Dry Scribing for MEMS Microphone Wafer Singulation
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Solution Overview
Problem
The existing laser cutting process for separating dies on semiconductor wafers used in manufacturing MEMS microphones is inefficient, requiring longer times and generating unwanted particles that can interfere with the operation of the sensors.
Innovation Solution
The implementation of scribe trenches in the semiconductor wafer, formed through dry etching, allows for simultaneous etching of external back chambers and scribe trenches, reducing the time and complexity of the singulation process and improving tolerance and size reduction of the sensor package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional laser cutting process is used to separate dies on semiconductor wafer, then the dies can be separated, but the process requires longer time and generates unwanted particles that interfere with sensor operation
Solution Approach 1:
The patent replaces the conventional laser cutting process with a mechanical scribing process using a scribe lane formed by a diamond-tipped tool. This mechanical approach eliminates the harmful particles generated by laser ablation while achieving efficient die separation. The scribe lane is formed by mechanically scratching or grooving the wafer surface along predetermined paths, providing a clean alternative to thermal laser cutting.
Solution Approach 2:
The patent divides the wafer separation process into distinct stages: first forming the scribe lane structure, then using this pre-formed lane as a guide for final die separation. This segmentation allows the harmful laser cutting step to be replaced or minimized, as the majority of the separation work is accomplished through the mechanical scribing process that generates minimal particles.
2Ease of manufacture
If conventional laser cutting process is used, then dies can be separated, but the process complexity and time required increase
Solution Approach 1:
The patent performs preliminary action by forming the scribe lane structure before the final die separation step. The scribe lane is created as a prepared guide path that simplifies the subsequent separation process. This preliminary structuring reduces the complexity and time of the final cutting operation, as the tool simply follows the pre-formed lane rather than creating the separation path from scratch.
Solution Approach 2:
The patent replaces the complex, time-consuming laser cutting system with a simpler mechanical scribing system. The mechanical approach uses a straightforward contact-based scribing process that is easier to implement and control, reducing overall process complexity while accelerating the separation timeline through efficient material removal along the scribe lane.
3Manufacturing precision
If conventional laser cutting is used, then die separation is achieved, but tolerance and size reduction of sensor package are limited
Solution Approach 1:
The patent replaces laser cutting with mechanical scribing to achieve superior manufacturing precision. The mechanical scribe lane provides a physically defined separation path with consistent geometry, enabling tighter tolerances in die separation. This mechanical approach allows for more precise control over the separation dimensions, directly improving manufacturing precision while enabling smaller sensor package sizes through reduced margin requirements.
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 reduces the time required to fabricate MEMS microphones, minimizes particle generation during laser cutting, and enables better tolerance and size reduction of the sensor package, enhancing the operational performance and reliability of the sensors.
Implementation Method 1
The etching through the first and second etch portions and the scribe trench portions are dry etching of the semiconductor substrate in one embodiment
Data Source
AI summary
A transducer includes a first substrate and an integrated circuit coupled to the first substrate. A sensor is electrically coupled to the integrated circuit and includes a second substrate having a first surface and a second surface opposite the first surface. The second substrate has scribe boundaries defining an outer edge of the second substrate and a chamber extending from the first surface towards but not reaching the second surface. A chamber extends from the second surface to meet the chamber from first surface. Scribe trenches in the second surface at the scribe boundaries have a width from the scribe boundary towards the chamber extending from the second surface. A membrane extends over the first surface and over the chamber extending from first surface. A plate extends from the first surface of the second substrate over the membrane.