JPH01196828A - Manufacture of semiconductor device having carbon film formed thereon - Google Patents

Abstract

PURPOSE:To chemically stabilize a selective etching of carbon or a film containing as a main ingredient carbon by selectively removing the carbon or the film containing the carbon as the main ingredient by plasma oxidized gas. CONSTITUTION:In a gas system 10, hydrogen as carrier gas, hydrocarbon gas as reactive gas, oxidized gas as gas for etching a carbon film, and fluoride gas as etching gas are respectively introduced through a valve 28, a flowrate meter 29 to the nozzles 25, 25' in a reaction system 30. A substrate or gas to be treated is fed from a preliminary chamber 5 into a reaction chamber 4 by opening a gate valve 6, reduced under pressure in the chamber 4 to grow a carbon film or to etch the film. In this case, electric energy is applied from a high frequency electrode 15, a matching transformer 16, and a DC bias power source 17 between a pair of electrodes 2 and 3 to generate a plasma 40, thereby improving the treatment speed.

Description

Detailed Description of the Invention "Field of Application of the Invention" The present invention relates to carbon or a coating mainly composed of carbon (hereinafter simply referred to as carbon film) having a Vickers hardness of 2000 g/mm2 or more or a thermal conductivity of 2.5 W/cm deg or more. This invention relates to a method for manufacturing a semiconductor device by selectively plasma etching.

"Prior Art" Regarding carbon film coating, the patent application filed by the present inventor is entitled "Composite with Carbon Film and Method for Preparing the Same" (Japanese Patent Application No. 56-146936, September 1, 1988).
(filed on the 7th) is known. However, these only discuss the formation of a carbon film, and do not relate to selective etching of this carbon or a film mainly composed of carbon.

``Conventional Problems'' Furthermore, the possibility of applying a dry etching method that facilitates microfabrication, particularly preferably plasma etching, is not known at all. This carbon film has particularly strong chemical resistance and high hardness, so
It seemed impossible to etch it.

However, when considering the industrial application of carbon films, it is extremely important to establish a selective etching method.

The present invention has been made to solve this object.

The present invention involves forming a film of carbon or a film mainly composed of carbon on a semiconductor substrate or a base (the entire board on which electrical wiring, etc. are provided), and then forming a film on this film to form plasma. A mask that has a blocking effect against the oxygenated gas is provided,
The purpose is to turn this carbon film without a mask coating into plasma and remove it by etching with an oxygenate gas.

In the present invention, a hydrocarbon gas such as ethylene or methane is introduced into an atmosphere in which plasma is generated by direct current or high frequency, especially a high frequency electric field with a positive direct current bias applied to the substrate side, and is decomposed into an sp' hybrid gas. Rather than creating a C-C bond with an orbital, resulting in a non-transparent conductive or poorly conductive carbon like graphite, the optical energy band width (called Eg) determined by the fabrication conditions is ) is 1. OeV or more, preferably 1.5
A diamond-like insulating carbon or carbon-based coating having a voltage of ~5.5 eV is formed.

The hardness of the carbon used in the present invention is 2 on the Vickers hardness.
000Kg/mm” or more, preferably 4500Kg/m
m2 or more, ideally has a hardness similar to diamond of 6,500 Kg/mm", or a thermal conductivity of 2.!
IJ/cm deg or more preferably 4.0~6゜OW/
Amorphous with cm deg or 5
Carbon having a semi-amorphous structure with microcrystallinity of ~200 people, or hydrogen or halogen element in this carbon of 25 atomic % or less, or a valence of 7 or
Valance impurity is 5 at% or less, and nitrogen is N/C≦0.0
The present invention is intended to provide a composite body in which carbon (hereinafter simply referred to as carbon in the present invention) whose main component is so-called carbon added to a concentration of 5 is provided on a solid.

The present invention further provides oxygen (02) for this carbon film.

Atmosphere (oxygen, nitrogen mixed gas), No, , NO□, N20
．． An oxygenate gas such as a mixed gas of oxygen and hydrogen or water is introduced into a plasma reactor, preferably into the same reactor in which the carbon film is formed, and a The carbon film on the unmasked portions of the substrate to be etched is removed by plasma etching.

In the present invention, a carbon film is formed on a substrate on which an integrated circuit for microelectronics or the like is formed in a semiconductor, on which bonding pads or electrical wiring are formed, and the carbon film is selectively etched. It is something.

The manufacturing method of the present invention will be described below according to the drawings.

``Example 1'' FIG. 1 shows a plasma CVD apparatus and a plasma etching apparatus for forming carbon or a coating mainly composed of carbon and for selectively etching and removing such a coating for carrying out the present invention. An overview of the plasma processing equipment is shown.

