Patent Document

CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the priority of Chinese patent application No. 201410198249.8, filed on May 12, 2014, the entirety of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention generally relates to the field of semiconductor technology and, more particularly, relates to chip packaging structures and treatment processes thereof. 
     BACKGROUND 
     In an IC chip packaging process, after certain steps, metal and/or metal ions may be deposited on the insulation layer between adjacent electrical connect structures, such as soldering balls (bumps), and soldering pads, etc. Such metal ions are generated by plasma etching processes, and/or wet etching processes, etc. For example, tin and/or tin ions may be deposited on the insulation layer between the adjacent tin soldering balls. Such metal and/or metal ions are able to cause a leakage current issue between the two adjacent electrical contact structures. Thus, the final test (FT) may fail. 
     In order to solve the FT failure caused by the deposition of the metal and/or metal ions, some technical approaches have been developed. For example, an argon plasma treatment process is performed on the insulation layer to remove the metal and/or the metal ions; and then the removed metal and/or metal ions are pumped away by the vacuum system of the plasma instrument. 
     However, in practical processes, using the argon plasma to remove the metal and/or metal ions has certain limitations because it is a physical process. The metal and/or metal ions may not be entirely removed. Further, the argon plasma may damage the surface of the dielectric layer. Thus, the leakage current may still be generated between adjacent electrical connect structures. The disclosed device structures and methods are directed to solve one or more problems set forth above and other problems. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     One aspect of the present disclosure includes a method for treating a chip packaging structure. The method includes providing a chip packaging structure having at least a first electrical connect structure and a second electrical connect structure, and an insulation layer insulating the first electrical connect structure and the second electrical connect structure and also exposing portions or all of the first electrical connect structure and the second electrical connect structure; and selecting a plasma gas based on materials of the first electrical connect structure and the second electrical connect structure and a type of process forming the first electrical connect structure and the second electrical connect structure, wherein metal cations are left on the insulation layer. Further, the method also includes performing a plasma treatment process using the selected plasma gas including one of at least oxygen and nitrogen on the first electrical connect structure, the second electrical connect structure and the insulation layer, causing reaction of the metal cations to substantially convert the metal cations into electrically neutral materials; and removing the reacted metal cations from the insulation layer. 
     Another aspect of the present disclosure includes a chip packaging structure. The chip packaging structure includes a substrate having a plurality of devices; and a metal interconnect structure electrically connecting with the devices formed on the substrate. Further, the chip packaging structure also includes at least one first electrical connect structure and one second electrical connect structure electrically connecting with the metal interconnect structure formed over the metal interconnect structure; and an insulation layer insulating the first electrical connect structure and the second electrical connect structure and also exposing portion or all of the first electrical connect structure and the second electrical connect structure, wherein the insulation has a material structure being treated by a plasma treatment process using a plasma gas, selected based on materials of the first electrical connect structure and the second electrical connect structure and a type of process forming the first electrical connect structure and the second electrical connect structure. 
     Other aspects of the present disclosure can be understood by those skilled in the art in light of the description, the claims, and the drawings of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a structure corresponding to certain stages of an exemplary treatment process of a chip packaging structure consistent with the disclosed embodiments; 
         FIG. 2  illustrates another structure corresponding to certain stages of the exemplary treatment process of a chip packaging structure consistent with the disclosed embodiments; 
         FIG. 3  illustrates another structure corresponding to certain stages of the exemplary treatment process of a chip packaging structure consistent with the disclosed embodiments; and 
         FIG. 4  illustrates the exemplary treatment process of a chip packaging structure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments of the invention, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIG. 4  illustrates an exemplary treatment process of a chip packaging structure; and  FIG. 1  illustrates a structure corresponding to certain stages of the exemplary treatment process of a chip packaging structure. 
