Ovenized MEMS Package Layout for Temperature-Stable Resonators

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Solution Overview

Problem

Microelectromechanical systems (MEMS) components in integrated circuit packages face temperature-dependent performance variance and instability due to ambient temperature fluctuations, affecting frequency, voltage, and propagation delay.

Innovation Solution

The implementation of oven-controlled MEMS packages with temperature-stabilized regions, where MEMS components are heated to a steady-state 'oven' temperature using integrated or discrete heating elements, while temperature-insensitive circuitry is segregated for heat dissipation, maintaining thermal isolation and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If MEMS components operate in ambient temperature environment, then device complexity is reduced, but performance stability deteriorates due to temperature fluctuations

Engineering Contradiction:

Improveperformance stabilityVSAvoidtemperature control structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The package is divided into thermally isolated regions: a heated region containing the MEMS component and a separate ambient region for temperature-insensitive circuitry. This segmentation allows the MEMS component to operate in a stable thermal environment while other components remain in ambient conditions, resolving the contradiction between performance stability and device complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the package are assigned different thermal characteristics: the MEMS region is heated to a controlled temperature (e.g., 85°C) while other regions remain at ambient temperature. This local quality approach enables temperature-stable MEMS operation without requiring the entire device to be heated, thus managing complexity effectively.

Inventive Principle:

Principle #3Local quality

2Reliability

If heating elements are integrated with MEMS components, then temperature stability is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvetemperature stabilityVSAvoidintegration process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The heating element is integrated directly with the MEMS component on the same substrate, combining the thermal control function with the MEMS structure. This merging eliminates the need for separate heating components and their associated interconnects, improving temperature stability while actually simplifying the overall manufacturing process through integration.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If temperature-insensitive circuitry is segregated into separate regions, then thermal isolation is improved, but package area increases

Engineering Contradiction:

Improvethermal isolationVSAvoidpackage footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The package utilizes a three-dimensional stacked architecture where temperature-insensitive circuitry is placed on separate layers or substrates beneath or adjacent to the heated MEMS region. This vertical dimensionality change provides thermal isolation without significantly increasing the horizontal package footprint, resolving the contradiction between thermal isolation and package area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 approach stabilizes MEMS component performance by maintaining a consistent operating temperature, reducing temperature-dependent instability and enhancing operational reliability and accuracy.

Implementation Method 1

heating elements, fabricated separately from or as part of the transistor circuitry or part of the MEMS die, are provided to heat the MEMS component to a temperature higher than an ambient temperature range

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The MEMS component and the transistor circuitry are mounted to a common substrate that is affixed to an interior wall of a package housing by a thermally insulating material

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

the latter being provided with (e.g., disposed adjacent) one or more heat dissipation paths to discharge heat generated by transistor circuitry

Methodology Applied

Scientific EffectHeat dissipation: Heat Sink

Data Source

PatentUS20250007455A1Ovenized MEMS

Publication Date: 2025.01.02 SITIME CORP

AI summary

One or more heating elements are provided to heat a MEMS component (such as a resonator) to a temperature higher than an ambient temperature range in which the MEMS component is intended to operate-in effect, heating the MEMS component and optionally related circuitry to a steady-state “oven” temperature above that which would occur naturally during component operation and thereby avoiding temperature-dependent performance variance/instability (frequency, voltage, propagation delay, etc.). In a number of embodiments, an IC package is implemented with distinct temperature-isolated and temperature-interfaced regions, the former bearing or housing the MEMS component and subject to heating (i.e., to oven temperature) by the one or more heating elements while the latter is provided with (e.g., disposed adjacent) one or more heat dissipation paths to discharge heat generated by transistor circuitry (i.e., expel heat from the integrated circuit package).