KR100542890B1 - Manufacturing method of guided polycrystalline silicon film_ - Google Patents

Abstract

The present invention relates to a method of manufacturing a guided polycrystalline silicon film used as a micro structure material such as a microsensor, comprising: forming a sacrificial layer film (SiO ₂ ) on a silicon substrate using a silicon oxide film; In the upper part of the chamber, a large ring-shaped raw material gas injection tube 3 is disposed, and at the center side thereof, a small ring-shaped base gas injection tube 7 is disposed, and then a silicon substrate 4 having a sacrificial film is mounted in the chamber. Heating to a substrate temperature of ˜700 ° C. and simultaneously injecting silicon-containing gas and phosphorus-containing gas into the silicon substrate 4 at a pressure of 1 torr to deposit a guided polycrystalline silicon film on the sacrificial layer film; Inducting with the specific resistivity and residual stress minimized by manufacturing a guiding polycrystalline silicon film by performing a heat treatment step of rapidly heating the substrate on which the guiding polycrystalline silicon film is formed to a temperature of 900 ° C. in a reducing atmosphere for 30 to 60 seconds. A polycrystalline silicon film can be produced, and such a polycrystalline silicon film has a useful effect that can be applied to a structure such as micromachining.

Description

Manufacturing method of guided polycrystalline silicon film

The present invention relates to a method of manufacturing a guided polycrystalline silicon film used as a microstructure material such as a microsensor, and more particularly, by depositing a guided polycrystalline silicon film directly on a substrate on which a sacrificial layer thin film is formed, A method of manufacturing a guided polycrystalline silicon film capable of maintaining resistivity and minimizing internal residual stress.

In general, guided polycrystalline silicon is a material widely used in the semiconductor industry such as integrated circuits, micromachining, sensors, transistors, solar cells, and the like. In recent years, the fabrication of micromachining structures has been disclosed. 8th Conference Sensor and Actuator. 25 (1995) 198) In view of the sensitivity of the structure, the thickness is as thick as possible (about 2 to 10㎛), and the in-situ polycrystalline silicon film with low specific resistance and low residual stress is required.

Conventionally, a method of manufacturing a guided polycrystalline silicon film is divided into two methods: depositing an undoped-poly Si film on a sacrificial layer thin film, doping with phosphorus in a furnace, or depositing a guided silicon amorphous film. Can be. First, as shown in FIG. 1, a silicon oxide film as a sacrificial layer thin film is grown on a silicon substrate, and an undoped-poly Si film is deposited on the sacrificial layer thin film, followed by rapid thermal treatment of a polycrystalline silicon film in a furnace to diffuse phosphorus. The method is to deposit a silicon polycrystalline film at a temperature of 625 to 650 ° C. and heat-treat the substrate on which the sacrificial layer film is formed, and then to diffuse the fockle (POCI ₂ ) to 900 to 1000 ° C. in an electric furnace. Since the stress distribution is not uniform, the overall resistivity distribution is not uniform, and there is a disadvantage in that a large compressive stress remains among the residual stresses, so there is a problem in that the sensitivity is poor as a structure of micromachining.

Next, as shown in FIG. 2, a silicon oxide film, which is a sacrificial layer film, is grown on a silicon substrate, and a guided amorphous silicon film is deposited directly on the sacrificial layer film, followed by rapid thermal treatment to obtain a micromachining structure. A guiding amorphous silicon film is formed on the sacrificial layer film at a temperature of 610 ° C. at a pressure of 0.1 to 0.3 torr, and then subjected to heat treatment to polycrystallize. The advantage is that tensile stress is low in residual stress. Therefore, when manufacturing a film having a thickness of 2 μm or more due to the small deposition rate, there was a drawback that the process time should be kept long. In general, when the process time is long, a large amount of process source and gases are consumed, and unnecessary particles are generated, which may be incorporated into the film formation as a source of contamination.

In view of the above circumstances, the present invention has been conducted based on the results of research and experiments to solve the problems of the conventional method of manufacturing a guiding polycrystalline silicon film, and has a constant, low specific resistance and minimum residual stress. Its purpose is to provide a method for producing a ping polycrystalline silicon film.

In order to achieve the above object, the present invention provides a method of manufacturing a guided polycrystalline silicon film comprising: forming a sacrificial layer film (SiO ₂ ) as a silicon oxide film on a silicon substrate; In the upper part of the chamber, a large ring-shaped raw material gas injection tube 3 is disposed, and at the center side thereof, a small ring-shaped base gas injection tube 7 is disposed, and then a silicon substrate 4 having a sacrificial film is mounted in the chamber. Heating to a substrate temperature of ˜700 ° C. and simultaneously injecting silicon-containing gas and phosphorus-containing gas into the silicon substrate 4 at a pressure of 1 torr to deposit a guided polycrystalline silicon film on the sacrificial layer film; The substrate on which the guided polycrystalline silicon film is formed is rapidly heated to a temperature of 900 ° C. in a reducing atmosphere.

