KR100870914B1 - Dry etch method for silicon oxide - Google Patents

Abstract

The method for dry-etching of the silicon oxide film is provided to etch efficiently the silicon oxide film in the high etch speed. The silicon oxide film includes at least a thermal oxide film and SOD(Spin On Dielectric) oxide film. The etching gas is the mixing gas of the mixing gas of the HF gas and alkylamine or the HF gas and ammonia gas and isopropyl alcohol(IPA). A step is for producing the etching by-product on the substrate while etching the silicon oxide film(S2). The post-annealing step is for increasing the substrate temperature to remove the etching by-product from the substrate(S3). The etching and post- annealing step are performed by the in-situ. The chamber pressure in the dry etch is 10 mTorr or 150 Torr.

Description

Dry etch method for silicon oxide

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of dry etching a silicon oxide film commonly formed for manufacturing a semiconductor device. The technical field of the present invention may be broadly defined as removing a silicon oxide film formed on a substrate by an etching gas.

In general, the manufacturing process of a semiconductor device is a process of realizing an electronic circuit that performs a certain function by combining thin films, such as conductive films, semiconductor films, and insulating films, having different properties on a substrate, by combining the order of stacking and the shape of a pattern. I can speak. Accordingly, in the semiconductor device manufacturing process, deposition and etching of various thin films are repeatedly performed.

Among various thin films, in particular, the silicon oxide film is widely used as an insulating film because it has excellent compatibility with silicon commonly used as a substrate, is easy to form by a method such as thermal oxidation, and is easy to handle. Conventionally, the silicon oxide film is etched by wet etching using HF diluent or BOE (buffered oxide etchant), but as the design rule of the semiconductor device decreases, a dry etching method for forming a finer pattern has been proposed. .

Conventional silicon oxide dry etching methods often use only HF gas. This method requires a slower etching rate compared to wet etching, resulting in a long process time and a reduction in throughput.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a silicon oxide dry etching method capable of efficiently etching a silicon oxide film at a considerably high etching rate.

In order to solve the above problems, one configuration of the dry etching method according to the invention is characterized in that the silicon oxide film is etched in the chamber using a mixed gas of HF gas and alkylamine as an etching gas.

In this case, the etching gas may further include isopropyl alcohol (IPA) gas, and may further include at least one inert gas selected from N ₂ , Ar, and He. The substrate temperature may be set in a range of 20 ° C. to 50 ° C. to facilitate the etching reaction of the etching gas. In dry etching, the lower the pressure inside the chamber, the longer the process time and the corrosion problem. Therefore, the pressure in the chamber during dry etching may be in the range of 10 mTorr to 150 Torr in consideration of this point.

Another configuration of the dry etching method according to the present invention is characterized by using a mixed gas of HF gas, NH ₃ gas and isopropyl alcohol (IPA) as an etching gas.

In this case, the etching gas may further include at least one inert gas selected from N ₂ , Ar, and He, and the flow ratio of the HF gas: NH ₃ gas: IPA and the inert gas may be 1: 0.5 to 2: 0.5. It may be set to ˜2, the internal pressure of the chamber during dry etching may be 10 mTorr to 150 Torr, the substrate temperature may be 20 ℃ to 50 ℃. In addition, a post heat step of removing the etching by-products from the substrate by raising the substrate temperature after dry etching may be further performed in-situ.

According to the present invention, by using a mixed gas of HF gas and an alkylamine or a mixed gas of HF gas, NH ₃ gas and IPA as an etching gas, the silicon oxide film formed on the substrate can be etched with a very fast etching rate.

This reduces process time, reduces component damage in the chamber, maximizes etching efficiency, reduces etching costs, and improves throughput. Furthermore, the high throughput enables the replacement of conventional wet etching.

In addition, by the dry etching, by adjusting the gas type, flow rate and etching time, it is easier to set the process conditions such as the etching rate than the wet etching, and the etching rate may be controlled by adjusting the flow rate and the mixing ratio.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape of the elements in the drawings and the like are exaggerated to emphasize a clearer description.

(Example)

1 is a configuration diagram showing an example of an etching apparatus for performing a silicon oxide dry etching method according to the present invention.

