Pad Soaking Effect on Interfacial Fluid Pressure Measurements During CMP

2003 ◽  
Vol 125 (3) ◽  
pp. 582-586 ◽  
Author(s):  
Sum Huan Ng ◽  
Robert Hight ◽  
Chunhong Zhou ◽  
Inho Yoon ◽  
Steven Danyluk
Keyword(s):  
Water Absorption ◽  
Fluid Pressure ◽  
High Rate ◽  
Pressure Measurements ◽  
Ambient Fluid ◽  
Polishing Process ◽  
Soaking Time ◽  
Polishing Pad ◽  
Topmost Layer ◽  
Interfacial Fluid

Prior work has shown that there exist a sub-ambient fluid pressure at the interface between a rigid flat and the polishing pad during chemical mechanical polishing (CMP). This sub-ambient fluid pressure can have a significant impact on the polishing process since its magnitude may be similar to the applied load, depending on conditions. Further results have shown that there is a relationship between pad soaking time and the magnitude of this sub-ambient fluid pressure. This paper addresses measurements of the pad soaking time versus the magnitude of the sub-ambient interfacial fluid pressure. Experiments utilized a Rodel IC1000 polishing pad made of foamed polyurethane with average void size of 30 to 50 microns. Pad soaking tests indicated that the weight of the pad increased with soaking time due to water absorption. There is a high rate of water absorption initially before the pad becomes saturated and the mass of the pad stabilizes. It is also observed that the pad material is impermeable to water and most of the water penetrated only the topmost layer of voids in the material. These experiments suggest that the water progressively “softens” the top layers of the pad during the soaking and causes the sub-ambient fluid pressure to increase in magnitude. A model of the sub-ambient fluid pressure increasing as the elastic modulus of the pad decreases is also suggested.

Interfacial Fluid Pressure and Its Effects on SiO2 Chemical Mechanical Polishing

2000 ◽  
Vol 613 ◽  
Author(s):  
C. Zhou ◽  
L. Shan ◽  
J. R. Hight ◽  
S.H. Ng ◽  
A. J. Paszkowski ◽  
...  
Keyword(s):  
Material Removal ◽  
Removal Rate ◽  
Fluid Pressure ◽  
Single Crystal Silicon ◽  
Ambient Fluid ◽  
Crystal Silicon ◽  
Order Of Magnitude ◽  
Interfacial Fluid ◽  
Friction Measurements ◽  
P Type

ABSTRACTIn this paper, the experimental results of interfacial fluid pressure and friction measurements during polishing are presented, as well as their dependence on some major process variables. Under simulated conditions, a sub-ambient fluid pressure was observed, and its magnitude was of the same order of magnitude as the applied polishing load. Since this fluid pressure is non-uniformly distributed, the contact stress, obtained by combining the effects of both applied load and the fluid pressure, is not uniform across the wafer and will result in non-uniform material removal. The mechanism of the presence of the fluid pressure was investigated, and an analytical model was developed to predict the magnitude and distribution of this fluid pressure. The effects of the sub-ambient fluid pressure on material removal rate and profile were tested with thermally grown silicon dioxide on 100mm diameter, P-type (100), single crystal silicon wafers. The polishing experiments show the effect of sub-ambient fluid pressure on polishing rate and profile.

An Analysis of Mixed Lubrication in Chemical Mechanical Polishing

2005 ◽  
Vol 127 (2) ◽  
pp. 287-292 ◽  
Author(s):  
Sum Huan Ng ◽  
C. Fred Higgs, ◽  
Inho Yoon ◽  
Steven Danyluk
Keyword(s):  
Shear Flow ◽  
Physical Meaning ◽  
Parametric Study ◽  
Chemical Mechanical Polishing ◽  
Fluid Pressure ◽  
Mixed Lubrication ◽  
Mechanical Polishing ◽  
Ambient Fluid ◽  
Interfacial Fluid

Pressure and shear flow factors (Patir and Cheng, 1978) were used to take into account the roughness of the pad surface in the modeling of the interfacial fluid pressure during chemical mechanical polishing. An attempt was made to explain the physical meaning of the flow factors in this particular application. Additionally, a parametric study was carried out to see the effect on the model after the incorporation of the flow factors. The pressure and shear flow factors were found to have a competing effect on the magnitude of the sub-ambient fluid pressure.

