Embedded ESC Diode Assembly for High-Temperature Thermal Stress Relief

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Solution Overview

Problem

Existing diode designs in electrostatic chucks (ESCs) for plasma processing chambers fail at high temperatures due to thermal stress and coefficient of thermal expansion mismatches, leading to premature diode failure and ESC malfunction.

Innovation Solution

The design incorporates a thin plate with an intermediate coefficient of thermal expansion between the silicon die and the metal strap connector, and uses a bent metal strap connector or wire bonding to reduce thermal stress and prevent solder reflow to the diode edge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a direct connection between silicon die and metal strap connector is used, then device complexity is reduced, but thermal stress causes diode failure at high temperatures

Engineering Contradiction:

Improvediode structure complexityVSAvoiddiode reliability at high temperature

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

An intermediate layer with intermediate coefficient of thermal expansion is introduced between the silicon die and metal strap connector. This intermediate layer acts as a mediator that reduces thermal stress by providing a gradual transition in thermal expansion properties, thereby preventing solder reflow and diode failure at high temperatures while maintaining structural integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The diode structure employs composite materials including silicon die, intermediate layer materials (such as tungsten-copper alloy or tungsten-molybdenum alloy), and metal strap connectors. This composite construction allows each material to contribute its optimal properties: silicon for semiconductor function, intermediate layer for thermal stress management, and metal for electrical connection and mechanical strength.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If extended temperature range operation is enabled, then processing versatility is improved, but thermal stress increases causing diode failure

Engineering Contradiction:

Improvetemperature range adaptabilityVSAvoiddiode reliability under thermal stress

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention explicitly addresses thermal expansion by selecting materials with intermediate coefficients of thermal expansion for the intermediate layer. This allows the structure to accommodate thermal expansion differences between silicon and metal components during temperature cycling, preventing solder joint failure and enabling reliable operation across extended temperature ranges from low to high temperatures.

Inventive Principle:

Principle #37Thermal expansion

3Ease of manufacture

If solder is used to bond die to connector, then manufacturing ease is improved, but solder reflow to diode edge causes failure at high temperature

Engineering Contradiction:

Improvediode assembly easeVSAvoiddiode reliability preventing solder reflow failure

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The intermediate layer serves as a protective cushion that prevents solder from refloving to the diode edge during high-temperature operation. By providing this protective barrier in advance, the design prevents the harmful effect of solder migration without complicating the manufacturing process, as the intermediate layer is integrated into the bonding structure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 design significantly increases the lifetime and operating temperature range of the diodes, preventing thermal stress-induced failures and ensuring reliable ESC operation even at extended high-temperature conditions.

Implementation Method 1

a thin plate with an intermediate coefficient of thermal expansion between the silicon die and the metal strap connector

Methodology Applied

Scientific EffectCoefficient of thermal expansion: Thermal Expansion

Implementation Method 2

uses a bent metal strap connector or wire bonding to reduce thermal stress and prevent solder reflow to the diode edge

Methodology Applied

Scientific EffectThermal stress: Thermal Expansion

Data Source

PatentUS20250087518A1Long-life extended temperature range embedded diode design for electrostatic chuck with multiplexed heaters array

Publication Date: 2025.03.13 LAM RES CORP

AI summary

A substrate support for a plasma chamber includes a base plate arranged along a plane, a first layer of an electrically insulating material arranged on the base plate along the plane, a plurality of heating elements arranged in the first layer along the plane, and a plurality of diodes arranged in respective cavities in the first layer. The plurality of diodes are connected in series to the plurality of heating elements, respectively. Each of the plurality of diodes includes a die of a semiconductor material arranged in a respective one of the cavities. The semiconductor material has a first coefficient of thermal expansion. A first side of the die is arranged on the first layer along the plane. A first terminal of the die is connected to a first electrical contact on the first layer.