JP2012248779A - Etching device, etching method and etching program of silicon oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the uniformity of etching speed of a processed substrate and between the processed substrates in the etching of silicon oxide, especially, of a plurality of processed substrates.SOLUTION: The etching device 100 of silicon oxide has a process chamber including a substrate support section 15 in which a plurality of processed substrates 20 each having silicon oxide are placed at predetermined intervals so that the substrate surfaces face each other, an introduction section 12 which introduces an etching gas containing hydrogen fluoride reacting on the silicon oxide so as to flow in the substantially horizontal direction along the substrate surface, and a discharge section 16 which discharges reaction products produced by reaction of the etching gas and silicon oxide. The interval is 10.8-22.2 mm.

Description

  The present invention relates to an etching apparatus for silicon oxide, an etching method therefor, and an etching program therefor.

  The technical field to which MEMS (Micro Electro Mechanical Systems) devices using silicon and other materials are applied is steadily expanding. In recent years, the technology has been applied not only to micro turbines and sensors but also to information communication field and medical field. Has also been applied. One of the main elemental technologies that support this MEMS technology is the etching technology for forming microstructures using various materials typified by silicon, especially the etching technology for silicon oxide. Indispensable for the development of MEMS technology.

  Conventionally, elemental technologies for forming various microstructures by etching silicon oxide have been developed. Typically, a silicon oxide etching technique using hydrogen fluoride (HF) is disclosed (for example, Patent Document 1).

Special table 2008-521258 gazette

  By the way, especially in the mass production stage, it is necessary to perform etching processing on a plurality of substrates to be processed at one time. Therefore, it is strictly required to improve the uniformity of the etching rate within the substrate or between the substrates. become. Therefore, in the mass production stage, it is necessary to overcome not only the focus of improving the production efficiency by simply increasing the etching rate but also the technical problem of how to uniformly etch the entire substrate to be processed. However, it is very difficult to control the etching of silicon oxide using hydrogen fluoride as described above, and it is not easy to improve the uniformity of the etching rate within the substrate or between the substrates.

  The present invention improves the uniformity of the etching rate within the substrate to be processed and the uniformity of the etching rate between the substrates to be processed in the etching process of the silicon oxide included in the substrate to be processed, particularly the etching process of a plurality of substrates to be processed. It contributes greatly. Therefore, the present invention can be widely used as a mass production technique.

  The inventors have conducted intensive studies and analyzes on what parameters control, in other words, control the etching rate when etching silicon oxide provided on a plurality of substrates using gaseous hydrogen fluoride. Repeated. As a result, when etching a plurality of substrates to be processed with an etching gas, the inventors improve the uniformity of the etching rate by devising to optimize the gas flow and the reaction product flow. I found out. The present invention was created based on such knowledge.

  One etching apparatus for silicon oxide according to the present invention reacts with a silicon substrate and a substrate supporting portion that arranges a plurality of substrates to be processed with a predetermined interval so that the substrate surfaces face each other. A gas introduction part for introducing an etching gas containing hydrogen fluoride so as to flow in a substantially horizontal direction along the substrate surface, and a reaction product generated by the reaction between the etching gas and the silicon oxide are discharged. And a discharge chamber. In addition, the above-mentioned distance is 10.8 mm or more and 22.2 mm or less.

  According to this silicon oxide etching apparatus, although the detailed mechanism is not yet known, it is considered that the interval between the substrates to be processed can be optimized. As a result, the flow of the etching gas introduced so as to flow along each substrate surface and the flow of the reaction product from those substrates are appropriately controlled as a result from the viewpoint of the uniformity of the etching rate. become. In addition, if the interval is within the above range, a certain number of substrates to be processed that can be processed at a time can be secured, and the overall apparatus can be kept compact.

  Note that there is no particular limitation on the surface area of silicon oxide in the substrate to be processed, which is applied to the above-described silicon oxide etching apparatus invention. However, when the surface area occupied by the above-described silicon oxide on at least one surface of the substrate to be processed is 30% or less with respect to the total area of the one surface, in particular, the invention of the above-described silicon oxide etching apparatus invention A significant effect can be achieved.

  Also, in one silicon oxide etching method of the present invention, a plurality of substrates to be processed having silicon oxide are provided in the process chamber so that the substrate surfaces face each other with an interval of 10.8 mm to 22.2 mm. Then, an etching gas containing hydrogen fluoride that reacts with the silicon oxide is introduced so as to flow in a substantially horizontal direction along the aforementioned substrate surface.

