Auxiliary device for film thickness measurement by elliptical polarization method and film thickness measurement device
By combining reaction signal analysis with X-ray and elliptic polarization spectroscopy, the problems of surface contamination and laser damage were solved, enabling precise measurement of gate oxide layer thickness, reducing costs and ensuring compatibility with existing production lines.
Patent Information
- Application Number
- CN202520336746.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-27
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2035-02-27
AI Technical Summary
Existing elliptic polarization methods for measuring gate oxide thickness are hampered by surface contamination interfering with test results and the incident beam potentially damaging the thin film material. They cannot accurately measure the thickness of the natural oxide layer, and the excessively high laser energy limits high-precision applications.
By combining an X-ray generator, a signal collection module, and an energy analysis module, the damage to the film layer can be identified through the analysis of the reaction signals of the laser and X-ray beams. The energy of the light source can be corrected by an elliptic polarization spectrometer to avoid damage and achieve in-situ integration.
It effectively avoids damage to the thin film layer due to excessive laser energy, accurately measures the thickness of the gate oxide layer, reduces production and testing costs, and is compatible with existing production lines without the need for large-scale modifications.
Smart Images
Figure CN223580953U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to the field of semiconductor integrated circuit manufacturing, especially, a kind of film thickness measuring device. BACKGROUND
[0002] Ellipsometry is a technique for non-destructive measurement of transparent thin films using ellipsometry, which is a method for determining the refractive index and thickness of optical thin films by using the reflection of polarized light on the upper and lower surfaces of the film, and obtaining the relationship between optical parameters and polarization state by Fresnel formula. This measurement method is one of the most commonly used measurement methods for measuring the refractive index and thickness of optical thin films due to its speed, high precision and non-destructive measurement.
[0003] In semiconductor process, the thickness of gate oxide layer (i.e. Gate Oxide) needs to be accurately and efficiently monitored to achieve the required device electrical performance, so ellipsometry is often used to measure the thickness and / or structure of gate oxide layer. However, since the gate oxide layer is usually an ultrathin film with a thickness of between 1 nm and 10 nm, it is affected by natural oxidation from the end of thermal oxidation process to the next gate electrode process in process environment, but in practical application, this test technology only provides the thickness of the real-time measured oxide layer, and cannot accurately measure the thickness of the natural oxide layer, so the actual thickness of the gate oxide layer cannot be determined, which greatly interferes with the actual characterization and electrical performance evaluation. In addition, although ellipsometry is a non-contact measurement method for measuring the refractive index and / or thickness of a sample, the light source commonly used in ellipsometry is a laser, and high laser energy can unnecessarily damage the functional layer, and also limits its application in high-precision measurement field.
[0004] It should be noted that the above introduction to the technical background is only to facilitate the clear and complete description of the technical solutions of the present application, and to facilitate the understanding of those skilled in the art. The above technical solutions cannot be considered as known to those skilled in the art only because they are described in the background section of the present application. UTILITY MODEL CONTENT
[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present utility model is to provide an auxiliary device for ellipsometry film thickness measurement and a film thickness measurement device, to solve the problems of surface contamination interfering with test results, incident beam damaging the surface of thin film material, etc. when measuring the thickness of thin film by ellipsometry in existing process, for example, measuring the thickness of gate oxide layer.
[0006] To achieve the above-mentioned purpose and other related purposes, the utility model provides an auxiliary device for ellipsometry film thickness measurement, comprising:
[0007] A carrier for placing a workpiece to be tested, the workpiece to be tested having a target film layer formed on a side thereof away from the carrier;
[0008] A laser positioned above the carrier for providing a laser beam along a first optical path to the target film layer, the laser beam being projected to the target film layer to define a location of interest;
[0009] An X-ray generator disposed on a first side above the carrier for projecting an X-ray beam to the target film layer, the target film layer being excited by the X-ray beam to emit a reaction signal;
[0010] A positioning mechanism including a moving platform and support columns, the support columns being attached to the moving platform and having one end thereof passing through the carrier to be moved up and down for placing the workpiece to be tested on the carrier, the moving platform being positioned below the carrier for moving and positioning the workpiece to be tested on the first optical path;
[0011] A signal collection module for focusing an electron beam on the reaction signal emitted from the location of interest; and,
[0012] An energy analysis module positioned on a second side above the carrier for obtaining a photoelectron energy spectrum signal based on the focused electron beam for characterizing surface information of the target film layer, the second side being disposed opposite to the first side.
