JP2000306899A - Method of etching carbon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To implement the use of an interlayer insulating film, such as a final coating for an integrated circuit or the like by forming a film soncisting mainly of carbon on a substrate, arranging a mask having a blocking action on the film, and removing by plasma etching the carbon film not covered with a mask film. SOLUTION: An insulating film 37 and an electrical wiring 32 are formed on a silicon substrate 31. Thereafter, a blocking layer 33 is arranged for preventing the wiring 32 from being oxidized and insulated, and a carbon film 34 is formed on the layer 33. Furthermore, a photoresist or silicon oxide mask 35 is arranged on the film 34 while excluding the region from which the film 34 is removed by etching in a plasma atmosphere of oxygenated material gas. By replacing the atmosphere in the entire reaction chamber with an atmosphere consisting of the oxygenated material gas made into plasma, the whole upper portion of the substrate 31 is etched. As result, the oxygenated material gas activated by plasma can remove not only the photoresist by ashing but also carbon at a window 36. After these processing steps, the mask 35 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a Vickers hardness of 2000 g / mm ²
Method for selectively plasma-etching carbon or a film containing carbon as a main component (hereinafter simply referred to as a carbon film) having a thermal conductivity of 2.5 W / cm deg or more, and furthermore, a carbon film for an electronic device using this plasma etching method. Related to membrane applications.

[0002]

2. Description of the Related Art With respect to coating of a carbon film, a patent application filed by the present inventor "Composite having a carbon coating and a method for producing the same" (Japanese Patent Application No. 56-146936, filed on Sep. 17, 1981) It has been known. However, these documents only relate to the formation of a carbon film, and do not relate to selective etching of the carbon or a film containing carbon as a main component.

[0003]

Further, there is no known possibility of applying a dry etching method for easily performing fine etching, particularly preferably a plasma etching method. And it was thought that etching was impossible because this carbon film had particularly high chemical resistance and high hardness. However, considering the industrial application of carbon films, establishment of a selective etching method is extremely important. The present invention has been made to solve such an object.

[0004]

According to the present invention, carbon or a film containing carbon as a main component is formed on a substrate or a base (the entirety on which electric wiring and the like are provided on the substrate), and a plasma is formed on the film. A mask having a blocking effect on an oxygenate gas is provided, and the carbon film without the mask film is turned into plasma and removed by etching with the oxygenate gas.

According to 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, particularly a high frequency electric field in which a positive direct current bias is applied to the solid side, and is decomposed. Creates a C—C bond with SP ³ hybrid orbitals, resulting in an optical energy bandwidth determined by fabrication conditions, rather than a non-transparent or poorly conductive carbon such as graphite. (Eg) is 1.0 eV or more, preferably 1.
An insulating carbon or carbon-based coating similar to diamond having a 5-5.5 eV is formed.

The carbon used in the present invention has a Vickers hardness of 2000 kg / mm ² or more, preferably 4500 kg / mm ² or more, and ideally 6500 kg / mm ^{2, which} is similar to diamond. Amorphous (amorphous) structure having thermal conductivity of 2.5 W / cm deg or more, preferably 4.0 to 6.0 W / cm deg or semi-amorphous (semi-amorphous) structure having microcrystallinity of 5 to 200 mm Or a carbon having hydrogen or a halogen element of 25 atomic% or less or a trivalent or pentavalent impurity of 5 atomic% or less, and nitrogen having N / C ≦
A composite in which so-called carbon (hereinafter simply referred to as "carbon" in the present invention) added at a concentration of 0.05 on a solid is provided. In the present invention, oxygen (O ₂ ), air (mixed gas of oxygen and nitrogen), NO, NO ₂ , N ₂ O, mixed gas of oxygen and hydrogen, and oxygenated gas such as water are further applied to the carbon film. The carbon film in the unmasked portion on the substrate to be etched, which is introduced into the plasma reactor, preferably in the same reactor as the one in which the carbon film was formed, and which is pre-arranged in this device Is removed by plasma etching.

