CN219767851U - Chemical mechanical polishing system - Google Patents
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- CN219767851U CN219767851U CN202321060845.0U CN202321060845U CN219767851U CN 219767851 U CN219767851 U CN 219767851U CN 202321060845 U CN202321060845 U CN 202321060845U CN 219767851 U CN219767851 U CN 219767851U
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Abstract
The present utility model provides a chemical mechanical polishing system comprising: a front unit in which a wafer is stored; an apparatus main body for performing a polishing operation on a wafer; the mechanical arm is used for interacting between the front unit and the equipment main body so as to transfer the wafer; the front value measuring unit is used for measuring the thickness of the wafer before polishing in the wafer transmission process; and the back value measuring unit is used for measuring the thickness of the polished wafer in the wafer transmission process. The utility model integrates the wafer thickness measuring module into the chemical mechanical polishing system, can realize real-time measurement of the film thickness of the wafer surfaces before and after polishing in the wafer transmission process, and adjusts the polishing process according to the change relation of the deposition layer thickness of the wafer surfaces before and after historical polishing and the initial thickness of the next piece of incoming material.
Description
Technical Field
The utility model belongs to the technical field of wafer production, and particularly relates to a chemical mechanical polishing system.
Background
Integrated circuits (Integrated Circuit, IC) are the core and proposition of the development of the information technology industry. Integrated circuits are typically formed by sequentially depositing conductive, semiconductive, or insulative layers on a silicon wafer. Thereby depositing a film formed by the filler layer on the surface of the wafer. In the manufacturing process, a planarization operation is performed on the surface film layer.
Chemical Mechanical Polishing (CMP) is a well-known planarization method. The planarization method realizes the planarization of the film layer through the dual functions of physical grinding and chemical reaction, when in grinding, a polishing pad is arranged on a polishing table, a wafer is fixed on a bearing head, polishing liquid comprising grinding particles and grinding slurry is conveyed from a polishing liquid pipe to a polishing liquid arm and flows onto the polishing pad through the polishing liquid arm, the bearing head can contact the wafer with the polishing pad, exert pressure and rotate, and then the grinding of the film layer of the wafer is realized.
Various optical metrology systems, such as spectroscopic or ellipsometric measurement systems, may be used to measure the thickness before and after polishing, such as in-line metrology modules or stand-alone metrology equipment. In addition, various in situ monitoring techniques, such as optical or eddy current detection, may be used to detect the polishing endpoint.
The existing film thickness measuring technology for the transparent dielectric film and the semiconductor film on the surface of the wafer generally adopts measuring equipment hung on one side of the equipment main body to measure the thickness of the off-line wafer, so that the WPH of a production line is reduced, and the cost is higher.
Disclosure of Invention
The present utility model aims to solve at least one of the technical problems in the related art to some extent. To this end, the present utility model proposes a chemical mechanical polishing system.
An embodiment of the present utility model provides a chemical mechanical polishing system comprising:
a front unit in which a wafer is stored;
an apparatus main body for performing a polishing operation on a wafer;
the mechanical arm is used for interacting between the front unit and the equipment main body so as to transfer the wafer;
the front value measuring unit is used for measuring the thickness of the wafer before polishing in the wafer transmission process;
and the back value measuring unit is used for measuring the thickness of the polished wafer in the wafer transmission process.
In some embodiments, the apparatus body includes a polishing unit, a cleaning unit, a drying unit, and a transfer unit, and the wafer is sequentially transferred between the pre-unit, the polishing unit, the cleaning unit, the drying unit, and the transfer unit.
In some embodiments, the robot is located between the pre-unit and the apparatus body for transporting wafers from the pre-unit to the polishing unit and for transporting wafers from the transfer unit back to the pre-unit.
In some embodiments, the front value measurement unit is located on a wafer transmission path between the wafer outlet of the front unit and the apparatus main body.
In some embodiments, the back value measurement unit is located on a wafer transmission path between the apparatus main body and the wafer inlet of the front unit.
In some embodiments, the front value measurement unit and the back value measurement unit are configured to emit probe light toward a wafer.
In some embodiments, the robot carries the wafer to move at a constant speed, and the front value measurement unit and the rear value measurement unit emit probe light to the surface of the wafer for multiple times within a fixed time interval, so as to obtain measurement values at different points of the wafer.
In some embodiments, the front value measuring unit and the rear value measuring unit are located in a plane where the diameter of the wafer is located and perpendicular to the wafer, and along with the movement of the wafer, the probe light irradiates the surface of the wafer vertically and moves along the diameter direction of the wafer.
