Inventor’s corner

Monitoring molecular contamination of critical surfaces using coated SAWS

Many manufacturing processes and technologies are susceptible to airborne or gas-phase molecular contaminants (AMC), and to the related surface molecular contamination (SMC) resulting from chemical interactions between AMC and critical surfaces (or subject surfaces). Detrimental effects of SMC include changes in the chemical, electrical, and optical qualities of critical surfaces, which can decrease product performance and reliability, and raise product cost.

This invention is for monitoring molecular contamination on a subject surface susceptible to degradation by a molecular contaminant. The monitor includes a surface acoustic wave (SAW) device having a SAW measurement surface coated with a material that is equivalent to the subject material with respect to spontaneous contamination. Preferably, the coating (e.g., photoresist, copper, silver, gold) comprises the same material as the subject surface or a material that interacts chemically with the contaminant in an equivalent manner.

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The figure shows an example equivalent surface SAW apparatus (A), which comprises a substrate (B) having a measurement surface (C), with a first pair (D) of interdigital transducers (E, F) disposed on a first area (G) of the surface. A second pair (H) of interdigital transducers (I, J) is disposed on a second area (K) of the surface. A first contact pad (L) connects to a transducer of the first pair and to a first connection line (M). Similarly, a second contact pad (N) connects to a transducer of the first pair and to a second connection line (O). A third contact pad (P) connects to a transducer of the second transducer pair and to a third connection line (Q). A fourth contact pad (R) connects to a transducer of the second transducer pair and to a fourth connection line (S). A coating or thin film (T)-less than a micron in thickness-is disposed on the surface over an area in which surface acoustic waves propagate in response to electric signals input to one or more of the first transducer pair and the second transducer pair. The film changes the acoustic wave propagation velocity as compared to a substrate without a coating on its surface.

The SAW device provides real-time observations of the impact of AMC on surfaces using a more direct approach than air sample monitoring, and a mass sensitivity more than 100 times greater than existing quartz crystal microbalance (QCM) technologies. In this way, many sources of error are eliminated including: estimation of species-specific sticking coefficients, sticking coefficient variations due to temperature and humidity changes, and synergistic chemical interactions on the target surface.
Patent number: 6,945,090
Date granted: September 20, 2005
Inventor: Daniel Rodier (Louisville, Colo.)

Irradiation method for liquid crystal display (LCD) devices

Liquid crystal display (LCD) devices are basically configured from a pair of substrates with a liquid crystal layer disposed between them to constitute what is called a “liquid crystal panel” structure, wherein at least one of the substrates is made of a transparent material such as glass. As substrate sizes increase, it is more difficult to control liquid crystal orientation, which is important for displaying high-quality images with increased reliability.

Current orientation methods, including rubbing techniques, can introduce harmful contaminants such as static electricity, particulates, or scarring, and are inefficient for larger substrates. This invention provides a polarized light irradiation method for efficiently performing optical orientation in large area regions (diagonally measuring 10 inches or greater), as well as a polarized light irradiation apparatus for use in adding liquid crystal orientation controllability to an orientation film of liquid crystal display elements to achieve both wide visual field angles and a display uniformity with less display irregularities.

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This diagram shows the polarized light irradiation method in accordance with this invention, along with an optical system for use in practical implementation of this methodology. Light output from the light source (A) is guided through the attenuator (B), relay optical system (C), homogenizer (D) and fourth mirror (E) in this order, so that the optical intensity is equalized; the resulting light arrives at the slit (F). The light passing through the slit is reshaped in cross-section or profile into a corresponding rectangular beam pattern for introduction to the image-formation lens system (G). The output light is also converted to have a rectangular beam pattern, which is then incident upon the polarized light separator (H), which is comprised of a quartz plate and multiple films formed thereon, wherein its axis of optical polarization is formed on a surface that lies parallel to the optical polarizing axis AXp of P-waves of the incident light beam (i.e., the light of beam pattern [I] leaving the image-formation lens system). The separator is supported in such a manner as to be held by the holder (J) in a state in which it is tilted at the Brewster angle Θ relative to the optical axis of the incident light beam. Accordingly, the resultant light beam that has passed through the polarized light separator to reach the light irradiation plane (K) is only the P-wave component having the optical polarization axis AXp. The irradiation plane is supported on a scanning stage (L) which is movable in two-dimensional space perpendicular to the optical axis of the irradiation light. Letting the scan stage move in the direction of the arrows (M, N) makes it possible to two-dimensionally irradiate the irradiation plane in a region that is wider than the size of the light beam pattern.
Patent number: 6,924,860
Date granted: August 2, 2005
Inventors: Masahito Ohe, Shigeru Matsuyama, Kenkichi Suzuki, Masaaki Matsuda (Mobara, Japan)


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