Photo-Illuminated Electrostatic Clamping for High-Resistivity Substrates
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Solution Overview
Problem
Existing electrostatic clamps are ineffective in clamping high resistivity semiconductor substrates and electrically insulating substrates due to slow charge redistribution, which hampers processing efficiency, especially in ion implantation and other manufacturing processes.
Innovation Solution
The introduction of an illumination system that directs radiation with energy equal to or above a threshold (2.5 eV) to the substrate, generating mobile charges and enhancing conductivity, allowing for effective photo-assisted electrical clamping and releasing of substrates, including high resistivity and insulating materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic clamps are used to clamp substrates, then clamping force is generated, but high resistivity and insulating substrates cannot be effectively clamped due to slow charge redistribution
Solution Approach 1:
The patent changes the electrical parameter of the substrate by illuminating it with light of sufficient energy (≥2.5 eV) to generate mobile charge carriers. This transforms insulating or high resistivity substrates into effectively conductive states, enabling electrostatic clamping to work on previously incompatible substrate types.
Solution Approach 2:
The illumination system acts as an intermediary that mediates between the electrostatic clamp and the substrate. By introducing photons as an intermediate energy carrier, the system enables charge generation in the substrate without direct electrical contact, thus allowing clamping of high resistivity materials.
2Speed
If AC voltage is applied to generate clamping, then rapid clamping and declamping is achieved, but high resistivity and insulating substrates remain ineffective
Solution Approach 1:
The illumination is applied preliminarily or simultaneously with the AC voltage to pre-generate mobile charge carriers in the substrate. This preliminary charge generation ensures that when the AC voltage is applied, sufficient charge redistribution occurs rapidly, achieving both fast response and effective clamping on high resistivity substrates.
3Reliability
If substrate charging is allowed during processing, then electrostatic clamping is maintained, but substrate charging issues adversely affect processing especially in ion implantation
Solution Approach 1:
The illumination system serves as a controlled intermediary that generates charge carriers in a controlled manner. By regulating the illumination intensity and spectral content, the system maintains sufficient charge for clamping while preventing excessive charge buildup that would cause harmful charging effects during processing.
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
This approach enables reliable clamping and declamping of high resistivity substrates, such as glass and silicon carbide, by significantly reducing charging time and enhancing clamping force, thereby improving processing efficiency and addressing substrate charging issues.
Implementation Method 1
an illumination system, disposed to direct radiation to a front side substrate, opposite the back side of the substrate, when the substrate is disposed on the electrostatic clamp, wherein the radiation comprises a radiation energy, the radiation energy being equal to or above 2.5 eV
Implementation Method 2
Electrostatic clamping uses the principle of electrostatic induction where electrical charge is redistributed in an object due to the direct influence of nearby charges
Implementation Method 3
Electrostatic clamping uses the principle of electrostatic induction where electrical charge is redistributed in an object due to the direct influence of nearby charges. This charge creates an attractive force between the object and substrate
Data Source
AI summary
An apparatus may include a clamp to clamp a substrate wherein the clamp is arranged opposing a back side of the substrate; and an illumination system, disposed to direct radiation to the substrate, when the substrate is disposed on the clamp, wherein the radiation comprises a radiation energy equal to or above a threshold energy to generate mobile charge in the substrate, where the illumination system is disposed to direct radiation to a front side of the substrate, opposite the back side of the substrate.