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In this study, 2^4 full factorial design of experiment was applied to an FEM model, which gives pattern dependant contact pressure distribution, to build a qualitative model of pad effects on within die non-uniformity (WIDNU) in CMP. Analysis of variance showed that every single effect and two-way interaction effects of hard layer stiffness and soft layer stiffness are significant compared to the round-off error from mesh change. Various regression models were built and residual analyses were done for each of them. Best model with best normality of residuals includes only the effect of hard layer stiffness, soft layer stiffness and hard layer thickness. Based on this model, basic qualitative design rule for a stacked CMP pad to minimize WIDNU were suggested.

Local material removal rate is inversely proportional to the local pattern density in ILDCMP. With the assumption that the local velocity and Preston coefficient are constant across a die, local MRR non-uniformity is attributed to the local pressure non-uniformity. Pressure distributions on two different test patterns consisting of five different pattern density sections were calculated with a finite element model. These pressure distributions were compared with semi-empirical pattern dependant oxide CMP model with three different weighting functions. Results showed that pressure distribution can be well approximated with the pattern density dependant oxide CMP model.

It has been recognized that on ductile materials, high radial tool engagement conditions produce the largest burrs in face milling operations. Ideally, high radial engagement is avoided by configuring the tool path such that the mill is kept within the feasible offset region –a region that satisfies user requirements– of a given workpiece geometry and material. Fulfillment of this condition, however, is often difficult due to geometrical complexity of the manufactured components and cycle time constraints. For this reason there is great motivation to minimize burr formation at high tool engagement. In this paper, the mechanisms of burr formation and the effect of cutting parameters under high radial engagement are investigated, and possible burr minimization strategies are discussed. To this end, face milling tests results conducted by CODEF members and other researchers on different materials were examined. The proposed minimization strategies focus on the optimization of the following parameters: depth of cut, insert nose sharpness, lead angle, and axial rake angle, to promote a transition from primary to secondary burr formation.

There are many elements affecting CMP performance such as slurry, pad, process parameters and pad conditioning. Among these, the pad is considered as one of the most important parts because of its deterioration during polishing. However, a special purpose pad design has not been tried yet. In this paper, a fabrication process and prototype are detailed using micro molding technology. These are applied to pad design optimization pressure.

For an optimization of a drilling process to minimize burr formation, control chart or empirical model from design of experiment can be used. However, direct measurement of inter-layer burr is limited experimentally in the case of drilling through a multi-layered material, which is a common process in aerospace industry. A finite element model that can quantitatively predict the inter-layer burr formation from workpiece material properties and process conditions would significantly reduce the cost and time for building an empirical model. In this study, a finite element model using material properties of stainless steel 304L from previous work was applied to simulated burr formation process during drilling of a multi-layered material. Simulation showed inter-layer burr formation along with entrance burr formation. A quantitative prediction scheme of burr size using node displacement tracking for burr thickness and height was presented.

Micro-end-milling is emerging as an important fabrication process. Its benefits include the ability to fabricate micro and meso-scale parts out of a greater range of materials and with more varied geometry than is possible with lithography and etching. It also enables the creation of micro and meso-scale molds for injection molding. Factors affecting surface roughness have not been studied in depth for this process. A series of experiments has been conducted in order to begin to characterize the factors affecting surface roughness and determine the range of attainable surface roughness values for the micro-end-milling process. A 229 ?m diameter end mill was used to cut slots into aluminum (6061) samples. The machining factors studied were chip load (feed per tooth), cutting speed, and depth of cut. A two level factorial experiment was run, and it was determined that while chip load was the dominating factor, the interaction between chip load and cutting speed was also significant. Further experiments allowed the generation of a second order relationship between chip load and surface roughness. The model, which includes the effect of chip load, cutting speed, and the interaction between the two, predicted the surface roughness values with an accuracy of about +/- 10%. The surface roughness values ranged from 600 Å all the way to 3800 Å over the span of the studied parameters.It has previously been shown that run-out creates a greater problem for the dimensional accuracy of parts created by a micro-end-milling process as compared to parts created by a traditional end-milling process (Lee, et al 2001). It appears that run-out also has a more significant effect on the surface quality of micro-end milled parts. The surface roughness traces reveal large peak to valley variations with a period of twice the chip load. This means that one of the two cutting edges on the tool creates a deeper cut than the other. Cutting marks from the non-dominant cutting edge are also visible on the surface roughness traces as small steps between the much larger marks from the dominant cutting edge. It is postulated that the effect is due to run-out, and that improving machine tool run-out will have a very significant effect on the surface quality of micro-end-milled features.

