KR20040043410A - Middle pressure chemical vapor deposition system - Google Patents

Abstract

PURPOSE: A middle pressure chemical vapor deposition apparatus is provided to control the pressure of the inside of a reaction furnace without being influenced by an atmospheric pressure by including a low-vacuous vacuum pump and an absolute pressure control unit that can maintain an absolute pressure of 70-80 kilo pascal. CONSTITUTION: A reaction furnace(100) includes a reaction gas inducing nozzle. An exhaust unit(105) exhausts the gas generated from the reaction furnace to the outside, connected to the reaction furnace. An absolute pressure control unit(120) controls a uniform pressure inside the reaction furnace and maintains a uniform partial pressure of the reaction gas, attached to the exhaust unit. A gas exhausting pipe(110) exhausts the gas passing through the absolute pressure control unit to the outside, connected to the absolute pressure control unit. A low vacuum pump(130) increases the pressure inside the reaction furnace, connected to an end of the gas exhausting pipe.

Description

Medium pressure chemical vapor deposition apparatus {MIDDLE PRESSURE CHEMICAL VAPOR DEPOSITION SYSTEM}

The present invention relates to a medium pressure chemical vapor deposition apparatus, and more particularly to a medium pressure chemical vapor deposition apparatus capable of maintaining an absolute pressure.

The semiconductor manufacturing process consists of numerous steps in which physical and chemical processing is performed to manufacture a semiconductor device having a high degree of integration. In order to proceed with such a process, the equipment used in the semiconductor manufacturing process is manufactured at a high price to form a specific atmosphere. In addition, the cost for carrying out this step is also very high. Therefore, each step is carried out by an apparatus and method suitable for the characteristics of the processing to be performed by the step, so as to further reduce the cost.

Among the components of the semiconductor device, low pressure chemical vapor deposition (hereinafter, referred to as' a method for forming components in which uniformity of film quality is important, such as tunnel oxide film, gate electrode and various etch stop layers, '' LP-CVD '). The LP-CVD method is a method of accumulating a desired film by surface thermal reaction of only injected gases by maintaining the inside of a furnace at a low pressure and selectively injecting a reactant. LP-CVD apparatus requires a heater to increase the temperature inside the reactor and a vacuum pump to maintain the inside of the reactor at a vacuum of about 100 Pa or less, and an O-ring to maintain the degree of vacuum inside the reactor. Accessories for sealing the reactor, such as O-rings, are essential.

The process of the LP-CVD method includes a film such as silicon nitride, doped polysilicon, middle temperature oxide, and the like. The growth rate of the film quality by the LP-CVD method has variables such as temperature, pressure, composition of the gas, properties of the gas, properties of the reaction and characteristics of the reactor. At this time, the factors influencing the growth rate of the film quality such as the silicon nitride film, the doped polysilicon film and the intermediate temperature oxide film are in the order of temperature> pressure> gas content≥semiconductor substrate spacing.

However, the LP-CVD method has a low reaction rate due to a low partial pressure of the reactant, and thus, the process time of the entire manufacturing process of the semiconductor device is delayed, and the process cost increases to maintain the process conditions.

Accordingly, the uniformity of the film, such as silicon surface passivation, insulation, and oxide masking, is relatively insignificant and is a method of rapidly forming the film. Hereinafter, the method is referred to as 'AP-CVD'. The AP-CVD method is used in most oxide film processes in which an oxide film is rapidly formed by a strong bonding force between the surface of a silicon substrate and oxygen by forming a film while maintaining the inside of the reactor at a high temperature and maintaining the internal pressure at a normal pressure. have. Since the AP-CVD apparatus additionally does not have a vacuum pump, the by-products generated in the AP-CVD apparatus are discharged to the outside through the exhaust facilities of the semiconductor manufacturing building. Therefore, the pressure inside the reactor is only slightly lower than about 1 kPa than the atmospheric pressure (about 100 kPa), but the pressure is not controlled.

