TWI580486B - Treatment of contaminants in workpieces with yttrium oxide coating - Google Patents

Description

Method for treating contaminants of workpieces with yttria coating

The present invention relates to the field of semiconductor fabrication, and more particularly to a method for treating contaminants of a workpiece having a yttria coating for plasma etching.

In recent years, in the field of semiconductor manufacturing, plasma etching is involved in many processes, such as the formation of TSV (Through Silicon Via), which involves plasma etching of germanium, and the formation of metal interconnects involves metal plasma etching. The formation of the gate in the transistor involves etching of the dielectric layer. The above process is generally carried out in a plasma chamber in which a plurality of workpieces, such as a focus ring, a shower head, etc., are disposed.

Taking the shower head as an example, the existing sprinkler head is generally made of aluminum, but the aluminum is easily corroded in a plasma environment, resulting in a short life of the sprinkler. In view of this problem, in the prior art, the outer surface of the substrate is covered with a layer of aluminum oxide (Al 2 O 3 ) which is more resistant to etching than aluminum. However, since the surface of the shower head is etched with gas during use, it is generally included. Fluorine gas reacts to form aluminum fluoride particles, which are aggregated and easily fall on the wafer to be etched, resulting in contamination. Therefore, alumina is not the preferred material for the showerhead cover layer, and the industry is gradually becoming pollution-free. It is replaced by a layer of yttrium (thermal conductivity: 149Wm-1K-1) or yttrium carbide (thermal conductivity: 150Wm-1K-1) which is excellent in heat dissipation. However, tantalum and or tantalum carbide easily react with the etching gas, resulting in a shortened service life of the shower head. In response to the above problems, a cerium oxide-covered shower head having better etching resistance has appeared.

Similar to the anti-etching purpose of the showerhead mentioned above, the surface of other workpieces used for plasma etching is generally covered with a ruthenium oxide package. Cladding.

However, the inventors have found that after a workpiece having a ruthenium oxide coating layer is used for a period of time, there are some contaminants on the surface, and the contaminant is not treated, and is easily deposited on the wafer to be etched, resulting in contamination. , ultimately reducing wafer production efficiency.

In view of this, it is necessary to propose a method of treating a contaminant of a workpiece having a yttria coating for plasma etching to avoid the above problems.

The object of the present invention is to propose a method for treating a pollutant of a workpiece having a yttria coating for plasma etching, so that the contaminated workpiece can be reused.

To achieve the above object, the present invention provides a method for treating a contaminant of a workpiece having a yttria coating for plasma etching, comprising: wiping the workpiece with at least an acidic solution, the acidic solution being hydrochloric acid, The concentration of HCl in hydrochloric acid in deionized water ranges from 3 wt% to 10 wt%; the workpiece is then rinsed with deionized water, wherein the deionized water is added with isopropanol during the deionized water rinse. The temperature of the deionized water is 50 ° C or higher. .

Preferably, the ultrasonic wave oscillation is used in the deionized water rinsing process.

Preferably, the deionized water is washed with high pressure deionized water.

Preferably, during the high pressure deionized water cleaning process, the deionized water contains particulate matter.

Preferably, the particulate matter comprises cerium oxide, aluminum oxide, oxidation At least one of zirconium and cerium oxide.

Preferably, the size of the particulate matter ranges from 10 nm to 1 mm.

Preferably, the particulate matter has a concentration by weight of less than 50% by weight.

Preferably, during the high pressure deionized water cleaning process, the deionized water has a pressure in the range of 0.5 MPa to 50 MPa.

Preferably, the deionized water has a pressure in the range of 1 MPa to 30 MPa.

Preferably, the deionized water has a pressure in the range of 2 MPa to 20 MPa.

Preferably, isopropanol is added to the deionized water during the deionized water rinse.

Preferably, the temperature of the deionized water during the deionized water washing is in the range of 70 ° C to 120 ° C, and the weight percent concentration of the isopropanol is less than 90 wt %.

Preferably, the weight percent concentration of the isopropyl alcohol ranges from 1% by weight to 80% by weight.

Preferably, the weight percent concentration of the isopropyl alcohol ranges from 1% by weight to 50% by weight.

Preferably, the acidic solution further comprises at least one of nitric acid and HF acid.

Preferably, the acidic solution is hydrochloric acid, and the concentration by weight of HCl in deionized water is less than 90% by weight.

Preferably, the concentration by weight of HCl in deionized water in the hydrochloric acid ranges from 1% by weight to 15% by weight.

Preferably, the concentration by weight of HCl in deionized water in the hydrochloric acid ranges from 3 wt% to 10 wt%.

