JPH0483340A - Cleaning treatment of substrate - Google Patents

Abstract

PURPOSE:To satisfactorily conduct removing remaining surface deposits by decomposing and removing organic matter of a substrate surface through at least any of ozone supply, ultraviolet-light irradiation or plasma irradiation and by supplying the substrate surface with the vapor of a surface treating liquid containing hydrogen fluoride to etch a silicon oxide film and to clean the substrate surface. CONSTITUTION:In a pre-washing chamber 1, a substrate surface is supplied with ozone O3 and ultraviolet rays are uniformly applied to the substrate surface while the substrate W is rotated. The ozone O3 is decomposed into activated oxygen atoms O to oxidize organic matter of the surface of the substrate W by the oxygen atom O to separate the remove them from the substrate W. After the lapse of the necessary time, the application of ultraviolet rays is stopped and an inert gas is supplied to an ozone nozzle 13 via supply pipe 17 and introduction pipe 13b to purge remaining ozone and gases outward of the chamber via an exhaust pipe. Then, the substrate surface is supplied with the vapor of a surface-treating liquid containing hydrogen fluoride to etch a silicon oxide film to convert inorganics into fluorides. After that, the surface of the substrate W is supplied with pure water by injection pure water for the purpose of removing inorganics and organic matter by cleaning.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention applies to substrates such as semiconductor wafers, such as natural oxide films in contact holes, natural oxide films before diffusion, etc.
The present invention relates to a substrate cleaning method for cleaning the surface of a substrate such as a silicide film.

<Prior Art> As a conventional substrate cleaning method, for example, the method described in Japanese Patent Application Publication No. 1982-502930 is known.

According to this conventional example, a dry inert diluent gas such as dry nitrogen gas is supplied to the reaction chamber to pre-clean the substrate.
Anhydrous hydrogen halide gas and moisture are then supplied while flowing a dry inert diluent gas to substantially etch the film from the substrate, and even after the supply of anhydrous hydrogen halide gas and moisture is stopped. Post-cleaning of the substrate is performed by flowing a dry inert diluent gas.

<Problems to be Solved by the Invention> However, in the case of the above-mentioned conventional example, after the surface of the substrate has been treated by supplying anhydrous hydrogen halide gas and moisture, organic substances are formed on the surface of the substrate as a core. 0.2
Microparticles of 0 to 0.23 μm are generated,
In addition, near the boundary between the silicon oxide film and bare silicon and in the area after etching the silicon oxide film with a thickness of 200 Å or more, cloudy surface deposits, which are aggregates of microdroplets containing a large amount of hydrofluoric acid, are observed. However, even if post-cleaning with a dry inert diluent gas is performed, the above-mentioned surface deposits cannot be removed.

The present invention was made in view of the above circumstances, and it effectively removes organic substances prior to treatment with hydrogen fluoride, suppresses the generation of surface deposits accompanying treatment with hydrogen fluoride, and The purpose is to enable removal of remaining surface deposits in a good manner.

<Means for solving the problem> The substrate cleaning method of the invention according to claim (1) comprises:
In order to achieve this purpose, a first step of decomposing and removing organic substances on the substrate surface by at least one of ozone supply, ultraviolet irradiation, or plasma irradiation, and a surface treatment containing hydrogen fluoride after the first step. The method includes a second step of etching the silicon oxide film by supplying liquid vapor to the substrate surface, and a third step of cleaning the substrate surface by supplying pure water to the substrate surface after the second step. It is a feature.

Further, the substrate cleaning method of the invention according to claim (2) uses a surface treatment liquid containing hydrogen fluoride according to claim (1) that has an azeotropic composition concentration. It is characterized by

According to the configuration of the substrate cleaning method of the invention according to claim (1), in the first step, at least one of ozone supply, ultraviolet ray irradiation, and plasma irradiation is applied to the substrate surface. organic matter (C, H, O□
) is decomposed and removed into carbon dioxide (CO□) and water (H2O).

In the next second step, the silicon oxide film is etched with one atmosphere of a surface treatment solution containing hydrogen fluoride, converting inorganic substances such as metal particles on the surface of the silicon oxide film and in the film into fluoride, and The organic substances remaining on the surface of the film and the substances in the film are converted into substances that can be removed by washing with water.Next, in the third step, pure water is supplied to the surface of the substrate to wash it and convert it into fluoride. It is possible to wash and remove inorganic substances and organic substances that have been converted to substances that can be washed with water.

