US20060042756A1

US20060042756A1 - Semiconductor manufacturing apparatus and chemical exchanging method

Info

Publication number: US20060042756A1
Application number: US11/211,748
Authority: US
Inventors: Kunihiro Miyazaki; Takashi Higuchi; Toshiki Nakajima
Original assignee: Individual
Current assignee: Toshiba Corp; Seiko Epson Corp
Priority date: 2004-08-27
Filing date: 2005-08-26
Publication date: 2006-03-02
Also published as: CN1741249A; KR100693238B1; KR20060050557A; TWI279833B; CN100390932C; JP2006066727A; TW200625390A

Abstract

A semiconductor manufacturing apparatus for cleaning a semiconductor substrate comprises a high-temperature circulation type chemical bath which is filled with a chemical to be used for cleaning of a semiconductor substrate and in which the chemical is circulated and reused, a draining mechanism which drains the chemical in the chemical bath therefrom, an auxiliary fluid supplying mechanism which adds to the drained chemical regarded as a waste chemical an auxiliary fluid, and thereby heats the waste chemical, a heat exchanger in which the heated waste chemical is stored temporarily and a new chemical is allowed to flow, and which cools the waste chemical and raises temperature of the new chemical by heat exchange, and a pipe in which the new chemical having the temperature raised in the heat exchanger is supplied to the chemical bath.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2004-248970, filed Aug. 27, 2004, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to a semiconductor manufacturing apparatus in which a semiconductor substrate is cleaned by use of a high-temperature circulation type chemical bath and a chemical exchanging method for exchanging chemicals in the high-temperature circulation type chemical bath.
2. Description of the Related Art
Various types of method for cleaning a semiconductor substrate have been proposed. When a high-concentration g chemical is used, a system of repeatedly circulating and using chemicals for cleaning of a semiconductor substrate is adopted. In this circulation system, chemicals particularly heated for use are generally a mixture of sulfuric acid and hydrogen peroxide solution, a phosphoric acid solution, a mixture of hydrochloric acid and hydrogen peroxide solution, and a mixture of ammonia and hydrogen peroxide solution.
If chemicals are well used in a circulation system in which a semiconductor substrate are repeatedly cleaned with the same chemicals, impurities are dissolved in the chemicals or a reaction among the chemicals proceeds relative to initial concentration and, as a result, concentration of the chemicals is varied. For this reason, the chemicals need to be changed regularly or irregularly. When a high-temperature chemical is exchanged with a new chemical, a waste chemical valve provided at a pipe of a lowermost portion of a processing bath to drain the chemical therefrom. When cooling is necessary, an entire amount of chemical in the processing bath is temporarily stored in a cooling tank and then drained. When cooling is unnecessary, the chemical is drained as it is.
When draining an entire amount of chemical is ended, the waste chemical valve is closed and a new chemical is supplied to the processing bath. After the amount of chemical in the processing bath reaches the amount for circulation, a pump is operated and temperature of the chemical is raised by a heater. After the temperature is raised to a predetermined processing temperature, it is controlled at a constant temperature. Then, the temperature of the new chemical becomes the processing temperature and cleaning the semiconductor substrate is conducted again. In this case, the electric energy is required until the temperature of the new chemical is raised to the processing temperature at which the semiconductor substrate can be cleaned, and the processing needs to be waited during the temperature rise.
To solve these problems, a method of effectively using energy by raising the temperature of the new chemical by use of the chemical (waste chemical) to be drained from the processing bath has been proposed (Jpn. Pat. Appln. KOKAI Publication No. 2000-266496). In this method, the temperature of the new chemical to be supplied to the processing bath can be raised by conducting heat exchange between the high-temperature waste chemical and the new chemical by a heat exchanger. Thus, electric energy can be reduced and the time to raise the temperature of the new chemical to the processing temperature can be shortened.
However, this kind of method has a problem. The method of Jpn. Pat. Appln. KOKAI Publication No. 2000-266496 is heat exchange in a case where the fluid flow exists at any time. Specifically, this method relates to heat exchange in a system in which the inflow fluid (new chemical) to be supplied to the processing bath and the outflow fluid (waste chemical) to be drained from the processing bath flow simultaneously. Therefore, this method cannot be applied to a system of supplying the new chemical to the processing bath after making the processing bath completely empty. Moreover, there is another problem that the new chemical and the waste chemical may be mixed inside the processing bath.
In a general heat exchange system, the temperature of the new chemical is lower than that of the waste chemical (substantially equal to the temperature of the processing temperature). For this reason, the temperature of the new chemical cannot be raised to the processing temperature by conducting heat exchange alone. To further raise the temperature of the new chemical raised by heat exchange up to the processing temperature, electric energy is required.
As explained above, in the conventional semiconductor manufacturing apparatus in which a semiconductor substrate is cleaned by use of a high-temperature circulation type chemical bath, electric energy is required to raise the temperature of the new chemical to the processing temperature and the processing must be waited during the temperature rise of the new chemical. In addition, a method using heat exchange between the waste chemical and the new chemical has been proposed. In this method, however, the new chemical and the waste chemical may be mixed inside the processing bath. Moreover, the temperature of the new chemical cannot be raised to the processing temperature by heat exchange, and needs to be raised by the other means.

