JP4724273B2 - Substrate surface treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a substrate surface treatment method. The substrate surface treatment method of the present invention is useful for the surface treatment of a semiconductor substrate, and a metal film (UBM film; in a bump formation region) when manufacturing various electronic components, for example, semiconductor devices such as diodes, transistors, LSIs and the like. It can be suitably used for forming a metal film pattern of under bump metal.
[0002]
[Prior art]
A semiconductor device having a metal electrode such as an aluminum electrode is known. Bumps are formed on the aluminum electrode by solder or the like, but the solder and the aluminum electrode have poor wettability. Therefore, a metal film pattern is formed on the aluminum electrode by a metal film having good wettability with solder or the like.
[0003]
The pattern formation of the metal film in the manufacture of a semiconductor device is generally performed by a pattern formation method by photolithography. However, the above-described pattern formation by photolithography has a problem that the process cost of equipment and the like in photolithography and etching processes is very high, and the waste liquid treatment such as an etching solution is troublesome and the working environment is deteriorated.
[0004]
Recently, as a method for forming the metal film pattern, a metal film having good wettability is provided on the surfaces of the insulating part and the electrode part formed on the semiconductor substrate, and the insulating part and the electrode part with respect to the metal film are provided. A method of forming a pattern by peeling and removing only the metal film on the insulating portion with an adhesive sheet by using the difference in adhesiveness has also been proposed (Japanese Patent Laid-Open No. 10-64912).
[0005]
In such a pattern forming method using the metal film peeling and removing adhesive sheet, the metal film on the insulating portion other than the portion where the metal film is to be formed is peeled and removed without leaving the adhesive sheet, that is, the metal film on the insulating portion. The certainty of peeling is required. However, if the adhesion between the insulating film and the metal film is high, it is difficult to peel and remove the metal film on the insulating portion in a completely patterned form.
[0006]
[Problems to be solved by the invention]
The present invention relates to a convex portion of a substrate having a concavo-convex shape on the surface thereof (for example, a semiconductor substrate having a convex insulating portion and a concave electrode portion formed on the surface thereof used for forming a metal film pattern) in semiconductor device manufacturing. It is an object of the present invention to provide a substrate surface treatment method capable of selectively modifying only the substrate.
[0007]
It is another object of the present invention to provide a method for forming a metal film pattern using the substrate surface treatment method.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above object can be achieved by the following method and have completed the present invention.
[0009]
That is, the present invention provides a flat plate-like shape made of a surface member containing a fluorine-containing resin or a fluorine-adhesive substance only on the convex insulating portion on the substrate (A) on which the convex insulating portion and the concave electrode portion are formed. By performing heat treatment in a state where the surface portion of the sheet-like article (B) is in contact, a part of the surface member containing the fluorine-containing resin or the fluorine-adhesive substance is formed on the convex insulating portion on the substrate (A). After transferring and applying a surface treatment that weakens the adhesion of the convex insulating part to the metal film formed on the surface of the convex insulating part and the concave electrode part, a metal is formed on the convex insulating film and the concave electrode part. A step of forming a film and a step of peeling off the adhesive sheet after applying an adhesive sheet to the entire surface of the outermost layer portion of the formed metal film, thereby selectively selecting the metal film on the surface of the convex insulating portion. A semiconductor characterized by peeling and removing A method of forming a metal film pattern only in the recess electrode portion on the substrate, relates.
[0010]
According to the above method, by appropriately selecting the surface member of the article (B), a desired treatment can be performed only on the surface of the convex portion, and the properties of the convex surface and the concave surface are differentiated. Can do.
[0012]
According to the surface member of the object product (B) in the method of transferring the convex portion insulating portion on the substrate (A), it is possible to perform property change of the convex portion insulating portion easily.
[0013]
Examples of the surface member of the article (B) to be transferred to the convex insulating portion on the substrate (A) include those containing a fluorine-containing resin.
[0014]
By transferring the fluorine-containing resin to the convex insulating portion on the substrate (A), the free energy of the convex insulating portion can be reduced, and the adhesion of the convex insulating portion on the substrate (A). Can be weakened effectively.
[0015]
Moreover, as a surface member of the article (B) to be transferred to the convex insulating portion on the substrate (A), a material containing a fluorine-adhesive substance can be mentioned.
[0016]
The fluorine adhesive substance can be easily transferred to the convex insulating portion on the substrate (A), can reduce the free energy of the surface portion, and has an effect on the adhesion of the convex insulating portion on the substrate (A). Can be weakened.