Further, according to the structure of the substrate cleaning method of the invention according to claim (2), a surface treatment liquid containing hydrogen fluoride having an azeotropic composition concentration is used, and the concentration at the substrate surface is Surface treatment can be performed uniformly without causing any change.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic diagram of a substrate cleaning apparatus for carrying out a substrate cleaning method.

In this figure, 1 is a pre-cleaning treatment chamber, 2 is a surface treatment chamber,
3 designates post-cleaning processing chambers, and first to fourth substrate transport mechanisms 4a, 4b, 4c.

4d, transport to pre-cleaning chamber 1 → pre-cleaning chamber 1
Unloading from and loading into surface treatment chamber 2 → Surface treatment chamber 2
The first step is to decompose and remove organic substances on the surface of the substrate W by supplying ozone and irradiating ultraviolet rays. A second step of etching the silicon oxide film by supplying the straw of the surface treatment liquid to the surface of the substrate W, and a third step of cleaning the substrate surface by supplying pure water to the surface of the substrate W are sequentially performed. , is configured to remove organic matter and inorganic matter from the surface of the substrate W.

the first to fourth substrate transport mechanisms 4a, 4b;

4c and 4d each have the same structure, and as shown in the perspective view of FIG.
a second arm 7 rotatably attached to the free end of the arm;
Consisting of a transmission mechanism 8 that transmits the rotational motion of the first arm 6 to rotate the second arm 7, a vacuum chafing mechanism 9 formed at the free end of the second arm 7, and that sucks and holds the placed substrate W. has been done.

The pre-cleaning treatment chamber 1 in which the first process is carried out is
A spin chuck 11 for holding a substrate W and an ozone nozzle 13 made of quartz and having a built-in ultraviolet lamp 12 are installed inside the O.

The spin chuck 11 is configured to be driven and rotated around a vertical axis by a motor Ml. Ozone nozzle 1
A large number of ozone diffusion holes 13a are formed in the bottom plate of No. 3 so as to be uniformly distributed at predetermined intervals in the horizontal direction.

In order to increase the efficiency of decomposing and removing organic matter, it is preferable to make the distance between the substrate W on the spin chuck 11 and the ultraviolet lamp 12 as short as possible. Note that the ultraviolet lamp 12 may be suspended outside and below the ozone nozzle 13.

Although not shown, a first
A loading port for the substrate W is formed at a location corresponding to the second substrate transporting mechanism 4a, and a loading port for the substrate W is formed at a location corresponding to the second substrate transporting mechanism 4b. Each is provided with a shutter that opens and closes by sliding vertically using a drive mechanism.

Ozone supply pipe 16 of ozone generator 15 connected to oxygen cylinder 14 and supply pipe 1 of inert gas for purging (N2)
7 are connected to the inlet pipe 13b of the ozone nozzle 13 via valves 18 and 19, respectively.

Although not shown, an exhaust chamber for gases such as CO2 and HzO generated during decomposition and removal of ozone and organic matter is formed in the bottom plate of the housing 10, and a blower is connected to the exhaust chamber via an exhaust pipe. .

In the substrate processing chamber 2a in the surface processing chamber 2 where the second process is carried out, as shown in the schematic vertical cross-sectional view of FIG. A storage tank 20 that stores a surface treatment liquid in a pseudo-azeotropic state is connected via a steam supply pipe 21 .

A pipe 23 with a stirring pump 22 interposed therein is connected across the bottom wall and side wall of the storage tank 20 .

Further, a surface treatment liquid supply pipe 24 from another storage tank (not shown) that stores a surface treatment liquid in a pseudo-azeotropic state is connected to the storage tank 20, and the surface treatment liquid supply pipe 24 is connected to the surface treatment liquid supply pipe 24. When the on-off valve 25 is installed and the storage level of the surface treatment liquid is lower than the position detected by the liquid level gauge 26,
It is configured to open the on-off valve 25 to replenish as appropriate.

Inside the reservoir 120, a heater 27 that heats the surface treatment liquid, a cooling pipe 28 that cools the surface treatment liquid, and a temperature sensor 29 that measures the temperature of the stored surface treatment liquid are provided. The temperature sensor 29 is connected to a temperature control device 30, and a solenoid valve 31 interposed in the cooling pipe 28 and a heater 27 are connected to the temperature control device 30.

