Low contamination blending and metering systems for semiconductor processing

Blending and pumping systems for accurately delivering desired amounts of processing fluids, particularly for use in semiconductor processing and semiconductor processors. Thee blending systems include one or more supply tanks from which a processing fluid is accurately pumped using the novel metering pump and associated pumping and blending methods. The blending systems preferably include a recycle line which includes a control valve which is controlled to recycle process fluid during an initial startup period. The outflow from the pump is preferably totally recycled during this startup period by blocking flow of process fluid to the blending container. The metering pump includes a pump housing having a pumping chamber which is partially defined by a displacement member, such as a flexible bellows structure. The pumping chamber is isolated from inlet and outlet via inlet and outlet valves, respectively. The inlet and outlet valves are positively controlled into open and closed positions using a control system which preferably includes an elctronic controller. The controller appropriately sequences the operation of the pump inlet and outlet valves relative to a displacement member actuator which drives the displacement member. The control is preferably accomplished by using electrically operated solenoid valves which control the flow of an intermediary control fluid, such as air or other suitable gas. The invention further includes methods of blending and pumping to provide accurate and low contamination of the process fluids being metered.

TECHNICAL FIELD 
The field of this invention is accurate blending and pumping apparatus and 
methods for delivery of liquid compositions, particularly those related to 
the processing of semiconductors. 
BACKGROUND OF THE INVENTION 
In semiconductor substrate processing it is often necessary to provide 
carefully blended processing fluids to a processing chamber in which 
semiconductor wafers, photomasks, and other similar products are being 
treated or processed. Blended processing fluids may, for example, include 
mixtures of hydrogen peroxide with sulfuric acid, ammonium hydroxide, 
water and other processing fluids. Similarly, hydrofluoric acid may need 
to be blended with water, acidic acid, nitric acid, phosphoric acid or 
other processing fluids. 
Because of the relatively small size of semiconductor processors and the 
small number of articles typically processed at one time, the amounts of 
such processing fluids are relatively small. This requires that the 
metering of various constituents be done accurately to achieve the desired 
blend. Additionally, it is of utmost concern that the fluids be blended in 
a manner which does not add undesired contaminants to the processing 
fluids. Such contaminants can cause serious loss of wafer yields. 
The desired blending of process fluids is particularly of significance in 
processing where the same group of chemicals may be used in varying 
processing steps in different concentrations and or combinations. 
Previously it has been difficult to achieve repeatable accurate blending 
of processing fluid components from one processing run to the next. Each 
time the processing fluid constituents are mixed there is a chance for 
variability due to operator error and simple inability to accurately 
control the amounts of chemicals being combined to produce the desired 
blended processing fluid. Thus the semiconductor industry has experienced 
a keen need for processing equipment which can be stocked with several 
different processing fluids and then provide automated blending of these 
fluids without operator judgement and manual control. Previous systems 
were unable to achieve the desired degree of blending accuracy and 
repeatability.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The following disclosure of the invention is submitted in furtherance with 
the constitutional purpose of the Patent Laws "to promote the progress of 
science and useful arts" (Article 1, Section 8). 
FIG. 1 shows a semiconductor blending system 10 according to this 
invention. The blending system is advantageously included as a subsystem 
in a semiconductor processor not otherwise shown. A suitable example of 
semiconductor processor is an acid treatment processor (not shown). The 
blending system includes a first component supply container or reservoir 
11 used to stock a desired first processing fluid 12. The reservoir can 
advantageously be positioned in a room adjacent to a laminar flow clean 
room to save floor space in these high cost production facilities. The 
processing fluid can be furnished in the reservoir container or supplied 
to a fixed reservoir in any suitable manner. The container has an outlet 
13 through which process fluid 12 is withdrawn. The reservoir outlet 13 is 
connected to a pump supply conduit or line 15 which supplies metering pump 
20. The supply line 15 is connected to the inlet 21 of pump 20. Pump 20 is 
a metering pump such as described hereinafter. The pump outlet 22 is 
connected to an outflow line or outflow conduit system 23. The outflow 
system is branched in a suitable manner such as at branch fitting 24 to 
allow controlled recycle to reservoir 11 and controlled delivery to either 
a blending container 30 or by recycle to supply container 11. The 
controlled recycle allows priming of pump 20 and related fluid conduits. 