     At the beginning of the treatment process, a chip packaging structure is provided (S 101 ). As shown in  FIG. 1 , a chip packaging structure  1  is provided. The chip packaging structure  1  may include a semiconductor substrate (not labeled), a metal interconnect structure  11 , an insulation layer  13 , a first electrical connect structure  121  and a second electrical connect structure  122 . In one embodiment, the first electrical connect structure  121  is a first solder pad  121 ; and the second electrical connect structure  122  is a second soldering pad  122 . A portion of the first soldering pad  121  and a portion of the second soldering pad  122  may be exposed by the insulation layer  13 . In certain other embodiments, the chip packaging structure  1  may have one electrical connect structure, or more than two electrical connect structures. 
     A plurality of semiconductor devices, such as transistors, resistors and inductors, etc., may be formed in and/or on the substrate. The first soldering pad  121  and the second soldering pad  122  may be electrically connected with the semiconductor devices through the metal interconnect structure  11 . The first soldering pad  121  and the second soldering pad  122  may be electrically insulated by the insulation layer  13 . 
     The substrate may be made of any appropriate material, such as Si, Ge, SiGe, or glass, etc. The insulation material of the metal interconnect structure  11  may be made of silicon oxide, silicon nitride, or silicon oxynitride, etc. The metal material of the metal interconnect structure  11  may be made of Cu, W, or Al, etc. 
     The insulation layer  13  may be made of any appropriate material, such as silicon oxide, silicon nitride, or silicon oxynitride, etc. In one embodiment, the insulation layer  13  may be a passive layer to prevent moisture, or contaminations, etc. Thus, the insulation layer  13  may be made of silicon nitride. 
     In certain other embodiments, the metal of the soldering pads may have a relatively large stress. The stress may cause the dielectric layer of the metal interconnect structure  11  to crack. Thus, in order to avoid the crack, the insulation layer  13  may be made of polyimide. 
     The first soldering pad  121  and the second soldering pad  122  may be formed by any appropriate process. In one embodiment, the first soldering pad  121  and the second soldering pad  122  may be formed by forming a metal layer (not labeled) on the metal interconnect structure  11 . The metal layer may be made of any appropriate material, such as Cu, or Al, etc. The metal layer may electrically connect with the metal interconnect structure  11 . After forming the metal layer, the metal layer may be patterned by any appropriate processes to form the first soldering pad  121  and the second soldering pad  122 . In one embodiment, the metal layer may be patterned by a dry etching process. 
     During the dry etching process, the by-products may not be entirely removed. Thus, the copper cations, metal losing a certain number of electrons, or the aluminum cations may be deposited on the insulation layer  13 . The metal cations deposited on the insulation layer  13  may cause a leakage current issue between the first soldering pad  121  and the second soldering pad  122  when the IC chip is in operation. 
     Returning to  FIG. 4 , after providing the chip packaging structure  1 , a plasma gas may be selected for performing a plasma treatment process to remove the metal cations left on the insulation layer  13  (S 102 ). The plasma gas may selected based on materials of the first soldering pad  121  and the second soldering pad  122  and a type of process forming the first soldering pad  121  and the second soldering pad  122 . For example, if the first soldering pad  121  and the second soldering pad  122  are made of Cu, O 2  may be selected as the plasma gas. If the first soldering pad  121  and the second soldering pad  122  are made of Al, N 2  may be selected as the plasma gas. 
     Further, after selecting the plasma gas, a plasma treatment process may be performed (S 103 ). The corresponding structure is referred to  FIG. 1 . 
     Referring to  FIG. 1 , a plasma treatment process is performed on the first soldering pad  121 , the second soldering pad  122 , and the insulation layer  13  to remove the metal cations left on the insulation layer  13 . Specifically, selected plasma, i.e., plasma using the selected plasma gas may be used to bombard the first soldering pad  121 , the second soldering pad  122 , and the insulation layer  13  exposing the first soldering pad  121  and the second soldering pad  122  to remove the metal cations. 
     In one embodiment, the plasma gas is O 2 . Thus, the plasma may be referred as oxygen plasma. The O 2  pressure in the reaction chamber of the oxygen plasma may be in a range of approximately 1E10 −9  Pa˜1E10 −6  Pa. The voltage of the oxygen plasma may be in a range of approximately 900V˜1100V. The frequency of the oxygen plasma may be in a range of approximately 45 Hz˜55 Hz. 
     During the oxygen plasma treatment process, O 2  may be ionized into O ions and electrons “e”, etc. The O ions and the electrons may neutralize, and/or react with metal cations. The following reactions may happen:
 
