Solar Cell Metallization Lab Module

1
Solar Cell Metallization Lab Module

• End of Semester Report for
• Senior Design Project
• Luis Curiel
• Dr. Emily Allen, Advisor
• MatE198A, Fall 2001

2
End Semester Report Outline

• Introduction
• Statement of the problem
• Design project objectives
• Background
• Feasibility study
• Milestone schedule
• Conclusion
• Acknowledgment

3
Introduction

• Demand for electrical power
• Solar energy
• renewable source
• solar cell
• Solar cell
• semiconductor technologies

4
Statement of the Problem

• Solar cell test module
• Spartan solar cell design
• Center for Electronic Materials and Devices
• Solar cell fabrication lab module

5
Design Project Objectives

• Design student learning objectives
• Design process flow
• Design and produce lab manuals
• Prepare homework and in-lab questions
• Develop a cost spreadsheet

6
Student Learning Objectives

• After completing this lab module, students will
  be able to
• make a solar cell
• demonstrate use of a Material Safety Data Sheet
• describe photolithography
• draw cross sectional sketches
• describe doping of silicon

7
Solar Cell Design
photons
RL
p-type silicon
SiO2
Aluminum
n-type silicon
8
Background
p-type Si
n-type SI
conduction band
-

e-
valence band

photons
e-

e- hole pair generation
9
Feasibility Study Objectives

• Budget
• Safety
• Process flow
• evaluate student processing time
• evaluate equipment

10
Budget - Cost
11
Budget - Overall

• Estimated budget 3,500.00 /semester
• wafer prep
• wafers, chemicals, lab assistants
• student metallization process
• chemicals, lab assistants
• Additional cost
• lab manuals
• furnace

12
Design for Safety

• Identify safety hazards
• photoresist spinner
• UV light source
• photoresist developer
• Aluminum etch
• photoresist stripper

13
Design for Safety Example

• Safety hazard
• photoresist developer on counter
• Risk assessment
• spill or skin contact
• Design safety protocol
• lab assistant, lab group size, safety glasses,
  lab coat, gloves, pants and closed toe shoes

14
Process Flow
Spin Photoresist
Bake Photoresist
Tested with MatE129 students
Expose Photoresist
Develop Photoresist
Etch Aluminum
Strip Photoresist
15
Process Flow Experiment

• Student process time for 8 wafers
• 15 min spin photoresist
• 15 min bake photoresist
• 35 min expose and develop photoresist
• 15 min etch Aluminum
• 20 min strip photoresist
• Total student process time 1hr 40min
• Problem student process time scales

16
Optimize Student Processing
Spin-gtBake-gtExpose Develop-gtEtch-gtStrip
17
Experiment Results

• Optimize processing time
• Processing equipment
• photoresist spinner
• UV light source
• oven
• hot plates
• furnace
• Aluminum evaporator

18
Design Milestone Schedule
19
Conclusion

• Feasibility study completed
• lab module can be safely completed in one lab
  period
• Prepare lab module for Engr.10
• run lab module Spring 2002
• Optimize lab module to further reduce cost

20
Acknowledgment

• Neil Peters, Microelectronics Processing Lab
  Engineer