JP2001244322A - Wafer storage and storing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer storage for eliminating particles and chemical contaminant speedily and a storing method. SOLUTION: A storage comprises a housing 1, circulating air ducts 3, 4, 5, and 6 with a ventilator 8 for circulating gas in the housing 1, a wafer storage part 2 which has a door 7 for opening and closing in the circulating air ducts, a particles eliminating part 10 in the circulating air ducts for eliminating particles in circulating gas, and a chemical contaminant eliminating part 9 in the circulating air duct for eliminating chemical contaminant in circulating gas. The gas passes from upper to lower part of the wafer storage at a velocity of about more than 0.3 m/s.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer stocker and a stocking method for storing a wafer or a wafer case holding the wafer (hereinafter, referred to as a wafer including both) in the semiconductor field.

[0002]

2. Description of the Related Art In the field of semiconductor manufacturing, it is important to keep a wafer clean from fine particles, chemical contamination and the like. In a semiconductor manufacturing process, it is necessary to temporarily store a wafer, and a wafer stocker is used as a storage place. Conventional wafer stockers do not particularly have facilities for decontamination or have HEPA or ULPA filters installed for dust removal.

[0003] In recent years, chemical contamination has become a problem in the semiconductor manufacturing process, and it has been found that various types of chemical contaminants are generated and present in clean rooms. These chemical contaminations are generated from chemical substances used for walls, ceilings, floors, etc., which are clean room constituent materials, chemicals used in a semiconductor manufacturing process, and reactants thereof. In order to keep the stored wafers clean from these chemical contaminations, for example, Japanese Patent Application Laid-Open No. H11-238787 proposes a wafer stocker equipped with a chemical filter for removing chemical contaminants and through which the atmosphere circulates.

[0004]

However, the above-mentioned wafer stocker is carried into the wafer stocker because the opening area of the circulation path is small and the wind speed is about the same as or less than that of a clean room, for example, 0.2 m / s. When the wafer is contaminated, there is a disadvantage that dust and chemical contaminants are not quickly removed. Further, if the removal of the contamination is not rapid, the contamination may remain in the circulating airflow, accumulate, and conversely contaminate the wafer carried into the wafer stocker.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a wafer stocker for quickly removing fine particles and chemical contaminants, and a stocking method thereof.

[0006]

SUMMARY OF THE INVENTION A wafer stocker according to the present invention has a housing, a circulating air passage having a blower for circulating gas in the housing, and a circulating air passage having an openable / closable door. A wafer storage unit interposed in the circulating air passage, a particle elimination unit interposed in the circulating air passage for removing fine particles in the circulating gas, and a chemical contaminant removing unit interposed in the circulating air passage for removing the chemical contaminants in the circulating gas. The gas passes through the wafer storage unit from above to below at a speed of about 0.3 m / s or more.

A wafer stocker according to the present invention comprises:
A gas ionization section for ionizing gas is interposed in a circulation air passage.

[0008] The wafer stocker according to the present invention comprises:
It has a detection unit that detects the opening and closing of the door of the wafer storage unit, and increases the wind speed for a certain period of time after the opening and closing of the door.

Further, the wafer stocker according to the present invention comprises:
The housing is provided with an outside air intake having a particulate removing section and a chemical pollutant removing section.

[0010] The wafer stocker according to the present invention comprises:
The outside air intake is opened only when the wafer storage unit is under a negative pressure.

Further, in the stock method according to the present invention, a step of circulating a gas through a path including a wafer storage section in a housing, a step of removing fine particles in the circulating gas, and a step of removing chemical contaminants in the circulating gas. And the gas passes through the wafer storage unit from above to below at a speed of about 0.3 m / s or more.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows an embodiment.
FIG. 2 is a front sectional view showing the configuration of the wafer stocker according to the first embodiment, FIG. 2 is a side sectional view showing the configuration of the wafer stocker according to the first embodiment, and FIG. 3 is a plan view showing the configuration of the wafer stocker according to the first embodiment. In the figure, 1 is a housing,
Reference numeral 2 denotes a wafer storage unit which is set to a clean atmosphere by a downflow airflow flowing downward from above. 3 to 6
Is a circulation air passage for achieving a downflow airflow in the wafer storage unit 2. Reference numeral 3 denotes a circulating air passage above the wafer storage unit 2, 4 denotes a circulating air passage below the wafer storage unit 2, 5 denotes a circulation air passage on the side surface of the wafer storage unit 2, and 6 denotes a wafer storage unit 2.
A high-speed downflow airflow is achieved by making the opening area large by using the peripheral portion of the wafer storage section 2 in the circulation air path on the back surface of the wafer. Reference numeral 7 denotes a door provided in the wafer storage unit 2 for loading and unloading wafers, and a wafer storage unit 2.
Can be sealed. Reference numeral 8 denotes a blower capable of changing the wind speed. When the wind speed increases, the gas circulates at a speed of 0.3 to 10 m / s, which is higher than the wind speed of a general clean room. Circulate gas with s. Reference numeral 9 denotes a chemical filter as a chemical contaminant removing unit, which has a honeycomb structure such as Kondo Kogyo's Cleansorb II having a small pressure loss and using activated carbon fibers.
It is desirable that the amount of adsorption by the path is large. Numeral 10 denotes a filter for removing fine particles as a fine particle removing section.
A or ULPA filters are used. Reference numeral 11 denotes an ionizer serving as a gas ionization unit, and reference numeral 12 denotes a grid-like floor plate provided below a case 13 for holding a wafer. 1
Reference numeral 4 denotes an outside air intake provided in the upper part of the housing 1 and has a chemical filter 9 and a filter 10 for removing fine particles. Reference numeral 15 denotes a wafer carry-in detector, which is provided around the door 7 and sends a signal to the blower 8 when the wafer carry-in is detected, and increases the downflow airflow for a certain period after carrying in.

