High speed nozzle for pre-polish modification of substrate thickness

Abstract

A method of manufacturing a substrate includes, after depositing an exterior layer on a substrate and before polishing an exposed surface of the exterior layer of the substrate, hydrojet treating a selected portion of the exposed surface to remove material from the selected portion by directing a treatment liquid from a nozzle onto the selected portion at a sufficiently high velocity, thickness unevenness of the outer layer is reduced. Then, the outer layer of the treated substrate is subjected to chemical mechanical polishing to planarize and reduce the thickness of the outer layer.

Description

Technical Field

[0001] This disclosure relates to chemical mechanical polishing, and more specifically to modifying the substrate thickness distribution prior to polishing. Background Technology

[0002] Integrated circuits are typically formed on a substrate by sequentially depositing conductive layers, semiconductor layers, or insulating layers on a silicon wafer. Various manufacturing processes require planarization of the layers on the substrate. For example, one manufacturing step involves depositing a fill layer on a non-planar surface and planarizing the fill layer. For some applications, the fill layer is planarized until the top surface of a patterned layer is exposed. For example, a metal layer may be deposited on a patterned insulating layer to fill trenches and holes in the insulating layer. After planarization, the remaining metal in the trenches and holes of the patterned layer forms vias, plugs, and pipes to provide conductive paths between thin-film circuits on the substrate.

[0003] Chemical mechanical polishing (CMP) is a recognized planarization method. This planarization method typically requires mounting the substrate on a carrier head. The exposed surface of the substrate is usually pressed against a rotating polishing pad. The carrier head applies a controlled load to the substrate to push it toward the polishing pad. A polishing slurry containing abrasive particles is typically supplied to the surface of the polishing pad. Summary of the Invention

[0004] In one aspect, a method of manufacturing a substrate includes: after depositing an outer layer on the substrate and before polishing the exposed surface of the outer layer of the substrate, performing a hydroblast treatment on a selected portion of the exposed surface by guiding a treatment liquid from a nozzle onto the selected portion at a sufficiently high velocity to remove material from the selected portion, thereby reducing the thickness non-uniformity of the outer layer. The treated outer layer of the substrate is then subjected to chemical mechanical polishing to planarize and reduce the thickness of the outer layer.

[0005] In another aspect, a water jet treatment station for modifying a substrate undergoing integrated circuit manufacturing includes a chuck for holding the substrate, a nozzle coupled to a treatment liquid source, the nozzle being laterally movable relative to the substrate, and a controller configured to direct the treatment liquid at a sufficiently high speed onto a selected portion to remove material from the selected portion, thereby reducing thickness non-uniformity of the outer layer of the substrate.

[0006] The implementation may optionally include, but is not limited to, one or more of the following advantages. A more uniform substrate layer thickness prior to polishing makes it easier to control polishing parameters during polishing, and improves polishing uniformity and reduces the intra-wafer non-uniformity (WIWNU) of the polished substrate.

[0007] Details of one or more implementations are illustrated in the accompanying drawings and the following description. Other aspects, features, and advantages will be apparent from the specification, drawings, and claims. Attached Figure Description

[0008] Figure 1 This is a schematic cross-sectional view of the substrate after deposition.

[0009] Figure 2 A schematic cross-sectional view of the substrate during the treatment of fluid ejected through a high-speed nozzle.

[0010] Figure 3 This is a schematic cross-sectional view of the treated substrate.

[0011] Figure 4 This is a schematic cross-sectional view of a substrate being polished.

[0012] Figure 5 This is a schematic cross-sectional view of the substrate after polishing.

[0013] Figure 6 This is a schematic cross-sectional view of a water jet treatment station.

[0014] Figure 7 yes Figure 6 A schematic top view of the water jet treatment station.

[0015] Figure 8 This is a schematic cross-sectional view of another implementation of a water jet treatment station. Detailed Implementation

[0016] Typical semiconductor manufacturing processes involve depositing a layer, followed by chemical mechanical polishing to remove it until the desired thickness is achieved or the underlying layer is exposed. If the underlying layer is patterned, the deposited layer often exhibits small-scale morphologies, such as nanoscale, because the deposited layer fills the trenches or holes desired for the integrated circuit. These small-scale morphologies can be removed by polishing, thus planarizing the substrate.

