JP6994381B2 - Etching method - Google Patents

Description

The present invention relates to a semiconductor wafer, a liquid crystal display substrate, a plasma display substrate, an organic EL substrate, a FED (Field Emission Display) substrate, an optical display substrate, an organic EL substrate, a photomagnetic disk substrate, and a photomask substrate. , A technique for etching a substrate for a solar cell or the like (hereinafter, simply referred to as a substrate).

In the manufacturing process of semiconductor devices, various silicon oxide films having different forming methods are used. The silicon oxide film is used, for example, in a gate forming step, an interlayer insulating film forming step, an element separation step, or the like.

In the gate forming step, a general thermal oxide film is used for the gate oxide film, and a silicon oxide film formed by a chemical vapor deposition method (hereinafter referred to as a CVD method (Chemical Vapor Deposition)) is used for the sidewall. In the interlayer insulating film process, a CVD film typified by a BSG (Boron Si1icon Glass) film is used. Further, in the element separation step, a thermal oxide film is used as the pad oxide film, and a silicon oxide film formed by the CVD method is used in the element separation region. Further, in recent years, silicon formed by an atomic layer deposition method (hereinafter referred to as ALD method (Atomic Layer Deposition)), which is an atomic layer deposition method capable of forming a film in atomic layer units for miniaturization of semiconductor devices. The oxide film may be used in place of the silicon oxide film described above.

In the process of manufacturing a semiconductor device, it is necessary to process various silicon oxide films having different forming methods by etching in order to manufacture the semiconductor device. Due to the miniaturization of semiconductor devices, there is a problem that the pattern is collapsed by the conventional etching with a chemical solution. Therefore, gas phase etching under reduced pressure is being adopted these days.

When various silicon oxide films are processed by etching, if a silicon oxide film other than the silicon oxide film to be etched is etched, the processing accuracy of the semiconductor device deteriorates. Therefore, a technique for selectively etching only the silicon oxide film to be etched is desired.

For example, Patent Document 1 discloses a technique for selectively etching a silicon oxide film formed by the ALD method with respect to another silicon oxide film such as a thermal oxide film. Specifically, it is said that the silicon oxide film formed by the ALD method can be selectively etched by using HF gas or a mixture of HF gas and _F2 gas and alcohol or water vapor.

Japanese Unexamined Patent Publication No. 2016-62947

However, in the process of manufacturing a semiconductor device, as an oxide film other than the thermal oxide film, not only the ALD oxide film formed by the ALD method but also other oxide films such as BSG film exist. Patent Document 1 discloses selective etching of the ALD oxide film, but does not disclose any selective etching of the oxide film other than the ALD oxide film with respect to the ALD oxide film.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for etching a CVD oxide film with a high selectivity with respect to an ALD oxide film in a manufacturing process of a semiconductor device. ..

In order to solve the above problems, the first aspect is an etching method for etching an oxide film formed on a substrate, which is (a) a CVD oxide film by a CVD (Chemical Vapor Deposition) method, and an ALD (Atomic Layer Deposition). A step of preparing a substrate on which an ALD oxide film is formed by the method), and (b) a step of adjusting the temperature of the substrate prepared by the step (a) to a first temperature higher than 0 ° C and lower than 100 ° C. (C) The step includes a step of supplying hydrogen fluoride gas and steam to the surface of the substrate whose temperature has been adjusted to the first temperature by the step (b) to selectively etch the CVD oxide film.

The second aspect is the etching method of the first aspect, and the first temperature in the step (b) is 0 ° C. or higher and 50 ° C. or lower.

The third aspect is the etching method of the second aspect, and the first temperature in the step (b) is 25 ° C. or higher and 50 ° C. or lower.

The fourth aspect is an etching method according to any one of the first to third aspects, and further includes (d) in the step (c), a step of reducing the pressure around the substrate to 5 Torr or more and 30 Torr or less. ..

The fifth aspect is an etching method according to any one of the first to third aspects, and further includes (e) in the step (c), a step of reducing the pressure around the substrate to 500 Torr or more and 700 Torr or less. ..

A sixth aspect is the etching method according to any one of the first to fifth aspects, wherein (f) the substrate prepared by the step (a) is heated to a second temperature of 100 ° C. or higher and 300 ° C. or lower. The step of adjusting and (g) the surface of the substrate whose temperature has been adjusted to the second temperature by the step (f) is supplied with hydrogen fluoride gas and water vapor to selectively etch the ALD oxide film. Further includes the steps to be performed.

