JPH04278529A - Silicon wafer cleaning equipment - Google Patents

Abstract

PURPOSE:To stabilize cleaning effect by reducing the decrease of concentration due to variation with time of each chemical liquid in mixed chemical liquid in a chemical liquid tank. CONSTITUTION:In a chemical liquid tank 1, content analyzers 5 and 6 which measure the concentration of each chemical liquid mixed in a liquid are installed. Based on command signals 10 from the content analyzers, an on-off valve 4 for supplement is controlled. The chemical liquid whose concentration is decreased is automatically supplemented from chemical liquid supplement tanks 2a and 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon wafer cleaning device for cleaning silicon wafers with inorganic chemicals such as ammonia, hydrogen peroxide, sulfuric acid, and hydrogen peroxide in semiconductor integrated circuit device manufacturing equipment.

0002

[Prior Art] Conventionally, this type of silicon wafer cleaning equipment for manufacturing semiconductor integrated circuit devices uses chemical solutions such as ammonia, hydrogen peroxide, sulfuric acid, and hydrogen peroxide, as shown in the block diagram of FIG. Regarding replenishment, a replenishment on-off valve 4 located in the middle of the piping from each replenishment tank, an ammonia (or sulfuric acid) replenishment tank 2 and a hydrogen peroxide solution replenishment tank 3, to the chemical layer 1 opens and closes at a certain time interval, It was controlled to automatically replenish a certain amount of each chemical solution at certain time intervals. In this way, in the case of each chemical solution in the chemical solution tank 1, for example, ammonia and hydrogen peroxide solution, the cleaning effect is stabilized by keeping the concentrations of ammonia and hydrogen peroxide solution constant.

0003

[Problems to be Solved by the Invention] The conventional silicon wafer cleaning apparatus described above uses a mixture of inorganic chemicals such as ammonia, hydrogen peroxide, sulfuric acid, and hydrogen peroxide at 60 to 10
Silicon wafers are cleaned at a temperature of 0°C. At this time, the concentration of each chemical solution in the chemical solution tank of the silicon wafer cleaning apparatus changes in the direction of decreasing over time by setting the solution temperature to 60 to 100°C. Especially in the case of ammonia and hydrogen peroxide, when the concentration of ammonia decreases, the cleaning effect decreases, and in the case of sulfuric acid and hydrogen peroxide, when the concentration of hydrogen peroxide decreases, the amount of caroic acid produced decreases, and the cleaning effect decreases. decreases.

[0004] For this reason, in conventional devices, each chemical solution is automatically replenished in a fixed amount at fixed time intervals. However, with this method, it is difficult to control the concentration of each chemical solution in the chemical tank to be constant, and if the automatic replenishment method is not optimized, the concentration of each chemical solution over time may vary. There is a problem in that changes become more rapid and variations in concentration become larger.

[0005]

[Means for Solving the Problems] The silicon wafer cleaning apparatus of the present invention is equipped with a component analyzer that measures the concentration of each inorganic chemical solution such as ammonia, hydrogen peroxide solution, sulfuric acid, hydrogen peroxide solution, etc. This makes it possible to continuously monitor the concentration of each chemical solution mixed in the chemical solution tank. Then, the replenishment on-off valve is controlled based on the signal from the component analyzer, and even if the concentration of each chemical solution in the chemical tank decreases over time from immediately after the new solution is added, the concentration will decrease to a certain value. When the concentration of the chemical solution decreases, it can be automatically refilled.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of the present invention.

In the first embodiment, component analyzers 5 and 6 for optically measuring the concentrations of ammonia and hydrogen peroxide are attached to the chemical layer 1 of the silicon wafer cleaning apparatus. During analysis, first, the measurement sampling on-off valve 7 is opened, and the chemical solution in the chemical solution tank 1 is circulated through the filter 9 by the pump 8. As a result, the concentration of ammonia hydrogen peroxide solution in the chemical tank 1 can be continuously monitored at all times, and the replenishment on-off valve 4 is opened and closed by the opening/closing command signal 10 from the component analyzers 5 and 6. Even if the ammonia or hydrogen peroxide solution decreases over time, when the ammonia or hydrogen peroxide solution decreases to a certain amount, the ammonia replenishment tank 2a
By automatically replenishing the hydrogen peroxide solution from the hydrogen peroxide solution replenishment tank 3, it is possible to always keep the concentrations of ammonia and hydrogen peroxide solution constant in the chemical solution tank.

