复合型高深宽比沟槽标准样板

A hybrid high-aspect-ratio trench standard template

硅基MEMS器件中存在大量高深宽比结构,对这些结构进行线宽和深度的无损检测,是当前的热点问题。为了实现对这些高深宽比结构无损测量系统的准确校准,采用半导体工艺研制了一系列高深宽比沟槽标准样板,宽度范围2~30μm、深度范围10~300μm,其深宽比最大达到30∶1。为了满足样板的校准功能,设计了多种特征结构,包括辅助定值结构、测量定位结构和定位角结构等,还设计了样板量值的表征与考核方法。考核量值包括线宽尺寸、沟槽深度尺寸和均匀性。使用扫描电镜对标准样板进行了测试,结果表明该标准样板可以用于校准近红外宽光谱干涉显微测量系统。

Objective There are a large number of high-aspect-ratio structures in silicon-based MEMS devices,and nondestructive testing of linewidth and depth of these structures is a hot issue at present.Generally,the depth-towidth ratio of MEMS high-aspect-ratio structures is generally between 10∶1 and 100∶1,and the trench width is a few microns to tens of microns.At present,in the silicon-based MEMS process line,anatomical testing is the main means of high-aspect-ratio structure testing,but there are the following defects:it is necessary to use scanning electron microscopy(SEM)for auxiliary measurement,which is inefficient and cumbersome;It is a destructive measurement that causes irreversible damage to MEMS products;It can only be sampled and cannot fully reflect the characteristics of the process.Based on this,a non-destructive measurement system with highaspect-ratio structure near-infrared broad-spectrum microscopy measurement system was developed,and its measurement accuracy will directly affect the overall performance of the device under test,so it is necessary and urgent to calibrate the measurement system.Methods In order to achieve the accurate calibration of the non-destructive measurement system of high-aspectratio structure,a series of standard samples of high-aspect-ratio trenches are designed and developed by semiconductor process,with a width range of 2-30μm,a depth range of 10-100μm,and a maximum high-aspectratio of 30∶1(Tab.1).The samples were characterized and fixed,and finally the developed standard samples were applied to the calibration of the near-infrared broad-spectrum microscopy measurement system(Fig.13).Results and Discussions In order to meet the calibration function of the standard samples,a variety of characteristic structures are designed(Fig.1),including auxiliary fixed value structure,measurement positioning structure and positioning angle structure,etc.,and the characterization and assessment method of the sample value are designed(Fig.5-6).Measurement values include line width size,trench depth size,and uniformity.Finally,the developed standard template is applied to the near-infrared broad-spectrum microscopy measurement system to further verify the accuracy of the developed system,that is,the applicability of the template(Tab.2).Conclusions In order to solve the calibration problem of the near-infrared broad-spectrum interferometric microscopy system,a series of standard samples of high-aspect-ratio grooves were developed,with a width range of 2-30μm and a depth range of 10-300μm,and its high-aspect-ratio reached a maximum of 30∶1.In order to meet the calibration function of the template,a variety of characteristic structures are designed,including auxiliary fixed value structure,measurement positioning structure and positioning angle structure,etc.,and the characterization and assessment method of the sample measurement value is designed.Since there is no suitable measuring instrument to directly characterize the value of the standard template of the composite high-aspect-ratio trench,an auxiliary fixed value structure is designed for the standard template,and the cross-section of the highaspect-ratio trench structure is displayed by sectioning,and then it is measured by scanning electron microscope or atomic force microscope,and the uniformity of the template is characterized to ensure the consistency of the measurement results of the template.Finally,the developed standard template was measured by the near-infrared broad-spectrum interferometric micrometry system,and the measurement results showed that the magnitude was basically consistent with the characterization results.