Silicon-containing gas is injected into the source gas injection pipe 3, phosphorus-containing gas is injected into the base gas injection pipe 7, and silicon-containing gas and phosphorus-containing gas are injected and injected together onto the substrate. An in-doped polycrystalline silicon film is deposited, wherein the silicon-containing gas is either SiH ₄ or SiCl ₂ H ₂ , and the phosphorus-containing gas is PH ₃ .

Hereinafter, the present invention will be described in detail.

Generally, residual stress occurs in the guided polycrystalline silicon film 1). Difference in thermal expansion coefficient between substrate and guided polycrystalline silicon film, 2). Distribution of phosphorus along the longitudinal direction of the polycrystal, 3). It is known that a difference in deposition temperature occurs in the radial direction of the substrate when the guided polycrystalline silicon film is deposited.

The present invention is to control the guided polycrystalline formation conditions so as to suppress the causes caused by 2). And 3). Among the causes of the residual stresses, and to heat-treat to minimize the residual stresses inevitably generated.

That is, the present invention has a feature of providing a 2-10 μm thick guided polycrystalline film having a minimum resistivity and residual stress on a silicon substrate on which a sacrificial layer film is formed by depositing a silicon oxide film on a silicon substrate. This is made possible through the heat treatment to remove the residual stress and the conditions for injecting the silicon-containing gas and phosphorus-containing gas at the formation temperature and pressure of the guided polycrystalline silicon film of the present invention.

In order to form a guided polycrystalline silicon film according to the present invention, it is necessary to first form a silicon oxide film as a sacrificial layer film on a silicon substrate, and the silicon oxide film can be formed by any of the usual methods of dry oxidation and wet oxidation. The wet oxidation method that can form a thicker is more advantageous.

As described above, the silicon substrate 4 having the sacrificial layer film formed thereon is mounted in the reaction chamber 1 in the bell jar 2, which is a single-layer low pressure chemical vapor deposition equipment chamber as shown in FIG. 3, and is rapidly heated with a SiC heater 6. The silicon substrate 4 is heated by heat transfer through the susceptor 5. At this time, due to the temperature difference in the length and radial direction of the silicon substrate, the deposited stressed polycrystalline silicon film may have a very large difference in residual stress and resistivity. In order to prevent this, a large ring-shaped raw material gas injection tube 3 is disposed on the upper part of the chamber, and a small ring-shaped base gas injection tube 7 is disposed at the center thereof, and then a pressure of 1 torr is applied at a substrate temperature of 650 to 700 ° C. Silicon-containing gas such as SiH ₄ or SiCl ₂ H ₂ is injected and injected into the silicon substrate 4 through the base gas injection tube 7 while the doped phosphorus-containing gas of PH ₃ is injected through the base gas injection tube 7 while maintaining Therefore, by depositing the guided polycrystalline film on the sacrificial layer film, the thickness uniformity of the polycrystalline film generated due to the temperature difference in the substrate is greatly improved, and the phosphorus distribution in the polycrystalline film is uniform, thereby reducing the residual stress and the resistivity difference in the film. In addition, since PH ₃ gas is injected and deposited in the center of the substrate, the amount of indoping in the polycrystalline film increases, thereby reducing the overall specific resistance and reducing the residual stress.

As described above, the doped personnel may heat the guided polycrystalline film deposited on the sacrificial layer film to find the lattice sites, thereby reducing the specific resistance by 10 times and reducing the residual stress inside the polycrystalline film caused by thermal stress. Such a heat treatment method is a rapid heating in a reducing atmosphere, and the rapid heating may be a speed capable of inhibiting grain growth of the polycrystalline silicon film as much as possible, and according to an embodiment of the present invention, it is preferable to set it to 100 ° C / sec or more.

As described above, it is preferable to rapidly heat up to a temperature of 900 ° C., and to maintain the temperature for 30 to 60 seconds to reduce the resistivity and to remove the residual stress, because the holding temperature is less than 900 ° C. If the holding time is less than 30 seconds, there is no effect of reducing the specific resistance and removing residual stress. If the temperature or the holding time is longer than 60 seconds, phosphorus may diffuse out of the silicon film and the specific resistance may increase.

Next, the present invention will be described in detail through examples.

EXAMPLE

The silicon substrate used in this embodiment is a 4-inch n-type (100) substrate, which is a substrate in which a thermal oxide film is grown to a thickness of 1.5 mu m by a wet oxidation method. Thus, heat only the silicon substrate is mounted attached to the chamber of the prepared single-wafer silicon substrate low-pressure chemical vapor deposition apparatus of SiC heating element heater and comparing material containing silicon of the SiH ₄ to the temperature and the 1torr pressure of 650 ℃ on the silicon oxide film After spraying only the gas and depositing an undoped-poly Si film, rapid heat treatment was performed, and then the fockle (POCI ₂ ) was diffused at 1000 ° C. for 1 hour in an electric furnace. In addition, the gas injector was equipped with a large ring-shaped raw material gas inlet tube 3 at the top of the chamber, and a small ring-shaped base gas inlet tube 7 at the center thereof as shown in FIG. While maintaining the pressure, a silicon-containing gas of SiH ₄ was injected into the source gas injection tube _{3 and} a doping gas of PH ₃ was injected through the base gas injection tube 7 to deposit a guided polycrystalline silicon film on the silicon oxide film. . However, the flow rate of SiH ₄ at step was fixed at 60sccm, bar, PH ₃ and a relative molar ratio of SiH ₄ 5.56 × 10 ^-4 hayeotneun to change the flow rate of PH ₃ to change the relative molar ratio of PH ₃ and SiH ₄ The guided polycrystalline silicon film was deposited at 3.33 × 10 ⁻³ .

