Portland Community College | Portland, Oregon

This is Part III of the three course series on semiconductor process equipment. Part I (MT224) covers the individual components of process equipment (controllers, sensors, motors, etc.) Part II and III cover process equipment as a whole system. The LAM Rainbow etcher system is used as a typical example of a fab process system. Students will learn operations, theory of how various subsystems of the system function, maintenance procedures, and trouble shooting of the etcher. 

Students in this course are expected to be able to carry out independent research in order to discover the components and functions of the etcher system. They are also expected to be able to integrate their knowledge gained in MT224, MT240, and MT223 to gain insights into the etcher system.

I. Course Specific Knowledge and Professional Competence Learning Outcomes:

1. Understand modern semiconductor process equipment at various levels:

1.1.   Component level: Describe how components of process equipment work based on knowledge from MT224 (example: how does a stepper motor take discrete steps)

1.2.   Subsystem level: find out how a subsystem of process equipment works through research, reading schematics, etc. (Example: be able to investigate how a cassette indexer automatically controls feeding of wafers to the etcher with precision.)

1.3.   System level: Obtain a comprehensive understanding of the function of modern fab equipment from the very top level (computer controllers) to the bottom level individual components such sensors and motors and pneumatic valves. (Example: be able to describe under what conditions the controller issues what signals to command the stepper motors to go how many steps to cause the wafer transfer robots to move to what position.)  

2.      Gain a sense of confidence in working with fab equipment, which includes competence in the following three areas:

2.1.   Operation: gain proficiency in operating one tool—the Rainbow etcher

2.2.   Maintenance: learn and perform some basic industry standard maintenance procedures and be able to recover and return system to production worthy state.

Trouble shooting: perform simple trouble shooting tasks following a basic trouble-shooting methodology.

II. Transferable skill-set Learning Outcomes:

1.      Independent research skills: students have to carry out independent research in this course. Guidance and hints will be provided by the instructor. Resources in terms of manuals, schematic drawings and supplemental reading materials will be provided. From these starting points students will carry out independent investigation of the etcher system. You will learn how to find out answers on your own. You will learn to ask pertinent questions and set them up as goals of your research. You will learn to adopt strategies to achieve your research goals in an efficient manner. You will learn to define the scope of your research. You will learn to gather clues to guide you in your research. You will learn to draw upon your previous knowledge gained to support your current research.

2.      Learn how to handle complexity: The etcher is a complex system. In all of your previous MT courses, you have learned how to deal with component level systems (e.g. a circuit, a DC motor, etc.). Now you are asked to handle a much more complex integrated system with thousands of individual components. You will learn how to handle this complexity.

3.      Team work skills: students have to work in groups of four to eight people. You have to count on fellow team members to pool your knowledge and effort together to be able to accomplish your research, maintenance and trouble shooting tasks. You will learn to divide up labor efficiently.

4.      Communication skills: students should be able to communicate effectively to fellow students and the instructor the findings of their research projects and progress in their maintenance and trouble shooting tasks. Students will also learn to read and understand relevant specs and procedures.

The course will include instructor delivered lectures and demonstrations stressing key topics in the course. In preparation for the lecture portion of the course, students will be expected to complete all reading and homework assignments. Students will perform independent research, preventative maintenance, and trouble-shooting in class. Students may be required to come to the lab after school to work in groups on equipment as a part of homework.

Assessment of student performance in this course will be in the form of written and/or practice-based questions. Some formal reports and presentations are required also.

REQUIRED STUDENT COMPETENCIES:
1.0 Wafer Transfer System Alignment (week1, 2)
1.1 Understand the degrees of freedom a rigid body can have in 3 dimensional space, i.e. displacement freedom along x, y, z axis and rotation around x, y, z axis. Understand the alternative polar coordinate system of r, theta, and height.
1.2 Be able to read and understand conceptually a typical alignment procedure between two components of the wafer transfer system—the sender and the receiver (example: transfer of wafer from cassette indexer to the shuttle arm of the Lam etcher) following the methodology below:
Step1: Identify degrees of freedom the system has.
Step2: Identify in which degrees of freedom, adjustment is necessary.
Step3: Identify what mechanism the equipment uses to adjust alignment in each degree of freedom.
Step4: Find out the order of alignment—which degree of freedom of the system needs to be aligned first, second, …etc.
1.3 Upon reading Lam alignment procedure, be able to organize individual steps into groups to better organize and understand the steps of the procedures. (i.e. step 1-4 may all describe adjustment of height and leveling)
1.4 By reading schematics and by observing the operations of an actual piece of equipment, be able to develop an alignment procedure for the equipment following the methodology above.
1.5 Be able to perform alignment procedures described in the Lam etcher manual.
1.6 While performing the alignment procedure, be able to use observation of relevant indicators as a feed-back to judge whether the alignment is off in certain dimensions.

