Substrate Temperature Cycling for Uniform Semiconductor Etching
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Solution Overview
Problem
The etching process in semiconductor manufacturing often suffers from non-uniformity across the substrate plane, leading to variations in etching rates and film quality.
Innovation Solution
A technique involving a cycle of temperature stabilization and controlled etching gas supply, where the substrate temperature is first set and stabilized at a high temperature, then lowered to a lower temperature while supplying an etching gas, such as Cl2, to promote uniform etching across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If etching gas is supplied at constant high temperature, then etching rate is high, but in-plane uniformity deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant-temperature etching process to a dynamic temperature-changing process. The substrate temperature is first raised to a high temperature (400-600°C) to achieve high etching rate, then lowered (200-400°C) to improve in-plane uniformity. This temporal variation in temperature allows the system to achieve both high productivity and high precision that cannot be obtained at a single fixed temperature.
Solution Approach 2:
The etching process is divided into distinct periodic stages: a first period at high temperature for rapid etching, and a second period at lower temperature for uniformity improvement. This periodic action between different temperature states allows the process to sequentially achieve both high etching rate and good in-plane uniformity, resolving the contradiction between speed and quality.
2Manufacturing precision
If substrate temperature is lowered to improve uniformity, then in-plane uniformity improves, but etching rate decreases
Solution Approach 1:
The patent applies preliminary action by first establishing high substrate temperature to achieve high etching rate before the uniformity problem becomes critical. The high-temperature phase performs the primary etching work, and then the temperature is lowered in a subsequent phase to correct uniformity issues. This sequential approach ensures that productivity is maintained while still achieving the desired uniformity.
Solution Approach 2:
The patent changes the temperature parameter dynamically during the etching process. Instead of maintaining a constant temperature, the substrate temperature is changed from a first temperature (400-600°C) to a second temperature (200-400°C). This parameter change allows the system to optimize for different objectives at different times: high rate first, then high uniformity.
3Productivity
If temperature is stabilized at high value, then etching rate is high, but wafer-to-wafer uniformity deteriorates
Solution Approach 1:
The patent applies dynamics by implementing a two-stage temperature profile that varies over time. The first stage maintains high temperature for high etching rate, while the second stage lowers the temperature to improve wafer-to-wafer uniformity. This dynamic temperature control allows the system to achieve both high productivity and good uniformity across different wafers, resolving the contradiction that exists in constant-temperature processes.
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 method improves both in-plane and wafer-to-wafer uniformity of the etching process by adjusting the etching rate based on temperature differences, ensuring consistent film formation and reducing surface roughness.
Implementation Method 1
setting a temperature of the substrate having the first film formed on the surface to a first temperature; stabilizing an in-plane temperature of the substrate at the first temperature
Implementation Method 2
an etching gas is supplied to the substrate for a predetermined period
Data Source
AI summary
There is provided a technique that includes partially etching a film formed on a surface of a substrate by performing a cycle a predetermined number of times, the cycle including: (a) setting a temperature of the substrate having the first film formed on the surface to a first temperature; (b) stabilizing an in-plane temperature of the substrate at the first temperature; and (c) lowering the temperature of the substrate having the in-plane temperature stabilized at the first temperature from the first temperature to a second temperature that is lower than the first temperature, wherein in (c), an etching gas is supplied to the substrate for a predetermined period.