JP7423980B2 - Wafer surface cleaning device and wafer surface cleaning method - Google Patents

Description

The present invention relates to an apparatus and method for cleaning the surface of a wafer, and more particularly to an apparatus and method for cleaning the surface of a semiconductor wafer whose surface has fine grooves or holes formed by dry etching.

In the manufacturing of semiconductors, necessary cleaning is performed to remove contaminants such as particulates adhering to the surfaces of wafers and thin films according to each step of the manufacturing process. During the process of forming integrated circuits, wafers with grooves or holes formed by dry etching are subjected to dry etching to remove contaminants such as particles attached to the wafer surface and particles remaining inside the grooves or holes. Cleaning is in progress.

In recent years, with the miniaturization, three-dimensionalization, and high integration of semiconductor device structures, the aspect ratio of grooves or holes formed on the surface of wafers has been increasing, and the aspect ratio is 10 or more, and even the aspect ratio is 20 or more. Some even extend to. In order to clean wafers with such high aspect ratio grooves or holes, cleaning methods using solutions with low surface tension and low viscosity, such as isopropyl alcohol (IPA) and ethanol, or cleaning methods that use surfactant on the wafer surface in advance are recommended. A cleaning method has been proposed in which the surfactant is made hydrophilic with a chemical agent and then the surfactant is replaced with a chemical liquid.

Although IPA and ethanol are effective cleaning solutions for removing contaminants such as particles remaining inside the grooves or holes formed on the wafer surface, excessive use of these cleaning solutions increases running costs and harms the environment. There is a problem in that it leads to an increase in load. In addition, for example, in Patent Document 1, after a chemical solution containing hydrofluoric acid and ammonium fluoride is injected into a hole formed on a wafer surface, IPA vapor is used to hold the chemical solution inside the hole. A method has been disclosed in which the chemical solution is removed from the surface of the wafer while the wafer is still in the hole, and finally, pure water is supplied to replace the chemical solution inside the hole. There is also the problem that it leads to Additionally, Non-Patent Document 1 and Non-Patent Document 2 state that even if the concentration of IPA or ethanol in the solution is low, it is possible to allow the solution to penetrate into the inside of grooves or pores (pores) with a high aspect ratio. However, the surface tension of the solution increases due to the lower concentration of IPA or ethanol, and the gas present in the pores prevents the solution from immersing, so it takes less time to complete immersion. This takes a long time, and the overall throughput also decreases.

Furthermore, when a surfactant is used to remove contaminants such as fine particles remaining inside the pores formed on the wafer surface, as shown in Non-Patent Document 3, the rate of water infiltration into the pores is Although it is faster, there is a problem that the surfactant remains in the pores. Therefore, it is necessary to remove the surfactant remaining in the pores by UV treatment or the like, which also reduces the overall throughput.

Japanese Patent Application Publication No. 2008-147434

Langmuir, (2017), 33, 3601-3609 Solid State Phenomena, (2016), 255, 129-135 ESSL, (2006), 9, F17

The present invention has been made based on the above-mentioned circumstances, and it is possible to reduce running costs and environmental loads, and also to reduce the number of fine grooves or holes formed on the surface of a wafer by dry etching. However, contaminants such as fine particles remaining inside the grooves or holes can be effectively removed, and the throughput of wafer cleaning can be improved by accelerating the rate of water infiltration into the grooves or holes. An object of the present invention is to provide a wafer surface cleaning apparatus and a wafer surface cleaning method that are possible.

In order to solve the above-mentioned problems, the present invention first provides a cleaning tank, a gas supply means for supplying an easily soluble gas to the surface of a wafer placed in the cleaning tank, and a gas supply means for supplying an easily soluble gas to the surface of a wafer placed in the cleaning tank. A wafer surface cleaning device is provided, which includes a solution supply means for supplying a mixed solution of water and alcohol to the wafer surface after a soluble gas has been supplied (invention 1).

Here, the term "easily soluble gas" refers to a gas that is easily soluble in water, and includes, for example, N ₂ gas, CO ₂ gas, and the like.

