KR101232970B1 - Heat processing method and apparatus for semiconductor process, and computer readable medium - Google Patents

Abstract

In the heat treatment method for semiconductor processing, a plurality of substrates to be processed are stored in a stacked state at intervals in a processing region of a processing container. The substrate to be processed has a layer to be treated on its surface. Next, the oxidizing gas and the reducing gas are reacted by supplying the oxidizing gas and the reducing gas to the processing region and heating the processing region to generate oxygen active species and hydroxyl active species, and oxygen active species and hydroxyl active species are used. Oxidation is performed on the layer to be processed on the substrate to be processed. Next, annealing is performed on the layer to be treated by heating the layer to be treated after oxidation in an atmosphere of an annealing gas composed of ozone or an oxidative active species.

Description

Heat treatment method and apparatus for semiconductor processing and computer readable media {HEAT PROCESSING METHOD AND APPARATUS FOR SEMICONDUCTOR PROCESS, AND COMPUTER READABLE MEDIUM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method and apparatus for semiconductor processing that performs heat treatment for forming an oxide film or an oxynitride film on a substrate to be processed, such as a semiconductor wafer. Herein, semiconductor processing means a semiconductor layer, an insulating layer, a conductive layer, or the like on a substrate to be processed, such as a semiconductor wafer or a glass substrate for a flat panel display (FPD) such as an LCD (Liquid Crystal Display). By forming, it means the various processes performed in order to manufacture the structure containing a semiconductor device, the wiring connected to a semiconductor device, an electrode, etc. on the said to-be-processed substrate.

In general, in order to manufacture a semiconductor integrated circuit, various processes such as film formation, etching, oxidation, diffusion, and modification are performed on a semiconductor substrate made of a silicon wafer or the like. For example, oxidation may include oxidation of the surface of a single crystal silicon film or polysilicon film, oxidation of a metal film, or the like. In particular, the silicon oxide film formed by oxidation is applied to insulating films such as device isolation films, gate oxide films, and capacitors.

As a method of performing the oxidation treatment, there are an atmospheric pressure oxidation treatment method performed in a processing vessel under an atmosphere substantially equivalent to atmospheric pressure and a reduced pressure oxidation treatment method performed in a processing vessel under a vacuum atmosphere from the viewpoint of pressure. Moreover, from the viewpoint of the kind of gas used for oxidation, the wet oxidation processing method which produces | generates steam by burning hydrogen and oxygen in an external combustion apparatus, and oxidizes using this steam, for example, Unexamined-Japanese-Patent Application Japanese Patent Laid-Open No. 3-140453 (Patent Document 1). Further, there is a dry oxidation treatment method (for example, Japanese Patent Application Laid-Open No. 57-1232 (Patent Document 2)) in which only ozone or only oxygen flows into the processing vessel and oxidizes without using water vapor.

Thus, as the oxidation method, there are dry oxidation using oxygen gas and wet oxidation using water vapor. Generally, the oxide film formed by wet oxidation has a better film quality than the oxide film formed by dry oxidation. That is, as the insulating film, in consideration of film quality characteristics such as pressure resistance, corrosion resistance, and reliability, the wet oxide film is better. In addition, the film formation rate of the oxide film (insulating film) formed and the uniformity in the wafer plane are also important factors. From this point of view, in general, the film formed by wet oxidation at atmospheric pressure has a high oxidation rate but is inferior in in-plane uniformity of the film thickness. On the other hand, the film formed by wet oxidation under reduced pressure, on the other hand, has a small oxidation rate but is excellent in in-plane uniformity of film thickness.

When the design rules of a semiconductor device or a semiconductor integrated circuit are not very strict, various oxidation methods as described above are used in consideration of the use, process conditions, device cost, etc. to which the oxide film is applied. However, in recent years, line widths and film thicknesses of semiconductor devices have become smaller, and design rules have become strict. Accordingly, a higher demand is required for the characteristics of the film quality of the oxide film, the in-plane uniformity of the film thickness, and the like. For this reason, there arises a problem that the conventional oxidation method cannot sufficiently meet this demand.

Japanese Patent Application Laid-Open No. 4-18727 (Patent Document 3) discloses an oxidation apparatus using an example of a wet oxidation treatment method. In this apparatus, H ₂ gas and O ₂ gas are introduced separately at the lower end in the vertical quartz reaction tube, and are burned in a combustion section disposed in the quartz cap to generate water vapor. An oxidation process is performed while raising this water vapor along the arrangement direction of the wafer. In this case, since the H ₂ gas is to be combusted in the combustion section, water vapor is excessive at the lower end of the processing vessel in the vicinity. In addition, as water vapor rises, it is consumed, and conversely, there is a tendency of water vapor depletion at the upper end of the processing vessel. For this reason, the thickness of the oxide film formed on the wafer surface may vary greatly depending on the support position of the wafer in the wafer boat, and the inter-plane uniformity of the oxide film thickness may deteriorate.