  According to this silicon oxide etching method, although the detailed mechanism is still unknown, it is considered that the interval between the substrates to be processed can be optimized. As a result, the flow of the etching gas introduced so as to flow along each substrate surface and the flow of the reaction product from those substrates are appropriately controlled as a result from the viewpoint of the uniformity of the etching rate. become.

  Further, according to one silicon oxide etching program of the present invention, a plurality of substrates to be processed having silicon oxide are provided in the process chamber so that the substrate surfaces face each other with an interval of 10.8 mm to 22.2 mm. And a gas introduction step for introducing an etching gas containing hydrogen fluoride that reacts with the silicon oxide so as to flow in a substantially horizontal direction along the substrate surface.

  According to this silicon oxide etching program, although the detailed mechanism is still unknown, it is considered that the interval between the substrates to be processed can be optimized. As a result, the flow of the etching gas introduced so as to flow along each substrate surface and the flow of the reaction product from those substrates are appropriately controlled as a result from the viewpoint of the uniformity of the etching rate. become.

  According to one silicon oxide etching apparatus of the present invention, although the detailed mechanism is still unknown, it is considered that the interval between the substrates to be processed can be optimized. As a result, the flow of the etching gas introduced so as to flow along the surface of each substrate and the flow of the reaction products from those substrates are appropriately controlled as a result in terms of the uniformity of the etching rate. Become. In addition, if the interval is within the above range, a certain number of substrates to be processed that can be processed at a time can be secured, and the overall apparatus can be kept compact.

  Further, according to one silicon oxide etching method or silicon oxide etching program of the present invention, the detailed mechanism is not yet known, but it is considered that the interval between the substrates to be processed can be optimized. As a result, the flow of the etching gas introduced so as to flow along the surface of each substrate and the flow of the reaction products from those substrates are appropriately controlled as a result in terms of the uniformity of the etching rate. Become.

It is sectional drawing which shows the structure of the etching apparatus of the silicon oxide in one Embodiment of this invention. It is an enlarged view of the area | region A in FIG. It is a graph which shows the relationship between the etching rate uniformity (%) of the silicon oxide mainly in a wafer surface, and the pressure in a chamber in case one of distance d is 5.1 mm in one embodiment of this invention. It is a graph which mainly shows the relationship between the etching rate uniformity (%) of the silicon oxide in a wafer surface, and the pressure in a chamber in case one of distance d is 10.8 mm in one embodiment of this invention. It is a graph which shows the relationship between the distance d in one Embodiment of this invention, and the uniformity (%) in all the measurement points of the etching rate of a silicon oxide. 4 is a flowchart of etching silicon oxide in one embodiment of the present invention. It is a top view which shows the example of the measurement location for calculating the uniformity of the etching rate in one embodiment of this invention.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this description, common parts are denoted by common reference symbols throughout the drawings unless otherwise specified. In the drawings, the elements of the present embodiment are not necessarily shown to scale. Moreover, in order to make each drawing easy to see, some reference numerals may be omitted. Unless otherwise specified, the flow rates of the following various gases indicate the flow rates in the standard state.

<First Embodiment>
FIG. 1 is a cross-sectional view showing an example of an apparatus configuration of a silicon oxide etching apparatus 100 (hereinafter also simply referred to as an etching apparatus 100) according to this embodiment. FIG. 2 is an enlarged view of region A in FIG. In the present embodiment, the substrate 20 to be processed is a predetermined silicon oxide layer or film (hereinafter collectively referred to as a silicon oxide substrate on the front and / or back surface of a single crystal silicon substrate (6 inch wafer, thickness 625 μm)). In this case, the present embodiment is not limited thereto. However, the present embodiment is not limited to this. For example, the present embodiment can be applied even if the base substrate is a polycrystalline silicon substrate or an amorphous silicon substrate. Similarly, the base substrate is a metal substrate typified by an aluminum substrate, a ceramic substrate typified by an alumina (Al ₂ O ₃ ) substrate, a glass substrate, a resin substrate, or a layer of some materials thereof. Even in the case of stacked multilayer substrates, this embodiment can be applied as long as they have a silicon oxide layer to be etched.

  First, the configuration of the silicon oxide etching apparatus 100 shown in FIG. 1 and the etching process will be described. A substrate to be processed (hereinafter also simply referred to as “substrate” or “wafer”) 20 to be etched is provided in a chamber 10 constituted by a lid portion 10a and a chamber body 10b constituting a part of the chamber. Placed on the substrate support 15. Here, with respect to the chamber 10, the lid 10 a and the chamber body 10 b can be hermetically sealed by the sealing material 11. In FIG. 1, four substrates to be processed 20 are placed to simplify the drawing, but the number of substrates to be processed 20 that can be processed at one time is not limited to this number.