Cu 2+ +O+2 e →Cu+O
 
Cu e+ +O+2 e →CuO
 
     The metal Cu and the CuO may be electrically neutral. Thus, the metal Cu and the CuO may not have an electrostatic attraction with the insulation layer  13 ; and the metal Cu and the CuO may be easy to be removed from the surface of the insulation layer  13 . Further, the metal Cu and the CuO is not re-deposited on the insulation layer  13 . Thus, it may only need to pump the reaction chamber to remove the metal Cu and the CuO out the reaction chamber. 
     In one embodiment, the flow rate of O 2  may be in a range of approximately 5 sccm˜25 sccm. Such a flow rate may aid the generated O ions and/or electrons to react with the metal cations to form metal and/or metal compounds. 
     The plasma treatment time may be in a range of approximately 100 s˜150 s. In one embodiment, the treatment time is 120 s. Such a treatment time may not only entirely neutralize the metal cations to form metal and/or metal compounds, but also avoid damage to the surface of the insulation layer  13  during the bombarding process on the surfaces of the first soldering pad  121 , the second soldering pad  122 , and the insulation layer  13 . 
     In certain other embodiments, the plasma gas is N 2 . Thus, the plasma may be referred as nitrogen plasma. The pressure of N 2  in the reaction chamber of the nitrogen plasma may be in a range of approximately 1E10 −9  Pa˜1E10 −6  Pa. The voltage of the nitrogen plasma may be in a range of approximately 900V˜1100V. The frequency of the nitrogen plasma may be in a range of approximately 45 Hz˜55 Hz. The power of the nitrogen plasma may be in a range of approximately 270 W˜330 W. 
     In the nitrogen plasma treatment process, N 2  may be ionized into N ions and electrons “e”, etc. The N ions and the electrons “e” may have following reactions with the metal cations on the surface of the insulation layer  13 :
 
