Cleaning and liquid contact with solids – Apparatus – Automatic controls
Reexamination Certificate
1999-05-05
2001-01-30
Coe, Philip R. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
Automatic controls
C134S096100, C134S902000
Reexamination Certificate
active
06178975
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a waste water classifying recovery apparatus for recovering waste water while classifying in a single wafer cleaning system in which wafers are cleaned especially one wafer at a time and particularly to a waste water classifying recovery apparatus in a wafer cleaning system in which rinse (cleaning with pure water) waste water after cleaning can be classified into cloudy rinse waste water and clean rinse waste water for recovery.
2. Description of the Prior Art
Generally, a wafer cleaning system of a multistage batch type or a single tank (bath or container) type has well been known and waste water classifying recovery means are different between both types.
The wafer cleaning system of a multistage batch type, for example as shown in
FIG. 4
, comprises: a chemical liquid A tank
30
(bath); rinse tanks (baths)
31
,
32
; a chemical liquid B tank
33
; and rinse tanks
34
,
35
, wherein chemical liquid A and chemical liquid B are respectively supplied to the chemical liquid A tank
30
and the chemical liquid B tank
33
through a chemical liquid A supply line
37
and a chemical liquid B supply line
38
, while rinse water (pure water or ultrapure water) is supplied to all the tanks through a rinse water supply line
39
. A transport robot moves a carrier in which many wafers are included sequentially through the chemical liquid A tank
30
; the rinse tanks
31
,
32
; the chemical liquid B tank
33
, the rinse tanks
34
,
35
and the like so that the wafers are sequentially immersed into the tanks batchwise.
In a cleaning system of this type, waste water (including waste liquid, hereinafter same as this) can be recovered from each tank while classifying. That is, the chemical liquid A waste water is recovered from the chemical liquid A tank
30
, the chemical liquid B waste water is recovered from the chemical liquid B tank
33
, first rinse (cloudy rinse) waste water from the rinse tanks
31
,
34
and second rinse (clean rinse) waste water from the rinse tanks
32
,
35
.
A wafer cleaning system of a single tank batch type, as shown in
FIG. 5
, has been proposed (see “VLSI Process System Handbook,” published by Kohgyo Chosakai Co., Tokyo), in which chemical liquid A
43
, chemical liquid B
44
and rinse water
45
are selectively supplied to a cleaning tank (container or vessel)
48
through a mixing chamber
46
, wafers are placed in a cassette
41
in plural number and the cassette
41
are revolved in the cleaning tank
48
by a rotary shaft
47
, so that the wafers are cleaned in a immersion treatment.
In a wafer cleaning system of this type, a waste water (drain) line
42
is provided with a three way valve
40
and the like, and the three way valve
40
is operated for draining in each of timings of change of cleaning by the chemical liquids A, B and the rinse water, so that chemical liquid A waste water, chemical liquid B waste water and rinse waste water are classified and recovered.
On the other hand, as shown in
FIG. 6
, a single wafer cleaning system of a single tank (container or vessel) type has been known, in which wafers
2
are placed in a treatment tank
1
one wafer at a time and the wafers sequentially receive spray of the chemical liquids A, B and the rinse water. In a wafer cleaning system of this single tank type, since the wafers are sequentially sprayed with the chemical liquids and the rinse water one wafer at a time, classifying recovery of waste water is hard to be effected with a single waste water line
50
and mixed waste water of chemical liquids and rinse water has conventionally been collected.
The wafer cleaning system of a multistage batch type is advantageous in waste water processing, since each waste water in chemical liquid and rinse systems can be recovered while being classified, whereas there has been a tendency that as a wafer diameter is increased, a wafer cleaning system of a single tank type becomes adopted, since an installation space for tanks is increased.
As shown in
FIG. 5
, a wafer cleaning system of a single tank type is harder for classifying recovery than a wafer cleaning system of a multistage batch type because all the waste waters are recovered through the single waste pipe (drain) line
42
, but since a wafer cleaning system of a single tank type in which a cassette is immersed in a treatment tank is allowed to have a comparatively long time in cleaning, classifying recovery can be effected by operating a three way valve
40
in synchronization with each step of cleaning.
However, in a single wafer cleaning system of a single tank type, as shown in
FIG. 6
, in which wafers are sequentially sprayed with chemical liquid and rinse water one wafer at a time, since each cleaning time for a wafer is short (on the order of 1 to 3 minutes) and therefore, timing in waste water recovery is hard to be correctly matched, there has been much of difficulty in classifying recovery of waste water from the single common waste water line
50
. Therefore, there has conventionally been no way but to recover mixed waste water of chemical liquid and rinse water: classifying recovery of waste water into chemical liquid and rinse water, and further classifying recovery of the rinse water into cloudy rinse waste water and clean rinse waste water have been very hard. Especially, when classifying recovery of waste water into cloudy rinse waste water and clean rinse waste water is impossible, a trouble arises in purification and recycling of waste water and there has remained a problem that reasonable water utilization cannot be achieved.
SUMMARY OF THE INVENTION
The present invention has been made in light of such problems and it is an object of the present invention to provide a waste water classifying recovery apparatus in a single wafer cleaning system of a single tank (container or vessel) type, in which not only classifying recovery of waste water into chemical liquid waste water and rinse waste water but classifying recovery of rinse waste water into cloudy (contaminated) rinse waste water and clean rinse waste water can be effected.
In order to achieve such an object, the present invention is directed to a waste water classifying recovery apparatus in a wafer cleaning system of a single tank in which a wafer is cleaned in a single treatment tank while chemical liquid and rinse steps are selectively performed; in more concrete manner, wafers are cleaned in a single treatment tank one by one while chemical liquid and rinse water are selectively sprayed on the wafers, comprises: a common waste water line which is connected to the treatment tank; chemical liquid waste water and rinse waste water lines which are branched from the common waste water line; chemical liquid/rinse selective distributor automatic valves respectively provided on the chemical liquid waste water line and the rinse waste water line; a concentration meter sensor for detecting a concentration of the rinse waste water provided downstream from the distributor automatic valve on the rinse waste water line; and cloudy and clean rinse waste water lines branched from the rinse waste water line downstream from the concentration meter sensor through cloudy/clean rinse distributor automatic valves, wherein the cloudy/clean rinse distributor automatic valves are selectively operated according to a detection signal of the concentration meter sensor and thereby cloudy rinse waste water and clean rinse waste water are separately drained.
It is preferable that, in the present invention, a water quality meter sensor for detecting a water quality of the waste water is provided on the common waste water line; the chemical liquid waste water and rinse waste water lines are branched from the common waste water line downstream from the water quality meter sensor; the chemical/rinse selective distributor automatic valves are respectively provided on the chemical liquid waste water, and rinse waste water lines; and the chemical/rinse selective distributor automatic valves are controlled accordi
Coe Philip R.
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Shin-Etsu Handotai & Co., Ltd.
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