JP2003313584A - Detergent composition - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To maintain the smoothness of a wafer with a high etching amount,
Just by suppressing the residual surfactant on the wafer surface
Cleaning of silicon wafers, etc.
To provide a cleaning composition for dense parts. SOLUTION: General formula (1): RO- (AO)_n− (C
H_Two)_mCOOX [wherein R is also a straight chain having 1 to 18 carbon atoms.
Or a branched chain alkyl group or an alkyl having 2 to 18 carbon atoms.
AO represents an ethyleneoxy group and / or
X represents a hydrogen atom or an alkali metal atom;
Child, [NR '_Four]⁺(However, R 'is an alkyl having 1 to 3 carbon atoms.
Represents a kill group, and four R's may be the same or different
No. ) Or [HNR " _Three]⁺(Where R ″ is a hydrogen atom,
Or a carbon having 1 to 10 carbons which may be substituted by an OH group
A hydrogen group, and three R ″ s may be the same or different
Good. ), N represents 0 to 50, and m represents 1 to 3. ]
Detergent composition for precision parts containing the compound represented by
object.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cleaning composition for precision parts. More specifically, it relates to a cleaning composition for precision parts such as metal parts, electronic parts, semiconductor parts, silicon wafers and liquid crystal panels.

[0002]

2. Description of the Related Art A silicon semiconductor wafer is processed by lapping, etching and polishing a thin plate obtained by pulling a silicon crystal ingot and then cutting the ingot. In recent years, as the degree of integration of devices has been improved, the silicon wafer required for LSI has been required to have extremely high accuracy.

For example, a wafer processed with high accuracy by lapping has a work-affected layer on its surface, and therefore an etching process for chemically removing these layers is performed. It is desired to maintain the etching process.

However, not only the oil used for lapping, the abrasive grains or their composites remain on the wafer surface after lapping, but also these contaminants remain inside the fine cracks in the lapping marks. ing. If general acid etching is carried out with a mixed acid solution of hydrofluoric acid / nitric acid / acetic acid / pure water without sufficient removal of these, the etching ability is hindered by the oil film of the above residue, and uniform etching proceeds. However, the precision of the surface property and flatness will deteriorate.

Therefore, an alkali cleaning step is generally used to remove the dirt remaining on the wafer after lapping while etching silicon under alkali such as NaOH or KOH. However, when etching is performed with an aqueous solution containing only an alkali, unevenness derived from the crystal anisotropic etching of silicon occurs on the wafer surface.
There is a demand for a cleaning solution that not only removes oil and dirt on abrasive grains but also suppresses anisotropic crystal anisotropic etching and maintains the smoothness of the wafer.

In addition, in the alkaline cleaning step, the temperature of the cleaning liquid is raised to perform the cleaning in order to increase the etching amount. As the cleaning agent used in this cleaning solution, a nonionic surfactant is often used, but as the temperature is raised, a clouding phenomenon occurs in the cleaning solution, and when the alkali concentration rises, this clouding phenomenon occurs. The resulting temperature tends to drop. In the present invention, the temperature at which the white turbidity phenomenon occurs in the cleaning liquid is called the white turbidity point. When a silicon wafer is dipped and washed in this cloudy cleaning liquid and the wafer is pulled up, the cloudy nonionic surfactant is excessively adsorbed on the surface and remains as a cleaning agent stain on the wafer surface.

Furthermore, when this washing operation is repeated,
Since the nonionic surfactant is taken out of the cleaning liquid tank and the concentration of the nonionic surfactant in the cleaning component gradually decreases, there is a problem that the cleaning power gradually decreases.

Japanese Patent Laid-Open No. 2001-40389 discloses that
Although a cleaning solution for a silicon wafer having a low etching rate which is an alkaline aqueous solution containing a surfactant is disclosed, the disclosed etching amount of this cleaning solution is low,
It cannot be said that it is at a practical level.

[0009]

SUMMARY OF THE INVENTION The present invention is a silicon wafer which not only keeps the smoothness of the wafer with a high etching amount and suppresses the surfactant from remaining on the wafer surface, but also has a long-lasting cleaning effect. It is an object of the present invention to provide a cleaning composition for precision parts such as.

