Semiconductor Die Singulation via Reactive Ion Etching
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Solution Overview
Problem
Current methods for singulating semiconductor die from wafers are inefficient, consuming significant time and wafer space due to wide scribe lines, and often result in non-uniform separation and reduced die strength.
Innovation Solution
A method involving the formation of narrow singulation lines through a semiconductor wafer using a combination of etching processes, including isotropic and anisotropic reactive ion etching, to efficiently separate die while minimizing wafer consumption and preserving die strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional scribing or dicing methods are used to singulate die from wafers, then die can be separated from the wafer, but the scribe line width is large (about 150 microns) which consumes significant wafer space and reduces the number of die per wafer
Solution Approach 1:
The patent replaces traditional mechanical scribing/dicing methods with a chemical etching process using reactive ion etching (RIE). Instead of using a physical cutting wheel that requires wide scribe lines for tool alignment and width, the invention uses patterned photoresist masks and plasma etching to define and cut narrow singulation lines chemically, achieving much narrower line widths and higher die density per wafer.
Solution Approach 2:
The invention changes the fundamental parameter of scribe line width by transitioning from mechanical cutting (150 microns) to chemical etching with precisely controlled photoresist patterns. The etching process parameters (plasma power, gas flow, etch time) are optimized to achieve narrow, uniform singulation lines that maximize the number of die that can be placed on each wafer.
2Productivity
If traditional scribing methods are used to singulate die from wafers, then die can be separated from the wafer, but the process time is very long (over one hour) which reduces manufacturing throughput
Solution Approach 1:
The patent replaces the slow mechanical scribing process with a faster chemical etching process. The reactive ion etching can complete singulation of an entire wafer in a matter of minutes rather than over an hour, dramatically improving manufacturing throughput and reducing the time loss associated with the singulation operation.
Solution Approach 2:
The etching process can be performed continuously across the entire wafer surface in a single operation, whereas mechanical scribing must sequentially traverse the wafer. The chemical process acts simultaneously on all exposed areas, maintaining continuous useful action and significantly reducing total process time.
3Strength
If laser scribing is used to singulate die from wafers, then die can be separated from the wafer, but the laser melts the crystalline structure along the die edge which decreases die strength and causes non-uniform separation
Solution Approach 1:
The patent replaces laser scribing with chemical reactive ion etching. The chemical process cleanly removes material without the thermal effects that cause melting and crystalline structure damage. This results in sharp, clean edges that maintain die strength and provide uniform separation, eliminating the harmful thermal effects of laser processing.
Solution Approach 2:
The invention changes the energy delivery mechanism from thermal (laser) to chemical (plasma etching). By using reactive ions and chemical reactions rather than concentrated thermal energy, the process achieves precise material removal without melting or damaging the die crystalline structure, preserving die strength and ensuring uniform singulation.
4Ease of manufacture
If traditional scribing methods are used to singulate die from wafers, then die can be separated from the wafer, but the process requires expensive equipment and protective equipment for operators in the case of laser scribing
Solution Approach 1:
The patent replaces expensive laser scribing equipment with standard semiconductor fabrication equipment (photoresist coating, patterning, and reactive ion etching tools). These are conventional processes already present in semiconductor manufacturing facilities, eliminating the need for specialized and expensive laser systems while also reducing safety requirements compared to high-power laser operations.
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 increases the number of die per wafer, achieves uniform singulation, reduces processing time, and narrows the scribe line width, thereby enhancing manufacturing throughput and die strength compared to traditional methods.
Implementation Method 1
A method involves the formation of narrow singulation lines through a semiconductor wafer using a combination of etching processes, including isotropic and anisotropic reactive ion etching
Implementation Method 2
using a combination of etching processes, including isotropic and anisotropic reactive ion etching
Implementation Method 3
using a combination of etching processes, including isotropic and anisotropic reactive ion etching
Data Source
AI summary
In one embodiment, semiconductor die are singulated from a semiconductor wafer by etching openings completely through the semiconductor wafer.