CMP Heads With Cross-Zone Pressure Element Distributions

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Solution Overview

Problem

Chemical mechanical polishing (CMP) systems face challenges in achieving uniform workpiece thickness due to uneven pressure distribution across concentric pressure zones, leading to significant total thickness variation (TTV) greater than 0.35 micrometers, which can result in device failure and alter electrical properties.

Innovation Solution

A CMP system comprising a first CMP head with a first plurality of pressure elements and a second CMP head with a second plurality of pressure elements, where the distribution of pressure elements across the second CMP head differs from the first, allowing for compensation of undesired thickness achieved during the first CMP process, thereby reducing TTV to less than 0.3 micrometers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a single CMP head with uniform pressure elements is used, then the device complexity is low, but the manufacturing precision deteriorates due to significant TTV greater than 0.35 micrometers

Engineering Contradiction:

Improveworkpiece thickness uniformityVSAvoidCMP head configuration

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The polishing system is divided into multiple CMP heads (first CMP head, second CMP head, third CMP head) instead of using a single CMP head. Each CMP head has its own pressure elements that can be independently controlled, allowing the system to address thickness variations in different zones of the workpiece through segmented processing passes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each CMP head is equipped with pressure elements distributed in specific patterns (e.g., concentric zones, radial patterns) that apply localized pressure to specific regions of the workpiece. This allows different areas of the workpiece to receive tailored polishing pressure, compensating for local thickness variations and achieving more uniform overall thickness.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If multiple CMP heads with different pressure element distributions are used, then the manufacturing precision improves with TTV reduced to less than 0.3 micrometers, but the device complexity increases

Engineering Contradiction:

Improveplanarization accuracyVSAvoidmultiple CMP heads with different pressure distributions

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary polishing passes with the first CMP head to remove the majority of material and establish a baseline planar surface. Subsequent CMP heads then perform corrective polishing to address remaining thickness variations, with each head's pressure element distribution optimized for the specific corrections needed at that stage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system incorporates thickness measurement and control mechanisms that monitor the workpiece thickness during polishing. Based on measured thickness variations, the control system adjusts the activation and pressure of specific pressure elements in different CMP heads to compensate for deviations, creating a closed-loop feedback control system that achieves high precision planarization.

Inventive Principle:

Principle #23Feedback

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

The system achieves more accurate planarization and uniform workpiece thickness by adjusting pressure distributions between the first and second CMP processes, minimizing TTV and ensuring better processing outcomes.

Implementation Method 1

The plurality of pressure elements are configured to press corresponding concentric surfaces on a front-side of the workpiece into the polishing pad with varying force

Methodology Applied

Scientific EffectMechanical pressure: Mechanical Force

Implementation Method 2

planarization technology, such as a chemical mechanical polishing (CMP) process, has been implemented to planarize a wafer or one or more layers of features over the wafer

Methodology Applied

Scientific EffectChemical mechanical polishing: Abrasion

Data Source

PatentUS20220362903A1Multiple polishing heads with cross-zone pressure element distributions for cmp

Publication Date: 2022.11.17 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Various embodiments of the present disclosure are directed towards a chemical mechanical polishing (CMP) system including a first CMP head and a second CMP head. The first CMP head is configured to retain a workpiece and comprises a first plurality of pressure elements disposed across a first pressure control plate. The second CMP head is configured to retain the workpiece. The second CMP head comprises a second plurality of pressure elements disposed across a second pressure control plate. A distribution of the first plurality of pressure elements across the first pressure control plate is different from a distribution of the second plurality of pressure elements across the second pressure control plate.