JPS6384119A - Cleaning of substrate - Google Patents

Abstract

PURPOSE:To reduce a cleaning cost and a waste liquid amount by injecting a reaction gas containing O radical and cleaning solution to the surface of a substrate to remove the adhered material on the substrate. CONSTITUTION:A cleaning solution and O2 containing O3 are injected from holes 4a, 4b disposed at near positions to a nozzle 4, a vapor/liquid mixture stream is heated by a heater 7 of porous holes 7a to generate O radical to decompose the adhered organic material on an Si wafer 2 into CO2, CO, H2O to be removed, and the adhered material is cleaned with the cleaning solution. Accordingly, the organic material and the inorganic material can be removed in a short time to clean the waste liquid of small amount inexpensively. The temperature of the heater 7 is held at 150-500 deg.C during the cleaning to accelerate the decomposition of O3, and a pipe which contains O3 is held at 25 deg.C or lower by a cooling pipe 5a. The cleaning solution is selected according to the adhered material, and the flow rates of the solution and the gas are selected. After the vapor and the liquid are separated by a separator 15, it is evacuated by a unit 16 to held the vapor pressure in a treating chamber 1 to approx. 700-200 Torr.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a substrate cleaning method for removing deposits from the surface of a substrate such as a semiconductor wafer.

(Prior Art) For example, on the surface of a substrate such as a semiconductor wafer, deposits made of organic substances generated from the human body, etc. during the manufacturing process, etc.
Various deposits such as inorganic deposits generated from machinery etc. adhere to the surface. Substrate cleaning methods for removing such deposits include a wet cleaning method using a conventional cleaning liquid and a dry cleaning method using plasma or the like.

A common dry cleaning method uses oxygen plasma. In the cleaning method using oxygen plasma, a semiconductor wafer is placed in a processing chamber, oxygen gas introduced into the processing chamber is turned into plasma by a high-frequency electric field, and deposits made of organic matter are removed by the oxygen plasma.

In addition, in the wet cleaning method, a semiconductor wafer is placed in a processing chamber, and H2SO4, H202, H2
Cleaning is performed by spouting out one or more cleaning liquids such as 0, HCJ2, HF, NH40H, ozone water, or the like, or by immersing the semiconductor wafer in the cleaning liquid.

(Problems to be Solved by the Invention) However, among the conventional cleaning methods described above, the dry cleaning method can only remove deposits made of organic matter, but it is difficult to remove deposits made of inorganic matter. There is a problem.

In addition, with the wet cleaning method, it is easy to remove inorganic deposits, but it takes time to remove organic deposits, resulting in longer cleaning times and increased consumption of cleaning solution. However, there are problems such as an increase in cleaning costs and an increase in the amount of waste liquid.

The present invention has been made in response to such conventional circumstances,
It is an object of the present invention to provide a method for cleaning a substrate, which can remove both organic and inorganic deposits by cleaning in a short time, reducing cleaning costs, and reducing the amount of waste liquid.

[Structure of the Invention] (Means for Solving the Problems) That is, the substrate cleaning method of the present invention includes jetting a reactive gas containing oxygen atom radicals and a cleaning liquid toward the substrate surface to remove the adhesion on the substrate surface. It is characterized by removing the kimono.

(Function) In the substrate cleaning method of the present invention, a reactive gas containing oxygen atom radicals and a cleaning liquid are ejected toward the substrate surface,
Remove deposits from the substrate surface.

For example, a gas containing oxygen atomic radicals and a cleaning liquid are simultaneously ejected toward the substrate surface, and deposits on the substrate surface are removed by a gas-liquid multiphase flow of the gas containing oxygen atomic radicals and the cleaning liquid.

Therefore, due to the oxidative chemical reaction between oxygen atom radicals and organic matter, deposits made of organic matter are oxidized and decomposed into carbon dioxide, -carbon oxide, and water and removed, and at the same time, deposits made of inorganic matter are removed by the cleaning solution. It is possible to perform cleaning in a short time, at low cost, and with a small amount of waste liquid.

(Example) Hereinafter, an example of the substrate cleaning method of the present invention will be described with reference to the drawings.

FIG. 1 shows a cleaning apparatus used in a method according to an embodiment of the present invention. In the cleaning apparatus of this embodiment, a semiconductor wafer 2 is held in a processing chamber 1 by holding the peripheral edge of the semiconductor wafer 2. A holding mechanism 3 is arranged to hold the holder in an upright position.

On both sides of this holding mechanism 3, two-fluid nozzles 4 are arranged, which are composed of, for example, an opening 4a for spouting cleaning liquid and an opening 4b for spouting gas disposed close to the opening 4a. A cooling pipe 5a connected to the cooling device 5 is disposed around the pipe connected to the opening 4b of the two-fluid nozzle 4 through which gas is ejected.

