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Contact point:
Milo Koretsky

VirtualCVD Reactor

Screenshot of the CVD reactor room in the virtual fabrication lab.

The VirtualCVD Reactor is a web-based educational tool. It is a realistic simulation of a Low Pressure Chemical Vapor Deposition (LPCVD) process in a chip fabrication facility.

If you already have an account, you can jump in to the 3D fabrication environment. Instructors can also use Web administration to create and monitor assignments.

Table of Contents
1.Acknowledgements
2.Overview
3.Features
4.How to Obtain an Account
5.Sample Assignment
6.Green Engineering
7.Movies
8.Quotes by Students
9.Contributors
      
Overview Video
(50MB | 30MB | 20MB)

Acknowledgements

National Science Foundation Intel Corporation Oregon State University

Funded by NSF CCLI DUE 0717905 (Phase 2), NSF CCLI DUE 0442832 (Proof of Concept) ,
the Intel Faculty Fellows Program, and Oregon State University. The main project contact point is
Milo Koretsky. See the contributors section for a list of all contributors.

Overview

Presently there is a need for more effective ways to integrate statistical methodologies such as Design of Experiments (DOE) into the engineering curriculum. We have developed a virtual chemical vapor deposition (CVD) reactor based on a numerical simulation where students learn and then actually apply DOE. Associated educational materials are also being developed. The simulation of the virtual reactor is based on fundamental principles of mass transfer and chemical reaction, obscured by added "noise." However, rather than having access to the entire output of the model, the film thicknesses are given to students only at the select points within the wafer and from wafer to wafer that the students have decided to "measure." This package is all housed within a three-dimensional user interface where students are placed in a simulated clean room environment. Student assessment is based not only on the ultimate reactor performance but also on the cost of experimentation.

This learning tool represents an innovative use of computers and simulation in integrating statistics into engineering education. Students are given a "capstone" experience in which they have the opportunity to synthesize engineering science and statistics principles to optimize a reactor's performance. Since the simulation is from first principles, students can interpret the outputs given by the DOE in terms of the chemical and physical phenomena in the system masked by the variation seen in real processes and measurements. The virtual reactor allows students a broader and more realistic experience in using the DOE methodology for process improvement — as if they were operating an actual industrial reactor.

The VirtualCVD project allows students to practice the type of skills they will use in the chip fabrication industry, thus enriching their education. Each student is given access to one or more LPCVD reactors, and one or more ellipsometry machines. The student will then work on an assignment of the instructor's choosing, such as achieving uniform deposition at a given thickness, or optimizing an existing process recipe for several reactors which differ in some aspect.

The virtual fabrication system is flexible; instructors can customize many parameters in the virtual environment. Our Web server keeps track of the (virtual) cost incurred by each student, the student's process recipes and measurement locations, and makes these accessible to the instructor in tabular and graphical form.

Features

Screenshot of an ellipsometry machine in use.
  • Realistic reactor and measurement system
  • The reactor can be used by many students at once, so students get more individual time with the equipment, and "hands on" experience can be gained more quickly.
  • Thus assignments take less time, and the assignment scope can be greater.
  • The equipment never breaks.
  • Instructors can enable and disable reactors and ellipsometers in the virtual world; up to 8 reactors and 4 ellipsometers may be used.
  • An instructor may use a suggested assignment, or customize and extend an assignment by changing the number of reactors, modifying reaction rates, setting biased thermocouples, adding measurement noise, etc.

How to Obtain an Account

A student is given an account by the instructor of a class. Please contact your instructor if you do not have an account or cannot access the system.

An instructor may sign up to use VirtualCVD at a learning institution or business. The software is Web-based, so you can apply to use this project from any geographical location where students and instructors have reliable Internet access. The 3D client program run by the student also requires Microsoft Windows.

Sample Assignment

This is an assignment developed for class by Dr. Milo Koretsky at Oregon State University. The CVD reactor processes two hundred 300 mm wafers, with a wafer spacing of 6.35 mm, and 5 temperature zones. Each furnace run costs $5,000, and each measurement costs $75. The students were asked to optimize reactor parameters so that the silicon nitride film is uniform within the wafer and from wafer to wafer at 1500 Å. The assignment document given to the students is available from here ( pdf | doc ).

Any instructor with a VirtualCVD account may create a similar assignment for use in his or her class. The instructor may customize the number of wafers, wafer diameter, wafer spacing, number of temperature zones, costs, etc.

