JPH04346431A - Cleaning device of semiconductor silicon wafer - Google Patents

Abstract

PURPOSE:To avoid the uneven etching step by ammonia even if ammonia water and ozone are used together for cleaning up a semiconductor silicon wafer. CONSTITUTION:A tank 13 containing ammonia water 12 as a cleaning solution is arranged beneath a processing vessel 11. The ammonia water 12 kept at about 80 deg.C by a heater 14 is pressurized by a pump 15 to be jetted over a semiconductor silicon wafer 7 from nozzles 17. Ozone containing oxygen is fed from an ozone producer 5 so as to jet the ozone together with the ammonia water 12 from the nozzles 17. Through these procedures, the ammonia water 12 saturated with the ozone can be fed to the surface of semiconductor wafer 7. At this time, the surface of the semiconductor silicon wafer 7 can be mildly oxidized by the ozone and slightly etched away by the ammonia water 12.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for cleaning semiconductor silicon wafers using ammonia water.

0002

[Prior Art] Conventionally, a mixed aqueous solution of ammonia and hydrogen peroxide is used as a cleaning liquid to clean semiconductor silicon wafers.
It is used after being heated to about 80°C. In this method, hydrogen peroxide decomposes due to heating, and the cleaning solution deteriorates due to a decrease in concentration due to evaporation of ammonia. In particular, the concentration of hydrogen peroxide decreases faster than that of ammonia, and the concentration of ammonia is lower than that of hydrogen peroxide. becomes excessive. Therefore, if the cleaning liquid is used continuously, not only the cleaning power is reduced, but also the semiconductor silicon wafer is etched non-uniformly by ammonia. For this reason, hydrogen peroxide is replenished to make the concentration of hydrogen peroxide in the cleaning solution higher than that of ammonia, but for safety reasons when handling it as a chemical, the concentration of hydrogen peroxide solution is approximately 30%. However, there is a problem in that a large amount of water is brought into the cleaning solution, and when combined with the water generated by the decomposition of the hydrogen peroxide solution, the overall concentration of the cleaning solution decreases, resulting in a short lifespan of the cleaning solution. Perhaps for this reason, attempts have been made to supply ozone gas instead of hydrogen oxide water to prevent deterioration of the cleaning solution. A cleaning device using this ozone will be explained based on the drawings.

FIG. 3 is a schematic cross-sectional view of a conventional cleaning device using ozone. In the figure, 31 is a processing tank, 32 is a processing tank 31
The cleaning solution is ammonia water. 33 is processing tank 3
1 is a heater provided, 34 is a bubbler, 5 is a bubbler 34
6 is a supply pipe for supplying gas containing ozone from the ozone generator 5, and 7 is a semiconductor silicon wafer placed in a cleaning basket. Next, the operation will be explained. Cleaning liquid 3 placed in the processing tank 31
2, the liquid temperature is maintained at around 80° C. by turning on and off the heater 33. A gas containing ozone, for example, oxygen containing ozone, which is sent by taking the supply pipe 6 from the ozone generator 5, is bubbled and released from the bubbler 34 to the cleaning liquid 32.
Dissolve ozone in. When the semiconductor silicon wafer 7 is soaked in the cleaning liquid 32, the surface of the semiconductor silicon wafer 7 is slightly oxidized by the ozone contained in the cleaning liquid 32, and then light etching occurs by the ammonia water contained in the cleaning liquid 32, which causes the semiconductor The silicon wafer 7 is cleaned.

0004

However, in the conventional cleaning apparatus described above, the supply of ozone to the surface of the semiconductor silicon wafer 7 depends on bubbling from the bubbler 34 into the cleaning liquid 32. Therefore, due to the low solubility of ozone in water and the slow replacement of the ozone-containing cleaning liquid 32 on the surface of the semiconductor silicon wafer 7, the supply cannot keep up with the consumption of ozone on the surface of the semiconductor silicon wafer 7, resulting in an ozone shortage. This causes a problem in that the semiconductor silicon wafer 7 is etched non-uniformly by ammonia. The present invention was made in view of the above-mentioned conventional problems, and its purpose is to prevent uneven etching of the silicon wafer surface due to ammonia even if ammonia water and ozone are used to clean semiconductor silicon wafers. The object of the present invention is to provide a cleaning device that does not cause the problem.

[0005]

[Means for Solving the Problems] In order to achieve this object, the present invention includes a processing tank that holds semiconductor silicon wafers therein, a device that supplies aqueous ammonia under pressure, and a device that supplies ozone. By supplying the ammonia water under pressure, the ammonia water is ejected onto the semiconductor silicon wafer in the processing tank while mixing the ozone-containing gas. Further, the processing tank is sealed and a simple gas containing ozone is introduced into the processing tank.

