SEMI HB-LED Technical Committee Approves Second HB-LED Standard
By Paul Trio, SEMI Standards
Sapphire wafers are widely used in the manufacturing of HB-LED (High-Brightness Light-Emitting Diode) devices. These sapphire wafers are thicker than standard silicon wafers used in the semiconductor industry making it difficult to use the same cassettes and standards for HB-LED manufacturing. A basic prerequisite for building highly efficient HB-LED fabs is automated material handling. Cassettes with larger pockets and more space between wafers are needed for reliable automated handling of these sapphire wafers. Manufacturers and equipment suppliers are currently spending a significant amount of time and effort on ensuring adequate material handling within their production lines. By relying on standardized material handling, HB-LED manufacturers will be able to focus on their core competences.
At the North America (NA) Standards Spring 2013 meetings, the HB-LED Technical Committee approved SEMI Draft Document 5420A, New Standard: Specification for 150mm Open Plastic and Metal Wafer Cassettes Intended for Use for Manufacturing HB-LED Devices. Pending successful procedural review, this Document will be published as SEMI HB2, the second HB-LED Standard published by SEMI.
Developed by the Hardware Working Group of the HB-LED Equipment Automation Task Force, SEMI HB2 provides the dimensional requirements for plastic and metal wafer cassettes used for the processing and handling of 150 mm diameter HB-LED sapphire wafers conforming to the SEMI HB1 Standard. SEMI HB1 defines and specifies the physical geometry of 150 mm diameter sapphire wafers used in HB-LED manufacturing. These specifications cover dimensional, wafer preparation, and crystallographic orientation characteristics for five categories of single-crystal single-side polished sapphire wafers.
To minimize impact to the industry, the HB-LED Equipment Automation Task Force leveraged existing 150 mm silicon cassette standards with minor revisions. This allowed interoperability with existing 150 mm equipment and any other 150 mm compatible products. Considerations were taken around the cassette’s pocket size and spacing so that the sapphire wafers can be successfully transferred between cassettes with automated handling equipment.
Figure 1: General Usage Cassette Outline for 150 mm Wafers
A cassette standard will also enable standardization of load ports and transport systems. This will result in direct and indirect cost savings throughout the whole supply chain, less risk during ramp up and less effort for integration of the production line.
SEMI HB-LED Activities Continue
The HB-LED Committee is actively working on multiple other activities, organized within its various task forces.
HB-LED Equipment Automation Task Force
In addition to SEMI Draft Document 5420A, the HB-LED Hardware Working Group (WG) of the Equipment Automation TF has been working on SEMI Draft Document 5468, New Standard: Mechanical Interface Specification for 150mm HB-LED Load Port. SEMI Draft Document 5468 will define the basic interface dimensions of a load port and their arrangements on HB-LED manufacturing equipment, where HB-LED 150 mm cassettes can be loaded and unloaded. These interface specifications include:
- Location of physical interface between an HB-LED cassette and HB-LED manufacturing equipment.
- Definition of load port volume and horizontal spacing on the equipment.
- Ergonomic clearances for manual cassette handling.
- RFID reader/writer volumes
This Document defines a set of requirements and features to enable interoperability of load ports and carriers without limiting innovative solutions. Document 5468 will be submitted for the Cycle 3, 2013 voting period for Letter Ballot distribution.
The HB-LED Software WG of the Equipment Automation TF plans to submit SEMI Draft Document 5469 for Cycle 4, 2013 voting period. Document 5469 is a new standard specification for communication interfaces for HB-LED manufacturing equipment.
The purpose of this Standard is to define the equipment automation interface for communication and control of process, automation and metrology equipment used in HB-LED manufacturing. It intends to produce economic benefits for both manufacturers and equipment suppliers by identifying a subset of relevant functionalities out of the existing SEMI communications standards for the application in HB-LED manufacturing facilities.
On one hand, this Standard should reduce the effort of manufacturers to integrate equipment in their IT factory automation system. On the other hand, equipment suppliers could reduce their effort for developing and maintaining a variety of equipment communication interfaces. This Document is expected to provide a proven set of communication functionality to reduce both costs and time for ramp-up of new equipment in the manufacturing production environment.
Document 5469 references a collection of SEMI (e.g., E5, E30, E37/E37.1) and other standards and should give guidance how to apply them in HB-LED manufacturing environment in order to establish a reliable and extensible communication framework for the IT integration of equipment.
HB-LED Wafer Task Force
- laser marking and identification specification;
- definitions and specifications of impurities and defects;
- patterned sapphire substrate (PSS)-ready specification for 100mm and 150mm;
- double sided polished wafers specifications;
- updated surface roughness parameters & test methods; and
- reclaimed wafer specifications
The task force also continues its second round of the wafer marking experiment to characterize mark survivability, mark width, and depth. The first experiment was conducted last year where wafers (100 mm flatted, 150 mm notched) with front and back-surface marks (i.e., data matrix and OCR) were subjected to various surface modifications (e.g., slicing, grinding, polishing, GaN Ep). The outcome of the first experiment showed promising results.
The HB-LED committee and its task forces will meet in conjunction with the NA Standards meetings at SEMICON West 2013 in San Francisco, California. For more information and to register for these meetings, please visit the SEMI Standards website. For more information about SEMICON West 2013, visit www.semiconwest.org.
SEMI Standards Resources
SEMI, Standards Watch - May 2013