JP2003303788A - Etching equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide etching equipment of high reliability wherein a uniform etching characteristic can be obtained over the diameter of a silicon substrate. <P>SOLUTION: The etching equipment 20 is provided with: a reaction chamber 10 having an exhaust vent 9; a table 2 which is installed in the reaction chamber and on which a silicon substrate 1 is mounted; a rotatingly driving part 8 for rotating the table; and gas supply piping having a nozzle 3 which supplies gas to the silicon substrate in the reaction chamber. The tip 3a of the nozzle is made to face the substrate at a position which is located extending from 0.65 times to 0.75 times the distance from the center of the substrate to the end in the radial direction of the substrate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching apparatus used for chemical etching suitable for a fine processing technique typified by semiconductor processing, and more particularly to an etching apparatus using xenon difluoride gas.

[0002]

2. Description of the Related Art In recent years, research and development have been actively conducted for the purpose of miniaturizing and improving the performance of devices and existing equipment using fine processing technology. Especially the micromachine is silicon LS
As a mass production technology next to the I technology, the development attempting to apply it to various devices has been announced by each industry and research institute. In addition, it is possible to use the technologies accumulated in the semiconductor field together,
Since existing semiconductor equipment can be used as it is, even complex devices can be collectively manufactured on a wafer. In addition, the silicon wafer that serves as the substrate can be stably supplied regardless of price fluctuations and market trends based on the track record of semiconductor devices.

Further, as semiconductor technology has been improved, it has become possible to increase the diameter of silicon wafers, so that processing equipment suitable for a large surface area and precision of etching technology are required. For devices that require a particularly complicated structure, such as those with a multi-layered hollow structure, or specific devices that retain their structure with micron-order support legs, use a silicon film as a sacrificial layer. Is common. Further, hollowing using bulk silicon requires higher etching accuracy in order to prevent mutual interference due to etching with an adjacent structure.

The current micromachine technology is an application of the technology accumulated in semiconductor processing, but in the future, development and technology accumulation specific to the micromachine suitable for various devices will be required. For example, as a technique for forming a deep hole or groove in a silicon substrate, KOH or TMAH (Tetra-me
Thyl Ammonium Hydroxide) is used for anisotropic etching by a wet method and ICP-RIE (Induct) which is a dry method.
There is a collectively Coupled Plasma-Reactive Ion Etching) technology.

Further, in the dry etching method utilizing electromagnetic waves or heat, there is a concern that the element may be damaged or destroyed by thermal stress or plasma damage. In the wet method, problems such as damage due to a liquid flow caused by sliding with an etching solution, damage to a structure due to tension in a state of being pulled up from a bath, damage in a drying step, and the like are regarded as problems. To solve these problems, xenon difluoride (XeF ₂ ) is used for etching silicon material without using plasma.
There is an isotropic chemical etching technique using. This xenon difluoride (XeF ₂ ) has a sublimation property and is a kind of a silicon etching gas containing fluorine in a gas state. This xenon difluoride gas enables high-speed etching at room temperature and also has material selectivity with respect to the silicon oxide film. For this reason, application to various devices that require surface micromachining technology and deep etching is being studied.

A conventional etching apparatus is shown below in FIG.
This will be described with reference to FIGS. FIG. 14A is a schematic diagram showing the structure of a conventional etching apparatus. This etching apparatus has a tank 64 filled with xenon difluoride gas, a flow rate adjusting chamber 62, and a reaction chamber 60 connected to the flow rate adjusting chamber 62 by a pipe. The reaction chamber 60 is provided with a table 52 on which a silicon substrate 51 to be etched is placed and an exhaust port 59.
A pressure adjusting valve 65 and a pump 66 are connected to the. In this etching device, first, the tank 64 is filled with xenon difluoride gas, the accumulated gas is supplied to the flow rate adjusting chamber 62, and then mixed with the inert gas 67 and continuously sucked into the reaction chamber 60. Etching is performed.

Further, in this etching apparatus, as shown in FIG.
As shown in FIG. 4B, the etching gas is released by using a cylindrical ring tube 53 having a diameter larger than that of the silicon substrate 51. The ring tube 53 has a plurality of holes 5
3a is provided, and gas is emitted from each hole 53a toward the center of the silicon substrate 51 at various angles.

In the above-mentioned etching apparatus, the chemical reaction with the silicon substrate 51 is performed at room temperature without using a physical phenomenon for accelerating the etching reaction using plasma or electromagnetic waves such as high frequency waves or a method for activating the gas reaction due to heat. Etching is performed by utilizing a specific reaction. Further, etching is performed by balancing the suction and exhaust of gas into the reaction chamber 60 while controlling the exhaust amount of the reaction chamber 60 and maintaining a constant pressure. In this etching apparatus, the flow rate control chamber 62 has a volume that is at least twice as large as that of the reaction chamber 60, and the mixing of the inert gas 67 and the etching gas is performed by adjusting the valve in front of the reaction chamber 60. Thus, a large amount of gas is sucked into the reaction chamber 60.

Next, the process of etching the silicon substrate 51 using the above etching apparatus will be described with reference to FIG.
Based on the description. (1) Start the vacuum pump 66. (2) The supply valves 68a and 68b are opened to supply the nitrogen gas 67 to the reaction chamber 60. It should be noted that the standard of completion of opening to the atmosphere is determined by the supply time of the nitrogen gas 67. (3) After confirming the completion of the above work, the supply of the nitrogen gas 67 is stopped, the door 61 is opened, and the table 5 installed in the reaction chamber 60.
The silicon substrate 51 is installed at the designated position 2. After the installation is completed, the door 61 is closed and the inside of the reaction chamber 60 is evacuated by the pump 66 to complete the installation of the silicon substrate 51 in the reaction chamber 60. (4) Next, the sublimated xenon difluoride gas is filled in the tank 64. (5) Next, the gas is supplied to the flow rate adjusting chamber 62,
The valves 68a, 68b, 68c are adjusted and mixed with the inert gas 67, and the generated mixed gas is sucked to the reaction chamber 60 side. As a result, chemical etching of the silicon substrate 51 with xenon difluoride gas is started.

As a conventional etching apparatus, for example, JP-A-10-317169 proposes an etching apparatus for continuously supplying sublimated xenon difluoride gas to a reaction chamber in order to improve the processing capacity of the apparatus. Has been done.

[0011]

However, in the above-mentioned conventional etching apparatus, since the gas is supplied from the ring tube 53 to the end of the substrate 51, the gas is supplied near the end of the substrate 51. There is a problem that it is done excessively compared to the center. This is particularly remarkable when, for example, a silicon substrate 51 having a large surface area is used. FIG. 15 is a distribution diagram of etching amounts obtained by performing pulse etching processing on a silicon substrate 51 having a diameter of 15.24 cm (6 inches) by a conventional apparatus including the ring tube 53 shown in FIG. In FIG. 15, the horizontal axis is the number of 24 measurement points (etching monitor) from one end to the other end over the diameter of the silicon substrate 51, and the vertical axis is the etching amount (μm) at each measurement point. ing. As can be seen from FIG. 15, the etching reaction at the end of the silicon substrate 51 strongly appears, and the tendency to show the concave etching distribution appears strongly. Therefore, there is a problem that the etching uniformity in the silicon substrate 51 is poor.

Therefore, an object of the present invention is to provide a highly reliable etching apparatus which can obtain uniform etching characteristics over the diameter of a silicon substrate.

