JP2000290693A - Cleaning of electronic parts and members - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clean electronic parts and members with a reduced amount of extrapure water used without arranging a heater for a cleaning solution required for cleaning by cleaning anion remaining on the cleaning surface of electronic parts and members after being washed with a chemical such as a mixed solution of sulfuric acid and a hydrogen peroxide solution by using an ozone dissolving water. SOLUTION: Anion remaining on the cleaning surface of electronic parts and members is cleaned by using an ozone dissolving water to clean the electronic parts and members. The ozone dissolving water is obtained preferably by dissolving ozone in extrapure water having <=15 μg/L hydrogen peroxide solution concentration. The ozone dissolving water has preferably 0.05-20 ppm dissolved ozone gas concentration. A finished product and half-finished goods of a silicon substrate, a semiconductor substrate such as group III-V semiconductor wafer, a substrate material such as glass substrate for liquid crystal, etc., an electronic part such as memory element, sensor element, etc., may be cited as the electronic parts and members to be an object of cleaning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning electronic parts such as a semiconductor substrate, a glass substrate, an electronic part, or a part for manufacturing the same.

[0002]

2. Description of the Related Art In the process of manufacturing electronic parts such as LSIs, it is sometimes required to make the surface extremely clean. For example, in LSI, a silicon oxide insulating film is formed on a silicon wafer, a resist layer is provided in a predetermined pattern on the silicon film, and the insulating film in a portion where the resist layer is not provided is removed by etching or the like to remove metal silicon. After the surface is cleaned and the surface is washed, a step of introducing a p-type or n-type element according to the purpose and embedding a metal wiring such as aluminum is repeated to manufacture an element. When introducing elements or embedding metal wiring, if foreign matter such as fine particles, metal, organic matter, natural oxide film, etc. adhere to the metal silicon surface, poor contact or contact resistance between the metal silicon and the metal wiring will occur. Due to the increase, the characteristics of the element may be poor. Therefore, in the LSI manufacturing process, the step of cleaning the surface of the silicon wafer is a very important step in obtaining a high-performance device, and it is necessary to remove impurities adhering to the silicon wafer as much as possible.

Conventionally, silicon wafer cleaning is performed by combining cleaning with a mixed solution of sulfuric acid and hydrogen peroxide, a mixed solution of hydrochloric acid and hydrogen peroxide, a hydrofluoric acid solution, and cleaning with ultrapure water. Organic substances, fine particles, metals, natural oxide films and the like adhering to the silicon wafer surface are removed without deteriorating the surface flatness at the atomic level. Of these, the sulfuric acid / hydrogen peroxide mixed solution is for removing organic substances and metal impurities adhering to the surface of the silicon wafer, and the hydrochloric acid / hydrogen peroxide mixed solution is used for removing the metal impurities on the silicon wafer surface. The hydrofluoric acid solution is for removing a natural oxide film on the surface of the silicon wafer.

A rinsing process carried out after the step of removing deposits with a chemical such as a mixed solution of sulfuric acid and hydrogen peroxide is for rinsing chemicals remaining on the wafer surface. , Ultrapure water usually produced by an ultrapure water production apparatus is used. In addition, in the ultrapure water cleaning step performed after the cleaning with the sulfuric acid / hydrogen peroxide mixed solution, it is not easy to remove the ions from the silicon wafer due to the high viscosity of the sulfate ions. In terms of being susceptible to contamination by metal and fine particles in the accompanying post-process, the water for rinsing is
Normally, warm ultrapure water heated to 80 ° C. or higher is used.

[0005]

However, the use of such warm ultrapure water increases the burden of thermal energy. For example, when a heating device is provided in a stage preceding the washing machine, the cost of the heating device is increased because the heating device includes auxiliary equipment such as a heating source and a temperature control system. In addition, since the installation space is unexpectedly taken, space saving cannot be achieved. Further, by providing a heating device, a higher safety management standard is required.
On the other hand, when using ultrapure water without heating, a large amount of ultrapure water is required for cleaning because the cleaning power is lower than that of warm ultrapure water. For this reason, there is a problem that the cost increases due to an increase in the amount of ultrapure water used.

Therefore, an object of the present invention is to clean the electronic component members in the step of rinsing (rinsing) the remaining anions after the step of cleaning the components with a chemical such as a mixed solution of sulfuric acid and hydrogen peroxide. It is an object of the present invention to provide a method for cleaning electronic parts and members that can reduce the amount of ultrapure water used without providing a cleaning liquid heating facility and that can perform reliable cleaning even at a low temperature.

