Effects of Wafer Carrier Design on Contact Stress Uniformity in CMP

2010 ◽  
Vol 126-128 ◽  
pp. 305-310 ◽  
Author(s):  
Ian Hu ◽  
Tian Shiang Yang ◽  
Kuo Shen Chen
Keyword(s):  
Contact Stress ◽  
Removal Rate ◽  
Ring Width ◽  
Pressure Profile ◽  
Back Pressure ◽  
Design Parameters ◽  
Wafer Surface ◽  
Retaining Ring ◽  
Floating Type ◽  
Stress Uniformity

Here we use 2-D models of fluid film lubrication and contact mechanics to calculate the contact stress and fluid (i.e., slurry) pressure distributions on the wafer–pad interface in CMP. In particular, the effective rigidity of the wafer (determined by the wafer carrier structure), the retaining ring width and its back pressure are taken to be the design parameters. The purpose is to study the synergetic effects of such parameters on the contact stress non-uniformity (NU), which directly affects the spatial non-uniformity of the material removal rate on the wafer surface. Our numerical results indicate that, for a given wafer rigidity, one may choose a particular combination of the retaining ring parameters to minimize NU. Also, the corresponding minimum NU decreases with the effective wafer rigidity, suggesting that it is beneficial to use a soft (e.g., floating-type) wafer carrier. Moreover, for a soft wafer carrier, the presence of the retaining ring also reduces NU to some extent, but the use of a multi-zone wafer-back pressure profile would be more effective in this regard.

The influence of ultrasonic vibrations on material removal in the silicon wafer polishing using DDCAMRF: Experimental investigations and process optimization

2021 ◽  
pp. 095440622110389
Author(s):  
Mayank Srivastava ◽  
Pulak M Pandey
Keyword(s):  
Silicon Surface ◽  
Material Removal ◽  
Removal Rate ◽  
Statistical Investigation ◽  
Wafer Surface ◽  
Experimental Investigations ◽  
Ultrasonic Power ◽  
Ultrasonic Vibrations ◽  
Mr Fluid ◽  
Process Factors

The present experimental investigation attempts to understand and address the effect of ultrasonic vibrations on material removal in the polishing of silicon wafers (1 0 0). The requisite finishing experimentations were performed on an indigenously developed experimental arrangement of double-disc chemical assisted magnetorheological finishing (DDCAMRF) process with longitudinal vibrations. The MR fluid used in the experiments consists of a water-based suspension prepared by mixing suitable amounts of carbonyl iron particles (CIPs), abrasive particles, and additives or stabilizers. The prepared MR fluid uses both mechanics and chemistry to finish the silicon surface. Mechanics is mainly responsible for micro-scratching of silicon surface, which gets “softened” by hydration utilizing DI water in the MR fluid. In this study, the ‘response surface methodology (RSM)’ was chosen for designing the experiments to evaluate the significance of different process factors, namely polishing speed, abrasive concentration, and ultrasonic power on the material removal rate (MRR) in DDCAMRF process. The material removed from the wafer surface was measured using the precision digital weighing balance. It was observed that the MRR was found to increase with the increase in various process factors used. Further, analysis of variance (i.e., ANOVA) technique with a 95% confidence interval was performed to analyze the significant contribution of different process factors on MRR. The validation of developed model was done by performing experiments on random and optimized set of process factors. From, the statistical investigation it was discovered that ultrasonic power has highest contribution of 57.9% on MRR, followed by the polishing speed (13.3%), and abrasive concentration (12.5%). Furthermore, a genetic algorithm optimization tool was utilized to obtain optimum set of process parameters to maximize MRR.

scholarly journals DIESEL INJECTOR PUMP WITH RING CONTROL VALVE

2020 ◽  
pp. 68-76
Author(s):  
Fanil' Gabdrafikov ◽  
Irshat Aysuvakov ◽  
Ilgiz Galiev
Keyword(s):  
Fuel Injection ◽  
Ring Width ◽  
Control Valve ◽  
Free Edge ◽  
Original Position ◽  
Design Parameters ◽  
Elastic Ring ◽  
Hydraulic Actuator ◽  
Wide Range ◽  
Ring Valve

