SEMI publishes HB-LED standard relating to sapphire substrates

Jan. 15, 2013
Several SEMI task forces have been developing standards related to LED manufacturing, and the first of these, describing specifications for 150-mm-diameter sapphire wafers, has now been approved.
The HB-LED Standards Committee of SEMI, the global semiconductor industry association, has approved its first LED-related standard, entitled “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, SEMI HB1 defines and specifies the physical geometry of 150-mm-diameter sapphire wafers used in 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 the North America Fall 2012 meetings, recently completed procedural review and will be published in January 2013.

Improving manufacturing efficiency and reducing cost are critical to enabling high-volume LED manufacturing, and 150 mm sapphire wafers represent a key inflection point.

Five categories of single-crystal, single-side polished sapphire wafers are covered in HB1, including:

  • Flatted 100 mm diameter, 650 μm thick, polished c-axis sapphire wafers
  • Flatted 150 mm diameter, 1,000 μm thick, polished c-axis sapphire wafers
  • Flatted 150 mm diameter, 1,300 μm thick, polished c-axis sapphire wafers
  • Notched 150 mm diameter, 1,000 μm thick, polished c-axis sapphire wafers
  • Notched 150 mm diameter, 1,300 μm thick, polished c-axis sapphire wafers.

SEMI standards development

SEMI believes that in order to reach the full potential of LEDs, there is a need for the global LED manufacturing supply chain to collaborate on industry standards to eliminate unnecessary costs, and better enable equipment and process innovation.

With this in mind, key industry stakeholders created the SEMI HB-LED Standards Committee in late 2010. The Committee and Task Forces are comprised of industry leaders in HB-LED devices, sapphire wafers, MOCVD wafer processing, and key equipment and materials suppliers to the LED industry.

Since 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). Ongoing activities include the following:

HB-LED Wafer Task Force (TF)

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 wafers specifications
  • definitions and specifications of impurities and defects (wafer and bulk)
  • laser marking and identification specification
  • bow, warp measurements.

HB-LED Equipment Automation Task Force

The Equipment Automation TF has developed draft document 5420A entitled “Specification for Cassettes for 150 mm Sapphire Wafers Used in HB-LED Manufacturing.”

To minimize impact to the industry, the TF is leveraging existing 150-mm silicon cassette standards with minor revisions. This will allow 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. A cassette standard will also enable standardization of load ports and transport systems.

HB-LED Impurities & Defects Task Force

The Impurities & Defects TF will begin experiments and test methods based on responses to a survey aimed at identifying 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 will be meeting in conjunction with the Strategies in Light conference (February 12-14, 2013) in Santa Clara, California.

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 for equipment suppliers, raw material suppliers, module makers and other involved parties.