JP6943012B2 - Liquid treatment method, liquid treatment equipment, and storage medium - Google Patents

Description

The present invention relates to a technique for supplying a processing liquid to a substrate to perform liquid treatment.

In the manufacturing process of a semiconductor device, a convex pattern, which is an element of the semiconductor device, is formed by etching on the surface of a substrate, for example, a silicon wafer (hereinafter referred to as a wafer), and an insulating film is embedded between the convex patterns. As a result, there is an element separation method called the STI (Shallow Trench Isolation) method that insulates adjacent convex patterns from each other.

Since etching residues remain on the surface of the wafer after the convex pattern is formed or an oxide film is formed on the surface of the silicon convex pattern, for example, an acidic chemical solution is supplied to the surface of the wafer. Then, a process of removing these etching residues and the oxide film is performed.

On the other hand, when the wafer is dried after supplying a treatment liquid such as a chemical solution to the surface of the wafer, the above-mentioned convex pattern may collapse.
As a method for removing the rinse solution remaining on the wafer surface while suppressing the occurrence of pattern collapse, for example, Patent Document 1 describes that the surface of a wafer washed with a chemical solution is modified to be hydrophilic and then surfaced on the surface of the wafer. By supplying a treatment agent (corresponding to the "water repellent agent" of the present application) and forming a water-repellent protective film, the surface tension acting on the pattern from the treatment liquid is reduced, and collapse when the treatment liquid is removed. A technique for suppressing the occurrence is described.

However, Patent Document 1 does not disclose any effect on the manufacturing process in the subsequent stage or a technique for reducing the effect of using the surface treatment agent treatment liquid.

JP2012-178606A: Claim 1, paragraphs 0017, 0042,

The present invention has been made under such circumstances, and an object of the present invention is a liquid treatment method and a liquid treatment apparatus capable of performing liquid treatment on a substrate while suppressing the influence of the use of a water repellent agent. , And to provide a storage medium.

The liquid treatment method of the present invention is a liquid treatment method for a substrate.
A chemical solution supply step of forming a convex pattern of silicon and supplying a chemical solution to the surface of a substrate containing at least one layer of silicon oxide and silicon nitride different from the silicon at the tip of the convex pattern.
After the chemical solution supply step, a rinse solution supply step of supplying the rinse solution to the surface of the substrate, and a rinse solution supply step.
After the rinse liquid supply step, a water repellent agent supply step of supplying a water repellent agent that replaces a hydroxyl group on the surface of the substrate with a hydrophobic group to make the surface of the tip of the convex pattern water repellent. , Including
The rinsing liquid supplying step, characterized in that it is performed in suppressing hydroxide suppressed environment an increase in the hydroxyl groups present on the surface of the silicon of the convex pattern.

In the present invention, since the rinsing liquid is supplied to the substrate in a hydroxylation-suppressing environment that suppresses the increase of hydroxyl groups existing on the surface of silicon having a convex pattern, hydrophobic groups substituted with hydroxyl groups remain on the surface of silicon. Can be suppressed.

It is a top view which shows the outline of the substrate processing system provided with the processing unit which concerns on embodiment of this invention. It is a vertical sectional side view which shows the outline of the processing unit. It is a block diagram which shows the supply system of the processing liquid to the processing unit. It is a process drawing which shows an example of the liquid processing using the said processing unit. It is a 1st operation diagram of the processing unit. It is a second operation diagram of the processing unit. It is a schematic diagram which shows the convex pattern before liquid treatment. It is an enlarged schematic diagram of the said convex pattern after rinsing treatment of a conventional method. It is a schematic diagram which shows the convex pattern after treating the wafer which was rinsed by the conventional method with a water repellent agent. It is an enlarged schematic diagram of the convex pattern after rinsing treatment in a hydroxylation-suppressing environment. It is a schematic diagram which shows the convex pattern after the wafer which was rinse-treated in the hydroxylation-suppressing environment was treated with the water-repellent agent. It is a schematic diagram which shows the convex pattern at the time of manufacturing the NAND type flash memory. It is a process drawing which shows another example of liquid treatment. It is a vertical sectional side view of an ultraviolet irradiation unit and a heating unit. It is a 1st explanatory view which shows the result of the ultraviolet ray treatment and the heat treatment.

FIG. 1 is a diagram showing a schematic configuration of a substrate processing system according to the present embodiment. In the following, in order to clarify the positional relationship, the X-axis, the Y-axis, and the Z-axis that are orthogonal to each other are defined, and the positive direction of the Z-axis is defined as the vertically upward direction.

As shown in FIG. 1, the substrate processing system 1 includes a loading / unloading station 2 and a processing station 3. The loading / unloading station 2 and the processing station 3 are provided adjacent to each other.

The loading / unloading station 2 includes a carrier mounting section 11 and a transport section 12. A plurality of substrates, and in the present embodiment, a plurality of carriers C for accommodating a semiconductor wafer (hereinafter referred to as wafer W) in a horizontal state are mounted on the carrier mounting portion 11.

The transport section 12 is provided adjacent to the carrier mounting section 11, and includes a substrate transport device 13 and a delivery section 14 inside. The substrate transfer device 13 includes a wafer holding mechanism for holding the wafer W. Further, the substrate transfer device 13 can move in the horizontal direction and the vertical direction and can rotate around the vertical axis, and transfers the wafer W between the carrier C and the delivery portion 14 by using the wafer holding mechanism. conduct.

The processing station 3 is provided adjacent to the transport unit 12. The processing station 3 includes a transport unit 15 and a plurality of processing units 16. The plurality of processing units 16 are provided side by side on both sides of the transport unit 15.