In the apparatus of Japanese Patent Application Laid-Open No. 57-1232 (Patent Document 2), a horizontal batch reaction tube in which a plurality of semiconductor wafers are arranged and used is used. O ₂ gas is introduced from one end of the reaction tube, or O ₂ gas and H ₂ gas are simultaneously introduced to form an oxide film under a reduced pressure atmosphere. In the case of this apparatus, however, the film is formed under a relatively high pressure atmosphere by using a hydrogen combustion oxidation method, so that the water vapor component becomes the main agent of the reaction. For this reason, as mentioned above, there exists a possibility that the density | concentration difference of the water vapor between the upstream and downstream of the gas flow in a process container may become large too much, and the interplanar uniformity of the thickness of an oxide film may deteriorate.

Another oxidizing device is disclosed in US Patent Application No. 6037273 (Patent Document 4). In this apparatus, oxygen gas and hydrogen gas are supplied into a single wafer process chamber by lamp heating. Both gases are reacted in the vicinity of the surface of the semiconductor wafer provided in the process chamber to generate water vapor, and the water vapor is oxidized to form an oxide film.

However, in this apparatus, oxygen gas and hydrogen gas are introduced into the process chamber from a gas inlet spaced about 20 to 30 mm from the wafer, and the oxygen gas and hydrogen gas are reacted in the vicinity of the semiconductor wafer surface to generate water vapor. Let's do it. In addition, since the processing pressure is also performed in a relatively high region, there is a fear that the in-plane uniformity of the film thickness is inferior.

Japanese Patent Application Laid-Open No. 2002-176052 (Patent Document 5) discloses another oxidation method. In this method, an oxidizing gas such as O ₂ and a reducing gas such as H ₂ are simultaneously supplied to the processing chamber and reacted under vacuum atmosphere to form an atmosphere mainly composed of oxygen active species and hydroxyl active species, and in this atmosphere. Oxide the silicon wafer or the like.

Japanese Patent Application Laid-Open No. 2000-183055 (Patent Document 6) discloses a method of forming an oxynitride film (SiON film) having good film quality as an insulating film other than an oxide film. In this method, for example, a SiON film is formed by subjecting SiO ₂ formed as described above to nitriding with ammonia, nitrogen monoxide (NO), dinitrogen monoxide (N ₂ O), or the like. In order to remove the excessive N component after this nitriding treatment, reoxidation treatment is performed by O ₂ gas or the like.

An object of the present invention is to provide a heat treatment method and apparatus for semiconductor processing that can form an oxide film or an oxynitride film having good electrical properties.

A first time point of the present invention is a heat treatment method for forming an oxide film in a semiconductor process, the process of storing a plurality of substrates to be processed in a stacked state in a processing region of a processing container, and the substrates to be treated Having an object layer on the surface and supplying an oxidizing gas and a reducing gas to the processing region, and heating the processing region to react the oxidizing gas and the reducing gas to generate oxygen active species and hydroxyl active species, and generate the oxygen Oxidizing the layer to be treated on the substrate using active species and the hydroxyl active species; and heating the layer to be treated after the oxidation in an atmosphere of an annealing gas composed of ozone or an oxidative active species. A step of annealing is provided.

A second time point of the present invention is a heat treatment method for forming an oxynitride film in a semiconductor process, the method comprising: accommodating a plurality of substrates to be treated having a layer to be treated on a surface thereof in a state in which they are stacked at intervals in a processing region of a processing container; And supplying an oxidizing gas and a reducing gas to the processing region, and heating the processing region to react the oxidizing gas and the reducing gas to generate oxygen active species and hydroxyl active species, and generate the oxygen active species and the hydroxyl activity. A step of oxidizing the layer to be treated on the substrate to be treated using a species, a step of nitriding the layer to be treated by heating the layer after the oxidation in an atmosphere of a nitride gas, and the treatment after the nitriding Annealing gas consisting of ozone or oxidative active species The process of annealing with respect to the said process target layer is heated by heating in the atmosphere of the process.

A third viewpoint of the present invention is a heat treatment apparatus for semiconductor processing, the processing container having a processing region for accommodating a plurality of substrates in a stacked state at intervals, and disposed around the processing container to heat the processing region. A heater, an exhaust system for exhausting the processing region, an oxidizing gas supply system for supplying an oxidizing gas to the processing region, a reducing gas supply system for supplying a reducing gas to the processing region, and ozone or oxidizing property to the processing region. An anneal gas supply system for supplying an anneal gas composed of active species is provided.

