JPH0238568A - Thin film-forming equipment - Google Patents

Abstract

PURPOSE:To form a thin metallic film with superior selectivity by applying chemical etching to the surface of a substrate in a spare chamber between a pretreatment chamber and a CVD reaction chamber to deactivate the surface at the time of forming a thin metallic film by a CVD method on the surface of a substrate to be treated. CONSTITUTION:A substrate 6 to be treated taken out from a cassette is moved through a vacuum conveyance robot chamber 5, a pretreatment chamber 1, the conveyance robot chamber 5, a spare chamber 3, the conveyance chamber 5, and a CVD reaction chamber 2 in the order named by means of a robot. In the pretreatment chamber 1, etching treatment is applied by means of sputtering to the substrate surface in a gaseous atmosphere containing at least O2, N2, and atomic F group OH or plasmic atmosphere to activate and clean the surface. Subsequently, the above substrate 6 is subjected to gas etching or to gas adsorption in the spare chamber 3 to undergo the deactivation of the activated layer formed in the pretreatment stage and is then subjected to CVD treatment in the CVD reaction chamber 2, by which the thin metallic film can be formed with superior selectivity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Objective of the Invention) (Industrial Application Field) The present invention relates to a thin film forming apparatus, and particularly to a thin film forming apparatus using chemical vapor deposition.

(Prior Art) In recent years, semiconductor devices have become increasingly highly integrated, and research into miniaturization of constituent elements and increased density is progressing rapidly.

However, with this miniaturization d5 and higher density fl', various problems have arisen in the manufacturing process of semiconductor devices.

For example, taking wiring as an example, 1, Ωi;-t Q-, t
While the wiring width is becoming smaller due to the reduction of xX+, the number of active elements is increasing, making the wiring complicated, the number of locations that must be electrically connected is also increasing, and the wiring length itself is increasing.

For this reason, wiring made of commonly used aluminum or aluminum-based alloys (Al: 1% Si, etc.) causes problems such as open defects where the wiring breaks, and electromigration due to increased electrical stress on the wiring. The following problems have also arisen:

For example, in a field-effect transistor (FET), a diffusion layer with a conductivity type opposite to that of the substrate is formed in a silicon substrate, and the depth of this diffusion layer is adjusted to improve controllability of the gate length. It tends to become shallower. After forming a contact hole for wiring on the shallow diffusion layer using a conventional photolithography method, a reactive ion edge leg method, etc., an aluminum layer made of AI (Si alloy) is further formed using a conventional method. When wiring is formed and heat treated, a so-called "pit" phenomenon in which Al atoms penetrate deeply into the SiN plate side and destroy the diffusion layer due to interdiffusion between Si atoms and Al atoms often occurs.

In addition, this electrical connection is made through a contact hole formed in the insulating layer, but the aspect ratio of the contact hole (
- contact depth/contact width) continues to increase. For this reason, problems such as disconnection at the bottom of the contact 1 hole and an increase in contact resistance occur one after another, which has become a major problem that hinders improvement in the reliability of semiconductor devices.

In order to solve these problems, a method has been proposed in which high melting point metals such as tungsten and molybdenum (Mo) or their silicide films are selectively buried in the contact holes to reduce the aspect ratio and to serve as a diffusion barrier layer for the contacts. has been done.

Furthermore, multilayer wiring is formed by repeatedly laminating wiring metal and interlayer insulating films. For this reason, the level difference on the surface of the board becomes larger as the number of layers increases, and the level difference is particularly large at wiring intersections and connections between upper layer wiring and lower layer wiring (via holes), and the reliability of the wiring decreases due to a decrease in coverage. The decline has become a major problem.

Therefore, in order to solve this problem, a method has been proposed as a planarization method in which a high melting point metal film such as a tungsten film is selectively formed by low pressure CVD, and the via hole is filled with a conductive material to eliminate the step difference in the via hole. has been done.

In these methods, under certain conditions, the CV of $
A high melting point metal film such as a tungsten film can be formed only in a specific region on the substrate using DI. This method is called a selective CVD method, and is attracting attention as a practical method for forming crystalline thin films because it simplifies the manufacturing process of semiconductor devices and can form highly reliable thin films in a self-aligned manner.

