Multi-Head Wafer Polishing for Individual Pressure and Rotation Control
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Solution Overview
Problem
Conventional CMP equipment faces challenges with high process times, high consumable costs, and inability to individually adjust polishing conditions for each wafer due to batch control methods, leading to inefficiencies and wafer shape precision issues under ultra-high-pressure conditions.
Innovation Solution
A wafer polishing apparatus with individually controllable multiple polishing heads, featuring a platen with a polishing pad and a polishing unit that includes independently operable polishing parts, pressure drive parts, rotation drive parts, and oscillation parts, allowing precise control over each polishing head's rotation, pressure, and oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple polishing heads are controlled in batches with one motor, then device complexity is reduced, but individual control capability is lost
Solution Approach 1:
The patent divides the single motor control system into multiple independent motors, with each motor controlling one polishing head. This segmentation allows each polishing head to be individually controlled according to different wafer requirements, resolving the contradiction between device complexity and individual control capability.
2Productivity
If ultra-high-pressure conditions (78.4 kPa or more) are applied to increase polishing rate, then productivity is improved, but wax fixing the wafer melts due to high frictional heat causing wafer detachment and shape precision deterioration
Solution Approach 1:
The patent applies oscillation to the polishing head, creating a dynamic polishing action that reduces frictional heat accumulation while maintaining high pressure contact. This dynamic approach allows ultra-high-pressure polishing to proceed without melting the wax, thereby maintaining both high productivity and wafer shape precision.
Solution Approach 2:
The oscillation creates periodic contact and separation between the polishing head and wafer surface, which prevents continuous frictional heating. This periodic action enables sustained ultra-high-pressure polishing while avoiding wax melting and wafer detachment, resolving the contradiction between polishing rate and shape precision.
3Manufacturing precision
If low-pressure conditions (300 to 400 g/cm2) are used for CMP, then wafer shape precision is maintained, but process time increases and consumables increase leading to high costs
Solution Approach 1:
By introducing oscillation motion to the polishing head, the system achieves effective polishing at ultra-high pressures without excessive heat generation. This dynamic approach enables maintaining wafer shape precision while dramatically reducing process time and consumable usage, thus resolving the contradiction between manufacturing precision and productivity.
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
Enables efficient and precise polishing of wafers by reducing process time, minimizing consumable material use, and improving polishing flatness, thereby reducing overall costs and enhancing wafer production quality.
Implementation Method 1
a turning motor mounted on the baseplate and having a motor rotation shaft penetrating downwardly through the baseplate; and a second rotary gear coupled to a motor rotation shaft of the turning motor
Implementation Method 2
Mechanical polishing involves applying pressure to the wafer while rotating it against a rotating polishing pad, resulting in surface abrasion due to the friction between the polishing pad and the wafer surface
Implementation Method 3
a pressure cylinder mounted on the baseplate and equipped with a piston rod that moves up and down and back and forth
Data Source
AI summary
A wafer polishing apparatus includes a platen having a polishing pad attached to its upper surface and rotating together with the polishing pad, and a polishing unit disposed on an upper side of the platen and configured to perform polishing by pressurizing and rotating a wafer interposed between the polishing unit and a polishing pad, wherein the polishing unit includes a baseplate, a plurality of polishing parts, a plurality of rotation drive parts and a plurality of pressure drive parts.