JP2017022233A - Vertical type thermal treatment apparatus and operational method for vertical type thermal treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve uniformity of film thickness between substrates when performing deposition processing by carrying a holder holding a plurality of substrates in a shelf state into a reaction vessel and supplying a process gas into a reaction tube.SOLUTION: The apparatus comprises: a gas supply part for supplying a deposition gas into the reaction vessel; and gas distribution adjustment members which are provided to be positioned higher and lower than an arrangement region of the plurality of substrates to be processed held by the substrate holder. The gas distribution adjustment member includes a first tabular member and a second tabular member which are provided lower than a top plate of the substrate holder and higher than a bottom plate of the substrate holder and for each of which ruggedness is formed. The first tabular member has a first surface area, and the second tabular member has a second surface area that is different from the first surface area.SELECTED DRAWING: Figure 14

Description

  The present invention relates to a vertical heat treatment apparatus that performs a film formation process on a plurality of substrates at once and a method for operating the vertical heat treatment apparatus.

  In general, in order to manufacture a semiconductor product, a film processing such as ALD (Atomic Layer Deposition) or CVD (Chemical Vapor Deposition) is performed on a semiconductor wafer made of a silicon substrate or the like (hereinafter referred to as a wafer). . This film forming process may be performed by a batch type vertical heat treatment apparatus that processes a plurality of wafers at the same time. In this case, the wafers are transferred to a vertical wafer boat, and the wafer boat is rack-shaped. To support in multiple stages. The wafer boat is loaded (loaded) from below into a evacuable reaction vessel (reaction tube). Thereafter, various gases are supplied into the reaction container while the reaction container is kept airtight, and the film formation process is performed on the wafer. As disclosed in Patent Document 1, a technique is known in which a wafer is placed on the wafer boat and the CVD is performed.

  Dummy wafers are held on the upper side and the lower side of the wafer boat, and a wafer that is a substrate to be processed for manufacturing the semiconductor product so as to be sandwiched between the dummy wafers from above and below (for convenience of description, described as a product wafer) The wafer boat is loaded into the reaction vessel as described above. The reason why the dummy wafer is held together with the product wafer in the wafer boat is that the gas flow in the processing vessel is made smooth and the temperature uniformity between the product wafers is increased, so that the product wafer is made highly uniform. The object is to prevent the particles from being placed on the product wafer when the film is formed or when particles are generated from the wafer boat made of quartz. Unlike the product wafer, the dummy wafer has no surface on which various films for forming the semiconductor product are formed, and therefore, no unevenness for forming wiring is formed. Hereinafter, this dummy wafer may be described as a bare wafer.

JP2008-47785

  By the way, miniaturization of a semiconductor product has progressed, and the surface area of the product wafer is gradually increasing as the irregularities are formed on the product wafer at a high density. For this reason, during the film forming process, the gas consumption in the product wafer is gradually increased with respect to the process gas consumption (reaction amount) in the bare wafer. Accordingly, with respect to the product wafers supported on the upper side and the lower side of the wafer boat, a relatively large amount of processing gas is supplied by placing a bare wafer with a low processing gas consumption near the product wafer. . However, for the product wafers supported on the middle stage of the wafer boat, the amount of processing gas consumed by the product wafers supported on the upper and lower sides is large, so that the amount of processing gas supplied per sheet is relatively small. As a result, there may be a large variation in film thickness formed by the processing gas between product wafers.

  In the prior art of Patent Document 1, in order to control the distribution of the processing gas, a dummy wafer made of silicon having a surface area substantially equal to that of a product wafer is mounted on a wafer boat and a film forming process is performed by CVD. In the above prior art, after the film formation, the dummy wafer is reused by immersing the dummy wafer in a hydrofluoric acid solution and removing the formed film. However, such a configuration requiring wet etching is disadvantageous because a dummy wafer must be transferred from the vertical heat treatment apparatus to another apparatus, which is troublesome.

  The present invention increases the uniformity of film thickness between substrates when carrying a film forming process by carrying a holding gas holding a plurality of substrates into a reaction container and supplying a processing gas into the reaction container. Provide technology to do.

In the vertical heat treatment apparatus of the present invention, a plurality of substrates to be processed having irregularities formed on the surface are heated by a heating unit while being held by a substrate holder in a vertical reaction container, and the substrate to be processed is heated. In the vertical heat treatment apparatus that performs the film formation process,
A gas supply unit for supplying a film forming gas into the reaction vessel;
A gas distribution adjusting member provided so as to be positioned above and below the arrangement region of the plurality of substrates to be processed held by the substrate holder,
The gas distribution adjusting member is provided above and below the top plate of the substrate holder and above the bottom plate of the substrate holder. A second plate-like member,
The first plate-like member has a first surface area, and the second plate-like member has a second surface area different from the first surface area.

  According to the present invention, the first plate member and the second member which are gas distribution adjusting members are positioned above and below the arrangement region of the plurality of substrates to be processed held by the substrate holder. A plate member is provided, and the first plate member and the second plate member have different surface areas. Accordingly, it is possible to finely adjust the amount of gas supplied to the upper and lower portions of the substrate holder, thereby increasing the uniformity of the film thickness formed between the substrates. When the gas distribution adjusting member is made of quartz, it is less likely to be etched by a cleaning gas which is a fluorine-based gas containing fluorine or a fluorine compound supplied into the reaction tube as compared with a case where the gas distribution adjusting member is made of silicon. Accordingly, since the gas distribution adjusting member can be cleaned together with the inside of the reaction tube by the gas, the labor of operation of the apparatus can be reduced.

It is a vertical side view of the vertical heat processing apparatus which concerns on the 1st Embodiment of this invention. It is a cross-sectional top view of the said vertical heat processing apparatus. It is a vertical side view of a product wafer. It is a timing chart of processing of the vertical heat treatment apparatus. It is explanatory drawing which shows a mode that it forms into a film on a product wafer in 1st Embodiment. It is explanatory drawing which shows a mode that it forms into a film on a product wafer in a comparative example. It is a graph which shows the film thickness distribution between the wafers processed with the said vertical heat processing apparatus. It is explanatory drawing which shows the example of arrangement | positioning of the product wafer in a wafer boat. It is a vertical side view of the vertical heat processing apparatus which concerns on 2nd Embodiment. It is a cross-sectional top view of the said vertical heat processing apparatus. It is a graph which shows the film thickness distribution between the wafers processed with the said vertical heat processing apparatus. It is a graph which shows the film thickness distribution between the wafers processed using the wafer boat which concerns on 3rd Embodiment. It is a graph which shows the film thickness distribution between the wafers processed using the wafer boat which concerns on 4th Embodiment. It is explanatory drawing which shows arrangement | positioning of each wafer in the wafer boat which concerns on 5th Embodiment. It is explanatory drawing which shows other arrangement | positioning of each wafer in the wafer boat which concerns on 5th Embodiment. It is explanatory drawing which shows other arrangement | positioning of each wafer in the wafer boat which concerns on 5th Embodiment. It is explanatory drawing which shows an example of schematic structure of the quartz wafer used in 5th Embodiment. It is explanatory drawing which shows the structure of the injector used by the evaluation test. It is a graph which shows the result of an evaluation test. It is a graph which shows the result of an evaluation test. It is a graph which shows the result of an evaluation test.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. 1 and 2 are a schematic longitudinal sectional view and a schematic transverse sectional view of a vertical heat treatment apparatus 1 according to the present invention. Reference numeral 11 in FIGS. 1 and 2 denotes a reaction tube forming a processing vessel formed of, for example, quartz in a vertical cylindrical shape. Further, a flange 12 is integrally formed at the peripheral edge of the lower end opening of the reaction tube 11, and a manifold 2 formed in a cylindrical shape with, for example, stainless steel is formed on the lower surface of the flange 12 such as an O-ring. It is connected via a seal member 21.

  The lower end of the manifold 2 is opened as a loading / unloading port (furnace port), and a flange 23 is formed integrally with a peripheral portion of the opening 22. Below the manifold 2, an opening 22 is hermetically closed on the lower surface of the flange 23 via a seal member 24 such as an O-ring. For example, a lid 25 made of quartz can be opened and closed by a boat elevator 26 in the vertical direction. Is provided. A rotation shaft 27 is provided through the central portion of the lid body 25, and a wafer boat 3 as a substrate holder is mounted on the upper end portion thereof via a stage 39.

