JP5155848B2 - N2 purge device for FOUP - Google Patents

Description

The present invention relates to an N2 purge apparatus for FOUP used in a semiconductor manufacturing clean room.

At present, in a semiconductor manufacturing clean room, a mini-environment system is generally used in which a wafer is stored in a FOUP and transported and handled between semiconductor manufacturing apparatuses without being exposed to the outside air.

With the progress of miniaturization of semiconductor circuits, the current design rule is 32 nm.
As a result, the environment required for the semiconductor manufacturing process has become more severe, and it has become necessary for the atmosphere in the FOUP containing the wafer to completely remove moisture, chemical gas, and the like depending on the process steps.

A breath filter section is provided at the bottom of the FOUP. The breath filter is designed to make the FOUP internal pressure and the outside air pressure uniform when the atmospheric pressure changes during transportation, and to prevent the FOUP from expanding and contracting. The breath filter is also installed inside the breath filter. Is for preventing dust from entering the FOUP from the outside when air enters and exits the FOUP.

Currently, the N2 purge system is used to fill the FOUP with high-purity N2 gas and protect the wafer surface contained therein from contamination by moisture or chemical gas, but through the breath filter from one side of the breath filter section. A method is employed in which N2 gas is injected and residual gas inside the FOUP is pushed out from the other breath filter part through the breath filter and replaced with high-purity N2 gas. As in the apparatus of the present invention, a means for forcibly sucking the residual gas in the FOUP through the breath filter from the breath filter section has not been adopted yet.

The pressure loss of the present breath filter is large, and in order to replace the residual gas inside the FOUP with a supply flow rate of N2 gas 5 L / min to 7 L / min, N2 gas is injected into the FOUP at a pressure of 2 Kpa to 5 Kpa. Yes. Increasing the N2 gas press-fitting pressure and increasing the supply flow rate to the FOUP also increases the exhaust flow rate from the exhaust side breath filter of the FOUP, but at the same time increases the pressure loss of the exhaust side breath filter. The expansion of the FOUP increases, the gap between the opening and the door further expands, and the leakage of N2 gas increases.
As a result, the replacement with N2 gas in the FOUP is not effectively performed, and the replacement time cannot be shortened for the increase in the consumption amount of N2 gas. Furthermore, an increase in the internal pressure of the FOUP leads to breakage of the FOUP.

N2 gas is a dangerous gas that is harmful to the human body, and the current N2 purge apparatus for FOUP requires installation of a large-scale exhaust duct that discharges leaked gas to the outdoors.

For the above reason, the current N2 purge apparatus for FOUP has extremely poor productivity.

In order to solve the above-described problems, the present invention provides an air supply / exhaust port with a filter (hereinafter referred to as “breath filter part”) so that a pressure difference does not occur between the inside and outside of the container due to a change in atmospheric pressure. Are abbreviated to "", and the N2 gas is injected into the FOUP from one part of the breath filter, and the residual gas in the FOUP is discharged from the other breath filter part. In an N2 purge device that replaces N2 gas and protects the surface of the semiconductor wafer housed inside from moisture or chemical gas contamination,
The flow rate of the residual gas that is forcibly sucked from the FOUP is kept constant at a value smaller by the flow rate of the N2 gas leaking from the gap between the FOUP opening and the door than the flow rate of the N2 gas injected into the FOUP. By controlling so that the N2 gas leakage is minimized, the inside of the FOUP is always maintained at a positive pressure with respect to the outside air, and dust and chemicals from the outside are replaced while the inside of the FOUP is replaced with N2 gas. While preventing the gas from entering the FOUP, the FOUP does not expand even if the pressure inside the FOUP is kept constant during the N2 gas replacement and the supply amount of the N2 gas is increased into the FOUP. The N2 purge device for FOUP is characterized in that leakage of N2 gas from the gap between the door and the door is kept constant, and the time for N2 gas replacement in the FOUP can be shortened.

