Wafer Flash Heating Layout with Shielded LED Bump Connections
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Solution Overview
Problem
Existing heat treatment apparatuses using flash lamps and semiconductor light emitting elements face damage from direct or reflected light, leading to wire breaks and substrate burning, which affects the efficiency and durability of the auxiliary light source.
Innovation Solution
The heat treatment apparatus includes an auxiliary light source with a substrate made of inorganic insulating material and semiconductor light emitting elements connected via bumps hidden from direct flash irradiation, preventing damage during flash irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If halogen lamps are used for preheating, then infrared heating capability is provided, but heating efficiency is low at temperatures of 500°C or below
Solution Approach 1:
The patent changes the spectral parameters of the light source by replacing halogen lamps with LED lamps that emit light with wavelengths not greater than 1 μm. This parameter change enables efficient absorption by silicon wafers at low temperatures (500°C or below), where conventional halogen lamps with longer wavelength infrared light are ineffective. The LED light sources are configured to match the absorption characteristics of silicon at different temperature ranges, thereby resolving the contradiction between providing infrared heating capability and achieving efficient heating at low temperatures.
2Ease of manufacture
If semiconductor light emitting elements are mounted on a substrate with wire bonding, then the auxiliary light source can be constructed, but the wires are damaged by flash lamp irradiation causing breaks
Solution Approach 1:
The patent extracts and eliminates the vulnerable wire bonding component from the system. Instead of using wire bonding to connect semiconductor light emitting elements to the substrate, the invention employs alternative connection methods such as bump bonding or direct chip attachment that do not involve exposed wire bonds. This extraction of the problematic element (wire bonds) prevents them from being damaged by flash lamp irradiation, thereby maintaining both the constructability and reliability of the auxiliary light source.
Solution Approach 2:
The patent applies beforehand cushioning by protecting the connection structures between semiconductor light emitting elements and substrate from flash lamp damage. By using connection methods inherently resistant to flash lamp irradiation (such as enclosed bump connections or positioning connections behind the chip), the design preemptively prevents the wire breakage problem before it can occur during flash lamp operation.
3Area of stationary object
If the auxiliary light source is positioned to provide preheating, then heating coverage is improved, but the substrate and light emitting elements are damaged by direct or reflected flash lamp light
Solution Approach 1:
The patent applies dimensionality change by positioning the auxiliary light source and its components in a spatial arrangement that places them outside the direct path of flash lamp irradiation. The semiconductor light emitting elements and substrate are positioned behind the chip or in shielded locations, effectively using the chip itself as a shield. This spatial reconfiguration maintains the heating coverage area while eliminating exposure to harmful flash lamp radiation.
Solution Approach 2:
The patent uses the chip structure itself as an intermediary shield or barrier. The chip body is positioned between the flash lamp light path and the vulnerable components (substrate, connection structures), acting as a natural shield that blocks direct and reflected flash lamp irradiation from reaching these components. This intermediary positioning allows the auxiliary light source to function effectively while protecting its components from damage.
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
Prevents damage to the auxiliary light source, ensuring reliable and efficient heating of semiconductor wafers by maintaining the integrity of the light emitting elements and substrates.
Implementation Method 1
an auxiliary light source provided on one side of the chamber and irradiating the semiconductor wafer held by the holder with light
Implementation Method 2
a flash lamp provided on the other side of the chamber and irradiating the semiconductor wafer preheated by the auxiliary light source with a flash of light
Data Source
AI summary
A flash heating part including multiple flash lamps is provided over a chamber for receiving a semiconductor wafer therein, and an auxiliary heating part is provided under the chamber. The auxiliary heating part is provided with multiple chips each including a semiconductor light emitting element. A pattern of an electrically conductive material is formed on a substrate made of aluminum nitride, and a plating layer of gold is formed on the pattern. A connection surface of each of the chips faces downward, and electrodes provided on the lower surface thereof are connected to electrodes on the pattern side by bumps. The bumps are hidden behind the chips as seen from the flash lamps, and are prevented from being damaged by flash irradiation.