JPS6357775A - Cvd thin film forming device - Google Patents

Abstract

PURPOSE:To prevent the formation and sticking of flakes of fine foreign matter particles to nozzle ends and inside wall surface by providing many pieces of reactive gas feed nozzles into coaxial multiple-layer structure to the central top of a bell-jar and providing plural pieces of the respective gas supply ports thereof symmetrically with the central axis of the nozzles. CONSTITUTION:Three piece of the reactive gas feed nozzles 20, 30, 40 are arranged in the coaxial multi-layer structure to the central top of the bell-jar 3 and four pieces of the gas supply ports 24, 34, 44 are respectively provided symmetrically with the central axis of the nozzles on the outer peripheral face of disk-shaped gas reservoirs 22, 32, 42 of the respective nozzles 20, 30, 40. Gaseous O2 is fed from a 1st nozzle 20 and the 3rd nozzle 40 respectively and the reactive gas such as SiH4 and/or PH3 except O2 is fed from the 2nd nozzle 30 to form the thin film on a wafer in the above-mentioned constitution. The formation and sticking of the flakes of fine oxide particles of SiO2, SiO,etc., on the nozzle ends and the inside wall surface are thereby effectively prevented and the flow velocity of the reactive gas fed into the furnace is kept constant. The thin film having a uniform film thickness is thus formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a CVD thin film forming apparatus. More specifically,
The present invention relates to a CVI) thin film forming apparatus that prevents the formation and adhesion of foreign particle flakes such as SiO or 5i02 on the wall surface and tip of a reaction gas feed nozzle of a reactor.

[Prior Art] One of the methods widely used in the l-conductor industry as a method for forming thin films is chemical vapor deposition (CV).
I):Chemical Vaporl)el)o
There is a location). CVD refers to turning a gaseous substance into a solid substance through a chemical reaction, and depositing the solid substance on the substrate F.

Characteristics of CVD are that various thin films can be obtained at deposition temperatures considerably lower than the melting point of the thin film to be grown;
The purity of the grown thin film is high, and the electrical properties are stable even when grown on a thermal oxide film of Si or Sih.
It is widely used as a passivation film on semiconductor surfaces.

Thin film formation by CVD is performed, for example, by supplying a reactive gas (for example, 5iHq+02. or S i Ha +PH,l +02 ) to a wafer heated to about 500°C. The reaction gas described in Section 1 is blown onto the wafer in the reactor to form a thin film of 5i02 or phosphosilicate glass (PSG) on the surface of the wafer. Also,
Two-layer film formation of SiO2 and PSG is sometimes performed.

Historically, molybdenum.

It can also be used to form metal thin films such as tungsten or tungsten silicide.

FIG. 3 shows a partial cross-sectional view of an example of an apparatus conventionally used for performing such a thin film forming operation using CV I).

In FIG. 3, the reactor 1 includes a circular buffer 2 covered with a bell jar 3, and a ring-shaped wafer mounting table 4 around the buffer 2, which is rotatably driven by a drive mechanism 5 or can rotate around its axis. to be installed. The bell jar 3 is connected to the reactor intermediate ring 12 via an O-ring 11. intermediate ring 1
A reactor main body 13 is disposed at the bottom of the reactor 2 via an O-ring 14.

An inner bell jar 15 is fixedly installed inside the bell jar to regulate the flow of reaction gas to suit the film forming reaction.

Reaction gas feed nozzles 8 and 9 are connected to the vicinity of one point of the bell jar 3.The gas fed from the gas feed nozzles is distributed by a buffer and directed to the wafer mounting table 4. The gases SiH4 and 02 must be fed into the reactor through separate gas feed nozzles. For example, 5iHq is fed through feed nozzle 8, and 02 is fed through feed nozzle 9. , PHJ can be sent together with S I H4.

A heating means 10 is provided directly below the wafer mounting table 4 via a small gear knob, and heats the wafer 6 to a predetermined temperature (for example, about 500° C.). The reaction gas (for example, Si
H4+02 or 5iHq +PH,3+02') flows down in the furnace as shown by the dotted arrow, touches the surface of the wafer 6 and flows, and the substance produced by the chemical reaction (Si02
or PSG) is formed on the surface of the wafer 6.

[Problems to be Solved by the Invention] However, the reaction gas feeding nozzle of such a conventional CV thin film forming apparatus had a structure as shown in FIG. 5iHq and/or PH from the inner nozzle tip, ? When the contained gas is introduced, it reacts with the oxygen gas introduced from the outer nozzle tip, and flakes of SiO or 5IIi material such as 5i02 are formed at the tips of the inner and outer nozzles and on the inner wall surface of the outer nozzle. is generated and arrives in season.

These flakes are separated by a jet of reactant gas,
It was blown away and traveled 17 times inside the furnace. Then, it gradually settles and falls and adheres to the surface of the wafer.

When these flakes adhere to the surface of the wafer, wafer 1-
This causes pinholes in the CVD film, which is a major cause of lower product yield.

