Electrostatic Chuck Porous Part for Temperature Uniformity
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Solution Overview
Problem
Electrostatic chucks with ceramic porous bodies for improved insulating properties in gas introduction paths suffer from low heat transfer rates, leading to temperature non-uniformity issues during substrate processing, resulting in hot spots and cold spots on the wafer surface.
Innovation Solution
The electrostatic chuck incorporates a ceramic dielectric substrate with a metal base plate and a porous part in the gas introduction path, featuring sparse and dense portions with specific pore dimensions and arrangements to enhance thermal conductivity and mechanical strength, ensuring uniform temperature control across the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic sintered porous body is used in the gas introduction path to improve insulating property, then electrical insulation is improved, but heat transfer rate decreases leading to temperature non-uniformity
Solution Approach 1:
The porous part is designed with non-uniform pore distribution, featuring sparse portions with larger pores for heat transfer and dense portions with smaller pores for electrical insulation. This local variation in pore density allows different regions of the same component to serve different functions: heat transfer zones and insulation zones, resolving the contradiction between thermal conductivity and electrical insulation
Solution Approach 2:
The porous part functions as a composite structure combining ceramic material with controlled porosity features. The integration of sparse and dense portions within a single ceramic component creates a composite-like behavior that simultaneously provides both thermal conductivity pathways and electrical insulation, addressing the contradictory requirements
2Productivity
If the porous part has high porosity for gas flow, then gas introduction efficiency is improved, but thermal conductivity decreases
Solution Approach 1:
Different regions of the porous part have different porosity characteristics: sparse portions with higher porosity and larger pores facilitate gas flow, while dense portions with lower porosity and smaller pores maintain thermal conductivity. This spatial variation in pore structure allows the single component to simultaneously optimize both gas introduction and heat transfer functions
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 configuration significantly improves temperature uniformity and mechanical strength, allowing for effective heat transfer and gas flow while preventing position shifts of the porous part, thus ensuring high temperature uniformity and rigidity of the wafer during processing.
Implementation Method 1
the heat transfer rate from the porous part to the ceramic dielectric substrate is lower than the thermal conductivity from the metal base plate to the ceramic dielectric substrate
Implementation Method 2
an electrostatic suction power is applied to built-in electrodes and a substrate such as a silicon wafer or the like is sucked by an electrostatic force
Implementation Method 3
an inactive gas such as helium (He) or the like is flown between a surface of the ceramic dielectric substrate and a back side of the substrate being a suction object, and a temperature of the substrate being the suction object is controlled
Data Source
AI summary
According to the embodiment, an electrostatic chuck includes a ceramic dielectric substrate, a base plate, and a porous part. The ceramic dielectric substrate has a first major surface placing a suction object, a second major surface on an opposite side to the first major surface, and a through hole provided from the second to first major surface. The base plate supports the ceramic dielectric substrate and includes a gas introduction path communicating with the through hole. The porous part is provided in the gas introduction path. The porous part includes sparse portions including pores and a dense portion having a higher density than the sparse portions. Each of the sparse portions extends in a first direction from the base plate toward the ceramic dielectric substrate. The dense portion is positioned between the sparse portions. The sparse portions include the pores and a wall portion provided between the pores.