JPH0214294A - Cleaning solution and method for cleaning - Google Patents

Abstract

PURPOSE:To preferably carry out cleaning of various articles requiring a high level of cleanness, such as molded fluororesin product vessels, tubes, wafers, carriers, etc., for wet etching agents employed in producing semiconductors by using a cleaning solution consisting of an aqueous solution of an electrolyte in a high concentration. CONSTITUTION:The objective cleaning solution obtained by preparing an electrolyte preferably selected from the group consisting of NH4Cl, NH4F, KCl, KF, NaCl, MgCl2, MgCO3, ZnCl2, ZnSO4, FeCl3, FeOS4, AlCl3 and Al2(SO4)3 in the form of an aqueous solution in a concentration as high as preferably >=0.5wt.%. A method for cleaning preferably includes cleaning-steps with the above-mentioned cleaning solution and with super pure water respectively at least once and further a cleaning step with dilute hydrofluoric acid.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a cleaning liquid and a cleaning method.

Conventional technology and its problems In cleaning performed in the so-called biotechnology field,
It is necessary to remove submicron particles, and it is expected that the requirements for cleanliness will become even stricter in the future.

For example, fluororesin containers for wet etching agents currently used in semiconductor manufacturing are usually cleaned using aqueous solutions of surfactants, strong acids, ultrapure water, etc. (including ultrasonic cleaning, immersion cleaning, etc.). It is being said. However, with these methods, for example, in the case of NH4F-based etching agents, it takes a very long time to reach a sufficient cleaning level (the number of particles of 0.5 μm or more is on the order of 103 particles/100 m1 or less). , it can only barely clear this level, and it will not be able to meet future demands for higher levels of cleanliness. In addition, if you fill the product with NH, F-based etching agent after final cleaning,
Although the cause is unknown, in some cases, problems such as a dramatic increase in the number of fine particles occur.

Means for Solving the Problems As a result of extensive research in view of the current state of technology as described above, the inventors have discovered that a highly concentrated aqueous solution of electrolyte can exhibit excellent effects as a cleaning solution.

That is, the present invention provides the following cleaning agent and cleaning method: (1) A cleaning liquid consisting of a highly concentrated aqueous solution of electrolyte.

(2) The cleaning solution according to item 1 above, wherein the electrolyte is a salt.

■The electrolyte is NH4Cl5NH,F,KC/! .

KFSNaC11MgC12, MgCO3, ZnC/2
2, ZnSO4, FeCf3, FeSO4, AlCl
3 and A12 (SO4)3.

(2) The cleaning liquid according to item (1) above, wherein the electrolyte concentration is 0.5% by weight or more.

(2) A cleaning method comprising a cleaning process including at least one cleaning process using a cleaning liquid made of a highly concentrated aqueous solution of electrolyte and one cleaning process using water.

(2) The cleaning method according to item 5 above, further comprising a cleaning step with dilute hydrofluoric acid.

The concentration of salt in the cleaning agent in the present invention is 0.5% by weight or more (more preferably 1% by weight or more) up to a saturation concentration. If the salt concentration is less than 0.5% by weight, the desired high degree of cleaning effect will not be fully achieved.

As salts, NH4Cl5NH4F, KC! ! ,K.F.
NaCl, MgCl2, Mgco3, ZnCl2, Zn
SO4, FeCl3, FeSO4, A! ICl3 and A
Use one selected from the group consisting of 1!2 (SO4)3.

The cleaning method according to the present invention comprises a cleaning process including at least one cleaning process using a cleaning liquid made of the above-mentioned high concentration aqueous solution of salt and at least one cleaning process using ultrapure water.

The number of times of cleaning may be appropriately selected depending on the degree of contamination of the object to be cleaned. However, it is preferable to perform cleaning with ultrapure water after cleaning with the cleaning liquid. In addition, the object to be cleaned is
When the container is for an etching agent, it is also preferable to perform final cleaning with the same solution as the etching agent to be filled as a product. Specific cleaning operations include flowing the cleaning liquid or ultrapure water relative to the object to be cleaned (for example, shaking the cleaning liquid or ultrapure water in the container to be cleaned; Examples of operations include immersing the object in the cleaning liquid or ultrapure water and stirring or circulating filtration of the cleaning liquid or ultrapure water, or immersing the object in the cleaning liquid or ultrapure water and leaving it for a long time.

The cleaning method according to the present invention may be carried out at room temperature, but if necessary, a heated cleaning solution and/or ultrapure water or dilute hydrofluoric acid may be used.

The cleaning liquid and cleaning method according to the present invention are suitable for cleaning various articles that require a high degree of cleanliness, and more specifically, fluororesin molded product containers for wet etching agents used in semiconductor manufacturing; Used for cleaning tubes, wafers, carriers, etc.

Effects of the Invention According to the present invention, a high degree of cleaning effect that could not be achieved with the prior art can be obtained. In particular, in the case of NH,F-based etching agents, 0,3~
It is also possible to remove fine particles of about 0.5 μm, and the drastic increase in the number of particles of unknown cause is substantially suppressed.

EXAMPLES Examples will be shown below to further clarify the features of the present invention.