In the drawing, in the gas system (10), hydrogen as a carrier gas is added to (11), a hydrocarbon gas as a reactive gas such as methane or ethylene is added to (12), and an oxygenate gas is used as an etching gas for the carbon film. , for example, oxygen (13
), etching gas of fluoride gas such as sulfur hexafluoride (1
4), is introduced into the nozzles (25) and (25') in the reaction system (30) through the valve (28) and the flow meter (29).

The reaction system (30) has a reaction chamber (4), a preliminary chamber (5) for loading and unloading, and a gate valve (6) between them.
has. The substrate or substrate to be processed is placed in the preliminary chamber (5)
The gate valve (6) is then opened to reach the reaction chamber (4), and after further closing the gate valve (6), a carbon film is formed or etched under reduced pressure in the reaction chamber. .

The reaction chamber (4) has a first electrode (2) and its auxiliary electrode (2'), a processing substrate (1) having a surface to be formed or a surface to be etched, and a second electrode (3); Between the pair of electrodes (2) and (3), there is a high frequency electrode (15), a matching transformer (16), and a DC bias power source (17).
More electrical energy is applied and plasma (40) is generated. In order to further decompose the reactive gas, 2.
．． 200 min in an excitation chamber (26) with a 45 GHz microwave.
Give microwave excitation of W ~2KW. As a result, the amount of active reactive gas could be increased, and the rate of carbon film formation could be increased by about five times, and the rate of processing and soching carbon with oxygen could be increased by about four times.

These reactive gases are present in the reaction space (40) at a concentration of 0.01 to
1 torr, for example, Q, and 50W to 5KW of energy can be applied by high frequency electromagnetic energy.

The DC bias is applied to the surface to be formed at -200 to 600 V (
Substantially -400 to +400V) is applied. This is because when the DC bias is zero, the self-bias is 1200V.
(with the second electrode at ground level).

The reactive gas for film formation was, for example, methane:hydrogen=1:1. For example, a cooling or heating means (9) is provided on the back side of the first electrode (2) to keep the substrate temperature at 150 to -100°.
Let C hold it. Thus, the plasma (40) causes the surface to be formed to have a Vickers hardness of 2000 Kg/mm" or more, and/or a thermal conductivity of 2.5 W/cm de
Carbon having an amorphous structure or a microcrystalline structure in which a large number of C--C bonds of 1 g or more were formed was produced. Furthermore, this electromagnetic energy supplied 50 W to IKW, and added plasma energy of 0.03 to 3 W/cm'' per unit area. 50-150°C,
When applying a DC bias of +100 to 300 V, the film formation rate is 100 to 200 people/min (when using methane and not using microwaves), and 500 to 1000 people/minute (when using methane and using microwaves). , or using ethylene and microwaves) were obtained.

All of these have a Vickers hardness of 2000Kg/mm.
``Only products that meet the above conditions are considered good quality.

Of course, if graphite is the main component (50% or more), it is extremely soft and black, which is completely different from the present invention.

This reaction product is formed as a film on the upper surface of the substrate (1). Unwanted substances after the reaction are exhausted from the exhaust system (20) via the turbo molecular pump (22) and the rotary pump (23). The reaction system is maintained at 0.001 to 10 torr (typically 0.01 to 0.5 torr), and a plasma state (40) is created in the reaction system by microwave (26) and high frequency energy (15). generated. In particular, when the excitation source has a frequency of IGHz or higher, for example 2.45GHz, hydrogen is separated from the C-H bond, and the high frequency source
．． At frequencies of 1 to 50 MHz, for example 13.56 MHz, C-C bonds and C-C bonds are decomposed to create C-C bonds or -C-C- bonds, and the unpaired bonds of carbons are separated from each other. Collision causes covalent bonding, resulting in a structure locally having a stable diamond structure.

Thus, carbon or P containing up to 25 mol% of hydrogen in carbon, especially carbon, on a semiconductor (e.g. silicon ueno\),
It was possible to form a film mainly composed of carbon having I or N type conductivity.

“Example 2” Figure 2 shows carbon (3
A mask (35) having a blocking function is selectively provided on the substrate coated with 4), and using this mask, the carbon film (35) prepared in advance in Example 1 is placed under the mask.
An example of selectively etching is shown below. The temperature of the substrate (31) was set to room temperature.

In FIG. 2, silicon oxide, photoresist, or silicon nitride was selectively formed as a mask (35) as an insulating film on a substrate or a carbon film (34) on a substrate (31) by a known method.

Furthermore, the entire structure including this mask was placed in the plasma processing apparatus shown in FIG. 1, in this case a plasma etching apparatus, and oxygen (13) was introduced from the gas system (10).

A high frequency electric field was then applied between the pair of electrodes (3) and (2). Then the voltage is 0.01 to 1 torr, for example 0.
The carbon film could be etched at an etching speed of 350 people/min at a high frequency output of 300 at a pressure of 1 torr. If this pressure is 0.05 torr, then the
The cutting speed was reduced to 270 people/min.

