KR20040063402A - Apparatus for inspecting a wafer - Google Patents

Abstract

PURPOSE: An apparatus for inspecting a wafer is provided to eliminate the necessity of additionally loading a bare wafer and performing a test process by installing a reference block in a wafer inspecting apparatus such that the reference block can mount a reference sample. CONSTITUTION: A chuck(110) supports a wafer(W) with a layer, capable of transferring. A reference block(120) supports the reference sample(10), provided in a side of the chuck. A light source(130) irradiates the first light. A detecting unit(140) detects the second light and the third light, respectively. The second light is irradiated from the light source and transmits the wafer. The third light transmits the reference sample. A Fourier transformer(150) obtains the first and second spectrums from the second and third light detected by the detecting unit. A data processing unit(160) makes the first spectrum corrected by the second spectrum to calculate a spectrum with respect to the layer.

Description

Apparatus for inspecting a wafer}

The present invention relates to a wafer inspection apparatus. More specifically, the present invention relates to a wafer inspection apparatus for measuring an impurity concentration of a film formed on a wafer using an infrared laser.

In general, a semiconductor device includes a Fab process for forming an electrical circuit on a silicon wafer used as a semiconductor substrate, a process for inspecting electrical characteristics of the semiconductor devices formed in the fab process, and the semiconductor devices are epoxy It is manufactured through a package assembly process for encapsulating and individualizing with resin.

The fab process includes a deposition process for forming a film on a wafer, a chemical mechanical polishing process for planarizing the film, a photolithography process for forming a photoresist pattern on the film, and the photoresist pattern using the photoresist pattern. An etching process for forming the film into a pattern having electrical characteristics, an ion implantation process for implanting specific ions into a predetermined region of the wafer, a cleaning process for removing impurities on the wafer, and a process for forming the film or pattern An inspection process for inspecting the surface or the composition and concentration of the film, and the like.

In recent years, as the degree of integration of semiconductor devices increases, electrical elements formed on a wafer are arranged in multiple layers, and the critical dimension (CD) of patterns for forming the electrical elements is reduced, and the aspect ratio tends to increase. There is this. Accordingly, electrical isolation between patterns has emerged as a more important technical factor. Insulating layers for insulating the patterns include fluorosilicate glass (FSG), boro-silicate glass (SGS), and boro-phospho-silicate glass (BPSG). An oxide film such as this is used.

The BPSG film is known as a good flow film with a sudden change in viscosity with respect to heat having a temperature of about 850 ℃. At this time, the impurity concentration of the BPSG film determines the degree of planarization and the degree of insulation at the process temperature. For example, in order to lower the process temperature, the concentration of impurities such as boron (B) and phosphorus (P) may be adjusted in the silicon oxide film (SiO ₂ ), which is a main component of the BPSG film. Therefore, the impurity concentration of the insulating film must be appropriately adjusted, and an inspection process for this must be essentially performed.

As a method for inspecting the impurity concentration of the insulating film, a Fourier transform infrared (FTIR) measuring method using an infrared laser is mainly used. The FTIR measurement method uses a measurement facility called an FTIR spectrometer, and represents the absorption distribution of the material in the spectral spectrum. When radiation passes through a solid, liquid, or gaseous layer, electrons that make up atoms, molecules, or ions absorb radiation and are transferred to an energy level as high as the photon energy of the radiation. These electron energy potential differences have inherent values for each chemical species, and the component materials in the sample can be known by investigating the frequency of the absorbed radiation. The frequency is represented by the propagation speed v of the wave and the wavelength [lambda], and the spectral spectrum is represented by the wave number, which is the inverse of the wavelength.

In order to measure the concentration of each material included in the sample, the peak area of the wave range indicated by each material in the spectral spectrum is used. That is, the concentration of each substance contained in a sample is grasped by the relative magnitude | size of the peak area which each substance in a sample shows.

In the FTIR inspection process for measuring the impurity concentration of an oxide film such as a BPSG film formed on a wafer, the measured spectral spectrum includes not only a component for the oxide film but also a component for the wafer and the patterns formed on the wafer, It also contains components for the air inside the inspection apparatus. Accordingly, a method of compensating the measured spectral spectrum with a reference spectral spectrum for a bare wafer or air is used to remove a large number of noises included in the measured spectral spectrum. In addition, a method using a test sample is also used to eliminate the influence of noise as described above, and an example of a method of manufacturing the test sample is disclosed in Japanese Patent Laid-Open No. 10-70168.

When applying the reference spectral spectrum for the bare wafer, it is cumbersome to obtain the reference spectral spectrum by loading the bare wafer into the FTIR inspection apparatus every time to perform the spectroscopic spectral measurement process, and apply the reference spectral spectrum for air In this case, since components other than the oxide film to be inspected in the measured spectral spectrum, that is, components on a wafer or a pattern or other film formed on the wafer, are detected, it is not easy to perform an accurate inspection process. In the actual inspection process, the reference spectral spectrum for air is used to eliminate the burden of loading the bare wafer every time, but this causes various noises to lower the reliability of the inspection process.

