TWI726847B - Method for fabricating substrate, and computer program product and integrated circuit fabrication system thereof - Google Patents

Abstract

A method of controlling polishing includes storing a base measurement, the base measurement being a measurement of a substrate after deposition of at least one layer on the substrate and before deposition of an outer layer over the at least one layer. After deposition of the outer layer and during polishing of the outer layer on the substrate, a sequence of raw measurements of the substrate during polishing are received from an in-situ monitoring system. Each raw measurement is normalized to generate a sequence of normalized measurements using the raw measurement and the base measurement. At least one of a polishing endpoint or an adjustment for a polishing rate is determined based on at least one normalized measurement from the sequence of normalized measurements.

Description

Method for manufacturing substrate, computer program product and integrated circuit manufacturing system

The present invention discloses a polishing control method such as during chemical mechanical polishing of a substrate.

Integrated circuits are usually formed on a substrate by continuous deposition of a conductive layer, a semiconductive layer, or an insulating layer on a silicon wafer. One manufacturing step includes depositing a filler layer on the uneven surface and planarizing the filler layer. For certain applications, the filler layer is planarized until the top surface of the patterned layer is exposed. For example, an oxide filler layer may be deposited on the patterned insulating layer to fill trenches or holes in the insulating layer. After planarization, the filler layer is planarized until a predetermined thickness is left over the uneven surface or the top surface of the lower layer is exposed. For other applications, the filler layer is planarized until the predetermined thickness remains above the patterned lower layer. In addition, the flattening of the substrate surface is often required for lithography.

Chemical mechanical polishing (CMP) is an accepted planarization method. This planarization method usually requires the substrate to be mounted on the carrier head. The exposed surface of the substrate is usually placed against the rotating polishing pad. The polishing head provides a controllable load on the substrate to push the substrate against the polishing pad. A polishing liquid (such as a slurry with adhesive particles) is usually supplied on the surface of the polishing pad.

One problem of CMP is to determine whether the polishing process is complete, such as whether the substrate layer has been planarized to the required flatness or thickness, or when the expected amount of material is removed. The initial thickness of the substrate layer, the composition of the slurry, Changes in the condition of the polishing pad, the relative speed between the polishing pad and the substrate, the thickness of each deposited layer, and the load on the substrate may cause changes in the material removal rate. These changes result in changes in the time required to reach the polishing endpoint. Therefore, it is impossible to determine the polishing end point only as a function of polishing time.

In some systems, during polishing, the substrate is subject to real-time optical monitoring, such as through the window of the polishing pad. However, the existing optical monitoring technology may not be able to meet the ever-increasing requirements of semiconductor component manufacturers.

In some optical monitoring processes, such as during the CMP polishing process, the real-time measured spectrum is compared with the reference spectrum database to find the best matching reference spectrum. The real-time measured spectrum may include multiple noise components that may distort the result, and there is an inaccurate comparison with the reference spectrum database. A significant noise component is the bottom layer change. That is, due to different processes, different material layers under the layer being polished may have substrate-to-substrate variations in refractive index and thickness.

Standardized methods that can deal with these problems include measuring the base spectrum of the substrate after depositing one or more dielectric layers but before depositing the outer layer to be polished. The measured base spectra are used to standardize the respective measured spectra obtained during the grinding, and the respective measured spectra obtained during the grinding can then be compared with the database of reference spectra to find the best matching reference spectra.

In one aspect, a computer program product tangibly embodied in a machine-readable storage device includes instructions to execute a method of controlling grinding. The method includes storing the base spectrum, which is a non-metal layer after the deposition of a plurality of deposited dielectric layers on a metal layer or a semiconductor wafer The spectrum of light reflected from a substrate before being deposited on a plurality of deposited dielectric layers. After the non-metallic layer is deposited on the plurality of deposited dielectric layers and during the polishing of the non-metallic layer on the substrate, the measurement of a series of original spectra of the light reflected from the substrate during the polishing is received from the real-time optical monitoring system. The original spectrum and the base spectrum are used to normalize each original spectrum in the series of original spectra to generate a series of normalized spectra. At least one of the polishing endpoint or the adjustment of the polishing rate is determined based on at least one standardized predetermined spectrum from the series of standardized spectra.

In another aspect, the method of manufacturing a substrate includes depositing at least one dielectric layer on a metal layer of the substrate or a semiconductor wafer. After depositing at least one dielectric layer but before depositing the outermost layer, an optical metrology system measures the base spectrum reflected from the substrate. The outermost layer is deposited on at least one dielectric layer, the outermost layer of the substrate is polished, and during the polishing of the outermost layer, the real-time optical monitoring system measures a series of original spectra reflected from the substrate. Use the original spectrum and the post-deposition base spectrum to normalize each original spectrum in the series of original spectra to generate a series of standardized spectra, and determine the grinding end point or the grinding rate based on at least one standardized predetermined spectrum from the series of standardized spectra At least one of the adjustments.

In another aspect, the integrated circuit manufacturing system includes a deposition system, a metering system, and a polishing system. The deposition system is configured to receive the substrate and deposit a stacked layer on the metal layer or semiconductor substrate, the stacked layer including a non-metal layer subjected to grinding and at least one dielectric layer under the non-metal layer. After depositing at least one dielectric layer and after depositing a non-metallic layer Previously, the metrology system was configured to produce a measurement of the spectrum of light reflected from the substrate. The polishing system is configured to receive the substrate and the non-metallic layer on the polishing substrate, and includes a controller that is configured to perform operations including: receiving the measurement of the light spectrum from the metering system and storing the measurement as a base The spectrum is measured by a series of original spectra of light reflected from the substrate during grinding with an instant optical monitoring system, the original spectra and the base spectra are used to normalize each original spectrum in the series of original spectra to generate a series of standardized spectra, and based on At least one standardized predetermined spectrum from the series of standardized spectra determines at least one of the polishing endpoint or the adjustment of the polishing rate.

