JP3016301B2 - Cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method and, more particularly, to a method for cleaning a substrate having organic dirt.

[0002]

Manufacture of LSI is carried out over a period of about 3 00 process the three months before and after the date and time. During such a long construction period, the semi-finished product is subjected to various kinds of contamination due to transportation or leaving between processes or the intervention of an operator. By minimizing these contaminations, the manufacturing yield of the device is improved, and the reliability and reproducibility of the process can be significantly improved. Therefore, it has been more important than before to perform cleaning before each step of the process to remove surface contaminants. For example, 0.8 μm for a 4 Mbit DRAM design, and 0.1 μm for a 16 Mbit DRAM.
A wiring technology of 5 μm is required, and in order to enable such fine processing, contamination particles, atomic and molecular contaminations of about 0.1 μm each (chemical contamination).
Control is required. Therefore, conventionally, to achieve the original purpose, contaminant particles and atomic contaminants are removed by wet cleaning with a solvent typified by RCA cleaning and IPA vapor phase drying, or ultraviolet light irradiation and ozone In some cases, molecular contamination was removed by dry cleaning typified by combined cleaning.

However, conventional wet cleaning and dry cleaning methods and apparatuses are not sufficient to completely remove contaminant particles of 0.1 μm or less, and are not satisfactory in removing molecular contaminants composed of organic substances. It is difficult to say, and as a result, there is a problem that a sufficient device manufacturing yield cannot be obtained. The causes for this include the following. For wet cleaning, recontamination by particles once separated from the surface increases as
m or less. Although the addition of a surfactant to the cleaning solution is effective in reducing these particles, the surfactant eventually remains on the surface of the substrate to be cleaned, and this causes molecular contamination of new organic substances. It does not become. In the case of dry cleaning using ultraviolet light irradiation and ozone in combination, although there is a certain degree of cleaning effect on organic substances, it has little effect on the contamination of inorganic substances, and removal of carbon oxides generated by oxidation of organic substances. Has limitations. The conditions imposed on the washing in the DRAM of 64M bits later developed, are considered to gradually become more stringent, current, it has been desired to develop excellent cleaning method and cleaning apparatus. Regarding the conventional technique (washing), for example, see “Kojima, 25th Applied Spectrometry, pp. 191 to 196 (199)
0) "," Chemical Review, No. 44, Surface Modification, edited by The Chemical Society of Japan, pp. 147-155 (1984) "," Tsuchibashi, Journal of the Japan Society of Precision Engineering, 54, 10, pp. 1840-1844 (198).
8) "," Ultraviolet Utilization Technology in Catalog of Sen Engineering Co., Ltd. "and the like.

[0004]

As described above, it is difficult to completely remove contaminant particles of 0.1 μm or less, or completely remove inorganic contaminants and molecular contaminants composed of organic substances by the conventional cleaning method. As a result, there is a problem that a sufficient device manufacturing yield cannot be provided.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. In particular, the present invention is intended to remove contaminant particles of 0.1 μm or less, as well as molecular contaminants including organic substances and carbon acids.
It is an object of the present invention to provide an excellent cleaning method capable of completely removing contamination made of a compound .

[0006]

The cleaning method according to the present invention comprises:
The object to be cleaned is obliquely immersed in a liquid in which ozone is dissolved, and the surface of the immersed object to be cleaned is irradiated with ultraviolet light for cleaning . Further, in another cleaning method of the present invention, an object to be cleaned is immersed obliquely in a liquid to which ozone gas has been bubbled, and the surface of the immersed object to be cleaned is irradiated with ultraviolet light for cleaning. Further, in the above-mentioned cleaning method,
The cleaning is performed at a pressure higher than the atmospheric pressure, or ultraviolet light is applied obliquely to the surface of the object to be cleaned.