Further, between the holding a ellipse 3 and the two-fluid nozzle 4, there is a heater 7 which is controlled by a temperature control device 6 and is formed in a disk shape and has a large number of through holes 7a as shown in FIG. is located.

The opening 4b of the two-fluid nozzle 4 is connected to the gas miscarriage regulator 8.
The openings 4a are connected to an ozone generator 10 which is connected to an oxygen supply source 9 via a cleaning liquid supply source 1.
Cleaning liquid flow rate regulators 12a, 1 connected to 1a, llb
2b.

A waste liquid discharge port 13 is provided at the bottom of the processing chamber 1, and the waste liquid discharge port 13 is connected to a waste liquid device 14 that processes waste liquid.
It is connected to the. Further, a gas-liquid separator 15 is arranged in the upper part of the processing chamber 1, and this gas-liquid separator 15
It is connected to the exhaust device 16.

Then, using the cleaning device having the above configuration, cleaning is performed in the following manner.

That is, first, the semiconductor wafer 2 is placed on the holding mechanism 3 using a wafer transfer device (not shown) or the like and held in an upright position.

Next, the flow rate of the oxygen gas supplied from the oxygen supply source 9 is adjusted by the gas flow rate regulator 8, and the gas is sent into the ozone generator 10, where it is passed from the cooling device 5 to the cooling pipe 5a as oxygen gas containing ozone. The liquid is ejected from the opening 4b of the two-fluid nozzle 4 toward the semiconductor wafer 2 in the processing chamber 1 through a pipe cooled to, for example, about 25° C. by cooling water or the like that is circulated therein.

At this time, H2SO4, H202, H20, HCA, and HP are simultaneously supplied from the cleaning liquid supply sources 11a and llb.
, NH4OH, ozone water, etc. are adjusted in flow rate by the cleaning liquid flow rate regulators 12a and 12b, and the two-fluid nozzle 4
One or more types of gas are ejected toward the semiconductor wafer 2 from the opening 4 a , and a gas-liquid multiphase flow of oxygen gas containing ozone and a cleaning liquid is ejected toward the semiconductor wafer 2 .

Note that the cleaning liquid is used in combination, depending on the type of deposits, etc., in the same way as in conventional wet cleaning equipment. Further, the flow rate of the oxygen gas containing ozone and the cleaning liquid is determined by, for example, the flow rate of the oxygen gas containing ozone being 10j2/1M1, as shown by curve A in the graph of FIG. 3, where the vertical axis is the flow rate and the horizontal axis is time.
It is also possible to change the air-liquid flow rate ratio arbitrarily during cleaning, such as by gradually decreasing the flow rate of the cleaning liquid from about It is also possible to perform only cleaning, or just wet cleaning immediately before the end of cleaning. 'Furthermore, the heater 7 is controlled to have a temperature of, for example, 150°C to 50°C by the temperature control device 6.
The exhaust device 16 heats the gas-liquid multiphase flow flowing out from the two-fluid nozzle 4 at a temperature of about 00°C, and exhausts the gas separated by the gas-liquid separator 15, for example, into the processing chamber 1. In other words, in the substrate cleaning method of this embodiment described above, the gas pressure in the two-fluid nozzle 4 is set to about 700 to 200 Torr.
The cleaning liquid and oxygen gas containing ozone are simultaneously ejected from b to form a gas-liquid multiphase flow, and this gas-liquid multiphase flow is heated by the heater 7 to generate oxygen atomic radicals from the ozone, resulting in chemical oxidation by the oxygen atomic radicals. The organic matter deposited on the surface of the semiconductor wafer 2 due to the reaction is decomposed into carbon dioxide, -carbon oxide, and water and removed, and the inorganic deposit is also cleaned with the cleaning solution. Both deposits can be removed in a short time, and cleaning can be performed at low cost and with a small amount of waste liquid.

Note that the lifespan of ozone generated by the ozone generator 10 is
As shown in the graph of Figure 4, where the vertical axis is the half-life of ozone decomposition and the horizontal axis is the temperature of the ozone-containing gas, as the temperature increases, ozone decomposition is accelerated and its lifespan rapidly shortens. Becomes shorter. Therefore, the temperature of the heater 7 during the cleaning process, which is performed using the oxidation reaction by oxygen atom radicals generated by decomposition of ozone, is 150°C to 500°C.
It is preferable that the temperature of the pipe through which the oxygen gas containing ozone cooled by the cooling pipe 5a is about 25°C or lower.

