JP3055292B2 - Semiconductor device cleaning method - Google Patents

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 a semiconductor device using a mixed solution of ammonia water, hydrogen peroxide solution and water used for cleaning a silicon wafer.

[0002]

2. Description of the Related Art A chemical mixture of aqueous ammonia, aqueous hydrogen peroxide and water is widely used for cleaning semiconductor devices because it is effective for removing particles. Hereinafter, an example of the above-described conventional semiconductor device cleaning method will be described with reference to the drawings. FIG. 4 shows a configuration diagram of a conventional cleaning apparatus. In FIG. 4, reference numeral 1 denotes a cleaning tank. Reference numeral 2 denotes a heater for heating a chemical solution to a processing temperature. Reference numeral 3 denotes a pump for circulating a chemical solution, and reference numeral 4 denotes a filter for removing particles. Reference numeral 5 denotes a weighing tank for preparing a chemical solution at a set mixing ratio, and reference numeral 7 denotes a sensor for detecting a liquid level.

[0003] The operation of the cleaning apparatus configured as described above will be described below. First, the weighing tank 5c
Is transferred to the processing tank 1 and then heated to a processing temperature of about 70 ° C. by the heater 2, and then the weighing tanks 5a and 5b
The ammonia water and the hydrogen peroxide solution measured in the above are mixed to prepare a cleaning solution. The chemical is circulated through the pump 3 and the filter 4, and performs cleaning while removing particles in the chemical. In this state, the composition ratio changes due to evaporation, decomposition, and the like. Therefore, ammonia water and hydrogen peroxide water are additionally supplied by a fixed amount at regular intervals or every wafer processing. This additional amount was empirically determined due to the lack of concentration measurement techniques.

[0004]

However, in the above configuration, it is not known how the concentration in the cleaning chemical solution changes, and both the ammonia water and the hydrogen peroxide water are additionally supplied. The problem is that the etching rate and cleaning characteristics change due to the above.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a method of cleaning a semiconductor device having an optimal amount of a chemical solution.

[0006]

In order to solve the above-mentioned problems, a method for cleaning a semiconductor device according to the present invention comprises the steps of:
In cleaning in a silicon process using a mixed solution of hydrogen peroxide water and water, an additional supply of ammonia water corresponding to the processing temperature is performed without additionally supplying hydrogen peroxide water. Further, the additional supply of the ammonia water is carried out at regular time intervals according to the processing temperature.

Further, the method for cleaning a semiconductor device according to the present invention comprises:
Additional amount of ammonia water at processing temperature T and elapsed time t
It is characterized in that v is calculated by (Equation 1).

[0008]

According to the present invention, since the change in the concentration of the chemical is a function of the temperature and the time, the concentration of the chemical can be accurately controlled without the necessity of measuring the concentration as needed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for cleaning a semiconductor device according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a method for cleaning a semiconductor device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a cleaning tank, and 2 denotes a heater for heating a chemical solution to a processing temperature. Reference numeral 3 denotes a pump for circulating a chemical solution, and reference numeral 4 denotes a filter for removing particles. Reference numeral 5 denotes a weighing tank for preparing a chemical solution at a set mixing ratio, and reference numeral 7 denotes a sensor for detecting a liquid level. Reference numeral 10 denotes a built-in timer 6 which forms an automatic adding device for adding the ammonia water 9 by the metering pump 8 at regular intervals. As shown in the conventional example, the treatment solution is measured using a weighing tank and set to an initial concentration of the solution. The chemical is circulated using the pump 3 and the filter 4 to remove particles.

The operation of the method for cleaning a semiconductor device configured as described above will be described below with reference to FIGS. 1, 2 and 3.

First, after the water measured in the weighing tank 5c is transferred to the processing tank 1, the water is heated to a processing temperature of about 70 ° C. by the heater 2, and then the ammonia water and the hydrogen peroxide water measured in the weighing tanks 5a and 5b are used. To prepare a cleaning solution. The chemical is circulated through the pump 3 and the filter 4 to perform cleaning while removing particles in the chemical. FIG. 2 shows a change in the concentration of ammonia and hydrogen peroxide at a processing temperature of 70 ° C. The ammonia decreases with time with respect to the set initial concentration, whereas the concentration of hydrogen peroxide is Remains constant. Further, as shown in FIG. 3, the decrease in the ammonia concentration depends on the temperature, and the change can be expressed by an exponential function (Equation 2).

[0012]

(Equation 2)

Therefore, once the chemical solution is mixed, it is not necessary to supply hydrogen peroxide additionally, and ammonia depends on the processing temperature. By additionally supplying, the concentration of the cleaning liquid can be kept constant. For example,
In the case where the stock solution of ammonia water is 29% and the original treatment liquid is 24 liters, 323 ml may be added every 10 minutes to keep the ammonia concentration at 4% at the treatment temperature of 70 ° C. Conversely, when the elapsed time from the previous process is known, it is possible to know how much should be added by calculation. Therefore, a signal is generated by the timer 6 every 10 minutes, the metering pump 8 is operated by the signal, and about 323 ml of the ammonia water 9 is additionally supplied. It has been found that there is almost no change in concentration even when the silicon wafer is cleaned with the chemical liquid whose concentration is controlled, and the concentration in the chemical liquid can be kept constant by additionally supplying only ammonia.

As described above, according to the present embodiment, it is clarified that the concentration of only ammonia changes in the cleaning using the aqueous ammonia and the aqueous hydrogen peroxide.
A calculation formula that can calculate the additional amount of the chemical solution only by the passage of time is derived, and this formula can eliminate a change in the concentration in the cleaning chemical solution.

In this embodiment, the automatic adding device 1
Although 0 uses a built-in timer 6 and metering pump 8, it is easy to realize that a microcomputer or the like can be installed and a chemical formula can be used to supply an additional amount of chemical solution at an arbitrary time at an arbitrary time. It is.

[0016]

As described above, according to the present invention, the concentration of ammonia water and hydrogen peroxide water can be controlled to be constant by additionally supplying a chemical solution at regular intervals using a concentration change formula. Thus, the etching rate and the cleaning effect can be stabilized, and variations between lot processes can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cleaning apparatus according to an embodiment of the present invention.

FIG. 2 is a concentration change characteristic diagram of ammonia and hydrogen peroxide for explaining the operation in the embodiment.

FIG. 3 is a characteristic diagram in which changes in concentrations of ammonia and hydrogen peroxide are exponentially plotted according to temperature in the embodiment.

FIG. 4 is a configuration diagram of a conventional cleaning device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Washing tank 2 Heater 3 Pump 4 Filter 5 Chemical weighing tank 6 Timer 8 Metering pump

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-92621 (JP, A) JP-A-59-188923 (JP, A) JP-A-5-53241 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) H01L 21/304

Claims (1)

(57) [Claims] 1. A mixture of aqueous ammonia, aqueous hydrogen peroxide and water
A method of cleaning a semiconductor device using a liquid, wherein an additional amount v of ammonia water at a processing time T and an elapsed time t is calculated by (Equation 1). (Equation 1)