This etching apparatus 100 has a chamber 10 in which a substrate w is loaded. The susceptor 20, on which the substrate w is disposed, may be installed at a lower side of the inner space of the chamber 10 so as to be liftable. It is provided with a predetermined heater (not shown) to adjust the temperature inside the substrate w and / or the chamber 10. A showerhead 30 may be provided at an upper side of the inner space of the chamber 10 to inject an etching gas to etch the silicon oxide film formed on the substrate w.

On the other hand, the chamber 10 is further provided with a gas supply system 40 for introducing a flow-controlled etching gas into the chamber 10. In the present invention, instead of using HF gas alone, a mixed gas including at least HF gas is used as an etching gas. For example, when using a mixed gas of HF gas and alkylamine as an etching gas, the etching gas is used. The gas supply system 40 is independently provided for each component gas constituting the etching gas so that each component gas constituting the component gas is supplied and mixed in the chamber 10 without being mixed in advance. That is, although not shown in detail, the gas supply system 40 includes a gas supply path 40b connected to a supply source of each component gas (such as a gas cylinder or a canister containing a liquid), and a flow controller 40c and an MFC provided therein. ), And the like.

The shower head 30 is a means for injecting the component gas supplied from the gas supply system 40 into the chamber 10, and is not mixed in the shower head 30, but is mixed into the chamber 10 and mixed before being mixed. The post mix type is good for maintenance of the shower head 30. To this end, a dual type having at least two independent flow paths formed in the shower head 30 is adopted. Of course, the means for injecting the component gas into the chamber 10 may be in a form other than a showerhead, such as a gas nozzle or a gas jet plate, and a method of introducing each gas from the lower side rather than the upper side of the chamber 10. It may be.

1 is a single etching apparatus that processes one sheet at a time, but the present invention is not limited thereto, and a batch etching method capable of etching a plurality of substrates at once is possible. It can also be applied using a device. The substrate w is not limited to a semiconductor substrate such as a silicon wafer, but can also be applied to an LCD substrate, a glass substrate, and the like. In addition, the method may be applied to an etch back for removing a silicon oxide film on the entire surface without a mask, in addition to patterning for forming a mask with a photoresist or the like on a silicon oxide film and then etching a portion thereof. Furthermore, the method of the present invention can be applied without regard to the type of silicon oxide film, such as a natural oxide film, a thermal oxide film, a deposition oxide film, a chemical oxide film, and a coated oxide film.

Next, the method of the present invention that can be performed using the etching apparatus configured as described above will be described.

2 is a flowchart of a silicon oxide dry etching method according to a first embodiment.

The substrate w on which the silicon oxide film is formed is loaded into the chamber 10 of the etching apparatus 100 (step s1), and the silicon oxide film is prepared by using a mixed gas of HF gas and alkylamine peculiar to the present invention as an etching gas. Is etched (step s2). As the alkylamine, methylamine (CH ₃ NH ₂ ) having low carbon number and easily available may be used.

Specifically, the pressure inside the chamber 10 is adjusted to 10 mTorr to 150 Torr and the susceptor 20 temperature is set to 20 ° C. to 50 ° C., and then the substrate w is loaded. The susceptor 20 temperature is selected in the temperature range most suitable for the etching reaction of the etching gas. The susceptor 20 temperature becomes the substrate w temperature. In this case, the substrate w may be deposited on the high temperature susceptor 20 through a predetermined preheating step. However, in the reverse order, the substrate w may be first placed on the susceptor 20, and then the temperature of the substrate w may be adjusted by adjusting the temperature of the susceptor 20. In this case, the wall of the chamber 10 may be maintained at 50 ° C. to 100 ° C. to prevent the etching gas from condensing.

Then, the flow-controlled HF gas (anhydrous HF gas) from the HF gas supply system is introduced into the chamber 10, while the flow-controlled alkylamine is introduced into the chamber 10 from the alkylamine supply system. When the alkylamine to be used is a liquid, it can be introduced by evaporating through a suitable bubbling or vaporizer. The temperature of the gas supply passage 40b is adjusted to 50 ° C. to 150 ° C. so as not to liquefy on the gas supply passage 40b according to the characteristics of the source that is liquid at room temperature.