The recycle line 26 is provided with a suitable recycle control valve 27 
which controls the flow of fluid from outflow of pump 20 back to reservoir 
11. Similarly, a blending tank conduit 28 is provided with a blending 
supply or delivery control valve 29. Alternatively, the branched 
connection 24 and control valves 27 and 29 can be integrated into a 
suitable two outlet (3-way) control valve known in the art. 
The blending tank supply line 28 empties into the blending tank, reservoir 
or container 30. Blended processing fluid 31 is held within the blending 
container 30. The blended processing fluid 31 is a combination of the 
first processing fluid component 12 and a second processing fluid 
component which is supplied via a second component supply valve 32. The 
second component can be metered in an accurate manner using a subsystem 
incorporating parts equivalent to reservoir 11, pump 20, recycle valve 27, 
delivery valve 28, and associated parts as described herein. 
Alternatively, the second component of the blended processing fluid 31, 
can be the major component and supplied using a relatively less accurate 
supply system. For example, where an active ingredient is being diluted 
into water, the water may be appropriately supplied through valve 32 to a 
desired level, or otherwise measured without metering the entire flow as 
described hereinafter. Blended processing fluid 31 is controllably 
supplied to the processing chamber (not shown) of a semiconductor 
processor via blended product control valve 34. 
FIG. 2 shows an alternative blending system 40 according to this invention. 
Blending system 40 is also designed as a subsystem to a semiconductor 
processor. Blending system 40 includes first, second and third processing 
fluid component reservoirs 11a, 11b, 11c, respectively, which are similar 
to reservoir 11 described hereinabove. Each fluid component 12a, 12b, and 
12c is held therein and supplied through metering pumps 20a, 20b, and 20c, 
respectively. The inlets 21a, 21b, and 21c, and outlets 22a, 22b, and 22c 
intake and discharge the respective processing fluid components. Recycle 
of the first, second and third processing fluid components is accomplished 
through first, second and third recycle lines 26a-c, using first, second 
and third recycle control valves 27a-c, respectively. The processing fluid 
components are delivered to a blending tank 42 via the first, second and 
third blending reservoir supply or delivery lines 28a-c, as controlled by 
blending supply control valves 29a-c. The mixture, solution or other 
combination of the three processing fluid components produces the blended 
processing fluid 43 held within the blending container 42. Blended 
processing fluid 43 is controllably supplied to the processing chamber 
(not shown) of the semiconductor processor as controlled by blended 
product control valve 44. 
FIGS. 3-7 show a preferred metering pump 20 useful in the processing fluid 
blending systems 10 and 40 and others according to this invention. Pump 20 
includes a pump housing 50. As shown, pump housing 50 is advantageously 
constructed using a number of component parts which are assembled 
together. The pump housing includes a main pump housing or first body 
member 51. Attached to the primary pump housing member 51 is a pumping 
actuator assembly 53 and two valve actuator assemblies 55 and 57. The 
pumping actuator assembly 53 uses two controlled supplies of compressed 
air or other suitable actuation media which are utilized to move a bellows 
60 to thus cause pumping action. Similarly, the inlet and outlet valve 
actuator assemblies 55 and 57 also use two controlled supplies of 
compressed air or other suitable media to controllably open and close 
inlet and outlet valve assemblies 56 and 58, respectively (see FIGS. 5 and 
7). The inlet valve 56 is opened to allow the fluid being pumped to enter 
into a pumping chamber 59. Pumping chamber 59 is in part defined by the 
interior of the bellows 60 which acts as a displacement element for 
positively displacing the fluid being pumped. The inlet valve 55 is opened 
and the outlet valve 57 is closed during the intake cycle wherein 
expansionary motion of bellows 60 occurs to thus draw fluid into pumping 
chamber 59. The outlet valve 57 is opened and the inlet valve 55 is closed 
during contractionary motion of bellows 60 to thus pump the fluid from 
pumping chamber 59. 