BRIEF SUMMARY OF THE INVENTION

An aspect of the present invention is a semiconductor manufacturing apparatus comprising: a high-temperature circulation type chemical bath which is filled with a chemical to be used for cleaning of a semiconductor substrate in a state that a temperature of the chemical is raised to a predetermined temperature, and in which the chemical is circulated and reused, a draining mechanism which drains the chemical in the chemical bath therefrom, an auxiliary fluid supplying mechanism which adds to the drained chemical regarded as a waste chemical an auxiliary fluid to generate heat by mixture with the waste chemical, and thereby heats the waste chemical, a heat exchanger in which the heated waste chemical is stored temporarily and a new chemical is allowed to flow, and which cools the waste chemical and raises temperature of the new chemical by heat exchange between the waste chemical and the new chemical, and a supply mechanism which supplies the new chemical having the temperature raised in the heat exchanger to the chemical bath.
Another aspect of the present invention is a semiconductor manufacturing apparatus comprising: a high-temperature circulation type chemical bath which is filled with a chemical to be used for cleaning of a semiconductor substrate in a state that a temperature of the chemical is raised to a first temperature, and in which the chemical is circulated and reused, a draining mechanism which drains the chemical in the chemical bath therefrom, an auxiliary fluid supplying mechanism which adds to waste chemical of second temperature lower than the first temperature of the drained chemical an auxiliary fluid to generate heat by mixture with the waste chemical, and thereby heats the waste chemical at third temperature higher than the first temperature, a heat exchanger in which the heated waste chemical is stored temporarily and a new chemical is allowed to flow, and which cools the waste chemical and raises temperature of the new chemical to the first temperature by heat exchange between the waste chemical and the new chemical, and a supply mechanism which supplies the new chemical having the temperature raised in the heat exchanger to the chemical bath.
Still another aspect of the present invention is, in a semiconductor manufacturing apparatus comprising: a high-temperature circulation type chemical bath which is filled with a chemical to be used for cleaning of a semiconductor substrate, and in which the chemical is circulated and reused after the cleaning, a method of exchanging the chemical in the high-temperature circulation type chemical bath, comprising draining the chemical in the chemical bath therefrom, adding to the drained chemical regarded as a waste chemical an auxiliary fluid to generate heat by mixture with the waste chemical, and thereby heating the waste chemical, temporarily storing the heated waste chemical in a heat exchanger, allowing a new chemical to flow in the heat exchanger, and cooling the waste chemical and raising temperature of the new chemical by heat exchange between the waste chemical and the new chemical in the heat exchanger, and supplying the new chemical having the temperature raised to the chemical bath.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a schematic diagram showing a semiconductor manufacturing apparatus according to a first embodiment of the present invention;
FIG. 2 is a cross-sectional view showing an inner structure of a heat exchanger used in the first embodiment shown in FIG. 1;
FIG. 3 is an illustration showing heat exchange in the heat exchanger of FIG. 2;
FIG. 4 is a schematic diagram showing a semiconductor manufacturing apparatus according to a second embodiment of the present invention; and
FIG. 5 is a graph showing variation in temperature of a diluted waste chemical in a case where water is added to sulfuric acid waste.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be explained below with reference to the accompanying drawings.

