JP2004263283A - Etching method and etching system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an etching method which can properly determine the end point in etching a substrate and to provide an etching system. <P>SOLUTION: When etching a substrate 100 is started, the micropattern part 100a of the substrate 100 is irradiated with light from a light source 2. A light detector 5 receives diffracted light and produces a detection signal in response to its condensedness. The information processing part 94a of a control unit 94 performs an image processing based on the detection signal to obtain a pattern of the diffracted light from the micropattern part 100a. The arithmetic part 94b of the control unit 94 compares the pattern shape of the diffracted light from the micropattern part 100a with the pattern shape of a diffracted light in the optimal etching state prestored in the memory unit 91 and judges their agreement or disagreement. When they agree with each other, the time when the judgement is performed is adopted as the end point of the etching. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an etching method and an etching system for obtaining a desired shape on a base material by performing an etching process on the base material, and particularly to a method for appropriately determining an end point of the etching process.
[0002]
[Prior art]
In recent years, in the field of optical pickup devices that are rapidly developing, extremely high precision optical elements such as lenses are required. In particular, a fine structure formed on the optical surface of such an optical element is required to have strict dimensional accuracy, and securing such accuracy is an important issue.
[0003]
Such an optical element can be manufactured, for example, by molding a material such as plastic or glass with a mold. Such mold molding is suitable for mass production of optical elements because a product having a uniform shape can be rapidly manufactured.
[0004]
By the way, such a mold, using a master having a mother optical surface corresponding to the optical surface of the optical element, specifically, by growing an electroformed through a chemical reaction on the mother, There are attempts to make it. According to such a mold manufacturing method, for example, by preparing a master mold in which an orb corresponding to the diffraction orb of the optical element is accurately formed, a mold for molding an optical element having less dimensional variation can be easily transferred and formed. can do.
[0005]
In addition, as a method of manufacturing such a matrix, cutting processing has been mainly used until now, but recently, in order to form a finer shape and further improve work efficiency, plasma or the like is used. (See, for example, Patent Document 1).
[0006]
In such an etching process, the processing end point (hereinafter, also referred to as an etching end point) is generally controlled by a time determined from the etching rate. However, the etching rate varies depending on the etching conditions and the etching environment. Therefore, the shape of the matrix obtained after the etching process may have an error of about 10% between batches.
[0007]
As described above, since the determination of the etching end point has a great influence on the shape of the matrix, for example, in order to obtain a matrix in which a zone corresponding to the diffraction zone of the optical element is accurately formed, the etching end point is required. Must be accurately determined.
[0008]
Therefore, when performing an etching process on the base material that is the master mold, for example, by monitoring the shape of the base material by a light emission monitor, or by analyzing the mass of a gas that etches the base material, or By measuring the mass of the base material, it is conceivable to determine the degree of progress of the etching process and accurately determine the etching end point.
[0009]
[Patent Document 1]
Japanese Patent Application No. 2002-253203 (paragraphs [0111] to [0134], FIG. 5)
[0010]
[Problems to be solved by the invention]
[0011]
However, optical elements such as lenses have a small surface area and the microstructure formed on the optical surface is on the order of microns to submicrons. It is difficult to monitor. In gas mass spectrometry, it is difficult to judge the progress of the etching process in each part of the base material because a part of the gas is collected and analyzed, and also in mass measurement, Therefore, there is a problem that it is difficult to determine the progress of the etching process in each part of the base material because the mass of the base material is measured.
[0012]
The present invention has been made in view of the above problems, and a purpose thereof is to irradiate light to a base material when performing etching processing on the base material, and to reflect the light, or An object of the present invention is to provide an etching method and an etching system capable of judging an etching state of a substrate by detecting diffracted light and appropriately determining an end point of an etching process on the substrate.
[0013]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 irradiates light to the base material in a state where the base material is subjected to an etching treatment so as to form a desired shape on the base material. Irradiation step, a detection step of detecting reflected light or diffracted light from the base material, and an end point determining step of determining an end point of the etching process based on a change in the amount of reflected light or diffracted light. It is characterized by the following.
[0014]
In order to solve the above problems, the invention according to claim 4 irradiates light to the base material in a state where the base material is subjected to an etching process so as to form a desired shape on the base material. Irradiation step, a detecting step of detecting diffracted light from the base material, and an end point determining step of determining an end point of the etching process based on a change in the pattern shape of the diffracted light, I do.
[0015]
In order to solve the above-mentioned problem, the invention according to claim 10 is an etching means for performing an etching process on the base material to form a desired shape on the base material, and an etching process on the base material. In the state where is applied, irradiation means for irradiating the base material with light, detection means for detecting reflected light or diffracted light from the base material, based on the light amount change of the reflected light or diffracted light, End point determining means for determining an end point of the etching process.
[0016]
In order to solve the above-mentioned problem, the invention according to claim 13 is an etching means for performing an etching process on the base material to form a desired shape on the base material, and an etching process on the base material. In the state where is applied, the irradiation means for irradiating the base material with light, the detection means for detecting the diffracted light from the base material, and based on the change in the pattern shape of the diffracted light, the etching process And an end point determining means for determining an end point.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, various embodiments of an etching method and an etching system according to the present invention will be described with reference to the drawings.
[0018]
[Configuration of etching system]
The etching system according to the present embodiment includes a plasma etching apparatus that performs an etching process on a base material, and an etching end point detection unit that detects an end point of the etching process performed by the plasma etching apparatus.
[0019]
FIG. 1 shows a plasma etching apparatus. FIGS. 3, 6 to 8, and 10 to 12 show an etching end point detecting unit. Although the plasma etching apparatus shown in FIG. 1 and the etching end point detection units shown in FIGS. 3, 6 to 8 and 10 to 12 are respectively shown as separate figures, the plasma etching apparatus shown in FIG. The etching apparatus and the etching end point detecting unit shown in FIG. 3, FIG. 6 to FIG. 8, or FIG. 10 to FIG.
[0020]
[Configuration of plasma etching apparatus]
First, a schematic configuration of a plasma etching apparatus included in the etching system will be described. However, in the following, an inductively coupled plasma processing apparatus capable of generating high-density plasma will be described as an example.
