JPS6021381A - Thin film forming reaction furnace of photo-cvd apparatus - Google Patents

Abstract

PURPOSE:To increase a thin film forming velocity, and to improve the quality by stretching a film having high heat resistance and good ultraviolet ray transmissivity, and preventing the reaction product from depositing on a quartz window. CONSTITUTION:The titled reaction furnace consists of a reaction chamber 12, a light source unit 2 for irradiating ultraviolet ray into the chamber 12 through a quartz window 1, a heat source unit 6 for heating a substrate 4 through a quartz window 11 and a susceptor 5, a film roller apparatus 17, and a reaction gas introducing and discharging groove. Said reaction chamber 12 is sealed with the upper and the lower transparent quartz windows 1 and 11 and side walls, and a group of the substrates 4 is contained therein. Said film roller apparatus 17 rolls in and out a film having high heat resistance and good ultraviolet ray transmissivity which is situated directly under said window 1 and movable in one direction in the chamber 12. The reaction product is not deposited on the window 1 by said reaction furnace, and a good-quality thin film can be obtained on the surface of the substrate 4 by light CVD.

Description

DETAILED DESCRIPTION OF THE INVENTION Semiconductor device processing technology is constantly progressing, and in particular, thin ++V generation technology is directed toward lowering the generation temperature. Plasma CVD (chemical vapor deposition) film production technology is already known as a means of lowering the temperature, but recently UqO
The generation technology of vDp is attracting attention. The present invention is based on optical CVD
This paper relates to improvement of the thin film production reactor of the device.

First, the optical CVD method will be explained. In the photo-CVD method, the reaction gas reacts with light energy, and not only can the generation temperature be lowered, but also there is no high-energy particles such as ions and electrons in the plasma CVD method, so there is no possibility of irradiation of the grown film by ions, etc. Since there is little damage and it is easy to make the irradiation intensity of light uniform, it is easy to make the thickness of the grown film uniform.
It has the advantage of being easy to process large-diameter curves, has good step coverage, and has fewer step depressions that occur in the pattern of the thin film on the substrate.
It is expected to be an important branch of VD film production technology.

)1', CV' The reaction formula of method D is expressed by the following formula.

1] Sea 1-H,9 uses the energy of ultraviolet light from a mercury lamp as a light beam and catalytically converts p(y(
100-200° C. represents the temperature at which the thin film of the wafer+ is formed. In any of the above reactions, a low-pressure mercury lamp having the emission spectrum shown in FIG. 1 is currently used as the light source in many cases.

FIG. 2 shows a typical example of a conventional optical (j V I) reactor. Reference numeral 1 in the figure is a quartz window plate for transmitting ultraviolet rays, and the area below this forms a light source chamber, and the area below it forms a reaction chamber. Reference numeral 2 denotes a mercury lamp unit for ultraviolet light, 3 denotes a fouling plate, and 4 denotes a group of wafers (substrates) placed on a susceptor 5''.

6 is an infrared lamp unit, 7 is a thermocouple, 8 is an auxiliary heater, 9 is a gas supply into the reaction chamber, ] 0 is an exhaust port to a vacuum pump 1]. In this reactor, the substrate 4 is heated with an infrared lamp unit 6 (the auxiliary heater 8 is an auxiliary plate that prevents the substrate from being directly irradiated with infrared light and improves the temperature distribution of the substrate). A reactant gas of a material determined by the thin film produced in the 2000-2000 film is introduced into the reactor from the mercury lamp unit 2, and the energy of ultraviolet light transmitted through the quartz window plate 1 is taken in from the mercury lamp unit 2. This method produces thin films at low temperatures.

However, a furnace having such a structure has the drawback that a produced film gradually adheres to the entrance window surface (the surface facing the reaction chamber, the bottom surface in the figure) of the quartz plate 1, and the amount of irradiated light decreases.

In the case of polysilicon films, this phenomenon has been reported to show that the production rate is extremely reduced when the produced film exceeds 300λ, but at present no device has been found that can solve this problem. The present invention was made to solve this problem, and will be described in detail below.

FIG. 3 shows a +Wr formation example Jl! of photoCVD reaction in which the present invention was implemented: l;i'i! ! 1.2.4.5.6 in Figure 37, which is Figure 51''. 'H7-,
>There are. That is, l is anhydrite %ov:t (J anti),
Inside reaction chamber 2 (2;=,
l,) Pass through 4. This is the upper part of the reaction chamber.
It is blocked from the outside air by the quartz window l and the 0 link (ET-)
>: Seal, lt.