A fourth aspect of the present invention is a computer-readable medium containing program instructions for executing on a processor, wherein the program instructions, when executed by a processor, perform a heat treatment method by controlling a heat treatment apparatus for semiconductor processing. The process of accommodating a several to-be-processed board | substrate which has a process target layer on the surface in the state laminated | stacked in the process area | region of the processing container at the surface, supplying an oxidizing gas and a reducing gas to the said process area, and heating the said process area | region Thereby reacting the oxidizing gas and the reducing gas to generate oxygen active species and hydroxyl active species, and oxidizing the layer to be treated on the substrate to be treated using the oxygen active species and the hydroxyl active species; The treatment zone consists of ozone or oxidative active species At the same time supplying a carbonyl gas, heating the treatment zone, by heating the above process layer after oxidation in the atmosphere of the annealing gas comprises a step of carrying out annealing for the process layer.

According to the present invention, it is possible to provide a heat treatment method and apparatus for semiconductor processing that can form an oxide film or an oxynitride film having good electrical properties.

1 is a block diagram showing a vertical heat treatment apparatus according to a first embodiment of the present invention.
Fig. 2 is a flowchart showing an example of forming a SiO ₂ film by the heat treatment method according to the first embodiment.
3 is a graph showing the annealing dependence of the SILC characteristics of the silicon oxide film obtained by the experiment according to the first embodiment.
Fig. 4 is a graph showing the annealing dependence of the TDDB characteristics of the silicon oxide film obtained by the experiment according to the first embodiment.
5 is a block diagram showing a vertical heat treatment apparatus according to a second embodiment of the present invention.
Fig. 6 is a flowchart showing an example of forming a SiON film by the heat treatment method according to the second embodiment.
Fig. 7 is a graph showing the annealing dependence of the TDDB properties of silicon oxynitride films obtained by the experiment according to the second embodiment.

The present inventors studied the problems of the prior art regarding the method of forming the oxide film or the oxynitride film by heat treatment in the semiconductor processing in the course of the development of the present invention. As a result, the present inventors obtained the knowledge as described below.

For example, according to the heat treatment method disclosed in the patent documents 1 to 6, an oxide film having a relatively good film quality can be formed, and in-plane uniformity of the film thickness of the oxide film can also be maintained relatively high. In recent years, however, several problems have been found in view of the fact that the characteristics required for insulating films used in semiconductor devices are becoming strict. For example, electrical characteristics such as a silicon induced leak current (SILC) characteristic and a time dependent direct break-down (TDDB) characteristic cannot sufficiently meet the demands that are being strict in the prior art. Moreover, SILC characteristic shows the leakage current at the time of using a silicon oxide film as a gate insulating film. The TDDB characteristic represents the amount of charge injected until breakdown when a constant current flows through a transistor using a silicon oxide film, and appears as a displacement amount of a gate voltage. According to the experiment, it is estimated that the degradation of these characteristics is caused by the residual of hydrogen in the insulating film.

EMBODIMENT OF THE INVENTION Below, embodiment of this invention comprised based on such knowledge is demonstrated with reference to drawings. In addition, in the following description, the component which has substantially the same function and structure is attached | subjected with the same code | symbol, and duplication description is performed only when necessary.

<1st embodiment>

1 is a block diagram showing a vertical heat treatment apparatus according to a first embodiment of the present invention. As shown in the drawing, this processing apparatus 2 has a vertical processing container 4 having a cylindrical shape with an open lower end, and houses a plurality of semiconductor wafers (substrates) stacked at intervals therein. Processing area 5 to be processed is defined. The processing vessel 4 is formed of a heat resistant material, for example quartz.

An exhaust port 6 is arranged at the ceiling of the processing container 4, and an exhaust line 8 that is bent in the transverse direction at right angles, for example, is continuously provided at the exhaust port 6. A vacuum exhaust system 14 provided with a pressure control valve 10, a vacuum pump 12, or the like is connected to the exhaust line 8, so that the atmosphere in the processing container 4 can be evacuated.

A manifold 16 formed into a cylindrical shape is connected to the opening of the lower end of the processing container 4 via a seal member 20 such as an O-ring for maintaining airtightness. Moreover, the whole manifold 16 can also be comprised by the cylindrical processing container made from the cylinder shape, without providing it separately. The manifold 16 consists of stainless steel, for example, and supports the lower end part of the processing container 4. The wafer boat 18 made of quartz is lifted and lowered through the lower end opening of the manifold 16, thereby loading / unloading the wafer boat 18 with respect to the processing container 4. In the wafer boat 18, a plurality of semiconductor wafers W are stacked in multiple stages as a substrate to be processed. For example, in the case of this embodiment, the wafer W 18 can support the wafer W which is 300 mm in diameter about 50 sheets in multiple steps at substantially equal intervals, for example.

