1. 7/26/2004 Presented by Ernie Marks 1
Procedures for DeterminingProcedures for Determining
Leak Integrity and LeakLeak Integrity and Leak
Sources in Vacuum SystemsSources in Vacuum Systems
Verify System Vacuum Status by
using the System’s own components

2. 7/24/2004 Presented by Ernie Marks 2
What we will learn today:What we will learn today:
Procedure for determining Pump base
pressure.
Procedure for determining Isolation Valve
Leak Integrity.
Procedure for determining System Base
Pressure.
Procedure for determining Chamber Leak
Rate.
Identify four types of leaks.

3. 7/24/2004 Presented by Ernie Marks 3
Why we will learn this today:Why we will learn this today:
This procedure, or the results of it, is critical
to the proper performance of a Vacuum
process tool.
This procedure can be used to avoid poor
process performance, and even scrapped
production material and damaged
equipment.

4. 7/24/2004 Presented by Ernie Marks 4
System ConfigurationSystem Configuration
Medium vacuum system (o-ring seals)
capable of achieving < 10 millitorr base
pressure.
Process chamber is isolated from the
vacuum pump with an isolation valve.
Both Process Chamber and Pump have
Pressure Gauges.
System may have dynamic and static seals.
System may have purges, which can be
isolated.

5. 7/24/2004 Presented by Ernie Marks 5
System ConfigurationSystem Configuration
Vacuum Chamber Chamber
Pressure
Gauge
Vacuum
Pump
Isolation
ValveFore Line
Pressure
Gauge
Chamber
Vent Valve
N2

6. 7/24/2004 Presented by Ernie Marks 6
System Configuration (Cont.)System Configuration (Cont.)
System has been taken down for a Major
Clean, and is in the process of being
requalified. The chamber has been pumped
down and cycle purged.
Note that all procedure steps will have a
delay in consideration of the following
variables:
– Vacuum Pump Size (Pumping Speed)
– Diameter, Length and Straightness of the
Vacuum Line
– Process Chamber Size

7. 7/24/2004 Presented by Ernie Marks 7
Pump Base Pressure ProcedurePump Base Pressure Procedure
1. Close any Vacuum line purges.
2. Close Vacuum Isolation Valve.
3. Allow several minutes for a stable Fore
Line Gauge pressure reading.
4. Record the fore line pressure.
5. Verify base pressure is <10 millitorr

8. 7/24/2004 Presented by Ernie Marks 8
Isolation Valve Leak IntegrityIsolation Valve Leak Integrity
ProcedureProcedure
1. Continue to read Fore Line Gauge.
2. Vent the Chamber.
3. Verify that the Fore Line pressure reading
does not change.

9. 7/24/2004 Presented by Ernie Marks 9
System Base PressureSystem Base Pressure
ProcedureProcedure
1. Open Vacuum Isolation Valve and pump
down the Chamber.
2. Allow the Chamber and Fore Line
pressure gauge readings to stabilize.
3. Record Chamber Pressure and compare to
the previous Fore Line Pressure reading.

10. 7/24/2004 Presented by Ernie Marks 10
System Base PressureSystem Base Pressure
Procedure ContinuedProcedure Continued
4. Record Length of Time it took to get to
Base Pressure.
5. Vent Process Chamber, Pump down
again, and recheck Base Pressure and
Pump Down Time.
6. Repeat this procedure three times.

11. 7/24/2004 Presented by Ernie Marks 11
Chamber Rise Rate ProcedureChamber Rise Rate Procedure
1. With the Chamber pumped down, close
the Vacuum Isolation Valve.
2. Monitor and record the Chamber Pressure
for several minutes.
3. Open the Vacuum Isolation valve, and
Pump the Chamber back to Base Pressure.
4. Close the Vacuum Isolation Valve again,
and check rise rate again.
5. Repeat this procedure three times.

12. 7/24/2004 Presented by Ernie Marks 12
Four Leak TypesFour Leak Types
1. Isolation Integrity Leak
2. Virtual Leak (Trapped Volume,
Outgassing)
3. Permeation Leak (Accumulation of
molecular sized leaks through porous
material)
4. Bona Fide Hole (scratch, ding, tear, crack,
etcetera).

13. 7/24/2004 Presented by Ernie Marks 13
Review QuestionsReview Questions
1. Why did we verify the isolation leak integrity of
the vacuum isolation valve?
2. What leak test operation can not be reliably
performed if the vacuum isolation valve does not
isolate?
3. Why did we pump and vent the Process Chamber
Three times?
4. Why did we perform the Process Chamber rise
rate check three times?
5. What affect can chamber volume have on our
ability to “see” a leak?