Multi-Head CMP Apparatus with Variable Pressure Zones

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Solution Overview

Problem

Conventional methods for ensuring wafer surface uniformity in semiconductor manufacturing, particularly in chemical mechanical polishing (CMP), have not been entirely satisfactory in achieving closely controlled target thickness and surface profile uniformity as device scaling continues, leading to significant variations across wafer surfaces.

Innovation Solution

A multi-head CMP apparatus with wafer head assemblies that include pressure zones with individually variable pressures and a control system for determining CMP polishing recipes based on pre- and post-polishing characteristics, using advanced process control to achieve target thickness and surface profile uniformity through a network of metrology tools, databases, and APC systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional CMP methods are used to achieve mean target thickness control, then the polishing process is simple and fast, but significant variations across wafer surfaces occur leading to poor surface profile uniformity

Engineering Contradiction:

Improvesurface profile uniformityVSAvoidpolishing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The polishing pad surface is divided into multiple discrete pressure zones (e.g., center, inner annulus, outer annulus zones) with independently controllable pressures. This segmentation allows different regions of the wafer to receive customized pressure profiles, enabling precise control over material removal rates across the wafer surface to achieve uniform surface profiles while maintaining process manageability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different pressure values are applied to different zones of the polishing pad based on the specific wafer surface profile requirements. The control system adjusts pressure distribution locally across various pad zones to compensate for non-uniform material removal, achieving high surface profile uniformity through localized pressure optimization rather than uniform pressure application

Inventive Principle:

Principle #3Local quality

2Productivity

If device scaling continues to increase functional density, then production efficiency increases and costs decrease, but variations across wafer surfaces become significant requiring closely controlled target thickness and surface profile uniformity

Engineering Contradiction:

Improveproduction efficiencyVSAvoidtarget thickness control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system incorporates real-time feedback from metrology tools that measure wafer surface profiles before and after polishing. The APC control system uses this feedback data to dynamically adjust pressure zone settings and polishing parameters, ensuring that target thickness and surface profile uniformity are achieved even as device scaling increases production demands

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary measurements of incoming wafer surface profiles and uses this information to pre-calculate optimal pressure zone configurations before the polishing process begins. This preliminary action allows the system to proactively compensate for expected variations, achieving precise target thickness control without requiring excessive process complexity during actual polishing

Inventive Principle:

Principle #10Preliminary action

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 solution effectively reduces variations in wafer surface profiles, achieving improved within-wafer and wafer-to-wafer uniformity, reducing rework rates and improving cycle time by up to 80% reduction in offset, 57.5% reduction in standard deviation, and 35.7% reduction in range from target profiles.

Implementation Method 1

chemical mechanical polishing (CMP) process

Methodology Applied

Scientific EffectChemical mechanical polishing:

Data Source

PatentUS10096482B2Apparatus and method for chemical mechanical polishing process control

Publication Date: 2018.10.09 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An apparatus and method for providing target thickness and surface profile uniformity control of a multi-head chemical mechanical polishing (CMP) process is disclosed. An exemplary method includes providing at least two wafers; determining a surface profile of each of the at least two wafers; determining an operation mode for a chemical mechanical polishing (CMP) process based on the surface profiles of the at least two wafers; determining a CMP polishing recipe for each of the at least two wafers based on the operation mode; and performing the CMP process on the at least two wafers based on the determined CMP polishing recipes.