Another feature of the present invention is that the solid surface to be plasma-etched is formed at a temperature lower than 150 ° C., preferably as low as -100 to 100 ° C., preferably at room temperature.
In addition, the substrate or the substrate in the present invention can use a semiconductor material, a glass material, a ceramic material, a metal material, a composite material thereof, or the like. A semiconductor substrate is used as a special substrate. Alternatively, a carbon film may be formed on a substrate on which a bonding pad or an electric wiring is formed on a substrate in which a microelectronic integrated circuit or the like is formed in a semiconductor, and the carbon film may be selectively etched and used. The present invention
It is particularly effective for electrical components that have high thermal conductivity, are wear-resistant materials, and require slip resistance on the surface. The manufacturing method of the present invention will be described below with reference to the drawings.

[0008]

EXAMPLE 1 FIG. 1 shows a plasma CVD apparatus and a plasma CVD apparatus for forming a carbon or carbon-based film for carrying out the present invention and selectively removing the film by etching. An outline of an etching apparatus, that is, a plasma processing apparatus is shown. In the drawing, in the gas system (10), hydrogen as a carrier gas is converted from (11) to hydrocarbon gas as a reactive gas, for example, methane and ethylene from (12), and oxygenates as etching gases for a carbon film. A gas, for example, oxygen (13), an etching gas of a fluoride gas such as sulfur hexafluoride from (14) through a valve (28) and a flow meter (29) to the reaction system.
It is introduced to the nozzles (25) and (25 ') in (30).

The reaction system (30) has a reaction chamber (4) and a spare chamber (5) for loading and unloading, between which a gate valve (6) is provided.
Having. The substrate or substrate to be processed reaches the reaction chamber (4) by opening the gate valve (6) from the preliminary chamber (5), and further closing the gate valve (6). A carbon film is formed or a carbon film is etched. Reaction chamber
In (4), a first electrode (2) and its auxiliary electrode (2 '), a processing substrate (1) having a surface to be formed or etched, and a second electrode (3) are provided. Electric energy is applied between the electrodes (2) and (3) by a high-frequency power supply (15), a matching transformer (16), and a DC bias power supply (17) to generate a plasma (40). In order to further decompose the reactive gas,
A microwave of 200 W to 2 KW is applied in the excitation chamber (26) with a microwave of 2.45 GHz. As a result, the amount of the active reactive gas could be increased, and the film formation rate of carbon could be improved about 5 times, and the etching rate of carbon with oxygen could be improved about 4 times. An exhaust system (20) exhausts unnecessary gas through a pressure regulating valve (21), a turbo molecular pump (22), and a rotary pump (23).

[0010] These reactive gases are present in the reaction space (40) at a concentration of 0.1 mm.
01 to 1 torr, for example, 0.1 torr, and an energy of 50 W to 5 KW can be applied by high frequency electromagnetic energy. DC bias is -200 to 600 V (effectively -400 to
+ 400V). This is because when the DC bias is zero, the self-bias has -200 V (the second electrode is at the ground level).

