Heater pedestal with improved uniformity and method of modifying the same

Abstract

Some embodiments of this disclosure relate to methods for modifying a heater base to improve temperature and thickness uniformity. Some embodiments of this disclosure relate to a modified heater base with improved temperature and thickness uniformity. In some embodiments, the height of the support platform in different regions of the base is modified to increase temperature uniformity. In some embodiments, the heater element is moved above vacuum channels and flushing channels to increase temperature uniformity. In some embodiments, the edge ring is modified to be coplanar with the top of the support substrate.

Description

[Technical Field]

[0001] Embodiments of this disclosure generally relate to methods for improving the temperature uniformity of a wafer across a heater base. Specifically, embodiments of this disclosure relate to methods for modifying the physical dimensions and arrangement of elements to improve temperature uniformity. [Previous Technology]

[0002] Semiconductor processing chambers typically include a base suspended within the chamber for supporting the wafer or substrate to be processed. In many embodiments, the base also includes a heater for maintaining the substrate at an elevated temperature during processing.

[0003] The base also includes several gas channels to aid in the processing of the substrate. For example, in some cases, the base includes a vacuum channel used to provide a vacuum to hold the substrate to the base. Another example is an edge flushing channel, which provides flushing gas flow to areas near the peripheral edge of the substrate to avoid unwanted deposits.

[0004] Unfortunately, both of these gas channels can reduce the temperature of the substrate that is tightly surrounding the channel. This temperature change, or "non-uniformity" (N / U), can affect the rate of processing reactions that occur on the substrate surface during processing, resulting in variations in thickness across the substrate surface (i.e., thickness non-uniformity).

[0005] Accordingly, an improved heater base is needed to provide better temperature uniformity. Furthermore, existing heater bases need to be modified to provide better temperature uniformity. [Summary of the Invention]

[0006] One or more embodiments of this disclosure are a method for modifying a heater base to reduce temperature nonuniformity across a substrate supported on the heater base. The method includes the steps of: modifying the height of the platforms in one or more concentric regions of the heater base; modifying the number of platforms on the heater base; modifying the depth of a clamping channel that secures the substrate to the heater base; modifying the composition of an edge ring surrounding the substrate; or modifying the height of the edge ring.

[0007] An additional embodiment of this disclosure is a method for modifying a heater base to reduce temperature nonuniformity across a substrate supported on the heater base. The method includes the steps of: moving a heater plate containing one or more heater coils above a top plate containing an edge flushing channel and a vacuum clamping channel; modifying a direction of an edge flushing gas flow rate relative to an edge of the heater plate; or modifying a thickness of the heater base to increase a flow path distance of the edge flushing gas flow rate close to the heater plate.

[0008] A further embodiment of this disclosure is a heater base for supporting a substrate during processing. The base includes: a base plate including an edge flushing channel extending from near the center of the base toward a peripheral edge of the base, and a vacuum channel extending from near the center of the base toward a plurality of outlets. A heater plate is on the base plate. The heater plate includes two concentric heaters: a first heater covering a radius of about 135 mm from the center of the base, and a second heater covering a radius of about 135 mm to the peripheral edge of the base. A top plate is on the heater plate. The top plate includes a plurality of top outlets and a plurality of substrate support platforms in the top surface of the top plate. The top outlets are provided with fluid connection to the outlets via the heater plate and the top plate. An edge ring surrounds the base plate, the heater plate, the top plate, and the periphery of the substrate when it appears.

Implementation Method

[0017] Before describing several exemplary embodiments of this disclosure, it should be understood that this disclosure is not limited to the details of the construction or processing steps set forth in the following description. This disclosure can have other embodiments and can be practiced or implemented in various ways.

[0018] As used in this specification and the appended claims, the term "substrate" refers to a surface or a portion thereof on which the treatment is performed. Those skilled in the art will also understand that reference to a substrate may also refer only to a portion of the substrate, unless the context clearly indicates otherwise. Furthermore, reference to deposition on a substrate may mean both a bare substrate and a substrate on which one or more films or features are deposited or formed.