Tungsten selection CVD method uses tungsten halide such as tungsten hexafluoride (WF6) and silane (
Using a mixed gas with SiH4) as a reaction gas, silicon,
A device in which a tungsten film is selectively grown by vapor phase growth only on conductors such as aluminum and its alloys, and high-melting point metals, and the tungsten film is not formed on insulating films such as silicon oxide films. This is an extremely effective method for formation.

However, conventionally, when tungsten is selectively grown in contact holes on a diffusion layer or via holes on aluminum or its alloys, the via contact resistance between the tungsten film and the diffusion layer, aluminum or its alloys is There was a problem with it becoming 8.

As a result of investigating the cause of the rise in via contact resistance between tungsten, the diffusion layer, and aluminum or its alloy, the inventors believe that this is due to the formation of via contacts on the surface of the diffusion layer, aluminum, or its alloy. We have discovered that there are fluorides, carbides, oxides, or mixtures thereof that have high insulating properties.

However, these fluorides, carbides, and oxides are chemically extremely stable compounds with low vapor pressure, so it is difficult to chemically remove them.

Therefore, it is most efficient to physically remove it in a vacuum using a sputtering method or the like.

(Problem to be solved by the invention) However, when the tungsten film is continuously formed after the physical treatment, a tungsten film is formed on the surface of the oxide film by sputtering (this is thought to be a tungsten pond). ) There was a problem in that a film was also formed on the oxide film in the active layer, making selective growth impossible.

A similar problem is the formation of a polycrystalline silicon film using silane (3iH+) gas as the source and 10,000 s of silane gas and oxygen (02
) The formation of silicon oxide (SiO2) layers using gas (7) is becoming more and more obvious even with other selective CVD methods.

The present invention has been made in view of the above-mentioned circumstances, and solves the above-mentioned drawbacks, inactivates the active layer formed in the pretreatment process, and
The purpose of the present invention is to provide a and a film forming position which enable good selective growth.

(Structure of the Invention) (Means for Solving the Problems) Therefore, in the present invention, a pre-treatment chamber is provided for etching and cleaning the surface of the 3144 substrate to be treated, and a chemical vapor phase is applied to a specific region of the pre-treated substrate to be treated. A preliminary chamber with a desired gas atmosphere is provided between the reaction chamber in which a metal thin film is selectively formed by a growth method (CVD method), and the preliminary seedlings are heated in this preliminary seedling prior to forming a metal thin film. The pretreated surface of the substrate to be processed is chemically etched or a gas is adsorbed onto the surface of the substrate to be processed.

(Function) - By drawing F, the natural oxide film and contamination layer formed on the surface of the diffusion layer, aluminum or its alloy are completely removed in the pretreatment chamber, resulting in a clean surface. Since the surface of the substrate is exposed to a predetermined gas atmosphere in the preliminary chamber for surface treatment, the surface activated in the pretreatment process is either etched by the gas or deactivated by adsorbing the gas. , it is possible to form metal thin films with good selectivity in the reaction chamber.

For example, when dry etching such as sputtering or reactive ion etching is applied to the surface of a silicon diffusion layer or aluminum wiring layer exposed in a contact hole formed in a silicon oxide film, the silicon oxide film becomes active. There are many dangling bonds on the surface of h(
, exposing the surface to an atmosphere containing nitrogen atoms, oxygen atoms, fluorine atoms, hydroxyl groups, etc. or a plasma atmosphere containing nitrogen atoms, oxygen atoms, fluorine atoms, hydrogen atoms, etc.;
Dangling bonds on the surface are removed by surface treatment, or -N, -0. −
F, -OH, etc.'7) Thekas molecules (15yoD/) can adsorb gas atoms, making the silicon oxide film surface inert to the adsorption of reactive gases used for metal thin film formation, and have high selectivity. (Embodiment) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1(a) is a diagram showing a schematic configuration of a thin film forming apparatus according to an embodiment of the present invention. FIG. 1(b) to FIG. 1(d> are
FIG. 2 is an explanatory diagram of main parts of the device.