[0021]
As shown in FIG. 1, the plasma etching apparatus 10 has an airtight container 20 which is assembled so as to be disassembled from a case made of a conductive material, for example, aluminum. The container 20 is grounded by a grounding wire 21, and the inner wall surface is anodized by anodization so that no contaminants are generated from the wall surface. It is preferable that the inside of the container 20 be airtightly divided into an antenna chamber 24 and a processing chamber 26 located on the upper side. The partition structure for partitioning the partition is formed by a support portion 34 including a dielectric wall 32 formed by combining segments made of quartz or the like. The lower surface of the support portion 34 is formed in a substantially uniform state on a horizontal plane. The lower surface of the support portion 34 is preferably covered with a dielectric cover made of quartz or the like having a smooth lower surface, while the upper surface of the dielectric wall 32 is covered with a resin made of PTFE (polytetrafluoroethylene) or the like. Preferably, a plate is provided.
[0022]
Further, a heater 61 is provided in the antenna chamber 24, and the heater 61 is connected to a power supply 62. The heater 61 heats the partition structure including the dielectric wall 32 via the support portion 34, thereby preventing by-products from adhering to the lower surface of the partition structure exposed to the processing chamber 26.
[0023]
The support portion 34 is formed of a hollow member made of a conductive material, preferably a metal, for example, an aluminum case, and is also used as a shower case for forming a shower head. The inner and outer surfaces of the housing constituting the support portion 34 are anodized by anodic oxidation so that no contaminants are generated from the wall surface. In the support / shower housing 34, a plurality of gas passages are formed inside, and communicate with the gas passages, and a plurality of openings that open to a mounting table 70, more specifically, a susceptor 71 described later. A gas supply hole is formed on the lower surface.
[0024]
A gas supply pipe 51 that communicates with a gas flow path in the support section 34 is provided in a tubular pipe section 35 connected to the center of the support section 34. The gas supply pipe 51 passes through the ceiling of the container 20 and is connected to a processing gas supply source 50 provided outside the container 20. In other words, during the plasma processing, the processing gas is supplied from the processing gas supply source 50 into the support / shower housing 34 via the gas supply pipe 51, and is discharged into the processing chamber 26 from the gas supply hole on the lower surface thereof. You.
[0025]
In the antenna chamber 24, a high frequency (RF) antenna 31 disposed on the partition structure is disposed so as to face the dielectric wall 32.
[0026]
The antenna 31 is formed of, for example, a spiral coil antenna having a spiral structure on the partition structure. One end of the antenna 31 is led out from substantially the center of the ceiling of the container 20, and is connected to a high frequency power supply 42 via a matching unit 41. On the other hand, the other end is connected to the container 20 and thereby grounded.
[0027]
During the plasma processing, high frequency power for generating an induced electric field is supplied to the antenna 31 from the high frequency power supply 42. An induced electric field is formed in the processing chamber 26 by the antenna 31, and the processing gas supplied from the support / shower housing 34 is converted into plasma by the induced electric field. For this reason, the high-frequency power supply 42 is set to be able to supply high-frequency power with an output sufficient to generate plasma.
[0028]
A susceptor 71 serving as a mounting table for mounting the base material 100 is disposed in the processing chamber 26 so as to face the high-frequency antenna 31 with the dielectric wall 32 interposed therebetween. The susceptor 71 is made of a member made of a conductive material, for example, aluminum, and its surface is anodized by anodic oxidation to prevent generation of contaminants. Around the susceptor 71, a holding member 73 for fixing the base material 100 is provided.
[0029]
The susceptor 71 is housed in the insulator frame 72 and is supported on a hollow support. The strut penetrates the bottom of the container 20 in an airtight manner, and is supported by a drive unit 74 provided outside the container 20. That is, the susceptor 71 is driven, for example, in the vertical direction by the driving unit 74 when the substrate 100 is loaded / unloaded.
[0030]
The susceptor 71 is connected to a high-frequency power source 82 via a matching unit 81 by a power supply rod disposed in a hollow support. During the plasma processing, high frequency power for bias is applied to the susceptor 71 from the high frequency power supply 82. The bias high-frequency power is used to effectively draw ions in the plasma excited in the processing chamber 26 into the substrate 100.
[0031]
Further, in the susceptor 71, in order to control the temperature of the base material 100, a heating means such as a heater, a temperature adjusting unit 75 including a coolant flow path and the like, and a temperature sensor are disposed. Connected to control unit 76. Piping and wiring for these mechanisms and members are all led out of the container 20 through hollow columns.
[0032]
A vacuum exhaust mechanism including a vacuum pump and the like is connected to the bottom of the processing chamber 26 via an exhaust pipe 77. The inside of the processing chamber 26 is evacuated by the vacuum exhaust mechanism, and the inside of the processing chamber 26 is set and maintained in a vacuum atmosphere and a predetermined pressure atmosphere during the plasma processing.
[0033]
Further, a control unit 94 for controlling the supply of the bias power is connected to the bias high-frequency power supply 82 that outputs the bias power.
[0034]
On the other hand, a control unit 94 is also connected to the plasma generation high-frequency power supply 42 that outputs plasma generation power having a frequency relatively higher than the bias power, and the control unit 94 controls the plasma generation power. Is controlled. The control unit 94 further includes a display unit 93 for displaying various setting input values and the like, an operation input unit 92 for performing operation inputs, various tables and various control programs, and storage for storing setting information and the like. The unit 91 is connected.
[0035]
In such a configuration, when performing the etching process, first, the base material 100 is loaded on the mounting surface of the susceptor 71 by the transport means through the gate valve 22, and then the base material 100 is fixed to the susceptor 71 by the holding member 73. I do.
[0036]
Next, a processing gas containing an etching gas (for example, a mixed gas of SF6 and O2 at a mixing ratio of, for example, 9: 1) is discharged from the processing gas supply source 50 into the processing chamber 26, and the processing chamber 26 is discharged through the exhaust pipe 77. By evacuating the inside, the inside of the processing chamber 26 is maintained at a predetermined pressure atmosphere.
