Research On Low-Loss Photoetchable Glass And Through-Glass-Via Technology

Interposer is the carrier of high-density interconnection and integrated passive components in three-dimensional integrated micro-systems.It is the key material to achieve three-dimensional integration and has the same significance as the silicon substrate of the Moore era.The photoetchable glass(PEG)as an interposer has become a research hotspot due to its advantages of adjustable thermal expansion and low process complexity relative to silicon and ceramics.However,due to the loss and integration of the photoetchable glass,its application range is limited.How to reduce the loss of the photolithographic glass and reduce the aperture to increase the degree of integration is an urgent problem to be solved.This dissertation is to study the above-mentioned problems:choose the Li-Al-Si system based photoetchable glass,design the basic formula according to the multi-ion coupling effect,and explore the neutralizing alkali effect,the suppression effect,the stabilization effect,and the The mechanism of oxygen capability in reducing loss of photoetchable glass;by optimizing the photosensitive performance and influencing parameters,a low-dielectric loss,highly integrated photoetchable glass was prepared,with a minimum dielectric loss of 0.0015 at 500 MHz and a through hole density up to 10000/cm².Main research results:Firstly,the Li-Al-Si system is selected as the main photoetchable glass system,and the photoetchable performance is achieved by adding a photosensitizer(Ce₂O₃),a nucleating agent(Ag₂O),and a reducing agent(Sb₂O₅).In this process,by increasing the content of photosensitizer and reducing agent to ensure the valence of the photosensitizer(Ce³⁺),the optimization of process parameters and process flow inhibited the crystallization of Li₂SiO₃ during the melting process,and successfully prepared photoetchable glass with photosensitive performance.And established a process platform for glass from melting to wafer finishing to through-hole forming.Secondly,it explores the internal connection between the suppression effect,stable shadow,oxygen supply capacity and loss reduction of the network modified body,network intermediate,and network forming body in the photolithographic glass.On the one hand,the network modifier hinders ion migration and reduces the thermal polarization and displacement polarization caused by the cation under an alternating electric field.On the other hand,it connects the non-bridging oxygen bonds generated by monovalent cations to achieve structural stability and balance,thereby reducing The dielectric loss of the photoetchable glass is found to have a minimum value of 0.003 when the content of CaO is 2%,and the mechanical strength reaches 90 MPa.The network intermediate(Al₂O₃)forms a[AlO₄]tetrahedron,which is connected to the[SiO₄]in the original glass network to form a ring structure.According to the principle of electrical neutrality,[AlO₄]will attract monovalent cations to balance the polarity of electricity.;At the same time,because the Al³⁺radius is larger than the Si⁴⁺ion radius,it will cause the spherical deformation of the adjacent O^2-,and the dielectric loss will be reduced under the alternating electric field.The study found that when the content of Al₂O₃ is 4%,the dielectric constant and dielectric loss are 5.0 and 0.0025,respectively.When the ratio of the network former(B₂O₃)to the alkali metal cation is less than 1,the glass network will be[BO₄]as the dominant one.Since the two[BO₄]cannot be directly connected,[BO₃]or[SiO₄]or cations are required In combination with it,the network structure of the glass is connected more closely,the migration of alkali metal cations is restricted,and the dielectric loss is reduced.The research results that when the B content is 2%,the dielectric loss is further reduced to 0.0015.Finally,through orthogonal experiments on the factors that affect the formation of photolithographic glass integration(through hole density)(including exposure energy,annealing temperature,annealing time,and etching time),the best conditions are obtained:exposure energy is 5 J/cm²,the annealing temperature is 565?,the annealing time is 45 min,the etching time is 12 min,the smallest through hole can reach 20?m,and the highest hole density can reach 10000/cm².Research on through-hole metallization of processed PEG samples.The seed layer is prepared by vapor deposition,the metallization in the hole is perfected by electroplating,and the surface copper is removed by mechanical polishing,and finally an interposer filled with the metal in the hole is obtained.The interposer laid a material foundation for the development of high-performance three-dimensional integrated microsystems.