[0007]

Under such circumstances, the present inventors have conducted intensive studies and as a result, have found that electronic component members can be mixed with a sulfuric acid / hydrogen peroxide mixed solution, hydrochloric acid / hydrogen peroxide mixed solution or hydrofluoric acid. After the step of washing with the solution, in the rinsing step of the remaining washing liquid, if ozone-dissolved water is used instead of conventionally used ultrapure water or warm ultrapure water, a heating apparatus for the washing liquid is particularly provided. The present inventors have found that the amount of pure water used can be reduced, and that cleaning can be performed reliably even at a low temperature, and the present invention has been completed.

[0008] That is, the present invention provides a method for cleaning electronic component members, characterized in that anions remaining on the cleaning surface of the electronic component members are cleaned with ozone-dissolved water. Further, according to the present invention, after the step of cleaning the electronic component members with a sulfuric acid / hydrogen peroxide solution, a hydrochloric acid / hydrogen peroxide solution or a hydrofluoric acid solution, the cleaning surface is cleaned with ozone-dissolved water. An object of the present invention is to provide a method for cleaning electronic component members, which comprises a step.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, electronic parts and members to be cleaned (also referred to as "objects to be cleaned") include:
Examples of various components and materials used in the electronic component manufacturing field and the like include, for example, silicon substrates, semiconductor substrates such as III-V semiconductor wafers, substrate materials such as glass substrates for liquid crystals, memory devices, CPUs, and sensor devices. And finished products such as electronic parts and semi-finished products thereof, parts for electronic parts manufacturing equipment such as quartz reaction tubes, cleaning tanks, substrate carriers, and the like.

According to the present invention, after cleaning electronic component members with, for example, a mixed solution of sulfuric acid and hydrogen peroxide, a mixed solution of hydrochloric acid and hydrogen peroxide or a hydrofluoric acid solution, anions remaining on the cleaning surface are dissolved in ozone. It is to be washed with water. Anions remaining on the cleaning surface include sulfate ions, nitrate ions,
Halogen ions such as chlorine ions and fluorine ions are exemplified. An example of a cleaning process for cleaning such electronic component members will be described below. (1) Sulfuric acid / hydrogen peroxide solution washing step; a mixed solution of sulfuric acid: hydrogen peroxide solution = 4: 1 (volume ratio) at 130 ° C.
Wash for 0 minutes. (2) Ozone-dissolved water washing step;
Wash for minutes. (3) Hydrofluoric acid washing step: washing with 0.5% hydrofluoric acid for 1 minute. (4) Ozone-dissolved water washing step;
Wash for minutes. (5) Ammonia / hydrogen peroxide water washing step: Washing is performed at 80 ° C. for 10 minutes with a mixed solution of ammonia: hydrogen peroxide: ultra pure water = 0.05: 1: 5 (volume ratio). (6) Ultrapure water washing step: Washing with ultrapure water for 10 minutes. (7) Hydrofluoric acid washing step: washing with 0.5% hydrofluoric acid for 1 minute. (8) Ozone-dissolved water washing step;
Wash for minutes. (9) Hydrochloric acid / hydrogen peroxide water washing step;
Wash at 0 ° C. for 10 minutes. (10) Ozone-dissolved water washing step;
Wash for 0 minutes. (11) Hydrofluoric acid washing step: washing with 0.5% hydrofluoric acid for 1 minute. (12) Ozone-dissolved water washing step;
Wash for 0 minutes. (13) Spin drying or IPA vapor drying

In the above step, the step of cleaning the electronic component members with a mixed solution of sulfuric acid / hydrogen peroxide solution, a mixed solution of hydrochloric acid / hydrogen peroxide solution or a hydrofluoric acid solution includes the steps (1), (3),
These are the steps (7), (9) and (11). The cleaning method in the step is not particularly limited, for example, a batch cleaning method in which an object to be cleaned is immersed in a cleaning liquid for cleaning, a circulating cleaning method in which the cleaning liquid is contacted with the cleaning liquid while being circulated, and a cleaning tank. Flow cleaning method in which the cleaning liquid is supplied from the bottom side and the cleaning is performed while overflowing from the top of the cleaning tank, cleaning liquid is sprayed on the object to be cleaned in a shower shape, and the cleaning liquid is sprayed on the object rotated at high speed. Washing method.