The wafer boat 18 is mounted on the table 24 via a quartz insulating tube 22. The table 24 is supported at the upper end of the rotating shaft 28 through the lid 26 for opening and closing the lower end opening of the manifold 16. The magnetic fluid seal 30 is interposed in the penetrating portion of the rotary shaft 28 of the lid 26, for example, to rotatably support the rotary shaft 28 while hermetically sealing it. At the periphery of the lid 26 and the lower end of the manifold 16, a sealing member 32 made of an O-ring or the like for maintaining airtightness is interposed.

The rotating shaft 28 is provided in the front-end | tip part of the arm 36 supported by the lifting mechanism 34, such as a boat elevator, for example. By the lifting mechanism 34, the wafer boat 18, the lid 26, and the like are raised and lowered integrally. In addition, the table 24 may be fixed and disposed on the lid 26 side, and the wafer W may be processed without rotating the wafer boat 18.

A carbon wire heater 38 is disposed on the side of the processing container 4 so as to surround it, and the atmosphere in the processing container 4 and the semiconductor wafer W are heated. A carbon wire heater can realize a clean process, and is excellent in the temperature rising temperature characteristic. In addition, the heat insulating material 40 is arrange | positioned in the outer periphery of this heater 38 in order to ensure thermal stability.

The manifold 16 is arranged with various gas supply systems for introducing and supplying various gases into the processing vessel 4. Specifically, the manifold 16 includes an oxidizing gas supply system 42 for supplying an oxidizing gas to the processing region 5, a reducing gas supply system 44 for supplying a reducing gas to the processing region 5, and The ozone supply system 46 which supplies ozone to the process area 5 is connected, respectively. The manifold 16 is also connected to a purge gas supply system (not shown) that supplies, for example, N ₂ gas as a purge gas. The two gas supply systems 42 and 44 penetrate the side walls of the manifold 16, and the oxidizing gas injection nozzles 48 and the reducing gas injection nozzles 50 whose front ends are inserted into and faced with the processing vessel 4 are disposed. ) Each.

In the gas passages 52 and 54 extending from the respective injection nozzles 48 and 50, the on / off valves 56 and 58 and the flow rate controllers 60 and 62 such as the mass flow controller are interposed therebetween. By controlling the open / close valves 56 and 58 and the flow rate controllers 60 and 62, respectively, it is possible to control the start and stop of the supply of each gas and the gas flow rate. Here, as an example, O ₂ gas is used as the oxidizing gas, H ₂ gas is used as the reducing gas, and each gas is supplied to the lower portion of the processing container 4.

The ozone supply system 46 has an ozone injection nozzle 64 which penetrates the side wall of the manifold 16 and inserts its front end into the processing vessel 4 and faces it. In the gas passage 66 extending from the ozone injection nozzle 64, an on / off valve 68, a flow controller 70 such as a mass flow controller, and an ozone generator 72 are sequentially provided. Therefore, ozone may be generated from O _{2 as} necessary and supplied to the lower portion of the processing container 4 while controlling the flow rate.

The whole operation of the processing apparatus 2 configured as described above is controlled by the control means 74 made of, for example, a computer. The program of the computer which performs this operation is stored in a storage unit 76 including a storage medium such as a floppy, a CD (Compact Disc), a hard disk, or a flash memory. Specifically, by the command from the control means 74, the start / stop of the supply of each gas (including the ozone), the control of the gas flow rate, the processing temperature, the processing pressure, and the like are performed.

In addition, although the single pipe | tube structure is shown as a structure of the processing container 4 here, it is not limited to this, You may use the processing container of the double pipe | tube structure which consists of an inner pipe and an external appearance. In addition, the shape of the nozzle of each gas (including ozone) is not limited to what was shown in figure. For example, you may arrange | position a large number of injection holes in the pipe | tube extended in the height direction of the wafer boat 18, and may make it spray each gas uniformly to each area of the height direction of the wafer boat 18. FIG.

Next, a heat treatment method according to the first embodiment performed using the processing apparatus 2 configured as described above will be described with reference to FIG. 2 as well. 2 is a flowchart showing an example of forming an SiO ₂ film by the heat treatment method according to the first embodiment. 2 shows a case where an SiO ₂ film is formed as an insulating film on the surface of a semiconductor wafer by oxidation.

That is, in this processing method, first, an oxide film is formed by oxidizing the surface of the semiconductor wafer W in an atmosphere having oxygen active species and hydroxyl active species generated by reacting the oxidizing gas and the reducing gas in the processing region 5 ( Oxidation process S1). Next, the oxide film is annealed by heating in an atmosphere of an active species of ozone or oxidizing gas (annealing step S2). These steps are sequentially performed in the same treatment region 5 to form an SiO ₂ film containing less hydrogen components in the film.

