JP4553227B2 - Heat treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat treatment method for performing heat treatment on a substrate such as a semiconductor wafer.
[0002]
[Prior art]
One of the film forming processes that are semiconductor device manufacturing processes is a process called CVD (Chemical Vapor Deposition). In this method, a processing gas is introduced into a reaction tube and a film is formed on the surface of a semiconductor wafer (hereinafter referred to as “wafer”) by chemical vapor phase reaction. One type of apparatus that performs such a film forming process in batch is a vertical heat treatment apparatus. This apparatus includes a vertical reaction tube provided on a cylindrical manifold, a heater provided so as to surround the reaction tube, and a gas introduction tube rushed through the manifold. And an exhaust pipe connected to the manifold. In such an apparatus, a holder called a wafer boat holds a plurality of wafers in a shelf shape so that an opening at the lower end of the manifold is formed. Then, the film is carried into the reaction tube and film formation is performed.
[0003]
Specifically, for example, when forming a silicon nitride film as an interlayer insulating film, the wafer is heated to a processing temperature, for example, 760 ° C. in a vacuum atmosphere of about 0.1 to 1 Torr, and this heating atmosphere is maintained. Film formation is performed by introducing ammonia (NH3) gas and dichlorosilane (SiH2 Cl2) gas, which are film formation gases.
[0004]
[Problems to be solved by the invention]
By the way, when a wafer is formed by the above-described apparatus under the above-mentioned conditions, the film thickness at the central portion of the wafer tends to be thinner than the peripheral portion. The reason is considered as follows. That is, in the above-described vertical heat treatment apparatus called a batch furnace, in the process of raising the wafer to the processing temperature, it is heated by a heater located on the peripheral side of the wafer, and per unit area at the peripheral edge of the wafer. Therefore, the temperature rise rate of the peripheral portion of the wafer becomes faster than that of the central portion, and the temperature of the peripheral portion becomes higher than that of the central portion. In the above apparatus, the film forming gas is introduced into the reaction tube by the gas introduction pipe, and the film forming gas is supplied from the peripheral side of the wafer to the wafer held by the wafer boat. The gas concentration is higher at the periphery of the wafer than at the center.
[0005]
As described above, due to the temperature difference and the concentration difference of the deposition gas generated between the peripheral portion and the central portion of the wafer, the peripheral portion of the wafer having the higher temperature and the concentration of the deposition gas is formed on the central portion. It is presumed that the reaction is promoted, the film thickness at the center of the wafer is thinner than the peripheral edge, and the in-plane uniformity of the film thickness is deteriorated. Such in-plane uniformity of film thickness becomes a problem because it becomes worse when a large-diameter wafer such as a 300 mm wafer or a thick film having a film thickness of 70 nm or more is formed.
[0006]
The present invention has been made under such circumstances, and an object of the present invention is to provide a heat treatment method capable of performing treatment with high in-plane uniformity when heat treating a substrate.
[0007]
[Means for Solving the Problems]
    In the present invention, the heat treatment atmosphere isMore than 3 steps verticallyIn the method of performing a heat treatment by disposing a substrate in each zone in the reaction vessel divided into zones and introducing a processing gas into the reaction vessel,
  Multiple boardsPlace it in a shelf on the board holderProcess to carry into reaction container(1)When,
  Heating each zone in the reaction vessel by a heating means to raise the temperature of each zone to a first process temperature corresponding to the zone(2)When,
  Then, for the uppermost zone and the intermediate zone between the uppermost zone and the lowermost zone, corresponding to each zoneFrom the first process temperature,eachUp to the second process temperature corresponding to the zoneTemperature dropMakeStep (3)And comprising
  When performing the step (3),Introduce processing gas into the reaction vessel to heat-treat the substrateYes,
  The temperature difference between the first process temperature and the second process temperature in the intermediate zone is smaller than the temperature difference between the first process temperature and the second process temperature in the uppermost zone.It is characterized by that.
