JPH0582450A - Vapor phase reaction equipment for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a vapor phase reaction equipment which can form an uniform film free from contamination or realize uniform etching free from contamination, and obtain excellent reproducibility when processes are repeated (continued). CONSTITUTION:The title equipment is provided with the following; a reduce pressure reaction chamber 1 linked with an evacuation system, a supporting stand 3 which retains a semiconductor substrate 2 in a reaction chamber, and an introducing pipe 4 which introduces process gas into the reaction chamber. An inner pipe 5 is installed above the supporting stand so as to cover the semiconductor substrate 2. The introducing pipe 4 of process gas is connected with the inside of the inner pipe 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of semiconductor devices such as ICs and LSIs, and more particularly to a gas phase reaction apparatus for forming a thin film or etching a thin film of a semiconductor device. Thin films of semiconductor devices include insulating films such as SiO ₂ and Si ₃ N ₄ , conductor films such as Al, W and TiN, and Si and Ga.
There is a semiconductor film of As or the like, and it is required to perform film formation and etching thereof uniformly and without contamination. These things become more important as the size of the semiconductor substrate (wafer) increases (the diameter increases). It is also important to be able to perform fine patterning and substrate cleaning properly.

[0002]

2. Description of the Related Art A conventional vapor phase reaction apparatus such as a film forming apparatus (CVD apparatus) or an etching apparatus basically has a reaction chamber connected to an exhaust system, a support base for supporting a semiconductor substrate in the reaction chamber, An introduction pipe for introducing a process gas (reaction gas, etching gas, etc.) to the reaction chamber is provided. A heater for heating the substrate to a predetermined temperature or a cooler for preventing temperature rise is provided under the support table. In the case of film formation, the reaction chamber is evacuated, the reaction gas is supplied to the reaction chamber while the semiconductor substrate is heated, and the film material is deposited on the semiconductor substrate by the reaction to form a predetermined film. Further, in the case of etching, the reaction chamber is evacuated, and the etching gas is supplied to the reaction chamber in a state where the semiconductor substrate is heated or cooled by cooling water according to the intended etching shape, and the formed film ( Alternatively, the semiconductor substrate) is selectively etched. Particularly, in etching, plasma is used to enhance the etching effect (action), and an electrode for plasma generation is provided in the reaction chamber.

[0003]

In the film forming process, the film grows not only on the semiconductor substrate but also on the heater, which may generate reaction by-products and particles. When the film forming process is repeated, particles adhere to the film forming surface of the semiconductor substrate, and the generation of by-products affects the film formed (grown) on the substrate surface (a kind of loading effect), and the film thickness Of non-uniformity, deterioration of film quality and deterioration of reproducibility. Further, since plasma is used in the etching process, dirt on the heater or dirt in the reaction chamber is taken into the etching atmosphere, and contaminants may adhere to and remain on the etched surface. Furthermore, if the film to be etched (or particles) is present in addition to the film to be etched on the surface of the semiconductor substrate, the etching profile deteriorates and the in-plane distribution of the etching rate becomes non-uniform.

An object of the present invention is to provide a gas phase reaction apparatus capable of performing uniform and contamination-free film formation or uniform and contamination-free etching, and having good reproducibility even when repeated (continuous). is there.

[0005]

[Means for Solving the Problems] The above object is to provide a decompression reaction chamber connected to a vacuum exhaust system, a support for supporting a semiconductor substrate in the reaction chamber, and an introduction pipe for introducing a process gas into the reaction chamber. In a gas phase reaction apparatus for manufacturing a semiconductor device, the inner tube is provided above the support table so as to cover the semiconductor substrate, and the introduction tube for the process gas is connected to the inner tube. It is achieved by a characteristic gas phase reactor for manufacturing a semiconductor device.

[0006]

With the structure of the gas phase reaction apparatus according to the present invention, the semiconductor substrate can be covered with the inner tube, and the process gas pressure in the inner tube is maintained at the maintaining pressure (vacuum degree) of the reaction chamber.
Can be larger than. By controlling the pressure in this way, the process gas passes through the gap between the lower end of the inner pipe and the support table at a high speed from the inside of the inner pipe to the outside, so that contamination or particles from the outside of the inner pipe to the semiconductor substrate can be prevented. Even if the reaction by-product adheres to the support and the heater, the influence thereof does not affect the film growth on the semiconductor substrate at all. Therefore, film formation and etching can be performed uniformly and without contamination, and reproducibility is good.