ing. The quartz window has an ultraviolet transmittance of 11% and 1%! (Water (IO'! Use AA. 2 is Ueno
A mercury lamp that supplies ultraviolet light energy to the 4's deficiency 1r11 Kin 1 Emperor, 4 is Uni I) X (substrate) on this surface (2 fi 41' II anti 1. L: (2 A! f:
II';: is formed. 5 is a susceptor that indirectly heats phenol (mainly silicon), and it takes one piece of carbon +4, which is a substitute for SIO. 6 is Sir [Ibuta 5 to force 11
A rank (No. 2 J) Rogen lamp is usually used as an infrared lamp unit that heats.
iTi+: The reflector belongs to E1 for double irradiation.
C1,=ru. This lamp unit is installed outside the reaction chamber to facilitate lamp replacement (2), and there is also a general movement mechanism for vertical and horizontal movement. The second to be transmitted to
The lower part of the reaction chamber is isolated from the outside air by the quartz window (plate) and the O-ring. 3 is a PFA film, which has the role of creating a spatial dimension νIt in the reaction chamber 2 between the quartz window 1 side and the reaction chamber 2 side so as to prevent reaction products and reaction residue from adhering to the quartz window 1. PFA firn,
As will be further explained later, it is a film that is heat resistant and has a high ultraviolet ray transmittance. ] 4 is a roller of PFA film, ], 5 is a fill reno roller for imparting re-drying motion to the roll 14, ] 6 is an auxiliary roller, P F
' Winding and feeding of A fill l. ] 3 11'1
This is for the purpose of 1j. 17 is the film supply chamber 20
a and the chamber of the film storage chamber 20b,] 8 prevents reaction products and reaction gas from entering the quartz window 1. This part is shown in detail in the page number 7 and the reaction gas aperture diagram of FIG. 19a shown in Figure 4 is ShiiJid, 19b
22 is a reaction gas, 23 is a purge gas, 24
is the exhaust. In Fig. 3, 20a is a film supply chamber with an auxiliary roller 16, a film roller 15, and a PFA.
Fill ＼ (1-Store 14. 20b is fill 7
・16 auxiliary rollers and 15 J film rollers in one storage room
l'l"'A Film roll] 4 is stored. 2
1 is water//l''i jacket, C] Schilling overheat prevention, film and film supply chamber 20a in reaction chamber 2.
1. Prevent overheating of the film storage chamber 20b.

Now, the feature of the reactor of the present invention shown in Fig. 3 is that, in order to solve the above-mentioned conventional problems, a heat exchanger (with high intensity and ultraviolet rays) is installed directly under the quartz window that transmits the light of the mercury lamp. A gas barge chamber (intermediate exhaust including gas par t7 and port 8 is equipped with i and ij functions) is provided between the reaction chamber J2 and the quartz window via a PFA bubble with good transmittance, as shown in Fig. 4. As shown in the figure, the gas is introduced and released, and the quartz window 1 is made 41-1 so that the reaction products do not come into contact with the quartz window 1.
x; 'Δ The reaction product should be attached only to the film. (There are two.

Figure 5 shows the transmittance characteristics of an anhydrous quartz plate with respect to the wavelength of light at a thickness of 1.5*m and a thickness of 1.5 m. Q II+1+1.30 mm quartz plate (two are shown, the difference in thickness is small). Figure 6 shows the transmittance characteristics of the PFA film with respect to the wavelength of light, and the thickness of the film is A = 7071. B car 90
This is the case for μ. PFA film is a fluorine film made of a copolymer of tetrafluoroethylene and perfluoroalcoquine ethylene, and is considered to be a version of the conventional P'I''FE (commonly known as Teflon) with particularly enhanced thermal plasticity. In our country, TJ city [υ!Toyoflon P as a product]
FA film (product name) etc. 19 times. This film has the highest mechanical strength among fluorine films at high temperatures, is chemically stable, and is not attacked by almost all chemicals, solvents, and oils. Its properties are shown in the table below. ←Problems → ÷Generally, synthetic resin films such as PFA films have the property of exothermic solidification when irradiated with ultraviolet rays, but in the reactor with the structure of the present invention, this property is fatal. The PIi" A film (2L) was subjected to an ultraviolet irradiation test to cause serious defects. &li of testing with uV,! 4! , Phil l,
The length λ) was 1 mm above 40°C, and no solidification was observed, proving that it was sufficiently durable for practical use.

Next, the structure of a part of the reactor of the present invention will be further explained with reference to FIG. In order to minimize adhesion of reaction products to the bottom of the quartz window, P and F are used between the reaction chamber 12 and the quartz window 1 except for the path of incidence of ultraviolet rays.
A film kites 19a, 9b are separated by diagonally shaded areas in Figure 44). In addition, the quartz window L has 11 grooves on the inner and outer peripheries (11 grooves each) on the flange on the quartz window L side, so that the reaction gas can circulate around the quartz window L. 18 and exhaust gas 24 from the outer circumferential side (thereby preventing the reaction gas from flowing into the quartz window).In addition, the pressure on the quartz window side is If the pressure of the reactant gas is increased even slightly than the pressure of the chamber 12, the effect of the reactant gas in this gas bulge method will be higher, so the probability that the reactant gas will reach the quartz window 1 is extremely small. Quartz window]
Against the side of 1. C: Adhesion of the product hardly occurs.