Specifically, when the processing apparatus 2 is in the standby state in which the semiconductor wafer W made of, for example, a silicon wafer is not loaded, the processing region 5 is maintained at a temperature lower than the processing temperature. In the process, first, a plurality of semiconductor wafers W at room temperature, for example, 50 sheets, are held in the wafer boat 18 in multiple stages at predetermined intervals. The wafer boat 18 is driven upward by driving the boat elevator 34 to be inserted into the processing container 4 in a hot wall state from below, and the wafer boat 18 is disposed in the processing region 5. In addition, the inside of the processing container 4 is sealed by closing the opening of the lower end of the manifold 16 with the lid 26.

Next, the inside of the processing container 4 is evacuated by the vacuum exhaust system 14 to maintain the processing region 5 at a predetermined processing pressure. In addition, by increasing the supply power to the heater 38, the wafer temperature is raised to raise the processing region 5 to the processing temperature for oxidation treatment. After the temperature of the processing region 5 is stabilized, the oxidizing gas injection nozzles 48 of the respective gas supply systems 42 and 44 while controlling the flow rate of the predetermined processing gas, that is, the O ₂ gas and the H ₂ gas, required to perform the oxidation process. And the reducing gas injection nozzle 50 are supplied to the processing region 5, respectively. At this point, ozone has not been supplied yet.

Both gases react under vacuum atmosphere while raising the treatment region 5 to generate hydroxyl active species and oxygen active species. The hydroxyl active species and the oxygen active species come into contact with the wafer W accommodated in the rotating wafer boat 18, and oxidation treatment is performed on the wafer surface (step S1). The processing gas or the gas generated by the reaction is exhausted out of the system from the exhaust port 6 of the ceiling of the processing vessel 4.

At this time, the H ₂ gas flow rate is set in the range of 200 to 5000 sccm, for example, 600 sccm. The O ₂ gas flow rate is set in the range of 200 to 10000 sccm, for example 1200 sccm. The treatment temperature is set in the range of 500 to 1200 ° C, for example 900 ° C. The processing pressure is set in the range of 0.02 Torr (2.7 kPa) to 3.0 Torr (400 kPa), for example, 0.35 Torr (46 kPa). In addition, a processing time is set to 10 minutes, for example.

The O ₂ gas and the H ₂ gas introduced into the processing vessel 4, respectively, are raised by the combustion reaction of hydrogen in the immediate vicinity of the wafer W while raising the processing region 5 in the processing vessel 4 in a hot wall state. An atmosphere mainly composed of oxygen active species (O ^* ) and hydroxyl active species (OH ^* ) is generated. These active species oxidize the surface of the wafer W to form an SiO ₂ film. At this time, the formation process of the active species is as follows. In other words, by introducing hydrogen and oxygen into the processing vessel 4 in a hot wall state under a reduced pressure atmosphere, the following combustion reaction of hydrogen proceeds in the immediate vicinity of the wafer W. In the following formulae, chemical symbols with * denote the active species.

H ₂ + O ₂ → H ^* + HO ₂

O ₂ + H ^* → OH ^* + O ^*

H ₂ + O ^* → H ^* + OH ^*

H ₂ + OH ^* → H ^* + H ₂ O

As such, when H ₂ and O ₂ are introduced into the treatment region 5, O ^* (oxygen active species), OH ^* (hydroxyl active species) and H ₂ O (water vapor) are generated during the combustion reaction of hydrogen. Then, the wafer surface is oxidized to form a SiO ₂ film. At this time, in particular, it is determined that both active species of O ^* and OH ^* act greatly.

Since the SiO ₂ film formed as described above uses hydrogen as the reducing gas, the hydrogen component is contained in the film, and as a result, the electrical film quality characteristics are lowered. For this reason, in order to remove a hydrogen component from a film | membrane, an annealing process in ozone atmosphere is performed next (step S2).

First, the supply of the O ₂ gas and the H ₂ gas is stopped, and at the same time, the ozone supply system 46 is operated to generate ozone (O ₃ ) from the ozone generator 72. The ozone is introduced into the processing container 4 while controlling the flow rate, and the inside of the processing container 4 is made into an ozone atmosphere, and the wafer W is heated and annealed in this ozone atmosphere.

At this time, the processing pressure is in the range of 0.1 Torr (13.3 kPa) to 76 Torr (10130 kPa), preferably 0.1 Torr (13.3 kPa) to 10 Torr (1330 kPa), for example, 0.35 Torr (47 kPa). Is set to). If the processing pressure is lower than 0.1 Torr (13.3 kPa), the annealing effect is insufficient. If the treatment pressure is higher than 76 Torr (10130 kPa), the activity of ozone is extremely lost. The treatment temperature is set in the range of 500 to 1200 ° C, preferably 300 to 1000 ° C. If the treatment temperature is lower than 500 ° C., the effect of annealing is insufficient. If the treatment temperature is higher than 1200 ° C, there is a fear that adversely affect the heat resistance of the device itself. In particular, in order to improve the throughput by reducing the time required for the elevated temperature of the wafer temperature, it is preferable to set the temperature of this annealing process to be the same as the processing temperature in the oxidation process. Here, the processing temperature of the annealing process is set to the same as the oxidation process, for example, 900 ° C.

