Abstract:
A method for fabricating a electronic device package provides a electronic device chip, wherein the electronic device chip includes a semiconductor substrate having a front side and a back side, wherein the semiconductor substrate has a first thickness, an electronic component disposed on the front side of the semiconductor substrate, and an interconnect structure disposed on the electronic component. The method further performs a thinning process to remove a portion of the semiconductor substrate from the back side thereof The method then removes a portion of the thinned semiconductor substrate and a portion of a dielectric layer of the interconnect structure from a back side of the thinned semiconductor substrate until a first metal layer pattern of the interconnect structure is exposed, thereby forming a through hole. Finally, the method forms a TSV structure in the through hole, and mounts the electronic device chip on a base.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of pending U.S. patent application Ser. No. 13/790,060, filed on Mar. 8, 2013, which claims the benefit of U.S. Provisional Application No. 61/698,450, filed on Sep. 7, 2012, the entireties of which are incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a radio-frequency (RF) device package and a method for fabricating the same, and in particular, to a radio-frequency (RF) device package with improved RF loss and linearity performances and a method for fabricating the same. 
         [0004]    2. Description of the Related Art 
         [0005]    In high speed applications (e.g. radio-frequency (RF) applications), the conventional RF device package comprises several discrete RF chips and other active or passive devices (such as power amplifiers (PAs), filters, decoupling and matching circuits) mounted on an RF main die by a wire bonding method. However, the conventional RF device package suffers from loss and low linearity problems because ground (GND) planes of the wire-bonding RF chips are designed to contact to the RF main die. 
         [0006]    Thus, a novel RF device package with improved RF loss and linearity performances is desirable. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    A radio-frequency (RF) device package and a method for fabricating the same are provided. An exemplary embodiment of a radio-frequency (RF) device package includes a base, wherein a radio-frequency (RF) device chip is mounted on the base. The RF device chip includes a semiconductor substrate having a front side and a back side. A radio-frequency (RF) component is disposed on the front side of the semiconductor substrate. An interconnect structure is disposed on the RF component, wherein the interconnect structure is electrically connected to the RF component, and a thickness of the semiconductor substrate is less than that of the interconnect structure. A through hole is formed through the semiconductor substrate from the back side of the semiconductor substrate, and is connected to the interconnect structure. A TSV structure is disposed in the through hole. 
         [0008]    An exemplary embodiment of a method for fabricating a radio-frequency (RF) device package includes providing a radio-frequency (RF) device chip. The RF device chip includes a semiconductor substrate having a front side and a back side, wherein the semiconductor substrate has a first thickness. A radio-frequency (RF) component is disposed on the front side of the semiconductor substrate. An interconnect structure is disposed on the RF component, wherein the interconnect structure is electrically connected to the RF component. A thinning process is performed to remove a portion of the semiconductor substrate from the back side thereof, thereby forming a thinned semiconductor substrate having a second thickness less than the first thickness. A portion of the thinned semiconductor substrate and a portion of a dielectric layer of the interconnect structure are removed from a back side of the thinned semiconductor substrate until a first metal layer pattern of the interconnect structure is exposed, thereby forming a through hole. A TSV structure is formed in the through hole. The RF device chip is mounted on a base, wherein the back side of the thinned semiconductor substrate is closer to the base than a front side of the thinned semiconductor substrate. 
         [0009]    A detailed description is given in the following embodiments with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0011]      FIGS. 1-7  are cross sections of one exemplary embodiment of a method for fabricating a radio-frequency (RF) device package of the invention. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0012]    The following description is a mode for carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. Wherever possible, the same reference numbers are used in the drawings and the descriptions to refer the same or like parts. 
         [0013]    The present invention will be described with respect to particular embodiments and with reference to certain drawings, but the invention is not limited thereto and is only limited by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual dimensions to practice the invention. 
         [0014]      FIGS. 1-7  are cross sections of one exemplary embodiment of a method for fabricating a radio-frequency (RF) device package  500  of the invention. In this embodiment, the RF device package  500  is fabricated with through silicon via (TSV) technology. As shown in  FIG. 1 , a radio-frequency (RF) device chip  300  is provided. In one embodiment, the RF device chip  300  may comprise a semiconductor substrate  200  having a front side  222  and a back side  224 . In one embodiment, the semiconductor substrate  200  may comprise silicon. In alternative embodiments, a SiGe, bulk semiconductor, strained semiconductor, compound semiconductor, silicon on insulator (SOI), or other commonly used semiconductor substrates are used as the semiconductor substrate  200 . The semiconductor substrate  200  may have a desired conductive type by implanting p-type or n-type impurities therein. A radio-frequency (RF) component  202  is disposed on the front side  222  of the semiconductor substrate  200 . As shown in  FIG. 1 , the RF component  202  is isolated from the other devices (not shown) by shallow trench isolation (STI) features  201  formed in the semiconductor substrate  200 . An interconnect structure  220  is formed on the front side  201  of the semiconductor substrate  200 . In one embodiment, the interconnect structure  220  may be constructed by dielectric layers  204 ,  208 , and  212  and metal layer patterns  206 , and  210 . The interconnect structure  220  may be used for input/output (I/O) connections of signals or a ground (GND) for the RF component  202 . Therefore, signals or ground (GND) terminals may be formed in the interconnect structure  220 . In one embodiment, the metal layer patterns  206 , and  210  of the interconnect structure  220  are electrically connected to the RF component  202 . In one embodiment as shown in  FIG. 1 , the metal layer patterns  210  are disposed at a top level and the metal layer patterns  206  are disposed at a lower-to-top level of the interconnect structure  220 . The number of the dielectric layers and metal layer patterns is defined by design for the RF component  202  and the scope of the invention is not limited thereto. In one embodiment as shown in  FIG. 1 , a thickness T1 of the semiconductor substrate  200  is larger than a thickness T2 of the interconnect structure  220 . 
