and a display Devices (displays, etc.); and memory devices (memory media). The main control unit of the control unit 106 allows the processing system 100 to perform a predetermined action based on, for example, a processing recipe stored in a storage medium built in the storage device or a storage medium provided in the storage device.

In such a processing system 100, the wafer W having the above-mentioned structure is stored in a plurality of carriers C and transferred to the processing system 100. In the processing system 100, one wafer is transferred from the carrier C of the loading / unloading unit 102 with one of the transfer arms 111a and 111b of the first wafer transfer mechanism 111 in a state where the atmospheric-side gate valve 116 is opened. W is transferred to the load interlocking chamber 103 and is received to the picker of the second wafer transfer mechanism 117 in the load interlocking chamber 103.

After that, the atmospheric-side gate valve 116 is closed to evacuate the vacuum in the loading interlocking chamber 103, and then the gate valve 154 is opened to extend the picker to the etching device 105 to carry the wafer W toward the etching device 105.

After that, the picker is returned to the loading interlocking chamber 103, and the gate valve 154 is closed, and an etching process such as a high Ge concentration SiGe film is performed in the etching apparatus 105 by the above-mentioned etching method.

After the etching process is completed, the gate valves 122 and 154 are opened, and the wafer W after the etching process is transferred to the heat treatment apparatus 104 by the picker of the second wafer transfer mechanism 117 to remove the etching residue and the like by heating.

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

In addition, if it is not necessary to remove the etching residue, etc., the heat treatment device 104 may not be provided. In this case, as long as the pick-up device of the second wafer transfer mechanism 117 can be used, the wafer W after the etching process is returned to the loading mutual The lock chamber 103 may be returned to the carrier C by any of the transfer arms 111 a and 111 b of the first wafer transfer mechanism 111.

<Etching Device>

Next, an example of an etching apparatus 105 for performing 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 device 105. As shown in FIG. 11, the etching apparatus 105 includes a chamber 140 as a sealed structure of a processing container that defines a processing space. The chamber 140 is provided with a wafer W placed thereon to be placed in a slightly horizontal state. Set the stage 142. The etching device 105 includes a gas supply mechanism 143 that supplies an etching gas to the chamber 140 and an exhaust mechanism 144 that exhausts the inside of the chamber 140.

The chamber 140 is configured by a chamber body 151 and a cover portion 152. The chamber body 151 has a substantially cylindrical side wall portion 151 a and a bottom portion 151 b, and an upper portion thereof becomes an opening, and this opening is closed by a cover portion 152. The side wall portion 151 a and the cover portion 152 are sealed by a sealing member (not shown) to ensure air-tightness in the chamber 140.

The cover portion 152 includes a cover member 155 that constitutes the outside, and a shower head 156 that is fitted into the inside of the cover member 155 and is provided so as to face the mounting table 142. The shower head 156 includes a body 157 having a cylindrical side wall 157a and an upper wall 157b, and a shower plate 158 provided at the bottom of the body 157. A space 159 is formed between the body 157 and the shower plate 158.

The cover member 155 and the upper wall 157b of the main body 157 are formed with a gas introduction path 161 that passes through the space 159. The gas introduction path 161 is a fluorine-containing gas supply pipe 171 connected to a gas supply mechanism 143 described below.

The shower plate 158 is formed with a plurality of gas ejection holes 162, and the gas introduced into the space 159 is ejected from the gas ejection holes 162 into the space in the chamber 140 via the gas supply pipe 171 and the gas introduction path 161.

The side wall portion 151 a is provided with a carry-out inlet 153 for carrying in and out the wafer W between the side wall portion 151 a and the heat treatment apparatus 104. The carry-out inlet 153 can be opened and closed by a gate valve 154.

The mounting table 142 is substantially circular in plan view, and is fixed to the bottom 151 b of the cavity 140. A temperature regulator 165 is provided inside the mounting table 142 to regulate the temperature of the mounting table 142. The temperature regulator 165 is provided with a pipe that circulates, for example, a medium for temperature adjustment (such as water), and the temperature of the mounting table 142 can be adjusted by exchanging heat with the medium for temperature adjustment that flows through the pipe. The temperature control of the wafer W on the mounting table 142 is achieved.

The gas supply mechanism 143 is 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, and these are respectively connected to a fluorine-containing gas supply pipe 171 and one end of the inert gas supply pipe 172. The fluorine-containing gas supply piping 171 and the inert gas supply piping 172 are provided with a flow controller 179 that performs opening and closing operations and flow control of the flow path. The flow controller 179 is configured by, 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. The other end of the inert gas supply pipe 172 is connected to a fluorine-containing gas supply pipe 171.

