Abstract:
The present disclosure relates to a nitride electronic device and a method for manufacturing the same, and particularly, to a nitride electronic device and a method for manufacturing the same that can implement various types of nitride integrated structures on the same substrate through a regrowth technology (epitaxially lateral over-growth: ELOG) of a semi-insulating gallium nitride (GaN) layer used in a III-nitride semiconductor electronic device including Group III elements such as gallium (Ga), aluminum (Al) and indium (In) and nitrogen.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional of application Ser. No. 13/548,522, filed on Jul. 13, 2012. Further, this application claims the benefit of priority from Korean Patent Applications No. 10-2011-0071343, filed on Jul. 19, 2011 and No. 10-2012-0018591, filed on Feb. 23, 2012 with the Korean Intellectual Property Office. The disclosure of these prior U.S. and Korean applications are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to a nitride electronic device and a method for manufacturing the same, and particularly, to a nitride electronic device and a method for manufacturing the same that can implement can implement various types of nitride integrated structures on the same substrate through a regrowth technology (epitaxially lateral over-growth: ELOG) of a semi-insulating gallium nitride (GaN) layer used in a III-nitride semiconductor electronic device including Group III elements such as gallium (Ga), aluminum (Al) and indium (In) and nitrogen. 
       BACKGROUND 
       [0003]    A gallium nitride (GaN)-based compound semiconductor is a direct transition type semiconductor and can control a wavelength from visible rays to ultraviolet rays. The gallium nitride-based compound semiconductor has high thermal and chemical stability and high electron mobility and saturated electron velocity. The gallium nitride-based compound semiconductor has excellent physical properties such as a large energy band gap as compared to known gallium arsenic (GaAs) and indium phosphorus (InP)-based compound semiconductors. On the basis of these properties, an application range of the gallium nitride-based compound semiconductor has been expanded to optical devices such as light emitting diodes (LEDs) of a visible ray region and laser diodes (LDs), and the next-generation wireless communication and satellite communication systems requiring high power and high frequency properties, which are fields having a limitation when using known compound semiconductors. 
         [0004]    Performance of a gallium nitride-based electronic device is determined by an epitaxial structure, a process technology such as ohmic contact by a low resistance metal material and Schottky contact having high bather potential and a device design for determining a range of high frequency operation and current operation. Here, the epitaxial structure includes a barrier layer constituted by aluminum gallium nitride (AlGaN), indium aluminum nitride (InAlN), aluminum nitride (AlN) and the like, a channel layer used as an electron movement path and a semi-insulating layer for device isolation and reduction in leakage current. 
         [0005]    However, when implementing integrated structures having various properties on a single substrate at the same time, there are many limitations in designing of the epitaxial structure, a device process and designing of a device, which is an obstacle to implementing a GaN-based electronic device. 
         [0006]    Accordingly, in order to manufacture a GaN-based field effect transistor (FET), it is necessary to develop an epitaxial structure, a process technology and a device design technology that can manufacture various FET devices on a single substrate. 
       SUMMARY 
       [0007]    The present disclosure has been made in an effort to provide an electronic device which has structures differently having channel layers and barrier layers through a regrowth technology using a GaN layer as a semi-insulating layer and regrowth, and has integrated structures with various properties, which are implemented on a single substrate using a unit process and a design technology, and a method for manufacturing the same. 
         [0008]    An exemplary embodiment of the present disclosure provides a nitride electronic device, including: a first nitride integrated structure in which a low temperature buffer layer, a first semi-insulating nitride layer, a first channel layer and a first barrier layer are sequentially stacked on a substrate, and the first semi-insulating nitride layer is partially etched; and a second nitride integrated structure in which a second semi-insulating nitride layer, a second channel layer and a second barrier layer are sequentially stacked on a part where the first semi-insulating nitride layer is partially etched. 
         [0009]    Another exemplary embodiment of the present disclosure provides a method for manufacturing a nitride electronic device, including: forming an epitaxial structure in which a low temperature buffer layer, a first semi-insulating nitride layer, a first channel layer and a first barrier layer are sequentially stacked on a substrate; stacking a first dielectric layer for forming a pattern on the first barrier layer and partially etching the first barrier layer, the first channel layer and the first semi-insulating nitride layer; regrowing a second semi-insulating nitride layer on the etched first semi-insulating nitride layer; sequentially stacking a second channel layer and a second barrier layer on the second semi-insulating nitride layer; stacking a second dielectric layer for forming a pattern on the second barrier layer and etching the second barrier layer, the second channel layer and the second semi-insulating nitride layer; and removing the first and second dielectric layers and stacking metal electrode layers on the first and second barrier layers. 
         [0010]    According to the exemplary embodiments of the present disclosure, it is possible to obtain the following various effects by integrating various types of devices using a semi-insulating GaN layer that isolates devices and limits leakage current in an electronic device. 
         [0011]    It is possible to implement a compound semiconductor integrated circuit in which various types of devices are simultaneously manufactured on a single substrate using a regrowth technology. 
