KR20080003158U - Plasma reactor with nozzles and variable process gas distribution - Google Patents

Abstract

A plurality of gas injection nozzles are disclosed that are modularly coupled to a gas distribution ring in a plasma reactor for processing a workpiece such as a mask or wafer. The gas injection nozzle is formed in a hollow cylindrical body having a first outer diameter portion and a second outer diameter portion forming a tip, in a longitudinal direction passing through the body, and A first passageway passing through the first outer diameter portion and extending at least into the second outer diameter portion, and a second aligned in the same axis as the first passageway and extending longitudinally from an end of the first passageway to an end of the tip; And a passage, wherein the first outer diameter portion is larger than the second outer diameter portion.

Description

Plasma reactor with nozzles and variable process gas distribution {PLASMA REACTOR WITH NOZZLES AND VARIABLE PROCESS GAS DISTRIBUTION}

The present invention relates to a plasma reactor with nozzles and variable process gas distribution.

Photolithographic mask fabrication for ultra high density integrated (ULSI) circuits requires a higher level of etching uniformity than in semiconductor wafer processing. Typically a single mask pattern occupies 4 inches squared area on a quartz mask. The image of the mask pattern is focused to the area of a single die (1 inch squared) on the wafer and then stepped across the wafer to form a single image for each die. Before etching the mask pattern to the quartz mask, the mask pattern is recorded by the scanning electron beam, which is a time consuming process that dramatically increases the cost of a single mask. The mask etching process is not uniform over the entire mask surface. In addition, the e-beam on which the photoresist pattern is recorded is uneven by itself, and when the feature size on the wafer is 45 nm, the pattern dimension (e.g., line width) is about 2-3 nm over the entire mask. It shows a large deviation. (This deviation is, for example, 3σ deviation for all measured line widths.) This non-uniformity in photoresist pattern size can vary between different mask sources or customers. The mask etching process does not increase this deviation above 1 nm, so the deviation in the etched mask pattern does not exceed 3-4 nm. This stringent requirement is due to the use of diffraction effects in the quartz mask pattern to achieve a clear image on the wafer. It is difficult to meet these conditions with current technology. It will also be more difficult in future technologies that will require a wafer feature size of 22 nm. This problem is compounded with the etching bias phenomenon, so that the reduction of the photoresist pattern during the mask etching causes the reduction of the line width (pattern size) of the pattern etched on the quartz mask. These problems are inherent in the mask etching process, since the etching selectivity of conventional etching materials (e.g., quartz, chromium, molybdenum silicide) for the photoresist is typically less than 1, so the mask photoresist pattern is a mask It is etched during the etching process.

Certain mask patterns need to etch the periodic openings exactly to a defined depth into the quartz mask, which is important to achieve extremely fine phase alignment of the interfering light beam during exposure of the wafer by the mask. For example, in one form of phase shift mask, each line is defined by a chrome line and a thin quartz line exposed on both sides of the chrome line, with the quartz line on one side being directed to light passing through the unetched quartz line. Etching is only etched to a precise depth that provides 180 degree phase shift of the light. In order to precisely control the etching depth of quartz, the etching process should be strictly monitored by stopping the etching process periodically to measure the etching depth of quartz. Each such inspection removes the mask from the mask etch reactor chamber, removes the photoresist, measures the etch depth, and then estimates the etch process time remaining until reaching the target depth based on the elapsed etch process time. It is necessary to deposit the harmful photoresist, e-beam write the mask pattern to the resist, insert the mask back into the mask etching chamber, and start the etching process again. Estimating the etching time remaining until reaching the desired depth is unreliable because it assumes that the etching rate remains stable and uniform. This cumbersome process involves not only low productivity and high cost, but also an increase in the possibility of contamination or damage of the photoresist pattern. However, due to the requirement for precisely controlled etching depth, there seems to be no way to solve this problem.

Small tolerances in pattern size variation require an etch rate that is extremely uniformly distributed over the mask surface. In masks requiring exact etch depth into the quartz material, there are two critical dimensions, one of which is line width and the other of which is etch depth, and uniformity for the two types of pattern size. The castle needs a uniform etch rate distribution over the mask. Non-uniformity in the etch rate distribution can be achieved by using a source power applicator capable of varying the radial distribution of plasma ion density, such as an inductive source power applicator consisting of internal and external coil antennas on top of the wafer. Can be reduced. However, this solution can only solve the problem of symmetrical nonuniformity, ie center-high or center-low etch rate distribution. Substantially, the nonuniformity of the etch rate distribution can be asymmetric, such as a high etch rate at one corner of the mask. A more fundamental limitation is that the mask etching process, which tends to have an extremely low centered distribution as above the etch rate, which is an adjustable feature such as an inductive power applicator with an inner coil and an outer coil, It is not possible to convert the etch rate distribution off.

Another problem with non-uniform etch rate distributions is that the etch rate distribution tends to change significantly between different reactors of the same design, and also in the same reactor whenever important or consumable parts are replaced, such as replacing gas distribution nozzles. The etch rate distribution can change significantly at. The etch rate distribution is very sensitive to small changes in the properties of the parts being replaced, along with unexpected changes due to consumable replacement. Another related challenge is the easy replacement of critical components such as gas distribution nozzles.

Plasma reactors for processing workpieces, such as masks or wafers, include a vacuum chamber including a gas distribution ring with one or more gas injection nozzles, wherein a gas injection nozzle is disclosed herein.

In one embodiment, a gas injection nozzle is disclosed that is adapted to be modularly coupled to a gas distribution ring in a plasma reactor. The gas injection nozzle is formed in a hollow cylindrical body having a first outer diameter portion and a second outer diameter portion forming a tip, in a longitudinal direction passing through the body, and A first passageway passing through the first outer diameter portion and extending at least into the second outer diameter portion, and a second aligned in the same axis as the first passageway and extending longitudinally from an end of the first passageway to an end of the tip; And a passage, wherein the first outer diameter portion is larger than the second outer diameter portion.

In another embodiment, a gas injection nozzle is disclosed that is adapted to be modularly coupled to a gas distribution ring of a plasma reactor. The gas injection nozzle has a hollow cylindrical body having a first outer diameter portion and a second outer diameter portion smaller than the first outer diameter portion, disposed through the outer diameter portion, and 90 degrees into a second passage disposed through the second diameter portion. A first passage moving to the boundary, and a radial face connecting the first outer diameter portion to the second outer diameter portion, wherein the first outer diameter portion is about 50% larger than the second outer diameter portion.

In another embodiment, a gas injection nozzle is disclosed that is adapted to be modularly coupled to a gas distribution ring in a plasma reactor. The gas injection nozzle has a hollow cylindrical body having a first outer diameter portion and a second outer diameter portion forming a tip, wherein the first outer diameter portion is larger than the second outer diameter portion, and is formed in a longitudinal direction passing through the body, and A first passageway passing through the first outer diameter portion and extending into at least the second outer diameter portion, aligned at the same axis as the first passageway, moving at a 90 degree boundary with the first passageway, at the end of the first passageway A second passage extending longitudinally to an end of the tip, and a side passage located in the second outer diameter portion connected to the first passage, the first passage being four times greater than the direct passage of the second passage; Have a bigger hit.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the exemplary embodiments of the present invention can be achieved and understood in detail, the more detailed description of the invention, briefly summarized above, can be made with reference to the embodiments of the invention shown in the accompanying drawings. It is to be understood that certain well known processes are not discussed herein in order to not obscure the present invention.