For example, a utility exhaust (O2 / HCl) is supplied to the reactor, and the utility exhaust (Control Exhaust) is controlled to about 0.4 ~ 1kPa using an automatic pressure controller (hereinafter referred to as 'APC'); Hereinafter, by-products are exhausted by 'UT exhaust'. Here, the APC functions to maintain a constant pressure difference between the clean room and the exhaust duct of the reactor in order to smoothly discharge the reaction gas, and the absolute pressure inside the reactor, such as a vacuum pump, is maintained. It cannot be kept constant. That is, the internal pressure of the reactor changes directly under the influence of the external pressure condition (atmospheric pressure).

The semiconductor manufacturing equipment is installed in a clean room, which maintains a slightly higher pressure than outside the clean room to maintain cleanliness. However, the pressure inside the clean room is included in the range of atmospheric pressure, and the atmospheric pressure is not maintained accurately, but changes in real time and the pressure inside the clean room is also fluid within an error range, so that the AP-CVD apparatus proceeds to normal pressure. Will affect the pressure inside the reactor. The change in the atmospheric pressure causes a change in the film thickness to be laminated, thereby causing a change in the process conditions, resulting in a change in the characteristics of the semiconductor device, thereby lowering the reliability of the semiconductor device.

Accordingly, it is an object of the present invention to provide a medium pressure chemical vapor deposition apparatus capable of maintaining an absolute pressure regardless of a change in external pressure.

1A is a schematic diagram of a Middle Pressure Chemical Vapor Deposition apparatus according to Example 1 of the present invention.

Figure 1b is a schematic diagram showing a reactor of the Middle Pressure Chemical Vapor Deposition apparatus according to Example 1 of the present invention.

2 is a graph showing a change in atmospheric pressure that changes over a year.

3A is a schematic diagram of a typical Atmospheric Chemical Vapor Deposition apparatus.

FIG. 3B is a graph showing the change in pressure at key points of the Atmospheric Chemical Vapor Deposition apparatus of FIG. 3A.

FIG. 4 is a graph showing the thickness of oxide film formed by pressure according to Pick's First Law of Diffusion. FIG.

5A to 5B are graphs illustrating a change in oxide film formation thickness over time using a general atmospheric chemical vapor deposition (Atmospheric Chemical Vapor Deposition) apparatus.

6A to 6B are graphs showing trends of pressures of oxide film formation thicknesses using a general atmospheric chemical vapor deposition (Atmospheric Chemical Vapor Deposition) apparatus.

7 is a schematic diagram of a parallel Middle Pressure Chemical Vapor Deposition apparatus according to Embodiment 2 of the present invention.

In order to achieve the above object, a medium pressure chemical vapor deposition apparatus includes a reactor including a reactor gas introduction nozzle, an exhaust port connected to the reactor, and an exhaust port attached to the exhaust port to constantly adjust the pressure in the reactor to reduce the partial pressure of the reactor. An absolute pressure control unit for maintaining a constant, a gas exhaust pipe connected to the absolute pressure control unit and a low vacuum pump connected to the end of the gas exhaust pipe.

In this way, a vacuum pump and an absolute pressure control unit are provided to manufacture a reliable semiconductor device by maintaining the absolute pressure without reacting to an external pressure change.

Hereinafter, the present invention will be described in detail.

The medium pressure diffusion reactor is a reactor including a reactor gas introduction nozzle, an exhaust port connected to the reactor, an absolute pressure control unit attached to the exhaust port to constantly adjust the pressure in the reactor to maintain a partial pressure of the reactor. And a low vacuum pump connected to an end of the gas exhaust pipe connected to the gas exhaust pipe connected to the absolute pressure control unit.

In this case, the reactor may be provided in plural for one low vacuum pump, the absolute pressure control unit maintains the pressure in the reactor at a constant pressure of 20 to 30kPa lower than atmospheric pressure.