In another aspect, the polishing system includes a carrier, a platform, a real-time optical monitoring system, and a controller. The carrier is configured to carry the substrate, wherein the substrate includes a stacked layer on a metal layer or a semiconductor substrate, and the stacked layer includes a non-metal layer subjected to grinding and a plurality of deposited media under the non-metal layer Electric layer. The platform accommodates the polishing pad, and the polishing pad is configured to be in contact with the substrate. The controller is configured to perform operations including: storing the post-deposition base spectra, the post-deposition base spectra being the spectrum of light reflected from the substrate after depositing a plurality of deposited dielectric layers and before depositing non-metallic layers; The real-time optical monitoring system receives the measurement of a series of original spectra of the light reflected from the substrate during grinding; uses the original spectra and post-deposition base spectra to standardize each of the original spectra in the series to generate a series of standardized spectra; and At least one standardized predetermined spectrum of the series of standardized spectra determines at least one of the polishing endpoint or the adjustment of the polishing rate.

In another aspect, a computer program product tangibly embodied in a machine-readable storage device includes instructions. When one or more computers execute the instructions, the instructions perform operations, including: receiving base measurements The base measurement is the eddy current measurement of the substrate after at least one layer is deposited on the semiconductor wafer and before the conductive layer is deposited on the at least one layer. After depositing the conductive layer on the at least one layer and during the grinding of the conductive layer on the substrate, a series of original measurements of the substrate are received from the instant eddy current monitoring system. The original measurement and the base measurement are used to standardize each original measurement in the series of original measurements to generate a series of standardized measurements, and at least one of the grinding end point or the adjustment to the grinding rate is determined based on at least the series of standardized measurements.

Implementations can optionally include one or more of the following advantages. The accuracy of determining the end points of the substrate can be improved by filtering noise from changes in the thickness and/or refractive index of the underlying deposited layer on the substrate. During the polishing, the thickness of the outermost material layer subjected to the polishing can be tracked by taking a spectral measurement of the substrate.

10: substrate

12: Base of the substrate

14: layer structure

16: first layer

18: second layer

20: layer

30: Outer gap packing layer

100: Grinding equipment

108: window

110: Grinding pad

112: Outer grinding layer

114: Softer back support layer

118: physical window

120: platform

121: Motor

124: drive shaft

125: axis

129: Rotary coupling

130: Port

132: Slurry

140: Carrying head

142: fixed ring

144: Elastic membrane

146a-146c: chamber

148a-148c: area

150: support structure

152: drive shaft

154: Carrying head rotation motor

155: Shaft

160: Instant optical monitoring system

162: light source

164: Light Detector

166: Circuit

170: bifurcated fiber

190: Controller

201: Location

201a-201k: points

204: Arrow

210: Index track

212: index value

214: Line

502: The initial stage of the substrate

504: Post-sedimentation stage

506: final post-grinding stage

510: after deposition

512: Post-etch substrate

514: Pre-gap fill substrate

802: step

804: step

806: step

808: step

810: step

812: step

814: step

816: step

900: Manufacturing equipment

902: Deposition System

904: Embedded Metering System

906: Metering System

908: Etching System

910: Embedded metering system

912: Grinding System

914: Real-time metering system

916: Controller

Figures 1A-1E are schematic cross-sectional views of an exemplary substrate before, during, and after polishing.

Figure 2 shows a schematic cross-sectional view of an example of the polishing equipment.

Figure 3 shows a schematic top view of a substrate with multiple regions.

Figure 4 shows the top view of the polishing pad and shows the position captured on the substrate by real-time measurement.

Figure 5 shows the different stages of manufacturing the demonstration substrate. The post-deposition base spectra can be measured at these different stages.

Figure 6 shows a series of values derived from the measured spectra.

Figure 7 shows a linear function that fits the series of values.

Figure 8 is a flow chart of an exemplary process for manufacturing substrates and detecting polishing endpoints.

Figure 9 is a schematic diagram of the manufacturing equipment.

The same numbers and codes in different drawings represent the same components.

The substrate may include a stacked layer on the metal layer or the semiconductor substrate, the stacked layer including the outermost layer subjected to grinding and a plurality of deposited layers under the outermost layer. In some implementations, the outermost layer is a non-metallic layer. As an example, the entire reference is made to a substrate with alternating layers of dielectric materials, such as a 3D NAND structure. It should be understood that other substrates can be used, and the substrate described in Figure 1 is an example.

As an example, referring to the substrate 10 in FIG. 1A, the substrate base 12 (such as a glass sheet or a semiconductor wafer) optionally includes an intermediate layer structure 14, which may include one or more patterned or non-patterned metal layers , Oxide layer, nitride layer or polysilicon layer.

At least one additional dielectric layer is deposited between the intermediate layer structure 14 (or the substrate base 12 if there is no intermediate layer structure) and the outermost layer. In some implementations, the at least one additional dielectric layer is a single layer. In some implementations, the at least one dielectric layer includes deposited on the layer structure 14 (e.g., in the conductive Multiple alternating layers on electrical materials. The alternating layers alternate between the first layer of material 16 and the second layer of material 18. For example, the first layer 16 (such as oxide or nitride) is deposited on the conductive layer 14. A second layer 18 (such as nitride or oxide) is deposited on the first layer. For example, the first dielectric layer may be silicon oxide, and the second dielectric layer may be silicon nitride. The deposition is repeated one or more times to produce alternating layers of material. In addition, the first layer 16 or the second layer 18 may be polysilicon instead of dielectric.

