JP2524020B2 - Liquid particle adhesion control method - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to electronic materials, magnetic materials,
The present invention relates to a method for controlling dispersion and adhesion of fine particles of various metals, alloys, inorganic compounds including ceramics or compounds containing organic substances in many manufacturing processes such as optical materials and ceramics.

In particular, the present invention relates to a cleaning method for preventing or reducing the adhesion of fine particles to the surface of a semiconductor substrate such as a semiconductor wafer in the manufacturing process of semiconductor devices.

[0003]

2. Description of the Related Art In recent years, the degree of integration of integrated circuits formed on the surface of a substrate such as a semiconductor wafer has been increasing, and the line width of patterns has become finer accordingly. The minimum processing size of the next 16 MDRAM is 0.5 μm, and it is considered that finer fine particles in the manufacturing process hinder the improvement of product quality and yield.

Conventionally, as a means for cleaning the surface of a substrate, RCA Review 31 (1970), pages 187 to 206 [RCA Review, 31 (197).
0) P. 187-206], a method of heating a mixture of ammonia water and hydrogen peroxide water to about 80 ° C. and immersing the wafer in this, or a method of applying ultrasonic waves in ultrapure water is used. is there. Especially for the latter ultrasonic cleaning, not the usual 50 kHz, but Journal of Electronic Materials Vol. 8 (1979) pp. 855 to 864 [J. Elec. Materials,
8 (1979) P855-864], a device with a frequency of 850 kHz is used,
As described in JP-A-0-187380, the distance between the ultrasonic wave emitting surface and the liquid surface may be changed, or JP-A-61-1012.
As described in No. 83, the fundamental frequency is frequency-modulated or various measures are taken for practical use.

[0005]

Due to the higher integration density of the integrated circuit, the minimum processing size of the next 16M DRAM is 0.5 μm, and the size of the fine particles to be cleaned is also reduced accordingly. 0.05
It is considered that it is also necessary to remove fine particles of μm.

As the fine particles become finer, the number of them present in the atmosphere increases, and the fine particles of 0.05 μm are several times larger than the fine particles of 0.13 μm which are currently (4MDRAM) targets. Moreover, it is considered that the particles become more likely to adhere to the substrate as they become finer, and thus it can be said that the need for particle cleaning technology is increasing.

However, in the conventional method of removing fine particles from a substrate by mechanical force such as ultrasonic waves, as the fine particles become finer, their mass and surface area become smaller, so that the mechanical force applied to each piece is small. Becomes difficult to remove. Further, damage to the substrate has become a problem as the degree of integration of semiconductors is improved. Therefore, it is considered difficult to remove fine particles by the conventional method.

The present invention provides a technique for changing the idea in order to solve the above problems and preventing or reducing the adhesion of fine particles to a substrate.

[0009]

The present invention provides a substance capable of controlling the zeta potential (surface potential) of fine particles in a solution,
The present invention relates to a method for controlling adhesion of fine particles in liquid, which prevents or reduces the adhesion of the fine particles in the solution by adding the fine particles in the solution.

FIG. 1 shows a basic conceptual diagram of the present invention. FIG.
FIG. 1A shows the relationship between the distance between the substrate and the fine particles and the potential energy (W), and FIG.
The electrostatic repulsion force by the electric double layer formed by the surface charge 3 between the substrate 1 and the fine particles 2, FIG.
FIG. 3 is a conceptual diagram showing an attractive force due to a van der Waals force between particles and fine particles 2. As shown in FIG.
In the liquid, the potential energy W between the substrate 1 and the fine particles 2 is the sum of two potentials (W = VA + VR), which are the attractive force (VA) due to the van der Waals force and the electrostatic repulsive force (VR) due to the electric double layer. It is considered that the particles adhere to the substrate when the potential peaks are exceeded. Therefore, the present invention has been made paying attention to increasing the electrostatic potential by increasing the surface potential (zeta potential) of the substrate and the particles in order to increase the peak of this potential and reduce the adhesion of the particles to the substrate. It is a thing.

FIG. 2 shows the relationship between the amount of fine particles adhering to the substrate and the zeta potential of the fine particles.

In FIG. 2, 4 is a silicon (Si) particle etched by hydrofluoric acid (HF: H in volume ratio).
Fine particles collected by a filter after being immersed in hydrofluoric acid of ₂ O = 1: 99. Hereinafter referred to as bare Si particles. ) 5 is untreated Si particles and 6 is polystyrene particles. The zeta potential differs depending on the type of particles, and even the same Si particles have different zeta potential values depending on the surface state, and the amount of fine particles attached to the substrate also differs. Therefore, it is considered that the adhesion of fine particles to the substrate can be prevented or reduced by controlling the zeta potential.

Further, the zeta potential of the substrate and the fine particles is generally negative, but in rare cases, both may be positive like the alumina substrate and the alumina particles. Controlling the zeta potential means increasing its absolute value.