In some embodiments, the front value measurement unit includes a front value measurement probe and a front value measurement controller connected thereto;
the back value measuring unit comprises a back value measuring probe and a back value measuring controller connected with the back value measuring probe.
In some embodiments, the front value measurement controller and the back value measurement controller are each independently electrically connected to a host computer.
Compared with the prior art, the utility model has the beneficial effects that:
the utility model integrates the wafer thickness measuring module into the chemical mechanical polishing system, can realize real-time measurement of the film thickness of the wafer surfaces before and after polishing in the wafer transmission process, and adjusts the polishing process according to the change relation of the deposition layer thickness of the wafer surfaces before and after historical polishing and the initial thickness of the next piece of incoming material.
Drawings
The advantages of the present utility model will become more apparent and more readily appreciated from the detailed description given in conjunction with the following drawings, which are meant to be illustrative only and not limiting of the scope of the utility model, wherein:
FIG. 1 is a schematic diagram of a chemical mechanical polishing system according to one embodiment of the present utility model;
FIG. 2 is a front view illustrating a detection process of a front value measurement unit according to an embodiment of the present utility model;
FIG. 3 is a schematic diagram showing the structures of a front value measuring unit and a rear value measuring unit according to an embodiment of the utility model;
FIG. 4 is a top view of a wafer inspection process according to one embodiment of the present utility model;
FIG. 5 is a schematic view showing the structure of a polishing unit according to an embodiment of the present utility model;
FIG. 6 is a schematic diagram showing a structure of a cleaning unit according to an embodiment of the utility model;
FIG. 7 is a diagram of the optical path within a front value measurement probe according to an embodiment of the present utility model;
FIG. 8 is a schematic diagram illustrating a structure of a front-value measurement unit according to an embodiment of the utility model;
FIG. 9 is a schematic diagram showing the structure of an assay module according to an embodiment of the present utility model;
fig. 10 is a flowchart of a polishing parameter control method according to an embodiment of the present utility model.
Detailed Description
The following describes the technical scheme of the present utility model in detail with reference to specific embodiments and drawings thereof. The examples described herein are specific embodiments of the present utility model for illustrating the concept of the present utility model; the description is intended to be illustrative and exemplary in nature and should not be construed as limiting the scope of the utility model in its aspects. In addition to the embodiments described herein, those skilled in the art can adopt other obvious solutions based on the disclosure of the claims and the specification thereof, including those adopting any obvious substitutions and modifications to the embodiments described herein.
The drawings in the present specification are schematic views, which assist in explaining the concept of the present utility model, and schematically show the shapes of the respective parts and their interrelationships. It should be understood that for the purpose of clearly showing the structure of various parts of embodiments of the present utility model, the drawings are not drawn to the same scale and like reference numerals are used to designate like parts in the drawings. The technical scheme of the utility model is further described by the following specific embodiments.
In the present utility model, "chemical mechanical polishing (Chemical Mechanical Polishing, CMP)" is also referred to as "chemical mechanical planarization (Chemical Mechanical Planarization, CMP)". The Wafer (W) is also called a Substrate (Substrate), and its meaning is equivalent to its actual function.
In one embodiment, as shown in FIG. 1, the present embodiment provides a chemical mechanical polishing system comprising:
a front unit 100 in which a wafer w is stored;
an apparatus main body for performing polishing work on a wafer w;
a robot 200 that performs interaction between the head unit 100 and the apparatus body to transfer the wafer w;
a front value measurement unit 700 for measuring the thickness of the wafer w before polishing during the wafer w transfer process;
the post value measuring unit 800 is used for measuring the thickness of the polished wafer w during the wafer w transferring process.
In this embodiment, a front value measurement unit 700 and a back value measurement unit 800 are installed between the front unit 100 (EFEM) and the apparatus main body, and before chemical mechanical polishing, the robot 200 in the EFEM transfers the wafer w in the wafer cassette to the temporary storage station of the apparatus main body, and during this transfer process, the front value measurement unit 700 completes the film thickness measurement of the wafer w, and obtains the thickness of the wafer w before polishing.
The wafer w is polished, cleaned and dried in the apparatus main body, and after the processing is completed, the wafer w is taken out from the temporary storage station of the apparatus main body by the manipulator 200 in the EFEM, and in this transmission process, the post value measurement unit 800 completes the film thickness measurement of the wafer w, and the thickness of the polished wafer w is obtained.