[0037]
Next, by applying a predetermined high-frequency power from the high-frequency power supply 42 to the antenna 31, a uniform induction electric field is formed in the processing chamber 26 via the partition wall structure. Such an induced electric field converts the processing gas into plasma in the processing chamber 26, and generates a high-density inductively coupled plasma.
[0038]
The ions in the plasma generated in this manner are effectively drawn into the base material 100 by a predetermined high-frequency power applied to the susceptor 71 from the high-frequency power supply 82, and the fine pattern portion 100 a is formed on the base material 100. An etching process is performed to form. A method for determining the end point of the etching process will be described later.
[0039]
The antenna 31, matching unit 41, high-frequency power supply 42, processing gas supply source 50, gas supply pipe 51, temperature adjustment unit 75, temperature control unit 76, matching unit 81, and high-frequency power supply 82 are "etching means" of the present invention. Is composed.
[0040]
At this time, under the control of the control unit 94, the high-frequency power of the first power having the predetermined first frequency is applied from the high-frequency power supply for plasma generation 42, and the high-frequency power for bias 82 is supplied via the matching unit 81 via the matching unit 81. A high frequency power of a second power, which is a second frequency relatively lower than the first power for plasma generation, is applied.
[0041]
Here, it is preferable that the control of the bias power is performed by adjusting the voltage value when the bias power is applied corresponding to each part of the base material 100 placed on the susceptor 71. Thus, for example, the etching selectivity (etching rate of the base material / etching rate of the resist layer) in each part of the base material 100 can be adjusted to control the amount of etching in each part of the base material 100.
[0042]
For example, the relationship between the bias voltage and the etching rate of the Si base and the etching rate of the resist layer is in a proportional relationship as shown in FIG. 2, and the relationship between the bias power and the etching rate of the base and the etching rate of the resist layer is also In order to comply with this proportional relationship, by adjusting the voltage value when applying the bias power as described above, the etching selectivity (the etching rate of the base material / the etching rate of the resist layer) in each part of the base material 100 can be reduced. By adjusting, the amount of etching in each part of the base material 100 can be controlled.
[0043]
[Configuration of etching end point detection unit]
Next, the configuration of the etching end point detection unit that configures the etching system will be described.
[0044]
(Example 1)
As shown in FIG. 3, the etching end point detection unit 1 includes a light source 2 for irradiating light to a fine pattern portion 100a formed on the optical surface of the base material 100, and a collimator for converting a light beam from the light source 2 into parallel light. A meter lens 3, a deflecting beam splitter 4 for reflecting parallel light from the collimator lens 3, and a photodetector 5 for receiving the diffracted light from the fine pattern portion 100 a of the substrate 100 via the deflecting beam splitter 4. , Is provided. The light source 2 can be, for example, a semiconductor laser, and the photodetector 5 can be, for example, a solid-state image sensor such as a CCD or a CMOS.
[0045]
The light source 2 and the collimator lens 3 constitute the “irradiating means” of the present invention.
[0046]
In such a configuration, when the etching process on the base material 100 by the above-described plasma etching apparatus 10 is started, light is emitted from the light source 2 and the light is emitted to the fine pattern portion 100a of the base material 100 by a predetermined amount. It is irradiated with a width and in a plane. That is, the same light as that given to an optical element such as a lens as a final product is applied to the fine pattern portion 100a of the base material 100. Incidentally, in this embodiment, the light from the light source 2 is irradiated so as to include the central axis of the base material 100 corresponding to the optical axis of the lens. The direction is along the central axis of the material 100. In addition, transmission windows 20a and 34a made of quartz glass are provided on the container 20 of the plasma etching apparatus 10 and the wall portion of the support / shower housing 34 in the optical path of the light from the light source 2, respectively. Is transmitted through them.
[0047]
Diffracted light from the fine pattern portion 100a of the substrate 100 is focused on the imaging surface of the photodetector 5. The condensed state changes with the progress of the etching process. For example, the focal position moves from the dotted line to the solid line in the drawing. When the diffracted light is condensed, a detection signal corresponding to the condensed state is generated from the photodetector 5, and the detection signal is subjected to image processing in the information processing unit 94a of the control unit 94, and thus obtained. The pattern shape of the diffracted light from the fine pattern portion 100a, which is image information, is displayed on the display unit 93 as an image. Further, the arithmetic unit 94b of the control unit 94 compares the pattern shape of the diffracted light from the fine pattern portion 100a with the pattern shape of the diffracted light in the optimal etching state, which is information stored in advance in the storage unit 91. Are performed, and their match / mismatch is determined. Incidentally, at this time, the display unit 93 further displays an image of the pattern shape of the diffracted light in the optimum etching state, which is information stored in advance in the storage unit 91, so that the pattern of the diffracted light from the fine pattern portion 100a can be displayed. It is possible to visually confirm that the shape matches the pattern shape of the diffracted light in the optimum etching state stored in the storage unit 91 in advance. The comparison process and the determination process are performed by the CPU (central processing unit) of the calculation unit 94b. Here, the pattern shape of the diffracted light in the optimum etching state referred to here is a pattern shape of the diffracted light obtained when the fine pattern portion 100a of the base material 100 has an optimum shape. By judging a match / mismatch with the above, it is possible to detect an etching state in which the substrate 100 can obtain optimal optical performance as an optical element.
[0048]
Note that the photodetector 5 and the control unit 94 constitute "detection means" of the present invention. In addition, the calculation unit 94b constitutes "end point determination means" of the present invention. Further, the storage unit 91 constitutes a “storage unit” of the present invention.
[0049]
Incidentally, the wavelength of the light emitted from the light source 2 is in a range of 400 nm to 800 nm, and specifically, a blue laser region around 400 nm and a red laser region around 650 nm used for the pickup lens (for DVD). , 780 nm in the infrared laser region (for CD). Thus, for example, even when the substrate 100 is a diffraction lens for a compatible recording medium, it is possible to detect an etching state in which optimum optical performance can be obtained for each wavelength region.
[0050]
(Example 2)
By the way, when a photodiode or the like is used as the photodetector 5, for example, an etching state in which the substrate 100 can obtain optimal optical performance as an optical element can be detected as follows.