As such, the HF gas and the alkylamine separately introduced into the chamber 10 are mixed while being injected into the chamber 10 through the shower head 30 to form a silicon oxide film in which the mixed gas is formed on the substrate w. It is removed by etching. The temperature of the showerhead 30 may be maintained at 50 ° C. to 150 ° C. to prevent the etching gas from condensing.

In this case, the etching gas may further include an IPA gas, and may further include at least one inert gas selected from N ₂ , Ar, and He. When HF gas reacts with alkylamine and silicon oxide, water is formed. IPA evaporates the water quickly, which improves the overall reaction rate, which results in an increase in the etching rate. As a result of the experiment, the etching speed is 300 kW per minute. In addition, the inert gas does not act effectively by directly participating in the etching, but serves as a carrier gas so that each component gas constituting the etching gas can be delivered to the substrate w.

Although HF gas alone is not effective in removing silicon oxide film, it is possible to remove silicon oxide film efficiently by mixing alkylamine with it, and especially when IPA gas is further mixed, the reaction time can be shortened. Can kill.

In this manner, after the silicon oxide film is etched, the temperature of the substrate w is raised to a temperature between 80 ° C. and 200 ° C., for example, 100 ° C. while the substrate w is maintained in the chamber 10. The post-heat treatment step of removing the etching by-products attached to w) may be further performed in-situ (step s3). In this case, since the etching process and the necessary post process are performed in one chamber, the throughput is improved, and the chamber 10 is exited in the state where the by-products are removed. Therefore, in the process of moving to another post-treatment chamber without removing the by-products, there is an effect of preventing contamination that may occur in other parts such as a transfer module.

3 is a flowchart of a silicon oxide dry etching method according to a second embodiment.

The substrate w on which the silicon oxide film is formed is loaded into the chamber 10 of the etching apparatus 100 (step s11), and the silicon oxide film is formed by using a mixed gas of HF gas, NH ₃ gas and IPA as an etching gas. It is etched (step s12).

Specifically, the pressure inside the chamber 10 is adjusted to 10 mTorr to 150 Torr and the susceptor 20 temperature is set to 20 ° C. to 50 ° C., and then the substrate w is loaded. Or in reverse order. At this time, as mentioned above, the chamber 10 wall may be maintained at 50 ° C. to 100 ° C., and the showerhead 30 may be maintained at 50 ° C. to 150 ° C.

Then, the flow-controlled HF gas from the HF gas supply system is introduced into the chamber 10, while the flow-controlled NH ₃ gas from the NH ₃ gas supply system is introduced into the chamber 10. In addition, flow-controlled IPA is introduced into the chamber 10 from the IPA supply system. At room temperature, IPA is liquid, so it is introduced by evaporation through a suitable bubbling or vaporizer. And the temperature of the gas supply path 40b is adjusted to 50 to 150 degreeC so that it may not liquefy on the gas supply path 40b according to the characteristic of the supply source which is liquid at room temperature.

As such, HF gas, NH ₃ gas, and IPA introduced into the chamber 10 are mixed while being injected into the chamber 10 through the shower head 30, and the mixed gas is formed on the substrate w. The silicon oxide film can be etched and removed.

In this case, the etching gas may further include at least one inert gas selected from N ₂ , Ar, and He, and may be used as a carrier gas, and the inert gas may be supplied alone, but with HF gas or NH ₃ gas or IPA gas. You may mix and supply. The flow rates of the HF gas, the NH ₃ gas, the IPA, and the inert gas may be selected from 10 to 300 sccm, respectively, and, for example, 60 sccm may be supplied to set the flow rate ratio of the HF gas: NH ₃ gas: IPA and the inert gas to 1: 1. Can be set to 1. However, an appropriate flow rate ratio can be set at 1: 0.5-2: 0.5-2. By adjusting the flow rate ratio of each gas, it is possible to change the etching rate, the selection ratio and the like, all of which will belong to the scope of the present invention.

When HF gas, NH ₃ gas and silicon oxide film react, water is formed, and for the same reason as described above, water is removed by IPA and the overall reaction rate is improved, resulting in an increase in etching rate.