Based on the information such as the thickness change relation of the wafer w before and after polishing, the thickness of the wafer w after polishing, polishing process parameters, the thickness of the incoming material before polishing and the like, the process parameters of subsequent polishing are adjusted, and the manufacturing quality of the integrated circuit is improved.
In the chemical mechanical polishing system provided by the embodiment, the film thickness measuring module of the wafer w is integrated in the chemical mechanical polishing system, real-time measurement of the thickness of the film layer on the surface of the wafer w before and after polishing can be realized in the transmission process of the wafer w, and the polishing process is adjusted according to the change relation of the thickness of the surface deposition layer before and after polishing of the historical wafer w and the initial thickness of the incoming material of the next wafer w.
The front unit 100 includes two or more front loading portions for accommodating wafer cassettes in which a plurality of wafers w are stored. The front loading portion is disposed adjacent to the housing of the chemical mechanical polishing system and is aligned in a width direction of the housing. The front loading section may be loaded with an open box, SMIF (Standard Manufacturing Interface) box, or FOUP (Front Opening UnifiedPod). The SMIF and the FOUP are sealed containers which internally house the wafer cassettes and are covered by a partition plate, thereby maintaining the relative isolation of the inner space and the outer space.
The front unit 100 is provided with a moving mechanism along the arrangement of the front loading units, and the moving mechanism is provided with at least one robot 200 movable along the arrangement direction of the wafer cassettes. The robot 200 is configured to be movable on a moving mechanism, and is capable of accessing wafers w mounted in a wafer cassette of a front loading unit. The robot 200 takes out the wafer w before processing from the cassette and returns the wafer w after processing to the cassette.
The inside of the front unit 100 needs to be kept in a clean state, and thus the inside of the front unit 100 needs to be maintained at a higher pressure than the apparatus main body. Meanwhile, a filter unit having a clean air filter such as a HEPA filter, a ULPA filter, or a chemical filter is provided in the front unit 100, and contaminated air containing particles, toxic vapor, or toxic gas in the front unit 100 is discharged through the filter unit to maintain a clean state inside the front unit 100.
Further, the apparatus body includes a polishing unit 300, a cleaning unit 400, a drying unit 500, and a transfer unit 600 sequentially arranged along a transfer direction of the wafer w, which is sequentially transferred between the front unit 100, the polishing unit 300, the cleaning unit 400, the drying unit 500, and the transfer unit 600. The robot 200 is located between the front unit 100 and the apparatus main body, and serves to transfer the wafer w from the front unit 100 to the polishing unit 300 and to transfer the wafer w from the transfer unit 600 back to the front unit 100.
The structures of the polishing unit 300, the cleaning unit 400, and the drying unit 500 are briefly described as follows:
the polishing unit 300 is a region where global planarization of the wafer w is performed, and at least one set of polishing apparatuses is provided in the polishing unit 300, and when a plurality of polishing apparatuses are provided, each polishing apparatus may be arranged along the length direction of the housing.
The embodiment shown in fig. 5 provides a polishing unit 300, and the main structure of the polishing unit 300 may include a polishing pad 310, a carrier head 330, a polishing liquid supply device 340, and a conditioner 350.
The polishing disk 310 is rotatable around its axis and has a polishing pad 320 having an abrasive surface mounted on its surface, and the polishing pad 320 may be a hard pad of foamed polyurethane type, a soft pad of suede type, a sponge, or the like. The type of the polishing pad 320 is adaptively selected according to the material of the object to be treated and the state of the contaminant to be removed.
The carrier head 330 is used for holding a wafer w and pressing the wafer w onto the surface of the polishing pad 320 on the polishing disk 310, and the wafer w is held on the lower surface of the carrier head 330 by vacuum adsorption and drives the wafer w to rotate around the axis thereof, so as to polish the wafer w under the action of the polishing solution and the polishing pad 320.
The polishing liquid supply device 340 is used to supply a polishing liquid and a dressing liquid (e.g., pure water) to the surface of the polishing pad 320. Specifically, the polishing liquid supply apparatus 340 includes a pure water nozzle for supplying pure water to the polishing surface of the wafer w, and the pure water nozzle is connected to a pure water supply source via a pure water pipe. The pure water pipe is provided with a control valve capable of opening and closing the pure water pipe, and pure water can be supplied to the polishing surface of the wafer w at any timing by opening and closing the control valve. The polishing liquid supply device 340 further includes a chemical liquid nozzle for supplying a polishing liquid to the polishing surface of the wafer w, and the chemical liquid nozzle is connected to a chemical liquid supply source via a chemical liquid pipe. The chemical liquid pipe is provided with a control valve capable of opening and closing the chemical liquid pipe, and chemical liquid can be supplied to the polishing surface of the wafer w at any timing by opening and closing the control valve. In chemical mechanical polishing, a polishing liquid is supplied from a polishing liquid supply device 340 onto the polishing surface of the polishing pad 320, and a wafer w to be polished is pressed against the polishing surface of the polishing pad 320 by a carrier head 330 and polished.