In the temperature control device 30, the temperature of the surface treatment liquid in the storage tank 20 is adjusted to a set temperature (for example, The heater 27 and the solenoid valve 31 are controlled so as to set the temperature to 30''C).

That is, when the temperature decreases due to replenishment of the surface treatment liquid to the storage tank 20, the heater 27 is energized and the storage tank 2 is heated.
Heat the surface treatment liquid in 0 and raise the temperature until it reaches the set temperature. Conversely, when the set temperature is exceeded, the t-magnetic valve 31 is opened and cooling water is allowed to flow through the cooling pipe 28 to lower the temperature.

With this temperature control, as will be described later, atmospheric pressure 7601
Under Hg, 39.4 wt% hydrogen fluoride HF and 6
A surface treatment liquid with an azeotropic concentration consisting of a mixed liquid with 0.6 wt % of pure water H and O can be maintained in an azeotropic state at an azeotropic temperature of 30°C.

A nitrogen gas supply pipe 34 for supplying carrier nitrogen gas Nz, which is equipped with a flow rate regulator 32 and a solenoid valve 33, is connected to the storage tank 20, and a nozzle 34a having a perforated plate at the tip thereof is connected. It is connected to distribute and equalize the pressure in the upper steam storage section 35 in the storage tank 20.

The vapor supply pipe 21 is connected to supply the vapor of the surface treatment liquid diluted with carrier nitrogen gas N2 from the vapor storage section 35 to the substrate processing chamber 2a.

A pressure sensor 36 is provided to measure the pressure of the atmospheric gas containing the vapor of the surface treatment liquid in the vapor storage section 35 of the storage tank 20, and this pressure sensor 36 is connected to a pressure control device 37, and the pressure control device 37 is nitrogen gas supply pipe 3
4 solenoid valve 33 is connected, and the solenoid valve 33 is controlled to open and close based on the pressure measured by the pressure sensor 36, and the nitrogen gas N
The atmospheric pressure of the steam storage section 35 in the storage tank 20 is maintained at atmospheric pressure of 760 mmHg by adjusting the supply amount of the steam storage section 35 in the storage tank 20.

The distal end portion of the nitrogen gas supply pipe 34, the grass storage section 35 of the storage tank 20, and the steam supply pipe 21 are covered with an outer pipe 38 made of a heat insulating material, and the upstream and downstream parts of the outer pipe 38 are connected to the pump 3.
They are connected via a bypass pipe 40 with a pipe 9 interposed therebetween, and hot water is stored inside, and a heater 41 is provided in the middle of the bypass pipe 40 .

With this configuration, hot water heated to a required temperature (for example, 50° C.) by the heater 41 is circulated, and the steam storage section 35
The temperature of the vapor of the surface treatment liquid, which is a mixed vapor of hydrogen fluoride gas and pure water vapor HF/H,O, which is flowed into the vapor supply pipe 21 from the above is maintained at a temperature exceeding the dew point.

That is, the saturated vapor pressure of the surface treatment liquid vapor and each component of the surface treatment liquid in the atmosphere is made to be equal to or higher than the respective partial pressures, and the vapor of the surface treatment liquid or each of its components is prevented from condensing or liquefying. There is.

In addition, the tea temperature in the atmosphere is 30"C1 pressure 160mmH
In the state of g, the total partial pressure of hydrogen fluoride gas and pure water vapor (P11F+pH2°) is 18 mmHg, and the partial pressure of nitrogen gas N2 is 142 mmHg.

FIG. 4 is a vapor pressure diagram of a liquid mixture of hydrogen fluoride HF and water H20. The horizontal axis shows the partial pressure PIIF of hydrogen fluoride HF, and the vertical axis shows the total pressure P, that is, hydrogen fluoride! (Partial pressure P of F
The total pressure of IIF and the partial pressure PH□0 of pure water vapor H20 (
P IIF + P 1120), and using temperature T as a parameter, partial pressure P
゜).

The plurality of diagonal lines are straight lines indicating each composition ratio (mole fraction) of hydrogen fluoride to the entire mixed liquid.

In this figure, under the conditions mentioned above, the pseudo azeotropic temperature is 30
If the temperature of the steam generated at °C is maintained above 30 °C, the mixed vapor of hydrogen fluoride gas and pure water vapor HF/H,O will not condense or liquefy.

