Electrostatic-Capacitance Pressure Sensor Diaphragm Segmentation
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Solution Overview
Problem
Electrostatic-capacitance pressure sensors in semiconductor manufacturing face issues with zero point shifts and reduced pressure sensitivity due to deposits on the diaphragm, leading to incorrect pressure measurements and frequent unnecessary adjustments.
Innovation Solution
A method and device that calculate an index for malfunction detection by comparing changes in capacitance between electrode pairs when the medium is removed, distinguishing between pressure-induced and deposit-induced deformations, reducing the frequency of unnecessary zero point adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the diaphragm vacuum gauge is used to measure pressure in semiconductor manufacturing processes, then pressure measurement is unaffected by gas species, but deposits form on the diaphragm causing zero point shift and reduced measurement precision
Solution Approach 1:
The patent segments the diaphragm into multiple regions with different thicknesses (thin region and thick region) by forming a step portion. This segmentation allows the thin region to be more sensitive to pressure changes while the thick region is less susceptible to deposit-induced deformation, thereby maintaining measurement precision despite deposit formation.
Solution Approach 2:
The patent applies local quality by creating a step portion that divides the diaphragm into regions with different properties. The thin region provides high pressure sensitivity while the thick region provides stability against deposit effects. Additionally, pressure introduction holes are strategically positioned in specific regions to optimize the local quality distribution.
2Measurement precision
If adjustments are made frequently to correct zero point shifts, then measurement accuracy is maintained, but productivity decreases due to frequent interruptions
Solution Approach 1:
The patent performs preliminary action by forming the step portion and positioning pressure introduction holes during manufacturing to pre-compensate for deposit formation effects. This preliminary structural design reduces the need for frequent adjustments during operation, maintaining productivity while ensuring measurement accuracy.
Solution Approach 2:
The patent implements self-service through the step portion structure that automatically compensates for deposit-induced zero point shifts. The differential thickness design causes the thin and thick regions to deform differently under deposits, and the signal processing unit utilizes this differential behavior to self-correct measurement errors without requiring manual intervention.
3Stability of the object's composition
If the diaphragm thickness is increased to reduce sensitivity to deposits, then zero point stability improves, but pressure sensitivity decreases
Solution Approach 1:
The patent segments the diaphragm thickness into two distinct regions: a thin region for high pressure sensitivity and a thick region for stability against deposit-induced deformation. This segmentation allows the system to simultaneously achieve both zero point stability and pressure sensitivity that would be contradictory in a uniform thickness diaphragm.
Solution Approach 2:
The patent applies local quality by assigning different thicknesses to different regions of the diaphragm. The thin region (central portion) provides high pressure sensitivity while the thick region (peripheral portion) provides stability. The step portion creates a clear boundary between these regions with different local qualities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively differentiates between pressure changes and changes caused by deposits, minimizing incorrect adjustments and improving the reliability of pressure measurements in semiconductor processes.
Implementation Method 1
an electrostatic-capacitance pressure sensor that uses a sensor element of this type. In an electrostatic-capacitance pressure sensor, a diaphragm elastically deforms when subjected to the pressure of a medium to be measured, and the displacement of the diaphragm is detected as a change in electrostatic capacitance
Implementation Method 2
a diaphragm elastically deforms when subjected to the pressure of a medium to be measured
Data Source
AI summary
An electrode pair that forms a pressure-sensitive capacitance Cx in the central portion of a diaphragm is called a first electrode pair (pressure-sensing electrode pair), and another electrode pair that forms a reference capacitance Cr in the circumferential portion of the diaphragm is called a second electrode pair (reference electrode pair). The ratio ΔCx/ΔCr of a change ΔCx in the pressure-sensitive capacitance Cx, which is obtained from the pressure-sensing electrode pair at the time of evacuation, to a change ΔCr in the reference capacitance Cr, which is obtained from the reference electrode pair at the time of evacuation, is calculated as an index for malfunction detection α. Then, the index for malfunction detection α thus calculated is compared with the reference value αref, which represents the index observed during normal operation, and whether deformation due to a cause other than pressure has been generated in the diaphragm is determined.