An L-shaped first source gas supply pipe 40 is inserted in the side wall of the manifold 2, and at the tip of the first source gas supply pipe 40, as shown in FIG. Two first source gas supply nozzles 41 made of a quartz tube extending upward in the reaction tube 11 are arranged with an elongated opening 61 of a plasma generation unit 60 described later interposed therebetween. In these first source gas supply nozzles 41, 41, a plurality (a large number) of gas discharge holes 41a are formed at predetermined intervals along the length direction, and the gas discharge holes 41a, 41a Gas can be discharged substantially uniformly in the horizontal direction. Further, a supply source of a silane-based gas, for example, SiH ₂ Cl ₂ (dichlorosilane: DCS) gas, which is a first source gas, is provided on the base end side of the first source gas supply pipe 40 via a supply device group 42. 43 is connected.

Further, an L-shaped second source gas supply pipe 50 is inserted in the side wall of the manifold 2, and the reaction tube 11 is formed at the tip of the second source gas supply pipe 50. A second source gas supply nozzle 51 made of quartz is provided that extends upward and bends in the middle and is installed in a plasma generator 60 described later. In the second source gas supply nozzle 51, a plurality of (many) gas discharge holes 51a are formed at predetermined intervals along the length direction thereof, and are directed from the gas discharge holes 51a in the horizontal direction. The gas can be discharged almost uniformly. The base end side of the second source gas supply pipe 50 is branched into two, and one second source gas supply pipe 50 is supplied with ammonia as a second source gas through a supply device group 52. A supply source 53 of (NH ₃ ) gas is connected, and a supply source 55 of nitrogen (N ₂ ) gas is connected to the other second source gas supply pipe 50 via a supply device group 54.

Furthermore, one end of a cleaning gas supply pipe 45 is inserted in the side wall of the manifold 2. The other end of the cleaning gas supply pipe 45 branches and is connected to a gas supply source 48 of F ₂ (fluorine) gas and a gas supply source 49 of HF (hydrogen fluoride) via supply device groups 46 and 47, respectively. ing. As a result, a mixed gas of F ₂ and HF can be supplied into the reaction tube 11 as a cleaning gas. The cleaning gas is not limited to using such a fluorine gas or a gas containing hydrogen fluoride gas as a main component. For example, a gas containing another fluorine compound as a main component may be used. Each of the supply device groups 42, 46, 47, 52, 54 includes a valve and a flow rate adjusting unit.

  In addition, a plasma generation unit 60 is provided along a height direction of a part of the side wall of the reaction tube 11. The plasma generation unit 60 forms a vertically elongated opening 61 by scraping the side wall of the reaction tube 11 with a predetermined width along the vertical direction, and forms a recess in a cross section so as to cover the opening 61. The partition wall 62 made of, for example, quartz is vertically and vertically welded and joined to the outer wall of the reaction tube 11. A region surrounded by the partition wall 62 is a plasma generation region PS.

  The opening 61 is formed long enough in the vertical direction so as to cover all the wafers held in the wafer boat 3 in the height direction. A pair of elongated plasma electrodes 63 are provided on the outer side surfaces of both side walls of the partition wall 62 so as to face each other along the length direction (vertical direction). A high frequency power source 64 for generating plasma is connected to the plasma electrode 63 via a power supply line 65 so that plasma can be generated by applying a high frequency voltage of, for example, 13.56 MHz to the plasma electrode 63. It has become. An insulating protective cover 66 made of, for example, quartz is attached outside the partition wall 62 so as to cover the partition wall 62.

  The manifold 2 has an exhaust port 67 for evacuating the atmosphere in the reaction tube 11. Connected to the exhaust port 67 is a vacuum pump 68 serving as a vacuum exhaust means capable of evacuating the inside of the reaction tube 11 to a desired degree of vacuum, and an exhaust pipe 59 including a pressure adjusting unit 69 composed of, for example, a butterfly valve. As shown in FIG. 1, a cylindrical heater 28 is provided so as to surround the outer periphery of the reaction tube 11 and is a heating means for heating the reaction tube 11 and the wafer in the reaction tube 11.

  The vertical heat treatment apparatus 1 includes a control unit 100. The control unit 100 includes, for example, a computer, and is configured to control the boat elevator 26, the heater 28, the supply device groups 42, 46, 47, 52, 54, the high frequency power supply 64, the pressure adjustment unit 69, and the like. More specifically, the control unit 100 stores a sequence program for executing a series of processing steps to be described later performed in the reaction tube 11, reads out commands of each program, and outputs a control signal to each unit It has means to do. The program is stored in the control unit 100 while being stored in a storage medium such as a hard disk, a flexible disk, a compact disk, a magnetic optical disk (MO), or a memory card.

  Next, the wafer boat 3 will be further described. The wafer boat 3 is made of quartz, and includes a top plate 31 and a bottom plate 32 that are placed in parallel with each other during the film forming process. The top plate 31 and the bottom plate 32 are respectively provided at one end and the other end of three support columns 33 extending vertically. It is connected. Each column 33 is provided with support portions 34 (see FIG. 2) in multiple stages, and is configured so that the wafer can be held horizontally on the support portions 34. Accordingly, the wafers are held on the wafer boat 3 in a shelf shape in multiple stages. An area where the wafer is supported on each support portion 34 is referred to as a slot. In this example, 120 slots are provided. Each slot is represented by a number from 1 to 120, and the upper slot is assigned a smaller number.

  In the first embodiment, the wafer 10 and the wafer 71 are mounted in the slot. The wafer 10 is a product wafer for manufacturing a semiconductor product described in the section of the background art, and is constituted by, for example, a silicon substrate. As shown in FIG. 3, irregularities for forming wiring are formed on the surface of the wafer 10. In the figure, 35 is a polysilicon film, and 36 is a tungsten film. Reference numeral 37 denotes a recess formed in these films 35 and 36. Reference numeral 38 denotes a SiN film (silicon nitride film) formed by the vertical heat treatment apparatus 1.

  The wafer 71 is a wafer made of quartz (hereinafter referred to as a quartz wafer). The quartz wafer 71 is configured such that its outer shape in plan view matches the outer shape of the wafer 10 so that it can be placed on the wafer boat 3. In order to prevent breakage during handling, the thickness of the quartz wafer 71 is, for example, slightly larger than the thickness of the wafer 10, for example, 2 mm. The vertical side surface of the quartz wafer 71 is shown in an enlarged manner within the dotted circle shown at the tip of the dotted arrow in FIG. As shown here, unevenness is formed on the front and back surfaces of the quartz wafer 71. This unevenness is formed by, for example, laser processing or machining.

  Let S0 be the surface area per unit area obtained by dividing the surface area of the wafer 10 by the surface area calculated based on the external dimensions of the wafer 10. The surface area determined by the outer dimensions is an imaginary surface area that is determined by assuming that the surface of the wafer 10 is a flat surface without considering the concave portion 37 on the surface of the wafer 10. That is, a value obtained by dividing the actual surface area of the wafer 10 by the virtual surface area is the surface area S0 per unit region. The surface area of the wafer here is the area of the upper surface (front surface) of the wafer + the area of the lower surface (back surface). The surface area per unit region obtained by dividing the surface area of the quartz wafer 71 by the surface area calculated based on the external dimensions of the quartz wafer 71 is S. The surface area determined by the external dimensions of the quartz wafer 71 is the same as in the case of the wafer 10, and the surface and the back surface of the quartz wafer 71 are flat without considering the recesses formed on the surface and the back surface of the quartz wafer 71. This is a virtual surface area required to be a surface. In order to adjust the gas distribution in the vertical direction of the wafer boat 3 as described later, S / S0 is set to satisfy 0.06 ≦ S / S0, for example. In this example, the quartz wafer 71 is configured so that S / S0 = 0.6.

  For example, S / S0 is set to 0.06 ≦ S / S0. If S / S0 is smaller than 0.06, the gas consumed by the wafer 10 is excessive, and each wafer 10 using the quartz wafer 71 is used. This is because there is a concern that it is difficult to adjust the film thickness. As shown in FIG. 1, the quartz wafer 71 is held in a plurality of slots on the upper end side and the lower end side among the slots of the wafer boat 3. The wafer 10 is held in the slot where the quartz wafer 71 is not held. Accordingly, the group of wafers 10 is held on the wafer boat 3 so as to be sandwiched between the quartz wafers 71 from above and below. The quartz wafer 71 may be configured to be detachable from the wafer boat 3 in the same manner as the wafer 10 or may be fixed. The wafer 10 is transferred to the wafer boat 3 by a transfer mechanism (not shown). When the quartz wafer 71 is configured to be detachable from the wafer boat 3, the quartz wafer 71 is transferred in the same manner as the wafer 10 by this transfer mechanism, for example. In this example, it is assumed that the quartz wafer 71 is fixed to the wafer boat 3 because it is easy to handle.

