Polishing Liquid Storage and Freshness Control in CMP
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Solution Overview
Problem
In semiconductor device manufacturing, the increasing number of interconnection layers leads to poor step coverage and surface irregularities, which reduces the effectiveness of multilayer interconnections and photolithographic processes due to inadequate utilization of polishing liquids in chemical mechanical polishing (CMP) processes.
Innovation Solution
A polishing apparatus and method that utilizes a polishing liquid storage mechanism on the polishing pad to retain and reuse polishing liquids with sufficient capability, coupled with sensors and controllers to measure and adjust the freshness of the polishing liquid, ensuring optimal polishing performance by minimizing liquid discharge and maximizing utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polishing liquid is continuously supplied onto the polishing pad during CMP process, then polishing performance is maintained, but polishing liquid is discharged without utilizing its remaining polishing capability
Solution Approach 1:
The patent recovers polishing liquid from the waste liquid discharge path, separates it from debris and by-products, and returns it to the polishing pad for continued use. This prevents the loss of polishing liquid that would otherwise be discharged after a single use, allowing the liquid to be reused multiple times while maintaining polishing performance.
Solution Approach 2:
The patent implements a continuous circulation system where polishing liquid is repeatedly supplied to the polishing pad through multiple cycles. Instead of discarding the liquid after one use, the system maintains continuous utilization by recovering and re-supplying the liquid, thereby extending its service life and maximizing its polishing capability.
2Measurement precision
If polishing liquid is recovered and analyzed for component concentration, then liquid management is improved, but the polishing capability at the time of actual polishing cannot be measured
Solution Approach 1:
The patent introduces a sensor that measures polishing liquid properties (such as pH, conductivity, or other parameters indicative of polishing capability) in advance, before the liquid is discharged from the polishing pad. This preliminary measurement allows the system to assess the liquid's remaining capability while it is still in use, rather than analyzing it after discharge when its actual performance state is lost.
Solution Approach 2:
The patent uses a sensor as an intermediary device to indirectly measure the polishing capability of the liquid during its actual use. Instead of directly analyzing the liquid's polishing performance (which cannot be done after discharge), the sensor detects related physical or chemical parameters that correlate with polishing capability, providing real-time information about the liquid's state during the polishing process.
3Ease of manufacture
If polishing liquid is discharged from the polishing pad, then liquid replacement is simplified, but the polishing capability held by the liquid is not utilized to the maximum
Solution Approach 1:
The patent recovers polishing liquid from the waste liquid discharge path, separates it from debris and by-products, and returns it to the polishing pad for continued use. This prevents the loss of polishing liquid that would otherwise be discharged after a single use, allowing the liquid to be reused multiple times while maintaining polishing performance.
Solution Approach 2:
The patent implements a continuous circulation system where polishing liquid is repeatedly supplied to the polishing pad through multiple cycles. Instead of discarding the liquid after one use, the system maintains continuous utilization by recovering and re-supplying the liquid, thereby extending its service life and maximizing its polishing capability.
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 maximizes the polishing capability of the polishing liquid, reducing waste and maintaining effective polishing performance by continuously monitoring and adjusting the freshness and supply conditions of the polishing liquid, thereby enhancing the surface planarization and step coverage in semiconductor devices.
Implementation Method 1
a polishing liquid storage mechanism disposed on the polishing pad and configured to store the polishing liquid on the polishing pad by damming the polishing liquid
Implementation Method 2
a polishing liquid sensor configured to measure a physical quantity representing the freshness of the polishing liquid that is stored by the polishing liquid storage mechanism
Implementation Method 3
a substrate such as a semiconductor wafer is brought into sliding contact with the polishing pad, so that the surface of the substrate is polished
Implementation Method 4
a polishing liquid containing abrasive particles such as silica (SiO2) or cerin (CeO2) therein is supplied onto a polishing pad
Data Source
AI summary
A polishing apparatus polishes a surface of a substrate by pressing the substrate against a polishing pad on a polishing table. The polishing apparatus includes a polishing liquid supply nozzle for supplying a polishing liquid onto the polishing pad, a polishing liquid storage mechanism disposed on the polishing pad for storing the polishing liquid on the polishing pad by damming the polishing liquid, and a polishing liquid sensor for measuring a physical quantity representing the freshness of the polishing liquid stored by the polishing liquid storage mechanism. The polishing apparatus further includes a freshness measuring instrument for calculating the freshness of the stored polishing liquid from the physical quantity measured by the polishing liquid sensor, and a freshness controller for controlling supply conditions of the polishing liquid or storage state of the polishing liquid, based on the freshness of the polishing liquid that is determined by the freshness measuring instrument.