To help understand the present invention, the same reference numerals are used to denote the same components commonly used in the drawings. Components and features in one embodiment may be usefully incorporated in other embodiments without further recitation. It is to be noted, however, that the appended drawings merely illustrate exemplary embodiments of the invention, and are not intended to limit the scope of the invention, and other equivalent effective embodiments of the invention may be tolerated.

Enhanced RF  With uniformity Cathode  :

The inventors found that one of the causes of the non-uniform etch rate distribution in the mask etching process is the presence of RF electrical non-uniformity in the support pedestal or cathode that holds the mask in the plasma reactor in which the mask etching process is performed. . RF bias power is applied to the pedestal to control the plasma ion energy at the mask surface, and RF source power is applied to the overhead coil antenna to generate plasma ions, for example. The RF bias source controls the electric field at the mask surface that affects ion energy. Since ion energy at the mask surface affects the etch rate, RF electrical non-uniformity at the pedestal produces a non-uniform etch rate distribution on the mask surface. We have found several sources of RF non-uniformity in the pedestal. One cause is the titanium screws that hold the aluminum pedestal (cathode) and the aluminum fixture plate. These screws create nodes in the electric field pattern across the surface of the pedestal (and thus the mask surface) because their electrical properties differ from those of the aluminum cathode. Another cause is a nonuniform distribution of conductivity between the cathode and the installation plate. Electrical conduction between the facility plate and the cathode is mainly limited to the periphery of the plate and the cathode. This may be due at least in part to the bowing of the cathode induced by vacuum pressure during the plasma process. Conduction near these perimeters may be uneven due to various factors, such as irregular tightening of the titanium screws and / or differences in surface finish near the perimeter of the plate or pedestal. We solved this problem by introducing several features that enhance RF electrical uniformity across the front of the pedestal. First, RF field nonuniformity or discontinuity caused by the presence of titanium screws in an aluminum cathode is solved by providing a continuous titanium gas injection ring that surrounds the head of all titanium screws and extends around the top surface periphery of the cathode. The change in conductivity due to the surface difference or irregular tightening of the titanium screws provides a conductive nickel plating on the facing peripheral surface of the fixture plate and cathode, and the RF gasket between the fixture plate and the cathode-tightly squeezed between them at these perimeters. Is solved by introducing

Referring to FIG. 1, a plasma reactor for etching a pattern in a mask includes a vacuum chamber 10 surrounded by side walls 12 and an upper ceiling 14 and is evacuated by a vacuum pump 15 that controls chamber pressure. do. Mask support pedestal 16 within chamber 10 supports mask 18. As disclosed later herein, the mask typically consists of a quartz substrate, and may further include additional mask thin film layers, such as chromium and molybdenum silicide, on the quartz substrate top surface. Also provided is a pattern-defining layer, which may be a hardmask or photoresist formed of a chromium layer. In other types of masks, the quartz substrate has no other top layer except for the photoresist pattern.

The plasma source power is applied by the upper inner and outer coil antennas 20, 22 driven by the respective RF source power generators 24, 26 via the RF matching circuits 28, 30, respectively. Sidewall 12 may be aluminum or other metal connected to ground, but ceiling 14 is typically an insulating material that allows inductive coupling of RF power from coil antennas 20 and 22 into chamber 10. Process gas is injected from the gas panel 36 via a gas manifold 34 through injection nozzles 32 evenly spaced above the sidewall 12. The gas panel 36 is composed of an output valve or flow control device 42 connected to the manifold 34 and several gas sources 38 connected through individual valves or flow control devices 40.

The mask support pedestal 16 consists of a metal (eg aluminum) cathode 44 supported on a metal (eg aluminum) fixture plate 46. The cathode 44 includes internal cooling or heating fluid flow passages (not shown) that are supplied and exhausted by supply and discharge ports (not shown) in the facility plate 46. RF bias power is applied from the RF bias power generator 48 to the installation plate through the RF impedance matching circuit 50. RF bias power is conducted to the top surface of the cathode 44 beyond the boundary between the facility plate 46 and the cathode 44. The cathode 44 comprises a central plateau 44a on which a rectangular quartz mask or substrate 18 is supported. As will be shown below, the pleto 44a is slightly smaller so that a small portion or lip 18a around the mask extends a short distance past the pleto 44a, but the pleto dimension is typically the dimension of the mask 18. Similar to

The pedestal gas injection ring 52 surrounding the pleto 44a forms the cover gas injection ring 52a and the remaining 3/5 of the gas injection ring 52 forming about two fifths of the gas injection ring 52. It is divided into a capture gas injection ring 52b that forms (in the form of a wedge or pie section shown in FIG. 2B or 7). The capture gas injection ring 52b includes a shelf 54 in which the lip 18a of the mask 18 is located. Three lift pins 56 (only one of which can be seen in FIG. 1) raise the capture gas injection ring 52b, which is a lip 18a each time the mask 18 needs to be removed from the support pedestal 16. The mask 18 is raised. The pedestal gas injection ring 52 has different electrical characteristics selected to match the RF impedance at the frequency of the bias power generator 48, represented by the combination of the quartz mask 18 and the aluminum pleto 44a. It consists of layers 53 and 55 of material. (The cover and the capture rings 52a and 52b are composed of different layers 53 and 55.) Also, the upper surface of the capture gas injection ring 52 is coplanar with the upper surface of the mask 18, and thus the mask ( A large uniform surface extending beyond the edge of 18) promotes a uniform electric field and sheath voltage on the surface of the mask 18 during the plasma process. Typically, this condition is satisfied when the lower gas injection ring layer 55 is quartz and the upper gas injection ring layer 53 is ceramic, such as alumina. The process controller 60 controls the gas panel 36, the RF generators 24, 26, 48 and the wafer handling apparatus 61. The wafer processing apparatus may include a lift servo 62 connected to the lift pin 56, a robot blade arm 63, and a slit valve 64 on the sidewall 12 of the chamber 10.

A series of evenly spaced titanium screws 70 secure them to each other along the perimeter of the cathode 44 and fixture plate 46. Due to the electrical difference between the aluminum cathode / facility plates 44 and 46 and the titanium screw 70, the screw 70 provides discontinuous non-uniformity in the RF electric field at the top of the cathode 44. Differences in the opposing surfaces of cathode 44 and fixture plate 46 create non-uniformity in the conductivity between them along the periphery of cathode 44 and fixture plate 46, providing a non-uniformity corresponding to the RF electric field. do. Since the cathode 44 tends to be bent upwards (due to the chamber vacuum) during the plasma process, the major electrical contact between the cathode 44 and the fixture plate 46 is made along these periphery. In order to reduce the sensitivity of the electrical conductivity between the cathode 44 and the installation plate 46 due to (a) differences in the tightness of the plurality of titanium screws 70 and (b) differences in the surface properties, nickel and Similarly, an annular thin film 72 of highly conductive material is deposited on the periphery of the lower surface 44b of the cathode 44, and a corresponding annular thin film 74 made of (eg) nickel is installed on the installation plate 46. Is deposited on the periphery of top surface 46a of the substrate. The nickel films 72, 74 are aligned to each other so that the two annular nickel films 72, 74 constitute opposing contact surfaces of the pedestal 44 and the fixture plate 46, with a very constant electrical conductivity therebetween. Gives the distribution of. In addition, the improvement in uniform electrical conductivity is realized by providing an annular groove 76 along the periphery of the bottom surface of the cathode 44 and placing the conductive RF gasket 80 in the groove 76. Optionally, a similar annular groove 78 may be provided on the top surface of the facility plate 46 in line with the groove 76. RF gasket 80 may be a suitable conventional variant, such as a metal helix that is compressed as the cathode 44 and fixture plate 46 are compressed with each other and tightened with screws 70. In order to reduce or eliminate non-uniform points of the field distribution that are likely to occur at the head of the titanium screw 70, a continuous titanium gas injection ring 82 is provided in the annular groove 84 at the periphery of the upper surface of the cathode 44. Is located.