Next, the operation will be described. The blower 8 circulates gas, that is, air, so as to form a uniform downflow airflow in the wafer storage unit 2, and its wind speed is generally about 0.3.
m / s. This is because the downflow airflow is suitable for quickly removing the contamination of the wafer, and the airflow of less than 0.3 m / s has a small effect of removing the contamination by the airflow. The airflow sent from the blower 8 passes through the particulate removal filter 10 and the chemical filter 9 to remove fine particles and chemical contaminants, and flows into the wafer storage unit 2 as a clean gas. Remove contamination. The airflow from which the contamination of the wafer has been removed returns to the blower 8 via the circulation air passages 3 to 6 via the grid-like floor plate 12 having a small pressure loss.

In the first embodiment, the downflow airflow is 0.3 m / s and the wind speed is relatively high, so that the contamination of the wafer can be removed quickly. May be charged. Therefore, in the first embodiment, as shown in FIG.
Is installed. The ionizer 11 ionizes gas in a polarity opposite to that of the charging by the downflow airflow, thereby preventing the charging of the wafer. Further, the gas ionized by the ionizer 11 may be adsorbed by passing through the filter 10 for removing fine particles and the chemical filter 9. Therefore, as for the installation position of the ionizer 11, the upper part of the wafer in the wafer storage part 2 is most suitable as shown in the figure.

Next, the time when a wafer is loaded will be described. Wafer carry-in is detected by the wafer carry-in detector 15, and the blower 8 receives a signal from the wafer carry-in detector 15 and changes the wind speed for a certain period of time, for example, about 10 minutes, to any wind speed of 0.3 to 10 m / s. To increase. This quickly removes contamination of the wafer. When the concentration of a wafer is reduced to a certain level or less, the progress of the removal of the contamination is slower than the wind speed. Therefore, in the first embodiment, in consideration of economy and the like, only 0.3 to 1 for 10 minutes after the wafer is loaded.
It increases to 0m / s wind speed and 0.3m after 10 minutes
/ s was reduced to wind speed.

In the first embodiment, since the outside air intake 14 is normally closed, the housing 1 is in a closed state. For this reason, the gas flowing through the circulation air passage is highly purified by passing through the particulate removal filter 10 and the chemical filter 9 a plurality of times. However, if the sealing of the wafer stocker is not perfect, outside air containing contaminants may enter the wafer stocker and contaminate the highly purified gas. Therefore, in the first embodiment, a pressure gauge (not shown) is provided in the wafer storage unit 2,
The differential pressure between the wafer storage unit 2 and the outside air is detected, and the wafer storage unit 2 is detected.
The outside air intake 14 is opened only when the inside has a negative pressure.

As a result, outside air is taken in only through a minimum necessary time through the filter 10 for removing fine particles and the chemical filter 9, so that the gas inside the wafer stocker can be highly purified.

Next, the difference from the conventional apparatus will be compared by actually using the wafer stocker of the first embodiment. First, the door 7 of the wafer stocker installed in the clean room is opened to make the contamination level substantially equal to that of the clean room atmosphere. After that, the Si wafer is set in the case 13, and without installing the chemical filter 9 and the particulate removal filter 10,
After circulating gas in a sealed state at a low wind speed of 7 m / s and leaving the wafer for 2 hours, the amount of organic contaminants adhering to the wafer is determined by thermal desorption-GC / MS (Gas Chromatography / Mass Spectrome).
try). Next, after installing a chemical filter 9 and circulating gas for 2 hours, the wafer was set and left in a circulating gas stream for 2 hours to measure the amount of organic substances on the wafer.