The transport unit 15 includes a substrate transport device 17 inside. The substrate transfer device 17 includes a wafer holding mechanism for holding the wafer W. Further, the substrate transfer device 17 can move in the horizontal direction and the vertical direction and swivel around the vertical axis, and transfers the wafer W between the delivery unit 14 and the processing unit 16 by using the wafer holding mechanism. I do.

The processing unit 16 performs predetermined substrate processing on the wafer W transported by the substrate transport device 17.

Further, the substrate processing system 1 includes a control device 4. The control device 4 is, for example, a computer, and includes a control unit 18 and a storage unit 19. The storage unit 19 stores programs that control various processes executed in the substrate processing system 1. The control unit 18 controls the operation of the substrate processing system 1 by reading and executing the program stored in the storage unit 19.

The program may be recorded on a storage medium readable by a computer, and may be installed from the storage medium in the storage unit 19 of the control device 4. Examples of storage media that can be read by a computer include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnet optical disk (MO), and a memory card.

In the substrate processing system 1 configured as described above, first, the substrate transfer device 13 of the loading / unloading station 2 takes out the wafer W from the carrier C mounted on the carrier mounting portion 11, and receives the taken out wafer W. Placed on Watanabe 14. The wafer W placed on the delivery section 14 is taken out from the delivery section 14 by the substrate transfer device 17 of the processing station 3 and carried into the processing unit 16.

The wafer W carried into the processing unit 16 is processed by the processing unit 16, then carried out from the processing unit 16 by the substrate transfer device 17, and placed on the delivery unit 14. Then, the processed wafer W mounted on the delivery section 14 is returned to the carrier C of the carrier mounting section 11 by the substrate transfer device 13.

As shown in FIG. 2, the processing unit 16 includes a chamber 20, a substrate holding mechanism 30, a processing fluid supply unit 40, and a recovery cup 50.

The chamber 20 houses the substrate holding mechanism 30, the processing fluid supply unit 40, and the recovery cup 50. An FFU (Fan Filter Unit) 21 is provided on the ceiling of the chamber 20. The FFU 21 forms a downflow in the chamber 20.

The substrate holding mechanism 30 includes a holding portion 31, a strut portion 32, and a driving portion 33. The holding unit 31 holds the wafer W horizontally. The strut portion 32 is a member extending in the vertical direction, the base end portion is rotatably supported by the drive portion 33, and the holding portion 31 is horizontally supported at the tip portion. The drive unit 33 rotates the strut unit 32 around a vertical axis. The substrate holding mechanism 30 rotates the holding portion 31 supported by the supporting portion 32 by rotating the supporting portion 32 by using the driving unit 33, thereby rotating the wafer W held by the holding portion 31. ..

The processing fluid supply unit 40 supplies the processing fluid to the wafer W. The processing fluid supply unit 40 is connected to the processing fluid supply source 70.

The recovery cup 50 is arranged so as to surround the holding portion 31, and collects the processing liquid scattered from the wafer W by the rotation of the holding portion 31. A drainage port 51 is formed at the bottom of the recovery cup 50, and the treatment liquid collected by the recovery cup 50 is discharged from the drainage port 51 to the outside of the treatment unit 16. Further, at the bottom of the recovery cup 50, an exhaust port 52 for discharging the gas supplied from the FFU 21 to the outside of the processing unit 16 is formed.

The processing unit 16 provided in the substrate processing system 1 described above corresponds to a liquid processing apparatus for executing the liquid processing method according to the embodiment. Hereinafter, the configuration of the processing unit 16 will be described in more detail with reference to FIG.
In the processing unit 16 of this example, the processing fluid supply source 70 connected to the processing fluid supply unit 40 is a DHF supply unit 71 that supplies a DHF (diluted hydrogen Fluoride) which is an acidic chemical solution, and an IPA. IPA supply unit 72 that supplies (Isopropyl Alcohol), water repellent agent supply unit 73 that supplies water repellent agent, and DIW supply unit that supplies DIW (Deionized Water, pure water) that is a rinse liquid. It is equipped with 74.

From the DHF supply unit 71, DHF for removing the etching residue adhering when forming the convex pattern 8 on the surface of the wafer W and the oxide film formed by the natural oxidation of silicon is supplied. BHF (Buffered Hydrogen Fluoride) may be used in addition to DHF as the acidic chemical solution for removing the etching residue and the oxide film.
The DHF supply unit 71 includes a DHF tank (not shown) and a flow rate adjusting mechanism, and is connected to a nozzle provided in the processing fluid supply unit 40 via an on-off valve V1. The DHF supply unit 71 corresponds to the chemical solution supply unit of this example, and the nozzle to which DHF is supplied from the DHF supply unit 71 corresponds to the chemical solution supply nozzle of this example.

IPA is supplied from the IPA supply unit 72. The IPA can be mixed with both the DIW and the water repellent agent which are difficult to mix with each other, and is supplied as a replacement liquid which replaces the DIW existing on the surface of the wafer W before the water repellent agent is supplied. The IPA is also supplied as a drying liquid that accelerates the drying of the wafer W after being treated with a water repellent agent.
The IPA supply unit 72 includes an IPA tank (not shown) and a flow rate adjusting mechanism, and is connected to a nozzle provided in the processing fluid supply unit 40 via an on-off valve V2.

A water repellent agent for making the surface of the wafer W water repellent is supplied from the water repellent agent supply unit 73. The water repellent is a compound having a silyl group (a functional group in which an alkyl group is bonded to a silicon atom and functions as a hydrophobic group), and a silyl group is introduced (water repellent) on the surface of the convex pattern 8. Then, the surface tension acting when the IPA supplied as the drying liquid is removed from the surface of the wafer W is reduced.
Examples of the water repellent agent include trimethylsilyldimethylamine (TMDMA), hexamethyldisilazane (HMDS), trimethylsilyldiethylamine (TMSDEA), dimethyl (dimethylamino) silane (DMSDMA), and 1,1,3,3-tetramethyldisilane ( TMDS) etc. can be adopted. Further, if necessary, those obtained by diluting these substances with a diluting solvent may be adopted as the water repellent agent.