Further, the semiconductor wafer 2 can be dried by heating with the heater 7, but it may also be configured to rotate the semiconductor wafer 2 or apply nitrogen gas or the like, for example.

Furthermore, the heater 7 includes a heater 20 having a plurality of concentric slits 20a as shown in FIG. 5, a heater 21 having a linear slit 21a as shown in FIG. 6, and a heater 21 having a linear slit 21a as shown in FIG. As shown in FIG.
3at! - The heater 23 may have any shape, such as a heater 23 with a radial slit 24a as shown in FIG. 9, a heater 25 with a large number of small holes 25a as shown in FIG.

FIG. 11 shows a cleaning apparatus in the second embodiment method, in which a holding mechanism 33 for holding a semiconductor wafer 32 in an upright position is arranged in a processing chamber 31.

On both sides of this holder 111i33, as shown in FIG. 12, there is a diffusion plate 34 in which a large number of parallel linear slits 34a are arranged in a disk-shaped plane having a slightly larger diameter than the semiconductor wafer 32. The gas/cleaning liquid outlet 35 provided with
A gas/cleaning liquid outlet 35 is disposed facing the semiconductor wafer 32 at a close interval of, for example, about 0.5 to 20 In1.
A cooling pipe 36a connected to a cooling device 36 is arranged inside.

Furthermore, between the retainer tR33 and the gas/cleaning liquid outflow section 35, a temperature control device 37 is used to control the temperature control device 37, and as shown in FIG. A filter 38 with a filter 38a is arranged.

The gas/cleaning liquid outlet 35 is connected to an ozone generator 42 connected to an oxygen supply source 41 via a gas flow rate regulator 40 and to cleaning liquid supply sources 44a and 44b, respectively, through three gas/cleaning liquid switching valves. It is connected to the connected cleaning liquid flow rate regulators 43a and 43b.

A waste liquid discharge port 45 is provided at the bottom of the processing chamber 31, and the waste liquid discharge port 45 is connected to the waste liquid device 4 that processes waste liquid.
6. Further, a gas-liquid separator 47 is arranged in the upper part of the processing chamber 31, and an exhaust port 48 is arranged around the gas/cleaning liquid outlet 35.
The exhaust port 48 is connected to an exhaust device 49.

In the cleaning apparatus of this embodiment having the above configuration, cleaning is performed as follows.

That is, first, the semiconductor wafer 32 is placed on the holding i-top 33 by a wafer transfer device (not shown) and held in an upright position.

Next, the three gas/cleaning liquid switching valves are connected to the ozone generator 42.
The oxygen gas supplied from the oxygen supply source 41 is adjusted by the gas flow rate regulator 40 so that the flow rate is, for example, about 3 to 15 bu/m1n per surface to be treated. It is sent into the ozone generator 42, where it is converted into oxygen gas containing ozone, and the cooling device r! From t36, the gas/cleaning liquid is supplied to the semiconductor wafer 32 in the processing chamber 31 from the gas/cleaning liquid outlet 35 which has been cooled to, for example, about 25° C. by cooling water or the like that is circulated in the cooling pipe 36a.

The heater 38 is controlled by the temperature control device 37, e.g.
It is controlled at a temperature of about 'C and contains ozone flowing out from the gas/cleaning liquid outlet 35'#! The exhaust device 49 heats the i-cumulative gas until the gas pressure in the processing chamber 31 is, for example, 700.
Evacuation is performed so that the pressure is in the range of ~200 Torr.

At this time, the oxygen gas containing ozone flowing out from the diffusion plate 34 of the gas/cleaning liquid outlet 35 is heated by the heater 38, and the ozone in the gas is rapidly decomposed and a large amount of oxygen atomic radicals are generated. This oxygen atom radical is
A gas flow from the center of the semiconductor wafer 32 to the periphery formed between the cleaning liquid outflow portion 35 and the semiconductor wafer 32 is supplied to the surface of the semiconductor wafer 32 to remove organic substances attached to the surface of the semiconductor wafer 32. The organic matter is decomposed into carbon dioxide, carbon oxide, and water and removed.

Note that the lifespan of ozone generated by the ozone generator 42 is
As mentioned above, since it depends on the temperature, the temperature of the heater 38 is preferably heated to about 150°C to 500°C, and the temperature of the opening of the gas/cleaning liquid outlet 35 is preferably about 25°C or less. .

The dry cleaning using oxygen gas containing ozone as described above is performed for about 30 seconds, for example, and then wet cleaning using a cleaning liquid is performed.