[0017] Some deposition processes can result in non-uniform deposition across the substrate. This non-uniform deposition can be much larger in scale and thickness than small-scale morphologies, for example, spanning regions up to 1 µm in thickness, typically in annular regions 5 to 40 mm wide. Many chemical mechanical polishing (CMP) systems include components that can vary the polishing rate across the substrate, such as a carrier head with multiple individually pressurized chambers, to compensate for non-uniform polishing effects or uneven layer thicknesses entering the substrate. However, non-uniform deposition caused by upstream processes can strain or exceed the compensation capabilities of the polishing system.

[0018] To address this issue, the substrate can be treated after deposition but before the next polishing process to modify its thickness distribution. Specifically, the substrate can be subjected to a fluid jet ejected from a high-speed nozzle, such as water jetting. Compared to etchant treatment, water jetting is primarily a mechanical removal process.

[0019] Figure 1 This is a schematic cross-sectional view of the substrate 10 after deposition. The substrate 10 includes a semiconductor wafer 12, one or more intermediate layers 14, and an outermost layer 16 having an exposed surface 18. The one or more intermediate layers 14 may include one or more patterned layers. In this case, the outermost layer 16 may have a small-scale morphology resulting from filling holes or trenches by the outermost layer 16. However, Figure 1-5 This small-scale morphology is not shown in the image.

[0020] In addition to any small-scale morphology, inhomogeneities in the deposition process can also lead to uneven thickness distribution in the outermost layer 16. For example, the outermost layer 16 may have a relatively thick region 20 that is thicker than other regions 22 of the outermost layer 16. The thick region 20 may be close to the edge of the substrate, for example, within 1-5 cm of the substrate edge. Since the deposition process is generally more uniform near the center of the substrate, the central portion 22 of the outermost layer 16 on the substrate 10 may have a relatively uniform thickness.

[0021] To address this unevenness, such as Figure 2 As shown, a relatively thick region 20 can be treated with water jetting, wherein fluid 50 (e.g., deionized water) is ejected at high speed from nozzle 52 (indicated by arrow A). Nozzle 52 can be moved laterally (indicated by arrow B) to scan the jet of fluid 50 onto the relatively thick region 20. Conversely, a thinner region 22 with a relatively uniform thickness is not treated with water jetting.

[0022] To determine which areas of the surface 18 of the outermost layer 16 of substrate 10 should be treated, the substrate can be transferred to a metrology station after deposition but before treatment. The metrology station can be a separate metrology system. The metrology station can generate thickness profiles, such as the thickness of the outermost layer 16 varying with radial position, or as a two-dimensional map, such as R... Alternatively, an XY diagram can be used. This measured thickness distribution can be stored by the controller and compared with the desired thickness distribution. Areas where the measured thickness distribution is thicker than the desired thickness distribution are identified as areas to be disposed of. In some implementations, only one substrate from a batch or cassette is measured; it is assumed that other substrates from the same batch or cassette have the same measured thickness distribution.

[0023] See Figure 3After water jet treatment, the thickness difference between the relatively thicker region 20' and the thinner region 22 is significantly reduced. For example, the thickness difference can be less than 2% of the total layer thickness, such as less than 1%. Specifically, the thickness difference can be reduced to the extent that variations in polishing parameters during chemical mechanical polishing (e.g., applying loads to different regions on the substrate through different pressurized chambers) can resolve any remaining inhomogeneities.

[0024] Figure 4 This is a schematic cross-sectional view of substrate 10 during the polishing process. Substrate 10 is held by a carrier head, and the surface 18 of the outer layer 16 abuts against polishing pad 60. Polishing liquid 62, such as an abrasive slurry, is applied to polishing pad 60, creating relative motion between polishing pad 60 and substrate 10 (indicated by arrow C). For example, polishing pad 60 may be located on a rotating platform, the carrier head may be rotated to rotate substrate 10, and optionally, the carrier head and substrate may be swept laterally across polishing pad 60.

[0025] The polishing system may include an in-situ monitoring system that generates a signal dependent on the thickness of the outermost layer 16. A controller within the polishing system can then receive this thickness data and control polishing parameters (e.g., pressurizing a chamber in the carrier head) to provide a polishing rate that results in a more uniform thickness after polishing.