         [0015]    Next, as shown in  FIG. 2 , the RF device chip  300  may be flipped so that the back side  224  of the semiconductor substrate  200  is facing upward. Next, a thinning process is performed to remove a portion of the semiconductor substrate  200  (as shown in  FIG. 1 ) from the back side  224  (as shown in  FIG. 1 ) of the semiconductor substrate  200  to reduce a thickness of the semiconductor substrate  200 . In one embodiment, the thinning process may comprise a chemical mechanical polishing (CMP) process. After performing the thinning process, a thinned semiconductor substrate  200   a  is formed. In one embodiment, the thinned semiconductor substrate  200   a  has a thickness T3 less than the thickness T1 of the semiconductor substrate  200  as shown in  FIG. 1 . In this embodiment, the thickness T3 of the thinned semiconductor substrate  200   a  may be designed to be between 20 nm to 50 nm to prevent the semiconductor substrate  200   a  from cracking. Also, the thickness T3 of the thinned semiconductor substrate  200   a  may be designed to be less than the thickness T2 of the interconnect structure  220 . 
         [0016]    Next, a TSV process is performed for the RF device chip  300  as shown in  FIGS. 3-5 . As shown in  FIG. 3 , a trench opening process, such as a laser drilling process, is performed to remove a portion of the thinned semiconductor substrate  200   a  and a portion of the dielectric layer  204  of the interconnect structure from a back side  224   a  of the thinned semiconductor substrate  200   a  until the metal layer patterns  206  of the interconnect structure  220  is exposed, thereby forming through holes  230 . In one embodiment, the through holes  230  define formation positions of subsequently formed TSV structures. 
         [0017]    Next, as shown in  FIG. 4 , an insulating liner  236  is conformably formed on a bottom  234  and a sidewall  232  of each of the through holes  230  by a disposition, photolithography and patterning process. Also, the insulating liner  236  covers a portion of the metal layer patterns  206  of the interconnect structure  220 . 
         [0018]    Next, as shown in  FIG. 5 , an etching process is performed to remove the insulating liner  236  on the bottom  234  of the through hole  230 , thereby forming an insulating liner  236   a.  In one embodiment, the etching process may comprise a dry etching process or a wet etching process. Next, a conductive material is filled in the through hole  230  to form a conductive via plug  238 . As shown in  FIG. 5 , the conductive via plug  238  covers a sidewall of the insulating liner  236 . After forming the conductive via plug  238 , a TSV structure  240  comprises the insulating liner  236   a  and the conductive via plug  238  surrounded by the insulating liner  236   a  is formed in the through hole  230 . In this embodiment, the TSV structure  240  is electrically connected to the metal layer patterns  206  at the lower-to-top level of the interconnect structure  220 . 
         [0019]    Next, as shown in  FIG. 6 , a bumping process is performed to form a conductive bump  242  on an end  241  of the TSV structure  240  close to the back side  224   a  of the thinned semiconductor substrate  200   a.  In one embodiment, the conductive bump  242  may comprise a solder bump, metal pillar or combinations thereof. 
         [0020]    Next, as shown in  FIG. 7 , the RF device chip  300  may be flipped again so that the back side  224  of the semiconductor substrate  200  faces downward. Next, a mounting process is performed to mount the RF device chip  300  on a base  250 . As shown in  FIG. 7 , the conductive bump  242  connects to the base  250  after mounting the RF device chip  300  on the base  250 . In one embodiment, the base  250  may comprise a main die or a printed circuit board (PCB). In one embodiment, the back side  224   a  of the thinned semiconductor substrate  200   a  is closer to the base  250  than the front side  222  of the thinned semiconductor substrate  200   a.  A distance d between the RF component  202  and the base  250  is the same as a total thickness T3 of the thinned semiconductor substrate  200   a  and the height H of the conductive bump  242 . After the aforementioned processes, one exemplary embodiment of a radio-frequency (RF) device package  500  is fabricated completely. 
         [0021]    Alternatively, the RF device chip  300  the radio-frequency (RF) device package  500  may further comprise a passive component  246  disposed in the interconnect structure  220 . In one embodiment, the passive component  246  comprises the metal layer patterns  210  at the top level of the interconnect structure  220 . 
         [0022]    Embodiments provide a radio-frequency (RF) device package  500 . In one embodiment, the RF device package uses a thinning process and a TSV process for the RF device chip. A TSV structure adopted by the RF device chip can achieve a higher density and a shorter connection than the conventional bonding wire. Compared with the conventional wire bonding device package, one exemplary embodiment of the RF device package may have a lower interconnection resistance due to the TSV structure for the RF device chip. Also, signal or ground (GND) terminals may be formed in the interconnect structure  220  of the RF device package. Therefore, one exemplary embodiment of the RF device package is fabricated without requiring a GND plane, which is used in the conventional wire bonding device package, designed to be disposed on a backside of the RF device package and contacting to the base. Accordingly, the RF device package can avoid disadvantages of the RF performance degradation of the conventional wire bonding device package due to the GND plane contacting to the base. Additionally, a back side of the RF device package is designed to be disposed closer to the base than the front side thereof Therefore, one exemplary embodiment of the RF device package may provide a higher position for passive components than the conventional flip chip package. Interference from the base to the passive components can be reduced, so that the RF device package can achieve superior RF performances of, for example, low loss and high linearity. 
         [0023]    While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.