[0013] Optionally, the carrier includes a ring-shaped body and at least three through-holes passing through the ring-shaped body, the through-holes being aligned with the corresponding support columns one by one to allow the support columns to be moved up and down.
[0014] Optionally, the support columns are provided with hollow portions in fluid communication with an external air pump to fix the workpiece to be tested at one end of the support columns when the hollow portions are in a suction state.
[0015] Optionally, the signal collection module includes an electromagnetic lens positioned below the carrier, the moving platform having an open area to allow the electromagnetic lens to pass through the open area to be disposed adjacent to the workpiece to be tested.
[0016] Optionally, the moving platform is configured to move and position the workpiece to be tested in a three-dimensional space to allow the X-ray beam to be projected to the location of interest along a second optical path, at least a region of the location of interest being excited by the X-ray beam to emit a reaction signal; and, the energy analysis module is configured to obtain a photoelectron energy spectrum signal based on the reaction signal emitted from the excited region of the location of interest.
[0017] Optionally, the energy analysis module comprises a spherical capacitor analyzer arranged in a collection path of the electron beam, for obtaining photoelectron energy spectrum signals from the focused electron beam, the photoelectron energy spectrum signals being used to characterize the element composition and element chemical state of the target film layer.
[0018] Optionally, the signal collection module further comprises an electron beam collection optical assembly for adjusting the incident angle and kinetic energy of the focused electron beam.
[0019] Optionally, the auxiliary device further comprises a signal processing module, and the energy analysis module communicates with the signal processing module to compare the photoelectron energy spectrum signals obtained at the position of interest and other positions of the target film layer, and to identify whether the position of interest is damaged.
[0020] The utility model also provides a film thickness measuring device, comprising:
[0021] The auxiliary device for ellipsometry film thickness measurement described above;
[0022] The ellipsometry spectrometer is located above the carrier and comprises:
[0023] The light source part is used for providing an incident light beam along a predetermined optical path, and the incident light beam transmits the target film layer to generate a reflection signal;
[0024] The ellipsometric analyzer is used for collecting the reflection signal, and calculating the current thickness of the target film layer based on the reflection signal.
[0025] Optionally, the signal processing module is further included, and the light source part communicates with the signal processing module to adjust the energy of the incident light beam to be lower than the critical laser energy at which the position of interest of the target film layer is damaged.
[0026] As described above, the auxiliary device for ellipsometry film thickness measurement and the film thickness measuring device provided by the utility model have the following beneficial effects:
[0027] The auxiliary device for ellipsometry film thickness measurement of the utility model is combined with the existing ellipsometry spectrometer, additional components such as an X-ray generator, a signal collection module and an energy analysis module are attached to the sample table, and the analysis function of additional photoelectron energy spectrum signals is realized; in addition, the mechanism related to the loading and movement of the workpiece to be measured is improved, the workpiece to be measured is driven by the moving platform, the workpiece to be measured is positioned near the convergence of the laser beam and the X-ray beam, the reaction signals before and after laser irradiation can be used to identify whether the target film layer is damaged, the auxiliary device is compatible with the existing semiconductor production equipment and production platform, and large-scale modification of the existing production line is not required, and the production and detection costs can be effectively saved.
[0028] The auxiliary device can realize in-situ integration of XPS and ellipsometry analysis technology, obtain initial information of the target film layer based on reaction signals before and after laser irradiation, and identify whether the target film layer is damaged, so that the incident beam energy of the light source part of the ellipsometry spectrometer is corrected, and the target film layer is effectively prevented from being damaged by high laser energy. BRIEF DESCRIPTION OF DRAWINGS
[0029] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. It is apparent that the accompanying drawings are only some embodiments of the application.
[0030] Figure 1 A structure schematic view of the auxiliary device for ellipsometry film thickness measurement in the embodiment of the utility model is shown.
