Welcome to Lam Research
Quick Change Cold Trap Project
Greg Sexton
Staff Mechanical Engineer
New Product Development
3/16/05
Slide - 2
Agenda
 Introduction
 Project Description
 Primary Constraints
 Secondary Constraints
Q & A
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Slide - 3
Introduction
 What does Lam Research
do?
– Lam Research Corp. is a major semiconductor equipment manufacturer and the
world leader in semiconductor etching equipment
– More detailed information available at www.lamrc.com
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Slide - 4
Introduction
How are new ideas investigated by New
Product Development?
Basic Feasibility Cycle:
Yes
PM Concept/Design
Manufacture
Installation
Test/Verify
Make available to
Product Groups
No
Redesign subsystem
Procure redesign
“Repeat until successful”
** Critical Path always hinges upon the discovery/verification of critical
process specifications. **
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Quick Change Cold Trap Project



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In the processing of a substrate, e.g., a semiconductor wafer, plasma is often
employed. The wafer is processed in a series of steps, one of which is etching.
During the etch process materials are selectively removed from the wafer to form
features needed to form electrical components thereon.
Etching produces byproducts. Generally, volatile byproducts may be easily
removed from the plasma chamber by the vacuum system, while non-volatile and
low-volatile byproducts tend to be deposited on exposed surfaces within the
plasma chamber which is undesirable.
For etching of non-volatile and low-volatile materials, assume that maintaining the
main processing area at between 300-400C will keep the byproducts volatile and
hence keep the area clean. For numerous reasons (use of elastomer seals etc.) the
pumping system can not be maintained at these temperatures and there are
components in the pumping system which are susceptible to the effects of these
byproduct deposits. Valves, vacuum pumps and instrumentation can all fail
prematurely when exposed to certain etch byproducts.
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Quick Change Cold Trap Project

Hence the problem. The byproduct stream exiting the main processing area, which
is heated, enters the pumping system which is relatively cold (60C max) and
deposits causing a loss of pumping system performance and premature failure of
certain components.
Volatile Byproducts
Volatile Byproducts
Main Process Area
Pumping Plenum
Pumping System
T=300-400C
T=300-400C
T=60C Max
Main Chamber
unheated
Byproducts
deposited in
pumping system
No Byproducts
Scrubber
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Slide - 7
Quick Change Cold Trap Project

One solution is to place a cold trap between the plasma processing area and the
pumping system to collect the harmful byproducts.
Volatile Byproducts
Main Process Area
Pumping Plenum
T=300-400C
T=300-400C
Volatile Byproducts
Cold Trap
No Byproducts
Main Chamber
unheated
Byproducts
deposited in
Cold Trap
Pumping System
Scrubber
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Slide - 8
Primary Constraints





The Cold Trap inlet must mate to a pumping plenum which is heated to between
300-400C
Cold Trap should capture 99% of byproducts
Cold Trap can not back stream byproducts into the pumping plenum
Conductance of Cold Trap should be maximized to minimize impact to pumping
efficiency
Conductance from main chamber to Cold Trap to be less than 5% of the
conductance from the pumping plenum to the Cold Trap
– Assume the pressures in the main chamber and pumping plenum are 300mTorr and
the pressure in the Cold Trap is 100mTorr



Cold Trap should be serviceable in less than 3 hours without venting the main
chamber or cooling the main process area or pumping plenum
Cold Trap materials must be appropriate for use with Cl2
Cold Trap must be easy to clean or have an inexpensive disposable liner
– Cost of disposable parts if used to be less than $500.00

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Volume of Cold Trap and associated HW to be less than 3.75 cubic feet
– Cross Section, Inlet Port, Outlet Port, Connection Tube, Envelope
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Secondary Constraints


Temperature of outside surfaces of Cold Trap Assembly not to exceed 60C
Contamination Constraints
– Cold Trap can not contaminate the parts of the process module which see vacuum with oil,
or other contamination

No Particle Adders
– Process Module will be running in a Class 1 clean room

The less mechanisms the better – simple
– Easy to set-up, service, and maintain

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Highly reliable (Long term goal >10,000 hours MTBF)
Slide - 10
Q&A
Slide - 11
Envelope for Quick Change Cold Trap – 20.00”x27.00”x12.00”
17.00” above center line of inlet port, 10.00” below center line of inlet port,
10.00” to either side of the center line of the inlet port and 12.00” from face of inlet port
Center Line
of
Inlet Port
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