Challenges in DMD TM Assembly and Test
- PDF / 1,412,739 Bytes
- 12 Pages / 612 x 792 pts (letter) Page_size
- 88 Downloads / 199 Views
Challenges in DMD™ Assembly and Test S. Joshua Jacobs, Joshua J. Malone, Seth A. Miller, Armando Gonzalez, Roger Robbins, Vincent C. Lopes, Dennis Doane Digital Imaging Texas Instruments 13536 N. Central Expressway MS 914 Dallas, TX 75243 Abstract The Digital Micromirror DeviceTM (DMDTM) developed at Texas Instruments is a spatial light modulator composed of 500,000 to 1.3 million movable micromachined aluminum mirrors. The DMDTM serves as the engine for the current generation of computer-driven slide and video projectors, and for next generation devices in digital television and movie projectors. The unique architecture and applications of the device present several packaging and test challenges. This paper provides a description of package humidity modeling and verification testing, as well as an overview of the automated optical testing and test equipment that have been developed to support manufacturing of the DMD™. Introduction The Digital Micromirror Device™ (DMDTM) is a spatial light modulator (SLM) whose primary market is business class and large venue projection systems. It consists of an array of 500,000 to 1.3 million micromachined aluminum mirrors fabricated above CMOS circuitry. Each mirror can be individually addressed by an applied voltage and temporarily driven in either of two directions. Light illuminating the resulting pattern of landed mirrors is reflected through a lens, and will appear on a screen as an image, with each mirror representing an individual pixel. The technology currently commands 40% of the projection market, and competes with liquid-crystal based SLMs made by a variety of manufacturers. The total projection market is expected to grow to $8 billion by the year 2003[1]. A simplified sketch of a DMDTM pixel is shown in Figure 1. The flat aluminum mirror is suspended above the silicon substrate by a flexible hinge. Application of a voltage between the mirror and substrate attracts the mirror to the surface, and at a critical threshold field the mirror will land.
Figure 1. Illustration of DMD™ Pixel.
Figure 2. SEM of DMD™ mirrors.
The mirror can be landed in two positions, defined as on and off, and as a result gives digital output. In the on state, the mirror is tilted at +10o relative to neutral; in the off state, at –10o. A 3x3 array of actual mirrors is shown in Figure 2. In this picture, each mirror is 17µm by 17 µm, though other pixel sizes are possible. Each mirror in this figure is shown in a landed position. The via in the center
EE6.1.1
of the mirror is a necessary part of the fabrication process, as it connects the mirror to the yoked hinge below it. The minimum cycle time of these mirrors is approximately 20 µs, compared to switching speeds of 30 ms for liquid crystal SLMs. The brightness of a video image can be adjusted by tuning the amount of time a given pixel is on or off during a video frame, which is 15-30 ms. Full color can be achieved from a single chip by inserting a rotating color wheel with red, green, and blue filters. Three distinct images can be broadca
Data Loading...
