KR20050049246A - Cleaning and dry method for wafer - Google Patents

Abstract

The present invention relates to a washing drying method. According to the present invention, a substrate is placed on a spin chuck and a chemical cleaning solution is supplied onto the substrate while the spin chuck is rotated at a predetermined speed to clean the substrate, and the substrate is rinsed by supplying a rinse liquid to the rotating substrate. In addition, while supplying a drying liquid uniformly spread over the entire surface of the substrate without agglomeration in the form of water droplets to the surface of the rotating substrate, the surface of the substrate is dried by supplying a dry gas from a portion where the drying liquid is supplied. In this way, if the drying liquid is evenly spread on the wafer without clumping in the form of water droplets, the drying liquid is completely dried by the drying gas so that water spots do not occur on the wafer.

Description

CLEANING AND DRY METHOD FOR WAFER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning drying method, and more particularly, to a cleaning drying method in which a substrate is dried so that water marks do not occur.

In general, a semiconductor device manufacturing process is roughly divided into a deposition process, a photographic process, an etching process, an ion implantation process, a polishing process, and a cleaning drying process, and a plurality of semiconductor devices are formed on a wafer when these processes are repeatedly performed. .

Among the above-described processes, the cleaning drying process removes residues and particles remaining on the wafer after performing the respective unit processes, and has emerged as a more important process in recent design rules requiring fine patterns.

The apparatus for cleaning and drying wafers includes a batch apparatus for processing a plurality of wafers at one time and a sheet type apparatus for processing wafers in sheets. The batch type washing and drying apparatus has a disadvantage in that it is not easy to cope with the increase in size of the wafer and uses a lot of cleaning solution. In addition, breakage of the wafer affects the entire wafer during the cleaning drying process. For this reason, a single sheet washing drying apparatus has recently been preferred.

In the method of cleaning and drying a wafer using a single wafer cleaning and drying apparatus, the spin chuck is rotated at a high speed while one wafer is placed on the spin chuck. Subsequently, a chemical cleaning solution is supplied to the surface of the wafer rotating at high speed to clean foreign substances remaining on the surface of the wafer. A rinse liquid, for example, pure water, is supplied to the cleaned wafer surface to rinse the wafer, and then a dry gas is supplied to dry the wafer surface. Dry gas is nitrogen gas mixed with isopropyl alcohol (isopropylalcohol).

However, when fabricating a semiconductor device, when a low dielectric film is deposited on a wafer in order to lower the dielectric constant of an interlayer insulating film, the surface of the wafer is not completely dried in the drying step, and pure water reacts with oxygen in air to generate water spots on the wafer. . This is because the low dielectric film used as the interlayer insulating film has hydrophobicity, and thus the pure water used as the rinse liquid does not spread evenly over the entire surface of the wafer, but in the form of droplets, the pure water is not completely dried in the drying step and generates water spots.

If water spots are generated on the wafer due to the above-described reasons, serious problems may occur such as peeling phenomenon or subsequent leakage current between wirings in a subsequent deposition process.

Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to dry a wafer so that water spots are not generated by supplying a dry gas in a state in which a rinse liquid is evenly spread on the entire surface of the wafer.

In order to realize the object of the present invention, the present invention is a step of placing the substrate on the spin chuck and rotating the spin chuck at a predetermined speed supplying a chemical cleaning solution to the substrate surface to clean the substrate, to the rotating substrate Rinsing the substrate by supplying the rinse liquid and supplying the dry gas from the portion where the dry liquid is supplied to the surface of the substrate while supplying the drying liquid that spreads uniformly over the entire surface of the substrate without clumping in the form of droplets It provides a cleaning drying method comprising the step of drying.

Preferably, the drying liquid is a mixture of isopropyl alcohol and a predetermined ratio in pure water.

Hereinafter, the cleaning and drying method according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a conceptual diagram of a cleaning drying apparatus according to the present invention.

Referring to FIG. 1, the cleaning drying apparatus 100 which performs the cleaning drying process of the wafer may include a chamber 100, a spin chuck 120, a cover 130, a fluid storage unit 140, and a fluid supply unit 150 and 160. 170), transfer devices 180 and 185 and a control unit (not shown). The control unit controls the washing and drying apparatus as a whole.

The spin chuck 120 is a portion in which the wafer 10 on which the cleaning and drying process is to be placed is placed, and is installed in the chamber 110. The center of the lower surface of the spin chuck 120 is provided with a rotating shaft 122 for supporting the spin chuck 120 and transmitting the rotation force. The first drive motor 124 for rotating the spin chuck 120 at high speed is connected to the rotation shaft 122.

