PZT Sensor Stack Planarization for Uniform TFT Display Integration
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Solution Overview
Problem
The integration of ferroelectric sensors or actuators in display devices leads to unevenness and performance inconsistencies due to their thickness, causing issues like uneven luminance and color, especially when stacked with functional regions.
Innovation Solution
A semiconductor device design incorporating a PZT sensor with a lower electrode, PZT film, upper electrode, and polyimide film, where the polyimide film is at least 5 μm thick to planarize the surface, allowing for uniform integration with TFTs and display regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a PZT sensor with certain thickness is stacked with a pixel forming region, then the sensor can detect pressure effectively, but unevenness occurs between the sensor portion and non-sensor portion
Solution Approach 1:
A resin layer is introduced as an intermediary substance between the PZT sensor and the pixel forming region. This resin layer fills the space around the sensor, compensating for the thickness difference and creating a flat upper surface that enables uniform light emission while preserving the sensor's pressure detection function
Solution Approach 2:
The refractive index of the resin layer is specifically controlled to match or coordinate with the pixel structure. By adjusting this optical parameter, the resin layer becomes optically transparent to the pixel light, preventing luminance unevenness while maintaining surface flatness
2Measurement precision
If a PZT sensor is formed only on a portion of the display region, then the sensor function is achieved, but uneven luminance or uneven color may occur between the sensor region and other regions
Solution Approach 1:
The resin layer acts as an optical intermediary that fills the regions where no sensor is present. This creates a uniform optical interface across the entire display region, ensuring that light from pixels passes through a consistent medium regardless of whether a sensor is present, thereby eliminating luminance and color unevenness
Solution Approach 2:
The resin layer provides a homogeneous optical environment across the display region. By having the same material properties throughout, it ensures uniform light transmission and prevents regional variations in luminance and color, making the sensor presence invisible optically
3Shape
If a thick polyimide film is used to planarize the surface, then surface unevenness is suppressed, but the overall device thickness increases
Solution Approach 1:
Instead of using a uniformly thick polyimide film across the entire device, the invention applies a resin layer only in specific regions where planarization is needed (around the sensor portions). This localized approach achieves surface flatness where required while minimizing the overall thickness increase of the device
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 suppresses unevenness and ensures uniform performance across the display area by planarizing the surface, enabling stable operation of PZT sensors and actuators in display devices.
Implementation Method 1
a polyimide film is formed over the PZT sensor... a thickness of the polyimide film is 5 μm or more
Data Source
AI summary
The purpose of the present invention is to form a semiconductor device in which an active area laminated on a PZT (lead zirconate titanate (PbZrTiO3) sensor having a piezoelectric effect. The main structure of the present invention is as follows. A semiconductor device having a PZT (lead zirconate titanate (PbZrTiO3)) sensor including: the PZT sensor including a lower electrode formed on a glass substrate, a PZT, an upper electrode, a first inorganic insulating film covering the upper electrode, and an upper wiring formed on the first inorganic insulating film and connected to the upper electrode through a first through-hole formed in the first inorganic insulating film; in which a polyimide film is formed over the PZT sensor; a plurality of TFTs are formed on the polyimide film, and a thickness of the polyimide film is 5 μm or more.