Achieving High Flatness of Workpiece Edge Shape by Considering Polishing Pressure

2010 ◽  
Vol 447-448 ◽  
pp. 71-75
Author(s):  
Takahiro Miyake ◽  
Toshiyuki Enomoto
Keyword(s):  
Semiconductor Devices ◽  
Silicon Wafers ◽  
Polishing Process ◽  
Model Based ◽  
Polishing Pad ◽  
Experimental Analyses ◽  
Polishing Pads ◽  
Polishing Pressure

In recent years, the achievement of further high flatness of workpiece edge shape is strongly required in mirror finishing. Especially, the edge roll off of silicon wafers as the substrates of semiconductor devices is demanded to decrease in the polishing process for raising the yield of IC chips. Many theoretical and experimental analyses for the edge roll off generation have been already done to meet the demand. The analyses, however, cannot fully account for the obtained edge shape in actual polishing. Concretely, the influence of the polishing pressure as one of the key polishing conditions on the edge roll off has not been clarified. In this study, the influence of the polishing pressure on the edge shape was investigated by the polishing experiments and the edge roll off generation analyses using the model based on the viscoelasticity of the polishing pad, which was proposed in the previous study. And it was revealed that an appropriate polishing pressure is needed to be set for achieving high flatness of workpiece edge shape with the consideration of the properties of applied polishing pads.

Digital manometry to measure cerebrospinal fluid pressure during lumbar puncture

2021 ◽  
pp. 197140092110551
Author(s):  
Robert Heider ◽  
Peter G Kranz ◽  
Erin Hope Weant ◽  
Linda Gray ◽  
Timothy J Amrhein
Keyword(s):  
Cerebrospinal Fluid ◽  
Lumbar Puncture ◽  
Pressure Measurement ◽  
Fluid Pressure ◽  
Cerebrospinal Fluid Pressure ◽  
Pressure Measurements ◽  
Csf Pressure ◽  
Left Lateral Decubitus Position ◽  
Significant Difference ◽  
Time Savings

Rationale and Objectives Accurate cerebrospinal fluid (CSF) pressure measurements are critical for diagnosis and treatment of pathologic processes involving the central nervous system. Measuring opening CSF pressure using an analog device takes several minutes, which can be burdensome in a busy practice. The purpose of this study was to compare accuracy of a digital pressure measurement device with analog manometry, the reference gold standard. Secondary purpose included an assessment of possible time savings. Materials and Methods This study was a retrospective, cross-sectional investigation of 71 patients who underwent image-guided lumbar puncture (LP) with opening CSF pressure measurement at a single institution from June 2019 to September 2019. Exclusion criteria were examinations without complete data for both the digital and analog measurements or without recorded needle gauge. All included LPs and CSF pressures were measured with the patient in the left lateral decubitus position, legs extended. Acquired data included (1) digital and analog CSF pressures and (2) time required to measure CSF pressure. Results A total of 56 procedures were analyzed in 55 patients. There was no significant difference in mean CSF pressures between devices: 22.5 cm H2O digitally vs 23.1 analog ( p = .7). Use of the digital manometer resulted in a time savings of 6 min (438 s analog vs 78 s digital, p < .001). Conclusion Cerebrospinal fluid pressure measurements obtained with digital manometry demonstrate comparable accuracy to the reference standard of analog manometry, with an average time savings of approximately 6 min per case.

A clinical comparison of subdural screw pressure measurements with ventricular pressure

1983 ◽  
Vol 58 (1) ◽  
pp. 45-50 ◽  
Author(s):  
A. David Mendelow ◽  
John O. Rowan ◽  
Lilian Murray ◽  
Audrey E. Kerr
Keyword(s):  
Head Injury ◽  
Intracranial Pressure ◽  
Severe Head Injury ◽  
Fluid Pressure ◽  
Ventricular Catheter ◽  
Pressure Measurements ◽  
Content Type ◽  
Single Lumen ◽  
Ventricular Fluid Pressure ◽  
Fine Print

✓ Simultaneous recordings of intracranial pressure (ICP) from a single-lumen subdural screw and a ventricular catheter were compared in 10 patients with severe head injury. Forty-one percent of the readings corresponded within the same 10 mm Hg ranges, while 13% of the screw pressure measurements were higher and 46% were lower than the associated ventricular catheter measurements. In 10 other patients, also with severe head injury, pressure measurements obtained with the Leeds-type screw were similarly compared with ventricular fluid pressure. Fifty-eight percent of the dual pressure readings corresponded, while 15% of the screw measurements were higher and 27% were lower than the ventricular fluid pressure, within 10-mm Hg ranges. It is concluded that subdural screws may give unreliable results, particularly by underestimating the occurrence of high ICP.

