JP2019019391A - Film deposition apparatus - Google Patents

Abstract

To provide a film deposition apparatus capable of forming a uniform film by using a center-flow process where a gas is supplied from right above the center of a substrate and exhausted from the outer periphery of the substrate.SOLUTION: A film deposition apparatus of an embodiment of the invention is equipped with a film deposition chamber, a stage and a shower head. The stage supports an object substrate set in the film deposition chamber. The shower head is arranged opposite the stage and has a flow channel of a gas to be introduced into the film deposition chamber. The flow channel has an opening of a round shape when cut by a plane parallel to the stage, wherein the area of the opening gets larger toward the stage. The flow channel is arranged opposite the center of the object substrate. The product r×h is constant in all planes parallel to the stage, wherein r indicates a radius of the flow channel when cut by a plane parallel to the stage, and h indicates a distance between the parallel plane and the stage.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a film formation apparatus used for film formation by, for example, an ALD (Atomic Layer Deposition) method.

Thinning the gate insulating film is indispensable for improving the performance and power consumption of MOS FETs. Up to now, SiO ₂ and SiON have been used as the gate insulating film, but with these materials, the leakage current increases rapidly as the thickness is reduced. In order to prevent this, a high dielectric constant (High-k) gate insulating film and a metal gate are essential. As the high-k gate insulating film, for example, HfO ₂ (hafnium dioxide), HfAlO, HfSiO, or the like is used.
In order to uniformly form a high-k gate insulating film having a thickness of several nanometers on a substrate, an atomic layer deposition (ALD) method capable of finely controlling the deposited film thickness is used. .

  In a film forming apparatus capable of forming a film by the ALD method, a supply port for supplying a reaction gas to the substrate is provided on the side of the substrate, and the gas is supplied in a state where the substrate is rotated (see, for example, Patent Document 1). ).

International Publication No. 2005/088692

  In the side flow type film forming apparatus for supplying gas from the side of the substrate as described above, the volume of the chamber becomes large, and the structure for introducing gas is complicated in order to form a film uniformly in the surface.

  In view of the circumstances as described above, an object of the present invention is to provide a center flow type film forming apparatus that supplies gas from directly above the center of the substrate and exhausts it from the outer periphery of the substrate.

In order to achieve the above object, a film formation apparatus of one embodiment of the present invention includes a film formation chamber, a stage, and a shower head.
The stage supports a substrate to be processed provided in the film formation chamber.
The shower head is arranged to face the stage, and is a flow path through which a gas introduced into the film formation chamber passes. The shower head is circular in a shape parallel to the stage and has an opening area toward the stage. Has a channel that becomes larger. The flow path is installed corresponding to the central portion of the substrate to be processed, the radius of the flow path cut by a plane parallel to the stage is r, and the distance between the parallel plane and the stage is h When this is done, r × h is constant on all surfaces parallel to the stage.

  According to such a configuration of the present invention, since the flow path of the shower head is configured so that rh is constant, the flux (flux) of the gas supplied to the substrate to be processed is changed to that of the substrate to be processed. It can be made almost uniform in the plane. As a result, a film having a substantially uniform film thickness can be formed on the substrate to be processed.

  You may further comprise the said gas supply source and the diffusion plate which diffuses the gas from the said supply source arrange | positioned between the said supply source and the said shower head.

  By providing the diffusion plate in this manner, the gas from the gas supply pipe having a relatively small cross-sectional area can be diffused in the plane direction parallel to the substrate to be processed. As a result, the gas diffused in the parallel plane direction is supplied to the substrate to be processed through the flow path of the showerhead, so that the film thickness of the film formed on the substrate to be processed can be made more uniform in the plane. Can be.

  The supply source includes a source gas supply source for supplying a source gas and a reaction gas supply source for supplying a reaction gas, and the supply of the source gas from the source gas supply source to the surface of the substrate to be processed. The supply of the gas that reacts with the source gas on the substrate to be processed from the reaction gas supply source may be alternately repeated.

  As described above, the present invention may be applied to film formation by the ALD method in which the supply of the source gas and the supply of the reaction gas are alternately repeated.

The source gas may be hafnium chloride (IV), and the reaction gas may be water vapor.
Thereby, hafnium dioxide can be deposited. Even in film formation using a gas that does not self-limit such as hafnium (IV) chloride, the flow path of the shower head is configured so that rh is constant, so that the gas supplied to the substrate to be processed Since the flux can be made substantially uniform within the surface of the substrate to be processed, hafnium dioxide having a substantially uniform film thickness within the surface can be obtained.

  As described above, according to the present invention, it is possible to provide a film forming apparatus capable of forming a thin film having a substantially uniform film thickness in a plane.

