臺灣博碩士論文加值系統

本論文利用實驗設計法研究以電感式耦合電漿之三氯化硼/溴化氫的氛圍來非選擇性蝕刻砷化銦鎵/砷化鎵/磷化銦鎵等磊晶層。文中將探討壓力、第一射頻功率（粒子加速功率）輸入、第二射頻功率（電感耦合功率）輸入、氣體流量比例等四個製程參數的變化對於蝕刻結果的影響。以電感式耦合電漿的三氯化硼/溴化氫氛圍來非選擇性的蝕刻砷化銦鎵/砷化鎵/磷化銦鎵將可提供一個蝕刻率超過每分鐘2700埃、大於80度的磊晶層側壁、與5以上的磊晶層對氮化矽的選擇比的新製程範圍。
本文所採用的實驗設計法為田口方法之L9直交表。在使用田口方法設計實驗之前，吾人將做一些前導實驗以掌握各製程參數的適當範圍，並評估選擇以光阻或氮化矽為田口方法實驗的罩幕（光罩材料）。此外，在分析直交表實驗的結果之後，吾人將以從田口實驗法所得到的最佳化製程參數來驗證製程的可靠度。
當壓力增加時，氣體粒子的平均自由徑會縮短，而導致物理性離子撞擊減少。因此，壓力愈降低，磊晶層的側壁就會愈陡峭，蝕刻率也會愈大。
另外，電漿的離子能量會隨著第一射頻功率輸入的增加而增加，這也會使得蝕刻率增加，且磊晶層側壁更傾斜，但是這可能會對元件造成損害。然而，較高的第二射頻功率輸入會產生較大的離子密度，所以磊晶層側壁將變得更陡峭，蝕刻率也將增加。
因為三氯化硼具有優異的吸收水氣以及去除材料自然氧化物之能力，所以三氯化硼常被用來蝕刻砷化鎵與相關的化合物。然而，若以三氯化硼的電漿來蝕刻含有銦的化合物半導體材料，則其產物氯化銦比其在蝕刻含鎵材料時的相對應產物－氯化鎵－較不具揮發性。另一方面，例如像溴化氫的含溴物質是一種對含銦、磷材料之良好乾蝕刻劑，因為其反應後的產物溴化銦、溴化磷之蒸汽壓較其相對應的氯化物低。隨著溴化氫的比例增加，不僅蝕刻率上升，且磊晶層側壁也更陡峭。然而，因為溴化氫的高離子化能量，使得它很難被點燃；因此溴化氫的比例不能太高，否則會使得電漿不穩定。

A design of experiment for nonselective etching InGaAs/GaAs/InGaP in inductively coupled plasma (ICP) BCl3/HBr discharges has been investigated. The influences of variations in pressure, RF1 power (chuck power-13.56MHz), RF2 power (ICP power-2MHz), and gas flow (BCl3/HBr) ratio on the etching performance were examined. The combination of BCl3/HBr plasmas made it possible to have a new process window for nonselective etching of InGaAs/GaAs/InGaP in an ICP reactor with high etch rate (> 2700 Å/min), steep epitaxial sidewall (>80º), and over 5 of selectivity of epitaxial layer to silicon nitride.
The design of experiment utilized is the L9 (34) table in Taguchi Method. Prior to Taguchi Method, some pre-experiments were done to realize the proper ranges of the process parameters and to choose either photo-resist or silicon nitride as the mask in L9 (34) experiment. After analyzing the results in L9 Method, experiments using the optimized recipe from L9 Method were run to verify the reliability.
As the pressure increases, the mean free path of gas shortens. It results in reducing physical ion bombardment. Therefore, the more pressure decreases, the steeper the epitaxial profile and the higher the etch rate are.
Ion energy increases as RF1 power. It results in sharper epitaxial sidewall and higher etching rate, but it may cause damage to the device. Moreover, higher RF2 power leads to higher ion density, so the etching profile becomes steeper and the etch rate of epitaxial layer is higher.