On the other hand, the partial pressure of the mixed gas of hydrogen fluoride gas and pure water vapor is 1
8mmNg, the partial pressure of nitrogen gas is 742mdg, and the total pressure is
If the temperature of the steam consisting of 160 mraHg is lowered to below 30'C, the saturated vapor pressure of the mixed gas will become supersaturated because the partial pressure of the mixed gas will drop below 18 mrg, and the mixture of hydrogen fluoride gas and pure water vapor will become supersaturated. Steam liquefies.

Here, pseudo azeotrope will be explained.

FIG. 5 shows the partial pressure PHF of hydrogen fluoride HF and the partial pressure PM of water H20. The total pressure (PNP + pH□.) is 760
It shows the characteristics of composition ratio versus temperature when mllNg, the horizontal axis is the composition ratio (concentration) [%] of hydrogen fluoride HF, and the vertical axis is the temperature (
”C).

In FIG. 5, the liquidus line and gas phase line at 760adg of a mixed solution of hydrogen fluoride HF and water HtO are at a temperature of 111
．． Meet at 4°C. This is the azeotropic point, and the concentration of hydrogen fluoride HF at the azeotropic point is 37.73%.

If hydrogen fluoride I with a concentration of 37.73% is in the storage tank 20,
F and 100-37.73 = 62.27% pure water H2
The azeotropic condition is satisfied by storing a surface treatment liquid consisting of Then, the composition ratio of the vapor of the surface treatment liquid is the same as that of the surface treatment liquid HF: Hto = 37.73:
62.27, and even if the amount of surface treatment liquid decreases as vaporization progresses, its composition ratio is always maintained constant.

However, since the temperature of 111.4°C is relatively high, it is preferable to vaporize the surface treatment liquid at a lower temperature to increase safety. If you want to set the vaporization temperature to 30″C, for example,
From Figure 4, the pressure that satisfies the azeotropic condition (P MF + P
xzo ) is 18 mm#g, and the concentration of hydrofluoric acid HF is 39.4%. (P Hv + P M2O)
=1811111#g To make it the atmospheric gas pressure, it must be reduced, but that pressure reduction is no longer necessary, and the atmospheric pressure is reduced to 7.
Pseudoazeotropy is vaporization in an atmosphere of 6 cm 11 g.

That is, 39.4% hydrofluoric acid H is in the storage tank 20.
A surface treatment solution containing a mixture of F and 100-39.4=60.6% pure water H, O is supplied, and the temperature of the surface treatment solution is increased to 3.
The temperature is controlled by a heater 27, a cooling pipe 28, a temperature sensor 29, and a temperature control device 30 so as to maintain the temperature at 0°C.

Then, the atmospheric gas in the storage tank 20, that is,
Partial pressure pHy of hydrogen fluoride gas, pure water thin air, and nitrogen gas,
The total atmospheric pressure of PH2O and Ps□ is 76011
The surface treatment liquid is evaporated in a state of IffiHg. When the atmospheric gas pressure deviates from 760 mmHl, the pressure sensor 36, solenoid valve 33, and pressure control device 37
Adjust the pressure to maintain 0 mml (g).

That is, nitrogen gas N2 with a partial pressure of 760-18=142 mmHtl is supplied to the storage tank 20 via the nitrogen gas supply pipe 34.
The gas is supplied as an atmosphere gas and a carrier gas.

The composition ratio of the surface treatment liquid in this case is HF:H,0=3
It is 9.4760.6. On the other hand, since the composition ratio of the atmospheric gas is P□y=7.09m5+h from FIG. 4, HF:HxO:Nz=7.09:10.9
1: 742 (+a shoes 77g) = 5.21:
8.00:86.79 (%), which is different from the composition ratio of the surface treatment liquid.

However, what is important for the cleaning process of the substrate W is
Hydrogen fluoride gas H, not the composition ratio of the entire atmospheric gas
It is the composition ratio between F and pure water vapor Hz O. This composition ratio is HF:H,0=5.21:8.0O=39.4
760.6 (In addition, even in the case of expression as HF + H20 + Nz = 760, HF: H, O = 7.09: 10.91 = 39
．． 4 F 60.6 ), which matches the composition ratio in the surface treatment liquid. This is a pseudo azeotrope.

Therefore, the composition ratio of the vapor of the surface treatment liquid supplied to the substrate processing chamber 2a (FIG. 1) is maintained constant. Moreover, it is possible to generate vapor from the surface treatment liquid at atmospheric pressure and at a temperature as low as 30° C., which increases safety and eliminates the need for reduced pressure.