         [0012]    Since different kinds of epitaxial structures may be grown, it is possible to form, as necessary, various types of electronic devices such as integration of high frequency devices having different operating frequencies, integration of a depletion mode (normally-on) device and a enhancement mode (normally-off) device by adjusting a thickness of a barrier layer, integration of a high frequency device constituted by a channel layer and a barrier layer and a high current device constituted by a channel layer or a Schottky diode and the like. 
         [0013]    As electronic devices are integrated vertically, a degree of integration of devices in the same area may be improved as compared to a known horizontal device arrangement, and when a semiconductor integration process is used, the surface planarization may be achieved in a horizontal direction, and devices may be integrated in a vertical direction. 
         [0014]    The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a cross-sectional view illustrating a structure of a GaN electronic device[KCI 1 ] according to the present disclosure. 
           [0016]      FIGS. 2 to 9  are a process flowchart illustrating a method for manufacturing a GaN electronic device according to the present disclosure. 
           [0017]      FIG. 10  is a cross-sectional view illustrating a structure of a GaN electronic device which includes only barrier layers by omitting a first channel layer and a second channel layer from the structure of the GaN electronic device of  FIG. 1 . 
           [0018]      FIG. 11  is a cross-sectional view illustrating a structure of a GaN electronic device in which a first integrated structure in the structure of the GaN electronic device of  FIG. 1  is constituted by only a channel layer, and a second integrated structure is constituted by a channel layer and a barrier layer. 
           [0019]      FIG. 12  is a cross-sectional view illustrating a structure of a GaN electronic device in which a first integrated structure in the structure of the GaN electronic device of  FIG. 1  is constituted by a channel layer and a barrier layer, and a second integrated structure is constituted by only a channel layer. 
           [0020]      FIG. 13  is a cross-sectional view illustrating a structure of a GaN electronic device which includes only channel layers by omitting a first barrier layer and a second barrier layer from the structure of the GaN electronic device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    In the following detailed description, reference is made to the accompanying drawing, which form a part hereof. The illustrative embodiments described in the detailed description, drawing, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. 
         [0022]    Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The configuration of the present disclosure and operational effect thereof may be apparently understood through the following detailed description. 
         [0023]    Prior to the detailed description of the present disclosure, it is noted that the same reference numerals refer to the same elements throughout the specification even though the same elements are shown in the other drawing, and known constitutions may not be described in detail if they make the gist of the present disclosure unclear. 
         [0024]      FIG. 1  illustrates a cross-sectional view of a GaN electronic device according to an exemplary embodiment of the present disclosure. 
         [0025]    As illustrated in  FIG. 1 , the GaN electronic device according to the exemplary embodiment of the present disclosure includes a sapphire substrate  101 , a low temperature buffer layer  102 , a first semi-insulating GaN layer  103 , a first channel layer  104 , a first barrier layer  105 , a second semi-insulating GaN layer  107 , a second channel layer  108 , a second barrier layer  109 , an ohmic contact layer-source electrode layer  111 , an ohmic contact layer-drain electrode layer  112  and a Schottky contact layer-gate electrode layer  113 . 
         [0026]    According to the exemplary embodiment of the present disclosure, the second semi-insulating GaN layer  107  is used so as to ensure device isolation and reduction in leakage current of the GaN electronic device, and properties of electrical insulation and device isolation between first and second GaN integrated structures are implemented through a regrowth process of the second semi-insulating GaN layer  107 , thereby manufacturing an electronic device capable of implementing the same kind of or different kinds of various devices together on the same substrate. 
         [0027]      FIGS. 2 to 9  illustrate a manufacturing process of the GaN electronic device according to the exemplary embodiment of the present disclosure. 
         [0028]    Describing the manufacturing process of the GaN electronic device, a basic epitaxial structure is first formed. The epitaxial structure is formed by sequentially stacking the low temperature buffer layer  102 , the first semi-insulating GaN layer  103 , the first channel layer  104  for electron movement and the first barrier layer  105  forming a 2-dimensional electron gas (2-DEG) layer on the sapphire substrate  101 . 
         [0029]    Thereafter, in an etching process for device integration, after patterning a first SiO 2  layer or a first SiN x  layer  106  using a first mask, the first channel layer  104  and the first barrier layer  105  are etched. Then, the second semi-insulating GaN layer  107  is regrown on the first semi-insulating GaN layer  103  which is exposed. After two-dimensional surface growth is completed, the second channel layer  108  and the second barrier layer  109  are sequentially stacked. In this case, epitaxial properties of the semi-insulating GaN layer, the channel layer and the barrier layer, which are grown separately, are determined according to properties of devices to be integrated on the single substrate, and various types of devices may be integrated. 
         [0030]    When the regrowth is completed, a second SiO 2  layer or a SiN x  layer  110  is deposited, and then patterned oppositely to patterning using the first mask. Next, an etching process is performed up to the first SiO 2  layer or the SiN x  layer  106 , and the SiO 2  layer or the SiN x  layer  106  which is exposed is removed. 
         [0031]    Thereafter, an electrode layer for manufacturing an electronic device is formed. In this case, a Schottky electrode of a gate electrode is formed after forming ohmic contact of a source electrode and a drain electrode according to a design of a device pattern. The same type of or different types of GaN devices may be integrated on a single substrate based on the above-mentioned processes. 
