本研究提出一套「高解析度陰影疊紋式量測系統」，此套系統是由LED光源模組、大面積小週期的線性光柵、影像擷取模組及軟體相位解調模組所組成，其系統架構簡單、組裝及調校容易，具低成本的開發優勢。此套量測系統具全域式的量測能力，可在不移動晶圓的條件下，準確地量測大尺寸(12吋)晶圓之翹曲及其表面形貌，其量測結果不會受定位系統所引入的幾何誤差之影響。
根據我們所提出的量測方法，我們使用白光LED光源模組來形成大範圍的均勻光束，而後使光束穿過光柵後將其週期影像投射至待測晶圓(未拋光矽晶圓)表面形成週期性的陰影條紋，此陰影條紋會受晶圓表面的翹曲或形貌之影響而改變其形態，改變後之陰影條紋影像將被反射後與原光柵再次交疊，形成相對應的陰影疊紋影像，此時可藉由影像擷取模組擷取陰影疊紋影像，而後再透過自行開發的軟體解相模組來解相及分析陰影疊紋影像的相位變化，進而得到待測晶圓的翹曲及其表面形貌。此外，本研究透過光柵(小週期)與影像擷取模組(高解析)的搭配來提升系統的解析度，亦可透過鏡頭倍率之縮放來動態調整影像擷取之範圍，能針對晶圓表面細微之切割痕跡進行三維形貌量測，有效提升陰影疊紋技術的量測能力。再者，本研究所使用快速傅立葉轉換法來進行相位解調模組之開發，相較於常見的四步移相解相技術，本技術具備高速與高準確度的技術優勢，大大提升了此套「高解析度陰影疊紋式量測系統」的應用範圍及其競爭力。
為了驗證「高解析度陰影疊紋式量測系統」的可行性及其量測性能，我們進行了多組量測試驗。首先，由晶圓傾斜角度實驗結果可知，此套系統可量測到的角度變化量可達5 µrad(將其視為系統之角度解析度)，其相對應可辨識的理論高度解析度為0.33 nm，而後我們透過晶圓表面切割痕跡的實驗可以得到此套系統可辨識的最小高度變化為270 nm，故將其定義為此套系統之真實高度解析度，驗證此套系統具備高解析度。此外，因翹曲變化是透過點與點之間的角度差異去得到曲率與曲面的變化，我們透過於晶圓背面黏貼加熱片的方式，藉由給予不同的電壓迫使其產生面的角度變形，而後將本研究提出的陰影疊紋系統量測到的翹曲變化與商用的彩色共焦位移計(Keyence CL-3000)相比較，其量測結果與本研究提出的量測技術結果變化相符，由此實驗可驗證本系統具備晶圓翹曲及其形貌的量測能力。此外，亦藉由旋轉晶圓的實驗結果可知，在不同旋轉角度的條件下進行30次量測，本量測系統的量測結果之一個標準差(σ)為0.35 μm，量測誤差可控制於1.4 %以下，驗證本研究技術具備高重複性。為了更進一步驗證我們量測系統具備微小結構的形貌量測能力，我們亦透過本研究開發的快速傅立葉轉換法及四步移相法之解相模組分析此晶圓上方的表面切割痕跡，並與商用的表面形貌檢測儀(Keyence VK-X3000)進行驗證，其量測結果與本研究提出的量測技術結果相符，驗證了此系統具備微小結構(瑕疵檢測)量測能力。由上述量測結果可知，本研究所提出的「高解析度陰影疊紋式量測系統」可在不移動待測物的條件一次性提供大面積(12吋)晶圓完整的表面翹曲及其形貌，因此驗證本技術具備高量測解析度、全域式量測及高重複性的量測能力，日後能廣泛應用於各式需要進行晶圓翹曲及表面形貌的場合中。

This research proposes a " High-resolution Shadow Moiré Measurement System", which is composed of an LED light source module, a large-area and small-pitch linear grating, an image acquisition module and a software phase demodulation module , the system structure is simple, easy to assemble and calibration, and making it cost-effective to develop. This measurement system has full-field measurement capabilities, and can accurately measure the warpage and surface topography of large-area (12-inch) wafers without moving the wafer. The measurement results will not affected by geometric errors introduced by the positioning system.
According to the measurement method we proposed, we use a white LED light source module to form a large-scale uniform light beam, and then let the beam pass through the grating and project its periodic image onto the surface of the wafer to be tested (unpolished silicon wafer) to form periodic shadow fringes, the shadow fringes will be affected by the warpage or shape of the wafer surface and change its shape, the changed shadow fringe image will be reflected and overlapped with the original grating again to form a corresponding shadow image at this time, the shadow moiré image can be captured by the image acquisition module, and then the self-developed software phase demodulation module can be used to solve the phase and analyze the phase change of the shadow moiré image, and then obtain the wafer to be tested warpage and its surface topography. In addition, this study improves the resolution of the system through the combination of the grating (small pitch) and the image acquisition module (high resolution). The three-dimensional topography measurement of the cutting marks on the wafer surface effectively improves the measurement capability of the shadow moiré technology. In addition, this study developed a phase demodulation module using the fast Fourier transform method. Compared with the common four-step phase-shift phase technology, this technology has the technical advantages of high speed and high accuracy, which greatly improves the application range and competitiveness of the "High-resolution Shadow Moiré Measurement System".
In order to verify the feasibility and measurement performance of the "High-resolution Shadow Moiré Measurement System", we conducted several sets of measurement experiments. First , from the experimental results of wafer tilt angle, it can be known that this system can measure an angle change of up to 5 µrad (consider it as the angular resolution of the system), and its corresponding identifiable theoretical height resolution is 0.33 nm, and then through the experiment of cutting marks on the wafer surface, we can get that the minimum height variation that this system can recognize is 270 nm, so it is defined as the true height resolution of this system, and it is verified that this system has high resolution . In addition, because the warpage change is obtained through the angle difference between points to obtain the change of curvature and surface, we stick the heating plate on the back of the wafer, and force it to generate the surface angle by giving different voltages, and then compare the warpage changes measured by the shadow moiré system proposed in this study with the commercial confocal sensor (Keyence CL-3000), the measurements were consistent with the variation in the results of the measurement techniques proposed in this study, so the experiment can verify that the system has the ability to measure wafer warpage and its surface topography. In addition, based on the experimental results of rotating the wafer, it can be known that the standard deviation (σ) of the measurement results of this measurement system is 0.35 μm under the condition of 30 measurements at different rotation angles, and the measurement error can be controlled below 1.4 %, it is verified that the research technique has high repeatability. In order to further verify that our measurement system has the ability to measure the surface topography of tiny structures, we also analyzed the cutting marks on the surface of the wafer through the fast Fourier transform method and the phase demodulation module of the four-step phase shift method developed in this research. And verified with a commercial surface topography tester (Keyence VK-X3000), the measurement results are consistent with the results of the measurement technology proposed in this study, which verifies that the system has the measurement capability of microstructure (defect detection). From the above measurement results, it can be seen that the " High-resolution Shadow Moiré Measurement System " proposed by this research can provide full-field surface warpage and its topography, therefore, it has been confirmed that this technology has high measurement resolution, full-field measurement and high repeatability measurement capabilities, and can be widely used in various situations that require the measurement of wafer warpage and surface topography in the future.

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