Back cutting is a special condition that occurs when there is tool run-out, uneven tool wear on the inserts or machining over the same region in opposite directions in two different passes. As the tool progresses along a tool path the instabilities mentioned might cause the back half of the cutter to machine the workpiece. This condition is commonly referred to as back cutting. The most common way of observing the presence of back cutting is the reversal in the direction of tool marks. A series of experiments were performed to gauge the actual effect on process performance due to back cutting. The results surprisingly showed that back cutting does not have a serious impact on the burr formation. Pictures of burrs under an optical microscope shows that back cutting do not create burrs but merely machines over the burrs created from forward cutting. Experiments performed with different back cutting depths produced identical results.The study also revealed that the tool wear which causes nose rounding is the more significant cause of burrs not explained by prediction theories. Two different strategies, tool geometry based and tool path based are proposed to avoid kinematic conditions that promote burr formation with worn tools. The results from these strategies are presented at the end of this paper.

Removal of burrs at cross-drilled hole intersections is often tedious and expensive due to limited accessibility. Automated edge finishing of crossholes has been practiced successfully using robot-assisted, flexible abrasive brush deburring, and non-traditional, mass finishing methods such as electrochemical deburring (ECD), abrasive slurry, and thermal deburring. These methods are very efficient but most require specialized equipment and dedicated cleaning operations to remove chemicals or trapped brush bristles. The Orbitool is an on-line, localized deburring alternative to brushes recently developed by JWDone Company. The Orbitool is a mechanized cutting tool with carbide edges specifically designed for crosshole deburring. Mechanized cutting provides greater selectivity and control of dimensional specifications compared to brushing and mass finishing methods. Furthermore, it can be implemented using existing machine tool equipment and cleaning procedures. As with any deburring tool, its desired capability is burr removal in the shortest time possible while meeting dimensional and surface quality requirements. To this end, process maps of chamfer width and surface roughness of the deburred edges, plotted against process parameters, were developed in this study. Workpieces consisted of Al 6061 T6 bars with zero-offset, perpendicular cross-holes with a diameter of 7.94 mm (5/16 in.). The experiments were conducted using Orbitools with a diameter of 6.35 mm (1/4 in.) and 36 cutting edges. The effect of the process inputs and their mutual interaction was assessed using Taguchi methods. The results show that proper selection of process parameters yield consistent and effective removal of burrs at cross-drilled intersections while achieving surface roughness values that range from 15 to 65 ?m at the chamfers.

Machining dry, without any coolant can be advantageous because of decreased costs associated with the use of coolant and a decrease in possible negative effects on worker health and the environment. Many problems associated with dry machining occur because of elevated temperatures. Because of increased ductility at elevated temperatures, the burrs formed are larger.

The surface and edge quality of single crystal and polycrystalline copper workpieces has been observed to vary significantly as a function of crystallographic orientation. At the precision scale, the chip formation process is influenced by the microstructure of the material, such as grain boundaries and grain orientation in polycrystalline materials, and crystallographic orientation in single-crystal materials. Such variation in the microstructure has a significant effect on the resulting surface, edge, and burr topography.

Polishing technology has been broadly used in manufacturing of components to enhance the surface quality at final processing stage. On the threshold for the 21th century, all of technologies are changing more rapidly than the past. One of them is the miniaturization of the smart systems that require new technological approaches in manufacturing processes. Scientists and engineers have some responsibilities to revise the terminology and expand the area of each technology from the conventional one to nanoengineering. This paper focuses on the introduction of new technological approaches in nanopolishing for microstructures that imply new additional concepts on the conventional polishing. New concepts include damage-free, planarization, nanotopography and conformalization. Damage-free means to get not only atomic level surface roughness, but also subsurface without any physical defects. As one of the emerging methods, chemical mechanical polishing (CMP) is introduced with chemical reaction on the conventional mechanical polishing. Planarization is one of the fabrication processes for semiconductor devices, to make flat from the bumpy or rugged pattern surfaces for rearrangement of ULSI below quarter microns. Representative applications are reported with IMD, STI, copper and low-k CMP. Nanotopography means nanofeatures having 0.2~20mm wave length covered between nanoroughness (10-100nm) and flatness. It influences on the deterioration of threshold voltage, dielectric breakdown and failure of CMP of thin blanket film. Final issue is pointed to the conformalization which means isotropic removal of microstructures to improve the roughness while maintaining the micro three dimensional forms. Electrorheological and magnetorheologi- cal fluid (ERF or MRF) assisted polishing techniques are summarized with their material removal mechanisms and some results.

