JP2008041744A - Dry etching method or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry etching device or the like capable of easily forming a taper to the side face of a trench formed to a work. <P>SOLUTION: In a dry etching method, an etching gas and a deposition gas are introduced alternately into a reaction chamber 2, a plasma is generated, and the trench section 25 is formed to the work 4 fitted to the reaction chamber by the plasma. In the dry etching method, the other gas is added to one gas when the etching gas or the deposition gas is introduced into the reaction chamber 2, and both gases are introduced into the reaction chamber 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present application relates to a dry etching method and the like.

  Conventionally, dry etching apparatuses using plasma are known. The dry etching apparatus, for example, introduces a predetermined process gas into a vacuum vessel, excites the process gas with a high frequency power source, generates plasma, and etches a semiconductor substrate with radicals generated by the plasma. It is.

  In the etching method using the dry etching apparatus, after the step of introducing the etching gas into the vacuum container and exhausting the gas from the vacuum container is completed, the deposition gas is introduced into the vacuum container and the gas is discharged. It is possible to form an anisotropic etching groove with respect to the wafer by alternately performing the process comprising the step of exhausting the gas from the vacuum container in a short time (several seconds) (for example, , See Patent Document 1).

  Moreover, the dry etching apparatus can control the taper angle formed on the side surface of the notch portion by the strength of etching or deposition. Specifically, the taper angle is controlled by adjusting the flow rate of the etching gas or deposition gas and the time of each processing step for introducing the etching gas or deposition gas into the vacuum vessel. It was.

JP 7-503815 A

  However, if the taper angle is controlled by adjusting the flow rate of the etching gas or deposition gas or the time of each processing step for introducing the etching gas or deposition gas into the vacuum vessel using the above method, the notch portion The quality of the product deteriorates, such as the bottom of the surface becomes rough, and in some cases, there is a problem that it cannot be used. In addition, since the bottom surface is rough (residue), the etching rate cannot be stabilized throughout the process, and the etching rate is lowered.

  In recent years, it has become necessary to manufacture molds for micro-channel devices in the field of MEMS (Micro Electro Mechanical Systems) at low cost using semiconductor materials. In such cases, it is necessary to pull out the molds. Therefore, it is necessary to form a channel groove whose side wall has a forward tapered shape.

  Further, in the formation of a weight portion of a minute sensor element (acceleration sensor, angular velocity sensor, etc.) using a semiconductor micromachining technology, an object to be etched is made high aspect and anisotropic by so-called DRIE (Deep Reactive Ion Etching). (Slot side wall is vertical or forward taper) needs to be processed.

  Therefore, in order to eliminate an example of such a problem, the present application can easily control the taper on the side surface of the groove formed in the workpiece without preventing the etching rate from decreasing and reducing the quality of the product. An object of the present invention is to provide a dry etching apparatus and the like that can be used.

  In order to solve the above-described problem, in the dry etching method according to claim 1 of the present application, an etching gas and a deposition gas are alternately introduced into the reaction chamber (2) to generate plasma, and the plasma is generated by the plasma. In the dry etching method for forming the groove (25) with respect to the workpiece (4) placed on the workpiece, when the etching gas or deposition gas is introduced into the reaction chamber, the one gas is added to the other gas. Gas is added and both gases are introduced into the reaction chamber.

  The dry etching method according to claim 2 of the present invention is the dry etching method according to claim 1, wherein the introduction amount of the different gas is greater than 0% and not more than 5% with respect to the gas to be introduced. It is characterized by being.

  The dry etching method according to claim 3 is characterized in that in the dry etching method according to claim 1 or 2, dry etching is performed by adding a deposition gas together with the etching gas during etching with an etching gas. And

  Further, the dry etching method according to claim 4 of the present invention is the dry etching method according to claim 3, wherein the workpiece in the groove formed in the workpiece by adding a deposition gas to the etching gas. The angle of the side surface with respect to the surface is defined in the range of 85 degrees to less than 90 degrees.

  The dry etching method according to claim 5 is characterized in that, in the dry etching method according to claim 1 or 2, the etching gas is added together with the deposition gas after the etching with the etching gas.