  Subsequently, a film forming process performed in the vertical heat treatment apparatus 1 will be described. First, the wafer boat 3 on which the group of wafers 10 is placed so as to be sandwiched between the quartz wafers 71 as described above is raised into the reaction tube 11 set in advance at a predetermined temperature from below and loaded ( The reaction tube 11 is sealed by closing the lower end opening 22 of the manifold 2 with the lid 25.

  Then, the inside of the reaction tube 11 is evacuated by the vacuum pump 68 so that the inside of the reaction tube 11 has a predetermined degree of vacuum. Next, the pressure in the reaction tube 11 is set to, for example, 665.5 Pa (5 Torr), and DCS gas and N 2 gas are supplied into the reaction tube 11 from the first source gas supply nozzle 41 at a flow rate of, for example, 1000 sccm and 2000 sccm, for 3 seconds, for example. The high frequency power supply 64 is supplied in the off state, and the molecules of the DCS gas are adsorbed on the surface of the wafer 10 held in a shelf shape on the rotating wafer boat 3 (step S1).

Thereafter, the supply of DCS gas is stopped, the N ₂ gas is continuously supplied into the reaction tube 11 and the pressure in the reaction tube 11 is set to 120 Pa (0.9 Torr), for example, to purge the reaction tube 11 with N 2 (step) S2). Next, the pressure in the reaction tube 11 is set to, for example, 54 Pa (0.4 Torr), and NH ₃ gas and N ₂ gas are supplied into the reaction tube 11 from the second source gas supply nozzle 51 at flow rates of, for example, 5000 sccm and 2000 sccm, respectively. For example, the high-frequency power supply 64 is supplied for 20 seconds with the power on (step S3). As a result, active species such as N radicals, H radicals, NH radicals, NH ₂ radicals, and NH ₃ radicals react with the molecules of the DCS gas to produce the SiN film 38 shown in FIG.

Thereafter, the supply of NH ₃ gas is stopped, N ₂ gas is continuously supplied into the reaction tube 11, and the pressure in the reaction tube 11 is set to 106 Pa (0.8 Torr), for example, and the reaction tube 11 is purged with N ₂ . (Step S4). FIG. 4 is a timing chart showing the timing of supplying each gas and the timing of turning on the high frequency power supply 64. As shown in this chart, by repeating the above steps S1 to S4 a plurality of times, for example, 200 times, a thin film of the SiN film 38 is laminated and grown on the surface of the wafer 10 one by one. A SiN film 38 having a thickness is formed.

  The state of the wafer 10 and the quartz wafer 71 when the DCS gas is supplied during the film forming process will be described with reference to the schematic diagram of FIG. In the figure, 70 is a molecule of DCS gas. In the middle stage of the wafer boat 3, the wafers 10 having a large surface area are formed in multiple stages by forming irregularities on the surface thereof, and the molecules 70 supplied to the middle stage of the wafer boat 3 are consumed by these wafers 10. (Adsorption). In this way, the molecules 70 are consumed so as to be distributed with high uniformity among the wafers 10, and the amount of adsorption of the molecules 70 per wafer 10 is suppressed from being excessive.

  As for the wafers 10 held at the upper and lower stages of the wafer boat 3, the wafer 10 having a large surface area, that is, the quartz wafer 71 is present in the vicinity thereof, like the wafer 10 held at the middle stage. Therefore, the molecules 70 supplied to the upper and lower stages of the wafer boat 3 are consumed so as to be distributed with high uniformity between the wafer 10 and the quartz wafer 71. That is, since the surface area is large, the amount of adsorption of the molecules 70 on the quartz wafer 71 is relatively large. Therefore, the supply of excess molecules 70 to the wafer 10 is suppressed, and the adsorption of molecules 70 per wafer 10 is absorbed. An excessive amount is suppressed.

  For comparison with FIG. 5, the schematic diagram of FIG. 6 is shown. FIG. 6 shows a case where the bare wafer 72 described in the section of the background art is placed in place of the quartz wafer 71 in each slot where the quartz wafer 71 described above is placed and processing is performed. 70 shows how 70 adsorbs. As described above, the bare wafer 72 is made of, for example, silicon and has a small surface area because no irregularities for device formation are formed on the surface thereof. Even when the bare wafer 72 is arranged, in the middle stage of the wafer boat 3, as described with reference to FIG. 5, the molecules 70 are distributed to the wafers 10, and the amount of adsorption to the wafers 10 per sheet is suppressed. However, the wafer 10 held on the upper and lower stages of the wafer boat 3 has a bare wafer 72 in the vicinity thereof, and the bare wafer 72 is consumed by the bare wafer 72 because the adsorption amount of the molecules 70 is small because the surface area is small. Surplus molecules 70 that cannot be absorbed are adsorbed to the wafer 10.

As described with reference to FIGS. 5 and 6, by holding the quartz wafer 71 on the wafer boat 3, it is possible to prevent the molecules 70 from being excessively adsorbed on the upper and lower wafers 10 of the wafer boat. The molecules 70 are adsorbed with high uniformity. The example in which the molecules 70 of the DCS gas are adsorbed has been described. However, by holding the quartz wafer 71 on the wafer boat 3, radicals generated from the NH ₃ gas and the N ₂ gas also pass between the molecules 70 between the wafers 10. As well as high uniformity. The supplied radical reacts with the molecule 70.

As described above, steps S1 to S4 are repeated 200 times to complete the process, and then the wafer boat 3 is unloaded from the reaction tube 11. After the processed wafer 10 is taken out from the wafer boat 3, the wafer boat 3 is loaded again into the reaction tube 11 and the opening 22 is closed. The inside of the reaction tube 11 is evacuated and set to a predetermined pressure, and the temperature is set to 350 ° C., for example. Then, the cleaning gas composed of F ₂ and HF described above is supplied into the reaction tube 11. As a result, the SiN film 38 formed on the reaction tube 11, the wafer boat 3 and the quartz wafer 71 is etched and removed from the reaction tube 11 on the exhaust flow. Thereafter, the supply of the cleaning gas is stopped, and the wafer boat 3 is unloaded from the reaction tube 11. Thereafter, the succeeding wafer 10 is mounted on the wafer boat 3, and a film forming process is performed on the succeeding wafer 10 according to the above steps S <b> 1 to S <b> 4.

  FIG. 7 shows a graph showing the relationship between the film thickness of the wafer 10 and the slot position. The horizontal axis of the graph corresponds to the film thickness of the wafer 10, and the vertical axis corresponds to the slot position. The wafer boat 3 is shown with slot numbers so that the vertical axis of the graph corresponds to its height. A graph indicated by a dotted line is data obtained based on an experiment. As described with reference to FIG. 6, as described in FIG. The film thickness distribution of the wafer 10 is shown. For the reasons described above with reference to FIG. 6, the film thickness of the wafer 10 gradually increases from the middle slot of the boat 3 toward the upper and lower slots. The difference in film thickness between the slot 10 and the wafer 10 is relatively large. That is, there is a large variation in film thickness between slots. Note that the wafer boat 3 in FIG. 7 shows a state in which not the bare wafer 72 but the quartz wafer 71 is held according to the embodiment.

  The solid line graph in FIG. 7 is a graph assumed when the processing is performed with the quartz wafer 71 arranged, as described with reference to FIGS. 1 to 5, and shows the effect of the first embodiment. For the reason described with reference to FIG. 5, the quartz wafer 71 suppresses excessive gas supply to the wafer 10 on the upper side and the lower side of the wafer boat 3, so that the upper and lower sides of the wafer boat 3 are displayed as shown in the graph. An increase in the film thickness of the wafer 10 can be suppressed. As a result, the uniformity of the film thickness of the wafer 10 can be increased between the slots.