FIG. 1B shows the substrate 10 after the etching process has been performed. The substrate 10 has been etched to produce a stepped structure, such as the substrate has been patterned or etched according to a pattern. Patterning may include applying photoresist to the substrate 10, as described in FIG. 1A, which defines a structure after etching, such as a stepped structure. After etching, if the photoresist has been used to pattern the substrate, the plasma ashing process can remove the remaining photoresist on the substrate 10.

FIG. 1C shows the substrate 10 after the layer 20 is deposited on the stepped structure. The layer 20 can be a nitride, such as silicon nitride. According to the substrate 10, the nitride layer 20 can be used as an insulator, a barrier layer, or a charge trap in a 3D NAND flash memory structure.

Figure 1D shows the substrate 10 after the outer gap filler layer 30 is deposited. The outer gap filler layer 30 is thick enough to fill the grooves (such as the grooves left by the stepped structure). The outer gap filler layer 30 is a non-metallic layer, such as oxide. For example, layer 30 can be silicon oxide. FIG. 1E shows the substrate 10 after the chemical mechanical planarization process has been performed. Chemical mechanical polishing can be used to planarize the substrate until the nitride layer 20 is exposed.

FIG. 2 shows an example of the polishing device 100. The polishing equipment 100 includes a rotatable dish-shaped platform 120, and the polishing pad 110 is located on the dish-shaped platform. 120 on. The platform is operable to rotate about the axis 125. For example, the motor 121 can rotate the drive shaft 124 to rotate the platform 120. The polishing pad 110 may be a two-layer polishing pad having an outer polishing layer 112 and a softer backing layer 114.

The polishing apparatus 100 may include a port 130 to distribute the polishing liquid 132 (such as a polishing slurry) on the polishing pad 110 to the pad. The polishing equipment may also include a polishing pad adjuster to polish the polishing pad 110 to maintain the polishing pad 110 in a consistent polishing state.

The polishing apparatus 100 includes one or more carrier heads 140. Each carrier head 140 can operably clamp the substrate 10 against the polishing pad 110. Each carrier head 140 may have independent control of polishing parameters associated with each individual substrate, such as pressure.

In particular, each carrier head 140 may include a fixing ring 142 to fix the substrate 10 under the elastic film 144. Each carrier head 140 also includes a plurality of independently controllable pressurized chambers (such as three chambers 146a-146c) defined by the membrane, which can apply independently controllable pressure to the associated elastic membrane 144 The regions 148a-148c and therefore are applied to the substrate 10 (see Figure 3). Referring to Fig. 3, the central area 148a may be substantially circular, and the remaining areas 148b-148c may be concentric annular areas around the central area 148a. Although only three chambers are shown in Figures 2 and 3 for brief description, there may be one or two chambers, or four or more chambers, such as five chambers.

Returning to FIG. 2, each carrying head 140 is suspended from a supporting structure 150 (such as a rotating material rack or a rail), and is connected to the carrying head rotation motor 154 via a driving shaft 152 so that the carrying head can rotate around the shaft 155. Each bearing head 140 can selectively oscillate sideways, such as on a slider on the rotating material rack 150; by the oscillation of the rotating material rack itself, or by movement along the track. In operation, the platform rotates around its central axis 125, and each carrier head rotates around its central axis 155 and moves laterally across the top surface of the polishing pad.

Although only one carrier head 140 is shown, more carrier heads can be provided to hold additional substrates so that the surface area of the polishing pad 110 can be effectively used. Therefore, a plurality of carrier head assemblies adjusted to hold the substrate for simultaneous polishing processing can stand (at least partially) based on the surface area of the polishing pad 110.

The polishing equipment may also include a real-time optical monitoring system 160, such as a spectroscopic camera monitoring system, which can be used for endpoint detection or to determine whether to adjust the polishing rate or adjust the polishing rate as described below. Optical access through the polishing pad is provided by including a hole (ie, a hole through the pad) or a solid window 118.

The optical monitoring system 160 may include a light source 162, a light detector 164, and a circuit 166. The circuit 166 is used to transmit and receive signals between the controller 190 (such as a computer) and the light source 162 and the light detector 164. One or more optical fibers (such as the bifurcated optical fiber 170) can be used to transmit light from the light source 162 to the optical connection in the polishing pad, and to transmit the light reflected by the substrate 10 to the detector 164.

The output of the circuit 166 can be a digital electronic signal transmitted through the rotary coupling 129 (such as a slip ring) in the drive shaft 124 to the controller 190 for the optical monitoring system. Similarly, the light source can be turned on or off in response to the transmission from the controller 190 through the rotary coupling 129 to the optical monitoring system Control commands in the digital electronic signal of the system 160. Alternatively, the circuit 166 may communicate with the controller 190 through wireless signals.

The light source 162 may be operable to emit white light. In one implementation, the emitted white light includes light having a wavelength of 200-800 nanometers. Suitable light sources are xenon lamps or xenon mercury lamps. In certain other implementations, the emitted light includes light having a wavelength in the near-infrared spectrum, such as 800-1400 nanometers.

The light detector 164 may be a spectrometer. A spectrometer is an optical instrument used to measure the light intensity on the electromagnetic spectrum. A suitable spectrometer is a grating spectrometer. The typical output for a spectrometer is the intensity of light as a function of wavelength (or frequency).

As described above, the light source 162 and the light detector 164 can be connected to a computing device, such as the controller 190. The computing device can operatively control the operation of the light source 162 and the light detector 164 and receive the light source 162 and the light detector 164 Signal. The computing device may include a microprocessor located near the grinding equipment, such as a programmable computer. With respect to control, for example, the computing device may synchronize the activation of the light source with the rotation of the platform 120.

