JPH07118469B2 - Plasma CVD equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a plasma generation chamber, which is communicated through an opening and into which a film formation substrate is placed, and which is connected to the plasma generation chamber through the opening. In the plasma CVD apparatus that forms a thin film on the surface of the deposition target substrate by introducing the reaction gas activated by the plasma extruded into the reaction chamber from the outside, the reaction gas is introduced to the front side of the deposition target substrate. For the configuration of the introduction path for.

[Conventional technology]

FIG. 3 shows an example of the structure of the reaction gas introduction path in this type of plasma CVD apparatus. In the reaction chamber 1 that communicates with the plasma generation chamber 15 through the opening 14, the film formation substrate 2 is placed on the wafer stage 3 near the bottom of the reaction chamber, and the film formation substrate 2 is surrounded to react. An inside of the chamber 1 is provided with a deposition-inhibiting cylinder 11 for preventing a film from adhering to the inner wall of the reaction chamber, and a gas introduction pipe line 6 for introducing a reaction gas into the reaction chamber 1 inside the deposition-inhibiting barrel 11.
Is fixed in the reaction chamber by being screwed into a pipe joint 10 that penetrates the bottom of the reaction chamber in an airtight manner, and has a nozzle 9 made of a hollow member having a square cross section formed in an annular shape on the upper end face thereof.
Are attached so as to surround the film formation substrate 2.
A plurality of gas discharge ports 7 are formed in the nozzle 9 inside the ring at intervals in the circumferential direction, and the reaction gas introduced into the nozzle 9 through the gas introduction conduit 6 is discharged from the ring 7 through the ring. It is released inward. When the reaction gas 8 (for example, monosilane gas SiH ₄ etc.) is released and the plasma 5 is introduced from the plasma generation chamber 15 into the reaction chamber 1 kept at a predetermined gas pressure, the reaction gas is decomposed to form plasma, for example, By interacting with nitrogen ions, a SiN film is formed on the substrate surface. If the substrate is a semiconductor wafer, the film thickness should be uniform on the wafer surface. Although the mechanism of film formation has not been clarified in detail, it is considered that the reaction gas 8 should be uniformly discharged toward the substrate 2 in order to form a uniform film thickness. For this reason, a plurality of gas discharge ports are provided inside the nozzle formed in an annular shape so as to surround the substrate 2.

[Problems to be Solved by the Invention]

In the conventional device having such a configuration, the diameters of the plurality of gas discharge ports 7 of the annular nozzle 9 are changed so that the amount of gas discharged from each gas discharge port becomes equal. However, the film-forming results after removing the nozzle 9 for maintenance work of the reaction chamber or replacing it with another nozzle manufactured according to the same design drawing are different from those immediately before, even though the film-forming conditions are the same. There are cases. The cause is presumed to be as follows.

(1) The nozzle mounting position is misaligned when recombining.

(2) The inclination of the gas introduction pipe is slightly different at the time of recombination, which changes the gas emission direction, impairing uniform gas emission toward the substrate.

(3) When manufacturing the nozzle, a difference in diameter exceeding a predetermined difference occurs between the gas discharge ports having different diameters. For example, the difference between the prescribed diameter of a large-diameter gas outlet of 2.2 mm and the prescribed diameter of a small-diameter gas outlet of 1.8 mm exceeds 0.4 mm, and the diameter of the large-diameter gas outlet is the runout of the drill during machining. For example, it will be 2.5 mm, and the difference in diameter will be 0.7 mm, so
The amount of released gas becomes non-uniform.

It is an object of the present invention to solve the problem of nozzle position shift during rearrangement, to keep the discharge direction unchanged from before the rearrangement, and to solve the problem of error in the difference in the diameter of the gas discharge port. Is to provide.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, in the present invention, a film formation substrate is placed in communication with a plasma generation chamber through an opening, inside the same as the axis of the opening and at a suitable distance from the opening. At an intermediate position between the opening in the reaction chamber and the film formation substrate,
It is composed of a hollow member formed in a continuous annular shape or a divided annular shape and provided with a plurality of gas discharge ports in the circumferential direction, and is arranged so as to surround the deposition target substrate through a gas introduction passage penetrating the wall surface of the reaction chamber. In the plasma CVD apparatus equipped with a nozzle for feeding a reaction gas, the annular nozzle has a plurality of gas outlets all formed to have the same diameter, and the cross-sectional area of the circumferential passage is set to the conductance of the passage. On the other hand, the conductance of the gas discharge port is formed to a size that can be substantially ignored, and the support member is supported so that the axis of the ring matches the axis of the opening. The structure is configured to be connected via a flexible connection pipe to a gas introduction pipe line that is fixed as possible and penetrates the wall surface of the reaction chamber.