[0026] although Figure 4 The substrate 10 is shown facing upwards, but this is for the purpose of... Figure 1-3 To maintain consistency; in fact, substrate 10 is typically polished with the face down orientation.

[0027] See Figure 5 The polishing process results in a reduction in the thickness of the outermost layer 16 of the substrate 10, for example, to a predetermined thickness, or until the underlying layer is exposed. This underlying layer will be one of one or more exposed intermediate layers 14. Due to the preceding water jetting treatment, the outermost layer 16 can have a substantially uniform thickness, for example, a non-uniformity of less than 3%, for example, between 1-2%. Furthermore, the substrate can have a more uniform thickness near the substrate edges, which improves bonding integration and edge grain performance.

[0028] Figure 6 A cross-sectional side view of a water jet treatment station 100, for example, for performing... Figure 2 The treatment shown is as described. The water jet treatment station 100 includes a chuck 110 for holding the substrate 10 and a dispenser 130 for delivering fluid 50 at high speed onto the surface 18 of the substrate 10.

[0029] The chuck 110 has a top surface 112 for contacting the back side of the substrate 10. In some implementations, the chuck 110 is rotatable, for example, by rotation of a drive shaft 114 driven by a motor 116. Although Figure 6 The chuck 110 is shown to be narrower than the substrate 10 (in the horizontal direction), but the chuck 110 may be wider than the substrate. A plurality of channels 120 may be formed through the chuck 110, with openings in the top surface 112. The channels 120 may be connected to a vacuum source 122, such as through a rotating fluid connection and any necessary conduit, flexible tubing, etc., to apply a vacuum to clamp the substrate 10 onto the chuck 110.

[0030] An annular shield 128 may surround the chuck 110, for example, concentric with the chuck 110, to block the disposal fluid 50 ejected from the substrate and thereby prevent contamination of other parts of the system. The shield 128 may also serve as a catch bowl to collect the disposal fluid 50 flowing out of the substrate 10.

[0031] To transfer substrate 10 onto chuck 110, the robot's end effector can transport substrate 10 to a position above the chuck. After the substrate is lowered onto chuck 110, a treatment fluid 50 (e.g., deionized water) is ejected at high speed from nozzle 52 (indicated by arrow A). In some implementations, a lifting rod 126 embedded in chuck 110 can be raised from chuck 110 to temporarily support substrate 10. When the lifting rod 126 supports substrate 10, the robot can retract the end effector. The lifting rod 126 can then retract back into chuck 110 until substrate 10 contacts the top surface 112 of chuck 110.

[0032] Alternatively, if the chuck 110 is narrower than the substrate 10, and the end effector is an edge gripper or edge support ring, the transfer of the substrate 10 can be accomplished simply by raising the chuck 110 using a vertical actuator (e.g., motor 116) until the chuck 110 contacts the substrate. The chuck 110 can be raised such that its top surface 112 is above the top edge 129 of the shield 128.

[0033] Alternatively, if the gap between the chuck 110 and the shield 128 is wide enough and the end effector is an edge gripper or an edge support ring, the transfer of the substrate 10 can be completed simply by lowering the end effector.

[0034] Dispenser 130 may include a nozzle 52 at the end of an arm 132 extending from base support 134. In some implementations, arm 132 may be pivotable (e.g., by rotation of a portion of base support 134) such that nozzle 52 can swing along an arc (indicated by arrow D), thereby controlling the radial position of nozzle 52 relative to the center of substrate 10 (e.g., relative to the axis of rotation of chuck 110). Simultaneously, rotation of chuck 110 and sweeping motion of the arm provide movement for the nozzle. Figure 2 (See arrow B in the image) to position the nozzle 52 at any desired location on the surface of the substrate 19.

[0035] Of course, there can be many other combinations of positioning for nozzle 52. For example, arm 132 may extend linearly rather than pivot. Base support 134 may be movable, for example, in a direction orthogonal to the linear movement of arm 132, to provide XY positioning of nozzle 52 above base plate 10. In this case, rotation of chuck 110 is unnecessary and optional.

