CN102082108B - Method and device for rapidly measuring sidewall appearance of micro-nano deep groove structure - Google Patents

Abstract

The invention discloses a method and device for rapidly measuring sidewall appearance of a micro-nano deep groove structure, which can simultaneously and rapidly measure the parameters of the sidewall appearance of the micro-nano deep groove structure, such as line width, groove depth, sidewall angle, sidewall roughness and the like. The method comprises the steps of: projecting elliptical polarized lights, which is obtained by polarizing light beams with the wavelengths ranging from near infrared waveband to middle infrared waveband, onto the surface of a structure to be measured; collecting zero-level diffraction signals on the surface of the structure to be measured, and calculating to obtain a measured infrared spectroscopic ellipsometry of the micro-nano deep groove structure; calculating theoretical spectroscopic ellipsometries in the near infrared waveband and the middle infrared waveband respectively by using a wavelength allocation modeling method, matching the theoretical spectroscopic ellipsometries with the infrared spectroscopic ellipsometry measured in the experiment by using a stepwise spectral inversion method, and sequentially extracting the groove structure parameter and the roughness parameter. The device comprises an infrared light source, first, second, third and fourth off-axis parabolic mirrors, a Michelson's interferometer, a planar reflector, a polarizer, a sample bench, an analyzer, a detector and a computer; and the method is a noncontact, nondestructive low-cost method for rapidly measuring the sidewall appearance.

Description

A kind of quick method of measurement of micro-nano deep groove structure sidewall pattern and device

Technical field

The invention belongs to integrated circuit (IC) and MEMS (MEMS) device measuring technique; Be specifically related to quick method of measurement of micro-nano deep groove structure etching process and device, this method is particularly useful for deep groove structure course of processing trenched side-wall topography measurement in 3D through-hole interconnection (TSV) and the dynamic random access memory (DRAM).

Background technology

In microelectronics and power semiconductor design and process for making, extensively adopted intensive three-dimensional structure array at present.For example in 3D through-hole interconnection (TSV) preparation and advanced person's dynamic random access memory (DRAM) capacitor design, all adopted the deep groove structure of high-aspect-ratio.Along with the continuous development of semiconductor technology " scaled " trend, various deep groove structure characteristic sizes constantly descend in the integrated circuit.In the process that characteristic size descends, original negligible sidewall roughness sidewall pattern parameters such as (SWR) to the influence of components and parts electric property with increasing.In general, trenched side-wall pattern parameter mainly comprises geometrical characteristic parameter (like parameters such as trench features width, gash depth and trenched side-wall angles) and trenched side-wall roughness parameter.For realizing effective technology controlling and process, it is significant in manufacture process, deep groove structure sidewall pattern to be carried out quick, nondestructive accurate detection.

In numerous nondestructive method of measurement; Measuring method is particularly suitable for this application demand; Reflective spectral measure method for example; Scattering spectrometries etc., these methods have been widely used in optical film thickness and composition measurement, in partial monopoly and document, have applied it in the measurement of linear grating groove structure.Proposed " a kind of micro-nano deep groove structure method of measurement and device " (publication number is CN101131317A the applicant; Be 2008-02-27 in open day) and " a kind of micro-nano deep groove structure On-line Measuring Method and device " (publication number is CN101393015A; Open day is 2009-03-25); This inventive method projects the silicon chip surface that contains deep groove structure with infrared beam, analyzes the interference light that forms from each surface reflections of deep groove structure and obtains measuring Infrared Reflective Spectra; Adopt EFFECTIVE MEDIUM THEORY to make up the theoretical Infrared Reflective Spectra of this deep groove structure equivalence plural layers storehouse optical model; Utilize simulated annealing, artificial neural net, realize the spectrum back analysis based on optimized Algorithm such as gradients; And then geometrical characteristic parameters such as the degree of depth of extraction groove and width, realize the accurate measurement of high-aspect-ratio deep trench width and degree of depth equidimension.This method can be measured gash depth, width and film thickness simultaneously.Implement device that this inventive method provides adopts the mid-infrared light bundle to treat geodesic structure and surveys, and through accurately measuring groove structure surface Infrared Reflective Spectra, and then the spectrum back analysis extracts and obtains groove structure geometrical characteristic parameter value.

