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SEMI releases 11 tech standards for FPD, MEMS

Posted: 20 Feb 2007 ?? ?Print Version ?Bookmark and Share

Keywords:SEMI? FPD? MEMS? flat panel display?

SEMI has published 11 technical standards for the semiconductor, flat-panel display (FPD) and MEMS manufacturing industries. The new standards include a guide for equipment data acquisition, a test method for evaluation of line-edge roughness and linewidth roughness, and a communications specification for the MECHATROLINK protocol.

"The new SEMI standards documents will help provide the industry with solutions for critical challenges in factory automation, substrates, and metrics for manufacturing efficiency," said Bettina Weiss, SEMI director of International Standards.

Technical experts from equipment suppliers, device manufacturers and other companies participating in the SEMI International Standards Program developed the standards.

New standards
One of the new standards is D47 that standardizes the method to measure electrical and optical characteristics of bent cold cathode fluorescent lamps (CCFLs) for FPD back light units. The standard can also be used for general measurement of CCFLs, such as primary performance, post-test reliability and shipping/incoming inspection of single CCFLs.

The next standard is D48 that defines the datum line required to clarify the reading position of 2D-ID, based on characteristics of feature sizes of the current substrates and substrate ID. By defining the datum lines, both equipment suppliers and FPD makers benefit because they can use common datum lines as references for positioning 2D-ID readers. Moreover, standardization of the ID reading position improves the reading accuracy, a key element for traceability.

The E54.19 standard defines a communication specification based on the Mechatrolink protocol to enable high-speed communications between intelligent devices on a sensor/actuator network (SAN) that operates according to SEMI E54 device models on semiconductor manufacturing equipment. All Mechatrolink slave devices can be connected to this network. A master controller can connect up to 30 slave nodes. Thus, if the system configuration is changed, slave devices can easily be added or removed to obtain a new system configuration. Examples of master controllers are PLCs, motion controllers, and board controllers. Examples of slave controllers are servo drives, steppers, inverters, IOs and temperature controllers.

E147 serves as a guide for equipment data acquisition (EDA). It is an umbrella document covering all five standards required to implement the EDA interface. The guide describes the interactions between SEMI standards E120 and E125, E138 and E132, and between E125 and E134, for example. The guide explains the movement of data collection from being a complex and single-wire solution into a simpler and flexible multi-client data collection mechanism. It also highlights the benefits of the EDA standards suite to address data collection limitations found in the SECSII protocol.

F103 specifies the size range of stainless steel canisters containing liquid chemicals and precursors used in the CVD process. By specifying the maximum outer diameter, maximum height and nominal volume, the canister size is fixed, resulting in more efficient use of storage space. This is to allow users to reduce the cost of chemical cabinets and reduce the number of canisters used.

The G81.1 standard describes the concept of map data characteristics of devices fabricated on a substrate. It provides the base concept of the characteristics regardless of time-dependent variations. This approach keeps track of mapping information to reduce misunderstanding among implementations and lower the costs for interchanging map information.

Three out of the 11 standards that SEMI released are preliminary documentsM68, M69 and M70.

M68 documents the practice for determining wafer near-edge geometry from a measured height data array using a curvature metric, ZDD. It uses existing industry-standard measurement equipment to provide near-edge metrics. Once adopted, this standard allows the wafer manufacturer to simplify and standardize internal and external procedures related to advanced wafer geometry specifications.

M69 specifies the practice for determining wafer near-edge geometry using roll-off amount (ROA) as a proposed metric. The ROA metric is suitable for quantifying near-edge geometry of wafers used in semiconductor device processing. The variation of ROA increases the thickness variation of films remaining in near-edge after the CMP process. Unless the thickness of remaining films is controlled within the allowable variation, pattern failures in the near-edge region may occur. Thus, the measurement and control of ROA can improve CMP performance and contribute to cost savings.

The third preliminary standard, M70, provides the practice for determining wafer-near-edge geometry using partial wafer site flatness to achieve higher yield. The standard requires no new measurement systems or metrics and instead adopts existing parameters and equipment.

Touted to aid the development of a Young's modulus standard for MEMS, the MS2 standard documents a test method for step-height measurements and applies to thin films such as those found in MEMS materials. Step-height test structures include a series of steps created by the presence or absence of different process layers, such as polysilicon and aluminum. The steps are surrounded on at least three sides by a reference platform used for leveling. The height difference between two platforms leads to the thickness measurements of the process layers, which can aid the design and fabrication of MEMS devices and to obtain thin-film material parameters.

The P47 standard specifies the test method for the evaluation of line-edge roughness (LER) and linewidth roughness. The standard accelerates the investigation of LER by resist and process tool vendors, resulting in LER reduction, which in turn improves production yield. The methodology defined in the standard applies to pattern inspection in various types of small pattern fabrications.

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