JPH02207526A - Single wafer washing method - Google Patents

Abstract

PURPOSE:To improve washing efficiency by a method wherein, after objects to be processed in a processing tank are brought into contact one by one, with a first chemical liquid containing aqueous solution of sulfric acid and hydrogen peroxide water, they are brought into contact with a second chemical liquid containing aqueous solution of ammonia and hydrogen peroxide water. CONSTITUTION:Firstly, in an individual processing tank 21 of A, a wafer W is arranged. When, from chemical liquid supplying pipes 21I, 21J, H2SO4 and H2O2 are dripped, both of the chemical liquids violently cause a chemical reaction and the temperature rises. Thus the surface of the wafer W is washed. After a specified time has passed, the liquid in the individual processing tank 21 of A is discharged, and the wafer W is pulled out, which is put into an individual processing tank 21 of B and washed with pure water. After that, the water in the individual processing tank 21 of B is discharged, the wafer W is pulled out and put into an individual processing tank 21 of C. NH4OH and H2O2 are supplied to the tank C, and the surface of the wafer W is washed. After a specified time has passed, the liquid in the individual processing tank 21 of C is discharged, and the wafer W is pulled out. The wafer is put in an individual processing tank 21 of D, and pure water is supplied and overflowed. After washing, the water is discharged, and the wafer is taken out, thereby finishing the washing process.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a single-wafer cleaning method that is optimal for use in cleaning, for example, semiconductor wafer manufacturing processes.

[Conventional technology]

Cleaning of semiconductor wafers is one of the essential operations when manufacturing semiconductor devices, especially ICs. During this cleaning, a jig such as a boat is used to hold the wafers at predetermined intervals within the processing tank.

[Problems to be solved by the invention]

For this reason, the cleaning efficiency of the contact area between the wafer and the boat and its vicinity is poor, and this often causes dirt to remain. In addition, dirt will remain on the boat, and the possibility of back contamination from the boat to the next wafer to be processed cannot be ignored. If a large number of wafers are stored and cleaned in one processing tank, even if a chemical circulation system is used to circulate the chemical, it is inevitable that contaminated chemicals will adhere to the wafers or boat. This resulted in a decrease in cleaning ability. These matters are becoming increasingly important problems that cannot be ignored, especially as the development of super-integrated technologies such as IM, 4M, and 16M advances.

[Means to solve the problem]

This invention was made in order to solve the above-mentioned problems. One object to be processed is stored in a processing tank, and a solution containing sulfuric acid and hydrogen peroxide is applied to the object in the processing tank. This is a single-wafer cleaning method characterized by contacting the first chemical solution with a second chemical solution containing an aqueous solution of ammonia and hydrogen peroxide. Another feature is that the chemical solution is brought into contact with the semiconductor wafer while being accompanied by ultrasonic vibrations.

[Effect]

When cleaning the object to be processed, the first chemical solution can remove an oxide film and the like, and the second chemical solution can remove fine resist residues and particles, allowing effective cleaning.