2A shows a mask support pedestal 16 and a lift assembly 90 underlying it. The lift assembly 90 includes a lift spider 92 driven by a pneumatic actuator or lift servo 94 and three lift pins 56 positioned on the lift spider 92. Lift pins 56 are directed to lift bellows 96 including ball bearings 98 for extremely flat, frictionless movement (to reduce contamination caused by wear). 2B shows the cathode 44 including the mask 18 in the raised position with the capture gas injection ring 52b. The space formed by the separation of the cover and capture rings 52a, 52b when the mask 18 is raised allows access to the mask 18 by the robot blade.

An extremely low center of etch rate distribution problem across the surface of the mask 18 is solved by changing the distribution of the electrical properties (eg, electrical permittivity) of the cathode pleto 44a. This is achieved in one embodiment by providing a central insert 102 and an outer insert 104 surrounding the top surface of the pleto 44a, the two inserts having a planar surface continuous with the pedestal gas injection ring 52. Forming and electrically different materials. For example, to reduce the tendency of the etch rate distribution to be extremely low centered, the central insert 102 may be a conventional material (eg, aluminum) and the outer insert 104 may be an insulating material (eg, Ceramics such as alumina). This conductive form of the central insert 102 provides a very low impedance path to RF current, increasing the ion energy and etching rate at the center of the mask 18, while the insulating outer insert 104 has a higher impedance. Decreases the etch rate at the periphery of the mask 18. This combination improves the etch rate distribution, making the etch rate distribution more uniform. Along with these characteristics, fine adjustment of the etch rate distribution can be performed by adjusting the relative RF power levels applied to the inner and outer coil antennas 20, 22. The radial distribution variation in plasma ion density required to achieve a uniform etch rate distribution is reduced to a very small amount, which is within the RF power distribution capability between the inner and outer coils 20, 22 to obtain a uniform etch rate distribution. 3 is a top view of the inner and outer inserts 102, 104. In an alternate embodiment, inserts 102 and 104 are insulators having different dielectric constants (electrical permittivity). 4 and 5 show a design in accordance with the inventive concept, wherein four concentric rings 102, 104, 106, 108 with progressively different electrical properties are used to make the etch rate distribution more uniform. 6 and 7 illustrate alternative embodiments that provide real-time tunability of the distribution of the RF electrical characteristics of the cathode 44. The plunger 110 controls the axial position of the movable aluminum plate 112 inside the hollow cylinder 114 in the center of the cathode 44. The aluminum plate 112 is in electrical contact with the remainder of the aluminum pleto 44a. An insulator (eg, ceramic) top layer 116 may cover the top of the cathode 44. As the aluminum plate 112 is pressed close to the top of the cylinder 114, the electrical impedance through the central region of the cathode 44 is reduced, thus increasing the etch rate at the center of the mask 18. Conversely, as the aluminum plate 112 moves down from the mask 18 in the cylinder 114, the etch rate at the center of the mask is reduced. The actuator 118 that controls the axial movement of the plunger 110 may be adjusted by the process controller 60 (FIG. 1) to compensate for nonuniformity or to adjust the etch rate distribution to maximize uniformity. have.

Through the back of the mask Etching  speed monitoring  And endpoint detection:

The high manufacturing costs incurred by periodically stopping the etch process to measure the etch depth or pattern size of the mask are reduced or eliminated using optical sensing through the back of the mask or substrate 18 and the cathode 44. In order to perform these periodic measurements, it was necessary to stop the etch process because of the low etch selectivity compared to photoresist: in general, the etching of the mask material is considerably slower than the photoresist. This problem is typically solved by depositing a thick photoresist on the mask, but the high etch rate of the resist randomly uneven or roughens the photoresist surface. This roughness can affect the light passing through the photoresist and introduce noise into any optical measurement of pattern size or etch depth. Thus, the photoresist can be temporarily removed for each periodic measurement to ensure noise-free optical measurement, which re-deposits the photoresist and rewrites the reticle pattern on the photoresist before restarting the interrupted mask etching process. It is inevitable to do so.

The mask etch plasma reactor shown in FIG. 8 solves these problems, and the entire etching process in which the mask or substrate 18 is placed on the mask support pedestal 16 using a backside optical measuring device provided in the cathode 44. While allowing for continuous observation of pattern size or measurement of etch depth. The backside measurement device utilizes the optically transparent nature of the mask substrate 18, which is typically quartz. Although thin films (chromium or molybdenum silicide) that can be deposited will be opaque, the formation of patterned openings defining the reticle pattern of the mask 18 can be optically sensed. The change in light intensity reflected by or transmitted through these layers can be observed through the cathode 44 from behind the mask. This observation can be used to perform etching process endpoint detection. When etching the quartz material, the optical interference seen through the cathode 44 and seen from behind the mask can be sensed to perform etch depth measurements in real time during the etching process. One advantage is that the images or light signals sensed from the back side of the mask are not affected by photoresist noise, or at least in comparison with an attempt to make such a measurement from the top side (photoresist side) of the mask 18. It is not affected.

For this purpose, the reactor of FIG. 8 includes a recess 120 in the top surface of the cathode 44, which has a lens 122 with the optical axis pointing towards the back of the mask or substrate 18. The pair of optical fibers 124 and 126 having a smaller diameter than the lens 122 have ends 124a and 126a approximating to or in contact with the lens 122, and the optical axis of the lens 122 Are arranged next to each other. Each of the optical fibers 124, 126 shown in FIG. 8 may be a substantially small optical fiber bundle. The optical fiber 124 has another end 124b connected with the light source 128. The light source emits light of a wavelength that passes through the mask 18, typically visible to the quartz mask. For interference depth measurements, the wavelength spectrum of the light source 128 is chosen to easily cause local coherence in the reticle pattern of the mask 18. For periodic features in an etched mask structure on the order of about 45 nm (or for periodic feature sizes of less than 1 micron), this condition is met when the light source 128 emits a visible light spectrum. The optical fiber 126 has another end 126b connected with the optical receiver 130. In the case of simple endpoint detection, the optical receiver 130 can simply detect the light intensity. In the case of pattern size (eg, line width) measurement, the optical receiver 130 may detect an image of lines etched within the viewing angle of the lens 122, from which the line width may be determined. In the case of etch depth measurement, the optical receiver 130 may detect an interference pattern or an interference fringe, from which the etch depth may be determined (ie, may be estimated from the interference or diffraction pattern, or calculated from the number of interference fringes). Can be). In another embodiment, optical receiver 130 may include a spectrometer that performs multi-wavelength interference measurements from which an etch rate may be estimated or calculated. For this determination, the process control device 60 includes an optical signal processing device 132 capable of processing the optical signal from the optical receiver. Such optical signal processing includes performing an etching process endpoint detection from a change in ambient light intensity; Pattern size measurement from the two-dimensional image sensed by the optical receiver 130; Etching depth calculation by calculating interference fringes; When the optical receiver 130 is configured as a spectrometer, it may involve one of the etching depth calculations (according to certain embodiments) from the multi-wavelength interference spectrum. Alternatively, such a spectrometer can be used to perform etch process endpoint detection from the backside of the wafer by a light emission spectrometer, and when the light source 128 is not used, it is emitted by the plasma to provide a transparent mask 18. Use light that passes through it.