It is a general-view figure of the film-forming apparatus of one Embodiment of this invention, and is a figure explaining an ALD module and a gas introduction system. It is the elements on larger scale of the film-forming apparatus of FIG. It is the elements on larger scale near the shower head of the film-forming apparatus shown in FIG. It is a figure for demonstrating the curved surface shape of the shower head of FIG. In the film forming apparatus of FIG. 1, the gas velocity distribution of each of the X-axis component and the Z-axis component of the gas velocity of the gas introduced into the film forming chamber is simulated. In the film-forming apparatus provided with the shower head of the comparative example, it is the figure which simulated the gas velocity distribution of each X-axis component and Z-axis component of the gas velocity of the gas introduced into the film-forming chamber. It is the conceptual diagram which simulated the flux (Flux, flux) of the gas produced based on FIG. 5 in the film-forming apparatus shown in FIG. It is the conceptual diagram which simulated the flux (Flux, flux) of the gas produced based on FIG. 6 in the film-forming apparatus of a comparative example. The film thickness distribution of hafnium dioxide formed by repeating the first process to the fourth process using the film forming apparatus of FIG. 1 while varying the introduction time of hafnium (IV) chloride in the first process. The film thickness distribution of hafnium dioxide formed by repeating the first step to the fourth step using the comparative film forming apparatus and varying the introduction time of hafnium (IV) chloride in the first step. 1 shows the film thickness distribution of hafnium dioxide formed by repeating the first to fourth steps by using the film forming apparatus of FIG. 1 and varying the introduction time of water vapor in the third step. The film thickness distribution of hafnium dioxide formed by repeating the first step to the fourth step using the film forming apparatus of the comparative example and varying the introduction time of water vapor in the third step. It is the figure which simulated the relationship between the cross-sectional area S and the gas velocity in the shower head with the flat surface facing the stage provided in the film-forming apparatus of a comparative example. It is a timing chart explaining the supply timing of the gas at the time of forming hafnium dioxide into a film using the film-forming apparatus of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A film forming apparatus according to an embodiment of the present invention is a center flow type film forming apparatus that supplies a gas from directly above a central portion of a substrate to be processed. In this embodiment, an example in which hafnium dioxide (HfO ₂ ) is formed as a thin film using the ALD method will be described. Here, hafnium chloride (IV) (HfCl ₄ ) gas and H ₂ O (water vapor) are used as a precursor.

[Film deposition system]
FIG. 1 is an overview of the film forming apparatus according to the first embodiment, and is a view for explaining an ALD module and a gas introduction system. FIG. 2 is a partially enlarged view of the film forming apparatus of FIG. 1. In FIG. 2, the gas introduction system is shown in a simplified manner. FIG. 3 is a partially enlarged view of the vicinity of the shower head of the film forming apparatus of FIG. FIG. 4 is a view for explaining the curved surface shape of the bottom surface of the shower head of FIG.

  The film forming apparatus 100 includes a film forming chamber 101, a lid unit 107, a film forming chamber 105, a heater stage 104, a diffusion plate 121, a gas supply source 111, a gas supply valve 112, and a gas supply pipe 113. It comprises.

  The lid portion 107 includes a lid body 102 and a shower head 103. The heater stage 104 and the shower head 103 are spaced apart from each other. In addition, the film forming apparatus 100 includes an exhaust pump that exhausts the gas in the film forming apparatus 100 via an exhaust duct 140 provided in the lower part of the film forming apparatus 100.

  The film forming chamber 101 is configured to accommodate the heater stage 104 and the lid portion 107 therein. The lid portion 107 forms a film forming chamber 105 for forming a thin film on the substrate 110 to be processed together with the inner bottom portion of the film forming chamber 101. The outer shape of the lid portion 107 has a substantially cylindrical shape with a diameter g of 480 mm. In addition, all the dimensions of each part to describe are examples, and are not limited to these.

  A shower head 103 is attached to the lower portion of the lid portion 107. A diffusion chamber 120 into which gas from the gas supply source 111 is introduced and diffuses is provided at a substantially central portion of the lid portion 107. A gas supply path 106 for supplying gas from the gas supply source 111 to the diffusion chamber 120 is provided above the lid portion 107.

  A space constituting the film forming chamber 105 is provided below the lid portion 107, and the diameter f of this space is 460 mm. The diffusion chamber 120 is located between the film formation chamber 105 and the gas supply path 106.

  The gas supply path 106 has a cylindrical shape, and its diameter n is 20 mm. The diffusion chamber 120 has a cylindrical shape with a diameter m of 100 mm and a height l of 25 mm. The gas supply path 106 has a relatively small cross section cut along a plane parallel to the XY plane, and the cross section cut along a plane parallel to the XY plane of the diffusion chamber 120 is larger than the cross section of the gas supply path 106.

  The upper part of the diffusion chamber 120 has an opening communicating with the gas supply path 106. The upper surface 103 b of the shower head 103 forms the bottom surface of the diffusion chamber 120. As a result, the lower part of the diffusion chamber 120 has an opening communicating with a flow path 103 a described later provided in the shower head 103.

  A diffusion plate 121 having a circular planar shape (XY plane in the drawing) parallel to the heater stage 104 is disposed in the center of the diffusion chamber 120. The thickness k of the diffusion plate 121 is 3 mm, and the diameter m is 100 mm. The diffusion plate 121 is provided with a through hole 121a through which gas can pass. The diffusion chamber 120 is divided into a diffusion chamber 120a and a diffusion chamber 120b vertically by a diffusion plate 121 in the drawing. The volume of the diffusion chamber 120b is designed to be larger than the volume of the diffusion chamber 120a.