Further, as shown in the figure, in the conventional nozzle, the gas supply [1] to the nozzle was -, so the gas flow rate was not uniform. As a result, the thickness of the CVD film formed on the wafer [-] tended to be non-uniform.

[Objective -1 of the invention] Therefore, the purpose of the present invention is to prevent the formation of flaky snow near the reactant gas feed nozzle, and to improve the CVD film by uniformizing the gas flow velocity. It is an object of the present invention to provide a C V l) thin film forming apparatus that makes the film thickness uniform.

[Means for Solving the Problems] As a means for solving the above-mentioned problems and also achieving the object of the present invention, this invention provides a CVf having a reaction gas feeding nozzle at the center top of the bell jar) In the thin film forming apparatus, the reaction gas supply nozzle is formed by coaxially arranging three or more nozzles, and a plurality of gas supply ports to each nozzle are arranged on the outer peripheral surface +1 of the nozzle symmetrically with respect to the central axis of the nozzle. C VI I) Provides a thin film forming apparatus characterized in that the thin film forming apparatus is individually arranged.

[Operation] As described above, the nozzle in the CV I) thin film forming apparatus of the present invention has a coaxial multiple structure.

As a result of extensive prototyping and research conducted by the inventors over many years, we found that when a reactive gas other than 02, such as SiH4+ or PH3'V'', comes into contact with the nozzle tip and inner wall surface, oxides form on that part. It was discovered that foreign substances are generated and attached.

Based on this discovery, by creating a nozzle with a multilayer structure, reactive gases other than oxygen are surrounded and isolated by oxygen gas and supplied into the furnace, and reactive gases other than oxygen come into contact with the tip of the nozzle and the inner wall surface. I succeeded in evoking something to do.

Although this is just a hypothesis, the OH- groups present near the tip and inner wall surface of the nozzle chemically react with floating SiO to generate SiO2 particles at the tip and inner wall surface of the nozzle. In addition, floating 5i02 particles react with the OH- groups and adhere to the tip and inner wall surface. This phenomenon results in electrical transformation, which gradually forms flakes on the tip and inner wall surface of the nozzle. On the other hand, if 02 molecules are present at the tip and inner wall of the nozzle, 02 and OH- groups will react to form H2O,
The OH- group, which has strong chemical activity, disappears. Therefore, by using oxygen as the isolation gas, the degree of adhesion of SiO2 particles to the nozzle tip and inner wall surface is reduced, making it difficult to form flakes.

As a result, it is effectively prevented that any flakes of oxide fine particles such as SiO or 5i02 are formed and adhered to the tip and inner wall surface of the nozzle.

This also effectively prevents the disadvantageous 1EflJ in which flakes fall onto the wafer surface and cause pinholes in the CVD film of the wafer.

Historically, a plurality (for example, four) of gas supply ports for supplying gas to each nozzle are arranged at equal intervals on the outer peripheral surface of the nozzle. Therefore, the flow rate of the reaction gas fed into the furnace becomes constant, and the uniformity of the thickness of the CVD film formed on the surface of the wafer can be improved.

In this way, not only can the wafer manufacturing yield be increased, but also the throughput of the entire semiconductor device manufacturing process can be improved.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in more detail while referring to the drawings.

FIG. 1 is a sectional view of a nozzle in the CVD thin film forming apparatus of the present invention, and FIG. 2 is a 11-plane view thereof.

As shown in FIG. 1, the nozzle of the CV I) thin film forming apparatus of the present invention is a first nozzle 20. Three nozzles, the second nozzle 30 and the third nozzle 40, are arranged coaxially.

02 gas is fed from the first nozzle 20, and the second nozzle 3
From the third nozzle 40, a reaction gas other than 02 such as SiH4 and/or PHa is fed, and from the third nozzle 40, 02 gas is fed. Thus, 5iHq and/or PHJ is 0
The gas is sandwiched between the two gases and sent into the furnace.

As a result, the reactive gas such as 5iHq and/or PHa cannot come into contact with the tip and inner wall of the nozzle, so foreign substances such as flakes are hardly generated or attached to these parts.

Although the flow rate of the gas sent from each nozzle is not particularly limited, the flow rate of the 02 gas sent from the first nozzle and the third nozzle is the same as that of the SiH4 gas sent from the second nozzle and/or
Alternatively, if the flow rate is higher than that of PHJ, the effect of isolating the reaction gas increases.

Disc-shaped gas reservoirs 22, 32 and 42 are disposed in one part of each nozzle. Gas supplies 1'-124, 34 and 44 are disposed on the outer peripheral surface of this gas reservoir.

As shown in FIG. 2, a plurality of gas supply ports are arranged at equal intervals on the outer peripheral surface of the disc-shaped gas reservoir. For example, four gases are supplied to the outer peripheral surface of the gas reservoir 22 of the first nozzle 20.
24, 24. 24 and 24 are symmetrically fixed in a 90° arrangement. Similarly, the gas reservoir 32 of the second nozzle 30 and the gas reservoir 42 of the third nozzle 40 each have four gas supply ports symmetrically fixed at a 90° arrangement.

