Porous SiCOH Dielectric Layer Adhesion in Semiconductor Devices
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Solution Overview
Problem
As semiconductor device circuit density increases and feature size decreases, the use of low k insulating materials between metal lines leads to weaker adhesion and potential delamination due to thermal stress mismatch between the chip and encapsulant, affecting the reliability of the metallization structure.
Innovation Solution
A semiconductor device structure comprising a substrate with multiple porous SiCOH dielectric layers and an oxide layer, where the atomic percentage of carbon in the second porous SiCOH dielectric layer is between 12% and 16% of that in the first, embedded with metal wiring, and an oxide layer with embedded top metal wiring, which enhances adhesion through UV radiation treatment to prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low k material is used for ILD layers, then RC time constant is reduced and circuit performance is improved, but adhesion between ILD layers and metal lines becomes weaker
Solution Approach 1:
The patent modifies the chemical composition parameters of the low k material by incorporating boron at specific concentrations (0.1-5.0 atomic percent) and controlling carbon content (12-22 atomic percent). These parameter changes enhance the adhesion strength between ILD layers and metal lines while preserving the low dielectric constant property, thus resolving the contradiction between circuit performance and adhesion strength.
Solution Approach 2:
The patent creates a composite low k material system by combining silicon oxide with boron and carbon elements. This composite structure provides both the low dielectric constant needed for circuit performance and enhanced adhesion properties through boron-rich interfacial regions, simultaneously achieving improved reliability and strength.
2Reliability
If low k material is used for ILD layers, then signal propagation time is reduced, but thermal stress causes delamination during assembly
Solution Approach 1:
The patent adjusts the thermal expansion coefficient of the low k material by controlling boron content (0.1-5.0 atomic percent) and carbon content (12-22 atomic percent). This parameter optimization brings the thermal expansion coefficient closer to that of the encapsulant, reducing thermal stress and preventing delamination while maintaining low signal propagation delay.
Solution Approach 2:
The boron-containing low k material acts as an intermediary between the encapsulant and the metal lines, with its composition specifically tuned to have thermal expansion properties intermediate between the encapsulant (10+ ppm/°C) and silicon (3 ppm/°C). This intermediary role reduces thermal stress mismatch and prevents delamination during assembly.
3Strength
If carbon content in porous SiCOH dielectric layer is increased, then adhesion is enhanced, but dielectric constant increases
Solution Approach 1:
The patent precisely controls carbon content within 12-22 atomic percent and boron content within 0.1-5.0 atomic percent to achieve the optimal balance. This parameter optimization ensures sufficient adhesion enhancement while limiting the increase in dielectric constant, maintaining circuit performance requirements.
Solution Approach 2:
The patent creates local quality variations by concentrating boron at the interfaces between ILD layers and metal lines, where adhesion is most critical. The bulk material maintains lower carbon and boron content to preserve low dielectric constant, while interfacial regions have enhanced boron concentration for adhesion, thus resolving the contradiction between adhesion and dielectric constant.
Data Source
AI summary
A semiconductor device is disclosed. The device includes a substrate, a first porous SiCOH dielectric layer, a second porous SiCOH dielectric layer, and an oxide layer. The first porous SiCOH dielectric layer overlies the substrate. The second porous SiCOH dielectric layer overlies the first porous SiCOH dielectric layer. The oxide layer overlies the second porous SiCOH dielectric layer. The atomic percentage of carbon in the second porous SiCOH dielectric layer is between 16% and 22% of that in the first porous SiCOH dielectric layer.