请问roughness analys 时，SSK、SKu、S10z[nm]各是什么含义？

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Wasp replied on Wed, Mar 4 2015 9:18 PM

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我们这里只有这样一个关于S10z的解释：S10z[nm] - the average height of the five highest local maximums plus the average height of the five lowest local minimums。

那究竟这两个参数是否可以表征图片的信噪比呢？或者说是不是Ssk越偏离0，Sku越偏离3，就说明图片受噪音的影响就越大？

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Hao Sun replied on Wed, Mar 4 2015 9:32 PM

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所以S10z在您的软件中的意思是五个最高点的平均值加上五个最低点的平均值。在我们的新的NSA离线软件中没有这个参数的相应参数。请问您使用的软件是？

这些参数均与噪声没有直接关系。如果要评估噪声，一般是使用均方根粗糙度Rq。具体方法是扫描一个0nm的位置，进行一阶拉平后将Rq与仪器噪声指标进行对比。

假定你的图片中有噪声，同没有噪声相比，Ssk并不能说明问题，因为两个图都可能是对称分布的。噪声也有正有负。Sku则能部分反映，因有噪声时数据的分布范围比较宽，但一般仪器的指标不会用它来衡量。S10z类似Ssk。所以最直接的比较还是均方根粗糙度。

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Hao Sun replied on Wed, Mar 4 2015 9:34 PM

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贴一个仪器指标的一般测试方法（以Icon原子力为例）：

仪器指标检测：

扫描管范围检测：XY：____ m，应不小于85m______(√)；Z：____ m，应不小于9.5m______(√)

测试方法：在XYZ开环下，将XYZ方向的扫描电压设置为最大值，检查最大扫描电压对应的扫描范围。

系统噪音检测：  ____ nm RMS ，应小于0.03nm______(√)

测试方法：打开XY方向的闭环，在tapping模式下扫描0 nm范围，扫描速度2.44 Hz获取Height图像，测量图像的Rq值。

扫描管Z方向闭环噪音水平： ____ nm RMS，应小于0.035nm ______(√)

测试方法：打开XY方向闭环，假进针，扫描范围0.01 nm，扫描速度2.44 Hz，获取Height sensor图像，测量图像的Rq值。

X方向的精确度： <2%       ____(√)

测试方法：扫描标准样品，确保测量的尺寸与标准尺寸的偏差在1%以内。

Y方向的精确度： <2%       _____(√)

测试方法：扫描标准样品，确保测量的尺寸与标准尺寸的偏差在1%以内。

Z方向的精确度： <2%       _____(√)

测试方法：扫描标准样品，确保测量的尺寸与标准尺寸的偏差在1%以内。

闭环扫描管的XY方向正交性： ____°（90°±2°）

测试方法：扫描标准样品，测量所获得的光栅图像X边缘与Y边缘的角度，确保此角度在90°±2°范围内。

样品台XY方向移动范围： X方向    _____mm，应≧180mm  _____(√)

                       Y方向    _____mm，应≧150mm  _____(√)

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Wasp replied on Wed, Mar 4 2015 11:15 PM

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好的，我们去试试。谢谢孙博士！

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Teddy Huang replied on Mon, Mar 16 2015 1:00 AM

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孙老师解释的很清楚。我也是第一次看到中文的翻译。受教了。

其实对各个参数，Nanoscope Analysis的说明书上也有介绍。在使用Nanoscope Analysis的时候按F1，说明书就出来了。一下是说明书来的，粘贴过程公式丢失，详见说明书。

如果你需要最新版的Nanoscope Analysis的软件，我可以提供下载链接。

Results Parameters

Statistics used by the Roughness routine are defined in this section. The terms are listed alphabetically. Most are derived from ASME B46.12 (“Surface Texture: Surface Roughness, Waviness and Lay”) available from the American Society of Mechanical Engineers.