[0019] As used herein, "substrate" means any substrate or material surface formed on a substrate on which a film treatment is performed during manufacturing processes. For example, substrate surfaces on which treatments can be performed include materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, but are not limited to, semiconductor wafers. Substrates may be exposed to pretreatment processes such as polishing, etching, reduction, oxidation, hydroxylation, annealing, UV curing, electron beam curing, and / or baking of the substrate surface. In addition to performing film treatments directly on the surface of the substrate itself, in this disclosure, any of the disclosed film treatment steps may also be performed on an underlayer formed on the substrate, as disclosed in more detail below, and the term "substrate surface" is intended to include such an underlayer as indicated by the context.

[0020] One or more embodiments of this disclosure are a base heater. Some embodiments of this disclosure advantageously provide lower temperature non-uniformity across the support wafer during processing. Some embodiments of this disclosure advantageously provide lower thickness non-uniformity of the deposited film across the support wafer during processing. Some embodiments of this disclosure advantageously reduce the temperature characteristics of the clamping channels on the support wafer during processing.

[0021] For the purposes of this disclosure, reference will be made to variable plotting and the values ​​derived therefrom. Variable plotting measures the substrate across its entire surface. In some embodiments, variable plotting measures 49 points or 73 points on the substrate surface. In some embodiments, variable plotting measures the temperature of the substrate. In some embodiments, variable plotting measures the thickness of the deposited film.

[0022] In some embodiments, the deposited film is a TiAl film deposited by atomic layer deposition at a substrate temperature of about 350 degrees Celsius.

[0023] Throughout this disclosure, a non-uniformity measure known as 3-sigma will be referenced. The 3-sigma value represents the percentage of measurement points that exceed the mean by 3 standard deviations. Accordingly, a lower 3-sigma value corresponds to higher uniformity and lower non-uniformity.

[0024] Referring to Figures 1 to 4, one or more embodiments are heater base 100. In some embodiments, heater base 100 includes a shaft 105 connected to a base plate 110. A heater plate 120 is located on the base plate 110. A top plate 130 is located on the heater plate 130. Each of the shaft 105, base plate 110, heater plate 120, and top plate 130 is shown separately in Figure 1. Those skilled in the art will understand that these elements may be formed of the same material, and one or more of these elements may be integrally formed together.

[0025] Shaft 105 provides conduits for gas flow (e.g., flushing, vacuum), electrical connections (e.g., heater power, metering sensors, etc.) and mechanical connections (e.g., motor connections, structural supports).

[0026] The base plate 110 is connected to the shaft 105 and provides structural support for the heater plate 120 and the top plate 130. The heater plate 120 includes one or more heaters to maintain the supporting substrate at a constant temperature during processing. Due to numerous factors, the temperature across the substrate surface may vary or have a degree of non-uniformity.

[0027] In some embodiments, the heater plate 120 includes more than one heating element. In some embodiments, the more than one heating element is concentrically arranged such that one or more heaters operate primarily on the inner region of the substrate, while an additional one or more heaters operate on the outer or peripheral region of the substrate. In some embodiments, the heater plate 120 includes two heating elements. In some embodiments, a first heating zone is heated by heater 630 and covers a radius up to 135 mm, while a second heating zone is heated by heater 640 and covers a radius of 135 mm to the outer peripheral edge of the heater base. In some embodiments, the heater base has a radius of 152 mm.

[0028] The top plate 130 is located on the heater plate 120 and provides support for the substrate during processing. In some embodiments, the top plate 130 has a radius of about 150 mm.

[0029] As shown in Figures 2 and 3, the substrate is supported by a plurality of mesa 210. In some embodiments, the top plate includes mesa in the range of about 500 to about 650. In some embodiments, the mesa is circular with a radius of about 30 mil. In some embodiments, the mesa has a height in the range of about 2 mil to about 4 mil.

[0030] For the purposes of this disclosure, the countertop 210 can be identified as being within concentric zones 215a to 215d. Zone 215a is the area defined by line A. Zone 215b is the area between line A and line B. Zone 215c is the area between line B and line C. Zone 215d is the area between line C and the periphery of the top plate 130.

[0031] Although four zones are shown in Figures 2 and 3, this disclosure may allow for more or fewer zones. In some embodiments, line A is located at a radius of approximately 25 mm. In some embodiments, line B is located at a radius of approximately 50 mm. In some embodiments, line C is located at a radius of approximately 100 mm.

[0032] Also shown in Figures 2 and 3 is the clamping channel 220. The clamping channel 220 is in fluid communication with at least one outlet 225 from the vacuum channel 430 (shown in Figure 4). As shown in Figure 3, the clamping channel 220 is recessed and has a depth in the range of 10 mil to 20 mil. The clamping channel 220 provides a backside negative pressure to the substrate to ensure that the substrate does not move on the heater base 100.

[0033] Referring to Figure 4, the top plate 130 also includes a vacuum channel 430 and an edge flushing channel 440 within the top plate 130. Both the vacuum channel 430 and the edge flushing channel 440 begin near the center of the top plate 130. As shown in Figure 4, the vacuum channel 430 begins at 432 and continues to four outlets 225. The edge flushing channel 440 begins at 442 and continues to sixteen outlets 445. Although four outlets 225 and sixteen outlets 445 are shown in Figure 4, any suitable number of outlets is contemplated as part of this disclosure.

[0034] Without being limited by theory, it is believed that the gas flow through the vacuum channel 430 and the edge flushing channel 440 reduces the local temperature of the substrate above these channels by decreasing the thermal conductivity of the base. For the heater base design shown in Figures 1 to 4, the outer radius of the vacuum channel 430 (at a radius of approximately 75 mm) exhibits the most significant temperature nonuniformity (see Figures 5A and 5B). Accordingly, when these channels are in use, the temperature nonuniformity will increase.

[0035] Due to this temperature non-uniformity, the inventors have discovered a variety of methods for modifying the heater base 100 to reduce the temperature non-uniformity of the substrate supported across the heater base 100.

[0036] In some embodiments, the methods include increasing the relative thermal conductivity of the base above the vacuum channel 430 to offset any conductivity loss due to the channel. In some embodiments, the methods include reducing the thermal conductivity of the base not above the vacuum channel 430 to provide more uniform thermal conductivity across the base.

[0037] In some embodiments, the methods include modifying the height of the tabletop in one or more regions. In some embodiments, the height of the tabletop is increased in one or more regions. In some embodiments, the height of the tabletop is increased by up to 200%. In some embodiments, the height of the tabletop 210 in region 215a may be increased by 100%, the height of the tabletop 210 in region 215b may be increased by 50%, the height of the tabletop 210 in region 215c may be increased by 0%, and the height of the tabletop 210 in region 215d may be increased by 50%. In some embodiments, the height of the tabletop 210 in region 215a may be increased by 2 mil, the height of the tabletop 210 in region 215b may be increased by 1 mil, the height of the tabletop 210 in region 215c may be increased by 0 mil, and the height of the tabletop 210 in region 215d may be increased by 1 mil.

[0038] In some embodiments, the method includes reducing the number of platforms 210 on the heater base 100. In some embodiments, the outermost ring of the platform 210 is removed. In some embodiments, the number of platforms is reduced by more than or equal to 15%. In some embodiments, the number of platforms is reduced from 622 to 528.

[0039] In some embodiments, the methods include modifying the depth of the clamping channel 220. In some embodiments, the depth of the clamping channel is reduced. In some embodiments, the depth of the clamping channel is reduced by more than or equal to 25%. In some embodiments, the depth of the clamping channel is reduced from about 15 mil to about 11 mil.

[0040] The inventors have surprisingly discovered that by implementing one or more of the disclosed methods, temperature nonuniformity (3-sigma) can be reduced by greater than or equal to 40%. For example, an unmodified heater base provides a 3-sigma value of about 3%, but a heater base modified by the disclosed methods provides a 3-sigma value of about 1.8% for temperature nonuniformity.

[0041] Similarly, the inventors also surprisingly discovered that by implementing one or more of the disclosed methods, the thickness nonuniformity (3-sigma) of the film deposited on the substrate can be reduced by greater than or equal to 50%. For example, the unmodified heater base provides a 3-sigma value of about 3%, but the heater base modified by the disclosed methods provides a 3-sigma value of about 1.5% for thickness nonuniformity. Figures 5A and 5B illustrate simulated temperature and deposition thickness profiles before and after modification.

[0042] In some embodiments, the disclosed method reduces temperature nonuniformity by more than or equal to 40%. In some embodiments, the disclosed method reduces thickness nonuniformity of the deposited film by more than or equal to 50%. In some embodiments, temperature reduction at the clamping channel is reduced.

[0043] Referring to FIG6, one or more embodiments are modified heater base 600. For the avoidance of doubt, the dimensions in FIG6 are not drawn to scale. In some embodiments, the top plate 130 is split to accommodate the heater plate 120. The lower top plate 130a includes a vacuum channel (not shown) and an edge flushing channel 440, as described above with respect to FIG4. The upper top plate 130b includes a platform and a clamping channel (both not shown), as described above with respect to FIGS. 2 and 3. The substrate 610 is supported on the upper top plate 130b. In some embodiments, an outlet (not shown) extends from the lower top plate 130a, which includes the vacuum channel, across the heater plate 120 to the upper top plate 130b, which includes the clamping channel.

[0044] In some embodiments, the modified heater base 600 includes an edge ring 620. In some embodiments, the edge ring 620 is primarily composed of Al2O3. In some embodiments, the edge ring 620 is primarily composed of AlN.

[0045] Without being limited by theory, it is believed that if the edge ring component has a higher thermal conductivity (AlN is higher than Al2O3), the energy imparted to the flushing gas will be higher, resulting in a flushing gas with a higher temperature and a lower edge cooling effect.

[0046] In some embodiments, when the top plate 130 is split to accommodate the heater plate 120, as described above, the thickness of the heater base 600 and the edge ring 620 is increased to accommodate the increased distance between the lower top plate 130a and the upper top plate 130b.

[0047] In some embodiments, the outlet 445 of the edge flushing channel 440 is vertically oriented. In some embodiments, the vertical orientation of the outlet 445 increases the residence time of the flushing gas near the heater plate 120.

[0048] Without being limited by theory, it is believed that one or more of the following factors contribute to improved temperature nonuniformity. First, the heater plate is closer to the substrate than the vacuum channel 430 and the edge flushing channel 440. Accordingly, the temperature drop typically observed is due to the lower position of these channels. Furthermore, the temperature effects of the channels are more easily offset by the heater before affecting the substrate.

[0049] Secondly, the increased thickness between the edge flushing channel and the substrate leads to an increased flow path distance of the flushing gas as it approaches the heater. It is believed that the temperature increase generated in the flushing gas has a relatively small cooling effect on the substrate edge.

[0050] The inventors have surprisingly discovered that by implementing one or more of these methods, the thickness non-uniformity (3-sigma) of the film deposited on the substrate can be reduced by greater than or equal to 60%. For example, an unmodified heater base provides a 3-sigma value of about 3%, but a heater base modified by the disclosed method provides a 3-sigma value of about 1.2% for thickness non-uniformity. Figure 7 illustrates simulated deposition thickness profiles before and after modification.

[0051] In some embodiments, the disclosed method reduces the thickness non-uniformity of the deposited film by more than or equal to 60%. In some embodiments, the temperature reduction at the clamping channel is reduced or eliminated.

[0052] In some embodiments, the height H of the edge ring 620 is modified. In some embodiments, the height H of the edge ring 620 is reduced such that the top of the edge ring 620 is substantially coplanar with the top surface 615 of the substrate 610. As used herein, "substantially coplanar" means that the top of the edge ring 620 and the top surface 615 of the substrate 610 are within + / - 5 mil.

[0053] Throughout this specification, references to "one embodiment," "some embodiments," "one or more embodiments," or "an embodiment" refer to a specific feature, structure, material, or characteristic described in connection with the embodiment being included in at least one embodiment of this disclosure. Therefore, phrases such as "in one or more embodiments," "in some embodiments," "in one embodiment," or "in one embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment of this disclosure. Furthermore, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0054] Although the disclosure herein has been described with reference to specific embodiments, those skilled in the art will understand that the described embodiments are merely illustrative of the principles and applications of the disclosure. Various modifications and variations to the methods and apparatus of the disclosure will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure. Therefore, the disclosure may include modifications and variations within the scope of the appended claims and their equivalents. [Simplified Explanation of the Diagram]

[0009] To gain a more detailed understanding of the features of this disclosure, a more specific description of the above-briefly summarized disclosure can be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only typical embodiments of this disclosure and should not be considered as limiting its scope, as other equivalent embodiments are permissible.