It is preferable that the support base is provided with temperature control means (heater or cooling plate for cooling medium) inside thereof and gas supply means for covering the lower side thereof with purge gas in the reaction chamber. The temperature control means is conventional, the heater accelerates the reaction, and the coolant cooling plate prevents the resist from overheating. A purge gas can be sent to the lower side of the temperature control unit to prevent the process gas (reaction gas, etching gas) from entering, and the by-product does not adhere to the heater. Here, even if the purge gas is supplied to the reaction chamber, it does not affect the process gas pressure in the inner pipe.

A cooling ring is preferably provided at the lower end of the inner tube. When forming a film, the heat of the support that heats the semiconductor substrate also heats the lower end of the nearby inner tube, which accelerates the reaction there and causes film growth, so the lower end is cooled. To prevent unwanted film attachment. It is desirable that the evacuation system be equipped with a large evacuation vacuum pump.
In order to create a difference (pressure difference) between the pressure in the inner tube and the pressure in the reaction chamber, the vacuum pump is a high-speed and large-capacity exhaust (large displacement) pump such as a mechanical booster pump, a rotary pump, and a turbo molecular pump.

The distance between the support and the lower end of the inner tube is 1 to 1.
It is preferably 00 mm (preferably 50 mm). The process gas flows through this interval, and the inner pipe diameter D,
Assuming that the interval H, the inner pipe pressure P, the gas flow velocity V, and the flow velocity v of the gas flow traversing, the relation of v = 760V / PπDH is obtained, and H is set so that v is 10 ² to 10 ⁶ cm / mm. , Preferably v ≧ 10 ³ cm / mm
So that

In order to perform plasma etching, it is preferable to provide a high frequency applying electrode for plasma generation inside the inner tube. This electrode is conventional. Further, it is preferable that the inlet of the process gas to the inner tube is of shower type. The shower system promotes uniform process gas flow in the inner tube.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings by way of example embodiments of the present invention. FIG. 1 shows a schematic cross section of a gas phase reaction apparatus for manufacturing a semiconductor device according to the present invention.
The reaction apparatus includes a reaction chamber 1 connected to an exhaust system, a support base 3 for supporting a semiconductor substrate 2 in the reaction chamber 1, and an introduction pipe 4 for introducing a process gas (reaction gas, etching gas, etc.) into the reaction chamber. And an inner tube 5 that extends downward from the upper wall surface of the reaction chamber 1 and covers the semiconductor substrate 2 inside the reaction chamber 1. The inner pipe 5 is made of aluminum alloy or stainless steel, and the lower end of the inner pipe 5 forms a predetermined gap with the support base 3. The length of the inner tube 5 is predetermined in consideration of a predetermined gap. In order to place or lower the semiconductor substrate 2 on the support base 3, the support base 3 can be moved up and down, and the predetermined gap can be changed and adjusted above and below. The length of the inner tube 5 may be changed by forming a part of the inner tube 5 as a bellows. A shower 6 connected to the introduction pipe 4 is provided above the inner pipe 5, and a cooling ring 7 is attached to the lower end thereof. A pipe 8 for circulating cooling water is provided in the cooling ring 7. Although the cooling ring 7 is necessary in the film forming process, it may not be the etching process.

A temperature control means 9 for bringing the substrate to a predetermined temperature is provided under the support table, a heater for heating in the case of film forming processing, and a cooler for preventing temperature rise in the case of etching processing. There is. Below the temperature control means 9, a purge gas supply pipe 11 for protecting the means 9 from the process gas is provided.
The supply pipe 11 is equipped with a purge gas (N ₂ , He,
A heat exchanger 13 for heating or cooling the purge gas so that an unnecessary load is not applied to the flow rate controller (mass flow controller) 12 for Ar, H _2, etc. and the temperature control means 9.
Is preferably provided.

A purge gas supply pipe 14 is provided outside the inner pipe 5 of the reaction chamber 1, and a purge gas (N ₂ , He, Ar, H _2, etc.) is sent to the supply pipe 14 through a flow rate controller 15 to carry out reaction. Adjust the pressure inside the room, dilute the process gas, and promote exhaust. A pressure gauge P ₁ for measuring the pressure of the reaction chamber 1 and a pressure gauge P ₂ for measuring the pressure of the inner tube 5 are attached. Further, a sluice valve 1 is provided between the reaction chamber 1 and the exhaust system (a vacuum pump (not shown) is provided at the tip of the arrow A).
There are 6 and 17. Although there are two exhaust ports in the drawing, one or more exhaust ports may be provided.

A ring-shaped electrode 18 is provided inside the inner tube 5 for plasma etching, and a voltage from a high frequency power source 19 is applied to the ring-shaped electrode 18. Cooling water circulates through the temperature control means 9 to cool the semiconductor substrate 2. Example 1 In the vapor phase reaction (CVD) apparatus described above, HF was previously prepared.
A tungsten (W) film is formed on a semiconductor substrate whose surface is cleaned with a solution or HF gas as follows.