An object of the present invention to solve the above problems is to provide a wafer inspection apparatus having a reference block for obtaining a reference spectral spectrum for compensating the spectral spectrum of the film to be inspected.

1 is a schematic diagram illustrating a wafer inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view illustrating the reference block illustrated in FIG. 1.

3 is a plan view illustrating another example of the reference block illustrated in FIG. 1.

Explanation of symbols on the main parts of the drawings

10: reference sample 100: wafer inspection apparatus

110: chuck 120: reference block

130: light source 140: detector

150: Fourier transformer 160: data processing unit

170: display unit 180: drive unit

190: transfer robot W: wafer

The present invention for achieving the above object, the chuck supporting the wafer on which the film is formed, the chuck is provided on one side of the chuck, a reference block for supporting the reference sample, a light source for irradiating the first light, A detection unit for detecting second light irradiated from a light source and transmitted through the wafer and a third light irradiated from the light source and transmitted through the reference sample, and a second light from the second light and the third light detected by the detection unit, respectively. Fourier transformer for acquiring the first spectrum and the second spectrum, respectively, and a data processor for calculating the spectral spectrum for the film by correcting the first spectrum to the second spectrum Provided is a wafer inspection apparatus.

As an example, the film includes an oxide film such as fluorosilicate glass (FSG), boro silicate glass (BSG), borophosphosilicate glass (BPSG), and the like. The reference sample may be a bare wafer or a sample partially taken from the bare wafer. The first light includes infrared light, and the chuck is installed to be movable by the drive unit.

Therefore, it is easy to obtain a reference spectral spectrum for compensating the spectral spectrum of the film to be inspected, and the trouble of having to load the bare wafer into the inspection apparatus every time to obtain the reference spectral spectrum is eliminated. Therefore, the efficiency of the inspection process is improved, and the reliability of the inspection process is improved by removing various noises.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram illustrating a wafer inspection apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the wafer inspection apparatus 100 includes a chuck 110 for supporting a wafer W, a reference block 120 for supporting a reference sample 10, a light source 130, and a wafer. (W) and a detector 140 for detecting the light transmitted through the reference sample 10, a Fourier transformer 150 for obtaining the spectral spectrum of the detected light, and a data processor 160 for processing the spectral spectrum. It includes.

An oxide film, such as fluorosilicate glass (FSG), borosilicate glass (BSG), borophosphosilicate glass (BPSG), or the like is formed on the wafer W, and various patterns may be formed under the oxide film.

The chuck 110 for supporting the wafer W is provided to be movable by the drive unit. A detailed description of the driving unit will be made later, and the driving unit moves the chuck 110 such that the first light irradiated from the light source 130 is irradiated onto the wafer W or the reference sample 10. In addition, the position of the chuck 110 is adjusted to perform the inspection process at various points of the wafer (W).

One side of the chuck 110 is provided with a reference block 120 for supporting the reference sample 10. Here, the sample 10 taken from the bare wafer may be used as the reference sample 10. However, as shown in FIG. 3, the bare wafer 20 itself may be used as a reference sample.

In the process of inspecting the component and the concentration of the oxide film formed on the wafer (W), the first light irradiated from the light source 130 passes through the wafer (W) to form a second light, the second light detector 140 Is detected by Meanwhile, in a test process for obtaining a reference spectral spectrum, the first light irradiated from the light source 130 passes through the reference sample 10 to form a third light, and the third light is detected by the detector 140. do.

The Fourier transformer 150 performs Fourier transform on the amount of light of the second light detected by the detector 140 during the process of inspecting the component and the concentration of the oxide film formed on the wafer W to calculate the first spectroscopic spectrum in wave units. The amount of light of the third light detected by the detector 140 during the test process is Fourier-transformed to calculate the second spectroscopic spectrum in wave units. Here, the second spectroscopic spectrum corresponds to the reference spectral spectrum.

The data processor 160 stores the second spectroscopic spectrum, and in the process of measuring the component and the concentration of the oxide film formed on the wafer W, corrects the first spectroscopic spectrum with the second spectroscopic spectrum and includes it in the first spectroscopic spectrum. Remove the noise.

On the other hand, in the test process, it is possible to further obtain a third spectroscopic spectrum for the air. The third spectroscopic spectrum for air is stored in the data processor 160 along with the second spectroscopic spectrum and used to correct the first spectroscopic spectrum in the process of measuring the component and the concentration of the oxide film. That is, by correcting the first spectroscopic spectrum with the second and third spectroscopic spectra, the noise removing effect is improved, and the reliability of the component and concentration measurement result of the oxide film is improved.

The light source 130 may use light in an infrared region, and an infrared laser may be used. The light source 130 is installed on the upper plate 102 and includes a lamp 132, a first reflector 134, a wavelength selector 136, and a second reflector 138. The lamp 132 may be a lamp for irradiating light in the visible region, the infrared region, or both spectral regions. For example, tungsten lamps can be used, and carbon arcs, glow bars, and the like can also be used. At this time, a wavelength selector 136 is used to select the wavelength of the infrared region, and the light irradiated from the lamp 132 is formed into a beam having a desired band through the first reflector 134 and the wavelength selector 136. . Here, suitable wavelength selector 136 may be a band pass filter, a monochromator, or the like. On the other hand, when the infrared laser is used as the light source, the wavelength selector 34 is not necessary. In addition, the light source 130 may be formed by various optical configurations.

