Utah-94-721002-System-Manual.pdf - 第51页

System Manual lñÑçêÇ=få ëíêìãÉåíë=mä~ëã~=qÉÅÜåçäçÖó== mä~ëã~ä~ Ä póëíÉã=NMM PRO CESS GA S OUT T O CHAMBER 100MM EXTRACTION CO LLAR SINGLE- SMC ASSE MBL Y SIX- W A Y SMC ASSEMBL Y GA S POD COVE R INTERLOCK MICROSWITCH GAS…

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WARNING
CONTACT WITH TOXIC GASES CAN CAUSE DEATH OR SERIOUS INJURY.
USERS SHOULD PERFORM THEIR OWN RISK ASSESSMENT OF HAZARDOUS GASES TO
BE USED ON THE SYSTEM.
BEFORE VENTING THE PROCESS CHAMBER, ALWAYS ENSURE THAT THE SYSTEM IS
ADEQUATELY PURGED AND PUMPED; SEE ‘VENTING THE SYSTEM’ IN SECTION 5 OF
THIS MANUAL.
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The purpose of the gas pod is to feed a mixture of process gases, at specified flow rates, to
the process chamber. Selection of gases and flow rates are determined by the system
controller. A ‘clean gas’ line can be incorporated to feed an etch gas mixture into the process
chamber to remove process residues.
The gas pod, shown in Fig 3.5, comprises a steel case with a removable cover. An extraction
collar at the top of the case enables any leaked gas to be safely removed by a laboratory
extraction system. The back panel of the case is fitted with fixing holes for wall or frame
mounting.
Description
UC Davis 94-721001 Issue 1: March 06 Page 3-14 of 22 Printed: 22-Mar-06, 7:29
System Manual lñÑçêÇ=fåëíêìãÉåíë=mä~ëã~=qÉÅÜåçäçÖó== mä~ëã~ä~Ä póëíÉã=NMM
PROCESS GAS
OUT TO CHAMBER
100MM EXTRACTION
COLLAR
SINGLE- SMC
ASSEMBLY
SIX-WAY SMC
ASSEMBLY
GAS POD COVER
INTERLOCK MICROSWITCH
GAS POD
PCB
'CLEAN
GAS' LINE
COMPRESSED
AIR
IN
OUT
CONTROL
CABLE FROM
PLC / PCB
PROCESS GAS
SHUT-OFF
VALVE
Fig 3.5: 94-81-9-51 Gas pod
The case incorporates stations for up to six gas lines. The outputs from the gas lines are fed
into a common manifold which is connected to the process chamber gas line. Pneumatically
operated shut-off valves in each gas line are driven by associated SMC valves, powered by
compressed air and controlled by signals from the system controller. A separate SMC valve,
controlled by an interlock microswitch, prevents the opening of any gas shut-off valve when
the case cover is not fitted, or when either of the system interlock lines are open.
The Gas Pod PCB receives signals from the system controller, to control the SMC valves, and
the Mass Flow Controllers (MFC) fitted in the gas lines. For a circuit diagram of the Gas Pod
PCB, refer to drawing SE81D15942 in Volume 2 of this manual.
The ‘clean gas’ line flow rate can be set either manually by a variable valve (as shown in Fig
3.5) or by an MFC. Note that the ‘clean gas’ is usually supplied from a cylinder containing the
required gas mixture. An alternative method is to mix separate gases in optional additional
gas lines.
Description
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mä~ëã~ä~Ä póëíÉã=NMM lñÑçêÇ=fåëíêìãÉåíë=mä~ëã~=qÉÅÜåçäçÖó== System Manual
WARNING
THE CONNECTION FROM THE GAS POD MANIFOLD TO THE PROCESS CHAMBER
SHOULD NOT INCLUDE ANY SHUT OFF VALVE, UNLESS THIS HAS BEEN CLEARED
WITH OXFORD PLASMA TECHNOLOGY. A BLOCKAGE HERE COULD CAUSE PROCESS
GASES TO MIX AND CROSS CONTAMINATE IN THE HIGH PRESSURE GAS DELIVERY
PIPEWORK.
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The standard non-toxic gas line is shown in Fig 3.6. All gas fittings are VCR and all stainless
steel pipework connections are welded. The ‘gas in’ tube passes into the side of the case,
protected by a grommet. A ferrite core, fitted to the ‘gas in’ tube, reduces the susceptibility
of the gas pod electronics to signals from nearby transmitting devices, e.g. mobile phones,
modems, etc..
Gas from the customer’s cylinder/regulator/filter flows into the gas in tube to the filter.
The gas flows through the 2-µm filter to the mass flow controller (MFC). The MFC controls the
flow of gas as commanded by the system controller. The gas then flows through the
pneumatically controlled outlet shut-off valve and into the gas out manifold where it is mixed
with the other process gases before flowing into the process chamber.
WARNING
THE CLOSED INLET VALVE REMAINS SHUT FOR DIFFERENTIAL PRESSURE UP TO 5
BAR. A FAILURE UPSTREAM WHICH PRODUCES LINE PRESSURES ABOVE THIS WILL
NOT BE CONTAINED. IF THIS PRODUCES A HAZARD, THE CUSTOMER IS WARNED TO
FIT ADDITIONAL PROTECTION UPSTREAM.
GAS IN TUBE
(STAINLESS STEEL)
GROMMET
2 µm FILTER
GAS LINE EXTENSION
FERRITE CORE
MASS
FLOW
CONTROLLER
GAS OUT
MANIFOLD
OUTLET SHUT-OFF
VALVE
(PNEUMATICALLY
CONTROLLED)
Fig 3.6: 94-81-9-11 Standard non-toxic gas lines
Description
UC Davis 94-721001 Issue 1: March 06 Page 3-16 of 22 Printed: 22-Mar-06, 7:29