The water repellent agent supply unit 73 includes a water repellent agent tank (not shown) and a flow rate adjusting mechanism, and is connected to a nozzle provided in the processing fluid supply unit 40 via an on-off valve V3. The nozzle to which the water repellent agent is supplied from the water repellent agent supply unit 73 corresponds to the water repellent agent supply nozzle of this example.

DIW for rinsing the surface of the wafer W is supplied from the DIW supply unit 74. The DIW supply unit 74 includes a DIW tank 741 described later and a flow rate adjusting mechanism (not shown), and is connected to a nozzle provided in the processing fluid supply unit 40 via an on-off valve V4. The nozzle to which DIW is supplied from the DIW supply unit 74 corresponds to the rinse liquid supply nozzle of this example.

Here, in FIGS. 3, 5 and 6, the DHF supply unit 71, the IPA supply unit 72, the water repellent agent supply unit 73, and the DIW supply unit 74 are provided for the common nozzle provided in the processing fluid supply unit 40. An example is shown in which various treatment liquids are supplied from. Instead of this example, a configuration may be adopted in which a plurality of nozzles are provided in the processing fluid supply unit 40 and these processing liquids are supplied from different nozzles.

The processing unit 16 having the configuration described above can perform the rinsing treatment in an environment in which oxygen contained in the DIW supplied to the wafer W and the atmosphere in the chamber 20 at the time of rinsing treatment is reduced. It has a configuration.
Before explaining the configuration, problems that occur when a water repellent agent is supplied after rinsing treatment in an environment where a relatively large amount of oxygen is present will be described with reference to FIGS. 7 to 9. ..

FIG. 7A is a schematic view of the longitudinal side surface of the convex pattern 8 in which the elements are separated by the STI method.
_{To briefly explain the STI method, after forming the SiO 2} (silicon oxide) layer 82 which is an oxide film on the surface of the silicon wafer W, a resist pattern is formed on the surface of the _{SiO 2 layer 82, and RIE (} By Reactive Ion Etching) or the like, for example, a convex pattern 8 structure having a line width of 30 nm or less and an aspect ratio of 10 or more of the silicon pattern 81 is formed. _{After that, the SiO 2} film is embedded in the groove between the adjacent convex patterns 8, and the _{unnecessary SiO 2} film is removed by CMP (Chemical Mechanical Polishing) to separate the elements between the convex patterns 8.

Of the above-mentioned manufacturing steps, the convex pattern 8 after RIE is subjected to a rinsing treatment using DIW after removing the etching residue and the oxide film by supplying DHF, and then making it water repellent. After making the surface of the convex pattern 8 water-repellent with an agent, a liquid treatment for removing the liquid existing on the surface of the wafer W is performed.

FIG. 7B is an enlarged schematic view of the surface of the convex pattern 8 after the treatment by DHF. When the oxide film on the surface of the silicon pattern 81 is removed by DHF, silicon is exposed on the surface of the silicon pattern 81, and the end thereof is in a state of being terminated by a hydrogen atom (H termination). However, a part of the silicon exposed on the surface of the silicon pattern 81 is in a state where the unbonded hands 811 generated when the convex pattern 8 is formed by RIE or when the oxide film is removed by DHF are left. There is.
_{On the other hand, the surface of the SiO 2} layer 82 formed at the tip of the convex pattern 8 is in a state of being terminated by a hydroxyl group (OH termination), and _{the surface of the SiO 2} layer 82 is removed by DHF. However, the surface of the newly exposed SiO ₂ layer 82 is maintained in an OH-terminated state.

DIW is supplied to the convex pattern 8 from which the etching residue and the oxide film have been removed by supplying the DHF, and the rinsing treatment is performed. At this time, when oxygen is contained in the DIW and the oxygen existing in the processing atmosphere in the chamber 20 is taken into the DIW, the unbonded hands 811 on the silicon pattern 81 side and a part of the H-terminated silicon are removed. It is oxidized by DIW containing oxygen and becomes OH-terminated (Fig. 8).

It is known that the water repellent agent introduces a silyl group at a position where a hydroxyl group exists (OH-terminated position) on the surface of the convex pattern 8. Therefore, as shown in the example of FIG. 8, the _{entire surface of the SiO 2} layer 82 is OH-terminated, and the convex pattern 8 in which the OH-terminated regions are scattered on the surface of the silicon pattern 81 is water-repellent. When the agent is supplied, a silyl group is introduced into these regions (FIGS. 9 (a) and 9 (b)).

In FIG. 9A, after the water repellent agent is supplied, the surface whose entire surface is covered with silyl groups is shown by a thick solid line, and the surface where the silyl groups are scattered is shown by a thick broken line.
Further, FIG. 9B schematically shows a state in which the silyl group 80 is introduced on the surface of the silicon pattern 81 or the SiO _{2 layer 82.} As an example of the silyl group, FIG. 9B shows a state in which the trimethylsilyl group is introduced.

In the state after the treatment with DHF, _{the water repellency (contact angle of water) of the SiO 2} layer 82 is about one tenth of that of the silicon pattern 81. On the other hand, in the state after the water repellent agent is supplied, as shown in FIG. 9A, the _{entire surface of the SiO 2} layer 82 is covered with the silyl group, so that _{the water repellency of the SiO 2} layer 82 is significantly increased. do. Further, since the silyl groups are scattered on the surface of the silicon pattern 81, the water repellency of the silicon pattern 81 is slightly increased, but the water repellency is about the same as that _{of the SiO 2 layer 82 after the water repellency.}
When the liquid existing on the surface of the wafer W including the convex pattern 8 in the above state is removed, the surface tension acting on the convex pattern 8 is reduced from the liquid, so that the convex pattern 8 collapses due to the removal of the liquid. Can be suppressed.