[0010]

The inventors of the present invention have used a cleaning composition containing a specific compound to control anisotropic etching of a wafer under an alkaline condition while controlling the anisotropic etching of the wafer at a high etching amount. The smoothness can be maintained, the oil on the wafer can be removed, and when used in combination with a nonionic surfactant, the nonionic surfactant remains on the surface of the wafer and the cleaning effect is also achieved. I found that it can be maintained for a long time.

That is, the present invention provides a compound represented by the general formula (1): R—O— (AO) _n — (CH ₂ ) _m COOX (1) [wherein, R is a straight chain or branched chain having 1 to 18 carbon atoms] Represents an alkyl group or an alkenyl group having 2 to 18 carbon atoms,
O represents an ethyleneoxy group and / or a propyleneoxy group, X represents a hydrogen atom, an alkali metal atom, [NR ′ ₄ ].
⁺ (However, R'represents an alkyl group having 1 to 3 carbon atoms,
The R's may be the same or different. ) Or [HN
R ″ ₃ ] ⁺ (wherein R ″ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with an OH group,
3 R ″ may be the same or different.),
n represents 0 to 50 and m represents 1 to 3. ] It is related with the cleaning composition for precision parts containing the compound shown by these.

[0012]

For precision parts cleaning composition of the embodiment of the present invention (hereinafter, the detergent composition) of the general formula (1): R-O- ( AO) n - (CH 2) m COOX (1 In the formula, R represents a linear or branched alkyl group having 1 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, and A
O represents an ethyleneoxy group and / or a propyleneoxy group, X represents a hydrogen atom, an alkali metal atom, [NR ′ ₄ ].
⁺ (However, R'represents an alkyl group having 1 to 3 carbon atoms,
The R's may be the same or different. ) Or [HN
R ″ ₃ ] ⁺ (wherein R ″ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with an OH group,
3 R ″ may be the same or different.),
n represents 0 to 50 and m represents 1 to 3. ] It is what contains the compound shown by these.

In the general formula (1), the carbon number of R is 1
From the viewpoint of maintaining the smoothness of the wafer surface, 4 or more is preferable, and from the viewpoint of increasing the etching amount while maintaining the smoothness, 16 or less is preferable.

Examples of AO in the general formula (1) include ethyleneoxy group and propyleneoxy group, and these alkyleneoxy groups may be used alone or in combination of two kinds. When used in combination, the (AO) _n portion may be random or block. As the alkyleneoxy group, an ethyleneoxy group alone is preferable from the viewpoint of water solubility.

In the general formula (1), n is 0 to 50, but is preferably 3 to 30 from the viewpoint of water solubility. m is
Although it is 1 to 3, 1 or 2 is preferable from the viewpoint of ease of production.

X is a hydrogen atom, an alkali metal atom, [N
R ’_Four]⁺Or [HNR ”₃]⁺But specifically
Is an alkali metal atom such as sodium or potassium
Is mentioned. [NR '_Four]⁺As tetramethyla
Examples include ammonium and the like. [HNR]₃]⁺As
Is [NH_Four]⁺And NR "₃Is dimethylamine,
Trimethylamine, diethylamine, triethylami
Amine, dibutylamine, octylamine, 2-ethylhexyl
Alkylamines such as silamine, monoethanolamine
Amine, diethanolamine, triethanolamine, methyl
Leethanolamine, methyldiethanolamine, dime
Cylethanolamine, monopropanolamine, dip
Lopanolamine, tripropanolamine, methyl
Lopanolamine, Methyldipropanolamine, Ami
When it is an alkanolamine such as noethanolamine
It can be combined. Among these, X is hydrogen source
Child, sodium, potassium, [NH_Four]⁺, [H₂NC
H₂CH₂OH]⁺And [HN (CH ₃)₂CH₂CH
₂OH]⁺Is preferred.

Specific examples of the compound represented by the general formula (1) include polyoxyethylene butyl ether acetic acid, polyoxyethylene hexyl ether acetic acid, polyoxyethylene octyl ether acetic acid, polyoxyethylene lauryl ether acetic acid, polyoxyethylene myristyl ether. Acetic acid, polyoxyethylene butyl ether propionic acid, polyoxyethylene hexyl ether propionic acid, polyoxyethylene octyl ether propionic acid, polyoxyethylene lauryl ether propionic acid, polyoxyethylene myristyl ether propionic acid, etc. and their sodium salts, potassium salts, Ammonium salts, tetramethylammonium salts, monoethanolamine salts, dimethylethanolamine salts and the like,
Preferably polyoxyethylene hexyl ether acetic acid,
Examples thereof include polyoxyethylene octyl ether acetic acid, polyoxyethylene lauryl ether acetic acid, polyoxyethylene myristyl ether acetic acid, and their sodium salts, potassium salts, and ammonium salts.