Example 1 10 after molding! ! Fill the inside of the fluororesin bottle with ultrapure water (specific resistance [mΩ・cmat 25℃]) in the order shown in Table 1.
: 18 or more, number of fine particles [pieces/100m1゜0.5 μm or more]: 10 or less, T, O, C [ppb]: 10-1
00, hereinafter the same) and a 40% by weight aqueous solution of NH4F. For cleaning, use ultrapure water or NH4F in the bottle.
Contains an aqueous solution, with an amplitude of 4 cm and a frequency of 160 vibrations/min.
After shaking for a minute, the mixture was allowed to stand, and the number of particles was measured using a particle counter. In addition, in each of the following Examples and Comparative Examples, unless otherwise specified, cleaning was performed in the same manner as in this Example.

Table 1 shows ultrapure water or NH4F aqueous solution 1 after each cleaning process.
It shows the number of fine particles of 0.5 μm or more present in 0.00ml. The number of fine particles can be measured using a dust counter (“HIAC/ROY
CO4100'').

The highly concentrated aqueous solutions of salts used in this example and the following examples were filtered through a 0.1 μm filter to remove the number of fine particles.

No. table From the results shown in Table 1, the following is clear.

In the case of bottle 1, by washing seven times with ultrapure water,
The number of fine particles has apparently decreased to 369. However, since the number of fine particles increased again after cleaning with the NH,F aqueous solution, it is clear that there were many fine particles that were not washed away with ultrapure water. Furthermore, by washing twice with ultrapure water, the number of fine particles finally decreased to 246, and then N
Even after washing with H4F aqueous solution, the number of fine particles no longer increases.

In the case of Bottle 2, the initial number of particles was extremely large, so even after washing 10 times with ultrapure water, the number of particles decreased.
The number has decreased to only about 50,000.

After that, when washed with NH,F aqueous solution, the number of fine particles was reduced to 10.
The number of fine particles increased by more than double, and by subsequent washing twice with ultrapure water and washing with an NH4F aqueous solution, the number of fine particles decreased to <1121 particles.

Example 2 The inside of a molded 101 fluororesin bottle was washed with ultrapure water in the same manner as in Example 1, and then filled with a 50% HF aqueous solution and kept immersed under the conditions shown in Table 2. Then,
Cleaning with ultrapure water and
Washing was performed with a wt% NH4F aqueous solution.

Table 2 shows the results. In addition, the number of fine particles after washing with NH and F aqueous solutions is 0.3 μ in 10 ml of solution.
Indicates the number of fine particles of 100 m or more.
0 in +r+1. Indicates the number of fine particles of 5 μm or more. 0.
The number of particles larger than 3 μm can be measured using a particle counter (“RIO”).
NKL-21'').

Table Example 3 The molded IOJ fluororesin bottles were washed with ultrapure water and with a 40% by weight NH4F aqueous solution in the order shown in Table 3.

Table 3 shows the number of fine particles of 0.5 μm or more in 100 ml of liquid at each stage.

From the results shown in Table 3, cleaning with ultrapure water and 40% by weight
It is clear that the cleaning effect is significantly improved by appropriately combining cleaning with an NH,F aqueous solution.

Example 4 The molded 106 fluororesin bottles were washed with ultrapure water and with a 20% KCl aqueous solution in the order shown in Table 4.

Table 4 shows the number of fine particles of 0.5 μm or more in 100 ml of liquid at each stage.

From the results shown in Table 4, cleaning with ultrapure water and 20% by weight
It is clear that by appropriately combining cleaning with a KCJ aqueous solution, fine particles that cannot be removed by cleaning with ultrapure water alone are removed (as shown by the rising edge of the graph), and the cleaning effect is significantly improved.

Comparative Example 1 Using a 0.1% by weight aqueous solution of a polyoxyethylene alkylphenol ether surfactant (trademark "Nonipol 100") used as a container cleaning agent and ultrapure water, a molded ICB fluororesin was prepared. After the inside of the bottle was washed, it was washed with a 40% by weight NH,F aqueous solution and ultrapure water.

The results are shown in Table 5.

As is clear from the results shown in Table 5, sufficient cleaning was apparently achieved by cleaning with the combination of surfactant diluted water solution and ultrapure water. However, NH,
By further washing with the F aqueous solution, the fine particles that had not actually been removed were washed out again. This shows that cleaning using a combination of a surfactant aqueous solution and ultrapure water is actually insufficient in cleaning, even if it appears to be clean.

(that's all) Procedural amendment (spontaneous) Display of incidents 1986 Patent Application No. 1.65223 name of invention Cleaning liquid and cleaning method

Claims (1)

[Claims] (1) A cleaning solution consisting of a highly concentrated aqueous solution of electrolyte. (2) The cleaning liquid according to claim 1, wherein the electrolyte is a salt. (3) The electrolyte is NH_4Cl, NH_4F, KCl,
KF, NaCl, MgCl_2, MgCO_3, ZnC
l_2, ZnSO_4, FeCl_3, FeSO_4,
The cleaning liquid according to claim 1, which is one selected from the group consisting of AlCl_3 and Al_2(SO_4)_3. (4) The cleaning liquid according to claim 1, wherein the electrolyte concentration is 0.5% by weight or more. (5) A cleaning method comprising a cleaning process including at least one cleaning process using a cleaning liquid made of a highly concentrated aqueous solution of electrolyte and one cleaning process using water. (6) The cleaning method according to claim 5, further comprising a cleaning step with dilute hydrofluoric acid.