Al 3+ +N+3 e →Al+N
 
Al 3+ +N+3 e →AlN
 
     The metal Al and the AlN may be electrically neutral. Thus, the metal Al and the AlN may have no electrostatic attraction with the insulation layer  13 ; and it may be easy for the metal Al and the AlN to leave the surface of the dielectric layer  13 . Further, the metal Al and the AlN is not re-deposited on the surface of the dielectric layer  13 . Thus, it may only need to pump the reaction chamber to remove the metal Al and the AlN out the reaction chamber. 
     In one embodiment, the flow rate of N 2  may be in a range of approximately 5 sccm˜25 sccm. Such a flow rate of N 2  may aid the N ions and the electrons generated by the plasma to react with the metal cations to form the metal Al and/or the AlN to remove the metal cations. 
     In one embodiment, the nitrogen plasma treatment time may be in a range of approximately 100 s˜150 s. Such a treatment time may not only neutralize the metal cations to form the metal and/or the metal compounds; but also avoid damage to the surface of the insulation layer  13  during the nitrogen plasma treatment process. 
     Returning to  FIG. 4 , when the plasma treatment process is being performed, the reacted metal cations may be removed (S 104 ). The reacted metal cations are removed by pumping the reaction chamber. 
     After the plasma treatment process using one or more of O 2  and N 2 , the metal cations may be removed. Thus, the leakage issue between the first soldering pad  121  and the second soldering pad  122  may be overcome. Further, by using the oxygen plasma or the nitrogen plasma, the damage to the surface of the insulation layer  13  and the metal interconnect structure  11  may be avoided. Therefore, the reliability of the chip packaging structure  1  may be improved. 
       FIG. 2  illustrates another structure corresponding to a certain stage of the exemplary treatment process of a chip packaging structure illustrated in  FIG. 4 . At the beginning of the treatment process, a chip packaging structure is provided (S 101 ). 
     As shown in  FIG. 2 , a chip packaging structure  2  is provided. In one embodiment, the chip packaging structure  2  is formed by forming a second metal interconnect structure  14  on the chip packaging structure  1  illustrated in  FIG. 1 ; and then forming a first electrical connect structure  151  and a second electrical connect structure  152  on the second metal interconnect structure  14 . In one embodiment, the first electrical connect structure  151  is a first re-distribution layer  151 ; and the second electrical connect structure  152  is a second re-distribution layer  152 . The first re-distribution layer  151  may be electrically connected with the first soldering pad  121  through the second metal interconnect structure  14 . The second re-distribution layer  152  may be electrically connected with the second soldering pad  122  through the second metal interconnect structure  14 . 
     Further, portions of the first re-distribution layer  151  and the second re-distribution layer  152  may be exposed by the insulation layer  13 . The insulation layer  13  may also electrically insulate the first redistribution layer  151  and the second re-distribution layer  152 . In certain other embodiments, the chip packaging structure  2  may include one re-distribution layer, or more than two re-distribution layers. 
     The first re-distribution layer  151  and the second re-distribution layer  152  may be used to electrically re-distribute the first soldering pad  121  and the second soldering pad  122 . Specifically, the positions of the first soldering pad  121  and the second soldering pad  122  and the distance between the first soldering pad  121  and the second soldering pad  122  may be re-arranged by the first re-distributing pad  151  and the second re-distributing pad  152 . Such as re-distribution may increase the device density in the chip packaging structure  2 . 
     The insulation material of the second metal interconnect structure  14  may be made of silicon oxide, silicon nitride, or silicon oxynitride, etc. The metal material of the second metal interconnect structure  14  may be made of Cu, W, or Al, etc. 
     The insulation layer  13  may be made of any appropriate material, such as silicon oxide, silicon nitride, or silicon oxynitride, etc. In one embodiment, the insulation layer  13  may be a passive layer to prevent moisture, or contaminations, etc. Thus, the insulation layer  13  may be made of silicon nitride. 
     In certain other embodiments, the metal of the soldering pads may have a relatively large stress. The stress may cause the dielectric layer in the metal interconnect structure  13  to crack. Thus, in order to avoid the crack, the insulation layer  13  may be made of polyimide. 
     The first re-distribution layer  151  and the second re-distribution layer  152  may be formed by any appropriate process. In one embodiment, the first re-distribution layer  151  and the second re-distribution layer  152  may be formed by forming a metal layer (not labeled) on the second metal interconnect structure  14 . The metal layer may be made of one of Cu and Al, etc. The metal layer may be electrically connected with the second metal interconnect structure  14 . After forming the metal layer, the metal layer may be patterned by any appropriate processes to form the first re-distribution layer  151  and the second re-distribution layer  152 . In one embodiment, the metal layer may be patterned by a dry etching process. 
     During the dry etching process, the by-products may not be entirely removed. Thus, copper cations or aluminum cations may be deposited on the insulation layer  13 . The metal cations deposited on the insulation layer  13  may cause a leakage issue between the first re-distribution layer  151  and the second re-distribution layer  152 . 
     Returning to  FIG. 4 , after providing the chip packaging structure  1 , a plasma gas may be selected for performing a plasma treatment process to remove the metal cations left on the insulation layer  13  (S 102 ). The plasma gas may selected based on materials of the first re-distribution layer  151  and the second redistribution layer  152  and a type of process forming the first re-distribution layer  151  and the second re-distribution layer  152 . For example, if the first re-distribution layer  151  and the second re-distribution layer  152  are made of Cu, O 2  may be selected as the plasma gas. If the first re-distribution layer  151  and the second re-distribution layer  152  are made of Al, N 2  may be selected as the plasma gas. 
     Further, after selecting the plasma gas, a plasma treatment process may be performed (S 103 ). The corresponding structure is referred to  FIG. 2 . 
     Referring to  FIG. 2 , after providing the chip packaging structure  2 , a plasma treatment process is performed on surface of the chip packaging structure  2 . Specifically, selected plasma may be used to bombard the first re-distribution layer  151 , the second re-distribution layer  152  and the insulation layer  13  exposing first re-distribution layer  151  and the second re-distribution layer  152 . 
     In one embodiment, the plasma gas is O 2 . Thus, the plasma may be referred as oxygen plasma. The O 2  pressure in the reaction chamber of the oxygen plasma treatment process may be in a range of approximately 1E10 −9  Pa˜1E10 −6  Pa. The voltage of the plasma may be in a range of approximately 900V˜1100V. The frequency of the oxygen plasma may be in range of approximately 45 Hz˜55 Hz. 
     During the oxygen plasma process, the O 2  may be ionized into O ions and electrons “e”, etc. The O ions and the electrons “e” may react with metal cations. The following reactions may happen:
 