The cover 130 is composed of a cover body 132 and an outlet 134. The cover body 132 is installed around the spin chuck 120 and prevents various liquids supplied to the wafer 10 from splashing out of the cover 130 during the cleaning drying process. The outlet 134 is installed on the lower surface of the cover body 132 to discharge various liquids collected in the cover body 132 to the outside of the chamber 100.

The fluid storage unit 140 includes a washing liquid storage unit 142, a pure water storage unit 144, an isopropyl alcohol storage unit 146, and a nitrogen gas storage unit 148.

The fluid supply part includes a first fluid supply part 150, a second fluid supply part 160, and a third fluid supply part 170.

The first fluid supply unit 150 supplies the cleaning liquid and the rinse liquid to the surface of the wafer 10. The first fluid supply unit 150 includes a first nozzle 151, a cleaning liquid supply pipe 153, and a rinse liquid supply pipe 155. The first nozzle 151 is installed above the spin chuck 120 and is spaced apart from the spin chuck 120 by a predetermined interval. The first nozzle 151 supplies the cleaning liquid and the rinse liquid to the wafer 10. The cleaning solution supply pipe 153 is connected to the first nozzle 151 and the cleaning solution storage unit 142 to supply the cleaning solution stored in the cleaning solution storage unit 142 to the first nozzle 151. A predetermined valve 153a is provided at a predetermined portion of the cleaning liquid supply pipe 153 to open and close the cleaning liquid supply pipe 153 according to a control signal of the controller. The rinse liquid supply pipe 155 is connected to the first nozzle 151 and the pure water storage unit 144 to supply the rinse liquid, that is, pure water to the first nozzle 151. A predetermined valve of the rinse liquid supply pipe 155 is provided with a second valve 155a for opening and closing the rinse liquid supply pipe 155 according to a control signal of the controller.

The second fluid supply unit 160 supplies a dry liquid having good spreadability to the surface of the hydrophobic wafer 10 by depositing a low dielectric film to prevent water spots on the wafer 10 in a drying process. The second fluid supply unit 160 includes a second nozzle 161, a dry liquid mixing unit 162, a first isopropyl alcohol supply pipe 163, a pure water supply pipe 165, and a dry liquid supply pipe 167. The second nozzle 161 is installed above the spin chuck 120 and is spaced apart from the spin chuck 120 by a predetermined interval.

The dry liquid mixing unit 162 is a device that mixes pure water and isopropyl alcohol at an appropriate ratio to form a dry liquid. Mixing pure water with isopropyl alcohol lowers the surface tension of the drying solution. Therefore, when a dry liquid mixed with pure water and isopropyl alcohol is supplied to the surface of the wafer 10 having hydrophobicity, the dry liquid is more easily spread to a uniform thickness over the entire surface of the wafer 10. 2 is a view showing the extent to which the drying liquid is spread according to the mixing ratio of pure water and isopropyl alcohol. 2, the higher the mixing ratio of isopropyl alcohol than the mixing ratio of pure water, the lower the contact angle between the drying liquid and the surface of the wafer 10, the lower the surface tension of the drying liquid and the better the spreadability. As shown in E of FIG. 4, when the isopropyl alcohol is used without mixing with pure water 100%, the spreadability of the dry liquid is best. Therefore, only isopropyl alcohol may be used for a dry liquid. However, when 100% isopropyl alcohol is used as the drying liquid, since the volatility is strong, the drying liquid may be evaporated before the drying process is completed and water spots may be generated on the wafer 10. In addition, since isopropyl alcohol is sensitive to fire, there is a high risk of fire occurring during the drying process. For this reason, it is preferable that the density | concentration of the isopropyl alcohol mixed with pure water is between 10% and 90%.

The first isopropyl alcohol supply pipe 163 is connected to the dry liquid mixing unit 162 and the isopropyl alcohol storage unit 146 to supply isopropyl alcohol to the dry liquid mixing unit 162. The pure water supply pipe 165 is connected to the dry liquid mixing unit 162 and the pure water storage unit 144 to supply pure water to the dry liquid mixing unit 162. A third valve 163a is installed in the first isopropyl alcohol supply pipe 163 and a fourth valve 164a is installed in the pure water supply pipe 165. The third valve 163a and the fourth valve 165a open and close the first isopropyl alcohol supply pipe 163 and the pure water supply pipe 165 according to the control signal of the controller to mix the isopropyl alcohol and the pure water in a set ratio. Supply to section 162.