  Further, it is considered that as the surface area of the quartz wafer 71 is increased, the gas supply to the wafers 10 on the upper side and the lower side of the wafer boat 3 can be suppressed. 7 is a graph of the film thickness distribution assumed when the surface area of the quartz wafer 71 is larger than the surface area of the wafer 10. In accordance with the surface area of the wafer 10, the surface area of the quartz wafer 71 is determined so as to have an appropriate film thickness distribution. Even if only one quartz wafer 71 is provided on each of the upper and lower portions of the wafer boat 3, the gas distribution of the wafer 10 can be adjusted as described above. However, it is preferable to provide a plurality of sheets from the viewpoint of controlling the temperature distribution between the wafers 10.

  Further, since the quartz wafer 71 is made of quartz, corrosion due to the cleaning gas, which is a gas made of the above-described fluorine gas or fluorine compound, can be suppressed as compared with a wafer made of Si. Therefore, it can be repeatedly used for the film formation process as described above. Moreover, since it is not necessary to carry to the apparatus which performs wet etching in order to perform cleaning, the operation | work effort of an apparatus can be held down.

  Incidentally, there are cases where a relatively small number of wafers 10 are held in the wafer boat 3 for processing. In that case, for example, as shown in FIG. To explain, the wafer 10 is held in the middle slot. In the example of FIG. 8, the wafers 10 are continuously placed in slots whose numbers are around 35 to 60. Then, for example, a plurality of the quartz wafers 71 are held in the upper and lower slots, respectively. In the example shown in FIG. 8, about five quartz wafers 71 are held above and below the slot where the wafer 10 is held.

  The bare wafer 72 is held in the upper slots and the lower slots of the wafer boat 3 so as to sandwich the quartz wafer 71 group and the wafer 10 group. The bare wafer 72 is mounted in order to prevent the gas flow in the reaction tube 11 from being disturbed and the temperature distribution in the wafer 10 from being disturbed. As described above, any of the wafer 10, the quartz wafer 71, and the bare wafer 72 is held in the slots 1 to 120.

  FIG. 8 also shows a graph showing the film thickness distribution as in FIG. The solid line graph indicates the film thickness distribution of the wafer 10 assumed when the quartz wafer 71 is mounted on the wafer boat 3 and the wafer 10 is processed as described above. The dotted line graph shows the film thickness distribution of the wafer 10 when the slot in which the quartz wafer 71 is held in the above description is processed by holding the bare wafer 72 instead of the quartz wafer 71. As illustrated in the graph of FIG. 8, even when processing a small number of wafers 10, the quartz wafer 71 is mounted on the wafer boat 3 as described above. Thus, it is possible to prevent the film thickness of the upper wafer 10 and the lower wafer 10 from increasing in the wafer 10 group mounted on the wafer boat 3. As a result, the uniformity of the film thickness between the wafers 10 can be increased.

(Second Embodiment)
As described with reference to FIG. 5, if there are members having a relatively large surface area above and below the wafer 10 group mounted on the wafer boat 3, the gas supply amount on the upper side and the lower side in the wafer 10 group is reduced. Thus, the film thickness distribution between the wafers 10 can be adjusted. Therefore, the adjustment member for adjusting such a gas distribution is not limited to the quartz wafer 71. 9 and 10 show a vertical side view and a transverse plan view of the vertical heat treatment apparatus 1 according to the second embodiment, respectively. The vertical heat treatment apparatus 1 of the second embodiment is different in the configuration of the reaction tube 11 of the first embodiment, and the other parts are configured in the same manner. 9 and 10, some of the members described in the first embodiment are omitted.

  In the vertical heat treatment apparatus 1 of the second embodiment, the surface area of the upper region 81 including the ceiling surface of the reaction tube 11 and the upper peripheral surface, and the lower region 82 that is the lower peripheral surface of the reaction tube 11 is determined. Concavities and convexities are formed to increase the height. These upper region 81 and lower region 82 are the inner peripheral surfaces of the reaction tube 11. The lower region 82 includes a region below the group of wafers 10 placed on the wafer boat 3 when the wafer boat 3 is stored in the reaction tube 11. The unevenness of the upper region 81 and the lower region 82 is formed by, for example, sandblasting or chemical treatment. When processed by sandblasting, the arithmetic average roughness Ra is, for example, 0.4 to 4.0 μm, and when chemical processing is performed, the arithmetic average roughness Ra is 0.3 to 4.0 μm. Even in the quartz wafer 71 of the first embodiment, the unevenness may be formed by such sandblasting or chemical treatment. Further, like the quartz wafer 71, the unevenness may be formed in the reaction tube 11 by laser processing.

  By forming such roughness (unevenness), the upper region 81 and the lower region 82 play a role of adjusting the gas supply distribution in the same manner as the quartz wafer 71 of the first embodiment. Therefore, regarding the upper region 81 and the lower region 82, assuming that the surface area per unit region is S, the relationship with the surface area S0 per unit region of the wafer 10 is, for example, 0.06 ≦ similarly to the first embodiment. The unevenness is formed so as to be S / S0. The surface area of the upper region 81 and the lower region 82 is the surface area of the surface facing the processing space to which the gas is supplied. As an example, the surface area S per unit region of the upper region 81 will be described more specifically. The upper region 81 has the same area A as that of the region surrounded by the outer shape of the wafer 10 as having no irregularities. Suppose you cut it like you have it. When the surface area of the surface facing the processing space in the reaction tube 11 is B, the S is B / A. The surface area B is a surface area measured as having unevenness. S in the lower region 82 is calculated in the same manner.

  A region sandwiched between the upper region 81 and the lower region 82 on the inner peripheral side surface of the reaction tube 11 is referred to as an intermediate region 83. The intermediate region 83 is located on the outer periphery of the group of wafers 10 when the wafer boat 3 is loaded into the reaction tube 11. The intermediate region 83 is configured as a smooth surface without being subjected to the above sandblasting and chemical treatment. That is, the roughness of the intermediate region 83 is smaller than that of the upper region 81 and the lower region 82.

  Also in the vertical heat treatment apparatus 1 of the second embodiment, the film forming process and the cleaning process are performed as in the first embodiment. Since the inner peripheral surface of the reaction tube 11 is rough as described above, the gas supplied to the upper side and the lower side of the wafer boat 3 during the film forming process is consumed in the upper region 81 and the lower region 82. Is done. As a result, as in the first embodiment, it is possible to prevent an excessive supply of gas to the wafers 10 held on the upper side and the lower side of the wafer boat 3. Thus, since the upper region 81 and the lower region 82 of the reaction tube 11 play the same role as the quartz wafer 71 of the first embodiment, in this example, the wafer boat 3 is different from the first embodiment in the quartz. Instead of the wafer 71, a bare wafer 72 is detachably held with respect to the wafer boat 3. That is, the group of wafers 10 is held so that the top and bottom are sandwiched between the bare wafers 72. Unlike the case of using the quartz wafer 71, the bare wafer 72 is removed from the boat 3 during the cleaning process.

  FIG. 11 shows the film thickness distribution of the wafer 10 in each slot as in FIG. The dotted line graph in the figure shows the film thickness distribution of the wafer 10 when processing is performed without forming the above-described roughness in the reaction tube 11. The solid line graph in the figure is the assumed film thickness distribution between the wafers 10 when processing is performed by forming roughness in the upper region 81 and the lower region 82 as described above. As illustrated in the graph, by forming the roughness in the reaction tube 11, the wafer 10 on the upper side and the lower side of the group of wafers 10 held by the boat 3 as in the first embodiment. It is possible to prevent excessive gas supply to the wafer 10 and to increase the uniformity of the film thickness between the wafers 10.

  The region that forms roughness on the upper side of the wafer 10 group of the reaction tube 11 may be only one of the ceiling surface and the side peripheral surface. Further, the region below the group of wafers 10 in the reaction tube 11 is not limited to the formation of roughness on the side peripheral surface, and the surface of the bottom plate of the reaction tube 11, that is, the lid 25 may be formed. .

(Third embodiment)
In the third embodiment, the vertical heat treatment apparatus 1 similar to that in the first embodiment is used, and for example, the roughness described in the second embodiment is not formed on the inner surface of the reaction tube 11. Instead, the surfaces of the top plate 31 and the bottom plate 32 of the wafer boat 3 are roughened in the same manner as the upper region 81 and the lower region 82 of the reaction tube 11 described in the second embodiment, and the surface area S per unit region, The surface area S0 per unit area of the wafer 10 is set to 0.06 ≦ S / S0, for example. FIG. 12 shows the wafer boat 3 in which the roughness is formed as described above. For example, as in the second embodiment, the wafer 10 and the bare wafer 72 are mounted on the wafer boat 3 and a film forming process is performed. During the film forming process, the top plate 31 and the bottom plate 32 include the quartz wafer 71 described in the first embodiment and the upper region 81 and the lower region 82 of the reaction tube 11 described in the second embodiment. Playing the same role, the film thickness distribution between the wafers 10 is adjusted.