[0051]
As described above, the diffracted light from the fine pattern portion 100a of the substrate 100 is focused on the imaging surface of the photodetector 5. The condensed state changes with the progress of the etching process, and the pattern shape is such that, for example, as shown in FIG. 4, each order light from an orbicular zone corresponding to the diffractive orbicular zone of the optical element is concentrically projected. It will be. The detection signal from the photodetector 5 is processed as the light quantity of each next light in the information processing section 94a of the control section 94, and the calculation section 94b of the control section 94 extracts the light quantity of the specific next light from these. , Determine its maximum value. Such determination processing is performed by the CPU (Central Processing Unit) of the arithmetic unit 94b.
[0052]
For example, as shown in FIG. 5, the relationship between the amount of primary light (light intensity) and the shape (blaze height) of the fine pattern portion 100a of the substrate 100 is such that the blaze height increases as the etching process proceeds. As it increases, the increase / decrease of the light amount (light intensity) is periodically repeated, and the blaze height 10 [μm] corresponding to 1 [Arb] which is the maximum value of the light amount (light intensity) of the primary light. ] Can be shaped so that the fine pattern portion 100a of the base material 100 can obtain optimal optical performance as an optical element.
[0053]
Therefore, the arithmetic unit 94b of the control unit 94 extracts the light amount of the specific next light and determines the maximum value thereof, so that the substrate 100 can obtain the optimal optical performance as an optical element in the etching state. Can be detected.
[0054]
The control unit 94 further determines in the arithmetic unit 94b that the pattern shape of the diffracted light from the fine pattern portion 100a matches the pattern shape of the diffracted light in the optimum etching state stored in the storage unit 91 in advance. In this case, or as described above, when the light amount of the specific next light is extracted and the maximum value is determined, control is performed to stop the etching of the base material 100 by the plasma etching apparatus 10. Specifically, first, the discharge of the processing gas including the etching gas from the processing gas supply source 50 is stopped. Thus, the supply of the processing gas from the support / shower housing 34 is stopped. Next, the application of high-frequency power from the high-frequency power supply 42 to the matching device 41 is stopped. Thereby, the formation of the induced electric field in the processing chamber 26 by the antenna 31 is stopped. Next, the application of high-frequency power from the high-frequency power source 82 for bias to the matching unit 81 is stopped. Thus, the application of the high frequency power for bias to the susceptor 71 is stopped. With these, the etching process on the base material 100 is stopped. Further, after the fixing by the holding member 73 is released, the base material 100 is unloaded from the mounting surface of the susceptor 71 to the outside of the container 20 by the transport means through the gate valve 22.
[0055]
Note that the control section 94 constitutes a "stop means" of the present invention.
[0056]
By the way, in the etching end point detection unit 1, while the etching process is performed on the base material 100 by the plasma etching apparatus 10, the calculation unit 94 b of the control unit 94 generates the diffracted light from the fine pattern portion 100 a of the base material 100. Alternatively, the processing status of the etching process in each part of the fine pattern portion 100a of the base material 100 is determined by analyzing the received light amount of the reflected light from each part of the fine pattern portion 100a of the base material 100 and the light receiving position thereof. Then, the processing status is fed back to the etching process performed by the plasma etching apparatus 10, that is, the control unit 94 controls the high-frequency power supply 82, so that the susceptor 71 is mounted on the susceptor 71 in accordance with the processing status of the etching process. Corresponding to each part of the fine pattern portion 100a of the base material 100 to be placed. By adjusting the voltage value at the time of applying the bias power, the etching selectivity at each portion of the fine pattern portion 100a of the base material 100 is adjusted, and the etching amount at each portion of the fine pattern portion 100a of the base material 100 is reduced. Can be controlled. Thereby, the degree of progress of the etching process in each part of the fine pattern portion 100a of the base material 100 can be corrected.
[0057]
As described above, the amount of diffracted light or reflected light increases as the etching process proceeds. Also, as the etching process proceeds, the pattern shape of the diffracted light changes, Since the light receiving position moves in a predetermined direction, the calculation unit 94b of the control unit 94 analyzes the light amount of each part of the pattern shape of the diffracted light, or analyzes the shape, and By analyzing the amount of light received from each part of the fine pattern portion 100a of the base material 100 and the light receiving position thereof, it is possible to determine the processing status of the etching process in each part of the fine pattern portion 100a of the base material 100. Can be.
[0058]
Incidentally, the received light amount of the reflected light from each part of the fine pattern portion 100a of the base material 100 is adjusted by irradiating each part of the fine pattern portion 100a of the base material 100 by moving the light source 2 by a moving means (not shown). Each time, the light detector can be moved by moving means (not shown) and the reflected light can be received to acquire the light. Further, the light receiving position of the reflected light from each part of the fine pattern portion 100a of the base material 100 can be obtained by detecting the position of the photodetector 5 when the reflected light is received by the detecting means (not shown). .
[0059]
Note that the control section 94 constitutes "situation determination means" of the present invention. In addition, the control unit 94, the matching unit 81, and the high-frequency power supply 82 constitute an “adjustment unit” of the present invention.
[0060]
As described above, in the etching end point detection unit 1 in the present embodiment, the same light that is actually given to the optical element such as a lens as a final product by the light source 2 The pattern portion 100a is irradiated, the photodetector 5 receives the diffracted light, and the control unit 94 detects the optimum etching state from the pattern shape or the light amount value of the specific next light. Therefore, the end point of the etching process can be accurately determined, and in the plasma etching apparatus 10, the etching process on the base material 100 is performed so that the base material 100 can obtain optimal optical performance as an optical element. Can be controlled.
[0061]
Particularly, in an optical element having a fine structure such as a diffractive structure, not only the evaluation of the overall shape of the lens and the like but also the evaluation of the optical performance related to the fine structure can be performed. Optical performance inspection can be omitted. As a result, the time and cost required for the quality assurance process can be reduced.