After the substrate 20 to be processed is placed in the chamber 10, the gas (mainly air) in the chamber 10 is exhausted by the pump 18. Thereafter, the flow rate of the etching gas sent from an etching gas cylinder (not shown) is adjusted by the gas flow rate controller 12 a and is introduced into the chamber 10 through the gas introduction unit 12. Note that the etching gas of this embodiment includes hydrogen fluoride (HF) gas 375 sccm (375 mL / min.), Ethanol (C ₂ H ₅ OH) gas 272 sccm (272 mL / min.), And nitrogen (N ₂ ) gas 900 sccm. (900 mL / min.) Of mixed gas. The temperature of the chamber 10 was about 50 ° C.

  When the introduced etching gas passes through the introduction diffusion plate 14a, the etching gas is substantially horizontal along the front surface or the back surface of the substrate 20 to be processed, as shown by the arrow (F) in FIG. Will flow in the direction. Thereafter, the etching gas reacts with silicon oxide formed on the surfaces of the substrates 20,..., 20, whereby moisture (water and / or water vapor, the same applies hereinafter) that is one of the reaction products. Generated. Further, after that, the unreacted etching gas and the reaction product pass through the exhaust diffusion plate 14 b and are then sent to the discharge unit 16 that is sucked by the pump 18. In this embodiment, the introduction diffusion plate 14a is used so that the etching gas flows in a substantially horizontal direction along the front or back surface of the substrate 20 to be processed. However, a method for controlling the gas flow is described below. The present invention is not limited to the introduction diffusion plate 14a, and other known methods can be appropriately employed.

なお、上記数式において、平均値とは、ウェハー面内であれば、ある１つウェハーの面内の測定箇所全てのエッチング速度の平均値であり、「全測定点」であれば、同時に処理した複数のウェハーにおける測定箇所の全てエッチング速度の平均値である。また最大値及び最小値は、それぞれ、算出の対象となる１つ又は複数のウェハーの測定箇所全てのエッチング速度のうちの最大値と最小値である。 Under the above-mentioned conditions, the inventors of the present invention adjust the exhaust capacity of the pump 18 and / or the pressure controller 17 (for example, the opening degree of the valve to be opened and closed) provided in the vicinity of the above-described discharge portion 16 to thereby adjust the chamber 10 and the distance between the substrates 20,... 20 (the distance d between the wafers in FIG. 2; hereinafter, also referred to as “distance d”) were changed. Specifically, for the distance d, etching rate uniformity was measured for four types of distances d of 5.1 mm, 10.8 mm, 16.5 mm, and 22.2 mm. As for the pressure in the chamber 10, the etching rate uniformity was measured in the case of five pressures of 10 kPa, 16 kPa, 20 kPa, 23 kPa, and 26.7 kPa. Note that the measurement in this embodiment is performed uniformly over almost the entire area on the wafer surface, and the number of measurement points is 49 as shown in FIG. Specifically, when the center of the substrate to be processed is positioned at the center of the coordinate axis in FIG. 7, measurement is performed on 8 points, 16 points, and 24 points on the concentric circles in addition to the center point. It was. In the present embodiment, the calculation formula for the uniformity (%) based on the above-mentioned measurement points is as follows.

In the above formula, the average value is the average value of the etching rates of all the measurement points in the surface of a certain wafer if it is within the wafer surface, and if it is “all measurement points”, it is processed simultaneously. It is the average value of the etching rates of all the measurement points in a plurality of wafers. Further, the maximum value and the minimum value are the maximum value and the minimum value, respectively, of the etching rates of all the measurement points of one or a plurality of wafers to be calculated.

  FIG. 3 is a graph mainly showing the relationship between the etching rate uniformity (%) of silicon oxide in the wafer surface and the pressure in the chamber 10 when the distance d is 5.1 mm under the above-described conditions. FIG. 4 is a graph mainly showing the relationship between the etching rate uniformity (%) of silicon oxide in the wafer surface and the pressure in the chamber 10 when the distance d is 10.8 mm under the above-described conditions. is there. In the present embodiment, the target substrate 20 to be measured is the one placed on the upper stage or the middle stage among the several target substrates 20 supported by the substrate support unit 15. , And one on the bottom was extracted. 3 and 4 also show, as reference data, the dependence of the etching rate uniformity (%) on the pressure in the chamber 10 on all the measurement points on the measured three substrates 20 to be processed in the chamber 10.

