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2.830J / 6.780J / ESD.63J Control of Manufacturing Processes (SMA 6...
Control of
  Manufacturing Processes
                Subject 2.830/6.780/ESD.63
                       Spring 2008
       ...
Background
•   Pre-requisites
•   Your Background and Interests
•   Relevant Experience
•   Course Schedule




    Manufa...
Expectations
• Assignments ~ Weekly
• 2 Quizzes in Class
• Group Project
   – End of term presentation
   – Report




  M...
Syllabus Details
• Lecturers
   – Duane Boning
   – David Hardt
• Course Secretary: Sharlene Blake




  Manufacturing    ...
Syllabus Details
• Prerequisites: One of the following :
   – 2.008 or 2.810 Manufacturing
   – 2.751J or 6.152J or 6.041 ...
Team Projects
• Topics:
   –   Process Diagnosis
   –   Process Improvement
   –   Process Optimization / Robustness
   – ...
Main Topics
• Physical Origins of Variation
   – Process Sensitivities
• Statistical Models and Interpretation
   – Proces...
Manufacturing Process Control
• Process Goals
   –   Cost
   –   Quality
   –   Rate
   –   Flexibility




  Manufacturin...
Focus
• Unit Operations
• (1) Maximizing Quality
   – Conformance to Specifications
• (2) Improving Throughput
• (3) Impro...
Typical Process Control Problems

• Minimum feature size on a semiconductor
  chip has too much variability
• DNA diagnost...
Typical Process Control Problems
• Airframe skin needs trimming and bending to
  fit frame
• Web thickness of a machined p...
Other Related Problems –
           Cost, Rate and Flexibility:
• 100% inspection with high scrap rates
     – low through...
Manufacturing Processes

• How are they defined?
• How do they do their thing?
• How can they be categorized?

• Why don’t...
The Process Components



Operator                                 Workpiece           Part
                    Equipment
...
Process Definition



A Manufacturing Process is a Change in the
Workpiece Material
• A change in geometry
• A change in c...
Conceptual Semiconductor Process Model




                 Image removed due to copyright restrictions. Please see Fig.
 ...
Simplified Conceptual Semiconductor
              Process Model



                Image removed due to copyright restrict...
Example: Oxidation

Wafer states


                  Image removed due to copyright restrictions. Please see Fig.
        ...
Example: Oxidation
Treatment (wafer environment)




                     Image removed due to copyright restrictions. Ple...
Oxidation Models




                                                   Analytic: Deal-Grove
                    Images re...
(Semiconductor) Manufacturing
                       Process Control




                     Image removed due to copyrig...
Process Model for Control


“controls”                    E(t )                 Geometry
                  Equipment      ...
The General Process Control Problem
Desired
Product                                                               Product
...
Process Control Hierarchy
• Reduce Disturbances
   –   Good Housekeeping            (Ops Management)
   –   Standard Opera...
Back to the Process: What Causes the
           Output Change?
• A Directed Energy Exchange with the Equipment

          ...
Modes of Geometry Change?
•   Removal of Material
•   Plastic Deformation of Material
•   Addition of Material
•   Formati...
What Causes Variation
                 in the Process Output?
• Material Variations
   – Properties, Initial Geometry
• Eq...
Process Model for Control


“controls”                    E(t )                 Geometry
                  Equipment      ...
What are the
                Process Parameters?

• Equipment Energy “States”
• Equipment Constitutive “Properties”

• Mat...
Energy States


Energy Domain          Energy or Power Variables
Mechanical            F, v ; P, Q or F, d ; σ, ε
Electric...
Properties
• Extensive: GEOMETRY
• Intensive: Constitutive Properties
   –   Modulus of Elasticity, damping, mass
   –   P...
A Model for Process Variations

“controls”                    E(t )              Geometry
                  Equipment     ...
The Variation Equation

        ∂Y                   ∂Y
   ΔY =    Δα              +    Δu
        ∂α                   ∂u...
Primary Process Control Goal: Minimize ΔY