[0062]
Further, in the etching end point detecting unit 1 in the present embodiment, the arithmetic unit 94b of the control unit 94 operates the fine pattern portion 100a of the base 100 in a state where the base 100 is subjected to the etching process by the plasma etching apparatus 10. From the amount of light received and the position of the light received from each part of the fine pattern portion 100a of the base material 100, the processing status of the etching process is determined, and this is used for the etching process by the plasma etching apparatus 10. Since the feedback can be made, the etching selectivity in each part of the fine pattern portion 100a of the base material 100 can be adjusted to control the amount of etching, and the etching process in each part of the fine pattern portion 100a of the base material 100 can be controlled. The degree of progress can be corrected.
[0063]
In the etching end point detection unit 1 in this embodiment, the collimator lens 3 is arranged between the light source 2 and the deflecting beam splitter 4. However, depending on the configuration, for example, as shown in FIG. As described above, it may be arranged between the substrate 100 and the deflection beam splitter 4.
[0064]
In addition, in the etching end point detection unit 1 in the present embodiment, the light source 2 is arranged in the horizontal direction and the photodetector 5 is arranged in the vertical direction. As shown in FIG. 7, the light source 2 may be arranged vertically and the photodetector 5 may be arranged horizontally. In such a case, the light from the light source 2 is emitted vertically downward, passes through the half mirror 6, irradiates the fine pattern portion 100a of the base material 100 via the collimator lens 3, and its diffraction The light is reflected by the half mirror 6 via the collimator lens 3 and received by the photodetector 5.
[0065]
Further, in the etching end point detection unit 1 in the present embodiment, the calculation unit 94b of the control unit 94 determines the pattern when the diffracted light from the fine pattern portion 100a of the base material 100 is condensed on the imaging surface of the photodetector 5. Although the end point of the etching process by the plasma etching apparatus 10 is determined based on the shape or the light amount value of the specific next light, other than this, for example, diffraction from the fine pattern portion 100a of the base material 100 may be performed. This may be determined based on the light amount distribution and the light collection efficiency when light is collected on the imaging surface of the photodetector 14.
[0066]
Further, in describing the etching end point detection unit 1 in the present embodiment, the fine pattern portion 100a is formed on the convex surface of the base material 100, but the fine pattern portion of the base material is It may be formed.
[0067]
In the description of the etching end point detecting unit 1 in the present embodiment, the fine pattern portion 100a of the base material 100 has a blazed shape, but the fine pattern portion of the base material has a binary shape. May be.
[0068]
(Example 3)
As shown in FIG. 8, the etching end point detection unit 1a includes a light source 2 for irradiating light to the fine pattern portion 100a of the substrate 100, and a photodetector for receiving light reflected from the optical surface 100a of the substrate 100. 5 is provided. The light source 2 includes, for example, a semiconductor laser, and the light detector 5 includes, for example, a photodiode.
[0069]
In such a configuration, when the etching process on the base material 100 by the above-described plasma etching apparatus 10 is started, light is emitted from the light source 2 and the light is transmitted to the fine pattern portion 100a of the base material 100. Irradiated. Incidentally, in this embodiment, the light from the light source 2 is in a direction along the central axis of the substrate 100 corresponding to the optical axis of the lens. In addition, transmission windows 20a, 20b and transmission window 34a made of quartz glass are provided on the container 20 of the plasma etching apparatus 10 and the wall surface of the support / shower housing 34 in the optical path of the light from the light source 2, respectively. , Light from the light source 11 is transmitted therethrough.
[0070]
Incidentally, the light source 2 constitutes the “irradiating means” of the present invention.
[0071]
The reflected light from the fine pattern portion 100a of the substrate 100 enters the imaging surface of the photodetector 5. The optical path moves in a predetermined direction due to a change in the shape of the fine pattern portion 100a of the base material 100 as the etching process proceeds. The position is adjusted so that the reflected light from the fine pattern portion 100a of the base material 100 enters the imaging surface. When the reflected light enters, a detection signal corresponding to the amount of received light is generated from the photodetector 5, and the detection signal is processed as the amount of light in the information processing unit 25 of the control unit 94. The calculation unit 94b determines the maximum value of the light amount. Such determination processing is performed by the CPU (Central Processing Unit) of the arithmetic unit 94b.
[0072]
More specifically, as shown in FIG. 9, the reflected light from the fine pattern portion 100a of the base material 100 is dispersed into the respective order lights at the time of the reflection, so that the photodetector 5 has a plurality of ( 5a to 5c) are preferably arranged at positions where the respective next lights enter. In such a case, the detection signals from the photodetectors 5a to 5c are processed as the light amounts of the respective next lights in the information processing section 94a of the control section 94, and the calculation section 94b of the control section 94 specifies the detection signals. Is extracted, and its maximum value is determined.
[0073]
By the way, in the case of the reflected light, similarly to the case of the diffracted light described above, for example, the relationship between the light amount (light intensity) of the primary light and the shape (blaze height) of the fine pattern portion 100a of the base material 100 is as follows. As the blaze height increases as the etching process proceeds, the increase / decrease of the light amount (light intensity) is periodically repeated, and the blaze height corresponding to the maximum value of the light amount (light intensity) of the primary light. The shape can be such that the fine pattern portion 100a of the base material 100 can obtain optimal optical performance as an optical element.
[0074]
Therefore, the arithmetic unit 94b of the control unit 94 extracts the amount of the specific next light and determines the maximum value thereof, so that the fine pattern portion 100a of the base material 100 obtains the optimal optical performance as an optical element. It is possible to detect a state in which the shape can be used.
[0075]
However, in such a case, it is only possible to detect the state of the shape of the specific portion of the fine pattern portion 100a of the base material 100, and the base material 100 may obtain optimal optical performance as an optical element. In order to detect a possible etching state, it is necessary to determine the maximum value of the amount of the reflected light for each part of the fine pattern portion 100a of the base material 100.
[0076]
The amount of light received from each part of the fine pattern portion 100a of the base material 100 is determined by irradiating the light to each part of the fine pattern portion 100a of the base material 100 by moving the light source 2 by a moving means (not shown). Each time, the light detector can be moved by moving means (not shown) and the reflected light can be received to acquire the light.
[0077]
Note that the photodetector 5 and the control unit 94 constitute "detection means" of the present invention. In addition, the calculation unit 94b constitutes "end point determination means" of the present invention.