[0013]

An etching apparatus according to the present invention includes a reaction chamber having an exhaust port, a table provided inside the reaction chamber for mounting a silicon substrate, and a rotary drive for rotating the table. And a gas supply pipe having a nozzle for supplying a xenon difluoride gas onto the silicon substrate inside the reaction chamber, the tip of the nozzle being a radial end from the center of the silicon substrate. It is characterized in that it is arranged so as to face a position between 0.65 times and 0.75 times the distance to the part.

Further, the etching apparatus according to the present invention is the etching apparatus, further comprising a synchronization control device for synchronizing the rotation of the table by the rotation drive unit and the supply of the gas by the gas supply pipe. It is characterized by

Further, the etching apparatus according to the present invention is
In the etching apparatus, the tip of the nozzle is
It is characterized by having a taper shape in which the diameter increases toward the tip.

Furthermore, the etching apparatus according to the present invention is the etching apparatus described above, wherein the outermost diameter of the table is substantially equal to or larger than the diameter of the substrate, and the diameter of the substrate is 1 or less. It is characterized in that it is within the range of 2 times or less.

The etching apparatus according to the present invention includes a reaction chamber having an exhaust port, a table provided in the reaction chamber for mounting a silicon substrate, a rotary drive unit for rotating the table, and a reaction chamber provided in the reaction chamber. A gas supply pipe for supplying a xenon fluoride gas; and a flat plate provided between the gas supply pipe and the table in the reaction chamber and having a plurality of through holes through which the gas can pass. Characterize.

Further, an etching apparatus according to the present invention is the etching apparatus described above, characterized in that it is provided with a plurality of flat plates having different projected positions of the through holes.

Further, the etching apparatus according to the present invention is
The etching apparatus is characterized in that the reaction chamber further includes exhaust ports provided in two spaces facing each of both surfaces of the flat plate.

Furthermore, the etching apparatus according to the present invention is the etching apparatus, further comprising an opening device for opening the table to the outside of the reaction chamber.

The etching apparatus according to the present invention is the etching apparatus, further comprising a mixing chamber connected to the outside of the reaction chamber via the gas supply pipe.

[0022]

DETAILED DESCRIPTION OF THE INVENTION An etching apparatus according to an embodiment of the present invention will be described below with reference to the accompanying drawings.
In the drawings, substantially the same members are designated by the same reference numerals.

Embodiment 1. The etching apparatus according to the first embodiment of the present invention will be described with reference to FIG. Figure 1
FIG. 3 is a schematic view showing an internal structure of a reaction chamber 10 which constitutes the etching apparatus 20. This etching device 20
Is a depressurizable reaction chamber 10, a table 2 for rotatably mounting the silicon substrate 1 inside the reaction chamber 10, and an etching gas supplied to the silicon substrate 1 on the table 2 inside the reaction chamber 10. And a nozzle 3 for Moreover, the reaction chamber 10 and the mixing chamber 12 connected by the piping of the nozzle 3 may be further provided. In this etching device 20,
The tip 3a of the nozzle 3 faces the substrate 1 at a distance of 0.65 to 0.75 times the distance from the center of the silicon substrate 1 to the end in the radial direction. Thereby, the etching uniformity within the surface of the silicon substrate 1 can be kept within about ± 10%. The relationship between the position where the tip portion 3a of the nozzle 3 faces the silicon substrate 1 and the etching uniformity will be described in detail later. In this etching device 20,
The etching gas 4 is sprayed using the nozzle 3 facing the silicon substrate 1 between 0.65 times and 0.75 times the distance from the center of the silicon substrate 1 to the ends in the radial direction.
As a result, it is possible to improve the etching amount and the etching uniformity required for etching the sacrificial layer provided on the silicon substrate 1 or the bulk silicon.

Next, each member constituting the etching apparatus 20 will be described. First, a table 2 in which a silicon substrate 1 is rotatably arranged inside a reaction chamber 10.
Will be described. The table 2 is rotated by a rotation drive unit 8 connected from the outside of the reaction chamber 10 via a rotary shaft 7. The rotation drive unit 8 controls the rotation speed change and the drive / stop operation. Also, in Table 2,
A step corresponding to the size of the silicon substrate 1 to be arranged is provided. By arranging the silicon substrate 1 on the table 2 in accordance with this step, it is possible to prevent the positional displacement at the time of arrangement and also prevent the positional displacement when the table 2 is rotated. The height of the step provided on the table 2 is 0.2 to 0.4 mm depending on the thickness of each silicon substrate 1. The diameter of the same step in which the silicon substrate 1 is housed is about 4 mm larger than the diameter of the silicon substrate 1.
It is made large. Therefore, when the table 2 is rotated, the silicon substrate 1 may rotate without being fixed in the step of the table 2. Therefore, the silicon substrate 1
It is preferable to roughen the back surface of the above in advance. As a method of this roughening treatment, for example, honing or blasting treatment may be used. By this, grinding particles can be sprayed on the flat surface of the table 2 with which the back surface of the silicon substrate 1 is in contact, and unevenness can be provided on the flat surface. Furthermore, the orientation flat of the silicon substrate 1,
By providing a step with a shape corresponding to the notch (V-shaped groove) shape applied to an 8-inch (20.32 cm) wafer,
It is possible to prevent the silicon substrate 1 from rotating independently of the rotation of the table 2.

Further, the table 2 is mounted with the silicon substrate 1 and is rotated during the etching process. Regarding the rotation drive of the table 2 by the rotation drive unit 8, high speed rotation in which centrifugal force acts on the silicon substrate 1 or low speed rotation in which the rotation drive becomes unstable is not preferable. Therefore, in order to improve the etching uniformity, it is preferable that the rotation drive unit 8 rotate the table 2 and the silicon substrate 1 in a rotation speed region where the rotation is stably performed. The rotation speed of the rotary drive is preferably 0.1 rpm to 100 rpm, more preferably 0.1 rpm to 10 rpm. In this etching apparatus 20, good etching characteristics can be obtained by rotating the table 2 and the silicon substrate 1 at a low speed of about 1 rpm.

Next, the nozzle 3 for supplying the etching gas 4 to the silicon substrate 1 in the reaction chamber 10 will be described.
The nozzle 3 is composed of a pipe part connected from the outside of the reaction chamber 10 to the inside of the reaction chamber 10, and a tip part 3 a for supplying an etching gas to the silicon substrate 1. This nozzle 3
May be made of, for example, a stainless material. Note that the material is not limited to the stainless steel material, and as the material that is difficult to react with xenon difluoride as an etching gas, for example, an aluminum material whose surface is coated with an oxide film by alumite treatment or the like may be used.

Here, the xenon difluoride gas used as the etching gas will be described. Although this xenon difluoride (XeF ₂ ) is a milky white solid at room temperature and pressure, it has sublimation properties and can be vaporized by a sublimation action by evacuation. In the gaseous state, it becomes a kind of silicon etching gas containing fluorine, which enables high-speed etching at room temperature and also has material selectivity with respect to the silicon oxide film. This xenon difluoride gas reacts with silicon according to the reaction formula shown below to perform isotropic chemical etching. 2XeF ₂ + Si → 2Xe + SiF ₄

FIG. 2 shows a front view and a bottom view of the tip of the nozzle 3. As shown in FIG. 2A, the nozzle 3 has a tip portion 3a having a tapered shape, that is, a shape in which the diameter is expanded toward the tip. As a result, the gas spray can be widely dispersed over the surface of the silicon substrate 1. Further, the tip shape of the nozzle 3 is not limited to the circular shape (FIG. 2 (b)), and any shape such as an ellipse or a quadrangle (FIG. 2 (c), (d)) may be used as long as it does not hinder the gas spraying. Shapes can also be used. In addition, when the inclination of the tip diameter is increased, cracks or the like occur at the bent portion or the tip of the nozzle 3. Therefore, for example, the tip portion of the nozzle 3 is formed as an independent tip member 3a, and the tip portion is attached to the pipe portion. The nozzle 3 may be configured.

