TWI713099B - Treatment method for removing an oxide layer of an electrode and etching the electrode - Google Patents

Abstract

The present invention relates to a processing method for removing an oxide film of an electrode and etching the electrode using plasma and gas, and more particularly the processing method comprises removing an oxide film on the electrode formed a channel; and performing an etching process on the electrode from which the oxide film has been removed.

Description

Treatment method for removing electrode oxide layer and etching electrode

The invention relates to a method for removing the oxide film formed on an electrode by using plasma and gas, and processing the damaged part of the electrode through an etching process.

The integrated circuit is manufactured through a process of forming a complex patterned material layer on the surface of the substrate. In order to form a patterned substance on the substrate, a controlled process for removing the substance is required. As such a process, there are a wet etching method using a chemical reaction (solution) and a dry etching method using a chemical reaction (gas).

On the other hand, wet etching includes transferring a photoresist pattern to a layer provided underneath, thinning the layer, or thinning the lateral dimension of features already present on the surface, and therefore is used for various purposes.

However, wet etching has major problems such as that the aspect ratio of the minute pattern increases, the surface cannot be etched uniformly, and the pattern collapses. In addition, among the micro patterns, dry etching has attracted much attention due to the limitations of the wet etching process and the low selectivity.

Dry etching includes vapor phase etching and plasma etching using the plasma state of reactive gas. Plasma etching in this dry etching can etch only the desired part, so it has good accuracy and can perform fine The advantages of patterning.

However, the plasma etching process has the following problems: the plasma energy will roughen the surface when etching the substrate, or the plasma-activated elements will adsorb or penetrate into the substrate surface to cause defects.

In addition, in the case of using an etching process for a structure with a high aspect ratio using a plasma process, there are problems as follows: For example, in the trench process for opening the gate electrode, the gas used in the plasma process The electrode is oxidized, and the performance of the device is reduced.

As an existing document related to this, Korean Registered Patent No. 10-0525119 (Publication Date: 2001.05.15.) discloses a method of forming a gate electrode, and discloses a method of forming a gate electrode in order to remove the oxide film formed on tungsten. The process of heat treatment in the environment, but there is a problem that it cannot be applied to channels, grooves and holes with high aspect ratio.

[The problem to be solved by the invention]

Therefore, the present invention provides an electrode treatment method that not only solves the problem caused by the oxide film formed on the electrode in a structure having a high aspect ratio, but also can remove the damaged portion from the electrode.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a processing method for removing an electrode oxide film and etching an electrode, which includes: removing the oxide film formed on the electrode from the electrode where the channel is formed; and removing the oxide film of the electrode Perform the steps of the etching process.

At this time, the processing method for removing the electrode oxide film and etching the electrode is characterized in that the oxide film removal process and the etching process are performed in the same chamber or cluster system.

The processing method for removing the electrode oxide film and etching the electrode is characterized in that the oxide film removal process and the etching process are performed in a vacuum and a non-oxidizing environment.

The processing method for removing the electrode oxide film and etching the electrode is characterized in that the electrode is formed of one or more selected from the group consisting of tungsten, titanium, polysilicon, and aluminum.

The processing method for removing the electrode oxide film and etching the electrode is characterized in that the removal of the oxide film is performed by using H ₂ /Ar gas, and the flow ratio of H ₂ to Ar in the H ₂ /Ar gas ( H ₂ /Ar) is 0.01 to 0.1.

The processing method for removing an electrode oxide film and etching an electrode is characterized in that the removal of the oxide film is performed using plasma and gas generated by radio frequency (RF) power.

The processing method for removing the electrode oxide film and etching the electrode is characterized in that the RF power applied when the oxide film is removed is 0.5 kW to 5.0 kW.

The processing method for removing an electrode oxide film and etching an electrode is characterized in that the removal of the oxide film is performed at a temperature exceeding normal temperature.

The processing method for removing the electrode oxide film and etching the electrode is characterized in that ClF ₃ gas is used to perform the etching process.

The processing method for removing the electrode oxide film and etching the electrode is characterized in that the etching process is performed by using plasma and gas generated by RF power.

The processing method for removing the electrode oxide film and etching the electrode is characterized in that the etching process is performed at a temperature below normal temperature.

The processing method for removing the electrode oxide film and etching the electrode is characterized in that the etching process is performed after the removal of the oxide film is performed until the electrode is opened.