FIG. 7 shows that the primary pump housing member 51 is preferably formed 
with inlet and outlet valve actuator mounting flanges 61 and 62, 
respectively. Flanges 61 and 62 are adapted for connecting the inlet and 
outlet valve actuators 55 and 57 to the main pump housing member 51. The 
valve actuators 55 and 57 each include valve actuator body pieces 65 
having mounting flanges 66. Connection of the valve actuators is 
advantageously accomplished using split mounting rings 63 which have 
tapered interior grooves 64. The tapered grooves 64 engage tapered back 
surfaces of the flanges 61 and 62, and tapered back surfaces of the 
mounting flanges 66. The corresponding halves of split mounting rings 63 
are held in position by mounting ring fasteners 68. This tapered flange 
and ring arrangement forces the mating flanges of the main pump housing 
and valve actuators together in a tightly sealed arrangement using gaskets 
67 or other sealing members. 
The inlet and outlet valves 56 and 58 each include a valve piece 70 which 
is movable in a longitudinal, axial direction within inlet and outlet 
valve chambers 71 and 72, respectively. Inward motion of the valve pieces 
70 cause truncated conical or frusto-conical sealing surfaces 73 on the 
head of each valve to engage and seal against valve seat members 74. The 
valve seats are each advantageously constructed with a valve orifice 75 
which receives the frusto-conical sealing end of the valve pieces 70. The 
orifices 75 are advantageously formed by a tubular portion 77 of the valve 
seat separated from remaining portions by an annular groove 78. 
The inlet and outlet valve actuators 55 and 57 are similarly constructed. 
The actuator body pieces 65 each include a central bore 80 having a number 
of different sections which mount the internal workings of the actuator. 
The actuators include actuator stems or stem pieces 81 which are adapted 
to connect between the outer ends of valve pieces 70 and flexible 
diaphragm members 82. The connection with the valve pieces is 
advantageously accomplished using an axial extension 83 on the stem which 
is received in an end receptacle 84 on each valve piece. The axial 
extension is advantageously provided with a groove 85 which helps to 
retain the parts together. The opposite outward ends of the stem pieces 81 
are similarly provided with extensions 86 which receive the diaphragms 82 
and diaphragm retainer caps 87 thereon. The extensions 86 are preferably 
provided with two circumferential retaining grooves 88. The central 
portions of the stem pieces 81 are received through guide apertures 89 
formed in the valve actuator body pieces 65. The guide apertures 89 are 
preferably adapted with small grooves 90 which receive annular stem seals 
91. 
The valve actuators 55 and 57 further include diaphragm backup pieces 93 
which are adapted to engage with the diaphragm retainer caps and prevent 
mechanical contact of the diaphragms 82. The backup pieces 93 support the 
outer peripheries of the diaphragms, and are sealed thereagainst using 
diaphragm periphery seals 94. Retainers 99 hold the backup pieces 93 in 
position within the actuator body pieces 65 by engaging with a retainer 
groove 100 formed in the central bore. The backup pieces 93 are provided 
with actuating fluid contraction passages 95 formed therethrough. The 
actuating fluid passages are advantageously adapted to receive threaded 
tubing connection fittings 96 through which pressurized actuation fluid, 
such as clean dry air, are supplied to force the diaphragms 82 inwardly to 
seal the valves. The diaphragms are moved outwardly by supplying 
pressurized actuation fluid through actuating fluid extension passages 97 
(see FIG. 5) which are similarly provided with tubing fittings 98. 
FIG. 6 shows in further detail the connection of the pumping actuator 
assembly 53 with pump housing main piece 51. The pump housing main piece 
51 is advantageously provided with a pumping actuator mounting flange 102 
having a tapered lower or inward flange surface 103. The upper or outward 
face 104 receives the face of the pumping actuator housing mounting flange 
105. The pumping actuator housing 106 also includes a housing extension 
107 which is advantageously received within the interior passage of the 
mounting flange 102. 
The pumping actuator assembly 53 also includes a housing end cap 109 which 
is connected to the main part of housing 106. The end cap is provided with 
a flange 110 having a tapered outward surface. Flange 110 mates with an 
upper flange 111 formed on the actuator housing 106. Flange 111 has a 
tapered lower surface. The flange pairs 110,111 and 102,105 are joined 
together by a two part split ring construction similar to that described 
hereinabove for the valve actuators. The flange pairs are received within 
tapered grooves 112 formed by mounting rings 113 using fasteners 108. This 
arrangement clamps the flange faces together. A suitable seal such as 
O-ring seal 114 is advantageously included between cap 109 and housing 
106. Sealing also occurs between the lower end face 115 of housing 106 and 
the main housing 51 using the bellows retaining flange 138 integrally 
formed from the lower end of flexible bellows 60. 