The cleaning composition of the present invention preferably further contains a nonionic surfactant from the viewpoint of more efficiently removing oil stains on the wafer after lapping.

Examples of such nonionic surfactants are compounds obtained by adding ethylene oxide and / or propylene oxide to a linear or branched saturated or unsaturated alcohol having a hydrocarbon group having 6 to 22 carbon atoms. ,
A compound obtained by adding ethylene oxide and / or propylene oxide to a linear or branched, saturated or unsaturated amine having a hydrocarbon group having 6 to 22 carbon atoms, and having 6 carbon atoms.
To 22 fatty acid to which ethylene oxide and / or propylene oxide are added, unsaturated polyhydric alcohol having 2 to 10 carbon atoms to which ethylene oxide and / or propylene oxide are added, and 2 carbon atoms
A compound obtained by adding ethylene oxide and / or propylene oxide to a polyamine of 10 to 10, a carbon number of 2 to 1
Compounds obtained by adding ethylene oxide and / or propylene oxide to polyvalent fatty acid of 0, compounds obtained by adding ethylene oxide and / or propylene oxide to alkylphenols, compounds obtained by adding ethylene oxide and / or propylene oxide to styrenated phenol , A compound in which ethylene oxide and / or propylene oxide is added to benzylated phenol, and a compound in which ethylene oxide and / or propylene oxide is added to naphthol.

Preferred nonionic surfactants include:
It is a compound in which ethylene oxide and / or propylene oxide is added to a linear or branched saturated or unsaturated alcohol having a hydrocarbon group having 6 to 22 carbon atoms, and the carbon number of the hydrocarbon group is the surface of the wafer. 8 or more is preferable from the viewpoint of the property, and 18 from the viewpoint of the etching rate.
The following are preferred. Further, from the viewpoint of reducing the cleaning agent stain on the wafer, the carbon number is preferably 6 to 20, and 4 to 18
Is more preferable.

The hydrocarbon group of the nonionic surfactant may be linear or branched, but is preferably a branched chain from the viewpoint of setting the cloud point to a higher temperature, and the carbon of the hydrocarbon group. The number is preferably 7 to 18, more preferably 10 to 14, and particularly preferably 12 to 14.

The ethylene oxide and / or propylene oxide may be used alone or in combination. When mixed and used, ethylene oxide and propylene oxide may be randomly contained,
Although it may be contained in a block, ethylene oxide alone is more preferable from the viewpoint of setting the cloud point higher than the cleaning temperature. The number of added moles is preferably 3 to 80, but from the viewpoint of setting the cloud point higher than the washing temperature, it is 10
It is preferably -50 mol, more preferably 10-30 mol.

Specific examples of the nonionic surfactant include hexanol, 2-ethylhexanol, octanol, decanol, dodecanol, 2-butyloctanol, isodecanol, tridecanol, tetradecanol, octadecanol, oleyl alcohol, Examples thereof include those obtained by adding ethylene oxide and / or propylene oxide to a mixture of secondary alcohols obtained by introducing an OH group into the -CH2- group of ₂ -hexyldecanol or n-paraffin.

The balance of the detergent composition of the present invention is water.
Examples of water include ion-exchanged water and pure water.

The cleaning composition of the present invention contains an inorganic acid, an organic acid, NaOH,
You may mix | blend pH adjusting agents, such as KOH, ammonia water, and an organic amine, and additives, such as a silicon type antifoaming agent, a chelating agent, alcohols, glycol ethers, a preservative, and an antioxidant.

The detergent composition of the present invention is prepared by appropriately adding and mixing the compound represented by the general formula (1), water, and if necessary, the nonionic surfactant and other additives. Obtainable.

The content of the compound represented by the general formula (1) in the detergent composition is preferably 0.01 to 50% by weight,
It is more preferably 0.1 to 20% by weight, and particularly preferably 0.1 to 5% by weight.

The content of nonionic surfactant is 0.0
1 to 40% by weight is preferable, and 0.1 to 2 is more preferable.
It is 0% by weight.

