Bi-directional Substrate Cooling via Dual Gas Flow
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Solution Overview
Problem
Current semiconductor wafer cooling techniques are inefficient, leading to prolonged processing times and increased costs due to the inability to effectively cool wafers from high temperatures before transferring them outside a processing chamber, especially in oxygen-rich environments, where passive cooling methods are impractical and may cause surface oxidation.
Innovation Solution
A bi-directional cooling process within the processing chamber using cooling gases directed at both the upper and lower surfaces of the substrate, with a combination of a gas distribution showerhead and an EFEM end effector introducing gases in opposite directions to accelerate cooling without handling the wafer, minimizing thermal shock and ensuring uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If passive cooling is used to cool the wafer from high temperature to transfer temperature, then the wafer can be transferred outside the processing chamber, but the cooling time becomes too long (more than 10 seconds)
Solution Approach 1:
The patent introduces active cooling gas flow through nozzles positioned above and below the wafer to rapidly cool the wafer surface. This pneumatic cooling system replaces passive radiative/convective cooling with forced gas flow, dramatically reducing cooling time from over 10 seconds to a much shorter duration, thereby improving throughput while enabling safe transfer at lower temperatures.
Solution Approach 2:
The cooling process is segmented into two independent cooling zones: one cooling the upper surface of the wafer from above, and another cooling the lower surface from below. This segmentation allows simultaneous cooling of both wafer surfaces, doubling the effective cooling area and significantly reducing total cooling time compared to single-sided cooling.
2Speed
If the wafer is transferred outside the processing chamber at high temperature, then transfer speed may be increased, but surface oxidation occurs in oxygen rich environment
Solution Approach 1:
The system performs preliminary active cooling of the wafer to below 230°C before transfer outside the processing chamber. By pre-cooling the wafer to a safe temperature threshold while still inside the chamber, the wafer can then be transferred at high speed without risk of surface oxidation in the oxygen-rich external environment.
Solution Approach 2:
The processing chamber maintains an inert or controlled atmosphere during the active cooling process, preventing oxidation while the wafer is being rapidly cooled. This controlled environment allows the wafer to be cooled to safe temperatures before exposure to oxygen-rich external conditions during transfer.
3Loss of time
If active cooling gas flow is introduced to cool the wafer rapidly, then cooling time is reduced, but thermal shock may damage the wafer
Solution Approach 1:
The cooling gas flow is distributed across multiple nozzles positioned at different locations above and below the wafer, creating localized cooling zones rather than concentrated intense cooling at one point. This distributed local cooling approach reduces thermal gradients across the wafer surface, minimizing thermal shock while maintaining rapid overall cooling rate.
Solution Approach 2:
The system dynamically controls the cooling gas flow rate and distribution, adjusting the intensity of cooling based on real-time conditions. The cooling process is made adaptive rather than static, allowing optimization between cooling speed and thermal shock prevention by modulating gas flow characteristics during the cooling cycle.
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 significantly reduces wafer cooling time, prevents surface oxidation, and maintains uniformity, thereby enhancing processing efficiency and reducing costs by allowing for faster throughput and minimizing the risk of wafer damage during handling.
Implementation Method 1
first cooling gas is introduced into the processing chamber from the upper gas source; the first cooling gas is introduced into the chamber in a downward direction towards the upward facing surface of the substrate
Implementation Method 2
second cooling gas is introduced, from the body portion of the end effector, into the processing chamber in an upward direction towards the downward facing surface of the substrate
Implementation Method 3
the substrate is heated to a high temperature in a processing chamber, while the substrate is held in a first position; when held in the first position, the substrate is located in proximity to a heat source
Data Source
AI summary
Techniques and mechanisms for cooling a substrate in a processing chamber by a bi-directional cooling process prior to transferring the substrate outside the processing chamber are provided. First cooling gas is introduced into the processing chamber from an upper gas source in a downward direction towards the upward facing surface of the substrate. An apparatus is placed underneath and in proximity to the substrate. Second cooling gas is introduced from the apparatus into the processing chamber in an upward direction towards the downward facing surface of the substrate. One or more gaps are cut out of the body portion of the apparatus, the gaps configured to allow the apparatus to avoid contact with the support structure holding the substrate, as the apparatus is moved in a horizontal direction into position underneath the substrate during placement of the body portion of the apparatus in proximity to the substrate.