臺灣博碩士論文加值系統

超臨界流體是一種先進的環保技術，可以減少溶劑與水的使用量，同時具有低表面張力、低黏度、高擴散性等獨特性質。當半導體元件的尺寸進入奈米等級後，將會面臨高深寬比結構，及材料特徵所導致的技術瓶頸，而超臨界流體技術對此均有很好的解決能力。
本研究的最終目的是研究超臨界二氧化碳與co-solvent去除蝕刻後的光阻及其殘餘污染物，分三個階段進行，第一階段為硬烤後的光阻去除，第二階段為離子植入製程後的光阻去除，第三階段為蝕刻製程後的光阻去除。
光阻的去除是利用昇降壓的動作使光阻與底材剝離，再以足夠的液體流量，將已膨脹、剝離的光阻移除，最後利用臨界二氧化碳將殘餘的co-solvent移除，以達到乾燥的目的。所以超臨界二氧化碳的光阻去除製程是ㄧ種 ”乾進－乾出 ”的製程。

Contents
Abstract（in Chinese）...................................i
Abstract（in English）..................................ii
Acknowledgement........................................iii
Contents ...............................................iv
Table Captions ........................................vii
Figure Captions ......................................viii

Chapter 1 Introduction
1.1 Background..........................................1
1.2 The issue of the existing process ..................2
1.3 The advantage of the supercritical fluids process...4
1.4 Thesis organization ................................5

Cahpter 2 The Purpose and Method of This Study
2.1 The purpose of this experiment......................7
2.2 The apparatus for the experiment ...................7
2.3 The subject of this experiment.....................10
2.3.1 The first stage...................................11
2.3.2 The second stage .................................11
2.3.3 The third stage ..................................11
2.4 The method for the experiment [4]..................11
2.4.1 Load, Purge, Pressurize chamber ..................12
2.4.2 Fill chamber......................................13
2.4.3 Soak .............................................13
2.4.4 Agitation and Flush ..............................13
2.4.5 Rinse ............................................14
2.4.6 Dry, Vent, Unload ................................15

Chapter 3 Theory
3.1 Supercritical fluid [2]............................17
3.2 Supercritical carbon dioxide ......................18
3.3 The mechanism of the photoresist removal using supercritical fluid ....................................21

Chapter 4 The Experiment
4.1 The procedure of this experiment ..................28
4.2 The first stage, removal of photoresist after hard-bake on the bare silicon wafer
4.2.1 The preparation of samples .......................32
4.2.2 The procedure of photoresist removal after hard-bake ...................................................32
4.3 The second stage, removal of photoresist after ion implantation process on the bare silicon wafer
4.3.1 The preparation of samples .......................33
4.3.2 The procedure of photoresist removal after Arsenic ion implantation .......................................34
4.4 The third stage, removal of photoresist and residue after silicon dioxide etched process
4.4.1 The preparation of samples .......................34
4.4.2 The procedure for the removal of photoresist and residue after silicon dioxide etched process ...........36

Chapter 5 Result and Discussion
5.1 The first stage, removal of photoresist after hard-bake on the bare silicon wafer..........................37
5.2 The removal of photoresist after ion implantation process
5.2.1 AfterArsenic ion implantation ....................39
5.3 The removal of photoresist and residue after silicon dioxide etched process .................................42

Chapter 6 The Conclusion and Future Work
6.1 The condition of photoresist removal using SCORR process ................................................61
6.2 The job we have to do before the SCORR process.....62
6.3 The issue of co-solvent remained on the wafer .....63
6.4 The conclusion.....................................63
6.5 Future work........................................64

Reference ..............................................65

Vita ...................................................68


Table Captions
Table 1 Comparsion of physical-chamical properties in vapor, liquid and supercritical fluid of typical organic fluid [ 1 ] ............................................5

Table 2 Critical temperature and pressure for some common fluids [ 1 ] ..........................................19

Table 3 Physical-chamical properties for CO2 [3] .....20


Figure Captions
Figure 1 Enable sub-130 nm residue removal ............4

Figure 2 Isco supercritical fluid extraction system ...8

Figure 3 Syringe pump .................................8

Figure 4 The structure of extractor inside ............9

Figure 5 Cartridge ....................................9

Figure 6 The flowchart of the process sequence [4] ...16

Figure 7 Opened container ............................18

Figure 8 Sealed container ............................18

Figure 9 The phase change from liquid and gas phases to supercritical phase ...................................18

Figure 10 Phase diagram of CO2 .......................21

Figure 11 The mechanism of P/R removal ...............25

Figure 12 The hard crust of photoresist after the ion implantation or etching process, and indicating the direction of diffusion and solution of SCCO2 and co-solvent ...............................................27

Figure 13 The time line chart of pressure in the chamber ...............................................31

Figure 14 The sample preparation for the second stage .................................................33

Figure 15 The sample preparation of the third stage ..35

Figure 16 FTIR analysis of bare Si wafer, hard-bake wafer before and after SCORR treatment ......................38

Figure 17 XPS analysis（a）before SCORR treatment,（b）bare Si wafer with SCORR treatment（c）the soak pressure = 3000 psi,（d）the soak pressure = 5000 psi,（e）the soak pressure = 7000 psi ...................................42

Figure 18 An OM picture that（a）oxide lines, after SCCO2 and co-solvent treatment.（b）oxide lines, after H2SO4 and H2O2 treatment, and the P/R have been stripped.（c）oxide pillars, after SCCO2 and co-solvent treatment.（b）oxide pillarss, after H2SO4 and H2O2 treatment, and the P/R have been stripped .........................................43

Figure 19 An SEM micrograph before SCORR treatment .............................................44

Figure 20 An SEM micrograph of the oxide line in clean region after SCORR treatment ..........................44

Figure 21 An SEM micrograph of the oxide line in non-clean region after SCORR treatment ..........................45

Figure 22 An SEM micrograph of the P/R upon oxide line is swollen ...............................................46

Figure 23 An SEM micrograph of the P/R upon oxide line is large swollen and broken...............................46

Figure 24 An SEM micrograph of the photoresist of swell has been removed from the surface of oxide line .......47

Figure 25 An SEM micrograph of the photoresist contamination, partially removed and entire removal of the photoresist ...........................................48

Figure 26 An OM picture of the sample after the treatment with SCCO2 and the co-solvent in the same condition except the soak pressure.（a）3000 psi,（b）5000 psi,（c）7000 psi ...................................................53

Figure 27 The influence of pressure on the removal of P/R using supercritical fluid............................54

Figure 28 An OM picture of the sample after the treatment with SCCO2 and the co-solvent in the same condition except the chamber temberature.（a）70℃, （b）90℃,（c）110℃ .................................................55

Figure 29 The influence of temperature on the removal of P/R using supercritical fluid..........................56

Figure 30 An OM picture of the sample after the treatment with SCCO2 and the co-solvent in the same condition except the proportion of co-solvent in SCCO2.（a）5 vol.%,（b）7 vol.%,（c）9 vol.% ....................................57

Figure 31 The influence of co-solvent on the removal of P/R using supercritical fluid..........................58

Figure 32 An OM picture of the sample after the treatment with SCCO2 and the co-solvent in the same condition except the cycles for agitation step.（a）4 cycles,（b）6 cycles,（c）8 cycles .........................................59

Figure 33 The influence of fluid flow in flush step on the removal of P/R using supercritical fluid ..............60

Figure 34 The conditions of photoresist removal using SCORR process .........................................61

Figure 35 Vapor-liquid critical surface extrapolated from data given in [10]. The PCO3-CO2 mixture is signal-phace at all conditions above the surface [8] ..................62

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