The reactive gas for film formation is, for example, methane: hydrogen = 1: 1. On the back side of the first electrode (2), for example, a cooling or heating means (9) is provided, and the substrate temperature is set to 150 to -100 ° C.
To be held. Thus Vickers on the formation surface by a plasma (40) - having's hardness 2,000 Kg / mm ² or more, or / and, an amorphous structure or a fine crystal structure to form a large number of thermal conductivity of 2.5 W / cm deg or more CC bond Having an amorphous structure. Further, this electromagnetic energy supplies 50 W to 1 KW, and 0.03 to 3 W / cm ² per unit area.
Of plasma energy was applied. The deposition rate is 100-1000
A / min, especially when the surface temperature is -50 to 150 ° C and DC bias is +100 to 300 V, the film formation rate is 100 to
200 A / min (with methane and no microwave),
500 to 1000 A / min (in the case of using methane with microwaves or in the case of using ethylene with microwaves) were obtained. All of these are acceptable under the condition that the Vickers hardness is 2000 kg / mm ² or more. Of course, if graphite is the main component (50% or more), it is very 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). Unnecessary substances after the reaction are exhausted from an exhaust system (20) through a turbo molecular pump (22) and a rotary pump (23). The reaction system is typically from 0.001 to 10 torr, typically from 0.01 to 0.5 torr.
The plasma state (40) is generated in the reaction system by the microwave (26) and the high-frequency energy (15). In particular, when the excitation source is at a frequency of 1 GHz or more, for example, 2.45 GHz, hydrogen is separated from the CH bond, and when the high frequency source is at a frequency of 0.1 to 50 MHz, for example, 13.56 MHz, C
-C bond, C = C bond is decomposed, and CC bond or -C
A -C- bond is formed, and unpaired carbon atoms collide with each other to form a covalent bond, whereby a structure having a stable diamond structure locally is obtained. Thus, on a solid surface on which a solid of a semiconductor (for example, a silicon wafer), ceramics, a magnetic material, a metal or an electric component is disposed, carbon or P-, I- or N-type containing carbon, in particular, containing not more than 25 mol% of hydrogen in carbon. It was possible to form a coating mainly composed of carbon having conductivity type.

Example 2 FIG. 2 shows that a mask (35) having a blocking function is selectively provided on a substrate coated with carbon (34) obtained by the manufacturing method of Example 1,
An example in which the carbon film (35) formed in advance in Example 1 below the mask is selectively etched using this mask will be described. The temperature of the substrate (31) was room temperature. In FIG. 2, as a mask (35), as an insulating film, silicon oxide, photoresist, and silicon nitride are selectively formed on a substrate or a carbon film (34) on the substrate (31) by a known method.

Further, the entire structure including the mask was disposed in the plasma processing apparatus shown in FIG. 1, in this case, a plasma etching apparatus, and oxygen (13) was introduced from a gas system (10).
Then, a high-frequency electric field was applied between the pair of electrodes (3) and (2). Then, set the voltage to 0.01 to 1 torr, for example, 0.1 torr, and output high frequency
The carbon film could be etched at an etching rate of 350 mm / min at 300 W. With this pressure at 0.05 torr, the etch rate was reduced to 270 ° / min. As a result, the throughput was increased and the mass productivity was excellent. After the etching treatment, the mask was removed and carbon films (34-1), (34-2), and (34-3) were selectively provided, and as a result, FIG. 2B was obtained. That is, it was possible to obtain a substrate in which the carbon film (34) was selectively coated on the substrate (31). The base has a semiconductor element, electric wiring, a heating element of a thermal head, and the like. And as a part of the substrate, a glass substrate, a semiconductor substrate,
A ceramic substrate or the like can be used for the substrate.

Embodiment 3 FIG. 3 shows another embodiment of the present invention. In FIG. 3, a semiconductor substrate such as a silicon substrate (3
1) An insulating film, for example, a silicon oxide film (37) is provided on the upper surface with openings. Further, electrical wirings (32) of aluminum, silicon, silver, and oxide superconducting materials are made by a known patterning method. Thereafter, a blocking layer (33) was provided to prevent the electrical wiring from being oxidized and insulated even when exposed to a plasma atmosphere of an oxygenate gas. Here, in the case of an insulating film, a silicon oxide film, a phosphorus glass, or a silicon nitride film was used. Further, a carbon film (34) was formed thereon in a thickness of 0.1 to 2 μm, for example, 0.5 μm according to Example 1.

Further, a mask was provided on the other portion except for the region where the carbon film (34) was to be removed by etching in a plasma atmosphere of an oxygenate gas. This drawing shows an example in which the carbon film on the bonding pad is removed. In this example, an organic resin was used as the mask. As an example, a photoresist was provided on these. Since this photoresist is slightly etched by the plasma oxygenated gas, it is necessary to have the plasma resistance, hardness or thickness necessary to leave the carbon in the window (36) to the extent that it is completely removed. I do. If the photoresist is not sufficiently resistant to plasma oxide gas, a photoresist, for example, a silicide oxide film, is formed under the photoresist mask to withstand the re-plasmaized oxygenate gas. First, the underlying silicon oxide film is etched by introducing a fluoride gas from the gas system in FIG. Next, the entirety of these reaction chambers is replaced with oxygenated gas that has been turned into plasma, and the entire upper portion of the gas is subjected to etching. Then, in addition to the removal of the photoresist by ashing, the carbon in the window (36) can be removed by the plasmated oxygenate gas.