The detector 140 is disposed on the lower plate 104 positioned below the wafer W supported by the chuck 110, and the second or third light transmitted through the wafer W or the reference sample 10 is disposed. The light is irradiated to the detector 140 through the third reflector 142 and the fourth reflector 144 disposed on the lower plate 104.

On the other hand, the data processing unit 160 is connected to the display unit 170 for showing the first, second and third spectroscopic spectrum, and although not shown, a control unit for controlling the wafer inspection apparatus 100 as a whole and A data input unit is further provided. The arrow shown in FIG. 1 means a path of the first light and the second light.

FIG. 2 is a plan view for explaining the reference block shown in FIG. 1, and FIG. 3 is a plan view for explaining another example of the reference block shown in FIG. 1.

2 and 3, the reference block 120 for supporting the reference sample 10 is connected to one side of the chuck 110. The chuck 110 includes a pair of supports for supporting both sides of the wafer W. As shown in FIG. The chuck 110 is provided with a vacuum for adsorbing the wafer W, respectively, and is provided to be movable by the driving unit 180.

The driving unit 180 moves the chuck 110 in accordance with the xy Cartesian coordinate system, and moves the chuck 110 in the y-axis direction and the first driving unit 182 for moving the chuck 110 in the x-axis direction. The second driving unit 184 is included. The first driving unit 182 and the second driving unit 184 may be used in various ways, a ball screw type or a reciprocating cylinder type that can be widely used in general may be used.

As shown in FIG. 2, the square sample taken from the bare wafer is used as the reference sample 10, but as shown in FIG. 3, the bare wafer 20 itself may be used as the reference sample.

Hereinafter, the method of using the wafer inspection apparatus as described above is briefly described.

First, the reference sample 120 taken from the bare wafer is loaded into the reference block 120. Subsequently, the driving unit 180 is operated to move the chuck 110 so that the first light radiated from the light source 130 passes through the reference sample 10.

Subsequently, the first light is irradiated to the reference sample 10, and the third light transmitted through the reference sample 10 is detected using the detection unit 140. The Fourier transformer 150 obtains a second spectroscopic spectrum of the reference sample 10 from the third light, and the data processor 160 stores the acquired second spectroscopic spectrum. In this case, the display unit 170 displays the second spectroscopic spectrum.

Subsequently, the transfer robot 190 loads the wafer W on which the oxide film is formed on the chuck 110. The chuck 110 sucks the loaded wafer W using the vacuum pressure, and the driving unit 180 moves the chuck 110 so that the first light is irradiated onto the wafer W.

The first light irradiated from the light source 130 passes through the wafer W to form a second light, and the Fourier transducer 150 obtains the first spectroscopic spectrum from the light amount of the second light detected by the detector 140. do.

The data processor 160 calculates the spectral spectrum of the oxide film formed on the wafer W by correcting the first spectroscopic spectrum of the wafer W to the stored second spectroscopic spectrum.

At this time, the step of obtaining a third spectroscopic spectrum for the air may be further performed. In addition, the film formed on the wafer W is not limited to the oxide film, and the embodiment of the present invention can be applied to various film qualities, and the reference sample 10 is taken from not only a bare wafer but also a wafer on which various patterns are formed. You may.

According to the present invention as described above, the wafer inspection apparatus is equipped with a reference block for mounting the reference sample. Therefore, it is possible to eliminate the need to perform a test process by separately loading a bare wafer to obtain a reference spectral spectrum for correcting the spectral spectrum obtained from light transmitted through the wafer in the wafer inspection process.

In addition, by correcting the spectral spectrum of the inspection target wafer using the reference spectral spectrum for the bare wafer and the air, it is possible to improve the reliability of the measurement of the components and concentrations of the film formed on the wafer.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (5)

A chuck supporting the wafer on which the film is formed and movably installed; A reference block provided on one side of the chuck to support a reference sample; A light source for irradiating first light; A detection unit for detecting second light irradiated from the light source and transmitted through the wafer and third light irradiated from the light source and transmitted through the reference sample; A Fourier transformer for respectively obtaining a first spectrum and a second spectrum from the second light and the third light detected by the detector; And And a data processor for correcting the first spectroscopic spectrum with the second spectroscopic spectrum to calculate a spectral spectrum for the film. The wafer inspection apparatus of claim 1, wherein the reference sample comprises a bare wafer and a sample partially taken from the bare wafer. The wafer inspection apparatus of claim 1, wherein the first light comprises infrared light. The wafer inspection apparatus according to claim 1, further comprising a driving unit for moving the chuck to irradiate the wafer and the reference sample with the first light. The wafer inspection apparatus according to claim 1, further comprising a display unit for displaying the first and second spectroscopic spectra.