TWI518921B - Schottky diode structure - Google Patents
Schottky diode structure Download PDFInfo
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- TWI518921B TWI518921B TW102128005A TW102128005A TWI518921B TW I518921 B TWI518921 B TW I518921B TW 102128005 A TW102128005 A TW 102128005A TW 102128005 A TW102128005 A TW 102128005A TW I518921 B TWI518921 B TW I518921B
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- epitaxial layer
- diode structure
- schottky diode
- guard ring
- conductivity type
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- 239000000758 substrate Substances 0.000 claims description 18
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 239000002184 metal Substances 0.000 claims description 13
- 230000015556 catabolic process Effects 0.000 claims description 11
- 239000008433 xiaoji Substances 0.000 claims description 10
- NFFIWVVINABMKP-UHFFFAOYSA-N methylidynetantalum Chemical compound [Ta]#C NFFIWVVINABMKP-UHFFFAOYSA-N 0.000 claims description 7
- 229910003468 tantalcarbide Inorganic materials 0.000 claims description 7
- 230000003247 decreasing effect Effects 0.000 claims description 5
- 230000005684 electric field Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000004888 barrier function Effects 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000005240 physical vapour deposition Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
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- Electrodes Of Semiconductors (AREA)
Description
本發明是有關於一種蕭基二極體結構，特別是有關於一種具有線性濃度之護環區之蕭基二極體結構。
The present invention relates to a Schottky diode structure, and more particularly to a Schottky diode structure having a guard ring region of linear concentration.
蕭基二極體(Schottky Diode)是利用金屬/半導體接面形成蕭基障壁(Schottky Barrier)，由於金屬中沒有少數載子，在開關切換時不會造成時間延遲，因此廣泛地應用於電力電子系統之開關元件。
Schottky Diode uses Schottky Barrier to form a Schottky Barrier. It is widely used in power electronics because it does not have a small number of carriers in the metal and does not cause time delay when switching. The switching elements of the system.
然而，由於蕭基二極體的反向偏壓較低及反向漏電流較大，且漏電流容易隨著溫度升高而急遽增加，因此在習知之蕭基二極體的發展中，如何獲得較高的擊穿電壓(Breakdown Voltage)、降低順向電壓(Forward Voltage)及降低漏電流(Leakage Current)一直是蕭基二極體發展的關鍵。
However, due to the low reverse bias of the Xiaoji diode and the large reverse leakage current, and the leakage current is likely to increase rapidly with the increase of temperature, how is the development of the conventional Xiaoji diode? Obtaining higher Breakdown Voltage, reducing Forward Voltage and Leakage Current has been the key to the development of the Xiaoji diode.
有鑑於上述習知技藝之問題，本發明之其中之一目的在於提供一種蕭基二極體結構，其磊晶層中具有線性濃度之護環區不僅可使得蕭基二極體的擊穿電壓提高、順向電壓降低及漏電流降低，更可消除邊緣之電場以提高蕭基二極體之耐壓能力。
In view of the above problems of the prior art, one of the objects of the present invention is to provide a Schottky diode structure in which a guard ring region having a linear concentration in an epitaxial layer can not only cause a breakdown voltage of a Schottky diode. Increase, forward voltage reduction and leakage current reduction, and eliminate the electric field at the edge to improve the withstand voltage capability of the Xiaoji diode.
此蕭基二極體結構至少包含具有第一導電類型之基板；具有第一導電類型之磊晶層，位於基板之第一表面上；具有第二導電類型之複數個護環區，分別位於磊晶層中之兩側，其中複數個護環區之摻雜濃度係朝著磊晶層之兩側而線性遞減；氧化層，覆蓋磊晶層且位於複數個護環區上，以暴露出複數個護環區間之磊晶層；以及第一金屬層，位於已暴露之磊晶層上。
The Schottky diode structure includes at least a substrate having a first conductivity type; an epitaxial layer having a first conductivity type on a first surface of the substrate; and a plurality of guard ring regions having a second conductivity type, respectively located in the Lei On both sides of the crystal layer, the doping concentration of the plurality of guard ring regions is linearly decreased toward both sides of the epitaxial layer; the oxide layer covers the epitaxial layer and is located on a plurality of guard ring regions to expose the plurality of guard rings An epitaxial layer of the guard ring; and a first metal layer on the exposed epitaxial layer.
