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標題: 矽材質化學機械研磨製程及清洗之研究
The Study of Chemical-Mechanical Polishing Process and Clear
作者: 歐沐怡
Ou, Mu Yi
關鍵字: 矽晶圓拋光;silicon polishing;化學機械研磨;cmp
出版社: 電機工程學系
的表面 粗糙度規格將趨近於原子級(Atomic scale)尺寸,同時
下一代十二吋矽晶圓 的表面不均勻度限制更為嚴格,因此必須
在CMP的物理機制與原理有深入的 研究與探討。
表 面粗糙度之影響實驗中發現,表面粗糙度與研磨墊材質及所
施加壓力十分密 切。此結果可從Liu等人所提出的物理研磨機制
做合理的解釋。 為了達到最佳化的表面微粗糙
度及較低的不均勻度,同時要求較高蝕刻 率,從實驗結果可以
找出矽晶圓研磨參數。另外從實驗結果得到矽蝕刻率與 施加壓
親 水性的表面不同,需要較特殊的清洗方法。在此研究中我們找
到一個適合矽 材質研磨後的清洗方法,使潔淨處理後的塵
粒(>0.24微米)少於500個。清洗 後晶圓表面金屬離子污染量極

Control of surface roughness during the chemical-
mechanical polishing (CMP) process is key to the
preparation of smooth, defect-free silicon starting
surfaces. In particular, the CMP process is a critical step in
the manufacturing of sub-quarter micron devices. Despite the
importance of CMP in device fabrication, little is known
about its control mechanism and how it effects the
resulting surface with atomic-scale flatness. From
this investigation, we confirm that process parameters , pad
materials, slurry supplier, and slurry pH strongly influence the
resulting surface roughness of a CMP silicon wafer.
Understanding the removal mechanism during the CMP
process is key to controlling the surface roughness
and achieving atomic-scale flatness. Using a previously
developed physical model[18], we describe the trend of roughness
as a function of process parameters in applied pressure, platen
speed and material properties of pads. The chemical
effect is not an explicit term in our model; but changes
in physical properties, which can result from chemical
effects, are included in the final equation of the model.
The dependence of removal rate and roughness on pH values, a
chemical effect, can be explained by the effect of pH
on pad and wafer softness. In our model, a softer wafer
surface would increase both removal rate and roughness.
Therefore, proper control of the CMP process, such as
with a two-step polish, a platen-polish followed by a buff-
polish, can achieve both fast removal rates and
atomic-scale flatness. A hydrophobic surface
on the bare silicon would be obtained after polishing,
a loots of abrasive particles would be remained on this
hydrophobic surface. Basic aqueous solution with surfactants
added could reduce the surface tension and leave
the same negative polarity on the surface of both
abrasive and wafers, improved wettibility on the
wafer surface and electrostatic repulsive forces are helpful for
SiO2 abrasive removal . Adding chelating agents like EDTA into
the solution mentioned above could reduce the
metallic ions contamination efficiently, close to the
detection limit of TXRF.
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