[0007]

In the present invention, since the surface of the object to be cleaned is covered with an organic solvent in which ozone is dissolved or bubbled ozone gas (the surface of the bubbled ozone gas has a thin liquid layer), it is wetted by ozone molecules and liquid. It is in the state where it was. When the surface of the object to be cleaned in such a state is irradiated with ultraviolet light, the ozone molecules absorb the ultraviolet light on the surface of the object to be cleaned and generate active oxygen atoms at the same time as photodecomposition occurs. In addition, molecular contamination of organic substances on the surface of the object to be cleaned absorbs ultraviolet light and is activated. In such an environment, some of the active oxygen atoms immediately react with the molecular contamination of activated organic substances on the surface of the object to be cleaned to form oxides. Most of the generated oxide immediately dissolves in the liquid on the surface of the object to be cleaned and then diffuses throughout the solution. Also, some of the remaining active oxygen atoms immediately react with water molecules to generate hydroxyl radicals (.OH), which react with inorganic contamination on the surface of the object to be cleaned to form hydroxides. Most of the generated hydroxide immediately dissolves in the liquid on the surface of the object to be cleaned, and then diffuses throughout the solution. As a result, organic contaminants such as molecular contaminants and inorganic contaminants are completely removed from the surface of the object to be cleaned. Further, as described above, in the present invention, both molecular contaminants and inorganic contaminants, which are organic substances, are simultaneously oxidized or hydrated and dissolved and diffused in a solution. It is also effective in decomposing and removing fine particles. Therefore, it is effective also in removing fine particles of 0.1 μm or less, which has conventionally been difficult to remove, and the removing effect is more effective as the finer particles are advanced. The resulting wash
The effect is large on the concentration of oxygen atoms generated on the surface of the object to be cleaned.
Is high, the molecular concentration of ozone is high.
A higher cleaning effect can be obtained. Ozone gas in organic solvents
Water has a higher solubility than other solvents such as water.
Cleaning by using an organic solvent
The effect increases. Among them, alcohol-based solvents are available
It is practical with little impact on the environment. Ozo
By immersing the object to be cleaned in the solution
Therefore, the affinity between the object to be cleaned and the ozone solution is improved. Special
When the solution is supplied from below and overflows
The liquid flows along the surface of the object to be cleaned without standing
Familiar degree is better, contaminants of better discharge of the
This improves the cleaning effect. Liquid without dissolving ozone gas
Small bubbles in the liquid by bubbling through the body
Ultrasonic waves generated when foaming enhances the cleaning effect. Ma
Also, by immersing the object to be cleaned obliquely,
Ozone bubbles are not accumulated on the surface to be cleaned.
Contact, and rises along the surface to be cleaned.
The result is improved. Bubbling ozone gas into it
As a liquid, water is safe, harmless and use water
Thereby, workability is improved. Pressurizing above atmospheric pressure
In other words, by increasing the pressure in the cleaning tank,
Ozone molecular concentration and ozone in liquid containing ozone gas
Since the molecular concentration of zon gas can be increased, the cleaning effect
The result is better. UV light is oblique to the surface of the object to be cleaned
Irradiation from the
Can be used even if components are mounted,
Ultraviolet light can be applied to the entire surface including the uneven side wall surface. order
Next, supply a new organic solvent that dissolves ozone.
Or supply liquid for bubbling ozone gas and update
By doing so, the liquid in which ozone is dissolved
Liquid or ozone gas with a clean and stable ozone concentration
And the good cleaning effect can be maintained.

[0008]

[Embodiment 1] FIG. 1 is a configuration diagram of a cleaning apparatus according to Embodiment 1 of the present invention. In the drawing, reference numeral 1 denotes a cleaning tank, which is mounted in the cleaning tank 1 so that the surface of the object 2 to be cleaned is irradiated with ultraviolet light (an incident angle of about 90 deg with respect to the surface to be cleaned ).
A low-pressure mercury lamp 3 (in this case, a UVL-40 low-pressure mercury lamp manufactured by Sun Engineering and power consumption of 40 W), which is an ultraviolet light source, and a liquid 6 in which ozone is used for cleaning, which is mounted so as to be irradiated at an angle. Is stored. The liquid 6 in which ozone is dissolved is fed into the ozone dissolving device 9 by the ozone gas 5 produced in the ozone gas generator 8 (in this case, using a silent discharge type ozone gas generator) and the liquid 4 in the liquid storage tank 7. And dissolved in the liquid. The liquid 4 may be basically any substance as long as it can dissolve ozone.
Reference numeral 10 denotes an insertion pump for feeding the liquid 6 in which ozone is dissolved into the cleaning tank 1. In this case, the flow rate of the liquid 6 was set to 10 cm / min with respect to the surface of the object 2 to be cleaned. 12 is waste liquid 1 which overflowed after washing
This is a waste liquid tank for storing 1. The waste liquid 11 is discharged through the outlet 13.

