JP3158311B2 - Replenishment method of liquid mixture and semiconductor - 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 of replenishing a mixture of chemicals, and more particularly to a method of replenishing a mixture of a plurality of chemicals which react with each other when mixed and at least one of which evaporates. The method for replenishing a drug solution and the method for replenishing the drug solution
The present invention relates to a semiconductor that has been cleaned by cleaning .

[0002]

2. Description of the Related Art Sulfuric acid is used as a wafer cleaning liquid to remove organic substances attached to a semiconductor wafer (typically, peeling-off of a photoresist film), inorganic substances (metals, etc.), and fine particles called particles. A mixed solution of hydrogen oxide water is often used. Originally, sulfuric acid alone has a cleaning effect, but when mixed with a hydrogen peroxide solution, the following reaction occurs. As a result, caroic acid H2 SO5 is generated, and a strong cleaning effect can be obtained. 2H2 SO4 + H2 O2 → H2 SO4 + H2 SO5 + H
2 O (this reaction is a reversible reaction)

[0003] That is, since caroic acid H2SO5 is a strong oxidizing agent, it reacts strongly with organic substances and the like to have the effect of decomposition and removal. Therefore, in order to generate such caloic acid H2 SO5, sulfuric acid is mixed with hydrogen peroxide to form a cleaning solution. In addition to caloic acid H2 SO5, sulfuric acid H2 SO4 and hydrogen peroxide H2 O2 have a cleaning effect. Caroic acid H2 SO
The effect of 5 is the strongest.

In a mixed solution of sulfuric acid and hydrogen peroxide, hydrogen peroxide evaporates immediately after the mixing is started, and the concentration of hydrogen peroxide decreases. When the concentration of hydrogen peroxide decreases, the cleaning power decreases. This is because hydrogen peroxide H2 O2 is an unstable substance that is easily decomposed, and when hydrogen peroxide H2 O2 is decomposed, water H2 O remains, and water increases with the passage of time. This is because the concentration of the acid H2 SO5 decreases. Therefore, it is necessary to replenish the hydrogen peroxide solution. And the conventional replenishment of hydrogen peroxide solution,
As shown in FIG. 4, replenishment of the hydrogen peroxide solution for a certain time width t5 has been performed by repeating at a constant cycle t6. The time width t5 and the cycle t6 do not change in the related art until the mixed liquid is discharged after the mixing of the mixed liquid is started.

[0005]

However, according to the chemical replenishing method shown in FIG. 4, the cleaning power of the mixed solution cannot be kept constant, and the cleaning power has a large change with time. Then, when the cause was investigated, the following became clear. Fig. 5 shows the mixed solution (sulfuric acid and hydrogen peroxide) when replenishment is performed by the conventional method.
The graph shows the change in the concentration of sulfuric acid and hydrogen peroxide in the hydrogen peroxide solution. Although the average replenishment rate of the hydrogen peroxide solution per unit time was constant (0.45 liter / hour), The change in concentration is large, and although the concentration was as high as 3 wt% at the beginning, it is reduced to less than 2 wt%, where it calms down. That is, even if the cleaning power is initially strong, the hydrogen peroxide concentration is reduced, so that the cleaning power is reduced.

FIG. 6 shows a change in the concentration of hydrogen peroxide when no replenishment of the aqueous solution of hydrogen peroxide was performed with respect to the aqueous solution of sulfuric acid. That is, immediately after the start of mixing, the liquid temperature rises due to the heat of hydration of sulfuric acid. Then, about 30 minutes after the mixing, the liquid temperature reaches around 125 ° C., after which a decomposition reaction of hydrogen peroxide occurs, and the hydrogen peroxide concentration drops sharply. The rate of decrease can be seen from the slope of the concentration curve. As described above, when the liquid temperature reaches a certain stage, the hydrogen peroxide decomposition reaction becomes intense thereafter, and the hydrogen peroxide concentration drops sharply. A time zone in which the hydrogen peroxide decomposition reaction is intense immediately after starting the mixing is referred to as a mixing initial time zone.

However, the decomposition of hydrogen peroxide does not always proceed violently, and the amount of decomposition of hydrogen peroxide is reduced from a certain stage and is stabilized. As is clear from the concentration change diagram in the conventional example shown in FIG. 5, the amount of hydrogen peroxide decomposed decreases from about 80 minutes after the completion of the temperature rise. The time zone in which the hydrogen peroxide decomposition amount is reduced is referred to as a consumption stabilization time zone. Therefore, during a certain time after the start of mixing the sulfuric acid and the hydrogen peroxide solution and heating, that is, during the initial mixing time period, the consumption of hydrogen peroxide is severe, but after the elapse of the time,
That is, during the consumption stabilization time period, the consumption of hydrogen peroxide becomes intense. Nevertheless, in the past, the hydrogen peroxide concentration could not be kept constant because the average amount of chemical replenishment per unit time was always kept constant. It turns out that it was.

