Electrostatic Chuck Cooling for High-Rate Selective Plasma Etching
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Solution Overview
Problem
Plasma etching processes for semiconductor substrates face challenges with low etching rates and poor selectivity, particularly when attempting to improve etching rates at low temperatures, which can lead to non-uniform recess depths and critical dimensions in semiconductor devices.
Innovation Solution
The development of an apparatus for plasma etching that includes an electrostatic chuck with a base layer, bonding layer, adsorption layer, and edge ring, along with a cooling system that allows for precise temperature control by injecting a coolant to reach specific temperature ranges during different stages of the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is performed at low temperature to improve etching rate, then etching rate is improved, but selectivity for substrate deteriorates
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the substrate temperature during different stages of the etching process. The temperature is lowered to −40° C. to −5° C. during main etching to maximize etching rate, then raised to 30° C. to 90° C. during over-etching to improve selectivity. This temporal variation in temperature resolves the contradiction between maintaining high etching rate and achieving good selectivity.
Solution Approach 2:
The patent implements periodic action through a two-stage temperature control cycle: first stage at low temperature (−40° C. to −5° C.) for main etching, second stage at higher temperature (30° C. to 90° C.) for over-etching. This periodic temperature adjustment allows the system to achieve both high productivity during main etching and high reliability during over-etching.
2Productivity
If plasma etching is performed at low temperature to improve etching rate, then etching rate is improved, but uniformity of recess depths deteriorates
Solution Approach 1:
The patent uses dynamic temperature adjustment to resolve the uniformity issue. By raising the temperature during over-etching (30° C. to 90° C.), the etching process becomes more uniform across the substrate surface, ensuring consistent recess depths while maintaining high etching rate during the main etching stage.
3Productivity
If plasma etching is performed at low temperature to improve etching rate, then etching rate is improved, but critical dimensions of lower hole deteriorate
Solution Approach 1:
The patent applies periodic temperature control to protect critical dimensions. The low temperature (−40° C. to −5° C.) is applied only during main etching when high productivity is needed, while the higher temperature (30° C. to 90° C.) is applied during over-etching to ensure precise critical dimensions of lower holes are maintained.
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 solution enables improved selectivity for semiconductor substrates while maintaining high etching rates, and ensures uniform control of recess depths and critical dimensions, thereby enhancing the quality and reliability of semiconductor devices.
Implementation Method 1
a cooling device configured to inject the coolant into the electrostatic chuck through the plurality of pipes and the plurality of coolant suppliers to control a temperature of the electrostatic chuck
Implementation Method 2
an electrostatic chuck disposed in a chamber in which a plasma etching process is performed
Implementation Method 3
plasma may be used in an etching process of a substrate, among semiconductor processes. Plasma etching may be performed by applying a high energy to gaseous molecules in a vacuum to ionize or decompose and activate the molecules
Implementation Method 4
applying a high energy to gaseous molecules in a vacuum to ionize or decompose and activate the molecules
Data Source
AI summary
An apparatus for plasma etching having an electrostatic chuck including a base layer, a bonding layer, an adsorption layer including a plurality of protrusions on the bonding layer and contacting a lower surface of a substrate, and an edge ring spaced apart from and surrounding a lateral surface of the substrate; a plurality of coolant suppliers injecting a coolant between the plurality of protrusions; a plurality of pipes supplying the coolant to the plurality of coolant suppliers to circulate the coolant in a predetermined direction; a cooling device in which the plasma etching process includes first and second operations, wherein the coolant is injected to cause the electrostatic chuck to reach a first temperature during the first operation, and reach a second temperature during the second operation; and a controller controlling a valve connected to the plurality of pipes to determine a circulation direction of the coolant.