The HB-LED Standards Committee of industry association Semiconductor Equipment and Materials International (SEMI) has approved its first standard ‘SEMI HB1: Specifications for Sapphire Wafers Intended for Use for Manufacturing High Brightness-Light Emitting Diode Devices’.
Developed by the HB-LED Wafer Task Force (TF), SEMI HB1 defines and specifies the physical geometry of 150mm-diameter sapphire wafers used in high-brightness light-emitting diode (HB-LED) manufacturing. HB1 covers dimensional, wafer preparation, and crystallographic orientation characteristics, as well as the appropriate measurement methods. The document was approved by the HB-LED Committee during SEMI’s North America Standards Fall 2012 meeting’s recently completed procedural review and will be published in January.
Improving manufacturing efficiency and reducing cost are critical to enabling high-volume manufacturing, and 150 mm sapphire wafers represent a key inflection point, says SEMI. Five categories of single-crystal single-side polished sapphire wafers are covered in HB1, including:
- flatted 100mm diameter, 650μm thick, polished c-axis sapphire wafers;
- flatted 150mm diameter, 1000μm thick, polished c-axis sapphire wafers;
- flatted 150mm diameter, 1300μm thick, polished c-axis sapphire wafers;
- notched 150mm diameter, 1000μm thick, polished c-axis sapphire wafers; and
- notched 150mm diameter, 1300μm thick, polished c-axis sapphire wafers.
SEMI says that, as critical semiconductor technologies for energy efficiency, safety and next-generation displays, HB-LEDs promise huge opportunities in solid-state lighting, display backlighting and other high-brightness applications. Improvements in cost per lumen and the lighting quality of HB-LEDs parallel those of Moore’s Law, but reaching the full potential of LEDs requires the global LED manufacturing supply chain to collaborate on industry standards to eliminate unnecessary costs, and better enable equipment and process innovation, SEMI adds.
With this in mind, key industry stakeholders created the SEMI HB-LED Standards Committee in late 2010. The Committee and Task Forces consist of industry leaders in HB-LED devices, sapphire wafers, MOCVD wafer processing, and key equipment and materials suppliers to the LED industry. Since its formation, the HB-LED Committee has initiated Task Forces on wafers, carriers, assembly and automation. Committee co-chairs are: Iain Black (Philips Lumileds), Chris Moore (Semilab), David Reid (Silian), and Bill Quinn (WEQ).
HB-LED Wafer Task Force
The HB-LED Wafer TF is already developing a revision proposal for further refinements to the HB1 standard including:
- patterned sapphire substrate (PSS)-ready specification for 100mm and 150mm;
- double-sided polished wafer specifications;
- definitions and specifications of impurities and defects (wafer and bulk);
- laser marking and identification specification; and
- bow, warp measurements.
The task force will also begin its second round of the wafer marking experiment to characterize mark survivability, mark width and depth. The first experiment was conducted in 2012, where wafers (100mm flatted, 150mm 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, says SEMI.
Additional activities this year will include performing core and wafer defect inspection on ultrasonic technology and compare them with conventional methods. Two surveys – one on patterned sapphire substrates (PSS) and another on double-side polishing – will also be deployed in early 2013.
HB-LED Equipment Automation Task Force
The HB-LED Hardware Working Group (WG) of the Equipment Automation TF plans to re-ballot SEMI Draft Document 5420A (‘Specification for Cassettes for 150mm Sapphire Wafers Used in HB-LED Manufacturing’) for the upcoming Cycle 1, 2013 voting period.
Document 5420A was developed to define standards for cassettes used to handle 150mm sapphire wafers in HB-LED manufacturing. To minimize impact to the industry, the TF is leveraging existing 150mm silicon cassette standards with minor revisions. This will allow interoperability with existing 150mm equipment and any other 150mm-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.
A cassette standard will also enable standardization of load ports and transport systems, which the TF has started to address via SNARF (#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 150mm cassettes can be loaded and unloaded. This document defines a set of requirements and features to enable interoperability of load ports and carriers without limiting innovative solutions. The draft proposal for ballot 5468 is expected to be completed by Spring 2013.
The HB-LED Software WG of the Equipment Automation TF continues its development of a new specification for HB-LED manufacturing equipment communication interface (SNARF (#5469). SEMI Draft Document 5469 will define the software 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. The draft proposal for ballot 5469 is expected to be completed by this Spring.
A SNARF (#5529) for a ‘New Standard: Specification of Job Management and Material Management for High Brightness LED Manufacturing Equipment (HB-LED JMMM)’ was submitted by the TF and approved at a HB-LED committee meeting held last October (in conjunction with SEMI’s North America Standards Fall 2012 meetings). This new activity will address the need for an additional specification to standardize the material management and job management features in full automation HB-LED applications, such as the GEM300 E39, E40, E87, E90, E94 standards in the semiconductor industry. The additional standardization will be built on the foundation of the 5469 specification with additional concepts & requirements.
HB-LED Impurities & Defects Task Force
The Impurities & Defects TF will begin experiments and test methods based on the responses received to the ‘Defect vs Inspection Technique Relevance Survey’ that was deployed in mid-June. The survey aimed to identify sapphire wafer defects that are relevant or important to HB-LED manufacturing as well as inspection techniques that can be applied to identify, measure or prevent such defects.
Upcoming Meetings
The HB-LED Wafer TF, Equipment Automation TF and Impurities & Defects TF are meeting in conjunction with the Strategies in Light 2013 conference in Santa Clara, CA (12-14 February). The NA HB-LED committee and its task forces will then meet in conjunction with the North America Standards Spring 2013 meetings in San Jose, CA (1-4 April).
Taiwan LED Safety Task Force
The LED Safety Task Force was chartered in late 2011 under the Taiwan EHS (Environmental, Health and Safety) Committee to develop specifications and guidelines related to LED manufacturing equipment. The activities of the task force will result in the development of an EHS industry standard with which equipment suppliers, raw material suppliers, module makers and other involved parties can find conformity.
