Thermal Sensor Recess Design for Thickness and Reliability

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Solution Overview

Problem

Current thermal sensor manufacturing processes result in a thick overall structure due to the formation of thermal sensing devices above transistors, and high-temperature heat treatments during dopant diffusion can damage metal members and lead to poor reflection efficiency in doped regions.

Innovation Solution

A thermal sensor design featuring a metal silicide reflective layer within a recess in the substrate, where the thermal sensing device includes a metal silicide reflective layer, dielectric layers, and a thermal absorbing layer, allowing the transistor and metal members to be formed after the thermal sensing device, thus avoiding high-temperature damage and improving reflection efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the thermal sensing device is formed above the transistor structure, then the thermal sensing device can be integrated with the transistor, but the overall structure thickness increases significantly

Engineering Contradiction:

Improveintegration capabilityVSAvoidstructure thickness

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent transitions from a vertical stacking arrangement (thermal sensing device above transistor) to a lateral arrangement where both the transistor and thermal sensing device are formed in the same substrate plane. This dimensional change allows integration without increasing overall thickness, as both components occupy the same two-dimensional plane rather than stacking in the third dimension.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If high-temperature heat treatment is applied to diffuse dopant into semiconductor material, then the seebeck coefficient increases, but previously formed metal members are damaged

Engineering Contradiction:

Improveseebeck coefficientVSAvoidmetal member damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent performs the high-temperature heat treatment to diffuse dopant into the semiconductor material before forming the metal members. By executing the dopant diffusion process first, the semiconductor achieves the desired seebeck coefficient enhancement, and subsequent metal deposition occurs at lower temperatures that do not damage the metal structures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent inverts the conventional process sequence by forming the thermal sensing device (requiring high-temperature dopant diffusion) before forming the transistor and its metal interconnects. This reversal ensures that the high-temperature process is applied when metal members are not yet present, eliminating the damage issue while maintaining the seebeck coefficient improvement.

Inventive Principle:

Principle #13The other way round (Inversion)

3Device complexity

If a doped region is used as the thermal reflective layer, then the structure can be simplified, but reflection efficiency deteriorates due to excessive dopant diffusion

Engineering Contradiction:

Improvestructure complexityVSAvoidreflection efficiency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the material parameter of the reflective layer from a doped semiconductor region to a metal silicide material. This parameter change provides superior thermal reflection efficiency compared to doped regions, while the metal silicide can be deposited at lower temperatures that prevent excessive dopant diffusion in adjacent doped regions used for the thermal absorbing layer.

Inventive Principle:

Principle #35Parameter changes

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 prevents damage to transistors and metal members during high-temperature treatments, enables the use of doped layers with higher seebeck coefficients for better thermal performance, and maintains reflection efficiency similar to metal reflective layers, facilitating maximum thermal absorption.

Implementation Method 1

For the heat that passes through the thermal absorbing layer without being absorbed, the thermal reflective layer may reflect the heat back to the thermal absorbing layer to achieve the object of maximum thermal absorbing efficiency

Methodology Applied

Scientific EffectThermal reflection: Reflection

Implementation Method 2

After the thermal absorbing layer absorbs heat, a signal may be transmitted to the transistor electrically connected thereto

Methodology Applied

Scientific EffectThermal absorption: Absorption (physical)

Implementation Method 3

it is preferable to select a doped semiconductor material having a higher seebeck coefficient

Methodology Applied

Scientific EffectSeebeck effect: Seebeck Effect

Data Source

PatentUS11856855B2Thermal sensor and manufacturing method thereof

Publication Date: 2023.12.26 NUVOTON

AI summary

Provided are a thermal sensor and a manufacturing method thereof. The thermal sensor includes a transistor and a thermal sensing device. The thermal sensing device is disposed in a recess in a substrate and electrically connected to the transistor. The thermal sensing device includes a first dielectric layer, a metal silicide reflective layer, a second dielectric layer, and a thermal absorbing layer. The first dielectric layer is disposed on sidewalls and a bottom of the recess. The metal silicide reflective layer is disposed on the first dielectric layer located on the bottom of the recess. The second dielectric layer is disposed at a top of the recess. The thermal absorbing layer is disposed on the second dielectric layer.