[0010]
Here, if the temperature during the process is kept constant, for example, in the case of a film forming process, the film thickness at the peripheral part becomes larger than the central part, or conversely, the degree depends on the zone in the reaction vessel. It may change. On the other hand, in the process of raising the temperature inside the reaction vessel, the endothermic amount per unit area in the peripheral part of the substrate is larger than that in the central part, so the temperature in the peripheral part is higher than in the central part. Since the amount of heat radiation per unit area at the peripheral edge of this is larger than that at the central part, the temperature at the peripheral part becomes lower than that at the central part. Therefore, the processing gas is introduced while the temperature is shifted, and the temperature distribution is given in the substrate surface, and the temperature distribution influences, for example, the film thickness distribution in the surface when the temperature during the process is constant. By doing so, processing with high in-plane uniformity can be performed as a result.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
First, an example of a vertical heat treatment apparatus for carrying out the method of the present invention will be described with reference to FIG. In FIG. 1, 1 is a reaction tube having a double tube structure made of, for example, quartz made of an inner tube 1a and an outer tube 1b, and a metallic cylindrical manifold 2 is formed on the lower side of the reaction tube 1. Is provided.
[0012]
The inner pipe 1 a has an upper end opened and is supported on the inner side of the manifold 2. The outer tube 1 b is closed at the upper end, and the lower end is airtightly joined to the upper end of the manifold 3. In this example, a reaction vessel is constituted by an inner tube 1a, an outer tube 1b, and a manifold 2. Reference numeral 21 denotes a base plate.
[0013]
In the reaction tube 1, for example, as shown in FIG. 2, a plurality of wafers, for example, about 170 wafers W are horizontally placed on a wafer boat 11 as a holder with a space in the vertical direction. The wafer boat 11 is held on a lid 12 via a heat insulating cylinder (heat insulator) 13. The lid 12 is mounted on a boat elevator 14 for loading and unloading the wafer boat 11 into and from the reaction tube 1. When the lid 12 is at the upper limit position, the lower end opening of the manifold 2 is mounted. That is, it has a role of closing the lower end opening of the reaction vessel composed of the reaction tube 1 and the manifold 2. In FIG. 2, reference numeral 15 denotes a transfer arm for transferring the wafer W to the wafer board 11.
[0014]
The manifold 2 is provided with a plurality of gas introduction pipes 31 and 32 arranged in the circumferential direction for supplying a film forming gas (processing gas) and a purge gas to the inner side of the inner pipe 1a. The film forming gas is introduced into the reaction vessel through the gas introduction pipes 31 and 32, respectively. These gas introduction pipes 31 and 32 are made of, for example, quartz pipes. For example, the gas introduction pipe 31 is configured by protruding the quartz pipe from the outside to the inside of the manifold 2 and bending the tip thereof upward. The tube 32 is configured by protruding the quartz tube from the outside of the manifold 2 into the inside. One or more of these gas introduction pipes 31 and 32 share a nitrogen gas (N2 gas) introduction pipe and a film formation gas introduction pipe as purge gas. In addition to the film forming gas, oxygen may be introduced into the inner tube 1a as the processing gas.
[0015]
The gas introduction pipes 31 and 32 are connected to gas supply sources (not shown) of film forming gas such as SiH2 Cl2 gas and NH3 gas via open / close valves V1 and V2, respectively. The open / close valves V1 and V2 are controlled. The opening / closing timing is controlled by the unit 5 based on a film-forming gas introduction program at the time of the film-forming process inputted in advance, thereby controlling the timing for introducing the film-forming gas. Further, an exhaust pipe 22 is connected to the manifold 2 so as to open between the inner pipe 1a and the outer pipe 1b, and the inside of the reaction vessel is evacuated by a vacuum pump (not shown). .
[0016]
A heater 4 serving as a heating means is provided around the reaction tube 1 so as to surround it. The heater 4 is composed of, for example, a heating resistor, and the controller 5 controls the temperature based on the temperature profile of the film forming process inputted in advance. By the way, the heat treatment atmosphere in the reaction tube is divided into a plurality of, for example, three zones (regions) 6 (6a, 6b, 6c) from the top to the bottom (meaning that the temperature control region is divided). The heater 4 is also divided into three heaters 4 (4a, 4b, 4c) corresponding to these three zones, that is, temperature control of these three zones 6a, 6b, 6c, respectively. Yes. Although the control unit 5 is shown as one block in FIG. 1 for convenience, a temperature controller (not shown) is actually provided for each heater 4a, 4b, 4c, and these temperature controllers are provided in the zones 6a, 6b, 6c. The power supply of each heater 4a, 4b, 4c is controlled based on the temperature detection signal of the temperature detection part which is provided corresponding to (not shown).