[0078]
Incidentally, the wavelength of the light emitted from the light source 2 is in a range of 400 nm to 800 nm, and specifically, a blue laser region around 400 nm and a red laser region around 650 nm used for the pickup lens (for DVD). , 780 nm in the infrared laser region (for CD). Thus, for example, even when the substrate 100 is a diffraction lens for a compatible recording medium, it is possible to detect an etching state in which optimum optical performance can be obtained for each wavelength region.
[0079]
The control unit 94 further calculates the specific amount of reflected light from the fine pattern portion 100a by the arithmetic unit 94b, and when the maximum value thereof is determined, the control unit 94 determines whether the plasma etching apparatus 10 Control to stop the etching process is performed. Specifically, first, the discharge of the processing gas including the etching gas from the processing gas supply source 50 is stopped. Thus, the supply of the processing gas from the support / shower housing 34 is stopped. Next, the application of high-frequency power from the high-frequency power supply 42 to the matching device 41 is stopped. Thereby, the formation of the induced electric field in the processing chamber 26 by the antenna 31 is stopped. Next, the application of high-frequency power from the high-frequency power source 82 for bias to the matching unit 81 is stopped. Thus, the application of the high frequency power for bias to the susceptor 71 is stopped. With these, the etching process on the base material 100 is stopped. Further, after the fixing by the holding member 73 is released, the base material 100 is unloaded from the mounting surface of the susceptor 71 to the outside of the container 20 by the transport means through the gate valve 22.
[0080]
Note that the control section 94 constitutes a "stop means" of the present invention.
[0081]
By the way, in the etching end point detection unit 1a, while the etching process is being performed on the base material 100 by the plasma etching apparatus 10, the operation unit 94b of the control unit 94 causes the calculation unit 94b of each part of the fine pattern portion 100a of the base material 100. By analyzing the amount and position of the reflected light received, the processing status of the etching process in each part of the fine pattern portion 100a of the base material 100 is determined, and the processing status is fed back to the etching process by the plasma etching apparatus 10. That is, by controlling the high-frequency power supply 82 by the control unit 94, in accordance with the processing state of the etching processing, corresponding to each part of the fine pattern portion 100a of the base material 100 mounted on the susceptor 71, By adjusting the voltage value when applying the bias power, the base material 10 Adjust the etching selectivity in each part of the fine pattern portion 100a, it is possible to control the etching amount in each part of the fine pattern portion 100a of the substrate 100. Thereby, the degree of progress of the etching process in each part of the fine pattern portion 100a of the base material 100 can be corrected.
[0082]
As described above, the amount of reflected light increases as the etching process proceeds, and as the etching process proceeds, the position of receiving the reflected light moves in a predetermined direction. The calculation unit 94b of the unit 94 analyzes the amount of light received from each part of the fine pattern portion 100a of the base material 100 and the light receiving position thereof, thereby performing etching at each part of the fine pattern portion 100a of the base material 100. The processing status of the processing can be determined.
[0083]
The amount of reflected light received from each part of the fine pattern portion 100a of the base material 100 is adjusted by irradiating each part of the fine pattern portion 100a of the base material 100 by moving the light source 2 by a moving means (not shown). Each time, the light detector can be moved by moving means (not shown) and the reflected light can be received to acquire the light. Further, the light receiving position of the reflected light from each part of the fine pattern portion 100a of the base material 100 can be obtained by detecting the position of the photodetector 5 when the reflected light is received by the detecting means (not shown). .
[0084]
Note that the control section 94 constitutes "situation determination means" of the present invention. In addition, the control unit 94, the matching unit 81, and the high-frequency power supply 82 constitute an “adjustment unit” of the present invention.
[0085]
As described above, in the etching end point detection unit 1a in this embodiment, the light source 2 irradiates each part of the fine pattern portion 100a of the base material 100 with light, and the light detector 5 reflects the light. Since the light is received and the control unit 94 can detect the optimum etching state from the light amount value of the specific next light, the end point of the etching process can be accurately determined, and the plasma etching apparatus 10 In, stop of the etching process on the base material 100 can be controlled so that the base material 100 can obtain optimal optical performance as an optical element.
[0086]
Particularly, in an optical element having a fine structure such as a diffractive structure, not only the evaluation of the overall shape of the lens and the like but also the evaluation of the optical performance related to the fine structure can be performed. Optical performance inspection can be omitted. As a result, the time and cost required for the quality assurance process can be reduced.
[0087]
Further, in the etching end point detection unit 1a according to the present embodiment, the arithmetic unit 94b of the control unit 94 operates the fine pattern portion 100a of the base 100 in a state where the base 100 is etched by the plasma etching apparatus 10. The amount of light received and the position of the light received from each part of the substrate 100 are analyzed, the processing status of the etching process is determined, and this can be fed back to the etching process by the plasma etching apparatus 10. The amount of etching can be controlled by adjusting the etching selectivity in each portion of the portion 100a, and the progress of the etching process in each portion of the fine pattern portion 100a of the base material 100 can be corrected.
[0088]
In addition, in the etching end point detection unit 1a in this embodiment, the light source 2 is arranged near the upper wall of the container 20, and the photodetector 5 is arranged near the side wall of the container 20. For example, as shown in FIG. 10, the light source 2 may be arranged near the side wall of the container 20, and the photodetector 5 may be arranged near the upper wall of the container 20, as shown in FIG. Further, for example, as shown in FIG. 11, the light source 2 and the photodetector 5 may be arranged near the upper wall of the container 20. For example, as shown in FIG. 12, the light source 2 and the photodetector 5 may be arranged near the side wall of the container 20. In such a case, it is not necessary to provide a transmission window made of quartz glass on the wall portion of the support / shower housing 34.
[0089]
Further, in the etching end point detection unit 1a in the present embodiment, the calculation unit 94b of the control unit 94 determines the amount of light when the reflected light from the fine pattern portion 100a of the base material 100 enters the imaging surface of the photodetector 5. The end point of the etching process in the plasma etching apparatus 10 is determined on the basis of the change in the light intensity. This may be determined based on the reflection efficiency when light is condensed.
