1237330 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種具南散熱效率之異質接面雙極電 晶體（HBT)功率元件，尤指一種以特殊的電晶體單元佈 局，透過背面導孔（backside via hole)以背面接地金 屬為尚效率的散熱器，可使元件之射極接面溫度分度更加 均勻’以有效避免電晶體之熱潰散（thermal runaway) 問題’同時亦保有HBT功率電晶體之優越操作特性。 【先前技術】 功率放大器可說是無線通訊系統裡最重要的元件。一 身又的功率放大器是由許多的電晶體單元所組成，而其中每 一個電晶體單元則是由異質接面雙極電晶體（HBT)所構 成。一般為了達到放大功率的功能，功率電晶體常在高電 流的條件下操作。然而，當HBT在高電流的操作條件下， 吊會因自我發熱” （self-heating)的效應，導致電晶 體熱>貝散（thermal runaway)的現象，並破壞元件的正 ^操作。這種自我發熱的效應是來自於集極電流與電晶體 /JDL度之間的正向反饋（positive feedback)關係。由半 導體/^/7接面間的溫度電流關係可以知，溫度上升將使 電晶體之集極電流增大，而電流增大又會使電晶體溫度升 南’因而更加增大集極電流。這樣的不穩定狀態將迅速的 I23733〇 影響功率放大器的正常操作，進而破壞整個電晶體。為了 要避免熱潰散的問題，一般常在HBT的射極加上一個壓艙 電阻（ballasting resistor)來使整個系統穩定。、射極 壓舱電阻可以使輸入與輸出端之間形成一個負向反饋迴 路（negative feedback loop)，因此可以避免電晶體自 我發熱的問題。然而，過大的壓艙電阻常會使Ηβτ元件的 功率增益與放大效益降低。 另一方面，HBT射極電流分佈不均也常會造成電晶體 熱潰散的問題。-般HBT功率電晶體常包含一組射極針狀 電極。如果這些射極針狀電極與基極電極之間的幾何配置 含有-些邊角’可能造成射極電流分佈不均的現象。不均 勻的電流分佈會使高電流密度區域局雜的升高溫度，進 而更加提以區域的電流密度，最後破壞電晶體的正常操 作口此各電極之間的幾何配置，並且設計適當的散熱 機制使電流分佈均勻，將可財效減少電晶體熱潰散的問 題。 曰第1圖所把繪的是先前技術所習知的傳統騰功率電 A佈局之俯視圖。就整體言，每一個電晶體包含三個主 口 P刀*極區10卜基極區以及射極區1〇3。集極 ^ 長林的集極魏1()4及—個長麵的基極區 亦稱為基極平台）。該基極平台包含—基極環狀電極 1237330 l〇5 ’以及在基極環狀電極内部的長方形射極區1〇3。射極 針狀電極106則配置於射極區之上，並且與基極區1〇2絕 緣為了使射極針狀電極1〇6接地，會在元件的遠端配置 接地區107。而為了節省空間，通常由許多個電晶體共 用-健地區，因此這些電晶體觸極針狀電極1〇6 均以金屬相連接，最後連接至該共用接地區1〇7的正面金 屬層。第2圖系-般接地區107之剖面結構圖。該接地區 107疋由一正面金屬20卜一背面導孔（backside咖 hole) 202以及透過該導孔202與正面金屬2〇1接觸之背 面金屬203所構成。其製作方式通常是在表面金屬結構製 作完成後，先在背面以光阻及曝光顯影技術定義出導孔 202的大小及位置，接著再以祕刻或乾蝴的技術讓導 孔202穿透至表面，最後在鍍上背面金屬2〇3，並使其透 過導孔202與表面金屬2〇1接觸。由於接地區1〇7的正面 金屬201是透過導孔202與整個背面金屬2〇3細，因此 接地區1G7也具備散熱的功能，可以當成是―個散熱器 (heat sink)。然而，以第1圖之傳統的配置方式而言， 會因距離接地區之遠近不同而在該射極電極的各區域產 生不同的電流密度。不均⑽t流密度分佈會使射極接面 在高電流密度的局部區域產生高溫，形成不均勻溫度分 佈’以致於在⑥溫區域造賴潰散問_使整個電晶體崩 1237330 潰。 有鑑於此，本案之發明人提供—種具高散熱效率之異 質接面雙極電晶體之佈局方式，以改善上述之缺點。 【發明内容】 本么明之主要目的係提供_種具高散熱效率之異質 接面雙極電晶體⑽）功率树，其以特殊的電晶體單 兀佈局’並利用背面導孔（backside via hole)以及背 面接地金屬，形成高財的散熱^，可有 熱潰散⑽围lru卿ay)’同時亦保有厮功率;曰晶體 之優越操作特性。 本發明所提出之HBT電晶體單元佈局的特點，在於背 面導孔與各電晶體之間的幾何配置，除了可以使溫度的更 均勻分佈外’射極電流也可以更均勻分佈以避免電晶體之 熱潰散問題。 為了對此-發明有更深人之瞭解，賴具體實施例及 其圖不詳述於後。 【實施方式】 為了有效利用接地區的散熱特性，本發明提出將勝 電晶體配置於背面導孔接地區的周圍，使射極電流及射極 接面溫度更加均勻。如第3圖所示之佈局方式即為本發明 1237330 的主要概念，亦為本發明之第一具體實施例。此佈局結構 的特色在於將電晶體緊鄰配置於接地區（散熱器）的兩 側如此來整 固射極電極的電流將均勾的流向接地區， 因此可以使射極接_溫度分佈更佳均勻，以避免電晶體 的熱潰散效應。第3圖的結構主要包含一方形接地區（或 稱散熱器）31以及二個腹電晶體32。該方形接地區31 的功能除了提供電晶體32接地外，也可作為—高效率散 熱器，其包含-正面金屬層3U、一背面導孔312以及一 層透過背面導孔312與該正面金屬;| 311接觸之背面金屬 層313。此二個電晶體32均包含一集極電極32卜一基極 電極322及-射極電極323。該射極電極323可設計為長 方形’其長邊與正方形接地區31之-邊平行，其覆蓋射 極區並延伸至接聽使其導通，用讀供麵極地作用及 並提供散熱的功能。如第3圖之示意圖所示，此佈局的特 點在於此二個電晶體32與該正方形接地區31的因幾何配 置方式而使射極接面溫度分佈更加均勻，如此可使射極電 流不會因為溫度分佈不均而產生局部發熱現象，因而確保 電晶體的正常操作。該方形接地區並不受限於正方形，也 可设计為長方形；此外背面導孔的幾何形狀並不受限於圓 形，其他的幾何形狀（如矩形）也可以提供同樣的功能。 依此概念延伸，也可以將四個電晶體配置於正方形的 1237330 接地區，如第4圖所示，此亦為本發明之另一具體實施例。 此佈局結構包含一正方形接地區（或稱正方形散熱 器）51、四個HBT電晶體52以及四個依實際需要而增設的 Μ艙電阻53 (ballasting resistor)以及雙通電容54 (bypass capacitor)。該正方形接地區51的功能除了提 供電晶體52接地外，也可作為一高效率散熱器，其包含 一正面金屬層511、一背面導孔512以及一層透過背面導 孔512與該正面金屬層511接觸之背面金屬層513。此四 個電晶體52均包含一集極電極521、一基極電極522及一 射極電極523。該射極電極523可設計為長方形，其長邊 與正方形接地區51之一邊平行，其覆蓋射極區並延伸至 接地區使其導通，用以提供接射極地作用及並提供散熱的 功能。此佈局的特點在於四個電晶體52與該正方形接地 區51的距離均等距，同時射極電流可以均勻的流向接地 區，因此可以使接面溫度均勻分佈，以避免電晶體熱潰散 問題產生。此外，由於四個電晶體52散熱程度相同，因 而並此並不因為其中一個電晶體電流過大而造成整個模 組崩潰。值得一提的是，我們在本實施例中增設了壓艙電 阻與雙通電容，如此的配置顯示本發明的佈局型態不不受 限於單純電晶體元件，仍然可以一不同的需求增設其他的 元件（如含各式的壓艙電阻以及雙通電容等），以提升電 1237330 晶體的操作特性。 實際上，如前二個實施例所描述，其中接地區的幾何 形狀並不受限於正方形或長方形，當然也可以設計為多邊 形或圓形，只要每一個電晶體與接地區之間的幾何配置可 以讓射極電流均勻分佈，並使每—個電晶體散熱程度相同 即可。如第5圖所示，即為圓形接地區以及其周圍電晶體 的配置示意圖，此配置方式也可視為本發明之另一實施 例第6圖則疋六邊型接地區以及其周圍電晶體的配置示 意圖，此亦為本發明之又一實施例。 