[0017]
Next, the heat treatment method of the present invention performed by the above-described apparatus will be described with reference to FIG. 3 taking a case of forming a silicon nitride film as an example. First, for example, 170 wafers W to be processed are mounted on the wafer boat 11 and the boat elevator 14 is lifted to carry the wafer W into the reaction tube 1 having a heating atmosphere of, for example, 600 ° C. from the lower end opening. Then, the lid 12 hermetically seals the lower end opening of the manifold 2, that is, the wafer loading / unloading port of the reaction vessel (loading process). Next, the inside of the reaction vessel is evacuated through the exhaust pipe 22 by a vacuum pump (not shown) in a heating atmosphere of 600 ° C. (stabilization process).
[0018]
Subsequently, after the temperature of each zone 6a, 6b, 6c in the reaction tube 1 is once heated to a first process temperature, for example, about 770 ° C. by the heaters 4a, 4b, 4c (first temperature raising step), While performing temperature control based on a predetermined temperature profile, SiH2 Cl2 gas and NH3 gas are introduced into the inner pipe 1a from the gas introduction pipes 31 and 32, respectively, as a film forming gas, whereby the pressure is 0.25 Torr. In this state, a silicon nitride film is formed on the surface of the wafer W (process step). At this time, the film forming gas is introduced into the inner tube 1 a and the inside of the outer tube 1 b is exhausted by the exhaust tube 22, so that the film forming gas spreads into the reaction tube 1 and is mounted on the wafer boat 11. A silicon nitride film is uniformly formed on the surface of W.
[0019]
Here, the zones 6a, 6b, and 6c are all subjected to the same temperature control. However, different temperature controls may be performed as described later.
[0020]
The present invention is characterized in that the temperature of the wafer W is controlled in the process step and the film forming gas is intermittently introduced in accordance with the temperature control. For example, in the process step, each zone 6a, 6b, 6c The temperature is raised and lowered repeatedly between the first process temperature and the second process temperature lower than the first process temperature, specifically at a temperature around 760 ° C., for example, in the range of 750 ° C. to 770 ° C. The temperature is controlled so that the film forming gas is introduced when the temperature is lowered.
[0021]
As a specific process, for example, as shown in FIG. 4, each zone 6a, 6b, 6c is temporarily heated to about 770 ° C., which is the first process temperature, by heating by the heaters 4a, 4b, 4c. After the temperature has been raised to, a second process temperature lower than the first process temperature, for example, about 750 ° C., the heating by each heater 4a, 4b, 4c is suppressed and the temperature is lowered in about 23 minutes, for example. SiH2 Cl2 gas and NH3 gas are introduced at flow rates of 100 sccm and 1000 sccm, respectively (steps after temperature), and then the temperature is raised again to about 770 ° C. in about 4 minutes, for example, with the introduction of these film forming gases stopped (first step). 2 temperature raising step). Next, while introducing the film forming gas again, the temperature is lowered to about 750 ° C. in about 23 minutes, for example, and then the introduction of the film forming gas is stopped, and the zones 6a, 6b, 6c are again set to about 770 ° C. For example, the temperature is raised in about 4 minutes (additional temperature transition step). Next, while introducing the film forming gas again, the temperature of each zone 6a, 6b, 6c is lowered to about 750 ° C. in about 23 minutes (temperature transition step), and then the introduction of the film forming gas is stopped. Then, the temperature of each zone 6a, 6b, 6c is raised again to about 770 ° C., for example, in about 4 minutes (additional temperature transition step). Then, the temperature of each zone 6a, 6b, 6c is lowered to about 750 ° C. in 23 minutes, for example, while introducing the film forming gas again. That is, in this process, the introduction of the film forming gas is started at the start of the temperature decrease, and the introduction of the film forming gas is stopped at the start of the temperature increase (at the end of the temperature decrease).
