應用曝光模擬系統對 130 nm 微影製程線寬控制之探討

Application of Exposure Simulation System to CD Control Investigation at 130 nm Photolithography Node

黃宇光(Yu-Kuang Huang)

指導教授 ： 陳念波

元智大學/工程學院/電機工程學系/碩士(2006年)

https://doi.org/10.6838/YZU.2006.00070

摘要

在半導體製程中，線寬微距控制是一個很重要的環節。若無法有效的控制線寬變異，曝光時會造成圖形斷線或橋接的現象。當關鍵尺寸持續的縮小，造成特徵解析度會受限於線寬控制能力。當晶圓曝光後的線寬變異量超過誤差值，在光罩上的線寬量測又合乎標準，因此之間的線寬變異可能來自於光罩鉻膜蝕刻的製程變異，造成不同的鉻膜側壁輪廓，而影響到曝光成像結果。可藉由橫切面的分析，清楚得知角度的偏差。在實驗中探討130 nm 製程的光罩，控制光罩的鉻膜側壁傾斜角在 90 度 +/- 5% 範圍之內的三組實驗組，經由AIMS Fab 248 曝光模擬系統來得知線寬變異，以光強度的空間變化來分析光罩上鉻膜傾斜角對晶圓上光阻能量分佈控制的影響，藉此有效的控管光罩品質與曝光結果。模擬結果可得知曝光容忍度在 3% 以內的嚴謹條件下，線寬變量為 4 nm 以內，聚焦深度的 3 sigma 為 17 nm，是可被接受的製程寬容度。當線寬越小的情況下，光罩的製程控制更加艱難，必然會存在著鉻膜側壁傾斜角的變化，間接影響到曝光後線寬的大小。由實驗結果得知，若能夠有效的控制鉻膜側壁傾斜角在小範圍內，在合理的曝光容忍度的條件下，線寬以及聚焦深度範圍是可被接受的。如此，非理想的光罩製程對晶圓曝光所產生的線寬差異之影響，可經由製程窗口的判斷，風險減至最小。

關鍵字

光罩 ； 鉻膜傾斜角 ； 曝光模擬系統 ； 光學趨近效應 ； 偏軸光照明 ； 線寬控制 ； 聚焦深度

並列摘要

In the semiconductor process field, the control of the critical dimension (CD) is a major task, specially in the processes of mask manufacturing and wafer exposure. If the linewidth cannot be well controlled, then the resultant patterns on the wafer may shrink or bridge. It is getting more critical as the technology node is pushed into smaller feature size. One of the difficult problems is that sometimes the linewidth variation on wafer is out of specification even though the linewidth on mask is in specification. The linewidth discrepancy may come from the process control during the chrome film etching, which will influence the sidewall profile of the chrome film pattern. We can get the angular variation of the profile by analyzing the cross-section of the mask. In this study, the masks used in the 130 nm technology node are investigated. Through the simulation done by AIMS fab 248 exposure system, the energy distribution on the photoresist, affected by the sidewall angular variation (90 deg +/- 5%) of the mask, is analyzed with the intensity distribution across the simulated exposure images. The result shows that within 3% of the exposure latitude the process window is acceptable if the linewidth variation is less than 4 nm and the 3 sigma of the depth of the focus (DOF) is 17 nm. The established process window can help the engineers to avoid the linewidth discrepancy between the wafer and the mask, even with the inevitable chrome sidewall angular variation of the mask.

並列關鍵字

AIMS ； Cr profile ； OAI ； OPE ； CD ； E-D Tree ； Process Window ； DOF

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