  The surface area S per unit area of the top plate 31 of the wafer boat 3 will be described in detail. The top plate 31 has the same area A as the area of the region surrounded by the outer shape of the wafer 10 as having no irregularities. If you cut it to have When the surface area of the surface facing the processing space in the reaction tube 11 is B, the S is B / A. Since the top plate 31 faces both the upper and lower surfaces in the processing space, the surface area B is the sum of the surface areas of the upper and lower surfaces. The surface area S per unit area of the bottom plate 32 of the boat 3 is similarly calculated, but the lower surface of the bottom plate 32 is covered with a stage 39 (see FIG. 1) that supports the wafer boat 3 and does not face the processing space. Therefore, the surface area B is the surface area of the upper surface.

  The graph of FIG. 12 shows the relationship between the slot of the wafer 10 and the film thickness as in the graphs of the other drawings. A dotted line graph shows the film thickness distribution between the wafers 10 when the top plate 31 and the bottom plate 32 are processed without being roughened. A solid line graph is a film thickness distribution between the wafers 10 assumed when the processing is performed by the wafer boat 3 having the roughness.

(Fourth embodiment)
In the fourth embodiment, the same vertical heat treatment apparatus 1 as that in the first embodiment is used, and the wafer boat 3 is configured in the same manner as in the first embodiment. In the fourth embodiment, wafers 10 and bare wafers 76 are held on the wafer boat 3. The shape of the bare wafer 76 is the same as that of the bare wafer 72 but is made of quartz instead of Si. When the surface area S per unit region is determined for the bare wafer 76 as in the first embodiment, the relationship with the surface area S0 per unit region of the wafer 10 is S / S0 <1.0.

  As shown in FIG. 13, the slots in which the wafers 10 and 76 are mounted are different from those in the second and third embodiments. In the same manner as in the second and third embodiments, the bare wafer 76 is mounted in a plurality of slots at the upper end and a plurality of slots at the lower end of the wafer boat 3, and is mounted in a slot having a consecutive number in the middle stage of the wafer boat 3. Is done. In the example of FIG. 13, the bare wafer 76 is mounted continuously from the 50th slot to the slot near the 60th. The wafer 10 is placed in the slot where the bare wafer 76 is not placed.

  In the fourth embodiment, the film forming process and the cleaning process are performed as in the other embodiments. During this film forming process, since a plurality of bare wafers 76 are mounted on the middle stage of the boat 3, gas consumption is reduced in the vicinity of the middle stage. Accordingly, the amount of gas supplied to the wafer 10 placed in a slot close to the slot on which the bare wafer 76 is mounted increases.

  The dotted line graph in FIG. 13 shows the film thickness distribution of the wafer 10 when the bare wafer 76 is mounted only on the upper and lower parts of the wafer boat 3 and the film forming process is performed. The solid line graph shows the film thickness distribution of the wafer 10 that is assumed when the processing is performed with the bare wafer 76 placed in the middle part of the wafer boat as described above. As shown in each graph, when the bare wafer 76 is arranged in the middle stage portion, the gas consumption in the middle stage portion is suppressed as described above, so the film thickness increases from the upper and lower stages of the wafer boat 3 toward the middle stage. After decreasing, it rises. With such a distribution, variations in film thickness can be suppressed as compared with the case where the bare wafer 76 is not disposed in the middle stage.

  As described above, since the bare wafer 76 is made of quartz, it is carried into the reaction tube 11 together with the wafer boat 3 and cleaned during the cleaning process, as in the first embodiment. Similarly to the quartz wafer 71 of the first embodiment, the bare wafer 76 may be fixed to the wafer boat 3 or may be detachable. In order to sufficiently improve the gas supply distribution, a plurality of bare wafers 76 which are plate-like members between the substrates to be processed are provided continuously in the middle stage of the wafer boat 3, but only one may be provided.

  This fourth embodiment is combined with other embodiments. Specifically, in FIG. 13 described above, the wafers loaded in the plurality of slots at the upper and lower ends of the wafer boat 3 are the bare wafers 76. However, when combined with the first embodiment, the bare wafers 76 are replaced. For example, a quartz wafer 71 is mounted and processing is performed. Further, as shown in the second embodiment, the wafer boat 3 loaded with the wafers 10 and 76 is loaded into the reaction tube 11 whose inner surface is roughened as shown in FIG. 13, and processing is performed. Further, as described in the third embodiment, the wafers 10 and 76 are arranged on the wafer boat 3 having the rough top plate 31 and bottom plate 32 as shown in FIG. That is, a member having a relatively large surface area for adjusting the gas distribution, in which one or a plurality of bare wafers 76 are arranged between the wafers 10 as described above, and is composed of quartz above and below the wafers 10. The processing is performed in a state where is arranged.

  The vertical heat treatment apparatus 1 is configured to perform ALD, but the present invention can be applied to a batch type processing apparatus that supplies a gas to form a film. Therefore, the present invention can also be applied to a vertical heat treatment apparatus that performs CVD. In addition, the above embodiments can be implemented in combination with each other. For example, in the first embodiment, the processing may be performed using the reaction tube 11 in which roughness is formed as described in the second embodiment. In the first to third embodiments, the fourth embodiment may be applied, and the bare wafer 76 may be disposed between the wafer 10 group and the wafer 10 group. In the second and third embodiments, a process may be performed by mounting a bare wafer 76 instead of the bare wafer 72.

  By the way, the wafer 10 is processed differently for each lot, and when the wafer 10 is mounted on the wafer boat 3 in a state where the line width of the pattern and the film thickness on which the unevenness is formed are different, that is, in the vertical heat treatment apparatus 1. Consider a case where the surface area of the wafer 10 is different for each lot to be transferred. In this case, for example, a plurality of types of quartz wafers 71 according to the first embodiment that are detachable from the boat 3 and have different surface areas are prepared. Then, a quartz wafer 71 to be mounted on the wafer boat 3 may be selected from the plurality of types according to the lot of the wafers 10 to be processed by the vertical heat treatment apparatus 1. Accordingly, the amount of gas supplied to the wafers 10 on the upper side and the lower side of the wafer boat 3 can be controlled for each lot of the wafers 10, and the film thickness of the wafers 10 can be made more uniform between the slots. can do.

(Fifth embodiment)
The fifth embodiment will be described with reference to FIG. 14, which shows the arrangement of the wafers in the wafer boat 3 with a focus on differences from the first embodiment. In the fifth embodiment, quartz wafers 71 are arranged in a plurality of slots on the upper end side and a plurality of slots on the lower end side among the slots of the wafer boat 3 as in the first embodiment. Then, the wafer 10 is placed in the slot where the quartz wafer 71 is not placed, and a film forming process is performed. However, as these quartz wafers 71, a quartz wafer (referred to as 71A) having a first surface area and a quartz wafer (referred to as 71B) having a second surface area different from the first surface area are used. Yes. For example, the quartz wafers 71 </ b> A and 71 </ b> B are configured to be detachable from the wafer boat 3. Similarly to the quartz wafer 71 of the first embodiment, assuming that the surface area S per unit area of the quartz wafer 71 and the surface area S0 per unit area of the wafer 10 are 0.06 ≦ the quartz wafers 71A and 71B, respectively. It is configured to be S / S0.

  In FIG. 14, quartz wafers 71 </ b> A and 71 </ b> B viewed in plan are schematically shown at the tip of each arrow. For example, the quartz wafers 71A and 71B have the same outer shape when viewed in plan. That is, the quartz wafers 71A and 71B have the same area and thickness in plan view. In FIG. 14, reference numeral 70 denotes a groove formed on the surface of the quartz wafers 71A and 71B. The quartz wafer 71A has a larger number of grooves 70 than the quartz wafer 71B, whereby the surface area of the quartz wafer 71A is larger than the surface area of the quartz wafer 71B. In this example, as compared with the surface area of the bare wafer 72 whose outer shape is the same as that of the quartz wafers 71A and 71B, the quartz wafer 71A has a surface area 30 times larger and the quartz wafer 71B has a surface area 10 times larger. .