According to this invention (invention 1), compared to conventional cleaning using only alcohol such as IPA or ethanol, the amount of alcohol used is small, so running costs and environmental burden can be reduced. In addition, by supplying a mixed solution of water and alcohol to the wafer surface after the easily soluble gas has been supplied, the easily soluble gas quickly dissolves in the mixed solution, resulting in fine particles adhering to the wafer surface. It is possible to effectively remove contaminants such as Even if fine grooves or holes are formed on the surface of the wafer by dry etching, the easily soluble gas can be easily dissolved by supplying the mixed solution to the grooves or holes filled with easily soluble gas. Since the gas quickly dissolves into the mixed solution, the rate of water infiltration into the grooves or holes is faster, which can effectively remove contaminants such as particles remaining inside the grooves or holes, and improve the throughput of wafer cleaning. can be improved.

In the above invention (invention 1), it is preferable that the easily soluble gas is N ₂ gas or CO ₂ gas (invention 2).

According to this invention (invention 2), since the easily soluble gas is N ₂ gas or CO ₂ gas, dissolution into the mixed solution is performed more quickly.

In the above inventions (Inventions 1 and 2), it is preferable that the mixed solution contains alcohol in a range of 3 mol/% or more and 10 mol/% or less based on ultrapure water (Invention 3).

According to this invention (Invention 3), since the surface tension and viscosity are lower than that of ultrapure water, the water immersion speed is faster, so even if grooves or holes are formed on the surface of the wafer by dry etching, , the throughput of wafer cleaning can be improved.

In the above invention (Invention 1-3), the alcohol is preferably isopropyl alcohol or ethanol (Invention 4).

According to this invention (Invention 4), since isopropyl alcohol and ethanol are highly hydrophilic, even when grooves or holes are formed on the surface of the wafer by dry etching, the grooves are difficult to penetrate with water alone. Alternatively, the mixed solution can be flooded into the holes.

In the above invention (Invention 1-4), it is preferable that a degassing membrane module for degassing the mixed solution is further provided (Invention 5).

Polar gases are easily dissolved in polar solvents such as alcohols, so when water and alcohol are mixed, the amount of saturated polar gas dissolved in the alcohol decreases, creating bubbles and hindering the progress of gas dissolution. Sometimes I end up putting it away. According to this invention (invention 5), the generation of bubbles can be prevented by deaerating the mixed solution before being supplied to the cleaning tank. In addition, by supplying the degassed mixed solution to the surface of the wafer after the easily soluble gas has been supplied, the dissolution of the easily soluble gas into the mixed solution is promoted, so the water immersion speed becomes even faster. The throughput of wafer cleaning can be further improved.

Second, the present invention includes a gas supply step of supplying an easily soluble gas to the surface of a wafer placed in a cleaning tank, and a step of supplying the easily soluble gas to the surface of the wafer after the gas supply step. Provided is a method for cleaning the surface of a wafer, comprising a solution supply step for supplying a mixed solution of water and alcohol (invention 6).

According to this invention (invention 6), compared to conventional cleaning using only alcohol such as IPA or ethanol, the amount of alcohol used is small, so running costs and environmental burden can be reduced. In addition, by performing the solution supply process after the gas supply process, the easily soluble gas on the wafer surface is quickly dissolved in the mixed solution, making it possible to effectively remove contaminants such as fine particles that adhere to the wafer surface. . Even if grooves or holes are formed on the surface of the wafer by dry etching, the mixed solution can be easily supplied to the grooves or holes filled with easily soluble gas in the solution supply step. Since the soluble gas quickly dissolves into the mixed solution, the rate of water infiltration into the grooves or holes becomes faster, and contaminants such as particulates remaining inside the grooves or holes can be effectively removed, as well as wafer cleaning. throughput can be improved.

In the above invention (invention 6), it is preferable that the easily soluble gas is N ₂ gas or CO ₂ gas (invention 7).

In the above inventions (inventions 6 and 7), it is preferable that the mixed solution contains alcohol in a range of 3 mol/% or more and 10 mol/% or less based on ultrapure water (invention 8).

In the above invention (Invention 6-8), the alcohol is preferably isopropyl alcohol or ethanol (Invention 9).