The dry liquid supply pipe 167 is connected to the dry liquid mixing unit 162 and the second nozzle 162 to supply the dry liquid to the second nozzle 162. The dry liquid supply pipe 167 is provided with a fifth valve 167a to open and close the dry liquid supply pipe 167 according to a control signal of the controller.

The third fluid supply unit 170 supplies a dry gas for drying the drying liquid uniformly spread on the surface of the wafer 10 to the surface of the wafer 10. The third fluid supply unit 170 includes a third nozzle 171, a dry gas mixing unit 172, a second isopropyl alcohol supply pipe 173, a nitrogen gas supply pipe 175, and a dry gas supply pipe 177. The third nozzle 171 is installed at the same height as the second nozzle 161. The third nozzle 171 is installed behind the second nozzle 161 based on the moving direction of the second nozzle 161. That is, the third nozzle 171 is installed between the second nozzle 161 and the outer circumference of the spin chuck 120, and the third nozzle 171 is in contact with the second nozzle 161.

The dry gas mixing unit 172 is a device for mixing isopropyl alcohol and nitrogen gas. Due to the pressure of the nitrogen gas supplied to the dry gas mixing unit 172, the isopropyl alcohol in the liquid state supplied to the dry gas mixing unit 172 becomes a fine droplet form.

The second isopropyl alcohol supply pipe 173 is connected to the dry gas mixing unit 172 and the isopropyl alcohol storage unit 146 to supply isopropyl alcohol to the dry gas mixing unit 172. The nitrogen gas supply pipe 175 is connected to the dry gas mixing unit 172 and the nitrogen gas storage unit 148 to supply the nitrogen gas dry gas mixing unit 172. The sixth valve 173a is installed in the second isopropyl alcohol supply pipe 173, and the seventh valve 175a is installed in the nitrogen gas supply pipe 175. The sixth valve 173a and the seventh valve 175a open and close the second isopropyl alcohol supply pipe 173 and the nitrogen gas supply pipe 175 according to the control signal of the controller to set the isopropyl alcohol and the nitrogen gas at a predetermined ratio and pressure. By the way, it supplies to the dry gas mixing part 172.

The dry gas supply pipe 177 is connected to the dry gas mixing unit 172 and the third nozzle 172 to supply the dry gas to the third nozzle 172. An eighth valve 177a is installed in the dry gas supply pipe 177 to open and close the dry gas supply pipe 177 according to a control signal of the controller.

The first nozzle 151, the second nozzle 161, and the third nozzle 171 described above move from the portion corresponding to the center of the wafer 10 toward the portion corresponding to the outer circumferential surface of the wafer 10, and the wafer 10. ) And clean. The first nozzle 151, the second nozzle 161, and the third nozzle 171 are moved by the moving devices 180 and 185. The moving devices 180 and 185 are composed of a first moving device 180 and a second moving device 185. The first moving unit 180 and the second moving unit 185 are installed to face each other with respect to the center of the wafer 10. The first moving device 180 is connected to the first nozzle 151 and moves the first nozzle 151 from the center of the wafer 10 toward the outer circumferential surface of the wafer 10. The second moving device 185 is connected to the second nozzle 161 and the third nozzle 171 so that the second nozzle 161 and the third nozzle 171 are simultaneously located at the center of the wafer 10. Move toward the outer circumference of the Reference numeral 183 denotes a second driving motor for driving the first moving device 180, and reference numeral 187 denotes a third driving motor for driving the second moving device 185.

The process of cleaning and drying a wafer using such a cleaning drying apparatus is as follows.

3 is a flow chart for explaining the cleaning drying method of the wafer according to the present invention, Figure 4 is a view for explaining the drying method of FIG.

1 and 3, the wafer 10 on which the cleaning and drying process is to be performed is placed on the upper surface of the spin chuck 120, and a vacuum pressure is generated on the upper surface of the spin chuck 120. Fix it. Subsequently, the spin chuck 120 is rotated at a high speed by driving the first driving motor 124.