As shown in FIG. 1, an object 2 to be cleaned is immersed in a liquid in which ozone is dissolved in a cleaning tank 1. In addition,
Since the liquid 6 in which ozone is dissolved is sequentially supplied through the insertion pump 10, the liquid 6 flows in the cleaning tank 1 at a constant speed.
Then, the liquid 6 in which the ozone overflowing from the cleaning tank 1 is dissolved
Are sequentially sent to a waste liquid tank 12 as a waste liquid 11. By energizing the low-pressure mercury lamp 3 in such a state, the surface of the cleaning object 2 can be irradiated with ultraviolet light. At this time, on the surface of the object 2 to be cleaned, the ozone molecules absorb ultraviolet light to cause photolysis, and at the same time, generate active oxygen atoms. Also,
Organic contamination on the surface of the object 2 to be cleaned also absorbs ultraviolet light and is activated. In such an environment, some of the active oxygen atoms immediately react with the molecular contamination of the surface of the object 2 to be cleaned, which is composed of activated organic substances, to form oxides. Most of the generated oxide immediately dissolves in the ozone-dissolved liquid 6 on the surface of the cleaning object 2 and then diffuses throughout the ozone-dissolved liquid 6. Some of the remaining active oxygen atoms immediately react with water molecules present in the liquid 6 in which ozone is dissolved to generate hydroxyl radicals (.OH), which react with inorganic contamination on the surface of the cleaning object 2. To produce hydroxide. Most of the generated hydroxide is immediately dissolved in the ozone-dissolved liquid 6 on the surface of the cleaning object 2 and then diffused throughout. The liquid 6 in which ozone containing a large amount of such oxides and hydroxides overflows from the washing tank 1, and sequentially becomes a waste liquid tank 12 as a waste liquid 11.
Sent to Therefore, the liquid 6 in which ozone is dissolved in the cleaning tank 1 is always kept at a liquid having a clean and stable ozone concentration, and a good cleaning effect can be maintained. As a result,
Organic contaminants such as molecular contaminants and inorganic contaminants are completely removed from the surface of the object 2 to be cleaned.

Example i After opening a 6-inch silicon wafer manufactured by Shin-Etsu Silicon Co., Ltd.,
For the purpose of contamination of the wafer surface, the wafer was immersed in a 1.0% by weight aqueous solution of calcium oleate for 5 minutes, washed with water for 5 minutes, and then dried to form an object to be cleaned (wafer to be cleaned). The wafer to be cleaned was immersed in ultra-pure water as a liquid for dissolving ozone using the apparatus shown in FIG. Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning ability was evaluated by measuring contaminants with a total reflection X-ray fluorescence spectrometer and a fine particle measuring device. Table 1 shows the results.
Shown in

The cleaning performance was evaluated by total reflection fluorescent X made by Technos.
(C) at the center of the cleaning wafer by the line TREX
a) Atomic density measurement of atomic and nickel (Ni) atoms per unit area, and the entire surface of the cleaned wafer by the surface inspection device LS6000 manufactured by Hitachi Electronics Engineering (excluding the portion within 5 mm from the wafer edge due to the device performance) Of fine particles having a size of 0.1 μm or more was measured.

The measurement of the atomic densities of calcium and nickel per unit area by the total reflection X-ray fluorescence is described in, for example, Yoshiaki Matsushita et al., NIKKEI MICRODE.
VICES October issue, pp. 99-106 (1990). The measurement of fine particles by the surface inspection device is described in detail in the instruction manual for the surface inspection device LS6000 manufactured by Hitachi Electronics Engineering.