  When the gas supply path 106 is projected onto the diffusion plate 121, the gas supply path 106 is located in the region of the diffusion plate 121. Thereby, the gas supplied from the gas supply path 106 to the diffusion chamber 120 collides with the diffusion plate 121 and flows along the upper surface of the diffusion plate 121. As a result, convection occurs and the gas diffuses in the diffusion chamber 120a. Is done. The diffused gas is introduced into the diffusion chamber 120b through the through hole 121a.

  When the diffusion plate 121 is projected onto the upper surface 103 b of the shower head 103, the through hole 121 a of the diffusion plate 121 is located within the upper surface 103 b of the shower head 103. Thereby, the gas introduced into the diffusion chamber 120b from the through hole 121a of the diffusion plate 121 collides with the upper surface of the shower head 103 and flows along the upper surface 103b of the shower head 103. As a result, convection is generated and gas diffusion occurs. It is diffused in the chamber 120b. The diffused gas is supplied to the substrate 110 to be processed placed on the heater stage 104 through the flow path 103a.

  The heater stage 104 supports a substrate 110 to be processed that is carried in from a substrate carry-in / out port 108 provided on a side surface of the film forming chamber 101. The heater stage 104 has a circular planar shape with a diameter e of 336 mm. The substrate to be processed 110 has a circular shape with a diameter o of 300 mm. Note that the size of the substrate to be processed 110 is not limited to this.

The gas supply source 111 includes a raw material container 111a that supplies hafnium chloride (IV) (HfCl ₄ ) as a raw material gas, and a water container 111c that supplies water vapor (H ₂ O) as a reactive gas.

A gas supply pipe 113, a raw material (HfCl ₄ ) container 111 a, a water (H ₂ O) container 111 c, and an argon (Ar) pipe 116 are connected to the film forming chamber 101. The temperature of the raw material (HfCl ₄ ) container 111a and the water container 111c is controlled at 136 ° C. and 5 ° C., respectively. MFC (Mass Flow Controller) 114a and 114c for controlling the flow rate are connected to the two containers 111a and 111c, respectively. The flow rates of argon flowing through the argon pipes 115a and 115c are controlled by the MFCs 114a and 114c, respectively, and introduced into the raw material container 111a and the water container 111c, respectively. Thereby, the argon gas containing the raw material (HfCl ₄ ) and the argon gas containing water are introduced into the film forming chamber 105.

  Argon introduced from the argon pipe 116 is used as a purge gas that flows after the supply of the source gas and the reaction gas is stopped. An MFC 114 b for controlling the flow rate is connected to the argon pipe 116, and argon gas whose flow rate is controlled is introduced into the film forming chamber 105.

  The gas supply valve 112 has gas supply valves 112a to 112c. The gas supply valves 112a to 112c adjust the supply amount of gas from the raw material container 111a, the argon pipe 116, and the water container 111c to the diffusion chamber 120, respectively. The gas supply valves 112 a to 112 c are provided in a gas supply pipe 113 that supplies gas from the raw material container 111 a, the argon pipe 115, and the water container 111 c to the gas supply path 106.

  The gas supply source 111 (the raw material container 111a and the water container 111c), the argon pipe 116, the gas supply valve 112, and the gas supply pipe 113 may be configured as a unit. The temperature of the gas supply path can be controlled by a heater, the vapor pressure of the gas is controlled by the heater, and the supply amount is controlled by a valve.

  The shower head 103 is disposed opposite to the heater stage 104 so as to be separated from the heater stage 104. A flow path 103 a that is a through hole is provided at the center of the shower head 103. The flow path 103a is installed so that the center thereof corresponds to the center of the substrate to be processed 110 disposed on the heater stage 104 during film formation (typically, the center of the heater stage 104). As a result, the gas is supplied from directly above the center of the substrate to be processed 110.

  The gas flowing from the diffusion chamber 120 to the film formation chamber 105 passes through the flow path 103a. The shape of the flow path 103a cut by a plane (XY plane) parallel to the heater stage 104 is a circle. The opening area of the flow path 103 a gradually increases from the diffusion chamber 120 toward the heater stage 104.

  The shape of the shower head 103 viewed from above is a ring shape in which the flow path 103a is located at the center. The shower head 103 has an upper surface 103b located on the diffusion chamber 120 side and a bottom surface 103c located on the film formation chamber 105 side. The flow path 103a is a through hole whose opening area gradually increases from the upper surface 103b to the bottom surface 103c.

  The flat outer shape of the shower head 103 is a circle having a diameter b of 459 mm. The thickness i along the Z-axis direction of the shower head 103 is 26 mm. The diameter a of the circular opening of the flow path 103a formed on the upper surface 103b is 40 mm, and the diameter c of the circular opening of the flow path 103a formed on the bottom surface 103c is 380 mm. During film formation, the distance p between the upper surface 103b of the shower head 103 and the upper surface 104a of the stage 104 is set to be 33 mm.

  When the shower head 103 is cut in a direction (Z-axis direction) perpendicular to the upper surface 104a of the heater stage 104, the portion forming the flow path 103a has a curve.