The larger the number of gas supply ports installed, the faster the gas supply flow rate will be.
This is preferable because it allows for chemotaxis. The number of gas supplies [1] can be changed depending on the nozzle.For example, the first and third nozzles that feed 02 are each provided with four gas supplies [1], and SiH4 and PHa It is also possible to arrange three gas supplies 11 in the second nozzle for feeding the gas.

Although the materials of the nozzle, gas reservoir, and gas supply 1-1 are not essential to the present invention, it is preferable to use stainless steel with excellent corrosion resistance. Furthermore, the diameter and size of the nozzle, gas reservoir, and gas supply 1-1 can be changed depending on the capacity of the reactor to which it is attached. Therefore, the nozzle, gas reservoir and gas supply 1-
The diameter, size, etc. of 1 are °1f terms that can be easily determined by those skilled in the art.

[Effects of the Invention (1) As explained above, the nozzle in the thin film forming apparatus (CVI) of the present invention has a coaxial multiple structure.

As a result of extensive prototyping and research conducted by the inventors over many years, we found that when a reactive gas other than 02, such as St 84 or PHJ, comes into contact with the nozzle tip and inner wall surface, oxides form in that area. It was discovered that foreign substances are generated and attached.

Based on this discovery, by creating a nozzle with a multilayer structure, reactive gases other than oxygen are surrounded and isolated by oxygen gas and supplied into the furnace, and reactive gases other than oxygen come into contact with the tip of the nozzle and the inner wall surface. succeeded in preventing him from doing so.

Although this is just a hypothesis, the OH- groups present near the tip and inner wall surface of the nozzle chemically react with the free Si0 to generate 5i02r at the tip and inner wall surface of the nozzle. In addition, 77 free SiO2 particles react with the OH- groups and adhere to the tip and inner wall surface. This phenomenon changes and gradually forms flakes on the tip of the nozzle and on the inner wall surface 1-. On the other hand, if 02 molecules are present at the tip and inner wall surface of the nozzle, 02 and OH- groups will react to form H2O, and the highly chemically active OH'' groups will disappear.For this reason, By using oxygen as the isolation gas, the degree of adhesion of Si02 particles to the nozzle tip and inner wall surface is reduced, making it difficult to form flakes.

As a result, flakes of fine oxide particles such as SiO or 5i02 are formed on the tip of the nozzle and on the inner wall surface 1-.
Adhesion is effectively prevented.

In addition, this effectively prevents inconvenient problems such as flakes falling onto the wafer surface and causing pinholes in the wafer's CVI) film. be done.

In history, a gas supply [-1] that supplies gas to each nozzle is provided at multiple (for example, 4) locations at equal intervals on the outer circumferential surface of the nozzle -1-.
It is arranged. Therefore, the flow rate of the reaction gas fed into the furnace is constant, and the surface of the wafer 1.

It is possible to improve the uniformity of the film thickness of the CVI) film formed on the substrate. In particular, when using an impurity such as PHa mixed in the reaction gas, generally a very small amount (11
Shika41! Therefore, if the flow rate into the reactor is uneven, there is a strong tendency for the impurity concentration to become uneven. but,
According to the apparatus of the present invention, even impurity gases that are mixed in only a very small amount can be subjected to a film forming reaction at a constant concentration.

In this way, not only can the manufacturing yield of wafers be increased, but also the throughput of the entire semiconductor device manufacturing process can be improved.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the nozzle in the CV l) thin film forming apparatus of the present invention, Figure 2 is its P side view, and Figure 3 is the conventional CV l)
Vl) It is a schematic diagram of a thin film forming apparatus. 1...JX Okoro T 2...Buffer, 3...
Bellja. 4... Wafer mounting table, 5... Drive mechanism, 6... Wafer. 8 and 9... Reaction gas feed nozzle, 10... Heating stage, 11 and 14... O ring, 12... Intermediate ring, 13... Reactor main body, 15... Inner Bellja. 20... First nozzle, 22... Gas reservoir for the first nozzle. 24... Gas supply port, 30... Second nozzle. 32... Gas reservoir for second nozzle, 34... Gas supply 1-1° 40... Third nozzle, 42... Gas reservoir for third nozzle. 44...Gas supply []

Claims (2)

[Claims] (1) In a CVD thin film forming apparatus having a reactant gas feed nozzle at the center top of a bell jar, the reactant gas feed nozzle is composed of three or more nozzles arranged coaxially, and the gas supply port to each nozzle is A CV characterized in that a plurality of CVs are arranged on the outer peripheral surface of the nozzle symmetrically with respect to the central axis of the nozzle.
D Thin film forming device. (2) The CVD according to claim 1, wherein the reactor is a revolution-rotation type atmospheric pressure CVD reactor.
Thin film forming equipment.