As described above, although HF gas alone is not effective in removing the silicon oxide film, the silicon oxide film can be efficiently removed by mixing NH ₃ gas, and the reaction time can be shortened by further mixing the IPA gas, thereby improving throughput. have. In this manner, after the silicon oxide film is etched, the post-heat treatment step may be further performed in situ as described above (step s13).

Experimental Example 1

By applying the present invention, the etching rate according to the type of silicon oxide film was tested.

First, a substrate on which a thermal oxide film was formed and a spin on dielectric (SOD) oxide film such as polysilazane (PSZ) were prepared. The thickness of the thermal oxide film was 1000 kPa and the thickness of the SOD oxide film was 1900 kPa.

The pressure inside the chamber 10 is 5 Torr, the temperature of the susceptor 20 is 40 ° C, the temperature of the wall of the chamber 10 is 75 ° C, and the temperature of the gas supply path 40c and the showerhead 30 is 100 ° C. Was used. Then, the dual type showerhead 30 was adopted and the spacing between the showerhead 30 and the substrate was maintained at 5 mm. The etching gas was a mixture of HF gas, NH ₃ gas and IPA, and N ₂ was supplied to IPA as a carrier gas. The flow rates of the HF gas, the NH ₃ gas, the IPA, and the N ₂ mixed gas were all supplied at 60 sccm, and the flow rate ratio of the HF gas: NH ₃ gas: IPA and the N ₂ mixed gas was set to 1: 1. The post heat treatment step was performed at a substrate temperature of 200 ° C. for 120 seconds. The etching time was changed from 30 seconds to 180 seconds, and the substrate subjected to post-heat treatment was taken out and the amount etched for 25 points was measured.

4 is a graph showing the results of the etching rate by applying the present invention.

In the graph, the x-axis shows the etching time, the y-axis shows the amount etched, and the etching rate of 327.6 당 / min for thermal oxide (-◆-) and 267.7 당 / min for SOD oxide (-■-) can be obtained. Results were obtained. This means that the etching efficiency is significantly improved compared with the case of etching using the conventional HF gas alone.

Experimental Example 2

Next, the selectivity according to the type of silicon oxide film was tested by applying the method according to the comparative example and the present invention.

First, in order to apply the method according to the comparative example, a substrate on which a thermal oxide film was formed and a substrate on which an SOD oxide film was formed were prepared. The thickness of the thermal oxide film was 1000 GPa, the uniformity was 0.5%, the thickness of the SOD oxide film was 2000 GPa, and the uniformity was 17%.

The pressure inside the chamber 10 is 100 Torr, which is a high pressure condition, the temperature of the susceptor 20 is 38 ° C, the temperature of the wall of the chamber 10 is 75 ° C, and the temperature of the gas supply passage 40c and the showerhead 30 is 100 ° C. conditions were used. And, the space | interval between the showerhead 30 and the board | substrate was maintained at 5 mm. The etching gas was used only the HF gas and the NH ₃ gas flow rate of HF gas and NH ₃ gas was supplied to all 60 sccm, respectively. The post heat treatment step was performed for 120 seconds at a substrate temperature of 200 ° C., and the substrates subjected to post heat treatment were taken out and the amount of the etched time was measured for 25 points.

5 is a graph showing the selectivity according to the type of silicon oxide film by applying a comparative example that does not use IPA.

In the graph, the x-axis shows the type of silicon oxide film and the y-axis shows the etching rate. The etching rate of the thermal oxide film was 207 kW / min and the SOD oxide film of 175 kW / min. The etching rate of the thermal oxide film was larger than that of the SOD oxide film, and the etching rate of the thermal oxide film to the SOD oxide film was calculated to be 1: 0.85, indicating that there was a selectivity to the thermal oxide film.

Next, Figure 6 is shown with the results obtained in Experimental Example 1.

In the graph, the x-axis shows the type of silicon oxide film and the y-axis shows the etching rate. As shown in Experiment 1 for the thermal oxide film, the etching rate was 327.6 kV / min and the SOD oxide film was 267.7 kV / min. The etching rate of the thermal oxide film: SOD oxide film was calculated to be 1: 0.82, indicating that the selectivity difference was higher in the case of the present invention using IPA more than the comparative example.