The instructor is in charge of student accounts for the class. In the class at Oregon State, there were eight groups in the class, so eight student accounts were created and passwords were given out to each group.

At this point, the students may use the reactor and ellipsometer in the virtual fab to complete the assignment. A typical use of the reactor is shown in the screenshots below:

The student logs in.
The LPCVD furnace room.
The LPCVD furnace console.
Using the LPCVD console.
Begin animation for the LPCVD reactor. A first lot of wafers is placed in the boat.
A second lot of wafers is placed in the boat.
The full boat is raised up, run through the reactor; the processed boat is lowered.
Lots are removed from the reactor. End animation.
The run number is displayed on the LPCVD console.
Walk into the adjacent room...
...Which contains the ellipsometry machines.
Create a new measurement set.
Specify which wafers to measure.
Measure at the same positions for every wafer.
Specify the positions to measure on the wafer.
Lots are lowered into the ellipsometer loading bay.
A lot moves into the ellipsometer so measurements can be taken.
Lots are removed from the ellipsometer loading bay.
The measurement set number is displayed on the ellipsometer console.
At the main menu, choose view/export data.
One can view/export reactor parameters and measurement sets.
View the measurement set.
Export it.
Open in Excel.
Make a plot.

In this case, the wafer thickness at (0, 0) mm ranges from 3100 Å down to 0 Å. This is far from the optimal 1500 Å uniform target thickness. In Dr. Koretsky's class, students used Design of Experiments (DOE) and reaction kinetics to attempt to achieve the 1500 Å uniform target thickness.

Green Engineering

This is an assignment developed for instructors who intend to integrate concepts of Green Engineering. This activity is supported by a grant, Green Engineering Project from the EPA. The materials are developed around the text "Green Engineering - Environmentally Conscious Design of Chemical Processes" by Allen and Shonnard [1]. In this problem, the student will use the VirtualCVD reactor to minimize the utilization of dichlorosilane within manufacturing and cost constraints, i.e., the student will actually practice Green Engineering. ( pdf | doc ).

Movies

A video (15MB) of the 3D virtual fab is available.

An overview video (50MB | 30MB | 20MB) is also available.

Quotes by Students

From anonymous feedback during end of course assessment at Oregon State University:

  • "I really enjoyed the virtual CVD project because it was a complex problem that integrated course principles (processing, research, and thin films concepts). I thought the simulation ran really well."
  • "The Virtual Reactor Project is very cool."
  • "I really liked the VirtualCVD project because it forced us to complete a real DOE, following the proper steps rather than fudging through after completing the 1st part. That will be a valuable tool in many situations."
  • "The Virtual Reactor is very useful for understanding how a CVD reactor would be set-up in industry and the cost associated with running it."

Contributors

Milo KoretskyPrincipal investigator
.
Mathematical Model Development
Sho KimuraCVD reactor math model development
.
Software Development
Connelly BarnesLead computer programmer
Bill BrooksLead computer programmer
Jeff Noffsinger3D interface development
Derek Meyers-Graham    3D interface development
.
Information Technology
Paul MontagneFaculty Research Assistant, OSU
Keith PriceAsst Network Research, OSU
Steve ClevelandComputing Systems Analyst, OSU
.
Linus Pauling Chairs (Senior Lab)
David Hackleman
Philip Harding
.
Research Methods
Dr. Edith GummerThe Northwest Regional Educational Laboratory
Judith Devine
Tori Stewart
.
Student Researchers
Danielle AmatorePh.D. Candidate, OSU
Debra Gilbuena Graduate student, OSU
Odell Glenn Graduate student, OSU
Eric Gunderson Graduate student, OSU
Erick Nefcy Graduate student, OSU
Kendra Seniow Undergraduate student, OSU
Ben Sherrett Graduate student, OSU
Hyrum JonesStudent contributor
.
College Coordinator
Dave Hata
.
High School Coordinator
Adam KirschCrescent Valley High School
.
Advisory Group
Dr. Jeff ArthurProfessor of Statistics, OSU
Dr. Dave JohnsonProfessor of Physics, UO
Angela MitlehnerIntel
Manu RehaniLSI Logic
Dr. Tsai-Chen Wang    WaferTech

All content Copyright 2004-2006 Milo Koretsky.