After the deposition of the guided polycrystalline silicon film, as described above, the rapid heat treatment was performed at a rate of 100 ° C./sec in the rapid heat treatment apparatus and heat-treated in a reducing atmosphere at a temperature of 900 ° C. for 30 to 60 sec. The physical properties of the guided polycrystalline silicon film thus produced were measured for each manufacturing step, and the results are shown in Table 1. In Table 1 the molar ratio is the relative molar ratio of PH ₃ and SiH ₄ , ie PH _{3 /} SiH ₄ .

division Deposition conditions (670 ℃, 1torr) Deposition rate (Å / min) Before heat treatment After heat treatment After diffusion Resistivity (mΩ.cm) Residual stress (MPa) Resistivity (mΩ.cm) Residual stress (MPa) Resistivity (mΩ.cm) Residual stress (MPa) Comparative material Molar ratio = 0. 420 - -160 - -100 1.8 -45 Invention material Molar ratio = 5.56 × 10 ^-4 323 10 110 0.75 -15 - - Molar ratio = 3.33 × 10 ^-3 138 10 105 0.58 -12 - -

As can be seen from Table 1, the deposition rate of undoped polycrystalline silicon at 675 ° C. and 1torr is 420 Å / min, and the deposition rate is 323 Å / min when the molar ratio of PH ₃ and SiH ₄ is 5.56 × 10 ^−4. It can be seen that the molar ratio of PH ₃ to SiH ₄ decreased to 138 dl / min when the fold ratio was increased 6 times to 3.33 × 10 ⁻³ . As the molar ratio increases, the deposition rate tends to decrease more at high temperatures with faster deposition rates. PH ₃ has a high adsorption force on the surface of the silicon substrate, thereby limiting the number of digits on which the surface of SiH ₄ can reach, thereby inhibiting nucleation required for growth of polycrystalline silicon, thereby reducing the deposition rate. The resistivity value of the guided polycrystalline silicon film in the deposited state was about 10 mΩ.cm, and the resistivity value after rapid heat treatment at 900 ° C. for 60 seconds decreased to about 1 mΩ.cm or less.

As described above, according to the present invention, it is possible to manufacture a guided polycrystalline silicon film having a minimum resistivity and residual stress, and the polycrystalline film has a useful effect that can be applied to a structure such as micromachining.

1 is a process flow chart showing a conventional guided polycrystalline silicon film manufacturing process

Figure 2 is another process flow chart showing a conventional guided polycrystalline silicon film manufacturing process

Figure 3 is a schematic view showing a gas injector in the chamber which is a low-pressure chemical vapor deposition equipment employed in the present invention

4 is a process flowchart showing a manufacturing process of the present invention-doped polycrystalline silicon film.

<Explanation of symbols for main parts of drawing>

1: reaction chamber 2: chamber

3: source gas injection pipe 4: silicon substrate

5: susceptor 6: SiC heater

7: base gas injection pipe 3 ', 7': gas injection port

Claims (4)

Forming a sacrificial layer film (SiO ₂ ) on a silicon substrate with a silicon oxide film; In the upper part of the chamber, a large ring-shaped raw material gas injection tube 3 is disposed, and at the center side thereof, a small ring-shaped base gas injection tube 7 is disposed, and then a silicon substrate 4 having a sacrificial film is mounted in the chamber. Heating to a substrate temperature of ˜700 ° C. and simultaneously injecting silicon-containing gas and phosphorus-containing gas into the silicon substrate 4 at a pressure of 1 torr to deposit a guided polycrystalline silicon film on the sacrificial layer film; And a heat treatment step of rapidly heating the substrate on which the guided polycrystalline silicon film is formed to a temperature of 900 ° C. in a reducing atmosphere for 30 to 60 seconds. 2. The silicon-containing gas and the phosphorus-containing gas according to claim 1, wherein silicon-containing gas is injected into the source gas injection pipe 3, phosphorus-containing gas is injected into the base gas injection pipe 7, A method of manufacturing a guided polycrystalline silicon film, characterized in that a jet injection is used to deposit a guided polycrystalline silicon film on a silicon substrate. The method of claim 1, wherein the silicon-containing gas is either SiH ₄ or SiCl ₂ H ₂ , and the phosphorus-containing gas is PH ₃ . The method for producing a guided polycrystalline silicon film according to claim 1, wherein the phosphorus-containing polycrystalline silicon film has a thickness of 4 to 7 µm.