Mini-Environment Temperature Control for Semiconductor Wafer Inspection
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Solution Overview
Problem
Existing methods for temperature control in semiconductor inspection apparatuses, such as CD-SEM, result in decreased throughput due to standby times and poor heat transfer performance, leading to temperature differences between the wafer and sample table, which affect image precision.
Innovation Solution
An apparatus with a mini-environment device equipped with a temperature control mechanism that measures and adjusts the temperature of the sample and sample table, ensuring the sample reaches a desired temperature quickly before observation, thereby eliminating standby times and improving heat transfer performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standby time is set for thermal equilibrium between wafer and sample table, then temperature difference is reduced, but apparatus throughput decreases
Solution Approach 1:
The temperature control mechanism performs preliminary temperature adjustment of the wafer before it is placed on the sample table. By controlling the wafer temperature in advance within the load lock chamber or during conveyance, the system eliminates the need for standby time after wafer placement, as thermal equilibrium is achieved beforehand rather than waiting passively for equilibrium to occur naturally.
2Reliability
If temperature control is performed inside the load lock chamber, then heat transfer performance improves, but device complexity increases
Solution Approach 1:
The temperature control mechanism uses an intermediary heating/cooling system within the load lock chamber to adjust wafer temperature before transfer. This intermediary system acts as a buffer that prepares the wafer thermally without requiring modification of the main sample table or vacuum chamber, thereby improving heat transfer performance while isolating the complexity to a specific subsystem rather than the entire apparatus.
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 configuration significantly enhances the throughput of the apparatus by eliminating standby times and ensuring precise temperature control, reducing thermal expansion and contraction-induced position changes, and maintaining precise pattern measurement without altering the load lock chamber temperature.
Implementation Method 1
a temperature control mechanism which can control a temperature of a sample inside the mini-environment device
Implementation Method 2
The vacuum evacuation of the load lock chamber is rapidly carried out. Accordingly, air temperature inside the load lock chamber is lowered due to adiabatic expansion
Implementation Method 3
the wafer is subjected to thermal expansion and contraction until the wafer is brought into a thermal equilibrium state
Data Source
AI summary
In order to prevent a sample from thermally expanding and contracting when the sample is placed on a sample stage inside a vacuum chamber, the related art has proposed a coping method of awaiting observation by setting a standby time from when the wafer is conveyed into the vacuum chamber until the wafer and the sample table are brought into thermal equilibrium. In addition, the coping method is configured so as to await the observation until the wafer is cooled down to room temperature when the wafer is heated in the previous step. Consequently, throughput of an apparatus decreases. A temperature control mechanism which can control temperature of the sample is installed inside a mini-environment device. The sample temperature control mechanism controls the temperature of the sample inside the mini-environment device so as to become a setting temperature which is set in view of a lowered temperature of the sample inside a load lock chamber.