The Exit Order Sequence (EOS) theory discussed by previous LMA students predicts the size of burrs formed during face milling. Other influences are tool geometry, coolant use, and material properties in aluminum silicon alloys and cast iron. Used, worn tools also increase the size of the burr. The effect of speed and feed are also discussed, particularly with regards to cast iron.

Semiconductor manufacturing and process design is driven to change rapidly by technology demands and competition. Incorporating environmental considerations into this process requires decision tools which will generate environmental analyses in as short a turn-around as possible. The predictive capability of QSAR methods are investigated and U.S. government QSAR software tools are surveyed for their applicability to environmental decision analysis in semiconductor equipment design.

High speed machining is pushing the limits of feeds and speeds. A different approach for high throughput is described here. The focus is on the maximum feed that can be obtained for a segment; the feed rate losses due to sharp changes in tool path are minimized. The interdependency of individual axis drive speeds for a tool path segment are analyzed. There exists an optimum work angle relative to the axes that reduces losses and increases allowable feeds for particular segments, saving valuable cycle time and balancing feed drive loads. Face milling and roughing steps of end milling are the most attractive application areas.

This paper presents an investigation on micro-burr formation in machining. Micro cutting is compared with conventional cutting in terms of cutting process characteristics and cutting conditions. An acceptable range of cutting conditions for micro cutting has been determined by extrapolating the conditions for conventional cutting and experimental verification. With cutting conditions determined, a series of experiments was conducted to investigate burr formation and tool life. Herein, tool life is defined as the number of holes created before a catastrophic increase in burr height occurs. Based on experimental results, contour charts for predicting burr formation as well as tool life are developed to minimize burr formation and to improve tool life.

In order to address new concerns in the CMP process, a new-concept pad with a composite structure and controlled geometries is proposed.

Factories of the digital future would require simulation and optimization of processes and process chains before establishing the actual line using very specific procedures. There is tremendous scope for reducing significantly the lead time for production and costs by employing planning tools for virtual machining. P4 is designed to address challenges faced by automobile industries to integrate developments in technology based software and pave way for defect free process plans. P4 presents a novel way to plan each process as an independent entity that exists as part of a sequence. Face milling is used as an example in this report to demonstrate the various concepts that form the core of P4.

In this report, the with-in wafer non-uniformity (WIWNU) of material removal rate and its optimization are discussed from both the machine side and consumable side. At the machine side, the pressure and velocity distribution are the major reasons for the non-uniform material removal rate across the wafer. The velocity distributions for the rotational type and linear type of machines are analyzed systematically. The rotational part of the velocity is the contributor of the velocity non-uniformity. The pressure non-uniformity in both cases of the solid-solid contact and the solid-fluid-solid contact are discussed. Adding the retaining ring is an effective way to reduce the pressure non-uniformity at the edge of the wafer in the solid-solid contact mode. In the solid-fluid-solid contact mode, the friction coefficient is identified as the major contributor to the non-uniformity. A process window of pressure and velocity in terms of small non-uniformity can be obtained by combining the model proposed in this report and the Stribeck curve of the friction coefficients. At the consumable side, a systematic method is proposed to optimize the WIWNU in solid-solid contact mode, based on the material removal model developed in previous works [5, 6, 7]. The basic idea is to reduce the sensitivity of the material removal on pressure and velocity distribution.

With increases in the use of multi-layered materials in the aerospace industry to reduce weight while still meeting strength requirements, the study of inter-layer burr formation in drilling of a multi-layered material becomes more important. Inter-layer gap formation due to material bending by drilling thrust force has significant effect on inter-layer burr formation. A finite element model for inter-layer gap formation in a multi-layered material was proposed. A gap formation was initiated by initial difference in elastic bending of layers and developed by plastic deformation of the first layer.

Modeling and simulation are critical to transfer CMP from an engineering 'art' to an engineering 'science'. Research efforts in CMP modeling have been attempted in the last decade. There is an urgent need to review the current models including their limitations and future research directions systematically. In this paper, chemical mechanical planarization modeling is reviewed systematically, from particle scale to die and wafer scales.

