阅读说明：本技术 一种基于相位测量偏折的晶圆翘曲度非接触式测量装置 (A kind of silicon wafer warpage degree non-contact measurement apparatus based on phase measurement deviation ) 是由 邹典 沈芳沅 王春涛 梁沛钊 阮旸 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种基于相位测量偏折的晶圆翘曲度非接触式测量装置,运用于测量技术领域。所述的测量装置包括：微投影仪、显微物镜、透镜组、CCD相机、晶圆承载平台和计算机,所述CCD相机包含带有光圈的镜头；所述晶圆承载平台可限制被测晶圆水平面内的移动,并保证晶圆处于无夹持状态。本发明在光路中加入显微物镜用于缩小微投影仪投射的图像,提高了测量精度；同时,加入透镜组用于放大被测晶圆反射图像,满足CCD相机分辨率并便于图像处理。本发明晶圆翘曲度提供了一种高精度、低成本实际可行的测量方法。(The invention discloses a kind of silicon wafer warpage degree non-contact measurement apparatus based on phase measurement deviation, applies to field of measuring technique.The measuring device includes: micro-projector, microcobjective, lens group, CCD camera, wafer carrying platform and computer, and the CCD camera includes the camera lens with aperture；The wafer carrying platform can limit the movement in tested wafer horizontal plane, and guarantee wafer in no clamp position.Microcobjective is added for reducing the image of micro-projector projection in the present invention in the optical path, improves measurement accuracy；Meanwhile lens group is added for amplifying tested wafer reflected image, meet CCD camera resolution ratio and convenient for image procossing.Silicon wafer warpage degree of the present invention provides a kind of high-precision, the practicable measurement method of low cost.)

1. a kind of silicon wafer warpage degree non-contact measurement apparatus based on phase measurement deviation, specifically includes that micro-projector, lens Group, microcobjective, CCD camera, wafer carrying platform and computer, comprising the following steps:

Step 1, micro-projector generate the sinusoidal gray scale striped of light intensity coding, and the sine gray scale striped is after microcobjective reduces Deviation is reflected and occurred by tested crystal column surface, is deformed striped, the deforming stripe is after lens group is amplified by CCD camera It receives, the surface face shape information of tested wafer is comprised in the phase of deforming stripe.

Step 2 is obtained the absolute phase of deforming stripe using phase-shifting method and phase unwrapping, and obtains tested crystalline substance corresponding with phase The actual facula coordinate in the corresponding micro-projector of point on circular surfaces.

Step 3 establishes optical ray trace model in a computer, obtains ideal crystal column surface and corresponds to ideal hot spot in micro-projector Coordinate.

Step 4, by analyzing all actual facula coordinates and the ideal offset as hot spot coordinate, tested crystal column surface can be found out Each point gradient integrates all gradient values, the height distribution of tested crystal column surface is obtained, to calculate angularity.

2. a kind of silicon wafer warpage degree non-contact measurement apparatus based on phase measurement deviation according to claim 1, It is characterized by phase-shifting method, the sinusoidal gray scale striped of micro-projector projection is encoded, is deviated using phase change Amount, improves measurement accuracy；Tested crystal column surface is projected after reducing by the striped that microcobjective generates micro-projector, is reduced The limitation of micro-projector pixel, improves measurement accuracy；Amplified by the deforming stripe that lens group reflects tested crystal column surface, is met The receivable resolution ratio of CCD camera.

3. a kind of silicon wafer warpage degree non-contact measurement apparatus based on phase measurement deviation according to claim 1, Be characterized in that: the CCD camera is equipped with the camera lens with aperture, guarantees that only tested region reflection light is by CCD camera It receives, avoids ambient interference.

4. a kind of silicon wafer warpage degree non-contact measurement apparatus based on phase measurement deviation according to claim 1, Be characterized in that: the wafer carrying platform has the adjustable wafer framing mask of center of circle fixed size, can limit tested wafer water Movement in plane, while guaranteeing tested wafer in no clamp position.

