GeneH
Stainless
- Joined
- Apr 11, 2006
- Location
- Pennsylvania
An article which discusses the processes of making ICs, especially modeling vapor deposition processes and their relationship to current "global warming" models.
"Global warming theory is a prediction based on complex mathematical models developed to explain the dynamics of the atmosphere. These models must account for a myriad of factors, and the resultant equations are so complex they cannot be solved explicitly or "analytically" but rather their solutions must be approximated "numerically" with computers."
"Although based on scientific "first principles", complex numerical models inevitably require simplifications, judgment calls, and correction factors. These subjective measures may be entirely acceptable so long as the model matches the available data -- acceptable because the model is not intended to be internally consistent with all the laws of physics and chemistry, but rather to serve as an expedient means to anticipate behavior of the system in the future. However, problems can arise when R&D funding mechanisms inevitably "reward" exaggerated and alarming claims for the accuracy and implications of these models."
(edit)
"A much better analogue to climate science is found in the semiconductor industry. Integrated circuits and many other building blocks of modern electronics are manufactured by creating artificial atmospheres or "climates" within which chemical vapor deposition (CVD) forms nanometer-scale thin solid films on silicon wafer surfaces. In CVD, metal vapor precursors entrained in carrier gases are used to deposit metal films on surfaces in a condensation process not unlike formation of dew or frost on a lawn. In such CVD processes, premature formation of metal particles is unwanted and needs to be controlled and prevented; such particle formation is akin to precipitation of rain drops in the atmosphere
The semiconductor process industry uses numerical models to predict the behavior of gases and vapors in order to deposit these substances on substrates, and thereby manufacture integrated circuits. I am not a climatologist or meteorologist but I have studied fluid mechanics and gasdynamics and have a general understanding of computer models used in process engineering. Such models are used to analyze industrial processes with which I am familiar."
"Almost all semiconductor manufacturing processes occur in closed vessels. This permits the engineers to precisely control the input chemicals (gases) and the pressure, temperature, etc. with high degree of precision and reliability. Closed systems are also much easier to model as compared to systems open to the atmosphere (that should tell us something already). Computer models are used to inform the engineering team as the design the shape, temperature ramp, flow rates, etc, etc, (i.e. the thermodynamics) of the new reactor.
Nonetheless, despite the fact that 1) the chemical reactions are highly studied, 2) there exists extensive experience with similar reactors, much of it recorded in the open literature, 3) the input gases and materials are of high and known purity, and 4) the process is controlled with incredible precision, the predictions of the models are often wrong, requiring that the reactor be adjusted empirically to produce the desired product with quality and reliability.
The fact that these artificial "climates" are closed systems far simpler than the global climate, have the advantage of the experimental method, and are subject to precise controls, and yet are frequently wrong, should lend some humility to those who make grand predictions about the future of the earth's atmosphere.
So serious are the problems, sometimes, that it is not unheard of for an experimental reactor to be scrapped entirely in favor of starting from scratch in designing the process and equipment. Often a design adjustment predicted to improve performance actually does the opposite. This does not mean that process models are useless, for they undergird the engineer's understanding of what is happening in the process and help him or her make adjustments to fix the problem. But it means that they cannot be relied upon by themselves to predict results. These new adjustments and related information are then used to improve the models for future use in a step by step process tested time and again against experimental reality.
In actuality, the semiconductor industry is well familiar with the limits of process modeling and would never make a decision to purchase equipment or adjust their manufacturing processes based on predictions derived from models alone. They would rightly expect extensive experimental data to support such a decision in order to assure the ability to reliably and economically manufacture high quality materials and devices."
(edit)
"While mankind cannot experiment on the global climate, these models can be used retroactively to see how well they "model" the past. The UN's 2001 Climate Change report distorted the historical record by eliminating the Medieval Warm Period in the famous "Hockey Stick Curve" which, by many accounts, unreasonably accentuated temperature rise in the 20th century. Such distortion of the historical data undercuts the credibility of the models themselves, since this is the only "experimental data" available for testing the fidelity of the models to the actual climate.
