Super Flat CMP with Hard Stop Points for GaN LED Substrate Removal
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) technology struggles to achieve a super flat surface for large semiconductor device planes, leading to significant location variables and reduced yield in mass production, which is not compatible with the laser lift-off method used for film GaN light emitting diodes, resulting in high costs and processing damages.
Innovation Solution
The implementation of super flat chemical mechanical polishing (SF-CMP) technology, which involves creating polishing stop points with materials harder than the substrate to be removed, such as diamond films, to control the polishing process and ensure a flat surface without damaging the active region, using Inductively Coupled Plasma etching and mechanical or chemical mechanical polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional chemical mechanical polishing (CMP) technology is applied to large semiconductor device planes, then the polishing process can be performed without laser equipment, but the location variables of two sides and center of the plane become too large, failing to achieve the required flatness standard
Solution Approach 1:
The patent applies local quality by creating polishing stop points with different material properties (harder material) at specific locations on the substrate. These localized hard points serve as reference markers that enable precise measurement and control of polishing uniformity across the entire large plane, allowing conventional CMP to achieve the required flatness standard without laser equipment
Solution Approach 2:
The patent changes the physical parameters of the polishing process by introducing reference points with different hardness characteristics. By measuring the depth or removal amount at these hard points versus surrounding areas, the system can quantify and control polishing uniformity, transforming the unmeasurable flatness into a measurable parameter that can be controlled within specifications
2Reliability
If laser lift-off method is used to remove sapphire substrate, then the active region can be kept intact, but expensive laser equipment is required and processing damages occur
Solution Approach 1:
The patent replaces the optical/laser-based lift-off system with a mechanical polishing system. By using conventional CMP equipment with harder reference points, the method eliminates the need for expensive laser equipment while maintaining the integrity of the active region through controlled mechanical removal of the sapphire substrate
Solution Approach 2:
The patent uses disposable or easily replaceable hard reference points (such as deposited metal layers or hard mask materials) that are removed along with the sapphire substrate. These inexpensive reference points enable the use of conventional equipment instead of expensive laser systems, reducing overall device complexity and cost
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
SF-CMP technology effectively reduces location variables, achieves low costs, and enhances yield by maintaining the flatness required for semiconductor devices, while providing better thermal dissipation and protecting the active region during substrate removal.
Implementation Method 1
the etching step is Inductively Coupled Plasma
Implementation Method 2
polishing the first material to expose the second layer material by mechanical or chemical mechanical polishing method
Implementation Method 3
chemical mechanical polishing (SF-CMP) technology
Implementation Method 4
the third material is diamond film or Diamond Like Carbon film
Implementation Method 5
the third material is diamond film or Diamond Like Carbon film
Implementation Method 6
bonding surface of the second layer on a conductive fourth material
Data Source
AI summary
The present invention provides a method of super flat chemical mechanical polishing (SF-CMP) technology, which is a method characterized in replacing laser lift-off in a semiconductor fabricating process. SF-CMP has a main step of planting a plurality of polishing stop points before polishing the surface, which is characterized by hardness of the polishing stop points material being larger than hardness of the surface material. Therefore, the present method can achieve super flat polishing surface without removing polishing stop points.