The reactor includes one quartz tube on which a wafer is loaded, a heating coil for forming a reaction temperature in the one quartz tube, a reaction gas inlet for introducing a reaction gas into the one quartz tube, and one quartz tube. And a by-product exhaust, which is present and introduces gas into the wafer, and a by-product vent for evacuating by-products generated in the one quartz tube.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example 1

1A is a schematic diagram of a Middle Pressure Chemical Vapor Deposition apparatus according to Example 1 of the present invention.

Referring to FIG. 1A, a Middle Pressure Chemical Vapor Deposition (hereinafter referred to as 'MP-CVD') apparatus includes a reactor 100 in which pressure and temperature are controlled to cause a reaction. The exhaust port 105 of the reactor 100 is attached to the gas exhaust pipe 110, the absolute pressure control unit for constantly adjusting the pressure in the reactor to the first inlet connected to the gas exhaust pipe 110, the exhaust port 105 120 is provided. The distal end of the gas exhaust pipe 110 provided with the absolute pressure control unit 120 is connected to the low vacuum pump 130. The exhaust of the low vacuum pump 130 is connected to the exhaust 140 of the semiconductor manufacturing equipment.

The MP-CVD apparatus is equipped with a separate low vacuum pump, an absolute pressure sensor, and a pressure regulating device capable of forming a vacuum degree of about 80 kPa or less, so that the absolute pressure of the reactor is about 70 to 80 kPa, which is about 20 to 30 kPa lower than atmospheric pressure. Keep constant In general, atmospheric pressure means about 100 kPa and varies in the range of about ± 4 kPa. Therefore, the pressure inside the reactor is not influenced by the external pressure, and in order to maintain the deposition rate required in the process, the atmospheric pressure must be kept constant at about 70 to 80 kPa, which is about 20 to 30 kPa. Therefore, while the conventional AP-CVD apparatus is exhausted by the exhaust pressure difference of the exhaust portion of the semiconductor manufacturing equipment and is affected by the atmospheric pressure, the MP-CVD apparatus does not respond to the change in the atmospheric pressure.

Figure 1b is a schematic diagram showing a reactor of the Middle Pressure Chemical Vapor Deposition apparatus according to Example 1 of the present invention.

Referring to FIG. 1B, the reactor includes a quartz tube 150 serving as a main body for loading a wafer. Since the MP-CVD apparatus achieves a much lower vacuum degree than the conventional LP-CVD apparatus, a single quality tube 150 is used. The quarts tube 150 is provided with a heating coil 155 for forming a reaction temperature inside the quarts tube 150, the reaction gas inlet 160 for introducing a reaction gas into the quarts tube 150 Include. The introduced reaction gas is provided to the wafer 190 through a quality gas nozzle 165. By-products of the gas reacted to the wafer 190 are discharged through the by-product exhaust port 170.

Influence of atmospheric pressure on the pressure inside the reactor

2 is a graph showing a change in atmospheric pressure that changes over a year.

Referring to FIG. 2, the actual atmospheric pressure change was measured monthly for one year for a certain region, and the atmospheric pressure was changed in the range of about 98.5 to 102.5 kPa. Therefore, the pressure inside the reactor also changes in a width of about 4 kPa within the range of about 98.0 to 102.0 kPa.

FIG. 3A is a schematic diagram of a typical Atmospheric Chemical Vapor Deposition apparatus, and FIG. 3B is a graph showing the change in pressure at key points of the Atmospheric Chemical Vapor Deposition apparatus of FIG. 3A.

3A and 3B, it can be seen that the pressure inside the reactor 300 changes in conjunction with the atmospheric pressure. The film formation method by AP-CVD apparatus forms a film quality, keeping the inside of a reactor high temperature, and maintaining an internal pressure at normal pressure. For example, the AP-CVD apparatus supplies a reactor body (O 2 / HCl) to the reactor 300 to form an oxide film, and the facility exhaust unit (APC 310) is controlled to an exhaust pressure of about 0.4 to 1 kPa using the APC 310 ( By-products). Here, the APC 310 serves to smoothly discharge the reactant gas by maintaining a differential pressure between the clean room and the inside of the exhaust duct of the reactor.