A turbo molecular pump (TMP) having a displacement of 1500 liters / second is used as a vacuum pump, and a purge gas (H
e) is supplied from the supply pipe 11 to the bottom of the heater for 5 SSCM and is supplied from the supply pipe 14 to the reaction chamber for 5 SSCM. Then, WF ₆ and H ₂ (or SiH ₄ , SiH ₂ F ₂ , B ₂ H ₆ , PH ₃ ) are introduced as a process gas into the shower 6 through the introduction pipe 4, and are supplied into the inner pipe 5. Inner tube 5 and support 3
The gap between and is 5 to 20 mm.

(I) A silicon substrate having a SiO ₂ oxide film is used as a semiconductor substrate, and 400 to 500 is provided on a support base.
Heat to ℃. WF ₆ (5SSCM) and H ₂ (200SSCM) are used as process gas, the inner pipe pressure P _{1 is set} to 10 Torr, and the reaction chamber pressure P _{2 is set} to 10 mTorr. As a result, a W film is formed on the entire surface of the semiconductor substrate.

(Ii) Using a silicon substrate having the same oxide film, heat it to 200 to 300 ° C. on a support. WF ₆ (5SSCM) and SiH ₄ (3SSC) as process gas
M) and the inner pipe pressure P ₁ is set to 20 mTorr and the reaction chamber pressure P ₂ is set to 0.1 mTorr. As a result, the W film is selectively formed only on the exposed silicon portion of the semiconductor substrate. In this case, if the selective growth of tungsten is performed by the conventional method without using the inner tube, as shown in FIG.
As shown in, the tungsten particles are rapidly generated on the oxide film after a certain period of processing time (selectivity is lost). On the other hand, when the device of the present invention is used, tungsten particles are hardly generated and do not increase with the passage of time.

Example 2 In the vapor phase reaction (CVD) apparatus described above, the semiconductor substrate
Then, an insulating film (TiN) film is formed as follows. Example 1
In the same way as the above, a vacuum pump with a displacement of 1500 liters / second
Using a turbo molecular pump (TMP), purge gas (He)
Flow 5SSCM from the supply pipe 11 to the bottom of the heater
Flow 5SSCM from 14 to the reaction chamber. And the introduction pipe 4
Through as a process gas TiCl_Four, Organic Ti compound
Thing, NH₃Or N₂H_FourAnd H ₂To shower 6
It is guided and supplied into the inner pipe 5. Gap between inner tube 5 and support 3
Is 10 to 30 mm.

The semiconductor substrate is heated to 600 ° C. on the support base.
It TiCl_Four(5SSCM), NH₃(100 SSC
M) and H₂(50SSCM) is supplied to the inner pressure of the inner pipe
Power P ₁To 1 Torr, and the reaction chamber pressure P₂To 0.1 mTo
Let rr. As a result, TiN is deposited on the entire surface of the semiconductor substrate.
Form a film. Example 3 In the vapor phase reaction (CVD) apparatus described above, the semiconductor substrate
Then, a metal film (Al) film is formed as follows.

As in Example 1, the displacement of the vacuum pump was 1500
Using a turbo molecular pump (TMP) of liter / second, purge gas (He) from the supply pipe 11 to under the heater 5SS
CM flow, 5SSCM flow from the supply pipe 14 to the reaction chamber. Then, Al (CH
₃ ) ₂ H and H ₂ are guided to the shower 6 and supplied into the inner pipe 5. The gap between the inner tube 5 and the support 3 is 10 to 30 mm.

The semiconductor substrate is heated to 280 ° C. on the support base. Al (CH ₃ ) ₂ H (10SSCM) and H
₂ (100SSCM) is supplied to set the inner pipe pressure P ₁ to 1
The pressure in the reaction chamber is set to 0 Torr and the pressure P ₂ in the reaction chamber is set to 0.1 mTorr. As a result, an Al film can be formed on the entire surface of the semiconductor substrate, and if a patterned oxide film substrate is used, Si film can be formed.
And only grow to metal. Al (iC
₄ H ₉ ) ₃ can also be used.

Example 4 In the vapor phase reaction (CVD) apparatus described above, HF was previously prepared.
Semiconductor substrate whose surface is cleaned with a solution or HF gas
A semiconductor (Si) film is epitaxially formed as follows.
To achieve. As in Example 1, the vacuum pump was equipped with a displacement of 1500 liters.
Torr / sec turbo molecular pump (or mechanical booth)
Using a tar pump) and a purge gas (H₂)
Flow 5SSCM from the supply pipe 11 to the bottom of the heater, and supply pipe 14
Flow 100 SSCM into the reaction chamber. And the introduction pipe 4
SiH as a process gas_Four(Or Si
₂H₆, SiH₂F₂, SiH₂Cl₂) Shower 6
And feed it into the inner pipe 5. Between the inner tube 5 and the support 3
The gap is 20 to 100 mm.