The dresser 350 is used to dress the abrasive surface of the polishing pad 320, and the polishing pad 320 can remove impurity particles remaining on the surface of the polishing pad 320, such as abrasive particles in a polishing liquid, and waste material falling off from the surface of the wafer w; the trimmer 350 can also adjust the surface morphology of the polishing pad 320 to meet the polishing process requirements, so as to stabilize the polishing removal rate of the wafer w and realize global planarization of the wafer w.
When the wafer w is chemically and mechanically polished, the carrier head 330 is rotated while reciprocating in the radial direction of the polishing pad 310 so that the surface of the wafer w in contact with the polishing pad 320 is gradually polished while the polishing pad 310 is rotated, and the polishing liquid supply device 340 sprays the polishing liquid to the surface of the polishing pad 320. The wafer w is rubbed against the polishing pad 320 by the relative motion of the carrier head 330 and the polishing platen 310 under the chemical action of the polishing liquid to perform polishing.
The polishing solution composed of submicron or nanometer abrasive particles and chemical solution flows between the wafer w and the polishing pad 320, the polishing solution is uniformly distributed under the action of the transmission and rotation centrifugal force of the polishing pad 320 to form a layer of liquid film between the wafer w and the polishing pad 320, chemical components in the liquid react with the wafer w to convert insoluble substances into soluble substances, then the chemical reactants are removed from the surface of the wafer w through micro-mechanical friction of the abrasive particles and dissolved into the flowing liquid to be taken away, and surface materials are removed in the alternating process of chemical film formation and mechanical film removal to realize surface planarization treatment, so that the purpose of global planarization is achieved.
The conditioner 350 is used to condition and activate the surface topography of the polishing pad 320 during polishing. The use of the conditioner 350 can remove impurity particles remaining on the surface of the polishing pad 320, such as abrasive particles in the polishing liquid, and waste material falling off from the surface of the wafer w, and planarize the deformation of the surface of the polishing pad 320 due to the polishing, ensuring the uniformity of the surface topography of the polishing pad 320 during polishing, and further maintaining the polishing removal rate stable.
After chemical mechanical polishing, the wafer w needs to be subjected to post-treatment such as cleaning and drying, so as to avoid pollution of trace ions and metal particles to semiconductor devices and ensure the performance and qualification rate of the semiconductor devices.
The cleaning mode can be double-fluid jet cleaning, rolling brush cleaning, megasonic cleaning or the like. The twin-fluid jet cleaning is a cleaning process in which minute droplets (mist) carried by a high-velocity gas are ejected from a twin-fluid nozzle toward the wafer w and collide with the surface of the wafer w, and particles and the like on the surface of the wafer w are removed by a shock wave generated by the collision of the minute droplets with the surface of the wafer w. The rolling brush cleaning may be classified into vertical rolling brush cleaning and horizontal rolling brush cleaning according to the placed state of the wafer w. Megasonic cleaning is a process of applying ultrasonic waves to a cleaning liquid to apply a force generated by the vibration acceleration of the cleaning liquid molecules to particles and other adhering particles to remove the particles.
The cleaning unit 400 in the chemical mechanical polishing system provided in this embodiment preferably employs a vertical cleaning apparatus, which in the embodiment shown in fig. 6 includes: a chamber 410 having a chamber for cleaning the wafer w formed therein; a cleaning assembly 420 including a rolling brush positioned at both sides of the wafer w; a support assembly positioned below the cleaning assembly 420 and in contact with an edge of the wafer w for supporting and defining the wafer w to rotate in a vertical plane; and a spray assembly 450 for spraying the cleaning liquid onto the surface of the wafer w.
Specifically, the cleaning assembly 420 includes two rolling brushes respectively disposed on two side surfaces of the wafer w, and the two rolling brushes reversely rotate to roll and brush the surface of the wafer w, for example, one rolling brush rotates clockwise while the other rolling brush rotates counterclockwise. Particularly preferably, the rotation direction of the rolling brushes at the two sides is away from the surface of the wafer w, so that upward friction force is generated on the wafer w when the rolling brushes rotate, so that the relative speed between the rolling brushes and the wafer w is maximized in the area where the cleaning liquid falls, and the brushing effect is improved.