This thin film forming apparatus includes a pretreatment chamber 1 that sputter-etches and cleans the surface of a substrate to be processed, and a thin metal film that is selectively deposited on specific areas of the pretreated substrate by chemical vapor deposition (CVD). A reaction chamber 2 for forming a film, and a selective recovery chamber 3 for etching the surface of a pretreated substrate or adsorbing gas on the surface of a pretreated substrate. It is connected through a gate valve 4 and is composed of a transfer robot chamber 1 to a chamber 5 equipped with a robot for substrate transfer, and a substrate storage cassette 8 which is placed under atmospheric pressure and stores substrates.

Each of these chambers is a cylindrical body made of aluminum alloy, is partitioned by a gate valve 4, is connected to a transfer robot chamber 5, and is maintained in a reduced pressure state by an exhaust path 7. It has become.

Further, the pretreatment chamber 1 is equipped with a frequency-losing lightning pole 12 connected to the high frequency terminal 14 so as to apply high frequency waves of 13 and 56 HIIz through a blocking capacitor 13,
Cover the high frequency electrode 12 with a quartz plate 15! i! The structure is such that the substrate 6 is installed and a sputter etching process is performed while supplying gas such as argon gas from the first gas supply path 16.

Furthermore, the reaction chamber 2 includes a second gas supply path 21 connected to a gas supply system (not shown), a substrate support 22 on which the substrate to be processed 6 is placed, and a halogen lamp 23 as a light source. It is configured such that light from a halogen lamp 23 irradiates the substrate 6 to be processed through a transparent quartz window 24 formed in a part of the cylindrical body constituting the outer wall and heats it. There is.

Furthermore, the selective recovery chamber 3 contains ammonia (NH3)
and a third gas supply path 31 for introducing gas such as xenon fluoride (XeF2) and NF3. A fourth gas supply path 3 provided via a microwave detonator 35 with a frequency of 2450 MHz for introducing SFe plasma, etc.
6, a support stand 32 for installing the substrate to be processed 6, a halogen lamp 33 for heating the substrate to be processed, and a quartz window 34 for transmitting light from the halogen lamp 33.
The substrate to be processed after pretreatment is exposed to a desired gas atmosphere, and the surface can be tweezed or the gas can be adsorbed onto the surface. Further, oxygen or water may be introduced from the third gas supply path 31.

Further, the chamber 5 to the transfer robot 1 is equipped with a substrate transfer robot that transfers substrates between the chambers, and is capable of forming two states: an atmospheric pressure state and a reduced pressure state. This robot 1 for transporting substrates picks up the substrates one by one from a substrate storage cassette placed under atmospheric pressure! i! Take out the physical board 6 and -
After the chamber is evacuated to a reduced pressure state, the gate valve 4 is opened, and the substrate 6 is placed on the substrate support stand 15 of the preprocessing chamber 1 in the reduced pressure state, the gate valve 4 is closed, and the substrate 6 is processed. do. After this, return to the transfer robot room 5 again,
The substrate 6 is placed on the substrate support stand 32 of the selective recovery chamber 3.

Then, the gate valve 4 is closed, the interior is returned to atmospheric pressure, and the next substrate 6 to be processed is transferred to the substrate storage cellar 1 to be taken out from the substrate storage cellar 1~ placed under atmospheric pressure. You can hear Goo 1-Bulb 4 between. On the other hand, if you want to take out the board from one of the three chambers, reduce the pressure in that chamber. First, these transfer robot room 5
After reducing the pressure in the chamber to the same degree of vacuum, the gate valve 4 between the corresponding chamber and the transfer robot chamber 5 is checked. In this way, the substrates are sequentially placed in the substrate storage cassette 8.
From, transport robot chamber 1 to chamber 5 - pretreatment to 1 - transport robot chamber 5 - selectivity recovery chamber 3 - transport robot chamber 5 - reaction chamber 2 -
The substrate is transferred to the transfer robot room 5 and then to the substrate storage cassette 8.