In the annealing process, the concentration of ozone [O ₃ / (O ₃ + O ₂ )] in the treatment region 5 takes into account the cost-effectiveness of the concentration of ozone on the function and annealing characteristics of the current ozone generator. , 5 to 20% by volume. However, since the annealing characteristic can be improved as the concentration of ozone is higher, for example, a concentration close to 100% by volume may be used. In the embodiment, the flow rate of ozone is set in a range of 0.1 to 10 slm, the concentration of ozone _{[O 3 / (O 3 +} O 2)] is set to 10% by volume.

Here, by performing an annealing treatment in an atmosphere of ozone, which is why the hydrogen component removed from among SiO ₂ film is assumed as follows. In other words, it is considered that the oxygen-activated species generated by decomposition of ozone reacts with the hydrogen component in the SiO ₂ film and is released from the film in the state of OH or H ₂ O.

<Evaluation result>

An SiO ₂ film was formed by the film forming method according to the first embodiment, and the electrical film quality characteristics thereof were measured and evaluated. 3 is a graph showing annealing dependence of SILC characteristics of a silicon oxide film. The definition of SILC characteristics is as described above. The SILC characteristic shown in FIG. 3 shows the leakage current at the charge of 5 [C / cm 2].

Fig. 3 also shows the results of the SiO ₂ films of various comparative examples A1 to A4 formed by other film formation methods. In Comparative Example A1, a SiO ₂ film was formed by dry oxidation. In Comparative Example A2, a SiO ₂ film was formed by wet oxidation. In Comparative Example A3, the SiO ₂ film was formed only by the oxidation treatment in the apparatus shown in FIG. 1 (no ozone annealing). In Comparative Example A4, a SiO ₂ film was formed in the apparatus shown in FIG. 1 and annealed in an N ₂ atmosphere (1000 ° C.). In Example B1, a SiO ₂ film was formed by the method according to the first embodiment and annealed in an ozone atmosphere (500 ° C.).

As shown in Fig. 3, the leakage current of Comparative Example A1, which is a SiO ₂ film by dry oxidation, was the most at about 0.3 10 ⁻⁷ (A / cm 2), and the film quality was not particularly good. In Comparative Examples A2 to A4, the leakage current was slightly smaller than that of Comparative Example A1, which was about 1 × 10 ⁻⁸ (A / cm 2), but not sufficiently small. In particular, even when annealed at 1000 ° C. as shown in Comparative Example A4, a sufficient effect was not obtained in the N ₂ gas atmosphere.

On the other hand, in the case of the SiO ₂ film | membrane by the method which concerns on Example 1 shown in Example B1, even if it anneals at 500 degreeC in ozone atmosphere, a leak current falls to about 0.5 * 10 <^-8> (A / cm <2>). It became. This significantly reduced leakage current compared with Comparative Examples A1 to A4, and confirmed that good film quality characteristics could be obtained.

4 is a graph showing annealing dependence of the TDDB characteristic of a silicon oxide film. The definition of the TDDB characteristic is as described above. Here, CCS (Constant Current Stress) was set to -0.1 A / cm <2>. 4 shows Comparative Examples A3 and A4 and Example B1 of the method according to the first embodiment as a representative.

As shown in Fig. 4, in the case of Comparative Examples A3 and A4, the gate voltage Vg dropped very rapidly with the passage of time, which was not so preferable. On the other hand, in the case of the method according to the first embodiment of Example B1, the gate voltage Vg did not decrease so much over time, and the film quality characteristics maintained good results. In other words, it was confirmed that the variation in the gate voltage Vg was small and the hole trap amount and the electron trap amount could be greatly reduced. In addition, there is currently no method of directly measuring the amount of the hydrogen component in the film, but can be indirectly recognized by the SILC characteristic or the TDDB characteristic as described above.

&Lt; Second Embodiment >

5 is a configuration diagram showing a vertical heat treatment apparatus according to a second embodiment of the present invention. 6 is a flowchart showing an example of forming a SiON film by the heat treatment method according to the second embodiment.

The heat treatment apparatus shown in FIG. 5 has a structure similar to that of the heat treatment apparatus shown in FIG. 1, but differs in that a nitriding gas supply system 80 for supplying nitriding gas into the processing container is further disposed. With this structure, in this heat treatment apparatus, as described below, the SiO ₂ film can be nitrided to form a SiON film.