The process control device 60 may process process endpoint detection information (or information) from the optical signal processing device 132 to control various components of the plasma reactor including the RF generator 24, 26, 28 and the wafer handling device 61. Etch depth measurement information). Typically, the process control device 60 stops the etching process and removes the mask from the pedestal 16 when the etching process end point is reached.

9 is a graph showing the ambient reflected light intensity detected from the top surface (coated with photoresist) of the mask as a function of time during the chromium etching process (where the chromium thin film on the quartz mask surface is etched according to the mask reticle pattern). . Large swings in intensity shown in the graph of FIG. 9 indicate noise generated by roughness at the top surface of the photoresist layer. The dashed line represents the step function signal hidden in the noise, and the step function coincides with the chromium etching process endpoint. FIG. 10 is the same measurement graph taken from the backside of the wafer through the cathode 44 in the reactor of FIG. 8, where the optical receiver 130 senses the reflected light level. The noise generated by the photoresist is greatly reduced, and the endpoint forming the step function is clearly seen in the optical data. The end of the step function represents a transition point at which the reflected light intensity drops as the etching process reaches the bottom of the chromium thin film, where the reflective surface area of chromium is drastically reduced.

11 and 12 are graphs of light intensity over time (or equally over space), and in FIG. 12, as detected by the optical receiver 130, where the periodic peaks in the light intensity correspond to an interference fringe. The peak spacing determines the etch depth, or thickness difference between the different surfaces of the periodically spaced apart features etched into the transparent quartz mask substrate 18. 11 shows the intensity detected through the photoresist from the top surface of the mask, including significant noise components produced by the photoresist that interfere with the detection of the interference fringe. FIG. 12 shows the intensity sensed through the mask backside by the optical receiver 130 of FIG. 8, substantially free of noise generated by the photoresist.

FIG. 13 is a graph showing the light intensity as a function of wavelength for the case where the optical receiver 130 is composed of a spectrometer and the light source 128 generates the wavelength spectrum. The characteristic of the spectral intensity in the graph of FIG. 13 indicates a state in which interference occurs between light reflected from a surface of different depths of features less than 1 micron periodically spaced in the transparent mask 18. At short wavelengths, the peaks are more periodic and more evenly spaced, and the main optical action is interference. At long wavelengths, local coherence for periodic features in the mask 18 is not very strong, so diffraction is becoming increasingly important as the wavelength increases, and intensity characteristics at higher wavelengths are less uniform, as shown in FIG. 13. Spaced and more complex. The peak spacing in FIG. 13 is a function of the etching depth, especially at low wavelengths, and the etching depth can be estimated as the peak-to-peak spacing.

FIG. 14 shows an embodiment of the reactor of FIG. 8, where the optical receiver 130 is an ambient light intensity detector and the optical signal processing device 132 is at the total reflected light intensity corresponding to the endpoint detection graph of FIG. 10. It is programmed to detect large changes (step functions). Light source 128 may be any suitable light source in this embodiment. Optionally, the light source 128 may be omitted, such that the photosensor 130 only responds to light from the plasma delivered through the transparent mask or substrate 18.

FIG. 15 shows an embodiment of the reactor of FIG. 8, wherein the optical receiver 130 is an interference fringe detector sufficiently focused by the lens 122 to distinguish the interference fringes, and the optical signal processing apparatus 132 is a transparent quartz It is programmed to calculate the interference fringes (eg, from time data versus intensity in the form shown in FIG. 12) to calculate the etch depth of the mask 18. This calculation yields a substantially instant etch depth, which is compared by the logic 200 to the user-specified target depth stored in the memory 202. The logic 200 may use conventional arithmetic matching or minimization routines to check for a match between the stored depth value and the measured depth value. The matching causes the logic 200 to inform the process control device 60 of the etch endpoint.

FIG. 16 illustrates an embodiment of the reactor of FIG. 8, using the interference spectroscopy technique of FIG. 13 to measure or determine the etch depth of the transparent quartz mask or substrate 18. In this case, light source 128 emits spectral or multiple wavelengths in the visible range (for periodic mask feature sizes of hundreds of nanometers or less). The optical receiver 130 is a spectrometer. The combination of the signal conditioner and the analog-to-digital converter 220 converts the spectral information collected by the spectrometer 130 into digital data that can be processed by the optical signal processor 132. One mode in which endpoint detection can be performed is performed to calculate the etch depth from the interval between periodic peaks of the short wavelength range of the data indicated by FIG. 13, as mentioned above. The comparison logic 200 may compare the instantaneously measured etch depth with the user-specified target depth stored in the memory 202 to determine whether the etch process endpoint has been achieved. In another mode, comparison logic 200 is sufficient to compare the digitally indicated wavelength spectrum (corresponding to the graph of FIG. 13) representing the instantaneous output of spectrometer 130 with a known spectrum corresponding to the desired etch depth. Powerful Known spectra are stored in the memory 202. Matching or coarse matching between the measured spectrum and the stored spectrum, detected by the comparison logic 200, generates an etch process endpoint flag to be sent to the process controller 60.

FIG. 17 shows an embodiment of the reactor of FIG. 8, in which an optical receiver 130 can distinguish emission lines from light radiation emitted by the plasma in the chamber to perform optical emission spectroscopy (OES). to be. Processing device 132 is an OES processing device programmed to track (or detect loss of) the selected optical lines corresponding to chemical species that indicate the material of the layer to be etched. In accordance with the predetermined change (eg, loss of the chromium wavelength line in the OES spectrum during the chromium etching process), the processing device 132 sends an etching process endpoint detection signal to the process control device 60.