[0031] Figure 2 A top view of the bearing, positioning mechanism and related components in the embodiment of the utility model is shown.
[0032] Figure 3 A schematic view of sample wafer transmission by a mechanical arm in the embodiment of the utility model is shown.
[0033] Fig. 4 is a working state schematic view of the bearing, positioning mechanism and related components in the embodiment of the utility model; wherein, Figure 4A is a side view of the positioning mechanism carrying the workpiece to be measured; Figure 4B is a side view of the positioning mechanism carrying the workpiece to be measured to the bearing.
[0034] Figure 5 A working principle diagram of the electromagnetic lens in the auxiliary device for ellipsometry film thickness measurement in the embodiment of the utility model is shown.
[0035] Fig. 6 is a structure schematic view of the photoelectron signal receiver in the embodiment of the utility model; wherein, Figure 6B is Figure 6A A partial enlarged view of the electron beam collection optical assembly in the signal collection module is shown.
[0036] Figure 7 A structure schematic view of the film thickness measurement device in the embodiment of the utility model is shown.
[0037] Element number explanation
[0038] 11 laser
[0039] 12 X-ray generator
[0040] 13 light source part
[0041] 30 robotic arm
[0042] 31 carrier
[0043] 32 mobile platform
[0044] 34 support column
[0045] 36 hollow
[0046] 22 energy analysis module
[0047] 23 ellipsometry analyzer
[0048] 24 signal processing module
[0049] 221 electromagnetic lens
[0050] 212 entrance slit
[0051] 214 electron beam collection optics
[0052] 216 spherical condenser analyzer
[0053] 218 detector
[0054] W wafer under test
[0055] X X-ray beam
[0056] L laser beam DETAILED DESCRIPTION
[0057] The above objects and advantages of the present application will become more apparent by describing in detail the preferred embodiment thereof with reference to the attached drawings in which:
[0058] It should be emphasized that the terms "comprises / comprising" when used in this specification are taken to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
[0059] Features described and / or illustrated for one embodiment can be used in the same or similar manner in one or more other embodiments, in combination with or in place of
[0060] As in the detailed embodiments of the utility model, for facilitating the explanation, the sectional view showing the structure of the device will be partially enlarged without the general proportion, and the schematic diagram is only an example, which should not limit the scope of the utility model protection here. In addition, the three-dimensional spatial dimensions including length, width and depth should be contained in the actual production.
[0061] For the convenience of description, spatial relationship words such as 'under', 'below', 'lower than', 'under', 'above', 'upper' and the like can be used to describe the relationship of one element or feature with other elements or features shown in the drawings. It will be understood that these spatial relationship words are intended to include other directions of the device in use or operation in addition to the directions depicted in the drawings. In addition, when a layer is referred to as 'between' two layers, it can be the only layer between the two layers, or one or more intervening layers can also be present.
[0062] In the context of the present application, the structure described as the first feature being 'above' the second feature can include the embodiment in which the first and second features are formed in direct contact, and can also include the embodiment in which another feature is formed between the first and second features, so that the first and second features can not be in direct contact.
[0063] It should be noted that the diagrams provided in the embodiments only schematically illustrate the basic concept of the utility model, and only show the components related to the utility model in the diagrams, not the number, shape and size of the components when actually implemented. The actual implementation of each component can be arbitrarily changed in shape, number and proportion, and the component layout pattern can also be more complex.
[0064] The utility model provides a kind of auxiliary device for ellipsometric film thickness measurement, such as Figure 1As shown, the auxiliary device comprises a carrier, a laser, an X-ray generator, a positioning mechanism, a signal collection module and an energy analysis module. The carrier is used to place a workpiece to be tested, and a target film layer is formed on the side of the workpiece away from the carrier. The laser is used to provide a laser beam along a first optical path to the workpiece to be tested, and the laser beam is projected to the target film layer to define a position of interest. The X-ray generator is arranged on a first side above the carrier and is used to project X-rays to the position of interest. At least a part of the position of interest is excited by the X-rays to emit a reaction signal. The positioning mechanism comprises a moving platform and a support column. The support column is attached to the moving platform and one end of the support column is lifted through the carrier to place the workpiece to be tested in place on the carrier. The moving platform is located below the carrier and is used to move and position the workpiece to be tested on the first optical path. The signal collection module is used to focus an electron beam on the reaction signal emitted by the position of interest. The energy analysis module is located on a second side above the carrier and is used to identify whether the target film layer is damaged based on the focused electron beam. The second side is arranged opposite to the first side.
