JP2737424B2 - Silicon wafer cleaning equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a semiconductor integrated circuit device, and more particularly to a silicon wafer cleaning apparatus for cleaning a silicon wafer with an inorganic chemical such as ammonia, hydrogen peroxide or sulfuric acid or hydrogen peroxide.

[0002]

2. Description of the Related Art Conventionally, a silicon wafer cleaning apparatus of this type for manufacturing a semiconductor integrated circuit device has a chemical solution such as ammonia, hydrogen peroxide solution or sulfuric acid or hydrogen peroxide solution, as shown in FIG. Regarding the replenishment, the replenishment on-off valve 4 in the middle of the piping from each replenishment tank 2 of the ammonia (or sulfuric acid) replenishment tank 2 and the hydrogen peroxide water replenishment tank 3 to the chemical solution layer 1 opens and closes at a certain time interval, It was controlled so that each drug solution was automatically replenished by a certain amount at a certain time interval. Thus, 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]

In the conventional silicon wafer cleaning apparatus described above, a mixed solution of an inorganic chemical such as ammonia, hydrogen peroxide or sulfuric acid, hydrogen peroxide is used for 60 to 10 minutes.
The silicon wafer is 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 a direction decreasing with time by setting the solution temperature to 60 to 100 ° C. In particular, in the case of ammonia and hydrogen peroxide solution, the cleaning effect decreases when the concentration of ammonia decreases, and also in the case of sulfuric acid and hydrogen peroxide solution, when the concentration of hydrogen peroxide solution decreases, the amount of generated caroic acid decreases, and the cleaning effect decreases. Decrease.

For this reason, in the conventional apparatus, each chemical solution is automatically replenished by a fixed amount at a fixed time interval. However, in 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 is not improved. There is a problem that the change becomes drastic and the variation in density becomes large.

[0005]

Means for Solving the Problems A silicon wafer cleaning apparatus of the present invention is a silicon wafer cleaning apparatus for cleaning a silicon wafer with an inorganic chemical such as sulfuric acid and hydrogen peroxide solution. Comprising a component analyzer for continuously monitoring the concentration of a drug solution comprising: and a replenishing closing valve for automatically refilling from a replenishing tank for each drug solution based on a signal from the component analyzer. I do. Ma
The component analyzer uses a mixture of sulfuric acid and hydrogen peroxide solution.
The concentration of caroic acid formed may be monitored.

[0006]

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

FIG. 1 is a configuration 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 solution are attached to the chemical liquid layer 1 of a silicon wafer cleaning apparatus. At the time of analysis, the measurement sampling on-off valve 7 is first opened, and the chemical solution in the chemical solution tank 1 is forwarded through the filter 9 by the pump 8. As a result, the concentration of the ammonia hydrogen peroxide solution in the chemical solution tank 1 can be continuously monitored, and the replenishing on-off valve 4 is opened and closed by the open / close command signal 10 from the component analyzers 5 and 6, so that the chemical solution tank 1 Even if the amount of ammonia or hydrogen peroxide decreases with time, the ammonia replenishing tank 2a is used when the amount of ammonia or hydrogen peroxide decreases to a certain amount.
In addition, automatic replenishment from the hydrogen peroxide solution replenishing tank 3 makes it possible to always keep the concentrations of ammonia and hydrogen peroxide in the chemical solution tank constant.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.
Example 2 shows an example in which a chemical analyzer 11 for optically measuring the concentration of caroic acid generated in a mixed solution of sulfuric acid and hydrogen peroxide in a chemical solution tank 1 is provided. The monitoring method and the like are the same as in the first embodiment.

Next, the effects of the first and second embodiments on the prior art will be described. FIG. 4 is a graph comparing Example 1 with the prior art, and FIG. 4A shows changes over time in the concentrations of ammonia and hydrogen peroxide in the chemical solution tank when Example 1 of the present invention is used. It is a graph. FIG. 2B is a graph showing the change over time in the concentrations of ammonia and hydrogen peroxide in the chemical solution tank when the conventional technique is used.

FIG. 5 is a graph comparing Example 2 with the prior art, and FIG. 5A is a graph showing the change over time of the concentration of caroic acid in the chemical tank when Example 2 of the present invention is used. is there.

FIG. 1B is a graph showing the change over time of the concentration of caroic acid in the chemical tank when the conventional technique is used.

[0013] As shown in FIG.
Conventionally, when the hydrogen peroxide solution is used, the variability of the ammonia and the hydrogen peroxide solution with respect to each set value is 30%.
In contrast, when the first embodiment is used, a variation of 10% can be suppressed for each set value. FIG.
As shown in (1), when sulfuric acid and hydrogen peroxide solution are used in the chemical tank, caroic acid is formed as a reactant in the chemical tank. This caroic acid concentration is 50% of the set value when using the conventional technology.
However, when the second embodiment is used, the variation can be suppressed to 15% of the set value.

[0014]

As described above, the silicon wafer cleaning apparatus of the present invention is provided 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 the automatic replenishment of the chemical solution whose concentration has decreased in accordance with the change over time in the concentration of each chemical solution in the chemical solution tank, thereby stabilizing the cleaning effect.

[Brief description of the drawings]

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.

FIGS. 4A and 4B are graphs for comparing the first embodiment with the prior art, in which FIG. 4A shows the case of the first embodiment and FIG. 4B shows the case of the prior art.

FIGS. 5A and 5B are graphs comparing the second embodiment and the prior art, wherein FIG. 5A shows the case of the second embodiment and FIG. 5B shows the case of the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chemical tank 2 Ammonia (or sulfuric acid) replenishment tank 2a Ammonia replenishment tank 2b Sulfuric acid replenishment tank 3 Hydrogen peroxide water replenishment tank 4 Replenishment on-off valve 5 Ammonia component analyzer 6 Hydrogen peroxide water component analyzer 7 Measurement sampling on-off valve Reference Signs List 8 pump 9 filter 10 opening / closing command signal 11 caroic acid component analyzer

Claims (2)

(57) [Claims] 1. A silicon wafer cleaning apparatus of the silicon wafer is washed with an inorganic chemical such as sulfuric acid and hydrogen peroxide, a continuous concentration of <br/> chemical the consisting of sulfuric acid and hydrogen peroxide solution of the chemical tank monitor And a replenishing closing valve for automatically replenishing each chemical solution from a replenishing tank based on a signal from the component analyzer. 2. The silicon wafer cleaning apparatus according to claim 1, wherein said concentration is a concentration of caroic acid generated in a mixed solution of said sulfuric acid and said hydrogen peroxide solution.