BCl3-based mixtures have been found to be attractive plasma chemistries for patterning GaAs and related compounds because of its ability to getter water vapor and readily remove the native oxides on these materials. Nevertheless, as the Indium-based compound semiconductors are etched in the BCl3 discharges, the InClx products are much less volatile than their GaClx counterparts. Bromine-based chemistry, such as HBr, is a good etching chemistry for dry etching indium and phosphorous containing materials because of the relatively low reaction product vapor pressures, InBrx and PBrx, compared to the respective chlorides. The more gas flow ratio of HBr, the higher the etch rate and the more abrupt the epitaxial profile are. However, the HBr gas has high ionization potential so that it is hard to be ignited. We can’t use too high gas flow ratio of HBr; otherwise, the plasma will be unstable.

Contents
摘要-------------------------------------------------------------------------- I
ABSTRACT -------------------------------------------------------------- II
致謝------------------------------------------------------------------------ III
Contents ----------------------------------------------------------------- IV
List of Tables ----------------------------------------------------------- VI
List of Figures ------------------------------------------------------- VIII
Chapter 1. Introduction ---------------------------------------------------------------- 1
Chapter 2. Review of Experiment Theory -------------------------------------- 6
2-1. Design of Experiment (DOE) ---------------------------------------------- 6
2-2. Inductively Coupled Plasma (ICP) ---------------------------------------- 9
2-3. Etchant Chemistry --------------------------------------------------------- 15
2-4. Epitaxy Constitution ------------------------------------------------------- 19
Chapter 3. Experiment ---------------------------------------------------------------- 22
3-1. Experiment using Photo-resist -------------------------------------------- 23
3-2. Experiment using Silicon Nitride (Hard Mask) ------------------------ 24
3-3. Design of Experiment ----------------------------------------------------- 24
3-4. Experiment of Verification ------------------------------------------------ 25
Chapter 4. Result and Discussion ------------------------------------------------- 31
4-1. Experiment using Photo-resist -------------------------------------------- 31
4-2. Experiment using Silicon Nitride (Hard Mask) ------------------------ 34
4-3. Design of Experiment ----------------------------------------------------- 39
4-4. Experiment of Verification ------------------------------------------------ 43
Chapter 5. Conclusion ----------------------------------------------------------------- 82
Reference ------------------------------------------------------------------------------------ 84
List of Tables
Table 2-1-1. The table of orthogonal array of L9 (34) and the response. -------------- 8
Table 2-2-1. The comparison between high-density plasma and capacitively coupled RF plasma. ------------------------------------------------------------------- 13
Table 2-2-2. Applications of inductively coupled plasmas. --------------------------- 13
Table 2-3-1. The boiling points of some etch products in III-V semiconductors. ---------------------------------------------------------------------------------- 18
Table 3-1. The original structure of the epitaxial-wafer. ---------------------------- 27
Table 3-2. The ranges of four parameters for Experiment using Photo-resist. --- 27
Table 3-3. The wafer profile with a 3000Å thick silicon nitride and the epitaxial-layer for Experiment using Silicon Nitride (Hard Mask) and Design of Experiment. ------------------------------------------------------ 27
Table 3-4. The ranges of four parameters for Experiment using Silicon Nitride (Hard Mask). ----------------------------------------------------------------- 28
Table 3-5. The three levels of the four factors of Taguchi L9 method. ------------ 28
Table 3-6. The recipe for each run in the orthogonal array L9 (34). --------------- 28
Table 3-7. The wafer profile with a 1000Å thick silicon nitride and the epitaxial-layer for Experiment of Verification. -------------------------- 29
Table 4-1-1. The whole recipes and the response results in the Experiment using Photo-resist. ------------------------------------------------------------------ 46
Table 4-2-1. The whole recipes and the response results in the Experiment using Silicon Nitride (Hard Mask). ---------------------------------------------- 47
Table 4-3-1. The results of Run No. 1 using the recipe, RF1—50W / RF2—400W / 3mTorr / BCl3—20sccm / HBr—20sccm, in Taguchi L9 Method. ------- 48
Table 4-3-2. The results of Run No. 2 using the recipe, RF1—50W / RF2—600W / 6mTorr / BCl3—27sccm / HBr—13sccm, in Taguchi L9 Method. ------- 48
Table 4-3-3. The results of Run No. 3 using the recipe, RF1—50W / RF2—850W / 10mTorr / BCl3—32sccm / HBr—8sccm, in Taguchi L9 Method. ------- 49