FIG. 18 illustrates an embodiment in which the inventors are configured to have a pair of lenses 230, 232 in recesses 231, 233, respectively, spaced apart from the surface of the cathode 44, wherein the lenses 230, 232 are shown in FIG. The interference fringes are focused so that the focused light is transmitted by each optical fiber 234, 236 facing or contacting each lens 230, 232. The optical fibers 234, 236 are connected to an interference detector 238 (which may be a pattern detector or spectrometer), and the detector 238 has an output connected to the process control device 60. The lenses 230 and 232 receive light from the light source 240 through the optical fibers 242 and 244. This light is reflected from the top of the mask 18 to the back of the lenses 230 and 232 and transmitted to the detector 238 by the optical fibers 234 and 236. In addition, the embodiment of FIG. 18 has a third recess 249 on the cathode surface, which accommodates a third lens 250 that is connected to the input of the OES spectrometer 254 via an optical fiber 252. The OES processor 256 processes the output of the OES spectrometer 254 to perform endpoint detection and transmits the results to the process control device 60. The cathode 44 of the FIG. 18 embodiment is shown in FIG. 19 and shows three recesses 231, 233, 249 which receive lenses 230, 232, 250, respectively. FIG. 20 shows corresponding holes 260, 261, 262 for accommodating an optical device (not shown) supporting the lenses 230, 232, 250 in the installation plate 46. Fig. 21 is a cross-sectional view showing the connection between the lens and the optical fiber inside the pedestal.

Although FIGS. 16, 17, and 18 are described as using spectrometers 130 (FIGS. 16 and 17) and 254 (FIG. 18), spectrometers 130 or 254 may include one or more optical wavelength filters tuned to predetermined wavelengths. Can be replaced. Each of these optical wavelength filters can be combined with a photomultiplier to enhance the signal amplitude.

Rear end-detection mask Etching  fair :

22A and 22B illustrate a process of etching a reticle pattern on the quartz material of a mask. In FIG. 22A, the quartz mask substrate 210 is covered with a photoresist layer 212 having a structure of openings 216 created in the photoresist layer 212 and periodically spaced lines 214. In the reactor of FIG. 15 or 16, a quartz-etch process gas consisting of CHF 3 + CF 4 + Ar is injected into chamber 10, powered by RF generators 24, 26, 48 and the quartz material is photoresisted. It is etched into the opening 216 formed in the layer 212. The etch depth of quartz is continuously measured using interference between light 218 reflected at the etched top surface and light 219 reflected at the unetched top surface of the quartz substrate 210. The etching process stops when the desired etching depth is reached (Figure 22A). The photoresist is then removed to produce the desired mask (Figure 22B).

23A-23E show lower quartz mask substrate 210, molybdenum silicide layer 260 (containing molybdenum oxy-silicon nitride), chromium layer 262, chromium oxide antireflective coating 264, and photoresist layer 266. A process of etching a three-layer mask structure constructed with the openings 268 formed in the photoresist layer 264 is shown (FIG. 23A). In the step of FIG. 23B, the chromium layer 262 and the antireflective coating 264 perform OES endpoint detection (chamber in FIG. 17) using a chromium etching process gas such as Cl2 + O2 + CF4 or a simple reflective endpoint. It is etched in the plasma reactor chamber to perform the detection (chamber of FIG. 14). Photoresist layer 266 is removed (FIG. 23C). Molybdenum silicide layer 260 is then etched, as shown in FIG. 23D, using a process gas that is an etchant of molybdenum silicide, such as SF6 + Cl2, and a chromium layer 262, such as a hard mask. This step takes place in a plasma reactor that performs end point detection by simple ambient reflection or by OES end point detection, such as the chamber of FIG. 14 or 17. In FIG. 23E, chromium layer 262 and chromium oxide antireflective coating 264 are removed using a chromium etching process gas such as CH3 + CF4 + Ar. This step can be accomplished using the reactor of FIG. 14 or FIG. 17 to perform simple endpoint detection without etch depth measurements. This leaves a quartz mask substrate having a top layer of molybdenum silicide with a reticle pattern formed.

24A-24E illustrate a process for fabricating a two-layer mask consisting of periodic chrome lines on a transparent quartz mask disposed next to the exposed quartz in a periodic space, with one of the exposed quartz spaces being transmissive The light is etched to a depth that is phase shifted to the desired angle (eg 180 degrees). 24A shows an initial structure consisting of a quartz mask substrate 300, a chromium layer 302, a chromium oxide antireflective coating 304, and a photoresist layer 306. In the step of FIG. 24B, the chromium and chromium oxide layers 302, 304 are etched with a process gas of Cl2 + O2 + CF4 in a reactor chamber such as the chamber of FIG. 14 or FIG. In the step of FIG. 24C, the photoresist layer 306 is removed, and then the exposed portion of the quartz mask substrate 300 is etched in the quartz-etch process gas consisting of CHF 3 + CF 4 + Ar as shown in FIG. 24D. . The quartz etching step of FIG. 24D is performed in a reactor chamber capable of sensing or monitoring the etch depth of the quartz mask substrate 300, such as the chamber of FIG. 15 or 16. During the etching process, the instantaneous etching depth is continuously monitored, and the etching process is stopped when the target etching depth is reached in the mask 300. The final result is shown in FIG. 24E.

For the mask surface Etching  Continuous of the velocity distribution monitoring  :

25 and 26 show an embodiment of the wafer support pedestal 16 of FIG. 1 with a matrix of backside etch depth sensing components (lens and optical fiber) on top of cathode 44, which stops the etch process. Or instantaneously provide an instant image or sample of an etch rate distribution or an etch depth distribution over the entire surface of the mask or substrate during the etching process without interrupting or otherwise disturbing the mask substrate. Aluminum pleto 44a has a matrix of openings 320 on its top surface, each opening having a lens 322 facing the back of mask substrate 300. The light source 324 provides light through an output optical fiber 326 connected with each lens 322. Lens 322 provides sufficient focusing to distinguish interference fringes. Interference detector 328, which may be a sensor or spectrometer to facilitate pattern calculation, is coupled with an input optical fiber 330 associated with each lens 322. The switch or multiplexer 332 directs light sequentially from each input fiber 330 to the detector 328. It is provided with three modes that can operate in the device of FIGS. 25 and 26. In the first mode, the etch depth in the viewing angle of a given lens 322 is calculated from the spacing between the interference fringes. In the second mode, the detector 328 is a spectrometer and the etch depth within the viewing angle of a given lens 322 is calculated from the short wavelength peak spacing of the multi-wavelength interference spectrum (corresponding to FIG. 13). In a third mode, the multi-wavelength interference spectrum is detected at a given instantaneous time and compared with a library 340 of spectra for that known etch depth. The etching rate distribution is calculated from the etching depth and the elapsed time. This distribution records the etch nonuniformity of the process and passes it to the process controller 132. Controller 132 may respond to reduce the non-uniformity of the etch rate distribution by adjusting the adjustable characteristics of the reactor.

25 and 26 are shown having a 3x3 matrix of etch depth sensors or lenses 322 on top of the pleto 44a, but any number of rows and columns are used in the matrix of such sensors. Matrix can be an n ㅧ m matrix, where m and n are appropriate integers.

In one embodiment, the process control device 132 may be programmed to estimate whether the etch rate distribution is high or low centered (from the etch rate distribution information supplied by the spectrometer or sensor 130). Process control device 60 may respond to this information by adjusting certain adjustable characteristics of the reactor to reduce non-uniformity. For example, the process controller 60 can change the RF power allocation between the inner coil 20 and the outer coil 22. Alternatively or additionally, the process control device 60 may change the height of the movable aluminum plate 112 in the reactor of FIGS. 6 and 7. Feedback from the etch depth sensing component array or matrix of the pleto 44a allows the process control 60 to improve the uniformity of the etch rate distribution by error testing and subsequent testing of the adjustable components of the reactor. .