[Action]

By configuring the gas introduction path in this way, the reaction gas is introduced into the nozzle through the connection port with the flexible connection tube through a constant inflow cross-sectional area. The problem of the positional deviation between the gas introduction pipe line (6) and the nozzle is solved. Further, the annular nozzle supports so that the axis of the annulus coincides with the axis of the plasma generation chamber opening. For example, the annular nozzle has a circular peripheral wall whose axis coincides with the axis of the opening and has a supporting surface formed in the circumferential direction. Since it is fixed to the member, the discharge direction from the gas discharge port does not change with each replacement of the nozzle. Further, since the diameters of the gas outlets are all formed to be the same, the problem of the diameter difference between the gas outlets is solved, and the conductance of these gas outlets is compared with that of the circumferential flow passage of the nozzle. Since the cross-sectional area of the circumferential flow passage is formed to be substantially negligible, the amount of the reaction gas discharged from the gas discharge port becomes equal at all gas discharge ports. Here, the conductance will be described.

The conductance quantitatively represents the ease with which a fluid moves, and varies depending on the cross-sectional area, length, shape, etc. of the gas flow passage. The larger the conductance, the easier the gas moves.

Now, assume that the cross section and the overall shape of the nozzle are as shown in FIG. In FIG. 2, the length of the circumferential passage from the gas inlet 9a to the gas outlet 7 is l, and the diameter of the gas outlet is φ. Conductance C of the circumferential flow path at this time
_l is the following formula: Given by. Where a and b are the width and height [m] of the rectangular cross-section flow path, p ₁ and p ₂ are the nozzle internal pressure [Pa (Pascal)] at the nozzle inlet and gas outlet positions, respectively. K is a coefficient determined by the dimensions a and b.

Now, assuming that a = 10 × 10 ⁻³ [m] and b = 40 × 10 ⁻³ [m], and that the pressure gradient in the circumferential flow passage of the nozzle is small, p ₁ p ₂
If = 13.3Pa (= 100mTorr), Therefore, as the value of l, l ₁ = 61 × 10 ⁻³ [m], l ₂ = 123
× 10 ^-3 [m], Becomes The conductance C _φ of the gas outlet is given by the following formula: W × C _φ = 1.7 × 10 ⁻⁶ (5), and the diameter φ ₁ of the gas outlet closer to the gas inlet 9a of the nozzle is φ ₁ = 2.5. If x10 ^-3 [m] and the wall thickness of the gas discharge port (hole length) W = 2 x 10 ^-3 [m], then (5)
From the formula, Becomes Therefore, in order to equalize the amounts of the reaction gases released from the two gas outlets, it is necessary to determine the diameter of the second outlet so that the combined conductances become equal. That is, From equation (8), Ie Since the lengths W of the holes are equal, φ ₂ φ ₁ is obtained.
As described above, when C _l and C _φ are significantly different, the amount of gas released by equalizing the diameters of the plurality of gas outlets becomes equal in all the gas outlets, according to the equation (7). I understand.

〔Example〕

FIG. 1 shows an embodiment of the gas introducing passage structure according to the present invention. In the figure, the same members as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. The nozzle 19 in which a plurality of gas discharge ports 17 of the same diameter are formed in the circumferential direction is a circular ring having a square flow passage cross section and a large flow passage cross sectional area, as shown in FIG. Has been formed. This ring is a metal block machined to accurately finish the mounting surface on the shelf 21a, which is formed inside the deposition-inhibiting cylinder 21 whose inner diameter matches the outer diameter of the ring and which forms a circumferential support surface. It is processed and produced. In this example, the depth of b /
After forming 2 circular grooves (see Fig. 2), cut out an annulus so that the wall thickness is W, make two of them, and stack them with the groove sides facing each other. One divided annular nozzle is formed by welding and dividing into two in the diameter direction. The gas introduction pipe line 16 for introducing the reaction gas into the reaction chamber 1 from the outside is formed shorter than before, and both ends of the flexible connection pipe 12 are connected to the upper end portion and the inlet of the nozzle 19, respectively. It