Therefore, the fluorine-containing gas system is supplied from the fluorine-containing gas supply source 175 to the shower head 156 through the fluorine-containing gas supply pipe 171, and the inert gas system is supplied from the inert gas supply source 176 through the inert gas supply pipe 172. And the fluorine-containing gas supply pipe 171 to be supplied to the shower head 156, and these gases are ejected toward the wafer W in the chamber 140 from the gas discharge hole 162 of the shower head 156.

The fluorine-containing gas in these gases is a reaction gas, and an inert gas is used as a diluent gas and a flush gas. The desired etching performance can be obtained by separately supplying a fluorine-containing gas or mixing and supplying a fluorine-containing gas with an inert gas.

The exhaust mechanism 144 has an exhaust pipe 182 which is connected to the exhaust port 181 formed by the bottom 151b of the chamber 140, and further has an exhaust pipe 182 provided in the exhaust pipe 182 and used to control the pressure in the chamber 140. An automatic pressure control valve (APC) 183 and a vacuum pump 184 for exhausting the inside of the chamber 140.

The side wall of the chamber 140 is provided with two capacitive vacuum gauges 186 a and 186 b so as to be inserted into the chamber 140 as a pressure gauge for measuring the pressure in the chamber 140. Capacitive vacuum gauge 186a is for high pressure, and capacitive vacuum gauge 186b is for low pressure. A temperature sensor (not shown) that detects the temperature of the wafer W is provided near the wafer W placed on the mounting table 142.

In such an etching apparatus 105, the wafer W having the above-mentioned structure is carried into a chamber 140 and placed on a mounting table 142. Then, the pressure in the chamber 140 is set to a range of 10 to 1000 mTorr (1.33 to 133 Pa), for example, 120 mTorr. The wafer W is preferably set to 100 ° C or higher by the temperature regulator 165 of the mounting table 142, and more preferably The temperature is 100 ~ 125 ℃, and the best temperature is 120 ℃.

Then, when etching is performed by the first example of the first embodiment, a fluorine-containing gas (for example, ClF ₃ gas) is preferably supplied into the chamber 140 at a flow rate of 1 to 100 sccm to etch a high Ge concentration SiGe. membrane. Thereby, a low Ge concentration SiGe film or a Si film is hardly etched, and a high Ge concentration SiGe film can be etched with a high selection ratio relative to these. In this case, an inert gas such as an Ar gas may be supplied together with the fluorine-containing gas at a flow rate of, for example, 100 to 1000 sccm. After the etching is completed, the inside of the chamber 140 is purged with a purge gas, and the wafer W is carried out from the chamber 140.

When the etching is performed by the first example of the second embodiment, the fluorine-containing gas (for example, ClF ₃ gas) is preferably supplied into the chamber 140 at a flow rate of 1 to 100 sccm, so as to etch a high Ge concentration. The etching process of the SiGe film and the cleaning process of vacuuming or vacuuming and supplying an inert gas to flush the processing space in the chamber 140 are performed to etch a high Ge concentration SiGe film with a desired amount of etching. Thereby, a low Ge concentration SiGe film or a Si film can be hardly etched, and a high Ge concentration SiGe film can be etched with a high selection ratio relative to these. At this time, in the etching step, an inert gas such as an Ar gas may be supplied together with the fluorine-containing gas at a flow rate of, for example, 100 to 1000 sccm. After the etching is completed, the inside of the chamber 140 is purged with a purge gas, and the wafer W is carried out from the chamber 140.

When etching is performed by the second example of the first and second embodiments, the etching is performed by the etching device 105 'shown in Fig. 12. The etching apparatus 105 'uses a gas supply mechanism 143' having a fluorine-containing gas supply source 175, an inert gas supply source 176, and an NH ₃ gas supply source 177 instead of the gas supply mechanism 143 of the etching apparatus 105 of Fig. 11. The NH ₃ gas supply source 177 is connected to one end of an NH ₃ gas supply pipe 173. The other end of the NH ₃ gas supply pipe 173 is connected to a fluorine-containing gas supply pipe 171. The NH ₃ gas supply pipe 173 is provided with a flow controller 179 in the same manner as the fluorine-containing gas supply pipe 171 and the inert gas supply pipe 172.