The round brush includes the cavity axle and the sponge of cladding in cavity axle periphery, the round brush is installed on a pair of rotatable fixed knot constructs, the fixed knot of round brush one end constructs and is provided with the feed liquor hole, through the inside feed liquor (washing liquid or rinsing liquid) of feed liquor hole to the cavity axle of round brush, a plurality of play liquid holes of evenly distributed on the cavity axle, so that the epaxial liquid can pass out the liquid hole and reach the sponge and ooze from the sponge, thereby moisturize for the round brush, and make the sponge surface form the liquid film, prevent that the sponge direct contact from leading to pollutant on the sponge to back to glue pollution wafer w.
The support assembly includes a first driving wheel 430, a second driving wheel 450 and a tachometer wheel 440, wherein the tachometer wheel 440 is located at the bottommost part of the edge of the wafer w, and the first driving wheel 430 and the second driving wheel 450 are symmetrically disposed on two sides of the tachometer wheel 440 with the tachometer wheel 440 as a center.
When the wafer w is cleaned, the first driving wheel 430 and the second driving wheel 450 are driven by the respective driving motors to rotate. The rolling brushes on two sides of the wafer w are contacted with the surface of the wafer w and rotate around the axis of the rolling brush, the wafer w vertically arranged in the gap between the two rolling brushes rotates around the axis of the wafer w under the action of friction force, and the rolling brushes are contacted with the rotating wafer w to remove pollutants on the surface of the wafer w. The tachometer wheel 440 is driven to passively rotate in the rotation process of the wafer w, the rotation number of the tachometer wheel 440 is calculated through a rear sensor, so that the rotation speed of the wafer w is calculated, and the cleaning state of the wafer w is monitored.
The spray assembly 450 comprises two spray bars which are positioned above the cleaning assembly 420 and are parallel to each other, a plurality of spray nozzles are uniformly distributed on the spray bars, and cleaning liquid sprayed by the spray nozzles at least covers the contact area between the cleaning assembly 420 and the wafer w.
The cleaned wafer w is sent to the drying unit 500 for drying, optionally by spin drying or marangoni drying. The rotary drying refers to that the wafer w is horizontally clamped by the clamping jaws and is driven to rotate at a high speed so as to spin-dry the residual cleaning liquid on the surface of the wafer w. The marangoni drying refers to that a thin water film is generated on the outer surface of the wafer w by flowing deionized water, and then a large amount of isopropanol gas is introduced to remove the water layer on the wafer w, so that the wafer w is dried.
The chemical mechanical polishing system according to the present embodiment is significantly different from the prior art in that a front value measuring unit 700 is disposed between the front unit 100 and the polishing unit 300, and is used for measuring the thickness of the wafer w in real time on the moving path of the robot 200 for feeding the wafer w from the front unit 100 into the polishing unit 300. A back value measuring unit 800 is provided between the transfer unit 600 and the front unit 100 for measuring the thickness of the wafer w in real time on a moving path of the robot 200, which is the path along which the wafer w is transferred from the transfer unit 600 to the front unit 100.
The front value measurement unit 700 and the rear value measurement unit 800 are configured to emit probe light toward the wafer w, the front value measurement unit 700 and the rear value measurement unit 800 are located in a plane where a diameter of the wafer w is located and perpendicular to the wafer w, the probe light is perpendicularly irradiated to a surface of the wafer w as the wafer w moves, and a light spot 715 formed on the surface of the wafer w by the probe light moves along the diameter direction of the wafer w (as shown in fig. 4).
At least a portion of the deposited layer on the surface of the wafer w allows probe light of a specific wavelength to pass through and interact with the material below the deposited layer, reflected light is formed after being reflected from the material below, the spectrum of the reflected light generated by different film thicknesses is different, the change in the absorption spectrum is collected by a detector or sensor and converted into an electrical signal, and the electrical signal can be evaluated by the host computer 900 to obtain optical data to determine the thickness or other properties of the measured film.
Specifically, as shown in fig. 2 and 3, the front value measurement unit 700 includes a front value measurement probe 710 and a front value measurement controller 720 connected thereto, and the rear value measurement unit 800 includes a rear value measurement probe 810 and a rear value measurement controller 820 connected thereto, and the front value measurement controller 720 and the rear value measurement controller 820 are electrically connected to the upper computer 900 independently, respectively.