Real-time configurable process gas distribution:

27 and 29 show an embodiment of the plasma reactor of FIG. 1 with an array of individually controllable gas injection orifices or nozzles 32. By controlling the individual nozzles 32 individually, the gas distribution in the chamber 10 can be altered to correct for non-uniform distributions of etch rates throughout the workpiece or mask 18. In the illustrated embodiment, the array of gas nozzles 32 is located on the sidewall 12 near the ceiling 14. To this end, the reactor comprises an upper gas injection ring 338 fixed between the removable lid 342, the lower surface of which constitutes the ceiling 14, and the top of the side wall 12. The outer shoulder 344 on the lower surface of the upper gas injection ring 338 is located on the top surface of the side wall 12. An inner shoulder 346 on the top of the gas injection ring receives the rim of the lid 342. An outer shoulder 348 provided on the lower surface of the lid 342 is located in the inner shoulder 346 of the gas injection ring 338. A gas injection orifice or nozzle 32 is formed at the vertical inner surface 349 of the gas injection ring 338, which may be defined as the inner diameter of the gas injection ring 338. The gas flow to each of the injection nozzles 32 is individually controlled by an individual valve 350, and one valve 350 is provided for each nozzle 32. Process gas flowing from gas panel 36 flows through gas supply line 352 connected to input port 354 formed in gas injection ring 338. Gas supply outlets 356-1 and 356-2 formed in the gas injection ring 338 flow out process gas flowing from the input port 354. A series of shutoff gas flow lines 358 are connected to a series of outer periphery of the gas injection ring 338 that delivers process gas from each gas supply outlet or port 356 to the corresponding set of valves 350. Form a connection.

In a preferred embodiment, each valve 350 is pneumatically controlled, an input flow-through port 350a and an output flow-through port 350b, controlled gas outlet port 350c. And an air pressure control input port 350d. The outlet port 350c supplies the controlled process gas to one corresponding nozzle 32. Process gas flows freely from input flow through port 350a to output flow through port 350b. The compressed air pressure at the control input port 350d determines whether to convert any process gas passing through the flow through ports 350a and 350b to the gas outlet port 350c. Such pneumatic control valves are known, and these internal structures need not be disclosed herein. Gas flow lines 358-1 and 358-2 are connected from the gas supply outlets 356-1 and 356-2 to the input flow through port 350a of the valves 350-1 and 350-2. . Each of the remaining gas supply lines 358 is connected from the output flow through port 350a of one valve 350 to the input flow through port 350b of the next valve 350. Thus, the gas flow through the series of valves 350 on the left side of FIG. 28 is counterclockwise, while the gas flow through the series of valves 350 on the right side of FIG. 28 is clockwise.

Gas flow from each output port 356 to the series of valves 350 is not blocked by any series of intermediate valves 350. Each valve 350 can be turned “on” without turning on or turning off any other valve 350 to provide gas flow to the corresponding gas injection orifice 32, and allow gas flow to the injection orifice. It may be turned “off” to abort. The valve setting processor 360 controls all valves 350 and may turn on or turn off any combination of valves 350 through the valve control link 362. As mentioned above, in a preferred embodiment, the valve 350 is a pneumatic valve and the control link 362 is a pneumatic (air) tube to prevent the presence of electrical conductors near the coil antennas 20, 22. . In the embodiment of FIG. 28, the compressor 364 is pressured with an array of solenoid (ie electrically controlled) valves 365 that control the application of pressurized air to the pneumatic control inputs 350a of the individual pneumatic valves 350. Supply air from the bottom. The valve setting processor 360 controls the solenoid valve 365 via electrical links away from the coil antennas 20, 22.

FIG. 29 illustrates a variation of the FIG. 28 embodiment where the valves 350 are each electrically controlled rather than pneumatically controlled. In FIG. 29, each control link 362 is an electrical line that extends directly from the controller 360 to the corresponding one valve 350, with the air compressor 364 and the compressed air solenoid valve 365 array removed. It became.

Referring again to FIGS. 27 and 28, each orifice 32 is formed with a radial cylindrical passage 366 through the gas injection ring 338. The hollow cylindrical sleeve 368 is received in the passage 366 and the tip 368a of the sleeve 368 forms a gas injection orifice. Each sleeve 368 is made of a ceramic material and is removable. Additional details of the gas injection orifice or nozzle 32 can be found in the description of FIGS. 36A and 36B. The controlled gas output port 350c of each valve 350 is connected to the outer end of the corresponding radial passage 366 via a short gas supply line 370. The entire gas distribution assembly is modular and is quickly disassembled by the connection (or disconnection) of each outlet gas supply line 358 and each short gas supply line 370, and the sleeve 368 is a hole 366. Individually removable in In this way, the gas distribution component and assembly support of the gas injection ring 338 can be easily installed according to the respective principles, without having to remove or replace expensive parts of the reactor, such as, for example, the gas injection ring 338. Replaced.

30A-30D are graphs of the etch depth distribution across the mask 18 obtained at a fixed time period of the etching process performed in the reactors of FIGS. 27 and 28 with different valve settings. The etch distribution in FIG. 30A is obtained when all valves 350 are open, and is generally a low center etch distribution with 0.51% variation or high nonuniformity across the mask surface. The distribution in FIG. 30B is obtained when a pair of adjacent valves 350a and 350b are closed and the remaining valves 350 are open, which is a nearly uniform distribution with only 0.38% of variation or non-uniformity. 30C is obtained by readjusting the valve setting again with all valves 350 open. The distribution in FIG. 30C is lower in center. The distribution in FIG. 30D is obtained by closing different pairs of adjacent valves 350c and 350d. The resulting distribution is more uniform and less centered with only 0.40% of variation.

FIG. 31 illustrates an alternative embodiment in which the gas injection nozzle 32 is disposed in a zigzag or " W " pattern in the gas injection ring 338. As shown in FIG. Each nozzle is controlled independently as disclosed in the previous embodiments. The injection pattern can be moved relative to the ceiling by activating only the bottom row 32b of the nozzle or only the top row 32a. The spacing between the nozzles can be changed by activating only the selected nozzle 32 (eg, every third nozzle or every fourth nozzle). 32 is a cross-sectional view of a portion of the gas injection ring 338 showing how the nozzles 32 are arranged to be ejected in different directions. A large change in gas distribution can be obtained, for example, by the valve setting controller 60 which turns on only the nozzles 32 oriented in a particular direction. For example, all nozzles 32c inclined to the right in the figure of FIG. 32 can be turned on at the same time except for all other parts. Large changes or corrections are achieved by turning on all nozzles 32d inclined to the left, for example, while turning off all other parts including all nozzles 32c inclined to the right.

Adjustable reactor part control with feedback from rear etch depth sensor array :

With reference to FIGS. 33 and 34, feedback control of the adjustable components of the mask etch plasma reactor is provided using the output of the two dimensional array of the back etch depth sensors of FIGS. 25 and 26. The adjustable component or components may include the individually controlled gas injection nozzles 32 of FIGS. 27 and 28. Optionally or additionally, the adjustable component controlled in this feedback loop is the height of the movable aluminum plate 112 or the RF power allocation between the inner and outer coils 20, 22 in the reactor of FIGS. 6 and 7. It may include.

