Polishing Pad Temperature Control for Wafer Etching
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to optimize the surface temperature of a polishing pad during wafer polishing to achieve an appropriate polishing rate, as the polishing rate depends on both the polishing load and the surface temperature of the pad, which can vary with the condition of the film being polished, and requires precise temperature control to prevent excessive etching or erosion.
Innovation Solution
A method involving a polishing apparatus with a surface-condition detector, such as a torque measuring device or film-thickness measuring device, to create time-series data and determine distinctive change points in the surface condition, allowing for real-time temperature control of the polishing pad using a pad-temperature regulating device, ensuring optimal temperature adjustments based on the film's condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the surface temperature of the polishing pad is increased to optimize the polishing rate, then the chemical action of the polishing liquid is enhanced, but excessive etching or erosion of the wafer occurs
Solution Approach 1:
The polishing pad temperature is changed from a static constant value to a dynamic time-varying profile. The temperature is automatically adjusted during the polishing process based on the polishing stage, creating a dynamic thermal environment that optimizes both polishing rate and wafer protection without requiring manual intervention.
Solution Approach 2:
A temperature profile is predetermined and programmed into the temperature control device before polishing begins. This preliminary action allows the system to automatically execute the optimal temperature sequence without real-time decision-making during polishing, ensuring consistent results while preventing harmful effects.
2Object-affected harmful factors
If the temperature of the polishing surface is lowered to prevent excessive etching, then wafer protection is improved, but the polishing rate decreases
Solution Approach 1:
Rather than maintaining a static low temperature to prevent etching, the system dynamically adjusts temperature throughout the polishing process. High temperatures are applied during early stages for efficient material removal, then temperatures are reduced in later stages to protect the wafer, thereby maintaining high productivity while preventing harmful effects.
Solution Approach 2:
The temperature control follows a periodic pattern with distinct phases: an initial high-temperature phase for rapid polishing, followed by a transition to lower temperatures for protection. This periodic temperature variation allows the system to achieve both high polishing rates and wafer protection sequentially.
3Ease of operation
If a constant temperature is maintained throughout the polishing process, then temperature control simplicity is preserved, but the polishing rate cannot be optimized for different film conditions
Solution Approach 1:
The complex temperature profile is predetermined and programmed before polishing begins. This preliminary action transforms a potentially complex real-time control problem into a simple execution of a pre-planned sequence, maintaining ease of operation while achieving optimized polishing rates for different film conditions.
Solution Approach 2:
The temperature control device automatically adjusts temperatures according to the pre-programmed profile without requiring continuous manual intervention or complex real-time decision-making. The system serves itself by executing the predetermined sequence, maintaining simplicity while achieving optimization.
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 enables precise control of the polishing pad's temperature according to the film's condition, optimizing the polishing rate and preventing excessive etching or erosion by adjusting the temperature dynamically during the polishing process.
Implementation Method 1
a pad contact member into which temperature-controlled heating liquid and cooling liquid are supplied
Implementation Method 2
The film of the wafer is planarized by a chemical action of the polishing liquid and mechanical action(s) of abrasive grains
Implementation Method 3
mechanical action(s) of abrasive grains contained in the polishing liquid and/or the polishing pad
Implementation Method 4
An oxide film may be formed on the film, to be polished, of the wafer between a film forming process and a polishing process for the wafer. This oxide film is formed by a reaction of the film formed in the film forming process with oxygen in the air
Data Source
AI summary
A polishing method capable of appropriately controlling a temperature of a polishing surface of a polishing pad during polishing of a workpiece is disclosed. The polishing method includes detecting a surface condition of a sample while polishing the sample on a polishing surface of a polishing pad; creating time-series data representing temporal change in the surface condition of the sample; determining a point in time at which the surface condition of the sample has distinctively changed based on the time-series data; determining a temperature control time based on the determined point in time; and controlling a temperature of the polishing surface of the polishing pad based on the temperature control time, while polishing a workpiece on the polishing surface of the polishing pad.