[0019]
Only on the surface of the convex portion insulating portion on a semiconductor substrate, by performing the pre-Symbol transfer process, can be weakened and the convex portion insulating portion, the adhesion between the metal film subsequently formed effectively, This improves the peelability of the metal film. On the other hand, since the surface treatment is not performed on the recessed electrode part, the adhesion with the metal film does not deteriorate. In this way, by selectively processing only the convex insulating portion on the semiconductor substrate, a favorable result is obtained in the formation of the metal film pattern using the adhesive sheet.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
In the following, a method for forming a metal film pattern on a substrate in the semiconductor manufacturing process will be described in detail by taking as an example the case of using a semiconductor substrate as the substrate (A). The substrate surface treatment method of the present invention is not limited to these examples.
[0021]
FIG. 1 is a cross-sectional view of a semiconductor substrate 1 in which a convex insulating part 3 and a concave electrode part 4 are formed. A metal electrode pattern is formed on the electrode part 4.
[0022]
An example of the semiconductor substrate 1 is a silicon substrate. In addition, a semiconductor element region 2 such as a diode or a transistor can be formed on the semiconductor substrate 1 of the present invention. The electrode part 4 is patterned in order to obtain conduction with the semiconductor element 2. The method for forming the insulating portion 3 and the electrode portion 4 on the semiconductor substrate 1 is not particularly limited, and can be formed by various methods. For example, the insulating part 3 and the electrode part 4 are formed by forming the insulating part 3 on the semiconductor substrate 1 by the CVD method or the like, and then patterning the insulating part 3 by using the photolithography method, and the electrode part 4 is provided at a necessary portion thereof. It is formed by the method of forming. As the electrode part 4, an aluminum electrode or the like is used, and as the insulating part 3, silica, BPSG (Bolon Phosphorus Silicate Glass), PSG (Phosphorus Silicate Glass), silicon nitride, polyimide, or the like is used.
[0023]
Next, as shown in FIG. 2, only the surface of the insulating portion 3 on the semiconductor substrate 1 is brought into contact with the surface treatment sheet 5 (a flat plate or sheet-shaped article (B)) and heated. Heating is performed by the heater 6. In FIG. 2, the heater 6 is provided only at the lower part of the semiconductor substrate 1, but the heater 6 can also be provided at the upper part of the surface treatment sheet 5. As the heater 6, a hot plate, bonding with a heat roll, or the like is used. As a result, a part (a small amount) of the surface treatment sheet 5 is transferred to the surface layer portion on the insulating portion 3, and the properties of the insulating portion 3 change.
[0024]
As the surface treatment sheet 5, for example, a fluorine-containing resin is preferably used. Examples of such a sheet include a sheet made of a general-purpose fluorine resin such as polytetrafluoroethylene, poly (chlorotrifluoroethylene), and polyvinylidene fluoride, but other sheets may be used. Moreover, as the sheet 5 for surface treatment, an adhesive sheet 5 ′ in which a fluorine-based adhesive layer is provided on a sheet base material can be used. The sheet base material may be either a sheet shape or a tape shape. Examples of the sheet substrate include plastic films used for general adhesive sheets such as polyethylene, polypropylene, polyethylene terephthalate, and acetylcellulose. For the adhesive layer, for example, various adhesive materials such as an acrylic polymer containing fluorine atoms are used. When the adhesive sheet 5 ′ is used as the surface treatment sheet 5, the adhesive layer of the adhesive sheet 5 ′ is brought into contact with the contact surface side with the substrate.
[0025]
In the metal electrode pattern forming method of the present invention, the semiconductor substrate 1 is subjected to the treatment, and the surface treatment sheet 5 is separated from the semiconductor substrate 1. Next, a metal film is provided on the surfaces of the insulating portion 3 and the electrode portion 4 formed on the semiconductor substrate 1. The said metal film is a deposit part of the adhesive sheet A for metal film peeling removal. The metal film 9 serving as an adherent portion is a film having good solder wettability, and is specifically formed using gold, copper, silver, platinum, iron, tin, nickel, nickel-vanadium alloy, or the like. . Of these, gold (Au) is preferably used.
[0026]
As shown in FIG. 3, the metal film is preferably a three-layer structure in which metal films 7, 8, and 9 are sequentially formed. The first-layer metal film 7 is a film for forming a good bond with the electrode portion 4, and specifically, titanium, vanadium, chromium, cobalt, zirconium, aluminum, tantalum, tungsten, platinum, and these metals. Thin films such as nitrides and alloys containing these metals as main components are used. Among these, a titanium thin film is preferable. The second-layer metal film 8 is a film for adjusting the stress applied to the interface between the metal film 7 and the insulating portion 3. Specifically, nickel, copper, palladium, and an alloy containing these metals as main components are used. A thin film such as is used. Among these, a nickel thin film is preferable. Due to the internal stress of the metal film 8 of the second layer, the adhesiveness at the interface between the metal film 7 and the insulating portion 3 is lowered, and the metal sheet is more easily peeled and removed by the adhesive sheet A. And as a 3rd layer, the metal film 9 with favorable solder wettability used as the adhesion part of the adhesive sheet A is provided.