First Embodiment

FIG. 1 is a schematic diagram showing a semiconductor manufacturing apparatus according to a first embodiment of the present invention.
Reference numeral 11 denotes a processing bath (high-temperature circulation type chemical bath) employed for cleaning of a semiconductor substrate such as a Si wafer or the like. The processing bath 11 is filled with, for example, a sulfuric acid based high-temperature chemical 12. A semiconductor substrate 13 is dipped into the chemical 12 in the processing bath 11 and then cleaned.
The chemical 12 in the processing bath 11 is circulated by a pump (P) 14. In other words, the chemical is supplied from a bottom portion of the processing bath 11 by the pump 14, and the chemical spilling from a top portion of the processing bath 11 is supplied again from the bottom portion of the processing bath 11 through a chemical circuit. A heater (H) 15 which controls a temperature of the chemical and a filter (F) 16 through which particles are removed as impurities, are inserted into the chemical circuit. A small quantity of the chemical 12 in the processing bath 11 is circulated by the pump 14 and the temperature control and removal of particles are conducted by the heater 15 and the filter 16, during cleaning of the semiconductor substrate 13 or standby. A concentration monitor 17 is provided outside the processing bath 11 to measure concentration of the chemical 12.
A waste chemical valve 21 is provided between the pump 14 and heater 15 of the pipe at the lower most portion of the processing bath 11, for example, the chemical circuit. The chemical 12 in the processing bath 11 is drained by the valve 21. Furthermore, a new chemical is supplied to the processing bath 11 from a topside of the processing bath 11.
Specifically, when a time to exchange the chemical has come, operations of the pump 14 and heater 15 are stopped, the waste chemical valve 21 is opened, and the chemical is drained from the pipe at the lowermost portion of the processing bath 11. When an entire amount of chemical is drained, the waste chemical valve 21 is closed and a new chemical is supplied to the processing bath 11. After the amount of the chemical 12 in the processing bath 11 reaches the amount for circulation, the pump 14 is operated, and the temperature of the chemical 12 is raised by the heater 15. After the temperature is raised up to the predetermined temperature, the temperature is controlled at a constant temperature. When the temperature becomes a predetermined processing temperature (processing temperature), cleaning the semiconductor substrate 13 is conducted again.
The basic structure explained above is the same as the prior art. Besides this, a heat exchanger 31 which conducts heat exchange between the waste chemical drained from the processing bath 11 and the new chemical supplied to the processing bath 11, and a water adding mechanism 32 which adds water to the waste chemical as an auxiliary fluid to raise the temperature of the waste chemical, are provided in the present embodiment.
In other words, the heat exchanger 31 is provided in the waste chemical system of the high-temperature circulation type chemical bath such that the chemical (waste chemical) drained from the processing bath 11 via the valve 21 is supplied to the heat exchanger 31. The waste chemical supplied to the heat exchanger 31 is temporarily stored in the heat exchanger 31 and finally discharged to outside from a valve 23. On the other hand, the new chemical is supplied to the heat exchanger 31 via a valve 24 and heated by the heat exchanger 31. The new chemical having temperature raised by the heat exchanger 31 is supplied to the processing bath 11. The water adding mechanism 32 adds water to the waste chemical which is to be supplied to the heat exchanger 31, by opening a valve 22, such that the temperature of the waste chemical is raised by heat of dilution. Therefore, the waste chemical reacts with water and the temperature of the waste chemical is thereby raised. Thus, the waste chemical having temperature raised is supplied to the heat exchanger 31.