  When the flow path 103a is cut by a plane parallel to the upper surface 104a of the heater stage 104, the radius of the circular cross section is r [mm], and the distance between the cut surface and the upper surface 104a of the heater stage 104 is h [mm]. In this case, the flow path 103a of the shower head 103 is formed so as to have a curved surface in which rh (r × h value; the same applies hereinafter) is constant on all surfaces parallel to the heater stage 104 in the flow path 103a. . FIG. 3 shows an example of the radius r and the distance h in the cut surface 150.

  FIG. 4 shows the relationship between the distance h and the step area S in the curved surface area of the bottom surface of the shower head 103. The cross-sectional area S is represented by S = 2πrh. The gas supplied from the diffusion chamber 120 to the film formation chamber 105 flows between the shower head 103 and the heater stage 104 so as to spread from the center of the substrate to be processed 110 toward the edge (periphery). The cross-sectional area S corresponds to the cross-sectional area of the flow path of the gas supplied from the diffusion chamber 120.

  The horizontal axis in FIG. 4 indicates the distance [mm] from the center of the shower head 103 in the XY plane of FIG. 3, and indicates the radius r in the cut surface 150 cut by a plane parallel to the XY plane of the flow path 103a. The center of the shower head 103 coincides with the center of the flow path 103 a of the shower head 103 in the XY plane, and the perpendicular line of the XY plane passing through the center of the shower head 103 passes through the center of the substrate to be processed 110.

The left vertical axis in FIG. 4 indicates the distance h [mm] from the upper surface 104a of the heater stage 104 along the Z-axis direction. The right vertical axis in FIG. 4 indicates the cross-sectional area S [mm ² ].

  In the present embodiment, when the substrate to be processed 110 is projected onto the bottom surface 103c, the substrate to be processed 110 is located within the outer region of the flow path 103a having a curved surface with a constant rh of the shower head 103. That is, the diameter of the circular substrate to be processed 110 is designed to be smaller than the diameter of the circular region serving as the largest opening of the flow path 103a.

  The bottom surface 103c of the shower head 103 may have a curved surface in which at least rh is constant in a region corresponding to the substrate to be processed 110, that is, a circular region having a diameter of 300 mm. As a result, the gas flows to the peripheral edge of the substrate to be processed 110 while the decrease in the gas flux is suppressed, and the uniformity of the film thickness of the substrate to be processed 110 is improved.

  The curved surface forming the bottom surface 103c is a curved surface having a quadratic cross section or an approximate curve thereof. In this embodiment, the distance between the shower head 103 and the heater stage 104 is A / r (A Is a constant, and r is a curve shape constituted by a curve (1 / R curve (R = r / A)) determined by a radius of the cut surface 150).

  More preferably, a curved surface having a constant rh is formed on the bottom surface 103c of the shower head 103 in a region larger than the region corresponding to the substrate to be processed 110 as in the present embodiment. As a result, the gas flow is more reliably distributed to the peripheral edge of the substrate to be processed 110 while the decrease in the gas flux is suppressed, and the film thickness uniformity at the peripheral edge of the substrate to be processed 110 is further improved. Thereby, a film can be formed on the substrate 110 to be processed with a uniform in-plane film thickness.

  An exhaust pump that exhausts the film forming chamber 105 through an exhaust port (not shown) is connected to the bottom of the film forming chamber 101. The exhaust pump is composed of various vacuum pumps such as a turbo molecular pump and a dry pump. When performing the film forming process in the film forming apparatus 100, the pressure in the film forming chamber 105 is set to 1 Pa to 1000 Pa, for example. The pressure is reduced to a predetermined pressure.

[Method for Forming Hafnium Dioxide (HfO ₂ )]
Next, a method for forming hafnium dioxide using the film forming apparatus 100 will be described. FIG. 14 is a timing chart for explaining gas supply timing.

  First, the substrate to be processed 110 is placed on the heater stage 104, and the substrate to be processed 110 is carried into the film formation chamber 105.

  Next, as a first step, hafnium (IV) chloride is introduced from the source gas supply source 111a. Hafnium (IV) chloride introduced into the diffusion chamber 120 diffuses in the diffusion chamber 120, and the diffused hafnium (IV) chloride is released into the film formation chamber 105. Thereby, hafnium chloride (IV) gas molecules are chemically adsorbed on the surface of the substrate 110 to be processed (coating process). After the hafnium chloride (IV) gas molecules are chemically adsorbed on the surface of the substrate to be processed 110, the introduction of hafnium (IV) chloride from the source gas supply source 111a is stopped.

FIG. 1 shows a conceptual diagram of an ALD module and a gas introduction system.
The coating conditions are as follows: the temperature of the substrate to be processed is 300 ° C., the temperature of the raw material container 111a of hafnium (IV) chloride is 136 ° C., the pressure in the film forming chamber 101 is 130 Pa, and the introduction time of hafnium (IV) chloride is 0.6. 1 to 1.5 seconds, argon is introduced into the raw material container 111a shown in FIG. 1 at a flow rate of 300 sccm, and vaporized hafnium (IV) chloride gas and argon are mixed in the container 111a, and then the film formation chamber 105 is formed. To introduce. In the subsequent processing, the temperature of the substrate to be processed is set to 300.degree.