      How do we make ΔY → 0                   ?
                        ∂Y     ...
OR

             ∂Y               ∂Y
        ΔY =    Δα          +    Δu         ΔY → 0
             ∂α               ∂u

...
OR

                 ∂Y        ∂Y
            ΔY =    Δα   +    Δu          ΔY → 0
                 ∂α        ∂u
•    mani...
Statistical Process Control

               ∂Y            ∂Y
          ΔY =    Δα       +    Δu
               ∂α         ...
Process Optimization

               ∂Y              ∂Y
          ΔY =    Δα         +    Δu
               ∂α            ...
Output Feedback Control

               ∂Y                   ∂Y
          ΔY =    Δα              +    Δu
               ∂...
Process Control Hierarchy
• Reduce Disturbances
   –   Good Housekeeping
   –   Standard Operations (SOP’s)
   –   Statist...
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Control of Manufacturing Processes

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Control of Manufacturing Processes

  1. 1. MIT OpenCourseWare ____________ http://ocw.mit.edu 2.830J / 6.780J / ESD.63J Control of Manufacturing Processes (SMA 6303) Spring 2008 ________________ For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.
  2. 2. Control of Manufacturing Processes Subject 2.830/6.780/ESD.63 Spring 2008 Lecture #1 Introduction February 5, 2008 Manufacturing 1
  3. 3. Background • Pre-requisites • Your Background and Interests • Relevant Experience • Course Schedule Manufacturing 2
  4. 4. Expectations • Assignments ~ Weekly • 2 Quizzes in Class • Group Project – End of term presentation – Report Manufacturing 3
  5. 5. Syllabus Details • Lecturers – Duane Boning – David Hardt • Course Secretary: Sharlene Blake Manufacturing 4
  6. 6. Syllabus Details • Prerequisites: One of the following : – 2.008 or 2.810 Manufacturing – 2.751J or 6.152J or 6.041 or 15.064J • Required Texts: – Montgomery, D.C., Introduction to Statistical Quality Control, 5th Ed. Wiley, 2005 – May and Spanos, Fundamentals of Semiconductor Manufacturing and Process Control, John Wiley, 2006. • Grading: – Problem sets 40% – Quizzes 40% – Team Projects 20% • Assignments: All except project are to be individual efforts • Final exam: No final exam • Course URL: (Registration and Certificate Required) Manufacturing 5
  7. 7. Team Projects • Topics: – Process Diagnosis – Process Improvement – Process Optimization / Robustness – Advanced Applications • Expectations – Background research on process and problem – Use of existing data or generation of new data – Oral presentation of results – Project report from group Manufacturing 6
  8. 8. Main Topics • Physical Origins of Variation – Process Sensitivities • Statistical Models and Interpretation – Process as a Random Variable(s) – Diagnosis of Problems • Effects Models and Designed Experiments – Input - Output Empirical Models • Process Optimization (Robustness) – Ideal Operating Points Manufacturing 7
  9. 9. Manufacturing Process Control • Process Goals – Cost – Quality – Rate – Flexibility Manufacturing 8
  10. 10. Focus • Unit Operations • (1) Maximizing Quality – Conformance to Specifications • (2) Improving Throughput • (3) Improving Flexibility • (4) Reducing Cost Manufacturing 9
  11. 11. Typical Process Control Problems • Minimum feature size on a semiconductor chip has too much variability • DNA diagnostic chip has uneven flow channels • Toys never fit when assembled at home! • Next generation high density electrical connector cannot be made reliably Manufacturing 10
  12. 12. Typical Process Control Problems • Airframe skin needs trimming and bending to fit frame • Web thickness of a machined panel is non- uniform • Plastic throttle bodies for fuel injection are out of round • Submarine hull welds need constant rework in production Manufacturing 11