The present invention is based on the finding that the zeta potential of fine particles or a substrate can be controlled by adding a specific substance to a liquid.

Here, the relationship between the zeta potential and the sliding surface will be briefly described.

When the fine particles move in the solution, it is considered that several layers of liquid molecules are adsorbed and moved around the fine particles. The boundary surface between several layers of liquid molecules and the surrounding liquid at this time is called a "sliding surface", and the electric potential of this surface is related to the adhesion of fine particles as described above. (The sliding surface is described in, for example, Fumio Kitahara, "Chemistry of Dispersion / Emulsion System" (Engineering Book, 1979), page 102.) On the other hand, since the zeta potential is measured by an electrophoresis method, this slip is exactly You are measuring the surface potential. (Details of the zeta potential measurement are shown in the examples below.) In the present invention, alcohol, glycol, amine, amide, aminoalcohol, aldehyde, organic acid, ester is used as a substance capable of controlling the zeta potential, that is, the potential of the sliding surface. It has been found that it is effective to add substances such as a ketone and a nonionic surfactant to the liquid. In these substances, the charge distribution in the molecule is not uniform, some parts are slightly positive, some parts are slightly negative, and the total is zero. That is, these materials have a dipole moment. It is considered that the nonuniformity of the charge distribution causes the zeta potential of the fine particles and the like to change due to these substances. For example, when various alcohols are used, the zeta potential values are different, which can be explained semi-quantitatively by the heterogeneity of the charge distribution in the molecule as follows.

FIG. 3 and FIG. 4 show the charge distribution in the molecule and the zeta potential of the alcohol obtained by theoretical calculation based on quantum mechanics for the alcohol molecule adsorbed on the surface of the fine particles. The adsorption state of each alcohol on the fine particles 2 may be the case shown in FIG. 3 or the case shown in FIG. In the case shown in FIG. 3, assuming that the position of the sliding surface is the third to fourth atoms from the surface of the fine particles 2, the larger the absolute value of the electric charge of the carbon atom near that position, the larger the absolute value of the zeta potential. I understand that. That is, when alcohol is adsorbed, it can be considered that the local distribution of electric charges existing in the vicinity of the third to fourth atoms from the adsorption end affects the value of zeta potential. On the other hand, in the case shown in FIG. 4, the relationship between the position of the oxygen atom having a large negative charge and the sliding surface differs depending on each alcohol, and the closer the oxygen atom is to the sliding surface, the larger the absolute value of the zeta potential becomes. I can think. Therefore, in each case, it is inferred that the magnitude of the zeta potential depends on the nonuniformity of the charge distribution in the alcohol molecule.

However, it is essential that a substance capable of controlling the zeta potential is adsorbed on a substrate or fine particles, and a hydrophilic group such as --OH, --CHO, --COOH and --NH ₂ and a hydrocarbon group are contained in one molecule. It has a common point that it is a substance having a hydrophobic group consisting of, and this is considered to cause adsorption to fine particles.

Further, the above substances capable of controlling the zeta potential are substances which hardly dissociate into ions. When a substance that easily dissociates into ions is added to the liquid, the concentration of ions in the liquid becomes high, and the particles tend to adhere. That is, even if the zeta potential is increased, the particle adhesion preventing effect may not be sufficiently exhibited. Therefore, it is very preferable to use a substance that is difficult to dissociate into ions in order to realize the present invention.

Therefore, it can be understood that a substance which is less likely to undergo ion dissociation and has a hydrophilic group and a hydrophobic group in one molecule is effective for controlling the zeta potential. However, the effect of controlling the zeta potential differs depending on the balance between the charge distribution in the molecule and the slip surface. That is, it can be easily understood that a substance in which the charge distribution of any of the atoms 2 to 6 from the adsorption end of the hydrophobic group to the fine particles or a plurality of atoms is negative is effective. Specifically, those atoms are oxygen atoms,
This is the case where a halogen atom, a nitrogen atom or the like has a large electronegativity, or the atomic group bonded to them is an electron emitting group or an atom with a high electronegativity. It is also effective to combine a plurality of types of substances.

FIG. 5 is a conceptual diagram showing a state in which two or more kinds of nonionic surfactants or the like having different molecular lengths are adsorbed on the surface of fine particles. As shown in FIG. 5, CH ₃ —R—R—R—R—OH and CH _{3 having} different molecular lengths are formed on the surface of the fine particles 2.
-R-R-R-OH ( R is, - (CH ₂₎ alcohol when n- of, R is _{- (CH 2 CH 2 O)} m-, or - (C
H ₂₎ n-and - (CH ₂ CH ₂ O) is when a m- combination is a nonionic surfactant. n and m are integers of about 5 to 20. ) Is adsorbed, the molecular ends of the shorter molecules that are densely adsorbed become pseudo particle surfaces, that is, the sliding surfaces of the fine particles shift to the outside of the ends of the shorter molecules. Since the hydrophilic group of the longer molecule (including an oxygen atom having a high electronegativity) is located just near the sliding surface, this is an effective method for controlling the zeta potential.