[0022]
In this embodiment, each zone 6a, 6b, 6c is heated to a predetermined temperature by the heater 4, but the predetermined temperature control in the process step is performed by the control unit 5 as described above. Based on the temperature profile input to the unit 5, the heating temperature by the heaters 4a, 4b, 4c is controlled. The start and stop of introduction of the film forming gas is performed by opening / closing the opening / closing valve V, and the opening / closing control of the opening / closing valve V is performed by the control unit 5 as described above.
[0023]
After the predetermined silicon nitride film is thus formed, the introduction of the film forming gas is stopped, and the temperature of each zone 6a, 6b, 6c is lowered to about 600 ° C. (temperature lowering step). A purge gas such as N2 gas is introduced from, for example, two of the gas introduction pipes 31 and 32 into which the film forming gas has been introduced, and the inside of the reaction vessel is returned to normal pressure. Then, the boat elevator 14 is lowered to open the loading / unloading port at the lower end of the reaction vessel, and the wafer boat 11 is unloaded from the reaction vessel (unloading process).
[0024]
According to such an embodiment, since the surface temperature of the wafer W is controlled in the process step so as to repeat the temperature increase and the temperature decrease, and the film forming gas is introduced at the time of the temperature decrease, the nitride formed In-plane uniformity of the thickness of the silicon film can be improved.
[0025]
That is, as described above, in the temperature raising process of the wafer W, the endothermic amount per unit area in the peripheral portion of the wafer is larger than that in the central portion, so that the temperature in the peripheral portion of the wafer is higher than that in the central portion. Here, since the film growth rate increases as the temperature at the time of film formation increases, if the film formation gas is introduced immediately after the wafer W is heated to a predetermined temperature, the film formation described above is performed. When combined with the concentration distribution of the film gas in the wafer surface, for example, as shown in FIG. 5, the film thickness at the center of the wafer becomes thinner than the peripheral edge. Here, FIG. 5 shows that in the vertical heat treatment apparatus, after each zone 6a, 6b, 6c is heated to a predetermined temperature, for example, 760 ° C., a film forming gas is immediately introduced to bring the temperature of the wafer W to the above temperature. FIG. 6 is a characteristic diagram showing a film thickness distribution in a wafer surface of a formed silicon nitride film when a silicon nitride film is formed in a maintained state.
[0026]
On the other hand, when the temperature of the wafer W is lowered, the heat radiation amount per unit area at the peripheral portion of the wafer is larger than that at the central portion, so that the temperature decreasing rate at the peripheral portion of the wafer is faster than that at the central portion. As shown in the temperature distribution in the wafer surface when W is lowered from about 770 ° C. to about 750 ° C., the temperature of the peripheral portion becomes lower than that of the central portion.
[0027]
Therefore, if each zone 6a, 6b, 6c is heated to the first process temperature, then the temperature is lowered to the second process temperature, and the film formation gas is introduced at the time of the temperature decrease, the film is formed in the center of the wafer W. Influence of the temperature distribution of the wafer W in the temperature lowering process in which the temperature at the peripheral portion is lower than that at the peripheral portion and the concentration distribution of the film forming gas in which the concentration at the peripheral portion is higher than that at the central portion of the wafer W Thus, for example, as shown in FIG. 7, it is assumed that the film thickness of the film formed is almost uniform in the plane of the wafer W. Here, FIG. 7 shows that in the vertical heat treatment apparatus, after each zone 6a, 6b, 6c is heated to the first process temperature, the film forming gas is introduced when the temperature is lowered to the second process temperature. FIG. 5 is a characteristic diagram showing a film thickness distribution in a wafer surface of a formed silicon nitride film when a silicon nitride film is formed.
[0028]
As described above, in this embodiment, when the silicon nitride film is formed, the first process temperature is 770 ° C., the second process temperature is 750 ° C., and the temperature difference is 20 ° C. Although the temperature affects the film quality of the silicon nitride film, the film forming temperature range is limited, but there is no problem if the difference between the first process temperature and the second process temperature is set to about 40 ° C. or less.
[0029]
Therefore, it is desirable to repeat the temperature transition process and the additional temperature transition process within a certain range of film formation temperature without any problem. When film formation is performed in this way, a good film thickness can be maintained while maintaining necessary film quality characteristics. Can be obtained. For this reason, the present invention is particularly effective when, for example, a film is formed on a wafer having a diameter of 300 mm, or when a film having a thickness of 70 nm or more is formed. Uniformity can be ensured.