[0065] Specifically, the X-ray generator can use a high-energy electron gun commonly used in the art to generate an X-ray beam by emitting an electron beam to bombard a metal anode. The moving platform can be used to move and position the workpiece to be tested in a three-dimensional space so that the X-ray beam is projected to the position of interest along a second optical path. The X-ray beam overlaps or is within the position of interest. The reaction signal includes photoelectrons, Auger electrons, secondary electrons and uncharged rays emitted by at least a region of the position of interest excited by the X-rays. The laser can be a high-power pulsed laser. In addition to defining the position of interest, the laser beam is used to scan the target film layer to remove contamination. The pulsed laser can set the pulse width, power, beam diameter and / or similar parameters of the laser according to the required laser energy.
[0066] The carrier can be placed on the positioning mechanism to move in a three-dimensional space under the driving of the moving platform. Figure 2 The carrier, the positioning mechanism and related components are shown as a top view. As Figure 2 As shown, in some examples, the carrier 31 can have a ring-shaped body and at least three through holes passing through the ring-shaped body.
[0067] The support column can be lifted from an initial position below the plane where the moving platform is located to a loading position above the carrier. The moving platform is attached to multiple support columns, for example, more than 3. As Figure 2As shown, the carrier 31 has a ring-shaped body, and a plurality of support columns 34 are arranged along the circumference of the ring-shaped body, and each support column 34 is aligned with a corresponding through hole of the ring-shaped carrier to allow the support column to pass through the ring-shaped carrier for lifting movement to pick up the workpiece from the robot arm, for example, as shown in Figure 3 As shown, the robot arm 30 transfers the workpiece W to the support columns 34, so that the support columns 34 collectively support the workpiece in a horizontal state, and the workpiece is placed in position on the carrier.
[0068] In a preferred example, the support column 34 can be provided with a hollow portion in fluid communication with an external air pump, and the hollow portion can be subjected to air suction by the air pump to fix the workpiece at one end of the support column. Figure 4A and Figure 4B The working state diagram of the carrier, positioning mechanism and related components is shown, as shown in Figure 4A As shown, when the support column 34 is lifted to the loading position, the workpiece is transferred to the support column 34 by the robot arm, and the plurality of support columns are lowered to carry the workpiece to the contact position with the carrier, i.e. placed in position, as shown in Figure 4B As shown, during the measurement operation, the support column can be lowered to an initial position below the plane where the moving platform is located to avoid blocking the optical path. By fixing the workpiece at one end of the support column by keeping the hollow portion in a suction state, the support column 34 drives the workpiece to move up and down, and / or the moving platform 32 performs positioning operation, thereby providing a holding force on the workpiece without the need for additional clamping mechanisms.
[0069] As shown in Figure 2 As shown, the moving platform 32 is provided as a square moving platform as a whole, and the signal collection module includes an electromagnetic lens, which can be located below the carrier. The working principle of the electromagnetic lens is as shown in Figure 5 As shown, an axisymmetric curved magnetic field is used, which has a focusing effect on the electron beam, thereby forming an electron optical image. In the electromagnetic lens, due to the non-uniform distribution of the magnetic field, the electrons in the magnetic field are subjected to both axial and radial components, so that the electron beam entering the magnetic field can obtain a focusing effect. In some examples, the moving platform 32 has a hollow region. The electromagnetic lens 221 penetrates the hollow region of the moving platform and the carrier to be adjacent to the workpiece, which reduces the absorption and reflection of electromagnetic waves, and is beneficial to enhance the focusing effect of the electron beam, so that most of the effective signals can be collected.