On the other hand, as described in the outline description of the STI method, the SiO ₂ film is embedded in the convex pattern 8 after the liquid is removed, and the elements are separated between the adjacent convex patterns 8. At this time, _{the silyl group covering the surface of the SiO 2} layer 82 is considered to be decomposed and removed by the heat treatment performed after that, but the substance caused by the silyl group (hereinafter, also referred to as “residue”). There is a possibility that a part of the above remains between the convex pattern 8 and the SiO _{2 film.}

Among the residues, residues of the surface of the SiO ₂ layer 82 is removed together with the SiO ₂ layer 82 by CMP. However, the residue due to the silyl groups scattered on the surface of the silicon pattern 81 remains in the semiconductor device even after the _{SiO 2 film is embedded.} At this time, the residue may be a factor that deteriorates the electrical characteristics of the semiconductor device.

As a result of studies to solve the above-mentioned problems, the inventor of the present invention removes the liquid from the surface of the wafer W after the liquid treatment while suppressing the occurrence of the collapse of the convex pattern 8. Then, it is not an indispensable requirement to make the entire surface of the convex pattern 8 (silicon pattern 81 and the SiO ₂ layer 82) water repellent, and if the surface of _{the SiO 2 layer 82 provided at the tip is made water repellent,} , It was newly found that a sufficient collapse suppressing effect can be obtained.

At this time, based on the mechanism in which the OH termination is formed on the surface of the silicon pattern 81 described above, if the rinsing treatment is performed under the condition that the surface of the silicon pattern 81 is difficult to be oxidized (OH termination is difficult), the number of hydroxyl groups increases. It is possible to perform a rinsing treatment for removing DHF from the surface of the wafer W while suppressing the pressure.

In this respect, for example, as described in Patent Document 1 (see paragraph 0144), from the viewpoint of suppressing the occurrence of pattern collapse, H _{2 is also applied to the surface of the silicon pattern 81 in which silicon is exposed by the DHF treatment.} it has been considered preferable to oxidize by supplying O ₂ or ozone-containing water.
However, from the viewpoint of suppressing the occurrence of pattern collapse, one of the features of the present invention is that it is sufficient to make the surface of _{the SiO 2 layer 82 formed at the tip of the convex pattern 8 water repellent.} ..

Therefore, the processing unit 16 of this example is configured to perform rinsing treatment in an environment in which an increase in hydroxyl groups existing on the surface of the silicon pattern 81 can be suppressed (hydroxyl suppression environment) (hydroxyl suppression environment). It has a forming part).
Hereinafter, a specific example of the configuration will be described with reference to FIG.

As shown in FIG. 3, the DIW supply unit 74 described above includes a DIW tank 741 that stores DIW, a pump 744 that sends the DIW stored in the DIW tank 741, and a liquid that removes air bubbles contained in the DIW. It includes a filter 745, a degassing module 746 that degass oxygen dissolved in DIW, and an air supply module 743 that supplies hydrogen gas to DIW.

The degassing module 746 removes the oxygen dissolved in the DIW to suppress the oxidation of the silicon pattern 81 during the rinsing treatment. For example, the degassing module 746 has a configuration in which a large number of hollow fiber membranes made of a resin material such as PTFE (polytetrafluoroethylene) are housed in the main body container. By passing DIW through the hollow fiber membrane and evacuating the inside of the main body container by vacuum, oxygen dissolved in the DIW permeates the hollow fiber membrane and is discharged to the container main body side.
The degassing module 746 corresponds to the degassing portion of this example and constitutes one of the hydroxylation suppressing environment forming portions.

_{The air supply module 743 absorbs hydrogen (H 2} ) gas into the DIW after the dissolved oxygen is removed by the degassing module 746 to saturate the DIW and suppress the reabsorption of oxygen. It also has a function of H-terminating by allowing hydrogen gas to act on the unbonded hands 811 and the like shown in FIG. 7 (b).
Similar to the degassing module 746, the air supply module 743 is configured by accommodating a large number of hollow fiber membranes that can permeate hydrogen gas in the main body container, and pressurizes the inside of the main body container with a gas containing hydrogen gas. As a result, the DIW flowing through the hollow fiber membrane absorbs hydrogen gas.

Here, when focusing on the function of suppressing the reabsorption of oxygen with respect to DIW, the gas absorbed by DIW is not limited to hydrogen gas, and may be nitrogen gas.
The air supply module 743 corresponds to the gas absorption unit of this example and constitutes one of the hydroxylation suppression environment forming units.

Further, the FFU 21 provided in the processing unit 16 of this example uses clean air (air) supplied from the air supply unit 211 and a nitrogen gas supply unit to supply gas for forming a downflow in the chamber 20. It can be switched between the nitrogen (N _{2) gas supplied from 212.} The air supply unit 211 and the nitrogen gas supply unit 212 are provided with a gas storage unit for storing these gases and a flow rate adjusting mechanism (both not shown).

The nitrogen gas supply unit 212 supplies nitrogen gas into the chamber 20 at the time of rinsing to create a low oxygen atmosphere, thereby suppressing oxidation of the silicon pattern 81. The gas supplied into the chamber 20 is not limited to nitrogen gas, and may be another inert gas that is inert to the silicon pattern 81, for example, a rare gas such as helium gas.
The nitrogen gas supply unit 212 corresponds to the inert gas supply unit of this example and constitutes one of the hydroxylation suppression environment forming units.