[0090]
In describing the etching end point detection unit 1a in the present embodiment, the fine pattern portion 100a is formed on the convex surface of the base material 100. However, the fine pattern portion of the base material is formed on a flat surface or a concave surface. It may be formed.
[0091]
In the description of the etching end point detecting unit 1a in the present embodiment, the fine pattern portion 100a of the base material 100 has a blaze shape, but the fine pattern portion of the base material has a binary shape. May be.
[0092]
[Steps of etching method]
Next, in the case of determining the end point of the etching process based on the change in the amount of light of the reflected light from the fine pattern portion of the base material with reference to the flowchart shown in FIG. Will be described as an example.
[0093]
As shown in FIG. 13, first, the etching process is started by irradiating the fine pattern portion 100a of the base material 100 with plasma (S01).
[0094]
<Irradiation step>
Next, in a state where the etching process is being performed, light is irradiated from the light source 2 to the fine pattern portion 100a of the base material 100 (S02).
[0095]
<Detection step>
Next, the reflected light is received by the photodetector 5. As a result, a detection signal corresponding to the amount of received light is generated in the photodetector 5, and in the control unit 94, the information processing unit 94a processes the detection signal as the amount of light (S03).
[0096]
<Judgment step>
Then, the calculation unit 94b of the control unit 94 determines the maximum value of the light amount (S04). Here, when the light amount reaches the maximum value, this is regarded as the optimum etching state, and it is determined as the end point of the etching process (S05).
[0097]
<Stop step>
Further, when determining the end point of the etching process, the control unit 94 stops the plasma irradiation and ends the etching process (S06).
[0098]
In this way, the etching process on the base material 100 can be terminated so that the base material 100 can obtain optimal optical performance as an optical element.
[0099]
<Adjustment step>
Further, while the etching process is being performed, the amount of light received and the light receiving position of the reflected light from each part of the fine pattern portion 100a of the base material 100 are analyzed, the processing status of the etching process is determined, and this is etched. By feeding back to the process, that is, by adjusting the etching selectivity in each part of the fine pattern portion 100a of the substrate 100 according to the processing status of the etching process, and controlling the etching amount, The degree of progress of the etching process in each part of the fine pattern portion 100a can be corrected.
[0100]
[Manufacturing process of optical element molding die]
The base material 100 that has been subjected to the etching treatment as described above is used as a final product, for example, a matrix for manufacturing an optical element molding die for molding an optical element as a final product. Can be used as
[0101]
Next, the manufacturing process of the optical element molding die including the etching process shown in FIG. 13 will be described with reference to FIG. 15 along the flow of the flowchart shown in FIG. In the following, an example in which an optical element molding die for molding an optical element having a diffraction ring pattern for a diffractive structure is formed by electroforming and transferring from a shape of a master mold.
[0102]
As shown in FIG. 14, first, the base material 100 serving as a matrix is set on an SPDT processing machine to form an aspherical shape corresponding to the optical surface of an optical element (S101, see FIG. 15A). Next, the substrate 100 having the aspherical shape is removed from the SPDT processing machine, and the resist L is dropped on the aspherical shape while rotating the substrate 100 to form a resist layer having a uniform thickness. (See FIG. 15B). Next, after performing a baking process to stabilize the resist layer (S103), drawing with the electron beam B is performed to form a diffraction ring pattern on the aspherical shape (S104, FIG. 15 ( C))). Next, an exposure process is performed (S105), and a resist development process is performed (S106) to obtain an annular pattern in the formation process on the resist layer. Next, by performing an etching process shown in FIG. 13 (S107, see FIG. 15D), a ring pattern is engraved on the aspherical shape of the base material 100, and the mother ring on which a desired ring pattern is formed is formed. Get the type. Next, by subjecting the matrix to electroforming (see FIG. 15E), a desired orbicular zone pattern is transferred and formed on the base material 200a to be a mold, and then the matrix is released. By combining the backing member with the base material 200a to be the mold (S108, see FIG. 15F), the optical element molding mold 200 is obtained.
[0103]
In this way, an optical element molding die for molding an optical element having a diffraction ring pattern can be manufactured. However, according to the etching method and the etching system according to the present invention, the etching process in this manufacturing process is performed. In the method described above, the fine pattern portion 100a of the base material 100 can be etched into an optimal shape, so that the diffraction zone pattern in the optical element molding die can be formed into an optical element having the most appropriate optical performance. Can be formed. Thereby, by molding using such an optical element molding die, an optical element having a diffraction zone pattern as a final product and having the most appropriate optical performance can be easily manufactured.
[0104]
As described above, various embodiments of the etching method and the etching system according to the present invention have been described. However, the etching method and the etching system according to the present invention are not limited to these. Various modifications can be made within the range.
[0105]
For example, the etching method and the etching system according to the present embodiment are applied to a case where a master mold for manufacturing an optical element molding die for molding an optical element is applied. It is needless to say that the present invention can be similarly applied to a case where a product having such a product is manufactured or a case where a mother die for manufacturing a molding die for forming such a product is manufactured.
[0106]
【The invention's effect】
As described above, according to the etching method and the etching system according to the present invention, when performing the etching process on the base material, the base material is irradiated with light, and the reflected light or diffraction thereof is performed. By detecting the light, the etching state of the substrate can be determined, and the end point of the etching process on the substrate can be properly determined.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a configuration of a plasma etching apparatus configuring an etching system according to an embodiment.
FIG. 2 is an explanatory diagram showing a relationship between a bias voltage, an etching rate of a Si base material, and an etching rate of a resist layer.
FIG. 3 is a configuration diagram illustrating a configuration of an etching end point detection unit included in the etching system according to the present embodiment.
FIG. 4 is an explanatory diagram showing a pattern shape of diffracted light from a fine pattern portion of a base material received on a detection surface of a photodetector constituting an etching end point detection unit.
FIG. 5 is an explanatory diagram showing a relationship between a light amount (light intensity) of a diffracted light of a specific order light and a shape of a fine pattern portion (blaze).