Next, using the thin film forming apparatus configured as described above, selective CVs are formed in the via holes formed in the silicon oxide film on the aluminum wiring layer in the same manner as in the first embodiment.
A method of embedding a tungsten film using the D method will be explained.

That is, in the same manner as in the first embodiment, the silicon oxide film 114 on the first aluminum interconnect 1113 formed on the silicon substrate 111 via the insulating fJIA 112 is coated with the silicon oxide film 114 shown in FIG. A substrate with via holes 115 formed therein as shown in FIG. 1 is stored as a substrate to be processed 6 in a 35-plate storage cassette 8 of the thin film forming apparatus shown in FIG.

Then, the board storage cassette 8 is loaded by the transport robot.
The silicon substrate 111 as the substrate to be processed 6 is then carried into the pre-processing chamber 1, and the surface of the silicon substrate 111 is subjected to sputter etching. Here, one zing condition is an argon (Ar) gas flow (L 100 cc/min).

Pressure Q, Q3 Torr, high frequency power 300W,
About 100 people applied the surface of the first aluminum side 13 with a self-bias of -800V and a 1-minute dodging time.
The surface of the silicon oxide film 14 is etched approximately 120 times.

In this way, after removing fluorides, carbides, oxides, etc. from the VIR ball 15, the transfer robot listens to the button valve 4 and moves from the pretreatment chamber 1 through the transfer robot chamber 5 to the selective recovery chamber 3. The substrate 6 is received on the support stand 2, and the support stand 2 is placed in the center by a transfer robot. Then, the substrate temperature is lowered to 200°C and the third gas supply path 3 is opened.
Flow ammonia (Nt-1a,) from 1 to 100
cc/min, pressure Q, and 5 Torr for about 1 minute, ammonia is adsorbed onto the surface of the silicon oxide film 114.

In this step, the surface of the silicon oxide film 114 produced by sputtering is inactivated by bonding nitrogen atoms to silicon dangling bonds.

Then, the substrate to be processed 6 is transferred from the selectivity recovery chamber 3 to the substrate support stand 2 in the reaction chamber 2 via the transfer robot chamber 5 using a transfer robot.

In this way, as shown in FIG. 2(d), the tungsten film 116 is selectively embedded only in the via hole 115 of the substrate 6 to be processed by the selective CVD method.The conditions for depositing this tungsten film 116 are as follows. , halogen lamp 23
By 51! ! While heating the buried substrate 6,
00°C, deposition pressure 0.2 Torr, tungsten hexafluoride W F 6 flow maximum 10 CC/min, silane SiH
The four-flow fil was 10 cc/min, and the deposition time was 150 seconds. The growth rate at this time was approximately 5,000 people/min.

In this way, the tungsten film 116 can be embedded in the via hole 115 with extremely high selectivity, and the contact characteristics are also extremely good. For comparison, the treatment in the selective recovery room 3 was omitted and the treatment in the via hall 11 was performed.
3(a) and 3(b) are comparative views of the state in which the tungsten film 116 is embedded in the tungsten film 116. As is clear from this figure, in the conventional method in which the treatment in the selectivity recovery chamber 3 is omitted, tungsten (=l W) is also observed on the silicon oxide 'fA114 surface, indicating that the selectivity is reduced. I understand.

In the above embodiment, the surface treatment of a substrate containing a mixture of aluminum and silicon oxide was described, but silicon, molybdenum, tungsten, titanium, and titanium
It is also effective for selective vapor phase growth treatment on the surface of a substrate in which light etc. and an insulating film such as silicon oxide are mixed.

In addition, in the above example, the surface treatment was performed in an ammonia atmosphere, but other gases used for surface treatment include chlorine fluoride (CIF>), chlorine trifluoride (CIF3), and chlorine pentafluoride (CIFs). Bromine fluoride (BrF) Bromine trifluoride (BrF3) Bromine pentafluoride (BrFs) Iodine trifluoride (1F3) Iodine pentafluoride (IFs) Iodine heptafluoride (IF73) Xenon fluoride (XeF2>Fluorine (
F2) Oxygen (02) Water vapor, etc., at least a fluorine atom F1 Oxygen atom 1 Nitrogen atom N, or a gas containing a hydroxyl group, or SF6, NF3゜CF4, N2, H2 plasma, etc. Oxygen atom O2 Nitrogen atom N, Fluorine atom A plasma gas containing "F, 1 hydrogen atom" may be used.