5. a kind of silicon wafer warpage degree non-contact measurement apparatus based on phase measurement deviation according to claim 1, It is characterized by computer to encode the throw light of micro-projector, generates six figures, each three of the direction XY, every three Opening with 0,2 π/3,4 π/3 is initial phase, and the deforming stripe that CCD is collected can be expressed from the next:

Wherein,For received light distribution on CCD camera pixel,For modulation degree distribution.It is moved by three steps The initial phase mutually provided can solve the phase distribution in tested wafer face.

Technical field

The present invention relates to a kind of silicon wafer warpage degree non-contact measurement apparatus based on phase measurement deviation.

Background technique

With the high speed development of electronic information technology, electronic product is brought by its function abundant to people's daily life Great convenience.Meanwhile people are also higher and higher for the performance requirement of electronic product, this original to semiconductor integrated circuit More stringent requirements are proposed for the quality of material --- wafer.The light that the angularity size of wafer will directly affect in subsequent production The yields of the techniques such as quarter, wafer bonding.Currently, the measurement method for silicon wafer warpage degree is generally divided into electron microscopy, optics is done Relate to method and mechanical probes method.

For electron microscopy using atomic force microscope as representative, principle is that quilt is presented using the van der Waals interaction between atom The surface characteristics of sample.This method measurement accuracy is high, but device is at high price, has very high requirement for measurement environment. Through Optical Interference Spectra combines optics and electronics, that there are measurement dynamic ranges is small, versatility is poor, while device involves great expense The defects of.For mechanical probes method by way of point-to-point measurement, data fitting, measurement efficiency is low, and may scratch tested wafer Surface.

Therefore, the defect of the above method how is made up, while meeting the requirement of high-precision, low cost, improves measurement efficiency, Expand measurement dynamic range, reducing requirement of the measurement to environment is those skilled in the art's problem to be solved.

Summary of the invention

In view of the above-mentioned problems, the invention proposes a kind of silicon wafer warpage degree non-contact measurement based on phase measurement deviation Device.Its primary structure includes micro-projector, microcobjective, lens group, CCD camera, wafer carrying platform and computer.Comparison Above-mentioned three kinds of measurement methods, the present apparatus are not limited while guaranteeing high-acruracy survey by tested wafer caliber size, measurement Dynamic range is big, and insensitive to environmental disturbances such as vibrations, with optical measuring technique, belongs to non-destructive testing classification.Simultaneously Apparatus of the present invention structure is simple, builds and operates conveniently, measurement cost is greatly saved.

The present invention measures silicon wafer warpage degree with phase measurement deviation technology.

Firstly, carrying out light intensity coding by throw light of the computer to micro-projector；Incident ray passes through microcobjective Crystal column surface is incident upon after diminution；Reflection light carries the face shape information of crystal column surface since deviation occurs for crystal column surface warpage； Reflection light is completely covered on each pixel of CCD camera by lens group；By computer to the modified strip got Line carries out phase extraction and phase unwrapping, acquires each point gradient of crystal column surface, obtains tested crystal column surface height by integral Distribution, then obtains angularity.Specific step is as follows:

(1) light that computer projects micro-projector encodes

X-direction is generated with phase-shifting method, Y-direction each three sinusoidal gray scale bar graphs, first phase is 0,2, 4And root Striped quantity and size are selected according to micro-projector pixel size.

(2) microcobjective reduces the strip encoding of micro-projector

Microcobjective is set in optical path between micro-projector and tested wafer, will be projected after the image down of micro-projector generation In tested crystal column surface.

(3) lens group amplifies deforming stripe image

The deforming stripe amplification that tested crystal column surface is reflected, and be completely covered on each pixel of CCD camera.

(4) CCD camera receives deforming stripe

CCD camera receives the deforming stripe after lens aperture filters, and avoids the interference of ambient.

(5) optical ray trace model is built

Optical ray trace model is built in a computer using ZEMAX, is obtained ideal crystal column surface and is corresponded to ideal in micro-projector Hot spot coordinate.

