Semiconductor Chip Stacking Adhesive Stress Control
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Solution Overview
Problem
In semiconductor device manufacturing, filler particles from the molding resin can damage the passivation film under the protective film due to mechanical stress during the stacking process, known as 'filler attack', which occurs when filler particles are pushed into gaps between semiconductor chips, causing mechanical damage.
Innovation Solution
Adjusting the modulus of elasticity of the adhesive layer, the sink amount of the adhesive layer, the thickness of the protective film, and the modulus of elasticity of the protective film to ensure that the calculated stress value 'y' remains 70 or less, as determined by the formula y=74.7−82.7a1+273.2a2−9882a3+65.8a4, where a1 is the logarithm of the adhesive layer's modulus, a2 is the sink amount, a3 is the protective film's thickness, and a4 is the logarithm of the protective film's modulus, thereby reducing the stress on the passivation film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filler particles are used in the molding resin to improve mechanical strength and electrical insulation, then the reliability of the semiconductor device is improved, but the filler particles can be pushed into gaps between semiconductor chips during stacking, causing mechanical damage to the passivation film
Solution Approach 1:
The adhesive layer is formed with predetermined properties (modulus of elasticity between 10-100 MPa, thickness 5-20 μm) before the stacking process to prevent filler attack. This preliminary preparation of the adhesive layer with specific mechanical properties creates a buffer that absorbs stress and prevents filler particles from reaching the passivation film during subsequent stacking operations.
Solution Approach 2:
The invention changes the physical parameters of the adhesive layer, specifically controlling the modulus of elasticity to be between 10-100 MPa and thickness to be 5-20 μm. These parameter adjustments optimize the adhesive layer's ability to absorb stress and prevent filler particles from penetrating to the passivation film, thereby resolving the contradiction between using filler particles for reliability and preventing filler attack.
2Ease of manufacture
If a liquid resin adhesive layer is used to bond semiconductor chips, then the ease of manufacture is improved, but the outer edge part of the adhesive layer can set back toward the inner side during wafer separation, creating gaps that lead to filler attack
Solution Approach 1:
The invention controls specific parameters of the adhesive layer including modulus of elasticity (10-100 MPa) and thickness (5-20 μm) to prevent the outer edge from setting back during wafer separation. By optimizing these parameters, the adhesive layer maintains its shape and position precision while still being formed as a liquid resin, thus resolving the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The adhesive layer is designed with specific mechanical properties (modulus of elasticity 10-100 MPa) that provide cushioning support during the wafer separation process. This beforehand cushioning prevents the outer edge from setting back toward the inner side, maintaining manufacturing precision while allowing the use of liquid resin for ease of manufacture.
3Strength
If the modulus of elasticity of the adhesive layer is increased to reduce deformation, then the strength is improved, but the stress on the passivation film increases, making it more susceptible to filler attack
Solution Approach 1:
The invention optimizes the modulus of elasticity of the adhesive layer to be between 10-100 MPa, which is a specific parameter range that balances strength and stress transmission. This parameter change ensures the adhesive layer has sufficient strength for bonding while simultaneously limiting the stress transmitted to the passivation film, preventing filler attack.
Solution Approach 2:
The adhesive layer is designed with specific local properties (modulus of elasticity 10-100 MPa, thickness 5-20 μm) that are optimized for the specific function of stress absorption. This local quality optimization allows the adhesive layer to provide sufficient bonding strength while locally absorbing stress to protect the passivation film from filler attack.
Data Source
AI summary
According to one embodiment, a manufacturing method of a semiconductor device is disclosed. The method includes: stacking and adhering a second semiconductor chip on a first semiconductor chip via an adhesive layer; adjusting at least one of an elasticity modulus of the adhesive layer, a sink amount of the adhesive layer, a thickness of a protective film at a surface of the first chip, and an elasticity modulus of the protective film such that “y” in a following formula is 70 or less; and sealing the chips by a molding resin with filler particles.y=74.7−82.7a1+273.2a2−9882a3+65.8a4a1: a logarithm of the modulus of elasticity [MPa] of the adhesive layera2: the sink amount [mm] of the adhesive layera3: the thickness [mm] of the protective filma4: a logarithm of the modulus of elasticity [MPa] of the protective film.