JP2008109093A - Film forming method, and film forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film forming method and a film forming apparatus capable of uniformly forming a good-quality SiO<SB>2</SB>film at a high speed even at a low temperature of ≤300°C, especially ≤100°C. <P>SOLUTION: In this method, the following steps are alternately executed: a step S1 of putting a workpiece into a processing chamber capable of being kept in vacuum state, and supplying an Si source into the processing chamber using an amino-silane gas of molecules each having two amino groups as the Si source, and oxygen radicals as an oxidizer; and a step S2 of supplying the oxygen radicals into the processing chamber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a film forming method and a film forming apparatus for forming a SiO ₂ thin film on an object to be processed such as a semiconductor wafer.

In a semiconductor device manufacturing process, there is a process of forming a SiO ₂ film on a semiconductor wafer typified by a silicon wafer. In such a SiO ₂ film forming process, a vertical batch heat treatment is performed. A technique is used in which a plurality of semiconductor wafers are collectively formed by chemical vapor deposition (CVD) using an apparatus.

And recently, with the progress of miniaturization and integration of semiconductor devices, the formation of SiO ₂ film having good quality characteristics at a low temperature of 400 ° C. or lower is required. A technique for forming a SiO ₂ film using ALD (Atomic Layer Deposition) in which an Si layer and an oxidant are intermittently supplied and repeatedly formed at an atomic layer level or a molecular layer level has been proposed ( For example, Patent Document 1).

However, recently, the demand for reducing the thermal history in the manufacturing process of semiconductor devices has further increased, and a technique capable of forming a SiO ₂ film at a lower temperature has been demanded. In addition to this, high throughput is also demanded, and in addition to film formation at a lower temperature, there is a need for a technique that can form a SiO ₂ film with good film quality at high speed and uniformly. .
Japanese Patent Laid-Open No. 2003-7700

The present invention has been made in view of such circumstances, and an object thereof is to provide a film forming method and a film forming apparatus capable of forming a SiO ₂ film even at a low temperature of 300 ° C. or lower, particularly 100 ° C. or lower. And It is another object of the present invention to provide a film forming method and a film forming apparatus capable of producing a SiO ₂ film having a good film quality at high speed and uniformly in addition to such low temperature film forming. It is another object of the present invention to provide a computer-readable storage medium in which a control program for executing such a film forming method is stored.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have used an aminosilane gas having two amino groups in one molecule as a Si source, preferably BTBAS (Bisteria butylaminosilane), and an oxidizing agent. By performing ALD using oxygen radicals, preferably O ₂ plasma, it is possible to form a film at a significantly lower temperature than before, specifically, a low temperature film formation of 300 ° C. or less, particularly 100 ° C. or less. Even so, it has been found that a high-quality SiO ₂ film can be stably produced at high speed, and the present invention has been achieved.

That is, in the present invention, an object to be processed is charged in a processing container capable of maintaining a vacuum, an aminosilane gas having two amino groups in one molecule is used as a Si source, an oxygen radical is used as an oxidizing agent, Is alternately supplied into the processing container to form a SiO ₂ film on the surface of the object to be processed.

In the film forming method according to the present invention, as the Si source gas, at least one selected from BTBAS (Bisthal Butylaminosilane), BDEAS (Bisdiethylaminosilane), and BDMAS (Bisdimethylaminosilane) can be used. Moreover, oxygen-containing gas plasma can be used as the oxygen radical, and the oxygen-containing gas plasma is at least selected from O ₂ gas, NO gas, N ₂ O gas, H ₂ O gas, and O ₃ gas. One of the plasmas can be used.

  In the film forming method, the step of supplying the Si source into the processing container and the step of supplying the oxygen radical into the processing container can be alternately performed. In this case, a step of removing the gas remaining in the processing vessel between the step of supplying the Si source into the processing vessel and the step of supplying the oxygen radicals into the processing vessel. Can be inserted. In the step of removing the gas remaining in the processing container, a purge gas can be introduced into the processing container while evacuating the processing container. In addition, the temperature during film formation is preferably 300 ° C. or lower, and more preferably 100 ° C. or lower.