Feedback from the array or matrix of etch depth sensing components 130 of FIGS. 25 and 26 allows the process control 60 to uniformize the etch rate distribution by error adjustment and subsequent testing of the reactor adjustable components. Allow to improve. In FIG. 33, the feedback loop begins with the array 400 of the back etch depth sensor 130 of FIGS. 25 and 26. The process control device 60 estimates the magnitude and location of the nonuniformity in the etch rate of the mask 18 and infers the most appropriate change in the particular adjustable component of the reactor that can reduce or eliminate this nonuniformity. (18) Programmed to use instantaneous etch depth measurement images throughout. This information is translated into instructions (or instructions) sent by processor 60 to any one or some or all of the adjustable components of the reactor. 33 thus shows the output signal path from the process control device 60 to the adjustable components, wherein the adjustable components that may be present in any one or all reactors are internal and external antenna RF power generators 24, 26. (For internal and external RF power allocation), actuator 118 for movable aluminum plate 112, nozzle array controller 360 of controllable nozzle 32 arrays.

The feedback loop can operate continuously during the entire mask etching process, thus reducing the non-uniformity sensed by the processor 60 from the “image” of the etch rate distribution throughout the mask 18. Etch rate distribution nonuniformity is to be improved. The feedback can be adjusted by software in the processor 60 to perform the test and error adjustment. Alternatively, software within processor 60 may incorporate commercial neural training techniques and feedback learning techniques that enable processor 60 to respond more intelligently to nonuniformities in the sensed etch rate distribution. Such software technology does not form a configuration of the present invention.

In one embodiment, a feedback command to the adjustable component (or components) may be generated such that the deviation of the etch depth sensor array is reduced. In other embodiments, feedback may be selected to resolve certain nonuniformities. For example, the etch rate distribution sensed by the array of sensors 130 may be very high in one quadrant or at the corner of the mask 18, in which case the valve setting processor is limited to one quadrant. Test) command to reduce the gas flow by volume. If such measures appear to be limited success depending on the sequential image of the etch rate distribution obtained from the array of backside sensors 130, the adjustment of the gas flow distribution can be increased. This adjustment and calibration cycle may last until the etch rate distribution uniformity is no longer improved.

Another nonuniformity can be handled in a similar way after the first is corrected. For example, the etch rate at different locations may be extremely high, in which case such a location would result in a predetermined reduction in this non-uniformity through multiple samples of the etch rate distribution “image” from the rear sensor 130 array. Gas flow to the furnace is reduced.

If the etch rate nonuniformity is symmetrical (e.g., high centered or low centered distribution), symmetrically adjustable, such as the height of the aluminum plate 112 or the RF power allocation between the inner and outer coils 20, 22 The components can be used by the processor 60 to reduce non-uniformity using a feedback control loop. For example, the low center etch rate distribution can either raise the aluminum plate 112 or increase the allocation of RF power to the inner coil 20 (relative to the outer coil 22) (or Both), resulting in less nonuniformity by the processor 60 which increases the etch rate in the center of the mask 18. In the feedback loop, this change can be small initially, and as the uniformity of the etch distribution image from the array of rear sensors 130 is improved, the location of the aluminum plate and / or the allocation of power to the inner coil 20 May be increased further. This cycle can last until no further improvement is found. All previous techniques can be implemented in software executed by the process control device 60.

FIG. 35 shows a possible example of a feedback cycle performed by the process control device 60 in the embodiment of FIGS. 33 and 34. First, processor 60 obtains a recent two-dimensional image of the etch rate across the mask surface from the rear sensor 130 array (block 380 of FIG. 35). From this image, processor 60 estimates the non-uniformity pattern of the etch rate distribution (block 382) and selects an adjustment for one of the adjustable components of the reactor from the list of options that may reduce the non-uniformity (block ( 384)). After performing this adjustment (block 386), processor 60 obtains a recent etch rate distribution image (block 388) and compares it with the previous image selected prior to adjustment. When improvements are made (the nonuniformity is reduced), the processor 60 repeats the same cycle so that it is generally increased more with the same successful adjustment. If no improvement is made (NO in block 390), the selected adjustment is removed from the list of options (block 392), and another adjustment is selected by returning to step 384.

FIG. 36A is a side cross-sectional view of one embodiment of a gas injection orifice or nozzle 32 that may be injected into the radial cylindrical passage 366 of the gas injection ring 338 of FIGS. 27 and 28. As described above, the nozzle 32 is configured to be easily removed from the radial cylindrical passage 366 for easy replacement. The nozzle 32 includes a hollow cylindrical sleeve or hollow body 368, which may be made of a material suitable for a process such as metal or ceramic. In one embodiment, the hollow body 368 is made of aluminum or ceramic material, such as aluminum oxide (Al ₂ O ₃ ) material. The hollow body 368 includes a first outer diameter 3620 and a smaller second outer diameter 3615 forming a tip 368a. In one embodiment, the first outer diameter 3620 is about 50% larger than the second outer diameter 3615.

Since conventional nozzles may include surfaces, or threads or coupling mechanisms, that tend to secure or attach the nozzles to the passage 366, one challenge addressed by other nozzles is the removal of nozzles during replacement. Or installation. Also, since these conventional nozzles must be rotated, twisted, drawn out, or otherwise separated in the passage, the gas injection ring 338 (FIG. 27) may need to be removed from the chamber. This causes significant downtime and damages throughput. The nozzle 32 has been reinforced to allow for easier replacement by reducing surfaces that tend to be fixed or attached, or by minimizing mating connections. The replacement of nozzles 32 thus does not require extensive disassembly of the chamber, which has been faced in the past, which minimizes equipment downtime.

The hollow body 368 also includes a longitudinal passageway formed therethrough, which includes a first passageway 3605 and a second passageway 3610. In one embodiment, the hollow body 368 begins with the first outer diameter 3620 portion and extends through the first passageway 3605 extending at least partially through the second outer diameter 3615 portion of the tip 368a. Include. The first passage 3605 includes a first diameter, the second passage 3610 includes a second diameter smaller than the first diameter, and the first passage rapidly fluctuates into the second diameter at a boundary of about 90 degrees. . In one embodiment, the second passage 3610 includes a diameter about four times smaller than the diameter of the first passage 3605. The second outer diameter 3615 also includes a side passage 3618 that opens into the first passage 3605. Side passage 3618 may include a diameter substantially the same as the diameter of second passage 3610 and is typically disposed perpendicular to second outer diameter 3615 or first passage 36050.