The interior of the pumping actuator is preferably divided into motor 
chamber 116 and bellows chamber 117. The motor chamber 116 is constructed 
to accommodate a fluid powered actuation motor 118. The motor 118 includes 
a cylinder liner 119 which receives a piston 120 which is slidable therein 
in an axial longitudinal direction, up and down as shown in FIG. 6. 
Leakage between the piston and cylinder is sealed using two piston rings 
121 which are received within suitable receiving grooves 122 formed in the 
sidewalls of the piston. The piston is connected to a connecting rod 123. 
Piston 120 bears against a mounting shoulder on connecting rod 123 and is 
retained thereagainst using a nut 124 which is threaded onto a piston 
mounting extension 125 of the connecting rod 123. The end of the extension 
section 125 is advantageously provided with a screw driver slot 126 to aid 
in assembly and disassembly. 
The connecting rod 123 is slidably received through a connecting rod 
aperture 127 formed through a housing bulkhead 128 which separates the 
motor chamber from the bellows chamber 117. The aperture 127 is 
advantageously provided with a sealing groove 129 which receives a sealing 
member 130. The bellows chamber 117 is preferably provided with a 
combination vent and drain 144 which is preferably connected to a building 
or other facilities drain system capable of handling potential discharges 
of the process fluids being blended. 
The upper end of piston 120 is designed to contact against an annular stop 
member 131. Stop member 131 is mounted to the inside of cap 109 using 
suitable means, such as fasteners 132. The stop member is contacted by 
piston 120 when the piston is in the fully extended position. The lower 
end of piston 120 contacts the upper side of bulkhead 128 when the piston 
is in the fully retracted position. 
The inward or lower end of connecting rod 123 is adapted for connecting to 
the bellows 60 using a connecting rod bellows flange 133. The connecting 
rod bellows flange 133 mates with a bellows connecting flange 134. These 
flanges are connected by split connection rings 135 in a manner similar to 
other flange connections described hereinabove. 
The bellows 60 is provided with a bellows head 136 which connects the 
bellows upper flange 134 to the bellows accordion portion 137. The lower 
end of bellows 60 is provided with a bellows retaining flange 138 which 
keeps the lower end in position relative to the housing. The upper end of 
bellows 60 is movable with the connecting rod 123 and piston 120. The 
interior 142 of the bellows is advantageously fitted with a bellows 
interior piece 139. Interior piece 139 is cylindrical and held by a 
receptacle 139a formed in the interior of bellows head 136 to receive a 
mounting extension 140 forming a part of interior piece 139. The bellows 
interior piece serves to support the bellows accordion and reduce the 
displacement of the bellows interior when the bellows accordion is 
expanded and contracted. The bellows is preferably made in sufficient 
length relative to the stroke of piston 120 so that from the median 
position of the movable bellows head, there is a 60 percent decrease in 
bellows length and a 40 percent increase in bellows length, as the bellows 
moves from the fully contracted to fully expanded conditions. This 
minimizes stress in the bellows and reduces the sloughing of bellows 
material into the processing fluid being pumped. This is significant in 
maintaining low contamination for semiconductor processing. 
The pumping chamber 59 is partially defined by the interior of the bellows 
and the bellows interior piece 139, and also by a pumping chamber recess 
141 formed in upper surfaces of the primary pump housing piece 51. The 
pumping chamber is further defined by a T-shaped pumping chamber 
passageway 143 which connects the bellows interior with the inlet and 
outlet valve orifices. 