The heat exchanger 31 comprises a pipe 35 in which the waste chemical is temporarily stored and a new chemical pipe 36 provided in the pipe 35 as shown in FIG. 2 which illustrates an internal structure of the heat exchanger 31. Volume of the waste chemical side pipe 35 of the heat exchanger 31 is equal to or more than the volume of chemical in the processing bath 11. An outer wall of the pipe 35 is subjected to heat resistance. In other words, the chemical in the processing bath 11 can be entirely drained to the heat exchanger 31. When the processing bath 11 is made empty and the new chemical is supplied thereto, the waste chemical and the new chemical are not mixed inside the processing bath 11. The pipe of the new chemical supplying side does not need to have the same volume as the processing bath 11. A necessary amount of new chemical may be supplied to the processing bath 11 by opening or closing the supply-side valve 24 under on-off control as occasion requires, while monitoring the new chemical temperature inside the heat exchanger 31. To improve heat exchanger effectiveness, an agitator (not shown) may be provided at the pipe of the waste chemical side.
A waste chemical temperature monitor 37 is provided at a waste chemical outlet side of the heat exchanger 31. A new chemical temperature monitor 38 is provided at a new chemical outlet side of the heat exchanger 31.
The volume of water added to the waste chemical before heat exchange may be determined in accordance with a detected value of the concentration monitor 17.
Specifically, concentration of sulfuric acid in the chemical 12 may be detected by the concentration monitor 17 before draining the chemical in the processing bath 11 and the addition volume of water which can be diluted may be preliminarily considered on the basis of the detection result and set within this range.
When the chemical in the processing bath 11 is exchanged with the new chemical, in the above-described structure, operations of the pump 14 and heater 15 are first stopped, the valve 21 is opened, and an entire volume of chemical 12 in the processing bath 11 is drained and temporarily stored in the heat exchanger 31. At this time, to heat the waste chemical, the valve 22 is opened and a predetermined volume of water is added to the waste chemical. Thus, the temperature of the heat exchanger 31 to be supplied to the heat exchanger 31 is raised to be higher than the processing temperature. The volume of water added to the waste chemical can be adjusted by the monitors 37 and 38 shown in FIG. 2 while checking the temperatures of the waste chemical and new chemical. When an entire volume of chemical 12 is drained, the waste chemical valve 21 is closed.
Next, the valve 24 is opened and the new chemical is supplied to the processing bath 11 through the heat exchanger 31. The temperature of the new chemical supplied to the heat exchanger 31 is raised by heat exchange with the waste chemical, and the new chemical of raised temperature is supplied to the processing bath 11. Therefore, to raise the temperature of the new chemical to the processing temperature, electric energy consumption can be reduced or no electric energy needs to be consumed.
FIG. 3 illustrates heat exchange between the waste chemical and the new chemical in the heat exchanger 31. The temperature of the waste chemical supplied to the heat exchanger 31 is represented by T1, the temperature of the waste chemical discharged from the heat exchanger 31 is represented by T2, the temperature of the new chemical supplied to the heat exchanger 31 is represented by T2′, and the temperature of the new chemical discharged from the heat exchanger 31 is represented by T1′. On the principle of heat exchange, temperature T1′ cannot be higher than temperature T1. For this reason, if the waste chemical of lower temperature than the processing temperature is supplied to the heat exchanger 31 as it is, temperature T1′ becomes lower than the processing temperature and great temperature raising energy is required for the new chemical. In the present embodiment, temperature T1 is made higher than the processing temperature by preliminarily raising the temperature of the waste chemical with heat of dilution by addition of water. For this reason, temperature T1′ can be made higher up to the processing temperature.
Variation in the temperature of the diluted waste chemical in a case where water is added to the sulfuric acid waste, is shown in FIG. 5. A horizontal axis represents the concentration of sulfuric acid waste diluted after addition of water and a vertical axis represents the temperature of the waste chemical. This figure shows an example of variation in the temperature of diluted waste chemical in a case where water is arbitrarily added to 93% and 78% sulfuric acid wastes both having temperature of 100° C. In general, the concentration of the sulfuric acid waste used for semiconductor cleaning is approximately 80%. If water is added such that the concentration of the waste chemical becomes 75%, the temperature of the waste chemical can be raised by approximately 10° C. and heat exchange loss in the fluid heat exchanger can be compensated.