The total amount of the compound represented by the general formula (1) and the nonionic surfactant in the detergent composition is 0.0
2 to 50% by weight is preferable, and 0.2 to 3 is more preferable.
It is 0% by weight.

The compounding ratio of the compound represented by the general formula (1) and the nonionic surfactant in the detergent composition (weight ratio,
The compound represented by the general formula (1) / nonionic surfactant) is preferably 100/0 to 5/100. From the viewpoint of increasing the etching amount by using the nonionic surfactant in a uniformly dissolved state, the blending ratio is 100/0.
-20/100 is more preferable.

The concentration of each component in the cleaning liquid composition is a preferable concentration for cleaning, but it may be a concentration at the time of producing the composition. Usually, the composition is produced as a concentrated solution, and it is often used by diluting the composition.

The detergent composition of the present invention thus obtained is, for example, a stain mainly composed of organic substances existing on the surface of a metal component, an electronic component, a semiconductor component, a silicon wafer or the like, or a liquid crystal stain such as a liquid crystal panel. However, it is particularly preferably used for cleaning the silicon wafer in the silicon wafer manufacturing process. For example, it can be preferably used in a cleaning process after a slicing process of a silicon wafer, a lapping process and a polishing process, and an alkaline etching process of an etching process for removing a work-affected layer.

Above all, it is preferable to use the cleaning composition of the present invention in a step of using it under an alkali, and a step of cleaning dirt in a polishing step called lapping (so-called,
It is particularly preferable to use it in the washing step after lapping).

When used in the cleaning step after lapping as described above, the cleaning composition for cleaning after lapping is prepared by blending the cleaning composition of the present invention in an alkaline aqueous solution. As the alkali source, NaOH, KOH, TMAH, aqueous ammonia, amine or the like is used. Further, particularly preferable alkalis include NaOH, KOH and TMAH.

The alkali concentration of the cleaning liquid for cleaning after the lapping is preferably 0.01 to 60% by weight in the cleaning liquid. From the viewpoint of washing in a uniformly dissolved state by using a nonionic surfactant in combination, the content is more preferably 0.1 to 40% by weight, still more preferably 0.1 to 10% by weight.

In the preparation of the cleaning liquid used in the cleaning step after lapping, the content of various components in the cleaning composition of the present invention may be within the above range. In addition, a cleaning composition is prepared in advance so that various components have high concentrations,
Then, at the time of use, it may be mixed with an aqueous solution containing an alkali source so as to have predetermined concentrations of various components. In this case, the concentration of the cleaning composition of the present invention in the cleaning liquid used in the cleaning step after lapping is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight.

When the cleaning composition of the present invention is used for cleaning, the temperature condition is preferably 0 to 100 ° C., and from the viewpoint of increasing the amount of alkali etching of the silicon wafer to a suitable amount, the temperature is 30 to 30 ° C. 100 ° C. is more preferable. Further, from the viewpoint of maintaining a uniformly dissolved state of the detergent component, 50 to 90 ° C. is preferable, and 60 to 9 is particularly preferable.
0 ° C is preferred.

The silicon wafer obtained as described above has less crystal anisotropic etching, is excellent in smoothness,
The residual nonionic surfactant on the wafer surface is suppressed. Moreover, the cleaning composition of the present invention can maintain the cleaning effect even when continuously used without replacement,
The effect that economically excellent cleaning can be performed is exhibited.

[0039]

EXAMPLE In a 300 ml beaker, NaOH, Table 1
The compound represented by the general formula (1) described in 1 above and the nonionic surfactant described in Table 2 are added so as to have the composition described in Table 3, and the washing liquid is made up to 100 parts by weight in total with pure water. Prepared. The washing solution was heated to 80 ° C.
Then, a 2-inch silicon wafer having a (100) plane lapped was dipped for 30 minutes, pulled up, thoroughly washed with pure water, and blow-dried. Regarding the cleaning performance of the cleaning liquid,
The following items were evaluated. The results are shown in Table 4.

1. Measurement of Etching Amount of Wafer After the lapping, the amount of reduction in plate thickness was obtained from the rate of weight change before and after immersion of the wafer to obtain the etching amount.