Tilt and Interfacial Fluid Pressure Measurements of a Disk Sliding on a Polymeric Pad

2005 ◽  
Vol 127 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Sum Huan Ng ◽  
Len Borucki ◽  
C. Fred Higgs ◽  
Inho Yoon ◽  
Andre´s Osorno ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Reynolds Equation ◽  
Fluid Pressure ◽  
Leading Edge ◽  
Dominant Factor ◽  
Pressure Measurements ◽  
Capacitive Sensing ◽  
One Dimensional ◽  
Pressure Mapping ◽  
Pressure Region

Previous experimental work has shown that negative fluid pressure does develop at the disk/pad interface during chemical mechanical polishing. However, these studies dealt with one-dimensional measurement and modeling. To better understand the problem, two-dimensional pressure mapping is carried out. In addition, the orientation of the disk is measured with a capacitive sensing technique. Results reveal a large negative pressure region at the disk/pad interface that is skewed toward the leading edge of the disk. The disk is also found to be leaning down toward the leading edge and toward the center of the pad. A mixed-lubrication model based on the Reynolds equation and taking into account the disk orientation angles has been developed. Modeling and experimental results show similar trends, indicating the tilting of the disk as a dominant factor in causing the negative pressure phenomenon.

Effects of the Profile of Workpiece Surface on Material Removal Rate Distribution in Polishing Process

2016 ◽  
Vol 851 ◽  
pp. 149-154
Author(s):  
Zhen Gang Wu ◽  
Dong Shan He ◽  
Ping Zhou ◽  
Dong Ming Guo
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Surface Profile ◽  
Prediction Method ◽  
Quantitative Prediction ◽  
Polishing Process ◽  
Workpiece Surface ◽  
Coefficient Distribution ◽  
Polishing Pad

Accurate prediction of the material removal rate (MRR) distribution is very important for the control of the polishing process. However, the widely used prediction method of MRR based on the Preston equation is still incapable of predicting the roll-off phenomenon in polishing process. One of the reasons is that many of the researchers’ neglected the effect of the surface profile of the workpiece on the MRR. In this paper, the evolutionary process of MRR distribution with the change of surface profile using two different polishing pad is studied, it is found that MRR varies gradually with the change of surface profile and tends to be uniform finally. Based on the analysis of contact pressure considering the actual surface profile of workpiece and modified Preston equation, the distribution of MRR is analyzed. It is found that the Preston coefficient distribution on workpiece surface is stable when the surface profile variation is small and shows obvious differences from the center to the edge of the workpiece. Through the comparison it is found that correlation between the regularities of Preston coefficient distribution and the type of polishing pad is significant. The research results in this paper will play an important guiding role in the quantitative prediction method research of polishing process.

A simplified method for obtaining cerebrospinal fluid pressure measurements in the dog

1963 ◽  
Vol 18 (4) ◽  
pp. 837-837 ◽  
Author(s):  
Javier Verdura ◽  
Robert J. White ◽  
Henry Kretchmer
Keyword(s):  
Cerebrospinal Fluid ◽  
Continuous Monitoring ◽  
Fluid Pressure ◽  
Cerebrospinal Fluid Pressure ◽  
Cerebrospinal Fluid Leakage ◽  
Pressure Measurements ◽  
Fluid System ◽  
Polyethylene Tube ◽  
Simplified Method ◽  
Direct Inspection

A simplified method for recording the cerebrospinal fluid pressure in the dog is presented. It consists of introducing the polyethylene tube of a Rochester needle into the sub-arachnoid space at the level of the ventral atlanto-occipital joint. The advantages of this technique are: the dura mater is punctured under direct vision; a completely sealed fluid system results which permits direct inspection for cerebrospinal fluid leakage; and the animal may be placed in any anatomical position during the continuous monitoring of cerebrospinal fluid pressure. This method of measuring the cerebrospinal fluid pressure has been utilized in 30 canine experiments and has proven equally effective in recording cerebrospinal fluid pressures in monkeys. Submitted on December 21, 1962

scholarly journals Cerebro?spinal fluid pressure measurements during an�sthesia

Anaesthesia ◽  
1966 ◽  
Vol 21 (2) ◽  
pp. 189-201 ◽  
Author(s):  
D. GORDON McDOWALL ◽  
JOHN BARKER ◽  
W. BRYAN JENNETT
Keyword(s):  
Fluid Pressure ◽  
Spinal Fluid ◽  
Pressure Measurements
Sign in / Sign up

Export Citation Format

Share Document