FIG. 6 (a) is a conceptual diagram showing a state in which, when a nonionic surfactant and an alcohol having a relatively short molecular chain are added in combination, these are adsorbed on the surface of the fine particles 2. 6 (b) and 6 (c) are conceptual diagrams showing a state in which, when a nonionic surfactant or the like and an amino alcohol are added in combination, these are adsorbed on the surface of the fine particles 2. In FIGS. 6A to 6C, R is the same as in FIG.

As described above, when the nonionic surfactant and the alcohol or aminoalcohol are used in combination, the low molecular weight alcohol or aminoalcohol is adsorbed on the hydrophobic group portion of the nonionic surfactant or the like. It is thought that a zeta potential change occurs. Further, depending on the type of fine particles, the amount of adsorption increases, so that the change in zeta potential also increases. Therefore, the effect of preventing the adhesion of fine particles is also increased.

In addition to those mentioned above, those having a large adhesion preventing effect when combined with a nonionic surfactant and the like include hydrophilic groups in one molecule such as glycol, amine, amide, aldehyde, organic acid, ester and ketone. It is a substance having a hydrophobic group.

The addition concentration of the above-mentioned substance depends on the kind of the substance, but is generally 10 to ^{7 to} 25 v with respect to the solution.
ol%. Addition of 10 to ⁷ vol% or more is effective, and addition of more than 25 vol% is meaningless.

The optimum addition concentration range is 0.1 to 2.5 vol% for alcohol, 10 to ⁷ to 10 to ¹ vol% for amino alcohol, and 10 to ³ to 10 for organic acid.
~ ¹ vol%, in the case of aldehyde 0.1-1 vol%,
In the case of ketone, it is 0.1 to 2 vol%.

[0027]

According to the present invention, by adding a substance capable of controlling the zeta potential to the solution, the absolute value of the zeta potential of the fine particles in the solution becomes large, and the electrostatic repulsion force between the substrate and the fine particles in the liquid is increased. Will increase. As a result, the potential energy between the fine particles and the substrate increases, and it becomes possible to prevent or reduce the adhesion of the fine particles to the substrate.

At the same time, it becomes possible to improve the dispersion or reduce the agglomeration of the fine particles.

[0029]

EXAMPLES First, the zeta potential measuring method will be described.

The zeta potential can be usually determined by an electrophoresis method. Electrophoresis is a phenomenon in which fine particles with surface charge move when an electric field is applied to a liquid. By measuring the moving velocity of the fine particles, the zeta potential of the fine particles, which is proportional to the moving velocity, is obtained. You can
In the present invention, LA manufactured by Pen Kem based on this principle is used.
The zeta potential of the fine particles was measured with a SER ZEE ™ Model 501.

In order to confirm the effect of the present invention, polystyrene particles, Si particles, SiO ₂ particles, Si ₃ N ₄ particles, T
iO ₂ particles, Cr particles, Fe particles, Cu particles and W particles were used. These particles are used simply because particles having a uniform particle size can be easily obtained, and the effect of the present invention is not limited to these fine particles.

The polystyrene particles are The Dow C
Particle size 1-0.0 made by chemical company
The one having a size of 38 μm was used. Si particles, SiO ₂ particles, S
i ₃ N ₄ particles, TiO ₂ particles, Cr particles, Fe particles, Cu
The particles and W particles used had a particle diameter of 1 μm manufactured by Kojundo Chemical. There is a case where Si particles are not pretreated, and a case where bare Si particles used in the experiment after being etched in hydrofluoric acid having a volume ratio of HF: H ₂ O = 1: 99 for 1 minute. Regarding P-type Si particles, a P-doped S-type 5 inch P-type S having a specific resistance of 9.00 to 12.0 Ωcm is used.
The i-wafer (100 surfaces) was crushed to a particle size of 1 μm and not pretreated, and the bare wafer used in the experiment after etching for 1 minute in hydrofluoric acid with a volume ratio of HF: H ₂ O = 1: 99. It may be P-type Si particles. Furthermore, highly doped P in which P is highly doped and a 5-inch P-type Si wafer (111 surface) having a specific resistance of 0.006 Ωcm is crushed to have a particle diameter of 1 μm.
Type Si particles were also used. Similarly for N-type Si particles,
A B-doped 5-inch N-type Si wafer (100 faces) having a specific resistance of 8.00 to 12.0 Ωcm was crushed to have a particle diameter of 1
.mu.m and no pretreatment, and pre-treated bare P-type Si particles and B highly doped specific resistance 0.01 to 0.018 .OMEGA.
A highly doped N-type Si particle having a particle diameter of 1 μm was obtained by crushing a 5-inch N-type Si wafer (111 surface).

