爐管為半導體產業常使用的製程設備，其良率為重要之技術指標，因此本研究針對垂直式爐管進行流場數值模擬，評估氣體噴注器的流量對於製程良率所產生的影響，藉由晶圓薄膜厚度之實測比對，找出氣體噴注器的出口流量與氣體在晶圓層分佈的相關性。在原始的爐管製程產品量測結果的缺失在於，晶圓的薄膜層厚度不均造成良率下降，因此本研究針對爐管之流場進行模擬分析，以找出其流場的缺失並進行改善。在此所探討之CVD製程中，利用兩根氣體噴注器分別通入矽甲烷(Silane, SiH4)與磷化氫(Phosphine, PH3)的氣體進入爐管以供進行需求之化學反應；在完成原始爐管之模擬後，利用後處理觀察每根噴注器的出口流量與爐管各區域的流場分佈；除此之外，在滿足流量非均勻性15%以內下，找出在氣體噴注器上所能適用的流量範圍，並得到了兩條經驗公式，可用來設計出符合良率要求之爐管模型。而為在晶圓層做進一步的觀察，本研究也利用多相流的數值計算模組VOF(Volume of Fluid)，來計算監控每片晶圓層間的氣體體積，觀察整批晶圓上的氣體分佈。在改變了氣體噴注器的孔洞直徑後，可發現利用參數化的調整，針對兩種不同製程氣體的噴注器，成功地讓每根噴注器的出口流量平均分配；再經由成品實測的結果比對驗證，晶圓上的薄膜層均勻度可有效的提升，所以氣體噴注器的孔洞直徑調整為重要參素。另外也發現入口氣體噴注器的出口流量，對於晶圓層間之氣體體積分佈有相對應的關係，雖然本模擬中並未考慮化學反應，僅在氣體特性與幾何參數作詳細探討，仍對於晶圓上薄膜均勻化的改良有相當的成效。

Furnace is an extensively used device for processing the wafer in semiconductor fabrication, in which the yield rate is the crucial indicator for technical advancement in wafer foundries. It is well known that flow patterns inside the furnace significantly influence the quality of wafer product. Therefore, this study intends to establish the capability for simulating flow fields and distributions of reacting gases inside a vertical diffusion furnace. In the process considered here, two gas supply injectors are implemented to transport silane (SiH4) and phosphine (PH3) to wafer surface for the CVD (chemical vapor deposition) process. Firstly, flow visualization via CFD simulation on the original furnace is carried out carefully to identify the adverse flow patterns inside the furnace and to check the spray uniformity of each gas injector. It is found that the spray non-uniformities of two gas injectors with 4 spray holes are not evenly distributed. For a low-flowrate PH3 (90 sccm), near 45% of PH3 enters the furnace via the 3rd injector hole; thus there is no sufficient PH3 left for the upper portion of furnace, where corresponds to the wafer layers 1 to 60. On the other hand, most of the high-flowrate SiH4 (800 sccm) is injected into the upper part of furnace. Moreover, the VOF (volume of fluid) multiphase model is used to evaluate the volume distributions (concentrations) of all reacting gases in each wafer layer, which is strongly correlated with the measurement on coating thickness over the entire 172 wafers.
Thereafter, a series of diameter modifications on injector holes is executed within the framework of CFD technology for diminishing the non-uniformities from 55.19% and 34.73% to 5.37% and 9.93% for PH3 and SiH4 supply pipes, respectively. Furthermore, this design procedure is performed systematically for various gas flowrates to meet with the practical need. Also, these optimized results are used to generate design formula for constructing an appropriate gas supply injector with the non-uniformity under 15% for the flowrates ranging from 50~7,600 sccm and 50~13,700 sccm for PH3 and SiH4 supply injectors, respectively. As long as the desired flowrate is determined; then all exit diameters in the gas supply injector can be calculated easily via these polynomial formulas. Additionally, VOF calculations on the diffusion furnaces equipped with the revised gas injectors are attained numerically to illustrate the effective improvements on the non-uniformities of these optimized injectors. Thus, it is concluded that appropriate arrangement on opening diameters in the gas supply injector is an effective approach to enhance flow uniformity and yield rate of wafer fabrication. In summary, this research successfully establishes a numerical model and a reliable ready-to-use formula for designing the gas supply injector oven an extensive range of flowrate for PH3 and SiH4. Certainly, this systematic analysis scheme can be employed to improve the wafer production in other furnaces with different reacting gases used in semiconductor process.

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