Cu 2+ +O+2 e →Cu+O
 
Cu 2+ +O+2 e →CuO
 
     The metal Cu and the CuO may be electrically neutral. Thus, the metal Cu and the CuO may not have an electrostatic attraction with the insulation layer  13 ; and the metal Cu and the CuO may be easy to be removed from the surface of the insulation layer  13 . Further, the metal Cu and the CuO is not re-deposited on the insulation layer  13 . Thus, it may only need to pump the reaction chamber to remove the Cu and the CuO out the reaction chamber. 
     In one embodiment, the flow rate of O 2  may be in a range of approximately 5 sccm˜25 sccm. Such a flow rate may aid the generated O ions and/or electrons to react with the metal cations to form the metal and/or the metal compounds. 
     The oxygen plasma treatment time may be in a range of approximately 100 s˜150 s. In one embodiment, the oxygen plasma treatment time is 120 s. Such a treatment time may not only entirely neutralize the metal cations to form metal and/or metal compounds, but also avoid damage to the surface of the insulation layer  13  during the bombarding process on the surface of the insulation layer  13 . 
     In certain other embodiments, the gas of the plasma is N 2 . Thus, the plasma may be referred as nitrogen plasma. The pressure of N 2  in the reaction chamber may be in a range of approximately 1E10 −9  Pa˜1E10 −6  Pa. The voltage of the nitrogen plasma may be in a range of approximately 900V˜1100V. The frequency of the nitrogen plasma may be in a range of approximately 45 Hz˜55 Hz. The power of the nitrogen plasma may be in a range of approximately 270 W˜330 W. 
     In the nitrogen plasma treatment process, N 2  may be ionized in to N ions and electrons “e”, etc. The N ions and the electrons “e” may have following reactions with the metal cations on the surface of the insulation layer  13 :
 