In addition, the present invention is a film forming apparatus for forming a SiO ₂ film on an object to be processed, the processing container having a vertical cylindrical shape that can be held in vacuum, and the object to be processed in a plurality of stages. A holding member to be held in the processing container in a held state, a heating device provided on the outer periphery of the processing container, and Si for supplying aminosilane gas having two amino groups in one molecule into the processing container A source supply mechanism, an oxygen-containing gas supply mechanism that supplies an oxygen-containing gas into the processing vessel, an activation mechanism that activates the oxygen-containing gas to form oxygen radicals, and the Si source gas and oxygen radicals. There is provided a film forming apparatus comprising a control mechanism for alternately supplying the inside of the processing container.

In the film forming apparatus, a plasma generation mechanism that generates oxygen-containing gas plasma can be used as the activation mechanism. As the oxygen-containing gas plasma generated by this plasma generation mechanism, plasma obtained by converting at least one selected from O ₂ gas, NO gas, N ₂ O gas, H ₂ O gas, and O ₃ gas into plasma is used. it can.

  Further, in the film forming apparatus, the control mechanism is controlled to alternately perform the step of supplying the Si source gas into the processing container and the step of supplying oxygen radicals into the processing container. Can be configured. In this case, the control mechanism causes the gas remaining in the processing vessel between the step of supplying the Si source into the processing vessel and the step of supplying the oxygen radical into the processing vessel. It can comprise so that it may control so that the process of removing may be inserted. Furthermore, a purge gas supply mechanism for supplying a purge gas into the processing container is further provided, and the control mechanism is configured to supply the purge gas into the processing container during the step of removing the gas. be able to.

  The film forming apparatus can be configured to further include a temperature control mechanism for controlling the film forming temperature to 300 ° C. or lower, more preferably 100 ° C. or lower. Furthermore, in the above-described film forming apparatus, at least one selected from BTBAS (Bisthal butylaminosilane), BDEAS (bisdiethylaminosilane), and BDMAS (bisdimethylaminosilane) can be used as the Si source gas. .

  Furthermore, the present invention is a computer-readable storage medium in which a control program that runs on a computer is stored, and the control program stores a film forming apparatus in the computer so that the film forming method is performed at the time of execution. It is possible to provide a computer-readable storage medium characterized by controlling the computer.

According to the present invention, ALD is performed using an aminosilane gas having two amino groups in one molecule as a Si source and oxygen radicals as an oxidant. The following low temperature film formation is possible. Further, even with such low temperature film formation, a high-quality SiO ₂ film can be manufactured at high speed and stably.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view showing an example of a film forming apparatus for carrying out the film forming method of the present invention, FIG. 2 is a cross sectional view showing the film forming apparatus of FIG. 1, and FIG. It is a timing chart which shows the timing of supply of gas. In FIG. 2, the heating device is omitted.

  The film forming apparatus 100 includes a cylindrical processing container 1 having a ceiling with a lower end opened. The entire processing container 1 is made of, for example, quartz, and a ceiling plate 2 made of quartz is provided on the ceiling in the processing container 1 and sealed. In addition, a manifold 3 formed in a cylindrical shape from, for example, stainless steel is connected to the lower end opening of the processing container 1 via a seal member 4 such as an O-ring.

  The manifold 3 supports the lower end of the processing vessel 1, and a quartz wafer boat 5 on which a large number of, for example, 50 to 100 semiconductor wafers W can be placed in multiple stages as objects to be processed from below the manifold 3. Can be inserted into the processing container 1. The wafer boat 5 has three columns 6 (see FIG. 2), and a large number of wafers W are supported by grooves formed in the columns 6.

  The wafer boat 5 is placed on a table 8 via a quartz heat insulating cylinder 7, and the table 8 passes through a lid 9 made of, for example, stainless steel that opens and closes the lower end opening of the manifold 3. It is supported on the rotating shaft 10.

  And the magnetic fluid seal | sticker 11 is provided in the penetration part of this rotating shaft 10, for example, and the rotating shaft 10 is supported rotatably, sealing airtightly. Further, a sealing member 12 made of, for example, an O-ring is interposed between the peripheral portion of the lid portion 9 and the lower end portion of the manifold 3, thereby maintaining the sealing performance in the processing container 1.