The seventh aspect is the etching method of the sixth aspect, in which the second temperature in the step (f) is 100 ° C. or higher and 170 ° C. or lower.

The eighth aspect is the etching method according to any one of the first to seventh aspects, and the CVD oxide film is a BSG (Boron Silicon Glass) film.

A ninth aspect is the etching method according to any one of the first to eighth aspects, in which a thermal oxide film is formed on the substrate prepared in the step (a).

According to the etching method of the first aspect, the substrate on which the ALD oxide film and the CVD oxide film are formed is brought into contact with hydrogen fluoride gas and water vapor at a first temperature higher than 0 ° C and lower than 100 ° C, whereby the ALD oxide film is formed. It is possible to etch the CVD oxide film while suppressing the etching of. Therefore, the CVD oxide film can be etched with a high selectivity with respect to the ALD oxide film.

According to the etching method of the second aspect, the substrate is temperature-controlled to the first temperature of 0 to 50 ° C. during the etching process, so that the CVD oxide film can be etched with a higher selection ratio.

According to the etching method of the third aspect, the etching of the CVD oxide film can be promoted by adjusting the temperature of the substrate to the first temperature of 25 to 50 ° C. during the etching process.

According to the etching method of the fourth aspect, the atmosphere around the substrate can be exhausted by setting the pressure around the substrate to 5 Torr or more and 30 Torr or less. Therefore, selective etching of the CVD oxide film with hydrogen fluoride gas and steam can be performed. Can be promoted.

According to the etching method of the fifth aspect, the etching of the CVD oxide film can be promoted by setting the pressure around the substrate to 500 to 700 Torr. As a result, even a CVD oxide film formed to be relatively thick can be effectively etched.

According to the etching method of the sixth aspect, by etching the substrate at a second temperature of 100 ° C. or higher and 300 ° C. or lower, the ALD oxide film can be etched while suppressing the etching of the CVD oxide film. Therefore, the ALD oxide film can be etched with a high selectivity with respect to the CVD oxide film.

According to the etching method of the seventh aspect, the ALD oxide film can be selectively etched by setting the temperature to 100 ° C. or higher and 170 ° C. or lower.

According to the etching method of the eighth aspect, the BSG oxide film can be etched with a high selectivity with respect to the ALD oxide film.

According to the etching method of the ninth aspect, the substrate on which the CVD oxide film, the ALD oxide film and the thermal oxide film are formed is brought into contact with hydrogen fluoride gas and steam at a first temperature higher than 0 ° C and lower than 100 ° C. , The CVD oxide film can be etched while suppressing the etching of the ALD oxide film and the thermal oxide film. Therefore, the CVD oxide film can be etched with a high selectivity with respect to the ALD oxide film and the thermal oxide film.

It is a side view which shows the schematic structure of the etching apparatus 1 of embodiment. It is a figure which shows the flow of the substrate processing (etching processing) in the etching apparatus 1. It is a figure which shows the etching amount with respect to the substrate temperature of a thermal oxide film, CVD oxide film, and ALD oxide film. It is a figure which shows the etching amount with respect to the substrate temperature of a thermal oxide film, CVD oxide film, and ALD oxide film.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the components described in this embodiment are merely examples, and the scope of the present invention is not limited to them. In the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary for easy understanding.

<1. Embodiment>
FIG. 1 is a side view showing a schematic configuration of the etching apparatus 1 of the embodiment. The etching device 1 is a single-wafer etching device that processes a substrate W such as a semiconductor wafer one by one. The etching device 1 may be applied to a part of a device for manufacturing a semiconductor device.

The etching apparatus 1 includes a processing chamber 2 and a control unit 3. The processing chamber 2 is a processing unit that performs predetermined processing on the substrate W. The control unit 3 controls the operation of elements provided in the etching apparatus, such as opening and closing a valve.

The processing chamber 2 is formed in a cylindrical shape that can accommodate the substrate W and process it. In the processing chamber 2, a substrate holder 4, a heating mechanism 5, a gas dispersion plate 6, an exhaust pipe 7, a vacuum pump 8, an APC (Auto Pressure Controller) valve 9, a pressure sensor 10, a gas supply pipe 11, a vaporizer 12, A water vapor flow rate controller 13, an HF gas flow rate controller 14, a nitrogen gas flow rate controller 15, and open / close valves 16 to 18 are provided.