FIG. 3B shows a state in which a photoresist or silicon oxide is used as a mask 35 to remove carbon in a window 36 below the mask. Thereafter, the gas introduced in the gas system shown in FIG. 1 is changed to a fluoride gas (14), and the blocking layer (3
3 ') was removed by etching. FIG. 3C shows the mask (35) removed by a known method after these processes. When the blocking layer (33 ') is made of silicon oxide, a mask (3
It can be removed simultaneously with the removal of 5), and the process can be simplified. Thus, after the coating of the carbon film of the present invention, a probe test of the wafer is performed, and in order to make each IC chip, a scribe and break process is performed, and each semiconductor chip is coated with a carbon film on the upper surface. The completed configuration was completed by die bonding and wire bonding.

[Embodiment 4] This embodiment shows an example in which the blocking layer (33) in Embodiment 3 is used as a conductor.
That is, a carbon film was formed as shown in FIG. 4 on the upper surface of a silicon wafer on which a semiconductor integrated circuit had been formed in advance. That is, an insulating film, for example, a silicon oxide insulating film (37), an electric wiring (32), a conductor blocking layer (33), and a carbon film (34) are provided on the substrate (31). In this case, the bonding pad or the electric wiring was made of aluminum, doped silicon, or metal silicide. The blocking layer of the conductor is gold, platinum, chromium,
Oxidation of silicon (silicon doped with impurities), metal silicide, oxide superconducting ceramics, or the like does not become an insulator. Then, the oxide insulating material of the conductor film (33) did not have an insulating film formed on the conductor by the plasma etching treatment, so that the bonding operation could be easily performed.

That is, for example, an aluminum electric circuit (32) and a gold blocking layer (33) on the upper surface of a silicon wafer
After the pad and the electric wiring were formed, the 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 only the bonding pad portion was removed from the carbon film by plasma etching of an oxide gas. Then, the metal pad was exposed. Further, the mask was removed. Then, a carbon film was formed on the upper surface of the IC chip as a final coat film. In this case, due to the high thermal conductivity of the carbon film, the heat locally heated by the power transistor or the like can be promptly spread to the whole, and it is possible to prevent the electrical properties from being locally deteriorated or reduced. In addition, blocking against sodium ions became possible.

Embodiment 5 FIG. 5 shows another embodiment of the present invention. In this drawing, electric wiring (32) was formed on an insulating substrate such as a glass substrate or a glazed ceramic substrate by a printing method or a photo-etching method. Further, as shown in Example 1, a coating (34) containing carbon or carbon as a main component was formed on the entire surface to a thickness of 0.2 to 2 μm.
Thereafter, the other portions were covered with the metal mask (41) except for the opening (36). These were placed in an oxygenated gas plasma atmosphere as shown in Example 2. As a result, the carbon film in the opening (36) provided in a metal mask, for example, a stainless mask having a thickness of 50 to 500 μm, could be selectively removed. Although this method of etching only by aligning the metal mask has a drawback that high accuracy is not obtained in mask alignment accuracy, it is coated in close contact with the surface to be etched of the photoresist, developed, plasma etched and Another feature is that there is no complicated process such as the subsequent stripping of the photoresist. In the present invention, another second electric wiring may be formed on this carbon film. Alternatively, a method of forming an electric wiring after forming carbon or a carbon film may be used. In any case, heat generated in the electric wiring portion can be quickly diffused over the entire surface, and local temperature rise can be prevented.