The processing method for removing the electrode oxide film and etching the electrode is characterized in that: the greater the RF power used when removing the oxide film, the more the etching amount of the electrode in the etching process increases.

[Invention Effect]

According to the present invention, the oxide film formed on the electrode during the channel formation process can be removed by using plasma, so that problems such as the increase in the resistance of the electrode caused by the oxide film can be prevented.

In addition, the present invention can remove the damaged part of the electrode by using the gas etching process, so it can prevent the problem that other substances cannot be deposited on the electrode during the subsequent deposition process, and by removing the damaged part, it can solve the electrical conductivity of the electrode. The phenomenon of lowering the efficiency or preventing the lowering of the electrical conductivity can be used without malfunction and with reliability.

In addition, the processing method for removing the electrode oxide film and etching the electrode of the present invention can be performed in a vacuum environment and a non-oxidizing environment, so it is easy to control the electrode oxide film removal process and the etching process, and can prevent the electrode from reoxidizing.

In addition, a gas and plasma method is used and only radicals are used for the oxide film removal reaction, thereby minimizing physical damage and electrical damage caused by ions activated by the plasma.

With reference to the accompanying drawings, the above-mentioned objects, features, and advantages are described in detail, so that those of ordinary skill in the technical field to which the present invention belongs can easily implement the technical ideas of the present invention. In the description of the present invention, if it is determined that the detailed description of the known technology related to the present invention will unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. The same drawing symbols in the figures are used to indicate the same or similar constituent elements.

The present invention provides a processing method for removing electrode oxide film and etching electrode, which includes:

A step of removing the oxide film formed on the electrode from the electrode where the channel is formed; and

An etching process is performed on the electrode from which the oxide film is removed.

FIG. 1 is a sequence diagram showing a processing method for removing an electrode oxide film and etching an electrode according to the present invention. Hereinafter, referring to FIG. 1, the present invention will be described in detail.

The processing method for removing the oxide film of the electrode and etching the electrode of the present invention includes a step S100 of removing the oxide film formed on the electrode from the electrode where the channel is formed.

Usually, an electrode is formed on a substrate, an insulating film (SiO, SiO ₂ , Si ₂ N ₃ or a mixed layer thereof) is formed on the electrode, and a channel is formed through an etching process in order to open the electrode. However, there is a problem that the hard mask used to form the channel is provided on the insulating film, and the electrode that is opened when the channel is formed is oxidized due to the removal of the oxygen used in the hard mask.

Figures 2(a) and 2(b) are scanning electron micrographs showing the formation of an oxide film on the electrode opened after the process for forming the channel, and Figure 2(a) shows the formation on the electrode The channeled SEM photo, Figure 2(b) is the SEM photo showing the oxide film formed on the electrode due to oxygen. Specifically, as shown in FIG. 2(b), it can be seen that a channel is formed on the electrode and the electrode is opened, and it can be seen that an oxide film is formed on the opened electrode.

Fig. 3 is a schematic diagram schematically showing the electrodes in the SEM photographs of Figs. 2(a) and 2(b). As shown in FIG. 3, the electrode 10 forms an oxide film 11 due to the channel forming process as described above.

The above-mentioned oxide film causes a problem of increasing the resistance of the electrode. In order to remove this oxide film, a heat treatment process or a chemical mechanical polishing (CMP) process has been mainly used in the past. However, this conventional process has the problem that it cannot be applied to channels, trenches, and holes with high aspect ratios.

Therefore, it is necessary to remove or reduce the oxide film formed on the electrode when the channel is formed. In the present invention, in order to remove or reduce the oxide film from the channel, hole, trench, etc. having a high aspect ratio, a plasma can be used Remove the oxide film formed on the electrode.

In particular, the oxide film removal process of the present invention can remove or reduce the oxide film on the electrode under the channel, trench, or hole having an aspect ratio of at least 20 times or more.

In addition, since only radicals are used in the oxide film removal reaction using plasma provided with a shower head, physical damage and electrical damage to the substrate caused by ions activated by the plasma can be minimized.

In addition, in the present invention, H ₂ /Ar gas is used to remove the oxide film, so that it does not affect the existing deposits (other nitrides and/or oxides deposited when the channel is formed) and affects the electrodes formed on the electrodes. The upper insulating film achieves a high selectivity, that is, it does not damage the insulating film (oxide and nitride).

At this time, in the processing method for removing the oxide film of the electrode of the present invention, the electrode may be formed of one or more selected from the group consisting of tungsten, titanium, polysilicon, and aluminum.

