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Low temperature polysilicon technology LTPS introduction

Low Temperature Poly-silicon technology LTPS(Low Temperature poly-Silicon) was originally developed by Japanese and North American technology companies in order to reduce the energy consumption of Note-PC display and make Note-PC appear thinner and lighter. In the mid 1990s,this technology began to be put into trial phase.LTPS derived from the new generation of organic light-emitting panel OLED was also formally put into use in 1998,its biggest advantages are ultra-thin,light weight,low power consumption,can provide more gorgeous colors and clearer images.

Low temperature polysilicon

TFT LCD can be divided into polycrystalline silicon (Poly-Si TFT) and amorphous silicon (a-Si TFT),the difference between the two lies in the different transistor characteristics.The molecular structure of polysilicon is arranged neatly and directively in a Grain,so the electron mobility is 200-300 times faster than that of amorphous silicon.Generally known as TFT-LCD refers to amorphous silicon,mature technology,for the mainstream LCD products.The polysilicon mainly includes two kinds of products: high temperature polysilicon (HTPS) and low temperature polysilicon (LTPS).

Low Temperature Poly-silicon;Low temperature poly-Silicon;LTPS (thin film transistor liquid crystal display) uses excimer laser as heat source in the packaging process.After the laser light passes through the projection system,the laser beam with uniform energy distribution will be generated and projected on the glass substrate of amorphous silicon structure.After the glass substrate of amorphous silicon structure absorbs the energy of excimer laser,it will be transformed into a polysilicon structure.Because the whole process is completed at 600℃,so the general glass substrate can be applied.


LTPS-TFT LCD has the advantages of high resolution,fast reaction speed, high brightness,high opening rate, etc. In addition,because the silicon crystal arrangement of LTPS-TFT LCD is in order than a-Si,the electron mobility is more than 100 times higher,and the peripheral driving circuit can be fabricated on the glass substrate at the same time. Achieve the goal of system integration,save space and drive IC cost.

At the same time,because the driver IC circuit is directly produced on the panel,it can reduce the external contact of the component, increase reliability,easier maintenance,shorten the assembly process time and reduce EMI characteristics,and then reduce the application system design time and expand the design freedom.

LTPS-TFT LCD is the highest technology to achieve System on Panel,the first generation of LTPS-TFT LCD using built-in driver circuit and high-performance picture transistor to achieve high resolution and high brightness effect,has made LTPS-TFT LCD and A-Si have a great difference.

The second generation of LTPS-TFT LCD through the progress of circuit technology,from analog interface into digital interface,reduce power consumption.The on-carrier mobility of this generation LTPS-TFT LCD is 100 times that of a-Si TFT,and the line width of the electrode pattern is about 4μm,which is not fully used for LTPS-TFT LCD.

LTPS-TFT LCDS are better integrated into peripheral LSI than Generation 2.The purpose of LTPS-TFT LCDS is to :( 1) have no peripheral parts to make the module thinner and lighter,and reduce the number of parts and assembly time;(2) Simplified signal processing can reduce power consumption;(3) Equipped with memory can reduce power consumption to a minimum.

LTPS-TFT LCD is expected to become a new type of display due to its advantages of high resolution,high color saturation and low cost.With the advantages of high circuit integration and low cost,it has an absolute advantage in the application of small and medium-sized display panels.

However,there are two problems in p-Si TFT.First,the turn-off current (i.e. leakage current) of TFT is large (Ioff=nuVdW/L);Second,it is difficult to prepare high mobility p-Si material in large area at low temperature,and there is a certain difficulty in the process.

It is a new generation of technology derived from TFT LCD. LTPS screens are manufactured by adding a laser process to conventional amorphous silicon (A-Si)TFT-LCD panels,reducing the number of components by 40 percent and connecting parts by 95 percent,greatly reducing the chance of product failure.The screen offers significant improvements in power consumption and durability,with 170 degrees of horizontal and vertical viewing angles,12ms of response time,500 nits of brightness,and 500:1 contrast ratio.

There are three main ways to integrate low-temperature p-Si drivers:

The first is the hybrid integration mode of scan and data switch, that is,the line circuit is integrated together,the switch and shift register are integrated in the line circuit,and the multiple addressing driver and amplifier are externally connected to the flat panel display with the inherited circuit;

Second,all the driving circuit is fully integrated on the display;

Third,the driving and control circuits are integrated on the display screen.

Shenzhen Disen Display Technology Co., Ltd. is a high-tech enterprise integrating research and development,design, production,sales and service.It focuses on the research and development and manufacturing of industrial display screens,industrial touch screens and optical laminating products,which are widely used in medical equipment,industrial handheld terminals,Internet of Things terminals and smart home.We have rich R&D and manufacturing experience in tft LCD screen,industrial display screen,industrial touch screen,and full fit,and belong to the industrial display industry leader.

Post time: Mar-21-2023