Why on earth would climate scientists "massage the data" to produce doomsday predictions? The answer requires looking at the rewards available to these researchers."
for the rest see...
source
Gene
"Global warming theory is a prediction based on complex mathematical models developed to explain the dynamics of the atmosphere. These models must account for a myriad of factors, and the resultant equations are so complex they cannot be solved explicitly or "analytically" but rather their solutions must be approximated "numerically" with computers."
"Although based on scientific "first principles", complex numerical models inevitably require simplifications, judgment calls, and correction factors. These subjective measures may be entirely acceptable so long as the model matches the available data -- acceptable because the model is not intended to be internally consistent with all the laws of physics and chemistry, but rather to serve as an expedient means to anticipate behavior of the system in the future. However, problems can arise when R&D funding mechanisms inevitably "reward" exaggerated and alarming claims for the accuracy and implications of these models."
(edit)
"A much better analogue to climate science is found in the semiconductor industry. Integrated circuits and many other building blocks of modern electronics are manufactured by creating artificial atmospheres or "climates" within which chemical vapor deposition (CVD) forms nanometer-scale thin solid films on silicon wafer surfaces. In CVD, metal vapor precursors entrained in carrier gases are used to deposit metal films on surfaces in a condensation process not unlike formation of dew or frost on a lawn. In such CVD processes, premature formation of metal particles is unwanted and needs to be controlled and prevented; such particle formation is akin to precipitation of rain drops in the atmosphere
The semiconductor process industry uses numerical models to predict the behavior of gases and vapors in order to deposit these substances on substrates, and thereby manufacture integrated circuits. I am not a climatologist or meteorologist but I have studied fluid mechanics and gasdynamics and have a general understanding of computer models used in process engineering. Such models are used to analyze industrial processes with which I am familiar."
"Almost all semiconductor manufacturing processes occur in closed vessels. This permits the engineers to precisely control the input chemicals (gases) and the pressure, temperature, etc. with high degree of precision and reliability. Closed systems are also much easier to model as compared to systems open to the atmosphere (that should tell us something already). Computer models are used to inform the engineering team as the design the shape, temperature ramp, flow rates, etc, etc, (i.e. the thermodynamics) of the new reactor.
Nonetheless, despite the fact that 1) the chemical reactions are highly studied, 2) there exists extensive experience with similar reactors, much of it recorded in the open literature, 3) the input gases and materials are of high and known purity, and 4) the process is controlled with incredible precision, the predictions of the models are often wrong, requiring that the reactor be adjusted empirically to produce the desired product with quality and reliability.
The fact that these artificial "climates" are closed systems far simpler than the global climate, have the advantage of the experimental method, and are subject to precise controls, and yet are frequently wrong, should lend some humility to those who make grand predictions about the future of the earth's atmosphere.
So serious are the problems, sometimes, that it is not unheard of for an experimental reactor to be scrapped entirely in favor of starting from scratch in designing the process and equipment. Often a design adjustment predicted to improve performance actually does the opposite. This does not mean that process models are useless, for they undergird the engineer's understanding of what is happening in the process and help him or her make adjustments to fix the problem. But it means that they cannot be relied upon by themselves to predict results. These new adjustments and related information are then used to improve the models for future use in a step by step process tested time and again against experimental reality.
In actuality, the semiconductor industry is well familiar with the limits of process modeling and would never make a decision to purchase equipment or adjust their manufacturing processes based on predictions derived from models alone. They would rightly expect extensive experimental data to support such a decision in order to assure the ability to reliably and economically manufacture high quality materials and devices."
(edit)
"While mankind cannot experiment on the global climate, these models can be used retroactively to see how well they "model" the past. The UN's 2001 Climate Change report distorted the historical record by eliminating the Medieval Warm Period in the famous "Hockey Stick Curve" which, by many accounts, unreasonably accentuated temperature rise in the 20th century. Such distortion of the historical data undercuts the credibility of the models themselves, since this is the only "experimental data" available for testing the fidelity of the models to the actual climate.
Why on earth would climate scientists "massage the data" to produce doomsday predictions? The answer requires looking at the rewards available to these researchers."
for the rest see...
source
Gene
.