After the volume of the chemical in the processing bath 11 reaches the circulation volume by supply of the new chemical, the pump 14 is operated and the temperature of the chemical 12 is raised by the heater 15. After the temperature of the chemical 12 is raised to a predetermined temperature, it is controlled as a constant temperature. Thus, the temperature of the chemical 12 becomes the predetermined temperature and cleaning the semiconductor substrate 13 is conducted again.
As explained above, since high-concentration sulfuric acid solution is drained in the semiconductor cleaning step using high-temperature sulfuric acid, the temperature of the waste chemical to be supplied to the heat exchanger 31 can be made higher than the processing temperature used in circulation, by heat of dilution caused by water. For this reason, even if the heat exchanger effectiveness is poor, the temperature of the new chemical can be sufficiently raised up to, for example, circulation temperature (processing temperature). Therefore, new temperature raising energy for the new chemical can be reduced or no electric energy needs to be consumed. In this case, the heater 15 in the chemical circuit may be employed to keep the circulation temperature (processing temperature).
The waste chemical in the heat exchanger 31 is discharged to outside by opening the valve 23. Since this waste chemical is cooled by heat exchange with the new chemical, a cooling mechanism for cooling the waste chemical is unnecessary. Therefore, even if there is no heat resistance of the waste chemical pipe in a clean room, the waste chemical can be discharged without a cooling tank or the like.
After the cleaned semiconductor substrate 13 is taken out of the processing bath 11, the chemical deposited on the semiconductor substrate is sufficiently removed therefrom by use of ultrapure water, in a cleaning bath (not shown). Then, the semiconductor substrate 13 is dried and transferred to a next semiconductor manufacturing step. If impurities deposited on the semiconductor substrate 13 can hardly be removed therefrom with one chemical, the semiconductor substrate 13 is successively cleaned by conducting ultrapure water rinsing between cleaning steps using the chemical. Finally, after ultrapure water rinsing is conducted to sufficiently remove the chemical deposited on the semiconductor substrate therefrom, the semiconductor substrate is dried.
Moreover, when the waste chemical is exchanged for a new chemical, the substrate 13 is taken out of the processing bath 11, and after the exchange ends, it accommodates the substrate 13 in the processing bath 11.
According to the present embodiment, as described above, when the chemical in the processing bath 11 employed as the high-temperature circulation type chemical bath is exchanged, an entire volume of chemical 12 in the processing bath 11 is drained and stored in the heat exchanger 31, and the heat of the high-temperature waste chemical is supplied to the new chemical by the heat exchanger 31. Thus, electric energy to raise the temperature of the new chemical can be reduced and the circulation heating time for the temperature rise can be reduced.
Moreover, the temperature of the waste chemical to be used for heat exchange can be made further higher by adding water in the heat exchanger 31 and heating the waste chemical with heat of dilution. Particularly, since the concentration of sulfuric acid is high in the high-temperature circulation type chemical bath using sulfuric acid, heat of dilution caused by addition of water is great, which is very effective for the temperature rise. By raising the temperature of the waste chemical up to a sufficiently high temperature, new electric energy is not required when the new chemical is supplied. In addition, at the chemical exchange, an entire volume of chemical in the processing bath 11 is drained from the processing bath 11 and then the new chemical is supplied thereto. Thus, mixture of the new chemical and waste chemical in the processing bath 11 can be preliminarily prevented.
In other words, the temperature of the new chemical can be raised by heat exchange between the new chemical and waste chemical without mixing the new chemical and waste chemical in the processing bath 11, and further reduction of electric energy and reduction of the chemical exchange time can be achieved.

