Research On Embedded Wafer Temperature Monitoring Device

In the semiconductor manufacturing process,uneven wafer temperature distribution or slight deviation from the process set temperature will directly lead to a significant drop in chip yield.In order to improve the accuracy of wafer temperature measurement and make it compatible with the current highly automated semiconductor manufacturing production line,wireless embedded wafer temperature monitoring equipment based on contact technology came into being.The equipment not only has high measurement accuracy,but also can participate in the actual process flow as a"test wafer",thereby avoiding modification and adjustment of various manufacturing equipment.This kind of"non-invasive"tool for the semiconductor processing chamber plays a very important role in accelerating the high volume manufacturing(HVM)production cycle,chamber-to-chamber matching,tool qualification,process characterization and other key links.However,at present,the development of advanced test equipment in China is slow,and there is almost no research on such devices.Therefore,this thesis will design a set of embedded wafer temperature monitoring prototype system which can be used in plasma etching and post exposure bake(PEB)processes.This system has important practical significance for promoting the independence of advanced semiconductor testing equipment in China.(1)Through the design of software and hardware,the core functions of the embedded wafer temperature monitoring device were realized.Among them,the lower computer used a flexible substrate to integrate various electronic components,which simplified the steps of subsequent device installation and reduced the production cost of the device.Its core area was 43×55 mm~2,and the power consumption was less than 137 m W.8-channel data acquisition and storage were realized,and the acquisition time and sampling frequency were adjustable.The GUI interface of the upper computer was written in Python and QT,which was used for real-time interaction with the lower computer,and could realize the functions of real-time display of temperature data,reconstruction of wafer temperature field,data storage and reading,etc.(2)The protection device of the core module was designed and realized.The device mainly used the low thermal conductivity material in the middle of the double-layer shell to achieve effective heat insulation,and the electromagnetic shielding of metal material was used to achieve effective electrical isolation in the radio frequency environment.Finally,the thermal and electromagnetic simulations were carried out by Comsol.The results showed that after the core module equipped with the device was baked at 120?for 10 min,the temperature was kept at about 60?,which was lower than its upper limit temperature and could isolate the induced current in the plasma environment excited by13.56 MHz.(3)The large-area deep groove etching process for 6-inch wafers was explored,and the specific solvents and process parameters for photolithography,silicon dioxide etching,and silicon etching were determined.A 6-inch wafer wet etching equipment was built to solve the problem that bubbles on the surface of the silicon wafer were difficult to remove during large-area etching.The groove was etched with a depth of about 0.2 mm and with a relatively smooth bottom.(4)A calibration experiment and a series of test experiments were carried out on the embedded wafer temperature monitoring device.The results showed that the absolute value of the sensor measurement error of the device did not exceed 1.23?,and the absolute value of the temperature field error did not exceed 1.8?.The device enables temperature measurements in flat panel heaters and plasma environments.