Table 4-3-4. The results of Run No. 4 using the recipe, RF1—120W / RF2—400W / 6mTorr / BCl3—32sccm / HBr—8sccm, in Taguchi L9 Method. -------- 49
Table 4-3-5. The results of Run No. 5 using the recipe, RF1—120W / RF2—600W / 10mTorr / BCl3—20sccm / HBr—20sccm, in Taguchi L9 Method. ----- 50
Table 4-3-6. The results of Run No. 6 using the recipe, RF1—120W / RF2—850W / 3mTorr / BCl3—27sccm / HBr—13sccm, in Taguchi L9 Method. ------- 50
Table 4-3-7. The results of Run No. 7 using the recipe, RF1—200W / RF2—400W / 10mTorr / BCl3—27sccm / HBr—13sccm, in Taguchi L9 Method, and the etching time was 158sec. --------------------------------------------------- 51
Table 4-3-8. The results of Run No. 8 using the recipe, RF1—200W / RF2—600W / 3mTorr / BCl3—32sccm / HBr—8sccm, in Taguchi L9 Method. -------- 51
Table 4-3-9. The results of Run No. 9 using the recipe, RF1—200W / RF2—850W / 6mTorr / BCl3—20sccm / HBr—20sccm, in Taguchi L9 Method. ------- 52
Table 4-3-10. The analysis results for each level of four factors in Taguchi L9 Method. ---------------------------------------------------------------------------------- 52
Table 4-4-1. The results of Base-line 01 using the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm. --------------------------------- 53
Table 4-4-2. The results of Base-line 02 using the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm. --------------------------------- 53
Table 4-4-3. The results of Critical Condition 01 (After a special recipe) using the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm. ---------------------------------------------------------------- 54
Table 4-4-4. The results of Critical Condition 02 (Stand by for 24 hours) using the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm. ---------------------------------------------------------------- 54
Table 4-4-5. The results of Critical Condition 03 (After wet-clean and dry-clean) using the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm. ---------------------------------------------------------------- 55
List of Figures
Figure 1-1. A representative epitaxial layer structure of a GaAs HBT. ------------- 4
Figure 1-2. Simplified schematic cross sections of a GaAs HBT and a monolithically integrated Schottky diode. --------------------------------- 4
Figure 1-3. Schematic diagram of the cross section of etched sample and the responses to get in this study. ----------------------------------------------- 5
Figure 2-2-1. A sketch of the structure of an inductively coupled plasma reactor. --------------------------------------------------------------------------------- 14
Figure 2-2-2. A block diagram of an inductively coupled plasma system. ---------- 14
Figure 2-4-1. The energy bandgap as a function of lattice constant for several elemental and compound semiconductors. ------------------------------ 21
Figure 3-1. The flow chart of this study, which is divided into 4 parts of experiments. ----------------------------------------------------------------- 30
Figure 3-2. The three samples were named as “a”, “b”, and “c” from top to bottom, and the direction of carrier loaded into ICP system was fixed. ------- 30
Figure 4-1-1(a). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 5mTorr / BCl3—40sccm, without baking the mask (photo-resist) at low magnification. -------------------------------------------------------- 56
Figure 4-1-1(b). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 5mTorr / BCl3—40sccm, without baking the mask (PR) at high magnification. ------------------------------------------------------------- 56
Figure 4-1-2(a). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 5mTorr / BCl3—40sccm, with baking the mask (PR) at low magnification. ------------------------------------------------------------- 56
Figure 4-1-2(b). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 5mTorr / BCl3—40sccm, with baking the mask (PR) at high magnification. ------------------------------------------------------------- 56
Figure 4-1-3(a). SEM photo shows the result of the recipe, RF1—100W / RF2—850W / 5mTorr / BCl3—40sccm, with baking the mask (PR) at low magnification. ------------------------------------------------------------- 57
Figure 4-1-3(b). SEM photo shows the result of the recipe, RF1—100W / RF2—850W / 5mTorr / BCl3—40sccm, with baking the mask (PR) at high magnification. ------------------------------------------------------------- 57
Figure 4-1-4. SEM photo shows the result of the recipe, RF1—100W / RF2—400W / 5mTorr / BCl3—40sccm, with baking the mask (PR). ----------------- 57
Figure 4-1-5(a). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 5mTorr / BCl3—40sccm, with baking the mask (PR) at low magnification. ------------------------------------------------------------- 57
Figure 4-1-5(b). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 5mTorr / BCl3—40sccm, with baking the mask (PR) at high magnification. ------------------------------------------------------------- 58
