JPH1128431A - Method for washing substrate and production of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To the wash both surfaces of a substrate without damaging the substrate by rotating washing liquid by the rotation of a washing liquid receiver and immersing and holding the substrate in the washing liquid. SOLUTION: The washing liquid 6 is supplied from a supply section 2 of the washing liquid receiver 1. A wafer 4 is then held by a holder 5 and is lowered in the washing liquid receiver 1, by which its entire surface is immersed into the washing liquid 6. The washing liquid receiver 1 is then rotated, by which washing is executed. The washing liquid 6 is repetitively stirred and circulated by rotation of the washing liquid receiver 1 and the effective washing is thus executed. The rotation of the washing liquid receiver 1 is stopped after the end of the washing. The washing liquid is then discharged. Pure water is supplied in turn and the wafer is washed with water by rotating the washing liquid receiver 1. A series of the actions may be executed without stopping the rotation. The wafer holder 5 is risen and rotated after the end of the washing with the water to splash the adhered water and to dry the wafer 4. The drying of the water by supplying gaseous nitrogen into the washing liquid receiver 1 is equally well. The wafer 4 is thus washed effectively without the damage.

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 articles in a manufacturing process of electronic materials, magnetic materials, optical materials, ceramics and the like.

[0002]

2. Description of the Related Art Semiconductor wafers, glass square substrates for liquid crystals,
There are the following conventional methods for supplying a cleaning liquid or the like to a substrate such as a color filter substrate to perform a cleaning process on the substrate.

There is a batch type process in which several wafers are inserted into a cassette and immersed in a cleaning solution or an etching solution to perform a large number of cleanings at once. Regarding this, for example,
No. 7-245290.

In the conventional single-wafer processing for performing one-by-one cleaning, a substrate is held horizontally and a rotatable spin chuck and a cleaning liquid for supplying a cleaning liquid to the substrate held by the spin chuck are provided. It has a jet nozzle. In such an apparatus, a cleaning liquid is supplied from an ejection nozzle to the surface of a substrate while rotating the substrate while holding the substrate on a spin chuck, thereby cleaning the surface of the substrate. This is described in, for example, JP-A-7-297160.

[0005]

With the increase in the degree of integration of an integrated circuit formed on a semiconductor surface, the next 256
The minimum processing size in MDRAM is 0.2 μm,
Accordingly, it is considered that it is necessary to reduce the size of fine particles to be cleaned and to remove fine particles of 0.02 μm.

[0006] As the fine particles are miniaturized, the number of particles present in the atmosphere increases, and 0.02 µm fine particles are present several times more than the current 0.03 µm fine particles (64M DRAM). Further, it is considered that the finer the fine particles are, the more likely they are to adhere to the substrate, and it can be said that the necessity of the fine particle cleaning technology is increasing.

However, in the batch type cleaning, a large number of wafers are cleaned at one time, and at the same time, these wafers may become a source of contamination and recontaminate other wafers.

In the conventional rotary type single wafer cleaning, when a rectangular substrate is held on a spin chuck, the substrate is placed on a plurality of support pins provided on the upper surface of the spin chuck, and the substrate is further rotated. The two corner portions are supported by a pair of positioning pins. However, when the size of the substrate is increased, when the substrate is rotated at a high speed while holding the vicinity of the substrate with positioning pins, a large force is applied to the vicinity of the substrate corner, and the substrate corner may be damaged. In addition, an apparatus has been proposed in which the center of the lower surface of the substrate is vacuum-adsorbed and cleaned while rotating at a high speed. There is. This is described in JP-A-7-297159.
No.

An object of the present invention is to provide a substrate cleaning apparatus and a substrate cleaning method capable of satisfactorily cleaning both surfaces of a substrate without damaging the substrate such as a semiconductor wafer. Another object of the present invention is to provide a substrate cleaning method capable of reducing cleaning unevenness due to rebound of a cleaning liquid on a substrate surface and further reducing consumption of the cleaning liquid as compared with the conventional apparatus.

