Semiconductor Solder Bump Joining Structure with Low Resistance
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Solution Overview
Problem
The resistance at the junction of connection pads and terminals in semiconductor devices increases due to the formation of intermetallic compound layers and segregation of Bi during high-temperature reliability tests, affecting the reliability and durability of the joints.
Innovation Solution
A semiconductor device design featuring intermetallic compound layers of Cu3Sn or Ni3Sn4 at the boundaries between connection pads and joining members, and Cu6Sn5 or (Cu,Ni)6Sn5 between these layers, with Bi dispersed within, preventing Bi layer formation and reducing resistance changes under high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Sn-Bi solder bump is used to join connection pad and connection terminal, then the joining member has low melting point and ease of manufacture, but the resistance at the joint increases during high-temperature reliability tests due to intermetallic compound formation and Bi segregation
Solution Approach 1:
The joining member is segmented into multiple functional layers: a Cu3Sn intermetallic compound layer at the connection pad boundary, a Cu6Sn5 intermetallic compound layer in the middle, and a Ni3Sn4 intermetallic compound layer at the connection terminal boundary. This segmentation prevents Bi segregation and controls intermetallic compound formation to maintain low resistance during high-temperature operation.
Solution Approach 2:
The joining member uses a composite structure combining multiple intermetallic compounds (Cu3Sn, Cu6Sn5, Ni3Sn4) with controlled Bi distribution. This composite material approach leverages the advantages of each intermetallic compound to achieve both manufacturability and reliability under high-temperature conditions.
2Strength
If intermetallic compound layers form at the boundary between connection pad and solder bump, then the joining strength increases, but the resistance at the joint increases due to Bi segregation forming high-resistance Bi layers
Solution Approach 1:
Different regions of the joining member have different local compositions: Cu3Sn intermetallic compound layer at the connection pad boundary for strong bonding, Cu6Sn5 intermetallic compound layer in the middle section for mechanical strength, and Ni3Sn4 intermetallic compound layer at the connection terminal boundary. This local quality control prevents Bi segregation while maintaining joining strength.
Solution Approach 2:
The invention changes the compositional parameters and structural configuration of the joining member by forming specific intermetallic compound layers with controlled thicknesses and distributions. This parameter optimization ensures strong joining while preventing high-resistance Bi layer formation during high-temperature operation.
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 configuration enhances the heat resistance and connection reliability of the semiconductor device by limiting resistance increases and suppressing Kirkendall void growth, thereby improving the durability of the joints during high-temperature exposure.
Implementation Method 1
a first intermetallic compound layer composed of an intermetallic compound of Cu3Sn or Ni3Sn4 and formed at a boundary between the connection pad and the joining member, a second intermetallic compound layer composed of an intermetallic compound of Cu3Sn or Ni3Sn4 and formed at a boundary between the connection terminal and the joining member, a third intermetallic compound layer composed of an intermetallic compound of Cu6Sn5 or (Cu,Ni)6Sn5 and formed between the first intermetallic compound layer and the second intermetallic compound layer
Implementation Method 2
with Bi dispersed within, preventing Bi layer formation and reducing resistance changes under high temperatures
Data Source
AI summary
A semiconductor device is provided with a wiring substrate including a connection pad, a joining member joined with the connection pad, and a semiconductor chip including a connection terminal electrically connected to the connection pad via the joining member. The joining member consists of a first intermetallic compound layer formed at a boundary between the connection pad and the joining member, a second intermetallic compound layer formed at a boundary between the connection terminal and the joining member, a third intermetallic compound layer composed of an intermetallic compound of Cu6Sn5 or (Cu,Ni)6Sn5 and formed between the first intermetallic compound layer and the second intermetallic compound layer, and discrete metal grains, each being composed of a simple substance of Bi, in the third intermetallic compound layer. Surfaces of each of the metal grains are completely covered by the third intermetallic compound layer so that the metal grains do not form a layer.