Parameter	Description
Image Raw Mean	Mean value of data contained within the whole image, except for stop bands. This is calculated as if the OL Plane fit were set to None during image capture.
Image Mean	Mean value of data contained within the whole image, except for stop bands. This is calculated after the OL Plane fit set during image capture has been applied.
Image Z Range	Maximum vertical distance between the highest and lowest data points in the image prior to the planefit.
Image Surface Area	The three-dimensional area of the entire image. This value is the sum of the area of all of the triangles formed by three adjacent data points.
Image Projected Surface Area	Area of the image rectangle (X x Y).
Image Surface Area Difference	Difference between the image’s three-dimensional Surface area and two dimensional projected surface area.
Image Rq	Root mean square average of height deviations taken from the mean image data plane, expressed as:
Image Ra	Arithmetic average of the absolute values of the surface height deviations measured from the mean plane.
Image Rmax	Maximum vertical distance between the highest and lowest data points in the image following the planefit.
Raw Mean	Mean value of image data within the cursor box you define without application of plane fitting. This is calculated as if the OL Planefit were set to None during image capture.
Mean	The average of all the Z values within the enclosed area. The mean can have a negative value because the Z values are measured relative to the Z value when the microscope is engaged. This value is not corrected for tilt in the plane of the data; therefore, plane fitting or flattening the data changes this value. This is calculated after the OL Planefit set during image capture has been applied.
Z Range	Peak-to-valley difference in height values within the analyzed region.
Surface Area	The three-dimensional area of the region enclosed by the cursor box. This value is the sum of the area of all of the triangles formed by three adjacent data points.
Projected Surface Area	Area of the selected data.
Surface Area Difference	Difference between the analyzed region’s three-dimensional Surface area and its two-dimensional, footprint area.
Rq	This is the standard deviation of the Z values within the box cursor and is calculated as: where Zi is the current Z value, and N is the number of points within the box cursor. This value is not corrected for tilt in the plane of the data; therefore, plane fitting or flattening the data changes this value.
Ra	Arithmetic average of the absolute values of the surface height deviations measured from the mean plane within the box cursor:
Rmax
Skewness	Measures the symmetry of surface data about a mean data profile, expressed as: where Rq is the Rms roughness. Skewness is a non dimensional quantity which is typically evaluated in terms of positive or negative. Where Skewness is zero, an even distribution of data around the mean data plane is suggested. Where Skewness is strongly non-zero, an asymmetric, onetailed distribution is suggested, such as a flat plane having a small, sharp spike (> 0), or a small, deep pit (< 0).
Kurtosis	This is a non-dimensional quantity used to evaluate the shape of data about a central mean. It is calculated as Graphically, kurtosis indicates whether data are arranged flatly or sharply about the mean.
Rz	This is the average difference in height between the (RZ Count value) highest peaks and valleys relative to the Mean Plane.
Rz Count	Number of peak/valley pairs that are used to calculate the value Rz.
Peak Count	The number of peaks taller than the Threshold Value.
Valley Count	The number of valleys shorter than the Threshold Value.
Max Peak ht (Rp)	Maximum peak height within the analyzed area with respect to the mean data plane.
Average Max Height (Rpm)	Average distance between the (Peak Count value) highest profile points and the mean data plane.
Maximum Depth (Rv)	Lowest data point in examined region.
Average Max Depth (Rvm)	Average distance between the (Valley Count value) lowest profile points and the mean data plane.
Line Density	The number of zero crossings per unit length on the X and Y center lines of the box cursor. A zero crossing is a point where the Z values go through zero regardless of slope. This value is the total number of zero crossings along both the X and Y center lines divided by the sum of the box dimensions.
Box X Dimension	The width of the Lx box cursor you define.
Box Y Dimension	The length of the Ly box cursor you define.

Table 3: Roughness Results

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Hao Sun replied on Tue, Mar 17 2015 6:36 AM

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谢谢Teddy的补充！

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Wasp replied on Tue, Mar 17 2015 6:59 PM

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非常感谢！还望提供链接。谢谢！

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Teddy Huang replied on Tue, Mar 17 2015 7:12 PM

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留个邮箱或者发request给我到 teddy.huang@bruker.com

谢谢

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Wasp replied on Thu, Mar 26 2015 1:22 AM

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孙博士，我用两套参数测试roughness（tapping mode）。 其中Amplitude较高的得到的Rq=0.114nm  SSK=0.0571  SKU=3.06

Amplitude较低的得到的Rq=0.14nm  SSK=0.116  SKU=3.3   

然后我有用scan size=0um 去测试Rq，  其中Amplitude较高的得到的Rq=0.0694nm  其中Amplitude较低的得到的Rq=0.0534nm

那么这两套参数谁的信噪比更好呢？怎么解释这种现象？谢谢！

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Hao Sun replied on Sun, Mar 29 2015 10:53 PM

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Tapping mode下测roughness和很多因素相关，必须固定探针以及探针和样品间的作用力来测量，这样得到的结果才能进行比较。若在不同的Amplitude下，由于探针与样品的相互作用不同，且因响应时间不同而导致Gain的最优设置不同，都会对Roughness有影响。所以不能直接比较。

请问您的应用是什么，为什么要比较信噪比？

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Wasp replied on Mon, Mar 30 2015 12:10 AM