【Example】

Next, an example in which the single wafer cleaning method of the present invention is applied to cleaning a single wafer dip type semiconductor wafer is shown in FIGS. 1 and 2.
This will be explained with reference to the figures. In the diagram showing a single wafer dip type semiconductor wafer cleaning apparatus, a closed processing tank 2 is a box with a bottom, and is made of, for example, Teflon or quartz, which has good corrosion resistance against chemicals L1 and L2. As the first chemical solution L1 for cleaning the wafer W, an aqueous solution of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) is used, and as the second chemical solution L2, ammonia (
Aqueous solutions of NH40H) and hydrogen peroxide (H20□) are employed. In the chemical solution L1, H2SO2 and H
202(7) ratio is preferably 4:1, and in chemical solution L2, the ratio of N H40H to Hz 02 and H20 is l:
l:5 is desirable. Inside the processing tank 2 installed inside the apparatus main body 1, a plurality of individual processing tanks 21 are arranged at predetermined intervals. This individual processing tank 21 includes an outer tank 21A as shown in FIG.
Inner 21B inside. A wafer W storage space 21G is provided by combining 2IC, 21D and wedges 21E, 21F, and the inner 2
1B has a notch 21 for chucking the wafer W.
H is provided. The inner 21D is provided with a groove 21M for holding the wafer W upright in the accommodation space 21G.
Instead of just one, a plurality of them may be provided to hold the wafer W. In addition, there are four vibrators 21 r facing outward in the outer tank 2LA.
, 21J, 21 are provided with 21L, and 211.21
J is used as a chemical liquid supply pipe, 21 is an overflow pipe for discharging overflowing chemical liquid when overflowing the wafer W, and 21L is used as a train pipe for discharging the chemical liquid after processing the wafer W. A rod-shaped cap 22 having a length approximately equal to the width of the wafer W is attached to the upper opening of each individual processing tank 21. Both ends of the cap 22 are fitted into the arcuate grooves 24 of the side plates 23C, which are erected at both longitudinal ends of the cover 23, which has an upper opening 23A and a lower opening 23B. A drive source 3 such as a motor or an air cylinder is connected to the rotary shaft 25 mounted thereon by an arm 26 and slides in the arcuate groove 24, and is connected to the rotary shaft 25 by a universal joint 27, 28 and a connecting shaft 29.
Drive it at 0 and position it at the lower end of the arcuate groove 24! The upper opening of the individual treatment tank 21 is closed when the individual treatment tank 21 is ready for use. A lid 4 is provided on the top of the individual processing tank 21 with a seal 3 interposed therebetween, and the individual processing tank 21 is attached thereon via a seal 5. The drain pipe 21L of each individual processing tank 21 passes through the processing tank 2 and is attached using a bushing 6 with a seal, and a train tube 14 and an air valve 15 are attached to the tip thereof. Furthermore, a heater 7 for controlling the heat of the pure water filled in the processing tank 2 is installed at the bottom of the processing tank 2 using a bushing 8 with a seal, and an ultrasonic vibrator 9 is installed at the bottom with a seal l It is attached via ○. Processing tank 2
In addition to these, a pure water supply pipe, a liquid temperature sensor, an exhaust pipe, a liquid upper limit level sensor, and a liquid lower limit level sensor (not shown) are attached to the connection hole 4A of the lid 4. Connection hole 2 of treatment tank 2
The drain pipe 21L is attached to A, and the connection hole 2B is connected to the drain pipe 21L.
A drain tube 13 is attached to the drain tube 13 for releasing pure water if too much pure water enters the drain tube. The pure water in the processing tank 2 is always kept in a groove to keep the individual processing tank 21 warm and to protect the ultrasonic transducer 9. Three chemical solution supply systems and a pure water supply system are provided on the side of the processing tank 2. Details of the chemical solution supply system 16 are shown in FIG. The chemical solution stored in the storage tank 161 is pumped to the pump 162.
through the filter 163 and air valve 164 to the measuring tank 16.
Sent to 5. From the measuring tank 165, it is sent to the individual processing tank 21 by gravity via an air valve 166. Normally, chemical liquid is passed through a filter 163 and an air valve 167 (the air valve 164 is closed) by a pump 162 to a storage tank 1.
When the chemical solution in the measuring tank 165 reaches the lower limit level, the air valve 167 is closed and the air valve 1
64 is opened and sent to the measuring tank 165. H2SO4, HzO□, and NH40H are stored separately in three storage tanks provided corresponding to each chemical supply system 16. The materials for the pipes of each supply system 16 and 17 above are as follows:
Teflon, quartz, or the like is used, and the material has excellent corrosion resistance compared to the chemical solution L2. Also pump 1
62 is a chemical liquid L+ whose delivery capacity is set to about 10 to 30 I2/min, and which enters from the chemical liquid supply pipe 211.21J.
, La flow rate is set to about 3 to 10 I2/min. Assuming that the individual processing tanks 21 are designated as A, B, C, and D from the second solid state, the processing liquids used here are A, chemical liquid L+, and chemical liquid L+ in this embodiment.
Pure water is used for B, chemical liquid L2 is used for C, and pure water is used for D. However, the number of processing tanks 2 is further increased to make two tanks, and the individual processing tanks 21 of the first processing tank 2 contain chemical liquid L+, chemical liquid Ll, Pure water,
Using pure water, each chemical solution L2. Chemical solution L2. Pure water or purified water may be used;