Second Embodiment

FIG. 4 is a schematic diagram showing a semiconductor manufacturing apparatus according to a second embodiment of the present invention. Elements like or similar to those disclosed in the first embodiment are denoted by similar reference numbers and are not described in detail here.
The present embodiment is different from the first embodiment in view of setting an addition amount of water by the water adding mechanism 32 on the basis of the measurement result of the concentration monitor 17. In addition, a valve 25 which does not allow the waste chemical to partially pass through the heat exchanger 31, but allows the waste chemical to be directly discharged, is provided between the waste chemical valve 21 and the heat exchanger 31. A valve 26 which does not allow the new chemical to partially pass through the heat exchanger 31, but allows the new chemical to be directly supplied to the processing bath 11, is provided at a new chemical side pipe of the heat exchanger 31.
In the present embodiment, too, the new chemical having temperature raised by the heat exchanger 31 can be supplied without mixture of the new chemical and waste chemical in the processing bath 11, similarly to the first embodiment.
In addition to this, the addition volume of water can be set in the following manners on the basis of the measurement result of the concentration monitor 17, in the present embodiment:
(1) The concentration of sulfuric acid is monitored in a system using high-temperature sulfuric acid, a desired temperature of the waste chemical is obtained empirically or experimentally such that the temperature of the new chemical to be raised in the heat exchanger 31 becomes the processing temperature, and the addition volume of water is determined such that the temperature of the new chemical can be raised to the temperature of the waste chemical. In this case, electric energy to raise the temperature of the new chemical is unnecessary. In other words, the temperature of the new chemical can be raised to the processing temperature by heat exchange alone.
(2) The concentration of sulfuric acid is monitored in a system using high-temperature sulfuric acid, and a necessary volume of water is determined on the basis of the relationship between the concentration of the waste chemical to be drained from the processing bath 11 and the predetermined concentration of the waste chemical. Recently, reducing as much discharge of the waste chemical out of factories as possible has been desired from the viewpoint of reduction of load on environment. For example, sulfuric acid is often recovered from a semiconductor manufacturing apparatus after discharging and used in other industrial fields as dilute sulfuric acid. In this case, sulfuric acid needs to be recovered in accordance with a certain degree of concentration.
In other words, generally, the sulfuric acid based waste chemical is not disposed of as industrial waste, but is often used for other industrial purposes. The concentration of sulfuric acid is desired to be constant. Thus, the addition volume of water is determined such that the concentration of sulfuric acid in the waste chemical becomes 75% on the basis of the measurement result of the concentration monitor 17. The waste chemical discharged by opening the valve 23 after heat exchange thereby contains sulfuric acid having concentration of 75%, and can be used for other purposes as it is.
If the concentration of the waste chemical is set at the above value, the temperature of the new chemical may not be raised to the processing temperature by the heat exchanger 31. The temperature of dilute waste chemical in case where water is added to 93% or 78% sulfuric acid waste having temperature of 100° C. is shown in FIG. 5. A vertical axis represents the temperature of the waste chemical and a horizontal axis represents the concentration of sulfuric acid waste diluted after addition of water. In general, the concentration of the sulfuric acid waste used for semiconductor cleaning is approximately 80%. The temperature of the waste chemical can be raised by approximately 10° C. by adding water such that the concentration of the waste chemical of approximately 100° C. becomes 75%. Heat exchange loss in the fluid heat exchanger can be thereby compensated. If the temperature of the new chemical does not reach the processing temperature, the new chemical may be heated by the heater 15 or other means. In this case, too, since the temperature of the new chemical has been raised to some extent by heat exchange, a small quantity of electric energy is only needed to raise the temperature up to the processing temperature.
If the temperature of the new chemical raised by the heat exchanger 31 is equal to or higher than the processing temperature, the temperature of a total volume of new chemical may become the processing temperature in the processing bath 11 by bypassing a small quantity of new chemical by the valve 26. Moreover, a small quantity of waste chemical may be preliminarily drained through the valve 21 and then the temperature of the new chemical may be raised to the processing temperature by the waste chemical which is heated by heat of dilution generated by mixture of remaining waste chemical and water.