The substrate holder 4 holds the substrate W in a substantially horizontal posture in the processing chamber 2. The "horizontal posture" means a state in which the substrate W is parallel to the horizontal plane (XY plane). The substrate W is carried into the processing chamber 2 from the outside by a transport system (not shown) and installed in the substrate holder 4.

The heating mechanism 5 is built in the substrate holder 4. The substrate W held in the substrate holder 4 is heated to a predetermined temperature by the heating mechanism 5. The heating mechanism 5 is, for example, a resistance heating type electric heater. The heating mechanism 5 may include, for example, a lamp instead of the electric heater. By irradiating the substrate W with infrared rays from the lamp, the temperature of the substrate W may be adjusted to a predetermined temperature.

The gas dispersion plate 6 is arranged at a position above the substrate holder 4 in the processing chamber 2. The gas dispersion plate 6 is formed in a plate shape that spreads horizontally in the processing chamber 2. In the gas dispersion plate 6, a plurality of openings 6H penetrating in the thickness direction are formed so as to be dispersed in the horizontal direction.

The exhaust pipe 7 is connected to the bottom of the processing chamber 2 in a state of communicating with the inside of the processing chamber 2. The vacuum pump 8 is connected to the exhaust pipe 7. The vacuum pump 8 decompresses the inside of the processing chamber 2 by sucking the air in the processing chamber 2 through the exhaust pipe 7.

The APC valve 9 is interposed in the exhaust pipe 7. The APC valve 9 adjusts the pressure in the processing chamber 2 by adjusting the opening degree in the exhaust pipe 7.

The pressure sensor 10 is connected to the processing chamber 2 and detects the degree of vacuum in the processing chamber 2. The control unit 3 controls the APC valve 9 to adjust the pressure in the processing chamber 2 so that the degree of vacuum detected by the pressure sensor 10 becomes a desired degree of vacuum.

After the substrate W is held in the substrate holder 4, the vacuum pump 8 operates to start evacuation in the processing chamber 2. In the present embodiment, the means for reducing the pressure in the processing chamber 2 is described by the vacuum pump 8, but the present invention is not limited to this, and for example, the exhaust gas from the factory utility can be used.

The gas supply pipe 11 is connected to the upper part of the processing chamber 2 in a communication state with the inside of the processing chamber 2. The vaporizer 12 stores water for producing water vapor. The steam flow controller 13 supplies the steam generated by the vaporizer 12 into the processing chamber 2. The HF gas flow rate controller 14 controls the flow rate of the HF gas supplied into the processing chamber 2.

When the on-off valve 16 is opened, the water vapor vaporized by the vaporizer 12 is supplied from the gas supply pipe 11 into the processing chamber 2. By supplying nitrogen gas to the vaporizer 12 from a nitrogen gas supply pipe (not shown) as a carrier gas to the vaporizer 12, water vapor vaporized in the vaporizer 12 is generated. The supply flow rate of the steam is adjusted by the steam flow controller 13.

When the on-off valve 17 is opened, the HF gas is supplied into the processing chamber 2. The supply flow rate of HF gas is adjusted by the HF gas flow rate controller 14. The supply of water vapor and HF gas is performed, for example, at the same time.

When the on-off valve 18 is opened, nitrogen gas is supplied into the processing chamber 2. The supply flow rate of nitrogen gas is adjusted by the nitrogen gas flow rate controller 15. Nitrogen gas is supplied into the treatment chamber 2 for pressure adjustment in the treatment chamber 2 or for purging in the treatment chamber 2 after the etching treatment under reduced pressure.

The control unit 3 controls a heating mechanism 5, a vacuum pump 8, an APC valve 9, a pressure sensor 10, a water vapor flow rate controller 13, an HF gas flow rate controller 14, a nitrogen gas flow rate controller 15, and open / close valves 16-18.

The water vapor and the HF gas supplied into the processing chamber 2 via the gas supply pipe 11 communicated with and connected to the upper portion of the processing chamber 2 pass through the gas dispersion plate 6 and reach the substrate W.

The mixed gas of water vapor and HF gas supplied to the upper side of the gas dispersion plate 6 in the processing chamber 2 moves to the lower side of the gas dispersion plate 6 by passing through a plurality of openings 6H provided in the gas dispersion plate 6. Then, it is uniformly supplied on the substrate W. The inner diameter of the opening 6H is, for example, 0.1 mm. The distance between the adjacent openings 6H and 6H is, for example, 5 mm. The inner diameter and spacing of the openings 6H are not limited to these. Further, in the example shown in FIG. 1, only one gas dispersion plate 6 is installed in the processing chamber 2, but a plurality of gas dispersion plates 6 may be installed so as to overlap each other in multiple stages.