It is considered that the value of the zeta potential does not depend on the particle size of the particles, and the measured data with the above particle size is 0.05 μm.
Even ultrafine particles of about m can be used as they are.

Example 1 Tables 1 and 2 show the effects of controlling the zeta potential of substances having a hydrophilic group and a hydrophobic group that are difficult to dissociate into ions. Alcohol, aldehyde, organic acid,
A wide range of substances such as esters and ketones were observed to have a zeta potential controlling effect. Among these, as an example of the added concentration and the effect of controlling the zeta potential, a case where ethanol is added to bare Si particles etched with hydrofluoric acid will be described.

[0035]

[Table 1]

[0036]

[Table 2]

FIG. 7 shows the relationship between the concentration of ethanol added and the change in zeta potential of bare Si particles. The bare Si particles before the addition of ethanol were −23.2 mV, but 0.5 vo
It was possible to control the zeta potential of Si particles to -47.3 mV by adding 1% ethanol. (Although not shown in FIG. 7, it was effective up to about 25 vol% (20 wt%) addition.) The addition concentration at which the value of the zeta potential becomes the minimum varies depending on the substance, but also for substances other than ethanol, FIG. Similar results were obtained. Table 1 and Table 2
Table 1 shows the added concentration and the value of the zeta potential when the value of the zeta potential was minimum for various substances.

Example 2 With respect to amino alcohol, a larger effect was obtained with a smaller addition concentration.
Table 3 shows changes in zeta potential when various amino alcohols were added.

[0039]

[Table 3]

FIG. 8 shows the relationship between the added concentration when 2-aminoethanol was added and the zeta potential of 1 μm polystyrene particles, and FIG. 9 is the relationship between the added concentration and monoisopropanolamine when added. Shown in. In the case of amino alcohol, the value of the zeta potential is unlikely to be the minimum as in the substance of Example 1, and the absolute value of the zeta potential becomes larger as it is added as shown in FIGS. 8 and 9.

Amino alcohol is 10 to ⁷ mol.
Addition of 1 / l (6 × 10 to ⁷ vol%) or more showed a sufficient effect for controlling the zeta potential.

Example 3 Table 4 shows changes in the zeta potential when an alcohol containing a halogen atom or the like was added.

[0043]

[Table 4]

Hexafluoro-2-propanol and 1
It was found that H, 1H-pentafluoropropanol has an effect of greatly changing the zeta potential. It can be seen that both are more effective than the substance containing no halogen atom.

Further, pentadecafluorocaprylic acid was examined as an example of a surfactant containing halogen. It was found to have the effect of changing the zeta potential.

Example 4 Table 5 shows changes in zeta potential when a substance containing a nitrogen atom was added.

[0047]

[Table 5]

It was found that formamide and N-methylformamide have the effect of greatly changing the zeta potential. It can be seen that both are more effective than the substance containing no nitrogen atom.

(Example 5) _{(R :-( CH 2) n-,} n synthesizes a nonionic surfactant represented by an integer.) Of 5 to 20, were studied zeta potential control effect. Table 6 shows the results.

[0050]

[Table 6]

It has been found to be effective for many particles. A similar effect can be expected with a surfactant having a similar structure.

Example 6 Two kinds of nonionic surfactants I: CH ₃ (CH ₂ ) ₁₀ CH ₂ O (CH ₂ C) having different molecular lengths
H ₂ O) ₁₂ H and II: CH ₃ (CH ₂ ) ₁₄ CH ₂ O (CH ₂
CH ₂ O) ₁₄ H was synthesized and the zeta potential control effect of these was examined. The results are shown in Table 7.

[0053]

[Table 7]

It has been found to be effective for many particles. The same effect can be expected with a combination of surfactants having a similar structure.

Example 7 Nonionic Surfactant CH
Examples in which ₃ (CH ₂ ) ₁₀ CH ₂ O (CH ₂ CH ₂ O) ₁₂ H and an alcohol are used in combination are shown in Tables 8, 9 and 10.

[0056]

[Table 8]

[0057]

[Table 9]

[0058]

[Table 10]

In particular, the effect of F, which is small with alcohol alone, is small.
It was found that e particles, Si particles, SiO ₂ particles and the like also have a great effect. Further, similar to Si particles, Si particles doped with impurities such as P-type Si particles and N-type Si particles also had a great effect. Of course, similar effects can be expected with alcohols other than ethanol.

Example 8 Nonionic Surfactant CH
Examples of combinations of ₃ (CH ₂ ) ₁₀ CH ₂ O (CH ₂ CH ₂ O) ₁₂ H and amino alcohol are shown in Tables 11, 12 and 13.