[0006]

[Operation] In the present invention, by jetting ammonia water as a mixed gas containing ozone onto the semiconductor silicon wafer, the ammonia water saturated with ozone is quickly supplied to the silicon wafer surface, and the wafer surface is removed from the surrounding atmosphere. Promote the supply of ammonia water,
Non-uniform etching of the silicon wafer surface due to ozone deficiency will no longer occur.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same reference numerals as those in the prior art indicate the same configurations as in the prior art, and detailed description thereof will be omitted. In the figure, 11 is a processing tank, and 12 is ammonia water, which is a cleaning liquid, and in this example, the concentration is 3.5%. 13 is a tank placed below the treatment tank 11 to contain the ammonia water 12, 14 is a heater provided in the tank 13, 15 is a pump, and 16 is a filter, which in this embodiment has a pore diameter of 0.3 μm. ing. Reference numeral 17 is a nozzle, and the interior thereof is a water pump that sucks in another fluid by the flow of fluid.

Next, the operation will be explained. The ammonia water 12 in the tank 13 is maintained at around 80° C. by turning the heater 14 on and off. The semiconductor silicon wafer 7 placed in the cleaning basket is placed in the processing tank 11 . Ammonia water 12 in tank 13 is pressurized by pump 15 and particles of 0.1 .mu.m or larger are removed by filter 16, and then sprayed onto semiconductor silicon wafer 7 from nozzle 17. At the same time, oxygen containing ozone sent from the ozone generator 5 through the supply pipe 6 is sucked into the ammonia water 12 by the nozzle 17 and mixed into the ammonia water 12 due to the depressurizing effect caused by the flow of the ammonia water 12.

[0009] By suctioning and mixing ozone into the ammonia water 12, dissolution in the ammonia water 12 is promoted and saturation is rapidly achieved. Further, ammonia water 12 saturated with ozone is constantly supplied to the surface of semiconductor silicon wafer 7 by spouting ammonia water 12 from nozzle 17 . Furthermore, ozone that cannot be dissolved in the ammonia water 12 is also supplied in gaseous form to the surface of the semiconductor silicon wafer 7 along with the spout of ammonia water. As a result, sufficient ozone is supplied to the surface of the semiconductor silicon wafer 7 compared to the consumption amount, so that light oxidation of the surface of the semiconductor silicon wafer 7 by ozone and light etching by ammonia water occur, and the semiconductor silicon wafer 7 is cleaned. is performed without uneven etching due to lack of ozone. The ammonia water after washing flows down into the treatment tank 11 and returns to the tank 13 from the lower part of the treatment tank 11.

FIG. 2 shows another embodiment of the present invention. In this embodiment, a lid 22 that can be opened and closed is provided on the processing tank 21 to keep the processing tank 21 in a sealed state, and at the same time ozone is applied to one side of the processing tank 21. An inlet 23 for introducing oxygen containing ozone sent from the generator 5 into the processing tank 21 and an exhaust port 24 for exhausting the air inside the processing tank 21 are provided on the other side. By providing the treatment tank 21 with the inlet 23 and the exhaust port 24, the ozone concentration inside the treatment tank 21 can be increased. When the pump 15 is operated and the ammonia water 12 is ejected from the nozzle 17 together with ozone, the ozone atmosphere is present around the semiconductor silicon wafer 7, so that the supply of ozone is further promoted.

[0011]

[Effects of the Invention] As explained above, according to the present invention,
Since the gas containing ozone is ejected from the nozzle together with ammonia water onto the semiconductor silicon wafer, the ozone is sufficiently supplied to the semiconductor silicon wafer surface, and uneven etching does not occur. This has the effect that the wafer can be cleaned reliably.

[Brief explanation of drawings]

FIG. 1 is a schematic side sectional view of the invention.

FIG. 2 is a schematic side sectional view showing another embodiment of the invention.

FIG. 3 is a schematic side sectional view of a conventional device.

[Explanation of symbols]

5 Ozone generator 7 Semiconductor silicon wafer 11 Processing tank 12 Ammonia water 13 Tank 15 Pump 17 Nozzle

Claims (2)

[Claims] 1. A processing tank that holds a semiconductor silicon wafer therein, a device that supplies ammonia water under pressure, and a device that supplies ozone, and contains the ozone by supplying the ammonia water under pressure. A cleaning device for semiconductor silicon wafers, characterized in that the ammonia water is jetted onto the semiconductor silicon wafers in the processing tank while mixing gases. 2. The semiconductor silicon wafer cleaning apparatus according to claim 1, wherein the processing tank is sealed and ozone alone is introduced into the processing tank.