| 摘要: | 化學氣相沉積法(chemical vapor deposition)在半導體薄膜生長製程中已是常見之方法。針對10奈米以下半導體製程所需之12吋磊晶晶圓改善平坦度，其中關鍵技術為：1.超均勻之磊晶薄膜 2.矽晶圓基材與磊晶薄膜的形狀匹配。本研究採用多重物理量有限元素分析軟體(COMSOL Multiphysics)建立磊晶製程係使用應用材料Centura®常壓磊晶反應腔體進行熱場、流場、物種傳輸模擬分析，比較以不同之進氣流量配比(Accuset)、載盤轉速與氣體混和區的幾何形狀(Upper liner and low liner)、石英上蓋設計(Upper dome)對於薄膜生長速率(Growth rate)之影響。
當生長大尺寸矽磊晶薄膜時，因反應腔體尺寸過大、幾何形狀過於複雜，不容易使晶圓上方的薄膜達到良好的均勻性，因此本研究首先建立起三維物理模型，當氫氣與三氯矽烷(Trichlorosilane)通入反應腔體時，三氯矽烷與氫氣會隨著溫度變化產生化學表面吸附反應。當製程溫度為1050℃-1150℃時，不同的進氣流量配比與氣體混和區的幾何形狀將影響矽磊晶薄膜的輪廓外型、薄膜沉積速率與平坦度。從模擬結果發現，藉由溫度場分析，去除氣體混和區的幾何形狀(partition)，有助於氣體進入腔體前，減少溫度梯度，使混和氣體濃度更均勻，使薄膜達到較好的均勻度；從石英上蓋設計上，腔體高度及曲率半徑大小也會影響Growth rate profile甚大，在曲率半徑愈小、腔高愈大時，並搭配進氣流量比，將可得到均勻性較佳的結果。
接著，在製程參數上，加入旋轉的條件也可達到提高均勻性的效果，在模擬結果中得到，加入轉速後的均勻性皆比未旋轉時的情況較佳，並且提高轉速也可提高均勻度，在去除partition後，除了旋轉可提高均勻度的優點外，原本出現局部長率較低的現象也可有效改善。
;Chemical vapor deposition is a common method in semiconductor thin film growth processes. The flatness is improved for 12-inch epitaxial wafers required for semiconductor processes below 10 nm. The key technologies are: 1. Ultra-uniform epitaxial film 2. The wafer substrate is matched with the shape of the epitaxial film. In this study, the multi-physics finite element analysis software (COMSOL Multiphysics) was used to establish the epitaxial process system. The thermal field, flow field and species transfer simulation were performed using the applied material Centura® atmospheric pressure epitaxy reaction chamber. The effects of different Accuset, Upper liner and low liner, and Upper dome on the growth rate of the film were compared.
When growing large-size tantalum epitaxial films, the size of the reaction chamber is too large and the geometry is too complicated, so it is not easy to achieve good uniformity of the film above the wafer. Therefore, this study first establishes a three-dimensional physical model, when hydrogen and trichlorosilane is introduced into the reaction chamber, trichlorosilane and hydrogen will react with temperature to produce a chemical surface adsorption reaction. When the process temperature is 1050℃ to 1150 °C, the different inlet flow ratio and the geometry of the gas mixing zone will affect the shape, film deposition rate and flatness of the bismuth epitaxial film. From the simulation results, it is found that the temperature field analysis removes the geometry of the gas mixing zone, helps the gas to enter the cavity, reduces the temperature gradient, makes the concentration of the mixed gas more uniform, and achieves a better uniformity of the film. From the quartz cover design, the height of the cavity and the radius of curvature also affect the Growth rate profile. The smaller the radius of curvature, the larger the cavity height, and the ratio of the intake flow rate, the better uniformity results.
Then, in the process parameters, the addition of the rotation condition can also achieve the effect of improving the uniformity. In the simulation results, the uniformity after the addition of the rotation speed is better than that when the rotation is not performed, and the increase of the rotation speed can also improve the uniformity. After the partition is removed, in addition to the advantage that the rotation can improve the uniformity, the phenomenon that the local growth rate is low can be effectively improved. |