As a result, the sloop rate was increased and the mass productivity was excellent.

After the etching process, the mask is removed and the carbon film (
34-1), (34-2), and (34-3) were provided, and as a result, FIG. 2(B) was obtained. That is, the substrate (31
) was selectively coated with a carbon film (34).

"Example 3" FIG. 3 shows another embodiment of the invention.

In FIG. 3, a semiconductor substrate such as a silicon substrate (31
) is provided with an insulating film (for example, a silicon oxide film (37)) with a window formed thereon. Furthermore, aluminum, silicon, silver,
Electrical wiring (32) of oxide superconducting material is made by known patterning methods. Thereafter, a blocking layer (33) was provided to prevent the electrical wiring from becoming oxidized and insulated even when exposed to an oxygenate gas plasma atmosphere. Here, in the case of the insulating film, a silicon oxide film, phosphorous glass, or a silicon nitride film was used. Furthermore, according to Example 1, 0.1 to
A carbon film (3
4) was formed.

Furthermore, a mask was provided on this, except for the area where the carbon film (34) was to be removed by etching in an oxygenate gas plasma atmosphere. This drawing shows an example of removing a carbon film on a bonding pad.

In this example, organic resin was used as this mask.

As an example, a photoresist was provided on top of these.

Since this photoresist will be slightly etched by the oxygenated gas plasma, it must have sufficient plasma resistance, hardness, or thickness to ensure that the carbon in the window (36) remains long enough to be completely removed. do.

If the photoresist is not sufficiently resistant to plasma oxide gases, create a film under the photoresist mask that is resistant to the re-plasmaized oxygenate gas, such as a silicide oxide film, and use the photoresist as a mask. First, the underlying silicon oxide film is etched by introducing fluoride gas from the gas system shown in FIG. Next, the entirety of these reaction chambers is replaced with oxygenated gas which has been turned into plasma, and the entire upper portion of the gas is subjected to an etching process. This oxygenated gas plasma can then remove carbon at the window (36) in addition to removing the photoresist by ashing.

In FIG. 3(B), carbon in the window (36) underneath is removed using photoresist or silicon oxide as a mask (35).

After this, the gas introduced in the gas system shown in FIG. 1 is fluoride gas (14), and the blocking layer (3) above the window (36) is
3') was removed by etching.

FIG. 3(C) shows the mask (35) removed by a known method after these treatments.

When the pronking layer (33') is made of silicon oxide, the mask (
It can be removed simultaneously with the removal of 35), and the process can be simplified.

Thus, after coating with the carbon film of the present invention, the wafer is probe tested, and furthermore, in order to make each IC chip, it goes through a scribing and breaking process, and the configuration in which each semiconductor chip is coated with a carbon film on its upper surface is made into individual IC chips. Completed with bonding and wire bonding.

"Example 4" This example is based on the blocking layer (33) in the example.
An example is shown when is used as a conductor. That is, a carbon film is placed on the upper surface of a silicon wafer on which a semiconductor integrated circuit has been formed in advance.
It was formed as shown in the figure.

That is, an insulating film such as a silicon oxide insulating film (37), an electrical wiring (32), a blocking layer of a conductor (
33), and has a carbon film (34). In this case, the bonding pads or electrical wiring were made of aluminum, impurity-doped silicon, or metal silicide. The conductor blocking layer is made of a material that does not become an insulator when oxidized, such as gold, platinum, chromium, silicon (silicon doped with impurities), metal silicide, or oxide superconducting ceramic.

Then, the oxide insulator of the conductor film (33) was not formed on the top of the conductor by plasma etching, and the bonding work could be easily performed.

That is, for example, an aluminum electrical circuit (32) and a gold blocking Ff (33') on the top side of a silicon wafer.
After forming a batt and electrical wiring, a carbon film of the present invention was formed thereon to a thickness of 0.1 to 2 μm, for example, 0.5 μm. Further, as shown in Example 3, a mask for selective removal was selectively provided, and the carbon film was removed, for example, only at the bonding pad portion by plasma etching with oxide gas. He then revealed a metal bat. Additionally, the mask was removed. Then, a carbon film was formed as a final coat film on the upper surface of the chip.

In this way, due to the high thermal conductivity of the carbon film, the heat locally heated by the power transistor etc. could be quickly spread over the whole, making it possible to prevent the electrical properties from deteriorating or decreasing locally.

In addition, blocking against sodium ions has become possible.