  Next, as a second step, argon gas is introduced as a purge gas from the purge gas supply source 111b. The argon gas introduced into the diffusion chamber 120 diffuses in the diffusion chamber 120, and the diffused argon gas is released into the film formation chamber 105. The pressure in the diffusion chamber 120 is increased by the purge gas, and the source gas is pushed out of the diffusion chamber 120. The source gas diffused into the film forming chamber 105 is evacuated by an exhaust pump (purge process).

  The purge conditions were an argon gas introduction time of 1.5 seconds, a pressure in the film forming chamber 101 of 130 Pa, and an argon gas flow rate of 400 sccm.

  Next, as a third step, water vapor is introduced as a reactive gas from the reactive gas supply source 111c. The water vapor introduced into the diffusion chamber 120 diffuses in the diffusion chamber 120, and the diffused water vapor is released into the film formation chamber 105. The water vapor reacts with the molecules of the hafnium chloride (IV) gas adhering to the surface of the substrate to be processed 110 to oxidize the hafnium chloride (IV) to form a thin film of hafnium dioxide (oxidation process). After the molecules of the source gas (hafnium (IV) chloride) on the surface of the substrate 110 to be processed react with the reactive gas (water vapor), the introduction of the reactive gas from the reactive gas supply source 111c is stopped.

  Oxidation conditions were as follows: the introduction time of water vapor was 0.5 seconds, the temperature of the water container 111c in FIG. 1 was 5 ° C., the pressure in the film forming chamber 101 was 130 Pa, and argon was introduced into the water container 111c at a flow rate of 50 sccm. Then, the water vapor and argon in the container 111 c are mixed and then introduced into the film formation chamber 105.

  Next, as a fourth step, argon gas is introduced as a purge gas from the purge gas supply source 111b. The argon gas introduced into the diffusion chamber 120 diffuses in the diffusion chamber 120, and the diffused argon gas is released into the film formation chamber 105. The pressure in the diffusion chamber 120 is increased by the purge gas, and the reaction gas is pushed out of the diffusion chamber 120. The reaction gas diffused into the film formation chamber 105 is evacuated by an exhaust pump (purge process).

  The purge conditions were an argon gas introduction time of 1.5 seconds, a pressure in the film forming chamber 101 of 130 Pa, and an argon gas flow rate of 400 sccm.

  The above first to fourth steps are repeated a plurality of cycles in order until a hafnium dioxide thin film having a desired thickness is formed. In this embodiment, the number of cycles was 32, and hafnium dioxide having a thickness of 2 to 3 nm was obtained.

  In the present embodiment, the film formation is performed using the film formation apparatus 100 including the shower head 103 having a curved surface with a constant rh, so that the raw material is substantially uniformly in-plane on the substrate 110 to be processed in the coating process. Gas can be supplied. Further, in the oxidation step, the reaction gas can be supplied almost uniformly on the substrate 110 to be processed within the surface, so that the oxidation reaction can be uniformly generated within the surface. Thereby, a thin film of hafnium dioxide having a uniform in-plane thickness is obtained.

[Comparison between this embodiment and comparative example]
Next, when the shower head 103 having a curved surface with a constant rh is used according to the present embodiment, and a shower head with a flat bottom shape with a constant distance h between the bottom surface of the shower head and the heater stage as a comparative example. Compare the cases used.
It is assumed that a cylindrical flow path with a diameter of 40 mm through which gas passes is provided at the center of the shower head of the comparative example. The film forming apparatus of the comparative example and the film forming apparatus of the present embodiment are the same except for the bottom face shape of the shower head.

The gas supplied from directly above the substrate to be processed 110 spreads from the center of the substrate to be processed 110 toward the peripheral edge (edge portion).
FIG. 5 shows changes in the gas velocity accompanying the spread of the gas introduced into the film formation chamber 105 of the film formation apparatus 100 having the shower head 103 of the present embodiment, and the X-axis component V _X and the Z-axis component of the gas velocity. V _Z respective gas velocity distribution is a diagram obtained by simulating the. FIG. 7 is a diagram simulating changes in the gas flux (Flux) created based on FIG. 5 in the film forming apparatus 100 including the shower head 103 according to the present embodiment.

FIG. 6 shows the change in gas velocity accompanying the spread of the gas introduced into the film formation chamber 105 of the film formation apparatus having the shower head of the comparative example, and each of the X-axis component V _X and the Z-axis component V _{Z of the} gas velocity. It is the figure which simulated gas velocity distribution of this. FIG. 8 is a diagram simulating changes in the gas flux created based on FIG. 6 in the film forming apparatus 100 having the shower head of the comparative example.

  FIG. 13 is a diagram simulating the relationship between the cross-sectional area S and the gas flow velocity in the shower head of the comparative example. In FIG. 13, the horizontal axis indicates the distance from the center of the substrate to be processed along the radius of the substrate to be processed, the left vertical axis indicates the gas velocity, the right vertical axis indicates the cross sectional area S, the dotted line indicates the cross sectional area S, and the solid line indicates the gas. Indicates speed. As shown in FIG. 13, the cross-sectional area S is represented by a straight line that rises to the right as the gas spreads.

