Light-Irradiated Wafer Oxidation for Precise Thin Oxide Films
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Solution Overview
Problem
Conventional thermal oxidation methods struggle to form silicon oxide films with good properties due to oxidation starting at undesired temperatures during wafer transport and difficulty in controlling film thickness, especially for high dielectric constant films in semiconductor manufacturing.
Innovation Solution
A method involving light irradiation of a substrate to heat it, followed by switching to an oxidizing atmosphere when a predetermined temperature is reached, and controlling the growth of the oxide film by adjusting gas supply and pressure, using a heat treatment apparatus with a chamber, light irradiator, gas supply part, and pressure reduction mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thermal oxidation methods are used, then silicon oxide films can be formed, but oxidation starts at undesired temperatures during wafer transport and film thickness control is difficult
Solution Approach 1:
The patent replaces conventional thermal oxidation (heating the entire furnace) with light irradiation heating (direct optical energy conversion to thermal energy at the substrate surface). This substitution enables precise temperature control during oxidation by controlling light intensity and duration, preventing premature oxidation during transport while achieving desired film thickness through controlled irradiation parameters
Solution Approach 2:
The patent changes the heating method parameter from thermal conduction (furnace heating) to optical conversion (light irradiation). By adjusting light irradiation parameters (intensity, wavelength, duration) and oxidizing gas parameters (pressure, flow rate, composition), the patent achieves precise control over oxidation timing and film thickness, resolving both the premature oxidation and thickness control issues
2Manufacturing precision
If light irradiation is used to heat the substrate, then oxidation can be suppressed at lower temperatures and film thickness can be precisely controlled, but additional equipment and process complexity are required
Solution Approach 1:
The patent designs the light irradiation apparatus to serve multiple functions: heating the substrate, controlling oxidation timing, and enabling precise film thickness control, all within a single integrated system. The gas supply system also provides dual functionality by controlling both atmosphere composition and pressure, reducing the need for separate control systems
Solution Approach 2:
The patent controls the oxidation process by adjusting parameters of existing components (light irradiation intensity, gas pressure, gas flow rate) rather than adding complex new subsystems. This parameter-based control approach achieves precise film thickness control while minimizing additional apparatus complexity
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 the formation of thin oxide films with superior properties by suppressing oxidation at lower temperatures and allowing precise control over film thickness.
Implementation Method 1
irradiating the substrate with light to heat the substrate
Implementation Method 2
supplying an oxidizing gas into the chamber to change an atmosphere within the chamber... oxidation reaction of silicon
Data Source
AI summary
A silicon semiconductor wafer is transported into a chamber, and preheating of the semiconductor wafer is started in a nitrogen atmosphere by irradiation with light from halogen lamps. When the temperature of the semiconductor wafer reaches a predetermined switching temperature in the course of the preheating, oxygen gas is supplied into the chamber to change the atmosphere within the chamber from the nitrogen atmosphere to an oxygen atmosphere. Thereafter, a front surface of the semiconductor wafer is heated for an extremely short time period by flash irradiation. Oxidation is suppressed when the temperature of the semiconductor wafer is relatively low below the switching temperature, and is caused after the temperature of the semiconductor wafer becomes relatively high. As a result, a dense, thin oxide film having good properties with fewer defects at an interface with a silicon base layer is formed on the front surface of the semiconductor wafer.