The sulfuric acid / hydrogen peroxide mixed solution, hydrochloric acid
After the object to be cleaned is cleaned with a mixed solution of hydrogen peroxide or a hydrofluoric acid, the cleaning surface where the cleaning liquid remains is cleaned with ozone-dissolved water. The steps are (2), (4), (8), (10) and (12) in the washing step. The cleaning method in this step will be described with reference to FIG. FIG. 1 shows an example of a cleaning apparatus for performing a method of cleaning electronic component members with ozone-dissolved water. In the figure, 1 is an ultrapure water production apparatus, 2 is an ozone gas dissolving tank, 3 is a cleaning tank,
Reference numeral 4 denotes an ozone generator. The cleaning device 10 is further provided with a degassing device 5 for removing gas dissolved in the ultrapure water produced by the ultrapure water production device 1 as necessary.

The ultrapure water production apparatus 1 includes, for example, a pretreatment apparatus for treating raw water, which is not shown in the figure, with a coagulation settling apparatus, a sand filtration apparatus, and an activated carbon filtration apparatus, and a reverse osmosis membrane apparatus, Bed 3 tower ion exchanger, mixed bed ion exchanger,
Primary pure water production equipment that obtains primary pure water by processing with a precision filter, UV irradiation on the primary pure water, mixed bed polisher,
The apparatus is provided with a secondary pure water production device that performs an ultrafiltration membrane treatment to remove fine particles, colloidal substances, organic substances, metal ions, anions and the like remaining in the primary pure water.

The ultrapure water produced by the ultrapure water production apparatus 1 preferably has, for example, the following water quality. That is, the electric resistivity is 18.0 MΩ · cm or more, the total organic carbon is 10 μgC / L or less, the number of fine particles having a particle size of 0.07 μm or more is 10 / ml or less, the number of viable bacteria is 10 / L or less, and the silica is 1 μgS
iO ₂ / L or less, sodium 0.01 μg Na / L or less, iron 0.
01 μg Fe / L or less, copper 0.01 μg Cu / L or less, chloride ion 0.01 μg Cl / L or less, hydrogen ion concentration (pH)
7. It has a hydrogen peroxide concentration of 15 μg / l or less. Among them, the concentration of hydrogen peroxide is preferably set to 15 μg / l or less, because ozone water obtained by dissolving ozone in ultrapure water is suppressed from self-decomposition and its life is significantly extended. As a method for reducing the concentration of hydrogen peroxide in ultrapure water to 15 μg / l or less, a method in which ultrapure water is not subjected to ultraviolet irradiation in the process of producing ultrapure water, even if it is subjected to ultraviolet irradiation, A method of adsorbing or decomposing hydrogen peroxide, a method of decomposing with a palladium-supported carrier ion exchange resin or a metal ion type cation exchange resin, and the like can be given.

The ultrapure water produced by the ultrapure water producing apparatus 1 is dissolved in the ozone gas dissolving tank 2 in the ozone gas dissolving tank 2. It is preferable to remove them. Degassing device 5
In particular, it is preferable to remove oxygen gas, nitrogen gas, and carbon dioxide gas dissolved in ultrapure water, and the dissolved gas concentration of one or a combination of two or more thereof is 10 p.
It is preferable to degas so as to be less than pm, preferably 2 ppm or less. The dissolved gas concentration is 10p
When the pressure is equal to or more than pm, air bubbles are generated at the time of cleaning, the air bubbles adhere to the object to be cleaned, and the cleaning effect on the portion where the air bubbles are adhered tends to decrease. In the degassing device 5, as a method for degassing the dissolved gas in the ultrapure water, a method of vacuum degassing via a gas permeable membrane is preferable.

The ozone gas is dissolved in the ozone gas dissolving tank 2 in the ultrapure water from which the dissolved gas dissolved in the degassing device 5 is degassed. The cleaning liquid obtained by dissolving ozone gas in ultrapure water in the ozone gas dissolving tank 2 is a positive oxidation suitable for removing sulfate ions, for example, of a mixed solution of sulfuric acid and hydrogen peroxide, remaining on the surface of electronic component members. A cleaning solution having a reduction potential can be used.
° C, 1-20 atm, 0.05-20ppm, especially 3-10ppm
Preferably, the ozone gas is dissolved so that
If the ozone dissolution concentration exceeds 20 ppm, it is not appropriate because it causes deterioration of liquid contact parts such as piping.

