Silicon Dioxide Adhesion Layer for Dielectric Substrates
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Solution Overview
Problem
The adhesion of dielectric layers to semiconductor substrates is compromised due to the presence of unwanted polymeric by-products and surface contamination during processes like TSV and Via Reveal Applications, requiring multiple cleaning steps that can leave residues and affect the vacuum properties of bonding materials.
Innovation Solution
A method involving the direct deposition of a silicon dioxide adhesion layer onto the semiconductor substrate using a low oxygen flow or no oxygen PECVD process, followed by the deposition of a dielectric layer, which improves adhesion by using a low RF frequency and specific gas flow rates, pressures, and RF power configurations to create an optimal plasma environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple cleaning steps (O2 ashing and EKC polymer strip) are performed to remove polymeric by-products, then the polymeric by-products are removed from the silicon surface, but residues remain on the silicon surface which compromise adhesion of subsequently deposited dielectric layers
Solution Approach 1:
The patent applies preliminary action by depositing a silicon dioxide adhesion layer directly onto the silicon substrate surface before depositing the dielectric layer. This adhesion layer is deposited using a PECVD process with controlled oxygen flow rate (250 sccm or less), creating a surface that ensures adequate adhesion even when the underlying silicon surface contains residues from cleaning processes. The adhesion layer acts as a buffer that prevents residue-related adhesion failures.
2Reliability
If outgassing is performed prior to CVD deposition to address unstable vacuum properties of bonding adhesive, then vacuum properties are improved, but outgas by-products contaminate the silicon surface which compromises adhesion of subsequently deposited dielectric layers
Solution Approach 1:
The patent uses the silicon dioxide adhesion layer as an intermediary between the potentially contaminated silicon substrate and the dielectric layer. This intermediate layer is deposited in-situ using PECVD with controlled oxygen flow, creating a fresh surface that ensures adequate adhesion without being affected by outgas by-products or other surface contaminants present on the silicon substrate.
3Productivity
If conventional PECVD processes are used to deposit dielectric layers on contaminated surfaces, then deposition can proceed, but adhesion of the dielectric layer is compromised due to surface contamination
Solution Approach 1:
The patent changes the oxygen flow rate parameter in the PECVD process to 250 sccm or less during adhesion layer deposition. This parameter change creates a controlled atmosphere that allows the formation of a high-quality silicon dioxide adhesion layer even on contaminated surfaces. The reduced oxygen flow rate prevents excessive oxidation of surface contaminants while still enabling formation of the adhesion-promoting silicon dioxide layer.
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 enhances the adhesion and electrical characteristics of dielectric layers, reducing leakage current and maximizing breakdown voltage, while minimizing moisture content and carbon incorporation, resulting in improved film stability and adhesion even on contaminated surfaces.
Implementation Method 1
depositing a silicon dioxide adhesion layer directly onto the silicon substrate by a first Plasma Enhanced Chemical Vapour Deposition (PECVD) process
Implementation Method 2
The polymer by-product needs to be removed before any isolation layers are deposited. One reason for this is that the presence of polymeric by-product compromises the adhesion of subsequently deposited dielectric layers.
Data Source
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AI summary
According to the invention there is provided a method of improving adhesion between a semiconductor substrate and a dielectric layer comprising the steps of: depositing a silicon dioxide adhesion layer onto the semiconductor substrate by a first plasma enhanced chemical vapor deposition (PECVD) process; and depositing the dielectric layer onto the adhesion layer by a second PECVD process; in which the first PECVD process is performed in a gaseous atmosphere comprising tetraethyl orthosilicate (TEOS) either in the absence of O2 or with O2 introduced into the process at a flow rate of 250sccm or less.