Energy Transfer Layer for Uniform Rapid Thermal Processing
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Solution Overview
Problem
Current rapid thermal processing (RTP) systems face challenges in achieving uniform heating and control of semiconductor wafers due to variations in optical properties and three-dimensional topography, leading to temperature gradients and non-uniform process results, especially during high-temperature, short-duration annealing processes.
Innovation Solution
The application of an energy transfer layer on the wafer surface that absorbs or generates heat through chemical reactions, such as exothermic or endothermic processes, to influence the thermal profile and enhance heat transfer, allowing for more controlled and uniform thermal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If external energy sources (tungsten-halogen lamps or hot-wall furnace) are used for rapid thermal processing, then heating capability is achieved, but temperature uniformity deteriorates due to variations in optical properties and three-dimensional topography
Solution Approach 1:
An energy transfer layer is introduced as an intermediary between the external energy source and the wafer surface. This layer absorbs radiant energy from the heat source and transfers it to the wafer through thermal conduction, mediating the heating process to achieve more uniform temperature distribution across the wafer surface regardless of optical property variations or topography
Solution Approach 2:
The invention replaces direct radiant heating (electromagnetic energy transfer) with conductive heating through the energy transfer layer. By substituting the heating mechanism from direct radiation absorption to thermal conduction through a medium, the system overcomes the limitations of optical property variations and achieves superior temperature uniformity
2Speed
If high power energy sources are used for millisecond annealing, then heating rate is improved, but temperature non-uniformity worsens due to uneven power coupling across the wafer surface
Solution Approach 1:
The energy transfer layer serves as a mediator that decouples the high power energy source from direct interaction with the wafer surface. The layer absorbs the high power radiant energy and distributes it uniformly through thermal conduction, enabling rapid heating without the temperature non-uniformity that would result from direct high power coupling to patterned wafer surfaces
Solution Approach 2:
The invention changes the thermal parameters at the wafer surface by introducing a layer with specific thermal properties. The energy transfer layer has thermal conductivity and heat capacity parameters that enable rapid energy transfer while smoothing out spatial variations in energy distribution, thus achieving both high heating rate and temperature uniformity
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 improved uniformity and repeatability of thermal processing by managing temperature gradients and optimizing heat transfer, reducing the peak-width of annealing cycles and minimizing thermal stresses, while also simplifying equipment design and increasing throughput.
Implementation Method 1
applying an energy transfer layer on the wafer surface that absorbs or generates heat through chemical reactions
Implementation Method 2
absorbs or generates heat through chemical reactions, such as exothermic or endothermic processes
Implementation Method 3
Surface heating allows very rapid heating of the relatively small thermal mass of the surface region, as well as quick cooling because the heat in the surface region is dissipated into the bulk of the wafer by thermal conduction
Data Source
AI summary
A method that is performed for heat treating a semiconductor wafer in a process chamber, as an intermediate part of an overall multi-step technique for processing the wafer, includes applying an energy transfer layer to at least a portion of the wafer, and exposing the wafer to an energy source in the process chamber in a way which subjects the wafer to a thermal profile such that the energy transfer layer influences at least one part of the thermal profile. The thermal profile has at least a first elevated temperature event. The method further includes, in time relation to the thermal profile, removing the energy transfer layer in the process chamber at least sufficiently for subjecting the wafer to a subsequent step. An associated intermediate condition of the wafer is described.