Electrostatic Wafer Chuck Heat Spreader for Uniform Wafer Temperature
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Solution Overview
Problem
Existing electrostatic wafer chucks experience inconsistent wafer temperature variations due to non-uniform internal heating and cooling designs, leading to reduced process control and increased complexity and cost, with temperature feedback measurements often being distant from the wafer surface, introducing offset errors.
Innovation Solution
Incorporating a high thermal conductivity heat spreading layer and relocating temperature measurement probes closer to the wafer surface or providing a direct line of sight for optical measurements, along with a multi-layer ceramic plate structure that includes a heat spreader and dielectric layers to enhance heat distribution and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If existing electrostatic wafer chucks use non-uniform internal heating and cooling designs, then device complexity is reduced, but wafer temperature uniformity deteriorates
Solution Approach 1:
The patent applies local quality by creating non-uniform heating zones with different power densities across the wafer surface. The heating element is designed with spatially varying thermal conductivity and heating power distribution to compensate for heat loss patterns, ensuring uniform temperature across the wafer despite non-uniform internal heating structure.
Solution Approach 2:
The patent changes physical parameters including thermal conductivity distribution, heating power density, and layer thicknesses of dielectric and conductive layers. By adjusting these parameters non-uniformly across different regions, the system achieves uniform wafer temperature without requiring complex uniform heating mechanisms.
2Measurement precision
If temperature measurement probes are relocated closer to the wafer surface, then temperature measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses an optical fiber as an intermediary to measure wafer temperature without direct contact. The optical fiber transmits light through the wafer-backside assembly, and temperature-dependent optical properties (absorption, scattering, fluorescence) serve as the measurement mechanism, eliminating the need for complex probe positioning near the wafer surface.
Solution Approach 2:
The patent replaces mechanical temperature probes with optical measurement methods. Instead of physically contacting the wafer with temperature sensors, the system uses optical properties that change with temperature, substituting a mechanical measurement system with an optical field-based system.
3Temperature
If a heat spreader layer is added to enhance heat distribution, then wafer temperature uniformity is improved, but device complexity increases
Solution Approach 1:
The patent segments the heating and thermal management function into multiple distinct layers: a heating element layer, dielectric layers with specific thicknesses, and conductive layers. Each layer has a specific thermal and electrical function, allowing independent optimization of heat generation, insulation, and distribution without requiring a single complex component.
Solution Approach 2:
The patent uses composite material structures combining dielectric materials with different thermal conductivities and electrical properties. The multi-layer construction with varying material properties creates controlled thermal pathways that spread heat uniformly while maintaining electrical isolation, achieving temperature uniformity through material composition rather than mechanical complexity.
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 design improves wafer surface temperature uniformity, reduces temperature variation, and increases process control and yield, while simplifying the system and reducing costs by integrating heat spreading and temperature sensing for more precise control.
Implementation Method 1
a heater; a heat spreader configured to uniformly distribute heat from the heater to the semiconductor wafer
Implementation Method 2
a heat spreader configured to uniformly distribute heat from the heater to the semiconductor wafer
Implementation Method 3
an electrode configured to electrostatically hold a semiconductor wafer
Data Source
AI summary
This disclosure describes electrostatic wafer chuck designs for holding and heating semiconductor wafers. An electrostatic wafer chuck may include a metal base; a temperature sensor; and a multi-layer ceramic plate including: a bonding layer; a heater; a first dielectric positioned between the heater and the bonding layer; an electrode to electrostatically hold a semiconductor wafer; a second dielectric positioned between the heater and the electrode; a heat spreader to uniformly distribute heat from the heater to the semiconductor wafer; and a third dielectric positioned between the electrode and the semiconductor wafer; and a temperature sensor may extend through the metal base and at least partially through the multi-layer ceramic plate.