Furthermore, since the surface treatment liquid is evaporated at a temperature below the boiling point of the surface treatment liquid, the surface treatment liquid is evaporated from the liquid surface without being boiled, so that no aerosol is generated.

A mechanical chuck 42 that holds a substrate W and rotates horizontally is provided in the bottomed cylindrical substrate processing chamber 2a.

The chuck that holds the substrate W is not limited to a mechanical chuck, and may be a known vacuum suction chuck. Alternatively, the chuck may be equipped with a heating means for heating the substrate to a required temperature while vacuum suctioning it. An electric motor M2 is interlocked and connected to a rotating shaft 43 of the mechanical chuck 42, and is configured to drive and rotate the substrate W held by the mechanical chuck 42 around a vertical axis.

A cup-shaped lid 44 (
3) is composed of a tapered peripheral wall portion, a chamber 45 that is integrated in a watertight manner at the bottom of the tapered peripheral wall portion, and a top plate that is integrated in an upper portion in a watertight manner. Inside the lid body 44, a hot water supply tube 46 and a hot water discharge tube 47 for constantly retaining hot water at a constant temperature (for example, 50° C.) are provided and connected to the tapered peripheral wall portion. It is configured as a constant temperature hot water bath 4B that maintains the internal temperature at a constant temperature.

An aspirator 49 is provided inside the constant temperature hot water tank 48,
The surface of the substrate W is etched into the aspirator 49.
A steam supply pipe 21 that supplies vapor of a surface treatment liquid that is a mixture of hydrogen fluoride gas HF for cleaning, pure water vapor H, O, and nitrogen gas N2, and nitrogen gas N as a carrier gas.
A carrier gas supply tube 50 that supplies the carrier gas N2 and a steam supply tube 51 that supplies the vapor of the surface treatment liquid to the chamber 45 are connected, and the vapor of the surface treatment liquid is is suctioned, the vapor of the surface treatment liquid is diluted with carrier gas N2, and the diluted vapor of the surface treatment liquid is supplied to the chamber 45.

The reason why the steam supply pipe 21, aspirator 49, and steam supply tube 51 are inserted into the constant temperature bath 48 is to control the temperature of the steam of the surface treatment liquid to a temperature exceeding the dew point to prevent its liquefaction, that is, the generation of aerosol. It is.

The chamber 45 has a gas inlet in its peripheral wall that is inclined at an appropriate angle (for example, 30°) with respect to the radial direction, and a perforated plate 52 is provided at the lower opening. chamber 4
The vapor of the surface treatment liquid that has flowed into the chamber 5 from the inclined gas inlet becomes a vortex in the chamber 45, and due to its centrifugal action, the flow rate is high in the periphery and low in the center.

Therefore, when the mechanical chuck 42 is in a stopped state, the flow rate of the vapor of the surface treatment liquid from the small holes of the perforated plate 52 is limited to the surrounding area. This generates negative pressure on the center side and increases the outflow flow rate from the center side, equalizing the outflow flow rate from all the small holes of the porous plate 52, and causing the vapor of the surface treatment liquid to reach the surface of the substrate W. This allows for uniform supply.

The cup-shaped lid 44 is configured to be vertically movable together with the chamber 45, and when lowered, it comes into contact with a buffing ring on the upper edge of the substrate processing chamber 2a, thereby making the substrate processing chamber 2a airtight. A lifting air cylinder 53 serves as a mechanism for moving the lid body 44 up and down.
is provided.

The main processing section consisting of the substrate processing chamber 2a, the cup-shaped lid 44, etc. described above is housed inside the surface processing chamber 2, and has a double chamber structure. A substrate loading port 54a and a substrate loading port 54b are formed in the peripheral wall of the surface treatment chamber 2 at a location corresponding to the height of the mechanical chuck 42, and are opened and closed by a shank (not shown).

The first substrate transport mechanism 4b is provided outside the surface treatment chamber 2 at a position close to the loading port 54a, and
The third substrate transport mechanism 40 is located near the export port 54b.
is provided and the substrate processing chamber 2a is opened by lifting the lid 44, and the substrate W is carried into the surface processing chamber 2 through the loading port 54a while holding the substrate W by suction. transferred to the mechanical chuck 42,
Further, the substrate W is transferred from the mechanical chuck 42 to the unloading port 54.
b is configured to be carried out from the surface treatment chamber 2 to the outside.