FIG. 3 shows an example in which three types of hydroxylation-suppressing environment forming units (DIW degassing module 746, air supply module 743, and nitrogen gas supply unit 212 for forming downflow) are provided, but the processing unit 16 is provided. However, it is not essential that all of these hydroxylation-suppressing environment-forming portions are provided, and at least one type of hydroxylation-suppressing environment-forming portion may be provided.

The operation timing of the degassing module 746 and the air supply module 743 and the switching operation of the gas supplied to the FFU 21 between the air supply unit 211 and the nitrogen gas supply unit 212 are executed by the above-mentioned control unit 18. Will be done.

The contents of the liquid treatment carried out by using the treatment unit 16 having the configuration described above will be described with reference to FIGS. 4 to 6.
When the wafer W carried into the processing unit 16 by the substrate transfer device 17 is held by the substrate holding mechanism 30, the processing fluid supply unit 40 is moved to the processing position and the wafer W is rotated at a predetermined rotation speed.

After that, the on-off valve V1 is opened, a predetermined flow rate of DHF is supplied from the DHF supply unit 71, and the etching residue and the oxide film on the surface of the wafer W are removed (process P1 in FIG. 4, chemical solution supply step).
At this time, as shown in FIG. 5, clean air is supplied to the FFU 21 from the air supply unit 211, and a downflow of clean air is formed in the chamber 20.

When it is time to end the supply of DHF, the gas supplied to the FFU 21 is switched to the nitrogen gas on the nitrogen gas supply unit 212 side, and a downflow of the nitrogen gas is formed in the chamber 20.
Next, the on-off valve V1 is closed to stop the supply of DHF, while the on-off valve V4 is opened to supply DIW from the DIW supply unit 74 (process P2 in FIG. 4, rinse liquid supply step).

At this time, as shown in FIG. 6, vacuum exhaust is performed in the main body container of the degassing module 746 to remove oxygen dissolved in DIW, and the inside of the main body container of the air supply module 743 is pressurized with hydrogen gas to dissolve. Allow the DIW after removing oxygen to absorb hydrogen gas.
After a branch line is provided between the air supply module 743 and the on-off valve V4 and the degassing module 746 and the air supply module 743 are started to operate, the dissolved oxygen in the DIW becomes equal to or less than the target concentration, and the hydrogen gas concentration becomes high. The DIW may be cut off until the target concentration is exceeded.

By supplying DIW, a rinsing process for removing DHF on the surface of the wafer W is performed. At this time, since the dissolved oxygen in the DIW is removed and the downflow of nitrogen gas is formed in the chamber 20, oxidation of the unbonded hands 811 on the silicon pattern 81 side and the H-terminated silicon is unlikely to occur. .. Further, the unbonded hand 811 shown in FIG. 7 (b) can be H-terminated by the action of hydrogen dissolved in DIW (FIG. 10).

As described above, the processing unit 16 of this example performs the rinsing treatment in a hydroxylation-suppressing environment (removal of dissolved oxygen in DIW, absorption of hydrogen gas into DIW, supply of nitrogen gas into chamber 20). As a result, the formation of the OH termination on the surface of the silicon pattern 81 described with reference to FIG. 8 is compared with the case where the rinsing treatment is performed in an atmosphere in which the downflow of clean air is formed using DIW containing dissolved oxygen. Can be suppressed.

When it is time to finish the rinsing process, the degassing module 746 and the air supply module 743 are stopped, the on-off valve V4 is closed to stop the DIW supply, and the on-off valve V2 is opened to start the IPA supply. Further, the gas supplied to the FFU 21 is switched to the air supply unit 211 side to form a downflow of clean air in the chamber 20 (process P3 in FIG. 4).
Regarding the treatments P3 to P5 of FIG. 4, the point that the supply source of the treatment liquid is switched to the IPA supply unit 72 and the water repellent agent supply unit 73, and the opening / closing valves V2 and 3 corresponding to these supply sources are opened. Except for this, since there is no difference from the example shown in FIG. 5, the state in which these treatment liquids and clean air for downflow are supplied is omitted.

When the DIW on the surface of the wafer W is replaced with the IPA, the on-off valve V2 is closed to stop the supply of the IPA, while the on-off valve V3 is opened to start the supply of the water repellent agent (FIG. 4). Treatment P4, water repellent supply step).
When the water repellent agent is supplied to the convex pattern 8 on the surface of the wafer W, the _{entire surface of the OH-terminated SiO 2} layer 82 is covered with the silyl group. It is the same as the state after supply (thick solid line in FIG. 11 (a) and silyl group 80 in FIG. 11 (b)).

On the other hand, the surface of the silicon pattern 81 that has been rinsed in the hydroxylation-suppressing environment has fewer OH terminations present on the surface of the silicon pattern 81 than in the case of the normal rinsing treatment. As a result, even if the water repellent agent is supplied, almost no silyl group is introduced on the surface of the silicon pattern 81 (silicon pattern 81 in FIGS. 11A and 11B).

On the other hand, as described above, the surface of the silicon pattern 81 after being treated with DHF has a certain degree of water repellency. Therefore, in the state where the silyl group is not introduced, the occurrence of pattern collapse in the convex pattern 8 can be sufficiently suppressed by covering only the surface on the _{SiO 2 layer 82 side, which has much smaller water repellency, with the silyl group.} Can be done.

When the surface of the SiO ₂ layer 82 is covered with the silyl group by the supply of the water repellent agent, the on-off valve V3 is closed to stop the supply of the water-repellent agent, and the on-off valve is again opened and closed. V2 is opened and the supply of IPA, which is a drying liquid, is started (process P5 in FIG. 4).
As a result, the water repellent on the surface of the wafer W is replaced by IPA.

