JPS5946088B2 - Gas phase reactor - Google Patents

Description

Detailed Description of the Invention The present invention introduces a gaseous body into a planar reaction chamber under reduced pressure or normal pressure, and forms a monocrystalline, polycrystalline, or amorphous solid on a substrate (wafer) installed in the reaction chamber. The invention relates to an apparatus for growing .

In a conventional planar vapor phase growth apparatus, the gas necessary for growth is introduced into the center of the upper electrode 2 or the center of the lower electrode 3 in the reaction chamber 1, as shown in the cross-sectional views of FIGS. 1 and 2. It is introduced through the gap between the electrode and the wall of the reaction chamber.

In addition, in FIGS. 1 and 2, 4 is a high frequency oscillator, and 5 is a high frequency oscillator.
denotes a heater, 63T39 a gas inlet, and 8 and Ba38b a gas outlet connected to an exhaust (vacuum) pump. In addition, these gases are exhausted from the periphery of the reaction chamber in the case of Figure 2 where the gas is introduced from the center of the reaction chamber 1, and in the case of Figure 1 where the gas is introduced from the periphery of the reaction chamber. In each case, exhaust air is discharged from the center of the reaction chamber. However, in such a gas introduction method, it is inevitable that the film thickness on the growing substrate becomes non-uniform along the direction of propagation of the introduced gas. Even if the non-uniformity of the grown film thickness is within an acceptable range, if two or more gases are used to grow a film of a compound or a mixture, the reaction may occur when the two or more gases are introduced. In some cases, a gas mixing chamber is installed along the path of the gases being introduced into the chamber, and the gases are introduced into the reaction chamber in a mixed state. Some may form solids before being introduced into the reaction chamber. Furthermore, even if the gas is not formed in the gas introduction tube, it is generated not only in the gas plasma reaction chamber excited by the high-frequency discharge generated by applying a high-frequency voltage between the electrodes, but also in the case where the gas is introduced into the reaction chamber through an opening. Since it also occurs strongly in pores, it forms solids at the pore openings.

These unexpected solids deposit on the substrate surface in the form of particles or flakes, but such deposition not only creates unnecessary irregularities in the grown film, but also affects the electrical, optical, and crystallographic properties of the film. will be significantly damaged. The present invention eliminates these drawbacks and provides an apparatus for producing plasma excitation or high-temperature crystalline or non-crystalline materials by introducing a desirable reactive gas, and will be described in detail below.

FIG. 3 is a sectional view of a plasma silicon nitride film growth apparatus embodying the present invention.

In this figure, a reaction chamber 1 made of stainless steel is evacuated by a vacuum pump through an exhaust pipe 10, and after reaching a predetermined reduced pressure state, the reaction gas is introduced from gas introduction pipes Al3 and Bl4 (by opening electromagnetic valves (not shown)). Introduced into the reaction chamber 1. Taking as an example the case where a Si3N4 film is grown on a Si substrate, NH3 (5% Ar diluted) 200ml/Mln gas is supplied from the gas introduction pipe Al3, and SiH4 (2% H2) is grown from the introduction pipe Bl4. dilution) 4001n
1,/Min, respectively. SlH4B gas is introduced from a high frequency power supply 12 with a frequency of 13.56 MHz through a matching circuit 11 to an electrode 2 to which a high frequency voltage is applied, and passes from a space 15 of the electrode through a circular small hole 16 with a diameter of 2 to 2.5 mm. For example, a sample holder (tray) 2 on a ground electrode 19 is rotated by a device 18 that externally rotates a rotating shaft inside a closed container using a magnet.
It collides with the substrate (wafer) 21 which is placed flat on the ground.
On the other hand, NH3 gas A is introduced into the space 17 of the electrode 2,
A donut-shaped small hole 22 with a width of 2 to 3 mm surrounds the circular small hole 16.
It collides with the substrate 21 through the. The circular small hole 16 and the donut-shaped small hole 22 are formed to eject gas almost perpendicularly to the substrate 21, and the distance d between the combination of the ejection holes and other combinations is 15 m7! A large number of electrodes are provided on the bottom surface of the electrode 2, as shown in FIG. FIG. 4 is a bottom view of the electrode 2 to explain the procedure, in which A represents the lower surface of the space 15 and B represents the lower surface of the space 17, respectively. Also, Figure 3 shows a case where the introduced gases are separated into two groups by two types or gases that do not react directly with each other, but if there are even more types and groups of gases, multiple pipes can be used. In this case, for example, it becomes a doughnut-like shape with multiple centers as shown in FIG. 4B, but the separate introduction of gas can be achieved in the same way.
Note that 23 in FIG. 3 represents an insulator in the upper part of the reaction chamber 1, and 24 represents a gate valve. Now, when a high frequency electric field is applied between the high frequency electrode 2 and the earth electrode 19, a gas glow discharge occurs at both electrodes, a gas plasma is formed, a chemical reaction occurs between SiH4 and NH3, and Si3
A thin film of H4 is formed on the substrate 21. In this way, each of the reaction gases is separated and sent to the reaction chamber,
In addition, the distribution of the gas flowing over the substrate is homogeneous, and the chemical reaction occurs only in the space on the substrate, so not only the thin film deposition rate is high but also a homogeneous film can be obtained. The above-mentioned problem of falling does not occur. The silicon nitride film with a thickness of 100 to 400 μm obtained when the substrate 21 is heated to 350 to 400° C. by the heater 5 has a stoichiometry extremely close to that of Si3N4.
The film surface had a refractive index of 2.0, a density of 2.8 to 3.0, and was an excellent nitride film with no cracks.
lcateglass,BSG(BOrOnsjllc
ateglass) growth, Pt silicide,
It is not only used for forming thin films such as TiW, but also GaA
It can be used to grow single crystal and polycrystalline thin films of compound semiconductors such as S, AsSe, etc.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a conventional planar vapor phase growth apparatus, FIG. 3 is a cross-sectional view of a plasma silicon nitride film growth apparatus in which the present invention is implemented, and FIG. 4 is an electrode surface shown in FIG. 3. FIG. 3 is a cross-sectional view of the electrode surface showing the gas ejection ports. 1... Reaction chamber, 2, 3... Electrode, 4,
12... High frequency oscillator, 5... Heating body, 6, 7, 8... Gas inlet, 8, 8a, 8b
...Gas exhaust port, 10...Exhaust pipe, 1
1...Matching circuit, 13...A gas introduction pipe, 14...B gas guide pipe, 15, 17
...Empty chamber (space) of electrode 2, 16...
... Small hole for B gas release, 19 ... Earth electrode,
20... Sample phase holder, 21... Wafer, 22... Small hole for A gas release of electrode 2.

Claims (1)

[Claims] 1. A gas separation passage for separating and introducing two or more types of gases that form a solid in an apparatus that converts and grows a gas into a solid by gas plasma or heating on the surface of a group of substrates in a reaction chamber. In addition, a gas injection surface is provided in which a plurality of gas injection ports are arranged concentrically and connected to each of the separation passages, and a plurality of gas injection ports are arranged adjacently so that the distance between the centers is a certain value or less. 1. A gas phase reaction device, which is disposed so as to face a plane on which a group of substrates is placed, and is characterized by ejecting a gas substantially perpendicularly toward the group of substrates.