Specifically, the nitriding gas supply system 80 has a nitriding gas injection nozzle 82 which penetrates the side wall of the manifold 16, inserts the front end part into the processing container 4, and faces it. In the gas passage 84 extending from the nitriding gas injection nozzle 82, a flow controller 88 such as an on-off valve 86 and a mass flow controller is sequentially provided. Therefore, the nitriding gas can be supplied to the lower part of the processing container 4 as needed, while controlling the flow rate.

In this embodiment, NH ₃ is used as the nitride gas. However, as this nitriding gas, one or more gases selected from the group consisting of NO, N ₂ O, and NH ₃ can be used.

In the case of the heat treatment apparatus of 2nd Embodiment, as shown in the flowchart of FIG. 6, the nitriding process shown by step S1-1 is performed between the oxidation process of step S1 and the annealing process of step S2. Because of this, and supplies the processing region (5), while the flow control nitriding gas by the step at S1 after the formation of SiO ₂ film, H ₂ gas and O to stop the supply of the _second gas, nitriding gas supply system 80. The As a result, the SiO ₂ film, which is an oxide film formed on the surface of the wafer W, is nitrided with a nitride gas to form a SiON film, which is an oxynitride film.

At this time, the processing pressure is in the range of 100 to 760 Torr, and is set to, for example, 650 Torr. Treatment temperature is set in the range of 500-1200 degreeC. The flow rate of the nitriding gas is set in the range of 0.1 to 10 slm.

After forming a SiON film by the above-mentioned process, as shown in step S2 of FIG. 6, the annealing process is performed similarly to the process demonstrated by step S2 in FIG. 2, and a hydrogen component is removed from a SiON film.

Process conditions, such as the process pressure, process temperature, and ozone flow volume in step S2 (anneal process) in FIG. 6, can be made the same as that of step S2 in FIG. However, the process condition of step S2 in FIG. 6 may be different from that of step S2 in FIG.

Also in 2nd Embodiment, in order to improve a throughput, it is preferable to set all the oxidation process of step S1, the nitriding process of step S1-1, and the annealing process of step S2 to the same process temperature. Here, the treatment temperature of the nitriding step and the annealing step is set to the same as the oxidation step, for example, 900 ° C.

The reason why the hydrogen component is removed from the SiON film by annealing in the atmosphere of ozone is the same as that described for the SiO ₂ film.

<Evaluation result>

A SiON film was formed by the film-forming method which concerns on the said 2nd Embodiment, and the electrical film quality characteristic was measured and evaluated. Fig. 7 is a graph showing the annealing dependence of the TDDB characteristics of the silicon oxynitride film. Here, CCS was set to -0.1 A / cm <2>.

7 also shows the results of various SiON films of Comparative Examples A5 to A7 formed by other film formation methods. In Comparative Example A5, after formation of the SiON film, reoxidation treatment was performed at 900 ° C. in an O ₂ gas atmosphere. In Comparative Example A6, no annealing was performed after the formation of the SiON film. In Comparative Example A7, annealing was performed in N ₂ gas atmosphere (900 ° C.) after formation of the SiON film. In Example B2, a SiON film was formed by the method according to the second embodiment and annealed in an ozone atmosphere (600 ° C). In Example B3, a SiON film was formed by the method according to the second embodiment and annealed in an ozone atmosphere (900 ° C).

As shown in Fig. 7, in the case of Comparative Examples A5 to A7, the gate voltage Vg was very decreased with the passage of time, which was not preferable. The degree of deterioration was getting worse in the order of Comparative Examples A5 to A7. In contrast, in the case of the method according to the second embodiment of Examples B2 and B3, the gate voltage Vg did not decrease so much over time, and the film quality characteristics were maintained with good results. That is, it was confirmed that the variation in the gate voltage Vg was small and the hole trap amount and the electron trap amount could be greatly reduced. In Example B3 having an annealing temperature of 900 ° C., the lowering of the gate voltage Vg is smaller than that of Example B2 having an annealing temperature of 600 ° C., and therefore, a higher annealing temperature can maintain better film quality characteristics. Could know.

<Common Items Common to First and Second Embodiments>

In the said embodiment, an annealing process is performed in ozone atmosphere. Instead of this, you may perform an annealing process in the atmosphere of the active species of the oxidizing gas containing no hydrogen component. As this oxidizing gas, O ₂ , NO, NO ₂ gas can be used. In this case, in order to generate the active species of the oxidizing gas, for example, the plasma excitation mechanism disclosed in US 7,300, 885 B2, the teachings of which are hereby incorporated by reference can be used. This plasma excitation mechanism has a pair of electrodes to which a high frequency voltage is applied along the side of the vertical processing vessel. By this plasma excitation mechanism, the oxidative gas can be converted into plasma to generate oxidative active species. Instead of this, a so-called remote plasma excitation mechanism can be used, which forms an oxidative active species by plasma outside the processing vessel and introduces the active species into the processing vessel.