Preferably, the step of wiping the workpiece with an alkaline solution, the base, is also performed before or after wiping the workpiece with an acidic solution The solution is at least one of a KOH solution, a NaOH solution, and a NH4OH solution.

Preferably, the alkaline solution is a NH4OH solution, and the weight concentration of NH4OH in the deionized water in the NH4OH solution is less than 50% by weight.

Preferably, the concentration by weight of NH4OH in deionized water in the NH4OH solution ranges from 1% by weight to 30% by weight.

Preferably, the concentration by weight of NH4OH in deionized water in the NH4OH solution ranges from 1% by weight to 5% by weight.

Preferably, the step of rinsing the showerhead with deionized water is followed by a step of wiping the showerhead with an alkaline solution.

Preferably, in the step of rinsing the workpiece with deionized water after the step of wiping the workpiece with an alkaline solution, ultrasonic wave oscillating, high pressure deionized water washing, deionized water is added with isopropanol, deionized The temperature of the water is at least one of 50 ° C or higher.

Compared with the prior art, the invention has the following advantages: after using the yttrium oxide coating layer, some pollutants are generated on the workpiece after a period of use, and the main components of the pollutant are fluorine, bismuth, aluminum, carbon and Compounds between oxygen and other contaminants containing metal elements such as copper, titanium, etc., can remove most of the poorly adhering contaminants by using an acidic solution, and then rinsed with deionized water to make the contaminated spray The head is re-used; further, for a small number of highly contaminant contaminants, ultrasonic wave turbulence or high-pressure deionized water is used during the deionized water rinsing process; further, for the strong adhesion of individual adhesion Washing with deionized water containing particulate matter; further, due to the strong wetting of isopropanol, deionized water Isopropanol is added to the deionized water during the rinsing process to enhance the infiltration ability of the deionized water on the surface of the contaminant, and the contaminant is easily removed by cleaning; further, since the aluminum fluoride is dissolved in the hot water, the deionized water is rinsed. Increasing the temperature of the water allows the aluminum fluoride-based contaminants to loosen on the surface in contact with the cerium oxide, and is easy to clean and remove the contaminants; further, since the cerium oxide is dissolved in the acid, the contaminant is removed. In order to prevent damage to the performance of cerium oxide, the concentration of acid in deionized water needs to be strictly controlled.

As described in the background art, after the workpiece having the yttrium oxide coating layer is used for some time, some contaminants are generated thereon, and the inventors performed SEM test and EDS spectrum analysis on the pollutant, and the results are respectively shown in the figure. 1 and FIG. 2, the main component of which is fluorine, ruthenium-based compound, the present invention proposes to use an acidic solution to remove most of the poorly-contaminated contaminants, and then rinsed with deionized water to make the contaminated workpiece Re-use it.

The above described objects, features and advantages of the present invention will become more apparent from the aspects of the invention. Since the principles of the invention are illustrated, they are not drawn to scale.

Taking a shower head as an example, FIG. 3 is a flow chart showing a method for treating a pollutant of a shower head having a ruthenium oxide coating layer according to an embodiment of the present invention. The implementation process of the processing method will be described in detail below with reference to FIG. 3.

First, step S11 is performed to wipe the contaminants on the shower head having the ruthenium oxide coating layer with isopropyl alcohol (IPA).

The composition of the contaminant is mainly described above, which is mainly fluorine and antimony produced by the reaction of the fluorine-containing etching gas and the cerium oxide coating layer in the plasma etching process. a compound based.

Isopropanol has strong infiltration ability. After dissolving the isopropanol in the deionized water of the subsequent step S12, it can enhance the infiltration ability of the deionized water into the interface between the contaminant and the cerium oxide layer, and is easy to clean and remove the pollution in the subsequent steps. Things.

Then, step S12 is performed, and rinsed with deionized water. In order to enhance the effect of pollutant removal, in this step, (1) ultrasonic cleaning can be used, (2) isopropanol can also be added in deionized water, and (3) the temperature of deionized water can also be controlled above 50 °C, or (4) Wash with high pressure deionized water. The above four methods can be used at the same time or alternatively, depending on the removal effect.

For (1), the specific frequency and power of the ultrasonic waves used are determined according to the removal effect.

For (2), since isopropanol is volatile, the amount of isopropanol added in the deionized water washing step is not too large, and the inventors have found that the temperature of the deionized water in this step is 70 ° C - At 120 ° C, when the weight percentage concentration of the isopropanol in deionized water is less than 90% by weight, the function of the cerium oxide may not be affected and the pollutants can be effectively removed. Preferably, the weight concentration of the isopropyl alcohol is in the range of 1 wt. More preferably, the weight percent concentration of the isopropanol ranges from 1% by weight to 50% by weight.