  FIG. 14 shows a state in which the quartz wafer 71A is disposed in the plurality of slots on the lower end side and the quartz wafer 71B is disposed in the plurality of slots on the upper end side. By arranging in this way, the uniformity of the film thickness distribution of each wafer 10 can be made higher than arranging the quartz wafers 71A in a plurality of slots on the upper end side and the lower end side as shown in an evaluation test described later. it can. This is because if the quartz wafer 71A is also placed in the slot where the quartz wafer 71B is placed and a film forming process is performed, a large amount of processing gas (film forming gas) is consumed in the quartz wafer 71A. This makes it difficult for the processing gas to reach the central portion of the wafer boat 3 that is relatively far from the quartz wafer 71A, and the film thickness of the wafer 10 at the central portion of the height decreases as shown in an evaluation test described later. End up. That is, by using the quartz wafers 71A and 71B together, the amount of the processing gas supplied to each wafer 10 is finely controlled, and the height of the wafer boat 3 that is relatively far away from each of the quartz wafers 71A and 71B. This prevents the amount of processing gas supplied to the center from greatly decreasing. Thereby, the uniformity of the film thickness between the wafers 10 is improved.

  In the example shown in FIG. 14, a quartz wafer 71 </ b> A having a relatively large surface area is disposed on the lower side of the wafer boat 3, and a quartz wafer 71 </ b> B having a relatively small surface area is disposed on the upper side of the wafer boat 3. The reason why the quartz wafer 71 having a relatively large surface area is arranged on the lower side of the wafer boat 3 is described below in detail below the reaction tube 11 into which the wafer boat 3 is loaded as shown in FIG. Since the exhaust port 67 is opened below the wafer boat 3, the concentration of the film forming gas on the lower side tends to be higher than that on the upper side of the wafer boat 3. This is because a large amount of film forming gas is adsorbed. By adsorbing more film forming gas on the lower side in this way, the film thickness uniformity between the wafers W can be further increased. However, the quartz wafer 71A may be arranged on the lower side of the wafer boat 3 and the quartz wafer 71B may be arranged on the upper side of the wafer boat 3, respectively. When the exhaust port 67 is opened on the upper side of the reaction tube 12, more More specifically, for example, when the exhaust port 67 is opened above the wafer boat 3, it is effective to arrange such quartz wafers 71A and 71B.

  Further, as shown in FIG. 15, the film forming process may be performed by placing quartz wafers 71 </ b> A and 71 </ b> B on the lower side and the upper side of the region where the wafer 10 is placed in the wafer boat 3. In the example shown in FIG. 15, in a plurality of slots on the upper side of the wafer boat 3, the quartz wafer 71A is disposed on the upper side and the quartz wafer 71B is disposed on the lower side. In the lower slot of the wafer boat 3, the quartz wafer 71A is disposed on the lower side, and the quartz wafer 71B is disposed on the upper side. The reason for this arrangement is that if the quartz wafer 71A having a large surface area and the wafer 10 are arranged close to each other, a large amount of processing gas is adsorbed to the quartz wafer 71A and supplied to the wafer 10. This is because the amount of the processing gas becomes extremely small and the film thickness of the wafer 10 may be reduced.

  Further, in the arrangement example shown in FIG. 14, the quartz wafer 71B is arranged in the slot at the upper end, but as shown in FIG. 16, the quartz wafer 71B is arranged in a slot below the slot at the upper end, The wafer 10 may be disposed in the upper and lower slots of the slot in which the quartz wafer 71B is disposed. The quartz wafer 71A is not limited to being placed in the slot at the lower end, but is placed in the slot above the slot at the lower end, and the wafer 10 is placed in the slot above and below the slot where the quartz wafer 71A is placed. You may be made to do. However, as described above, there is a concern that the film thickness of the wafer 10 in the slot adjacent to the quartz wafer 71A may be reduced. Therefore, from the viewpoint of reducing the number of wafers 10 adjacent to the quartz wafer 71A, the quartz wafer 71A is preferably disposed in the slot at the lower end. In each of the above arrangement examples, a plurality of quartz wafers 71A and 71B are arranged, but only one quartz wafer 71A and / or 71B may be arranged on the wafer boat 3.

  The surface areas of the quartz wafer 71A and the quartz wafer 71B are not limited to the above. However, if the difference between the surface areas of the quartz wafers 71A and 71B is small and the surface areas of the quartz wafers 71A and 71B are relatively large, the wafer boat 3 can be disposed as in the case where only the quartz wafer 71A is disposed on the wafer boat 3. The film thickness of the wafer at the center of the height becomes small. Further, when the difference in surface area between the quartz wafers 71A and 71B is small and the surface area of each of the quartz wafers 71A and 71B is relatively small, the processing gas supplied to the upper side and the lower side of the wafer boat 3 is sufficiently supplied to the quartz wafers 71A and 71B. There is a concern that it cannot be adsorbed to 71B. Accordingly, the quartz wafers 71A and 71B are configured so that, for example, 0.01 ≦ surface area of the quartz wafer 71B / surface area of the quartz wafer 71A ≦ 0.9.

  Incidentally, as described above, the quartz wafers 71A and 71B have different surface areas. Here, the different surface areas do not mean that the surface areas are different due to errors in the manufacturing process, but that the surface areas are designed and manufactured to be different. In the above-described example, the surface area is different between the quartz wafers 71A and 71B depending on the number of grooves 70. However, in addition to the number of grooves 70, for example, the width of the groove 70, the depth of the groove 70, and the length of the groove 70 are different. The surface areas of the quartz wafers 71A and 71B may be different. Note that three or more types of quartz wafers 71 having different surface areas may be disposed on the wafer boat 3 to perform the film forming process.

  Incidentally, how much processing gas is adsorbed by the quartz wafer 71 on the upper side and the lower side of the wafer boat 3 will determine whether an appropriate film thickness distribution can be obtained between the wafers 10 mounted on the wafer boat 3. It depends on the surface area of 10. Therefore, for example, several types of quartz wafers 71B having relatively small surface areas are prepared with different surface areas. A quartz wafer 71A having a relatively large surface area is reused in each film forming process, and a quartz wafer 71B having an appropriate surface area is used for each film forming process according to the surface area of the wafer 10 to be processed. The processing may be performed by selecting and mounting on the wafer boat 3. Thus, by using the quartz wafer 71A, the number of manufactured quartz wafers 71 can be reduced, and by replacing the quartz wafer 71B, the amount of processing gas supplied to each wafer 10 can be controlled appropriately. Can do. Since the miniaturization of the pattern of the wafer 10 is progressing and the surface area of the wafer 10 to be film-formed is not always uniform, it is effective to take such measures.

  Also, the fifth embodiment can be combined with the above-described embodiments. Therefore, for example, the quartz wafers 71A and 71B may be transferred by a transfer mechanism (transfer mechanism) for transferring the wafer 10 to the wafer boat 3, or after the quartz wafers 71A and 71B are arranged on the wafer boat 3. Further, as described in the second embodiment, unevenness is formed in the reaction tube 11, and as described in the third embodiment, unevenness is formed in the top plate 31 and / or the bottom plate 32 of the wafer boat 3. As described in the fourth embodiment, the bare wafer 76 can be arranged on the wafer boat 3.

  By the way, when the quartz wafer 71 and the bare wafer 72 have the same outer shape, the quartz wafer 71 has a surface area three times or more that of the bare wafer 72 and only the quartz wafer 71 having the same surface area is used for film formation. It is estimated from the evaluation test described later that the film thickness is reduced on the wafer 10 at the center of the height of the wafer boat 3. Therefore, this fifth embodiment is particularly effective for improving the film thickness of the wafer 10 at the center of the height of the wafer boat 3 when the quartz wafer 71A has a surface area more than three times that of the bare wafer 72, for example. It is. It is assumed that the quartz wafer 71B has a smaller surface area than the quartz wafer 71A.

  In the wafer boat 3, it has been described that the quartz wafers 71A and 71B are arranged in order to adjust the gas distribution supplied to each wafer 10, but instead of the quartz wafers 71A and 71B, a wafer constituted of a material other than quartz. May be arranged to adjust the gas distribution supplied to each wafer 10. Such a wafer is configured in the same manner as the quartz wafers 71A and 71B except for the material. Examples of materials other than quartz include alumina (aluminum oxide), SiC (silicon carbide), and glassy carbon. Further, the film forming process may be performed in a state where a wafer on which a pattern other than the bare wafer 76 and / or the wafer 10 is formed is mounted between the quartz wafers 71 </ b> A and 71 </ b> B and the wafer 10. The bare wafer 76 and the wafer on which the pattern is formed are not limited to being made of quartz.