  The rotary shaft 10 is attached to the tip of an arm 13 supported by an elevating mechanism (not shown) such as a boat elevator, for example, and moves up and down the wafer boat 5 and the lid 9 etc. integrally. 1 is inserted into and removed from the inside. The table 8 may be fixedly provided on the lid 9 side, and the wafer W may be processed without rotating the wafer boat 5.

In addition, the film forming apparatus 100 includes an oxygen-containing gas supply mechanism 14 that supplies an oxygen-containing gas, for example, O ₂ gas, into the processing container 1, and two amino groups in one molecule as Si source gas into the processing container 1. A Si source gas supply mechanism 15 for supplying an aminosilane gas having Bt, such as BTBAS (Bistally butylaminosilane), and a purge gas supply mechanism 16 for supplying an inert gas, for example, N ₂ gas, as a purge gas into the processing vessel 1. ing.

The oxygen-containing gas supply mechanism 14 is connected to the oxygen-containing gas supply source 17, the oxygen-containing gas pipe 18 that guides the oxygen-containing gas from the oxygen-containing gas supply source 17, and the oxygen-containing gas pipe 18. An oxygen-containing gas dispersion nozzle 19 made of a quartz tube that penetrates inward and is bent upward and extends vertically is provided. A plurality of gas discharge holes 19a are formed at a predetermined interval in the vertical portion of the oxygen-containing gas dispersion nozzle 19, and oxygen is uniformly distributed from each gas discharge hole 19a toward the processing container 1 in the horizontal direction. A contained gas, for example, O ₂ gas can be discharged.

  The Si source gas supply mechanism 15 is connected to the Si source gas supply source 20, the Si source gas pipe 21 that guides the Si source gas from the Si source gas supply source 20, and the Si source gas pipe 21. And a Si source gas dispersion nozzle 22 made of a quartz tube that is bent upward and extends vertically through the side wall. Here, two Si source gas dispersion nozzles 22 are provided (see FIG. 2), and each Si source gas dispersion nozzle 22 has a plurality of gas discharge holes 22a at predetermined intervals along the length direction thereof. An aminosilane gas having two amino groups in one molecule as a Si source gas, for example, BTBAS gas, can be discharged from each gas discharge hole 22a in a horizontal direction into the processing vessel 1 in a horizontal direction. It can be done. Note that only one Si source gas dispersion nozzle 22 may be provided.

Further, the purge gas supply mechanism 16 includes a purge gas supply source 23, a purge gas pipe 24 that guides the purge gas from the purge gas supply source 23, and a purge gas nozzle 25 that is connected to the purge gas pipe 24 and is provided through the side wall of the manifold 3. have. As the purge gas, an inert gas such as N ₂ gas can be preferably used.

  The oxygen-containing gas pipe 18, the Si source gas pipe 21, and the purge gas pipe 24 are provided with on-off valves 18a, 21a, 24a and flow controllers 18b, 21b, 24b such as mass flow controllers, respectively. Si source gas and purge gas can be supplied while controlling their flow rates.

  A plasma generation mechanism 30 that forms plasma of the oxygen-containing gas is formed on a part of the side wall of the processing vessel 1. This plasma generation mechanism 30 is airtight on the outer wall of the processing container 1 so as to cover the opening 31 formed vertically from the outside by scraping the side wall of the processing container 1 with a predetermined width along the vertical direction. And has a plasma compartment wall 32 welded thereto. The plasma partition wall 32 has a concave cross-sectional shape and is elongated vertically, and is made of, for example, quartz. The plasma generation mechanism 30 includes a pair of elongated plasma electrodes 33 disposed on the outer surfaces of both side walls of the plasma partition wall 32 so as to face each other in the vertical direction, and a power supply line 34 provided to the plasma electrode 33. And a high frequency power supply 35 for supplying high frequency power. Then, by applying a high frequency voltage of 13.56 MHz, for example, from the high frequency power supply 35 to the plasma electrode 33, plasma of oxygen-containing gas can be generated. Note that the frequency of the high-frequency voltage is not limited to 13.56 MHz, and other frequencies such as 400 kHz may be used.

  By forming the plasma partition wall 32 as described above, a part of the side wall of the processing container 1 is recessed outward in the shape of a recess, and the internal space of the plasma partition wall 32 is integrated with the internal space of the processing container 1. Will be in a state of communication. The opening 31 is formed long enough in the vertical direction so as to cover all the wafers W held by the wafer boat 5 in the height direction.