[0061]

[Table 11]

[0062]

[Table 12]

[0063]

[Table 13]

In particular, it was found that Fe particles, Si particles, SiO ₂ particles, etc., which have a small effect only with amino alcohol, have a great effect. Also, as with Si particles, P type S
There was a great effect on Si particles doped with impurities such as i particles and N-type Si particles.

(Example 9) The effect of preventing adhesion of fine particles according to the present invention was confirmed by the following procedure. As shown in FIG. 10, 0.038 μm polystyrene particles were dispersed in ultrapure water in the liquid tank 9 (fine particle concentration was adjusted to 5 × 10 ¹¹ particles / m ³ ), and the 4-inch Si wafer 8 was immersed for a certain period of time. did. Next, this is pulled up from the liquid tank 9 and spinner dried,
The number of attached polystyrene particles was measured by an electron microscope (SEM). The relationship between the immersion time and the number of deposits is shown as 10 in FIG. It was found that the number of deposits increased with the immersion time. Next, 2-aminoethanol is added at 6 × 10 to ⁵ vol.
%, The adhesion test was conducted in the same manner, and the obtained result is also shown as 11 in FIG. Almost no adhesion was seen.

When ethanol was added instead of 2-aminoethanol, the adhered amount was reduced to about one third (12 in FIG. 12) (Example 10) Next, 0.038 μm polystyrene particles were used. The same adhesion experiment was conducted by adding hydrochloric acid to adjust the hydrogen ion concentration of the solution. The relationship between the immersion time at pH = 3 and the number of deposits was the same as the result in ultrapure water and was the same as in FIG. That is, the number of adhesion increases with the immersion time,
Almost no adhesion was observed by adding 6 × 10 ⁵ vol% of aminoethanol.

Example 11 Next, the same adhesion experiment was conducted using 0.2 μm polystyrene particles. However, an optical microscope was used to measure the number of adhered particles. Since particles of 0.2 μm hardly adhere to ultrapure water, hydrochloric acid was added to adjust the hydrogen ion concentration of the solution, and the experiment was conducted. As shown as 13 in FIG. 13, when the acidity becomes higher than about pH 3, 0.2 μm particles will adhere. (The particle concentration was set to 4 × 10 ¹² particles / m ³ and the wafer was immersed for 10 minutes.) 2-Aminoethanol 6 × 10
When ~ ⁵ vol% was added, the hydrogen ion concentration at which adhesion occurred changed as shown as 14 in FIG. That is,
It is shown that the addition of 2-aminoethanol can prevent the adhesion that has occurred at a certain pH.

Example 12 Next, the same adhesion experiment was conducted using 1 μm polystyrene particles. However, an optical microscope was used to measure the number of adhered particles. Almost no adhesion of 1 μm particles was observed in ultrapure water, so experiments were conducted by adding hydrochloric acid to adjust the hydrogen ion concentration of the solution. FIG.
As shown as No. 15, when the acidity becomes higher than about pH 2.2, 1 μm particles are attached. (The fine particle concentration was set to 5 × 10 ¹³ particles / m ³ and the wafer was immersed for 10 minutes.) When 6 × 10 to ⁵ vol% of 2-aminoethanol was added, hydrogen was produced as shown by 16 in FIG. The ion concentration changed. That is, it is shown that the addition of 2-aminoethanol can prevent the adhesion that has occurred at a certain pH, that is, the adhesion can be prevented even in a region having a higher acidity.

It should be noted that there is a symmetrical effect on the alkaline side as well, and the addition of 2-aminoethanol makes it possible to shift the region where adhesion occurs to a more alkaline region.

(Example 13) Next, the volume ratio of HF: H ₂ O was changed.
= 1:99 of hydrofluoric acid was prepared to disperse bare Si particles having a particle diameter of 1 µm, and the same adhesion experiment was performed.
(The fine particle concentration was adjusted to 5 × 10 ¹³ particles / m ³ ).
As shown in 17 of No. 5, it was found that the number of deposits increased with the immersion time. Next, 10 to ⁶ mol / l of the nonionic surfactant used in Example 7 and 6 × 1 of 2-aminoethanol were used.
After adding 0 to ⁵ vol%, an adhesion experiment was conducted in the same manner. The obtained result is also shown at 18 in FIG. Almost no adhesion was seen.

(Example 14) Next, the particle diameter was 1 μm in ultrapure water.
m Si particles were dispersed and the same adhesion experiment was performed.
(Si particles were not subjected to etching treatment with hydrofluoric acid, and the particle concentration was adjusted to 5 × 10 ¹³ particles / m ³ .
Soaked for a minute. ) As shown as 19 in FIG.
If the acidity is higher than about 2.2, 1 μm particles will be attached. The nonionic surfactant used in Example 7 and 10 to ⁶ mol / l and 2-aminoethanol were added to 6 × 10 to ⁵
When vol% was added, the hydrogen ion concentration at which adhesion occurred changed to a more acidic side, as indicated by 20 in FIG.
That is, a certain pH is obtained by adding 2-aminoethanol.
It was found that it was possible to prevent the adhesion that had occurred in.