For example, looking at the change in the actual atmospheric pressure in February, when the atmospheric pressure 330 is in the range of about 98.5 to 102.5 kPa, the pressure 340 in the clean room is about 30 Pa higher than the atmospheric pressure, and the pressure of the exhaust 350 ) Is about 700 Pa lower than the pressure inside the clean room. The pressure inside the reactor 360 by the APC is about 400 Pa lower than the inside of the clean room so that it is maintained in the range of about 98.5 to 102.5 kPa.

As such, since the pressure inside the reactor is affected by the atmospheric pressure, the pressure inside the reactor must be kept lower than the atmospheric pressure, and about 70 to 80 kPa should be maintained in order to maintain it stably. That is, even if the atmospheric pressure changes in a certain range, the pressure in the reactor is always kept lower than the atmospheric pressure, and thus does not affect the inside of the reactor.

Influence of Pressure in Reactor on Film Formation Rate

The process of forming an oxide film using a general AP-CVD apparatus is to form a thin film while maintaining the inside of the reactor at a high temperature and maintaining the internal pressure at atmospheric pressure. In this case, when the oxide film formation process is expressed based on the Pick's first law of diffusion, the flux on the oxide film surface is expressed by Equation 1, and the flux is a gas on the oxide film surface. It can be seen that it is proportional to the concentration NO.

J = DN ₀ / (X ₀ + D / k _s ) Equation 1

J: Particle flow per unit area (flux)

D: Diffusion coefficient

N ₀ : Oxygen concentration at the oxide surface

X ₀ : Thickness of the silicon dioxide layer

k _s : Rate constant for the reaction at Si-SiO2 interface

According to Equation 1, since the gas concentration N ₀ is proportional to the partial pressure of the reactor, it can be seen that the growth rate of the oxide film increases as the pressure in the reactor increases.

FIG. 4 is a graph showing the thickness of oxide film formed by pressure according to Pick's First Law of Diffusion. FIG.

Referring to FIG. 4, when the oxide film is formed under the same conditions except for 60 minutes, the thickness of the oxide film formed during the same time increases as the pressure inside the reactor increases. The oxide film formation rate, which is the growth thickness of the oxide film with respect to unit time, increases. Therefore, in the general AP-CVD apparatus, when the atmospheric pressure increases, the pressure of the reactor increases, so that the partial pressure of the reactor increases, and thus the oxide film growth rate increases.

5A to 5B are graphs illustrating a change in oxide film formation thickness over time using a general atmospheric chemical vapor deposition (Atmospheric Chemical Vapor Deposition) apparatus.

5A to 5B, in a typical AP-CVD apparatus, when the atmospheric pressures 500 and 520 decrease by about 1 kPa from about 100.5 kPa to 99.5 kPa, the pressure inside the reactor is simultaneously reduced, and the wet oxide film thickness 510 is reduced. It can be seen from FIG. The dry oxide film 530 also exhibits the same tendency and can be seen to change in proportion to atmospheric pressure.

6A to 6B are graphs showing trends of pressures of oxide film formation thicknesses using a general atmospheric chemical vapor deposition (Atmospheric Chemical Vapor Deposition) apparatus.

Referring to FIGS. 6A to 6B, as a result of linear regression analysis (minimum square method) using the results of FIGS. 5A to 5B, in the case of the wet oxide film 600 using water vapor, the deposition rate is about 1 kPa. In the case of the dry oxide film 610 using% 2 and H2 gas, the deposition rate increased by about 0.25% when the atmospheric pressure increased by about 1 kPa.

At this time, assuming that the atmospheric pressure is changed by 4 kPa for one year, when the wet oxide film is formed at 200 kPa, the thickness change of 8 kPa corresponding to 4% occurs only by the influence of atmospheric pressure even if the error of equipment or other process conditions is excluded.