[0030]
In order to actually confirm the effect of the present invention, 170 8-inch wafers W were mounted on the wafer boat 11 and a silicon nitride film was formed by the above-described vertical heat treatment apparatus according to the above-described process. The results shown in FIGS. 8 and 9 were obtained. As the film forming gas, SiH2 Cl2 gas and NH3 gas are used, and the temperature of each zone 6a, 6b, 6c is controlled according to the temperature profile shown in FIG. In each case, a silicon nitride film is formed with a process pressure of 0.25 Torr and a thickness of 150 nm as a target, and the in-plane distribution of the thickness of the silicon nitride film and the in-plane uniformity of the thickness of the silicon nitride film are formed. Was measured. A similar experiment was also performed in the case where a silicon nitride film was formed by continuously introducing a deposition gas while maintaining the temperature of the wafer surface at 760 ° C. with the above-described vertical heat treatment apparatus. In this case, the flow rate of the film forming gas was 100 sccm for SiH2 Cl2 gas and 1000 sccm for NH3 gas, and the process pressure was 0.25 Torr.
[0031]
The results are shown in FIGS. 8 and 9, respectively. The degree of variation in the thickness of the silicon nitride film is shown in FIG. 8, and the in-plane distribution of the thickness of the silicon nitride film is shown in FIG. The case where the temperature control is performed is indicated by □, and the case where the temperature control is not performed is indicated by ◯. 8, the seventh, 46th, 85th, 124th, and 163rd wafers W from the top of the wafer boat 11 were sampled and formed on these wafers W. In-plane uniformity of the film thickness of the silicon nitride film was measured with a film thickness measuring device (Ellipsometer).
[0032]
As a result, when temperature control is performed, the value of the degree of film thickness variation is lower than when temperature control is not performed, and the lower value indicates higher in-plane uniformity. It was confirmed that the in-plane uniformity of the thickness of the silicon nitride film formed can be enhanced by controlling the temperature during the process and introducing the film forming gas when the temperature is lowered.
[0033]
In addition, the in-plane distribution of the film thickness of the silicon nitride film in FIG. 9 is obtained by sampling the 124th wafer W from the top on the wafer board 11 and, as shown in the plan view of the wafer W in FIG. The film thickness of the silicon nitride film at five positions (A, B, C, D, E) in the radial direction on the diameter was measured. Here, C is the center of the wafer W, A and E are positions 5 mm inside from the outer edge of the wafer W, and B and D are positions 52.5 mm inside from the outer edge of the wafer W.
[0034]
As a result, when the temperature control is not performed, the thickness of the silicon nitride film is found to be about 2.91 to 3.48 nm thinner than the peripheral portion at the central portion, whereas when the temperature control is performed. In this case, the film thickness of the silicon nitride film is recognized to be almost constant although there is a variation of about 0.36 nm, and the nitride formed by performing temperature control during the process step and introducing a film forming gas when the temperature is lowered. It was confirmed that the in-plane uniformity of the thickness of the silicon film can be improved.
[0035]
As described above, in the present invention, the first temperature raising step for raising the temperature of each zone 6a, 6b, 6c to the first process temperature is performed, and then the film forming gas is introduced while the temperature is lowered to the second process temperature. It is only necessary to carry out a temperature lowering step for film formation, and it is not always necessary to repeat the temperature transition step and the additional temperature transition step, but if the temperature transition step, the additional temperature transition step and the temperature decrease step are repeated, the higher Uniformity of the film thickness can be ensured.
[0036]
Furthermore, the present invention can be applied not only to the formation of a silicon nitride film but also to the formation of a polysilicon film, a silicon oxide film by TEOS, an HTO (High Temperature Oxide) film, and the like. Further, the present invention can be applied to film formation of oxide films such as dry oxidation, wet oxidation, and HCl oxidation other than the CVD film formation process.
[0037]
In the above embodiment, an example in which the same temperature control is performed on the zones 6a, 6b, and 6c in the reaction tube 1 has been described. However, the heaters 4a and 4b are applied to the zones 6a, 6b, and 6c, respectively. , 4c may be used for different temperature control.
