Exposed Layer Activation Using a Sacrificial Fluorinated Plasma Layer
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Solution Overview
Problem
Existing methods for direct substrate bonding in microelectronic devices face limitations in bonding energy and etching of the exposed layer during activation plasma treatment, particularly when using fluorinated gases like CF4 or SF6.
Innovation Solution
A method involving the deposition of a layer with formula SiaYbXc, where X is fluorine or chlorine and Y is oxygen or nitrogen, followed by an activation plasma treatment that consumes the layer partially or fully, reducing its density to minimize etching and enhance bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fluorinated gas is injected in oxygen-based activation plasma to increase bonding energy, then bonding energy between substrates is improved, but etching of the exposed layer occurs
Solution Approach 1:
A fluorinated layer is deposited on the exposed layer before plasma treatment to protect it during activation. The layer is deposited in advance with controlled parameters (low density, specific thickness) so that it can be partially consumed by subsequent plasma treatment without exposing the underlying layer to harmful etching effects
Solution Approach 2:
The fluorinated layer acts as an intermediary between the plasma treatment and the exposed layer. It absorbs the harmful etching effects of the plasma while allowing the desired activation and bonding energy improvement to occur. The layer is designed to be partially consumed during plasma treatment, maintaining its protective function while enabling surface activation
2Quantity of substance
If conventional PECVD is used to deposit fluorinated layer, then layer formation is achieved, but layer density is too high to be consumed by activation plasma
Solution Approach 1:
Deposition parameters are modified to control layer density and thickness. By adjusting PECVD parameters (power, pressure, gas flow rates, temperature), a layer with optimal density is formed that allows partial consumption during plasma treatment. The layer thickness is also controlled to ensure it serves as a sacrificial protective layer rather than a permanent coating
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 the bonding interface by chemically modifying the exposed layer without deteriorating the assembly properties, enhancing bonding energy and reducing etching effects.
Implementation Method 1
a deposition, on the exposed layer, of a layer based on a material of formula SiaYbXc... Typically, the layers deposited in the deposition reactor, for example by PECVD
Implementation Method 2
a treatment of the layer SiaYbXc by an activation plasma based on at least one from among oxygen and nitrogen... it is possible to remove this layer at least partially by the activation plasma
Data Source
AI summary
A method for activating an exposed layer of a structure including a provision of a structure including an exposed layer, a deposition of a layer based on a material of formula SiaYbXc, with X chosen from among fluorine F and chlorine Cl, and Y chosen from among oxygen O and nitrogen N, a, b and c being non-zero positive integers, a treatment of the layer SiaYbXc by an activation plasma based on at least one from among oxygen and nitrogen, the parameters of the deposition of the layer SiaYbXc being chosen so as to obtain a sufficiently low material density such that the layer SiaYbXc is at least partially consumed by the activation plasma.