Next, once the door 7 of the wafer stocker is opened, the wind speed is increased to 0.3 m / s, and when the chemical filter 9 and the filter 10 for removing fine particles are not installed, the wafer when the chemical filter 9 is installed is set. The amount of adhered contamination was measured. Table 1 shows the results.

[0020]

[Table 1]

From the results, it is clear that the high wind speed has a higher removal rate of organic contaminants than the low wind speed, and the effect of removing the contamination by increasing the speed of the wafer stocker is shown. In addition, the amount of organic matter has been reduced to one-fourth by circulating the atmosphere through a chemical filter for 2 hours. By installing a chemical filter in the atmosphere circulation path and sealing the wafer stocker, the amount of contamination on the wafer is reduced. It's clear what you can do.

[0022]

Thus, according to the wafer stocker of the present invention, a circulation air passage having a housing, a ventilation device for circulating gas in the housing, and a door that can be opened and closed is provided. A wafer storage unit interposed in the circulating air passage, a particle elimination unit interposed in the circulating air passage for removing fine particles in the circulating gas, and a chemical contaminant removing unit interposed in the circulating air passage for removing the chemical contaminants in the circulating gas. Since the gas passes through the wafer storage unit from above to below at a speed of about 0.3 m / s or more, it is possible to quickly remove fine particles and chemical contaminants.

Further, according to the wafer stocker according to the present invention, the gas ionizer for ionizing the gas is interposed in the circulation air passage, so that the wafer can be prevented from being charged.

Further, according to the wafer stocker of the present invention, since the detection unit for detecting the opening / closing of the door of the wafer storage unit is provided, and the wind speed is increased for a certain time from the opening / closing of the door, the speed is quickly and economically increased. Wafer decontamination can be performed.

According to the wafer stocker according to the present invention, since the housing is provided with the outside air intake having the fine particle removing portion and the chemical contaminant removing portion, the wafer is stored even when the housing is not completely sealed. The gas inside the stocker can be kept clean.

Further, according to the wafer stocker of the present invention, the outside air intake is opened only when the wafer storage section is under a negative pressure, so that the gas inside the wafer stocker can be kept at a higher level.

Further, according to the stock method of the present invention, a step of circulating a gas through a path including a wafer storage unit in a housing, a step of removing fine particles in the circulating gas, and a step of removing chemical contaminants in the circulating gas. Removing the gas from the upper part to the lower part of the wafer storage part at a speed of about 0.3 m / s or more, so that the particulates and chemical contaminants can be removed quickly.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a configuration of a wafer stocker according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing a configuration of a wafer stocker according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a configuration of a wafer stocker according to the first embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 housing, 2 wafer storage unit, 3, 4, 5, 6 circulation air passage, 7 door, 8 blower, 9 chemical filter, 1
0 Filter for removing fine particles, 11 Ionizer, 12
Floor plate, 13 cases, 14 outside air intake, 15 wafer loading detector

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hiroshi Kurokawa, Inventor 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsui Electric Co., Ltd. (72) Inventor Akemi Ueyama 2-3-2, Marunouchi, Chiyoda-ku, Tokyo Rishi Electric Co., Ltd. F term (reference) 3L058 BD01 BE02 BF01 BG03 5F031 CA02 DA08 DA17 FA01 FA03 NA03 NA13 NA16 NA17 NA18 PA26

Claims (6)

[Claims] 1. A housing, a circulating air passage having a blower for circulating gas in the housing, a wafer storage unit having an openable / closable door and interposed in the circulating air passage, and A particle removing unit interposed in the air passage for removing fine particles in the circulating gas; and a chemical contaminant removing unit interposed in the circulating air passage for removing a chemical contaminant in the circulating gas, wherein the gas is stored in the wafer storage. A wafer stocker that passes through the portion from above to below at a speed of about 0.3 m / s or more. 2. The wafer stocker according to claim 1, wherein a gas ionizer for ionizing gas is interposed in the circulation air passage. 3. The wafer stocker according to claim 1, further comprising a detection unit for detecting whether the door of the wafer storage unit is opened or closed, and increasing the wind speed for a predetermined time from when the door is opened or closed. 4. The wafer stocker according to claim 1, wherein the housing is provided with an outside air intake having a particulate removing section and a chemical pollutant removing section. 5. The wafer stocker according to claim 4, wherein the outside air intake is opened only when the wafer storage section is under a negative pressure. 6. A method comprising: circulating a gas in a path including a wafer storage unit in a housing; removing fine particles in the circulating gas; and removing a chemical contaminant in the circulating gas. A stock method, wherein the gas passes through the wafer storage section from above to below at a speed of about 0.3 m / s or more.