Intermediate Dry-Gas Chamber for Condensation-Free Wafer Transfer
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Solution Overview
Problem
Condensation forms on workpieces when transferred from a cold ion implantation environment to a warmer external environment, leading to defects and production losses due to deposited particles and residues.
Innovation Solution
An ion implantation system with a sub-ambient temperature chuck and an intermediate chamber that cools or heats the workpiece to prevent condensation, using a dry gas with a dew point less than the external environment to isolate the intermediate environment from the external environment, thereby minimizing exposure to moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the workpiece is cooled to a processing temperature below the dew point of the external environment, then ion implantation processing is enabled, but condensation forms on the workpiece when transferred to the external environment
Solution Approach 1:
An intermediate chamber is introduced between the process chamber and external environment. This intermediate chamber serves as a buffer zone where the workpiece can be transferred without direct exposure to the external environment. The chamber maintains a controlled atmosphere with pressure between vacuum and atmospheric pressure, preventing condensation while allowing the workpiece to remain at low processing temperatures.
Solution Approach 2:
The intermediate chamber is filled with a dry gas (such as nitrogen or dry air) that has a dew point lower than the workpiece temperature. This creates an inert atmosphere that prevents moisture condensation on the cold workpiece surface during transfer, eliminating the harmful condensation effect while maintaining the low temperature processing capability.
2Object-affected harmful factors
If the workpiece is held in the load lock chamber for temperature adjustment, then condensation is prevented, but processing time increases
Solution Approach 1:
The workpiece is pre-cooled to the processing temperature in the process chamber before transfer to the intermediate chamber. This preliminary cooling action eliminates the need for time-consuming heating or cooling operations in the load lock chamber, as the workpiece is already at the desired temperature when transferred to the condensation-prevention zone.
Solution Approach 2:
The intermediate chamber provides a rapid transfer pathway that eliminates the need for extended load lock chamber holding times. By providing a controlled environment immediately upon transfer, the workpiece doesn't need to wait in the load lock chamber for temperature adjustment, significantly reducing processing time while still preventing condensation.
3Object-affected harmful factors
If the intermediate chamber uses dry gas with low dew point, then condensation is prevented, but system complexity increases
Solution Approach 1:
The intermediate chamber serves multiple functions simultaneously: it acts as a pressure buffer between vacuum and atmospheric environments, provides a condensation-free transfer zone, and enables rapid workpiece ejection. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in system complexity despite the added capability of condensation prevention.
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
Effectively prevents condensation on workpieces during transfer, reducing defects and production losses by maintaining a controlled environment that keeps the workpiece above the dew point temperature of the external environment, thus ensuring a dry and controlled transfer process.
Implementation Method 1
a clamping voltage is typically applied between the wafer and the electrode, wherein the wafer is clamped against the chuck surface by electrostatic forces
Implementation Method 2
a sub-ambient temperature chuck, such as a cryogenically cooled electrostatic chuck, is configured to support the workpiece within the process chamber
Implementation Method 3
The positive pressure source is configured to provide a dry gas to the intermediate chamber. The dry gas, for example, has a dew point that is less than a dew point of the external environment
Implementation Method 4
a heating station configured to heat the workpiece to a second temperature. The first temperature, for example, is associated with the process temperature, and the second temperature is associated with an external temperature
Data Source
AI summary
An ion implantation system provides ions to a workpiece positioned in a process environment of a process chamber on a sub-ambient temperature chuck. An intermediate chamber having an intermediate environment is in fluid communication with an external environment and has a cooling station and heating station for cooling and heating the workpiece. A load lock chamber is provided between the process chamber and intermediate chamber to isolate the process environment from the intermediate environment. A positive pressure source provides a dry gas within the intermediate chamber at dew point that is less than a dew point of the external environment to the intermediate chamber. The positive pressure source isolates the intermediate environment from the external environment via a flow of the dry gas from the intermediate chamber to the external environment.