5 and 6, the horizontal axis indicates the distance from the center of the substrate to be processed 110 along the radius of the circular target substrate 110, and the vertical axis indicates the gas velocity. When the gas velocity is V [m / sec], the flow rate is Q [Pa · m ³ / sec], and the pressure is P [Pa], V = Q / [P · S].

  7 and 8, the horizontal axis indicates the distance from the center of the substrate to be processed 110 along the radius of the substrate to be processed 110, and the vertical axis indicates the magnitude of gas concentration, flux, and gas velocity. The flux is determined by the product of gas velocity and gas concentration.

As shown in FIGS. 6, 8, and 13, in the shower head having a flat bottom shape in the comparative example, the region of the substrate to be processed corresponding to the flow path of the shower head, that is, the distance from the center of the substrate to be processed. However, in the region up to about 20 mm, the gas velocity gradually increases, but the gas velocity decreases from around 20 mm.
Further, since the gas is absorbed and decomposed on the substrate 110 and the wall surface of the film formation chamber 105, the gas concentration gradually decreases toward the peripheral edge of the substrate 110 to be processed.
As described above, in the shower head in the comparative example, the gas velocity and the gas concentration are decreased toward the peripheral portion of the substrate to be processed. Therefore, the gas flux is gradually decreased toward the peripheral portion of the substrate to be processed. Go. For this reason, the thickness of the substrate to be processed is reduced particularly at the peripheral portion, and it is difficult to obtain a uniform thickness in the surface.

  On the other hand, as shown in FIGS. 5 and 7, in the shower head 103 having a curved surface with a constant rh in the present embodiment, an opening having a diameter a of 40 mm on the diffusion chamber 120 side of the flow path 103a of the shower head. The gas velocity gradually increases in the region of the substrate to be processed corresponding to, i.e., the region from the center of the substrate to be processed to about 20 mm, the gas velocity decreases from about 20 mm, and the gas velocity starts again from about 40 mm. It is gradually increasing. Further, since the gas is absorbed and decomposed on the substrate to be processed and the wall surface of the film formation chamber 105, the gas concentration gradually decreases toward the peripheral edge of the substrate to be processed 110.

  In the shower head 103 according to the present embodiment, although the gas velocity once decreases, the gas velocity increases again, and this increase in gas velocity continues to the peripheral edge of the substrate to be processed 110. As the gas flows from the center toward the peripheral edge, the decrease in the gas flux is suppressed as compared with the shower head of the comparative example, and the magnitude of the gas flux after exceeding about 40 mm from the center of the substrate 110 to be processed. Is almost constant.

  As described above, in this embodiment, since the flux of the gas supplied to the substrate to be processed 110 is suppressed from decreasing toward the peripheral portion of the substrate to be processed, the surface of the substrate to be processed 110 is almost uniformly uniform. Since the raw material gas is supplied and the water vapor is supplied substantially uniformly in the plane and the uniform oxidation treatment is performed in the plane, a thin film with improved in-plane uniformity of film thickness can be obtained.

  Further, since the gas supplied to the flow path 103a of the shower head 103 is diffused by the diffusion plate 121, the gas introduced into the flow path 103a has a substantially uniform concentration in the plane. Thereby, the in-plane uniformity of the film thickness of the thin film formed on the to-be-processed substrate 110 can be further improved.

Next, this embodiment and a comparative example are compared regarding the introduction time of hafnium (IV) chloride.
FIG. 9 shows the film forming apparatus 100 having the shower head 103 according to the present embodiment, and the steps from the first step to the fourth step are changed by changing the introduction time of hafnium (IV) chloride in the first step. The film thickness distribution of the to-be-processed substrate 110 of hafnium dioxide formed by repeating the cycle is shown. In FIG. 9, the horizontal axis indicates the distance from the center along the radius of the substrate to be processed 110, and the vertical axis indicates the film thickness of hafnium dioxide. FIG. 9 shows that the introduction time of hafnium (IV) chloride is shaken in six ways of 0.5 seconds, 0.8 seconds, 0.9 seconds, 1.0 seconds, 1.2 seconds, and 1.5 seconds. Is the film thickness distribution of the thin film formed under the above-described conditions.

  FIG. 10 is a comparative example of FIG. In the comparative example, film formation was performed using the film forming apparatus provided with the shower head having a flat bottom surface shape in which the distance h between the bottom surface of the shower head and the upper surface of the heater stage described above is constant. FIG. 10 shows the film thickness distribution of the substrate 110 to be processed of hafnium dioxide formed under the same film forming conditions as FIG. In FIG. 10, the horizontal axis indicates the distance from the center along the radius of the substrate to be processed 110, and the vertical axis indicates the film thickness of hafnium dioxide. FIG. 10 shows that the introduction time of hafnium (IV) chloride is shaken in six ways of 0.5 seconds, 0.8 seconds, 0.9 seconds, 1.0 seconds, 1.2 seconds, and 1.5 seconds. Is the film thickness distribution of the thin film formed under the above-described conditions.