Then, when the timing at which the water repellent agent on the surface of the wafer W is replaced with IPA is reached, the on-off valve V2 is closed to stop the supply of IPA. Further, the wafer W is dried by continuing the rotation of the wafer W and removing the IPA from the surface of the wafer W (process P6 in FIG. 4).

At this time, in the convex pattern 8 formed on the surface of the wafer W, the surface of the SiO ₂ layer 82 on the tip end side is covered with a hydrophobic silyl group. Due to the action of the silyl group, the surface tension that acts when the IPA that has entered the groove between the adjacent convex patterns 8 is removed is reduced, and the IPA can be removed while suppressing the occurrence of collapse of the convex pattern 8. It can be carried out.
When the drying process of the wafer W is completed, the rotation of the wafer W is stopped, and the liquid process for the wafer W is completed. After that, the wafer W is carried out from the processing unit 16 in the reverse procedure to that at the time of carrying in.

According to this embodiment, there are the following effects. Since DIW is supplied to the wafer W in a hydroxylation-suppressing environment that suppresses an increase in hydroxyl groups (OH terminations) existing on the surface of the silicon pattern 81 of the convex pattern 8, silyl groups substituted with hydroxyl groups are transferred to the surface of silicon. It can be suppressed from remaining.
As a result, the amount of residue remaining on the surface of the convex pattern 8 can be reduced after the _{SiO 2 film is embedded in the subsequent treatment.}

On the other hand, as in the case of the normal rinsing treatment, _{the surface of the SiO 2} layer 82 formed at the tip of the convex pattern 8 is covered with the silyl group, so that the surface of the wafer W can be seen. The surface tension acting on the convex pattern 8 when removing the liquid (IPA which is a dry liquid in this example) can be reduced, and the effect of suppressing the occurrence of pattern collapse can be exhibited as before.

Here, the convex pattern 8 to which the liquid treatment according to the present embodiment in which the rinsing treatment is performed in a hydroxyl group-suppressing environment is applied is not limited to the example shown in FIG. 7A. For example, in the convex pattern 8 of FIG. 7A, a SiN (silicon nitride) layer may be formed instead _{of the SiO 2 layer 82.}
Oxygen is taken into the SiN layer in the process of film formation, and an OH-terminated region also exists on the surface of the SiN layer.

The water repellency (contact angle of water) of the SiN layer is about half the size of the silicon pattern 81, but is nearly ten times larger than _{that of the SiO 2 layer 82.} On the other hand, in the state after the introduction of the silyl group, the hydroxyl group on the surface of the SiN layer is replaced with the silyl group, so that the water repellency of the SiN layer becomes about twice as large.
As described above, the surface of the silicon pattern 81 after the treatment with DHF has a certain degree of water repellency. Therefore, in the state where the silyl group is not introduced, the SiN layer side having low water repellency side. By preferentially introducing a silyl group on the surface of the convex pattern 8, the occurrence of pattern collapse in the convex pattern 8 can be sufficiently suppressed.

Further, FIG. 12 shows an example of a convex pattern 8a for a NAND circuit in which a _{SiO 2 layer 82, a polysilicon layer 83 and a SiN layer 84 are laminated on the tip end side of the convex pattern 8a.} In the convex pattern 8a of this example, when the water repellent agent is supplied after the rinsing treatment in the hydroxyl group suppressing environment, the surface of the _{SiO 2 layer 82 becomes visible as shown by the thick solid line in FIG.} While being covered with a silyl group, a silyl group is also introduced on the surface of the SiN layer 84.

A convex pattern for removing liquid from the surface of the wafer W after liquid treatment by introducing a silyl group into the surfaces of _{the SiO 2} layer 82 and the SiN layer 84 formed at the tip of the convex pattern 8a. The occurrence of collapse of 8a can be suppressed.
Residues on the surface of the SiN layer 84 are removed together with the SiN layer 84 by CMP. When it is also necessary to remove the residue on the surface of the SiO ₂ layer 82, the silyl group is removed using the ultraviolet irradiation unit 161 or the heating unit 162 for removing the silyl group, which will be described later, and then the SiO _{2 is removed.} The membrane may be embedded.

Next, as another method for rinsing in a hydroxyl group-suppressed environment, there is an example in which rinsing is performed using IPA, which has a lower oxygen solubility than DIW.
In FIG. 13, the DHF on the surface of the wafer W is removed by omitting the rinsing treatment (treatment P2) by DIW shown in FIG. 4 and immediately starting IPA substitution immediately after the supply of DHF (treatment P1). An example of rinsing treatment is described (treatment P3', rinsing liquid supply step). The rinsing treatment may be carried out in an atmosphere in which a downflow of nitrogen gas is formed in the chamber 20.

Here, since the solubility of DHF in IPA is smaller than the solubility of DHF in DIW, during the rinsing treatment using IPA (process P3'in FIG. 13), the IPA replacement shown in FIG. 4 (FIG. 4). It is preferable to increase the supply flow rate of IPA per unit time and to lengthen the supply time of IPA as compared with the process P3).
The IPA supply unit 72 that supplies the IPA that is the rinsing liquid constitutes one of the hydroxylation suppression environment forming units of this example.

Further, the content of the liquid treatment performed on the wafer W is not limited to the examples described with reference to FIGS. 4 and 13, and the type of treatment liquid supplied in each treatment is appropriately used. , May be changed.
For example, BHF may be supplied instead of DHF that removes the oxide film in the process P1 that is the chemical solution supply step. Further, for the drying liquid supplied in the treatment P5 before the wafer W is dried, another organic solvent such as acetone may be supplied instead of IPA.