On the other hand, the MP-CVD apparatus, unlike the AP-CVD apparatus, maintains a constant absolute pressure inside the reactor even when the external atmospheric pressure changes, so that the process conditions can be stably maintained. Does not cause In addition, since the reactor maintains a vacuum degree of about 70 to 80 kPa, it is possible to maintain a higher deposition rate than a general LP-CVD apparatus. In addition, since a lower vacuum degree is required than LP-CVD, the manufacturing cost of components constituting the device is lower than that of LP-CVD, thereby reducing the installation cost.

Example 2

7 is a schematic diagram of a parallel MiddlePressure Chemical Vapor Deposition apparatus according to Example 2 of the present invention.

Since Embodiment 2 shows the same performance as Embodiment 1 of the present invention, redundant descriptions will be omitted.

Referring to FIG. 7, a parallel MP-CVD apparatus includes a plurality of reactors R1, R2,..., Rn in which pressure and temperature are controlled to cause a reaction. In the exhaust ports E1, E2, ..., En of each of the plurality of reactors R1, R2, ..., Rn, one gas exhaust pipe P1, P2, ..., Pn is provided for each exhaust port. Attached. The respective reactors R1, R2, ..., are connected to the first inlet of the respective gas exhaust pipes P1, P2, ..., Pn connected to the respective exhaust ports E1, E2, ..., En. Absolute pressure regulating sections C1, C2, ..., Cn for regulating the pressure in Rn) are provided, respectively. End portions of the gas exhaust pipes P1, P2, ..., Pn are connected to one low vacuum pump (V). The exhaust of the low vacuum pump (V) is connected to the exhaust (U) of the semiconductor manufacturing equipment.

A single low vacuum pump (V) is used to simultaneously maintain the interior of multiple reactors in a vacuum state, and the absolute pressure inside the reactor is maintained by an absolute pressure control unit attached to each reactor. Since the degree of vacuum to be maintained inside the reactor is about 20 to 30 kPa lower than atmospheric pressure, only one vacuum pump can be used in connection with a plurality of reactors.

As described above, according to the present invention, the medium pressure chemical vapor deposition apparatus includes a low vacuum vacuum pump and an absolute pressure control unit capable of maintaining an absolute pressure of about 70 to 80 kPa, thereby regulating the pressure inside the reactor without being affected by atmospheric pressure. do.

As such, the vacuum pump and the absolute pressure control unit are provided to maintain the absolute pressure without reacting to the external pressure change, thereby removing the change in the thickness of the film due to the atmospheric pressure. Therefore, high reproducibility can be ensured and a reliable semiconductor device can be manufactured.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified without departing from the spirit and scope of the invention described in the claims below. And can be changed.

Claims (4)

A reactor including a reactor gas introduction nozzle; An exhaust port connected to the reactor and configured to discharge gas generated in the reactor to the outside; An absolute pressure control unit attached to the exhaust port to constantly adjust the pressure in the reactor to maintain a partial pressure of the reactor body; A gas exhaust pipe connected to the absolute pressure control unit and configured to exhaust the gas passing through the absolute pressure control unit to the outside; And And a low vacuum pump connected to an end of the gas exhaust pipe and configured to lower the pressure in the reactor. The medium pressure chemical vapor deposition apparatus according to claim 1, wherein the absolute pressure control unit maintains the pressure in the reactor at a pressure set in a range in which the difference between the pressure in the reactor and the atmospheric pressure is at least 20 kPa and at most 30 kPa. . The method of claim 1, wherein the reactor One quartz tube on which the wafer is loaded; A heating coil for forming a reaction temperature in the one quartz tube; A reaction gas inlet for introducing a reaction gas into the one quartz tube; A quartz gas nozzle present in said one quartz tube and introducing gas into said wafer; And And a by-product exhaust port for discharging the by-product generated in the one quartz tube. The medium pressure chemical vapor deposition apparatus according to claim 1, wherein the reactor is provided in plurality.