  As shown in FIG. 10, in the comparative example, regardless of the introduction time of hafnium (IV) chloride, the formed hafnium dioxide film becomes thinner toward the peripheral edge of the substrate 110 to be processed. . As described above, the gas concentration is normally consumed by being adsorbed or decomposed on the substrate to be processed or the wall surface, and therefore gradually decreases toward the downstream side of the gas, that is, toward the peripheral edge of the substrate to be processed. In addition to this, in the film forming apparatus of the comparative example having a flat shower head, the gas velocity also decreases on the downstream side (periphery side of the substrate to be processed), so the gas flux is the peripheral edge of the substrate to be processed. It goes down as it goes to the department. For this reason, as shown in FIG. 10, the film thickness of the hafnium dioxide formed by the film forming apparatus equipped with the shower head having a flat bottom shape is thicker in the vicinity of the central part, and from the central part to the peripheral part. The film thickness gradually decreases as it goes, and the in-plane film thickness distribution becomes non-uniform.

  On the other hand, in this embodiment, as shown in FIG. 9, if the introduction time of hafnium chloride is 0.8 seconds or more, the film thickness of the formed hafnium dioxide increases from the central part toward the peripheral part. Although the film thickness is slightly reduced, the vicinity of the periphery of the substrate to be processed is also sufficiently formed, and the in-plane uniformity of the film thickness is greatly improved as compared with the comparative example. In addition, when the introduction time of hafnium chloride is 0.5 seconds, the film thickness at the outer peripheral portion is extremely thin compared with the central portion, but this is because the gas reaches the peripheral portion of the substrate to be processed. It is presumed that there was not enough time to complete.

  In this manner, by performing film formation using the film formation apparatus 100 including the shower head 103 having a curved surface with a constant rh, the film formation rate within the surface of the substrate to be processed can be made substantially uniform. Further, as shown in FIG. 9, if the introduction time of hafnium (IV) chloride is set to 0.8 seconds or more, the film formation rate within the surface of the substrate to be processed can be made substantially uniform, and 0.8 seconds. 1 to 1.5 seconds, the film formation rate exhibits substantially the same behavior, and a thin film having a substantially uniform film thickness can be obtained in the plane. The introduction time of hafnium (IV) chloride is preferably 1.5 seconds or less, more preferably 1.0 seconds or less, and if it is longer than 1.5 seconds, the processing time for each substrate becomes long, and the productivity is increased. Not practical.

Further, in order to make the film formation rate within the surface of the substrate to be processed even more uniform, the time for introducing water vapor during the oxidation step may be adjusted.
Next, this embodiment and a comparative example are compared regarding the introduction time of water vapor | steam.

  FIG. 11 shows the film forming apparatus 100 provided with the shower head 103 according to the present embodiment, and the above-mentioned first to fourth steps are repeated 32 cycles with different water vapor introduction times in the third step. The film thickness distribution of the deposited hafnium dioxide is shown. Here, the introduction time of hafnium (IV) chloride in the first step was set to 0.8 seconds, and the other conditions were the same as the coating conditions described in the first step of the hafnium dioxide film forming method. The purge conditions were the same as the purge conditions in the second and fourth steps. The oxidation conditions in the third step were the same as the above oxidation conditions except for the introduction time of water vapor.

  In FIG. 11, the horizontal axis indicates the distance from the center toward the peripheral edge along the radius of the circular substrate 110, and the vertical axis indicates the film thickness of hafnium dioxide. FIG. 11 shows a thin film formed by varying the water vapor introduction time in five ways of 0.5 seconds, 0.7 seconds, 0.8 seconds, 0.9 seconds, and 1.0 seconds.

  FIG. 12 is a comparative example of FIG. In the comparative example, film formation was performed using a film forming apparatus including a shower head having a flat bottom surface shape in which the distance h between the bottom surface of the shower head and the upper surface of the heater stage is constant, as in the above comparative example. FIG. 12 shows a film thickness distribution of hafnium dioxide formed on the substrate 110 to be processed under the same film forming conditions as hafnium dioxide shown in FIG. Here, the introduction time of hafnium (IV) chloride in the first step was set to 1.0 second, and the other conditions were the same as the coating conditions described in the first step of the hafnium dioxide film forming method. The purge conditions were the same as the purge conditions in the second and fourth steps. The oxidation conditions in the third step were the same as the above oxidation conditions except for the introduction time of water vapor.

  In FIG. 12, the horizontal axis indicates the distance from the center toward the peripheral edge along the radius of the circular substrate 110, and the vertical axis indicates the film thickness of hafnium dioxide. FIG. 12 shows a thin film formed by varying the water vapor introduction time in four ways of 0.3 seconds, 0.5 seconds, 0.7 seconds, and 1.0 seconds.

As shown in FIG. 12, in the comparative example, the film thickness of the formed hafnium dioxide film becomes thinner as it approaches the peripheral edge of the substrate 110 to be processed regardless of the introduction time of water vapor. In particular, when the introduction time of water vapor was 1.0 second, the variation in the film thickness within the surface of the substrate to be processed was larger than the other introduction times. This is presumably because the water supply is excessive and the multilayer adsorption is performed, so that the water component becomes excessive HfO _x (x> 2).
As described above, the film thickness of hafnium dioxide formed by the film forming apparatus having a flat shower head is extremely thin in the vicinity of the peripheral portion of the substrate 110 to be processed, compared with the central portion. The film thickness distribution is uneven.