[0010] FIG1 is a side view of a heater base according to one or more embodiments of the present disclosure;

[0011] FIG2 is a top view of a heater base according to one or more embodiments of the present disclosure.

[0012] FIG3 is an enlarged perspective view of the top of a heater base according to one or more embodiments of the present disclosure.

[0013] Figure 4 is a top view of an internal channel within a heater base according to one or more embodiments of the present disclosure;

[0014] Figures 5A and 5B illustrate simulated temperature and deposition thickness profiles before and after modifications according to one or more embodiments of the present disclosure;

[0015] Figure 6 is an enlarged side view of the peripheral edge of a heater base according to one or more embodiments of the present disclosure; and

[0016] Figure 7 illustrates simulated deposition thickness profiles before and after modifications according to one or more embodiments of the present disclosure. [Biomaterial Storage]

[0056] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A method for modifying a heater base to reduce temperature nonuniformity of a substrate supported across the heater base, the method comprising the steps of: modifying a height of a platform in one or more concentric regions of the heater base; modifying a number of platforms on the heater base; modifying a depth of a clamping channel for securing the substrate to the heater base; modifying a component of an edge ring surrounding the substrate; or modifying a height of the edge ring.

2. The method as described in claim 1, wherein the method reduces the temperature range by more than or equal to 40%.

3. The method as described in claim 1, wherein the method reduces the thickness non-uniformity of a deposited film by more than or equal to 50%.

4. The method as described in claim 1, wherein the temperature increase at the clamping channel is greater than or equal to 1 degree Celsius.

5. The method as described in claim 1, wherein the height of the tabletop is increased.

6. The method as described in claim 5, wherein the height of the tabletop is increased to 100%.

7. The method as described in claim 1, wherein the heater base includes a platform with four concentric regions.

8. The method as described in claim 7, wherein the outer radii of the concentric regions are approximately 25 mm, 50 mm, 100 mm, and 150 mm, respectively.

9. The method as described in claim 8, wherein the tabletops are increased in height by 100%, 50%, 0%, and 50%, respectively.

10. The method as described in claim 8, wherein the height of the tabletops is increased by 2 mil, 1 mil, 0 mil, and 1 mil, respectively.

11. The method as described in claim 1, wherein the number of countertops is reduced by more than or equal to 15%.

12. The method as described in claim 11, wherein the number of countertops is reduced from 622 to 528.

13. The method as described in claim 1, wherein the depth of the clamping channel is reduced by more than or equal to 25%.

14. The method as described in claim 13, wherein the depth is reduced from a depth of 15 mil to a depth of 11 mil.

15. The method as described in claim 1, wherein an edge ring mainly composed of Al2O3 is replaced by an edge ring mainly composed of AlN.

16. The method as described in claim 1, wherein the height of the edge ring is reduced to be substantially coplanar with a height of the substrate.

17. A method for modifying a heater base to reduce temperature nonuniformity across a substrate supported on the heater base, the method comprising the steps of: moving a heater plate including one or more heater coils above a top plate including an edge flushing channel and a vacuum clamping channel; modifying a direction of an edge flushing gas flow rate relative to an edge of the heater plate; or modifying a thickness of the heater base to increase a flow path distance of the edge flushing gas flow rate close to the heater plate.

18. The method as described in claim 17, wherein the method reduces the thickness non-uniformity of a deposited film by more than or equal to 60%.

19. A heater base for supporting a substrate during processing, comprising: A base plate including an edge flushing channel extending from a center near the base toward a peripheral edge of the base, and a vacuum channel extending from the center near the base toward a plurality of outlets; a heater plate on the base plate including two concentric heaters, a first heater covering the center of the base to a radius of about 135 mm, and a second heater covering a radius from about 135 mm to the peripheral edge of the base; a top plate on the heater plate including a plurality of top outlets and a plurality of substrate support platforms in a top surface of the top plate, the top outlets being provided with fluid connection to the outlets via the heater plate and the top plate; and an edge ring surrounding the base plate, the heater plate, the top plate, and the periphery where the substrates appear.

20. The heater base as claimed in claim 19, wherein a thickness non-uniformity of a TiAl film deposited on the substrate has a 3-sigma value of less than or equal to 1.5%.

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