  As shown in FIG. 3, when the distance d between the substrates 20,..., 20 is 5.1 mm, it becomes clear that the distribution of the etching rate of silicon oxide varies greatly depending on the pressure in the chamber 10. It was. In particular, it has been found that the etching rate uniformity of the silicon oxide in the wafer surface of the substrate 20 to be processed disposed in the middle stage and the lower stage in the substrate support portion 15 is very poor as the pressure increases. As a result, the etching rate uniformity with respect to all of the measurement points on the measured three substrates 20 to be processed also deteriorated.

  On the other hand, as shown in FIG. 4, when the distance d is 10.8 mm, the etching rate uniformity in the wafer plane at a pressure of at least 23 kPa is 7% or less for any substrate 20 at any mounting position. I understood that. More precisely, except for the result (6.6%) of the upper substrate 20 at a pressure of 16 kPa and the result (5.6%) of the lower substrate 20 at a pressure of 23 kPa, all of them are uniform. It was confirmed that the property was less than 5%. As a result, it was found that the etching rate uniformity for all of the measurement points on the measured three substrates to be processed 20 was within a preferable numerical range for performing the etching process.

  Similarly to the above, when the distance d was 16.5 mm or 22.2 mm, the dependency of the etching rate uniformity in the wafer surface on the pressure in the chamber 10 was examined. As a result, if the distance d is 10.8 mm or more, the etching rate uniformity in the wafer surface is the etching treatment if the pressure in the chamber 10 is at least 23 kPa or less for any substrate 20 to be processed. It falls within a preferable numerical range when performing the above.

  Next, FIG. 5 shows the relationship between the distance d and the uniformity (%) at all measurement points of the etching rate of silicon oxide when the pressure in the chamber 10 is 20 kPa and the above-mentioned four types of distances d. It is a graph to show. That is, it is a graph showing the etching rate uniformity with respect to “all measurement points” for which a plurality of wafers are calculated. As shown in FIG. 5, when the distance d is 16.5 mm, the etching rate uniformity at all measurement points is the best (about 5.7%), and the distance d is 10.8 mm or 22.2 mm. It was confirmed that the uniformity was suppressed to 8% or less. Therefore, if the distance d between the substrates 20,..., 20 is at least within the range of 10.8 mm to 22.2 mm, the numerical value is within the preferable range for performing the etching process. If the distance d is 10.8 mm or more and 22.2 mm or less, the substrate 20 to be processed at any mounting position has an etching rate uniformity within the wafer plane of 2.3% or more and 3.2% or less. It was worthy of special mention.

  Further, similarly to the above, the cases where the pressure in the chamber 10 was 10 kPa, 16 kPa, 23 kPa, and 26.7 kPa were also examined. As a result, if the distance d is at least within the range of 10.8 mm or more and 22.2 mm or less, it falls within a preferable numerical range for performing the etching process. In particular, except for the case of 26.7 kPa, it is very preferable in performing the etching process that the distance d is at least in the range of 10.8 mm to 22.2 mm.

  Further, according to the investigation and analysis by the inventors of the present application, when silicon oxide is etched in this embodiment, moisture (water or water vapor) is generated as a by-product (reaction product). Can be a factor that increases Therefore, if the surface area occupied by silicon oxide on at least one surface of the substrate to be processed 20 is 30% or less with respect to the total area of the one surface, the amount of water as a reaction product can be suppressed, so that the wafer The etching rate uniformity within the plane and at all measurement points falls within a preferable numerical range for performing the etching process.

  By the way, as shown in FIG. 1, the etching apparatus 100 according to the present embodiment includes a temperature provided in the gas introduction unit 12 (in the present embodiment, more directly, the gas flow rate controller 12 a), the pump 18, and the chamber 10. The controller (not shown) and the pressure controller 17 provided in the vicinity of the discharge unit 16 are controlled by the control unit 30. As an example of specific control, the control unit 30 includes an etching gas introduction amount in the gas introduction unit 12, a pumping speed in the pump 18, a pressure controller 17 (valve opening degree) provided in the vicinity of the discharge unit 16, and The temperature of the chamber 10 is controlled.

  The control unit 30 included in the above-described etching apparatus 100 is connected to the computer 60. The computer 60 monitors or comprehensively controls the above-described process by an etching program for executing the above-described silicon oxide etching process. The silicon oxide etching program will be described below with reference to a specific manufacturing flowchart. In this embodiment, the above-described etching program is stored in a known recording medium such as an optical disk inserted into a hard disk drive in the computer 60 or an optical disk drive provided in the computer 60. The storage destination of is not limited to this. The etching program can also monitor or control each of the above-described processes via a known technique such as a local area network or an Internet line.