The studies were carried out with the aim of modernizing the pump injector with a hydraulic actuator of the HEUI system plunger with the development of a control valve model based on a split elastic ring that provides fast fuel injection control. The upgraded device differs from the existing ones in that instead of a control freely floating valve (ball) or a poppet valve with springs, a valve in the form of a split elastic ring is installed in the valve assembly. One end of this ring is fixed rigidly, the other is freely movable to block the drain channel of the liquid. The canal overlaps the free edge of the ring when the electromagnet is turned on (installed with a gap inside the ring), and also (in the absence or malfunction of the electromagnet) from the valve itself running under the pressure of the supplied fluid. When upgrading the pump injector by the proposed method and using an annular control valve with electronic control (with optimal ring parameters), a new technical effect is achieved - reducing the response time of the control valve. This is due to the fact that the free edge of the split elastic ring, like a mechanical multiplier, blocks the drain canal π times faster than the valve stroke when it rises from the pressure of the fluid flow or signal when the electromagnet is on. The ring valve simultaneously acts as a spring to return to its original position, simplifying the design as much as possible. In the course of research, a new mathematical expression was derived for calculating the valve stroke depending on its design parameters. Using this formula, the optimal parameters of the control ring valve of the pump injector were established, which affect the quality of fuel injection in a wide range of diesel operation: diameter - 20 mm, ring width - 12 mm, thickness - 0.46 mm, diameter of the control fluid supply canal - 3 mm.

The Force Analysis of Anchor Anti-Slide Pile in Slope Reinforcement under Seismic Load

2015 ◽  
Vol 777 ◽  
pp. 148-153
Author(s):  
Hui Ding ◽  
Jie Chen ◽  
Li Song
Keyword(s):  
Dynamic Analysis ◽  
Seismic Wave ◽  
Contact Stress ◽  
Dynamic Performance ◽  
Bending Moment ◽  
Dynamic Contact ◽  
Design Parameters ◽  
Seismic Load ◽  
Slope Reinforcement ◽  
Earthquake Action

The force affect factors of anchor anti-slide pile in slope reinforcement under seismic load are studied in this paper. First of all, the method of dynamic analysis is introduced in FLAC3D. At the same time, seismic wave is selected in seismic dynamic analysis. Then, the sensitivity influence of anti-slide pile design parameters on dynamic contact stress, shear force and dynamic bending moment is analyzed by applying the seismic wave, giving the most significant effect factors of the dynamic contact stress and dynamic moment. In the end, the distribution regular of the contact force and the pile body stress under earthquake action is analyzed by selecting a case, laying a theoretical foundation for the further study of the dynamic performance of the reinforced slope.

Thermal-Mechanical Analysis of an NCA Type of Chip-on-Glass Assemblies

2000 ◽  
Author(s):  
Hsien-Chie Cheng ◽  
Ming-Hsiao Lee ◽  
Kuo-Ning Chiang ◽  
Chung-Wen Chang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Contact Resistance ◽  
Contact Stress ◽  
Manufacturing Process ◽  
Element Model ◽  
Conductive Adhesive ◽  
Physical Contact ◽  
Design Parameters ◽  
Design Quality

Abstract Since the electrical conduction in the COG assembly using a non-conductive adhesive takes place through the connection of the bump and the electrodes, the contact resistance can be applied to the evaluation of the design quality as well as the overall reliability of the particular assembly. It should be further noted that as reported in the literature (e.g., see Liu, 1996; Kristiansen et al, 1998; Nicewarner, 1999; Timsit, 1999), the contact resistance between the bump and the electrode on the substrate strongly depends on the contact stress and the contact area. A higher reliability of the packaging somewhat relies on better contact stability as well as larger bonding stresses. In order to explore the physical contact behaviors of a non-conductive adhesive type of COG assemblies, the contact pressure during manufacturing process sequences and during the temperature variation are extensively investigated using a three-dimensional nonlinear finite element model. The so-called death-birth simulation technique is applied to model the manufacturing process sequences. The typical COG assemblies associated with two types of micro-bumps that are made of different materials: metal and composite are considered as the test vehicle. The contact stress between the electrode and the bump is extensively compared at each manufacturing sequence as well as at elevated temperature in order to investigate the corresponding mechanical interaction. Furthermore, the adhesion stresses of the adhesive are also evaluated to further investigate the possibilities of cracking or delamination within the adhesive and in its interfaces with the die and with the substrate. At last, a parametric finite element model is performed over number of geometry/material design parameters to investigate their impact on the contact/adhesion stresses so as to attain a better reliability design.