The supply flow rate of the HF gas supplied for etching the silicon oxide film formed on the substrate W is, for example, 50 to 300 cc / min, preferably 30 to 170 cc / min. The supply flow rate of water vapor mixed with the HF gas is, for example, 50 to 300 cc / min, preferably 60 to 300 cc / min.

The control unit 3 adjusts the opening degree of the APC valve 9 so that the pressure value of the pressure sensor 10 indicates a predetermined pressure value according to the supply flow rate of the mixed gas of steam and HF gas. As a result, the pressure in the processing chamber 2 is appropriately adjusted. During the processing of the substrate W, the pressure in the processing chamber 2 is maintained at, for example, 5 to 700 Torr.

<Flow of board processing>
FIG. 2 is a diagram showing a flow of substrate processing (etching processing) in the etching apparatus 1 of the embodiment. The etching process described below may be applied as part of the manufacturing process of a semiconductor device.

First, the substrate W to be etched is prepared (step S1: preparation step). This substrate W is formed with a CVD oxide film by the CVD method, an ALD oxide film by the ALD method, and a thermal oxide film.

In the CVD method, for example, a silicon substrate is exposed to a raw material gas containing a component of a thin film of interest, and heat or plasma is used to cause a chemical reaction on the silicon substrate. By this chemical reaction, a target thin film is formed on a silicon substrate. When a BSG film is formed by the CVD method, boron (B) is mixed in the raw material gas.

Further, in the ALD method, first, the substrate W placed in the chamber is exposed to the precursor A. Subsequently, after the precursor A in the chamber is removed by purging, the substrate is exposed to another precursor B (eg ozone). Then, the precursor B in the chamber is removed by purging again. By repeating these processes, a film at the level of one molecule is formed layer by layer. Specifically, when the silicon oxide film is the target of film formation as the ALD oxide film, aminosilane is used as the raw material gas (precursor A), and the aluminum oxide (Al ₂ O ₃ ) film is the target of film formation. Trimethylaluminum is used as a raw material gas.

Further, the thermal oxide film is formed by a method of oxidizing from the surface of the substrate to the inside. Specifically, by exposing the silicon substrate to oxygen or steam in a high-temperature atmosphere, silicon (Si) and oxygen (O ₂ ) are chemically reacted to form a thin film (heat) of silicon dioxide (SiO ₂ ). Oxide film) is formed.

When the substrate W is prepared in step S1, a transport system (not shown) transports the substrate W into the processing chamber 2 and mounts the substrate W on the substrate holder 4 (step S2: substrate mounting step).

After the substrate W is placed on the substrate holder 4, the control unit 3 controls the vacuum pump 8 to reduce the pressure in the processing chamber 2 to a high vacuum state (for example, ^10-6 Torr level) (step S3). : Processing chamber decompression process). The degree of depressurization is appropriately determined depending on the capacity of the vacuum pump 8 used and the allowable depressurization time. By reducing the pressure in the processing chamber 2 as much as possible, the atmosphere in the processing chamber 2 can be exhausted as much as possible, and thus the cleanliness in the processing chamber 2 can be improved.

Once the inside of the processing chamber 2 is depressurized to a high vacuum state, the control unit 3 supplies nitrogen gas into the processing chamber 2 by opening the on-off valve 18. Further, the control unit 3 controls the nitrogen gas flow rate controller 15 based on the pressure value indicated by the pressure sensor 10 to adjust the supply flow rate of nitrogen gas and adjust the opening degree of the APC valve 9. By these adjustments, the control unit 3 adjusts the pressure in the processing chamber 2 to a predetermined pressure of 5 to 700 Torr (step S4: first pressure adjusting step). Further, the control unit 3 controls the heating mechanism 5 to adjust the temperature of the substrate holder 4 to a predetermined temperature (step S5: first temperature adjustment step). For example, the control unit 3 may start temperature control (heating) of the substrate holder 4 substantially at the same time as starting the depressurization in the processing chamber 2 in step S2.