Figure 4-1-6(a). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 3mTorr / BCl3—40sccm, with baking the mask (PR) at low magnification. ------------------------------------------------------------- 58
Figure 4-1-6(b). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 3mTorr / BCl3—40sccm, with baking the mask (PR) at high magnification. ------------------------------------------------------------- 58
Figure 4-1-7(a). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 10mTorr / BCl3—40sccm, with baking the mask (PR) at high magnification. ------------------------------------------------------------- 58
Figure 4-1-7(b). SEM photo shows the surface morphology of the recipe, RF1—50W / RF2—400W / 10mTorr / BCl3—40sccm, with baking the mask (PR). ------------------------------------------------------------------------------- 59
Figure 4-1-8(a). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 15mTorr / BCl3—40sccm, with baking the mask (PR) at low magnification. ------------------------------------------------------------- 59
Figure 4-1-8(b). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 15mTorr / BCl3—40sccm, with baking the mask (PR) at high magnification. ------------------------------------------------------------- 59
Figure 4-1-9(a). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 3mTorr / BCl3—20sccm / HBr—20sccm, with baking the mask (PR) at low magnification. -------------------------------------------------------- 59
Figure 4-1-9(b). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 3mTorr / BCl3—20sccm / HBr—20sccm, with baking the mask (PR) at high magnification. ------------------------------------------------------- 60
Figure 4-1-10(a). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 5mTorr / BCl3—20sccm / HBr—20sccm, with baking the mask (PR) at low magnification. --------------------------------------------------- 60
Figure 4-1-10(b). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 5mTorr / BCl3—20sccm / HBr—20sccm, with baking the mask (PR) at high magnification. -------------------------------------------------- 60
Figure 4-1-11(a). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 10mTorr / BCl3—20sccm / HBr—20sccm, with baking the mask (PR) at low magnification. --------------------------------------------------- 60
Figure 4-1-11(b). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 10mTorr / BCl3—20sccm / HBr—20sccm, with baking the mask (PR) at high magnification. -------------------------------------------------- 61
Figure 4-2-1(a). SEM micrograph shows the original profile of silicon nitride, hard mask, at low magnification, and the thickness of nitride is 3000Å. ----------------------------------------------------------------------------- 61
Figure 4-2-1(b). SEM micrograph shows the original profile of silicon nitride, hard mask, at high magnification, and the thickness of nitride is 3000Å. ----------------------------------------------------------------------------- 61
Figure 4-2-2(a). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------------------------- 61
Figure 4-2-2(b). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at high magnification. ----------------------------------------------------------- 62
Figure 4-2-3(a). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------- 62
Figure 4-2-3(b). SEM photo shows the result of the recipe, RF1—50W / RF2—400W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at high magnification. ---------------------------------------- 62
Figure 4-2-4(a). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------------------------- 62
Figure 4-2-4(b). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at high magnification. ----------------------------------------------------------- 63
Figure 4-2-5(a). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------- 63
Figure 4-2-5(b). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at high magnification. ---------------------------------------- 63
Figure 4-2-6(a). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 3mTorr / BCl3—40sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------------------------- 63
Figure 4-2-6(b). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 3mTorr / BCl3—40sccm, with hard mask (silicon nitride) at high magnification. ----------------------------------------------------------- 64
Figure 4-2-7(a). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 3mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------- 64
Figure 4-2-7(b). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 3mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at high magnification. ---------------------------------------- 64
Figure 4-2-8(a). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 10mTorr / BCl3—40sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------------------------- 64