By using the etching device 105 'in this way, it can be seen from the two structural examples shown in FIGS. 5 and 6 that the SiGe film having a high Ge concentration and the SiGe film (or Si film) having a low Ge concentration can be in an opposite state. The structured wafer W uses a fluorine-containing gas and an NH ₃ gas to etch a low-Ge-concentration SiGe film (or Si film) with a high selectivity relative to a high-Ge-concentration SiGe film.

<Other applicable>

Although the embodiments have been described above, the embodiments disclosed this time should be illustrative and not restrictive in all points of view. The above-mentioned embodiment can be omitted, replaced, or changed in various forms without exceeding the scope of the attached patent application and its gist.

For example, the structure of the object to be processed in the above embodiment is merely an example, as long as it is a object having a first SiGe-based material and a second SiGe-based material (including a case where Ge is 0%) having different Ge concentrations from each other. Is applicable. The structure of the above-mentioned processing system or individual device is merely an example, and the etching method of the present invention can be implemented by variously configured systems or devices.

Claims (17)

    An etching method in which an etching gas is supplied to a subject having a first SiGe-based material and a second SiGe-based material that are different in Ge concentration from each other, and the first SiGe-based material and the second SiGe-based material are used. One of the first SiGe-based material and the second SiGe-based material is selectively etched relative to the other due to a difference in latency between etching by the etching gas.         An etching method is to supply an etching gas to a subject having a first SiGe-based material and a second SiGe-based material that are different in Ge concentration from each other, to etch one of the first SiGe-based material and the second SiGe-based material. Or, the etching process and the cleaning of the processing space that do not substantially etch another etch time are repeated several times, while one of the 1SiGe-based material and the second SiGe-based material is selectively etched relative to the other. By.         For example, the application of the etching method in the second item of the patent scope, wherein the time for one etching process is 1 to 10 sec, and the time for one flushing process is 5 to 30 sec.         For example, the etching method according to any one of claims 1 to 3, wherein the temperature during the etching is 100 ° C or higher.         For example, the application of the etching method in the fourth item of the patent scope, wherein the temperature during the etching is 100 ~ 125 ° C.         An etching method in which a processing object having a first SiGe-based material and a second SiGe-based material that differ in Ge concentration from each other is supplied with an etching gas in a low temperature region, and the etching is selectively performed with respect to the other One of the first SiGe-based material and the second SiGe-based material.         For example, the etching method of the sixth aspect of the patent application, wherein the temperature during the etching is below 60 ° C.         For example, the etching method according to item 7 of the patent scope, wherein the temperature during the etching is 0 ~ 60 ° C.         For example, the etching method according to any one of claims 1 to 3, 6 to 8, wherein the etching gas system contains a fluorine-containing gas.     For example, the etching method according to item 9 of the patent application range, wherein the fluorine-containing gas system is selected from at least one group consisting of ClF ₃ gas, F ₂ gas, and IF ₇ gas.     For example, the etch method for item 9 in the patent application range, wherein the first SiGe-based material is a first film composed of a SiGe film with a relatively high Ge concentration, and the second SiGe-based material is a SiGe film with a relatively low Ge concentration or The second film made of a Si film is selectively etched with respect to the second film by using a fluorine-containing gas as an etching gas.     For example, the etch method for item 9 in the patent application range, wherein the first SiGe-based material is a first film composed of a SiGe film with a relatively high Ge concentration, and the second SiGe-based material is a SiGe film with a relatively low Ge concentration or The second film made of the Si film is selectively etched with respect to the second film by using a fluorine-containing gas and an NH ₃ gas as the etching gas.     For example, the etching method according to the eleventh aspect of the patent application, wherein the system to be processed is configured such that the first film and the second film are laminated on the substrate more than once.         For example, the etching method according to item 11 of the patent application scope, wherein the system to be processed is formed on the substrate with a structure portion having the first film as an object to be etched; the structure portion is provided outside the structure portion, and has A non-etching target SiGe film having the same Ge concentration; and the second film provided between the structure portion and the non-etching target SiGe film as a protective layer of the non-target film.         For example, the etching method of any of items 1 to 3, 6 to 8 in the scope of patent application, wherein the pressure during etching is 1.33 ~ 133Pa.         For example, the etching method according to item 11 of the patent application range, wherein the Ge concentration of the first film is 20 to 50 at%, and the Ge concentration of the two films is 0 to 20 at%.         For example, the etching method of the 16th aspect of the patent application, wherein the Ge concentration of the first film is 25 to 35 at%, and the Ge concentration of the second film is 5 to 15 at%.