In the above embodiment, O ₂ gas is used as the oxidizing gas. In this regard, the oxidizing gas may use one or more gases selected from the group consisting of O ₂ , N ₂ O, NO, NO _2, and O ₃ .

In the above embodiment, H ₂ gas is used as the reducing gas. In this regard, the reducing gas may use at least one gas selected from the group consisting of H ₂ , NH ₃ , CH ₄ , HCl and deuterium.

When O ₃ (ozone) is used as the oxidizing gas, the oxidizing gas supply system 42 can also serve as an ozone supply system, and thus the ozone supply system 46 can be omitted from the heat treatment apparatus 2 of FIG. . In the case where the same gas as the oxidizing gas and the nitriding gas is used, for example, NO and NO ₂ , the oxidizing gas supply system 42 can also be used as the nitriding gas supply system. 80 may be omitted.

In the said embodiment, it performs in the same process container from an oxidation process to an annealing process. Instead of this, each process may be performed in another processing container (processing apparatus). The material to be oxidized is not limited to silicon, but may be another semiconductor material, an oxide film, or an oxynitride film. As the substrate to be treated, instead of a semiconductor wafer, a glass substrate, an LCD substrate, a ceramic substrate, or the like can be used.

2: processing unit
4: Processing vessel
5: processing area
6: exhaust port
8: exhaust line
10: pressure control valve
12: vacuum pump
14: vacuum exhaust system
16: manifold
18: wafer boat
20, 32: seal member
W: Wafer

Claims (11)

It is a heat treatment method for forming an oxide film in a semiconductor process,
Accommodating a plurality of substrates to be processed having a layer to be treated on the surface in a stacked state at intervals in a processing region of the processing container;
While supplying an oxidizing gas and a reducing gas to the processing region, heating the processing region to react the oxidizing gas and the reducing gas to generate an oxygen active species and a hydroxyl active species, and the oxygen active species and the hydroxyl active species. Oxidizing the layer to be treated on the substrate to be treated using
And a step of annealing said layer to be treated by heating said layer to be treated after said oxidation in an atmosphere of an annealing gas consisting of only ozone or an oxidative active species. The heat treatment method according to claim 1, wherein the annealing is performed in the processing region by supplying the anneal gas to the processing region and heating the processing region. The heat treatment method for semiconductor processing according to claim 1, wherein the anneal gas is ozone. The method of claim 3, wherein the annealing uses a processing temperature of 500 to 1200 ° C. and a processing pressure of 0.1 Torr (13.3 kPa) to 76 Torr (10130 kPa). The method of claim 1, wherein the oxidizing gas comprises at least one gas selected from the group consisting of O ₂ and N ₂ O, NO and NO ₂ and O ₃ , the reducing gas is H ₂ and NH ₃ and CH ₄ and A heat treatment method for semiconductor processing comprising at least one gas selected from the group consisting of HCl and deuterium. The heat treatment method for semiconductor processing according to claim 5, wherein the oxidation uses a processing temperature of 500 to 1200 ° C and a processing pressure of 0.02 Torr (2.7 kPa) to 3.0 Torr (400 kPa). The heat treatment method for semiconductor processing according to claim 1, wherein the processing target layer comprises silicon. A processing container having a processing area for storing a plurality of substrates to be processed in a stacked state at intervals;
A heater disposed around the processing container to heat the processing region;
An exhaust system for exhausting the processing region;
An oxidizing gas supply system for supplying an oxidizing gas to the processing region;
A reducing gas supply system for supplying a reducing gas to the processing region;
And a anneal gas supply system for supplying an anneal gas consisting of only ozone or oxidative active species to the processing region. The heat treatment apparatus for semiconductor processing according to claim 8, further comprising a nitride gas supply system for supplying a nitride gas to the processing region. A computer readable medium containing program instructions for executing on a processor,
When the program instruction is executed by a processor, the heat treatment apparatus for semiconductor processing is controlled to execute a heat treatment method.
Accommodating a plurality of substrates to be processed having a layer to be treated on the surface in a stacked state at intervals in a processing region of the processing container;
While supplying an oxidizing gas and a reducing gas to the processing region, heating the processing region to react the oxidizing gas and the reducing gas to generate an oxygen active species and a hydroxyl active species, and the oxygen active species and the hydroxyl active species. Oxidizing the layer to be treated on the substrate to be treated using
Supplying an anneal gas consisting of only ozone or oxidative active species to the treatment region, and heating the treatment region, and heating the treatment target layer after the oxidation in an atmosphere of the anneal gas to anneal the treatment target layer. Computer-readable medium provided. The said target object layer of Claim 10 by supplying a nitride gas to the said process area | region after the said oxidation and before annealing, and heating the said process area | region, and heating the said process target layer after the said oxidation in the atmosphere of a nitride gas. A computer-readable medium, further comprising a step of nitriding the fluoride.

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