In this embodiment, the front value measurement probe 710 and the rear value measurement probe 810 have the same structure, and the structure of the front value measurement controller 720 is briefly described as an example:
as shown in FIG. 7, front value measurement probe 710 includes beam splitter 712, first lens 711, second lens 714, and third lens 713.
A first lens 711 and a beam splitter 712 are sequentially disposed along a light transmission direction on an optical path between the light source 721 and the surface of the wafer w, and the first lens 711 is configured to expand the probe light. The beam splitter 712 is configured to reflect the probe light and transmit the reflected light, and make the probe light emitted by the light source 721 incident on the surface of the wafer w along a direction perpendicular to the surface of the wafer w after being reflected by the beam splitter 712, and the reflected light formed after being reflected on the surface of the wafer w passes through the beam splitter 712 along a direction perpendicular to the surface of the wafer w to be incident on the measurement module 722.
A second lens 714 is disposed in the optical path between the measurement module 722 and the beam splitter 712, and the second lens 714 is configured to focus the reflected light to the measurement module 722.
A third lens 713 is disposed on the optical path between the beam splitter 712 and the wafer w, and the third lens 713 is configured to focus the probe light onto the surface of the wafer w. The third lens 713 is coaxial with the probe light reflected by the beam splitter 712, so that the light emitted from the light source 721 is collimated into the probe light. The beam splitter 712 has a predetermined angle with the optical axis of the probe light so as to reflect the probe light to the surface of the wafer w, the predetermined angle being matched with the positional relationship between the beam splitter 712 and the surface of the wafer w.
In the present embodiment, the front value measurement controller 720 and the back value measurement controller 820 have the same structure and may include a light source 721, a spectrometer, a supporting circuit, such as a control circuit, a power supply, a clock circuit, a cache memory, etc., wherein the light source 721 is operable to emit white light with a wavelength of 300-1000nm, and a xenon lamp, a halogen lamp, a deuterium lamp, an LDLS, etc. may be used as the light source 721. The upper computer 900 may include a Central Processing Unit (CPU), a memory, a support circuit, and the like.
Specifically, taking the previous value measurement controller 720 as an example, the structure thereof will be briefly described:
as shown in fig. 8, the front value measurement controller 720 includes a light source 721, a measurement module 722 and an operation module 724, the front value measurement probe 710 is connected to the light source 721 and the measurement module 722 through an optical fiber 723, and preferably, the front value measurement probe 710, the light source 721 and the measurement module 722 are connected by a Y-shaped optical fiber, and the Y-shaped optical fiber includes a main optical fiber and two branch optical fibers led out from one end of the main optical fiber, which are a first branch optical fiber and a second branch optical fiber, respectively. The front value measurement probe 710 is connected to a main fiber, and the first and second branch fibers are connected to a light source 721 and a measurement module 722, respectively.
The probe light generated by the light source 721 may include a near infrared region in a wavelength range, and preferably low coherence light is generated as the probe light. The light source 721 is optically connected to the first branch optical fiber, and the probe light generated by the light source 721 is guided to the surface of the wafer w by the first branch optical fiber and is emitted to the surface of the wafer w by the front value measuring probe 710.
The measurement module 722 is optically connected to the second branch optical fiber, the probe light is reflected on the surface of the wafer w to generate reflected light, the reflected light enters the second branch optical fiber through the front value measurement probe 710, the reflected light is transmitted to the measurement module 722 by the second branch optical fiber, and the measurement module 722 outputs the wavelength intensity distribution of the reflected light as a detection result to the operation module 724.
The operation module 724 calculates the optical characteristics of the sample based on the detection result output from the measurement module 722. The operation module 724 may be implemented using a processor executing a program, or may be implemented using hardware devices such as a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), a system on a chip (SoC), or the like.
The operation module 724 is connected to the host computer 900 through the interface 725, and data exchange between the interface 725 and the host computer 900 may include measurement results of optical characteristics calculated by the operation module 724, or data and attribute information used in calculating a reflectance interference spectrum of a surface film layer of the wafer w may be exchanged. Interface 725 may use transmission media such as ethernet, wireless LAN, USB, etc.
The upper computer 900 calculates a reflection spectrum according to the wavelength intensity distribution included in the reflected light, performs wave number conversion on the reflection spectrum to obtain a wave number conversion reflection spectrum, performs fast fourier transform on the wave number conversion reflection spectrum based on discrete wave number data with uniform intervals, determines wave number spectrum power based on the discrete wave number data after the fast fourier transform, detects an optical film thickness based on a peak position appearing in the power spectrum, and divides the measured optical film thickness by a refractive index of a deposition layer on the surface of the wafer w to calculate a film thickness on the surface of the wafer w.