In some implementations, the light source 162 and the detector 164 of the real-time monitoring system 160 are installed in the platform 120 and rotate together with the platform 120. In this case, the movement of the platform will cause the sensor to scan across the substrates. Specifically, when the platform 120 rotates, the controller 190 will cause the light source 162 to emit a series of flashes when the light connection just starts to be transmitted under the substrate 10 and when the light connection just ends to be transmitted under the substrate 10. Alternatively, the computing device may cause the light source 162 to continuously emit light when each substrate 10 has just begun to transmit optical access and each substrate 10 has just passed the optical access. Love here In other cases, the signal from the detector can be combined in the sampling period to produce a spectrum measurement at a sampling frequency.

In operation, for example, the controller 190 may receive a signal carrying information describing the spectrum of light received by the photodetector for the flash of a specific light source or the period of the detector. Therefore, this spectrum is the spectrum measured immediately during grinding.

As shown in Figure 4, if the detector is installed in the platform, due to the rotation of the platform (as indicated by arrow 204), when the window 108 moves under the carrying head, an optical monitoring system for optical measurement generated at a sampling frequency This will cause the spectrum measurement to be captured at position 201 which is located on the arc passing through the substrate 10. For example, each of the points 201a-201k represents the position of the spectrum measurement measured by the monitoring system (the number of the points is exemplary; more or less points can be captured according to the sampling frequency). The sampling frequency can be selected so that five to twenty spectra are acquired every time the window 108 is swept. For example, the sampling period can be between 3 and 100 milliseconds (millisecond).

As shown in the figure, after one rotation of the platform, spectra are obtained from different radii on the substrate 10. That is, some spectra are obtained closer to the center of the substrate 10 and some spectra are obtained closer to the edge. Therefore, for any given scan of the optical monitoring system across the substrate, based on time, motor coding information, and optical detection of the substrate edge and/or fixed ring, the controller 190 can calculate the radial position (relative At the center of the scanned substrate). The polishing system may also include a rotating position sensor, such as a flange attached to the edge of the platform through a fixed optical blocker, to provide additional information for determining which spectrum to measure on the substrate and the position on the substrate. Therefore, the controller can associate the respective measured spectra to the controllable areas 148b-148e on the substrates 10a and 10b (see Figure 2). In some implementations, the time of the spectral measurement can be used as a substitute for the exact calculation of the radial position.

After the rotation of multiple platforms in each area, a series of spectra over time can be obtained. Not limited to any specific theory, due to the change in the thickness of the outermost layer, as the grinding progresses (such as ending multiple rotations of the platform, rather than a single scanning period across the substrate), the spectrum of the light reflected from the substrate 10 develops, resulting in a The time-varying spectrum of the series. In addition, the specific thickness of the layer stack exhibits a specific spectrum.

In some implementations, a controller (such as a computing device) can be programmed to receive the base spectra of the substrate 10 after deposition but before polishing, and to normalize a series of measured spectra from each region. The controller can then be programmed to compare each standardized spectrum of the series of standardized measurement spectra from each region with multiple reference spectra to generate a series of best-matched reference spectra for each region.

As used in this specification, the reference spectrum is a predefined spectrum generated before polishing the substrate. The reference spectrum may have a predefined correlation (ie, defined before the polishing operation) related to a value representing the polishing process time. Assuming that the actual polishing rate follows the expected polishing rate, the spectrum is expected to appear at that time. Or or even more, the reference spectrum may have a predefined correlation with the value of the substrate property, such as the thickness of the outermost layer, such as the layer to be polished.

The reference spectrum can be generated empirically, such as by measuring the light from a test substrate (such as a test substrate including a deposited layer with a known layer thickness) Spectrum. For example, in order to generate a plurality of reference spectra, the arranged substrate is polished using the same polishing parameters as the polishing parameters that will be used during the polishing of the component wafer, while simultaneously collecting a series of spectra. For each spectrum, record the value representing the time the spectrum was collected during the grinding process. For example, the value can be the elapsed time, or the number of platform rotations.

In addition to empirical decisions, part or all of the reference spectrum can be calculated theoretically, such as using the optical mode of the substrate layer. For example, the optical mode can be used to calculate a reference spectrum for a given substrate that includes a deposited layer of a known thickness and a given outer layer thickness D. A value representing the grinding process time can be calculated, and the reference spectrum can be collected at this time, such as by assuming that the outer layer is removed at a uniform grinding rate.

The measured spectra of the substrate subjected to the polishing can be compared with reference spectra from one or more databases.

In some implementations, each reference spectrum is assigned an index value. Generally speaking, each database may include a large number of reference spectra 320, such as one or more (such as exactly one) reference spectra for each platform rotation after the expected grinding time of the substrate. This index can be a value (such as a number) representing the grinding treatment time, at which the reference spectrum is expected to be observed. The spectrum can be indexed so that each spectrum in a particular database has a unique index value. The index can be implemented so that the index values are sorted according to the order in which the test substrate spectrum is measured. You can choose the index value to change monotonously as the grinding progresses, such as increasing or decreasing. Specifically, the index value of the reference spectrum can be selected so that the index value forms a linear function of time or the number of platform rotations (assuming that the grinding rate follows the pattern used to generate the reference spectrum of the database or the test substrate The grinding rate). For example, the index value can be directly proportional to (e.g., equal to) the number of platform rotations, with which the reference spectrum is measured for testing the substrate or appearing in the optical mode. Therefore, each index value can be an integer. The index number can represent the expected platform rotation, and the associated spectrum appears with the expected platform rotation.

The reference spectrum and its associated index value can be stored in the reference spectrum database. For example, each reference spectrum and its associated index value can be stored in a database record. The database of the reference library of the reference spectrum can be implemented in the memory of the computing device of the polishing equipment.

