Semiconductor Flip-Chip Bonding with Segmented Pressing Members
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Solution Overview
Problem
The flip chip package assembly method is hindered by the need for a pressing member to reach high temperatures for metal bonding, leading to longer manufacturing times and productivity degradation due to the time required for heating and cooling, as well as issues with adhesive sticking to the pressing member and dicing tape, resulting in defects and reduced productivity.
Innovation Solution
A method involving separate pressing members for temporary and main press-bonding, where the temporary press-bonding is performed at a temperature lower than the melting point of the metal, and the main press-bonding at a temperature equal to or higher than the melting point, using a pair of facing pressing members to connect semiconductor chips and substrates with an adhesive layer, and employing an adhesive with a melt viscosity of 7000 Pa·s or less to minimize void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressing member is heated to high temperature for metal bonding, then connection reliability is improved, but manufacturing time increases due to heating and cooling cycles
Solution Approach 1:
The pressing member is divided into two separate members: a first pressing member for temporary press-bonding at lower temperature, and a second pressing member for main press-bonding at high temperature. This segmentation allows each pressing member to be optimized for its specific function, eliminating the need to cool and reheat a single pressing member, thus reducing manufacturing time while maintaining connection reliability
Solution Approach 2:
The first pressing member performs temporary press-bonding at lower temperature before the main press-bonding process. This preliminary action secures the chips in position and prevents displacement during subsequent high-temperature processing, ensuring connection reliability without requiring the pressing member to be repeatedly heated and cooled
2Reliability
If the pressing member is heated to high temperature for metal bonding, then metallic bond is formed, but adhesive sticks to the pressing member causing defects
Solution Approach 1:
The pressing process is segmented into two stages using two separate pressing members: temporary press-bonding at lower temperature and main press-bonding at high temperature. The first pressing member operates at lower temperature where adhesive sticking is minimized, while the second pressing member operates at high temperature for metallic bond formation without adhesive contamination
Solution Approach 2:
The temperature parameter is changed between the two pressing members: the first pressing member uses lower temperature to avoid adhesive sticking, while the second pressing member uses high temperature (equal to or higher than metal melting point) to form metallic bonds. This parameter change resolves the conflict between adhesive sticking and bond formation
3Device complexity
If a single pressing member is used for both temporary and main press-bonding, then device complexity is reduced, but productivity decreases due to temperature cycling
Solution Approach 1:
The pressing function is segmented into two separate pressing members specialized for temporary and main press-bonding respectively. Although this increases device complexity, it eliminates the time-consuming temperature cycling of a single pressing member, thereby significantly improving manufacturing productivity through parallel optimization of both pressing stages
Solution Approach 2:
The first pressing member performs preliminary temporary press-bonding at lower temperature, preparing the workpiece for the main press-bonding process. This preliminary action allows the second pressing member to operate continuously at high temperature without waiting for cooling cycles, improving overall productivity despite increased device complexity
4Productivity
If heating time is reduced for high productivity, then manufacturing time decreases, but uniform pressure distribution becomes difficult to achieve
Solution Approach 1:
The pressing members are designed with large-area contact surfaces that provide uniform pressure distribution across the workpiece. This local quality feature ensures that even with reduced heating time, the pressure is evenly distributed, allowing rapid heating while maintaining manufacturing precision and avoiding localized defects
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 significantly reduces the time needed for heating and cooling, allowing for the rapid production of reliable semiconductor devices with improved connection reliability and reduced voids, while maintaining high productivity by using a large-area press-bonding head and a sheet for collective connection with specific elastic properties to ensure uniform pressure and prevent unevenness.
Implementation Method 1
heating and pressuring a laminate having: the semiconductor chip; the substrate, the another semiconductor chip or a semiconductor wafer including a portion corresponding to the another semiconductor chip; and the adhesive layer disposed therebetween
Implementation Method 2
heating and pressuring the laminate by interposing the laminate with a pair of facing pressing members for main press-bonding separately prepared from the pressing members for temporary press-bonding, to thereby electrically connect the connection portion of the semiconductor chip and the connection portion of the substrate or the another semiconductor chip by metal bonding. At least one of the pair of pressing members for main press-bonding is heated to a temperature equal to or higher than at least one melting point of a melting point of the metal material forming the surface of the connection portion of the semiconductor chip and a melting point of the metal material forming the surface of the connection portion of the substrate or the another semiconductor chip
Data Source
AI summary
Disclosed is a method for manufacturing a semiconductor device which includes: a semiconductor chip; a substrate and/or another semiconductor chip; and an adhesive layer interposed therebetween. This method comprises the steps of: heating and pressuring a laminate having: the semiconductor chip; the substrate; the another semiconductor chip or a semiconductor wafer; and the adhesive layer by interposing the laminate with pressing members for temporary press-bonding to thereby temporarily press-bond the substrate and the another semiconductor chip or the semiconductor wafer to the semiconductor chip; and heating and pressuring the laminate by interposing the laminate with pressing members for main press-bonding, which are separately prepared from the pressing members for temporary press-bonding, to thereby electrically connect a connection portion of the semiconductor chip and a connection portion of the substrate or the another semiconductor chip.