         [0032]      FIG. 2  illustrates an epitaxial structure layer that is a basic structure of an electronic device using a GaN compound semiconductor. The epitaxial structure layer has a structure in which a sapphire substrate  101 , a low temperature buffer layer  102 , a first semi-insulating GaN layer  103 , a first channel layer  104  and a first barrier layer  105  are sequentially stacked. 
         [0033]    Describing steps of a manufacturing process of the epitaxial structure layer, the low temperature buffer layer  102  is first grown on the sapphire substrate  101 . Thereafter, the first semi-insulating GaN layer  103  is grown on the low temperature buffer layer  102  to have a thickness of 2 to 3 μm so as to electrically insulate electronic devices and reduce leakage current. The first semi-insulating GaN layer  103  is grown to have an epitaxial structure which has high resistivity by changing a growth speed of high temperature GaN or controlling a growth mode of GaN. 
         [0034]    Then, the first channel layer  104  is grown on the first semi-insulating GaN layer  103 . The first channel layer  104  is a path through which electrons forming an current flow in an electronic device move between electrode layers, and in order for the first channel layer  104  to have high mobility, no impurities is doped or a minimum amount of dopant is used. The first channel layer  104  may be constituted by a ternary compound semiconductor including indium (In) or aluminum (Al) so as to increase an effect of interrupting leakage current and limiting current. 
         [0035]    Then, the first barrier layer  105  is grown on the first channel layer  104 . The first barrier layer  105  is mainly constituted by a ternary (Al x Ga 1-x N, In x Ga 1-x N, In x Al 1-x N) or quaternary (In x Al y Ga 1-x-y N) compound semiconductor. In this case, a composition ratio of elements and a thickness of the barrier layer are determined according to performance required for the GaN electronic device. In a high frequency electronic device, an Al x Ga 1-x N barrier layer is mainly used, a composition ratio of Al is in the range of 20 to 40%, and a thickness thereof is in the range of 10 to 40 nm. 
         [0036]      FIGS. 3 and 4  illustrate a step of forming a pattern and an etching step for regrowing semi-insulating GaN. 
         [0037]    Referring to  FIG. 3 , a first dielectric layer  106  is used to form a pattern, and in this case, a thickness of the dielectric layer is in the range of 0.1 to 0.2 μm. SiO 2  or SiN x  may be used for the first dielectric layer  106 . 
         [0038]    Referring to  FIG. 4 , an etching thickness is up to a depth at which the first semi-insulating GaN layer  103  is exposed and is generally in the range of 0.1 to 0.5 μm.  FIG. 4  illustrates a first integrated structure. 
         [0039]    Referring to  FIG. 5 , the second semi-insulating GaN layer  107  is regrown on the surface of the etched first semi-insulating GaN layer[KCI 2 ]  103 , and the second channel layer  108  and the second barrier layer  109  are stacked in sequence. In this case, a total thickness of the grown second integrated structure needs to be within the range of 1 μm in consideration of pattern work. The detailed configuration of the second channel layer  108  and the second barrier layer  109  is similar to that of the first channel layer  104  and the first barrier layer  105  and needs to be designed depending on properties of the GaN electronic device. 
         [0040]      FIGS. 6 to 9  simply illustrate steps of a manufacturing process of the GaN electronic device. 
         [0041]    Referring to  FIG. 6 , a second dielectric layer  110  for an etching process is formed. In this case, the pattern formed is opposite to that of the first dielectric layer  106 . SiO 2  or SiN x  may be used for the second dielectric layer  110 . 
         [0042]    Referring to  FIG. 7 , an etching process is performed up to the first dielectric layer  106 . Referring to  FIG. 8 , the first dielectric layer  106  and the second dielectric layer  110  used for forming the patterns are removed. Referring to  FIG. 9 , ohmic metal electrode layers  111  and  112  are stacked, and then Schottky metal electrode layers  113  are stacked according to a design structure of the GaN electronic device, thus manufacturing the GaN electronic device of  FIG. 1 . 
         [0043]      FIGS. 10 to 13  illustrate various types of electronic device structures based on the structure of the GaN electronic device illustrated in  FIG. 1 . 
         [0044]      FIG. 10  illustrates a structure in which the first channel layer  104  and the second channel layer  108  are omitted. In the high frequency electronic device, a channel layer may be omitted depending on properties of the first semi-insulating GaN layer  103  and the second semi-insulating GaN layer  107 . 
         [0045]      FIG. 11  illustrates a structure in which the first barrier layer  105  is omitted, and  FIG. 12  illustrates a structure in which the second barrier layer  109  is omitted. 
         [0046]    Most of the electronic devices including a barrier layer have a high electron mobility transistor (HEMT) structure, and an electronic device without a barrier layer has a metal semiconductor field effect transistor (MESFET) structure having a high current driving property. 
         [0047]      FIG. 13  illustrates a structure including only channel layers by omitting both the first barrier layer and the second barrier layer.  FIG. 13  illustrates a structure in which the same kind or different kinds of metal semiconductor field effect transistors are integrated according to properties of the channel layer. 
         [0048]    From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.