In addition, the flow ratio of H ₂ to Ar (H ₂ /Ar) in H ₂ /Ar used when removing the electrode oxide film is preferably 0.01 to 0.1. If the flow rate ratio of H ₂ to Ar is too small, there is a problem that the oxide film formed on the electrode cannot be removed. If the flow rate ratio is too large, the oxide film removal efficiency is reduced or the plasma discharge is stabilized.

The RF power applied when removing the electrode oxide film is preferably 0.5 kW to 5.0 kW. If the applied RF power is too small, there is a problem that a part of the oxide film cannot be removed, and if it is applied too much, damage due to arc discharge may occur.

In addition, it is preferable to perform the removal of the oxide film at a temperature exceeding normal temperature.

Secondly, the processing method for removing the oxide film of the electrode and etching the electrode of the present invention includes a step S200 of performing an etching process on the electrode from which the oxide film is removed.

In this regard, in addition to the generation of an oxide film on the surface of the electrode, a portion of the electrode under the oxide film may also be damaged by oxygen or other processes, and the damaged electrode portion under the oxide film needs to be removed. Particularly, in the case of high-speed components, the resistivity is more important. If the electrode part under the oxide film is damaged, the conductivity will drop due to lattice distortion, which may cause problems in high-speed driving (see It can be seen from FIG. 3 that, in the lower portion of the oxide film 11, a damaged portion 12) is generated in the electrode due to the diffusion of oxygen in the oxide film.

Specifically, if the electrode produces a damaged part, there is a problem that other substances cannot be deposited on the electrode during the subsequent deposition process due to wettability, and there is the following problem: the final device is damaged due to the damage of the electrode The reactivity becomes slower, thereby increasing malfunctions, and therefore the reliability of the final manufactured element is reduced.

The etching process is a process of using an etching process to remove the damaged electrode part from the electrode where the oxide film is removed. The etched electrode part is tens of angstroms, which is very thin compared to the electrode size.

At this time, ClF ₃ /N ₂ gas can be used to perform the etching process.

In addition, the lower the reaction temperature during the etching process, the better the selection ratio of nitrides formed on the insulating film. Therefore, it is preferable to perform the etching process at a temperature below normal temperature.

Due to the conditions of the etching process as described above, the oxide film of the insulating film is not damaged and the damage of the nitride is reduced. Therefore, only the electrode can be etched without damaging the high aspect ratio channel.

4 is a schematic diagram showing a plasma device used in a processing method for removing an electrode oxide film and etching an electrode according to an embodiment of the present invention. The plasma apparatus 100 includes a processing chamber 106, a gas source 102, and a high-frequency power supply 122. A gas source 102 for generating plasma is provided on the upper part of the processing chamber 106, and a high-frequency power supply 122 is provided on one side of the processing chamber 106. .

The processing chamber 106 is provided with a gas distribution plate 112, a shower head 128 and a susceptor 120, and a substrate 118 is provided on the upper portion of the susceptor 120. There is a gas area 114 between the gas distribution plate 112 and the shower head 128, and there is a gas reaction area 116 between the shower head 128 and the substrate 118.

First, the gas used to generate plasma is supplied from the gas source 102 and flows into the processing chamber 106 through the gas injection port 108. The inflowing gas can enter the gas distribution plate 112 and the cluster through the holes 110 in the gas distribution plate 112. The gas area 114 between the shooting head 128. The gas area 114 may be a plasma excitation area, and the gas distribution plate 112 may function as an electrode to generate plasma. That is, the high-frequency power supply 122 is connected to the gas distribution plate 112, and the shower head 128 is grounded, and plasma is generated between the gas distribution plate 112 and the shower head 128.

In addition, the plasma generated in the gas region 114 enters the gas reaction region 116 through the shower head 128, so that the oxide film of the structure formed on the substrate 118 can be removed.

The hole 124 formed in the shower head 128 may allow the passage of reactive radicals or uncharged neutral species, and control or prevent the passage of plasma (ionized substances).

The susceptor 120 supports the substrate 118 and can move up and down in the processing chamber 106. A thermocouple (TC) is provided on the susceptor 120, so that the temperature of the substrate 118 can be measured or controlled.

In addition, the gas for etching the electrode is supplied from the gas source 102 or the shower head 128, so that the damaged electrode can be etched.

In the processing method for removing the oxide film of the electrode and etching the electrode of the present invention, the oxide of the electrode can be removed by using the plasma of H ₂ /Ar gas as described above, and secondly, the electrode can be etched by using ClF ₃ /N ₂ gas. electrode.