  By the way, the quartz wafers 71A and 71B may have a pattern (unevenness), that is, a groove 70 formed on both of two main surfaces (upper surface and lower surface), as shown in FIG. A pattern may be formed on only one of the two main surfaces. The main surface on which the pattern is formed is referred to as an uneven surface, and the main surface on which the pattern is not formed is referred to as an uneven surface. For example, when each of the quartz wafers 71A and 71B is configured to have such an uneven surface and an uneven surface, the uneven surface of the quartz wafers 71A and 71B is supported by the transfer mechanism, and the uneven surface is processed. It is conveyed with the surface facing up. By being transported as such, the quartz wafers 71A and 71B are transferred between the wafer boat 3 and the carrier that stores the quartz wafers 71A and 71B and transports them to the vertical heat treatment apparatus 1, for example. Accordingly, the quartz wafers 71A and 71B are mounted on the wafer boat 3 with the concavo-convex processed surface as the upper surface.

  As described above, when the quartz wafers 71A and 71B having the uneven surface and the uneven surface are repeatedly used and the SiN film is laminated, as a result of the difference in the amount of film forming gas adsorbed between the uneven surface and the uneven surface. There is a possibility that the stress applied to the uneven surface (lower surface) gradually increases, and the quartz wafers 71A and 71B warp so that the center portion of the uneven surface that is the upper surface is higher than the peripheral portion. Then, it can be considered that when the quartz wafers 71A and 71B are gradually warped in this way, it becomes difficult to support and transport the lower surfaces of the quartz wafers 71A and 71B by the transfer mechanism. In order to prevent this, as shown in the schematic diagram of FIG. 17, for example, a stress relaxation film 77 is deposited on the uneven surface of the quartz wafers 71 </ b> A and 71 </ b> B to suppress warpage by suppressing the stress on the uneven surface. It is preferable to form a film by the above.

  The stress relaxation film 77 is made of silicon oxide (SiO 2) or amorphous silicon (α-Si), and by forming a film of these materials, stress is suppressed and warpage of the quartz wafers 71A and 71B is suppressed. The reason is that the compressive stress of the SiN film can be offset by the tensile stress of the stress relaxation film 77. If the film has such an action, a material other than the above-described materials can be used. Can also be applied as the stress relaxation film 77. In the figure, reference numeral 78 denotes a support portion of the transfer mechanism that supports the uneven surface of the quartz wafers 71A and 71B.

  By repeatedly forming the film, the film thickness of the SiN film formed on the surfaces of the quartz wafers 71A and 71B increases. For example, when the stress relaxation film 77 is made of α-Si, the film thickness of the SiN film / When α-Si film ≦ 0.43, it is considered that the occurrence of warpage of the quartz wafers 71A and 71B can be suppressed. When the thickness of the SiN film / α-Si film> 0.43, it is considered that the quartz wafers 71A and 71B are warped, so that the quartz wafers 71A and 71B are cleaned. For example, when the stress relaxation film 77 is made of SiO2, it is considered that the occurrence of warpage of the quartz wafers 71A and 71B can be suppressed when the thickness of the SiN film / α-Si film ≦ 1.0. When SiN film thickness / SiO 2 film> 1.0, it is considered that the quartz wafers 71A and 71B are warped, so the quartz wafers 71A and 71B are cleaned. Accordingly, the film thickness of the stress relaxation film 77 is set in consideration of, for example, the number of times the quartz wafers 71A and 71B are repeatedly used and the film thickness of SiN formed by one film formation process. 77 is formed in advance on the quartz wafers 71A and 71B before being used in the film forming process.

(Evaluation test)
An evaluation test conducted in connection with the present invention will be described. As the evaluation test 1, as described in the background art section, the wafer boat 3 is mounted with the bare wafer 72 in the plurality of slots at the upper end and the plurality of slots at the lower end, and the wafer 10 is mounted in the other slot. Film formation processing was performed with a heat treatment apparatus. After the film forming process, the film thickness of the wafer 10 in each slot was measured. Further, as an evaluation test 2, a test wafer was mounted instead of the bare wafer 72 for processing. This test wafer has the same surface area as the wafer 10 and is made of the same material as the wafer 10. The surface area of both the wafer 10 and the test wafer is three times the surface area of the bare wafer 72.

  As the vertical heat treatment apparatus used for this evaluation test, an apparatus configured substantially the same as the apparatus of the above-described embodiment was used. However, the injector for supplying DCS gas is configured as shown in FIG. Yes. That is, a source gas supply nozzle 41b for supplying gas to the upper side of the boat 3 and a first source gas supply nozzle 41c for supplying gas to the lower side of the boat 3 are provided, and DCS gas is supplied from these nozzles 41b and 41c, respectively. Configured to be supplied.

  The graph of FIG. 19 is a graph showing the results of evaluation tests 1 and 2, wherein the horizontal axis indicates the slot number, and the vertical axis indicates the measured film thickness (unit: Å) of the wafer 10. In addition, the range of film thickness variation between the slots on which the wafer 10 is mounted in each evaluation test is indicated by arrows. As is clear from FIG. 19, in the evaluation test 1, the film thickness of the wafer 10 is larger in the upper and lower slots, that is, the slot near the slot on which the bare wafer 72 is mounted, in comparison with the evaluation test 2. Therefore, in the evaluation test 1, the variation in the film thickness of the wafer 10 between the slots is larger than that in the evaluation test 2. On the other hand, in the evaluation test 2, such an increase in the film thickness of the wafer 10 in the upper and lower slots is suppressed, thereby suppressing variations in film thickness between the slots. From the results of this test, as described in each embodiment, it is understood that it is effective to provide a member having a large surface area above and below the wafer 10 group arrangement region.

  Subsequently, evaluation tests 3-1 and 3-2 will be described. As an evaluation test 3-1, a large number of wafers 10 were placed in the slots of the wafer boat 3 as shown in FIG. A quartz wafer 71 was placed in a plurality of slots below the slot in which the wafer 10 was placed. In this evaluation test, the surface area S per unit area of the quartz wafer 71 / the surface area S0 per unit area of the wafer 10 is set to 3/5 = 0.6. In this way, each wafer was placed on the wafer boat 3 and the film forming process was performed as described in the embodiment of the invention. After the film forming process, the film thickness of 20 wafers 10 arranged in the slot above the slot where the quartz wafer 71 was arranged was measured. The wafers 10 used for the film thickness measurement are arranged on the wafer boat 3 adjacent to each other during the film formation process, and the wafer 10 arranged on the lowermost side among them is adjacent to the quartz wafer 71. This is the wafer that was placed.

  As evaluation test 3-2, film formation was performed in the same manner as in evaluation test 3-1, except that a bare wafer 72 was placed instead of the quartz wafer 71 in the slot where the quartz wafer 71 was placed in the evaluation test 3-1. And the film thickness of the 20 wafers 10 arrange | positioned above the bare wafer 72 was measured similarly to the evaluation test 3-1.

  The graph of FIG. 20 shows the results of evaluation tests 3-1, 3-2. The vertical axis of the graph represents the measured film thickness (unit: Å). The horizontal axis of the graph represents the number of wafers 10 used for the measurement. Of the wafers 10 used for the measurement, the wafer 10 placed on the uppermost side of the wafer boat 3 is set to 1, and the wafer placed below is shown. It is shown with a larger number. As shown in the graph, in the evaluation test 3-1, the film thickness of the wafer 10 having a relatively large number may be larger than the film thickness of the wafer 10 having a relatively small number as compared to the evaluation test 3-2. It is suppressed. When the maximum value of the film thickness-the minimum value of the film thickness was calculated, it was 3.40 mm in the evaluation test 3-1, and 7.41 mm in the evaluation test 3-2, and the calculated value in the evaluation test 3-1 was smaller. It was.

  As described above, in the evaluation test 3-1, variation in film thickness among the wafers 10 is suppressed as compared with the evaluation test 3-2. From the results of the evaluation tests 3-1 and 3-2, even when the quartz wafer 71 is placed in the slot above the slot in which the wafer 10 is placed, the film thickness of the wafer 10 placed near the quartz wafer 71. It is thought that it can prevent that becomes too large. Therefore, it was shown from the evaluation tests 3-1 and 3-2 that the film thickness distribution of each wafer 10 can be changed by the quartz wafer 71. As described in the fifth embodiment, by arranging the quartz wafers 71 having different surface areas, the film forming gas supplied to the wafer 10 can be adjusted with higher accuracy. It is thought that it can be made more uniform.