  The oxygen-containing gas dispersion nozzle 19 is bent outward in the radial direction of the processing container 1 in the middle of extending upward in the processing container 1, and is the innermost part (processing container 1) in the plasma partition wall 32. (The portion farthest from the center of the head)). For this reason, when the high frequency power supply 35 is turned on and a high frequency electric field is formed between the electrodes 33, the oxygen gas injected from the gas injection holes 19 a of the oxygen-containing gas dispersion nozzle 19 is turned into plasma, and the processing container 1. It flows while diffusing toward the center.

  An insulating protective cover 36 made of, for example, quartz is attached to the outside of the plasma partition wall 32 so as to cover it. In addition, a refrigerant passage (not shown) is provided in the inner portion of the insulating protective cover 36, and the plasma electrode 33 can be cooled by flowing a cooled nitrogen gas, for example.

  The two Si source gas dispersion nozzles 22 are provided upright at a position sandwiching the opening 31 on the inner wall of the processing container 1, and a plurality of gas injection holes formed in the Si source gas dispersion nozzle 22. An aminosilane gas having two amino groups in one molecule can be discharged as a Si source gas toward the center of the processing vessel 1 from 22a.

  On the other hand, an exhaust port 37 for evacuating the inside of the processing container 1 is provided at a portion opposite to the opening 31 of the processing container 1. The exhaust port 37 is formed in an elongated shape by scraping the side wall of the processing container 1 in the vertical direction. An exhaust port cover member 38 having a U-shaped cross section so as to cover the exhaust port 37 is attached to a portion corresponding to the exhaust port 37 of the processing container 1 by welding. The exhaust port cover member 38 extends upward along the side wall of the processing container 1, and defines a gas outlet 39 above the processing container 1. The gas outlet 39 is evacuated by a vacuum exhaust mechanism including a vacuum pump (not shown). A cylindrical heating device 40 for heating the processing container 1 and the wafer W inside the processing container 1 is provided so as to surround the outer periphery of the processing container 1.

  Control of each component of the film forming apparatus 100, for example, supply / stop of each gas by opening / closing valves 18a, 21a, 24a, control of gas flow rate by the mass flow controllers 18b, 21b, 24b, and on / off control of the high-frequency power source 35 The control of the heating device 40 is performed by a controller 50 including, for example, a microprocessor (computer). Connected to the controller 50 is a user interface 51 including a keyboard for a process manager to input commands to manage the film forming apparatus 100, a display for visualizing and displaying the operating status of the film forming apparatus 100, and the like. Has been.

  Further, the controller 50 causes each component of the film forming apparatus 100 to execute processes according to a control program for realizing various processes executed by the film forming apparatus 100 under the control of the controller 50 and processing conditions. A storage unit 52 that stores a program for storing the recipe, that is, a recipe, is connected. The recipe is stored in a storage medium in the storage unit 52. The storage medium may be a hard disk or semiconductor memory, or may be portable such as a CDROM, DVD, flash memory or the like. Moreover, you may make it transmit a recipe suitably from another apparatus via a dedicated line, for example.

  Then, if necessary, an arbitrary recipe is called from the storage unit 52 by an instruction from the user interface 51 and is executed by the controller 50, so that a desired process in the film forming apparatus 100 is performed under the control of the controller 50. Is done.

Next, a method for forming a SiO ₂ film according to this embodiment, which is performed using the film forming apparatus configured as described above, will be described with reference to FIG.

  First, at room temperature, for example, a wafer boat 5 on which 50 to 100 semiconductor wafers W are mounted is loaded into the processing container 1 controlled in advance at a predetermined temperature by raising it from below, and the lid 9 By closing the lower end opening of the manifold 3, the inside of the processing container 1 is made a sealed space. An example of the semiconductor wafer W is 300 mm in diameter.

  Then, the inside of the processing vessel 1 is evacuated to maintain a predetermined process pressure, and the power supplied to the heating device 40 is controlled to increase the wafer temperature to maintain the process temperature, and the wafer boat 5 is rotated. The film forming process is started in this state.