Reference numeral 55 indicates an exhaust pipe of the substrate processing chamber 2a, and reference numeral 56 indicates an exhaust pipe of the surface processing chamber 2.

As shown in FIG. 1, the post-cleaning processing chamber 3 in which the third step is carried out includes a mechanical chuck 58 that holds the substrate W in a housing 57 and rotates horizontally. An electric motor M3 is interlocked and connected to a rotating shaft 59 of the mechanical chuck 58, and is configured to drive and rotate the substrate W held by the mechanical chuck 59 around a vertical axis.

A top plate portion of the housing 57 is provided with a pure water nozzle 60 that sprays and supplies pure water, and a nozzle 61 that sprays nitrogen N2 gas as an inert gas.

A cover 62 is provided to cover the periphery of the mechanical chuck 59 and prevent pure water from scattering.

With the above configuration, first, in the first step, while the substrate W is being rotated in the pre-cleaning processing chamber 1, ozone is applied to the surface of the substrate. In addition to supplying ultraviolet rays (UV: formerly tra-Vi),
olet rays) are uniformly irradiated onto the substrate surface.

Ozone O2 is decomposed into activated oxygen atoms O by the irradiated ultraviolet rays, and these oxygen atoms oxidize organic substances (C, HfO2) on the surface of the substrate W, converting them into CO□, H2O, etc., and removing the entire substrate W. Separate and remove. The generated Cot
, Hz O, etc. are discharged outside through the exhaust pipe.

In the oxidation reaction, ultraviolet rays and heat promote the production of activated oxygen atoms and promote the decomposition of organic matter.

In this practical example, since ozone is directly supplied to the surface of the substrate W from the beginning, the amount of ozone supplied is sufficient and the frequency of contact between the surface of the substrate W and ozone is high, increasing the rate of decomposition and removal of organic matter. It has the advantage of being fast.

Even after the supply of ozone is stopped, the irradiation of ultraviolet rays is continued for a required period of time. Thereby, organic matter remaining at the interface on the surface of the substrate W can be continuously decomposed and removed.

After the required time has elapsed, the ultraviolet lamp 12 is turned off to stop the ultraviolet irradiation, and then the valve 19 is opened and the supply pipe 17. A required flow rate of inert gas is supplied to the ozone nozzle 13 through the introduction pipe 13b, and ozone remaining in the pre-cleaning chamber 1 and gases such as CO□, H, O, etc. generated in the pre-cleaning chamber 1 are removed. Purge outside through the exhaust pipe.

In the present invention, the substrate W may not be rotated, or the organic substance may be decomposed and removed by plasma.

Next, the substrate W is transferred from the pre-cleaning chamber 1 to the surface treatment chamber 2 by the second substrate transport mechanism 4b, and the second process begins.

In this second step, while rotating the substrate W, vapor of a surface treatment liquid containing hydrogen fluoride is supplied to the surface of the substrate to etch the silicon oxide film and convert inorganic substances into fluoride.

Thereafter, the substrate W is transferred from the surface treatment chamber 2 to the post-cleaning chamber 3 by the third substrate transport mechanism 40, and the process proceeds to the third process.

In this third process, while rotating the substrate W,
By spraying and supplying pure water to the surface of the substrate W, inorganic substances and organic substances such as metal particles remaining on the surface of the substrate W are washed and removed.

In this third step, if necessary, an ultrasonic vibrator may be attached to the nozzle 60, and ultrasonic waves having a frequency of 800 kH2 or more may be added to the pure water to improve the cleaning efficiency.

After that, the substrate W is rotated at high speed while supplying an inert gas with the supply of pure water stopped, and a large centrifugal force is exerted on the substrate W to blow off the pure water etc. adhering to the surface of the substrate W and liquidize it. Cut and dry.

In this third step, it is preferable to accelerate the drying speed by irradiating an infrared ray lamp for drying, especially infrared rays in the wavelength range of 1200 nm, which is easily absorbed by silicon wafers, or by reducing the pressure in the post-cleaning chamber 3.

In this example, the second process was carried out in the surface treatment chamber 2, and the third process was carried out in the post-cleaning chamber 3, respectively, but the second process and the third process were carried out in the same process chamber. It may also be processed.