[0010]

A substrate cleaning method according to the present invention is for cleaning a substrate surface, and includes a cleaning liquid receiver having a free rotation mechanism, a substrate holder for holding a substrate, and a cleaning liquid supply means. It can be carried out by an apparatus provided with Further, it is preferable that the apparatus further includes a rotation mechanism for rotating the substrate holding unit and a gas supply unit for drying the substrate.

According to the present invention, since the wafer holder is not rotated, cleaning can be performed without applying a load to the wafer. Therefore, it is possible to suppress the impact applied to the semiconductor wafer even when cleaning the large semiconductor wafer. At the same time, by using this cleaning method, more high-quality semiconductors can be manufactured than before, and the yield can be improved.

FIG. 1 shows a conceptual diagram of the present invention. FIG.
FIG. 1 shows a schematic view of the stirring mechanism of the present invention.

A supply section 2 is provided at the center of the lower portion of the cleaning liquid receiver 1, and the supply section 2 is connected to cleaning liquid supply means, pure water supply means and gas supply means. In the washing liquid receiver 1,
A circulation mechanism and a stirring mechanism 3 are provided. Above the cleaning liquid receiver 1, a wafer holder 5 for holding the wafer 4 is arranged.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A procedure for cleaning a wafer 4 using the cleaning apparatus of the present invention having the above structure will be described below.

First, the cleaning liquid 6 is supplied from the supply unit 2 of the cleaning liquid receiver 1.
Supply. Next, the wafer 4 is lowered using the holder 5 and the entire surface to be cleaned is immersed in the cleaning liquid 6. The cleaning is performed by rotating the cleaning liquid receiver 1. While the cleaning liquid receiver 1 is rotating, the cleaning liquid 6 in the cleaning liquid receiver is agitated and circulated, so that cleaning is effectively performed.

When the cleaning with the cleaning liquid is completed, the rotation of the cleaning liquid receiver 1 is stopped and the cleaning liquid is discharged. Thereafter, pure water is supplied to fill the cleaning liquid receiver 1 with pure water, and the cleaning liquid receiver 1 is rotated to supply the pure water. After stirring, the cleaning liquid remaining on the surface to be cleaned of the wafer 4 is washed with pure water. In addition, this series of operations can be performed without stopping the rotation of the cleaning liquid receiver 1.

When washing with pure water is completed, the wafer holder 5 is raised and the wafer is rotated to scatter the pure water to dry the wafer 4. Further, a nitrogen gas is supplied into the cleaning liquid receiver 1, and the pure water in the cleaning liquid receiver 1 is scattered by the pressure of the nitrogen gas, so that the cleaning liquid receiver 1 is also dried. This is to prevent the concentration of the cleaning liquid contained in the cleaning liquid receiver 1 from changing every time the wafer 4 is cleaned when the next wafer 4 is cleaned. At this time, drying is effectively performed by using nitrogen gas in combination.

Here, it is also possible to discharge the pure water in the cleaning receiver 1 and rotate the cleaning liquid receiver to agitate the gas in the cleaning liquid receiver 1 to dry the wafer 4. This method does not apply a load to the wafer because the wafer holder is not rotated.

As described above, in this embodiment, with the cleaning liquid stored in the pre-cleaning liquid receiver 1, the cleaning surface of the wafer 4 is changed by the stirring mechanism accompanying the rotation of the cleaning liquid receiver 1 shown in FIG. Washed. Then, the cleaning liquid remaining on the surface to be cleaned of the wafer 4 due to the supply of pure water is washed with water. At this time,
It is possible not only to rotate the cleaning liquid receiver 1 but also to rotate the wafer holder to perform cleaning and water washing. Here, in FIG. 2, (a), (c), and (e) show vertical sectional views of three types of cleaning liquid receivers, and (b), (d), and (f) show respective plan views. 2 (a) and 2 (b) show a case where the stirring unit 3 is provided on the inner side wall of the cleaning liquid receiver 1, and FIGS. 2 (c) and 2 (d) show a case where the stirring unit 3 is at the bottom and FIG. (E),
(f), the stirring unit 3 is provided on the side wall and the bottom.