Modified Embodiment

The present invention is not limited to the above-described embodiments. In the embodiments, water is used as an auxiliary fluid for the sulfuric acid based chemical used as a cleaning fluid and the waste chemical is heated by heat of dilution. However, combination of the chemical and the auxiliary fluid can be arbitrarily changed. For example, a chloric acid based chemical can be heated with heat of neutralization generated by adding an organic alkali thereto. An ammonium based chemical can be heated with heat of reaction generated by adding an organic acid thereto. However, a substance which is not deposited or precipitated inside the heat exchanger when the temperature is lowered, needs to be selected.
A position where the auxiliary fluid is added may be the pipe to enter the heat exchanger or in the heat exchanger. A relief valve (not shown) may be provided at the waste chemical side of the processing bath as a safety device. FIG. 2 shows only one chemical. However, if a mixture chemical containing two or more chemicals including pure water is used, the new chemical supply pipe may be arranged parallel to the heat exchanger 31 and temperatures of two or more chemicals may be simultaneously raised by heat exchange. A fluid such as hydrogen peroxide which is decomposed at high temperature may be supplied, at necessary amount, directly to the processing bath, without heat exchange.
As the semiconductor substrate cleaning, there are batch cleaning of dipping some semiconductor substrates into the processing bath containing the chemical and simultaneously cleaning them, and single wafer cleaning of blowing the chemical onto the semiconductor substrates while rotating them one by one. The present invention can be applied to any chemical circulation system using a high-concentration chemical even if the system is batch cleaning or single wafer cleaning.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Claims

1. A semiconductor manufacturing apparatus comprising:

a high-temperature circulation type chemical bath which is filled with a chemical to be used for cleaning of a semiconductor substrate in a state that a temperature of the chemical is raised to a predetermined temperature, and in which the chemical is circulated and reused;

a draining mechanism which drains the chemical in the chemical bath therefrom;

an auxiliary fluid supplying mechanism which adds to the drained chemical regarded as a waste chemical an auxiliary fluid to generate heat by mixture with the waste chemical, and thereby heats the waste chemical;

a heat exchanger in which the heated waste chemical is stored temporarily and a new chemical is allowed to flow, and which cools the waste chemical and raises temperature of the new chemical by heat exchange between the waste chemical and the new chemical; and

a supply mechanism which supplies the new chemical having the temperature raised in the heat exchanger to the chemical bath.

2. The apparatus according to claim 1, wherein volume of a pipe of the heat exchanger to the waste chemical is equivalent to or more than volume of the chemical supplied to the chemical bath.

3. The apparatus according to claim 1, wherein the auxiliary fluid generates heat of dilution, reaction or neutralization by mixture with the waste chemical.

4. The apparatus according to claim 1, wherein the chemical contains sulfuric acid, the auxiliary fluid is water and the chemical is heated with heat of dilution generated by mixture with the auxiliary fluid.

5. The apparatus according to claim 1, wherein the chemical contains hydrochloric acid, the auxiliary fluid is an organic alkali and the chemical is heated with heat of neutralization generated by mixture with the auxiliary fluid.

6. The apparatus according to claim 1, wherein the chemical contains at least ammonia, the auxiliary fluid is an organic acid and the chemical is heated with heat of reaction generated by mixture with the auxiliary fluid.

7. The apparatus according to claim 1, wherein an addition volume of the auxiliary fluid is set in accordance with temperature of the waste chemical required to raise temperature of the new chemical to a predetermined temperature in the heat exchanger.

8. The apparatus according to claim 1, further comprising a concentration gauge which measures concentration of at least one chemical in the chemical bath,

wherein an addition volume of the auxiliary fluid is determined in accordance with measurement result of the concentration gauge.