As described above, for each area of each substrate, based on the series of measurement spectra or the area and the substrate, the controller 190 can be programmed to generate a series of best matching spectra. The best matching reference spectrum can be determined by comparing the measured spectrum obtained during grinding with the reference spectrum from a specific database.

Use the post-deposition base spectra from the substrate measurement to normalize the measured raw spectra. After obtaining the deposited base spectrum, refer to Fig. 5 as described below. The base spectrum can be obtained before polishing the substrate. Specifically, the base spectrum can be measured after one or more dielectric layers are deposited on the substrate but before the layer to be polished is deposited. The base spectra can be measured after the alternate oxidation and nitridation layers of the entire stack have been deposited. For example, the alternate layer of the stack may be an ONON stack (ie, alternate oxidized and nitrided layers of the stack) deposited in the resulting 3D NAND memory. In some implementations, the base spectra are measured before the substrate is etched (e.g., before the stepped structure is created). In some implementations, after etching the substrate However, the base spectrum is measured before the intermediate layer (such as the nitride layer) is deposited. In some implementations, the base spectra are measured after the intermediate layer is deposited but before the filler layer (such as an oxide layer thick enough to fill the etched hole) is deposited. After normalizing the original spectra, then comparing the normalized spectra with the reference spectra to determine the best match, for example, by calculating the sum of square differences, cross-correlation coefficients, or the like.

The base spectrum can be measured at a stand-alone metering station (such as a system from Nova Measuring Instruments or Nanometrics) or an in-line metering station. The embedded metering station is integrated to perform the deposition or etching as described in Figure 5. Process deposition or etching system.

Normalization can include division operations, where the original spectrum is in the numerator and the base spectrum is in the denominator. The base spectrum can be the spectrum of light reflected from the multiple dielectric layers and the bottommost material that light is expected to reach. The base spectrum is measured as described above with reference to three processing points, such as after depositing the layer stack, after etching, and after depositing the intermediate layer.

The measured spectrum can be standardized as follows: R=(A-DA)/(B-DB) where R is the normalized spectrum, A is the original spectrum, DA and DB are dark spectra obtained under dark conditions, and B is the base spectrum. The dark spectrum is the spectrum measured by the real-time optical monitoring system when no substrate is measured by the real-time optical monitoring system. In some implementations, DA and DB have the same spectrum. In some implementations, DA is the dark spectrum collected when the original spectrum is collected (such as rotating on the same platform), and DB is the dark spectrum collected when the original spectrum is collected (such as rotating on the same platform).

Figure 5 shows the different stages of manufacturing. The post-deposition base spectra can be measured at these different stages. FIG. 5 shows the exemplary substrate 502 in different manufacturing stages, from the initial stage 502 to the post-deposition stage 504 (such as the substrate 502 with a layer of deposited dielectric material) and to the final post-grinding stage 506. In order to obtain the post-deposition base spectrum (such as the spectrum of the substrate in the post-deposition stage (ie, stage 504 and after)), the spectrum can be measured by an optical monitoring system. As described above, the post-deposition base spectrum can also be used to post-etch the substrate 512 (e.g., the substrate after the material is removed from one or more layers deposited on the substrate (e.g., the material removed from the substrate after the deposition 510)) Spectra obtained. In addition, the post-deposition base spectra can be applied from a pre gap fill substrate 514 (a pre gap fill substrate 514), which once had a material layer after etching 512 (such as a nitride deposition layer) but before depositing a gap filler layer (such as a thick oxide layer). On the substrate).

Referring now to FIG. 6, FIG. 6 shows the result of only a single area of a single substrate. The index value of each of the best matching spectra in the series can be determined to generate the index value 212 of the time-varying series. This series of index values may be referred to as an index track 210. In some implementations, the index trajectory is generated by comparing each standardized measured spectrum (eg, the post-deposition base spectrum standardized to the measurement) with a reference spectrum from an exact database. Generally speaking, the index track 210 may include one (exactly one) index value for each scan of the under-substrate optical monitoring system.

For a given index track 210, where multiple spectra are measured and standardized, for a specific area in a single scan of the optical monitoring system (called the "current spectrum"), the best match can be determined by the current standard Between each of the measured spectra and one or more (such as exactly one) reference spectra in the database. In some implementations, each selected current spectrum is compared with each reference spectrum of the selected library or libraries. Or, in some implementations, the current spectrum can be combined (for example, averaged), and the combined spectrum of the comparison result and the reference spectrum can be combined to determine the best match and the index value.

In summary, each index trajectory includes a series of 210 index values 212, wherein each specific index value 212 of the series is generated by selecting a reference spectrum index from a given database, and the given database most conforms to the standardized measurement spectrum. The time value of each index for the index track 210 may be the same as the time measured by the standardized measurement spectrum.

As shown in Figure 7, a function (such as a polynomial function of known degree, such as a linear function (such as line 214)) conforms to the spectral index value of the series (such as using robust line fitting). Other functions (such as quadratic polynomial functions) can be used, but line functions (line) provide simple calculations. The grinding can be stopped at the endpoint time TE, and the line 214 intersects the target index IT at TE.

Figure 8 shows a flow chart of the method of manufacturing and polishing a product substrate. When the test substrate is used to generate the reference spectrum of the database, the product substrate may have at least the same layer structure and the same pattern. In some implementations, the method of FIG. 8 can be performed using the manufacturing equipment described below with reference to FIG. 9. Figure 8 illustrates the method of manufacturing and polishing an exemplary substrate (such as a 3D NAND structure). However, it should be understood that steps 804 and steps 808-816 can be applied to any suitable substrates.