Further, the nozzle 3 may be provided with a displacement mechanism (not shown) for displacing the nozzle 2 in the horizontal direction with respect to the table 2. With this displacement mechanism, the silicon substrate 1
The nozzle 3 can be retracted when the table is installed on the table 2, the silicon substrate 1 can be easily arranged, and damage due to a collision or the like at that time can be prevented.
As a mechanism for retracting the nozzle 3 from the upper portion of the table 2, for example, a mechanism for providing a bellows at a fitting portion with the reaction chamber 10 may be used. This allows the nozzle 3 to be easily moved to the retracted position. It is necessary to fix the nozzle 3 at the specified position every time the silicon substrate 1 is loaded. Therefore, for example, it is preferable to provide a stopper mechanism such as a hook near the fitting portion of the reaction chamber 10. With this stopper mechanism, the position of the nozzle 3 can be easily adjusted.

Further, other members constituting this etching apparatus will be described. The reaction chamber 10 is provided with an exhaust port 9 and can be depressurized by exhausting from the exhaust port 9. Further, the reaction chamber 10 is equipped with a vacuum gauge 5 for measuring the internal pressure. The vacuum gauge 5 sets the pressure in the reaction chamber 10 to an appropriate pressure. Further, the reaction chamber 10 has an opening door 11 on the top surface for loading / unloading the silicon substrate 1 into / from the reaction chamber 10. The silicon substrate 1 is put in and taken out after the inside of the reaction chamber 10 is returned to the atmosphere and then the open door 11 is pulled up and fixed. The open door 11 may be provided with a viewing window 6 for observing the silicon substrate 1 from the outside. Also,
The etching apparatus 20 includes a mixing chamber 12 connected to a nozzle 3 that supplies an etching gas into the reaction chamber 10. The mixing chamber 12 supplies the mixed gas 4 into the reaction chamber 10 through the nozzle 3 after generating the etching gas and the inert gas for dilution at a predetermined ratio.

Next, the gas piping system of the etching apparatus 20a will be described with reference to FIG. The etching apparatus 20a includes a reaction chamber 10 and a mixing chamber 12 that supplies a mixed gas containing an etching gas into the reaction chamber 10. Nitrogen or air (G
A pipe for supplying as3) is provided. A valve V6 is provided in the pipe. Further, the reaction chamber 10 and the mixing chamber 12 are connected by a pipe connected to a nozzle 3 for supplying a gas to the silicon substrate 1 in the reaction chamber 10, and a valve V3 is provided in the pipe. In addition, vacuum gauges 5 and 15 (G1 and G) are provided in the reaction chamber 10 and the mixing chamber 12, respectively.
2) is provided. Furthermore, the reaction chamber 10 and the mixing chamber 12
Is connected to the pump 16 through the exhaust ports 9 and 14. The pipes are provided with valves V4 and V5, respectively, so that the reaction chamber 10 and the mixing chamber 12 can be independently evacuated. The mixing chamber 12 includes two pipes, a pipe for supplying a xenon difluoride gas (Gas1) and a pipe for supplying an inert gas nitrogen gas (Gas2). The pipes are provided with valves V1 and V2, respectively. Although nitrogen was used as the inert gas mixed with xenon difluoride, the present invention is not limited to this, and another inert gas such as argon may be used.

Further, each procedure of the etching process performed by using the etching apparatus 20a will be described below with reference to FIG. First, a preparatory step of setting the silicon substrate 1 in the reaction chamber 10 and evacuating the reaction chamber 10 and the mixing chamber 12 to a predetermined vacuum value will be described. (A) First, when the inside of the reaction chamber 10 is under reduced pressure, the valve V6 is opened and nitrogen gas (gas3) is supplied in order to return the inside to atmospheric pressure. Nitrogen was used as the gas (gas3) supplied to the reaction chamber 10. After setting the pressure in the reaction chamber 10 to atmospheric pressure, the valve V6 is closed, the opening door 11 is opened, and the silicon substrate 1 is placed on the table 2. (B) After the installation of the silicon substrate 1 is completed, the open door 11 is closed, the valve V5 is opened, and the reaction chamber 10 is opened by the pump 16.
Exhaust the inside. (C) When the vacuum gauge 5 is monitored and the vacuum value defined in the reaction chamber 10 has been reached, the valve V5 is closed and left standing for a while. At this time, it is confirmed whether the vacuum value in the reaction chamber 10 has changed. During the initial exhaust, the ultimate vacuum degree frequently changes due to the influence of dew condensation or the like. Even if the mixed gas 4 is sprayed in this state, the accuracy of the pressure control is not sufficient, and there is a risk that the etching uniformity will be impaired. Therefore, for example, it is desirable that the evacuation is repeated a plurality of times to confirm that the degree of vacuum in the reaction chamber 10 is stable, and then the process proceeds to the next step. For example, in this etching apparatus 20, the influence on the etching was removed by confirming that there was no pressure change by performing a leak test for 1 minute after repeatedly exhausting the gas about 5 times. Further, by providing a heating facility such as a heater around the reaction chamber 10 to remove the influence of dew condensation,
A more stable etching process can be performed. (D) The valve V4 connected to the mixing chamber 12 is opened to exhaust gas. (E) The vacuum gauge 15 is monitored, and when the inside of the mixing chamber 12 reaches a specified vacuum value, the valves V1 and V2 are sequentially opened to remove the gas remaining in the pipe. At this time, the main valve of each gas cylinder is closed. (F) When the above process is completed, each valve (V1, V2,
By sequentially closing V4), the steps up to the etching preparation are completed. In addition, in parallel with the leak test, the mixing chamber 12
The time can be shortened by exhausting the inside and each pipe. In this case, the steps (d) to (f) may be processed in parallel. However, the valves V3 and V5 are closed during this parallel processing.

Next, the step of producing the mixed gas containing the xenon difluoride gas in the mixing chamber 12 will be described. (G) After confirming that the vacuum value in the reaction chamber 10 is normal by monitoring the vacuum gauge 5, the table 2 is rotated by the rotary drive unit 8 via the rotary shaft 7. The table 2 is rotationally driven at a constant speed until the etching process is completed. (H) Open the main valves of the xenon difluoride cylinder and the nitrogen cylinder. (I) Next, the valve V1 is opened to supply the xenon difluoride gas into the mixing chamber 12. (J) When the pressure value of the xenon difluoride gas reaches a predetermined value, the valve V1 is closed and the valve V2 is opened to supply the nitrogen gas into the mixing chamber 12. For example, the flow rate was controlled using an orifice or a mass flow controller to supply the nitrogen gas into the mixing chamber 12. Since the interior of the mixing chamber 12 is exhausted to about 9 Pa, nitrogen can be supplied using back pressure. (K) When the pressure inside the mixing chamber 12 reaches a predetermined pressure value, the valve V2 is closed. As a result, the mixed gas 4 containing the xenon difluoride gas is generated in the mixing chamber 12. in this case,
The mixing ratio of the mixed gas 4 (xenon difluoride / nitrogen) was 0.4.