FIG. 2 is a block diagram of a second embodiment of the present invention. Embodiment 2 shows an example in which a component analyzer 11 is installed in the chemical tank 1 to optically measure the concentration of caroic acid produced in a mixture of sulfuric acid and hydrogen peroxide. The monitoring method and the like are the same as in Example 1.

Next, the effects of Examples 1 and 2 over the prior art will be explained. FIG. 4 is a graph comparing Example 1 and the conventional technology, and FIG. 4 (a) shows the change over time in the concentration of ammonia and hydrogen peroxide in the chemical tank when Example 1 of the present invention is used. It is a graph. Further, FIG. 2B is a graph showing changes over time in the concentrations of ammonia and hydrogen peroxide in the chemical tank when the conventional technique is used.

FIG. 5 is a graph comparing Example 2 with the prior art, and FIG. be.

[0012] FIG. 2B is a graph showing the change over time in the caroic acid concentration in the chemical tank when the conventional technique is used.

As shown in FIG. 4, ammonia,
When using hydrogen peroxide solution, the agricultural degree of ammonia and hydrogen peroxide solution used to vary by 30% compared to each set value.
%, whereas when Example 1 is used, the variation can be suppressed to 10% for each set value. Also, Figure 5
As shown in , when sulfuric acid and hydrogen peroxide are used in the chemical tank, caroic acid is produced as a reactant in the chemical tank. When the conventional technique is used, the Caroic acid concentration has a variation of 50% with respect to the set value, but when Example 2 is used, the variation with respect to the set value can be suppressed to 15%.

[0014]

As described above, the silicon wafer cleaning apparatus of the present invention is equipped with a component analyzer so that the concentration of each chemical in the chemical tank can be continuously monitored as a mass ratio. This makes it possible to control automatic replenishment of a chemical solution whose concentration has decreased in accordance with changes in the concentration of each chemical solution in the chemical tank over time, thereby stabilizing the cleaning effect.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional cleaning device.

FIG. 4 is a graph comparing Example 1 and the prior art; FIG. 4(a) shows the case of Example 1, and FIG. 4(b) shows the case of the prior art.

FIG. 5 is a graph comparing Example 2 and the prior art; FIG. 5(a) shows the case of Example 2, and FIG. 5(b) shows the case of the prior art.

[Explanation of symbols]

1 Chemical solution tank 2 Ammonia (or sulfuric acid) replenishment tank 2a
Ammonia replenishment tank 2b Sulfuric acid replenishment tank 3 Hydrogen peroxide replenishment tank 4 Replenishment on-off valve 5 Ammonia component analyzer 6 Hydrogen peroxide water component analyzer 7 Measurement sampling on-off valve 8 Pump 9 Filter 10 Opening/closing command signal 11 Caroic acid component analyzer

Claims (1)

[Claims] Claim 1: In a silicon wafer cleaning apparatus for cleaning silicon wafers with an inorganic chemical solution such as ammonia, hydrogen peroxide solution, sulfuric acid, hydrogen peroxide solution, etc., a chemical solution tank such as ammonia, hydrogen peroxide solution, sulfuric acid, hydrogen peroxide solution, etc. A component analyzer continuously monitors the concentration of the mixed chemical solution as a mass ratio for each drug solution, and based on the signal from this component analyzer, the appropriate amount of drug solution is dispensed according to the change in the mass ratio of each drug solution over time. A silicon wafer cleaning device characterized by having a replenishment on-off valve that automatically replenishes each chemical solution from a replenishment tank.