Example ii Using the apparatus shown in FIG. 1, the above-described wafer to be cleaned was immersed in isopropyl alcohol as a liquid for dissolving ozone for 10 minutes while irradiating the surface of the wafer with ultraviolet light for cleaning. Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 1 shows the results.

EXAMPLE iii The above-mentioned wafer to be cleaned was irradiated with ultraviolet light on the surface of the wafer to be cleaned by using the apparatus shown in FIG. 1 and using trifluorotrichloroethane as a liquid for dissolving ozone.
It was immersed for a minute and washed. Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 1 shows the results.

Embodiment 2 FIG. FIG. 2 is a configuration diagram of a cleaning apparatus according to Embodiment 2 of the present invention. In the apparatus of the first embodiment, ozone is supplied to the surface of the cleaning object 2 by the liquid 6 in which ozone is dissolved. However, in the apparatus of the second embodiment shown here, the ozone gas generator 8 is used instead of the liquid 6 in which ozone is dissolved. The liquid 14 containing the ozone gas made in the above is used. That is, the ozone gas generated in the ozone gas generator 8 is sent into the liquid and bubbled. In this case, the flow rate of the liquid 6 is 10 cm / m with respect to the surface of the object 2 to be cleaned.
In speed was adjusted. Liquid 1 containing ozone gas
4 is obtained by mixing the liquid 4 inserted into the cleaning tank 1 from the liquid storage tank 7 via the insertion pump 10 with the ozone gas 5 discharged in the form of small bubbles from the porous ozone gas discharge port 15. . At this time, the concentration of the ozone gas 5 is adjusted by the flow valve 16. In this study, a constant supply of 500 cc / min was performed. At this time, the object to be cleaned 2
The surface to be cleaned was set at an angle of 45 deg with respect to the direction in which the gravitational acceleration works (the direction in which the ozone gas flows naturally) so that the ozone gas 5 comes into contact directly and without stagnation.
In addition, in each code in FIG. 2, the same code as each code shown in FIG. 1 has the same meaning.

As shown in FIG. 2, the object to be cleaned 2 is immersed in a liquid 14 containing ozone gas in the cleaning tank 1.
At this time, in the liquid 14 containing the ozone gas, the ozone gas 5 partially dissolves in the liquid 4, and most of the ozone gas 5 rises in the liquid 4 in a gaseous state and reaches the surface of the cleaning object 2. The liquid 14 containing the ozone gas is supplied to the insertion pump 1
Since the liquids 4 are sequentially supplied through the cleaning tank 0, the liquid 4 flows at a constant speed in the cleaning tank 1. Then, the liquid 14 containing the ozone gas overflowing the cleaning tank 1 is sequentially sent to the waste liquid tank 12 as the waste liquid 11. By energizing the low-pressure mercury lamp 3 in such a state, the surface of the cleaning object 2 can be irradiated with ultraviolet light. At this time, on the surface of the object 2 to be cleaned, the ozone gas molecules absorb ultraviolet light to cause photolysis, and at the same time, generate active oxygen atoms. In addition, molecular contamination of organic substances on the surface of the cleaning target 2 also absorbs ultraviolet light and is activated. In such an environment, some of the active oxygen atoms immediately react with the molecular contamination of the surface of the object 2 to be cleaned, which is composed of activated organic substances, to form oxides. Most of the generated oxide immediately dissolves in the ozone gas-containing liquid 14 on the surface of the cleaning object 2 and then diffuses throughout the ozone gas-containing liquid 14. In addition, some of the remaining active oxygen atoms immediately react with water molecules present in the liquid 14 containing ozone gas to generate hydroxyl radicals (.OH), which react with inorganic contamination on the surface of the object 2 to be cleaned. To produce hydroxide. Most of the generated hydroxide is immediately dissolved in the liquid 14 containing the ozone gas on the surface of the cleaning object 2 and then diffused throughout. Then, the liquid 14 containing the ozone gas containing a large amount of oxides and hydroxides overflows from the cleaning tank 1 and is sequentially sent to the waste liquid tank 12 as the waste liquid 11. Therefore, the liquid 14 containing the ozone gas in the cleaning tank 1 is always kept as a liquid having a clean and stable ozone concentration, and a good cleaning effect can be maintained. As a result,
Organic contaminants such as molecular contaminants and inorganic contaminants are completely removed from the surface of the object 2 to be cleaned.