Further, the mixed gas 4 generated in the mixing chamber 12 is passed through the nozzle 3 to the silicon substrate 1 in the reaction chamber 10.
Next, the step of performing the etching process by supplying the same to the substrate will be described. (L) Mixed gas 4 having a predetermined pressure value in the mixing chamber 12
After the generation of the silicon substrate, the valve V3 is opened, and the silicon substrate 1 placed on the table 2 in the reaction chamber 10 through the nozzle 3
Is supplied with mixed gas 4. This starts the etching reaction. (M) The vacuum gauge (G1) 5 is monitored and the mixed gas 4 is continuously supplied until a predetermined pressure value is reached. In this case, the pressure value in the reaction chamber 10 gradually increases due to the supply of the mixed gas 4. (N) When the pressure inside the reaction chamber 10 reaches a predetermined pressure value, the valve V3 is closed. (O) After holding for a certain period of time, the valve V5 is opened to exhaust the residual gas such as the reacted gas and the unreacted gas. The vacuum gauge 5 is monitored to confirm that the inside of the reaction chamber 10 has reached a predetermined vacuum value, and the valve V5 is closed. At this stage, the etching reaction is completed. (P) The valve V4 is opened to exhaust the inside of the mixing chamber 12. (Q) After exhaustion is completed, V6 is opened, the inside of the reaction chamber 10 is returned to the atmosphere, and then the silicon substrate is removed from the table 2. (R) Finally, the valve V5 is opened and the inside of the reaction chamber 10 is evacuated until a predetermined vacuum value is reached. This completes the etching process using the etching apparatus 20a.

Further, in this etching apparatus 20a, 1
Not only the etching process performed only once but also pulse etching in which the etching process is repeated a plurality of times can be performed. By reducing the amount of etching gas supplied in one etching process and repeating the etching process a plurality of times, the required etching amount can be obtained and the etching characteristics can be finely controlled.
The procedure of this pulse etching will be described below. (1) The etching process can be performed once by performing the above steps (a) to (o). In this case, the etching amount per time can be controlled by controlling the predetermined pressure value when the mixed gas 4 is supplied into the reaction chamber 10 in the procedure (m). In addition, when the mixed gas 4 is generated in the procedure (j), the inside of the reaction chamber 10 may be evacuated to about 4 Pa in advance as a parallel process. Thereby, the mixed gas 4 can be supplied into the reaction chamber 10 due to the back pressure difference between the reaction chamber 10 and the mixed gas 4 generated in the mixing chamber 12. (2) Further, the above steps (a) to (o) are repeated a predetermined number of times to repeat the etching process. (3) After that, the steps (p) to (r) described above can be performed to complete the pulse etching process.

Next, a method for evaluating the etching characteristics of the etching process by the etching apparatus 20, 20a will be described. Here, the etching characteristics are evaluated using the etching amount measurement silicon substrate 21 shown in FIGS. 4 and 5. This etching amount measurement silicon substrate 2
1 has etching monitors 23 for measuring the etching amount, which are provided at a plurality of positions in the plane. Each etching monitor 23
The etching characteristics are evaluated by measuring the etching amount at. Specifically, a silicon oxide film 24 is formed as a mask film on the etching amount measurement silicon substrate 21. Further, on the substrate 21, etching monitors 23 each having a rectangular slit-shaped opening 25 formed in the silicon oxide film 24 are arranged in parallel from one end to the other end having a diameter passing through the center of the substrate. Therefore, by measuring the etching amount in each etching monitor 23, the etching characteristics such as the etching amount distribution can be evaluated.

This etching amount measuring silicon substrate 21
The manufacturing method of will be described. As the silicon substrate 21, a mirror-polished silicon substrate 21 having a thickness of 0.625 mm and a diameter of 6 inches was used. Also, the silicon substrate 2
A structure in which etching monitors 23 having rectangular openings 25 are arranged in parallel on one surface was manufactured by the following procedure. (1) First, the silicon oxide film 24 is formed on the silicon substrate 21 by plasma CVD to a thickness of about 500 nm. The silicon oxide film 24 is formed by etching the silicon film with xenon difluoride gas to about 100.
Since it has a selectivity of 0 or more, it was used as a mask film. However, the material is not limited to the silicon oxide film, and another material having selectivity with respect to silicon, such as silicon nitride, may be used as the mask film. Further, here, since the measurement is performed from above the mask film 24 with an optical microscope at the time of the etching evaluation, it is necessary to use a visible transparent material. (2) Next, using the photoengraving technique, the silicon oxide film 2
A pattern is formed on the substrate 4 in which slit-shaped openings made of a photosensitive resin material are arranged in parallel at equal intervals. (3) After completion of pattern transfer, RIE (Plasma-Reactive
The silicon oxide film 24 is etched by using a plasma etching process such as Ion Etching) or IBE (Ion Beam Etching) to expose the silicon substrate 21 through the slit-shaped openings. (4) After that, the photosensitive resin material on the silicon oxide film 24 is removed by using, for example, acetone and a resist stripping solution to complete the production of the etching characteristic evaluation silicon substrate 21.

The silicon substrate 21 for measuring the etching amount obtained by the above procedure will be described. The slit-shaped etching monitor 23 formed on the silicon oxide film 24 of the substrate 21 has a pattern having a width of about 1 μm and a length of about 20 μm. Twenty-four etching monitors 23 are arranged in the horizontal direction with respect to the orientation flat 22.
It is formed in parallel from the one end portion through the center of the substrate to the other end portion in parallel. The bottom surface of this etching monitor needs to expose the bulk silicon 21 as shown in the sectional view of FIG. Therefore, in this evaluation, the step of removing the natural oxide film is performed in advance. Thermal oxide film etching rate 2 nm / sec
Silicon substrate 2 in a hydrofluoric acid solution with a concentration that can be etched with
The natural oxide film on the surface of the substrate 21 was removed by immersing 1 for about 5 seconds.

Next, a method of evaluating etching characteristics using the etching amount measuring silicon substrate 21 will be described. This evaluation method is performed according to the following procedure. (1) First, the etching amount measurement silicon substrate 21 is carried into the reaction chamber 10. (2) Next, the silicon substrate 21 is etched under various conditions. At this time, the etching monitor 23 at each measurement point isotropically chemically etches the silicon substrate 21. (3) After the etching process, the etching amount of each etching monitor 23 of the silicon substrate 21 is measured.

A method of measuring the etching amount will be described. The etching amount is measured by an optical microscope. FIG. 5 is a cross-sectional view showing the state before and after the etching monitor 23 isotropically etched (FIG. 5A).
FIG. 6B is a plan view after etching (FIG. 5C). The area where the etching gas circulates under the silicon oxide film 24 of the mask film and is hollowed is the bulk silicon 2
Compared with the case where 1 exists, the light transmittance is different. Therefore,
The entire width of the area hollowed out in the plane is observed with an optical microscope. The value of half of this full width is estimated as the etching amount. That is, as shown in the sectional view of FIG. 5B, since the etching with the xenon difluoride gas is isotropic etching, the etching progresses from the opening 25 of the slit in the depth direction of the silicon substrate 21. Together with the silicon oxide film 2
Etching proceeds along the substrate surface at the bottom of 4. For this reason, a cavity portion is formed by etching with a width d that is approximately the same width as the etching depth d, from the slit center to the left and right in the plane. Therefore, it is possible to estimate the etching depth d to be equivalent to ½ of the entire width of the cavity observed in the lateral direction of the etching monitor 23. Instead of the optical microscope, the etching amount may be measured using a dimension measuring instrument that can obtain dimensional accuracy on the order of microns.