其中，基板及磊晶層可例如為碳化矽(SiC)，第一導電類型及第二導電類型則可例如分別為N型及P型。
The substrate and the epitaxial layer may be, for example, tantalum carbide (SiC), and the first conductivity type and the second conductivity type may be, for example, N-type and P-type, respectively.
此外，此蕭基二極體結構更包含第二金屬層位於基板之第二表面上。
In addition, the Schottky diode structure further includes a second metal layer on the second surface of the substrate.
前述之蕭基二極體結構之順向電壓(Forward Voltage)可例如介於1.5伏特(V)至1.8伏特(V)。前述之蕭基二極體結構之擊穿電壓(Breakdown Voltage)可例如介於600伏特(V)至900伏特(V)。
The forward voltage of the aforementioned Schottky diode structure may be, for example, between 1.5 volts (V) and 1.8 volts (V). The aforementioned Breakdown Voltage of the Schottky diode structure may be, for example, between 600 volts (V) and 900 volts (V).
承上所述，依據本發明之蕭基二極體結構，其可具有一或多個下述優點：
In view of the above, the Schottky diode structure according to the present invention may have one or more of the following advantages:
(1) 本發明之蕭基二極體結構利用具有線性濃度之護環區以使得蕭基二極體的擊穿電壓提高、順向電壓降低及漏電流降低。
(1) The Schottky diode structure of the present invention utilizes a guard ring region having a linear concentration to increase the breakdown voltage of the Schottky diode, reduce the forward voltage, and reduce the leakage current.
(2) 本發明之蕭基二極體結構利用具有線性濃度之護環區以消除蕭基二極體邊緣之電場，進而提高蕭基二極體的耐壓能力。
(2) The Schottky diode structure of the present invention utilizes a guard ring region having a linear concentration to eliminate the electric field at the edge of the Schottky diode, thereby improving the withstand voltage capability of the Schottky diode.
(3) 本發明之蕭基二極體結構利用碳化矽之基板及磊晶層以提高蕭基二極體的擊穿電壓。
(3) The Schottky diode structure of the present invention utilizes a substrate of tantalum carbide and an epitaxial layer to increase the breakdown voltage of the Schottky diode.
茲為使 貴審查委員對本發明之技術特徵及所達到之功效有更進一步之瞭解與認識，謹佐以較佳之實施例及配合詳細之說明如後。
For a better understanding and understanding of the technical features and the efficacies of the present invention, the preferred embodiments and the detailed description are as follows.
10‧‧‧基板
20‧‧‧磊晶層
30、31、32、33‧‧‧護環區
40‧‧‧氧化層
50‧‧‧第一金屬層
60‧‧‧第二金屬層
10‧‧‧Substrate
20‧‧‧ epitaxial layer
30, 31, 32, 33‧‧‧ guard ring area
40‧‧‧Oxide layer
50‧‧‧First metal layer
60‧‧‧Second metal layer
第1圖係為本發明之蕭基二極體結構之第一實施例示意圖。
第2圖係為本發明之蕭基二極體結構之第二實施例示意圖。
Figure 1 is a schematic view showing a first embodiment of the Schottky diode structure of the present invention.
Fig. 2 is a schematic view showing a second embodiment of the Schottky diode structure of the present invention.
以下將參照相關圖式，說明依本發明之蕭基二極體結構之實施例，為使便於理解，下述實施例中之相同元件係以相同之符號標示來說明。
The embodiments of the Schottky diode structure according to the present invention will be described below with reference to the related drawings. For ease of understanding, the same components in the following embodiments are denoted by the same reference numerals.
請參閱第1圖，第1圖係為本發明之蕭基二極體結構之第一實施例示意圖。本發明之較佳實施例中之第一導電類型及第二導電類型係分別以N型及P型作舉例，惟本發明不限於此。
Please refer to FIG. 1. FIG. 1 is a schematic view showing a first embodiment of the Schottky diode structure of the present invention. The first conductivity type and the second conductivity type in the preferred embodiment of the present invention are exemplified by N-type and P-type, respectively, but the invention is not limited thereto.