Further, the processing temperature may be selected from a range of 0 to 600° C. depending on the structure of the substrate to be processed or the type of gas used for surface treatment.

Furthermore, in the above embodiment, the selectivity recovery chamber and the transfer port chamber were separated, but depending on the gas used for surface treatment, the selectivity recovery chamber and the transfer O-pot chamber may be integrated, and two One may be made to have the ability.

Furthermore, in the above embodiments, selective growth of tungsten film was explained, but selective growth of aluminum using organic aluminum such as trimedel aluminum, various high melting point metals using high melting point metal halide and silane gas, etc. It is also applicable to the selective growth of silicides and their silicides.

〔Effect of the invention〕

As described above, according to the thin film forming apparatus of the present invention, a pretreatment chamber for cleaning the surface of a substrate to be processed, and a chemical vapor deposition method (CVD) applied to a specific area of the pretreated substrate to be processed,
A preliminary chamber in which a desired gas atmosphere is formed is provided between the reaction chamber in which a metal thin film is selectively formed by a method (method), and the surface of the substrate to be processed, which has been pretreated in this preliminary chamber, is Since etching is performed with gas or adsorption of gas, the surface activated in the pretreatment process in the pretreatment chamber is inactivated by etching or gas adsorption, and the metal thin film is selectively deposited in the reaction chamber. It is possible to selectively form a metal film that can be formed into a film and has low contact resistance.

[Brief explanation of the drawing]

FIG. 1(a) is a diagram showing a schematic configuration of a thin film forming apparatus according to an embodiment of the present invention, FIG. 1(b) to FIG. a) Noseed tube 2 (d) is a diagram showing the selective CVDI process using the same thin film forming apparatus, and Figure 3 (a)
) and FIG. 3(b) are comparative views showing the surface conditions of a substrate formed using the same thin film forming apparatus and a substrate formed using a conventional thin film forming apparatus, respectively. DESCRIPTION OF SYMBOLS 1... Pretreatment chamber, 2... Reaction chamber, 3... Selectivity recovery chamber, 4... Gate valve, 5... Transfer robot chamber, 6... Substrate to be processed, 7...・Exhaust path, 8... Board storage cassette, 12... High frequency electrode, 13... Blocking capacitor, 14... High frequency power supply, 15...
- Quartz plate, 16... First gas supply path, 21... Second gas supply path, 22... Substrate support stand, 23... Halogen lamp, 24... Quartz window, 31... ...Third gas supply path, 32... Support stand, 33... Halogen lamp, 34... Quartz window, 35... Microwave discharge tube,
36... Fourth gas supply path, 111... Silicon substrate, 112... Insulating film, 113... First aluminum layer, 114... Silicon oxide film, 115... Via hole, 116 ...Tungsten film. Figure 2 (C) Figure 2 (d) Figure 3 (0) Figure 3 (b)

Claims (4)

[Claims] (1) A pretreatment chamber for etching and cleaning the surface of the substrate to be processed, and a chemical vapor deposition method (
In a thin film forming apparatus equipped with a reaction chamber for selectively forming a metal thin film by a CVD method, a pretreated substrate surface is placed between the pretreatment chamber and the reaction chamber in a desired manner. 1. A thin film forming apparatus comprising a preliminary chamber configured to expose to a gas atmosphere and perform chemical etching or gas adsorption. (2) The thin film forming apparatus according to claim 1, wherein the processing chamber is equipped with an etching mechanism using sputtering. (3) Thin film formation according to claim (1), wherein the processing chamber is configured to form a gas atmosphere containing at least oxygen atoms O, nitrogen atoms N, fluorine atoms F, or hydroxyl groups OH. Device. (4) The processing chamber is configured to form a plasma atmosphere of a gas containing at least oxygen atoms O, nitrogen atoms N, fluorine atoms F, or hydrogen atoms H. thin film forming equipment.