[0036] Nozzle 52 is fluidly coupled to treatment fluid source 138 via fluid line 136 (e.g., via pipe, flexible fitting, passage through arm 132, etc.). Fluid source 138 may be a temperature-controlled fluid reservoir, facility line, etc. Pump or valve 140 controls the flow rate of treatment fluid 50 from fluid source 136 to nozzle.

[0037] Treatment liquid 50 may be deionized water (DI water). Specifically, unlike slurry-based polishing operations, treatment liquid 136 may be abrasive-free. Furthermore, treatment liquid 50 does not need to include any etchant. Treatment liquid 50 may include pH adjusters and / or accelerators. In some implementations, the treatment liquid may include abrasive particles, such as a slurry.

[0038] During operation, the pump or valve 140 can guide fluid 50 through nozzle 52 at a certain rate, causing the flow of fluid 50 to be sprayed onto the surface 18 of the outermost layer 16 of substrate 10 at a speed of approximately 5-20 m / s (e.g., 10 m / s). This speed should be sufficient to produce a hydrodynamic jet effect that removes material from the substrate. Excessive speed may result in over-removal or damage to the substrate. Insufficient speed may prevent material removal altogether. The size of the nozzle opening and the spacing between the nozzle and the substrate can be selected so that the treatment fluid 50 impacts the substrate within an area of ​​0.5 to 20 mm.

[0039] although Figures 6 to 7 The illustration shows substrate 10 in an upward-facing position for water jet treatment, but this is not mandatory. For example, see reference... Figure 8 The substrate 10 can be kept in a downward position, allowing the treatment fluid 50 to be sprayed upward from the nozzle 52. In some cases, this may be a superior configuration because the treatment fluid 50 will naturally fall off the surface of the substrate 10.

[0040] return Figures 6 to 7The hydraulic jet treatment station 100 may include a controller 190 coupled to various components of the station, such as a motor 116 for controlling the rotation and / or vertical position of the chuck 110, a motor for controlling the position of the arm 132 and the nozzle 52, and a pump or valve 140 for controlling the flow rate of the treatment fluid onto the substrate 10. Therefore, the controller 190 is configured to cause the system to perform hydraulic jet treatment operations.

[0041] Controller 190 can store a desired thickness distribution, for example, the outermost layer varying with radial position or as a two-dimensional graph (e.g., R). The desired thickness (or XY diagram) can be received from user input, uploaded files, or generated by an algorithm. The controller 190 can also receive, for example, a measured thickness distribution from a separate metering station measuring the substrate after the deposition of the outermost layer 16. The controller 190 can compare the measured thickness distribution with the desired thickness distribution to identify areas where the measured thickness distribution is thicker than the desired thickness distribution. Based on this identification, the controller 190 can generate a scanning and flow plan, such as a set of movements of the chuck 110 and / or arm 132, and a flow rate of the treatment liquid as the nozzle 52 moves relative to the substrate, to treat the identified areas and reduce the difference between the measured thickness distribution and the desired thickness distribution.

[0042] In some implementations, the controller 190 stores data, for example, in the form of a lookup table, containing information about the removal rate of the outermost layer 16 as a function of the flow rate of the treatment fluid 50. The data can be determined empirically for each type of substrate, for example, depending on the composition of the outermost layer 18 and the pattern on the substrate 10.

[0043] The water jet treatment station 100 may also include an in-situ monitoring system 180 that provides a measurement of the thickness of the outermost layer 116 during the treatment process. Examples of the monitoring system 180 include eddy current sensors or optical monitors, such as reflectometers or spectrometers. For example, the monitoring system 180 may include: a light source 182 for generating a light beam 184 reflected from the surface 18 of the outermost layer 18 of the substrate; and a detector 186, such as a photodetector, for detecting the intensity of the reflected light. The monitoring system 180 may be positioned to monitor an area on the substrate at the same radial location as that being treated by the nozzle 52. For example, the optical monitoring system 180 may be attached to the same arm 132 holding the nozzle 52, or the optical monitoring system 180 may be attached to a separate arm extending above the chuck, and the controller 190 may cause the separate arm to position the monitoring area at the same radial distance from the center of the substrate as the nozzle 52. The monitoring system 180 may communicate with the controller 190 to provide feedback and control the treatment process.