[0070] In a specific example, the signal collection module further includes an electron beam collection optical element for adjusting or matching the incident angle and kinetic energy of the focused electron beam, as shown in Figure 6AAs shown, the focused electron beam can enter the electron beam collection optical assembly 214 through the entrance slit 212.
[0071] Further, the energy analysis module comprises a spherical capacitor analyzer and a detector, such as Figure 6B As shown, the spherical capacitor analyzer 216 is arranged in the collection path of the electron beam for obtaining photoelectron energy spectrum signals from the collected electron beam, the focused electron beam sequentially passes through the electron beam collection optical assembly 214, the spherical capacitor analyzer 216 and reaches the detector 218 along the electron beam collection path, the detector 218 can resolve photoelectron energy spectrum signals for characterizing surface information, the photoelectron energy spectrum signals include full element spectrum of the target film layer and fine spectrum corresponding to element chemical state, for characterizing element composition and / or element chemical state of the target film layer, and for identifying contaminations such as particles, polymers and the like attached, adsorbed or similarly combined on the surface thereof.
[0072] In some examples, the auxiliary device further comprises a signal processing module, the X-ray generator communicates with the signal processing module to project an X-ray beam to the target film layer before the target film layer is irradiated by the laser beam, thereby obtaining a reaction signal for characterizing initial information of the target film layer; and the X-ray beam is projected to the target film layer after the irradiation of the laser beam defines the position of interest, and a reaction signal of the position of interest of the target film layer is obtained. Further, the energy analysis module communicates with the signal processing module to compare photoelectron energy spectrum signals obtained at the position of interest and other positions of the target film layer, and to identify whether the position of interest is damaged; wherein, based on the ratio of characteristic peak intensity of element chemical state of the target film layer and its base material obtained at the position of interest of the target film layer, equal to or less than one half of the ratio of characteristic peak intensity of element chemical state of the target film layer and its base material obtained at other positions of the target film layer, the position of interest is identified as damaged.
[0073] Embodiments of the present application provide a film thickness measuring device, the film thickness measuring module preferably comprises the auxiliary device of the ellipsometry film thickness measuring described previously; and an ellipsometry spectrometer located above the carrier.
[0074] Figure 7 The structure of the film thickness measuring device in the embodiments of the present application is shown. As Figure 7As shown, the ellipsometer includes a light source portion for providing an incident light beam along a predetermined optical path, the incident light beam transmits the target film layer to generate a reflected signal including an ellipsometric light. For example, the light source portion employs a Xenon (Xe) lamp having a spectral range covering from 190 nm to 2100 nm for providing higher measurement accuracy and sensitivity.
[0075] In one implementation, the auxiliary device is configured to determine an incident light beam energy of the light source portion, the light source portion communicates with the signal processing module to adjust an energy magnitude of the incident light beam to be lower than a critical laser energy at which a location of interest of the target film layer is damaged, effectively avoiding the laser energy being too high to damage the target film layer.
[0076] The ellipsometer further includes an ellipsometric analyzer for collecting the reflected signal, and calculating a current thickness of the target film layer based on the reflected signal. Further, the signal processing module can store a relationship model of optical parameters and thickness of the target film layer, and calculate the current thickness of the target film layer based on the relationship model, the optical parameters used in the relationship model including a refractive index and an extinction coefficient.
[0077] The ellipsometer includes one of a photometric ellipsometer and an extinction ellipsometer. In some examples, the film thickness measurement device employs the photometric ellipsometer, and the ellipsometric analyzer includes a polarizer, a beamsplitter, and similar optical components for selecting the ellipsometric light signal. In other examples, the film thickness measurement device employs the extinction ellipsometer, and the ellipsometric analyzer includes a spatial filter for selecting a power density in the reflected signal.
[0078] In one specific example, the ellipsometer further includes a polarizer disposed on the predetermined optical path for providing a light beam having a controllable polarization state, for example, a linearly polarized light having a known polarization state based on the incident light beam. Based on a change in relative amplitude and phase of the linearly polarized light after being reflected by a surface of a thin film material, the ellipsometric analyzer communicates with the signal processing module to establish a relationship model of optical parameters and thickness of the thin film material, and thereby calculate a thickness value of the thin film material.