Figure 4-2-8(b). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 10mTorr / BCl3—40sccm, with hard mask (silicon nitride) at high magnification. ----------------------------------------------------------- 65
Figure 4-2-9(a). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 15mTorr / BCl3—40sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------------------------- 65
Figure 4-2-9(b). SEM photo shows the result of the recipe, RF1—200W / RF2—850W / 15mTorr / BCl3—40sccm, with hard mask (silicon nitride) at high magnification. ----------------------------------------------------------- 65
Figure 4-2-10(a). SEM photo shows the result of the recipe, RF1—100W / RF2—850W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------------------------- 65
Figure 4-2-10(b). SEM photo shows the result of the recipe, RF1—100W / RF2—850W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at high magnification. ----------------------------------------------------------- 66
Figure 4-2-11(a). SEM photo shows the result of the recipe, RF1—100W / RF2—850W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------- 66
Figure 4-2-11(b). SEM photo shows the result of the recipe, RF1—100W / RF2—850W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at high magnification. ---------------------------------------- 66
Figure 4-2-12(a). SEM photo shows the result of the recipe, RF1—200W / RF2—400W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------------------------- 66
Figure 4-2-12(b). SEM photo shows the result of the recipe, RF1—200W / RF2—400W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at high magnification. ----------------------------------------------------------- 67
Figure 4-2-13(a). SEM photo shows the result of the recipe, RF1—200W / RF2—400W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------- 67
Figure 4-2-13(b). SEM photo shows the result of the recipe, RF1—200W / RF2—400W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at high magnification. ---------------------------------------- 67
Figure 4-2-14(a). SEM photo shows the result of the recipe, RF1—100W / RF2—400W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------------------------- 67
Figure 4-2-14(b). SEM photo shows the result of the recipe, RF1—100W / RF2—400W / 5mTorr / BCl3—40sccm, with hard mask (silicon nitride) at high magnification. ----------------------------------------------------------- 68
Figure 4-2-15(a). SEM photo shows the result of the recipe, RF1—100W / RF2—400W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at low magnification. ----------------------------------------- 68
Figure 4-2-15(b). SEM photo shows the result of the recipe, RF1—100W / RF2—400W / 5mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) at high magnification. ---------------------------------------- 68
Figure 4-3-1(a). SEM photo shows the result of the recipe No. 1, RF1—50W / RF2—400W / 3mTorr / BCl3—20sccm / HBr—20sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “a”. ----------------------------------------------------------------------------- 68
Figure 4-3-1(b). SEM photo shows the result of the recipe No. 1, RF1—50W / RF2—400W / 3mTorr / BCl3—20sccm / HBr—20sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “b”. ----------------------------------------------------------------------------- 69
Figure 4-3-1(c). SEM photo shows the result of the recipe No. 1, RF1—50W / RF2—400W / 3mTorr / BCl3—20sccm / HBr—20sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “c”. ----------------------------------------------------------------------------- 69
Figure 4-3-2(a). SEM photo shows the result of the recipe No. 2, RF1—50W / RF2—600W / 6mTorr / BCl3—27sccm / HBr—13sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “a”. ----------------------------------------------------------------------------- 69
Figure 4-3-2(b). SEM photo shows the result of the recipe No. 2, RF1—50W / RF2—600W / 6mTorr / BCl3—27sccm / HBr—13sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “b”. ----------------------------------------------------------------------------- 69
Figure 4-3-2(c). SEM photo shows the result of the recipe No. 2, RF1—50W / RF2—600W / 6mTorr / BCl3—27sccm / HBr—13sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “c”. ----------------------------------------------------------------------------- 70
Figure 4-3-3(a). SEM photo shows the result of the recipe No. 3, RF1—50W / RF2—850W / 10mTorr / BCl3—32sccm / HBr—8sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “a”. ----------------------------------------------------------------------------- 70
Figure 4-3-3(b). SEM photo shows the result of the recipe No. 3, RF1—50W / RF2—850W / 10mTorr / BCl3—32sccm / HBr—8sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “b”. ----------------------------------------------------------------------------- 70
Figure 4-3-3(c). SEM photo shows the result of the recipe No. 3, RF1—50W / RF2—850W / 10mTorr / BCl3—32sccm / HBr—8sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “c”. ----------------------------------------------------------------------------- 70