In above patent documentation, mention method of measurement, mainly use measurement with geometrical characteristic parameters such as deep trench characteristic width, the degree of depth based on deep groove structure surface Infrared Reflective Spectra.Yet,, in the approximate modeling of EFFECTIVE MEDIUM, ignored the influence of trenched side-wall roughness parameter, thereby can't realize the measurement of deep groove structure complete side walls pattern because middle Infrared Reflective Spectra is insensitive to the trickle morphology change of groove.At the implement device that this method proposes, need measure a reflectance spectrum with reference to reflecting surface in advance.Owing to, can bring than mistake to measurement result with reference to the difference of reflecting surface reflective spectral measure condition and tested sample reflective spectral measure condition.

Summary of the invention

The object of the present invention is to provide the quick method of measurement of a kind of micro-nano deep groove structure sidewall pattern parameter; This method can carry out accurately detecting fast to the complete trenched side-wall pattern parameter that comprises geometrical characteristic parameter such as gash depth, width and trenched side-wall roughness parameter; Have untouchable; Non-destructive, high speed and high-precision characteristics, the present invention also provides the device of realizing this method.

Micro-nano deep groove structure sidewall pattern measurement method of parameters disclosed by the invention, its step comprises:

The 1st step after the polarizer rises partially, projected the article surface to be measured that comprises deep groove structure with infrared beam, and infrared beam is positioned at near-infrared to middle-infrared band scope, and wavelength is 0.8～20um;

The 2nd steps into irradiating light beam after each surface reflection of deep groove structure, through the analyzer analyzing, adopts Infrared Detectors to receive reflected signal, obtains interference signal;

The 3rd step received the interference signal that obtains to Infrared Detectors and carries out Fourier transform, obtained the infrared ellipse polarisation spectrum of deep groove structure;

The 4th step adopted and divides the wavelength modeling method, calculated deep groove structure respectively near infrared band and the ellipse polarisation spectrum of middle-infrared band, comprised amplitude ratio and phase difference;

The 5th step adopted substep spectrum inversion method to extract deep groove structure parameter and roughness parameter successively based on above minute wavelength modeling method.

The device of the quick method of measurement of realization provided by the present invention said micro-nano deep groove structure sidewall pattern is characterized in that: this device comprises infrared light supply, first to fourth off-axis paraboloidal mirror, Michelson's interferometer, plane mirror, the polarizer, sample stage, analyzer, detector and computer; Infrared light supply, first off-axis paraboloidal mirror, Michelson's interferometer and plane mirror are positioned on the same light path successively, plane mirror and and the emitting light path of Michelson's interferometer between angle be 45 °; The polarizer and second off-axis paraboloidal mirror are positioned on the plane mirror reflected light path successively, and sample stage is positioned on the second off-axis paraboloidal mirror reflected light path; The relative sample stage surface normal of the emergent light axis of the incident light axis of the 3rd off-axis paraboloidal mirror and second off-axis paraboloidal mirror symmetric arrangement, the 3rd off-axis paraboloidal mirror receive second off-axis paraboloidal mirror folded light beam folded light beam once more on testing sample; Analyzer and the 4th off-axis paraboloidal mirror are positioned on the emitting light path of the 3rd off-axis paraboloidal mirror successively, and detector is positioned on the focal plane of the 4th off-axis paraboloidal mirror emitting light path, and computer links to each other with detector successively.

Compare with current measuring methods, method provided by the present invention can realize online, quick, the high-precision measurement of micro-nano deep groove structure, will have wide practical use in Measurement of Semiconductors and technology controlling and process field.Particularly, the present invention can obtain following effect in the micro-nano deep groove structure measurement in devices such as TSV, DRAM:

(1) the complete side walls pattern Parameter Measuring of various typical deep groove structures among realization TSV, the DRAM;

(2) realize among TSV, the DRAM etching process defects detection in the various typical deep groove structures, judge fast that etching is blocked (chocking), mask is crossed erosion typical etching defects such as (mask erosion).

Description of drawings

Fig. 1 is that deep groove structure sidewall pattern parameter is divided wavelength modeling sketch map;

Fig. 2 is that deep groove structure sidewall pattern parameter is extracted flow chart step by step;

Fig. 3 is the present invention's one case study on implementation plant system drawing.