The processing method for removing electrode oxide film and etching electrode of the present invention can be performed in the same chamber, or in a cluster system that has multiple chambers and performs oxide film removal process and etching process in each chamber get on.

In addition, the processing method for removing the electrode oxide film and etching the electrode of the present invention has the following advantages: it is performed in a vacuum environment, and the process control of the electrode oxide film removal process and the etching process is relatively easy, and it is not necessary to supply oxygen. Execute in an oxidizing environment to prevent the electrode from re-oxidizing.

Example 1: Removal of tungsten oxide film and etching of tungsten 1

1. Removal of the oxide film formed on tungsten

After confirming that an oxide film is formed on the open tungsten after the channel is formed, the channel-formed tungsten is placed on the susceptor of the processing chamber. Inject H ₂ /Ar (flow ratio = 0.05) reaction gas into the chamber, apply 1.5 kW of RF power to generate plasma, and then use reactive radicals passing through the shower head to react for 240 seconds to remove tungsten Oxide film.

2. Etching of tungsten

The ClF ₃ /N ₂ gas is supplied to the tungsten from which the oxide film is removed to etch the tungsten. At this time, the etching time was 120 seconds.

Example 2: Removal of tungsten oxide film and etching of tungsten 2

During the removal process of the oxide film formed on tungsten, an RF power of 2.0 kW was applied. Except for this, the oxide film formed on tungsten was removed and tungsten was etched in the same manner as in the first embodiment.

Example 3: Removal of tungsten oxide film and etching of tungsten 3

During the removal process of the oxide film formed on tungsten, an RF power of 2.5 kW was applied. Except for this, the oxide film formed on tungsten was removed and tungsten was etched in the same manner as in the first embodiment.

Comparative example 1: Tungsten etching

After confirming that an oxide film was formed on the open tungsten by forming a channel, a ClF ₃ /N ₂ reaction gas was supplied to perform a reaction for 120 seconds.

The following Table 1 describes the process conditions of Examples 1 to 3 and Comparative Example 1.

[Table 1] Example Process conditions Oxide film removal process Etching process Gas type Flow ratio Power (kW) Gas type Example 1 H ₂ /Ar 0.05 1.5 ClF ₃ /N ₂ Example 2 H ₂ /Ar 0.05 2.0 ClF ₃ /N ₂ Example 3 H ₂ /Ar 0.05 2.5 ClF ₃ /N ₂ Comparative example 1 - - - ClF ₃ /N ₂

Experimental example 1: Analysis of tungsten etching corresponding to whether to perform the tungsten oxide film removal process

In the processing method for removing electrode oxide film and etching electrode of the present invention, whether or not tungsten etching corresponding to the tungsten oxide film removal process is performed is analyzed, and the result is shown in FIG. 5.

As shown in FIG. 5, it can be seen that in Comparative Example 1 where the tungsten oxide film removal process is not performed, even if the etching process of the present invention is performed, tungsten is not etched.

Experimental example 2: Analysis of tungsten etching amount change corresponding to tungsten oxide film removal process

In the processing method for removing the electrode oxide film and etching the electrode of the present invention, the change in the amount of tungsten etching corresponding to the oxide film removal process is analyzed, and the result is shown in FIG. 6.

In Example 1, Example 2, and Example 3, the RF power was changed to 1.5 kW, 2.0 kW, and 2.5 kW, respectively. Otherwise, the oxide film removal process and the etching process were performed under the same conditions.

As shown in FIG. 6, it can be seen that even if the tungsten etching process is performed in the same manner, if the RF power applied during the oxide film removal process is increased, the etching rate of tungsten will increase.

The result of FIG. 6 is a result that is not universal in the technical field to which the present invention belongs and is difficult for a person of ordinary skill to speculate.

As shown in FIG. 6, it is believed that the reason why the electrode oxide film removal process affects the subsequent process, that is, the electrode etching process is as follows.

Even though the electrode oxide film exposed to the chemical species during the electrode oxide film removal process is uniform macroscopically in the thickness direction due to factors such as crystallographic directionality, it is unevenly removed microscopically.

If other process conditions are the same, the more the RF power in the electrode oxide film removal process increases, the more hydrogen radicals are generated, and the amount of tungsten oxide removed increases, and therefore the scattered tungsten electrode parts increase.