  The dry etching apparatus according to claim 6 of the present invention alternately introduces an etching gas and a deposition gas into the reaction chamber to generate a plasma, and the workpiece is installed in the reaction chamber by the plasma. When the etching gas or deposition gas is introduced into the reaction chamber, the other gas is added to the one gas and both gases are introduced into the reaction chamber. A gas introduction means (16) is provided.

  According to the dry etching method or the like of the present invention, it is possible to form a taper on the side surface of the groove formed in the workpiece without deteriorating the quality as a product. With this etching method, the taper angle formed on the side surface of the groove formed in the workpiece can be easily controlled. In addition, according to the conventional dry etching method, a residue is generated on the bottom surface, resulting in a decrease in the etching rate. However, according to the dry etching method of the present application, a decrease in the etching rate of the workpiece due to the residue on the bottom surface can be prevented. It is possible to shorten the process of forming a fine tapered groove having a high aspect ratio and reduce the cost.

  The best mode for carrying out the present application will be described below with reference to the drawings. In the embodiment described below, the present application is applied to a commercially available dry etching apparatus using a so-called inductively coupled plasma etching method (ICP etching method). As the plasma source, in addition to the ICP type, capacitively coupled plasma (CCP type: Capacitively-Coupled Plasma), electron cyclotron resonance plasma (ECP type: Electron-Coupled Plasma), microwave excited surface wave plasma (SWP: Surface Wave) Similar effects can be obtained even when using Helicon Wave Plasma (HWP), Helicon Wave Plasma (HWP), or the like. The “forward taper” described later refers to the shape of the side surface narrowing toward the bottom surface of the groove portion, and the “reverse taper” refers to the shape of the side surface widening toward the bottom surface of the groove portion. . The “taper angle” refers to the angle of the side surface of the groove with respect to the surface of the workpiece.

  1 is a configuration diagram of the dry etching apparatus of the present application, FIG. 2 is a time chart of an etching step and a deposition step when forming a groove portion on a sample, and FIG. 3 is a structural diagram of the groove portion.

  As shown in FIG. 1, the dry etching apparatus S of this embodiment includes a reaction chamber 2 configured to have a vacuum vessel. Inside the reaction chamber 2, a sample stage 6 on which a sample 4 is installed at the bottom is provided. The sample 4 is, for example, a silicon wafer on which a photoresist mask patterned by a photolithography method is formed. The sample stage 6 functions as a lower electrode and is connected to an applied bias power source 8 provided outside the reaction chamber 2. A predetermined power is applied to the sample stage 6 by the applied bias power supply 8.

  An induction coil 10 that functions as an upper electrode is provided above the reaction chamber 2 so as to face the sample stage 6. The induction coil 10 is connected to a coil power source 12 provided outside the reaction chamber 2, and predetermined power is applied to the induction coil 10 by the coil power source 12.

  Further, the sample stage 6 and the induction coil 10 are provided apart from each other by a space necessary for generating plasma.

  An inlet 2a for introducing a process gas into the reaction chamber 2 is formed at the upper end of the reaction chamber 2, and the process gas is supplied into the induction coil 10 through the inlet 2a. . The introduction port 2 a is connected to a gas supply line 15 including a gas pipe provided outside the reaction chamber 2.

  The gas supply line 15 communicates with the storage chambers 18 to 18 c storing a predetermined type of process gas via a gas flow rate controller 16 and a predetermined valve body 17. The valve body 17 has a function of supplying a predetermined process gas to the gas flow rate controller 16 by opening and closing, and the gas flow rate controller 16 supplies the process gas supplied from each of the storage chambers 18 to 18 c via the valve body 17. It has a function of adjusting so that a predetermined flow rate is supplied into the reaction chamber 2. Note that the gas flow rate controller of the present embodiment functions as the gas introduction means of the present application.

The predetermined process gas stored in the storage chambers 18 to 18c is, for example, a fluorine supply gas or a deposition gas (hereinafter referred to as a deposition gas) as an etching gas (hereinafter referred to as an etching gas). And a low molecular gas such as oxygen (O ₂ ) and nitrogen (N ₂ ) supplied to the reaction chamber as needed, and an inert noble gas such as argon gas (Ar). It is known that a fluorine supply etching gas is used as an etching gas, and a fluorocarbon having a particularly low fluorine to carbon ratio is used as a deposition gas. In this embodiment, a gas generally referred to as SF ₆ is used as an etching gas, and a gas generally referred to as C ₄ F ₈ is used as a deposition gas. However, the etching gas and the deposition gas are not limited to the above combinations, and may be any of the above gases that are corrosive to the workpiece and a gas that forms a fluororesin-based deposition film on the section. That's fine.