此蕭基二極體結構至少包含具有第一導電類型之基板10、具有第一導電類型之磊晶層20、具有第二導電類型之複數個護環區30、氧化層40及第一金屬層50。
The Schottky diode structure includes at least a substrate 10 having a first conductivity type, an epitaxial layer 20 having a first conductivity type, a plurality of guard ring regions 30 having a second conductivity type, an oxide layer 40, and a first metal layer 50.
續言之，具有第一導電類型之磊晶層20係可例如以物理氣相沉積(Physical Vapor Deposition, PVD)法或化學氣相沉積(Chemical Vapor Deposition, CVD)法形成於基板10上，此磊晶層20主要係用以在反向操作時形成空乏區(Depletion Region)以承受高電壓。其中，基板10較佳為N+型摻雜碳化矽基板以使得基板10背面形成良好的歐姆接觸，磊晶層20較佳為N-型碳化矽磊晶層。
In other words, the epitaxial layer 20 having the first conductivity type can be formed on the substrate 10 by, for example, a physical vapor deposition (PVD) method or a chemical vapor deposition (CVD) method. The epitaxial layer 20 is primarily used to form a Depletion Region to withstand high voltages during reverse operation. The substrate 10 is preferably an N+ type doped tantalum carbide substrate such that a good ohmic contact is formed on the back surface of the substrate 10. The epitaxial layer 20 is preferably an N-type tantalum carbide epitaxial layer.
由於碳化矽相較於矽具有較寬的能隙、較高的擊穿電壓、較高的熱傳導係數及較高的電子飽和速度等特性，因此利用碳化矽之基板10及磊晶層20，可提高此蕭基二極體的擊穿電壓。
Since the tantalum carbide has a wider energy gap, a higher breakdown voltage, a higher heat transfer coefficient, and a higher electron saturation speed than tantalum, the substrate 10 and the epitaxial layer 20 of the tantalum carbide can be used. Increase the breakdown voltage of this Xiaoji diode.
續言之，具有第二導電類型之複數個護環區30係分別形成於磊晶層20中之兩側，並且複數個護環區30之摻雜濃度係朝著磊晶層20之兩側而線性遞減。其中，具有線性濃度之複數個護環區30較佳為P型護環區，且可例如以離子佈植製程形成，惟本發明不限於此。
In other words, a plurality of guard ring regions 30 having a second conductivity type are respectively formed on both sides of the epitaxial layer 20, and the doping concentration of the plurality of guard ring regions 30 is toward both sides of the epitaxial layer 20. And linearly decreasing. Wherein, the plurality of guard ring regions 30 having a linear concentration are preferably P-type guard ring regions, and may be formed, for example, by an ion implantation process, but the invention is not limited thereto.
因此，藉由磊晶層20中具有線性濃度之複數個護環區30不僅可使得蕭基二極體的擊穿電壓提高、順向電壓降低及漏電流降低以外，更可藉由複數個護環區30之摻雜濃度朝著磊晶層20之兩側而線性遞減之特性，使得蕭基二極體邊緣之電場消除，進而提高蕭基二極體之耐壓能力。
Therefore, by the plurality of guard ring regions 30 having a linear concentration in the epitaxial layer 20, not only the breakdown voltage of the Schottky diode but also the forward voltage and the leakage current can be reduced, and the plurality of guards can be used. The doping concentration of the ring region 30 is linearly decreasing toward both sides of the epitaxial layer 20, so that the electric field at the edge of the Schottky diode is eliminated, thereby improving the withstand voltage capability of the Schottky diode.
續言之，氧化層40係覆蓋磊晶層20且位於複數個護環區30上，並且可例如藉由習知之微影及蝕刻製程對氧化層40進行圖案化，使得複數個護環區30間之磊晶層20暴露出來。
Continuingly, the oxide layer 40 covers the epitaxial layer 20 and is located on the plurality of guard ring regions 30, and the oxide layer 40 can be patterned, for example, by conventional lithography and etching processes, such that the plurality of guard ring regions 30 are The epitaxial layer 20 is exposed.