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我们测试的roughness小于0.4nm的样品。Amplitude小的我们用的gain值也会相应的减小。

请问噪音到了什么程度就可能影响到Rq的结果呢？有没有一个衡量的标准？

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Hao Sun replied on Mon, Mar 30 2015 12:23 AM

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如果使用Low Force Tapping来测超平样品，在Amplitude减小时由于响应时间随之减小，相应的Gain应该增大，否则就失去了小振幅的优势。请参考以下Low Force Tapping的步骤和注意事项：

（以MM8为例，软件版本为8.1x，其他版本软件原理类似）

3. High resolution imaging with tapping Mode

A. Probe selection: OLTESPA or FESPA probes are suitable for high resolution imaging under tapping mode. Stiffer probe like TESPA causes too much impact to the sample, it is not recommended due to the worse force control. Probe without coating such as TESP, RTESP is also not recommended, because the signal-noise ratio becomes lower due to low SUM signal.

B. Sample: In this case we use alkane sample for high resolution imaging experiments.

C: Force control: Tapping force control is more difficult than Peak Force Tapping force control, because the relationship between tapping amplitude and tapping force is more complex. Under tapping mode, to control force, one should finely adjust amplitude setpoint and drive amplitude. The relationship between tapping amplitude and tapping force was demonstrated by Chanmin Su, Lin Huang, et al. (2003) and Shuiqing Hu (2007). This is shown in following picture. Tip wear often happens at the middle amplitude setpoint values. To achieve high resolution in tapping mode, one can use “Low force tapping” technique invented by Lin Huang et al. which is operating at very low amplitude setpoint and produces very low tip-sample interactions. The low setpoint operation enables high feedback loop gain, which improves tracking and reduces tip wear. However, sometimes it can results in 0 amplitude on rough samples at high scan rate.

D. D. Noise control: For MultiMode SPM system, put the microscope on the triple to reduce the environmental noise.

E. Procedure:

(1) Start the NanoScope v8 software by double clicking the NanoScope software icon on the Windows desktop.

(2) In “Select Experiment” Window, choose “Tapping Mode” and correct experiment group due to your experiment, and then click “Load Experiment”.

(3) Go to “Microscope” Menu, select “Engage Settings”. “Engage Parameters” pops up, in this window, set “Sew tip” to “Yes”, which can protect probe during engage process. Then click ‘OK”.

(4) Click “Setup” icon on the workflow toolbar, in “Tune cantilever” windows, click “Manual Tune” to open “Cantilever Tune” window. On “Auto Tune” Panel, modify the default “Target amplitude” to a smaller value, usually “100 mV”, set “Peak offset” to “5%”, click “Auto Tune” button. Adjust “Data Scale” in “Channel 1” Panel and “Sweep Width” in “Graph” Panel to make Amplitude-Frequency curve easy to see. Record the “Drive Amplitude” value. Click “Exit” to close “Cantilever Tune” window.

(5) Set initial parameters. Click “Expended Mode” to display more parameters. In “Scan” Panel, set “Scan Size” to “0.00 nm”, “X Offset” and “Y Offset” to “0.000 nm”, “Scan Rate” to “0.977 Hz”. In “Feedback” Panel, set “Integral Gain” to “0.300” and “Proportional Gain” to “1.000”, set “Lock-in BW” to “5k Hz”. In “Limits” Panel, set “Amplitude Limit” to “1000 mV” and “Z Limit” to its max range. Set Data Channel of Height, Amplitude Error, etc.

(6) Explore sample surface under OMV video, the best place to be imaged is flat area around some black spots. Select Microscope > Engage or click the Engage icon on the workflow toolbar to engage the tip.

(7) Reduce the “Drive Amplitude” by 2/3 so that the free amplitude in air should be 60~70 mV now if the “Target Amplitude” is set to “100 mV” when tuning cantilever. Reduce the “Amplitude Setpoint” to 12~15 mV. Increase “Integral Gain”, and monitor the “Amplitude Error” signal. Slightly decrease “Integral Gain” if oscillation is observed.  The peak value of “Amplitude Error” should be less than 10 mV. In “Limits” Panel, decrease “Z Limit” to “1.000 um” to increase vertical resolution. Capture the image.

(8) After imaging, select Microscope > Withdraw or click the Withdraw icon on the workflow toolbar to withdraw the tip.

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Hao Sun replied on Mon, Mar 30 2015 12:24 AM

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请指明您的仪器型号，如果是新型号的仪器做这类应用请使用ScanAsyst模式。