In the invention (invention 6-9), it is preferable that the method further includes a deaeration step for deaerating the mixed solution before the solution supply step (invention 10).

According to this invention (invention 10), the generation of bubbles can be prevented by degassing the mixed solution before the solution supply step. In addition, in the solution supply process, by supplying the degassed mixed solution to the surface of the wafer after the easily soluble gas has been supplied, the dissolution of the easily soluble gas into the mixed solution is promoted. This makes it possible to further improve the throughput of wafer cleaning.

According to the wafer surface cleaning apparatus and wafer surface cleaning method of the present invention, compared to conventional cleaning using only alcohol such as IPA or ethanol, the amount of alcohol used is small, so running costs and environmental impact are reduced. can be reduced. In addition, by supplying a mixed solution of water and alcohol to the wafer surface after the easily soluble gas has been supplied, the easily soluble gas quickly dissolves in the mixed solution, resulting in fine particles adhering to the wafer surface. It is possible to effectively remove contaminants such as Even if fine grooves or holes are formed on the surface of the wafer by dry etching, the easily soluble gas can be easily dissolved by supplying the mixed solution to the grooves or holes filled with easily soluble gas. Since the gas quickly dissolves into the mixed solution, the rate of water infiltration into the grooves or holes is faster, which can effectively remove contaminants such as particles remaining inside the grooves or holes, and improve the throughput of wafer cleaning. can be improved.

FIG. 1 is a schematic diagram showing a wafer surface cleaning apparatus according to a first embodiment of the present invention. FIG. 3 is a schematic diagram showing a wafer surface cleaning apparatus according to a second embodiment of the present invention. 3 is a schematic diagram showing a wafer surface cleaning apparatus of Comparative Example 1. FIG. FIG. 3 is a schematic diagram showing a wafer surface cleaning apparatus of Comparative Example 2. 2 is a schematic diagram showing a wafer used in the wafer surface cleaning apparatus of FIG. 1, in which (a) is a front view of the wafer, and (b) is a diagram showing a part of the AA' cross section in (a). .

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a wafer surface cleaning apparatus and a wafer surface cleaning method of the present invention will be described below with appropriate reference to the drawings. The embodiments described below are intended to facilitate understanding of the present invention, and are not intended to limit the present invention in any way.

[Wafer]
FIG. 5 is a schematic diagram showing a wafer 10 used in a wafer surface cleaning apparatus and a wafer surface cleaning method according to an embodiment of the present invention, in which (a) is a front view of the wafer 10, and (b) is a front view of the wafer 10. 2 is a diagram showing a part of the AA' cross section in (a); FIG.

As shown in FIG. 5(b), the wafer 10 has a plurality of recesses 12 formed in its surface 11 by dry etching. In this state, contaminants (not shown) such as residues and particles generated during dry etching are attached to the surface 11 of the wafer 10 and the sides and bottoms of the recesses 12.

The aspect ratio of the recess 12 is expressed as the ratio of the depth 14 of the recess 2 to the width 13 of the recess 12. Here, a high aspect ratio means that the ratio of the depth 14 to the width 13 of the recess 12 is 2 or more. In this embodiment, the recess 12 is a fine groove (trench) extending in the vertical direction in FIG. 5(a), and has a high aspect ratio. More specifically, the recess 12 has a width 13 of 30 nm, a depth 14 of 300 nm, a depth (not shown) of 10 mm, and a depth to width ratio (aspect ratio) of 10. Note that the recess 12 only needs to have a high aspect ratio, and its width and depth are not limited to those of this embodiment, but it is preferable that the width 13 is 30 nm or less.

Further, in this embodiment, the recess 12 is a groove (trench), but the shape of the recess 12 is not limited to this, and may be a fine hole.

[Wafer surface cleaning equipment]
Next, the apparatus for cleaning the surface of the wafer 10 as described above will be explained in detail with reference to FIGS. 1 and 2. Note that in this embodiment, an immersion cleaning method is employed as a cleaning device for the wafer surface. The immersion cleaning method is one of the wet cleaning methods, and refers to a cleaning method in which the wafer is immersed in a liquid.