  On the other hand, an exhaust port 2 b for exhausting process gas from the inside of the reaction chamber 2 to the outside is formed at the lower end of the reaction chamber 2. The exhaust port 2b is connected to an exhaust line 20 including a gas pipe provided outside the reaction chamber.

  An exhaust system including a turbo molecular pump 22 and a dry pump (or a rotary pump) (not shown) is connected to the exhaust line 20 via a pressure adjustment controller 21, and the process gas contained in the reaction chamber 2 at a predetermined pressure. Is exhausted to the outside. The configuration of the exhaust line is not limited to the above configuration as long as the reaction chamber can be maintained at a vacuum level in the range of 0.1 to 10 Pa (Pascal) during the process.

  In the etching apparatus S configured as described above, for example, when the valve body 17 is controlled to be opened and closed by a control unit (not shown), the flow paths of the etching gas and the deposition gas are alternately switched at a predetermined time. The etching gas and the deposition gas are controlled by the gas flow rate controller 16 at a predetermined flow rate, and are alternately supplied to the inside of the reaction chamber 2 through the gas introduction port 2a. The air is exhausted from the outside.

  Here, in the etching step in which the etching gas is introduced into the reaction chamber 2, when the etching gas is introduced into the reaction chamber 2, plasma is generated in the upper part of the reaction chamber 2, and the sample in the reaction chamber 2 is generated by the plasma. The sample 4 (for example, a silicon wafer on which a photoresist mask patterned by a photolithography method is formed on the upper surface) placed on the stage 6 is etched. On the other hand, when the deposition gas is introduced into the reaction chamber 2 in the deposition step in which the deposition gas is introduced into the reaction chamber 2, the side wall of the etched groove 25 with respect to the sample 4 is protected. In this manner, as shown in FIG. 2, by performing the etching step and the deposition step alternately a predetermined number of times at predetermined time intervals, the anisotropic groove portion is formed on the sample 4 as shown in FIG. 25 can be formed.

  Next, a process for forming a groove having a taper will be described. 4A and 4B show the structure of the groove, FIG. 4A shows the structure of the groove whose side has a forward taper, FIG. 4B shows the structure of the groove whose side has a reverse taper, and FIG. It is a time chart of an etching step and a deposition step when forming so as to have a forward taper.

  First, by alternately switching between an etching step for introducing an etching gas and a deposition step for introducing a deposition gas via the valve element 17, an etching gas and a deposition gas are provided in the reaction chamber 2 in a predetermined manner. Are alternately introduced and exhausted in unit time.

  At this time, in this embodiment, when one of the etching gas and the deposition gas is introduced into the reaction chamber 2, a predetermined amount of the other gas is added and introduced into the reaction chamber 2.

  Specifically, when the groove 25 is formed so that the side wall 25a has a forward taper, as shown in FIG. 5, in the etching step, it is specified to obtain a predetermined taper angle θ together with the etching gas. A small amount of deposition gas is added and introduced into the reaction chamber 2. In the deposition step after the etching step, only the deposition gas is introduced into the reaction chamber 2. Then, after the etching step, the process of performing the deposition step is one process, and the process is repeated a predetermined number of times, whereby the groove 25 having a forward taper can be formed on the side surface 25a.

  On the other hand, when the groove 25 is formed so that the side wall 25a has a reverse taper, in the deposition step, an etching gas of a specified amount is added together with the deposition gas to obtain a predetermined taper angle θ. Introduce into the reaction chamber. In the etching step after the deposition step, only the etching gas is introduced into the reaction chamber.

  Here, etching of the resist patterning wafer having various opening patterns that occupy about 10% of the substrate area is performed by the method described above, and the taper angle measured in the opening pattern and the deposition gas with respect to the etching gas. The relationship with the introduction amount will be described with reference to FIG. In addition, the opening pattern performed in this embodiment is a wiring pattern in which linear groove portions having a predetermined width (15 μm) are formed at equal intervals, and a square pattern in which a square groove portion of 200 μm is formed in the center. is there.

