Research On Particle Improvement Method Of Amorphous Silicon Film Prepared By High Generation TFT-LCD Production Line

TFT-LCD is a combination of microelectronic technology and liquid crystal display technology,it is widely used in the production of notebook computers,tablet computers,vehicle mounted displays,televisions,mobile phones,watches and other daily electronic products.PECVD is a chemical vapor deposition technology.The principle is that gas is introduced into the process chamber,and the required silicon film is generated by chemical reaction under the action of radio frequency power and heat energy.PECVD has the advantages of low reaction temperature,fast film deposition rate and good film deposition uniformity.It is widely used in large-scale industrial production.It is the main way of amorphous silicon film deposition in LCD industry.However,when PECVD equipment is used to prepare amorphous silicon film,due to poor pre cleaning,poor adhesion of amorphous silicon film,bombardment of chamber by high power,poor hardware design and so on,it is easy to produce particle pollution,which leads to the failure of TFT devices and has a great impact on the yield and reliability of products.In addition,with the development of TFT-LCD technology,the product grade is higher and higher,and the TFT size is smaller and smaller,resulting in the further amplification of the impact of amorphous silicon film particle on the product yield and reliability.How to improve amorphous silicon film particle has become an important research topic for TFT-LCD factory.This paper studies the improvement of amorphous silicon film particle from three aspects:amorphous silicon film deposition process,film deposition equipment and film process equipment management,and finds an effective method to improve amorphous silicon film particle through verification.Process optimization direction:（1）For the two agglomerated particles,it is found that the pre-treatment process is the main reasons.The reduction of NH₃/N₂treatment time and treatment power before film deposition can be significantly improved.（2）For the arcing particle,It is found that GH film deposition process is the main reason.The decrease of GH deposition power,the increase of GH deposition pressure and the decrease of GH deposition power ramping rate can be significantly improved,in addition,the chamber hardware also has some effect.（3）For the first substrate particle,it is found that the clean season process is the main cause,in addition,the surface condition of diffuser also has some effect.The flow of cleaning gas NF₃is reduced,the cleaning power is reduced,the position cleaning of process chamber slit valve is increased,process chamber is purged with Ar or N₂after cleaning,the season film is thickened,the laminated structure of SiO_x/SiON_x/SiN_x is used for the season film,the roughness of diffuser is increased and the process chamber is treated with H₂plasma after idle can be effectively improved.（4）For small particles,it is found that the cleaning process before film deposition,film deposition process and clean season process have important effects on small particle.It can be effectively improved by optimizing the cleaning process of HDC,GI film quality of film deposition process,GH film deposition conditions of film deposition process,process chamber cleaning process and process chamber clean season cycle.Equipment optimization direction:（1）For the particles gathered at the four corners around,it is found that loadlock pumping port,shadow frame and shadow frame support are the main reasons.The pumping speed of loadlock decreased,the baffle of the pumping port was added with the fast speed pumping and slow speed pumping were controlled separately,shadow frame was changed from ceramic to aluminum,the L-shape of shadow frame support was changed to T-shape,the separated type of shadow frame support was changed to the integrated type can be effectively improved.（2）For single side aggregation particles,It is found that loadlock I/O door and flap door,process chamber slit valve and grounding line,HDC roller brush and air knife are the main reasons.The frame of loadlock I/O door is removed,the area of stopper of the loadlock flap door is increased,the vibration damping design is adopted for slit valve,and the aluminum base of the grounding line is changed to nickel base or the aluminum base hourglass type design is adopted,the direct DI water of HDC roller brush unit is changed to direct water,and the singe type air knife of HDC is changed to double type can be effectively improved.（3）For long aggregate particles,it is found that process chamber susceptor grounding line,transfer chamber vacuum robot pad,and HDC are the main reasons.The anodizing process of changing grounding line fixed screw cap sulfuric acid method to oxalic acid method,susceptor split type to integrated type,transfer chamber vacuum robot pad fixed type to integrated pressing type,and the addition of lower brush cleaning before film deposition can be effectively improved.Optimization direction of process equipment management:It can be effectively improved by adding repair process for amorphous silicon film particle,adding particle control for diffuser using,adding gloss control for backing plate using,optimizing amorphous silicon film equipment maintenance process and equipment environmental management.