(4) Using the etching amount obtained in the procedure of (3) above, the in-plane etching uniformity of the silicon substrate 21 was evaluated. For the etching uniformity, the maximum value, the minimum value, and the average value of the etching amount were calculated, and by using these, the following formula was used. Etching uniformity (%) =
((Maximum value-minimum value) / (2 x average value)) x 100

Although a slit-shaped etching monitor 23 is provided here to evaluate the etching uniformity, the shape of the etching monitor 23 is not limited to a rectangular slit, and conversely, the etching monitor 23 is a convex isolated pattern.
May be For example, an isolated pattern of a photosensitive resin material is provided on the silicon substrate 1 by photolithography, and this is used as the etching monitor 23. In the measurement of the etching amount, since the etching progresses from the exposed silicon surface around the isolated pattern, a convex isolated pattern is formed. In measuring the etching amount, the etching amount is calculated from the step difference of the convex portion obtained by removing the photosensitive resin material. In this case, for example, the etching amount of the obtained convex portion may be calculated from the step using a stylus type step gauge. In addition, the isolated pattern width must have a convex cross section in the end against side etching from four sides,
For example, if etching is performed by 10 μm in the depth direction,
The width of the isolated pattern should be at least 20 μm or more.

Bulk silicon is exposed on the back surface of the silicon substrate 1 unless special treatment is performed. If the mixed gas 4 is released in this state, the reaction on the back surface becomes dominant, and the etching uniformity and the reproducibility between the substrates 1 are hindered and the production efficiency is significantly reduced. Therefore, as the back surface protection film, for example, a silicon oxide film is preferably formed by plasma CVD or the like to protect the back surface. It should be noted that the back surface protective film may be made of a material that can obtain selectivity by etching xenon difluoride into the silicon substrate, such as an organic photosensitive resin, a silicon nitride film, a silicon carbide film, or a magnesium oxide film. . However, in order to suppress the influence of warpage on the silicon substrate 1 as much as possible, an internal stress of 10 ⁹ dyne /
It is desirable to form the back surface protective film by selecting a material having a thickness of about cm ² and a film thickness of about several hundreds nm.
This suppresses the warpage of the silicon substrate 1,
For example, it is possible to suppress the influence on the covering property of the wiring material and the insulating film provided on the silicon substrate 1.

Next, in the etching process of the silicon substrate 1 using this etching apparatus 20a, the relationship between the position of the tip 3a of the nozzle 3 and the diameter of the table 2 and the etching characteristics will be described with reference to FIGS. explain.
First, the position where the tip 3a of the nozzle 3 faces the silicon substrate 1 will be examined. FIG. 6A is a graph showing the relationship between the position where the tip 3a of the nozzle 3 faces the silicon substrate 1 and the etching uniformity. Each pulse etching is repeated 10 times. The position r of the tip 3a of the nozzle 3 is the distance from the center of the substrate 1 at the facing point on the silicon substrate 1 facing the tip 3a, as shown in FIG. 6 (b). The unevenness shown in the distribution diagram indicates the etching distribution tendency of the entire silicon substrate 1. For example, when the etching amount in the center of the silicon substrate 1 tends to be larger than the etching amount in the peripheral portion, it is made convex, while when the etching amount in the end portion is larger than the others, it is made concave. Further, in the figure, the results using two types of silicon substrates 1 having different diameters (diameter 15.24 cm (6 inches φ), diameter 20.32 cm (8 inches φ)) are shown.

As shown in FIG. 6A, the etching distribution tendency changes from convex to concave depending on the position of the tip 3a of the nozzle 3. This is because the silicon substrate 1 has a diameter of 1
20.32 cm even for 5.24 cm (6 inches)
The same tendency is shown in the case of (8 inches). Specifically, the tip portion 3a of the nozzle 3 is provided near the center of the silicon substrate 1.
In the case of arranging and spraying with a gas, the etching reaction tends to be concentrated near the center of the substrate 1. On the other hand, if the tip 3a of the nozzle 3 is moved away from the center of the substrate 1 toward the end in the radial direction, the value of the etching uniformity becomes small, and the etching uniformity is improved. Further, when the tip portion 3a of the nozzle 3 is brought closer to the end portion, the etching distribution tendency becomes concave, the value of the etching uniformity becomes large, and it deteriorates. Therefore, the etching uniformity depends on the tip 3 of the nozzle 3.
It depends on the position of a. Further, as shown in FIG. 6B, in order to reduce the value of etching uniformity, the nozzle 3
It is desirable that the tip portion 3a of the above is opposed to the silicon substrate at a distance of 0.65 to 0.75 times the distance from the center of the silicon substrate 1 to the end portion. As a result, the etching uniformity can be suppressed within ± 10%. This tendency can be applied even when the diameter of the silicon substrate 1 is different.

Next, the height h of the tip portion 3a of the nozzle 3 from the silicon substrate 1 will be examined. FIG. 6C shows
Height h between tip 3a of nozzle 3 and silicon substrate 1
3 is a graph showing the relationship between the etching uniformity and the etching uniformity. A silicon substrate 1 having a diameter of 15.24 cm (6 inches φ) was used. The number of pulse etching processes is 1
0 times. As shown in FIG. 6C, the higher the height h of the tip 3a of the nozzle 3 from the substrate 1, the smaller the etching uniformity value.

Further, the radius of the table 2 on which the silicon substrate 1 is placed will be examined. FIG. 7A shows a difference L between the radius of the table 2 and the radius of the silicon substrate 1 shown in FIG.
It is a graph which shows the relationship between (mm) and etching uniformity. As shown in FIG. 7A, when the diameter of the table 2 is made larger than the diameter of the silicon substrate 1, the value of etching uniformity is gradually increased and deteriorates. Therefore, the value of the etching uniformity can be reduced by bringing the diameter of the table 2 close to the diameter of the silicon substrate. That is, the silicon substrate 1
It is possible to solve the problem that the vicinity of the edge of the is selectively etched. Specifically, as shown in FIG. 7A, the diameter 1
In the case of the substrate 1 having a length of 5.24 cm, the radius of the table 2 is equal to or larger than that of the silicon substrate 1 and is 10 mm or less, whereby the etching uniformity can be suppressed to ± 10% or less. The same tendency is exhibited when the silicon substrate 1 has different diameters. Therefore, by setting the ratio of the diameter of the table 2 to the diameter of the silicon substrate 1 (diameter of the table / diameter of the silicon substrate) in the range of 1 to 1.2, the etching uniformity can be suppressed to ± 10% or less. . In addition, the table 2 is arranged outside the end of the silicon substrate 1 in the radial direction by about 10
It is preferable to provide a step and a protrusion as shown in FIG. 7B in a region within mm so as to serve as a stopper when the silicon substrate 1 rotates.