Embodiment

Measuring process with the skew wall deep groove structure is an example below, in conjunction with accompanying drawing the principle and the course of work of the inventive method is done further explain.

The performing step of the inventive method comprises:

(1) with infrared beam after the polarizer rises partially, project the article surface to be measured that comprises deep groove structure, infrared beam is positioned at near-infrared to middle-infrared band scope, wavelength is 0.8～20um;

(2) incident beam through the analyzer analyzing, adopts Infrared Detectors to receive reflected signal after each surface reflection of groove structure, obtains interference signal;

(3) interference signal that infrared detector measurement is obtained carries out Fourier transform, obtains the infrared ellipse polarisation spectrum of deep groove structure;

(4) adopt branch wavelength modeling method, calculate deep groove structure respectively near infrared band and the ellipse polarisation spectrum of middle-infrared band (comprising amplitude ratio and phase difference);

As shown in Figure 1, be divided into two types according to the characteristics of groove structure sidewall pattern parameter: sidewall roughness parameter and geometrical characteristic parameter.

In middle-infrared band, the ellipse polarisation spectrum of groove structure only changes sensitive to the groove structure geometrical characteristic parameter.Therefore, can groove structure sidewall pattern parameter predigesting only be considered groove live width D, pitch P, depth H, side wall angle SWA geometrical characteristic parameter.According to simplifying the deep groove structure characteristics, adopt modeling method based on EFFECTIVE MEDIUM THEORY, will simplify the deep groove structure equivalence and be plural layers storehouse model, and adopt EFFECTIVE MEDIUM approximate formula (1) to calculate each equivalent layer effective dielectric constant ε _Eff:

$\frac{{\mathrm{\ϵ}}_{\mathrm{eff}}-{\mathrm{\ϵ}}_h}{{\mathrm{\ϵ}}_{\mathrm{eff}}+2{\mathrm{\ϵ}}_h}=\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{f}_j\frac{{\mathrm{\ϵ}}_{\mathrm{eff}}-{\mathrm{\ϵ}}_h}{{\mathrm{\ϵ}}_j-2{\mathrm{\ϵ}}_h}$ $\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{f}_j=1---\left(1\right)$

Wherein, ε _hBe the electric medium constant of the pairing groove structure layer of this equivalent layer main material, f _jBe the shared percent by volume of other media of j kind in the pairing groove structure layer of this equivalent layer, ε _jBe the electric medium constant of other media of j kind in the pairing groove structure layer of this equivalent layer, j is the pairing sequence number of other medium kinds in the groove structure layer.N is a groove structure layer medium species number, and the j value is 1 to N.Based on the modeling method of EFFECTIVE MEDIUM approximation theory referring to disclosed method among the CN 101131317A.

In near infrared band, suppose that deep groove structure geometrical characteristic parameter value is known, the sidewall roughness unknown parameters.Because the infrared ellipse polarisation spectrum characteristic sensitive near infrared band to the deep trench sidewall roughness; Adopt the theoretical modeling method of rigorous coupled wave; With geometrical structure parameters such as trenched side-wall roughness parameter, groove live width, gash depth, side wall angles is input, calculates the ellipse polarisation spectrum of this deep groove structure near infrared band:

1. with the trenched side-wall pattern abstract be one-period property SIN function, the SIN function amplitude is w for the A frequency.

2. with the groove structure layering, utilization rigorous coupled wave modeling method calculates corresponding Jones (Jones) matrix $J=\left[\begin{array}{cc}{J}_{11}& J_{12}\\ J_{21}& J_{22}\end{array}\right].$

3. through Jones matrix element J ₁₁And J ₂₂Calculate the theoretical ellipse polarisation spectrum of groove structure near infrared band, wherein, amplitude ratio $\mathrm{Tan}\mathrm{\ψ}=\frac{\left|J_{11}\right|}{\left|J_{22}\right|},$ Phase difference $\mathrm{\Δ}=\mathrm{Arg}\left(\frac{J_{11}}{J_{22}}\right).$

Adopting plural layers optical propagation matrix method to calculate equivalent plural layers storehouse model composes at the ellipse polarisation in middle-infrared band:

1. at first calculate plural layers storehouse model optical propagation matrix:

$\left(\begin{array}{cc}{M}_{11}& M_{12}\\ M_{21}& M_{22}\end{array}\right)=D_0^{-1}\left[\underset{l=1}{\overset{N}{\mathrm{\Π}}}{D}_l{P}_l{D}_l^{-1}\right]D_s---\left(2\right)$

Wherein, D wherein ₀Be the optical signature matrix of environment, D _sBe the optical signature matrix of substrate, D _lBe the refractive index of film stack l layer and the matrix function at refraction angle, P _lIt is the matrix function at l layer phase change angle.For TE polarization direction l layer $D_l=\left(\begin{array}{cc}1& 1\\ n_l\mathrm{Cos}{\mathrm{\θ}}_l& -n_l\mathrm{Cos}{\mathrm{\θ}}_l\end{array}\right),$ For TM polarization direction l layer $D_l=\left(\begin{array}{cc}\mathrm{Cos}{\mathrm{\θ}}_l& \mathrm{Cos}{\mathrm{\θ}}_l\\ n_l& -n_l\end{array}\right).$

2. use plural layers optical propagation matrix and calculate TE and TM polarization direction reflectivity factor r respectively:

$r_{\mathrm{TE}\left(\mathrm{TM}\right)}=\frac{M_{21}}{M_{11}}---\left(3\right)$

3. simplify the theoretical ellipse polarisation spectrum of groove structure by TE and TM polarization direction emissivity coefficient calculations, obtain amplitude ratio $\mathrm{Tan}\mathrm{\ψ}=\frac{\left|r_{\mathrm{TE}}\right|}{\left|r_{\mathrm{TM}}\right|},$ Phase difference $\mathrm{\Δ}=\mathrm{Arg}\left(\frac{r_{\mathrm{TE}}}{r_{\mathrm{TM}}}\right).$

(5), adopt substep spectrum inversion method to extract groove structure parameter and roughness parameter successively based on above minute wavelength modeling method;

As shown in Figure 2, the infrared ellipse polarisation spectrum that at first will measure by wavelength be decomposed into the ellipse polarisation spectrum of near-infrared with in infrared ellipse polarisation spectrum.

In middle-infrared band; Adopt the corresponding theoretical infrared ellipse polarisation spectrum of aforementioned EFFECTIVE MEDIUM THEORY modeling method computational short cut groove structure; Through spectral matching, extract the groove structure geometrical characteristic parameter again, comprise parameters such as groove live width, gash depth, side wall angle.Here, spectral matching can be referring to disclosed method among the CN101393015A.

In the near infrared band scope, adopt the rigorous coupled wave modeling method, calculate the theoretical infrared ellipse polarisation spectrum of corresponding deep groove structure; Groove structure roughness parameter model is input; It is given value that the ellipse polarisation spectrum of aforementioned middle-infrared band is extracted the geometrical characteristic parameter that obtains; Adopt spectral matching then; Extract and describe groove structure SIN function amplitude A and frequency w value, adopt formula shown in Figure 1 to calculate the sidewall roughness parameter value again.,, therefore, can adopt Local Optimization Algorithm here,, seek out the trenched side-wall roughness parameter fast like steepest gradient descent method because parameter to be asked has only the sidewall roughness parameter.

As shown in Figure 3, apparatus of the present invention comprise infrared light supply 31, the first off-axis paraboloidal mirrors 32, Michelson's interferometer 33, plane mirror 34; The polarizer 35, the second off-axis paraboloidal mirrors 36, sample stage 37, the three off-axis paraboloidal mirrors 39; Analyzer 40, the four off-axis paraboloidal mirrors 41, detector 42, computer 43.

Infrared light supply 31, the first off-axis paraboloidal mirrors 32, Michelson's interferometer 33, plane mirror 34 are positioned on the same light path successively, plane mirror 34 and and the emitting light path of Michelson's interferometer 33 between angle be 45 °.The polarizer 35 and second off-axis paraboloidal mirror 36 are positioned on plane mirror 34 reflected light paths successively, and sample stage 37 is positioned on second off-axis paraboloidal mirror, 36 reflected light paths.The relative sample stage 37 surface normal symmetric arrangement of the emergent light axis of the incident light axis of the 3rd off-axis paraboloidal mirror 39 and second off-axis paraboloidal mirror 36, the 3rd off-axis paraboloidal mirror 39 receive second off-axis paraboloidal mirror, 36 folded light beams folded light beam once more on testing sample 38.Analyzer 40 and the 4th off-axis paraboloidal mirror 41 are positioned on the emitting light path of the 3rd off-axis paraboloidal mirror 39 successively, and detector 42 is positioned on the focal plane of the 4th off-axis paraboloidal mirror 41 emitting light paths.Computer 43 links to each other with detector 42 successively.