FIG. 3 is a schematic diagram showing the configuration of the apparatus of the present invention. FIG. 3A shows the wafer 4 transferred from the loader 7.
Shows that the processing is performed in the cleaning / drying chamber 8 in which cleaning and drying can be performed in the same processing chamber, and then the wafer is transferred to the unloader 9. FIG. 3B is a schematic diagram of an apparatus configuration in which cleaning and drying are performed in separate processing chambers.
The wafer 4 transferred from the loader 7 is cleaned in the cleaning chamber 10, passes through the transfer system 11, and is dried in the drying chamber 12. Thereafter, the wafer is transferred to the unloader 9. Here, FIG. 4 shows a schematic diagram of a drying apparatus used in the drying chamber 12. Here, a hole 14 is formed in the drying device 13 to reduce the load on the rotating device during drying.

Although the embodiment of the cleaning apparatus of the present invention has been described, it goes without saying that the cleaning effect can be exerted even when applied to a developing apparatus and a plating apparatus.

(Embodiment 1) The present invention was implemented with the apparatus configuration shown in FIG. In carrying out this embodiment, 50 commercially available
% Hydrofluoric acid and 40% ammonium fluoride in a volume ratio of HF: NH ₄ F: H ₂ O = 1: 5: 19 (HF 2%, N
The thermal oxide film was etched using a mixed aqueous solution of H ₄ F (8%) as an etching solution. After the cleaning time is 5 minutes, the rotation speed of the cleaning liquid receiver is 50 rpm, the subsequent water washing time is 2 minutes, and after the liquid is drained, the rotation speed of the cleaning liquid receiver is rotated at 1000 rpm for 30 seconds while irradiating the wafer with nitrogen gas. The in-plane distribution of the etching amount at 100 points of the oxide film was within ± 5%.

(Embodiment 2) The present invention was implemented with the apparatus configuration shown in FIG. In carrying out this embodiment, 50 commercially available
% Hydrofluoric acid and 40% ammonium fluoride in a volume ratio of HF: NH ₄ F: H ₂ O = 1: 5: 19 (HF 2%, N
The thermal oxide film was etched using a mixed aqueous solution of H ₄ F (8%) as an etching solution. The cleaning time is 3 minutes, the rotation speed of the cleaning solution receiver is 50 rpm, the subsequent water washing time is 2 minutes, and then the wafer is loaded into the drying chamber by the loading device.
When rotated at 30 rpm for 30 seconds, the in-plane distribution of the etching amount at 100 points of the thermal oxide film was within ± 5%.

(Embodiment 3) The present invention was carried out in an apparatus configuration shown in FIG. 3 (b) in a Si ₃ N ₄ film forming step in a semiconductor manufacturing process. Commercially available 50% hydrofluoric acid and ultrapure water
F: H ₂ O = 1:99 diluted hydrofluoric acid cleaning solution
A 6-inch semiconductor product was cleaned. The wafer is then conveying apparatus and dried is loaded into the drying chamber, and then subjected to loading in the Si ₃ N ₄ film with apparatus were semiconductors manufactured through the Si ₃ N ₄ film forming step.

As compared with the conventional batch-type cleaning method, the cleaning method according to the present invention has a reduced load at the time of cleaning, and the number of foreign substances adhered on the semiconductor product due to the foreign substance re-attachment during the cleaning is small. Table 1 shows the number of foreign particles adhered per unit area of the wafer. In addition, the semiconductor manufacturing method of the present invention has made it possible to manufacture semiconductors with high quality and high yield. In addition, the number of adhered foreign substances was measured by a visual inspection apparatus and SEM observation (measured foreign substance diameter: 0.3 μm or more).

[0026]

[Table 1]

(Embodiment 4) The present invention was carried out in an apparatus configuration shown in FIG. 3B in an Al wiring cleaning step in a semiconductor manufacturing process. A commercially available mixed solution of acetic acid and ammonia water (however, the mixing ratio is adjusted so that the solution has a pH of 5,
A 6-inch semiconductor product was cleaned with a cleaning solution prepared at a temperature of 80 ° C.). Thereafter, the wafer was carried into a drying chamber by a carry-in device and dried, and the semiconductor was manufactured through the following steps.