The semiconductor substrate is placed on a support table at 700 to 900 ° C.
Heat to. SiH ₄ (20SSCM) (or Si _{2
H 6: 15SSCM, SiH 2 Cl} 2: 15SSCM)
And H ₂ (10 to 15 liters) to supply the inner pipe pressure P ₁ to ₁₀ to 100 Torr and the reaction chamber pressure P ₂
Is 1 to 100 mTorr. As a result, the Si film is selectively epitaxially formed only on the exposed silicon portion of the semiconductor substrate.

In the case of these film formations, it is possible to uniformly form a predetermined film on the semiconductor substrate without mixing or adhering particles. In gas phase reactors Example 5 above, as the plasma etching apparatus includes a plasma generating electrode, etching the Si0 ₂ film formed on the semiconductor substrate.

As in Example 1, the displacement of the vacuum pump was 1500
Using a turbo molecular pump (TMP) of liter / second, purge gas (He) from the supply pipe 11 to under the heater 5SS
CM is supplied, and 10 SSCM is supplied from the supply pipe 14 to the reaction chamber.
The gap between the inner tube 5 and the support 3 is 5 to 20 mm. (I) To remove the native oxide film formed on the silicon surface as a pretreatment by etching, NF ₃ (5
Shower 6 with SSCM) and H ₂ (100SSCM)
And feed it into the inner pipe 5. The inner pipe pressure P ₁ is 20m
Torr, and the reaction chamber pressure P ₂ is 0.01 mTorr. The semiconductor substrate is kept at room temperature by cooling with cooling water on a support. Then, 50 W of 13.56 Hz high frequency is applied to the electrodes to perform plasma etching.

[0026] The selective etching of (ii) Si0 ₂ film by using a resist mask pattern, the etched portions are not covered, through inlet pipe 4 NF ₃ (10
Shower 6 with SSCM) and H ₂ (100SSCM)
And feed it into the inner pipe 5. The inner pipe pressure P ₁ is 20m
Torr, and the reaction chamber pressure P ₂ is 0.01 mTorr. A semiconductor substrate is placed on a support table with a cooling medium (liquid nitrogen)
Maintain at 60 ° C. Then, 300 W of 13.56 Hz high frequency is applied to the electrodes to perform plasma etching.

In the case of these etchings, the SiO ₂ film can be uniformly formed without mixing or adhering particles.

[0028]

As described above, in the vapor phase reaction apparatus (CVD apparatus, etching apparatus) for manufacturing a semiconductor device according to the present invention, a higher quality film (uniform and non-contamination-free film formation) can be obtained. Therefore, high precision etching can be performed. Since the support base and the temperature control means (heater) are covered with the purge gas to prevent the by-products from adhering, the cleaning cycle of these can be greatly extended, which contributes to the reduction of the number of cleanings and the cost.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a gas phase reaction apparatus for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a graph showing the relationship between the processing time for forming a tungsten film and the number of particles on the oxide film.

[Explanation of symbols]

1 ... Reaction chamber 2 ... semiconductor substrate 3 ... support stand 5 ... inner tube 6 ... Shower 9 ... temperature control unit P _1, P ₂ ... pressure gauge

Claims (6)

[Claims] 1. A reduced pressure reaction chamber connected to a vacuum exhaust system,
A gas phase reaction apparatus for manufacturing a semiconductor device, comprising: a support for supporting a semiconductor substrate in the reaction chamber; and an introduction pipe for introducing a process gas into the reaction chamber, wherein the support (3)
A semiconductor characterized in that an inner pipe (5) is provided above the semiconductor substrate (2), and the introduction pipe (4) for the process gas is connected to the inner pipe (5). Gas phase reactor for equipment manufacturing. 2. The support base (3) is provided with a temperature control means (9) below the support base, and a gas supply means for covering the lower side of the support base with a purge gas is provided in the reaction chamber. The manufacturing method according to claim 1. 3. Device according to claim 1, characterized in that it comprises a cooling ring (7) at the lower end of the inner tube (5). 4. The apparatus according to claim 1, wherein the vacuum pumping system is provided with a vacuum pump with a large pumping capacity. 5. Device according to claim 1, characterized in that the distance between the support (3) and the lower end of the inner tube (5) is between 1 and 100 mm. 6. The device according to claim 1, characterized in that a high-frequency applying electrode (18) for plasma generation is provided inside the inner tube (5).