[0038]
Next, another embodiment of the present invention will be described with reference to FIG. FIG. 11 is a diagram showing the relationship between time and temperature in each of the zones 6a, 6b and 6c when a silicon nitride film is formed on the surface of the wafer W using SiH2 Cl2 gas and NH3 gas as film forming gases. is there. As shown in FIG. 11, in the control unit 5, the first process temperatures assigned to the zones 6a, 6b, 6c are different from each other, and the second process temperatures assigned to the zones 6a, 6b, 6c are also different from each other. A temperature profile is set. For example, the first process temperature and the second process temperature in the upper zone 6a are 765 ° C. and 732 ° C., respectively, and the first process temperature and the second process temperature in the middle zone 6b are 770 ° C. and It is 757 ° C. The first process temperature and the second process temperature in the lower zone 6c are 800 ° C. and 757 ° C., respectively.
[0039]
In any of the zones 6a, 6b, and 6c, the temperature is first raised to the first process temperature (temperature raising step), and then the temperature is changed to the second process temperature in the temperature transition step where the film forming gas is introduced. In the temperature transition process, the temperature of any of the zones 6a, 6b, and 6c is lowered, and a film forming gas is introduced during the temperature lowering to form a uniform silicon nitride film on the surface of the wafer W. In this case, the temperature may be further increased from the second process temperature to the first process temperature (additional temperature transition step), and then the temperature may be decreased from the first process temperature to the second process. In the middle zone 6b, when the temperature is constant, the difference in film thickness between the peripheral edge and the center of the wafer W is very small. The difference between the first process temperature and the second process temperature) is considerably smaller than the gradient of the temperature change in the upper zone 6a and the lower zone 6b.
[0040]
Thus, when performing temperature control mutually between each zone 6a, 6b, 6c, since process gas rises from the bottom within a reaction container, it is high temperature in the upper zone 6a. The temperature of the zone 6a is controlled at a relatively low temperature, and the temperature of the lower zone 6c is controlled at a relatively high temperature. When the temperature is constant, the difference in film thickness between the peripheral edge and the center of the wafer W is grasped in advance, and the gradient of the temperature change is determined according to the difference in film thickness. Therefore, the silicon nitride film in each wafer W can be made uniform, and the silicon nitride film formed on the surface of the wafer W can be made uniform between the zones 6a, 6b, 6c.
[0041]
Furthermore, another embodiment of the present invention will be described with reference to FIG. FIG. 12 is a diagram showing the relationship between time and temperature in each zone when a silicon oxide film is formed on the surface of the wafer W using TEOS (tetraethoxysilane: Si (C2H5O) 4) as a film forming gas. It is. In this method, the heat treatment atmosphere is divided into five zones, and the heater 4 is also divided into five zones correspondingly, and different temperature control is performed for each zone by the divided heaters. ing. For convenience of explanation, 6a, 6ab, 6b, 6bc, and 6c are assigned to each zone divided into five stages in order from the upper stage side.
[0042]
Regarding the first process temperature and the second process temperature in each of the zones 6a, 6ab, 6b, 6bc, and 6c, the first process temperature and the second process temperature in the first stage zone (top stage) 6a are respectively 699 ° C. and 672 ° C., and the first process temperature and the second process temperature of the second stage zone 6ab are 692 ° C. and 674 ° C., respectively, and the first process temperature and the second process temperature of the third stage zone 6b are The process temperature of No. 2 is 685 ° C. and 673 ° C., respectively, and the first process temperature and the second process temperature of the fourth stage zone 6bc are 675 ° C. and 675 ° C., respectively. The first process temperature and the second process temperature are 662 ° C. and 685 ° C., respectively. Thus, in this embodiment, the first process temperature and the second process temperature are different from each other between the zones 6a, 6ab, 6b, 6bc, and 6c.
[0043]
As shown in FIG. 12, in any of the zones 6a, 6ab, 6b, 6bc, 6c, first, the temperature is raised to the first process temperature (temperature raising step), and then a temperature transition step in which TEOS is introduced is entered. In this temperature transition step, the temperature is raised from the first process temperature to the second process temperature in the fifth zone 6c, and is kept isothermally from the first process temperature to the second process temperature in the fourth zone 6bc. Then, in the first to third zones 6a, 6ab, 6b, the temperature is lowered from the first process temperature to the second process temperature.