Since the N2 gas leakage due to the expansion of the FOUP is suppressed to a constant amount and the inside of the FOUP can be replaced with the N2 gas without damaging the FOUP, the safety of the N2 purge system is improved.
Substitution time with N2 gas in FOUP can be shortened, and productivity is improved.

Embodiments of the present invention will be described below.
FOUP sectional view in FIG. 1, shows the FOUP bottom in FIG.
The FOUP 1 has a door 3 and an opening 2. Inside, 25 wafers 10 can be stored. A lifting flange 8 for lifting the FOUP is provided at the top, and a breath filter part 4 is provided at the FOUP bottom 7. A breath filter 5 is provided at the breath filter part 4 so that dust does not enter the FOUP 1.

The bottom portion 7 of the FOUP has a seat 9, and the seat 9 is provided with a kinematic coupling 11 for determining an installation position in the semiconductor manufacturing apparatus.

FIG. 3 shows a cross section of the breath filter unit 4 provided at the bottom of the FOUP.
A breath filter 5 is attached to the cylindrical filter case 6, and the breath filter case 6 is attached to the FOUP bottom 7. Mating of the FOUP bottom 7 and the filter case 6 is sealed by O-ring 12.

FIG. 4 shows a sectional view of the gas supply / exhaust nozzle 16 of the N2 purge device for press-fitting or sucking N2 gas into the FOUP 1 in the present invention. The gas supply / exhaust nozzle 16 has a conical tip end 14 at the tip of a hollow cylinder 13 and is connected to a gas supply / exhaust pipe 15.

Figure 5 shows a cross-sectional view when fitting of the gas supply and exhaust nozzle 16 and the FOUP bottom 7 of the breath filter portion 4 when FOUP1 is installed in N2 purge device.
The conical tip 14 of the gas supply / exhaust nozzle 16 and the inner corner 17 of the breath filter case 6 come into contact with each other, and the seal is maintained.

FIG. 6 shows a conventional N2 purge device for FOUP.
When the FOUP 1 containing the semiconductor wafer 10 is installed in the FOUP N2 purge device , the breath filter unit 4 and the gas supply / exhaust nozzle 16 at the bottom of the FOUP 7 are fitted .
The N 2 gas 21 adjusted by the N 2 gas pressure regulator 18 is supplied to the gas supply / exhaust nozzle 16 through the gas supply / exhaust pipe 15, the inlet flow meter 19, and the breath filter 5 of the breath filter unit 4. Supplied to FOUP1. Internal residual gas 25 FOUP1 is breath filter 5 of the other breath filter portion 4, via the blanking less filter unit 4, gas supply and exhaust nozzle 16 and the exit-side flow meter 20, is discharged from the gas supply and exhaust pipe 15 The

Generally, the pressure loss of the breath filter 5 is 2 Kp to 5 Kp. The N2 gas 21 press-fitted into the FOUP 1 increases the pressure inside the FOUP 1 to a pressure corresponding to the pressure loss of the breath filter 5 on the discharge side. The FOUP 1 expands to create a gap between the opening 2 of the FOUP 1 and the door 3, and the N2 gas 21 leaks from this gap.

If the pressure of the N2 gas 21 is further increased to increase the supply flow rate to the FOUP 1, the exhaust flow rate from the breath filter unit 4 on the exhaust side from the FOUP 1 also increases. The pressure loss also increases, the expansion of the FOUP 1 increases, the gap between the opening 2 and the door 3 further expands, and the leakage of the N 2 gas 21 increases.
As a result, the replacement with the N2 gas 21 in the FOUP 1 is not effectively performed, and the replacement time cannot be shortened for the increase in the consumption amount of the N2 gas 21. Furthermore, an increase in the internal pressure of the FOUP 1 leads to breakage of the FOUP 1.