Other combinations are also possible. In this embodiment, the chemical liquid L1 is used in the individual processing tank 21, and the chemical liquid L1 is mixed within the individual processing tank 21. That is, H*S O from the chemical supply pipe 211
4 is supplied with H2O2 from the chemical supply pipe 21J and mixed in the individual treatment tank 21, reacts vigorously and reaches a high temperature (approximately 150
°C) becomes a chemical solution. NH from the individual treatment tank 211 of C
, OH is supplied with HzOz from the chemical solution supply pipe 21J,
Mixed in a tank. Pure water is supplied to the individual processing tanks B and D from chemical solution supply pipes 211 and 21J. Next, the effects of the above configuration will be sequentially explained. First, a wafer W coated with a resist or subjected to an ashing process is placed in the individual processing bath 21 of A. The air valve 166 of the H2SO4 chemical supply system 16 is opened for a certain period of time (until the individual treatment tank 21 is filled with the chemical), and each H2SO4 is supplied from the measuring tank 165.
4 and H20□ are dropped from the chemical solution supply pipe 211.21J, the chemical solution causes a vigorous chemical reaction and becomes high temperature (approximately 150° C.), thereby cleaning the surface of the wafer W. During this time, the ultrasonic vibrator 9 is operated to promote the chemical reaction and effectively clean both sides of the wafer W. The cleaning time varies depending on the wafer W to be processed, but is about 20 seconds to 3 minutes. After a predetermined period of time has elapsed, the air valve 15 is opened and the chemical liquid in the individual treatment tank 21 of A is poured. Drain the liquid and pull out the wafer W. Next, put the pulled out wafer W into the individual processing tank 21 of B, and
More pure water is injected from the pure water supply system 17, and washing is performed with pure water. In the case of pure water cleaning, pure water is supplied during the processing time, and overflowing pure water during that time is drained through the overflow pipe 21. During this time as well, the ultrasonic vibrator 9 operates to promote cleaning. After a predetermined period of time, open the air valve 15 and open the individual treatment tank 2 of B.
The pure water in 1 is drained, and the wafer W is pulled out and placed in the individual processing tank 21 of C. In the individual treatment tank 21 of C, the chemical solution supply pipe 2
NH, OH and H2O2 are supplied from 11 and 21J respectively, and the tank is filled with the chemical solution L2 to clean the surface of the wafer W. During this time, the ultrasonic vibrator 9 is operated to effectively clean both sides of the wafer W while promoting the chemical reaction. The washing time is approximately 20 seconds to 3 minutes. After a predetermined time has elapsed, the air valve 15 is opened, the chemical solution L2 in the individual processing tank 21 of C is drained, and the wafer W is pulled out and placed in the individual processing tank 21 of D. D
In the individual treatment tank 21, chemical solution supply pipes 211, 2 are connected similarly to B.
Supply pure water from 1J to overflow and wash. During this time as well, the ultrasonic vibrator 9 operates to promote cleaning. After a predetermined time has elapsed, the air valve 15 is opened, the pure water in the individual processing tank 21 of D is drained, and the wafer W is taken out, thereby completing the cleaning process. Next, FIG. 4 shows another embodiment of the single wafer cleaning method of the present invention. The processing tank 41 is provided with a wafer fixing table 43 having a predetermined height and having an ultrasonic vibrator 42 at the bottom thereof, and a quartz tube heater 44 is arranged around the wafer fixing table 43 . The wafer fixing table 43 has an open top, and ultrasonic nozzles 45 and 46 for blowing out chemical liquid are attached to the top. Of the chemical liquid, H2SO4 is blown out from the ultrasonic nozzle 45 via the high temperature pump 47, and H2O2 is blown out from the ultrasonic nozzle 46 via the pump 48, on the surface of the wafer W set on the wafer fixing table 43. Wash. On the other hand, these aqueous solutions are recycled by circulating between the treatment tank 41 and the chemical liquid regeneration treatment device 49. That is, the chemical liquid regeneration processing device 49 includes a waste liquid storage tank 50 and a regeneration liquid storage tank 51, and a filtration device 52 attached therebetween.
It is designed to be played by. 53 and 54 are high temperature pumps or pumps, respectively. The chemical liquid sent to the waste liquid storage tank 50 through the drain port 55 of the processing tank 41 is sent to the filtration device 52 by the pump 54, and stored in the regeneration liquid storage tank 51 to be used as needed. High temperature pump 5
3, the liquid is fed into the processing tank 41 via the liquid supply port 56. At this time, the lower surface of the wafer W immersed in the chemical solution L1 is also cleaned by the ultrasonic vibrator 42 provided at the bottom of the wafer fixing table 43. A similar device is provided separately, and NH, OH and H
A chemical solution L2 made of zO2 is then applied to both the front and back surfaces of the wafer W to perform a cleaning process. Chemical liquid L1. The cleaning time by L2 may be the same as in the previous embodiment. By the way, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the number of individual processing tanks and the number of ultrasonic nozzles are not limited to those in the embodiments, and may be larger or smaller.
1 can take various forms depending on the shape of the wafer. 4. In the above embodiment, a case where the present invention is applied to cleaning a semiconductor wafer has been described, but any cleaning process may be used, such as cleaning an LCD substrate, a substrate on which a TPT circuit is formed, or the like.