綜上所述，本發明確實可達到預期之目的，提供一種 具高散熱效率之異質接面雙極電晶體，可有效避免電晶體 之熱潰散，同時財電晶體之優顧作雜，極具產業利 用之價值，爰依法提出專利申請。 【圖式簡單說明】 第1圖係-傳統HBT功率電晶體佈局之俯視圖。 第2圖係背面導孔的剖面結構圖。 第3圖係以背面導孔為散熱裝置之本發明第一實施例之俯 視不意圖。 第係以背面導孔為散熱裝置之本發明另—實施例之俯 視不意圖。 第5圖係本發剩形接地區的—種實施例之俯視示意圖。 1237330 第6圖係本發明多邊型接地區的一種實施例之俯視示意 圖0 【主要元件符號說明】 集極區101 射極區103 基極環狀電極105 接地區107 背面導孔202 方形接地區（散熱器）31 基極區102 集極電極104 射極針狀電極106 正面金屬201 背面金屬203 HBT電晶體321237330 IX. Description of the invention: [Technical field to which the invention belongs] The present invention relates to a heterojunction bipolar transistor (HBT) power element with southern heat dissipation efficiency, especially a special transistor unit layout, which is conducted through the back side. The backside via hole uses the back ground metal as an efficient heat sink, which can make the temperature division of the emitter junction of the element more uniform 'to effectively avoid the thermal runaway problem of the transistor' while also maintaining HBT power Superior operating characteristics of transistors. [Previous technology] The power amplifier can be said to be the most important component in a wireless communication system. The power amplifier is composed of many transistor units, and each transistor unit is composed of a heterojunction bipolar transistor (HBT). In order to achieve the function of amplifying power, power transistors are often operated under high current conditions. However, when HBT is operating under high current, the self-heating effect of the HBT will cause the phenomenon of transistor thermal runaway and destroy the normal operation of the device. This This kind of self-heating effect comes from the positive feedback relationship between the collector current and the transistor / JDL degree. From the temperature-current relationship between the semiconductor / ^ / 7 interface, it can be known that the temperature rise will make the electricity The collector current of the crystal increases, and the increase of the current will cause the temperature of the transistor to rise south, thereby increasing the collector current. Such an unstable state will quickly affect the normal operation of the power amplifier, and then destroy the entire power supply. Crystal. In order to avoid the problem of thermal collapse, it is common to add a ballasting resistor to the emitter of HBT to stabilize the entire system. The emitter ballast resistor can make a negative between the input and output terminals. Negative feedback loop, so it can avoid the problem of self-heating of the transistor. However, too large ballast resistance often makes the power gain of the Ηβτ element and The large benefit is reduced. On the other hand, the uneven distribution of HBT emitter currents often causes the problem of transistor thermal collapse.-Generally, HBT power transistors often include a group of emitter needle electrodes. If these emitter needle electrodes and the base The geometric configuration between the electrodes contains some corners that may cause the phenomenon of uneven emitter current distribution. The uneven current distribution will locally increase the temperature in high current density areas, and further increase the current density in the area. Finally, the normal operation of the transistor is destroyed, and the geometric configuration between the electrodes is designed, and an appropriate heat dissipation mechanism is designed to make the current distribution uniform, which can effectively reduce the problem of thermal collapse of the