FIG. 9 is a schematic diagram of the manufacturing equipment 900. The manufacturing equipment 900 includes a deposition system 902, such as a chemical vapor deposition system or a plasma enhanced chemical vapor deposition system, and optionally includes an embedded metering system 904. In some implementations, the manufacturing facility 900 may include a stand-alone metering system 906.

The manufacturing equipment 900 further includes an etching system 908, which can receive a substrate, pattern the substrate, and perform an etching process. The etching system 908 may include an embedded metrology system 910.

In addition, the manufacturing equipment 900 includes a grinding system 912 that can receive the substrate and grind (remove) the outer layer of material on the substrate. The polishing system 912 is configured with an instant optical metrology system 914 and a controller 916 configured to perform operations.

The layer 26 of the material is based on the substrate (step 802). As described above, referring to FIGS. 1A and 5, the substrate base 12 (such as a glass sheet or a semiconductor wafer) may include a conductive layer 14 disposed on the substrate base, such as a metal such as copper, tungsten, or aluminum.

The substrate is transferred to the deposition system 902. In some implementations, the deposition system 902 is used to deposit alternating layers (such as alternating the first layer of material and the second layer of material) on the substrate, or in some implementations on the conductive layer 14. For example, the first dielectric layer 16 (such as oxide or nitride) is deposited on the conductive layer, and the second dielectric layer (such as oxide or nitride) is deposited on the first layer. For example, the first dielectric layer may be silicon oxide, and the second dielectric layer may be silicon nitride. The deposition is repeated one or more times to produce a stack of alternating layers of material. As described above with reference to Figure 1, one of the layers (such as the first layer material or the second layer material) may be polysilicon.

The spectrum reflected from the substrate can be measured at this point in the manufacturing process and stored as a post-deposition base spectrum, as described in step 804. The substrate can be measured by the embedded metering system 904 in the deposition system 902 or by the independent metering system 906.

Next, the substrate is patterned and etched, for example, to produce a stepped structure. In order to perform etching, the substrate may be transferred to the etching system 908. After removing any remaining photoresist, the spectrum reflected from the substrate can be alternately measured at this point in the manufacturing process and stored as a post-deposition base spectrum. The substrate can be measured by the embedded metering system 910 in the etching system 908 or by the independent metering system 906.

Next, an intermediate layer (such as the nitride layer 20 in Figure 1, such as silicon nitride) is deposited on the alternating layer material with etched holes. The deposition of the intermediate layer can be performed by the same deposition system 902 that deposits alternating layers of the stack or by different deposition systems. The spectrum reflected from the substrate can be alternately measured at this point in the manufacturing process (before depositing the outer gap filler layer 30) and stored as a post-deposition base spectrum. The substrate can be measured by an embedded metering system (such as the embedded metering system 904 in the deposition system 902) or by a stand-alone metering system 906.

Therefore, after deposition but before polishing and before depositing the layer to be polished, the product substrate is measured (step 804). The spectrum reflected from the product substrate is measured for use in the standardized measurement spectrum during grinding, as described below. Measure the product substrate to obtain the post-deposition base spectrum, Such as the substrate spectrum in the post-deposition stage is used to standardize the original spectrum measured during grinding. The post-deposition base spectra can be measured from the spectra of the product substrate after deposition and before etching. The post-deposition base spectrum can also be measured after etching, for example, after the material is removed from one or more layers deposited on the product substrate to create a stepped structure. In addition, the post-deposition base spectrum can be measured after etching and depositing the nitride layer on the product substrate but before polishing.

An outer gap filler layer (such as a thick oxide) is deposited on the substrate after the base spectrum is deposited after the measurement (step 806). The deposition of the intermediate layer can be performed by the same deposition system 902 for depositing alternating layers of the stack and/or the same deposition system 902 for depositing the intermediate layer or by different deposition systems.

The product substrate is ground to remove the gap filler layer (step 808). For example, a polishing pad may be used in the polishing system 912 (such as the polishing device described in FIG. 2) to polish and remove the gap filler layer. Of course, steps 802-806 can be performed elsewhere, so that the processing for a specific operator of the grinding system 912 starts with step 808.

The real-time measurement system 914 is used to detect (using the above-mentioned real-time monitoring system 914) the spectrum of the product substrate measured during grinding (step 810).

The controller 916 in the polishing system 912 uses the measured post-deposition base spectrum to normalize the measured spectrum (step 812), as discussed above. In some implementations, the function (such as a linear function) corresponds to the index value of the series of spectra collected after time TC, and the clearance of the gap filler layer is detected at time TC.

The standardized measured spectra are analyzed to generate a series of index values, and a function conforms to the series of index values. Specifically, for each measured spectrum in the series of measured spectra, the index value of the most consistent reference spectrum is determined to generate the index value of the series (step 814). That is, the measured standardized spectrum is analyzed to generate a series of index values, and a function conforms to the series of index values.

Once the index value (for example, the calculated index value generated from the linear function corresponding to the index value of the new series) reaches the target index, the grinding can be stopped (step 816). The target thickness IT can be set and stored by the user before the grinding operation. Alternatively, the user can set the target amount to be removed, and can calculate the target index IT from the target amount to be removed.

After detecting the removal of the outermost layer (such as the gap filler layer) to adjust the polishing parameters (such as adjusting the polishing rate of one or more areas on the substrate to improve the polishing uniformity), the function is used to match the index value from the collected spectrum. It is possible.

In some implementations, index trajectories can be generated for each region. In addition to or as an alternative to detecting the grinding end point, the index trajectory can be used to calculate the adjustment of the grinding parameters, which will adjust the grinding rate for one or more areas to improve the grinding uniformity, such as US Patent Application No. 13/ According to 094,677, different areas can reach their more similar target thickness to reduce grinding.