  As shown in FIG. 3, the film formation process at this time includes a step S1 in which an aminosilane gas having two amino groups in one molecule, for example, BTBAS is flowed as an Si source gas to adsorb the Si source, and an oxygen-containing gas. Step S2 in which oxygen radicals formed by exciting the gas are supplied to the processing container 1 to oxidize the Si source gas are alternately repeated, and the gas remaining in the processing container 1 is removed from the processing container 1 between them. Step S3 is performed.

  Specifically, in step S1, an aminosilane gas having two amino groups in one molecule as a Si source gas, eg BTBAS, is supplied from the Si source gas supply source 20 of the Si source gas supply mechanism 15 as a Si source gas pipe 21. Then, the gas is supplied from the gas discharge hole 22a into the processing container 1 through the Si source gas dispersion nozzle 22 for a period T1. Thereby, the Si source is adsorbed on the semiconductor wafer. The period T1 at this time is exemplified by 1 to 180 seconds. Further, the flow rate of the Si source gas is exemplified by 1-1000 mL / min (sccm). Moreover, the pressure in the processing container 1 at this time is exemplified by 13.3 to 1333 Pa (0.1 to 10 Torr).

  In this case, examples of the aminosilane gas having two amino groups in one molecule used as the Si source gas include BDEAS (bisdiethylaminosilane) and BDMAS (bisdimethylaminosilane) in addition to the above BTBAS. Since the number of amino groups per molecule is as small as two, structurally, as in the above-mentioned Patent Document 1, the number of amino groups is more a hindrance to the Si adsorption reaction than the aminosilane gas (structure hindrance). hard. In addition, an aminosilane gas having two amino groups in one molecule is more stable than one having one amino group per molecule, and among these, BTBAS is most preferable.

In the step of supplying oxygen radicals in step S 2, for example, O ₂ gas is supplied as an oxygen-containing gas from the oxygen-containing gas supply source 17 of the oxygen-containing gas supply mechanism 14 through the oxygen-containing gas pipe 18 and the oxygen-containing gas dispersion nozzle 19. The gas is discharged from the gas discharge hole 19a. At this time, the high-frequency power source 35 of the plasma generation mechanism 30 is turned on to form a high-frequency electric field, and oxygen-containing gas, for example, O ₂ gas is converted into plasma by this high-frequency electric field. The oxygen-containing gas that has been converted into plasma is supplied into the processing container 1. Thereby, the Si source adsorbed on the semiconductor wafer W is oxidized to form SiO ₂ . The period T2 of this process is exemplified by a range of 1 to 300 seconds. Further, the flow rate of the oxygen-containing gas varies depending on the number of mounted semiconductor wafers W, but 100 to 20000 mL / min (sccm) is exemplified. The frequency of the high frequency power supply 35 is exemplified by 13.56 MHz, and the power is 5 to 1000 W. Moreover, the pressure in the processing container 1 at this time is exemplified by 13.3 to 1333 Pa (0.1 to 10 Torr).

In this case, examples of the oxygen-containing gas include O ₂ gas, NO gas, N ₂ O gas, H ₂ O gas, and O ₃ gas, which are converted into plasma by a high frequency electric field and used as an oxidizing agent. . The oxidant is not limited to oxygen-containing gas plasma as long as it is an oxygen radical, but it is preferable to form oxygen-containing gas plasma, and among them, O ₂ plasma is preferable. By using plasma of oxygen radicals, particularly oxygen-containing gas, as the oxidant, the SiO ₂ film can be formed at 300 ° C. or lower, further 100 ° C. or lower, ideally even at room temperature.

Further, step S3 performed between step S1 and step S2 is a step of removing a gas remaining in the processing container 1 after step S1 or after step S2 and causing a desired reaction in the next step. In addition, an inert gas such as N ₂ gas is supplied as a purge gas from the purge gas supply source 23 of the purge gas supply mechanism 16 through the purge gas pipe 24 and the purge gas nozzle 25 while evacuating the inside of the processing container 1. The period T3 of this step S3 is exemplified by 1 to 60 sec. The purge gas flow rate is exemplified by 50 to 20000 mL / min (sccm). In this step S3, if the gas remaining in the processing container 1 can be removed, the evacuation may be continuously performed without supplying the purge gas without supplying the purge gas. Good. However, the residual gas in the processing container 1 can be removed in a short time by supplying the purge gas. The pressure in the processing container 1 at this time is exemplified by 13.3 to 1333 Pa (0.1 to 10 Torr).