[0044]
In this case, in each zone 6a, 6ab, 6b, 6bc, 6c, the temperature is further transferred from the second process temperature to the first process temperature (additional temperature transition step), and then the first process temperature to the second The temperature may be shifted to the process temperature (temperature transition step). Thereafter, the zones 6a, 6ab, 6b, 6bc and 6c enter the temperature holding process.
[0045]
Here, in the zone 6c of the fifth stage, which is the lowest stage, the film thickness tends to be higher at the central part than at the peripheral part of the wafer when temperature control is not performed. Unlike the temperature control in the zones 6a, 6ab, 6b, 6bc, the temperature is raised in the temperature transition process. Further, in the fourth zone 6bc, the difference in film thickness between the peripheral edge and the central portion of the wafer W is very small when the temperature is constant, so that the temperature is kept isothermal in the temperature transition process.
[0046]
Thus, by performing different temperature control between the zones 6a, 6ab, 6b, 6bc and 6c, that is, by setting appropriate first process temperature and second process temperature according to each zone, The silicon oxide film on the wafer W can be made uniform, and the silicon oxide film formed on the surface of the wafer W can be made uniform between the zones 6a, 6ab, 6b, 6bc and 6c.
[0047]
【The invention's effect】
As described above, according to the present invention, in-plane uniformity with a high film thickness can be ensured when forming a film on a substrate.
[Brief description of the drawings]
FIG. 1 is a vertical side view showing an example of a vertical heat treatment apparatus for carrying out the method of the present invention.
FIG. 2 is a perspective view showing a part of the vertical heat treatment apparatus.
FIG. 3 is a characteristic diagram showing the relationship between temperature and time when a silicon nitride film is formed by the method of the present invention.
FIG. 4 is a characteristic diagram showing the relationship between temperature and time when forming a silicon nitride film.
FIG. 5 is a characteristic diagram showing the relationship between the thickness of the silicon nitride film and the position on the wafer.
FIG. 6 is a characteristic diagram showing a relationship between temperature and a position on a wafer.
FIG. 7 is a characteristic diagram showing the relationship between the thickness of the silicon nitride film and the position on the wafer.
FIG. 8 is a characteristic diagram showing the relationship between the in-plane variation of the film thickness of the silicon nitride film and the position of the wafer on the wafer board.
FIG. 9 is a characteristic diagram showing the relationship between the thickness of the silicon nitride film and the position on the wafer.
FIG. 10 is a plan view for explaining sampling locations on the wafer.
FIG. 11 is a characteristic diagram showing a relationship between temperature and time when a silicon nitride film is formed.
FIG. 12 is a characteristic diagram showing the relationship between temperature and time when a silicon oxide film is formed.
[Explanation of symbols]
W Semiconductor wafer
1 reaction tube
1a Inner pipe
1b Outer pipe
2 Manifold
3 Gas introduction pipe
4 (4a, 4b, 4c) Heater
5 Control unit
V open / close valve

Claims (2)

In a method in which a heat treatment atmosphere is arranged in each zone in a reaction vessel divided into three or more zones in the vertical direction, and a heat treatment is performed by introducing a processing gas into the reaction vessel.
A step (1) of arranging a plurality of substrates in a shelf shape on a substrate holder and carrying them into a reaction container;
A step (2) of heating each zone in the reaction vessel with a heating means to raise each zone to a first process temperature corresponding to the zone;
Next, the temperature of the uppermost zone and the intermediate zone between the uppermost zone and the lowermost zone are lowered from the first process temperature corresponding to each zone to the second process temperature corresponding to each zone. Step (3)
When performing the step (3), have a row to a heat treatment to the substrate by introducing a process gas into the reaction vessel,
The temperature difference between the first process temperature and the second process temperature in the intermediate zone is smaller than the temperature difference between the first process temperature and the second process temperature in the uppermost zone. Heat treatment method. In the step (3), the temperature of the intermediate zone is maintained at the first process temperature instead of lowering from the first process temperature to the second process temperature corresponding to the zone. The heat treatment method according to claim 1.

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