Alumina Electrostatic Chuck with Carbon-Graded Support for Niobium Diffusion Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electrostatic chucks with heaters using aluminum nitride for ceramics face issues with substrate detachment response, dielectric breakdown, and non-uniform heating due to low volume resistivity and niobium diffusion, especially when high voltages are applied.
Innovation Solution
An electrostatic chuck with a base made of sintered alumina, featuring a dielectric layer with low carbon content and a support member with varying carbon concentrations to prevent niobium diffusion and enhance anti-dielectric breakdown characteristics, while using niobium or platinum for the resistance heating body to ensure uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If aluminum nitride is used for the ceramics of the base, then the base has good thermal conductivity, but the volume resistivity is small causing decreased substrate detachment response
Solution Approach 1:
The patent changes the material parameter from aluminum nitride to alumina, which fundamentally alters both thermal conductivity and volume resistivity. Alumina provides sufficiently high volume resistivity (10^14 Ω·cm or more) to ensure rapid substrate detachment response, while maintaining adequate thermal conductivity for heating purposes.
Solution Approach 2:
The base is constructed as a composite structure combining alumina ceramic with a carbon-containing sintered layer. This composite approach allows the alumina to provide high volume resistivity for detachment response, while the carbon-containing layer compensates for thermal conductivity and prevents niobium diffusion.
2Reliability
If alumina is used for the base to increase volume resistivity, then substrate detachment response improves, but niobium diffusion into the support member occurs causing non-uniform heating
Solution Approach 1:
A carbon-containing sintered layer is introduced as an intermediary barrier between the alumina base and the niobium resistance heating body. This intermediate layer prevents niobium atoms from diffusing into the alumina support member, thereby maintaining uniform heating characteristics while allowing the alumina to provide high volume resistivity for detachment response.
Solution Approach 2:
The base structure is designed with spatially varying composition: the region adjacent to the resistance heating body contains carbon (0.03-5 wt%) to prevent niobium diffusion, while other regions maintain pure alumina properties for high volume resistivity. This local quality variation addresses both the detachment response and heating uniformity requirements.
3Force
If high voltage is applied to increase suction force, then substrate holding force improves, but dielectric breakdown occurs
Solution Approach 1:
The patent increases the volume resistivity parameter of the base material to 10^14 Ω·cm or more by using alumina instead of aluminum nitride. This parameter change allows the dielectric layer to withstand high voltages (several thousand volts) applied to the ESC electrode for generating strong suction force, preventing dielectric breakdown.
4Stability of the object's composition
If the resistance heating body contains niobium for thermal expansion matching, then thermal compatibility improves, but niobium diffusion changes resistance characteristics causing malfunction
Solution Approach 1:
The carbon-containing sintered layer serves as a protective intermediary between the niobium resistance heating body and the alumina support member. This intermediate layer maintains thermal expansion compatibility while blocking the diffusion path of niobium atoms, preventing changes in resistance characteristics and ensuring stable heating performance.
Solution Approach 2:
The patent extracts the niobium containment function from the bulk alumina material and concentrates it in a specific carbon-containing layer adjacent to the heating body. This extraction allows the majority of the alumina to maintain its high volume resistivity properties while only a localized region provides diffusion protection.
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
The solution enhances substrate detachment response, prevents dielectric breakdown, and maintains uniform heating performance even under high voltage conditions, improving the reliability and temperature controllability of the electrostatic chuck.
Implementation Method 1
an electrostatic chuck of a type using Coulomb force as the electrostatic force... holds the substrate on the substrate mounting surface by electrostatic force generated on the substrate mounting surface
Implementation Method 2
a resistance heating body for heating up the substrate... heats up the semiconductor wafer
Data Source
AI summary
An electrostatic chuck with a heater includes: a base formed of a sintered body containing alumina; an ESC electrode provided in an upper portion side in the base; and a resistance heating body embedded in a lower portion side in the base. The base is composed of a dielectric layer from the ESC electrode to an upper surface of the base, and of a support member from the ESC electrode to a lower surface of the base. In the support member, a carbon content differs between an ESC electrode neighborhood in contact with the dielectric layer and a lower region below the ESC electrode neighborhood, a carbon content in the dielectric layer is 100 wt ppm or less, the carbon content in the ESC electrode neighborhood is 0.13 wt % or less, the carbon content in the lower region is 0.03 wt % or more and 0.5 wt % or less, and the carbon content in the ESC electrode neighborhood is smaller than the carbon content in the lower region. The resistance heating body contains niobium or platinum.