FIG. 6 is a schematic diagram showing another configuration of the etching end point detection unit shown in FIG. 3;
FIG. 7 is a schematic diagram showing another configuration of the etching end point detection unit shown in FIG. 3;
FIG. 8 is a schematic diagram illustrating another configuration of the etching end point detection unit configuring the etching system according to the present embodiment.
FIG. 9 is an explanatory diagram illustrating a state in which reflected light from a fine pattern portion of a base material is dispersed.
FIG. 10 is a schematic diagram showing another configuration of the etching end point detection unit shown in FIG. 8;
11 is a schematic diagram showing another configuration of the etching end point detection unit shown in FIG.
FIG. 12 is a schematic diagram showing another configuration of the etching end point detection unit shown in FIG. 8;
FIG. 13 is a flowchart illustrating steps of an etching method of the etching system according to the present embodiment.
FIG. 14 is a flowchart showing a manufacturing process of an optical element molding die including the etching method shown in FIG.
FIG. 15 is an explanatory diagram for describing a manufacturing process of the optical element molding die shown in FIG.
[Explanation of symbols]
1, 1a Etching end point detection unit
2 Light source
3 Collimator lens
4 Deflection beam splitter
5, 5a, 5b, 5c Photodetector
6 Half mirror
10 Plasma etching equipment
20 containers
20a, 20b Transmission window
21 Ground wire
22 Gate valve
24 antenna room
26 Processing room
31 antenna
32 dielectric wall
34 Support
34a transparent window
35 tube
41 Matching device
42 High frequency power supply
50 Processing gas supply source
51 Gas supply pipe
61 heater
62 Power
70 Mounting table
71 Susceptor
72 Insulator frame
73 Holding member
74 drive unit
75 Temperature control section
76 Temperature control unit
77 Exhaust pipe
81 Matching device
82 High frequency power supply
91 Memory
92 Operation input unit
93 Display
94 Control unit
94a Information processing unit
94b arithmetic unit
100 base material
100a Fine pattern part
200 Mold for optical element molding
200a Mold base
L resist
B electron beam

Claims (20)

In order to form a desired shape on the substrate,
In a state where the etching process is performed on the base material,
Irradiating the substrate with light,
A detection step of detecting reflected light or diffracted light from the base material,
An end point determining step of determining an end point of the etching process based on a change in the amount of reflected light or diffracted light. 2. The etching method according to claim 1, wherein in the end point determining step, when a maximum value of the amount of the reflected light or the diffracted light is detected, the end point of the etching process is determined. Based on the amount of reflected light or diffracted light from each part of the base material, a situation determination step of determining the processing status of the etching process in each part of the base material,
The etching method according to claim 1, further comprising an adjusting step of adjusting a condition of the etching process on each part of the base material according to a processing state of the etching process on each part of the base material. Method. In order to form a desired shape on the substrate,
In a state where the etching process is performed on the base material,
Irradiating the substrate with light,
A detection step of detecting diffracted light from the base material,
An end point determining step of determining an end point of the etching process based on a change in the pattern shape of the diffracted light. 5. The etching method according to claim 4, wherein in the end point determining step, when the pattern shape of the diffracted light matches a predetermined pattern shape, the end point of the etching process is determined. The predetermined pattern shape is a pattern shape of the diffracted light when the desired shape is formed on the base material, irradiating the base material with light, and detecting diffracted light from the base material. 6. The etching method according to claim 5, wherein: Based on the pattern shape of the diffracted light, a situation determination step of determining the processing status of the etching process in each part of the base material,
7. The method according to claim 4, further comprising an adjusting step of adjusting an etching process condition for each part of the base material according to a processing state of the etching processing in each part of the base material. Item 10. The etching method according to Item. The etching method according to claim 1, further comprising a stopping step of stopping the etching process on the base material when an end point of the etching process is determined. 9. The etching method according to claim 1, wherein a wavelength of light irradiated in the irradiation step is in a range of 400 nm to 800 nm. 10. In order to form a desired shape on the substrate,
Etching means for performing an etching treatment on the base material,
In a state where the etching process is performed on the base material,
Irradiating means for irradiating the substrate with light,
Detecting means for detecting reflected light or diffracted light from the base material,
An end point determining means for determining an end point of the etching process based on a change in the amount of reflected light or diffracted light. 12. The etching system according to claim 11, wherein the end point determining means determines that the end point of the etching process is when a maximum value of the amount of the reflected light or the diffracted light is detected. Based on the amount of reflected light or diffracted light from each part of the base, based on the amount of reflected light or diffracted light, a situation determination unit that determines the processing status of the etching process in each part of the base,
The method according to claim 10, further comprising an adjusting unit configured to adjust an etching process condition for each part of the base material according to a processing state of the etching process in each part of the base material. Etching system. In order to form a desired shape on the substrate,
Etching means for performing an etching treatment on the base material,
In a state where the etching process is performed on the base material,
Irradiating means for irradiating the substrate with light,
Detection means for detecting diffracted light from the base material,
An etching system comprising: an end point determining unit that determines an end point of the etching process based on a change in the pattern shape of the diffracted light. A storage unit for storing a predetermined pattern shape,
14. The etching system according to claim 13, wherein the end point determining unit determines that the end point of the etching process is when the pattern shape of the diffracted light matches a predetermined pattern shape. The predetermined pattern shape is a pattern shape of the diffracted light when the desired shape is formed on the base material, irradiating the base material with light, and detecting diffracted light from the base material. The etching system according to claim 14, wherein: Based on the pattern shape of the diffracted light, a situation determination unit that determines the processing status of the etching process in each part of the base material,
The apparatus according to claim 13, further comprising an adjusting unit configured to adjust a condition of the etching process on each part of the base material according to a processing state of the etching process on each part of the base material. 17. Item 18. The etching system according to Item. 17. The method according to claim 10, further comprising: stopping means for stopping the etching processing on the base material when the end point of the etching processing is determined by the end point determining means. 18. The described etching system. 18. The etching system according to claim 10, wherein the irradiation unit irradiates the substrate with light having a wavelength in a range of 400 nm to 800 nm. The etching system according to claim 10, wherein the detection unit is a photodiode or a solid-state image sensor. 14. The etching system according to claim 13, wherein the detection unit is a solid-state image sensor.

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