Al 3+ +N+3 e →Al+N
 
Al 3+ +N+3 e →AlN
 
     The metal Al and the AlN may be electrically neutral. Thus, the metal Al and the AlN may have no electrostatic attraction with the insulation layer  13 ; and it may be easy for the metal Al and the AlN to leave the surface of the dielectric layer  13 . Further, the metal Al and the AlN may not be re-deposited on the surface of the dielectric layer  13 . Thus, it may only need to pump the reaction chamber to remove the metal Al and the AlN out the reaction chamber. 
     In one embodiment, the flow rate of N 2  may be in a range of approximately 5 sccm˜25 sccm. Such a flow rate of N 2  may aid the N ions and the electrons generated by the nitrogen plasma to react with the metal cations to form the metal Al and/or the AlN. 
     In one embodiment, the nitrogen plasma treatment time may be in a range of approximately 100 s˜150 s. Such a treatment time may not only neutralize the metal cations to form the metal and/or the metal compounds; but also avoid the damage to the surface of the insulation layer  13  during the nitrogen plasma treatment process. 
     Returning to  FIG. 4 , when the plasma treatment process is being performed, the reacted metal cations may be removed ( 104 ). The reacted metal cations is removed by pumping the reaction chamber 
     After the plasma treatment process using one of O 2  and N 2 , the metal cations on the insulation layer  13  may be removed. Thus, the leakage current issue between the first re-distribution layer  151  and the second re-distribution layer  152  may be overcome. Further, by using the O 2  plasma or the N 2  plasma, the damage to the surface of the insulation layer  13  may be avoided. Therefore, the reliability of the chip packaging structure  2  may be improved. 
       FIG. 3  illustrates another structure corresponding to certain stages of the exemplary treatment process of a chip packaging structure illustrated in  FIG. 4 . At the beginning of the treatment process, a chip packaging structure is provided (S 101 ). 
     As shown in  FIG. 3 , a chip packaging structure  3  having a first electrical connect structure  171  and a second electrical connect structure  172  is provided. In one embodiment, the first electrical connect structure  171  may be a first soldering ball  171 ; and the second electrical connect structure  172  may be a second soldering ball  172 . In certain other embodiments, the number of the soldering balls may be more than two. 
     In one embodiment, the chip packaging structure  3  may be formed by forming certain structures on the chip packaging structure  1  illustrated in  FIG. 1 . Referring to  FIG. 1  and  FIG. 3 , a first under-ball metal (UBM) layer  161  may be formed on the first soldering pad  121  and a portion of the insulation layer  13 . Further, a second under ball metal (UBM) layer  162  may be formed on the second soldering pad  122  and a portion of the insulation layer  13 . Further, after forming the first UBM layer  161  and the second UBM layer  162 , a first soldering ball (bump)  171  may be formed on the first UBM layer  161 ; and a second soldering ball  172  may be formed on the second UBM layer  162 . 
     The first soldering ball  171  may be electrically connected with the first solder pad  121  through the first UBM layer  161 ; and the second soldering ball  172  may be electrically connected with the second soldering pad  122  through the second UBM layer  162 . The insulation layer  13  may electrically insulate the first soldering pad  121  and the second solder pad  122 , the first UBM layer  161  and the second UBM layer  162 ; and the first soldering ball  171  and the second soldering ball  172 . 
     The insulation layer  13  may be made of any appropriate material, such as silicon oxide, silicon nitride, or silicon oxynitride, etc. In one embodiment, the insulation layer  13  may be a passive layer to prevent moisture, or contaminations, etc. Thus, the insulation layer  13  may be made of silicon nitride. 
     In certain other embodiments, the metal of the soldering pads may have a relatively large stress. The stress may cause the dielectric layer of the metal interconnect structure  13  to crack. Thus, in order to avoid the crack, the insulation layer  13  may be made of polyimide. 