This, of course, is a result of a given condition, and if the conditions such as the susceptor 20 temperature are changed differently, it is also possible to etch both the thermal oxide film and the SOD oxide film at a constant speed or a speed close thereto. For example, as the susceptor 20 is increased, the selectivity ratio of the SOD oxide to the thermal oxide is increased.

Experimental Example 3

The etching rate and the etching uniformity were tested by applying the method and the present invention according to the comparative example.

A substrate having a 1700 kPa SOD oxide film was prepared, and the pressure inside the chamber 10 was 100 Torr under high pressure, the temperature of the susceptor 20 was 36 ° C, the temperature of the wall of the chamber 10 was 75 ° C, and the gas supply path ( The temperature of 40c) and the showerhead 30 used 100 degreeC conditions. And the space | interval between the showerhead 30 and the board | substrate was maintained at 40 mm. The post heat treatment step was performed for 120 seconds at a substrate temperature of 200 ° C., and the substrates subjected to post heat treatment were taken out and the amount of the etched time was measured for 25 points.

In the method according to the comparative example, only HF gas and NH ₃ gas were used as etching gas, and the flow rates of HF gas and NH ₃ gas were respectively 60 sccm. In the method according to the present invention, a mixed gas of HF gas, NH ₃ gas, and IPA was used as an etching gas, and N ₂ was mixed and supplied to IPA as a carrier gas. The flow rates of the HF gas, the NH ₃ gas, the IPA, and the N ₂ mixed gas were all supplied at 60 sccm, and the flow rate ratio of the HF gas: NH ₃ gas: IPA and the N ₂ mixed gas was set to 1: 1.

7 is a result graph showing an etching rate and an etching uniformity when the method according to the comparative example and the present invention are applied.

In the graph, the y-axis shows the etch rate and etch uniformity. According to the comparative example, the etching rate was 112.7 kPa / min, and in the present invention, the etching rate was 202.7 kPa, indicating that the months of the present invention had a high etching rate. Furthermore, in the etching uniformity, the comparative example shows 17% and 13% of the present invention, indicating that the present invention is quickly and evenly etched.

In the above, the present invention has been described in detail with reference to some preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. It is obvious. Accordingly, all such modifications are intended to be included within the scope of this invention.

1 is a view of an etching apparatus capable of performing a dry etching method according to the present invention.

2 is a flowchart of a silicon oxide dry etching method according to a first embodiment.

3 is a flowchart of a silicon oxide dry etching method according to a second embodiment.

4 is a graph showing the results of experiments on the etching rate according to the type of silicon oxide film by applying the present invention.

5 is a result graph showing selectivity according to the type of silicon oxide film by applying a comparative example.

6 is a graph showing the selectivity according to the type of silicon oxide film to which the present invention is applied.

7 is a result graph showing an etching rate and an etching uniformity when the method according to the comparative example and the present invention are applied.

Claims (10)

delete delete delete delete In the method of dry etching the silicon oxide film formed on the substrate in the chamber, The silicon oxide film includes at least a thermal oxide film and a spin on dielectric (SOD) oxide film, While maintaining the substrate temperature at 20 ° C. to 50 ° C., a mixed gas of HF gas, NH ₃ gas, and isopropyl alcohol (IPA) is used as an etching gas, and at least one selected from N ₂ , Ar, and He in the etching gas. An inert gas may be further included, and the etch selectivity ratio of the thermal oxide film and the SOD oxide film may be set by setting a flow rate ratio of the HF gas: NH ₃ gas: IPA and the inert gas to 1: 0.5 to 2: 0.5 to 2. Generating an etch byproduct on the substrate while etching the silicon oxide film to be 0.82 to 1: 1; And A post heat treatment step of removing the etching byproduct from the substrate by raising the substrate temperature to a temperature between 80 ° C. and 200 ° C., The etching and the post-heat treatment step is a silicon oxide dry etching method, characterized in that to proceed in-situ. delete delete The method of claim 5, wherein the internal pressure of the chamber during dry etching is 10 mTorr to 150 Torr, silicon oxide film dry etching method. delete delete

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