續言之，第一金屬層50(即陽極電極)係形成於已暴露之磊晶層20上，以藉由磊晶層20/第一金屬層50接面形成蕭基障壁(Schottky Barrier)。此外，此蕭基二極體結構更包含第二金屬層60(即陰極電極)位於基板10之背面。
In other words, the first metal layer 50 (ie, the anode electrode) is formed on the exposed epitaxial layer 20 to form a Schottky barrier by the epitaxial layer 20 / the first metal layer 50. In addition, the Schottky diode structure further includes a second metal layer 60 (ie, a cathode electrode) on the back side of the substrate 10.
因此，藉由本發明之蕭基二極體結構可使得蕭基二極體的擊穿電壓提高、順向電壓降低及漏電流降低。其中，順向電壓可例如介於1.5 V至1.8 V；擊穿電壓可例如介於600 V至900 V。
Therefore, with the Schottky diode structure of the present invention, the breakdown voltage of the Schottky diode can be increased, the forward voltage is lowered, and the leakage current is lowered. Wherein, the forward voltage may be, for example, between 1.5 V and 1.8 V; and the breakdown voltage may be, for example, between 600 V and 900 V.
請參閱第2圖，第2圖係為本發明之蕭基二極體結構之第二實施例示意圖。第二實施例與第一實施例之差異僅在於複數個護環區31、32、33。
Please refer to FIG. 2, which is a schematic view of a second embodiment of the Schottky diode structure of the present invention. The second embodiment differs from the first embodiment only in a plurality of guard ring regions 31, 32, 33.
在第一實施例中，磊晶層20兩側之護環區30係分別為一個，而第二實施例中之磊晶層20兩側之護環區31、32、33則分別為三個，且複數個護環區31、32、33之摻雜濃度係朝著磊晶層20之兩側而線性遞減，亦即護環區31之摻雜濃度大於護環區32之摻雜濃度，而護環區32之摻雜濃度大於護環區33之摻雜濃度。
In the first embodiment, the guard ring regions 30 on both sides of the epitaxial layer 20 are respectively one, and the guard ring regions 31, 32, and 33 on the two sides of the epitaxial layer 20 in the second embodiment are respectively three. And the doping concentration of the plurality of guard ring regions 31, 32, 33 decreases linearly toward both sides of the epitaxial layer 20, that is, the doping concentration of the guard ring region 31 is greater than the doping concentration of the guard ring region 32, The doping concentration of the guard ring region 32 is greater than the doping concentration of the guard ring region 33.
如此一來，藉由複數個護環區31、32、33之摻雜濃度朝著磊晶層20之兩側而線性遞減之特性，可使得蕭基二極體邊緣之電場消除，進而提高蕭基二極體之耐壓能力。惟，本發明不限於此，只要摻雜濃度係朝著磊晶層20之兩側而線性遞減之複數個護環區，皆應屬本發明所請求保護之範圍。
In this way, by the characteristic that the doping concentration of the plurality of guard ring regions 31, 32, 33 linearly decreases toward both sides of the epitaxial layer 20, the electric field at the edge of the Xiaoji diode can be eliminated, thereby increasing Xiao. The pressure resistance of the base diode. However, the present invention is not limited thereto, and a plurality of guard ring regions whose doping concentration is linearly decreasing toward both sides of the epitaxial layer 20 are within the scope of the claimed invention.
以上所述僅為舉例性，而非為限制性者。任何未脫離本發明之精神與範疇，而對其進行之等效修改或變更，均應包含於後附之申請專利範圍中。
The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.
無no
10‧‧‧基板 10‧‧‧Substrate
20‧‧‧磊晶層 20‧‧‧ epitaxial layer
30‧‧‧護環區 30‧‧‧ guard ring area
40‧‧‧氧化層 40‧‧‧Oxide layer
50‧‧‧第一金屬層 50‧‧‧First metal layer
60‧‧‧第二金屬層 60‧‧‧Second metal layer
Claims (6)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| TW102128005A TWI518921B (en) | 2013-08-05 | 2013-08-05 | Schottky diode structure |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| TW102128005A TWI518921B (en) | 2013-08-05 | 2013-08-05 | Schottky diode structure |
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| Publication Number | Publication Date |
|---|---|
| TW201507170A TW201507170A (en) | 2015-02-16 |
| TWI518921B true TWI518921B (en) | 2016-01-21 |
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| Country | Link |
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| TW (1) | TWI518921B (en) |
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