Here, the CVD oxide film is selectively etched from the thermal oxide film, the CVD oxide film, and the ALD oxide film. Therefore, in steps S4 and S5, the control unit 3 sets the pressure of the processing chamber 2 and the temperature of the substrate W to the first pressure (for example, 10 Torr) suitable for selective etching of the CVD oxide film and the first in the low temperature region. Adjust to a temperature (for example, a temperature of 25 ° C. or higher and 50 ° C. or lower).

When the temperature of the substrate W reaches the first temperature after a predetermined time elapses after the start of temperature control in step S5, the control unit 3 opens the on-off valves 16 and 17 to process the HF gas and steam in the processing chamber 2. Supply inside. At this time, the control unit 3 controls the steam flow rate controller 13 and the HF gas flow rate controller 14 to adjust the HF gas and steam to a predetermined flow rate.

The mixed gas of water vapor and HF gas supplied into the processing chamber 2 passes through the plurality of openings 6H formed in the gas dispersion plate 6 and comes into contact with the entire surface of the substrate W substantially uniformly. At this time, since the substrate W is temperature-controlled to a predetermined temperature in the low temperature region, the CVD oxide film to be etched is selectively etched by the steam and the HF gas (step S6: selective etching step). When a predetermined time has elapsed after the start of supply of HF gas and steam, the control unit 3 stops the supply of HF gas and steam by closing the on-off valves 16 and 17.

In the manufacturing process of semiconductor devices, the thickness of the silicon oxide film used for the interlayer insulating film such as the BSG film is thicker (several tens of nm to several nm) than the film thickness of the general ALD oxide film (several nm). It may be 100 nm). When it is desired to etch a silicon oxide film having such a film thickness at a high etching rate, the pressure in the processing chamber 2 in step S6 (selective etching step) may be set to 500 to 700 Torr.

Subsequently, the control unit 3 supplies nitrogen gas into the processing chamber 2 by opening the on-off valve 18. Further, the control unit 3 controls the nitrogen gas flow rate controller 15 based on the pressure value indicated by the pressure sensor 10 to adjust the supply flow rate of nitrogen gas and adjust the opening degree of the APC valve 9. By these adjustments, the control unit 3 adjusts the pressure in the processing chamber 2 to a predetermined pressure of 5 to 700 Torr (step S7: second pressure adjusting step). Further, the control unit 3 controls the heating mechanism 5 to adjust the temperature of the substrate holder 4 to a predetermined temperature (step S8: second temperature adjustment step).

Here, the ALD oxide film is selectively etched from the thermal oxide film, the CVD oxide film, and the ALD oxide film. Therefore, in steps S7 and S8, the control unit 3 sets the pressure of the processing chamber 2 and the temperature of the substrate W to a second pressure (for example, 10 Torr) suitable for selective etching of the ALD oxide film and a second temperature region. Adjust to a temperature (for example, a predetermined temperature of 100 ° C. or higher and 170 ° C. or lower).

After a predetermined time has elapsed after the start of pressure adjustment in step S7 and the start of temperature control in step S8, the control unit 3 supplies HF gas and steam into the processing chamber 2 by opening the on-off valves 16 and 17. At this time, the control unit 3 controls the steam flow rate controllers 13 and 14 to adjust the HF gas and steam to a predetermined flow rate. The mixed gas of water vapor and HF gas supplied into the processing chamber 2 passes through the plurality of openings 6H formed in the gas dispersion plate 6 and comes into contact with the entire surface of the substrate W substantially uniformly. At this time, since the substrate W is temperature-controlled to a predetermined temperature in the low temperature region, the ALD oxide film to be etched is selectively etched by the water vapor and the HF gas (step S9: selective etching step). When a predetermined time has elapsed after the start of supply of HF gas and steam, the control unit 3 stops the supply of HF gas and steam by closing the on-off valves 16 and 17.

When a predetermined time has elapsed from the stop of supply of steam and HF gas, the control unit 3 supplies nitrogen gas into the processing chamber 2 by opening the on-off valve 18 (step S10: purge step). At this time, the control unit 3 controls the nitrogen gas flow rate controller 15 to adjust the supply flow rate of the nitrogen gas. In this way, the control unit 3 purges the inside of the processing chamber 2 which was in the depressurized state with nitrogen gas to return the inside of the processing chamber 2 to the atmospheric pressure so that the substrate W can be carried out. The board W that can be carried out is appropriately carried out from the board holder 4 by a transport system (not shown).