     The first UBM layer  161  and the second UBM layer  162  may be formed by any appropriate process. In one embodiment, the UBM layer  161  and the second UBM layer  162  may be formed by forming a metal layer (not labeled) on the first soldering pad  121 , the second soldering pad  122  and the insulation layer  13 . The metal layer may electrically connect with the first soldering pad  121  and the second soldering pad  122 . After forming the metal layer, the metal layer may be patterned by any appropriate processes to form the first UBM layer  161  and the second UBM layer  162 . In one embodiment, the metal layer may be patterned by a dry etching process. 
     The metal layer may be made of Ti or Cu, etc. During the dry etching process, the by-products may not be entirely removed. Thus, Ti cations or Cu cations may be deposited on the surface of the insulation layer  13 . Further, the first soldering ball  171  and the second soldering ball  172  may be made of Cu, Sn, or Ag, etc. Thus, during the process for forming the first soldering ball  171  and the second soldering ball  172 , Cu cations, Sn cations, or Ag cations may also be formed on the insulation layer  13 . The metal cations deposited on the insulation layer  13  may cause a leakage issue between the first soldering ball  171  and the second soldering ball  172 . 
     In certain other embodiments, the first soldering ball  171  and the second soldering ball  172  may be formed on the chip packaging structure  2  illustrated in  FIG. 2 . Correspondingly, the first UBM layer  161  may be formed on the first re-distribution layer  151 ; and the second UBM layer  162  may be formed on the second re-distribution layer  152 . Then, the first soldering ball  171  may be formed on the first UBM layer  161 ; and the second soldering ball  172  may be formed on the second re-distribution layer  152 . Such a chip packaging structure may increase the device density. Similarly, metal cations may be formed on the insulation layer  13  during the processes for forming the first UBM layer  161 , the second UBM layer  162 , the first soldering ball  171  and the second soldering ball  172 . The metal cations may cause a leakage current issue between the first soldering ball  171  and the second soldering ball  172 . 
     Returning to  FIG. 4 , after providing the chip packaging structure  1 , a plasma gas may be selected for performing a plasma treatment process to remove the metal cations left on the insulation layer  13  (S 102 ). The plasma gas may selected based on materials of the first UBM layer  161 , the second UBM  162 , the first soldering ball  171  and the second soldering ball  172  and a type of process forming the first UBM layer  161 , the second UBM  162 , the first soldering ball  171  and the second soldering ball  172 . For example, if the first UBM layer  161 , the second UBM  162 , the first soldering ball  171  and the second soldering ball  172  are made of Cu, Sn, Ti or Ag, O 2  may be selected as the plasma gas. If the first UBM layer  161 , the second UBM  162 , the first soldering ball  171  and the second soldering ball  172  are made of Al, or Ti, N 2  may be selected as the plasma gas. 
     Further, after selecting the plasma gas, a plasma treatment process may be performed ( 103 ). The corresponding structure is referred to  FIG. 2 . 
     Referring to  FIG. 3 , a plasma treatment process is performed on the surface of the chip packaging structure  3  to remove the metal cations. Specifically, selected plasma, i.e., plasma using the selected plasma gas, may be used to bombard the first soldering ball  171 , the second soldering ball  172 , and the insulation layer  13 . 
     In one embodiment, the plasma gas is O 2 . Thus, the plasma may be referred as oxygen plasma. The O 2  pressure in the reaction chamber of the oxygen plasma treatment process may be in a range of approximately 1E10 −9  Pa˜1E10 −6  Pa. The voltage of the oxygen plasma may be in a range of approximately 900V˜1100V. The frequency of the oxygen plasma may be in range of approximately 45 Hz˜55 Hz. 
     During the oxygen plasma process, the O 2  may be ionized into O ions and electrons “e”, etc. The O ions and the electrons “e” may react with metal cations. The following reactions may happen:
 