Although the above discussion assumes a rotating platform with an optical endpoint monitor in the mounting platform, the system can be applied to other types of relative motion between the monitoring system and the substrate. For example, in some implementations such as track Movement, the light source moves across the substrate in different positions, but does not pass through the edge of the substrate. In such cases, the collected spectra can be divided into groups. For example, the spectra can be collected at a specific frequency, and the spectra collected in a time period can be regarded as part of a group. The time period should be long enough to collect five to twenty spectra for each group.

In addition, although the above discussion focused on the use of base spectra for standardization, the base spectra can be used in other applications. As a first example, not used for standardization, the base spectrum can be used as a reference spectrum during the grinding process.

As a second example, the position of the peak or valley in the base spectrum can be determined. This data can be used to adjust the target of the spectral feature tracking algorithm. For example, the algorithm described in U.S. Patent No. 7,998,358 can be adjusted by modifying the target position by an amount based on the positions of peaks or valleys in the base spectrum, which is incorporated herein by reference.

As a third example, without division, the base spectrum can be subtracted from the measured spectrum.

As a fourth example, one of various stored endpoint algorithms can be automatically selected by the controller based on the base spectrum. For example, before grinding, the base spectrum can be compared with a plurality of spectra, and the best matching spectrum can be identified. Each of the plurality of spectra may have an associated algorithm type, such as Fourier transform, spectral feature tracking, difference tracking with respect to a reference spectrum, or identification of matching reference spectra from a database. After the controller determines which spectrum is the best match, the controller can automatically select the endpoint algorithm associated with that spectrum.

In addition, although the above discussion focuses on the standardization of the spectrum measured during the polishing of the dielectric layer, the method can also be applied to the standardization of the eddy current measurement during the polishing of the conductive layer. In this case, the outermost layer is a conductive layer, such as metal, such as copper. An eddy current monitoring system (such as US Patent Publication No. US 2012/0276661) replaces the optical monitoring system and is used to monitor the substrate during grinding. Stand-alone or embedded eddy current metering devices are used to produce base measurements of the substrate after the conductive layer is deposited on the semiconductor wafer but before the outermost conductive layer is deposited. Eddy current measurement can be standardized as follows: R=(A-DA)/(B-DB) where R is the standardized measurement, A is the original measurement during grinding, and DA and DB are the instant eddy current when the sensor is not under the substrate. The measurement produced by the monitoring system, and the base measurement produced by the B system before the deposition of the outer conductive outermost layer.

As used in this specification, the term substrate may include, for example, a product substrate (for example, it includes a plurality of memory or processor modules), a test substrate, and a gate substrate. The term substrate can include circular discs and rectangular sheets.

The embodiments of the present invention and all function operations described in this specification can be implemented in digital electronic circuits, computer software, firmware or hardware, including the structural components disclosed in this specification and their structural equivalents, or a combination of the above. The embodiments of the present invention can be implemented as one or more computer program products (that is, one or more computer programs tangibly embodied in a machine-readable storage medium) for use by data processing equipment (such as programmable Processor), a computer or multiple processors or computers, or control data processing equipment, computers, or operations performed by multiple processors or computers. Computer programs (also called programs, software, software applications or codes) can be in any form of programming language Written, including compilation or interpretation languages, and computer programs can be deployed in any form, including stand-alone programs or as modules, components, subprograms, or other units suitable for use in a computing environment. The computer program does not have to correspond to the file. Programs can be stored in the part of the file that saves other programs or data, in a single file of the program used for discussion, or in a multi-person collaborative file (such as a part of one or more modules, subprograms, or codes) Of the file). Computer programs can be deployed and executed on one computer or on one site or distributed across multiple sites and on multiple computers connected by a communication network. The processing and logic flow described in this specification can be executed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processing and logic flow can also be executed by specific-purpose logic circuits (such as FPGA (field programmable gate array) or ASIC (application-specific integrated circuit)), and the device can also be implemented as a specific-purpose logic circuit (such as FPGA or ASIC).

The above-mentioned grinding equipment and method can be applied to various grinding systems. Either the polishing pad, the carrier head, or both can move to provide relative movement between the polishing surface and the substrate. For example, the platform can orbit rather than rotate. The polishing pad can be a round (or some other shape) pad fixed to the platform. Certain aspects of the endpoint detection system can be applied to linear grinding systems, such as a belt that moves continuously or linearly from reel to reel. The abrasive layer may be a standard (for example, polyurethane with or without filler) abrasive material, soft material or fixed abrasive material. Use relative positioning terms; it should be understood that the grinding surface and the substrate can be clamped in a vertical direction or some other direction.

Specific embodiments of the invention have been described. Other embodiments are within the scope of the following patent applications.

502‧‧‧The initial stage of the substrate

504‧‧‧Post-sedimentary stage

506‧‧‧The final post-grinding stage

510‧‧‧After deposition

512‧‧‧After etching the substrate

514‧‧‧Pre-gap filling substrate

Claims (28)