Evaluation test 4
As described in the first embodiment as the evaluation test 4, a silicon wafer having a pattern formed on the surface is arranged in the plurality of upper slots and the plurality of lower slots of the wafer boat 3, and the silicon wafer is arranged. A wafer 10 was placed in a slot that was not formed, and a film forming process was performed. And the film thickness formed in the wafer 10 of each slot was measured. Silicon wafers having a surface area of 30 times, 10 times, 5 times, and 3 times that of the bare wafer 72 having the same outer shape were prepared, and silicon wafers having different surface areas were used for each film forming process. However, it is assumed that the silicon wafers arranged in each slot for performing one film formation process have the same surface area.

  A film forming process using a silicon wafer having a surface area 30 times that of the bare wafer 72 (hereinafter referred to as “30 times silicon wafer”) is evaluated in Test 4-1, a silicon wafer having a surface area 10 times that of the bare wafer 72 (hereinafter referred to as 10 times). Film formation process using a silicon wafer) is evaluated test 4-2, and film formation process using a silicon wafer having a surface area five times that of the bare wafer 72 (hereinafter referred to as 5 times silicon wafer) is evaluated test 4- 3. A film forming process using a silicon wafer having a surface area three times that of the bare wafer 72 (hereinafter referred to as a triple silicon wafer) is referred to as an evaluation test 4-4.

  The graph of FIG. 21 is a graph showing the results of the evaluation test 4. The numbers on the horizontal axis of the graph indicate the slot numbers on which the wafers 10 are mounted, and the vertical axis indicates the measured film thickness. In the graph of FIG. 21, the film thickness (unit: Å) of each wafer 10 measured in the evaluation tests 4-1, 4-2, 4-3, and 4-4 with a solid line, a dotted line, a one-dot chain line, and a two-dot chain line, respectively. ). 21, in each of the evaluation tests 4-1 to 4-4, the film thickness of the wafer 10 mounted in the slot of the number 60 in the center of the height of the wafer boat 3 and the number in the vicinity thereof is as follows. It can be seen that the film thickness of the wafer 10 mounted in another slot is greatly reduced. In particular, in the evaluation test 4-1 using a 30-times silicon wafer, the difference between the film thickness of the wafer 10 in the central slot of the wafer boat 3 and the film thickness of the wafer 10 in the other slots is large. That is, it was confirmed that if only silicon wafers having the same surface area are arranged, the film thickness distribution between the wafers 10 may not be improved sufficiently. It is considered that the same experimental result is obtained when a wafer made of a material other than a silicon wafer, for example, the above-described quartz wafer 71 is disposed.

Evaluation test 5
As evaluation test 5-1, film formation was performed in the same manner as evaluation test 4-1. In this evaluation test 5-1, a 30-fold silicon wafer was placed in the upper two slots of the slot group in which the wafer 10 was placed and the lower seven slots. As evaluation test 5-2, a 10-fold silicon wafer is placed in the five slots above the slot group where the wafer 10 is placed, and a 30-fold quartz is placed in the seven slots below the slot group where the wafer 10 is placed. Except that the wafer 71 was disposed, a film formation process similar to that in the evaluation test 5-1 was performed. In each of the evaluation tests 5-1 and 5-2, the film thickness of each wafer 10 is measured after the film formation process, and the film thickness of the wafer 10 having the largest film thickness and the film thickness of the wafer 10 having the smallest film thickness are measured. The difference value was calculated.

  The difference value was 6.99 mm in the evaluation test 5-1, and 5.67 mm in the evaluation test 5-2. That is, in the evaluation test 5-2, variation in film thickness difference between the wafers 10 is suppressed. Therefore, from this evaluation test 5, the effect of the present invention was confirmed. In this evaluation test 5 as well, it is considered that the same experimental result is obtained even when a wafer of another material that is not a silicon wafer, for example, the above-described quartz wafer 71 is disposed.

W Wafer 1 Vertical heat treatment apparatus 10 Controller 11 Reaction tube 28 Heater 3 Wafer boat 60 Plasma generator 68 Vacuum pumps 71, 71A, 71B Quartz wafer 72 Bare wafer 100 Controller

Claims (17)

Vertical heat treatment in which a plurality of substrates to be processed having irregularities formed on the surface are heated by a heating unit while being held by a substrate holder in a vertical reaction vessel to perform film formation on the substrate to be processed In the device
A gas supply unit for supplying a film forming gas into the reaction vessel;
A gas distribution adjusting member provided so as to be positioned above and below the arrangement region of the plurality of substrates to be processed held by the substrate holder,
The gas distribution adjusting member is provided above and below the top plate of the substrate holder and above the bottom plate of the substrate holder. A second plate-like member,
The vertical heat treatment apparatus, wherein the first plate-shaped member has a first surface area, and the second plate-shaped member has a second surface area different from the first surface area. The vertical heat treatment apparatus according to claim 1, wherein the gas distribution adjusting member is made of quartz. The vertical heat treatment apparatus according to claim 1, wherein 0.01 ≦ the second surface area / the first surface area ≦ 0.9. 4. The device according to claim 1, wherein the first plate-like member is provided on one of the upper side and the lower side of the arrangement region of the substrate to be processed, and the second plate-like member is provided on the other side. 5. Vertical heat treatment apparatus described in 1.   The vertical heat treatment apparatus according to any one of claims 1 to 4, wherein the first plate-like member and the second plate-like member can be transported by a transport mechanism that transports the substrate to be processed.   In at least one plate-like member of the first plate-like member and the second plate-like member, the unevenness is formed on one main surface of two main surfaces, and the plate shape is formed on the other main surface. 6. The vertical heat treatment apparatus according to claim 1, wherein a film for preventing warping of the member is formed.   The vertical heat treatment apparatus according to any one of claims 1 to 6, wherein the gas distribution adjusting member includes a top plate of the substrate holder on which irregularities are formed.   The vertical heat treatment apparatus according to any one of claims 1 to 7, wherein the gas distribution adjusting member includes a ceiling portion of the reaction vessel in which irregularities are formed.   The vertical heat treatment apparatus according to any one of claims 1 to 8, wherein the gas distribution adjusting member includes a bottom plate of the substrate holder on which irregularities are formed.   The vertical heat treatment apparatus according to claim 1, wherein the gas distribution adjusting member includes an inner wall portion of the reaction vessel provided below an arrangement region of the plurality of substrates to be processed. Vertical heat treatment in which a plurality of substrates to be processed having irregularities formed on the surface are heated by a heating unit while being held by a substrate holder in a vertical reaction vessel to perform film formation on the substrate to be processed In the operation method of the device,
Supplying a film forming gas into the reaction container by a gas supply unit in a state where the gas distribution adjusting members are positioned above and below the arrangement region of the plurality of substrates to be processed held by the substrate holder, respectively. With
The gas distribution adjusting member is provided above and below the top plate of the substrate holder and above the bottom plate of the substrate holder. A second plate-like member,
The operation method of the vertical heat treatment apparatus, wherein the first plate-like member has a first surface area, and the second plate-like member has a second surface area different from the first surface area.   The operation method of a vertical heat treatment apparatus according to claim 11, wherein the gas distribution adjusting member is made of quartz. The operating method of the vertical heat treatment apparatus according to claim 11 or 12, wherein 0.01 ≦ the second surface area / the first surface area ≦ 0.9. The first plate-like member is provided on any one of the upper side and the lower side of the arrangement region of the substrate to be processed, and the second plate-like member is provided on the other side, respectively. The operation method of the vertical heat treatment apparatus described in 1.   In at least one plate-like member of the first plate-like member and the second plate-like member, the unevenness is formed on one main surface of two main surfaces, and the plate shape is formed on the other main surface. The method for operating a vertical heat treatment apparatus according to any one of claims 11 to 14, wherein a film for preventing warping of the member is formed.   The operating method of the vertical heat treatment apparatus according to any one of claims 11 to 15, wherein the gas distribution adjusting member includes a ceiling portion of the reaction vessel.   The operation of the vertical heat treatment apparatus according to any one of claims 11 to 16, wherein the gas distribution adjusting member includes an inner wall portion of the reaction vessel provided below an arrangement region of the plurality of substrates to be processed. Method.

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