transistor. Top view of the traditional Teng-power A layout known in the prior art. As a whole, each transistor includes three main port P knives * pole region 10 base region and emitter region 103. Collector ^ long Lin's collector Wei 1 () 4 and a long-surface base region are also referred to as the base platform.) The base platform includes a base ring electrode 1237330 l05 'and inside the base ring electrode. Rectangular emitter region 10 The emitter needle electrode 106 is arranged above the emitter region and insulated from the base region 102. In order to ground the emitter needle electrode 106, a connection region 107 is arranged at the far end of the component. Space-saving, usually shared by many transistors, so the contact pins 106 of these transistors are connected by metal, and finally connected to the front metal layer of the shared region 107. Figure 2 A cross-sectional structural view of the general connection area 107. The connection area 107 is composed of a front metal 20, a backside hole 202, and a back metal 203 that contacts the front metal 201 through the guide hole 202. Make up. The manufacturing method is usually to define the size and position of the guide hole 202 on the back by photoresist and exposure development technology after the surface metal structure is completed, and then use the secret or dry butterfly technology to penetrate the guide hole 202 to On the surface, the back metal 203 is finally plated, and it is made to contact the surface metal 201 through the via hole 202. Because the front metal 201 of the connection area 107 is thinner than the entire back metal 203 through the via hole 202, the connection area 1G7 also has a heat dissipation function and can be regarded as a heat sink. However, with the conventional arrangement shown in Fig. 1, different current densities will be generated in each region of the emitter electrode depending on the distance from the adjacent area. The uneven 流 t current density distribution will cause the emitter junction to generate high temperature in a local area of high current density, forming an uneven temperature distribution ', so as to cause failure in the temperature region _ and cause the entire transistor to collapse 1237330. In view of this, the inventor of the present case provides a layout method of a heterojunction bipolar transistor with high heat dissipation efficiency to improve the above-mentioned disadvantages. [Summary of the invention] The main purpose of this Meming is to provide _ a kind of heterojunction bipolar transistor with high heat dissipation efficiency ⑽) power tree, which uses a special transistor unit layout and uses backside via holes And the grounded metal on the backside, forming a high-quality heat sink ^, there can be thermal break-up ⑽ around lruqing ay) 'while also maintaining the power; said crystal's superior operating characteristics. The feature of the HBT transistor unit layout proposed by the present invention is that the geometric configuration between the backside vias and the transistors can not only make the temperature more uniformly distributed, but also the emitter current can be more evenly distributed to avoid the transistor. Thermal collapse problem. In order to have a deeper understanding of this invention, the specific embodiments and their drawings are not detailed below. [Embodiment] In order to effectively utilize the heat dissipation characteristics of the junction