As compared with the conventional batch-type cleaning method, the cleaning method according to the present invention reduces the load at the time of cleaning, and the number of foreign substances adhered to the semiconductor product due to the re-adhesion of foreign substances during cleaning is small. Table 2 shows the number of foreign particles attached per unit area of the wafer. In addition, the semiconductor manufacturing method of the present invention has made it possible to manufacture semiconductors with high quality and high yield. In addition, the number of adhered foreign substances was measured by a visual inspection apparatus and SEM observation (measured foreign substance diameter: 0.3 μm or more).

[0029]

[Table 2]

(Embodiment 5) The present invention was implemented with the apparatus configuration shown in FIG. A solution of ammonia water, hydrogen peroxide and ultrapure water was added to a intentionally contaminated wafer prepared by spin-coating an aqueous solution in which Si particles having an average particle size of 0.5 μm were dispersed on a 6-inch Si wafer. Is pH = 1
The mixing ratio was adjusted to 1 and the cleaning liquid was adjusted to a liquid temperature of 80 ° C.) to clean a 6-inch Si wafer. 0.2 μm remaining on the wafer after drying
The number of foreign substances described above was measured.

As a result of cleaning by the cleaning method of the present invention, the removal rate of foreign substances was 80% in the batch system, whereas it was 90% in the batch system.
%.

(Embodiment 6) The present invention was implemented with the apparatus configuration shown in FIG. In the present embodiment, the same cleaning liquid and intentionally contaminated wafer as in the fifth embodiment are used, and cleaning is performed by applying ultrasonic waves (frequency: 980 kHz) while immersing the wafer in the cleaning liquid.

As a result of the cleaning by the method of the present invention, the removal rate of the foreign matter is 10 times higher than when no ultrasonic wave is applied.
% To almost 100%.

(Embodiment 7) The present invention was implemented with the apparatus configuration shown in FIG. According to the present invention, metal impurities were removed using ultrapure water in which ozone gas was dissolved and dilute hydrofluoric acid. 0.5 wt% diluted hydrofluoric acid prepared by mixing ultrapure water in which ozone gas was dissolved at 10 ppm and hydrofluoric acid was used as a cleaning liquid. As an object to be cleaned, a 6-inch Si wafer immersed in an aqueous solution containing 0.1 ppm of Cu ions for 30 minutes was used.

After washing with the above-mentioned washing solution for 10 seconds and drying, Cu remaining on the wafer was measured by a total reflection X-ray fluorescence analyzer.

As a result of cleaning by the cleaning method of the present invention, the concentration of Cu before cleaning was 2 × 10 ¹⁴ atoms / cm ² , but after the cleaning, the lower limit of detection (1 × 10 ¹⁰ atoms / cm ²⁾ ) In addition, when the same contaminated wafer is cleaned for 120 seconds by the conventional batch cleaning, Cu after cleaning is used.
The residual amount was 6 × 10 ¹⁰ atoms / cm ² , and the cleaning method according to the present invention had higher removal ability.

Although the present embodiment has been described with reference to ultrapure water in which ozone gas is dissolved, the same effect can be obtained with hydrogen peroxide. Alternatively, electrolysis may be performed by adding an electrolyte to ultrapure water and electrolyzed water having a high oxidizing power generated on the anode side may be used.

[0038]

According to the present invention, since the wafer holder is not rotated, cleaning can be performed without applying a load to the wafer. Therefore, even when cleaning a large semiconductor wafer, it is possible to suppress the impact on the semiconductor wafer. At the same time, by using this cleaning method, more high-quality semiconductors can be manufactured than before, and the yield can be improved. It goes without saying that the present invention can be applied to cleaning not only semiconductor wafers but also substrates such as thin film devices and disks.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the cleaning method of the present invention.

FIG. 2 is a schematic longitudinal sectional view and a plan view of a stirring mechanism used for carrying out the present invention.