Subsequently, the first nozzle 151 of the first fluid supply unit 150 is positioned at the center of the wafer 10, and the cleaning solution supply pipe 153 is opened to clean the cleaning solution, for example, on the surface of the rotating wafer 10. Supply a chemical cleaning solution containing ammonia solution and hydrogen peroxide solution. Then, foreign substances remaining on the surface of the wafer 10 are removed by the supply of the cleaning liquid and the rotation of the spin chuck 120 (S200).

The cleaning liquid supply pipe 153 is closed and the rinsing liquid supply pipe 155 is opened to supply a rinse liquid, for example, pure water, to the surface of the rotating wafer to remove the cleaning liquid and foreign substances remaining on the surface of the wafer 10. (S210).

When the cleaning of the wafer is completed, the drying solution and the drying gas are supplied to the wafer 10 to dry the wafer 10 so that water spots do not occur on the wafer 10 (S220).

First, the second moving device 185 is driven to position the second nozzle 161 of the second fluid supply unit 160 at the center of the wafer 10, and open the drying liquid supply pipe 167. Then, the drying liquid mixed with pure water and isopropyl alcohol is supplied to the wafer 10 through the drying liquid supply pipe 167 and the second nozzle 161 (S222). The surface tension of the drying liquid supplied to the wafer 10 is lower than when using 100% pure water as in the prior art. Therefore, when the wafer 10 is rotated by the spin chuck 120, the drying liquid is spread evenly within a short time without aggregation of water droplets on the surface of the hydrophobic wafer 10.

Referring to FIG. 3, when the drying liquid is supplied to the center of the wafer 10 through the second nozzle 161, the drying gas supply pipe 177 is opened. Then, the dry gas in which isopropyl alcohol and nitrogen gas are mixed is supplied to the wafer 10. As such, when the drying liquid and the drying gas are supplied to the wafer 10 through the second nozzle 161 and the third nozzle 171, the second moving device 185 is moved from the center portion of the wafer 10 to the wafer 10. ) To the outer circumferential surface. At this time, the third nozzle 171 follows the second nozzle 161. Then, the drying liquid supplied to the wafer 10 through the second nozzle 161 is dried by the drying gas supplied from the third nozzle 171.

As described above, the reason why the drying liquid is supplied to the wafer 10 in the drying step S220 is to prevent water spots from occurring on the wafer 10. That is, when the drying liquid is not supplied to the wafer 10 in the drying step S220, pure water remaining on the surface of the wafer in the rinsing step S210 may be aggregated in the form of droplets due to the hydrophobicity of the wafer 10. Pure water aggregated in the form is not completely dried by dry gas. In this case, pure water remaining in the wafer 10 and oxygen in the air react to generate water spots on the wafer 10.

In addition, even if the drying liquid is supplied to the wafer 10 in the drying step (S220), if the surface tension of the drying liquid is high, the drying liquid does not spread evenly on the surface of the wafer 10 having hydrophobicity, and the drying liquid is in the form of droplets in a predetermined portion. To be united. This creates water spots on the wafer surface. Therefore, the drying liquid supplied to the wafer 10 in the drying step S220 should be spread evenly within a quick time without agglomeration in the form of water droplets on the surface of the wafer 10 having hydrophobicity as in the present invention.

As described in detail above, the dry liquid containing isopropyl alcohol can be prevented from occurring on the surface of the wafer by spreading it evenly within a rapid time without aggregation of water droplets on the surface of the hydrophobic wafer.

1 is a conceptual diagram of a cleaning drying apparatus according to the present invention.

2 is a view showing the extent to which the drying liquid is spread according to the mixing ratio of pure water and isopropyl alcohol.

3 is a flowchart for explaining a method of cleaning and drying a wafer according to the present invention.

4 is a view for explaining the drying method of FIG.

Claims (5)

Placing the substrate on a spin chuck and supplying a chemical cleaning solution to the substrate while rotating the spin chuck at a predetermined speed to clean the substrate; Rinsing the substrate by supplying a rinse liquid to the rotating substrate; Supplying a dry gas from a portion to which the drying liquid is supplied while supplying a drying liquid uniformly spread over the entire surface of the substrate without agglomeration in the form of water droplets to dry the surface of the substrate; The washing and drying method characterized by the above-mentioned. The method of claim 1, wherein the drying liquid is isopropyl alcohol mixed with pure water in a predetermined ratio. The washing and drying method according to claim 2, wherein the ratio of isopropyl alcohol mixed with the pure water is between 10% and 90%. The method of claim 1, wherein the drying liquid is isopropyl alcohol. The method of claim 1, wherein the drying gas comprises isopropyl alcohol.