2.0 Process Chamber (week 3-6)
2.1 Understanding of the components of the process chamber and its subsystems—upper electrodes, lower electrodes*, and the gap drive. (*lower electrode is optional this year)
2.1.1 Be able to read a cross sectional or exploded view schematic and discern the various parts of a subsystem and discern their spatial relations
2.1.2 Be able to locate the components on the etcher with the aid of a schematic
2.1.3 Describe the function that each component performs.
2.1.4 Describe the major functions of the process chamber. Be able to discover and then describe how the functions of the process chamber as a whole are achieved by the functions of the individual components. The major functions of the process chamber should include: RF delivery, gas delivery, pressure control, temperature control including He cooling and wafer clamping, gap distance control and end point detection.
2.2 Understand how process parameters affect processes which occur during etch, and in turn etch properties (such as etch rate).
2.3 Preventative Maintenance (PM):
2.3.1 Be able to perform the following Preparation Procedures:
P1: Automatic chamber vent
P2: Manual chamber vent
P3: Automatic pump and purge cycle
2.2.2 Be able to perform the following verification procedures:

V1. Rate of rise check
V2. Upper electrode centering
V3 Lower clamp centering (*optional this year)
V4 Gap parallelism calibration
V5 Gap spacing calibration
(V6 Particle scan) optional
(V7 Etch rate scan) optional
2.2.3 Be able to perform the following upper electrode PM procedures:
U1. Confinement ring removal and replacement
U2. Clamp/ plunger attachment plate removal and replacement
U3. Upper electrode removal and replacement (including upper electrode centering)
2.2.4 *Be able to perform the following lower electrode PM procedures: (*optional this year)
L1. Lower clamp removal and replacement (including lower clamp centering)
L2. Lower electrode removal and replacement (needs to perform lower clamp centering)
2.2.5 * Be able to perform chamber clean PM procedure (*optional this year)
2.2.6 Demonstrate good PM practices while performing the above PMs (for example, lay out parts in advance of PM, noting how to put things back while taking them apart)
2.2.7 Demonstrate good PM strokes while performing the above PMs (for example, holding both sides of ranches so as not to damage the electrode)
2.2.8 Be able to understand a PM by reading spec. Be able to dissect a complex PM procedure into simpler blocks.
2.2.9 Be able to come up with the right sequence of steps to perform in a related hypothetical PM (example, rate of rise of ELL).

3.0 Vacuum System (week 7-8)
3.1 Understanding of the components of the vacuum system
3.1.1 Be able to identify the various components of a subsystem and discern their functions by inspecting and observing the subsystem by eye. Subsystems should include: process chamber, ELL, and XLL.
3.1.2 Be able to draw a schematic of how the various components are linked with each other in a subsystem.
3.1.3 Describe the major functions of a subsystem. Be able to discover and then describe how the functions of the vacuum system as a whole are achieved by the functions of the components. The major functions of the vacuum system should include: venting, purging, pump down, and pressure control.
3.2 Be able to read a flow diagram of the process gas delivery system and discern how gases are flown into the chamber
3.3 Given a diagram, show the valving sequence to get a process gas to flow into the chamber.
3.4 Be able to design the right sequence of events to achieve certain task of the etcher (example, vent ELL manually)

4.0 Trouble-shooting (week 9, 10)
4.1 Be able to form an objective problem statement
4.2 Be able to form a clear mental picture of the entire system involved in the problem
4.3 Be able to design and then carry out quick and definitive tests to isolate the problem to a subsystem.
4.4 Be able to make a list of all possible causes of the problem in this sub-system.
4.5 Be able to design quick and definitive tests to verify whether a possible cause is the true cause or not.
4.6 Be able to prioritize to see which possible causes to check first based on the ease of the check and the probability of the cause
4.7 Be able to gather and use clues to judge which path to follow. (Given the clues, what is the likely cause? Training of this judgment)