LEDmanufacturing technology
Comprehensive inspection techniques can underpin high-yield LED manufacturing
A hike in LED manufacturing yields can ensure profitable production of lower cost chips and spur the growth of solid-state lighting.One way for fabs to produce more die that are in-spec is to introduce inspection tools for various steps of the process, alongside software that collates all the data and pin points process issues, says KLA-Tencor’s Director of Product Marketing, John Robinson.
T
he LED industry is not standing still. Leading manufacturers are upgrading production to 6- inch wafers and turning to LED architectures that are significantly more sophisticated – two trends that increase the cost invested at the die and wafer level. Where these chips are going is also shifting, with more and more of them being deployed in automobile headlights, LED TVs, personal electronics and architectural lighting. The emergence of the incredibly lucrative solid-state LED lighting market is also underway, which should enable widespread replacement of conventional incandescent lighting with energy efficient, mercury- free, alternatives.
This evolution of the LED industry has impacted the approach taken to inspect the product during its manufacture. In the past, manufacturers had minimal incentive to deploy in-line yield-improvement strategies because the cost-per-device was low, and the applications for these LEDs were far less demanding on chip performance. Back then, a “test- and-sort” methodology involving selection of good devices at the final production stage could satisfy customer requirements.
Today it’s very different. Not only are customers demanding far higher, tighter specs – the price of the LED has also plummeted, and chipmakers must hit higher yields to ensure profitability. Consequently, most leading manufacturers are turning to comprehensive yield management methods to better serve the needs of their markets while retaining cost
July 2011
www.compoundsemiconductor.net 33
competitiveness. At KLA-Tencor, a US-based manufacturer of inspection tools for the semiconductor industry, we are firm believers in the benefits of a holistic approach to LED yield management strategy. Ideally this should include: in- line automated inspection at key points throughout the production process; fast detection of process excursions; timely root cause identification through Defect Source Analysis; use of advanced Spatial Signature Analysis; and a comprehensive universal software system for aggregating, analysing and utilizing information to minimize propagation of production errors and drive timely corrective actions.
Tremendous opportunities Two key targets set out in the US Department of Energy’s roadmap for solid-state lighting are a doubling of LED efficiency and a halving of its price per lumen over the 2009-2015 timeframe (see Figure
Figure 1: In-line
inspection and yield
management will cut the cost and improve the performance of LED
manufacturing
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104