FIG. 7 shows a schematic diagram of the N 2 purge device for F OUP of the present invention. The supply method of the N2 gas 21 into the FOUP 1 is the same as the conventional FOUP N2 purge apparatus shown in FIG. In the present invention, it is characterized by sucking the residual gas 25 in FOUP1 at a constant flow rate, Here, an example of adapting the vacuum ejector 23 as a suction device. When the supply amount of the high-pressure air 24 into the vacuum ejector 23 is increased, the suction force of the residual gas 25 in the vacuum ejector 23 also increases.
A vacuum pump may be applied as the suction device.

An outlet-side flow meter 20 and a vacuum ejector 23 are connected to the exhaust-side gas supply / exhaust pipe 15. The pressure of the high-pressure air 24 is adjusted by the suction force adjusting pressure regulator 22 and supplied to the vacuum ejector 25. FOUP3 internal residual gas 25, the exhaust side of the breath through the breath filter 5 filters 6 reaches the gas supply and exhaust nozzle 16, through vacuum ejector the outlet side flow meter 20 further via the gas supply and exhaust pipe 15 23, and is sucked by the suction force generated in the vacuum ejector 23 by the high-pressure air 24 and discharged to the outside.

Described method of setting the discharge flow rate of the residual gas 25.
The supply flow rate into the FOUP 1 is set while adjusting the suction pressure adjusting pressure regulator 22 and checking the flow rate of the N2 gas 21 with the inlet flow meter 19. Then adjusting the suction force of the vacuum ejector 23 by the suction force adjusting pressure regulator 22, to the flow rate of the incoming side N2 gas 21, the exhaust flow rate of the residual gas 25, the opening portion 2 of FOUP1 previously assumed door It is set so that the amount of leakage from the gap between 3 is reduced.

It is a cross-sectional view of the FOUP. It is a bottom view of the FOUP. It is sectional drawing of a breath filter part . It is sectional drawing of a gas supply / exhaust nozzle . A mating cross-sectional view of the gas supply and exhaust nozzle and the breath filter unit. It is the schematic of the conventional N2 purge apparatus for FOUP . It is the schematic of the N2 purge apparatus for FOUP of this invention .

1 FOUP
2 opening 3 door 4 breath filter unit 5 breath filter 6 Breath filter case 7 FOUP bottom 8 hanging flange 9 seat 10 wafer 11 Kinematic Thich coupling 12O ring 13 hollow cylindrical 14 conical tip 15 gas supply and exhaust pipe 16 gas supply exhaust nozzle 17 Breath filter case inside corner 18N2 gas pressure regulator 19 entry side flow meter 20 egress flow meter 21N2 gas 22 suction force adjusting pressure regulator 23 vacuum ejector 24 high-pressure air 25 residual gas

Claims (1)

The bottom of the FOUP (semiconductor container), supply and exhaust ports with filters so that the pressure difference is not generated in the vessel interior and exterior by a change in air pressure (hereinafter, abbreviated as "breath filter unit") is provided with a plurality, N2 gas was injected into the FOUP from one part of the breath filter, the residual gas in the FOUP was discharged from the other breath filter part, and the inside of the FOUP was replaced with high-purity N2 gas and stored inside. In an N2 purge apparatus that protects the surface of a semiconductor wafer from contamination by moisture or chemical gas ,
Against the flow rate of N2 gas pressed into the F OUP, the flow rate of the residual gas to compulsorily sucked from the FOUP, at a flow rate of an amount corresponding small value of N2 gas leaking from the gap between the opening and the door of the FOUP By controlling to be constant, the leakage of N2 gas is minimized, the inside of the FOUP is always maintained in a positive pressure state with respect to the outside air, and dust from the outside is replaced while replacing the inside of the FOUP with N2 gas. and while preventing entry into the chemical gas FOUP, holding Chi pressure in the FOUP constant during N2 gas substitution, increasing the supply amount of N2 gas into the FOUP, FOUP is not inflated, FOUP leakage of N2 gas from the opening and the gap of the door is suppressed constant, FOUP for N2 purge device being characterized in that to be able to shorten the N2 gas replacement time in the FOUP.

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