In-situ Wafer Temperature Control via Optical Fiber Detection
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Solution Overview
Problem
The semiconductor industry faces challenges in controlling critical dimension (CD) due to variations in substrate temperature during plasma etching, as traditional methods lack in-situ monitoring and precise control, leading to chamber-to-chamber inconsistencies and difficulties in achieving stringent CD control.
Innovation Solution
An automated in-situ wafer temperature measurement system using light-sensitive materials and fiber optic pipes to monitor substrate temperature, coupled with a chamber controller that adjusts electrostatic chuck parameters to maintain desired temperature ranges, ensuring continuous monitoring and tight CD control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If substrate temperature is indirectly controlled by controlling the ESC temperature, then the ESC temperature can be monitored, but the substrate temperature cannot be precisely controlled due to heat transfer limitations
Solution Approach 1:
A light-sensitive material is introduced as an intermediary between the light source and the detection system. This material converts thermal energy to optical signals that can be detected and used to determine substrate temperature, resolving the inability to directly measure substrate temperature through ESC temperature monitoring alone
Solution Approach 2:
The patent replaces the indirect thermal control method (controlling ESC temperature) with a direct optical detection method. By using light-sensitive materials that emit or reflect light in response to temperature, the system substitutes mechanical/thermal measurement with optical measurement, enabling precise substrate temperature determination
2Adaptability or versatility
If ESC surface roughness changes due to process chemistries, then the contact between ESC and wafer changes, but substrate temperature drifts over time
Solution Approach 1:
The system continuously monitors substrate temperature through the light-sensitive material and provides feedback to the control system. When temperature drift is detected, the ESC temperature is adjusted in real-time to compensate, maintaining stable substrate temperature despite changes in ESC-wafer contact caused by surface roughness variations
Solution Approach 2:
The light-sensitive material on the substrate serves itself by directly indicating its own temperature state through optical properties. This self-indicating mechanism eliminates the need for separate temperature sensors that could be affected by ESC surface changes, providing stable temperature measurement regardless of contact variations
3Productivity
If multiple plasma etching chambers are used to reach manufacturing throughput, then productivity increases, but chamber-to-chamber variation in etching performance increases
Solution Approach 1:
The patent enables direct measurement and control of substrate temperature as a critical process parameter in each chamber. By monitoring and adjusting substrate temperature (along with other parameters like ESC temperature, RF power, and gas flow) in each individual chamber, the system achieves consistent etching performance across multiple chambers, eliminating chamber-to-chamber variation while maintaining high throughput
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 provides instant and precise substrate temperature control, minimizing wafer-to-wafer and chamber-to-chamber variations, thereby enhancing the consistency of etch profiles and meeting stringent CD requirements in advanced semiconductor manufacturing.
Implementation Method 1
a light source coupled to the at least one light pipe, the light source being configured to supply light to the at least one light pipe so as to apply light to the at least one spot on the backside of the substrate
Implementation Method 2
a light source coupled to the at least one light pipe, the light source being configured to supply light to the at least one light pipe so as to apply light to the at least one spot on the backside of the substrate
Data Source
AI summary
Broadly speaking, the embodiments of the present invention fill the need by providing in-situ wafer temperature measuring method and apparatus. The in-situ substrate temperature measuring method and apparatus provide instant wafer temperature information to allow for continuous monitoring of the etching process. The method and apparatus also allow for instant substrate temperature control to tighten wafer-to-wafer and chamber-to-chamber process distribution. An exemplary cluster tool system is provided. The cluster tool system includes a substrate holding station for holding a substrate capable of emitting signals indicative of substrate temperature, and a processing chamber, the processing chamber being configured to receive the substrate from the substrate holding station and to run through an active process operation when the substrate is in the processing chamber. The cluster tool system also includes a signal detector for detecting the signals emitted by the substrate when the processing chamber runs through the active process operation, the signal detector being configured to collect the emitted signals indicative of the substrate temperature.