In this way, the SiO ₂ film is thin by repeatedly supplying the Si source gas and the oxygen-containing plasma as oxygen radicals alternately and intermittently with the step S3 of removing the gas from the processing vessel 1 in between. The films can be laminated one layer at a time to a predetermined thickness.

The reaction at this time will be schematically described with reference to FIG.
As shown in FIG. 4A, OH groups are present on the surface of the already deposited SiO ₂ film, and for example, BTBAS is supplied thereto as a Si source. In the step (step S1) in which the Si source is adsorbed, as shown in FIG. 4B, Si of BTBAS reacts with O of the OH group on the surface to release the trimethylamino group. At this time, BTBAS, which is an aminosilane having two amino groups, has high reactivity with OH, and is structurally unlikely to be a hindrance to such Si reaction, so that the Si adsorption reaction proceeds rapidly. The trimethylamino group eliminated at this time is removed from the processing container 1 in step S3. Then, in the next oxidation step (step S2), as shown in FIG. 4C, the Si compound after the trimethylamino group is detached is oxidized by oxygen radicals such as O ₂ gas plasma, and SiO _2. (However, H is adsorbed on the surface and OH groups are formed). Thus, unlike a pure chemical reaction, an oxidation reaction using oxygen radicals such as O ₂ gas plasma does not require a high temperature, and thus can be performed at a low temperature.

Based on the ALD technique that enables film formation at a low temperature and provides good film quality as described above, two amino acids in one molecule represented by BTBAS, which is highly reactive as a Si source and hardly causes structural damage, is used. Since oxygen radicals such as O ₂ gas plasma in which the reaction proceeds without increasing the temperature in the oxidation treatment using an aminosilane having a group, a SiO ₂ film having a good film quality is 100 ° C. or lower, and further room temperature. Therefore, it is possible to form a film at a low temperature and a high film formation rate, which is unthinkable.

  In the present invention, the film can be formed at an extremely low temperature of 100 ° C. or lower in principle, but the film can be formed even at a higher temperature. However, the film thickness variation increases as the film formation temperature rises, and when the temperature exceeds 300 ° C., the film thickness variation may not be negligible. Therefore, the film formation temperature is preferably 300 ° C. or lower.

Next, the result of actual film formation based on the present invention will be described.
First, an experiment was conducted on an oxidizing agent. A SiO ₂ film was formed by ALD using BTBAS as the Si source gas and O ₂ gas plasma for the oxidation treatment. Here, 100 300 mm wafers are inserted into the processing container, the deposition temperature is 100 ° C., the supply amount of BTBAS is 30 mL / min (sccm), the pressure is 533 Pa (4 Torr), and step S1 is performed for 30 seconds. ₂ gas supply amount is 2000 mL / min (sccm), pressure is 66.5 Pa (0.5 Torr), high frequency power of 13.56 MHz is 50 W, step S2 is performed for 40 seconds, and this is repeated for 42 cycles to form a SiO ₂ film. A film was formed. For purging inside the processing container, N ₂ gas is supplied as a purge gas at a flow rate of 3500 mL / min (sccm) for 7 seconds while continuing to evacuate the processing container before step S 1. For example, N ₂ gas was supplied as a purge gas for 6 sec at a flow rate of 3500 mL / min (sccm) while continuing to evacuate the processing container.

For comparison, a SiO ₂ film was formed under the same conditions as above except that O ₃ gas was supplied at a flow rate of 250 g / Nm ³ without being converted into plasma as an oxidizing agent in the oxidation treatment in step S2.

The result is shown in FIG. FIG. 5 shows the film formation rate normalized with the center film formation rate of 1 when O ₃ gas is used as the oxidant on the vertical axis, and the center in-plane uniformity when O ₃ gas is also used as the oxidant. In-plane uniformity normalized to 1 as the property. As shown in this figure, when O ₂ gas plasma, which is oxygen radicals, is used as an oxidant according to the present invention, the film formation is about five times that when O ₃ gas that does not radicalize oxygen is used. It was confirmed that a rate (speed) was obtained. It was also confirmed that the in-plane variation in film thickness was extremely small.