Embodiment 6 FIG. 6 shows another embodiment of the present invention. The main process followed Example 3. FIG. 6 has a semiconductor substrate (31), an insulating film (37), a first electric wiring (32), and a contact (38) thereof. A first carbon film (34) was coated on the whole according to Example 1. Then, after this, another opening (38 '),
(38 '') was opened. The opening (38 '') is the interconnection between the multilayer wirings by selective etching of the carbon film, and the opening (38 ') is the substrate
For connection with (31). Further, a second electric wiring (32 ')
Was formed by aluminum film formation or the like by a sputtering method or the like. Further, another second carbon film or another passivation film (39) was formed thereon. The opening (36) of the bonding pad is opened. In this case, the carbon film (34) was provided below the second electric wiring, and this carbon film could prevent sodium or the like from entering from outside into the substrate. And local heat generation due to a large current operation of a power transistor or the like in the semiconductor substrate could be prevented. Alternatively, the second electric circuit may be configured so that both upper and lower surfaces are surrounded by carbon films and not in contact with another insulating film.

[0022]

According to the method of the present invention, selective etching of a chemically extremely stable carbon film can be performed for the first time, so that the carbon film can be used for an interlayer insulating film such as a final coating of a semiconductor integrated circuit. It is also very effective for electric members that run by rubbing the thermal head and other surfaces. In particular, this carbon film has a thermal conductivity of 2.5 W / cm deg or more, typically 4.0 to 6.0 W / cm deg.
Because the temperature is close to deg, the heat generated by high-speed tape-shaped carrier running and the heat generated by the generation of a large local current in the IC are uniformly dispersed and released throughout, causing a local temperature rise and the accompanying deterioration in characteristics and characteristics. Since the deterioration can be prevented, many characteristics such as abrasion resistance, high thermal conductivity, and high smoothness unique to the carbon film are effectively used in combination.

In the present invention, as the oxide superconducting material,
(A_1-XBx) CuzOw x = 0.3 to 1, y = 2 to 4, z = 1.5 to 3.
5, w = 4 to 10, where A is group 3a of the periodic table of the element,
From one or more of the group 3b, 5a and 5b elements
And B represents one of the elements of Group 2a of the periodic table or
A typical example is a high-temperature superconducting material composed of a plurality of types. An example
For example Bi₁Sr₁Ca₁Cu_Two~_ThreeO_Four~_Ten, YBa_TwoCu_ThreeO₆~ ₈, Y_0.5Bi_0.5S
r₁Ca₁Cu_Two~_ThreeO_Four~_Ten, Bi₁Sr₁Mg_0.5Ca_0.5Cu_Two~_ThreeO_Four~_Ten, B
i_0.5Al_0.5Sr₁Ca₁Cu_Two~_ThreeO_Four~_TenEtc. can be raised
You. These materials are electron beam deposited like Al, Cu, Au etc.
Example 3 using the sputtering method, the sputtering method, the photo CVD method, and the photo PVD method
~ 6 thin films for electric circuits.

[Brief description of the drawings]

FIG. 1 shows an outline of an apparatus for forming or etching carbon or a film containing carbon as a main component of the present invention.

FIG. 2 shows an embodiment of the present invention.

FIG. 3 shows an embodiment of the present invention.

FIG. 4 shows an embodiment of the present invention.

FIG. 5 shows an embodiment of the present invention.

FIG. 6 shows an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 31 Substrate 37 Silicon oxide insulating film 32 Electric wiring 33 Blocking layer 34 Carbon film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/768 H01L 21/90 KA

Claims (3)

[Claims] 1. A method of etching a carbon film, comprising: forming a blocking layer; forming a carbon film on the blocking layer; and etching the carbon film. 2. a step of forming a first blocking layer; a step of forming a carbon film on the first blocking layer; and a step of forming a second blocking layer on the carbon film. A method of etching a carbon film, comprising: patterning the second blocking layer; and etching the carbon film using the second blocking layer as a mask. 3. The method according to claim 1, wherein the blocking layer is a silicon oxide film or a silicon nitride film.