Also, during CvD film formation, PFA film: 2-tank 2 product adheres,
Although the low point of the river is seen, the film 13 was applied to the 1 Samurai in which a certain thickness of reaction product 1 was added to the film 1-;', i! t, '1 Fill 7 at the right end of the figure - Take 7 pieces to the roll 14 in the storage chamber 20b, film supply chamber 20
If a new film is supplied from the roll a, the ultraviolet irradiation light h) is kept active for a long time, increasing the production rate. By repeating this operation, the desired 117
1!74 (usually 5.000Å・~10.ooo7,
) can be obtained.

Needless to say, a structure that facilitates film replacement is desirable. Therefore, P II' A fill 7.
Kite (shaded area in Figure 4) is 19a, ``2'' of ``91''.

1-゛It has a structure that can be separated into guides, and in order to replace the film, the flange to which 9 a is fixed and each roll chamber] If you open the + flange of 7, 1 j will be inserted into the cylinder.
It is becoming more and more popular.

Further, since the roll chamber 1'7 is evacuated intermediately between the roll chamber 1'7 and the reaction chamber 12, there is almost no reaction scum. Therefore, there is no problem of contamination due to reactive gases.

On the other hand, since there is a drive unit in this roll chamber, there is a slight risk that a small amount of fine powder will not be generated, but is there an intermediate exhaust in the exhaust 24? Because of this, this fine powder hardly ever enters the reaction chamber 12.

Finally, cooling of the PFA film will be explained.

As shown in the table 111, the limit temperature for PFA film is 260"C on the high temperature side, and the lowest possible temperature is 260"C.
71A is desirable. Therefore, the side surface of the reaction chamber and the lower surface of the F guide 19b are water-cooled.

For example, PFA film has a thickness of 2.5,50°75
．． 5 types of 100, 125 (each μrn), width 500.
Two types of 1000 mm (each mm) and a film length of 50 m are commercially available. The unit price per square meter of 25 μm PFA film is currently about 5,600 yen. According to trial 311, when a polysilicon film of 6000 µm is formed on a 4-inch wafer, the fill per wafer is 11 y; l: ], 0201+], but PFA
The film can be washed 6 times.

Note that film] 3 is not limited to PFA film, and may be P'FA film, which has a high heat resistance and high ultraviolet transmittance.
Needless to say, any equivalent film can be used.

As explained in detail, the photo-CVD reactor of the present invention can cause a reaction when ultraviolet rays are emitted through the quartz window from the 4'' side of the substrate that produces a thin ++V on the surface. In order to prevent the reaction products in the chamber from adhering to the quartz window and reducing the amount of light entering the reaction chamber, a PF'A filter was installed at the target of the quartz window and the second section of the reaction chamber. It has a remarkable effect on improving the production rate of thin ++y・ and improving the quality of thin 11'1. Whereas labor was necessary, the present invention requires only the winding and renewal of the film, so labor is almost unnecessary (automatic winding may be possible in the future), making it economical and practical. The effect! 1 is big.

[Brief explanation of drawings]

Figure 1 is an example of the emission spectrum of a low-pressure mercury lamp, Figure 2
The figure shows the typical structure and factors of the reactor of a conventional photo-CV'D device, FIG. 3 is a schematic diagram of the structure of the reactor of the photo-CVp device according to the present invention, and FIG. Detailed view of the section showing the flow of purge gas and reactant gas. FIG. 5 is a light transmission characteristic diagram of an anhydrous quartz plate, and FIG. 6 is a light transmission characteristic diagram of a PFA film. 1...Quartz window (board), 2...Ultraviolet lamp unit, 3...Reflector plate,
4... Substrate (wafer), 5... Susceptor, 6
... Infrared lamp unit, 7 ... Thermocouple, 8
...Auxiliary heater, 9...Gas filler 1", 10...
...Vacuum pump inlet, 11...Second quartz window (plate), 12...Reaction chamber, 1311...PFA film, 1-4@・Φ・Film roll, 15... Film roller, 16... Auxiliary roller, 1700 Film chamber (film chamber 20a, 2
(including 0b), 18...Gaspan port, 19...Guide,
20a...Film supply chamber, 20b...Film storage chamber, 21...Water cooling jacket, 22...Reaction gas flow, 23...Reaction gas flow, 24... jk minded. Patent applicant: Kokusai Electric Co., Ltd.

Claims (1)

[Claims] The reaction chamber is fixed by a transparent quartz window plate of 1° and the side wall, and contains a group of substrates (wafers) lined up in ten directions. a light source unit that irradiates the substrate, a heat source unit that heats the substrate group through the quartz window plate and the heater, and a heat source unit that is located directly below the above quartz window and can be moved in one direction within the reaction chamber, and after being moved. A film with high heat resistance and good UV transmittance is wound up outside the reaction chamber, a film roller device that winds it up and takes it out, and upper and lower guides along the film at the exit of the film into the reaction chamber. A thin film production reaction of a photo-CVD apparatus, characterized in that a reaction gas introduction groove and a purge gas discharge groove are provided in the middle of the photo-CVD apparatus to produce a uniform thin film on the surface of a substrate by photo-CVD. Furnace.