In the case where the second embodiment is applied, there is an advantage that ultrasonic waves generated when small bubbles in the liquid 14 containing ozone gas are foamed enhance the cleaning effect. In addition, there is an advantage that the expensive ozone dissolving device 9 used in the first embodiment is not required.

Example iv The above-mentioned wafer to be cleaned was immersed in the apparatus shown in FIG. 2 for 10 minutes while irradiating the surface of the wafer to be cleaned with ultraviolet light, using ultrapure water as a liquid containing ozone gas, and cleaning the wafer. .
Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 1 shows the results.

Example v The wafer to be cleaned was immersed in the apparatus shown in FIG. 2 for 10 minutes while irradiating ultraviolet light to the surface of the wafer to be cleaned, using isopropyl alcohol as a liquid containing ozone gas. Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 1 shows the results.

Example vi The wafer to be cleaned was immersed in the apparatus shown in FIG. 2 for 10 minutes while irradiating ultraviolet light to the surface of the wafer to be cleaned using trifluorotrichloroethane as a liquid containing ozone gas. Washed. Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 1 shows the results.

Embodiment 3 FIG. FIG. 3 is a configuration diagram of a cleaning apparatus according to Embodiment 3 of the present invention. This device is the same as that of the first embodiment.
And 2 are combined. Note that FIG.
In each reference numeral, the same reference numerals as those shown in FIGS. 1 and 2 have the same meaning.

Example vii The above-mentioned wafer to be cleaned was immersed for 10 minutes while irradiating ultraviolet light on the surface of the wafer to be cleaned, using ultrapure water as a liquid for dissolving ozone using the apparatus shown in FIG. . Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 1 shows the results.

Embodiment 4 FIG. FIG. 4 is a configuration diagram of a cleaning apparatus according to Embodiment 4 of the present invention. Reference numeral 18 denotes a compressor connected to increase the pressure in the cleaning tank 1, and is connected to a closed container 20 containing the cleaning tank 1 via a regulator 19. Reference numeral 17 denotes a pressure valve for adjusting the pressure in the closed container 20.
In addition, in each code | symbol in FIG. 4, the code | symbol same as each code | symbol shown in FIG. 1, FIG. 2, and FIG. 3 has the same meaning.

The cleaning method of the present invention basically includes
The requirement is to supply ozone to the surface. Further, the cleaning effect obtained at that time largely depends on the concentration of oxygen atoms generated on the surface of the object 2 to be cleaned. Therefore, a higher cleaning effect can be obtained as the molecular concentration of ozone, which is the base, becomes higher. In the apparatus of the fourth embodiment shown in FIG. 4, the pressure inside the cleaning tank 1 is increased to increase the molecular concentration of ozone in the liquid 6 in which ozone is dissolved and the molecular concentration of ozone gas 5 in the liquid 14 containing ozone gas. As a result, the cleaning effect is further improved.

Example viii The above-mentioned wafer to be cleaned was immersed in the apparatus shown in FIG. 4 for 10 minutes while irradiating the surface of the wafer to be cleaned with ultraviolet light, using ultrapure water as a liquid for dissolving ozone, and cleaning it. . Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 1 shows the results.

[0026]

[Table 1]

Comparative Example i Using the wafer as it was after sealing as a sample of Comparative Example i, contaminants were measured by a total reflection fluorescent X-ray and fine particle measuring device in the same manner as in Example i. Table 2 shows the results.

Comparative Example ii Using the apparatus shown in FIG. 1, the surface of the wafer to be cleaned was irradiated with ultraviolet light for 10 minutes without using a liquid for dissolving ozone. Thereafter, the cleaning ability was evaluated in the same manner as in Example i. Table 2 shows the results.