"Embodiment 5" FIG. 5 shows another embodiment of the present invention. In this drawing, electrical wiring (32) is formed on an insulating substrate such as a glass substrate or a glazed ceramic substrate by a printing method or a photoetching method. Furthermore, as shown in Example 1, carbon or a coating mainly composed of carbon (3
4) was formed to a thickness of 0.2 to 2 μm. After that, a metal mask (41) was used to cover the other parts except for the opening (36). These were then placed in an oxygenate gas plasma atmosphere as shown in Example 2. Then a metal mask,
For example, the carbon film in the opening (36) provided in the stainless steel mask with a thickness of 50 to 500 μm could be selectively removed.

In the present invention, another second electrical wiring may be formed on this carbon film. Also, after forming carbon or carbon film,
A method of forming electrical wiring may also be used.

In either case, the heat generated in the electrical wiring portion can be quickly diffused over the entire surface, thereby preventing local temperature rise.

"Embodiment 6" FIG. 6 shows another embodiment of the present invention. The main process was according to Example 3.

FIG. 6 has a semiconductor substrate (3 parts), an insulating film (37), a first electrical wiring (32), and its contact (38). Example 1 A first carbon film (34) was applied to all of these.
It was coated according to the following. After this, other openings (38') and (38''
) was opened. The opening (38") is an interconnection between multilayer wiring by selective etching of the carbon film, and the opening (38')
is for connection with the substrate (31). Further, a second electrical wiring (32') was formed by forming an aluminum film using a sputtering method or the like. Furthermore, another second carbon film or other passivation film (39) was formed on these. The opening (36) of the bonding pad portion is opened.

In this case, the carbon film (34) was provided below the second electrical wiring, and this carbon film was able to prevent sodium and the like from entering into the substrate from the outside.

It was also possible to prevent local heat generation due to large current operation of power transistors and the like within the semiconductor substrate.

Further, the second electric circuit can be surrounded by carbon films on both upper and lower surfaces so that it does not come into contact with other insulating films.

"Effects" By the method of the present invention, selective etching of a chemically extremely stable carbon film was achieved for the first time, and thus it could be used for interlayer insulating films such as final coatings of semiconductor integrated circuits and the like. It is also extremely effective for electrical components that run by rubbing against thermal surfaces and other surfaces. In particular, this carbon film has a thermal conductivity of 2.5 W/cm deg or more, typically 4.0 to 6. OW/cmdeg and diamond 6
．． Since it is close to 6W/cm deg, the heat generated by high-speed tape-shaped carrier running and the heat generated by local large currents inside the IC are uniformly dispersed and released, preventing local temperature rise and resulting characteristic deterioration. Since deterioration of properties can be prevented, many properties such as wear resistance, high thermal conductivity, and high smoothness unique to carbon films are effectively used in combination.

In the present invention, as an oxide superconducting material used in an electric circuit, (A+-x Bx)ycuzow x =0.3~
1+y=2~4. z = 1.5-3.5. lol
= 4 to 10, and A is group MA of the periodic table of elements;
A typical example is a high-temperature superconducting material consisting of one or more elements of group II [B, Va, and Vb groups, where B is one or more elements of Ua group of the periodic table of elements. For example, Bi, Sr+Ca, Cu2~xOn ~to+
YBazCu30b~a+Yo, 5Bio, 5Sr
lCa ICuz~xL ~l 01 Bi tsr
+Mgo, 5Cao, ,Cuz~304~+o+
Bio, 5AIo, 5SrlCa+Cuz~30n~
It can be raised to 10 mag. These materials are AI, C
Similarly to U, Au, etc., the thin films for electrical circuits of Examples 3 to 6 can be obtained using electron beam evaporation, sputtering, photo-CVD, and photo-PVD.

[Brief explanation of the drawing]

FIG. 1 schematically shows an apparatus for forming or etching carbon or a film containing carbon as a main component according to the present invention. 2, 3, 4, 5 and 6 show embodiments of the invention.

Claims (1)

[Claims] 1. A step in which at least one semiconductor element is provided on a semiconductor substrate, and an electrical wiring or bonding pad is formed above the semiconductor substrate, and an oxygen oxide formed into plasma is formed on the electrical wiring or the bonding pad. A step of forming a gas blocking layer and a carbon or carbon-based film, and a mask is provided on the film to remove unnecessary carbon or carbon-based film, such as on a bonding pad. A method for manufacturing a semiconductor device on which a carbon film is formed, comprising the step of selectively removing carbon or a film containing carbon as a main component using the oxygenated gas turned into plasma. 2. In claim 1, the carbon film is characterized in that the blocking layer is made of an organic resin, silicon oxide, silicon nitride, or a composite film thereof, or an oxidation-resistant metal such as gold, platinum, or chromium. A method for manufacturing a semiconductor device having a structure formed therein. 3. In claim 1, the oxygenate gas to be turned into plasma is oxygen, atmosphere (mixed gas of oxygen and nitrogen),
A method for manufacturing a semiconductor device having a carbon film formed thereon, characterized by comprising water, N_2O, NO, NO_2, or a composite gas thereof.