【Effect of the invention】

As is clear from the above explanation, when cleaning wafers, each wafer is treated one by one with individual chemical solutions, so wafers do not come into contact with chemicals contaminated by cleaning other wafers, and furthermore, they are not contaminated by reverse contamination. There is no risk of Therefore, there is an excellent effect of significantly improving cleaning efficiency in response to larger diameter and higher quality wafers.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main part of a wafer cleaning apparatus to which the method of the present invention is applied, Fig. 2 is a longitudinal cross-sectional view of the main part, and Fig. 3 is a chemical liquid supply system 1.
FIG. 4 is a schematic sectional view showing another embodiment. 1... Apparatus body 2... Processing tank 9... Ultrasonic vibrator 16... Chemical supply system 1... Individual processing tank 22... Rod-shaped cap 3... Guide
24... Arc-shaped groove 5... Rotating shaft 26
...Arm 0...Drive source 1...Processing tank 42...Ultrasonic vibrator 3.
...Wafer fixing stand 44...Quartz tube heater 5.46
... Ultrasonic nozzle 7 ... High temperature pump 48 ... Pump 9 ... Chemical liquid regeneration processing device 0 ... Drainage liquid storage tank 51 ... Regeneration liquid storage tank 2.
...Filtering device 53...High temperature pump 4...Pump 55...Drain port 6...Liquid supply port
W... Wafer patent applicant Tokyo Electron Ltd. Same as above Sugai Co., Ltd. Genealogy Co.] 5.D

Claims (1)

[Claims] 1. One object to be processed is stored in a processing tank, and a first object containing an aqueous solution of sulfuric acid and hydrogen peroxide is added to the object in the processing tank.
A single wafer cleaning method, which comprises contacting with a second chemical solution and then contacting with a second chemical solution containing an aqueous solution of ammonia and hydrogen peroxide. 2. The single wafer cleaning method according to claim 1, wherein the contact of the chemical solution to the object to be treated is performed with ultrasonic vibration.