FIGS. 6 and 7 show that the inlet 21 and outlet 22 of pump 20 are 
advantageously provided with an inlet fitting 145 and outlet fitting 146, 
respectively. The fittings 145 and 146 facilitate the connection of supply 
line 15 and outflow line 23 (see FIG. 1). The fittings are received in 
threaded inlet and outlet receptacles 147 and 148 formed in the housing 
piece 51. The receptacles 147 and 148 are advantageously isolated from 
remaining portions of the housing piece by annular isolation grooves 149 
which are advantageously fitted with reinforcement inserts 150. This 
structure provides a preferably polymer threaded receptacle for superior 
sealing with fittings 145 and 146, enhanced by superior mechanical 
integrity. Sealing of the fittings 145 and 146 is further enhanced by a 
sealing ring structure including a tapered first ring 151 which receives a 
second tapered sealing ring 152 (FIG. 6). The second ring swages the first 
outwardly and forms a tight seal with the housing piece 51. 
The housing piece 51 includes an inlet chamber 153 which is in fluid 
communication with the inlet valve chamber 71. Similarly, housing piece 51 
includes an outlet chamber 154 which is in fluid communication with the 
outlet valve chamber 72. 
FIG. 8 shows a preferred construction of control system for the blending 
system 10 of FIG. 1. The control system includes an electronic controller 
155 which is electrically connected to provide control signals to two 
solenoid operated control valves 156 and 157. Control valves 156 and 157 
receive pressurized air or other actuation media via an adjustable 
pressure regulator 159. A pressure gauge 160 is advantageously included to 
indicate the pressure to a pneumatic distribution manifold and control 
valves 156 and 157. Control valves 156 and 157 are preferably 3-way valves 
each having two pneumatic outputs. First control valve 156 has outputs 161 
and 162. Similarly, second solenoid operated pneumatic control valve 157 
has two outputs 163 and 164. Control valves 157 and 158 are advantageously 
mounted in a manifold block 158. Manifold block 158 is supplied with 
compressed gas, such as clean, dry air or nitrogen preferably through an 
adjustable pressure regulator 159. When control valve 156 is activated 
then pressurized gas is supplied to output 161. When control valve 156 is 
not activated then pressurized gas is supplied to output 162. When control 
valve 157 is activated then pressurized gas is supplied to output 163. 
When control valve 157 is not activated then pressurized gas is supplied 
to output 164. The non-pressurized outputs are automatically bled of 
residual pressure by bleed ports on each valve (not shown). A pressure 
gauge 160 can advantageously be included to indicate the pressure of the 
gas supplied to manifold 158. 
The pneumatic control fluid outputs 161-164 are connected to pneumatic 
control lines 165-168, respectively. Control lines 165 and 166 are 
connected to the pump actuator motor at fittings 166 and 167, 
respectively, to thus apply pressure at the top of piston 120 when valve 
156 is activated. Control line 167 is connected to the extension side 
fitting 98 of the inlet valve actuator 55 to thus cause the inlet valve 56 
to open when control valve 157 is activated. Control line 167 is also 
connected to the contractionary fitting 96 of the outlet valve actuator 57 
thus causing the outlet valve to be closed when control valve 157 is 
activated. Conversely, the control line 168 is connected to the extension 
fitting of the outlet valve 58, and to the contractionary fitting of the 
inlet valve. Because of the control fluid in lines 167 and 168 are 
substantially out of phase this causes the inlet and outlet valves to be 
operated in an opposite and substantially complementary manner. The 
electronic controller 155 coordinates the operation of the inlet and 
outlet valves with respect to the operation of the bellows 60. 
FIG. 8 also shows that electronic controller 155 is connected to provide 
output control signals to the recycle control valve 27 and the fluid 
delivery control valve 29. This can be done directly by using electrical 
solenoid operated control valves for valves 27 and 29. Alternatively and 
more preferably, the valves 27 and 29 can be pneumatically actuated, in 
which event intervening solenoid operated pneumatic control valves 27a and 
29a would be included to control the flow of actuating gas to the process 
fluid control valves 27 and 29. 
The pump and associated parts described above preferably are made of 
fluorocarbon polymer, such as TEFLON or other PTFE, or other suitable 
materials as needed for the particular process fluids being used. The 
parts are formed into the indicated parts using standard materials working 
techniques such as machining or molding. The various seals used and 
identified above can similarly be selected from commercially available 
materials dependent upon the chemical process fluids being used. 