Comparative Example iii Using the apparatus shown in FIG. 1, ultrapure water was used as a liquid for dissolving ozone, and the above-mentioned wafer to be cleaned was immersed for 10 minutes without being irradiated with ultraviolet light, and was washed. Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 2 shows the results.

Comparative Example iv The surface of the wafer to be cleaned was irradiated with ultraviolet light for 10 minutes using the apparatus shown in FIG. 2 without using a liquid for dissolving ozone. Thereafter, the cleaning ability was evaluated in the same manner as in Example i. Table 2 shows the results.

Comparative Example v Using the apparatus shown in FIG. 2, the wafer was immersed for 10 minutes in ultrapure water without irradiating the surface of the wafer to be cleaned with ultraviolet light, and washed. Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 2 shows the results.

Comparative Example vi Using the apparatus shown in FIG. 2, the wafer to be cleaned was immersed for 10 minutes in ultrapure water without flowing ozone gas for cleaning.
Thereafter, the cleaning wafer was taken out of the cleaning tank and dried, and the cleaning performance was evaluated in the same manner as in Example i. Table 2 shows the results.

Comparative Example vii The wafer as it was after being sealed using conventional cleaning using RCA cleaning and IPA vapor phase drying in combination was used as a sample of Comparative Example vii, and the cleaning ability was evaluated in the same manner as in Example i. Was. Table 2 shows the results.

Comparative Example viii The wafer to be cleaned was cleaned by using conventional cleaning using both RCA cleaning and IPA vapor phase drying to obtain a sample of Comparative Example viii.
The cleaning ability was evaluated in the same manner as in Example i. Table 2 shows the results.

[0035]

[Table 2]

In the samples of all the examples shown in Table 1, the atomic densities of calcium (Ca) atoms and nickel (Ni) atoms per unit area were as small as those of Comparative Example i in Table 2 immediately after the unsealing and the conventional samples. It can be seen that the atomic density of the wafer immediately after the cleaning using both the RCA cleaning and the IPA vapor phase drying is lower than that. Thus, despite contamination with calcium oleate, all of the samples according to the embodiments of the present invention immediately after the sealing and the conventional RCA cleaning and IP
It can be seen that better cleaning was performed on the wafer immediately after cleaning using the vapor phase drying in combination. Further, it can be seen that the number of fine particles of the samples of Comparative Example i and Comparative Examples vii and viii is also smaller in the measurement result of fine particles of 0.1 μm or more. On the other hand, in the samples of Comparative Examples ii to v, although the cleaning was performed using the apparatus shown in FIGS. 1 and 2 according to the present invention, no ultraviolet irradiation or solution or ozone was used during the cleaning. It turns out that contaminants remain remarkably. This indicates that the solution, ultraviolet irradiation and ozone are effective for cleaning, and that the cleaning effect is significantly improved by irradiating the solution in the presence of ozone or ozone gas with ultraviolet light.

From comparison between Example i, Example ii and Example iii, it can be seen that Example ii and Example iii have a higher cleaning effect. This is probably because the solubility of ozone gas in the solvent is higher in isopropyl alcohol and trifluorotrichloroethane than in distilled water, and consequently the effect of contributing to cleaning is increased. For the same reason (the solubility of ozone gas in the solvent is increased by increasing the pressure), it is considered that the cleaning effect of Example viii was higher than that of Example i. The reason why the cleaning effect of Example vii was slightly higher than that of Example i is probably due to the effect of ozone gas.

In the above embodiment, the incident angle of the ultraviolet light to be irradiated is set to be about 90 deg with respect to the surface to be cleaned of the object to be cleaned in order to increase the irradiation efficiency of the ultraviolet light.
The present invention is not limited to this, and may be 70 deg to 110 deg. The surface to be cleaned has irregularities or parts are mounted
Irradiate the surface of the object to be cleaned obliquely
As a result, the entire surface of the object to be cleaned, including the uneven sidewalls
Can be irradiated with ultraviolet light.

