BS IEC 62047-31:2019 pdf download.Semiconductor devices - Micro-electromechanical devices
1 Scope
This part of IEC 62047 specifies a four-point bending test method for measuring interfacial adhesion energy of the weakest interface in the layered micro-electromechanical systems (MEMS) based on the concept of fracture mechanics. In a variety of MEMS devices, there are many layered material interfaces, and their adhesion energies are critical to the reliability of the MEMS devices. The four-point bending test utilizes a pure bending moment applied to a test piece of layered MEMS device, and the interfacial adhesion energy is measured from the critical bending moment for the steady state cracking in the weakest interface. This test method applies to MEMS devices with thin film layers deposited on semiconductor substrates.
The total thickness of the thin film layers should be 100 times less than the thickness of a supporting substrate (typically a silicon wafer piece).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
There are no normative references in this document.
4.1 General
The test piece for the layered MEMS materials shall be prepared using the same fabrication process that applies to actual MEMS devices. Machining of the test piece shall be performed to prevent formation of unintended cracks or flaws and delamination in the test piece.
5.1 Test principle
The test is performed by applying a pure bending moment to a test piece with a layered material interface as shown in Figure 1. The test consists of two steps: the first is the introduction of an interface crack between two layered materials with the weakest interface. By gradually increasing the four-point bending load applied to the test piece, a crack is initiated from a machined pre-crack. The initiated crack extends in a direction of thickness and then becomes an interface crack when it touches the weakest interface. When the interface crack is formed, the bending load is relaxed. The second step is the extension of the interface crack. By reloading the bending load, the energy release rate at the tip of the interface crack increases, and the interface crack starts to extend. The energy release rate of an interface crack is independent of the crack length when the test piece is under pure bending. For this test method, it is unnecessary to measure the length of the interface crack.BS IEC 62047-31 pdf download.