Furthermore, this etching apparatus 20, 2
0a, the etching characteristics of the etching performed under the preferable conditions based on the above-mentioned examination are shown in FIG.
Will be explained. 7C shows the measurement point No. of the etching monitor. 3 is a graph showing the relationship between the amount of etching and the amount of etching at each measurement point. As conditions for this etching, first, the substrate 1 has a diameter of 15.24 cm (6 inches φ).
The silicon substrate of was used. In addition, the tip 3a of the nozzle 3
Are opposed to each other at a distance of 0.65 to 0.75 times the distance from the center of the silicon substrate 1 to the end in the radial direction. Specifically, the tip 3a of the nozzle 3 was opposed to the edge of the substrate 1 in the radial direction by 45 mm from the center of the substrate 1. Furthermore, nozzle 3
The height h from the tip 3a to the substrate 1 was 65 mm. Furthermore, the tip 3a of the nozzle 3 has a wide tip by providing a taper with an inclination of about 30 °. In addition, the number of times of pulse etching is 10 times (10 Lo
(c) of FIG. 7 for the case of performing 20 times (20 Loops). As shown in FIG. 7C, the distribution of the etching amount is almost flat regardless of the number of pulse etching processes, and the etching uniformity is ± 10% or less. Therefore, there is no region that is selectively etched in the plane of the silicon substrate 1.

Embodiment 2. An etching apparatus according to the second embodiment of the present invention will be described. This etching apparatus is different from the etching apparatus according to the first embodiment in that the supply of the mixed gas 4 from the nozzle 3 and the rotation of the table 2 are synchronized. Thereby, the mixed gas can be uniformly sprayed over the entire surface of the silicon substrate, and the etching uniformity of the silicon substrate 1 can be improved.

The structure of this etching apparatus will be described. FIG. 8 is a schematic diagram showing the configuration of this etching apparatus. In this etching apparatus, as compared with the etining tool apparatus according to the first embodiment, a drive control unit 26 for controlling the driving / stopping of the table 2 and valves V1, V2, V3, V4.
A sequencer 27 that controls opening and closing of V5, and a computer 28 that transmits a control signal to the sequencer are further provided. Each valve V1, V2, V3, V4, V5 is a solenoid valve whose opening and closing can be controlled by an electric signal. The computer 28
The opening / closing of the valve and the rotation of the table 2 are controlled by a program read in the internal memory and executed.

Next, an example of how the supply of the mixed gas 4 and the rotation of the table 2 are synchronized in the etching process using this etching apparatus is shown in FIGS. 9 (a) and 9 (b). Each of these will be described. First,
A case in which the valve opening / closing operation is performed in accordance with the rotation of the table 2 will be described with reference to FIG. In FIG. 9A, the horizontal axis represents time, and the vertical axis represents, from top to bottom, the pulse etching period, the rotational position of the table 2, and the valve V.
1 ON / OFF (open / closed), valve V2 ON / OF
F (open / close), ON / OFF of valve V3 (open / close),
ON / OFF (open / close) of valve V4, O of valve V5
N / OFF (open / closed) is shown. In this case, the table 2 is continuously rotated.

When the opening / closing operation of the valve is performed in accordance with the rotation of the table 2, the procedure is as follows. Figure 9
(A) shows a time-series change of the open / closed state of the valve and the rotation of the table 2. Here, the table 2 and the silicon substrate 1 during the pulse etching process are always driven in the same cycle. (A) Xenon difluoride gas is supplied into the mixing chamber 12 by opening / closing the valve V1, and then nitrogen gas is supplied into the mixing chamber 12 by opening / closing the valve V2. (B) Wait for the time indicated by the shaded area until the specific position of the table 2 reaches the predetermined position, open the valve V3 when the specific position of the table 2 reaches the predetermined position, and supply the mixed gas to the nozzle 3 for the predetermined time. To the reaction chamber 10 via. As a result, one etching process is performed. (C) After a predetermined time has passed, the valve V3 is closed and the valve V4 is closed.
Is opened and closed to exhaust the inside of the mixing chamber 12. The first (1 Loop) pulse etching is completed by the series of procedures described above. (D) After that, the valves V1 and V2 are opened and closed to supply xenon difluoride gas and nitrogen to the mixing chamber 12. In addition, as parallel processing, the valve V5 is opened and the exhaust of the reaction chamber 10 is advanced. (E) Wait for the time of the shaded portion until the table 2 reaches the predetermined position, open the valve V3, and add the mixed gas to the reaction chamber 10
And perform the next etching process. By repeating the above procedure a plurality of times as necessary, the mixed gas can be uniformly dispersed in the surface, and the etching uniformity can be improved.

As another example, the valve V4 is opened in front of the mesh portion shown in FIG. 9 (a) to evacuate the mixing chamber 12, and then the mixed gas 4 is generated with timing. Good. In addition, the dotted line in the figure in (a) of FIG.
This is for clarifying the position of the table 2 when the spraying of the mixed gas 4 is finished and the valve V3 is closed.

Further, referring to FIG. 9B, the table 2
A description will be given of a case where the control of the rotation drive / stop operation and the control of the valve opening / closing operation are performed respectively. Compared with the procedure shown in FIG. 9A, this procedure is the same until the end of the first pulse etching in procedure (c), but a stop operation for stopping the rotation drive of the table 2 is performed. Is different. As a result, the waiting time until the next etching process can be reduced and the etching efficiency can be improved. Even when the stop operation for stopping the rotation drive of the table 2 is performed, the rotation speed is 1 rp.
In the case of m, it did not rotate by inertia.

Since the supply time of the xenon difluoride filled in the cylinder into the mixing chamber 12 may vary depending on the solid amount, for example, a plurality of cylinders should be prepared to reduce the solid amount. It is more preferable to alternately use them and to provide a filling chamber between the mixing chamber 12 and the xenon difluoride cylinder.

Embodiment 3. An etching apparatus according to Embodiment 3 of the present invention will be described. Compared with the etching apparatuses according to the first and second embodiments, this etching apparatus is provided between the nozzle 3 for supplying the mixed gas 4 into the reaction chamber 10 and the silicon substrate 1 as shown in FIG. The difference is that a flat plate 31 having a plurality of through holes 32 through which the mixed gas 4 can pass is interposed. The plurality of through holes 32
By providing the flat plate 31 having the above, it is possible to disperse the region of the etching selectivity by the nozzle 3 and improve the etching uniformity. Further, the flat plate partitions the inside of the reaction chamber 10 into a first chamber containing the nozzle 3 and a second chamber containing the silicon substrate 1. The first chamber and the second chamber are provided with exhaust ports 29a and 29b, respectively, and when exhausted, they are exhausted from both sides of the flat plate 31, respectively.
It is possible to prevent the flat plate 31 from being distorted or damaged.

Next, members constituting this etching apparatus will be described. In this etching apparatus, a flat plate 31 having a plurality of through holes 32 is provided between the nozzle 3 and the silicon substrate 1. The flat plate 31 is supported by a support base 33. The shape of the through hole 32 is preferably circular or elliptical, but is not limited to this and other shapes may be used as long as they do not hinder the gas spray. Further, it is preferable that the tip of the opening of the through hole 32 is provided with an inclination by, for example, a spot facing process. This facilitates the smooth introduction of the mixed gas 4 from the first chamber to the through hole 32. Further, for the flat plate 31, it is preferable to use a material which has selectivity and durability to a metal material such as aluminum or stainless steel or xenon difluoride gas such as polycarbonate.

In this etching apparatus, by using the flat plate 31, the nozzle 3 can be easily arranged regardless of the diameter of the silicon substrate 1. In addition, by directly installing the flat plate 31 on the support base 33 in the reaction chamber 10, the flat plate 3
1 can be easily attached and detached. Further, the flat plate 31 having the through holes 32 corresponding to the structure of the silicon substrate 1 can be replaced if necessary. Note that the flat plate 31 includes, for example, a support base 33.
It is preferable to provide a knob in the vicinity. Thereby, the flat plate can be easily attached and detached without affecting the through hole 32.

