Split-Gate Power Device Lateral Recess Etching
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Solution Overview
Problem
The existing methods for manufacturing split-gate power devices face challenges such as difficulty in etching control gate contact holes due to narrow lateral widths of control gates and instability in forming insulating film dielectric layers, leading to low yield and process control issues.
Innovation Solution
The method involves forming lateral recesses in the control gate groove, depositing a conductive film to fill these recesses, and using the insulating film as a mask for precise etching of control gates and split-gate grooves, followed by additional insulating and conductive film deposition to enhance process stability and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the control gate lateral width is made small to reduce parasitic capacitance, then the switching speed is improved, but the difficulty in etching control gate contact holes increases
Solution Approach 1:
The patent forms lateral recesses in the control gate groove before depositing the conductive film. This preliminary action creates a broader base structure that supports the formation of control gate contact holes, making the etching process easier even when the control gate lateral width is small. The recesses provide additional space for contact hole formation without increasing the final control gate width, thus resolving the contradiction between fast switching speed and ease of manufacturing contact holes.
2Ease of manufacture
If the etching-back method is used to form insulating film dielectric layers, then the control gate groove can be formed, but parts of the insulating film dielectric layers above the control gates are easily etched, making the control gates hard to protect
Solution Approach 1:
The patent segments the insulating film formation process into multiple steps: first forming the insulating film dielectric layers, then selectively removing portions above the control gates through targeted etching, and finally forming protective structures. This segmentation allows precise control over where insulating material remains and where it is removed, ensuring control gates are protected only where needed while maintaining the ability to form the control gate groove effectively.
Solution Approach 2:
The patent introduces lateral recesses as an intermediary structure between the control gate groove and the insulating film dielectric layers. These recesses serve as a buffer zone that prevents direct etching damage to the control gates while still allowing the insulating film to be formed and patterned correctly. The recesses act as a mediator that decouples the conflicting requirements of groove formation and gate protection.
3Device complexity
If the existing typical method is used to manufacture split-gate power device, then the basic structure can be formed, but the manufacturing process is hard to control and the yield is low
Solution Approach 1:
The patent performs preliminary actions by forming lateral recesses in the control gate groove before depositing conductive films and forming other structures. This advance preparation creates a more robust foundation for subsequent processing steps, reducing variability and improving process control. The recesses are formed in advance to ensure proper alignment and dimensions, which directly contributes to higher yield by preventing defects in later stages.
Solution Approach 2:
The patent changes key geometric parameters of the control gate groove by introducing lateral recesses, which modify the groove profile from a simple trench to a more complex shape with widened base. This parameter change affects multiple downstream process parameters, including conductive film deposition thickness, etching selectivity, and alignment tolerances, thereby improving overall process controllability and reducing yield loss.
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 simplifies the manufacturing process, improves yield, and reduces the complexity of forming control gate electrode contact holes, making the process more reliable and easier to control, particularly suitable for 25V-200V semiconductor power devices.
Implementation Method 1
depositing a first conductive film, the first conductive film at least filling the lateral recesses at the two sides of the control gate groove and below the first insulating film
Implementation Method 2
depositing and etching-back a third insulating film to form third insulating film dielectric layers on side walls of the control gates
Implementation Method 3
depositing and etching-back a second conductive film to form a split-gate in the split-gate groove
Data Source
AI summary
The present invention relates to the field of manufacturing technologies of semiconductor power devices, and more particularly to a method for manufacturing a split-gate power device. In the method for manufacturing a split-gate power device according to the present invention, lateral etching is added to form lateral recesses of a control gate groove below a first insulating film in a process of forming the control gate groove by etching, and therefore, after a first conductive film is deposited, the first conductive film can be directly etched by using the first insulating film as a mask to form control gates. The technical process of the present invention is simplified, reliable and easy to control, and can greatly improve the yield of the split-gate power device. The present invention is particularly suitable for the manufacture of 25V-200V semiconductor power devices.