The method for dissolving ozone gas in ultrapure water is not particularly limited. A film dissolving method in which ozone gas is injected into ultrapure water through a gas permeable membrane to dissolve the ozone gas, and ozone gas is bubbled into ultrapure water. Dissolving ozone gas in ultrapure water via an ejector,
A method of supplying ozone gas to the upstream side of a pump for supplying ultrapure water to the gas dissolving tank and dissolving the ozone gas by stirring in the pump may be used. As the gas permeable film used for the film dissolution, a fluororesin-based hydrophobic porous film that can withstand the strong oxidizing power of ozone is suitable, but is not limited to this. Examples of the ozone generator include an ozone generator using a silent discharge, an electrolytic method, or the like.

The ozone-dissolved water in which the ozone gas is dissolved in the ozone gas dissolving tank 2 is sent to the cleaning tank 3. As a method of cleaning the object to be cleaned in the cleaning tank 3 with the ozone-dissolved water, the same method as in the case of the chemical cleaning of the sulfuric acid / hydrogen peroxide mixed solution or the like can be used. A washing method by immersing the ozone-dissolved water in the washing tank, a circulating washing method in which the ozone-dissolved water is circulated and brought into contact with the liquid to be washed, and the ozone-dissolved water is supplied from the bottom side of the washing tank and overflowed from the top of the washing tank. A flow cleaning method for washing, a method of spraying ozone-dissolved water on an object to be washed in a shower shape, and a method of spraying ozone-dissolved water on an object to be washed rotated at a high speed for washing are exemplified.

A heater may be provided in the cleaning tank 3 to adjust the temperature of the ozone-dissolved water as required. It is more preferable to adjust the temperature of the ozone-dissolved water to 20 to 80 ° C. for cleaning. This is preferable in that a cleaning effect can be obtained. As described above, the cleaning time for cleaning the object to be cleaned with ozone-dissolved water is not particularly limited, but is, for example, 3 to 20 minutes.
Preferably, it is 5 to 10 minutes.

In the present invention, electronic parts and members are described as examples.
For example, sulfuric acid / hydrogen peroxide mixed solution, hydrochloric acid / hydrogen peroxide
After washing with a chemical such as a mixed solution or hydrofluoric acid solution, ozone
Rinse with dissolved water to leave on the cleaning surface
Sulfate ion, chloride ion and fluoride ion etc.
Of anions such as halogen ions from water into ozone-dissolved water
And the oxidizing power of ozone-dissolved water, for example,
Degree 1 × 10¹¹atoms / cm ^TwoIt can be reliably removed to the extent. Ma
In addition, there is no special need
The amount of water used can be reduced.

[0021]

Next, the present invention will be described more specifically with reference to examples. (Cleaning Apparatus) FIG. 2 is a schematic flow chart showing the configuration of a cleaning apparatus for performing the cleaning method of the present invention. 2, the same components as those of FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Only different points will be described. That is, FIG.
, Reference numerals 12 to 23 denote respective cleaning tanks and rinsing tanks constituting the batch-type silicon wafer cleaning apparatus, and among these tanks, 12 is a cleaning tank using a sulfuric acid / hydrogen peroxide mixed cleaning liquid; Reference numerals 18 and 22 denote cleaning tanks using a hydrofluoric acid solution as a cleaning liquid, reference numeral 20 denotes a cleaning tank using a hydrochloric acid / hydrogen peroxide mixed cleaning liquid, and reference numeral 16 denotes a cleaning tank using an ammonia / hydrogen peroxide mixed cleaning liquid. At the subsequent stage of each of the tanks, a rinsing tank 13, 15, 19, 21, 23 using ozone-dissolved water and a rinsing tank 17 using ultrapure water are provided, respectively. The ozone-dissolved water from the ozone-dissolved water producing apparatus 10a is distributed to the rinsing tanks 13, 15, 19, 21, and 23, and the rinsing tanks 1
To 7 is supplied water degassed from ultrapure water by a degassing device 5.