Next, as an additional embodiment, a process for removing the silyl group remaining on the surface of the convex pattern 8 will be described.
As described above, even when the rinsing treatment is performed in a hydroxyl group-suppressing environment to suppress the oxidation of the silicon pattern 81, the surface of the silicon pattern 81 is slightly oxidized and silyl is formed at the OH-terminated portion. The group may be introduced. Further, as in the convex pattern 8a shown in FIG. 12, _{the surface of the SiO 2} layer 82 which is not removed by CMP or the like in the subsequent step may remain covered with the silyl group.

As a method for removing unnecessary silyl groups remaining on the surface of the wafer W, a method of decomposing the silyl groups by irradiating the wafer W with ultraviolet rays (UV: Ultra Violet) or heating the wafer W is conceivable. Be done.
However, if the wafer W is UV-irradiated or heated in an atmosphere in which oxygen is present, an oxide film may be formed again on the surface of the silicon pattern 81. On the other hand, it was found that even if these treatments are performed in a low oxygen atmosphere, the effect of decomposing the silyl group may not be sufficiently obtained.

Therefore, the substrate processing system 1 of this example is an ultraviolet irradiation unit (ultraviolet irradiation) that performs UV irradiation (ultraviolet irradiation treatment) on the wafer W after liquid treatment in a low oxygen atmosphere to which nitrogen gas, which is an inert gas, is supplied. Part) 161 and a heating unit (heating part) 162 that heats (heat-treats) the wafer W after UV irradiation in a low oxygen atmosphere to which nitrogen gas is also supplied.
These ultraviolet irradiation treatments and heat treatments constitute a hydrophobic group removing step for removing silyl groups (hydrophobic groups) existing on the surface of the wafer W.

The ultraviolet irradiation unit 161 is provided so that the wafer W is placed on the mounting table 912 arranged in the chamber 911 to which the nitrogen gas is supplied from the nitrogen gas supply line 914 and faces the wafer W on the mounting table 912. UV light is emitted from the UV light source 913.
For example, the oxygen concentration in the chamber 911 is 5% or less, preferably 1% or less, and as the UV light source 913, various UV light sources 913 having a wavelength of about 300 nm or less, such as a mercury lamp, a UV LED, and an excimer light UV lamp, may be adopted. .. The amount of energy dose per unit area of the wafer W varies depending on the number of silyl groups per unit area remaining on the surface of the wafer W, but can be exemplified to be about ^{200 to 600 mJ / cm 2.}

The heating unit 162 is composed of a resistance heating element or the like provided in a heating unit 923 on which a wafer W is placed on a mounting table 922 arranged in a chamber 921 in which nitrogen gas is supplied from a nitrogen gas supply line 924. The heating unit 923 heats the wafer W via the mounting table 912. The method of heating the wafer W is not limited to heat transfer via the mounting table 922, and may be heating by heat radiation using a heating lamp as the heating unit 923.
For example, the oxygen concentration in the chamber 921 is 5% or less, preferably 1% or less, and the wafer W is heated to a temperature in the range of 200 to 800 ° C., preferably 300 to 400 ° C., for example, about 30 seconds to 10 minutes. Heating is carried out.

The ultraviolet irradiation unit 161 and the heating unit 162 of this example can be provided in place of the two processing units 16 arranged on the transport unit 12 side of the substrate processing system 1 shown in FIG. The wafer W after liquid treatment in each processing unit 16 is sequentially carried into these units 161 and 162, and is subjected to UV irradiation and heating in a low oxygen atmosphere.

At this time, nitrogen gas is supplied to the path through which the wafer W is transported from the ultraviolet irradiation unit 161 to the heating unit 162, and the wafer W is transported in a low oxygen atmosphere, whereby oxidation progresses on the surface of the silicon pattern 81. May be suppressed.
Further, the UV light source 913 and the heating unit 923 may be provided in the common chamber 911 to continuously carry out UV irradiation and heating, or to carry out UV irradiation and heating at the same time.

(experiment)
For additional embodiments, the effects of UV irradiation and heating in a low oxygen atmosphere were investigated.
A. Experimental conditions
(Comparative Example 1) In order to increase the sensitivity of the effect of removing silyl groups, DHF was supplied to the surface of a wafer W having a diameter of 300 mm, and then ozone water was further supplied before rinsing. However, the liquid treatment was carried out according to the procedure shown in FIG. 4, except for the point where the normal rinsing treatment was carried out.
(Comparative Example 2) After performing the liquid treatment under the conditions of Comparative Example 1, the amount of UV light of 173 nm from the excimer UV light source 913 is applied to the wafer W under a nitrogen gas supply atmosphere (oxygen concentration of 10% vol or less). The irradiation was carried out so as to be 400 mJ / cm ^2.
(Example)
After irradiating with UV light under the condition of Comparative Example 2, the wafer W was heated at 450 ° C. for 10 minutes under a nitrogen gas supply atmosphere (oxygen concentration of 10% vol or less).
The contact angle of the wafer W and the film thickness of the oxide film formed on the surface of the wafer W were measured after each of the above three conditions.

B. Experimental result
The results of Examples 1 and 2 are shown in FIG. The horizontal axis of FIG. 15 shows the identification numbers of each Example and Comparative Example, the vertical axis on the left side shows the contact angle [°], and the vertical axis on the right side shows the film thickness [nm] of the oxide film. In FIG. 15, the contact angle is plotted as a white diamond, and the oxide film thickness is plotted as a white square.

According to the results shown in FIG. 15, it can be seen that in the example in which heating was performed after UV irradiation in a low oxygen atmosphere, the contact angle was the smallest and more silyl groups were removed. Next, since the contact angle increased in the order of Comparative Examples 1 and 2, it was confirmed that UV irradiation and heating each had an effect of removing the silyl group.