  This is because in the film forming apparatus of the comparative example provided with the shower head having a flat bottom surface shape, both the hafnium chloride (IV) and the water vapor decrease in the same way toward the peripheral portion of the substrate to be processed. Even if the introduction time of hafnium (IV) chloride and water vapor is changed, there is no optimum condition for making the film thickness distribution in-plane uniform, or the margin is narrowed.

  In contrast, in the present embodiment, as shown in FIG. 11, if the water vapor introduction time is 0.5 seconds or more, the formed hafnium dioxide film is treated regardless of the water vapor introduction time. It became almost uniform in the plane of the substrate 100. In particular, by making the introduction time of water vapor 0.9 seconds or more, the in-plane uniformity of the film thickness of the formed hafnium dioxide was further improved as compared with other introduction times.

As shown in FIG. 11, if the introduction time of water vapor in the third step is 0.5 seconds or more, the film formation rate on the surface of the substrate to be processed becomes substantially uniform, and the film thickness of hafnium dioxide is uniform in the surface. Improves. More preferably, if it is 0.9 seconds or more, the in-plane uniformity of the film forming rate can be further improved, and the in-plane uniformity of the film thickness of hafnium dioxide can be further improved.
The introduction time of water vapor is preferably 1.5 seconds or less, more preferably 1.0 seconds or less. If the time is longer than 1.5 seconds, the treatment time for each substrate becomes long, which is not practical for production. .

  As described above, in this embodiment, film formation is performed using the film formation apparatus 100 including the shower head 103 including a flow path having a curved surface with a constant rh, thereby forming a film within the surface of the substrate to be processed. The film rate can be made substantially uniform.

  As described above, when hafnium dioxide is formed using the ALD method in the film forming apparatus 100 including the shower head 103 having a flow path having a constant rh, the introduction time of hafnium chloride is set to 0. It is possible to obtain hafnium dioxide with improved in-plane uniformity of the film thickness by setting the water vapor introduction time to 0.5 seconds to 1.0 seconds and 0.8 seconds to 1.0 seconds.

  In this embodiment, the case where hafnium dioxide is deposited using the ALD method is taken as an example. Hafnium chloride (IV), which is a source gas, is a source material that does not self-stop growth (self-limitation). Therefore, during the coating process, the amount of the source gas molecules adsorbed to the substrate to be processed is the amount of gas transported. The distribution is greatly affected. Since the transport amount is determined by the gas flux, it is difficult to make the adsorption amount of the raw material gas molecules uniform within the substrate surface unless the gas flux supplied within the substrate surface is constant.

  Since the film forming apparatus of the present embodiment includes a shower head having a curved surface with a constant rh, the gas flux supplied to the substrate to be processed can be made almost constant within the surface of the substrate to be processed. A film having a uniform film thickness can be formed within the surface of the substrate to be processed. As described above, the film forming apparatus of the present embodiment can form a film with a substantially uniform film thickness within the surface of the substrate to be processed even when a source gas that does not self-limit is used. This is particularly effective when a raw material gas that is not used is used.

The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention. In the present embodiment, the film formation of hafnium dioxide has been described as an example in the film formation using the ALD method. However, the present invention is not limited to this. For example, the present invention can also be applied to the film formation of Al ₂ O ₃ . In the film formation of Al ₂ O ₃ , TMA (trimethylaluminum) is used as a source gas and water vapor is used as a reaction gas.

DESCRIPTION OF SYMBOLS 100 ... Film-forming apparatus 103 ... Shower head 103a ... Flow path 104 ... Heater stage (stage)
105 ... Film formation chamber 111 ... Gas supply source 110 ... Substrate to be processed 121 ... Diffusion plate

Claims (4)

A deposition chamber;
A stage for supporting a substrate to be processed provided in the film formation chamber;
A flow path that is disposed opposite to the stage and through which a gas introduced into the film forming chamber passes, and has a circular shape cut along a plane parallel to the stage and has an opening area that increases toward the stage. And a shower head with
The flow path is installed corresponding to the central portion of the substrate to be processed, the radius of the flow path cut by a plane parallel to the stage is r, and the distance between the parallel plane and the stage is h Then, r × h is constant on all surfaces parallel to the stage. The film forming apparatus according to claim 1,
A source of the gas;
A film forming apparatus, further comprising: a diffusion plate that diffuses gas from the supply source disposed between the supply source and the shower head. The film forming apparatus according to claim 1 or 2,
The supply source has a source gas supply source for supplying source gas and a reaction gas supply source for supplying reaction gas,
The supply of the source gas to the surface of the substrate to be processed from the source gas supply source and the supply of the gas that reacts with the source gas on the substrate to be processed from the reaction gas supply source are alternately repeated. Deposition equipment to be performed. The film forming apparatus according to claim 3,
The source gas is hafnium chloride (IV), and the reaction gas is water vapor.

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