area, the present invention proposes to dispose a transistor in the vicinity of the backside via hole junction area to make the emitter current and the emitter junction temperature more uniform. The layout shown in FIG. 3 is the main concept of the present invention 1237330, and also the first specific embodiment of the present invention. The characteristic of this layout structure is that the transistor is arranged close to the two sides of the connection area (heat sink), so that the current of the emitter electrode is consolidated, and the current flows uniformly to the connection area, so that the emitter connection temperature distribution can be better and uniform. To avoid the thermal collapse effect of the transistor. The structure of FIG. 3 mainly includes a square connection area (or heat sink) 31 and two abdominal transistor 32. In addition to providing the transistor 32 ground, the function of the square connection area 31 can also be used as a-high efficiency heat sink, which includes-a front metal layer 3U, a back via 312 and a layer through the back via 312 and the front metal; | 311 contacts the back metal layer 313. Each of the two transistors 32 includes a collector electrode 32, a base electrode 322, and an emitter electrode 323. The emitter electrode 323 can be designed as a rectangle with its long side parallel to the side of the square junction area 31, which covers the emitter region and extends to the answer to make it conductive, uses the read supply surface to polarize, and provides the function of heat dissipation. As shown in the schematic diagram in FIG. 3, the layout is characterized in that the temperature distribution of the emitter junction is more uniform due to the geometric configuration of the two transistors 32 and the square junction area 31, so that the emitter current will not be affected. Local heating occurs due to uneven temperature distribution, thus ensuring normal operation of the transistor. The square junction area is not limited to a square, and it can also be designed as a rectangle. In addition, the geometry of the back guide hole is not limited to a circle. Other geometric shapes (such as rectangles) can also provide the same function. Extending from this concept, four transistors can also be arranged in a square 1237330 junction area, as shown in FIG. 4, which is another specific embodiment of the present invention. This layout structure includes a square connection area (also called a square heat sink) 51, four HBT transistors 52, and four ballasting resistors 53 and a bypass capacitor 54 added according to actual needs. In addition to providing the grounding of the transistor 52, the function of the square connection area 51 can also be used as a high-efficiency heat sink, which includes a front metal layer 511, a back via 512, and a layer through the back via 512 and the front metal layer 511. The back metal layer 513. Each of the four transistors 52 includes a collector electrode 521, a base electrode 522, and an emitter electrode 523. The emitter electrode 523 may be designed as a rectangle, and its long side is parallel to one side of the square junction region 51. It covers the emitter region and extends to the junction region to make it conductive, so as to provide an emitter-ground effect and a heat dissipation function. The characteristic of this layout is that the distances between the four transistors 52 and the square ground region 