Furthermore, in this etching apparatus, as shown in FIG.
As shown in FIG. 5, the exhaust port 29b is also provided in the first chamber on the nozzle 3 side of the reaction chamber 10 divided into two by the flat plate 31. As a result, the first chamber can be sufficiently exhausted, and the flat plate 31 can be prevented from being distorted. Further, it is possible to prevent the flat plate 31 from dropping or being damaged from the support base 33. It should be noted that, for example, by removing the four corners of the flat plate 31 and providing openings larger than the through holes 32 on the flat plate 31, the respective vacuum levels of the partitioned first chamber and second chamber can be kept substantially the same. You can In addition, since gas flows out from the opening during the gas spraying, it is necessary to set the conditions in consideration of the total flow rate of the mixed gas 4 required for etching.

The first chamber on the nozzle 3 side, which is separated from the flat plate 14, may be integrated with the open door 11, for example. As a result, the table 2 can be exposed to the outside of the reaction chamber 10 when the door 11 is opened, and the silicon substrate 1 can be taken in and out. Furthermore, the silicon substrate 1 is provided on the side surface of the reaction chamber 10.
A vacuum chamber dedicated to transfer and an opening valve or door suitable for transportation may be provided. Further, a transfer mechanism or the like for transferring the silicon substrate 1 from the reaction chamber 10 to the vacuum chamber may be provided. As a result, it is not necessary to detach the flat plate 31, and the silicon substrate 1 can be transferred while keeping the degree of vacuum inside the reaction chamber 10 constant.

Fourth Embodiment An etching apparatus according to Embodiment 4 of the present invention will be described. Compared with the etching apparatus according to the third embodiment, this etching apparatus has a structure in which a plurality of flat plates 31a and 31b having a plurality of through holes 32 through which a mixed gas can pass are stacked, as shown in FIG. The difference is that it is interposed between the nozzle 3 and the silicon substrate 1. In this etching apparatus, a structure in which a plurality of flat plates 31a and 31b are stacked is used, and the flat plate 3
By forming a cavity between 1a and the flat plate 31b, the mixed gas can be subdivided over the surface of the substrate 1 and uniformly dispersed. Further, by stacking the plurality of flat plates 31a and 31b, more strength can be obtained.

The structure of an example of this etching apparatus will be described with reference to FIG. In this etching apparatus, a structure in which two flat plates 31a and 31b are superposed is interposed between the nozzle 3 and the silicon substrate 1. The flat plate 31a and the flat plate 31b have through holes 32, respectively.
Are overlapped so that the projection positions of are different. For example, on the basis of the arrangement position of the through hole 32 of the flat plate 31a facing the nozzle 3 side, the flat plate 31b facing the table 2 side is
As shown in the figure, the mixed gas 4 can be finely dispersed by arranging the mixed gas 4 around the through-hole 16 at regular intervals. Further, the structure can be reinforced by providing the reinforcing material 34 between the flat plate 31a and the flat plate 31b. It is preferable that at least a plurality of reinforcing members 34 support the flat plates 31a and 31b in order to maintain strength. Further, the reaction chamber 10 is divided into a first chamber including the nozzle 3 and a second chamber including the table 2 by a structure composed of the flat plates 31a and 31b, and exhaust to each of the first chamber and the second chamber. It is preferable to provide the mouths 29a and 29b. Thereby, the first chamber and the second chamber can be maintained at substantially the same degree of vacuum. As an example of the installation position of the exhaust port, for example,
By providing an exhaust port (not shown) suitable for exhausting the inside of the cavity between the flat plate 31a and the flat plate 31b and providing a differential pressure between the first chamber and the cavity, the mixed gas 4 Can be smoothly guided to the cavity.

FIG. 11B is a schematic diagram showing the structure of another example of this etching apparatus. This etching apparatus is different from the etching apparatus shown in FIG. 11A in that an opening is provided in the peripheral portion of the flat plate 31a facing the nozzle 3 side. The mixed gas 4 flows from this opening along the side wall of the reaction chamber 10 to the cavity between the flat plate 31b. As a result, the amount of unreacted gas remaining without passing through the through hole 32 of the flat plate 31a on the nozzle 3 side can be reduced, and the utilization efficiency of the mixed gas can be improved.

The configuration of this etching apparatus will be described. The flat plate 3 arranged on the nozzle 3 side as shown in the drawing
The through hole 32 of 1a is arranged so as to easily pass through the vicinity of the center of the silicon substrate 1. Furthermore, each flat plate 31a, 31
b may be coupled using a screw or the like. Alternatively, they may be bonded with a resin adhesive or the like. Since it is difficult to provide the through hole 32 in the fitting portion, it is preferable that the joint area is as small as possible. Further, here, the fitting portion is provided near the center 35 of the silicon substrate 1, but the fitting portion is not limited to this. For example, a plurality of fitting portions may be provided outside the region of the silicon substrate 1 that does not hinder the gas spray, and the reinforcing member may be provided. 34 may be substituted. Further, by providing the groove 36 in the fitting portion with the nozzle 3 side, screw fixing and coupling can be easily performed. Furthermore, it is easy to provide a cavity between the flat plates 31a and 31b. In addition,
It is desirable that the step difference of the groove 36 is adjusted to the same height as the reinforcing member 34. By providing the groove 36, the strength of the structure can be improved.

Further, FIG. 12 shows a plurality of flat plates 31a, 3a.
It is the schematic which shows the structure which integrated the structure which consists of 1b, and the nozzle 3 with the open door 11. By opening and closing the integrated open door 11, the nozzle 3 and the plurality of flat plates 31a, 31b
Since the table 2 can be opened to the outside of the reaction chamber 10 without removing and, the silicon substrate 1 can be easily loaded and unloaded.

FIG. 13 is an enlarged cross-sectional view showing a structure including a flat plate 31a and a flat plate 31b, and a peripheral portion of a through hole 32 which penetrates both the flat plate 31a and the flat plate 31b.
As shown in the drawing, a column 37 extending from a flat plate 31a arranged on the nozzle 3 side is passed through the inside of the through hole 32 to finely disperse the gas in the local portion of the silicon substrate 1 for gas spraying 5. be able to. Although the column 37 penetrates the through hole 32 provided in the flat plate 31a on the table 2 side, the diameter of the through hole 32 needs to be larger than that of the column 37. For example, by providing a gap of 1 mm or more on one side with respect to the diameter of the column 37, it is possible to prevent mutual interference caused by distortion due to vacuum exhaust or the like.
The through hole 32 may also be provided inside the pillar 37 extending from the nozzle 3 side. Further, the support column 37 may be flush with the flat plate 31b arranged on the table 2 side as shown in FIG. 13, or may be projected from the plane of the flat plate 31b. Further, the pillar 37 may have an inverted trapezoidal shape in which the upper surface is narrower than the bottom surface, for example. Furthermore, it is preferable to provide the through hole 32 that penetrates the support column 37 with the same inclination as that of the support column 37, but the invention is not limited to this. For example, a shape that prevents mutual interference due to distortion is preferable. The cross-sectional shape of the pillar 37 is
For example, any shape such as a circle, a triangle, a quadrangle, a rhombus, or an ellipse may be used.