Figure 4-3-4(a). SEM photo shows the result of the recipe No. 4, RF1—120W / RF2—400W / 6mTorr / BCl3—32sccm / HBr—8sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “a”. ----------------------------------------------------------------------------- 71
Figure 4-3-4(b). SEM photo shows the result of the recipe No. 4, RF1—120W / RF2—400W / 6mTorr / BCl3—32sccm / HBr—8sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “b”. ----------------------------------------------------------------------------- 71
Figure 4-3-4(c). SEM photo shows the result of the recipe No. 4, RF1—120W / RF2—400W / 6mTorr / BCl3—32sccm / HBr—8sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “c”. ----------------------------------------------------------------------------- 71
Figure 4-3-5(a). SEM photo shows the result of the recipe No. 5, RF1—120W / RF2—600W / 10mTorr / BCl3—20sccm / HBr—20sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “a”. ----------------------------------------------------------------------------- 71
Figure 4-3-5(b). SEM photo shows the result of the recipe No. 5, RF1—120W / RF2—600W / 10mTorr / BCl3—20sccm / HBr—20sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “b”. ----------------------------------------------------------------------------- 72
Figure 4-3-5(c). SEM photo shows the result of the recipe No. 5, RF1—120W / RF2—600W / 10mTorr / BCl3—20sccm / HBr—20sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “c”. ----------------------------------------------------------------------------- 72
Figure 4-3-6(a). SEM photo shows the result of the recipe No. 6, RF1—120W / RF2—850W / 3mTorr / BCl3—27sccm / HBr—13sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “a”. ----------------------------------------------------------------------------- 72
Figure 4-3-6(b). SEM photo shows the result of the recipe No. 6, RF1—120W / RF2—850W / 3mTorr / BCl3—27sccm / HBr—13sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “b”. ----------------------------------------------------------------------------- 72
Figure 4-3-6(c). SEM photo shows the result of the recipe No. 6, RF1—120W / RF2—850W / 3mTorr / BCl3—27sccm / HBr—13sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “c”. ----------------------------------------------------------------------------- 73
Figure 4-3-7(a). SEM photo shows the result of the recipe No. 7, RF1—200W / RF2—400W / 10mTorr / BCl3—27sccm / HBr—13sccm, of Taguchi method with hard mask (silicon nitride) for 158sec at position “a”. ----------------------------------------------------------------------------- 73
Figure 4-3-7(b). SEM photo shows the result of the recipe No. 7, RF1—200W / RF2—400W / 10mTorr / BCl3—27sccm / HBr—13sccm, of Taguchi method with hard mask (silicon nitride) for 158sec at position “b”. ----------------------------------------------------------------------------- 73
Figure 4-3-7(c). SEM photo shows the result of the recipe No. 7, RF1—200W / RF2—400W / 10mTorr / BCl3—27sccm / HBr—13sccm, of Taguchi method with hard mask (silicon nitride) for 158sec at position “c”. ----------------------------------------------------------------------------- 73
Figure 4-3-8(a). SEM photo shows the result of the recipe No. 8, RF1—200W / RF2—600W / 3mTorr / BCl3—32sccm / HBr—8sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “a”. ----------------------------------------------------------------------------- 74
Figure 4-3-8(b). SEM photo shows the result of the recipe No. 8, RF1—200W / RF2—600W / 3mTorr / BCl3—32sccm / HBr—8sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “b”. ----------------------------------------------------------------------------- 74
Figure 4-3-8(c). SEM photo shows the result of the recipe No. 8, RF1—200W / RF2—600W / 3mTorr / BCl3—32sccm / HBr—8sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “c”. ----------------------------------------------------------------------------- 74
Figure 4-3-9(a). SEM photo shows the result of the recipe No. 9, RF1—200W / RF2—850W / 6mTorr / BCl3—20sccm / HBr—20sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “a”. ----------------------------------------------------------------------------- 74
Figure 4-3-9(b). SEM photo shows the result of the recipe No. 9, RF1—200W / RF2—850W / 6mTorr / BCl3—20sccm / HBr—20sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “b”. ----------------------------------------------------------------------------- 75
Figure 4-3-9(c). SEM photo shows the result of the recipe No. 9, RF1—200W / RF2—850W / 6mTorr / BCl3—20sccm / HBr—20sccm, of Taguchi method with hard mask (silicon nitride) for 120sec at position “c”. ----------------------------------------------------------------------------- 75
Figure 4-3-10. Angle of epitaxial layer as functions of RF1 power, RF2 power, pressure, and gas flow ratio of BCl3/HBr. --------------------------- 75