〔The invention's effect〕

As described above, according to the present invention, the deposition target substrate is arranged in communication with the plasma generation chamber through the opening, inside the same coaxial with the axis of the opening, and appropriately separated from the opening. A hollow member, which is formed in a continuous annular shape or a divided annular shape and has a plurality of gas discharge ports in the circumferential direction, is provided at an intermediate position between the opening in the reaction chamber and the deposition target substrate so as to surround the deposition target substrate. A plasma CVD apparatus equipped with a nozzle which is arranged and into which a reaction gas is fed through a gas introduction pipe line which penetrates the wall surface of the reaction chamber, wherein the annular nozzle forms a plurality of gas emission ports all having the same diameter. And the cross-sectional area of the circumferential flow passage is formed in a size such that the conductance of the gas discharge port can be substantially ignored with respect to the conductance of the flow passage,
A gas introducing pipe line that is detachably fixed to a supporting member that has a supporting portion formed in the circumferential direction and that penetrates through the reaction chamber wall surface and that is supported so that the axis of the ring matches the axis of the opening. Since it is configured to be connected via the connection pipe of (1), the reaction gas is always introduced into the nozzle from the inlet formed in the nozzle through a constant flow passage cross section. As described above, there is no change in the inflow cross-sectional area due to the positional deviation from the gas introduction pipe line when reassembling after the nozzle is disassembled or when the nozzle is reconfigured to another nozzle by the same design drawing.

(2) Since the annular nozzle is fixed to a support member that is particularly limited so that the axis of the annular ring coincides with the axis of the plasma generation chamber opening, the plane of the annular ring may tilt during reassembly or reassembly after disassembly. Is eliminated, and the gas discharge direction is always kept constant.

(3) Since the cross-sectional area of the circumferential flow passage of the nozzle is set so that the conductance of the gas discharge port can be substantially ignored with respect to the conductance of the flow passage, the amount of gas discharged from the gas discharge port is made equal. However, the diameters of the gas outlets can all be made the same, and the problem of the diameter difference between the gas outlets as in the conventional case can be solved.

That is, with the configuration of the gas introduction passage according to the present invention, a uniform flow of the reaction gas can always be stably formed on the front surface side of the film formation substrate. Since the nozzle and the gas introduction pipe for introducing the reaction gas into the reaction chamber are connected via a flexible connecting pipe, the inclination of the gas introduction pipe during reassembly has an influence on the gas discharge direction. It is also possible to obtain the merit in the work such that the reassembling can be performed without worrying about reassembling.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the gas introduction path configuration according to the present invention, in which (a) is a vertical cross-sectional view of the reaction chamber, and (b) is the arrow direction at the position AA in the previous figure (a). FIG. FIG. 2 is a diagram for explaining the conductance of the gas flow path, in which (a) is a plan view showing a configuration example of an annular nozzle and a position example of a gas discharge port, and (b) is a front view (a). FIG. 7B is an enlarged cross-sectional view of the nozzle as seen in the direction of the arrow at the position BB in FIG. FIG. 3 is a diagram showing a configuration example of a conventional gas introduction path, in which (a) is a vertical cross-sectional view of the reaction chamber, and (b) is seen in the direction of the arrow at the CC position in the previous figure (a). FIG. 1: Reaction chamber, 2: Substrate (deposition substrate), 5: Plasma, 6, 16:
Gas introduction pipe line, 7, 17: Gas discharge port, 8: Reaction gas, 9, 19: Nozzle, 12: Connection pipe, 14: Opening, 15: Plasma generation chamber.

Claims (1)

[Claims] 1. An opening in a reaction chamber in which a film formation substrate communicates with a plasma generation chamber through an opening, is coaxial with the axis of the opening, and is appropriately spaced from the opening, and the film is formed in the reaction chamber. At the intermediate position of the substrate, a hollow member formed in a continuous annular shape or a divided annular shape and provided with a plurality of gas discharge ports in the circumferential direction is arranged so as to surround the film formation target substrate, and the wall surface of the reaction chamber is formed. In a plasma CVD apparatus equipped with a nozzle into which a reaction gas is fed through a gas introduction pipe line that penetrates, the annular nozzle has a plurality of gas discharge ports all formed with the same diameter and the circumferential flow path is cut off. A supporting portion in the circumferential direction, the area of which is formed so that the conductance of the gas discharge port can be substantially ignored with respect to the conductance of the flow path, and the axis of the annular ring is aligned with the axis of the opening. Support member formed with Plasma CVD apparatus characterized by being connected detachably fixed through the gas inlet pipe and a flexible connection tube which penetrates the reaction chamber wall.