<First embodiment>
As shown in FIG. 1, a wafer surface cleaning apparatus 100 according to a first embodiment of the present invention supplies a cleaning tank 1 and an easily soluble gas to a surface 11 of a wafer 10 installed in the cleaning tank 1. The solution supply means 3 is mainly provided for supplying a mixed solution of water and alcohol to the surface 11 of the wafer 10 after the easily soluble gas has been supplied by the gas supply means 2. In this embodiment, the gas supply means 2 and the solution supply means 3 are configured as one gas/solution supply unit 4.

[Cleaning tank]
The cleaning tank 1 is a water tank for cleaning the surface 11 of the wafer 10, and has a wafer holder (not shown) on which the wafer 10 is placed. The cleaning tank 1 may be configured to be able to clean the surface 11 of the wafer 10 with the easily soluble gas supplied from the gas supply means 2 and the mixed solution supplied from the solution supply means 3. In this embodiment, a dipping type cleaning method is adopted, but the method is not limited to this.

[Gas supply means]
The gas supply means 2 is a means for supplying easily soluble gas to the surface 11 of the wafer 10 placed in the cleaning tank 1 . In this embodiment, the gas supply means 2 includes a pipe L1 that connects the gas supply source and the cleaning tank 1, and the pipe L1 is provided with a filter 23 for filtering easily soluble gas. Further, a gas pressure regulator 21 and a mass flow meter 22 are connected in this order to the piping L1 on the upstream side of the filter 23. The piping L1 is provided with automatic opening/closing valves for adjusting the supply amount of easily soluble gas at positions upstream of the filter 23 and connected to the gas pressure regulator 21 and mass flow meter 22, respectively. . As the automatic opening/closing valve, it is preferable to use a suckback type valve, but the invention is not limited to this.

Here, the term "easily soluble gas" refers to a gas that is easily soluble in water, and includes, for example, N ₂ gas, CO ₂ gas, and the like. In this embodiment, the easily soluble gas is preferably N ₂ gas or CO ₂ gas, and particularly preferably CO ₂ gas. When the easily soluble gas is N ₂ gas or CO ₂ gas, dissolution into a mixed solution of water and alcohol, which will be described later, is performed more quickly.

[Solution supply means]
The solution supply means 3 is a means for supplying a mixed solution of water and alcohol to the surface 11 of the wafer 10 after the easily soluble gas has been supplied by the gas supply means 2. In this embodiment, the solution supply means 3 includes a pipe L2 that connects the ultrapure water supply source and the cleaning tank 1, and a pipe L3 that connects the alcohol supply source and the pipe L2. At the connection between the pipe L2 and the pipe L3, an automatic opening/closing valve for adjusting the amount of alcohol supplied is provided on the pipe L3 side. As the automatic opening/closing valve, it is preferable to use a suckback type valve, but the invention is not limited to this.

The pipe L2 is provided with a solution mixing chamber 32 for mixing ultrapure water and alcohol to produce a mixed solution downstream of the connection between the pipes L2 and L3. A filter 35 is provided on the side for removing impurities from the mixed solution of water and alcohol. Further, in the pipe L2, a flow meter 31 is provided on the upstream side of the solution mixing chamber 32, and a flow meter 31 is provided on the downstream side of the solution mixing chamber 32 and upstream of the filter 35, and a flow meter 31 is provided on the downstream side of the solution mixing chamber 32 and upstream of the filter 35. An online TOC meter 33 and a mass flow meter 34 are provided in this order for managing the flow rate. The piping L2 is provided with an automatic opening/closing valve on the upstream side of the flow meter 31 to adjust the amount of ultrapure water supplied. As the automatic opening/closing valve, it is preferable to use a suckback type valve, but the invention is not limited to this.

In this embodiment, the online TOC meter 33 is used to manage the mixing degree of ultrapure water and alcohol, but this is not limited to this, and for example, to monitor the flow rate of ultrapure water. The mixing degree of ultrapure water and alcohol may be managed only by proportional control to the measured value of the flowmeter 31.

