Akinori Hongu

A Practical Method for Quantifying Eco‐Efficiency Using Eco‐Design Support Tools

Eco‐efficiency at the product level is defined as product value per unit of environmental impact. In this paper we present a method for quantifying the eco‐efficiency using quality function deployment (QFD) and life‐cycle impact assessment (LCIA). These well‐known tools are widely used in the manufacturing industry. QFD, which is one of the methods used in product development based on consumer preferences, is introduced to calculate the product value. An index of the product value is calculated as the weighted average of improvement rates of quality characteristics. The importance of customer requirements, derived from the QFD matrix, is applied. Environmental impacts throughout a product life cycle are calculated based on an LCIA method widely used in Japan. By applying the LCIA method of endpoint type, the endpoint damage caused by various life‐cycle inventories is calculated. Willingness to pay is applied to integrate it into a single index. Eco‐design support tools, namely, the life‐cycle planning (LCP) tool and the life‐cycle assessment (LCA) tool, have already been developed. Using these tools, data required for calculation of the eco‐efficiency of products can be collected. The product value is calculated based on QFD data stored in the LCP tool and the environmental impact is calculated using the LCA tool. Case studies of eco‐efficiency are adopted and the adequacy of this method is clarified. Several advantages of this method are characterized.

Mechanism of amine additive in chemically amplified resist visualized by using Monte Carlo simulation

A novel simulator using the Monte-Carlo method, which simulates molecular-like movements and reactions in chemically amplified resist systems, has been developed in order to clarify the mechanism of amine additive. The simulation program simulates diffusion phenomena with random-walked acids and amine molecules, and reactions of deactivation (neutralization) and inhibitor cleavage in every movement of the molecules. It was found that the amine in the exposed area was rapidly deactivated, and the concentration profile of the remaining amine was rapidly changed to an inversely shaped profile of that of the acid. This means that the remaining amine prevents diffusion of acids outside the exposed area by functioning as a barrier during almost the whole period of post-exposure bake (PEB). These concentration profiles lead to an enhancement of stability of pattern sizes and reduction of edge roughness of the pattern. Environmental stability was also calculated, and amine additive was also found to prevent contamination from the environment in the initial period of the PEB.

A fine pitch COG technique for a TFT-LCD panel using an indium alloy

A fine pitch chip-on-glass (COG) bonding technique for liquid crystal display (LCD) panels has been developed. An IC chip with gold bumps was dipped in a stirred indium alloy bath in a nitrogen atmosphere without flux. Shallow-bowl-shaped In alloy bumps were selectively formed on the Au bumps on the IC electrodes. The minimum bump pitch was 50 /spl mu/m, and the bump size was 31 by 31 /spl mu/m. The In alloy bumps whose minimum pitch was 100 /spl mu/m were connected to molybdenum conductors without flux at low pressure (30 gf/bump or less) and low temperature (110/spl deg/C or less). The temperature was lower than the alloy melting point. The mean contact resistance was 0.78 /spl Omega/. It was found that the calculation of the minimum bump pitch for the bump sizes and the In alloy bump height is useful for designing new ICs with fine pitch bumps. It has been demonstrated through a thermal shock test (TST), a high temperature and high-humidity storage test; and a high-temperature storage test that the contact resistance changes satisfied the specification. Prototype TFT-LCD panels with 80-/spl mu/m pitch driver ICs were successfully developed. >

A framework of eco-design support

Although there are several methods and tools to support environmentally-conscious design (eco-design) from various viewpoints, the images of integrated design support systems are few. In this paper, a framework of an eco-design support is proposed to make an integrated system image clear, as follows: (1) requirements of eco-design support are clarified; (2) environmental targets are derived; (3) a configuration of an eco-design support system which consists of tools is described; and (4) relations between tools and design processes are described. In addition, the recyclability evaluation tool which is newly implemented in the system is described.

Chemically ampilified ArF excimer laser resists using the absorption band shift method

The VUV-absorption spectrum of aromatic compounds can be red-shifted toward longer wavelengths to make the window of absorption align with 193 nm by extending the conjugation length of the double bonds. Based on this observation, the new concept of absorption band shifting is proposed as a way to increase the transparency of resist components for 193 nm ArF excimer laser exposure. A chemically amplified single-layer ArF excimer laser resist consisting of naphthalene-containing photoacid generator, a dissolution inhibitor, and base polymer has been newly developed. Using this resist, a 0.17 micrometers line/space pattern with a vertical resist profile was resolved by a prototype 0.55 NA projection lens for ArF excimer laser exposure, and a resolution limit of 0.16 micrometers was achieved.

A new face down bonding technique using a low melting point metal

The authors have developed a face-down bonding technique for use in making an LCD (liquid-crystal-display) panel. The maximum bonding temperature is limited by the heat resistance temperature for the liquid-crystal materials and polarizer plates. The bonding temperature is approximately 150 degrees C. Using a low-melting-point metal, such as the indium alloy, the IC electrodes and bonding pads on a glass substrate can be connected at a temperature less than 150 degrees C. This technique is called the low-melting-point-metal connection (LMC) technique. Shallow-bowl-shaped bumps of low-melting-point metal, 10-20- mu high, were formed on the IC bonding pads by dipping, and the IC and the glass substrate were connected. This process was carried out at a pressure of 30 gf/bump or less and at a temperature of 150 degrees C or less. Two kinds of reliability tests were then carried out. One was a thermal shock test, and the other was a high-temperature, high-humidity test (70 degrees C, 90% R.H., 500 h). Stable results were obtained for both tests. Dot-matrix LCD panels with 640*400 dots were assembled using 20 driver IC chips and were shown to work well.<<ETX>>