| 摘要: | 隨著物聯網以及人工智慧的快速發展，在5G 通訊網路產品中三態內容定址記憶體(Ternary Content Addressable Memories, TCAM)扮演著越來越重要的角色，因為TCAM不同於一般的內容定址記憶體(Content Addressable Memories, CAM)，TCAM 除了擁有
存取邏輯’’1’’以及邏輯”0”的功能之外，還提供了”Don’t care”模式，透過”Don’t care”模式我們能夠規避”don’t caring”的資料來提升我們在記憶體內搜尋的效能。
非揮發性三態內容定址記憶體(Non-volatile Ternary Content Addressable Memories,nv-TCAM)是一種透過非揮發記憶體像是可變電阻式記憶體(Resistive-Random-Access-Memory, RRAM)、磁阻式隨機存取記憶體(Magnetic-Random-Access-Memory, MRAM)、鐵電場效電晶體記憶體(Ferroelectric Field-Effect Transistor, FeFET)來實現的TCAM。
在本篇論文中，提出了一種新型的nv-TCAM，透過一個控制電晶體結合一層金屬-鐵電氧化層-金屬(Metal-Ferroelectric-Metal, MFM)結構與一層金屬-金屬氧化層-金屬(Metal-Insulator-Metal, MIM)結構來實現，透過把MFM層的下電極連結在電晶體的閘極端，把MIM 層的下電極連結在電晶體的汲極端，使它同時具有鐵電性以及憶阻器之功能，並且利用MFM 層來儲存nv-TCAM 所需要的”Care”與”Don’t Care”狀態，MIM層則是用來儲存要被搜尋的位元。
此設計成功混合了兩種不同的非揮發記憶體MFM 層以及MIM層來實現nv-TCAM的操作，相比於一般傳統透過靜態隨機存取記憶體(Static-Random-Access-Memory,SRAM)來實現的TCAM，此設計不僅能解決資料易失性的問題，且每個Unit Cell 也只需要使用一顆控制電晶體，因此可以省下更多的面積、功耗，並利用非揮發記憶體的優勢提高了資料的儲存密度，來達到高性能的記憶體內搜尋。;With the development of Internet-of-Things and Artificial Intelligence, Ternary Content Addressable Memories (TCAM) gradually plays as an important role in 5G network communication products. Different from the Content Addressable Memories (CAM), in addition to the capability in storage of bit-1 and bit-0, the TCAM also provides the “Don’t care” mode to by-pass those “don’t-caring” data to improve the performance in memory searching.
Non-volatile TCAM(nv-TCAM) is a type of TCAM that is based on non-volatile memories such as Resistive-Random-Access-Memory(RRAM), Magnetic-Random-Access-Memory(MRAM), or Ferroelectric Field-Effect Transistor(FeFET).
In this thesis, we invent a new nv-TCAM which is composed of an MFM(Metal-Ferroelectric-Metal) and an MIM(Metal-Insulator-Metal) layers with a control transistor.
Through connecting MFM bottom electrode to the gate of the control transistor and connecting the MIM bottom electrode to the drain of the control transistor, the nv-TCAM can combine the functionalities of ferroelectrically and memristor. The MFM layer is used to store the “Care”
and “Don’t care” state which are needed for the nv-TCAM, while MIM layer is used to store bit-1 and bit-0 to be searched.
This design successfully integrated two different types of non-volatile memory, the MFM layer and the MIM layer to implement the operation of nv-TCAM. Compared to the traditional TCAMs based on Static-Random-Access-Memory (SRAM), this design dese not only solve the problem of data volatility but also uses only one transistor of a unit-cell. Therefore, this design can save more area and power. Additionally, with the advantage of non-volatile memories, this design promotes the data storage density and achieves high-performance in memory searching. |