In addition, in a general recipe for cleaning the surface of a wafer, the time for sending out one liquid is often about 0.5 minutes to 1 minute, and the flow rate is 2 L/min. ~4L/min. Since the volume of the solution mixing chamber 32 is about 5 L, it is sufficient. As the solution mixing chamber 32, a conventional chemical injection mechanism can be applied.

In this embodiment, as shown in FIG. 1, the piping L2 between the solution mixing chamber 32 and the filter 35 uses a plurality of bent pipes (elbows) and is provided with a restriction (orifice) in the piping. It is being Since the pipe L2 between the solution mixing chamber 32 and the filter 35 has such a structure, mixing of the mixed solution flowing out from the solution mixing chamber 32 is further promoted.

A line mixing device such as a static mixer may be further provided upstream of the solution mixing chamber 32. However, by adjusting the piping system and the flow rate during transfer and mixing so that the Reynolds number is 4000 or more, if the viscosity and density of each liquid are equal to about +/-20%, there is no need to install a static mixer. Sufficient mixing can also be achieved by using a bent pipe (elbow) as the piping or by providing an orifice in the piping.

The pipe L3 is provided with a storage tank 36 for storing alcohol supplied from an alcohol supply source through the pipe L3, and the storage tank 36 is provided with a supply tank 36 for supplying the stored alcohol to the pipe L2. A liquid pump 37 is connected.

Note that, as the pipe L2, a pipe having an inner diameter of 8 mm or less can be suitably used, but it is not limited to this as long as a flow velocity sufficient to cause turbulence can be obtained.

In this embodiment, the mixed solution of water and alcohol preferably contains alcohol in a range of 3 mol/% or more and 10 mol/% or less based on ultrapure water, and particularly contains alcohol in a range of 3 mol/% or more and 10 mol/% or less based on ultrapure water. It is preferable that it contains about 3 mol/%. The mixed solution M containing alcohol in the range of 3 mol/% or more and 10 mol/% or less with respect to ultrapure water has a lower surface tension and viscosity than ultrapure water, so it is not formed on the surface 11 of the wafer 10. The rate of water infiltration into the recess 12 becomes faster.

In this embodiment, the mixed solution of water and alcohol contains alcohol in a range of 3 mol/% or more and 10 mol/% or less based on ultrapure water. For example, a trace amount of HCl or NH ₄ OH may be further mixed as long as the content is within the range of mol/% or more and 10 mol/% or less. By further mixing a small amount of HCl or NH ₄ OH into the mixed solution of water and alcohol, the cleaning effect can be improved.

Further, the alcohol contained in the mixed solution of water and alcohol is preferably isopropyl alcohol or ethanol. Since sopropyl alcohol and ethanol are highly hydrophilic, a mixed solution of water and alcohol can be applied to the recesses 12 of the wafer 10, which are difficult to infiltrate with water alone.

<Second embodiment>
Next, a wafer surface cleaning apparatus 200 according to a second embodiment of the present invention will be described with reference to FIG. As shown in FIG. 2, the wafer surface cleaning apparatus 200 has the following features except that the piping L2 constituting the solution supply means 3 further includes a degassing membrane module 38 between the solution mixing chamber 32 and the online TOC meter 33. has the same configuration as the wafer surface cleaning apparatus 100 according to the first embodiment, so the same reference numerals are used for the same configurations as the wafer surface cleaning apparatus 100 and the description thereof will be omitted.

The degassing membrane module 38 is for degassing a mixed solution of water and alcohol, and has a vacuum pump 39 as a power source for moving gas. Polar gases are easily dissolved in polar solvents such as alcohols, so when water and alcohol are mixed, the amount of saturated polar gas dissolved in the alcohol decreases, creating bubbles and hindering the progress of gas dissolution. Sometimes I end up putting it away. Therefore, by degassing the mixed solution of water and alcohol using the degassing membrane module 38 and then supplying it to the cleaning tank 1, it is possible to prevent the generation of air bubbles and to remove the mixed solution of easily soluble gas. Since the dissolution of the wafer 10 into the concave portion 12 is promoted, the rate at which water enters the concave portion 12 of the wafer 10 can be increased.

