Through-Hole Electrode for Semiconductor Thermal Stress
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Solution Overview
Problem
Conventional semiconductor devices face challenges with connection reliability due to thermal stress, particularly when using solder bumps or wire bonding, which can lead to cracks and reduced reliability, and existing solutions like interposers do not adequately address bonding strength and thermal expansion mismatches between semiconductor elements and mounting boards.
Innovation Solution
The semiconductor device incorporates a through-hole electrode that passes through the semiconductor substrate, extending to the second main surface and jutting out, which is electrically connected to an active region and embedded in bonding materials like solder, enhancing bonding strength and connection reliability against thermal stress by reducing thermal stress through increased surface contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If solder bumps are used to connect the semiconductor element and mounting board, then connection area is minimized, but thermal stress causes cracks in the solder bumps reducing connection reliability
Solution Approach 1:
The patent introduces an interposer substrate as an intermediary component between the semiconductor element and mounting board. This interposer has a thermal expansion coefficient that matches the semiconductor element, serving as a thermal bridge that reduces thermal stress on the connecting electrodes while maintaining compact mounting area.
Solution Approach 2:
The patent changes the thermal expansion parameter by selecting materials with specific thermal coefficients. The interposer is made of a material whose thermal expansion coefficient is closer to that of the semiconductor element than the mounting board is, thereby reducing differential thermal stress during temperature variations.
2Reliability
If wire bonding is used to connect pad electrodes, then connection reliability is maintained, but additional space is required around the semiconductor device
Solution Approach 1:
The interposer substrate acts as a mediator that enables direct electrical connection between the semiconductor element and mounting board through embedded connecting electrodes, eliminating the need for wire bonding and the associated additional space requirements.
3Reliability
If an interposer with matching thermal coefficient is used, then thermal stress is reduced, but bonding strength between connecting electrodes and semiconductor electrodes is insufficient
Solution Approach 1:
The patent transitions from surface-level electrode connections to three-dimensional embedded connections. The connecting electrodes extend through the interposer substrate in the thickness direction, creating vertical bonding paths that increase contact area and bonding strength while maintaining thermal expansion matching.
Solution Approach 2:
The connecting electrodes are nested within the interposer substrate, with electrode portions embedded in the thickness direction of the interposer. This nested configuration allows the electrodes to be surrounded by the interposer material, increasing bonding interface area and mechanical strength.
4Ease of manufacture
If connecting electrodes are attached to flat surfaces, then manufacturing is simplified, but thermal stress causes separation at the interface
Solution Approach 1:
The patent moves from two-dimensional surface attachment to three-dimensional embedded attachment. The connecting electrodes extend through the interposer substrate in the thickness direction, creating vertical bonding interfaces that are more resistant to thermal stress-induced separation while maintaining manufacturing feasibility.
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 through-hole electrode design improves connection reliability by increasing bonding strength and reducing thermal stress effects, ensuring stable connections even under temperature changes, thus enhancing the overall reliability of semiconductor devices.
Implementation Method 1
The mounting board has a thermal coefficient different from that of the semiconductor element. Hence, with a temperature change, thermal stress is applied to the solder bumps connecting the mounting board and the semiconductor element.
Implementation Method 2
By mounting the semiconductor device face down on the mounting board, an area necessary for mounting can be made equal to a size of the device. However, the mounting board has a thermal coefficient different from that of the semiconductor element. Hence, with a temperature change, thermal stress is applied to the solder bumps connecting the mounting board and the semiconductor element.
Data Source
AI summary
In the semiconductor device of the present invention, an active region is formed in an upper surface of a semiconductor substrate, and is surrounded by a trench filled with an oxide. A through-hole electrode electrically connected to the active region extends from the upper surface of the semiconductor substrate to a lower surface thereof. A bottom end of the through-hole electrode juts out of an insulating film covering the lower surface of the semiconductor substrate. Accordingly, a jutting portion of the through-hole electrode is embedded in the bonding material when the semiconductor device is mounted on a mounting board, and thus the connection reliability therebetween is improved.