Wafer Temperature Measurement via Amorphous Layer Recrystallization
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Solution Overview
Problem
In semiconductor wafer annealing processes, existing methods struggle to accurately measure temperature variations across different positions in a furnace, leading to yield and characteristic degradation due to discrepancies between intended and actual wafer temperatures.
Innovation Solution
A method involving ion implantation to form an amorphous layer on the wafer, followed by thermal treatment and film thickness measurement before and after recrystallization, where the temperature is calculated based on the film thickness difference using a preset relation, allowing for precise temperature measurement without the need for expensive thermocouple-equipped monitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermocouple-equipped monitor wafers are used for temperature measurement, then temperature measurement capability is provided, but measurement precision and reliability are insufficient due to contactless measurement limitations
Solution Approach 1:
The patent introduces an amorphous layer as an intermediary substance between the wafer and the measurement system. This layer undergoes controlled recrystallization during thermal treatment, and the recrystallized depth serves as a proxy indicator for temperature exposure. By measuring the film thickness of this intermediary layer before and after thermal treatment, the system indirectly but accurately determines the temperature history of the wafer without requiring direct contact measurement devices.
2Measurement precision
If expensive thermocouple-equipped monitor wafers are used, then temperature measurement is enabled, but manufacturing cost increases significantly
Solution Approach 1:
The patent employs a cost-effective amorphous layer formed through standard ion implantation processes that already exist in semiconductor manufacturing. This layer serves as a single-use temperature indicator that can be measured, discarded, or reused after one measurement cycle. The approach eliminates the need for expensive thermocouple-equipped monitor wafers while maintaining measurement accuracy, as the amorphous layer can be formed using conventional ion implantation equipment and measured using standard film thickness measurement tools.
3Ease of operation
If temperature profile control is used in furnace annealing, then temperature management is implemented, but actual wafer temperature varies from intended temperature due to position-dependent differences
Solution Approach 1:
The patent applies local quality by placing multiple amorphous layer-formed wafers at different positions within the furnace during thermal treatment. Each wafer at a specific location experiences the local temperature conditions of that position, and its amorphous layer recrystallizes accordingly. By measuring the film thickness of amorphous layers from wafers at various positions, the system maps the temperature distribution throughout the furnace, revealing position-dependent temperature variations that differ from the intended uniform temperature profile.
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 approach enables more accurate and cost-effective temperature measurement across the furnace, reducing the influence of inter-sample variance and providing detailed temperature distribution, thereby improving process control and wafer quality.
Implementation Method 1
introducing an impurity into a first surface of a wafer to form an amorphous layer
Implementation Method 2
thermally treating the wafer to recrystallize part of the amorphous layer
Data Source
AI summary
A semiconductor wafer temperature measurement method according to the present embodiment includes introducing an impurity into a first surface of a wafer to form an amorphous layer on a side of the first surface of the wafer. The present temperature measurement method includes measuring a first film thickness that is the film thickness of the amorphous layer. The present temperature measurement method includes thermally treating the wafer to recrystallize part of the amorphous layer. The present temperature measurement method includes measuring a second film thickness that is the film thickness of the amorphous layer after the thermal treatment. The present temperature measurement method includes measuring the temperature of the wafer at the thermal treatment based on a film thickness difference between the first film thickness and the second film thickness.