Metal Buffer Layer for Analog Circuit Stress Management
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Solution Overview
Problem
The precision of electric characteristics in analog circuits is compromised due to non-uniform compressive stress generated during the mold packaging process of semiconductor devices, where resin with a filler is used, leading to variations and changes in circuit characteristics.
Innovation Solution
Incorporating a metal layer or metal interconnects as buffer layers above the analog circuit blocks to uniformize stress, reducing the non-uniformity of microstress transferred from the filler, thereby mitigating the impact on electric characteristics without requiring special materials or production methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resin with filler is used for mold packaging, then productivity and mechanical strength are improved, but non-uniform compressive stress is generated causing deterioration of electric characteristic precision
Solution Approach 1:
A stress relief layer is introduced as an intermediary between the filler-containing resin and the analog circuit block. This layer absorbs and redistributes the non-uniform compressive stress generated during mold packaging, preventing direct transmission of stress to the circuit elements. The stress relief layer acts as a buffer that decouples the harmful mechanical stress from the sensitive electronic components while allowing the resin to maintain its structural support function.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers with different mechanical properties: the filler-containing resin provides mechanical strength and dimensional stability, while the stress relief layer (with different elastic modulus and thermal expansion characteristics) absorbs mechanical stress. This composite approach allows simultaneous achievement of high productivity through resin packaging and high manufacturing precision through stress management.
2Stability of the object's composition
If filler particle size is increased to reduce stress concentration, then stress uniformity is improved, but manufacturing cost increases due to special material requirements
Solution Approach 1:
Rather than modifying the filler particles in the resin, the patent introduces a dedicated stress relief layer as an intermediary component. This layer is designed with specific mechanical properties to absorb stress, eliminating the need for expensive special filler materials or complex particle size control while achieving stress uniformity.
Solution Approach 2:
The patent changes the structural parameter of the packaging system by adding a layered structure with controlled thickness and material properties. The stress relief layer's thickness and elastic modulus are optimized to achieve stress uniformity without requiring changes to the filler material itself, thereby avoiding increased production costs associated with special materials.
3Stability of the object's composition
If metal layer with slits is used as stress relief structure, then stress uniformity is improved, but device complexity increases
Solution Approach 1:
The metal layer with slits serves as an intermediary stress management structure between the resin and the analog circuit. The slits allow the metal layer to expand and contract independently, absorbing thermal and mechanical stress while protecting the underlying circuit. This structured approach provides stress relief through a relatively simple geometric modification rather than complex multi-layer compositions.
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 effectively suppresses the lowering of precision and variation in electric characteristics, ensuring stable and precise performance of semiconductor devices during the mold packaging process.
Implementation Method 1
resin having a large coefficient of linear expansion shrinks on hardening during the forming process, thereby generating compressive stress on the surface and the inside of the IC
Implementation Method 2
With the piezoelectric effect due to this compressive stress, the electric characteristics of various devices non-uniformly change
Data Source
AI summary
A semiconductor device includes a semiconductor substrate, an analog circuit block including an active element arranged in the semiconductor substrate, a metal layer having a slit or a plurality of metal interconnects arranged in parallel, positioned above the analog circuit block, and a resin layer containing a filler, positioned above at least the metal layer or the plurality of metal interconnects. In the case of forming a semiconductor device by sealing a semiconductor chip with resin having a filler mixed therein, according to this semiconductor device, it is possible to suppress lowering of the level of precision of the electric characteristics of the analog circuit, and a variation in the characteristics or a change in the characteristics, in a mold packaging process, without using special materials or production methods.