The cleaning surface of the cleaning object 2 is dissolved in ozone.
It was installed at an angle of 45 deg with respect to the direction in which the gravitational acceleration works (the direction in which the ozone gas flows naturally) so as to improve the familiarity with the liquid and the ozone gas. The surface to be cleaned of the object is 10de
It is good to install so that it may incline at an angle of g to 80 deg. In particular, when ozone gas is bubbled, tilt it.
The ozone gas blends very well with the surface to be cleaned and is effective and
is there.

Further, the liquid used in the present invention is not limited to the above-mentioned water, isopropyl alcohol and trifluorotrichloroethane, but may be basically any substance as long as it can dissolve ozone. An alcohol-based solvent, a fluorine-based solvent, a mixture thereof, or a solvent containing these as a main component is used. Organic
The solubility of ozone gas in solvents is higher than that of other solvents such as water.
Organic solvent as the solvent for ozone gas
This increases the cleaning effect, which is desirable. Inside
But alcoholic solvents are easily available and have a negative impact on the environment.
It is practical with little sound.

[0041]

As described above, according to the cleaning method of the present invention, the object to be cleaned is obliquely immersed in the liquid in which ozone is dissolved, and the surface of the immersed object to be cleaned is exposed to ultraviolet light. Irradiation was carried out for cleaning, and the interaction between wet ozone and ultraviolet light made the removal difficult by the conventional method.
There is an effect that it is possible to remove contaminant particles of μm or less, and to completely remove inorganic contamination, organic molecular contamination and carbon oxide contamination. Further, the solubility of ozone gas in an organic solvent is higher than that of other solvents such as water, so that the cleaning effect is enhanced. Also, by immersing the object to be cleaned obliquely, the affinity between the object to be cleaned and the ozone solution is improved . Further, another cleaning method of the present invention includes:
By immersing the object to be cleaned obliquely in a liquid in which ozone gas is bubbled, and irradiating the surface of the immersed object with ultraviolet light for cleaning, the interaction between wet ozone and ultraviolet light is performed in the same manner as in the above method. Thus, there is an effect that it is possible to remove contaminant particles of 0.1 μm or less, which were difficult to remove by the conventional method, and to completely remove inorganic contamination, organic molecular contamination, and carbon oxide contamination. . In addition, there is an effect that ultrasonic waves generated when small bubbles of ozone gas are foamed enhance the cleaning effect . Also,
In the cleaning method, by performing the cleaning at a pressure higher than the atmospheric pressure, the molecular concentration of ozone in the liquid in which ozone is dissolved and the molecular concentration of ozone gas in the liquid containing ozone gas can be increased. Better.
Further, in the above-described cleaning method, by irradiating the surface of the object to be cleaned with ultraviolet light obliquely, even if the surface of the object to be cleaned has irregularities, even if components are mounted, it is possible to cope with the irregularities, and the side walls of the irregularities In addition, ultraviolet light can be applied to the entire surface of the object to be cleaned.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a cleaning apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a cleaning apparatus according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating a cleaning apparatus according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram illustrating a cleaning apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 cleaning tank 2 object to be cleaned 3 low-pressure mercury lamp that is a source of ultraviolet light 6 liquid in which ozone is dissolved 14 liquid containing ozone gas

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/304 645 B08B 3/08 H05K 3/26

Claims (4)

(57) [Claims] 1. An object to be cleaned is inclined in a liquid in which ozone is dissolved.
Cleaning method characterized by immersed in the order, washed by irradiating ultraviolet light on this soaked cleaning object surface. 2. An ozone gas is bubbled with ozone gas.
Dip the object to be cleaned diagonally in the liquid
Irradiate the surface of the object to be cleaned with UV light
A cleaning method characterized by the following. 3. The method according to claim 1, wherein the pressure is increased to above atmospheric pressure.
The cleaning method according to claim 1 or 2, wherein the cleaning method is performed. 4. The ultraviolet light is oblique to the surface of the object to be cleaned.
4. The method according to claim 1, wherein the irradiation is performed.
The washing method according to 1.