多孔性低介電常數材料之特性研究.

Abstract

隨著半導體技術的進步，元件的尺寸不斷的縮小，而入深次微米的領域中。為了增加積體電路的性能，降低導線的線寬和增加金屬導線層的數目，便成為超大型積體電路技術所需採用的方式。然而電子訊號在金屬導線間傳遞所造成的延遲，變成半導體元件速度受限的主要原因。為了降低訊號傳遞的時間延遲，使用低介電常數材料作為導線間的絕緣層，便可降低導線間的電容值，使元件在速度方面的性能提高，並且可以降低功率的消耗(power dissipation)及雜訊干擾(cross-talk noise)。在眾多的低介電常數材料中，多孔性的二氧化矽(porous silica)薄膜，是其中極具發展潛力的一種材料。在本論文中，將對二氧化矽薄膜的物性、熱穩定性及電性進行探討。除此之外，也對薄膜經過電漿處理過後的特性加以分析。在本研究中，控制薄膜孔隙度的體積百分比於50到70之間，可以使多孔性二氧化矽的介電常數降至1.7，而且其漏電流密度在電場強度為1MV/cm時可維持在10-6 A/cm2。經過電漿處理後，所得到的漏電流及介電常數均比未處理時低。

As IC technology moves into the deep submicrometer regime in high performance ULSI circuits, it is required to decrease the metal pitch and to increase the number of metal layers for interconnect to accommodate the increased packing density and functional complexity. But the signal propagation delay in the interconnect becomes an appreciable fraction of the total time delay. Use of low dielectric constant material (low-k) as the intermetal dielectric (IMD) results in low inter-line capacitance and therefore high performance in speed, low power dissipation, and low cross-talk noise. During various low dielectric materials, porous silica film is one of the possible candidates with an inherent low dielectric constant. In this thesis, the intrinsic properties such as fundamental physical, electrical, thermal stability of the spin on glass (SOG) have been investigated. We also study the properties of the SOG film with various plasma and treatments. An inherent low dielectric constant of 1.7 is achieved for about 50~70% porosity of the porous silica film and the leakage current density hold at a level of ~10-6 A/cm2 at 1MV/cm electric field strength. Applying the plasma treatment, both leakage current density and dielectric constant are decreased compared to untreated porous silica film. In this work, we will identify interconnect reliability problems related to the use of low-k porous silica film and to provide useful treatment for further material improvement. Abstract (English) ........................................................................................................ ii Acknowledgements ..................................................................................................... iv Contents ........................................................................................................................ v Table Captions ............................................................................................................ vii Figure Captions ......................................................................................................... viii Chapter 1 Introduction 1.1 General Background ..................................................................... 1 1.2 Motivation & Material Options .................................................... 3 1.3 Organization of This Thesis ......................................................... 7 Chapter 2 The Intrinsic Characterization of NanoPorous Silica Film 2.1 Introduction ................................................................................ 9 2.2 Experimental Procedure ............................................................. 10 2.3 Results and Discussion ............................................................... 12 2.3.1 Intrinsic Film Properties .................................................. 12 2.3.2 Thermal Stability ............................................................. 14 2.3.2 Analysis of the Leakage Current...................................... 18 2.4 Summary .................................................................................... 21 Chapter 3 Characterization of Porous silica Film with Various Plasma Treatment 3.1 Introduction ................................................................................ 23 3.2 Experimental Procedure ............................................................. 24 3.2.1 Standard Process ............................................................. 24 3.2.2 Plasma Treatment ............................................................ 25 3.2.3 Electrical Characteristics Measurement .......................... 26 3.3 Results and Discussion ............................................................... 27 3.3.1 The Impact of O2 Plasma Exposure ............................. 27 3.3.2 Effect of H2 Plasma Exposure …................................... 29 3.3.3 Effect of N2, N2O, and NH3 Plasma Exposure …............ 32 3.4 Conclusion and Summaries ........................................................ 33 Chapter 4 Conclusions and Suggestions for Future Work 5.1 Conclusions ................................................................................ 35 5.2 Suggestions for future Work ....................................................... 36 References .................................................................................................................. 38