(Example 15) Next, the particle size in ultrapure particles was 1 μm.
The SiO ₂ particles of m were dispersed and the same adhesion experiment was conducted. (The fine particle concentration was adjusted to 5 × 10 ¹³ particles / m ³ and the wafer was immersed for 10 minutes.) As shown as 21 in FIG. 17, when the acidity becomes higher than about pH 2.2, 1 μm particles adhere. . The nonionic surfactant used in Example 7 (10 to ⁶ mol / l) and 2-aminoethanol (6 ×) were added.
When 10 to ⁵ vol% was added, the hydrogen ion concentration at which adhesion occurred changed to a more acidic side, as indicated by 22 in FIG. That is, it was found that the addition of 2-aminoethanol can prevent the adhesion that had occurred at a certain pH.

(Example 16) Next, a particle size of 1 was added to ultrapure water.
Fe particles of μm were dispersed, and the same adhesion experiment was performed. (The fine particle concentration was adjusted to 5 × 10 ¹³ particles / m ³ and the wafer was immersed for 10 minutes.) As shown as 23 in FIG. 18, when the acidity becomes higher than about pH 3, 1 μm particles adhere. The nonionic surfactant used in Example 7 (10 to ⁶ mol / l) and 2-aminoethanol (6 × 10 6) were added.
When ~ ⁵ vol% was added, the hydrogen ion concentration at which adhesion occurred changed as shown by 24 in FIG. That is,
It has been found that the addition of 2-aminoethanol can prevent the adhesion that had occurred at a certain pH.

Example 17 Next, the relationship between the concentration of 2-aminoethanol added and the anti-adhesion effect was examined. 1
The same adhesion experiment was performed by dispersing polystyrene particles of μm. (The fine particle concentration was adjusted to 5 × 10 ¹³ particles / m ³ ). As shown as 25 in FIG. 19, when the acidity becomes higher than about pH 2.2, 1 μm particles adhere. When 2-aminoethanol was added in an amount of 6 × 10 to ⁵ vol%, the hydrogen ion concentration at which adhesion occurred changed as indicated by 26 in FIG. It was revealed that when the addition concentration of 2-aminoethanol was set to 6 × 10 to ³ vol%, the hydrogen ion concentration at which adhesion occurred was further reduced and the adhesion prevention effect was further increased, as indicated by 27 in FIG. . That is, it is considered that the absolute value of the zeta potential of the fine particles increased as the concentration of 2-aminoethanol added increased, and the anti-adhesion effect increased accordingly. Therefore, the same effect can be expected for other particles by increasing the addition concentration.

(Embodiment 18) Next, in a volume ratio, HF: H ₂ O
= 1: 99 hydrofluoric acid was prepared to adjust the particle size of S to 1 μm.
The i particles were dispersed and the same adhesion experiment was performed. (The particle concentration was adjusted to 5 × 10 ¹³ particles / m ³ ). As shown in FIG. 20, it was found that the number of deposits increased with the immersion time. Next, 10 to ⁷ mol of the nonionic surfactant used in Example 7
/ L and 1-vol% of m-aminophenol were added,
An adhesion experiment was conducted in the same manner, and the obtained results are also shown at 29 in FIG. Almost no adhesion was seen.

(Example 19) Next, in volume ratio, HF: H ₂ O was used.
= 1: 99 hydrofluoric acid was prepared to adjust the particle size of S to 1 μm.
The i particles were dispersed and the same adhesion experiment was performed. (The particle concentration was adjusted to 5 × 10 ¹³ particles / m ^3. ) As shown in FIG. 21, it was found that the number of deposits increased with the immersion time. Next, the nonionic surfactants 10 to ⁷ used in Example 7 were used.
After adding mol / l and 0.5 vol% formamide,
An adhesion experiment was conducted in the same manner, and the obtained results are also shown at 31 in FIG. Almost no adhesion was seen.

(Embodiment 20) Next, in volume ratio, HF: H ₂ O
= 1: 99 hydrofluoric acid was prepared to adjust the particle size of S to 1 μm.
The i particles were dispersed and the same adhesion experiment was performed. (The particle concentration was adjusted to 5 × 10 ¹³ particles / m ^3. ) As shown in FIG. 22, it was found that the number of adhesion increased with the immersion time. Next, the nonionic surfactants 10 to ⁷ used in Example 7 were used.
After adding mol / l and benzylamine 10 to ⁵ mol / l, the adhesion test was conducted in the same manner, and the obtained results are also shown in 33 of FIG. Almost no adhesion was seen.

From the above adhesion experiments, it was proved that the control of the zeta potential described in the present invention is effective for preventing and reducing the adhesion of fine particles.