There are many elements affecting CMP performance such as slurry, pad, process parameters and pad conditioning. Among these elements, the pad is considered one of the most important because of its deterioration during polishing. A special purpose pad design, however, has not been tried yet. In this paper, a fabrication process and prototype are detailed using micro molding technology. These are applied to pad design optimization.

Heating, ventilation, and air conditioning (HVAC) systems used in the clean room environment of biotechnology and drug development and manufacturing, are extremely energy and water intensive and represent a significant operating cost for these facilities [1]. HVAC systems are also the primary source of environmental emissions for the majority of companies operating within the biotechnology and drugs sector. While the processes used in drug manufacture have negligible environmental impact, the power plants, and water treatment facilities which annually provide the billions of kilowatt hours (kWh) of required electricity and hundreds of billions of gallons of make up water [5], also produce tons of CO2, CO, VOC, PM10, SO2, NOX, and in some cases Hg [3]. These issues of water and air emissions, key concerns of the California Department of Toxic Substance Control (DTSC) and the Environmental Protection Agency (EPA), are increasingly shared by the CEOs of leading pharmaceutical and biological products companies, and are appearing in their annual Environmental Health and Safety (EHS) reporting [4] with greater frequency and detail. The HVAC system used in the clean room manufacturing environment has been modeled with a functional unit of $/CFM. Economic and environmental impacts as a function of specified performance criteria have been captured, allowing for cost of ownership assessment of both existing and future systems of varying configurations serving a variety of clean room conditions. The opportunities for increased efficiency and cost savings of HVAC systems used in clean rooms are considerable, as much as 50% [5]. The HVAC model developed may lead to these savings through estimated results, which are considerably accurate, within 25% of several industry and government organized case study results [6]. The following report details a discussion of the HVAC system model, the methodology behind its development, its capabilities, and limitations.

The surface quality obtained in diamond turning operations Is highly influenced by the interaction between the tool and workpiece. These influences include changes in cutting forces, chip formation phenomena, microstructure of workpiece, and others. Local changes in the depth of cut and material properties lead to variable cutting forces that may result in unacceptable form errors. This research proposes an innovative approach for mapping the AE RMS generated during diamond turning able to graphically represent several features of the interaction between tool and workpiece related to instant depth of cut distribution, grain boundaries, and grain orientation.

In order to keep pace with tight designs for MEMS, CMP has started to be adopted. In this report, some MEMS devices fabricated with CMP are shown, and some possible areas in which CMP can make contribution to are suggested.

Experiments are performed to observe the influence or quantify the effect a process choice has on the process outcome. Utilization of results from controlled experiments for production plan design using conventional data analysis techniques can lead to inefficient use of available information. The scheme described in this report helps overcome this pitfall by modifying the objective function used to compute the regression parameters. The report also presents a discussion on the various ways of applying this scheme to generate the envelope.

For the face milling process, many algorithms have been developed to optimize the tool path with respect to the burr formation process, and to predict the occurrence of burrs. However, collecting data to create the factual knowledge base for face milling burr expert systems has long been seen as too costly and time consuming due to the many parameters that influence the burr formation process in the face milling operation. A suitably designed part that captures in essence the distinguishing mechanisms of burr formation can be very beneficial in reducing the number of experiments performed. This paper describes the geometry of a workpiece and the machining strategy employed to generate the distinct face milling burr formation mechanisms. Measurement is limited to burr size parameters that directly influence the functionality of the workpiece edge and the ease of burr removal in further processing. The burr data collected after machining the specially designed workpiece is stored in the database. The database is designed using an Entity-Relationship model. This high level conceptual model helps structure the data in a fashion that renders this database highly suitable for planning applications. The database is designed to handle the most important queries raised by a process planner. For example, identifying insert materials that generate the smallest burrs for a given workpiece material, and so forth. The database also directly interfaces with the optimization programs like burr prediction and tool path planning that were developed for burr minimization in face milling. In addition, this database can be used as a standalone system, i.e. a "burr expert", to recommend cutting parameters or tools for a specific material.

A method for manufacturing a new type of CMP pad is presented. The goal is to create a mold containing micro sized features that can be used in vacuum casting to produce the polymeric polishing pads. To achieve this, a positive mold is cut from PMMA using micro milling techniques. An opposite mold is then created by electroplating nickel onto the mold and separating the metal from the polymer.