Figure 4-3-11. Foot angle (the angle of substrate) as functions of RF1 power, RF2 power, pressure, and gas flow ratio of BCl3/HBr. ------------------ 75
Figure 4-3-12. Etch rate of epitaxial layer as functions of RF1 power, RF2 power, pressure, and gas flow ratio of BCl3/HBr. --------------------------- 76
Figure 4-3-13. Etch rate of silicon nitride layer as functions of RF1 power, RF2 power, pressure, and gas flow ratio of BCl3/HBr. ------------------ 76
Figure 4-3-14. Selectivity of epitaxial layer to nitride as functions of RF1 power, RF2 power, pressure, and gas flow ratio of BCl3/HBr. ------------- 76
Figure 4-3-15. Average roughness [Ra], where there was no pattern, as functions of RF1 power, RF2 power, pressure, and gas flow ratio of BCl3/HBr. ----------------------------------------------------------------------------- 76
Figure 4-4-1. SEM micrograph shows the original profile of silicon nitride, hard mask, and the thickness of nitride is 1000Å. ------------------------ 77
Figure 4-4-2(a). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, from Taguchi analysis method with hard mask (silicon nitride) for 30sec etching at position “a” for Baseline 01. ----------------------------------------- 77
Figure 4-4-2(b). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, from Taguchi analysis method with hard mask (silicon nitride) for 30sec etching at position “b” for Baseline 01. ----------------------------------------- 77
Figure 4-4-2(c). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, from Taguchi analysis method with hard mask (silicon nitride) for 30sec etching at position “c” for Baseline 01. ------------------------------------------ 77
Figure 4-4-3(a). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, from Taguchi analysis method with hard mask (silicon nitride) for 30sec etching at position “a” for Baseline 02. ----------------------------------------- 78
Figure 4-4-3(b). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, from Taguchi analysis method with hard mask (silicon nitride) for 30sec etching at position “b” for Baseline 02. ----------------------------------------- 78
Figure 4-4-3(c). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, from Taguchi analysis method with hard mask (silicon nitride) for 30sec etching at position “c” for Baseline 02. ------------------------------------------ 78
Figure 4-4-4(a). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) for 30sec etching at position “a” for Critical Condition 01 (After a special recipe). ------------------------------------------------ 78
Figure 4-4-4(b). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) for 30sec etching at position “b” for Critical Condition 01 (After a special recipe). ------------------------------------------------ 79
Figure 4-4-4(c). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) for 30sec etching at position “c” for Critical Condition 01 (After a special recipe). ------------------------------------------------ 79
Figure 4-4-5(a). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) for 30sec etching at position “a” for Critical Condition 02 (Stand by for 24 hours). ------------------------------------------------ 79
Figure 4-4-5(b). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) for 30sec etching at position “b” for Critical Condition 02 (Stand by for 24 hours). ------------------------------------------------ 79
Figure 4-4-5(c). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) for 30sec etching at position “c” for Critical Condition 02 (Stand by for 24 hours). ------------------------------------------------ 80
Figure 4-4-6(a). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) for 30sec etching at position “a” for Critical Condition 03 (After wet-clean and dry-clean). -------------------------------------- 80
Figure 4-4-6(b). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) for 30sec etching at position “b” for Critical Condition 03 (After wet-clean and dry-clean). -------------------------------------- 80
Figure 4-4-6(c). SEM photo shows the result of the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, with hard mask (silicon nitride) for 30sec etching at position “c” for Critical Condition 03 (After wet-clean and dry-clean). -------------------------------------- 80
Figure 4-4-7. The average etching angle of epi-layer and that of substrate for the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, in different chamber conditions. --------------------- 81
Figure 4-4-8. The selectivity, the etching rate of epi-layer and that of silicon nitride for the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, in different chamber conditions. ----------------------------------------------------------------------------- 81
Figure 4-4-9. The mean of average roughness (Ra) for the recipe, RF1—120W / RF2—850W / 10mTorr / BCl3—20sccm / HBr—20sccm, in different chamber conditions. ---------------------------------------------------- 81

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