[0044] As used in this specification, the term "substrate" may include, for example, product substrates (e.g., those comprising multiple memory or processor dies), test substrates, bare substrates, and gated substrates. Substrates may be present at various stages of integrated circuit manufacturing.

[0045] The controllers and other computing device components of the systems described herein can be digital electronic circuit systems or implemented as computer software, firmware, or hardware. For example, the controller may include a processor to execute a computer program, such as one stored in a computer program product, for example, stored on a non-transitory machine-readable storage medium. Such a computer program (also referred to as a program, software, software application, or code) may be written in any form of programming language, including compiled or interpreted languages, and may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0046] In the context of a controller, “configuration” indicates that the controller has the necessary hardware, firmware or software, or a combination thereof, to perform the desired function during operation (rather than simply being programmable to perform the desired function).

[0047] Several implementations have been described. However, it will be understood that various modifications may be made without departing from the spirit and scope of this specification. Therefore, other implementations are within the scope of the appended claims.

Claims

1. A method comprising: After depositing the outer layer on the substrate and before polishing the exposed surface of the outer layer on the substrate, the selected portion of the exposed surface is subjected to hydrojet treatment by guiding treatment liquid from the nozzle to the selected portion at a sufficiently high speed to remove material from the selected portion, thereby reducing the thickness non-uniformity of the outer layer; as well as The outer layer of the treated substrate is chemically and mechanically polished to planarize it and reduce the thickness of the outer layer.

2. The method of claim 1, comprising depositing the outer layer at a deposition station and transferring the substrate to a hydrojet treatment station for the hydrojet treatment.

3. The method of claim 1, further comprising holding the substrate on a chuck during the water jet treatment.

4. The method of claim 3, further comprising holding the substrate in an upward orientation during the water jet treatment.

5. The method of claim 3, further comprising holding the substrate in a downward orientation during the water jet treatment.

6. The method of claim 3, further comprising vacuum clamping the substrate to a chuck.

7. The method of claim 3, further comprising rotating the chuck and sweeping the nozzle radially across the substrate to position the nozzle above the selected portion.

8. The method of claim 1, wherein the treatment fluid comprises deionized (DI) water.

9. The method of claim 8, wherein the treatment fluid is free of abrasives and / or etchants.

10. The method of claim 1, wherein the selected portion is annular.

11. The method of claim 10, wherein the selected portion has a radial width of about 5 to 40 mm.

12. The method of claim 1, further comprising flowing the treatment fluid onto the exposed surface of the substrate at a speed of 5-20 m / s.

13. The method of claim 1, further comprising receiving a measured thickness distribution from a metrology station, storing a desired thickness distribution, and comparing the measured thickness distribution with the desired thickness distribution to determine the selected portion of the surface.

14. A water jet treatment station for modifying a substrate undergoing integrated circuit manufacturing, the station comprising: A chuck is used to hold the substrate; A nozzle, coupled to a source of liquid to be disposed, is laterally movable relative to the substrate; as well as The controller is configured to direct the treatment liquid onto the selected portion at a sufficiently high speed to remove material from the selected portion, thereby reducing the thickness non-uniformity of the outer layer of the substrate.

15. The water jet treatment station of claim 14, comprising a shield to capture treatment fluid ejected or falling from the substrate.

16. The water jet treatment station of claim 14, comprising a plurality of channels through the chuck, the plurality of channels being coupled to a vacuum source to vacuum clamp the substrate to the chuck.

17. The water jet treatment station of claim 14, wherein the controller is configured to receive a measured thickness distribution of the outer layer from a metering station, store a desired thickness distribution, and compare the measured thickness distribution with the desired thickness distribution to determine the selected portion of the surface.

18. The water jet treatment station of claim 14, comprising a pump or valve to control the flow rate of the treatment liquid from the source to the nozzle.

19. The water jet treatment station of claim 18, wherein the controller is configured to control the pump or valve such that the treatment liquid is jetted onto the exposed surface of the substrate at a speed of 5-20 m / s.

20. The water jet treatment station of claim 14, wherein the chuck is rotatable.

21. The water jet treatment station of claim 20, wherein the nozzle is suspended from the pivot arm.

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