High speed face milling test were performed on two aluminum silicon alloys currently used in automotive engine production to study the effect of cutting parameters and tool geometry in edge quality. Axial Rake and Radial Rake angles were varied to assess their effect in burr formation, as well as cutting speed, feedrate and depth of cut. Significant improvements in edge quality were obtained by optimizing these geometrical and kinematical parameters.

This report describes the optimization of tool path plans to minimize burr formation while face milling powertrain components in the automotive industry. The algorithm controls conditions responsible for burr formation by manipulating tool offsets to generate a feasible region for selection of tool paths.

This paper reviews some of the main developments in cutting technology since the foundation of CIRP over fifty years ago. Material removal processes can take place at considerably higher performance levels in the range up to Qw = 150 - 1500 cm3/min for most workpiece materials at cutting speeds up to some 8.000 m/min. Dry or near dry cutting is finding widespread application. The superhard cutting tool materi- als embody hardness levels in the range 3000 – 9000 HV with toughness levels exceeding 1000 MPa. Coated tool materials offer the opportunity to fine tune the cutting tool to the material being machined. Machining accuracies down to 10 ?m can now be achieved for conventional cutting processes with CNC machine tools, whilst ultraprecision cutting can operate in the range < 0.1?m. The main technological developments associated with the cutting tool and tool materials, the workpiece materials, the machine tool, the process conditions and the manufacturing environment which have led to this advancement are given detailed consideration in this paper. The basis for a roadmap of future development of cutting tech- nology is provided.

Polishing processes are critical to high value production processes such as IC manufacturing. The fundamental material removal mechanisms, howeve, are poorly understood. Technological outputs (e.g., surface finish, sub-surface damage, part shape) and throughput of lapping and polishing processes are affected by a large number of variables. Individual processes are well controlled within individual enterprises, yet there appears to be little ability to predict process performance a priori. As a first step toward improving process modeling, this paper reviews the fundamental mechanisms of material removal in lapping and polishing processes and identifies key areas where further work is required.

The influence of an exit surface angle on drilling burr formation was analyzed. The experimental research found that a burr forms on only a certain portion of a hole when an exit surface is not perpendicular to a drill path. An effective interaction angle was newly defined and the concept of degree of plastic deformation was introduced in order to explain this phenomenon. The burr forming location predicted from the effective interac- tion angle was verified with experimental results

A material removal rate (MRR) model as a function of abrasive weight concentration has been proposed by extending a material removal model developed earlier [1-2]. With an increase of the weight concentration of abrasives/MRR, three regions of material removal exist: first, a chemically dominant and rapid increasing region, whose range is determined by the generation/passivation rate and hardness of the surface passivation layer, second, a mechanically dominant linear region, where the material removal is proportional to the weight concentration, and third, a mechanical dominant saturation region, where the material removal saturates because the total contact area is fully occupied by the abrasives. The passive layer of the wafer surface is proposed to be a bi-layer structure. In the first part of this paper, a detailed model is proposed to explain that the transition from the first to the second region is due to a transition from a wafer surface covered with a single soft material to a surface covered with both soft and hard materials. The chemicals contribute to the material removal through the generation rate of the upper softer layer of the passive films. The slope of the linear region is a function of abrasive size distribution, and the saturation removal rate is a function of abrasive size distribution and wafer-pad contact area. These are supported by experimental results to be discussed in the second part of this paper [39]. The model can help to clarify the roles of chemicals, wafer-pad contact area and abrasive size distribution in chemical mechanical polishing.

An analytical model for drilling burr formation was developed. The model holds for ductile materials that do not show catastrophic fracture during the plastic deformation of workpiece material for burr formation. The proposed burr formation mechanism was based on the observation of behavior of workpiece materials during drilling of low alloy steel. The model was based on the principle of energy conservation and metal cutting theory. Experimental validation was done, and the results showed good agreement with the model. Based on the model, the effects of several important parameters on burr formation was investigated.

The low repeatability of the AE RMS level and its weak correlation with some grinding quantities has been the main problem that limits the use of this sensing technique in industrial environments. This paper presents results on the influence of some measuring conditions on the AE information. Some reliable grinding monitoring functions are proposed for production based on fast RMS analysis and binary contact detection techniques. An innovative grit mapping technique is introduced based on these new concepts. Some examples of application that include information about the topographic characteristics of a grinding wheel and its transformation during grinding are presented.