2. Observation of Wafer Surface The surface of the wafer used for the etching test was observed with a scanning electron microscope (SEM) (1000 times) to examine the smoothness of the wafer after lapping. If only cracks due to lapping and polishing are observed on the surface, smoothness is maintained, wafer smoothness is ○, and if pyramid-shaped protrusions due to anisotropic etching are observed, wafer smoothness is maintained. Is x.

3. Measurement of cloud point The cloud point was measured based on the cloud point measurement described in ASTM D2024. Into a 150 mL beaker, the nonionic surfactant, NaOH, and the ion-exchanged water at 30 ° C. or less in the amounts shown in Examples 5 to 6 and Comparative Examples 2 to 3 were weighed out so that the total amount was 100 g, and dissolved. Stir well until Add this solution to a 200 mm test tube.
Pour to 0 ± 5 mL and place in a water bath. The mixture was stirred with a thermometer, and at the time when cloudiness could be visually confirmed, the test tube was taken out of the water bath and cooled with stirring with a thermometer, and the temperature at which the solution became transparent was taken as the cloud point.

4. Observation of Silicon Wafer Blemishes The cleaning liquids obtained in Examples 5 to 6 and Comparative Examples 1 to 80 were used.
After adjusting the temperature to around 0 ° C., the wafer was soaked for 1 minute after being lapped for 2 inches, then pulled up, and allowed to stand at room temperature as it is, and the residual surfactant (cleaning agent stain) on the surface of the wafer was visually observed. .

5. Confirmation of carried-out amount of surfactant The cleaning liquids obtained in Examples 5 to 6 and Comparative Examples 1 to 80 were used.
After adjusting the temperature to around 0 ° C., three wafers after lapping of 2 inches are immersed for 1 minute, and then slowly pulled up. This operation was repeated 5 times. The surfactant concentration in the cleaning liquid before dipping the wafer and after dipping 5 times was measured by the total organic carbon meter (TOC-5).
00 Shimadzu Corporation). Regarding the change in concentration, the surfactant concentration before immersion in the wafer was set to 1 and the surfactant concentration after immersion was shown in relative values.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

[Table 4]

From the results shown in Table 4, the cleaning liquids obtained in Examples 1 to 6 had a larger etching amount than those of Comparative Examples 2 and 3 and could maintain the smoothness of the wafer.

In the case of Examples 5 to 6 in which the nonionic surfactant and the compound of the general formula (1) are used in combination, the nonionic surface active agent is added by using the compound of the general formula (1) in combination. The cloudiness point of the cleaning liquid derived from the cloud point of the agent is 7
It was possible to raise the temperature above 5 ° C. Washing is usually 6
Since it is carried out in the vicinity of 0 to 80 ° C., it can be understood that the cleaning liquid having a high clouding point as described above hardly causes clouding. In addition, as a result, it is found that the generation of spots on the wafer is suppressed and the carry-out of the nonionic surfactant from the cleaning liquid tank is suppressed.

[0051]

The cleaning composition for a silicon wafer according to the present invention is applied to any step of a silicon wafer manufacturing process, for example,
By using it for the slicing of silicon wafers, the cleaning process after lapping and polishing processes, and the alkaline etching process for removing the process-affected layer, smoothness is maintained even with a high etching amount, and surface activity on the wafer surface is maintained. It is possible to economically manufacture a silicon wafer in which residual agent is suppressed.

Claims (4)

[Claims] 1. General formula (1): R—O— (AO) _n — (CH ₂ ) _m COOX (1) [In the formula, R is a linear or branched alkyl group having 1 to 18 carbon atoms or Represents an alkenyl group having 2 to 18 carbon atoms, A
O represents an ethyleneoxy group and / or a propyleneoxy group, X represents a hydrogen atom, an alkali metal atom, [NR ′ ₄ ].
⁺ (However, R'represents an alkyl group having 1 to 3 carbon atoms,
The R's may be the same or different. ) Or [HN
R ″ ₃ ] ⁺ (wherein R ″ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with an OH group,
3 R ″ may be the same or different.),
n represents 0 to 50 and m represents 1 to 3. ] The cleaning composition for precision parts containing the compound shown by these. 2. The cleaning composition according to claim 1, further comprising a nonionic surfactant. 3. A cleaning method for a silicon wafer.
Or the cleaning composition according to 2. 4. The cleaning composition according to claim 1, which is used in a cleaning step after lapping in a silicon wafer manufacturing step.