The upper computer 900 may calculate the film thickness in consideration of the wavelength dependence of the refractive index of the surface film layer of the wafer w. After calculating the reflection spectrum R (λ), the wave number K (λ) =2n (λ)/λ is calculated from the refractive index n (λ) of each wavelength, and then the wave number conversion reflectances R are calculated from the reflectances R of the respective wavelengths, respectively 1 Identical to R/(1-R). Reflection spectrum R by wave number conversion 1 (K) Calculating a power spectrum by performing a Fourier transform on a wave number K (lambda), which wave number transforms a reflection spectrum R 1 (K) Representing the calculated wave number K and wave number conversion reflectivity R of each wavelength 1 Is a relationship of (3). Detecting the optical film thickness based on the position of the peak appearing in the power spectrum, employing thisThe mode can accurately calculate the film thickness of each layer on the surface of the wafer w containing a plurality of deposition layers.
As shown in fig. 9, the measurement module 722 includes a slit 7221, a shutter 7222, a filter 7223, a collimator lens 7224, a diffraction grating 7225, a focusing lens 7226, and a light receiver 7227, which are arranged in this order in the optical path direction of the reflected light.
Wherein the slit 7221 is used to adjust the diameter of the spot 715 of the reflected light. The light shield 7222 shields the reflected light incident on the light receiver 7227. The filter 7223 is configured to filter wavelength components outside the measurement wavelength range included in the reflected light incident on the light receiver 7227, and can filter light of 400nm to 600nm, for example. In some embodiments, the filter 7223 may also be used to filter reflected light below 400nm wavelength to reduce damage to the wafer w dielectric layer from reflected light in this wavelength range.
The collimator lens 7224 converts light incident through the slit 7221 into parallel light after reflection, and guides the parallel light to the diffraction grating 7225. The diffraction grating 7225 separates the incident light according to the wavelength, guides the light to the light receiver 7227, and the diffracted waves at specific wavelength intervals are reflected by the diffraction grating 7225 in different directions and are irradiated to different light receiving elements.
The focusing mirror 7226 focuses the reflected light of the diffraction grating 7225 separated according to wavelength, and forms an image on the detection surface of the photodetector 7227. The light receiver 7227 receives the light separated in wavelength by the diffraction grating 7225, and the light receiver 7227 has a plurality of light receiving elements aligned, each of which outputs an electric signal of the intensity of each wavelength component included in the spectrum split by the diffraction grating 7225.
The present utility model can also perform in-situ detection on the wafer w before measuring the wafer w, and the in-situ detection in the previous value measurement process is described below as an example:
in the process of transmitting the wafer w, when the wafer w appears under the projection surface of the front value measuring probe 710, the front value measuring probe 710 receives the reflected light, the front value measuring controller 720 sets the state variable to 1 according to the received reflection spectrum or the reflectance greater than a certain threshold, and the upper computer 900 reads the state variable to 1 and instructs the controller to transmit the film thickness information of the wafer w and store the film thickness information. In this process, the robot 200 controls the wafer w to move at a constant speed, and the controller collects the film thickness information at a fixed time interval, so that the positional relationship between the measured thickness and the measured point on the wafer w can be obtained.
The current value measurement probe 710 cannot receive the reflected light, and the controller sets the state variable to 0 according to the received reflected light spectrum or the reflectance less than a certain threshold value, and the upper computer 900 reads the state variable to 0 and stops storing the thickness information of the wafer w.
The in-situ detection of the post-value measurement process is similar to the above process and will not be described again.
The above shows an alternative method for obtaining position information of the measuring point, namely, distinguishing by the magnitude of the reflection spectrum or the reflectivity. In addition, the position information of the measurement point can be obtained by reading the encoder information of the manipulator 200. Of course, the above are just a few of the location information acquisition manners provided by way of example, and the present embodiment does not exclude the use of other information acquisition schemes.
In connection with the above, the operation principle of the chemical mechanical polishing system provided in this embodiment will be briefly described:
during the chemical mechanical polishing operation, the robot 200 in the front end unit takes out the wafer w from the wafer box loaded in the wafer box and transmits the wafer w to the polishing unit 300, and the front value measuring unit 700 is located above the wafer w transmission path and measures the front value of the thickness of the wafer w in the wafer w transmission process, so as to obtain the relationship data of any position on the diameter of the wafer w and the thickness at the moment;
the wafer w is polished in the polishing unit 300, and after the polishing is finished, the robot 200 takes out the wafer w from the polishing unit 300, transfers it to the cleaning unit 400 and the drying unit 500 to be sequentially cleaned and dried, and then transfers it to the transfer unit 600; the robot 200 takes out the wafer w from the transferring unit 600, and the back value measuring unit 800 is located above the transferring path of the wafer w, and measures the back value of the thickness of the wafer w after the wafer w is transferred, so as to obtain the data of the relation between any position on the diameter of the wafer w and the thickness.