The light beam that infrared light supply 31 sends obtains collimated light beam through 32 reflections of first off-axis paraboloidal mirror, and collimated light beam gets into the polarizer 33 and obtains parallel elliptical polarization light beam.The elliptical polarization light beam is after Michelson's interferometer 34 modulation; Converge by second off-axis paraboloidal mirror 36; Project tested sample 38 surfaces with 45 °; Folded light beam is through off-axis paraboloidal mirror 39 reflections, and the parallel analyzer 40 of injecting detects and obtains the ellipse polarization state of light of wilfully shaking after the tested sample surface reflection.Get in the Infrared Detectors 42 by the 4th off-axis paraboloidal mirror 41 reflection backs from the collimated light beam of analyzer 40 outgoing.Infrared Detectors 6 comprises functions such as signals collecting, amplification, filtering, digital-to-analogue conversion.The interference signal that Infrared Detectors collects is sent into computer 43 after pre-process.

The present invention not only is confined to above-mentioned embodiment; Persons skilled in the art are according to content disclosed by the invention; Can adopt other multiple embodiment embodiment of the present invention, therefore, every employing project organization of the present invention and thinking; Do some simple designs that change or change, all fall into the scope of the present invention's protection.

Claims (2)

1. micro-nano deep groove structure sidewall topography measurement method, its step comprises:

The 1st step after the polarizer rises partially, projected the article surface to be measured that comprises deep groove structure with infrared beam, and infrared beam is positioned at near-infrared to middle-infrared band scope, and wavelength is 0.8～20um;

The 2nd steps into irradiating light beam after each surface reflection of deep groove structure, through the analyzer analyzing, adopts Infrared Detectors to receive reflected signal, obtains interference signal;

The 3rd step received the interference signal that obtains to Infrared Detectors and carries out Fourier transform, obtained the infrared ellipse polarisation spectrum of deep groove structure;

The 4th step adopted and divides the wavelength modeling method, calculated deep groove structure respectively near infrared band and the ellipse polarisation spectrum of middle-infrared band, comprised amplitude ratio and phase difference;

The 5th step adopted substep spectrum inversion method to extract deep groove structure parameter and roughness parameter successively based on above minute wavelength modeling method.

2. realize the device of the described a kind of micro-nano deep groove structure sidewall topography measurement method of claim 1, it is characterized in that: this device comprises infrared light supply (31), first to fourth off-axis paraboloidal mirror (32,36,39,41), Michelson's interferometer (33), plane mirror (34), the polarizer (35), sample stage (37), analyzer (40), detector (42) and computer (43);

Infrared light supply (31), first off-axis paraboloidal mirror (32), Michelson's interferometer (33) and plane mirror (34) are positioned on the same light path successively, plane mirror (34) and and the emitting light path of Michelson's interferometer (33) between angle be 45 °; The polarizer (35) and second off-axis paraboloidal mirror (36) are positioned on plane mirror (34) reflected light path successively, and sample stage (37) is positioned on second off-axis paraboloidal mirror (36) reflected light path; The relative sample stage of emergent light axis (37) the surface normal symmetric arrangement of the incident light axis of the 3rd off-axis paraboloidal mirror (39) and second off-axis paraboloidal mirror (36), the 3rd off-axis paraboloidal mirror (39) receive second off-axis paraboloidal mirror (36) folded light beam folded light beam once more on testing sample (38); Analyzer (40) and the 4th off-axis paraboloidal mirror (41) are positioned on the emitting light path of the 3rd off-axis paraboloidal mirror (39) successively, and detector (42) is positioned on the focal plane of the 4th off-axis paraboloidal mirror (41) emitting light path, and computer (43) links to each other with detector (42) successively.

Images