  13. 13. Other Related Problems – Cost, Rate and Flexibility: • 100% inspection with high scrap rates – low throughput – high costs • 100% inspection with frequent rework – low throughput – high costs • High variability at changeover – Reluctance to changeover – low flexibility Manufacturing 12
  14. 14. Manufacturing Processes • How are they defined? • How do they do their thing? • How can they be categorized? • Why don’t they always get it right? Manufacturing 13
  15. 15. The Process Components Operator Workpiece Part Equipment Material • Etch bath • Coated Silicon • IC chip • Injection Molder • Plastic Pellets • Connector Body • Lathe • Bar stock • Shaft • Draw Press • Sheet Metal • Hood • ... • ... • ... Manufacturing 14
  16. 16. Process Definition A Manufacturing Process is a Change in the Workpiece Material • A change in geometry • A change in constitutive properties Manufacturing 15
  17. 17. Conceptual Semiconductor Process Model Image removed due to copyright restrictions. Please see Fig. 1 in Boning, D. S., et al. “A General Semiconductor Process Modeling Framework.” IEEE Transactions on Semiconductor Manufacturing 5 (November 1992): 266-280. Boning et al., c. 1990 Manufacturing 16
  18. 18. Simplified Conceptual Semiconductor Process Model Image removed due to copyright restrictions. Please see Fig. 15 in Boning, D. S., et al. “A General Semiconductor Process Modeling Framework.” IEEE Transactions on Semiconductor Manufacturing 5 (November 1992): 266-280. Manufacturing 17
  19. 19. Example: Oxidation Wafer states Image removed due to copyright restrictions. Please see Fig. 17 in Boning, D. S., et al. “A General Semiconductor Process Modeling Framework.” IEEE Transactions on Semiconductor Manufacturing 5 (November 1992): 266-280. Manufacturing 18
  20. 20. Example: Oxidation Treatment (wafer environment) Image removed due to copyright restrictions. Please see Fig. 18 in Boning, D. S., et al. “A General Semiconductor Process Modeling Framework.” IEEE Transactions on Semiconductor Manufacturing 5 (November 1992): 266-280. Manufacturing 19
  21. 21. Oxidation Models Analytic: Deal-Grove Images removed due to copyright restrictions. Please see Fig. 19 and 20 in Boning, D. S., et al. “A General Semiconductor Process Modeling Framework.” IEEE Transactions on Semiconductor Manufacturing 5 (November 1992): 266-280. Empirical: Change in wafer state Empirical: Equipment model for mean and std. Manufacturing dev. of oxide thickness 20
  22. 22. (Semiconductor) Manufacturing Process Control Image removed due to copyright restrictions. Please see Fig. 26 in Boning, D. S., et al. “A General Semiconductor Process Modeling Framework.” IEEE Transactions on Semiconductor Manufacturing 5 (November 1992): 266-280. Manufacturing 21
  23. 23. Process Model for Control “controls” E(t ) Geometry Equipment Material & Properties Process Y ≡ Process Ouputs Y = Φ(α ) α ≡ process parameters What are the α’s? Hardt, c. 1995 Manufacturing 22
  24. 24. The General Process Control Problem Desired Product Product CONTROLLER CONTROLLER EQUIPMENT EQUIPMENT MATERIAL MATERIAL Equipment loop Material loop Process output loop Control of Equipment: Control of Material: Control of Product: Forces, Strains Geometry Velocities Stresses and Temperatures, , .. Temperatures, Properties Pressures, .. Manufacturing 23
  25. 25. Process Control Hierarchy • Reduce Disturbances – Good Housekeeping (Ops Management) – Standard Operations (SOP’s) – Statistical Analysis and Identification of Sources (SPC; 2.830J) – Feedback Control of Machines (Automation and Control; 2.168) • Reduce Sensitivity (Process Optimization or Robustness) – Measure Sensitivities via Designed Experiments (2.830J) – Adjust “free” parameters to minimize • Measure output and manipulate inputs – Feedback control of Output(s) (2.830J) Manufacturing 24