In the above description, the substrate W is first temperature-controlled to the first temperature in the low temperature region to selectively etch the CVD oxide film, and then the substrate W is temperature-controlled to the second temperature in the high temperature region to select the ALD oxide film. Etching. However, first, the substrate W is temperature-controlled to the second temperature in the high temperature region to selectively etch the ALD oxide film, and then the substrate W is temperature-controlled to the first temperature in the low temperature region to selectively etch the CVD oxide film. It may be etched.

Further, after the step of selectively etching the CVD oxide film (step S6) is completed by the control unit 3, the substrate W is subjected to before the step of selectively etching the ALD oxide film (step S9). Predetermined processing may be performed. For example, after step S6, the substrate W may be taken out from the processing chamber 2 by purging, and another predetermined processing may be performed on the substrate W by a predetermined processing apparatus. After the predetermined processing is completed, the substrate W may be carried into the processing chamber 2 again, and the control unit 3 may execute steps S7 and subsequent steps.

<Explanation of selective etching>
Next, selective etching for selectively etching each of the CVD oxide film and the ALD oxide film will be described.

3 and 4 are diagrams showing the etching amounts of each of the thermal oxide film, the CVD oxide film, and the ALD oxide film formed on the substrate W with respect to the substrate temperature. Here, the CVD oxide film is a BSG (Boron Silicon Glass) film. The ALD oxide film is an ALD silicon oxide film.

FIG. 3 shows each etching amount when the substrate W is etched for 30 seconds while the pressure in the processing chamber 2 is maintained at 10 Torr, the supply flow rate of HF gas is 150 cc / min, and the supply flow rate of steam is 150 cc / min. It is a figure which shows. Further, FIG. 4 shows each case where the substrate W is etched for 30 seconds while the pressure in the processing chamber 2 is maintained at 600 Torr, the supply flow rate of HF gas is 60 cc / min, and the supply flow rate of steam is 150 cc / min. It is a figure which shows the etching amount.

(1) Selective etching of CVD oxide film As shown in FIGS. 3 and 4, the temperature of the substrate W is set to a low temperature region (specifically, greater than 0 ° C. and less than 100 ° C., preferably greater than 0 ° C. and 75 ° C. or lower). More preferably, the CVD oxide film (BSG film) is selectively etched with respect to the thermal oxide film and the ALD oxide film by adjusting the temperature to a predetermined temperature (first temperature) of 25 ° C. or higher and 50 ° C. or lower. It is possible to do. However, the optimum temperature for selective etching of the CVD oxide film is considered to depend on the structure of the semiconductor device and the like.

Further, as described above, by setting the pressure in the processing chamber 2 to, for example, 500 Torr or more and 700 Torr or less, a CVD oxide film having a wall thickness of several tens of nm to several hundreds of nm can be effectively etched. Specifically, as shown in FIG. 4, when the pressure in the processing chamber 2 is 600 Torr, the etching amount of the BSG film is significantly larger than that of 10 Torr shown in FIG. 3 (specifically, about 350 nm). ). Further, even when the pressure is set to 600 Torr, the etching of the BSG film hardly proceeds when the temperature of the substrate W is 100 ° C. or higher.

On the other hand, when increasing the selectivity of the BSG film, the pressure in the treatment chamber 2 may be, for example, 5 Torr or more and 30 Torr or less. Specifically, when the pressure is 10 Torr as shown in FIG. 3, the etching amount of the BSG film is 10 nm or less when the temperature of the substrate W is less than 100 ° C. By reducing the pressure in this way, although the etching amount is reduced, the BSG film can be etched with a high selectivity with respect to other oxide films (ALD oxide film and thermal oxide film).

It is known that HF _2- ⁽ hydrogen fluoride ion) mainly contributes to the etching of the silicon oxide film. This HF ₂ ^- is produced by the reaction of HF and _H2O . The BSG film has a lower film density than the ALD oxide film and the thermal oxide film, and contains water in the film. Therefore, in the BSG film, the reaction ^by HF _2- is more likely to proceed than in the ALD oxide film and the thermal oxide film, and the water content in the film also contributes to the ionization of HF in the reaction process, so that etching is performed. It is considered to proceed easily. On the other hand, when the temperature is 100 ° C. or higher, the water content in the BSG film is removed to form a strong film. Therefore, it is considered that the etching of the BSG film hardly proceeds at 100 ° C. or higher.