The silicon wafer 11 is sequentially transported through the tanks 12 to 23 arranged as described above as indicated by arrows in the figure, and sequentially removes organic substances, removes fine particles, removes adhered metals, and performs the subsequent steps of each cleaning step. The cleaning process for removing the oxide film using a hydrofluoric acid solution is performed, and finally, the wafer is transferred to the spin dryer 24 to be dried.

Embodiments 1 and 2 (Ultra pure water) In this embodiment, ultra pure water is obtained by coagulating and separating raw water from a coagulated sedimentation treatment apparatus, a reverse osmosis membrane treatment apparatus, a two-bed three-column ion exchange treatment apparatus, and a mixed-bed type. An ion exchange treatment device, a primary pure water production device that produces primary pure water by passing through a membrane treatment device using a precision filter, and then the primary pure water is further passed through a mixed-bed polisher and an ultrafiltration device to remove ultrapure water. It was manufactured from the ultrapure water production apparatus 1 including the secondary pure water production apparatus to be produced (both are not shown in the drawings), and the water quality was as described above.

A silicon wafer 11 having a size of 6 inches was washed by an overflow method in a washing tank 12 at 130 ° C. for 10 minutes. In the overflow cleaning, a cleaning tank capable of overflowing the cleaning liquid is used. The silicon wafer is stopped in the cleaning tank, and the cleaning liquid is supplied at a linear flow rate of 5 m /.
The washing process was performed while overflowing at h. The cleaning liquid used in the cleaning tank 12 includes sulfuric acid: hydrogen peroxide solution = 4:
A mixed solution of 1 (volume ratio) was used. Next, the washed silicon wafer 11 was transferred to a rinsing tank 13 and subjected to a rinsing process at room temperature or at a temperature of 80 ° C. Rinse tank 13
The ozone-dissolved water used in (5) was obtained by using an electrolytic ozone generator.
Was dissolved and produced. The rinsing treatment was performed by the same overflow method as described above using ozone-dissolved water. That is, a rinsing tank capable of overflowing was used, the silicon wafer was kept stationary in the tank, and the rinsing treatment was performed while the amount of the ozone dissolved water overflowed at a linear flow rate of 5 m / h for 5 minutes or 10 minutes. After the rinsing process, the residual ion concentration was measured on the cleaned surface of the silicon wafer. The measurement was performed by hot water extraction ion chromatography. Table 1 shows the results.

Comparative Example 1 The same procedure as in Example 1 was carried out except that ultrapure water was used instead of the ozone-dissolved water. Table 1 shows the results.

[0026]

[Table 1]

[0027]

According to the present invention, after the step of cleaning the electronic component members with a chemical such as a sulfuric acid / hydrogen peroxide mixed solution, the cleaning liquid containing the remaining anions is sufficiently washed with low-temperature ozone-dissolved water. Can be washed. For this reason, the amount of electricity used and the cost of auxiliary facilities can be reduced without providing a cleaning liquid heating facility as in the related art. Further, since the cleaning efficiency is improved, the rinsing time can be shortened, and the amount of pure water used can be reduced. Further, productivity is improved by shortening the time of the cleaning step.

[Brief description of the drawings]

FIG. 1 is a schematic flow chart showing the configuration of a cleaning apparatus for cleaning electronic component members of the present invention with ozone-dissolved water.

FIG. 2 is a schematic flow chart showing a configuration of a cleaning apparatus for performing the cleaning method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrapure water production apparatus 2 Ozone gas dissolving tank 3 Cleaning tank 4 Ozone generator 5 Degassing apparatus 10 Electronic component member cleaning apparatus 11 Silicon wafer 12-23 Cleaning tank or rinsing tank 24 Spin dryer

Claims (4)

[Claims] 1. A method for cleaning electronic component members, wherein anions remaining on the cleaning surface of the electronic component members are cleaned with ozone-dissolved water. 2. A process of cleaning electronic component members with a mixed solution of sulfuric acid and hydrogen peroxide, a mixed solution of hydrochloric acid and hydrogen peroxide or a hydrofluoric acid solution, and then cleaning the cleaning surface with ozone-dissolved water. And a method for cleaning electronic component members. 3. The ozone-dissolved water has a hydrogen peroxide concentration of 1
3. The method according to claim 1, wherein ozone is dissolved in ultrapure water having a water quality of 5 μg / L or less. 4. The ozone-dissolved water has a dissolved ozone gas concentration of 0.05 to 20 ppm.
4. The method for cleaning electronic component members according to claim 3.