(6) deforming stripe image procossing

With phase extraction and expansion technique, the phase information of tested wafer face shape for including in deforming stripe figure is obtained, and obtain Obtain the actual facula coordinate put in corresponding micro-projector on tested crystal column surface corresponding with phase.Analyze all actual faculas Coordinate and ideal find out tested crystal column surface each point gradient, integrate, obtain to all gradient values as the offset of hot spot coordinate Height to tested crystal column surface is distributed, to calculate angularity.

The present invention uses non-contact measurement, ensure that crystal column surface is injury-free；It is flat using the wafer carrying of no clamping Platform meets the standard of angularity measurement；While reaching the measurement of high-precision angularity, cost is lower, and noise resisting ability is more By force.

Detailed description of the invention

Fig. 1 is optical path schematic diagram of the invention；

Fig. 2 is the embodiment of the present invention measurement procedure schematic diagram；

Fig. 3 is the sine streak figure of the light intensity coding of micro-projector；

Fig. 4 is the tested wafer three dimensional warped figure measured.

Specific embodiment

The embodiment of the present invention is described in detail with reference to the accompanying drawing.

A kind of silicon wafer warpage degree non-contact measurement apparatus based on phase measurement deviation, optical path is as shown in Figure 1, main Will be by a computer 1, a micro-projector 2, microcobjective 3 is tested wafer 4, wafer carrying platform 5, a lens group 6, One CCD camera 7 forms.Wherein, micro-projector 2 and CCD camera 7 are connected with computer 1 respectively.

With reference to Fig. 2, which is the embodiment of the present invention measurement procedure schematic diagram, which includes:

Step 1, micro-projector is opened, projects X, two direction the Y sinusoidal gray scale striped that totally 6 width light intensity encode to tested crystal column surface Figure；

Step 2, deforming stripe phase is extracted according to the received deforming stripe figure through tested crystal column surface reflection of CCD camera, and By phase unwrapping, obtains the tested practical face shape of wafer and correspond to actual facula coordinate on micro-projector；

Step 3, optical ray trace model is built in a computer using ZEMAX, obtain ideal crystal column surface and correspond on micro-projector Ideal hot spot coordinate；

Step 4, comparison actual facula and ideal hot spot coordinate, obtain the gradient distribution of tested crystal column surface；

Step 5, gradient distribution is integrated, obtains tested wafer face shape altitude information, and the three-dimensional for obtaining tested wafer is stuck up Diagram.

The measurement of specific implementation silicon wafer warpage degree is described in detail below, wherein specifically with a diameter for 1 inch Pattern-free wafer be measurand for, carry out the measurement of angularity.Fig. 3 is that micro-projector is projected to tested crystal column surface Sinusoidal gray scale striped, Fig. 4 are the three dimensional warped figures of tested wafer, are included the following steps:

(1) tested wafer and device initialization are loaded

Tested wafer is placed in the wafer framing mask on wafer carrying platform, adjustment wafer framing mask diameter to tested crystalline substance Circle is identical, guarantees that wafer is irremovable in the horizontal plane.

(2) deforming stripe is acquired

Computer controls the sinusoidal gray scale striped of micro-projector projection light intensity coding, and the striped is thrown after microcobjective reduces It penetrates and is being tested crystal column surface and is reflecting, be deformed striped；The deforming stripe is again successively by lens group amplification, camera After lens aperture filters, acquired by CCD camera.

(3) phase distribution is obtained

The light distribution of three groups of deforming stripes is obtained according to three step phase-shifting methods.The phase of tested crystal column surface is solved according to the following formula Distribution:

By required X, Y-direction phase distribution obtains the actual facula coordinate on corresponding micro-projector.It is being calculated by ZEMAX Optical ray trace model is established in machine and obtains ideal hot spot distribution, is calculated the difference of actual facula and ideal hot spot, is obtained offset.

(4) gradient distribution and the reconstruct of face shape are solved

The X of the point on tested crystal column surface is solved according to offset, the gradient distribution of Y-direction is acquired using integral reconstructors method The height distribution of tested crystal column surface, to obtain tested silicon wafer warpage degree.

Above said content is the preferred embodiment of the present invention, it is noted that for the ordinary skill of the art For personnel, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications It is considered as protection scope of the present invention.