  FIG. 6 is a flowchart of etching of silicon oxide according to this embodiment.

  As shown in FIG. 6, when the silicon oxide etching program of this embodiment is executed, first, in step S101, after the substrate 20 to be processed is transferred into the chamber 10, the gas in the chamber 10 is exhausted. . Thereafter, in steps S102 to S104, the silicon oxide included in each of the substrates 20 to be processed is etched in the chamber 10.

  Specifically, first, in step S <b> 102, an etching gas introduction operation is performed from the gas introduction unit 12 into the chamber 10. In addition, in step S103, an operation for adjusting the pressure in the chamber 10 to a desired pressure value is performed. Here, the pressure in the chamber 10 is performed by adjusting the exhaust capacity of the pump 18 and / or the pressure controller 17 (for example, the opening degree of the valve) provided in the vicinity of the discharge unit 16 described above. Moreover, it is a suitable one aspect | mode which can be employ | adopted also when step S102 and step S103 are performed substantially simultaneously.

  Then, the etching step is performed while maintaining the above conditions for a predetermined time (step S104). After the etching of the silicon oxide is stopped (step S105), the program of the present embodiment sets the processing target substrates 20,..., 20 to be taken out (step S106), and then the program of the present embodiment ends. . At this time, the substrate 20,..., 20 may be directly taken out from the chamber after the atmosphere in the chamber 10 is restored to the atmospheric pressure, but the chamber 10 is kept in a reduced pressure state in the chamber 10. The substrates 20 to be processed may be taken out via loaders / unloaders (not shown) that can be connected.

  As described above, the silicon oxide etching program of the present embodiment integrally controls each condition in the etching process. As a result of the execution of the etching program of this embodiment, the uniformity of the etching rate within the substrate to be processed and the uniformity of the etching rate between the substrates to be processed in the etching process of silicon oxide provided on a plurality of substrates to be processed are realized. Is done.

  As described above, modifications that exist within the scope of the present invention including other combinations of the embodiments are also included in the scope of the claims.

DESCRIPTION OF SYMBOLS 10 Chamber 10a Cover part 10b Chamber main body 11 Sealing material 12 Gas introduction part 12a Gas flow controller 14a Diffusion plate 14b Diffusion plate 15 Substrate support part 16 Discharge part 17 Pressure controller 18 Pump 20 Processed substrate (substrate)
30 control unit 60 computer 100 etching apparatus

Claims (9)

A substrate support portion for disposing a plurality of substrates to be processed having silicon oxide so that the substrate surfaces face each other at a predetermined interval;
A gas introduction part for introducing an etching gas containing hydrogen fluoride that reacts with the silicon oxide so as to flow in a substantially horizontal direction along the substrate surface;
A discharge part for discharging a reaction product generated by a reaction between the etching gas and the silicon oxide;
A process chamber comprising:
The interval is 10.8 mm or more and 22.2 mm or less,
Silicon oxide etching equipment. The pressure in the process chamber is 16 kPa or more and 23 kPa or less,
The silicon oxide etching apparatus according to claim 1. The surface area occupied by the silicon oxide of at least one surface of the substrate to be processed is 30% or less with respect to the total area of the one surface.
The silicon oxide etching apparatus according to claim 1 or 2. In the process chamber, a plurality of substrates to be processed having silicon oxide are disposed so that the substrate surfaces face each other with an interval of 10.8 mm to 22.2 mm,
An etching gas containing hydrogen fluoride that reacts with the silicon oxide is introduced so as to flow in a substantially horizontal direction along the substrate surface.
Etching method of silicon oxide. An etching gas containing hydrogen fluoride that reacts with the silicon oxide is introduced so as to flow along the substrate surface so that the pressure in the process chamber is 16 kPa or more and 23 kPa or less.
The method for etching silicon oxide according to claim 4. An arrangement step of arranging a plurality of substrates to be processed having silicon oxide in the process chamber so that the substrate surfaces face each other with an interval of 10.8 mm to 22.2 mm,
A gas introduction step for introducing an etching gas containing hydrogen fluoride that reacts with the silicon oxide so as to flow in a substantially horizontal direction along the substrate surface;
Silicon oxide etching program. The gas introduction step is a step of introducing the gas so that the pressure in the process chamber is 16 kPa or more and 23 kPa or less.
The silicon oxide etching program according to claim 6.   A recording medium on which the etching program according to claim 6 is recorded. A silicon oxide etching apparatus comprising a control unit controlled by the etching program according to claim 6.

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