W Wafer 16 Processing unit 20 Chamber 212 Nitrogen gas supply unit 30 Substrate holding mechanism 40 Processing fluid supply unit 71 DHF supply unit 73 Water repellent agent supply unit 74 DIW supply unit 743 Air supply module 746 Degassing module

Claims (16)

In the liquid treatment method of the substrate
A chemical solution supply step of forming a convex pattern of silicon and supplying a chemical solution to the surface of a substrate containing at least one layer of silicon oxide and silicon nitride different from the silicon at the tip of the convex pattern.
After the chemical solution supply step, a rinse solution supply step of supplying the rinse solution to the surface of the substrate, and a rinse solution supply step.
After the rinse liquid supply step, a water repellent agent supply step of supplying a water repellent agent that replaces a hydroxyl group on the surface of the substrate with a hydrophobic group to make the surface of the tip of the convex pattern water repellent. , Including
The rinsing liquid supplying step, the liquid processing method characterized by being performed in suppressing hydroxide suppressed environment an increase in the hydroxyl groups present on the surface of the silicon of the convex pattern. The liquid treatment method according to claim 1, wherein a hydroxylation-suppressing environment is formed by using pure water in which dissolved oxygen has been degassed as the rinsing liquid. The liquid treatment method according to claim 1 or 2, wherein a hydroxylation-suppressing environment is formed by using pure water in which at least one of hydrogen gas and nitrogen gas is absorbed as the rinsing liquid. The liquid treatment method according to claim 1, wherein the hydroxylation-suppressing environment is formed by using isopropyl alcohol as the rinsing liquid. The liquid treatment method according to any one of claims 1 to 4, wherein the hydroxylation-suppressing environment is formed by carrying out the rinse liquid supply step in an atmosphere to which the inert gas is supplied. .. The liquid treatment method according to any one of claims 1 to 5, wherein the chemical solution is a chemical solution for removing an oxide film on the surface of the silicon. The first aspect of the present invention is characterized in that, after the water repellent supply step, a hydrophobic group removing step of removing the liquid existing on the surface of the substrate and then removing the hydrophobic group existing on the surface of the substrate is included. The liquid treatment method according to any one of 6 and 6. The hydrophobic group removing step involves an ultraviolet irradiation treatment of irradiating the substrate with ultraviolet rays in an atmosphere supplied with an inert gas, and heating the substrate after the ultraviolet rays or the substrate irradiated with the ultraviolet rays. The liquid treatment method according to claim 7, further comprising heat treatment. In a liquid treatment device that treats liquid on a substrate
A silicon convex pattern is formed, and at the tip of the convex pattern, a substrate holding portion that horizontally holds a substrate containing at least one layer of silicon oxide and silicon nitride different from the silicon, and
A chemical solution supply nozzle that supplies a chemical solution to the surface of the substrate, a rinse solution supply nozzle that supplies a rinse solution, and a water repellent agent supply nozzle that supplies a water repellent agent that replaces a hydroxyl group on the surface of the substrate with a hydrophobic group. ,
A step of supplying the chemical solution from the chemical solution supply nozzle to the surface of the substrate held by the substrate holding portion, a step of supplying the chemical solution from the rinse solution supply nozzle to the surface of the substrate after the chemical solution supply, and then a step of supplying the rinse solution to the surface of the substrate. Control to output a control signal for executing the step of supplying the water repellent agent from the water repellent supply nozzle to the surface of the substrate and making the surface of the tip portion of the convex pattern water repellent. Department and
And characterized by comprising a hydroxide suppressing environmental forming portion for performing the steps of supplying the rinse liquid suppressing hydroxide suppressed environment an increase in the hydroxyl groups present on the surface of the silicon of the convex pattern Liquid treatment equipment. The hydroxylation suppression environment forming unit degass the pure water supply unit that supplies pure water to the rinse liquid supply nozzle and the dissolved oxygen contained in the pure water supplied from the pure water supply unit to the rinse liquid supply nozzle. The liquid treatment apparatus according to claim 9, further comprising a degassing portion. The hydroxylation suppression environment forming unit is a pure water supply unit that supplies pure water to the rinse liquid supply nozzle, and the pure water supplied from the pure water supply unit to the rinse liquid supply nozzle, and hydrogen gas and nitrogen gas are added to the pure water. The liquid treatment apparatus according to claim 9 or 10, further comprising a gas absorbing unit that absorbs at least one of them. The liquid treatment apparatus according to claim 9, wherein the hydroxylation-suppressing environment forming unit includes an IPA supply unit that supplies isopropyl alcohol (IPA) to the rinse liquid supply nozzle. The hydroxylation suppressing environment forming unit includes an inert gas supply unit that supplies an inert gas in a space where the rinse liquid is supplied from the rinse liquid supply nozzle to the substrate held by the substrate holding unit. The liquid treatment apparatus according to any one of claims 9 to 12, wherein the liquid treatment apparatus is characterized. The liquid treatment apparatus according to any one of claims 9 to 13, wherein the chemical solution supply nozzle is provided with a chemical solution supply unit for supplying a chemical solution for removing an oxide film on the surface of the silicon. In order to remove the hydrophobic group existing on the surface of the substrate from which the water repellent agent has been supplied and the liquid on the surface has been removed, ultraviolet rays irradiate the substrate with ultraviolet rays in an atmosphere to which an inert gas is supplied. The liquid according to any one of claims 9 to 14, further comprising an irradiation unit and a heating unit for heating the substrate after being irradiated with the ultraviolet rays or the substrate irradiated with ultraviolet rays. Processing equipment. A storage medium for storing a computer program used in a liquid treatment apparatus that supplies liquid to a horizontally held substrate and then supplies liquid to the substrate to perform liquid treatment.
A storage medium, wherein the computer program controls to execute the liquid treatment method according to any one of claims 1 to 8.

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