[0067]

As described above, according to the etching apparatus of the present invention, the tip of the nozzle is between 0.65 and 0.75 times the distance from the center of the silicon substrate to the end in the radial direction. To face the substrate. As a result, the value of in-plane etching uniformity of the silicon substrate can be lowered, and the etching uniformity can be improved.

Further, the etching apparatus according to the present invention further comprises a synchronization control device for synchronizing the rotation of the table and the supply of the xenon difluoride gas from the nozzle.
As a result, the gas can be supplied uniformly over the surface of the substrate, and the etching uniformity can be improved.

Further, according to the etching apparatus of the present invention, the tip of the nozzle is tapered so that the diameter increases toward the tip. This allows the gas to be dispersed over the surface of the silicon substrate.

Further, according to the etching apparatus of the present invention, the outermost diameter of the table is set within the range of 1.0 to 1.2 times the diameter of the silicon substrate. Thereby, the etching uniformity can be improved.

According to the etching apparatus of the present invention, a flat plate having a plurality of through holes through which gas can pass is interposed between the gas supply pipe and the table in the reaction chamber.
As a result, the etching gas from the nozzle can be dispersed uniformly over the surface of the silicon substrate, and the etching uniformity can be improved.

Further, according to the etching apparatus of the present invention, a plurality of flat plates having different projected positions of the through holes are further provided. This allows the gas to be uniformly dispersed over the surface of the silicon substrate.

Further, according to the etching apparatus of the present invention, the exhaust ports are provided in the two spaces respectively facing both sides of the flat plate. This can prevent the flat plate from being distorted or damaged during exhaust.

Furthermore, the etching apparatus according to the present invention further includes an opening device for opening the table to the outside of the reaction chamber. Thereby, even when the flat plate is interposed between the gas supply pipe and the table, the table can be opened to the outside of the reaction chamber and the substrate can be easily placed.

Further, according to the etching apparatus of the present invention, the reaction chamber is provided with the mixing chamber for supplying the mixed gas. This allows the xenon difluoride gas and the inert gas to be mixed at a desired mixing ratio.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an etching apparatus according to a first embodiment of the present invention.

2A is a side view of a tip portion of a nozzle in the etching apparatus of FIG. 1, and FIGS. 2B to 2D are bottom views of the tip portion of the nozzle.

FIG. 3 is a schematic diagram showing a piping system of the etching apparatus according to the first embodiment of the present invention.

FIG. 4 is a plan view of an etching amount measuring silicon substrate according to a first embodiment of the present invention.

5A is a sectional view of the etching monitor of the etching amount measuring silicon substrate of FIG. 4 before etching, and FIG. 5B is a sectional view of FIG. 4A after etching,
(C) is a plan view of (b).

FIG. 6A is a graph showing the relationship between the position r at which the tip of the nozzle faces the silicon substrate and the etching uniformity, and FIG. 6B is the position r at which the tip of the nozzle faces the substrate. FIG. 4C is a schematic diagram showing the relationship between the height h of the tip of the nozzle from the substrate and the etching uniformity, and FIG. 7D is a schematic diagram showing the height h of the nozzle. Is.

FIG. 7A is a graph showing a relationship between a radius difference L between a table and a silicon substrate and etching uniformity, and FIG. 7B is a schematic diagram illustrating the radius difference;
(C) is a graph showing an etching amount distribution at each measurement point under preferable etching conditions.

FIG. 8 is a schematic diagram showing a configuration of an etching apparatus according to a second embodiment of the present invention.

9 (a) is a timing chart of rotation driving of a table and valve opening / closing in pulse etching performed using the etching apparatus of FIG. 8, and FIG. 9 (b) is
It is an example of an etching method different from (a), and is a timing chart of rotation drive and stop operation of a table, and valve opening / closing.

FIG. 10 is a schematic diagram showing a configuration of an etching apparatus according to a third embodiment of the present invention.

FIG. 11A is a schematic diagram showing a configuration of an etching apparatus according to Embodiment 4 of the present invention, and FIG.
It is a schematic diagram showing composition of an etching device different from (a).

FIG. 12 is a schematic diagram showing the configuration of still another etching apparatus according to the fourth embodiment of the present invention.

FIG. 13 is an enlarged cross-sectional view around a through hole in the structure of another etching apparatus according to the fourth embodiment of the present invention.

FIG. 14A is a schematic view showing a configuration of a conventional etching apparatus, and FIG. 14B is a perspective view showing an arrangement of a ring tube and a silicon substrate in the reaction chamber of FIG.

15 is a graph showing an etching amount distribution of a silicon substrate by the conventional etching apparatus of FIG.

[Explanation of symbols]

1 silicon substrate, 2 table, 3 nozzles, 3a
Tip, 4 mixed gas, 5 vacuum gauge, 6 viewing window, 7
Rotating shaft, 8 rotation drive, 9 exhaust port, 10 reaction chamber,
11 open door, 12 mixing chamber, 14 exhaust port, 16 pump, 20 etching device, 21 silicon substrate, 2
2 orientation flat, 23 etching monitor, 24 mask film, 25 opening, 26 drive controller, 27 sequencer, 28 computer, 29a,
29b Exhaust port, 31, 31a, 31b Flat plate, 32
Through hole, 33 support base, 34 reinforcing material, 35 fixing screw, 36 groove, 37 post, 51 silicon substrate, 52
Table, 53 ring pipe, 59 exhaust port, 60 reaction chamber, 61 open door, 66 pump, 62 flow rate control chamber, 64 tank, 65 pressure control valve, 67 inert gas, 68, 69 valve

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiyuki Nakagi             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F term (reference) 5F004 AA01 BA19 BB28 BB32 BC02                       BC03 CA02 CA05 DA19 DA25                       DB01 EA06 EA07 EB08

Claims (9)

[Claims] 1. A reaction chamber having an exhaust port, a table provided inside the reaction chamber for mounting a silicon substrate, a rotation drive unit for rotating the table, and the silicon substrate inside the reaction chamber. And a gas supply pipe having a nozzle for supplying xenon difluoride gas, the tip of the nozzle being 0.65 to 0.75 times the distance from the center of the silicon substrate to the end in the radial direction. An etching apparatus characterized in that it is arranged to face a position between two times. 2. The etching apparatus according to claim 1, further comprising a synchronization controller that synchronizes the rotation of the table by the rotation drive unit and the supply of the gas by the gas supply pipe. 3. The etching apparatus according to claim 1, wherein the tip end portion of the nozzle has a tapered shape whose diameter increases toward the tip end. 4. The outermost diameter of the table is substantially equal to or larger than the diameter of the substrate and is 1.2 times or less the diameter of the substrate. 1
The etching apparatus according to any one of 1 to 3. 5. A reaction chamber having an exhaust port, a table provided in the reaction chamber for mounting a silicon substrate, a rotation drive unit for rotating the table, and a xenon difluoride gas supply into the reaction chamber. And a flat plate provided between the gas supply pipe and the table in the reaction chamber and having a plurality of through holes through which the gas can pass. 6. The etching apparatus according to claim 5, further comprising a plurality of flat plates having different through-hole projection positions. 7. The etching according to claim 5, wherein the reaction chamber further comprises exhaust ports provided in two spaces facing each of both surfaces of the flat plate. apparatus. 8. The apparatus according to claim 1, further comprising an opening device for opening the table to the outside of the reaction chamber.
The etching apparatus according to any one of items 1 to 7. 9. The etching apparatus according to claim 1, further comprising a mixing chamber connected to the outside of the reaction chamber via the gas supply pipe.