Wafer Chuck Mesa Layout for Low-Pressure Backside Contact

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Solution Overview

Problem

Existing wafer chuck designs with contact-minimizing structures can cause damage to the backside of semiconductor wafers due to high clamping pressures over small contact areas, leading to indentation or cracking of films.

Innovation Solution

The use of high-density mesa patterns on the wafer chuck surface, where individual mesas have a substantially flat contact surface and are arranged in a pattern that increases the collective contact area, reducing the contact pressure from clamping forces below a critical level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If contact-minimizing structures (small hemispherical domes or pillars) are used on the chuck surface, then particle generation is reduced, but clamping pressure is magnified causing damage to wafer backside films

Engineering Contradiction:

Improveparticle generationVSAvoidfilm integrity

Core Design Contradiction:

Object-generated harmful factorsVSStrength

Solution Approach 1:

The chuck surface is segmented into multiple discrete contact-minimizing structures (mesas) distributed across the surface. Each mesa provides a localized contact point while the collective array distributes clamping forces, preventing concentration of stress that would damage films while maintaining minimal total contact area to reduce particle generation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The contact-minimizing structures are designed with specific local geometric properties (mesa shape, size, and distribution) that optimize the balance between minimizing contact area and distributing pressure. The mesas provide localized regions of controlled contact that prevent both excessive particle generation and film damage.

Inventive Principle:

Principle #3Local quality

2Area of stationary object

If the number of contact structures is kept small to maintain minimal contact area, then particle generation is reduced, but clamping pressure per structure increases causing film damage

Engineering Contradiction:

Improvecontact areaVSAvoidclamping pressure

Core Design Contradiction:

Area of stationary objectVSStress or pressure

Solution Approach 1:

The total contact area is segmented into numerous small mesa structures distributed across the chuck surface. This segmentation allows the system to maintain a small overall contact area fraction (minimal particle generation) while the distributed nature of multiple mesas prevents pressure concentration, keeping individual contact pressures below damage thresholds.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20250167025A1Apparatus and methods for reducing wafer backside damage

Publication Date: 2025.05.22 LAM RES CORP

AI summary

A wafer chuck assembly is disclosed, in accordance with at least one embodiment. In at least one embodiment, wafer chuck assembly comprises a wafer chuck comprising a substantially circular surface having a first area. In least one embodiment, plurality of mesas is distributed over the wafer chuck surface. In at least one embodiment, individual ones of the plurality of mesas extend a height above the wafer chuck surface. In at least one embodiment, plurality of mesas has a contact surface having a second area that is at least 3% of the first area.