[0079] The film thickness measurement device described above can be used for elemental composition analysis, elemental chemical state analysis, and thickness analysis of an ultra-thin film, wherein the thickness of the ultra-thin film is less than or equal to 10 nm.
[0080] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.
Claims
1. An auxiliary device for film thickness measurement using elliptic polarization, characterized in that, include: A carrier for placing the workpiece to be tested, wherein a target film layer is formed on the side of the workpiece away from the carrier; A laser, located above the carrier, is used to provide a laser beam to the target film along a first optical path, the laser beam being projected onto the target film to define a location of interest; An X-ray generator is disposed on a first side above the carrier and is used to project an X-ray beam onto the target film, wherein the target film is excited by the X-ray beam and emits a reaction signal. A positioning mechanism, comprising a moving platform and a support column, wherein the support column is attached to the moving platform and one end of the support column passes through the carrier and moves up and down to place the workpiece to be tested in place on the carrier, and the moving platform is located below the carrier to move and position the workpiece to be tested on the first optical path. The signal collection module is used to focus the electron beam on the reaction signal emitted from the location of interest; In addition, an energy analysis module, located on the second side above the carrier, is used to acquire photoelectron spectral signals for characterizing the surface information of the target film based on the focused electron beam, the second side being disposed opposite to the first side.
2. The auxiliary device for film thickness measurement by elliptic polarization method according to claim 1, characterized in that: The support member includes an annular body and at least three through holes penetrating the annular body, the through holes being aligned with corresponding support columns to allow the support columns to move up and down.
3. The auxiliary device for film thickness measurement by elliptic polarization method according to claim 1, characterized in that: The support column is provided with a hollow part that is in fluid communication with an external air pump so that the workpiece to be tested can be fixed to one end of the support column when the hollow part is in a suction state.
4. The auxiliary device for film thickness measurement by elliptic polarization method according to claim 1 or 2, characterized in that: The signal collection module includes an electromagnetic lens located below the carrier, and the moving platform has a cutout area to allow the electromagnetic lens to penetrate the cutout area and be positioned adjacent to the workpiece to be tested.
5. The auxiliary device for film thickness measurement by elliptic polarization method according to claim 1, characterized in that: The mobile platform is configured to move and position the workpiece under test in three-dimensional space so that the X-ray beam is projected toward the position of interest along a second optical path, and at least one region of the position of interest is excited by the X-ray beam to emit a reaction signal. The energy analysis module is configured to acquire photoelectron spectral signals based on the reaction signals emitted from the excitation region at the location of interest.
6. The auxiliary device for film thickness measurement by elliptic polarization method according to claim 1, characterized in that: The energy analysis module includes a spherical capacitor analyzer, which is positioned on the collection path of the electron beam and is used to acquire photoelectron spectroscopy signals from the focused electron beam. The photoelectron spectroscopy signals are used to characterize the elemental composition and chemical states of the target film.
7. The auxiliary device for film thickness measurement by elliptic polarization method according to claim 6, characterized in that: The signal collection module also includes an electron beam collecting optical component for adjusting the incident angle and kinetic energy of the focused electron beam.
8. The auxiliary device for film thickness measurement by elliptic polarization method according to claim 5, characterized in that: The auxiliary device also includes a signal processing module, and the energy analysis module communicates with the signal processing module to compare the photoelectron energy spectrum signals obtained from the target film at the location of interest and other locations to identify whether the location of interest is damaged.
9. A film thickness measuring device, characterized in that, include: An auxiliary device for film thickness measurement by elliptic polarization as described in any one of claims 1 to 8; An elliptic polarization spectrometer, located above a support, includes: The light source section is used to provide an incident light beam along a predetermined optical path, the incident light beam passing through the target film to generate a reflected signal; An elliptic polarizer is used to collect the reflected signal and calculate the current thickness of the target film based on the reflected signal.
10. The film thickness measuring device according to claim 9, characterized in that, Also includes: A signal processing module, wherein the light source part communicates with the signal processing module to adjust the energy amplitude of the incident beam to below the critical laser energy at which the target film is damaged at the point of interest.