Load Lock Wafer Heating via Resistive and Radiant Sources
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Solution Overview
Problem
Current wafer heating methods in load locks are inefficient due to high pedestal temperatures, slow heating times, and challenges in achieving uniform temperature control, which limits throughput and introduces contamination risks.
Innovation Solution
A combination of radiant and resistive heat sources is used to heat wafers in a load lock, with resistive heating initially bringing the wafer to 250-600°C and then radiant heating taking over, aided by an inert gas and electrostatic chuck for precise temperature control, allowing for rapid and uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heated pedestal is used for wafer heating in a load lock, then the wafer can be heated, but the heating is inefficient and slow because the pedestal must be maintained at much higher temperatures than desired
Solution Approach 1:
An inert gas (such as nitrogen or argon) is introduced as an intermediary medium between the heated pedestal and the wafer. The gas conducts heat from the pedestal to the wafer more efficiently than direct contact heating, allowing the pedestal to operate at lower temperatures while still achieving the desired wafer temperature. This resolves the contradiction by improving heat transfer efficiency without requiring excessive pedestal temperature.
Solution Approach 2:
The invention changes the heat transfer parameter from direct thermal conduction through contact to thermal conduction through a gas medium. By controlling the inert gas pressure and flow, the heat transfer coefficient is optimized to achieve rapid and uniform wafer heating at lower pedestal temperatures, thereby improving heating efficiency and reducing energy consumption.
2Temperature
If a heated pedestal is used for wafer heating, then heating can be achieved, but the heating time is long which limits throughput
Solution Approach 1:
The inert gas acts as a highly efficient thermal conductor between the pedestal and wafer, dramatically increasing the heat transfer rate. This intermediary gas medium enables rapid heating of the wafer to the desired temperature, reducing heating time from minutes to seconds and thereby improving system throughput.
Solution Approach 2:
The invention replaces the slow thermal diffusion process inherent in direct contact heating with a more efficient gas-phase heat conduction mechanism. By controlling gas pressure and composition, the system achieves rapid thermal energy transfer that overcomes the time limitation of conventional pedestal heating.
3Temperature
If a heated pedestal is used for wafer heating, then heating can be achieved, but uniform temperature control is difficult which introduces contamination risks
Solution Approach 1:
The inert gas provides a uniform heat distribution medium that surrounds the wafer, ensuring even temperature across the entire wafer surface. This eliminates hot spots and temperature gradients that occur with direct contact heating, achieving uniform temperature control that prevents contamination from thermal stress or incomplete processing.
Solution Approach 2:
The use of inert gas creates a controlled atmosphere that prevents chemical contamination while simultaneously providing uniform heat transfer. The inert nature of the gas prevents unwanted reactions, while its thermal conduction properties ensure uniform heating, thereby eliminating contamination risks associated with both heating method and atmospheric composition.
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 wafers to reach high temperatures uniformly in seconds, improving throughput and reducing contamination risks by minimizing the need for intermediate heating stations and enhancing temperature control accuracy.
Implementation Method 1
The heat is transmitted by gas conduction and radiation through a small gap between the wafer and the pedestal
Implementation Method 2
The heat is transmitted by gas conduction and radiation through a small gap between the wafer and the pedestal
Implementation Method 3
aided by an inert gas and electrostatic chuck for precise temperature control
Data Source
AI summary
A semiconductor processing tool heats wafers using radiant heat and resistive heat in chamber or in a load lock where pressure changes. The wafers are heated in greater part with a resistive heat source until a transition temperature or pressure is reached, then they are heated in greater part with a radiant heat source. Throughput improves for the tool because of the wafers can reach a high temperature uniformly in seconds.