Next, an experiment was performed on the Si source. Here, a case of forming the SiO ₂ using BTBAS and _{O 2} gas plasma under the above conditions, the Si source from BTBAS Tri-DMAS - the SiO ₂ in exactly except that instead of the (tri (dimethylamino) silane) Similarly The case where the film was formed was compared.

  The result is shown in FIG. In FIG. 6, the film formation rate is standardized by assuming the film formation rate to be 1 when using Tri-DMAS. As shown in this figure, it was confirmed that when Tri-DMAS was used as the Si source, the film formation rate was about 2/3 lower than when BTBAS was used. This is presumed to be because when Tri-DMAS having 3 amino groups per molecule is used, structural damage is likely to occur compared to BTBAS having 2 amino groups.

Next, an experiment was performed on the film formation temperature.
Here, BTBAS was used as the Si source gas, O ₂ gas plasma was used for the oxidation treatment, and film formation was performed in the same manner as in the above experiment except for the film formation temperature. The experiment was conducted by changing the temperature to room temperature (25 ° C.), 75 ° C., 100 ° C., 200 ° C., and 300 ° C.

  The result is shown in FIG. In FIG. 7, the vertical axis represents the film formation rate normalized by setting the film formation rate at 300 ° C. to 1, and the in-plane uniformity normalized by setting the in-plane uniformity at 300 ° C. to 1. As shown in this figure, it was confirmed that a film can be formed at a high film formation rate even at a low temperature of 100 ° C. or lower, and that a sufficiently practical film formation is possible even at room temperature. Moreover, it was confirmed that the uniformity of the film thickness is high at a low temperature of 100 ° C. or lower. Moreover, when the film formation temperature exceeded 300 ° C., the variation in film thickness increased, and it was confirmed that the film formation temperature is preferably 300 ° C. or less.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the above-described embodiment, the present invention is applied to a batch-type film forming apparatus in which a plurality of semiconductor wafers are mounted and collectively formed. However, the present invention is not limited to this. The present invention can also be applied to a single-wafer type film forming apparatus for film formation. The aminosilane having two amino groups in one molecule is not limited to those shown in the above embodiment. In addition, various oxygen-containing gas plasmas are exemplified as the oxygen radicals, but the present invention is not limited to this, and any oxygen radicals that include radicalized oxygen are applicable.

Further, in the above embodiment, the Si source gas and the oxygen radical are supplied completely alternately. However, the oxygen radical may be supplied also when the Si source gas is supplied.
Furthermore, in the above-described embodiment, the example in which the mechanism for forming plasma is integrally incorporated in the processing container has been described. However, the present invention is not limited to this, and is provided separately from the processing container and previously converted into plasma outside the processing container. Alternatively, a remote plasma apparatus introduced into the processing vessel may be used.

  Furthermore, the object to be processed is not limited to a semiconductor wafer, and the present invention can be applied to other substrates such as an LCD glass substrate.

The present invention is suitable for forming a SiO ₂ film used for an interlayer insulating film or the like in a semiconductor device.

The longitudinal cross-sectional view which shows an example of the film-forming apparatus for enforcing the film-forming method of this invention. The cross-sectional view which shows an example of the film-forming apparatus for enforcing the film-forming method of this invention. 3 is a timing chart showing gas supply timing in the film forming method of the present invention. The schematic diagram for demonstrating reaction at the time of implementing the film-forming method of this invention. Diagram comparing the case of forming the SiO ₂ film, in the case of using the O ₃ gas in the oxidation treatment for comparison, the deposition rate and film thickness variation in accordance with the present invention. A case of forming the SiO ₂ film in accordance with the present invention, in the case of using TDMAS as SiO ₂ source for comparison, graph comparing the film forming rate. Diagram showing the relationship between the deposition temperature and the deposition rate and film thickness variation in the case where a SiO ₂ film in accordance with the present invention.

