Research Project Information

Research Project Summary Information

Productivity Improvement to Reduce Energy Costs to Produce Aluminum Nitride Substrates for UV LED Development(ST9908-1)

Crystal IS, Incorporated


The goal of the project was to increase efficiency and yield of the Crystal IS, Inc. (CIS) Aluminum Nitride (AlN) crystal growth process. AlN substrates are becoming an increasingly important material for the production of solid state devices that produce ultraviolet light (e.g., blue-ray lasers, ultraviolet lights for purification and sterilization applications, and devices used for high performance lighting applications). CIS has previously developed a unique production method for AlN that uses high temperature sublimation of aluminum in a nitrogen-rich environment. While the process produced usable crystals, there were process optimization challenges they anticipated could be addressed through the application of modeling and model-based control.

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Project Description

Process optimization is an iterative process. The work was comprised of three main segments - process modeling, experimental validation of the models, and implementation on equipment installed at the CIS facility. Initially, modeling was performed using best-known data. As the model was used in production, additional data was developed, and the fidelity of the model refined.


The primary metric evaluating the growth process is the crack-free yield, defined as the percentage of wafers produced from AlN crystals, or boules, without detrimental cracking. (Wafers are cut from boules.) At the beginning of the effort crack-free AlN wafer yield was approximately 15-20%; by the conclusion of the project the crack-free yield had increased to greater than 60%. By improving yield, energy consumption has been reduced and per wafer cost lowered. These improvements are enabling CIS to market its products more competitively and should increase future economic success.

Project Results

CIS worked closely with engineers at RPI to develop improved thermal-stress and heating control models specific to the AlN crystal growth process. Enhanced crack-free yield was accomplished through an iterative approach that relied on model-based process improvements. As a result, a series of model suggested and validated improvements have been incorporated into the CIS crystal growth process. Optimized process improvements have been applied to other growth stations; increasing crack-free yield across CIS’s manufacturing processes.


Crystal IS, Incorporated
70 Cohoes Ave
Green Island, NY 12183

Principle Investigator

Leo Schowalter

Universities Involved


Project Type:

On-site Process Improvement

Technologies Types:

Advanced Materials

NYSERDA Contact Information

Kathleen O'Connor


R&D - Environment & Energy Res

Contract Details

Start Date: 1/11/2010
Project Status: Active
Contract Number: ST9908-1

Last Updated: 11/13/2013