1 piece and then as a substrate, the diameter is 150am+ and the thickness is 600mm
P-type silicon wafers (manufactured by Semicon Nagano ■) containing boron (B) as an impurity were used to measure particles. Regarding the measurement of particles, the size is 0.20 μm or more and less than 0423 μm (CHI in the table mentioned later), 0.23 or more and less than 0.25 μm (
The number of particles was measured by dividing into CH2 in the table described below), 0.25 or more and less than 0.28 μm (CH3 in the table described later), and 0.28 μm or more (CH4 in the table described later).

First, the natural oxide film on a silicon wafer, which has been cleaned with a mixture of ammonia, hydrogen peroxide, and water and dried with IPA paper (isopropyl alcohol vapor), is etched with hydrofluoric acid vapor. As an experimental example, particles attached to the silicon wafer were measured (indicated by 1-a in the table).

This silicon wafer was simply washed with pure water, and particles on the surface of the substrate after spin drying were measured (indicated by ib in the table).

This cleaning process uses a dry task chamber (spin processor), supplies pure water from a capillary nozzle for 60 seconds while rotating the silicon wafer at 50 Orpm, and then rotates the silicon wafer at 300 Orpm for 4
Spin dry for 5 seconds.

As a result, for example, if we consider only particles with a size of 0.20 μm or more and less than 0.23 μm (CHI), we can see that 99.7% of particles can be removed. It was clear that it belonged to

In order to confirm reproducibility, the same experiment was conducted twice as a second and third experimental example. However, regarding the measurement of particles, after etching with hydrofluoric acid vapor (see 2 in the table)
-a, 3-a) and after washing with pure water (2-a in the table).
b, 3-b).

In the second and third experimental examples, almost the same results as in the first experimental example were obtained.

Next, the substrate was cleaned with a mixture of ammonia, hydrogen peroxide, and water as a final cleaning, and then a 150-diameter substrate was treated with IPA paper (isopropyl alcohol vapor) in the same manner as in the first experimental example. An N-type silicon wafer (manufactured by Semicon Nagano ■) having a thickness of 600 μm and containing phosphorus (P) as an impurity was used to measure the initial particles of this silicon wafer (this will be referred to as 4th Experimental Example 4).

Next, using the silicon wafer of the fourth experimental example, a fifth experiment was conducted.
As the seventh to seventh experimental examples, after etching with hydrofluoric acid vapor (indicated by 5-a, 6-a, and 7-a in the table),
After washing with pure water (indicated by 5b, 6-b, and 7-b in the table)
Particles were measured in each case.

In these fifth to seventh experimental examples, there is a similar tendency as in the second and third experimental examples, and no difference is observed between the P type and the N type.

Next, as a final cleaning, a P-type 6-inch silicon wafer (manufactured by Osaka Titanium ■) was cleaned with a mixture of ammonia, hydrogen peroxide, and water, and then removed from pure water and dried. When the treatment with hydrogen acid vapor was performed, the results of the 8th to 19th experimental examples (indicated by 8 to 19 in the table) were obtained.

From these results, it was found that after treatment with hydrofluoric acid vapor, the number of particles was extremely reduced when the particles were pulled up and dried with pure water compared to when dried with IPA paper (alcohol vapor). It is speculated that organic matter may be adsorbed onto the surface of the substrate during drying.

Therefore, as the 20th experimental example, we measured the initial particles (indicated by 20-a in the table) of the above-mentioned P-type 6-inch silicon wafer (manufactured by Osaka Titanium), and then
Measure particles after exposing to A paper (2 in the table)
(denoted as 0-b).

From this result, it is clear that the number of particles increases due to drying of IPA Heber, and it was found that drying of IPA paper is inappropriate.

Next, the silicon wafer exposed to the IPA paper of the 20th experimental example was treated with hydrofluoric acid vapor, and particles were measured (indicated by 21 in the table) as a 21st experimental example.

As a result, it was found that there were many microparticles of 0.20 μm or more and less than 0.23 μm, and that they were locally adsorbed, which was thought to be due to local adsorption of the IPA paper.

Furthermore, as a 22nd experimental example, the silicon wafer of the 21st experimental example was washed with pure water and then dried, and its particles were measured (indicated by 22 in the table).

Localization of minute particles of 0.20 μm or more and less than 0.23 μm disappeared.