On the other hand, the subsequent process, that is, the electrode etching process uses a plasma etching process, so even if a part of the tungsten oxide film remains, the electrode under the tungsten oxide film remains due to the characteristics of the plasma etching process as isotropic etching Will also be etched.

Therefore, if the RF power in the tungsten oxide film removal process increases, the exposed surface of the electrode under the tungsten oxide increases due to the microscopically uneven etching characteristics of the tungsten oxide. Therefore, it is judged that the tungsten oxide film is removed. The greater the RF power in the process, the greater the amount of electrode etching in the subsequent electrode etching process.

Experimental example 3: Analysis of electrode surface resistance due to tungsten oxide film removal process

In the processing method for removing electrode oxide film and etching electrode of the present invention, the surface resistance of tungsten is analyzed after the oxide film removal process is performed.

It was confirmed that if the oxide film formed on tungsten is removed by the electrode oxide film removal process of the present invention, the area resistance of tungsten is reduced by 4% to 5% compared to before the oxide film is removed. In addition, when the damaged portion of tungsten is further removed by the electrode etching process of the present invention, the surface resistance will be further reduced.

That is, the processing method of the present invention not only removes the oxide film formed on the electrode, but also removes the damaged part, thereby improving the reactivity of the electrode, and thus improving the performance of the element.

In the above, the description has been centered on the embodiments of the present invention, but a person of ordinary skill can make various changes or modifications. Therefore, it can be understood that such changes and modifications are included in the scope of the present invention as long as they do not depart from the scope of the present invention.

10: Electrode 11: Oxide film 12: Damaged part 100: Plasma device 102: gas source 106: processing chamber 108: Gas injection port 110: Hole of gas distribution plate 112: Gas distribution plate 114: gas area 116: gas reaction area 118: substrate 120: Pedestal 122: high frequency power supply 124: Shower Head Hole 128: shower head S100, S200: steps

FIG. 1 is a sequence diagram showing a processing method for removing an electrode oxide film and etching an electrode according to the present invention. FIGS. 2(a) and 2(b) are scanning electron microscope (SEM) photographs showing that an oxide film is formed in an electrode that is opened during the mask process for forming a channel. Fig. 3 is a schematic diagram schematically showing the electrodes in the SEM photographs of Figs. 2(a) and 2(b). 4 is a schematic diagram showing a plasma device used in a processing method for removing an electrode oxide film and etching an electrode according to an embodiment of the present invention. 5 is a scanning electron microscope (SEM) photograph showing the electrode after the process of Example 1 and Comparative Example 1 of the present invention. 6 is a graph showing the change in the etching amount of tungsten corresponding to the increase in RF power when the oxide film is removed in the processing method for removing an electrode oxide film and etching an electrode of the present invention.

S100, S200: steps

Claims (10)

A processing method for removing an electrode oxide film and etching an electrode includes: removing an oxide film formed on the electrode from an electrode formed with a channel; and performing an etching process on the electrode from which the oxide film is removed, wherein Chlorine trifluoride gas performs the etching process. The processing method for removing an electrode oxide film and etching an electrode according to claim 1, wherein the electrode is one or more selected from the group consisting of tungsten, titanium, polysilicon, and aluminum. The processing method for removing an electrode oxide film and etching an electrode according to claim 1, wherein the removal of the oxide film is performed using hydrogen/argon gas. The processing method for removing an electrode oxide film and etching an electrode according to claim 3, wherein in the hydrogen/argon gas, the flow rate ratio of hydrogen to argon (hydrogen/argon) is 0.01 to 0.1. The processing method for removing an electrode oxide film and etching an electrode according to claim 1, wherein the removal of the oxide film is performed using plasma and gas generated by radio frequency power. The processing method for removing an electrode oxide film and etching an electrode according to claim 1, wherein the etching process is performed using plasma and gas generated by radio frequency power. The processing method for removing an electrode oxide film and etching an electrode according to claim 1, wherein the etching process is performed at a temperature below normal temperature. The processing method for removing an electrode oxide film and etching an electrode according to claim 1, wherein the etching process is performed after the removal of the oxide film is performed until the electrode is opened. The processing method for removing an electrode oxide film and etching an electrode according to claim 1, wherein the greater the radio frequency power used when removing the oxide film, the more the etching amount of the electrode in the etching process increases . The processing method for removing an electrode oxide film and etching an electrode according to claim 1, wherein the removal of the oxide film and the etching process are performed in a non-oxidizing environment.

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