FIG. 36B is an enlarged side view of a portion of the body 368 shown in FIG. 36A. The boundary between the first outer diameter 3620 portion and the second outer diameter 3615 portion is joined by a radial face 3625 extending at right angles from the second outer diameter 3615 portion to the first outer diameter 3620 portion. . In one embodiment, the radiating face 3625 includes a radius that fluctuates to a relief 3630, a bevel, or a first outer diameter 3620, which may be a chamfer. Face 3625 includes an annular groove 3635 formed therein, which may be configured as an o-type gas injection ring groove to receive an o-type gas injection ring (not shown). In one embodiment, a portion of first outer diameter 3620 that includes face 3625 radially outward from annular groove 3635 may be removed as indicated by dashed line 3622. In this configuration, face 3625 may be stepped, and the o-type gas injection ring will connect with the stepped portion rather than the annular groove. In some embodiments, face 3625 includes a radius 3640 that changes to a second outer diameter 3615. The annular groove 3635 (or optionally the stepped portion after removing the portion indicated by dashed line 3622) may comprise a surface free from scratches or machine marks, and in one embodiment, the surface is approximately It can be finished to have an average surface roughness Ra of 16 μm. Except for the annular groove 3635, the hollow body 368 surface may also be finished with an Ra of about 32 μm. In one embodiment, tip 368a includes a relief, bevel, or radius, which may be a chamfer, to relieve the edge of the face of tip 368a.

While it has been so far directed to embodiments of the invention, other features and embodiments of the invention may be devised without departing from the basic spirit and scope of the invention as determined by the appended claims.

1 is a conceptual cross-sectional view of one embodiment of a plasma reactor performing a mask etching process.

FIG. 2A is an isometric cutaway view of the lower portion of the reactor of FIG. 1. FIG.

FIG. 2B is a mask cut pedestal isometric cutaway view of the reactor of FIG. 1 in a raised position. FIG.

3 is a plan view of the cathode of the reactor of FIG.

4 and 5 are each a side view and a plan view of an alternative embodiment of the cathode of the reactor of FIG.

6 and 7 are side and top views, respectively, of another alternative embodiment of the cathode of the reactor of FIG.

8 is a conceptual side view of a plasma reactor having a back end detection device.

9 and 10 are graphs of respective endpoint detection optical signals obtained from the front and rear surfaces of the mask.

11 and 12 are graphs of respective interference fringe optical signals obtained from the front and rear surfaces of the mask.

FIG. 13 is a graph of a multi-wavelength interference spectral signal obtained in one embodiment of the reactor of FIG. 8.

FIG. 14 is a conceptual side view of one embodiment of the reactor of FIG. 8 performing backside endpoint detection based on the total reflected light intensity corresponding to FIG. 10.

15 is a conceptual side view of the embodiment of the reactor of FIG. 8 performing backside endpoint detection based on the interference fringe calculation corresponding to FIG. 12.

FIG. 16 is a conceptual side view of the embodiment of FIG. 8 performing backside endpoint detection based on a multi-wavelength interference spectrometer. FIG.

FIG. 17 is a conceptual side view of the embodiment of FIG. 8 performing backside endpoint detection based on optical emission spectrometry (OES).

FIG. 18 is a conceptual side view of the reactor of FIG. 8 showing an example with both backside endpoint detection based on OES and interference. FIG.

19 and 20 are isometric views of the cathode and fixture plate of the embodiment of FIG. 18, respectively.

21 is a cross-sectional view of the cathode of FIG. 19.

22A and 22B illustrate sequential steps in a quartz mask etch process using back end detection.

23A, 23B, 23C, 23D, and 23E show sequential steps in a chromium-molsilicide-quartz mask etching process using backside endpoint detection.

24A, 24B, 24C, 24D and 24E show sequential steps in a chromium-quartz mask etching process using backside endpoint detection.

25 and 26 are conceptual side and end views, respectively, of an embodiment where the real-time etch rate distribution is continuously measured at the back of the mask.

27 and 28 are each an isometric view and plan view of an embodiment with an array of individually controllable gas injection nozzles.

FIG. 29 is a plan view of the embodiment of FIGS. 27 and 28 using a pneumatic valve.

30A-30D are graphs of etch depth distribution across a mask, obtained when different valves of the array of valves of FIGS. 27 and 28 are activated.

FIG. 31 is an isometric view of an alternative embodiment of the reactor of FIGS. 27 and 28.

32 shows another alternative embodiment of the reactor of FIGS. 27 and 28.

33 and 34 are each a block diagram and perspective view of a plasma reactor capable of performing real-time feedback control of the adjustable components of the reactor based on an instant two-dimensional image of the etch rate distribution.

35 is a block diagram of a feedback control process that may be performed in the reactors of FIGS. 33 and 34.

36A is a side cross-sectional view of one embodiment of a gas injection nozzle.

36B is an enlarged side view of the body portion of the nozzle of FIG. 36A.

Claims (20)

A gas injection nozzle adapted to be modularly coupled with a gas distribution ring of a plasma reactor, A hollow cylindrical body having a first outer diameter and a second outer diameter defining a tip; A first passage formed in the longitudinal direction through the body and extending at least partially into the second outer diameter portion through the first outer diameter portion; And A second passage aligned with the same axis as the first passage and extending longitudinally from an end of the first passage to an end of the tip, the first outer diameter being greater than the second outer diameter Nozzle. The method of claim 1, And a side passage disposed in the second outer diameter portion is connected to the first passage. The method of claim 1, And the first passage has a diameter four times larger than the diameter of the second passage. The method of claim 1, And said hollow cylindrical body comprises a radial face extending perpendicularly from said second outer diameter portion to said first outer diameter portion. The method of claim 4, wherein And the radial face comprises an annular groove. The method of claim 1, And the hollow cylindrical body is made of ceramic material. A gas injection nozzle adapted to be modularly coupled with a gas distribution ring of a plasma reactor, A hollow cylindrical body having a first outer diameter portion and a second outer diameter portion smaller than the first outer diameter portion; A first passage disposed through the first outer diameter portion and varying at a 90 degree boundary into a second passage disposed through the second outer diameter portion; And And a radial surface joining the first outer diameter portion and the second outer diameter portion, wherein the first outer diameter portion is about 50% larger than the second outer diameter portion. The method of claim 7, wherein And the radial surface is disposed perpendicular to the second outer diameter portion. The method of claim 7, wherein And the radial side comprises an annular groove. The method of claim 9, The annular groove has an average surface roughness of 16 μm. The method of claim 9, And the hollow cylindrical body is made of ceramic material. The method of claim 9, And the first passageway has a diameter about four times larger than the diameter of the second passageway. The method of claim 9, And a side passage disposed in the second outer diameter portion is connected to the first passage. A gas injection nozzle adapted to be modularly coupled with a gas distribution ring of a plasma reactor, A hollow cylindrical body having a first outer diameter portion and a second outer diameter portion defining a tip, wherein the first outer diameter portion is larger than the second outer diameter portion; A first passage formed in the longitudinal direction through the body and passing through the first outer diameter portion and at least partially extending into the second outer diameter portion; A second passage aligned with the same axis as the first passage and varying at a 90 degree boundary with the first passage and extending longitudinally from an end of the first passage to an end of the tip; And And a side passage connected to said first passage and disposed within said second outer diameter portion, said first passage having a four times larger direct diameter than the diameter of said second passage. The method of claim 14, And the first outer diameter portion and the second outer diameter portion include a surface having an average surface roughness of 32 μm. The method of claim 14, And said hollow cylindrical body comprises a radial surface extending at right angles from said second outer diameter portion to said first outer diameter portion. The method of claim 16, And the radial side comprises an annular groove. The method of claim 17, The annular groove has an average surface roughness of 16 μm. The method of claim 14, And the hollow cylindrical body is made of ceramic material. The method of claim 14, And the hollow cylindrical body is made of aluminum oxide material.

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