Next, in order to check reproducibility, as the 23rd and 24th experimental examples, particles were measured after treating the above-mentioned P-type 6-inch silicon wafer (manufactured by Osaka Titanium ■) with hydrofluoric acid vapor (see Table 2). 23-a and 24-a), and then the particles were measured after washing with pure water (shown as 23-b and 24-b in the table).

Furthermore, as the 25th and 26th experimental examples, the initial particles of silicon wafers were measured (25-a and 2
6-a), and measured particles after treatment with hydrofluoric acid vapor (25-b, 26- in the table).
b)).

Table-1 (Hereinafter, blank space) Table-2 Table-3 In addition, a thermal oxide film with a thickness of 2,000 mm and a diameter of 50 mm was formed on the surface of a P-type 4-inch silicon wafer, and the silicon wafer was coated with hydrogen fluoride. When the surface was observed after treatment with acid vapor, cloudy deposits were observed on the thermal oxide film and on the bare silicon surface surrounding the thermal oxide film. This cloudy surface deposit had a pungent odor and was detected when a hydrogen fluoride detector was brought close to it, and it turned out to be condensed particles containing hydrofluoric acid, which could be cleaned with pure water. Ta.

From the above experimental results, it is clear that the surface deposits generated on the surface of the substrate after treatment with hydrofluoric acid vapor include surface deposits generated from organic contamination as a core, and silicon oxide droplets that are hydrofluoric acid droplets. Although there are cloudy surface deposits caused by the film, it is necessary to avoid drying by dissolving Il such as IPA base 7 (-), and to use at least one of ozone supply, ultraviolet irradiation, or plasma irradiation as pre-cleaning. By working together with the complete removal of organic matter, the occurrence of surface deposits as described above can be prevented, and furthermore, by performing post-cleaning with pure water, organic matter can be removed even better. It was also clear that hydrofluoric acid droplets could be washed away.

In the apparatus of the above embodiment, a single-wafer type apparatus is shown in which the substrates W are processed one by one.However, in implementing the method of the present invention, a so-called process is performed in which a large number of substrates are accommodated in a substrate boat and processed.
A batch type device may also be used.

<Effects of the Invention> According to the substrate cleaning method of the invention according to claim (1), in the first step, the organic contaminant layer adsorbed on the substrate surface is decomposed and removed, so that the organic matter is not removed as a core. In addition, in the second process, inorganic substances such as metal particles on the surface of the silicon oxide film and in the film can be prevented from occurring. At the same time, the surface of the silicon oxide film and the grains in the film are converted into substances that can be removed by washing with water, and the inorganic and organic substances converted into fluorides are washed by supplying pure water in the third step. Because of the removal, it is possible to suppress the generation of surface deposits due to treatment with hydrofluoric acid, and also to successfully remove remaining surface deposits, thereby improving reproducibility.

Further, according to the substrate cleaning method of the invention according to claim (2), since the surface is treated with a surface treatment liquid containing hydrogen fluoride at an azeotropic composition concentration, the concentration due to liquefaction on the substrate surface is There is no change, surface treatment can be performed uniformly, and a much cleaner substrate can now be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a substrate cleaning apparatus used in the substrate cleaning method of the present invention, FIG. 2 is a perspective view showing a substrate transport mechanism, and FIG. 3 is a surface treatment using hydrogen fluoride vapor. A schematic longitudinal sectional view showing the configuration for carrying out the treatment, Figure 4 is a vapor pressure diagram of a mixed liquid of hydrofluoric acid vapor and water, and Figure 5 is a diagram of the vapor pressure of hydrofluoric acid at atmospheric pressure. It is a characteristic curve diagram of composition versus temperature. 1... Pre-cleaning chamber 2... Surface treatment chamber 3... Post-cleaning chamber W... Substrate applicant Dainippon Screen Mfg. Co., Ltd. Agent Patent attorney Tsutomu Sugitani - HF book ratio ['/,]

Claims (2)

[Claims] (1) A first step of decomposing and removing organic substances on the substrate surface by at least one of ozone supply, ultraviolet irradiation, or plasma irradiation; After the first step, vapor of a surface treatment liquid containing hydrogen fluoride is applied to the substrate surface. A substrate cleaning process comprising: a second step of supplying pure water to etch the silicon oxide film; and a third step of cleaning the substrate surface by supplying pure water to the substrate surface after the second step. Method. (2) A method for cleaning a substrate, wherein the surface treatment liquid containing hydrogen fluoride according to claim (1) has an azeotropic composition concentration.