In this embodiment, the degassing membrane module 38 is of a hollow fiber type, but is not limited to this as long as it can degas a mixed solution of water and alcohol, and may be of a spiral type, for example. Since the degassing membrane module 38 is of the hollow fiber type, the membrane area per module volume becomes large, so that the dissolved gas concentration can be sufficiently lowered with a small module, and highly efficient degassing processing becomes possible.

In this embodiment, the pipe L2 between the degassing membrane module 38 and the filter 35 is preferably made of a material with high airtightness in order to maintain the degree of gas deaeration, for example, made of metal, PVDF, or vinyl. It is preferable to use piping.

Note that the mixed solution mixed in the solution mixing chamber 32 may be pumped or gas pressure fed to the degassing membrane module 38.

[Wafer surface cleaning method]
Next, a method for cleaning the surface of the wafer 10 using the wafer surface cleaning apparatuses 100 and 200 as described above will be explained in detail with reference to FIGS. 1 and 2.

<First embodiment>
A method for cleaning a wafer surface using the wafer surface cleaning apparatus 100 includes a step of installing a wafer 10 in a cleaning tank 1, and a gas supplying an easily soluble gas to the surface 11 of the wafer 10 installed in the cleaning tank 1. The supply process mainly includes a solution supply process for supplying a mixed solution of water and alcohol to the surface 11 of the wafer 10 after the easily soluble gas has been supplied in the gas supply process. The gas supply process and the solution supply process are performed continuously.

[Wafer installation process]
First, in a wafer installation step, the wafer 10 is installed in a wafer holder of the cleaning tank 1.

[Gas supply process]
Next, in the gas supply step, easily soluble gas is supplied by the gas supply means 2 to the surface 11 of the wafer 10 placed in the cleaning tank 1 . As a result, the surface 11 of the wafer 10 is covered with the easily soluble gas, and the inside of the recess 12 having a high aspect ratio is also filled with the easily soluble gas.

In the gas supply step, in order to dissolve the easily soluble gas remaining on the wafer 10 into the mixed solution of water and alcohol in the subsequent solution supply step, even after supplying the easily soluble gas, The easily soluble gas covers the surface 11 of the wafer 10 and fills the inside of the recess 12 .

Here, the term "easily soluble gas" refers to a gas that is easily soluble in water, and includes, for example, N ₂ gas, CO ₂ gas, and the like. In this embodiment, the easily soluble gas is preferably N ₂ gas or CO ₂ gas, and particularly preferably CO ₂ gas. When the easily soluble gas is N ₂ gas or CO ₂ gas, dissolution in the mixed solution of water and alcohol is performed more quickly.

[Solution supply process]
In the solution supply step, a mixed solution of water and alcohol is supplied by the solution supply means 103 to the surface 11 of the wafer 10 after the gas supply step. As a result, the easily soluble gas that covers the surface 11 of the wafer 10 and fills the inside of the recess 12 is dissolved in the mixed solution, so that the inside of the recess 12 with a high aspect ratio can be sufficiently cleaned with the mixed solution. Can be done.

Furthermore, by supplying a mixed solution of water and alcohol to the recesses 12 filled with easily soluble gas, the easily soluble gas is quickly dissolved in the mixed solution, so that the rate of water infiltration into the recesses 12 becomes faster. , the throughput of wafer cleaning can be improved.

Note that after the solution supply step, a drying step of drying the wafer 10 by a known method such as spin drying can be performed.

<Second embodiment>
Next, a method for cleaning the surface of the wafer 10 using the wafer surface cleaning apparatus 200 will be described with reference to FIG. The method for cleaning the surface of a wafer 10 using the wafer surface cleaning apparatus 200 includes the first step, except that it further includes a degassing step for degassing the mixed solution of water and alcohol before the solution supply step. Since this method has the same configuration as the wafer surface cleaning method using the wafer surface cleaning apparatus 100 according to the embodiment, only the degassing step will be described below.