Experimental Investigation on Wafer Polishing of Oxide and Copper Layers

2002 ◽  
Author(s):  
Jhy-Cherng Tsai
Keyword(s):  
Process Parameters ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Removal Rate ◽  
Back Pressure ◽  
Copper Layer ◽  
Wafer Polishing ◽  
Critical Technology ◽  
And Performance ◽  
Polishing Pressure

Polishing, in particular chemical-mechanical polishing (CMP), is a critical technology for the planarization of wafers. This paper investigates, via experiments, and compares the performance of CMP process with different process parameters for wafers with silicon-dioxide (SiO2) layer and for wafers with copper (Cu) layer. Polishing pressure (P), speed (V), and back pressure (BP) are used as process parameters in this study. Different pads and slurries are also experimented for copper layer as its properties are different from that of conventional oxide layer. Material removal rate (RR) and non-uniformity (NU) are used as indices to measure the performance. Experimental data on oxide layers show RR increases as P and V increase but NU gets worse at the same time. This condition can be improved, for both oxide and copper layers, with suitable BP. Experiments on copper CMP using slurry with abrasives show that RR increases with higher P and V. While NU gets worse with higher P, it can be reduced as V increases using a soft pad. Better NU can be obtained using soft pad though RR is lower in this case. For abrasive-free polishing of copper layer, RR, though relatively lower compared to CMP with regular slurry, is unstable using hard pad despite that NU becomes better at higher P. NU of polished wafer is best at certain pressure but becomes worse at low pressure for hard pad and at high P for soft pad. It is also observed that NU of AFP can be improved with BP and softer pad. Soft pad gives better polishing quality and performance though RR is lower than that using slurry with abrasives.

Femur Design Parameters and Contact Stresses at UHMWPE Hip Joint Cup

2011 ◽  
Vol 478 ◽  
pp. 93-102
Author(s):  
H. Fouad ◽  
S.M. Darwish
Keyword(s):  
Hip Joint ◽  
Contact Stress ◽  
Contact Stresses ◽  
Functionally Graded ◽  
Design Parameters ◽  
Slight Reduction ◽  
Metal Backing ◽  
Low Modulus ◽  
Long Term Performance ◽  
Term Performance

The contact stress that occurs in the ultra-high molecular weight polyethylene (UHMWPE) hip joint cup has been shown to be correlated with the implant wear rate. The wear of the hip joint is considered as one of the main factors that affect the long term performance of the implant. The contact stress that occurs in the UHMWPE hip joint cup is affected by the implant dimensions and materials. In this study, four different femur materials and geometries were used to investigate the effects of femur design parameters on the resultant contact stress on the UHMWPE cup. The results of the finite element (FE) simulation show that the contact stresses at the UHMWPE cup decreases dramatically with increasing the femur diameter. Also the results indicated that the contact stresses on the UHMWPE cup decrease significantly when using functionally graded (FG) femur with low modulus of elasticity. The presence of metal backing results in a slight reduction in the UHMWPE cup contact stresses especially for small femurs. Finally, the presence of a gap between the UHMWPE cup and the femur results in a remarkable increase in the cup stress especially for a small femur. The hip joint femur dimensions and materials are thought to play an important role in the transition of load in the implant and should be taken into consideration during the design of the hip joint.

Improvement of Wafer Edge Profile and Cmp Performance Through The Floating Head Design

2000 ◽  
Vol 613 ◽  
Author(s):  
Huey-Ming Wang ◽  
Gerry Moloney ◽  
Mario Stella ◽  
Sesinando Deguzman
Keyword(s):  
Chemical Mechanical Planarization ◽  
Pressure Chamber ◽  
Point Of View ◽  
Thickness Variation ◽  
Deformation Control ◽  
Edge Profile ◽  
Retaining Ring ◽  
Floating Type ◽  
Edge Exclusion ◽  
Wafer Edge

ABSTRACTThe dependence of IC fabrication on the Chemical Mechanical Planarization (CMP) process increases as the device features go down to 0.25 micron or beyond. Due to the tighter CMP process spec, it is very important to reduce the within wafer non-uniformity (WIWNU%) to achieve higher process yield. The symmetrical increment of linear velocity at wafer edge is not sufficient to change wafer edge profile by breaking the matched speed rule. A better solution is through the change of head design for a fixed platen from the polisher design point of view. This study demonstrates the improvement of the CMP process performance, especially at the wafer edge, from the modification of the floating type polish head. The best WIWNU% from a single air chamber head is about 5.12% at 6-mm edge exclusion (EE). In order to obtain better pad deformation control, the retaining-ring pressure chamber is separated from that of the sub-carrier. The average WIWNU% is about 4% for 3-mm and 5-mm EE from two-pressure-chamber head. Due to the limitation of retaining-ring pressure effect, a third pressure chamber is further added that can be extended the edge control up to 1 inch from the wafer edge. The WIWNU% is about 3.8% at 5-mm edge exclusion with low down forces. The slurry and insert types also show effect on the wafer edge profile. It has been also proven that this three-pressure-chamber head is able to reduce the post-CMP thickness variation from the ILD production wafer, especially at wafer edges. More detailed information and CMP mechanism will be discussed in this paper.

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