A computer program product encoded on one or more non-transitory computer storage media. The computer program product includes instructions. When one or more computers execute the instructions, the instructions cause the one or more A computer-executed operation includes the following steps: storing a base measurement after the at least one patterned layer is deposited on a semiconductor wafer and before an outer layer is deposited on the at least one layer of a product substrate For a measurement, the base measurement is an eddy current measurement or a base spectroscopy measurement; after the outer layer is deposited on the at least one layer and during the grinding of the outer layer on the substrate, a series of the real-time monitoring system is received. The original measurement of the substrate; the original measurement and the base measurement are used to standardize each of the original measurements in the series of original measurements to generate a series of standardized measurements; and based on at least the series of standardized measurements to determine a polishing end point or for a polishing At least one of an adjustment of the rate. The computer program product according to claim 1, wherein the outer layer is a conductive layer and the real-time monitoring system includes a real-time eddy current monitoring system. The computer program product of claim 2, wherein the base measurement includes after the deposition of the at least one layer but before the etching of the at least one layer, after the etching of the at least one layer but a barrier layer The measurement of one of the substrates before the deposition of the barrier layer, or after the deposition of the barrier layer but before the deposition of the conductive layer. The computer program product according to claim 1, wherein the outer layer is a non-metallic layer and the real-time monitoring system includes a real-time optical monitoring system. The computer program product according to claim 4, wherein the base measurement is a base spectrum, the base spectrum is a plurality of deposited dielectric layers deposited after overlapping a metal layer or a semiconductor wafer, and the non-metal layer is deposited on the A spectrum of light previously reflected from a substrate on a plurality of deposited dielectric layers, and the series of original measurements include a series of original spectra of light reflected from the substrate during grinding. The computer program product according to claim 5, wherein the base spectrum includes after the deposition of the dielectric layers but before an etching process, after the etching process but before the deposition of a nitride layer, or after the nitride layer is deposited but One of the spectra of the substrate measured before depositing the non-metallic layer undergoing grinding. The computer program product of claim 1, wherein the standardization includes a division operation, wherein the original measurement is a numerator and the base measurement is a denominator. The computer program product according to claim 7, wherein the division operation calculates a standardized measurement R that satisfies

Wherein A is the original measurement, B is the base measurement, and when no substrate is being measured by the real-time monitoring system, the measurements generated by the real-time monitoring system are D _A and D _B. The computer program product according to claim 1, wherein the operations further include generating a series of values from the series of measurements, matching a function to the series of values, and determining a predicted time for the function to reach a target value, and At least one of a polishing endpoint or an adjustment to a polishing rate is determined based on the predicted time. The computer program product according to claim 9, wherein the operations further include stopping the grinding when the function matches or exceeds a target value. The computer program product according to claim 1, wherein the step of grinding the substrate includes a rear end part of a production line of an integrated circuit manufacturing process. A method of manufacturing a product substrate, comprising the following steps: depositing at least one layer on a semiconductor wafer; generating a base measurement of the substrate, the base measurement is after the at least one patterned layer is deposited and an outer layer is deposited on the at least One of the previous measurements of the substrate on a layer; the outer layer is deposited on the at least one layer; the outer layer of the substrate is ground; during the grinding of the outer layer, a real-time monitoring system is used to generate the A series of original measurements; use the original measurement and the base measurement to standardize each original measurement in the series of original measurements to produce a series of standardized measurements; and determine a grinding based on at least one standardized predetermined spectrum from the series of standardized measurements At least one of an end point or an adjustment to a polishing rate. The method according to claim 12, wherein the outer layer is a conductive layer and the real-time monitoring system includes a real-time eddy current monitoring system. The method according to claim 13, wherein the at least one layer includes at least one underlying conductive layer and at least one dielectric layer on the semiconductor wafer. The method according to claim 14, wherein the base measurement is a measurement on one of the substrates after depositing a plurality of alternating layers on the substrate but before etching the substrate. The method of claim 15, wherein the plurality of alternating layers include polysilicon and silicon oxide. The method according to claim 13, wherein the base measurement is a measurement made after etching the substrate but before depositing a barrier layer. The method of claim 13, wherein the base measurement is a measurement made after depositing a barrier layer but before depositing the conductive layer. The method according to claim 12, wherein the outer layer is a The non-metallic layer and the real-time monitoring system include an optical monitoring system. The method according to claim 19, wherein the base measurement is a base spectrum, the base spectrum is a plurality of deposited dielectric layers deposited after overlapping a metal layer or a semiconductor wafer, and the non-metal layer is deposited on the plurality of A spectrum of light previously reflected from a substrate on the deposited dielectric layer, and the series of original measurements include a series of original spectra of light reflected from the substrate during grinding. The method according to claim 20, comprising the following steps: depositing alternating non-metallic layers on a substrate, the alternating non-metallic layers including the at least one dielectric layer; etching the substrate to produce a stepped structure; depositing an intermediate Layer on the etched substrate; and depositing the outermost layer on the intermediate layer. The method of claim 21, wherein the step of measuring the base spectrum includes measuring the base spectrum after depositing the alternating oxide and nitride layers on the substrate but before etching the substrate. The method of claim 21, wherein the step of measuring the base spectrum includes measuring the base spectrum after etching the substrate but before depositing a nitride layer. The method of claim 21, wherein measuring a post-deposition base spectrum includes measuring the post-deposition base spectrum after depositing a nitride layer but before depositing the outermost layer. The method according to claim 12, wherein the step of polishing the substrate includes a rear end portion of a production line of an integrated circuit manufacturing process. An integrated circuit manufacturing system includes: a deposition system configured to receive a product substrate, and deposit a stacked layer on the substrate, the stacked layer including an outer layer subjected to grinding and under the outer layer At least one patterned layer; a metering system configured to produce a measurement of the substrate after depositing the at least one patterned layer and before depositing the outer layer; and a grinding system configured to receive The substrate and the outer layer on the substrate are polished, wherein the polishing system includes a controller configured to perform the following operations including: receiving the measurement from the metering system and storing the measurement as a base measurement, receiving A series of original measurements from the substrate of a real-time monitoring system during grinding, using the original measurement and the base measurement to standardize each of the original measurements in the series to generate a series of standardized measurements; and At least one standardized predetermined measurement of the standardized measurement determines at least one of a grinding end point or an adjustment to a grinding rate. The system according to claim 26, wherein the metering system is an embedded metering station in the deposition system. The system according to claim 26, wherein the metering system is an independent metering system.

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