(2) Selective etching of ALD oxide film As shown in FIG. 3, the temperature of the substrate W is kept in a high temperature region (100 ° C. or higher and 300 ° C. or lower, preferably 100 ° C.) while the vacuum degree in the processing chamber 2 is maintained at 10 Torr. By adjusting the temperature to a predetermined temperature (second temperature) of ° C. or higher and 240 ° C. or lower, more preferably 100 ° C. or higher and 170 ° C. or lower, other than CVD oxide film (here, BSG film) or thermal oxide film. The ALD oxide film can be selectively etched with respect to the silicon oxide film of. In particular, when the temperature of the substrate W is 150 ° C., the ALD oxide film can be etched most selectively.

The ALD oxide film is formed by depositing one molecular layer at a time. Therefore, the ALD oxide film has a smaller amount of water in the film than the CVD oxide film such as the BSG film. Further, in the ALD oxide film, the bond between the molecular layers is weaker than that in the CVD oxide film. Therefore, it is considered that the etching of the ALD oxide film proceeds because the bonds between the molecular layers are easily broken by raising the substrate W to a high temperature of 100 ° C. or higher. On the other hand, as described above, the CVD oxide film (BSG film) is less likely to be etched when the substrate temperature is 100 ° C. or higher. Therefore, it is considered that the ALD oxide film can be selectively etched at 100 ° C. or higher.

As described above, for the substrate W on which the CVD oxide film and the ALD oxide film are formed, each oxide film is selected by contacting each oxide film with HF gas and water vapor under the condition of being temperature-controlled to a predetermined temperature. Can be targeted for etching. Further, when manufacturing a semiconductor device using the CVD oxide film and the ALD oxide film, the semiconductor device can be satisfactorily manufactured by applying the etching technique of the present invention.

Although the invention has been described in detail, the above description is exemplary in all aspects and the invention is not limited thereto. It is understood that innumerable variations not illustrated can be assumed without departing from the scope of the present invention. Each configuration described in each of the above-described embodiments and modifications can be appropriately combined or omitted as long as they do not conflict with each other.

1 Etching device 2 Processing room 3 Control unit 4 Board holder 5 Heating mechanism 6 Gas dispersion plate 6H Opening 7 Exhaust piping 8 Vacuum pump 9 APC valve 10 Pressure sensor 11 Gas supply piping 12 Vaporizer 13 Steam flow controller 14 HF gas flow controller 15 Nitrogen gas flow controller 16-18 Open / close valve
W board

Claims (9)

It is an etching method that etches the oxide film formed on the substrate.
(A) A step of preparing a substrate on which a CVD oxide film by a CVD (Chemical Vapor Deposition) method and an ALD oxide film by an ALD (Atomic Layer Deposition) method are formed, and
(B) A step of adjusting the temperature of the substrate prepared by the step (a) to a first temperature higher than 0 ° C. and lower than 100 ° C.
(C) A step of supplying hydrogen fluoride gas and water vapor to the surface of the substrate whose temperature has been adjusted to the first temperature by the step (b) to selectively etch the CVD oxide film.
Etching method, including. The etching method according to claim 1.
The etching method, wherein the first temperature in the step (b) is 0 ° C. or higher and 50 ° C. or lower. The etching method according to claim 2.
The etching method, wherein the first temperature in the step (b) is 25 ° C. or higher and 50 ° C. or lower. The etching method according to any one of claims 1 to 3.
(D) In the step (c), a step of reducing the pressure around the substrate to 5 Torr or more and 30 Torr or less.
Further including etching methods. The etching method according to any one of claims 1 to 3.
(E) In the step (c), a step of reducing the pressure around the substrate to 500 Torr or more and 700 Torr or less.
Further including etching methods. The etching method according to any one of claims 1 to 5.
(F) A step of adjusting the temperature of the substrate prepared by the step (a) to a second temperature of 100 ° C. or higher and 300 ° C. or lower, and
(G) A step of supplying hydrogen fluoride gas and water vapor to the surface of the substrate whose temperature has been adjusted to the second temperature by the step (f) to selectively etch the ALD oxide film.
Further including etching methods. The etching method according to claim 6.
An etching method in which the second temperature in the step (f) is 100 ° C. or higher and 170 ° C. or lower. The etching method according to any one of claims 1 to 7.
An etching method in which the CVD oxide film is a BSG (Boron Silicon Glass) film. The etching method according to any one of claims 1 to 8.
An etching method in which a thermal oxide film is formed on the substrate prepared in the step (a).

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