Canon global

Manufacturing High-Precision Mirrors with the World's Largest Diameter^*1

Canon's LCD lithography equipment employs a mirror-scanning method that makes use of a mirror-based projection optical system. The system offers such merits as a simple configuration facilitating increases in substrate size, a wide exposure field, no chromatic aberration, which can occur with lenses, and no image performance degradation.
Pattern exposure processes for LCD panels are carried out with a precision of several μm.^*2 The projection mirror used in the system also requires high precision. Large concave mirrors in particular, with a large diameter to realize an exposure width capable of exposing large panels seamlessly in a single pass, enable significant increases in productivity.
By making use of extremely high-precision processing technologies, Canon has succeeded in developing the world's largest diameter concave mirror, a 1,514 mm 8th-generation^*3 ultra-high precision concave mirror with a surface processing accuracy of 0.015 μm. The mirror makes possible a resolving power of 3 μm across the entire exposure field.

Large-Diameter High-Precision Concave Mirror (1,514 mm diameter)

• *1 World's largest diameter
  Among semiconductorexposure equipment and mirror projection aligners as of October 2010
• *2 Micrometer (μm) : 1 μm = one millionth of a meter.
• *3 8th-generation
  Ongoing changes in the size of glass substrates are represented as "generations." The larger the substrate, the better suited it is for producing large panels. Productivity also increases as a single substrate yields multiple panels, so the number of generations has risen rapidly. At present, the 8th-generation is being mass produced, but development is already being conducted with an eye to the next generation.

Exposing Large Scale Substrates at a Speed of 750 mm per Second

Canon's latest LCD lithography equipment measures 9 m (W) x 11.6 m (D) x 5.8 m (H). The main body of the unit weighs 100 tons, with the moving mask stage weighing 1 ton and the substrate stage weighing 4 tons, making the aligner Canon's largest product.
As the size of LCD substrates increases, the weight of the moveable parts has also increased. Because increased weight tends to impair the performance of the stages, Canon selects materials with a low specific gravity and strong rigidity in order to develop ultra-large stages that reduce overall weight while maintaining component strength.
The substrate stage and mask stage are each maintained by air bearings and are driven by non-contact linear motors. The comparatively light mask stage follows the comparatively heavy substrate stage for completely synchronized "master slave control." The drive performance of the substrate stage realizes an extremely high level of precision, achieving a speed of 750 mm per second in just 0.5 seconds upon moving, and comes to a complete stop in a mere 0.2 seconds upon arriving at the stop position. Both stages utilize positional measuring technology using a laser interferometer to control position and speed.
The high-performance and high-speed operation of the ultra-large stage allows it to attain a high throughput of 323 panels per hour for 55-inch wide panels.

LCD Lithography Equipment for Eighth-Generation Glass Substrate Sizes

Supporting the Film Deposition Process for Large Panels

Vacuum deposition^*4 technology, used in the wiring process during LCD panel production, forms a thin film in a vacuum using the "sputter deposition"^*5 method. This is a film deposition method that uses the "sputtering phenomenon" to form a thin film of metal, such as the aluminum and molybdenum used in transistor circuit wiring, on glass substrates.
Since its founding, Canon ANELVA has developed original ultra-high vacuum technologies and produced film deposition equipment for semiconductors, storage devices, and panel devices. Canon ANELVA developed the ANELVA System, a vertical transfer system for substrates during the manufacture of LCD panels, which accommodates upgrades in glass substrate generations while solving such problems as substrate bowing, which would occur in conventional horizontally-oriented transfer systems, and equipment installation space. Further, Canon ANELVA also developed the "rectangular split cathode," a unique cathode configuration for sputtering that can expose two substrates at once by consecutive deposition of three types of film material (targets) in the same vacuum chamber. The deposited film delivers uniformly superior quality and also improves the usage rate of the target.
The equipment reduces panel costs while increasing productivity within the rapidly growing LCD panel-production sector.

Sputtering Equipment for LCDs (DL3100 Series)

• *4 Vacuum deposition
  Thin films (thickness of 1 μm or less) are commonly formed on a physical surface by either electroplating or vacuum deposition. Vacuum deposition, which takes place in a vacuum, facilitates the controlling of the film's thickness during formation. Methods of vacuum deposition include "vacuum evaporation," in which the film material is heated and evaporated; "CVD," which makes use of a chemical reaction with a gaseous film material; and "sputter," which uses physical reactions.
• *5 Sputter deposition
  When voltage is applied to a glass substrate and film material (target) within a vacuum containing argon or other inert gas, the gas becomes ionized (Ar+) and collides with the target at high speed, causing the atoms and molecules composing the target to be ejected (the sputtering phenomenon). The sputtered atoms and molecules adhere to the surface of the substrate in a thin layer.