FIG. 3 is a schematic plan view showing an apparatus for manufacturing a semiconductor device.

FIG. 4 is a schematic perspective view of a drying device.

[Explanation of symbols]

1. Cleaning liquid receiver, 2. Cleaning liquid, pure water, gas supply unit, 3.
Stirring mechanism, 4 wafer, 5 wafer holder, 6 cleaning liquid, 7 loader, 8 cleaning / drying chamber, 9 unloader,
10 cleaning chamber, 11 transport system, 12 drying chamber, 13 drying apparatus, 14 holes.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/304 351 H01L 21/304 351S

Claims (18)

[Claims] 1. A method of cleaning a substrate, comprising immersing a substrate in a cleaning liquid receiver provided with a freely rotatable means for cleaning. 2. The method for cleaning a substrate according to claim 1, wherein the cleaning liquid receiver is rotated clockwise or counterclockwise or clockwise or counterclockwise at an arbitrary time interval. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the cleaning liquid is circulated in the cleaning liquid receiver during cleaning. 4. The method for cleaning a substrate according to claim 1, wherein the cleaning liquid in the cleaning liquid receiver is stirred during the cleaning. 5. The method for cleaning a substrate according to claim 1, wherein the substrate after cleaning is dried by rotating the cleaning liquid receiver and stirring gas. 6. The method for cleaning a substrate according to claim 1, wherein the direction of the substrate when holding the substrate is either upward or downward. 7. A substrate drying step for drying a substrate by supplying a gas toward said substrate.
The method for cleaning a substrate according to any one of the above. 8. The method for cleaning a substrate according to claim 1, wherein the cleaning or drying is performed while rotating the substrate. 9. The method of manufacturing a semiconductor device according to claim 1, wherein said substrate is rotated clockwise or counterclockwise or alternately clockwise or counterclockwise at an arbitrary time interval. Method and cleaning method. 10. The apparatus according to claim 1, wherein the direction of rotation of the cleaning liquid receiver and the direction of rotation of the substrate are performed in the same direction or in opposite directions, or alternately in the same direction and at an arbitrary time interval.
10. The method for cleaning a substrate according to any one of items 9 to 9. 11. The cleaning liquid according to claim 1, wherein water is used.
The method for cleaning a substrate according to any one of the above. 12. The method of manufacturing a semiconductor device according to claim 1, wherein a surface treatment liquid or the like is used as said cleaning liquid. 13. An acidic solution containing at least one of hydrofluoric acid (hydrofluoric acid), hydrochloric acid, sulfuric acid, nitric acid, acetic acid, and an organic acid. 2) One or more acidic solutions and a hydrogen peroxide solution. , An acidic solution containing any of ammonium fluoride, 3) an alkaline solution containing at least one of ammonia water and an amine, 4) an aqueous solution of one or more of the above alkaline solutions and a hydrogen peroxide solution,
An alkaline solution containing ammonium fluoride or the like, 5) a mixed solution containing the one or more kinds of acidic solutions and the one or more kinds of alkaline solutions, 6) a cleaning solution comprising one of a neutral solution such as water. 13. The method for cleaning a substrate according to any one of items 12 to 12. 14. The cleaning liquid according to claim 1, wherein an organic solvent is used.
14. The method for cleaning a substrate according to any one of items 13 to 13. 15. The substrate according to claim 1, wherein an additive such as a cationic surfactant, an anionic surfactant, an amphoteric surfactant, or an organic solvent is used in combination with the cleaning solution. Cleaning method. 16. The method for cleaning a substrate according to claim 1, wherein an ultrasonic wave is applied to said cleaning liquid. 17. Water in which an oxidizing, reducing or inert gas is dissolved in place of the cleaning liquid or pure water, or water in which the physical or chemical properties of water are modified by externally applying energy. The method for cleaning a substrate according to any one of claims 1 to 16, wherein the method is performed by using or using together. 18. A method for manufacturing a semiconductor device, comprising performing cleaning or surface treatment by the cleaning method according to claim 1. Description: