Elimination of internal reflections in interferometric endpoint detection systems.

Abstract

To provide a method for eliminating internal reflections of endpoint detection system for semiconductor processing.SOLUTION: A method is disclosed for operating an endpoint detection system 164 of a processing chamber having a ceiling 103 formed therein, a substrate support 116 located internal to the processing chamber, and a substrate 120 resting on the substrate support. A transparent panel 204 is located in the ceiling of the processing chamber. The transparent panel is oriented at a first acute angle α relative to the substrate and the substrate support. The transparent panel receives an incident light beam 176 from the endpoint detection system at a second acute angle β relative to the transparent panel. The transparent panel transmits the incident light beam to the substrate within the processing chamber at an angle perpendicular to the substrate and the substrate support.SELECTED DRAWING: Figure 1

Description

background

[0001] (Field) FIELD Embodiments of the present disclosure relate generally to endpoint detection in semiconductor processing, and more particularly to an endpoint detection system and method with reduced reflection of incident and reflected light.

[0002] Description of Related Art Semiconductor device geometries have dramatically decreased in size since their initial introduction several decades ago. Increasing circuit density places additional demands on the processes used to fabricate semiconductor devices. For example, with increasing circuit density, pitch sizes have rapidly decreased to dimensions below 50 nm, while vertical dimensions, such as trench depth, have remained relatively constant. As a result, feature aspect ratios, or height divided by width, have increased. Precise control of the dimensions of these high-density, submicron features is essential for the reliable formation of semiconductor devices.

[0003] Traditionally, semiconductor devices such as transistors and capacitors are formed by patterning the surface of a substrate to define the lateral dimensions of the features and then etching the substrate to remove material and define the features. To form features with desired electrical performance, the feature dimensions must be formed within controlled specifications. As a result, precise patterning of the substrate and subsequent etching are essential for reliable formation of features with desired critical dimensions.

[0004] In integrated circuit manufacturing, layers must be constructed to form high-density semiconductor devices. Therefore, it may be necessary to partially remove one or more layers using a plasma etching process. During plasma etching, a mask is used to transfer a pattern to a target layer disposed on a substrate without etching layers disposed below the target layer. Interferometric endpoint technology is used to partially etch the underlying layer or substrate to a desired depth or thickness. Interferometric endpoint systems use the interference of reflected light waves reflected from various interfaces on the wafer surface to recognize variations in etch depth or film thickness on the surface.

[0005] Interferometers measure the difference between two or more optical paths by overlapping the residual light from both paths to produce interference fringes. A monochromatic or broadband light source is used, reflected from the surface of a complex film stack. Small changes within the wavelength range of the light source can be detected.

[0006] The reflected light is a combination of signals from each layer deposited on the substrate, forming unique interference fringes for each layer. For endpoint detection, the interference fringe patterns can be simulated for the various layers and then compared to the measured signal during etching. This method is very effective and can be used for monitoring and endpoint detection of etching or deposition of substrates with multiple layers on them.

[0007] Transmitted and reflected light typically passes through a nearly flat, transparent window in a plasma etching chamber, while the incident surface of the substrate is etched. Unfortunately, conventional flat interferometer endpoint (IEP) detection windows experience significant internal reflection during etching, reducing sensitivity to metrics on the substrate. A typical method for reducing internal reflection in IEP windows is to employ an anti-reflective coating (ARC) on the window surface. Unfortunately, ARCs only function over a limited range of wavelengths, despite the need to eliminate internal reflections over a wide wavelength range, typically from 200 nm to 800 nm.

[0008] Therefore, there is a need in the art for an effective method for eliminating internal reflections in endpoint detection systems.

[0009]

[0003] Embodiments presented herein provide a method for operating an endpoint detection system, a transparent panel for the endpoint detection system, and a processing chamber having the same. The processing chamber has a ceiling formed therein, a substrate support disposed inside the processing chamber, and a substrate resting on the substrate support. The transparent panel is disposed on the ceiling of the processing chamber and oriented at a first acute angle relative to the substrate and the substrate support. The transparent panel receives an incident light beam from the endpoint detection system at a second acute angle relative to the transparent panel. The transparent panel transmits the incident light beam to the substrate in the processing chamber at an angle perpendicular to the substrate and the substrate support.

[0010] The embodiments presented herein further provide a processing chamber. The processing chamber includes a chamber body having a sidewall and a bottom. A ceiling is mounted on the chamber body, the ceiling and the chamber body defining an interior space of the processing chamber. A substrate support is disposed in the interior space of the processing chamber and configured to support a substrate during processing. The processing chamber further includes an endpoint detection system. The processing chamber further includes a transparent panel mounted on the ceiling, the transparent panel configured to allow the endpoint detection system to interact with the substrate through the transparent panel. The transparent panel is oriented at a first acute angle relative to the substrate and the substrate support. The transparent panel is configured to receive an incident light beam from the endpoint detection system at a second acute angle relative to the transparent panel. The transparent panel is further configured to transmit the incident light beam to the substrate in the processing chamber at an angle perpendicular to the substrate and the substrate support.

[0011] The embodiments presented herein further provide a tilted window suitable for use in a processing chamber endpoint detection system. The tilted window comprises a mounting frame having a body including a first section and a second section extending perpendicularly from the first section. The second section has a top surface and a bottom surface. The top surface of the second section is tilted at a first acute angle relative to the bottom surface of the second section and at a second acute angle relative to the first section. The tilted window further comprises a panel having a body with a top surface, a bottom surface, and a sidewall, the panel being disposed on the mounting frame. The sidewall of the panel is adjacent to the first section of the mounting frame, and the bottom surface of the panel rests on the top surface of the second section of the mounting frame and is oriented at the first acute angle relative to the bottom surface of the second section of the mounting frame.

[0012] The embodiments presented herein further provide a processing chamber. The processing chamber comprises a chamber body having a sidewall and a bottom. A ceiling is mounted on the chamber body, the ceiling and the chamber body defining an interior space of the processing chamber. A substrate support is disposed in the interior space of the processing chamber and configured to support a substrate during processing. The processing chamber further comprises an endpoint detection system. The processing chamber further comprises a tilted window mounted on the ceiling, the tilted window configured to allow the endpoint detection system to interact with the substrate through the tilted window. The tilted window comprises a mounting frame having a body including a first section and a second section extending perpendicularly from the first section. The second section has a top surface and a bottom surface. The top surface of the second section is tilted at a first acute angle relative to the bottom surface of the second section and at a second acute angle relative to the first section. The tilted window further comprises a panel having a body with a top surface, a bottom surface, and sidewalls, the panel being disposed on the mounting frame. The sidewall of the panel is adjacent to the first section of the mounting frame, and the bottom surface of the panel rests on the top surface of the second section of the mounting frame and is oriented at a first acute angle relative to the bottom surface of the second section of the mounting frame. [Brief explanation of the drawings]

[0013] In order that the foregoing features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above will now be made with reference to embodiments, some of which are illustrated in the accompanying drawings. However, since the present disclosure may include other equally effective embodiments, it should be noted that the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be construed as limiting the scope thereof.

[0014] [Figure 1] 1 shows a schematic cross-sectional view of a plasma etching chamber according to one embodiment of the present disclosure. [Figure 2] FIG. 1 is a side view of a tilted window used in an endpoint detection system of a processing chamber according to embodiments of the present disclosure. [Figure 3] FIG. 3 is a top view of the tilting window of FIG. 2. [Figure 4] A method of operating an endpoint detection system for a processing system, the endpoint detection system employing the tilted window of FIGS. 1-3 suitable for use in a processing chamber endpoint detection system. [Figure 5A] 1 is a curve showing the relationship between the magnitude of reflection and wavelength for a conventional window. [Figure 5B] 1 is a comparison of curves showing the relationship between the magnitude of reflection and wavelength for a conventional window and a tilted window. [Figure 6] 1 shows a curve representing the relationship between the magnitude of the normalized amplitude of the tilt window and the depth of the etch recess. [Figure 7A] 1 shows plots of fringe spectrum magnitude versus relative time for tilted and conventional windows. [Figure 7B] 1 shows the fringe curve spectrum magnitude versus wavelength curve for a tilted window compared to a conventional window.

[0015] For ease of understanding, the same reference numerals have been used, wherever possible, to designate identical elements common to the figures. Furthermore, it is contemplated that elements disclosed in one embodiment may be beneficially used on other embodiments described herein without specific description. DETAILED DESCRIPTION

[0016] The tilted windows presented herein can effectively reduce internal reflections over a wide range of wavelengths of interest (e.g., between approximately 200 and 800 nm) without the need for anti-reflection coatings. The dynamic range of IEP systems is improved. Direct benefits of tilted windows include improved control of etch depth and thickness and extended window life. Tilted windows are generally compatible with existing chamber bodies and, therefore, may be retrofitted into nearly any existing plasma processing chamber utilizing an IEP system.

[0017] 1 is a schematic cross-sectional view of a plasma processing chamber 100 according to one embodiment of the present disclosure. Suitable processing chambers include inductively coupled and capacitively coupled plasma etch chambers, such as the SYM3® Etch System available from Applied Materials, Inc., Santa Clara, California, among others. Other types of processing chambers may also be adapted to benefit from the present invention, including, for example, chemical vapor deposition chambers, capacitively coupled parallel plate chambers, and magnetically enhanced ion etch chambers, as well as inductively coupled plasma etch chambers of various designs.

[0018] The processing chamber 100 generally comprises a chamber body 102 and an energy-transparent ceiling 103. The chamber body 102 also has a chamber bottom 107. The chamber body 102 is fabricated from a metal, such as anodized aluminum or stainless steel. The ceiling 103 is attached to the body 102. The ceiling 103 may be flat, rectangular, arched, conical, dome-shaped, or multi-radius shaped. The ceiling 103 is fabricated from an energy-transparent material, such as ceramic or other dielectric material. An induction coil 126 is positioned above the ceiling 103 of the processing chamber 100 and is utilized to energize gases within the chamber 100 during processing.

[0019] The substrate support 116 is disposed within the processing chamber 100 and has a substrate support surface 188 for supporting the substrate 120 during processing. The substrate support 116 may comprise an electrostatic chuck, where at least a portion of the substrate support 116 is electrically conductive and may function as a process bias cathode.

[0020] Process gases are introduced into the process chamber 100 from a process gas source 148 through a gas distributor 122. The gas distributor 122 may be generally located in the ceiling 103 above the substrate support 116 or in the chamber body 102. Mass flow controllers (not shown) for each process gas, or alternatively, for a mixture of process gases, are located between the gas distributor 122 and the process gas source 148 to regulate the respective flow rates of the process gases into the chamber body 102.

[0021] A plasma zone 114 is defined within the chamber body 102 between the substrate support 116 and the ceiling 103. A plasma is formed in the plasma zone 114 from the process gas using a coil power supply 127, which supplies power to an inductive coil 126 to generate an electromagnetic field in the plasma zone 114 via an RF match network 135. The substrate support 116 may include an electrode therein. The electrode is powered by an electrode power supply 128 and generates a capacitive electric field within the processing chamber 100 via the RF match network 125. Typically, RF power is applied to the electrode of the substrate support 116 while the body 102 is electrically grounded. The capacitive electric field is oriented transverse to the plane of the substrate support 116 and influences the directionality of charged species in a more perpendicular direction relative to the substrate 120, providing a more vertically oriented anisotropic etch of the substrate 120.

[0022] The process gases and etchant byproducts are exhausted from the process chamber 100 through an exhaust system 130. The exhaust system 130 may be located at the bottom 107 of the process chamber 100 for removal of the process gases, or may be located in another portion of the body 102 of the process chamber 100. A throttle valve 132 is provided at the exhaust port 134 to control the pressure within the process chamber 100.

[0023] 1 further shows an endpoint detection system 164 coupled to the processing chamber 100. The endpoint detection system 164 may be an interferometric endpoint (IEP) detection system. The endpoint detection system 164 is positioned to interact with the substrate 120 through a portion of the ceiling 103. In one embodiment, the endpoint detection system 164 is positioned to interact with the peripheral portion of the substrate through a portion of the ceiling 103 that is offset from the center of the ceiling 103. In this manner, the endpoint detection system 164 has a direct line of sight to probe the peripheral surface of the substrate 120.

[0024] The endpoint detection system 164 generally includes a light source 166, a collimating assembly 168, and a photodetector 170. The light source 166 is configured to emit a light beam. The collimating assembly 168 is configured to focus the light beam into an incident light beam 176. The incident light beam 176 passes through the ceiling 103 in a direction perpendicular to the substrate support surface 188 and illuminates an area or spot 180 on the surface of the substrate 120. The incident light beam 176 is reflected by the surface of the substrate 120 to form a reflected light beam 178. At least a portion of the reflected light beam 178 is directed in a direction perpendicular to the substrate support surface 188 and returns through the ceiling 103 to the photodetector 170. The photodetector 170 is configured to measure the intensity of the reflected light beam 178. The computer system 172 processes the spectrum using advanced spectral analysis techniques, such as calculating a portion of the real-time measured waveform spectrum of the reflected light beam 178 reflected from the beam spot 180 on the substrate 120 and comparing that spectrum to stored characteristic waveform patterns.

[0025] The light source 166 comprises a monochromatic or polychromatic light source that generates an incident light beam 176 used to illuminate a beam spot 180 on the substrate 120. The intensity of the incident light beam 176 is selected to be high enough so that the reflected light beam 178 has a measurable intensity. In one alternative embodiment, the light source 166, such as a Xe lamp, provides polychromatic light and produces an emission spectrum of light with wavelengths from about 200 nm to about 800 nm. The polychromatic light source 166 may be filtered to select the frequencies that make up the incident light beam 176. A color filter may be placed in front of the photodetector 170 to filter out all wavelengths except the wavelength of light of interest, and then measure the intensity of the reflected light beam 178 that enters the photodetector 170. The light source 166 may also comprise a monochromatic light source, such as a He-Ne or Nd-YAG laser, to provide light of a selected wavelength.

[0026] One or more focusing lenses 174a, 174b may be used to collimate the incident light beam 176 from the light source 166 to form a beam spot 180 on the substrate surface and to focus the reflected light beam 178 back onto the active surface of the photodetector 170. The size or area of ​​the beam spot 180 should be large enough to compensate for variations in the surface topography of the substrate 120 and device design features. This allows for etch endpoint detection at the target depth for design features with small openings, such as vias or narrow trenches, which may be densely packed or isolated. The area of ​​the reflected light beam should be large enough to activate a large portion of the active light-detecting surface of the photodetector 170.

[0027] The incident light beam 176 and the reflected light beam 178 are directed through a transparent, tilted window 182 of the processing chamber 100. The tilted window 182 allows both light beams 176, 178 to enter and exit the processing environment of the processing chamber 100 substantially without internal reflection. The tilted window 182 includes a substantially flat, transparent panel 204. When the tilted window 182 is positioned within the substantially flat, horizontal ceiling 103 of the processing chamber 102, the flat, transparent panel 204 of the tilted window forms a first acute angle α between the transparent panel 204, the horizontal ceiling 103, the substrate support surface 188, and the substrate 120. The first acute angle may be in the range of 2° to 5°, preferably 3°. The substrate support surface 188 of the substrate support 116 on which the substrate 120 rests is aligned parallel to the ceiling 103 and perpendicular (90°) to both light beams 176, 178. At the same time, the panel 204 of the angled window 182 forms a second acute angle β with both light beams 176, 178. In one embodiment, β is in the range of 85° to 88°, preferably 87°. Therefore, no internal reflection occurs from either the top surface 207 of the panel 204 or the bottom surface 224 of the panel 204.

[0028] In one embodiment, a transparent panel 204 disposed on the ceiling 103 of the processing chamber 100 is configured to receive an incident light beam from the endpoint detection system 164 at a second acute angle β relative to the panel 204, the panel 204 being oriented at a first acute angle α relative to the substrate 120 and the substrate support 116. The panel 204 is further configured to transmit the incident light beam to the substrate 120 in the processing chamber 100 at an angle perpendicular to the substrate 120 and the substrate support 116. The panel 204 is further configured to receive a reflected light beam from the substrate 120 at the second acute angle. The panel 204 is further configured to transmit the reflected light beam to the endpoint detection system 164 at an angle perpendicular to the endpoint detection system 164.

[0029] The diameter of the beam spot 180 is typically about 2 mm to about 10 mm. However, if the beam spot 180 encompasses a large, isolated area of ​​the substrate containing only a few etched features, it may be necessary to use a smaller beam spot to focus on the feature of interest. Thus, the size of the beam spot may be optimized depending on the design features of a particular device.

[0030] If desired, the optical beam positioner 184 may be used to move the incident optical beam 176 across the substrate 120 to locate the appropriate portion of the substrate surface where the beam spot 180 is located to monitor the etching process. The optical beam positioner 184 may include one or more primary mirrors 186 that may be rotated through small angles to direct the optical beam from the optical source 166 to various locations on the substrate surface. Additional secondary mirrors (not shown) may be used to block the reflected optical beam 178 that is reflected from the surface of the substrate 120 and focused onto the optical detector 170. The optical beam positioner 184 may also be used to scan the optical beam in a raster pattern across the surface of the substrate 120. In this alternative embodiment, the optical beam positioner 184 includes a scanning assembly consisting of a movable stage (not shown) on which the optical source 166, collimating assembly 168, and detector 170 are mounted. The movable stage moves at set intervals by a drive mechanism (such as a stepping motor) to move the beam spot 180 over the entire surface of the substrate 120 .

[0031] The photodetector 170 comprises a light-sensitive electronic component, such as a charge-coupled device (CCD), photodiode, or phototransistor, that provides a signal in response to the measured intensity of the reflected light beam 178 reflected from the surface of the substrate 120. The signal may take the form of a change in the level of current flowing through the component or a change in voltage applied to the component. The reflected light beam 178 undergoes constructive and / or destructive interference, which increases or decreases the intensity of the reflected light beam, causing the photodetector 170 to provide an electrical output signal related to the measured intensity of the reflected light beam 178. The electrical output signal is displayed as a function of time to provide a waveform spectrum having a number of waveform patterns corresponding to the varying intensity of the reflected light beam 178.

[0032] A computer program on computer system 172 compares the shape of the measured waveform pattern of reflected light beam 178 with a stored characteristic waveform pattern and determines the endpoint of the etch process when the measured waveform pattern is the same as the characteristic waveform pattern. The period of the interference signal as a function of time may then be used to calculate depth and etch rate. The program may also operate on trends in the interference to detect characteristic patterns, such as inflection points. The operations may be simple mathematical operations, such as evaluating a moving derivative to detect inflection points.

[0033] Although the endpoint detection system 164 may be positioned to interact with the substrate 120 through a portion of the substantially horizontal ceiling 103 of the processing chamber 100, in some embodiments, the endpoint detection system 164 may be positioned horizontally above the chamber 100 and may further include a folding mirror above the chamber 100 to bend the incident light beam 176 and the reflected light beam 178 from a vertical position to a horizontal position. A transparent tilting window 182 may be positioned on the side of the chamber 100 or on the bottom of the chamber 100.

[0034] 2 is a side view of the tilted window 182 used in the endpoint detection system 164 of the processing chamber 100. The tilted window 182 includes a mounting frame 202 and a panel 204 disposed on the mounting frame 202. The mounting frame 202 has a first section 206 and a second section 208 extending from the first section 206. The first section 206 has a substantially flat top surface 210 and sidewalls 212 that extend vertically to an intersection 214 with the top surface 216 of the second section 208. The second section 208 has the top surface 216, substantially vertical sidewalls 218, and a bottom surface 220 (forming the bottom surface 220 of the mounting frame 202).

[0035] The panel 204 has a top surface 222 and a bottom surface 224. In one embodiment, the top surface 222 is parallel to the bottom surface 224. The panel 204 also includes a near outer edge 226 and a far outer edge 228. In one embodiment, the near outer edge 226 and the far outer edge 228 are oriented at a 90° angle relative to the top surface 222 and the bottom surface 224. The panel 204 is configured to rest on the top surface 216 of the second section 208 of the mounting frame 202. In one embodiment, the angle of the top surface 222 of the panel 204 relative to the top surface 210 of the first section 206 of the mounting frame 202 is a first acute angle α. The top surface 216 of the second section 208 is inclined at the first acute angle α relative to the bottom surface 220 of the second section 208 and is inclined at a second acute angle β relative to the first section 206. In another embodiment, the near outer edge 226 and the far outer edge 228 are oriented at a second acute angle β relative to the bottom surface 220 of the second section 208 of the mounting frame 202 to fit snugly against the side wall 212 of the first section 206 and the top surface 216 of the second section 208 of the mounting frame 202.

[0036] 3 is a top view of the tilting window 182 of FIG. 2. In one embodiment, the panel 204 is substantially circular, forming a disk within the mounting frame 202. In other embodiments, the panel 204 may be substantially square, rectangular, triangular, oval, or the like. In one embodiment, the panel 204 may be made of sapphire, fused silica, or MgF2. It is contemplated that other transparent materials may also be used.

[0037] In one embodiment, the mounting frame 202 is substantially circular, forming an annular ring around the panel 204. In other embodiments, the mounting frame 202 may be substantially square, rectangular, triangular, oval, or the like. In one embodiment, the mounting frame 202 may be made of metal or ceramic. It is contemplated that other transparent or opaque materials may also be used. The material of the mounting frame 202 may be different from the material of the panel 204. However, a one-piece design facilitates maintaining a vacuum seal between the mounting frame 202 and the panel 204.

[0038] 4 illustrates a method 400 for operating an endpoint detection system 164 in a processing chamber 100, the endpoint detection system employing a tilted window 182 with a transparent panel 204, as shown in FIGS. 1-3. The processing chamber 100 includes a ceiling 103 formed thereon, a substrate support 116 disposed within the processing chamber 100, and a substrate 120 resting on the substrate support 116. In block 405, a transparent panel 204 disposed on the ceiling 103 of the processing chamber 100, the panel 204 oriented at a first acute angle α relative to the substrate 120 and the substrate support 116, receives an incident light beam from the endpoint detection system 164 at a second acute angle β relative to the panel 204. In block 410, the panel 204 transmits the incident light beam to the substrate 120 within the processing chamber 100 at a perpendicular angle relative to the substrate 120 and the substrate support 116. At block 415, the panel 204 receives the reflected light beam from the substrate 120 at a second acute angle. At block 420, the panel 204 transmits the reflected light beam to the endpoint detection system 164 at an angle perpendicular to the endpoint detection system 164.

[0039] FIG. 5A shows a curve representing the magnitude of reflection versus wavelength for a conventional window. FIG. 5B compares the curves representing the magnitude of reflection versus wavelength for a conventional window compared to a tilted window 182. Curve 502 displays the magnitude of reflection from the conventional window, and curve 504 displays the magnitude of reflection from the tilted window 182. There is very little reflection from the tilted window compared to approximately 20K counts (counts are a unit of spectrometer output) for the conventional window. The IEP spectrum from the wafer with the tilted window consists of the spectrum reflected only from the substrate, without the 20K count background reflection from the conventional IEP window. The tilted window 182 significantly improves IEP tuning.

[0040] 6 shows curves representing the relationship between normalized amplitude magnitude and etch recess depth for a tilted window (curve 602) and a conventional window (curve 604). The range of recess depth controlled by using the etch IEP algorithm with a tilted window can be reduced by approximately 10 Å based on laboratory test results for WEB (WEB stands for W (tungsten) etchback) chips. Using a tilted window, etch depth variations within 5 Å to 20 Å can be achieved.

[0041] Figure 7A shows curves representing the magnitude of the fringe curve spectrum versus relative time for a tilted window (curve 702) and a conventional window (curve 704). Figure 7B shows curves representing the magnitude of the fringe curve spectrum versus wavelength for a tilted window (curve 706) and a conventional window (curve 708). As can be seen from these curves, the IEP tuning depth (sensitivity) is increased by approximately 80% for the tilted window curves 702 and 706 compared to the conventional window curves 704 and 708. This is desirable because spectral analysis relies on calculating on-wafer metrics (the dimensions of features on the wafer surface), and a stronger spectral response to subtle on-wafer metric changes results in a higher signal-to-noise ratio and more accurate results for the on-wafer metrics.

[0042] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be made without departing from the basic scope thereof, which scope is defined by the following claims.

Claims

1. a ceiling formed in the etching processing chamber; The device has a body including a first section and a second section extending perpendicularly from the first section. a substantially circular mounting frame, the second section having a top surface and a bottom surface, The top surface of the second section is inclined at a first acute angle relative to the bottom surface of the second section, and the first section a mounting frame inclined at a second acute angle relative to an inner sidewall of the frame; a substrate support disposed within the etching processing chamber; and a substrate resting on a substrate support. A method of a transparent panel disposed in the ceiling of the etching processing chamber, the transparent panel being adapted to connect the substrate and the substrate support; A transparent panel oriented at a first acute angle to the incident light beam from the endpoint detection system at a second acute angle relative to the transparent panel, the transparent panel includes a body including a top surface, a bottom surface, and side walls; The transparent panel is placed in a substantially circular mounting frame, a sidewall of the transparent panel adjacent to the first section of the substantially circular mounting frame; a bottom surface of the transparent panel disposed on the top surface of the second section of the substantially circular mounting frame is oriented at a first acute angle relative to the bottom surface of the second section of the substantially circular mounting frame; the substantially circular mounting frame forms an annular ring around the transparent panel; A substantially circular mounting frame and a transparent panel are mounted on the substantially circular mounting frame. configured to maintain a vacuum seal between the frame and the transparent panel; The essentially circular mounting frame exposes the center of the transparent panel, the center of the transparent panel being coincident with the radial center of the inner sidewall of the first section of the mounting frame; A transparent panel directs the incident light beam into the processing chamber at a normal angle to the substrate and substrate support. transmitting the light to a substrate within the A reflected light beam having an intensity corresponding to the size of the opening in the substrate is received by a photodetector. a process dimension including a target depth; The dimensions including the target depth and the etching rate are calculated based on the waveform spectrum of the reflected light beam. Calculating the magnitude of the waveform spectrum corresponds to the intensity.

2. A step in which a transparent panel receives the reflected light beam from the substrate at a second acute angle; The method of claim 1 further comprising the step of: a transparent panel transmitting the reflected light beam to an endpoint detection system.

3. The method described in claim 2, wherein the transparent panel does not cause reflection of the incident light beam or the reflected light beam.

4. The method of claim 1 , wherein the second acute angle is equal to 90° minus the first acute angle.

5. The method of claim 4 , wherein the first acute angle is in the range of 2° to 5°.

6. 2. The method of claim 1, wherein the first acute angle is 3 degrees and the second acute angle is 87 degrees.

7. 1. An etch processing chamber comprising: an etching chamber body having a sidewall and a bottom; a ceiling mounted on the chamber body, the ceiling and the chamber body forming a processing chamber; The ceiling that defines the interior space of a substrate support disposed in the interior space of the processing chamber and configured to support the substrate during processing; With the body, an endpoint detection system; The device has a body including a first section and a second section extending perpendicularly from the first section. a substantially circular mounting frame, the second section having a top surface and a bottom surface, The top surface of the second section is inclined at a first acute angle relative to the bottom surface of the second section, and the first section a mounting frame inclined at a second acute angle relative to an inner sidewall of the frame; It has a transparent panel attached to the ceiling, an endpoint detection system configured to interact with the substrate through the transparent panel; the transparent panel is oriented at a first acute angle relative to the substrate and the substrate support; the transparent panel includes a body including a top surface, a bottom surface, and side walls; The transparent panel is placed in a substantially circular mounting frame, a sidewall of the transparent panel adjacent to the first section of the substantially circular mounting frame; a bottom surface of the transparent panel disposed on the top surface of the second section of the substantially circular mounting frame is oriented at a first acute angle relative to the bottom surface of the second section of the substantially circular mounting frame; the substantially circular mounting frame forms an annular ring around the transparent panel; A substantially circular mounting frame and a transparent panel are mounted on the substantially circular mounting frame. configured to maintain a vacuum seal between the frame and the transparent panel; The essentially circular mounting frame exposes the center of the transparent panel, the center of the transparent panel is the same as the radial center of the inner sidewall of the first section of the mounting frame; the transparent panel receives an incident light beam from the endpoint detection system at a second acute angle relative to the transparent panel; the transparent panel transmits the incident light beam to the substrate within the etching processing chamber at an angle normal to the substrate and the substrate support; The endpoint detection system receiving, at a photodetector, a reflected light beam having an intensity corresponding to a dimension of the opening in the substrate; The computer calculates the target depth and edge based on the waveform spectrum of the reflected light beam. The etching rate is calculated and the waveform spectrum corresponds to the intensity in the etching chamber.

8. The transparent panel is receiving the reflected light beam from the substrate at a second acute angle; The processing chamber of claim 7 , further configured to transmit the reflected light beam to an endpoint detection system.

9. 8. The processing chamber of claim 7, wherein the second acute angle is equal to 90 degrees minus the first acute angle.

10. 10. The processing chamber of claim 9, wherein the first acute angle is in the range of 2 degrees to 5 degrees.

11. 9. The processing chamber of claim 8, wherein the first acute angle is 3 degrees and the second acute angle is 87 degrees.

12. 1. A tilted window suitable for use in an endpoint detection system for a plasma etch chamber, comprising: The device has a body including a first section and a second section extending perpendicularly from the first section. A mounting frame for the second section having a top surface and a bottom surface; The top surface of the second section is inclined at a first acute angle relative to the bottom surface of the second section. a mounting frame inclined at a second acute angle relative to an inner sidewall of the section; A panel having a body with a top surface, a bottom surface, and a side wall, The panel is placed in a mounting frame, a side wall of the panel adjacent to the first section of the mounting frame; The bottom of the panel rests on the top of the second section of the mounting frame. a panel oriented at a first acute angle with respect to the bottom surface of the second section; The panel is a transparent panel provided parallel to the bottom wall of the second section of the mounting frame. Comparatively, it reduces reflection of light beams over the wavelength range of 200 nm to 800 nm; The endpoint detection system detects the plasma etching temperature based on the waveform spectrum of the reflected light beam. The trench depth of the substrate placed in the chamber is calculated, and the waveform spectrum corresponds to the intensity. The mounting frame is an integrated design, and there is a vacuum seal between the mounting frame and the panel. Maintain a tilted window.

13. 13. The tilting window of claim 12, wherein the second acute angle is equal to 90 degrees minus the first acute angle.

14. 13. The tilting window of claim 12, wherein the first acute angle is in the range of 2° to 5°.

15. 13. The tilting window of claim 12, wherein the second acute angle is in the range of 85° to 88°.

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