For (3), since the aluminum fluoride is dissolved in hot water, the temperature of the water is increased during the deionized water washing process, so that the aluminum fluoride-based contaminant can be loosened on the surface in contact with the cerium oxide, and the contaminant is easily Cleaning and removal;

For (4), when cleaning with high pressure deionized water, the inventors have found that when the pressure range is from 0.5 MPa to 50 MPa, the effect of removing contaminants is remarkable, and preferably, the pressure of deionized water ranges from 1 MPa to 30 MPa, and more Preferably, the pressure of deionized water ranges from 2 MPa to 20 MPa, and the degree of damage to yttrium oxide is minimized on the premise of removing contaminants.

In addition, in the high-pressure deionized water cleaning process, for some of the highly adherent contaminants that cannot be removed by the above methods, it is possible to use (5) adding particulate matter in deionized water. The particulate matter increases the probability that the contaminant will be stripped off. In a specific implementation, the particulate matter may include one or more of cerium oxide, aluminum oxide, zirconium oxide or cerium oxide, and the particle size ranges from 10 nm to 1 mm. At the same time, the content of the particulate matter can also be controlled. The inventors have found that when the weight concentration of the particulate matter in the deionized water is less than 50% by weight, some pollutants which cannot be removed by the methods (1) to (4) can be removed. .

Then, step S13 is performed, and the solution is wiped with an acidic solution. The acidic solution in this step may be hydrochloric acid, nitric acid or HF acid. Since the cerium oxide as a coating layer is soluble in acid, even if it is wiped, the concentration control of the acid needs to be strictly controlled. In the present embodiment, hydrochloric acid is used. The inventors have found that when the concentration of HCl in deionized water is less than 90% by weight, the wiping time can be appropriately controlled, and the coating layer can be removed without damaging the coating. Preferably, the weight percent concentration of HCl in the hydrochloric acid ranges from 1% by weight to 15% by weight, and more preferably, the weight percent concentration of HCl in the hydrochloric acid ranges from 3% by weight to 10% by weight.

Then step S14 is performed and rinsed with deionized water. This step is the same as step S12. However, one or several schemes can be selected from the (1)-(5) schemes. Performing this step enhances the removal of contaminants from the surface of the cerium oxide.

Thereafter, step S15 is performed, and the solution is wiped with an alkaline solution. The alkaline solution in this step may be a KOH solution, a NaOH solution or a NH4OH solution.

In this embodiment, an NH4OH solution is used. The concentration of NH4OH in the deionized water in the NH4OH solution is less than 50% by weight, and the acidic solution that has not been washed before can be neutralized. In addition, the alkaline solution is further It can also be reacted with contaminants to remove contaminants dissolved in an alkaline solution. Preferably, the concentration of NH4OH in the NH4OH solution in deionized water ranges from 1% by weight to 30% by weight. More preferably, the weight percent concentration of NH4OH in the deionized water in the NH4OH solution ranges from 1 wt% to 5 wt%.

Then, step S16 is performed, and rinsed with deionized water. This step is the same as step S12. However, one or several schemes can be selected from the (1)-(5) schemes. Performing this step enhances the removal of contaminants from the surface of the cerium oxide.

Then, step S17 is performed to check the surface of the shower head that has been processed to determine whether the pollutant removal meets the requirements. If the requirements are met, the processing is completed. If the requirements are not met, steps S13-S17 are performed again until the requirements are met. .

It should be noted that, in the steps S11-S17 described above, each step is performed, and the deionized water in the conventional process can be used to wash away the contaminants peeled off from the surface of the cerium oxide in this step.

In the step S15 in this embodiment, the shower head is wiped with an alkaline solution, or may be performed before the shower head is wiped with an acidic solution in step S13, and the acidic solution wiped after the neutralization may neutralize the previously performed alkali. The alkaline solution that was not completely washed during the wiping of the solution.

What has been described above is a standard decontaminant process suitable for batch processing. In the specific implementation process, some steps can be selected, but at least acidic solution removal is required, followed by two steps of washing with deionized water.

The above describes the treatment process for the contaminants of the cerium oxide coated sprinkler. For other workpieces with a yttrium oxide coating in the plasma etching process, such as the contamination of the surface of the focus ring, the processing flow The same as the above process.

In summary, the present invention has the following advantages: after a portion of a workpiece having a yttria coating is used for plasma etching, some contaminants are generated thereon, and the main components of the contaminant are fluorine, antimony, aluminum, and carbon. Compounds between oxygen and other contaminants containing metal elements such as copper, titanium, etc., can remove most of the poorly adhering contaminants by using an acidic solution, and then rinsed with deionized water to make the contaminated spray The sprinklers are re-used.