  26. 26. Back to the Process: What Causes the Output Change? • A Directed Energy Exchange with the Equipment E(t ) Geometry Equipment Material & Properties ⎧mechanical ⎫ ⎪electrical ⎪ ⎪ ⎪ E(t ) → ⎨ ⎬ ⎪thermal ⎪ ⎪chemical ⎪ ⎩ ⎭ Manufacturing 25
  27. 27. Modes of Geometry Change? • Removal of Material • Plastic Deformation of Material • Addition of Material • Formation of Material from a Gas or Liquid • Any others??? Manufacturing 26
  28. 28. What Causes Variation in the Process Output? • Material Variations – Properties, Initial Geometry • Equipment Variations – Non-repeatable, long term wear, deflections • Operator Variations – Inconsistent control, excessive “tweaking” • “Environment” Variations – Temperature and Handling inconsistencies Manufacturing 27
  29. 29. Process Model for Control “controls” E(t ) Geometry Equipment Material & Properties Process Y ≡ Process Outputs Y = Φ(α ) α ≡ process parameters What are the α’s? Manufacturing 28
  30. 30. What are the Process Parameters? • Equipment Energy “States” • Equipment Constitutive “Properties” • Material Energy “States” • Material Constitutive ”Properties” Manufacturing 29
  31. 31. Energy States Energy Domain Energy or Power Variables Mechanical F, v ; P, Q or F, d ; σ, ε Electrical V,I Thermal T, ds/dt (or dq/dt) Chemical chemical potential, rate Manufacturing 30
  32. 32. Properties • Extensive: GEOMETRY • Intensive: Constitutive Properties – Modulus of Elasticity, damping, mass – Plastic Flow Properties – Viscosity – Resistance, Inductance, Capacitance – Chemical Reactivity – Heat Transfer Coefficient • Which has the highest precision? Manufacturing 31
  33. 33. A Model for Process Variations “controls” E(t ) Geometry Equipment Material & Properties • Recall: Y = Φ(α ) • One or more α’s “qualify” as inputs : u Y = Φ(α ,u ); u = vector of inputs • The first order variation ΔY gives the “Variation Equation” Manufacturing 32
  34. 34. The Variation Equation ∂Y ∂Y ΔY = Δα + Δu ∂α ∂u Control Inputs Disturbance Control Sensitivity Sensitivity or “Gain” Disturbances Manufacturing 33
  35. 35. Primary Process Control Goal: Minimize ΔY How do we make ΔY → 0 ? ∂Y ∂Y ΔY = Δα + Δu ∂α ∂u • hold u fixed (Δu = 0) – operator training (SOP’s) – good steady-state machine physics • minimize disturbances Δα ->Δαmin This is the goal of Statistical Process Control (SPC) Manufacturing 34
  36. 36. OR ∂Y ∂Y ΔY = Δα + Δu ΔY → 0 ∂α ∂u • hold u fixed (Δu = 0) • minimize the term: ∂Y the disturbance sensitivity ∂α This is the goal of Process Optimization ∂Y • Assuming ∂α = Φ(α ) α = operating point Manufacturing 35
  37. 37. OR ∂Y ∂Y ΔY = Δα + Δu ΔY → 0 ∂α ∂u • manipulate Δu by measuring ΔY such that ∂Y ∂Y Δu =− Δα ∂u ∂α This is the goal of Process Feedback Control • Compensating for (not eliminating) disturbances Manufacturing 36
  38. 38. Statistical Process Control ∂Y ∂Y ΔY = Δα + Δu ∂α ∂u Detect and Minimize Manufacturing 37
  39. 39. Process Optimization ∂Y ∂Y ΔY = Δα + Δu ∂α ∂u Empirically Minimize Manufacturing 38
  40. 40. Output Feedback Control ∂Y ∂Y ΔY = Δα + Δu ∂α ∂u ∂Y ∂Y Manipulate Δu = − Δα Actively ∂u ∂α Such That Compensate for Disturbances Manufacturing 39
  41. 41. Process Control Hierarchy • Reduce Disturbances – Good Housekeeping – Standard Operations (SOP’s) – Statistical Analysis and Identification of Sources (SPC) – Feedback Control of Machines • Reduce Sensitivity (increase “Robustness”) – Measure Sensitivities via Designed Experiments – Adjust “free” parameters to minimize • Measure output and manipulate inputs – Feedback control of Output(s) Manufacturing 40

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