51 are equal, and the emitter current can flow to the ground region uniformly, so the junction temperature can be evenly distributed to avoid the problem of transistor thermal collapse. In addition, because the four transistors 52 dissipate heat to the same degree, it does not cause the entire module to collapse due to the excessive current of one of the transistors. It is worth mentioning that we have added ballast resistors and double-pass capacitors in this embodiment. Such a configuration shows that the layout of the present invention is not limited to pure transistor elements, but can be added for different needs. Components (including various ballast resistors and double-pass capacitors) to improve the operating characteristics of electric 1237330 crystals. In fact, as described in the previous two embodiments, the geometry of the junction area is not limited to a square or rectangle. Of course, it can also be designed as a polygon or a circle, as long as the geometric configuration between each transistor and the junction area The emitter current can be evenly distributed, and the heat dissipation degree of each transistor can be the same. As shown in FIG. 5, it is a schematic diagram of the configuration of the circular junction area and the surrounding transistors. This configuration method can also be regarded as another embodiment of the present invention. Figure 6: The hexagonal junction area and the surrounding transistors. The configuration diagram is also another embodiment of the present invention. In summary, the present invention can indeed achieve the intended purpose, and provide a heterojunction bipolar transistor with high heat dissipation efficiency, which can effectively avoid the thermal collapse of the transistor, and at the same time, the advantages and disadvantages of the financial transistor are very complicated The value of industrial utilization is based on filing a patent application. [Schematic description] Figure 1 is a top view of the layout of a traditional HBT power transistor. Fig. 2 is a cross-sectional structure view of a back guide hole. Fig. 3 is a schematic plan view of the first embodiment of the present invention using the rear guide hole as a heat dissipation device. The first embodiment of the present invention, which uses the back guide hole as a heat dissipation device, is not intended to be viewed from the top. FIG. 5 is a schematic top view of an embodiment of the present invention in a left-shaped area. 1237330 FIG. 6 is a schematic plan view of an embodiment of the polygonal contact region of the present invention. [Description of the main component symbols] Collector region 101 Emitter region 103 Base ring electrode 105 Contact region 107 Back side guide hole 202 Square contact region ( Heat sink) 31 base region 102 collector electrode 104 emitter needle electrode 106 front metal 201 back metal 203 HBT transistor 32
正面金屬層311 背面導孔312 背面金屬層313 集極電極321 基極電極322 射極電極323 正方形接地區（正方形散熱器）51 壓艙電阻53 正面金屬層511 背面金屬層513 基極電極522 HBT電晶體52 雙通電容54 背面導孔512 集極電極521 射極電極523Front metal layer 311 Back via 312 Back metal layer 313 Collector electrode 321 Base electrode 322 Emitter electrode 323 Square junction (square heat sink) 51 Ballast resistor 53 Front metal layer 511 Back metal layer 513 Base electrode 522 HBT Transistor 52 Double-pass capacitor 54 Rear via 512 Collector electrode 521 Emitter electrode 523
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