Explanation of symbols

1; Processing vessel 5; Wafer boat (supply means)
14; oxygen-containing gas supply mechanism 15; Si source gas supply mechanism 16; purge gas supply mechanism 19; oxygen-containing gas dispersion nozzle 22; Si source gas dispersion nozzle 30; plasma generation mechanism 33; plasma electrode 35; 100; Film forming apparatus W; Semiconductor wafer (object to be processed)

Claims (19)

The object to be processed is placed in a processing container capable of maintaining a vacuum, an aminosilane gas having two amino groups in one molecule is used as a Si source, oxygen radicals are used as an oxidizing agent, and these are alternately processed. A film forming method, wherein the film is supplied into a container and an SiO ₂ film is formed on a surface of an object to be processed.   2. The film forming method according to claim 1, wherein at least one selected from BTBAS (Bistaributylbutylaminosilane), BDEAS (Bisdiethylaminosilane), and BDMAS (Bisdimethylaminosilane) is used as the Si source gas. .   The film forming method according to claim 1, wherein oxygen-containing gas plasma is used as the oxygen radical. The oxygen-containing gas plasma is obtained by converting at least one selected from O ₂ gas, NO gas, N ₂ O gas, H ₂ O gas, and O ₃ gas into plasma. The film-forming method of description.   5. The film forming method according to claim 1, wherein the step of supplying the Si source into the processing container and the step of supplying the oxygen radical into the processing container are alternately performed.   Inserting a step of removing the gas remaining in the processing vessel between the step of supplying the Si source into the processing vessel and the step of supplying the oxygen radicals into the processing vessel. The film forming method according to claim 5, wherein the film forming method is characterized in that:   The film forming method according to claim 6, wherein in the step of removing the gas remaining in the processing container, a purge gas is introduced into the processing container while evacuating the processing container.   The film forming method according to claim 1, wherein a temperature during film formation is 300 ° C. or lower.   The film forming method according to claim 8, wherein a temperature during film formation is 100 ° C. or lower. A film forming apparatus for forming a SiO ₂ film on an object to be processed,
A vertical processing container that can be held in a vacuum and has a cylindrical shape;
A holding member that holds the object to be processed in a plurality of stages in the processing container;
A heating device provided on the outer periphery of the processing vessel;
A Si source supply mechanism for supplying an aminosilane gas having two amino groups in one molecule into the processing container;
An oxygen-containing gas supply mechanism for supplying an oxygen-containing gas into the processing vessel;
An activation mechanism for activating the oxygen-containing gas to form oxygen radicals;
A film forming apparatus comprising: a control mechanism that alternately supplies the Si source gas and oxygen radicals into the processing container.   The film forming apparatus according to claim 10, wherein the activation mechanism is a plasma generation mechanism that generates an oxygen-containing gas plasma. The oxygen-containing gas plasma generated by the plasma generation mechanism is obtained by converting at least one selected from O ₂ gas, NO gas, N ₂ O gas, H ₂ O gas, and O ₃ gas into plasma. The film forming apparatus according to claim 11, wherein the film forming apparatus is characterized in that   The control mechanism performs control so that the step of supplying the Si source gas into the processing container and the step of supplying oxygen radicals into the processing container are alternately performed. The film forming apparatus according to claim 12.   The control mechanism is a step of removing gas remaining in the processing container between the step of supplying the Si source into the processing container and the step of supplying the oxygen radicals into the processing container. The film forming apparatus according to claim 13, wherein the film forming apparatus is controlled to be inserted.   15. The apparatus according to claim 14, further comprising a purge gas supply mechanism for supplying a purge gas into the processing container, wherein the control mechanism supplies the purge gas into the processing container in the step of removing the gas. The film-forming apparatus of description.   The film forming apparatus according to claim 10, further comprising a temperature control mechanism that controls the film forming temperature to 300 ° C. or lower.   The film forming apparatus according to claim 16, wherein the temperature control mechanism controls the film forming temperature to 100 ° C. or less.   18. The method according to claim 10, wherein the Si source gas is at least one selected from BTBAS (Bisthal Butylaminosilane), BDEAS (Bisdiethylaminosilane), and BDMAS (Bisdimethylaminosilane). The film forming apparatus according to claim 1. A computer-readable storage medium storing a control program that runs on a computer,
10. The computer-readable storage, wherein the control program causes a computer to control the film forming apparatus so that the film forming method according to claim 1 is performed at the time of execution. Medium.

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