In the embodiment shown in fig. 10, there is exemplarily provided a polishing parameter control method, which specifically includes the steps of:
(1) Before the wafer w moves into the polishing unit 300, thickness information before polishing is measured;
(2) The wafer w is polished in the polishing unit 300 according to the process parameters given by the system;
(3) Measuring thickness information of the polished wafer w during the process of moving the wafer w out of the polishing unit 300;
(4) The process control system calculates the removal amount of each Zone area of the wafer w according to the actual deviation value of the front value film thickness data and the target value of each Zone area of the wafer w;
(5) The process control system calculates the removal amount of each Zone area of the wafer w under the set polishing time and polishing pressure according to the back value film thickness data of the wafer w;
(6) The process control system builds a corresponding process control model, such as pressure-polishing time-polishing pad 320 lifetime-removal rate, for each Zone based on the polishing process information; when the wafer w is moved into the polishing unit 300, the front value thickness information measured by the front value measuring unit 700 and the desired target value are input into the process control model to obtain polishing process parameters, and the wafer w is made to reach the desired value according to the set process parameters.
The applicant declares that the above is only a specific embodiment of the present utility model, but the scope of the present utility model is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present utility model disclosed by the present utility model fall within the scope of the present utility model and the disclosure.
Claims (10)
1. A chemical mechanical polishing system comprising:
a front unit in which a wafer is stored;
an apparatus main body for performing a polishing operation on a wafer;
the mechanical arm is used for interacting between the front unit and the equipment main body so as to transfer the wafer;
the front value measuring unit is used for measuring the thickness of the wafer before polishing in the wafer transmission process;
and the back value measuring unit is used for measuring the thickness of the polished wafer in the wafer transmission process.
2. The chemical mechanical polishing system of claim 1, wherein the apparatus body comprises a polishing unit, a cleaning unit, a drying unit, and a transfer unit, and wafers are transferred between the pre-unit, the polishing unit, the cleaning unit, the drying unit, and the transfer unit in sequence.
3. The cmp system of claim 2 wherein the robot is positioned between the pre-unit and the apparatus body for transporting wafers from the pre-unit to the polishing unit and for transporting wafers from the transfer unit back to the pre-unit.
4. The cmp system of any one of claims 1 to 3 wherein the front value measurement unit is located on a wafer transfer path between a wafer exit of the front unit and the apparatus body.
5. A chemical mechanical polishing system according to any one of claims 1 to 3, wherein the back value measurement unit is located on a wafer transfer path between the apparatus body and a wafer inlet of the front unit.
6. The chemical mechanical polishing system of any one of claims 1 to 3, wherein the front value measurement unit and the back value measurement unit are configured to emit probe light toward a wafer.
7. The cmp system of claim 6 wherein the robot arm moves the wafer at a constant speed, and the front and rear measurement units emit probe light to the wafer surface multiple times at fixed time intervals to obtain measurement values at different points of the wafer.
8. A chemical mechanical polishing system according to any one of claims 1 to 3, wherein the front value measuring unit and the rear value measuring unit are located in a plane where the diameter of the wafer is located and perpendicular to the wafer, and the probe light is irradiated perpendicularly to the surface of the wafer and moves in the diameter direction of the wafer as the wafer moves.
9. A chemical mechanical polishing system according to any one of claims 1 to 3, wherein the front value measurement unit comprises a front value measurement probe and a front value measurement controller connected thereto;
the back value measuring unit comprises a back value measuring probe and a back value measuring controller connected with the back value measuring probe.
10. The cmp system of claim 9 wherein the front value measurement controller and the back value measurement controller are each independently electrically connected to a host computer.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117589074A (en) * | 2024-01-18 | 2024-02-23 | 无锡卓海科技股份有限公司 | Film measuring device, method, electronic equipment and storage medium |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117589074A (en) * | 2024-01-18 | 2024-02-23 | 无锡卓海科技股份有限公司 | Film measuring device, method, electronic equipment and storage medium |
| CN117589074B (en) * | 2024-01-18 | 2024-04-23 | 无锡卓海科技股份有限公司 | Film measuring device, method, electronic equipment and storage medium |
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