(Embodiment 21) FIG. 23 shows an example of a cleaning system for carrying out the present invention. In FIG. 23, the ultrapure water produced in the ultrapure water production unit 34 and the zeta potential control substance supplied from the zeta potential control substance storage unit 35 via the mixing amount adjuster 36 are sent to the cleaning tank 37. S that are mixed together and carried to the cleaning tank 37 from the Si wafer transfer system 38.
Used for cleaning i-wafer.

[0080]

According to the present invention, since the adhesion of fine particles in a liquid can be prevented and reduced, the yield of electronic parts such as semiconductor devices, thin film devices and disks can be increased, and the above products can be manufactured at low cost. Can be manufactured.

At the same time, it becomes possible to improve the dispersion of the fine particles or to reduce the agglomeration.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a distance between a substrate and fine particles and potential energy according to the present invention.

FIG. 2 is a diagram showing the relationship between the zeta potential of fine particles and the number of fine particles attached.

FIG. 3 is a diagram showing the charge distribution of alcohol molecules adsorbed on the surface of fine particles and the potential on the sliding surface.

FIG. 4 is a diagram showing the charge distribution of alcohol molecules adsorbed on the surface of fine particles and the potential of the sliding surface.

FIG. 5 is a diagram showing nonionic surfactant molecules or alcohol molecules adsorbed on the surface of fine particles.

FIG. 6 (a), FIG. 6 (b) and FIG. 6 (c) are diagrams showing adsorption states when a nonionic surfactant and an alcohol are added in combination.

FIG. 7 is a diagram showing the relationship between the concentration of ethanol added and the zeta potential of bare Si particles.

FIG. 8 is a graph showing the relationship between the concentration of 2-aminoethanol added and the zeta potential of polystyrene particles.

FIG. 9 is a graph showing the relationship between the concentration of monoisopropanolamine added and the zeta potential of fine particles.

FIG. 10 is a process diagram of immersing a 4-inch Si wafer in an ultrapure aqueous solution containing fine particles and taking it out.

FIG. 11 is a graph showing the relationship between the immersion time of a wafer and the number of adhered fine particles.

FIG. 12 is a graph showing the relationship between the immersion time of a wafer and the number of adhered fine particles.

FIG. 13 is a diagram showing a relationship between hydrogen ion concentration and the number of adhered fine particles.

FIG. 14 is a diagram showing the relationship between hydrogen ion concentration and the number of adhered fine particles.

FIG. 15 is a graph showing the relationship between the immersion time of a wafer and the number of adhered fine particles.

FIG. 16 is a diagram showing a relationship between the hydrogen ion concentration and the number of adhered fine particles.

FIG. 17 is a diagram showing a relationship between hydrogen ion concentration and the number of adhered fine particles.

FIG. 18 is a diagram showing a relationship between hydrogen ion concentration and the number of adhered fine particles.

FIG. 19 is a diagram showing a relationship between hydrogen ion concentration and the number of adhered fine particles.

FIG. 20 is a diagram showing the relationship between the immersion time of a wafer and the number of adhered fine particles.

FIG. 21 is a diagram showing the relationship between the immersion time of a wafer and the number of adhered fine particles.

FIG. 22 is a diagram showing the relationship between the immersion time of a wafer and the number of adhered fine particles.

FIG. 23 is a diagram showing an example of a cleaning system according to the present invention.

[Explanation of symbols]

1 ... Substrate, 2 ... Fine particles, 3 ... Surface charge, 4 ... Bare Si particles, 5 ... Si particles, 6 ... Polystyrene particles, 7 ... Sliding surface, 8 ... 4 inch Si wafer, 9 ... Liquid tank, 10 ... No additive In the case of, 11 ... 2-aminoethanol is added at 6 × 10 to ⁵ vo
When 1% is added, 12 ... Ethanol is added by 1 vol%, 13 ... Hydrochloric acid is added, 14 ... 2-Aminoethanol is added by 6 × 10 to ⁵ vol%, 15
... when hydrochloric acid is added, 16 ... when 2-aminoethanol is added at 6x10 to ⁵ vol%, 17 ... when no addition is added, 18 ... nonionic surfactant 10 to ⁶ mol / l and 2-
When 6 × 10 to ⁵ vol% of amino ethanol is added,
19 ... In the case of no addition, 20 ... Nonionic surfactant 10 to ⁶
mol / l and 2-aminoethanol the 6 × 10 ~ ⁵ vol
%, 21 ... no addition, 22 ... nonionic surfactant 10 to ⁶ mol / l and 2-aminoethanol 6 × 10 to ⁵ vol%, 23 ... no addition, 24 ... and a non-ionic surfactant 10 ~ ⁶ mol / l 2-
When 6 × 10 to ⁵ vol% of amino ethanol is added,
25 ... In the case of no addition, 26 ... 2-aminoethanol 6
When 10 × ⁵ to ⁵ vol% is added, 27 ... 2-Aminoethanol is added at 6 × 10 to ³ vol%, 28 ... When no addition is made, 29 ... Nonionic surfactant 10 to ⁷ mol / l
And when adding 1 vol% of m-aminophenol, 3
0 ... In case of no addition, 31 ... Nonionic surfactant 10 to ⁷ m
If 0.5 vol% of ol / l and formamide are added, 32 ... Without addition, 33 ... Nonionic surfactant 1
When 0 to ⁷ mol / l and 10 to ⁵ mol / l of benzylamine are added, 34 ... Ultrapure water production section, 35 ... Zeta potential control substance storage section, 36 ... Mixing amount controller, 37 ... Washing tank, 3
8 ... Si wafer transfer system.

