Liquid Discharge Head Substrate Bonding and Annealing
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Solution Overview
Problem
The existing methods for manufacturing liquid discharge head substrates face challenges in achieving consistent thickness of the insulating layer between the heat generation element and the conductive member, leading to suboptimal liquid discharge performance due to variations in heat dissipation, which affects the accuracy and quality of the liquid discharge.
Innovation Solution
A method involving the formation of a first substrate with a semiconductor element and a first wiring structure, and a second substrate with a liquid discharge element and a second wiring structure, where the two are bonded to ensure electrical connection, with the heat generation element formed on a protective film and annealed at a temperature above 400°C to improve flatness and alignment, allowing for precise control of the insulating layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the insulating layer thickness is increased, then heat dissipation decreases and liquid discharge amount increases, but manufacturing precision deteriorates due to difficulty in controlling thickness uniformly
Solution Approach 1:
The patent applies preliminary action by forming the insulating layer before planarization, establishing the initial thickness distribution that will be subsequently corrected. The CMP process then acts as a corrective action that removes material to achieve uniform thickness, transforming the non-uniform insulating layer into a uniform one while maintaining the desired thickness range for proper heat dissipation control.
Solution Approach 2:
The patent changes the physical state and properties of the insulating layer through CMP processing, transforming it from a non-uniform thickness state to a uniform thickness state. This parameter change in thickness uniformity directly affects heat dissipation characteristics, enabling precise control of liquid discharge amount by maintaining insulating layer thickness within the specified range of 100-300 nm.
2Reliability
If planarization is performed after each wiring layer formation, then wiring structure flatness improves, but upper wiring layer flatness deteriorates due to cumulative effects
Solution Approach 1:
The patent extracts the planarization step from the individual wiring layer formation process and applies it only to the insulating layer before heat generation element formation. This removal of redundant planarization steps from intermediate wiring layers simplifies the manufacturing process and prevents cumulative flatness degradation while maintaining necessary flatness for the critical heat generation element positioning.
Solution Approach 2:
The patent performs preliminary planarization of the insulating layer before forming the heat generation element, ensuring that the surface is sufficiently flat for precise element placement. This preliminary action on the insulating layer eliminates the need for subsequent planarization steps after wiring layer formation, preventing flatness degradation in upper layers.
3Quantity of substance
If insulating layer thickness varies across the wafer, then heat dissipation becomes non-uniform, but liquid discharge performance uniformity deteriorates
Solution Approach 1:
The patent implements feedback control through the CMP process, which continuously monitors and adjusts the planarization rate to achieve uniform thickness across the wafer. The CMP process provides real-time feedback on surface topography and adjusts polishing parameters accordingly, ensuring that the insulating layer thickness is uniformly controlled within the 100-300 nm range across the entire wafer surface, thereby maintaining consistent heat dissipation and liquid discharge performance.
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 enhances the flatness and uniformity of the insulating layer, improving the liquid discharge performance by stabilizing heat dissipation and reducing power consumption, thereby achieving better image quality and discharge accuracy.
Implementation Method 1
annealing at least one of the liquid discharge element and the protective film at a temperature not lower than 400°C before forming the second wiring structure
Data Source
Figure 1A~1B
Figure 2A~2E
Figure 3A~3E
AI summary
A method of manufacturing a liquid discharge head substrate is provided. The method includes forming a first substrate that includes a semiconductor element and a first wiring structure; forming a second substrate that includes a liquid discharge element and a second wiring structure; and bonding the first wiring structure and the second wiring structure such that the semiconductor element and the liquid discharge element are electrically connected to each other after the forming the first substrate and the second substrate.