In the conventional example shown in FIG. 5, the replenishment amount is determined based on the consumption amount of hydrogen peroxide during the consumption stabilization time period, that is, the replenishment condition is selected from the situation after the initial mixing time period. As a result, the intense consumption of hydrogen peroxide during the initial period of mixing could not be replenished, and eventually the hydrogen peroxide concentration of the sulfuric acid peroxide became low, eventually stabilizing at a low value, and the cleaning power could not be sufficiently increased. . Also, if the replenishment conditions were set so as to replenish the depleted amount in the initial mixing period, the replenishment amount of the hydrogen peroxide solution after the initial mixing period became excessive, and the sulfuric acid became low. Is undesirably reduced.

The present invention has been made to solve such a problem, and replenishes a mixture of a plurality of chemicals which react with each other and evaporate at least one of them when they are mixed. In the method of replenishing a mixed solution, the object is to enable replenishment so that the composition ratio of the solution is always substantially constant.
Detergency of washing that is always washed with uniform washing power by the washing method
The purpose is to provide a strong semiconductor .

[0010]

According to a first aspect of the present invention, there is provided a method for replenishing a mixed solution, wherein the average amount of the replenished solution per unit time is large during the initial mixing period when the mixed solution is rapidly evaporated. It is characterized in that the chemical solution is replenished under the condition that the average amount of the chemical solution replenished per unit time is reduced during the consumption stable time period in which the evaporation of the liquid is relatively small. In the method of replenishing a mixed solution according to claim 2, the replenishment of a certain time width is repeated at certain time intervals to perform the chemical solution, and the average replenishment amount per unit time is changed according to the time width and the time interval. It is characterized by. In the semiconductor according to the third aspect, the chemical solution of the mixed solution is rapidly evaporated.
Average liquid replenishment per unit time during new initial mixing period
Consumption is relatively large and the subsequent evaporation of the chemical solution is relatively small.
Low average replenishment rate per unit time during fixed hours
It is characterized by replenishing the solution under the following conditions and washing.

[0011]

According to the method for replenishing a chemical solution of the mixed liquid according to the first aspect, the replenishment of the chemical solution is increased by increasing the average amount of the chemical solution replenished per unit time during the initial mixing period when the evaporation of the chemical solution is intense. When this happens, the average chemical replenishment amount per unit time is reduced, so that the composition ratio of the chemical can be kept substantially constant from beginning to end. According to the method of replenishing a mixed solution of claim 2, the replenishment time and the replenishment cycle can be used to easily determine the average replenishment amount per unit time, for example, by controlling the replenishment pump using an electronic circuit. It is possible to switch between the mixing initial time zone and thereafter.
According to the semiconductor of the third aspect, the chemical solution of the mixed solution evaporates intensely.
Average replenishment volume per unit time during initial mixing period
Consistent consumption, with relatively little evaporation of the chemical afterwards
During the time period, the average replenishment volume per unit time decreases.
Cleaning was performed under the following conditions, so it was always constant during cleaning
Cleaning power, and the degree of cleaning varies.
A solid semiconductor can be provided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for replenishing a mixed solution according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example of a cleaning apparatus used for carrying out the method of replenishing the mixed solution with a chemical solution. In the drawing, 1 is a liquid tank, 2 is a reflux path, and a liquid tank 1
And the mixture is refluxed into the liquid tank 1. Reference numeral 3 denotes a pump provided in the reflux path, 4 denotes a damper, and 5 denotes a filter. 6a is a sulfuric acid tank, 6b is a hydrogen peroxide solution tank, and the chemicals in each tank 6a, 6b are supplied to the liquid tank 1 through replenishment lines 7a, 7b.

Numerals 8a and 8b denote pumps provided in the replenishment lines 7a and 7b, which are controlled and operated by an electronic circuit (not shown) to mix and discharge the chemicals.
Replenishment can be performed. Reference numeral 9 denotes a heater for increasing the temperature of the mixed solution to a predetermined temperature.

FIG. 2 is a time chart showing one embodiment of the method for replenishing a mixed solution of the present invention. In the method of replenishing the mixed solution with the chemical solution, sulfuric acid is replenished for a time width t1 within the initial mixing time zone x in which the hydrogen peroxide evaporates violently (time x after completion of the temperature rise, for example, until 80 minutes have elapsed). It repeats every time the time interval (cycle) t2 elapses, and in the consumption stable time zone after the elapse of the mixing initial time zone x, the time width t3
Is repeated each time the time interval t4 elapses, so that the average chemical solution replenishment amount per unit time is different in the mixing initial time zone and every elapse of the mixing initial time zone. x indicates the time from the start of mixing to the end of the initial mixing time zone after the end of the temperature rise.

That is, the average replenishing amount of the chemical per unit time in the mixing initial time zone x is set to a large value corresponding to the violent evaporation. Then, after the elapse of the initial mixing time zone x, that is, when the consumption stabilization time zone is entered, the average chemical solution replenishment amount per unit time is reduced by the smaller amount of hydrogen peroxide evaporated. Then, as shown in FIG. 3, the hydrogen peroxide concentration can be made to be a substantially constant value throughout.