Cu 2+ +O+2 e →Cu+O
 
Cu 2+ +O+2 e →CuO
 
     The metal Cu and the CuO may be electrically neutral. Thus, the metal Cu and the CuO may not have an electrostatic attraction with the insulation layer  13 ; and the metal Cu and the CuO may be easy to be removed from the surface of the insulation layer  13 . Further, the metal Cu and the CuO are not re-deposited on the insulation layer  13 . Thus, it may only need to pump the reaction chamber to remove the Cu and the CuO. 
     In certain other embodiments, if the first soldering ball  171  and the second soldering ball  172  are made of Sn, or Ag, corresponding metal and metal oxide may be formed during the plasma treatment process; and may be removed by pumping the reaction chamber. Further, the Ti cations caused by the process for forming the first UBM layer  161  and the second UBM layer  162  may be also be removed by the oxygen plasma treatment process. 
     In one embodiment, the flow rate of O 2  may be in a range of approximately 5 sccm˜25 sccm. Such a flow rate may aid the generated O ions and electrons to react with the metal cations to form the metal and/or the metal compounds. 
     The oxygen plasma treatment time may be in a range of approximately 100 s˜150 s. In one embodiment, the treatment time is 120 s. Such a treatment time may not only ensure entirely neutralize the metal cations to form metal and/or metal compounds, but also avoid damage to the surface of insulation layer  13  during the process for bombarding first soldering ball  171 , the second soldering ball  171 , and the insulation layer  13 . 
     In certain other embodiments, the gas of the plasma is N 2 . Thus, the plasma may be referred as nitrogen plasma. The pressure of N 2  in the reaction chamber may be in a range of approximately 1E10 −9  Pa˜1E10 −6  Pa. The voltage of the nitrogen plasma may be in a range of approximately 900V˜1100V. The frequency of the nitrogen plasma may be in a range of approximately 45 Hz˜55 Hz. The power of the nitrogen plasma may be in a range of approximately 270 W˜330 W. 
     In the nitrogen plasma treatment process, N 2  may be ionized into N ions and electrons “e”, etc. The N ions and the electrons “e” may neutralize the Sn ions, Cu ions, Ti ions or Ag ions, etc., to form neutral metal or metal nitride, etc. The metal and the metal nitride may have no electrostatic attraction with the insulation layer  13 ; and it may be easy for the metal and the metal nitride to leave the surface of the insulation layer  13 . Further, the metal and the metal nitride are not re-deposited on the surface of the insulation layer  13 . Thus, it may only need to pump the reaction chamber to remove the metal and the metal nitride out the reaction chamber. 
     In one embodiment, the flow rate of N 2  may be in a range of approximately 5 sccm˜25 sccm. Such a flow rate of N 2  may aid the N ions and the electrons generated by the nitrogen plasma process to react with the metal cations to form the metal and the metal nitride. 
     In one embodiment, the nitrogen plasma treatment time may be in a range of approximately 100 s˜150 s. Such a treatment time may not only neutralize the metal cations to form the metal and/or the metal compounds; but also avoid damage to the surface of insulation layer  13  during the plasma treatment process. 
     Returning to  FIG. 4 , when the plasma treatment process is being performed, the reacted metal cations may be removed ( 104 ). The reacted metal cations are removed by pumping the reaction chamber 
     After the plasma treatment process using one of O 2  and N 2 , the metal cations may be removed. Thus, the leakage current issue between the first soldering ball  171  and the second soldering ball  172  may be overcome. Further, by using the oxygen plasma or the nitrogen plasma, the damage to the surface of the insulation layer  13  may be avoided. Therefore, the reliability of the chip packaging structure may be improved. 
     Returning  FIG. 4 , after the plasma treatment process, further processes may be performed, such as a wire bonding process, or a soldering process, etc. Then, molding compound may be applied on the chip packaging structure to sealing the devices, the wire, and soldering structures, etc. 
     Thus, a chip packaging structure may be formed by the above disclosed processes and methods; and the corresponding semiconductor structure is illustrated in  FIG. 3 . As shown in  FIG. 3 , the chip packaging structure may include a substrate (not labeled) and a metal interconnect structure  11  electrically connecting with devices in the substrate formed on the substrate. The chip packaging structure may also include a first soldering pad  121  and a second soldering pad  122  electrically connecting with the metal interconnect structure  11  formed on the first interconnect structure  11 ; and an insulation layer  13  electrically insulating the first soldering pad  121  and the second soldering pad  122  formed on the first metal interconnect structure  11 . The insulation layer  13  is treated by oxygen plasma or nitrogen plasma to remove the metal cations on the surface. Further, the chip packaging structure may include a first UBM layer  161  formed on the first soldering pad  121 , and a second UBM layer  162  formed on the second soldering pad  122 . Further, the chip packaging structure may also include a first soldering ball  171  formed on the first UBM layer  161 ; and a second soldering ball  172  formed on the second UBM layer  162 . The detailed structures and intermediate structures are described above with respect to the fabrication and treatment processes. 
     Therefore, according to the disclosed methods and structures, instead of using ordinary argon plasma, oxygen plasma or nitrogen plasma may be used to bombard the plurality of electrical connect structures and the insulation layer exposing the electrical connect structure. During the plasma treatment process, oxygen ions and electrons or nitrogen ions and electrons may neutralize and/or react with the metal cations deposited on the insulation layer during the packaging process. Thus, metal atoms and/or metal compounds may be formed. The metal atoms and the metal compounds may be electrically neutral. Thus, the metal atoms and/or the metal compounds may have no electrostatic attraction with the insulation layer; and it may be easy for the metal atoms and/or the metal compounds to leave the surface of the insulation layer. Further, it is not easy for the metal and/or the metal compounds to be re-deposited on the insulation layer. Thus, it may only need to pump the reaction chamber to remove the metal atoms and/or the metal compounds out the reaction chamber. 
     Further, the electrical connect structures may include any appropriate structures, such as soldering pads, re-distribution layers, under-ball metal layers, and soldering balls, etc. Metal ions may be formed on the insulation layer during the process for forming any of such structures. Thus, the plasma treatment process may be performed on one or more of such structures and the insulation layer to neutralize the metal cations to form metal atoms and/or metal compounds. After the plasma treatment process using the oxygen plasma or the nitrogen plasma, the metal cations formed on the insulation layers may be removed; and the surface of the insulation layer may not be damaged. Therefore, the leakage current issue between the electrical connect structures may be overcome; and the reliability of the chip packaging structure may be improved. 
     The above detailed descriptions only illustrate certain exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention. Those skilled in the art can understand the specification as whole and technical features in the various embodiments can be combined into other embodiments understandable to those persons of ordinary skill in the art. Any equivalent or modification thereof, without departing from the spirit and principle of the present invention, falls within the true scope of the present invention.

Technology Category: 5