Continuation of the front page (72) Inventor, Osamu Oka, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Hitachi, Ltd., Institute of Industrial Science (56) References JP-A-3-74845 (JP, A) JP-A-5-337351 ( JP, A) JP-A-6-41770 (JP, A) JP-A-6-84866 (JP, A) JP-A-6-132267 (JP, A) AND MAT ERIALS, TOKYO (1989) P.I. 409-412 PROCESSEDINGS, 8TH W ORKSHOP ULTRA CLEAN TECHNOLOGY, TOKYO (1990) P. 35-55 Technical Report of IEICE, 87 [397] (1988) p. 45-48 Chemical Engineering Society Kansai Branch-sponsored seminar (sponsored by the Powder Engineering Society, Powder Industry Technology Association Submicron Subcommittee), (Osaka) (1989-9-29) Niida, P. 14-25

Claims (14)

(57) [Claims] 1. A control can substance zeta potential of particles in solution (surface potential), into the solution 10- ⁷ ~25vo
A method for controlling adhesion of fine particles in a liquid, which comprises preventing or reducing the adhesion of the fine particles, which are the adsorbents, in a solution by adding at an addition concentration in the range of 1%. 2. The method for controlling adhesion of fine particles in liquid according to claim 1, wherein the substance capable of controlling the zeta potential of the fine particles in the solution is a substance having a charge distribution in the molecule (a substance having a dipole moment). 3. The method for controlling adhesion of fine particles in a liquid according to claim 1, wherein the substance capable of controlling the zeta potential of the fine particles in the solution is a substance having a hydrophilic group and a hydrophobic group in one molecule. 4. A substance capable of controlling the zeta potential of fine particles in a solution is a substance composed of a molecule having any of atoms 2 to 6 from a molecular terminal or a plurality of atoms having a negative charge distribution. The method for controlling adhesion of fine particles in liquid according to claim 1. 5. The method for controlling adhesion of fine particles in a liquid according to claim 1, wherein the substance capable of controlling the zeta potential of the fine particles in the solution is a substance which is less likely to undergo ion dissociation. 6. The substance according to claim 3, wherein the substance having a hydrophilic group and a hydrophobic group in one molecule is a substance in which a part or all of hydrogen atoms of the hydrophobic group are replaced with halogen atoms. Liquid particle adhesion control method. 7. The method for controlling adhesion of fine particles in a liquid according to claim 1, wherein the substance capable of controlling the zeta potential of the fine particles in the solution is a substance having an amino group and a hydroxyl group in one molecule. 8. The method for controlling adhesion of fine particles in liquid according to claim 1, wherein the substance capable of controlling the zeta potential of the fine particles in the solution is a substance having an amide group in one molecule. 9. The method for controlling the adhesion of fine particles in a liquid according to claim 1, wherein the substance capable of controlling the zeta potential of the fine particles in the solution is a substance having a benzene ring and an amino group in one molecule. 10. The substance having a hydrophilic group and a hydrophobic group in one molecule is a substance in which a part or all of hydrogen atoms of the hydrophobic group are replaced with nitrogen atoms. Method for controlling adhesion of fine particles in liquid. 11. The method for controlling adhesion of fine particles in a liquid according to claim 2, which is carried out by adding two or more kinds of substances having different molecular lengths. 12. Adhesion of fine particles in a liquid according to claim 1, which is carried out by adding one or more kinds of nonionic surfactants and one or more kinds of substances having a hydrophilic group and a hydrophobic group in one molecule. Control method. 13. A solution containing hydrofluoric acid, an acidic solution containing a mixed solution of hydrochloric acid and hydrogen peroxide, an alkaline solution containing a mixed solution of ammonia water and hydrogen peroxide, or a neutral solution containing ultrapure water. The method for controlling adhesion of fine particles in liquid according to claim 1, wherein 14. The method for controlling adhesion of fine particles in liquid according to claim 1, wherein the adsorbent is a compound containing an inorganic substance or an organic substance including various metals, alloys, and ceramics.