Self-aligning interference endpoint housing

Abstract

Embodiments of an interference endpoint (IEP) housing assembly for endpoint detection for plasma processing are provided herein. In some embodiments, an IEP housing assembly includes an IEP housing having an upper end configured to interface with a light source and having an internal cavity, where a lower end of the IEP housing is configured to interface with a dome assembly of a processing chamber; a bracket having a main body disposed around the IEP housing, and having a plurality of arms extending radially outward from the main body; and a plurality of biasing members extending from the main body to the IEP housing and configured to retain the IEP housing within the main body while allowing lateral deflection.

Description

Technical Field

[0001] The embodiments of this disclosure generally relate to substrate processing equipment. Background Technology

[0002] Integrated circuits have evolved into complex devices, with millions of components (such as transistors, capacitors, resistors, and the like) potentially cascading onto a single chip. The evolution of chip design necessitates faster circuits and greater circuit density. This demand for greater circuit density inevitably leads to a reduction in the size of integrated circuit components. The minimum dimension of a feature in such a device is often referred to in the art as the critical dimension. Critical dimensions broadly encompass the minimum width of a feature, such as a line, column, aperture, space between lines, and the like.

[0003] As these critical dimensions shrink, precise measurement and processing control become increasingly challenging. Interference endpoint detection methods utilize a beam of light guided onto the substrate (e.g., from an interference endpoint (IEP) housing), which is then reflected from the substrate to form a reflected beam. Based on the reflected beam, the endpoint of plasma processing, the endpoint of etching processing, the etching depth, or the etching rate can be determined. However, interference endpoint housings in conventional processing chambers are often assembled in dead zones, posing difficulties for integration and alignment of the interference endpoint housing above the substrate during processing.

[0004] Therefore, the inventors hereby provide an embodiment of an improved interference endpoint housing assembly for endpoint detection. Summary of the Invention

[0005] This document provides an embodiment of an interferometric endpoint (IEP) housing assembly for endpoint detection in plasma processing. In some embodiments, an IEP housing assembly includes: an IEP housing having an upper end configured to interface with a light source and having an internal cavity, wherein a lower end of the IEP housing is configured to interface with a dome assembly of a processing chamber; a support having a body disposed around the IEP housing and having a plurality of arms extending radially outward from the body; and a plurality of biasing members extending from the body to the IEP housing and configured to retain the IEP housing within the body while allowing lateral deflection.

[0006] In some embodiments, an endpoint detection (IEP) housing assembly for plasma processing includes: an IEP housing having an upper end configured to interface with a light source and having an internal cavity, wherein a lower end of the IEP housing is configured to interface with a dome assembly of a processing chamber; a support having a body disposed around the IEP housing and having a plurality of arms extending radially outward from the body; a plurality of biasing members extending from the body to the IEP housing and configured to retain the IEP housing within the body while allowing lateral deflection; a first mounting plate coupled to the support through corresponding ends of the plurality of arms; and a plurality of second biasing members disposed between the plurality of arms and the first mounting plate and configured to apply force on the support to hold the IEP housing against the dome assembly.

[0007] In some embodiments, a processing chamber includes: a chamber body defining an internal volume therein; a dome assembly disposed within the internal volume, wherein the dome assembly includes a dome, a window, and a dome ring configured to clamp the window to the dome; and an upper assembly disposed above the dome, wherein the upper assembly includes: an interferometric endpoint (IEP) housing assembly for endpoint detection of plasma processing, comprising: an IEP housing having an upper end configured to interface with a light source and having an internal cavity, wherein a lower end of the IEP housing is configured to interface with the dome ring; a support having a body disposed around the IEP housing and having a plurality of arms extending radially outward from the body; and a plurality of biasing members extending from the body to the IEP housing and holding the IEP housing within the body while allowing lateral deflection to align the IEP housing relative to the dome ring.

[0008] Other and further embodiments of this disclosure are described below. Attached Figure Description

[0009] The embodiments of this disclosure, briefly summarized above and discussed in more detail below, can be understood by referring to the illustrative embodiments shown in the accompanying drawings. However, the drawings only illustrate the general embodiments of this disclosure and should not be considered as limiting the scope, as other embodiments with equivalent effects are permissible.

[0010] Figure 1 A schematic side view of a processing chamber is depicted according to at least some embodiments of this disclosure.

[0011] Figure 2 A schematic side view of the upper assembly of the processing chamber is depicted according to at least some embodiments of this disclosure.

[0012] Figure 3According to at least some embodiments of this disclosure, an enlarged isometric view of an interference endpoint (IEP) housing assembly is depicted.

[0013] Figure 4 According to at least some embodiments of this disclosure, a cross-sectional side view of a portion of an Interference End Point (IEP) housing assembly is depicted.

[0014] Figure 5 According to at least some embodiments of this disclosure, a cross-sectional side view of the interface between the biasing member of the bracket and the interference endpoint (IEP) housing is depicted.

[0015] Figure 6 A simplified top view of an RF coil is depicted according to at least some embodiments of this disclosure.

[0016] For ease of understanding, the same reference numerals are used as much as possible to denote the same elements in the figures. These figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. Detailed Implementation

[0017] This document provides an embodiment of an interferometric endpoint (IEP) housing assembly for endpoint detection in plasma processing. The IEP housing assembly is coupled to an upper assembly of a processing chamber, such as a plasma processing chamber, etching chamber, or the like. The IEP housing assembly generally comprises an IEP housing. Due to interference with other components of the processing chamber, the IEP housing may be difficult to align with a lower assembly of the processing chamber having a dome assembly. The IEP housing assembly provided herein includes a support, wherein a self-aligning feature between the support and the IEP housing facilitates movement of the IEP housing relative to the support, thereby enabling the IEP housing to self-align with the dome assembly of the processing chamber.

[0018] The IEP housing assembly can advantageously provide alignment in one or more directions. For example, the IEP housing assembly may include a plurality of biasing members configured to allow lateral deflection to provide radial alignment between the IEP housing and the dome assembly relative to the IEP housing. The IEP housing assembly may include a plurality of second biasing members to provide axial alignment between the IEP housing and the dome assembly relative to the IEP housing. The IEP housing assembly may be biased toward or held against the dome assembly via the plurality of second biasing members.

[0019] Figure 1A schematic side view of a processing chamber 100 is shown according to at least some embodiments of this disclosure. The processing chamber 100 generally includes cylindrical sidewalls or a chamber body 112 defining an internal volume 135. The chamber body 112 includes a dome assembly 123 having a dome 113, and further includes a chamber bottom 117 mounted to a sidewall 111 of the chamber body 112. A flat cover (not shown) or other alternative cover capable of being used with an inductor coil may be used instead of the dome 113. An RF coil 126 or an inductor coil is disposed around at least a portion of the dome 113. The chamber body 112 may be made of metal, such as anodized aluminum. The dome 113 may be made of an energy-transparent material, such as ceramic or other dielectric materials.

[0020] A substrate support 116 is disposed in the processing chamber 100 to support the substrate 120 during processing. The substrate support 116 can be a conventional mechanical or electrostatic chuck, at least a portion of which is conductive and can be used as a processing bias cathode. Although not shown, a photomask or photomask adapter can be used to secure a photomask or photomask to the substrate support 116. The photomask adapter generally includes a lower portion milled to cover an upper portion of the substrate support 116, and a top portion having an opening sized and shaped to hold the photomask.

[0021] Processing gases are introduced from a processing gas source 121 into the processing chamber 100 through a gas distributor 122 disposed around the substrate support 116. A mass flow controller (not shown) is provided between the processing chamber 100 and the processing gas source for each processing gas or for a mixture of processing gases to regulate the respective flow rate of the processing gases. The mass flow controller can regulate the flow rate of a single processing gas up to about 500 sccm, and the flow rate of a mixture of processing gases up to about 300 sccm.

[0022] Plasma region 114 is defined by processing chamber 100, substrate support 116, and dome 113. In plasma region 114, an RF coil 126 is powered by a coil power supply 127, thereby generating an electromagnetic field in plasma region 114 formed by the processing gas. In some embodiments, the coil power supply 127 may be coupled to an RF matching network 129. Substrate support 116 includes electrodes disposed therein, powered by an electrode power supply 128, generating a capacitive electric field in processing chamber 100. In some embodiments, electrode power supply 128 may be coupled to an RF matching network 131. Typically, RF power is applied to the electrodes in substrate support 116 while chamber body 112 is electrically grounded. The capacitive electric field is transverse to the plane of substrate support 116 and influences the directionality of charged matter to provide a more vertically oriented anisotropic plasma treatment to substrate 120.

[0023] Processing gases and etching byproducts are discharged from the processing chamber 100 through an exhaust system 130. The exhaust system 130 may be located in the chamber bottom 117 of the processing chamber 100 or in the chamber body 112 of the processing chamber 100, and is used to remove processing gases. A throttle valve 132 is provided in the exhaust port 134 for controlling the pressure in the processing chamber 100.

[0024] Processing chamber 100 includes an Interference End Point (IEP) housing assembly 140 disposed above dome 113 to determine the endpoint of the processing performed within chamber body 112. Typically, the IEP housing assembly 140 is coupled to a light source 152 suitable for emitting an incident beam and a photodetector 154 for measuring the intensity of the reflected beam from substrate 120 to generate a reflection intensity signal to determine processing parameters. The light source 152 may include a suitable light source, such as a monochromatic or polychromatic light source, to generate an incident beam with sufficiently high intensity to provide a reflected beam with measurable intensity reflected from substrate 110. The light source 152 may transmit the incident beam to the IEP housing assembly 140 via a suitable conduit (e.g., fiber optic cable). The incident and reflected beams are guided through a window 142 in dome 113 that allows the beam to enter and exit plasma region 114. The window 142 is made of a suitable material, such as sapphire, quartz, etc.

[0025] In some embodiments, the controller 144 is coupled to the IEP housing assembly 140, for example, to calculate the number of interference fringes in the reflected beam signal. The controller 144 may additionally or alternatively compare a portion of the reflected signal waveform measured in real time with a stored characteristic waveform or other representative pattern, and adjust the processing conditions in the processing chamber 100 when the two waveforms have substantially the same shape.

[0026] The photodetector 154 may include photosensitive electronic components, such as a photomultiplier tube, photovoltaic cell, photodiode, or phototransistor, to provide an electrical signal in response to the measured intensity of a reflected light beam reflected from the substrate 120. A signal filter (not shown) may be plated in front of the photodetector 154. The signal may be in the form of a change in the level of current passing through the electronic components or a change in voltage applied across the electronic components. The reflected light beam undergoes constructive and / or destructive interference, increasing or decreasing the intensity of the beam, and the photodetector 154 provides an electrical output signal related to the measured intensity of the reflected light beam. The electrical signal generated by the photodetector 154 may be transmitted to the controller 144 for evaluation.

[0027] Figure 2 A schematic side view of the upper assembly 210 of the processing chamber 100 is shown according to at least some embodiments of this disclosure. Figure 3 According to at least some embodiments of this disclosure, an enlarged isometric view of an IEP housing assembly 140 is shown. An upper assembly 210 includes the IEP housing assembly 140. In some embodiments, the upper assembly 210 is disposed above a dome 113 and is vertically movable relative to the dome 113. The IEP housing assembly 140 generally includes an IEP housing 204 having an upper end 206 configured to interface with a light source 152 and having an internal cavity 230. A support 212 having a body 216 is disposed around the IEP housing 204 and includes a plurality of arms 220 extending radially outward from the body 216. In some embodiments, the body 216 is annular in shape. In some embodiments, such as Figure 3 As shown, the plurality of arms 220 consists of three arms. In some embodiments, the upper end 206 of the IEP housing 204 includes a central opening 236, and the lower end 240 of the IEP housing 204 includes a second central opening concentric with the central opening 236. In some embodiments, the bracket 212 and the IEP housing 204 are made of plastic.

[0028] In some embodiments, the body 216 includes a plurality of clearance holes 382. In some embodiments, a plurality of screws 310 extend through the plurality of clearance holes 382 to loosely hold the IEP housing within a central opening of the body. In some embodiments, a plurality of biasing members 410 (hereinafter referred to as...) Figure 4 (Discussed in more detail) Extending from the body 216 to the IEP housing 204 to apply a biasing force to the IEP housing 204, thereby holding the IEP housing 204 within the support 212. Multiple biasing members 410 advantageously hold the IEP housing 204 while allowing lateral deflection or side-to-side play relative to the support 212, so that the IEP housing 204 self-aligns in the radial direction relative to the dome 113.

[0029] In some embodiments, the upper assembly 210 includes a first mounting plate 228 coupled to the bracket 212 via corresponding ends 238 of the plurality of arms 220. In some embodiments, the first mounting plate 228 includes an annular body and includes an upper ring 314 and a lower ring 318 extending downward and radially outward from the upper ring 314. In some embodiments, a plurality of mounting tabs 316 extend radially inward from the upper ring 314 and are configured to couple the first mounting plate 228 to the bracket 212.

[0030] In some embodiments, the upper assembly 210 further includes a lamp assembly 232 having a plurality of lamps 252 and coupled to the IEP housing assembly 140. In some embodiments, a second mounting plate 234 is coupled to a first mounting plate 228 and configured to mount the plurality of lamps 252. In some embodiments, the plurality of lamps 252 are disposed within the second mounting plate 234. In some embodiments, the first mounting plate 228 includes a plurality of second mounting tabs 324 extending radially outward from the upper ring 314 and configured to couple the first mounting plate 228 to the second mounting plate 234. In some embodiments, when mounted in the processing chamber 100, an RF coil 126 (discussed in more detail below) is disposed between the bracket 212 and the dome 113. In some embodiments, the RF coil 126 is disposed around the IEP housing 204 such that the IEP housing 204 is within or radially inward of the RF coil 126.

[0031] In some embodiments, a plurality of second biasing members 328 are disposed between the plurality of arms 220 and the first mounting plate 228, and configured to apply force to the bracket 212 to push the bracket 212 toward the dome 113, thereby forcing the IEP housing 204 toward the dome 113 to facilitate alignment of the IEP housing 204 with the dome 113. Examples of the plurality of second biasing members 328 may be springs, etc. In some embodiments, each of the plurality of second biasing members 328 is disposed around a fastener 330 extending through a corresponding one of the plurality of arms 220 and into the first mounting plate 228. In some embodiments, the fastener 330 is a shoulder screw.

[0032] In some embodiments, lens 244 is disposed in the lower end 240 of IEP housing 204. Lens 244 can be any suitable lens that focuses incident light from light source 152 onto substrate 120. In some embodiments, lens 244 is a convex lens. The size or area of ​​the light beam from light source 152 can be large enough to compensate for variations in the surface topography of substrate 120, thereby enabling the etching of high aspect ratio features with small openings, such as through-holes or deep, narrow trenches. Window 142 is aligned with lens 244 such that the light beam from light source 152 can pass through lens 244 and window 142.

[0033] Figure 4 According to at least some embodiments of this disclosure, a cross-sectional side view of a portion of the Interference End Point (IEP) housing assembly is shown. In some embodiments, window 142 is clamped to dome 113 via dome ring 414. When the upper assembly 210 is in a lower position, the lower end 240 of IEP housing 204 extends into dome ring 414. The lower end 240 is generally configured to interface with dome assembly 123 by, for example, receiving dome ring 414. For example, in some embodiments, dome ring 414 includes an angled surface 418 to advantageously facilitate self-alignment between dome ring 414 and IEP housing 204 when the upper assembly 210 is lowered onto dome assembly 123 during installation. In some embodiments, the angled surface 418 extends upward and radially outward.

[0034] In some embodiments, the IEP housing 204 includes an annular notch 440 at its lower end 240. In some embodiments, the annular notch 440 is defined at least partially by an angled surface 444 corresponding to an angled surface 418 of the dome ring 414. In some embodiments, the angled surface 418 extends downward and radially inward. In some embodiments, the annular notch 440 is defined by a substantially horizontal first edge 442, a substantially vertical second edge 446, and an angled surface 433 extending from the first edge 442 to the second edge 446. In some embodiments, the IEP housing 204 includes an upper annular notch 448 at its upper end 206. In some embodiments, the upper annular notch 448 includes an angled surface 452. In some embodiments, the angled surface 452 is disposed radially inward from the annular notch 440 at the lower end 240.

[0035] In some embodiments, a retaining ring 430 is coupled to the IEP housing 204 at its lower end 240 to hold the lens 244 therebetween. The retaining ring 430 is coupled to the IEP housing 204 through a threaded interface therebetween. The first mounting plate 228 is coupled to the bracket 212 through the respective ends of the plurality of arms 220. In some embodiments, the bracket 212 is completely disposed between the upper surface 434 and the lower surface 464 of the first mounting plate 228.

[0036] Figure 5According to at least some embodiments of this disclosure, a cross-sectional side view of the interface between the biasing members 410 of the bracket 212 and the IEP housing 204 is shown. The biasing members 410 may be disposed in an opening 504 of the bracket 212. In some embodiments, each of the biasing members 410 includes a housing 512, a pin 514, and a spring 516. The housing 512 is typically fixed within the opening 504. For example, each opening 504 may include a threaded insert 518 fixed therein. The housing 512 may include a threaded outer surface that engages with the internal threads of the threaded insert 518.

[0037] Pin 514 is movably disposed within opening 528 in housing 512. Spring 516 may be disposed within opening 528 and configured to force pin 514 away from opening 528. When disposed near IEP housing 204, spring 516 may push pin 514 toward outer surface of IEP housing 204, thereby advantageously facilitating self-alignment of bracket 212 with IEP housing 204.

[0038] Figure 6 A simplified top view of the RF coil 126 is shown according to at least some embodiments of this disclosure. In some embodiments, the RF coil 126 is disposed around but not through a central region 604, wherein the dimensions of the central region 604 are designed to prevent interference between the RF coil 126 and the IEP housing assembly 140. Therefore, the RF coil 126 does not extend through the center of the dome 113. In some embodiments, the RF coil 126 may include a split coil assembly having multiple coils, such as a first coil 126a and a second coil 126b. The split coil assembly includes two or more coils arranged in an annular pattern conforming to the shape of the dome 113 around the center of the dome, without extending through the central region 604. The split coil assembly can improve overall critical dimensions and processing uniformity on the substrate being processed. The split coil assembly according to this disclosure also reduces power loss from high-energy charged particles due to poor capacitive coupling and negative impacts on the equipment and processing chamber hardware, thereby improving power efficiency and hardware reliability.

[0039] In some embodiments, the first coil 126a and the second coil 126b are connected at a common point 620 near the central region 604. The first coil 126a and the second coil 126b are connected to the coil power supply 127 through the common point 620. In some embodiments, the lengths of the first coil 126a and the second coil 126b are substantially the same, for example, within about 5% or less. In some embodiments, the RF coil 126 is arranged asymmetrically.

[0040] Although the foregoing describes the implementation of this disclosure, other and further implementations of this disclosure can be designed without departing from the basic scope of this disclosure.

Claims

1. An interferometric endpoint (IEP) housing assembly for endpoint detection in plasma processing, the IEP housing assembly comprising: IEP housing having an upper end configured to interface with a light source and having an internal cavity, wherein the lower end of the IEP housing is configured to interface with a dome assembly of a processing chamber. A bracket having a body disposed around the IEP housing and having a plurality of arms extending radially outward from the body; as well as Multiple biasing members extend from the body to the IEP housing and are configured to retain the IEP housing within the body while allowing lateral deflection.

2. The IEP housing assembly of claim 1, further comprising a first mounting plate coupled to the bracket through respective ends of the plurality of arms.

3. The IEP housing assembly of claim 2, further comprising a plurality of second biasing members disposed between corresponding ends of the plurality of arms and the first mounting plate, and configured to output force on the bracket to hold the IEP housing against the dome assembly.

4. The IEP housing assembly of claim 2, further comprising a second mounting plate coupled to the first mounting plate and configured to mount a plurality of lamps.

5. The IEP housing assembly of claim 4, wherein the first mounting plate includes an upper ring and a lower ring extending downward and radially outward from the upper ring, and further includes a plurality of mounting tabs extending radially inward from the upper ring and configured for coupling the bracket, and a plurality of second mounting tabs extending radially outward from the upper ring and configured for coupling the second mounting plate.

6. The IEP housing assembly as claimed in any one of claims 1 to 5, wherein the body is annular and the plurality of arms are composed of three arms.

7. The IEP housing assembly as claimed in any one of claims 1 to 5, wherein the bracket and the IEP housing are made of plastic.

8. The IEP housing assembly as claimed in any one of claims 1 to 5, wherein the IEP housing includes an annular notch having an angled surface at the lower end of the IEP housing.

9. The IEP housing assembly as claimed in any one of claims 1 to 5, wherein the body includes a plurality of gap holes and further includes a plurality of screws extending through the plurality of gap holes to loosely retain the IEP housing within a central opening of the body.

10. The IEP housing assembly as claimed in any one of claims 1 to 5, wherein each of the plurality of biasing members comprises a housing, a pin, and a spring.

11. The IEP housing assembly as claimed in any one of claims 1 to 5, wherein each of the plurality of second biasing members is disposed around a fastener that extends through a respective one of the plurality of arms and into the first mounting plate.

12. The IEP housing assembly as claimed in any one of claims 1 to 5, wherein the bracket is completely disposed between the upper surface of the first mounting plate and the lower surface of the first mounting plate.

13. The IEP housing assembly as claimed in any one of claims 1 to 5, the IEP housing assembly further comprising a lens disposed in a lower end of the IEP housing, and a retaining ring coupled to the IEP housing at the lower end to clamp the lens therebetween.

14. The IEP housing assembly as claimed in any one of claims 1 to 5, wherein the upper end of the IEP housing includes a central opening, and the lower end of the IEP housing includes a second central opening concentric with the central opening.

15. A processing chamber, the processing chamber comprising: A chamber body that defines an internal volume therein; A dome assembly disposed within the internal volume, wherein the dome assembly includes a dome, a window, and a dome ring configured to clamp the window to the dome; and An upper assembly disposed above the dome, wherein the upper assembly includes the IEP housing assembly as described in any one of claims 1 to 5.

16. The processing chamber of claim 15, further comprising an RF coil disposed between the bracket and the dome, wherein the RF coil comprises a first coil and a second coil disposed around the IEP housing.

17. The processing chamber of claim 15, wherein the window is aligned with a lens disposed at the lower end of the IEP housing.

18. The processing chamber of claim 17, further comprising a lens disposed in the lower end of the IEP housing, and a retaining ring coupled to the IEP housing at the lower end to clamp the lens therebetween.

19. The processing chamber of claim 15, wherein the upper assembly further comprises a lamp assembly coupled to the IEP housing assembly.

20. The processing chamber of claim 15, wherein each of the plurality of biasing members comprises a housing, a pin, and a spring.

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