[Degassing process]
In the degassing process, the degassing membrane module 38 performs a degassing process on the mixed solution of water and alcohol before being supplied to the surface 11 of the wafer 10 in the solution supply process. Thereby, generation of bubbles can be prevented. Furthermore, in the solution supply step, by supplying a mixed solution of degassed water and alcohol to the surface 11 of the wafer 10 after the gas supply step, dissolution of the easily soluble gas into the mixed solution is promoted. The rate of flooding increases.

As described above, according to the wafer surface cleaning apparatus and the wafer surface cleaning method of the present invention, the amount of alcohol used is small compared to conventional cleaning using only alcohol such as IPA or ethanol, so Cost and environmental impact can be reduced. Further, by supplying a mixed solution of water and alcohol to the surface 11 of the wafer 10 after the easily soluble gas has been supplied, the easily soluble gas is quickly dissolved in the mixed solution, so that the wafer surface 11 Adhering contaminants such as fine particles can be effectively removed. Even if fine grooves or holes are formed on the surface 11 of the wafer 10 by dry etching, the mixed solution can be easily supplied to the grooves or holes filled with easily soluble gas. Since the soluble gas quickly dissolves into the mixed solution, the rate of water infiltration into the grooves or holes becomes faster, and contaminants such as particulates remaining inside the grooves or holes can be effectively removed, as well as wafer cleaning. throughput can be improved.

Although the present invention has been described above with reference to the drawings, the present invention is not limited to the above embodiments, and various modifications can be made. In the above embodiment, an immersion type cleaning device that immerses the wafer in a liquid is used as a cleaning device for the wafer surface. The present invention is not limited to this, and for example, a single-wafer cleaning device that sprays liquid onto the wafer may be used.

EXAMPLES Hereinafter, the present invention will be further explained in detail based on Examples, but the present invention is not limited to the following Examples.

Using the wafer surface cleaning apparatus shown in FIGS. 1 to 4, the surface of the wafer 10 shown in FIG. 5 was cleaned. An immersion type cleaning device was used for cleaning. Note that the wafer surface cleaning apparatus 300 shown in FIG. It has the following configuration. The wafer surface cleaning apparatus 400 shown in FIG. They have almost the same configuration.

The washing conditions are as follows.
<Sample wafer>
・Material: Si wafer (trenches are formed on the wafer surface using dry etching technology)
・Groove: width 30nm, depth 300nm, depth 10nm
・Surface composition: Hydrophobic (surface modified with hydrophobic polymer BUTS)
・Surface contact angle: 130°
<Easily soluble gas>
・Type: _CO2 gas (99.9% purity)
・Gas supply: 1L/min. ×5min.
<alcohol>
・Type: IPA (purity 98%)
・Supply concentration: 3 mol% ~
〈Flooding evaluation method〉
・Measuring equipment: ATR-FTIR
-Measurement method: IR irradiation was performed from the back side of the wafer sample, and the water immersion rate was calculated from the height of the OH-stretch peak on the wafer sample surface.

[Example 1]
A wafer sample was cleaned using a wafer surface cleaning apparatus 100 shown in FIG. First, a wafer sample was placed in the cleaning tank 1, and after a readily soluble gas was supplied for 5 minutes, a mixed solution of ultrapure water and alcohol (alcohol concentration 3 to 5 mol/%) was supplied. The water immersion rate of the wafer sample after cleaning was calculated using ATR-FTIR.

[Example 2]
A wafer sample was cleaned using a wafer surface cleaning apparatus 100 shown in FIG. First, a wafer sample was placed in the cleaning tank 1, and after an easily soluble gas was supplied for 5 minutes, a mixed solution of ultrapure water and alcohol (alcohol concentration 10 mol/%) was supplied. The water immersion rate of the wafer sample after cleaning was calculated using ATR-FTIR.

[Example 3]
A wafer sample was cleaned using a wafer surface cleaning apparatus 100 shown in FIG. First, a wafer sample was placed in the cleaning tank 1, and after an easily soluble gas was supplied for 5 minutes, a mixed solution of ultrapure water and alcohol (alcohol concentration of 10 mol/% or more) was supplied. The water immersion rate of the wafer sample after cleaning was calculated using ATR-FTIR.