FIG. 6 is a diagram showing the relationship between the taper angle and the amount of deposition gas introduced into the etching gas when a forward taper is obtained. The measurement in Figure 6, introduces SF ₆ as an etching gas is introduced in the range of 100~300sccm (standard cc / min), the C ₄ F ₈ as the deposition gas in the range of 50-200, Measurement was performed by applying power to the lower electrode in the range of 10 to 100 W and applying power to the coil electrode in the range of 500 to 2000 W.

  Thus, in the present embodiment, in the etching step, the taper angle of the side wall 25a formed by introducing the deposition gas in the range of more than 0% and 5% or less with respect to the introduced amount of the etching gas, The quality status was verified.

  As a result, as shown in FIG. 6, in the etching step, the deposition gas is about 88 degrees by adding about 1% of the introduced amount of the etching gas, and similarly about 87 degrees by adding about 2% of the deposition gas. Similarly, it was verified that a taper angle of 86 degrees was formed by adding about 3% of deposition gas. Thus, it was verified that a lower taper angle (which narrows toward the bottom of the groove 25) can be obtained with an increase in the amount of deposition gas introduced into the etching step.

  Further, it was verified that when the introduction amount of the deposition gas exceeds 5% with respect to the introduction amount of the etching gas, the bottom surface of the groove portion 25 becomes rough and the quality is deteriorated.

  In general, in etching of a pattern with a large opening area, the etchant tends to flow into a pattern with a large opening size (microloading effect). Therefore, a pattern with a large opening size tends to be inversely tapered. Although there is a tendency (FIG. 6), it was verified that a forward tapered groove can be formed even in an opening pattern having a large area.

  Thus, in order to form a forward taper in which a predetermined taper angle is formed on the side surface 25a without lowering the etching rate and causing a deterioration in quality, the deposition with respect to the introduction amount of the etching gas is performed in the etching step. It was verified that the deposition gas was added to the etching gas by controlling the gas introduction amount in the range of more than 0% and less than 5%. Moreover, it has been verified that the taper angle θ obtained at that time is defined in the range of 85 degrees to less than 90 degrees.

It is a block diagram of the dry etching apparatus of this application. 5 is a time chart of an etching step and a deposition step when forming a groove on a sample. It is a structural diagram of a groove part. FIG. 4A shows a structure of the groove portion, and FIG. 4B is a structure diagram of the groove portion whose side surface has a forward taper. FIG. 4B is a structure diagram of the groove portion whose side surface has a reverse taper. It is a time chart of an etching step and a deposition step when forming so that the side wall of a groove part may become a forward taper. It is a figure which shows the relationship between the taper angle in the case of obtaining a forward taper, and the introduction amount of the deposition gas with respect to etching gas.

Explanation of symbols

2 Reaction chamber 4 Sample 16 Gas flow controller 25 Groove

Claims (6)

In a dry etching method in which an etching gas and a deposition gas are alternately introduced into a reaction chamber, plasma is generated, and a groove is formed on the workpiece placed in the reaction chamber by the plasma.
When the etching gas or deposition gas is introduced into the reaction chamber, the other gas is added to the one gas, and both gases are introduced into the reaction chamber.   2. The dry etching method according to claim 1, wherein an amount of the other gas introduced is in a range of greater than 0% and 5% or less with respect to the gas to be introduced.   3. The dry etching method according to claim 1, wherein a dry etching is performed by adding a deposition gas together with the etching gas during the etching with the etching gas.   An angle of a side surface with respect to a surface of the workpiece of a groove formed in the workpiece by adding a deposition gas to the etching gas is defined within a range of 85 degrees to less than 90 degrees. Item 4. The dry etching method according to Item 3.   3. The dry etching method according to claim 1, wherein an etching gas is added together with the deposition gas after the etching with the etching gas. In a dry etching apparatus in which etching gas and deposition gas are alternately introduced into a reaction chamber, plasma is generated, and a groove is formed on the workpiece placed in the reaction chamber by the plasma.
When the etching gas or the deposition gas is introduced into the reaction chamber, gas introduction means is provided for adding the other gas to the one gas and introducing both gases into the reaction chamber. A dry etching apparatus.

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