Wafer Bonding Plasma Reduction for Oxide-Free Conductive Pads
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Solution Overview
Problem
Challenges exist in achieving high-quality hybrid bonding between semiconductor wafers due to the presence of oxide materials on conductive pads, which lead to increased resistance and reduced bonding quality in three-dimensional integrated circuits (3DICs).
Innovation Solution
An apparatus and method involving a plasma module and cleaning modules are used to remove metal oxides from the conductive pads of semiconductor wafers, followed by a bonding process that forms both metal-to-metal and non-metal-to-non-metal bonds, enhancing bonding integrity and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding processes are used without oxide removal, then the bonding process is simpler, but bonding quality and electrical performance deteriorate due to increased resistance
Solution Approach 1:
The patent applies preliminary plasma treatment and oxide removal processes before bonding to eliminate oxide materials from conductive pads. This preliminary action ensures that the bonding interface is free from contaminants that would increase resistance, thereby improving bonding quality and electrical performance before the actual bonding occurs.
Solution Approach 2:
The patent changes the chemical and physical parameters of the conductive pad surfaces through plasma treatment and controlled oxidation/reduction cycles. These parameter changes transform the surface properties to achieve optimal bonding conditions, reducing resistance while maintaining process control.
2Strength
If high pressure and temperature are applied in bonding, then bonding strength improves, but the risk of damage to sensitive structures increases
Solution Approach 1:
The patent performs preliminary oxide removal and surface activation treatments that prepare the bonding interfaces for stronger bonding at lower pressures and temperatures. This preliminary preparation eliminates the need for excessive bonding conditions, thereby reducing the risk of damage to sensitive semiconductor structures while achieving adequate bonding strength.
Solution Approach 2:
The patent replaces purely mechanical bonding (relying on high pressure and temperature) with a chemically-enhanced bonding process. By using plasma treatment and controlled oxide removal, the bonding mechanism is enhanced at the molecular level, allowing for lower mechanical stress and temperature conditions that reduce damage risk.
3Productivity
If oxide materials remain on conductive pads, then the bonding process is faster, but electrical resistance increases and performance decreases
Solution Approach 1:
The patent implements preliminary plasma cleaning and oxide removal steps that quickly eliminate oxide materials from conductive pads before bonding. This preliminary action ensures that the bonding interface has minimal resistance, improving electrical performance without significantly extending the overall process time.
Solution Approach 2:
The patent uses rapid plasma treatment and controlled chemical reactions to remove oxides in a time-efficient manner. By optimizing the parameters of oxide removal (such as plasma power, gas flow, and treatment duration), the process achieves effective oxide elimination quickly, maintaining high productivity while ensuring low resistance and excellent electrical performance.
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
The method improves bonding quality and performance by reducing oxide material on conductive pads, allowing for lower pressures and temperatures in the bonding process, resulting in stronger and more reliable connections between semiconductor wafers.
Implementation Method 1
a plasma module configured to perform a plasma operation and a reduction operation to a surface of the semiconductor wafer to convert metal oxides on the surface of the semiconductor wafer to the metal
Data Source
AI summary
An apparatus for wafer bonding includes a transfer module and a plasma module. The transfer module is configured to transfer a semiconductor wafer. The plasma module is configured to apply a first type of plasma to perform a reduction operation upon a surface of the semiconductor wafer at a temperature within a predetermined temperature range to convert metal oxides on the surface of the semiconductor wafer to metal, and apply a second type of plasma to perform a plasma operation upon the surface of the semiconductor wafer at a room temperature outside the predetermined temperature range to activate a surface of the semiconductor wafer.