[Example 4]
A wafer sample was cleaned using a wafer surface cleaning apparatus 200 shown in FIG. First, a wafer sample was placed in the cleaning tank 1, and an easily soluble gas was supplied for 5 minutes, and then a mixed solution of ultrapure water and alcohol (alcohol concentration 3 to 5 mol/%) was degassed and then supplied. The water immersion rate of the wafer sample after cleaning was calculated using ATR-FTIR.

[Comparative example 1]
A wafer sample was cleaned using a wafer surface cleaning apparatus 300 shown in FIG. First, a wafer sample was placed in the cleaning tank 1, and after an easily soluble gas was supplied for 5 minutes, only ultrapure water was supplied. The water immersion rate of the wafer sample after cleaning was calculated using ATR-FTIR.

[Comparative example 2]
A wafer sample was cleaned using a wafer surface cleaning apparatus 400 shown in FIG. First, a wafer sample was placed in the cleaning tank 1, and after an easily soluble gas was supplied for 5 minutes, only ultrapure water was degassed and then supplied. The water immersion rate of the wafer sample after cleaning was calculated using ATR-FTIR.

For Examples 1-4 and Comparative Examples 1 and 2, the time taken to complete immersion in water is shown in Table 1 along with the cleaning conditions. From this result, it was confirmed that the water immersion speed was increased by using a mixed solution of ultrapure water and alcohol containing 3 mol/% or more of alcohol (IPA) relative to the ultrapure water. It was also found that the rate of water immersion was further increased by deaerating the mixed solution before use.

As explained above, according to the wafer surface cleaning apparatus and wafer surface cleaning method of the present invention, running costs and environmental loads can be reduced, and multiple fine particles can be formed on the wafer surface by dry etching. Even when grooves or holes are formed, contaminants such as fine particles remaining inside the grooves or holes can be effectively removed, and by increasing the rate of water infiltration into the grooves or holes, The throughput of wafer cleaning can be improved.

The present invention provides a method for removing contaminants such as fine particles attached to the wafer surface and fine particles remaining inside the grooves or holes, especially from wafers in which grooves or holes have been formed by dry etching in the semiconductor manufacturing process. It is useful as a cleaning device and cleaning method.

10 Wafer 11 Surface 12 Recess 13 Width of recess 14 Depth of recess 100, 200 Wafer surface cleaning device 1 Cleaning tank 2 Gas supply means 21 Gas pressure regulator 22 Mass flow meter 23 Filter 3 Solution supply means 31 Flow meter 32 Solution mixing chamber 33 Online TOC meter 34 Mass flow meter 35 Filter 36 Storage tank 37 Liquid pump 38 Degassing membrane module 39 Vacuum pump L1, L2, L3 Piping

Claims (8)

A cleaning tank,
a gas supply means for supplying CO ₂ gas to the surface of the wafer installed in the cleaning tank;
A cleaning device for the surface of a wafer, comprising: a solution supply means for supplying a mixed solution of water and alcohol to the surface of the wafer after the CO ₂ gas is supplied by the gas supply means. The wafer surface cleaning apparatus according to claim 1 , wherein the mixed solution contains alcohol in a range of 3 mol/% or more and 10 mol/% or less based on ultrapure water. 3. The wafer surface cleaning apparatus according to claim 1, wherein the alcohol is isopropyl alcohol or ethanol. The wafer surface cleaning apparatus according to any one of claims 1 to 3 , further comprising a degassing membrane module for degassing the mixed solution. _a gas supply step of supplying CO2 gas to the surface of the wafer placed in the cleaning tank;
A method for cleaning the surface of a wafer, comprising a solution supply step of supplying a mixed solution of water and alcohol to the surface of the wafer after the CO ₂ gas has been supplied in the gas supply step. 6. The method for cleaning a wafer surface according to claim 5 , wherein the mixed solution contains alcohol in a range of 3 mol/% or more and 10 mol/% or less based on ultrapure water. The method for cleaning a wafer surface according to claim 5 or 6, wherein the alcohol is isopropyl alcohol or ethanol. The method for cleaning a wafer surface according to any one of claims 5 to 7 , further comprising a degassing process for degassing the mixed solution before the solution supplying process.

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