For a small number of highly contaminant contaminants, the use of deionized water washing process (1) using ultrasonic vibration, (2) deionized water can also add isopropanol, isopropanol infiltration ability is very strong, The deionized water can enhance the infiltration ability of the surface of the shower head, so that the pollutant can be quickly removed; (3) the temperature of the deionized water can also be controlled above 50 ° C, and the temperature of the deionized water solution is raised. It can enhance the solubility of aqueous solution to aluminum fluoride contaminants, so that aluminum fluoride-based contaminants loosen on the surface in contact with cerium oxide, which is easy to clean and remove contaminants; (4) use high-pressure deionized water Cleaning, the degree of damage to the yttrium oxide film is small, and at the same time the ability to peel off the surface from the yttrium oxide surface.

For individual highly adherent contaminants, (5) deionized water containing particulate matter is used for cleaning.

Since cerium oxide is easily dissolved in an acidic solution, the concentration of the acid in deionized water is strictly controlled. For example, when hydrochloric acid is used, the concentration by weight of HCl in deionized water is less than 90% by weight.

After the step of washing the alkaline solution, the shower head is further subjected to a deionized water rinsing step. In the deionized water rinsing step, the above steps (1) to (5) may be used to enhance the peeling of the contaminant from the cerium oxide surface. Clear function.

Although the present invention has been disclosed above in the preferred embodiment, it is not The present invention can be used to define the present invention, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. In the content of the technical solutions of the present invention, any simple modifications, equivalent changes, and modifications made to the above embodiments in accordance with the technical scope of the present invention are within the scope of protection of the technical solutions of the present invention.

Q‧‧‧Area

1 is a SEM test result of a contaminant; FIG. 2 is a EDS test result chart of the Q area in FIG. 1; FIG. 3 is a flow chart of a contaminant processing method provided by an embodiment of the present invention.

Claims (18)

A method for treating contaminants of a workpiece having a yttria coating for plasma etching, comprising: wiping the workpiece with at least an acidic solution, wherein the acidic solution is hydrochloric acid, and the hydrochloric acid is HCl in deionized water. The weight concentration ranges from 3 wt% to 10 wt%; the workpiece is then rinsed with deionized water, wherein the deionized water is added with isopropanol at a temperature of 50 ° C or higher. And the deionized water is washed by ultrasonic vibration or washed with high-pressure deionized water, and the deionized water contains particulate matter. The treatment method according to claim 1, wherein the particulate matter comprises at least one of cerium oxide, aluminum oxide, zirconium oxide, and cerium oxide. The processing method of claim 1 or 2, wherein the particle size ranges from 10 nm to 1 mm. The treatment method of claim 1, wherein the particulate matter has a concentration by weight of less than 50% by weight. The processing method according to claim 1, wherein the deionized water has a pressure ranging from 0.5 MPa to 50 MPa in a high pressure deionized water cleaning process. The treatment method according to claim 5, wherein the deionized water has a pressure ranging from 1 MPa to 30 MPa. The treatment method according to claim 6, wherein the deionized water has a pressure ranging from 2 MPa to 20 MPa. The treatment method of claim 1, wherein the temperature of the deionized water during the deionized water washing is in the range of 70 ° C to 120 ° C, and the weight percent concentration of the isopropanol is less than 90 wt %. The treatment method of claim 8, wherein the isopropyl alcohol has a weight percentage ranging from 1% by weight to 80% by weight. The treatment method according to claim 9, wherein the isopropyl alcohol has a weight percentage ranging from 1% by weight to 50% by weight. The treatment method according to claim 1, wherein the acidic solution further comprises at least one of nitric acid and hydrofluoric acid. The processing method of claim 1, wherein the step of wiping the workpiece with an alkaline solution is performed before or after wiping the workpiece with the acidic solution, the alkaline solution being a KOH solution, a NaOH solution, or a NH4OH solution. At least one of them. The treatment method according to claim 12, wherein the alkaline solution is a NH4OH solution, and the NH4OH has a weight concentration of less than 50% by weight in deionized water. The process of claim 13, wherein the NH4OH solution has a concentration by weight of NH4OH in deionized water ranging from 1% by weight to 30% by weight. The process of claim 14, wherein the NH4OH solution has a concentration by weight of NH4OH in deionized water ranging from 1 wt% to 5 wt%. The processing method of claim 12, wherein the step of wiping the workpiece with deionized water is further performed after the step of wiping the workpiece with the alkaline solution. The processing method of claim 16, wherein the step of rinsing the workpiece with deionized water after the step of wiping the workpiece with the alkaline solution is performed by ultrasonic oscillating, high pressure deionized water cleaning, deionization The temperature at which isopropanol and deionized water are added to water is at least one of 50 ° C or higher. The processing method of claim 1, wherein the workpiece is a showerhead or a focus ring.