In wet cleaning using a cleaning liquid, the three gas/cleaning liquid switching valves are opened to the cleaning liquid flow rate regulators 43a and 43b, and the H supplied from the cleaning liquid supply sources 44a and 44b is
2 SO4, H202, H2O, HCi, HF, NH
A cleaning liquid such as 40H or ozone water is supplied to the cleaning liquid flow rate regulator 43.
The flow rate is adjusted by a and 43b, and the gas/chemical liquid outflow part 35
This is carried out by ejecting one or more types of liquid from the liquid toward the semiconductor wafer 32 . Further, drying may be performed by heating with a heater 38, rotating the semiconductor wafer 32, or applying nitrogen gas, etc. At this time, the moisture evaporated from the substrate to be processed is passed through a gas-liquid separator 47. , is exhausted by an exhaust device 49.

In the cleaning apparatus of this embodiment described above, the ozone-containing gas is first flowed out toward the substrate from the gas/cleaning liquid outlet 35 to remove deposits made of ￥Ta. Since the cleaning liquid is ejected from the cleaning liquid outlet 35 to remove inorganic deposits by wet cleaning, both organic and inorganic deposits can be removed in a short time, and cleaning can be performed at low cost and with a small amount of waste liquid. be able to.

FIG. 14 shows a cleaning device in the third embodiment method. In the apparatus shown in the figure, a processing chamber 31a is used for dry cleaning and a processing chamber 3 is used for wet cleaning.
1b and are connected by a transfer system 50 to transfer the semiconductor wafer 32.
The semiconductor wafer 32 may be dry cleaned in the processing chamber 31b, and then the semiconductor wafer 32 is transferred to the processing chamber 31b by the transport system 50, and the wet cleaning is carried out in the processing chamber 31b. A gas flow controller 52 controls the flow rate of an inert gas such as nitrogen supplied from a gas supply source 51 and blows it out toward the semiconductor wafer 32 for drying. 43 are arranged in large numbers. In this figure, the same parts as those of the cleaning device shown in FIG. 11 are given the same reference numerals.

Note that the diffusion plate 34 may be a diffusion plate 60 having a plurality of concentric slits 60a as shown in FIG. A diffusion plate 61 made of a sintered body of metal or ceramic, etc., allows the gas to flow out, and a diffusion plate 62, which allows the gas to flow out from a plurality of concentrically divided regions 62a arranged with a large number of small holes 62b, as shown in FIG. etc.

Further, the ozone-containing gas is not limited to oxygen, but may also be used by adding ozone to a gas that does not react with ozone, especially an inert gas such as N2, A', Ne, etc.

[Effects of the Invention] As described above, in the substrate cleaning method of the present invention, both organic deposits and inorganic deposits can be cleaned and removed in a short time, reducing cleaning costs compared to the conventional method. The amount of waste liquid can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a cleaning device for explaining one embodiment of the method of the present invention, FIG. 2 is a bottom view showing the main parts of FIG. 1, and FIG.
The figure is a graph showing an example of flow rate control of gas and cleaning liquid.
The figure is a graph showing the relationship between the half-life of ozone and temperature, Figures 5 to 10 are bottom views showing modifications of Figure 2, and Figure 11 is a cleaning device for explaining the method of the second embodiment. Configuration diagram,
Fig. 12 is a bottom view showing the main parts of Fig. 11, Fig. 13 is a bottom view showing the main parts of Fig. 11, and Fig. 14 is a configuration diagram of a cleaning device for explaining the third embodiment method. , Figure 15-1
FIG. 7 is a bottom view showing a modification of FIG. 12. 2...Semiconductor wafer, 4...2 fluid nozzle, 10...Ozone generator, lla, llb
...Cleaning liquid supply source. Applicant Tokyo Electron Co., Ltd. Agent Patent Attorney Satoshi Suyama - Figure 2 Ebisu Joginya (Second) Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Box Figure 9 Figure ℃ Figure 11 Figure 12/M7 Figure 15 Figure 16 Figure 17

Claims (4)

[Claims] (1) A method for cleaning a substrate, which comprises jetting a reactive gas containing oxygen atom radicals and a cleaning liquid toward the surface of the substrate to remove deposits on the surface of the substrate. (2) The reaction gas containing oxygen atomic radicals and the cleaning liquid are ejected simultaneously toward the substrate surface, and the gas-liquid multiphase flow of the reaction gas containing oxygen atomic radicals and the cleaning liquid removes deposits on the substrate surface. 2. The method of cleaning a substrate according to claim 1, further comprising removing the substrate. (3) The substrate cleaning method according to claim 2, characterized in that the temperature of the gas-liquid multiphase flow is controlled together with the gas-liquid flow rate ratio in the gas-liquid multiphase flow. (4) The method for cleaning a substrate according to any one of claims 1 to 3, wherein the reactive gas containing oxygen atom radicals is generated using ozone as a raw material.