In the time chart (t1 or t2) in the time chart of FIG. 2, the hydrogen peroxide is replenished by operating the pump 8b under the control of the electronic circuit. By changing the pulse period and the pulse period, the average replenishing amount of the chemical per unit time can be easily changed.

In the above embodiment, after the sulfuric acid / hydrogen peroxide was prepared,
Although only the replenishment of the hydrogen peroxide solution is performed, the sulfuric acid concentration can be kept constant by appropriately replenishing the sulfuric acid. By the way, the present invention is not only a method for replenishing hydrogen peroxide with ammonium hydroxide NH4 OH + hydrogen peroxide H2 O2 + water H2 O, but also a method for replenishing hydrogen peroxide with hydrochloric acid HCl + hydrogen peroxide H2 O2 + water H2 O. It can be applied to the replenishment method. That is, the present invention can be generally applied to a method of replenishing a mixture of a plurality of chemicals which react with each other when mixed and at least one of which evaporates to replenish the evaporated liquid.

[0018]

According to the method for replenishing a mixed solution of chemicals according to the first aspect of the present invention, the average amount of replenished chemical per unit time is large during the initial mixing period when the mixed solution is rapidly evaporated. It is characterized in that the chemical solution is replenished under the condition that the average amount of the chemical solution replenished per unit time is reduced in a time zone that is extremely small. Therefore, according to the method for replenishing a mixed solution according to the first aspect, the replenishment of the chemical is increased by increasing the average amount of the replenished solution per unit time during the initial mixing period when the evaporation of the chemical is intense, and the evaporation of the chemical is reduced. In this case, the average replenishing amount of the chemical per unit time is reduced, so that the composition ratio of the chemical can be kept substantially constant throughout.

According to a second aspect of the present invention, in the method for replenishing a mixed solution, the replenishment for a certain time width is repeated at certain time intervals to perform the chemical solution, and the average replenishing amount per unit time is determined by the time width and the time interval. It is characterized by being changed. Therefore, according to the method for replenishing a mixed solution according to the present invention, the average replenishing amount per unit time can be easily controlled by a replenishing time and a replenishing cycle, for example, by controlling a replenishing pump using an electronic circuit. Can be switched between the mixing initial time zone and thereafter.

According to a third aspect of the present invention, the semiconductor of the mixed solution is evaporated.
The average chemical per unit time during the initial mixing
Supply is large, and the evaporation of the chemical after that is relatively small.
During the wear stabilization period, the average replenishment rate per unit time is small.
It is characterized by cleaning with replenishment of chemicals under the condition that disappears
You. Therefore, according to the semiconductor of the third aspect, the chemical liquid of the mixed liquid is used.
In the initial period of mixing when the evaporation of
The supply of chemicals is large, and the evaporation of chemicals is relatively small after that.
Average replenishment per unit time during stable consumption time
Replenishment was performed under conditions where the amount was small, and cleaning was performed.
It can be washed with a constant detergency during cleaning,
A semiconductor having no variation in the degree of cleaning can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a cleaning apparatus that can be used for performing a method of replenishing a mixed solution of the present invention.

FIG. 2 is a time chart showing one embodiment of a method for replenishing a mixed solution of the present invention.

FIG. 3 is a concentration change diagram showing a concentration change of hydrogen peroxide and sulfuric acid in a mixed solution (sulfuric acid / hydrogen peroxide) in the above embodiment.

FIG. 4 is a time chart showing a conventional example of a method of replenishing a mixed solution with a chemical solution.

FIG. 5 is a concentration change diagram showing a concentration change of hydrogen peroxide and sulfuric acid in a mixed solution (sulfuric acid / hydrogen peroxide) for explaining a problem in the conventional example.

FIG. 6 is a concentration change diagram showing changes in concentrations of hydrogen peroxide and sulfuric acid in a mixed solution (sulfuric acid / hydrogen peroxide) without replenishment.

Claims (3)

(57) [Claims] 1. A method of replenishing a mixture of a plurality of chemicals which react with each other when mixed and at least one of which evaporates is replenished with the evaporating chemical. Replenish the chemical under the condition that the average chemical replenishment volume per unit time is large during the intense mixing initial time zone, and the average chemical replenishment volume per unit time decreases during the consumption stabilization time when the chemical solution evaporation is relatively small thereafter. For replenishing a mixture with a chemical solution 2. The method according to claim 2, wherein the replenishment of a certain time width is repeated at certain time intervals to perform the liquid medicine, and an average liquid medicine replenishment amount per unit time is changed according to the time width and the time interval. Replenishment method of the described mixture 3. When mixed, they react with each other and at least
Half washed with a mixture of several chemicals, one of which evaporates
In the conductor, during the mixing initial time zone when the chemical solution of the mixed solution is strongly evaporated
Has a large average replenishment rate per unit time,
Unit time during the consumption stabilization time period where the chemical solution evaporates relatively little
Replenish the solution under the condition that the average
Semiconductor characterized by being cleaned