The pumping and blending systems according to this invention are 
advantageously operated to provide novel low contamination operation 
capable of delivering accurate amounts of relatively small quantities of 
process fluids. The operation will be described generally with respect to 
the blending system shown in FIG. 1. The process controller 155 sequences 
through the desired operational steps of the semiconductor processor until 
the appropriate time when blending of process chemicals is desired. 
Controller 155 causes de-ionized water or other process fluid to be 
supplied through valve 32 by opening the valve. Valve 32 can either be 
directly operated by an electrical solenoid, or operated pneumatically 
using an interposed pneumatic actuating control valve 32a which supplies 
actuating gas to valve 32. Valve 32 is opened for a predetermined period 
of time or otherwise controlled to provide a desired amount of water in 
blending container 30. Alternatively, the water or other process fluid 
supplied through valve 32 can be provided using a metering system similar 
to that shown supplying fluid to valve 29 and valve 32 functions in a 
manner the same as valve 29. 
The metering portion or portions of blending system 10 are controlled to 
initiate operation of metering pump 20 with recycle control valve 27 
opened to thus allow process fluid 12 to be recycled to reservoir 11 
during a startup period. The metering pump 20 operates in the following 
manner. The electronic controller 155 activates the solenoid valve 156 
thus causing actuating gas to flow from the manifold 158 through pneumatic 
control line 165 to fitting 170 on the bellows actuator. The actuating 
compressed gas causes the piston and connected head 136 of bellows 60 to 
move upwardly. The control valve 157 is also activated shortly thereafter 
to thus cause the inlet valve 56 to be opened by supplying the control gas 
to the actuating fluid extension passage 97 of the inlet valve actuator 
55. The positive displacement increase of the bellows and pumping chamber 
thus draw process fluid from reservoir 11 through supply line 15, fitting 
21, inlet chamber 153, inlet valve chamber 71 and into the passageway 143. 
As the piston 120 is fully extended upwardly, the controller 155 
deactivates the solenoid operated valve 157 thus closing the inlet valve 
55 and opening the outlet valve 57. Similarly, control valve 156 is 
deactivated to apply pneumatic pressure to the upper end of piston 120 to 
thus cause the piston and connected bellows head 136 to move downwardly. 
The contractionary movement of the bellows head decreases the volume of 
the pumping chamber 59 and displaces process fluid out through the outlet 
valve chamber 72, outlet chamber 154, and through fitting 22 to outflow 
line 23. 
The above process is repeated using the positive electronic control 
provided by controller 155 for a predetermined number of startup cycles in 
order to assure that the pump is fully primed and all process fluid 
conduits are full. For example, the recycle part of the operational 
sequence may be advantageously repeated for 5 or more cycles, more 
preferably 5-20 or more cycles. During this recycle part of the 
operational method the process fluid 12 is routed only to reservoir 11 
because controller 155 has caused recycle valve 27 to be open and delivery 
valve 29 to be closed. The recycle operation is preferably preprogrammed 
into controller 155 to occur automatically up initial operation of the 
pump 20. Once the recycle part of the method is sufficiently completed to 
eliminate startup flow variations and fill all process fluid lines, then 
recycle valve 27 is closed and delivery valve 29 is opened. This change is 
preferably accomplished during the start of a bellows compression stroke. 
The controller thereafter tallies the number of pump cycles which occur 
and automatically delivers a desired preprogrammed amount of process fluid 
12 through delivery valve 29 into blending container 30. The amount of 
process fluid 12 delivered is thus accurately determined and automatically 
delivered to produce an automatic blending process according to this 
invention. 
It should also be understood that pump 20 can be operated in a reverse 
pumping mode. In this reverse operation the inlet and outlets are reversed 
and the operation of the pump motor is properly coordinated to achieve 
reverse pumping in a manner similar to the operation described above. 
Reverse pumping can be used to remove fluid from the fluid conduits back 
to the supply reservoir. 
In compliance with the statute, the invention has been described in 
language more or less specific as to structural features. It is to be 
understood, however, that the invention is not limited to the specific 
features shown, since the means and construction herein disclosed comprise 
a preferred form of putting the invention into effect. The invention is, 
therefore, claimed in any of its forms or modifications within the proper 
scope of the appended claims appropriately interpreted in accordance with 
the doctrine of equivalents.