9. The apparatus according to claim 8, wherein the addition volume of the auxiliary fluid is determined in accordance with concentration measured by the concentration gauge such that temperature of the waste chemical is temperature required to raise the temperature of the new chemical to the predetermined temperature.

10. The apparatus according to claim 1, further comprising:

a chemical circuit which supplies a chemical overflowing from a top portion of the chemical bath, from a bottom portion of the chemical bath; and

a heater which is provided in a middle portion of the chemical circuit to raise temperature of a chemical to a predetermined temperature.

11. The apparatus according to claim 1, further comprising a pipe which allows the new chemical to bypass the heat exchanger.

12. The apparatus according to claim 1, further comprising another draining mechanism which allows a small quantity of waste chemical drained from the chemical bath not to be supplied to the heat exchange, but to be drained directly to outside.

13. A semiconductor manufacturing apparatus comprising:

a high-temperature circulation type chemical bath which is filled with a chemical to be used for cleaning of a semiconductor substrate in a state that a temperature of the chemical is raised to a first temperature, and in which the chemical is circulated and reused;

a draining mechanism which drains the chemical in the chemical bath therefrom;

an auxiliary fluid supplying mechanism which adds to the drained chemical regarded as a waste chemical of second temperature lower than the first temperature an auxiliary fluid to generate heat by mixture with the waste chemical, and thereby heats the waste chemical at third temperature higher than the first temperature;

a heat exchanger in which the heated waste chemical is stored temporarily and a new chemical is allowed to flow, and which cools the waste chemical and raises temperature of the new chemical to the first temperature by heat exchange between the waste chemical and the new chemical; and

14. A method of exchanging a chemical in a high-temperature circulation type chemical bath, comprising:

preparing a semiconductor manufacturing apparatus comprising the high-temperature circulation type chemical bath which is filled with a chemical to be used for cleaning of a semiconductor substrate, and in which the chemical is circulated and reused after the cleaning;

draining the chemical in the chemical bath therefrom;

adding to the drained chemical regarded as a waste chemical an auxiliary fluid to generate heat by mixture with the waste chemical, and thereby heating the waste chemical;

temporarily storing the heated waste chemical in a heat exchanger;

allowing a new chemical to flow in the heat exchanger, and cooling the waste chemical and raising temperature of the new chemical by heat exchange between the waste chemical and the new chemical in the heat exchanger; and

supplying the new chemical having the temperature raised to the chemical bath.

15. The method according to claim 14, wherein a fluid which generates heat of dilution, reaction or neutralization by mixture with the waste chemical is used as the auxiliary fluid mixed with the waste chemical.

16. The method according to claim 14, wherein an addition volume of the auxiliary fluid is set in accordance with temperature of the waste chemical required to raise temperature of the new chemical to a predetermined temperature in the heat exchanger.

17. The method according to claim 14, wherein concentration of at least one chemical in the chemical bath is measured and an addition volume of the auxiliary fluid is set in accordance with the measurement result.

18. The method according to claim 17, wherein the addition volume of the auxiliary fluid is set in accordance with the measured concentration of the chemical such that temperature of the waste chemical is temperature required to raise the temperature of the new chemical to the predetermined temperature.

19. The method according to claim 14, wherein a small quantity of the waste chemical drained from the chemical bath is drained directly to outside.

20. A method of manufacturing a semiconductor apparatus configured to house a semiconductor substrate in a high-temperature circulation type chemical bath which is filled with a chemical to be used for cleaning of a semiconductor substrate and in which the chemical is circulated and reused after the cleaning, and to clean the semiconductor substrate,

the method comprising:

draining the chemical in the chemical bath therefrom;

temporarily storing the heated waste chemical in a heat exchanger;

allowing a new chemical to flow in the heat exchanger, and cooling the waste chemical and raising temperature of the new chemical by heat exchange between the waste chemical and the new chemical in the heat exchanger;

supplying the new chemical having the temperature raised to the chemical bath; and

housing the substrate in the chemical bath in which chemicals are exchanged by draining the waste chemical and supplying the new chemical, and thereby cleaning the substrate.