[0027]
Next, as shown in FIG. 4, an adhesive layer of an adhesive sheet A is attached to the metal film 9 provided on the surfaces of the insulating part 3 and the electrode part 4 formed on the semiconductor substrate 1, and then the adhesive sheet A Tear off. At the time of peeling and removing, the surface of the insulating portion 3 has good peelability at the interface with the metal film 7 by the surface treatment. On the other hand, the interface between the electrode part 4 and the metal film 7 has good adhesiveness, and therefore is not peeled off by the adhesive sheet A. By this operation, the metal films 7, 8, 9 on the surface of the insulating portion 3 are selectively peeled and removed, and a desired metal electrode pattern is formed on the electrode portion 4 on the semiconductor substrate 1 as shown in FIG.
[0028]
By such a metal electrode pattern forming method of the present invention, a metal electrode pattern having good wettability with bumps is reliably formed on the electrode portion 4 on the semiconductor substrate 1 as shown in FIG. Bumps can be easily formed on the metal electrode thus patterned, and the manufacturing process of the semiconductor device can be performed easily and at low cost.
[0029]
The adhesive sheet A is obtained by forming an adhesive layer b on a sheet base material a. The adhesive sheet A may be either a sheet shape or a tape shape.
[0030]
Examples of the sheet substrate a include plastic films used for general adhesive sheets such as polyethylene, polypropylene, polyethylene terephthalate, and acetylcellulose. As the adhesive forming the adhesive layer, a base polymer applied to a general pressure-sensitive adhesive is used. As the base polymer, any of various known polymers such as acrylic polymers and rubber materials can be used, but it is particularly preferable to use acrylic polymers. A cross-linking agent and various additives can be appropriately blended in the adhesive layer.
[0031]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[0032]
Reference example 1
Acrylic polymer A consisting of a copolymer of 2-ethylhexyl acrylate / methyl acrylate / acrylic acid = 30/70/10 (weight ratio) (weight average molecular weight 2.80 million, weight average molecular weight (Mw) ÷ number average molecular weight (Mn ) = 22) 27 wt% toluene solution 100 g, dipentaerythritol hexaacrylate (manufactured by Nippon Gosei Kagaku; trade name: UV3000B) and polyisocyanate compound (manufactured by Nippon Polyurethane Industry; trade name: Coronate L) 0.8 g The applied adhesive composition (toluene solution) was applied onto a film substrate made of a polyester film having a thickness of 50 μm, and dried in a drying oven at 130 ° C. for 3 minutes each to form an adhesive layer having a thickness of 35 μm. An adhesive sheet was formed.
[0033]
Example 1
A semiconductor substrate 1 having a convex insulating portion 3 and a concave electrode portion 4 as shown in FIG. The convex insulating part 3 is a polyimide film, and the concave electrode part 4 is an aluminum thin film. Next, as shown in FIG. 2, a PTFE (polytetrafluoroethylene) plate having a thickness of 1 mm is brought into contact only with the convex insulating portion 3, and sandwiched between a lower part of the semiconductor substrate 1 and an upper part of the PTFE with a hot plate, Pressure bonding was performed for 30 seconds at 150 ° C. and 10 kg / cm ² . Thereafter, the PTFE plate was removed.
[0034]
Subsequently, as shown in FIG. 3, after the metal films 7, 8, and 9 are provided on the semiconductor substrate 1, the adhesive sheet prepared in Reference Example 1 is pasted on the metal film while following the roll at 50 ° C. Wearing. Thereafter, the mixture was kept at this temperature for 1 minute and cooled to room temperature. When the adhesive sheet was peeled off, only the metal films 7, 8 and 9 on the insulating film 3 were peeled off together with the adhesive sheet, and a metal electrode pattern for bump connection was formed on the electrode portion 4.
[0035]
Comparative Example 1
In Example 1, the same operation as in Example 1 was performed except that the surface treatment relating to the PTFE plate was not performed. The metal film on the insulating part 3 was peeled and removed only partially, and a metal electrode pattern was not obtained.
[0036]
Reference example 2
Polymer A consisting of a copolymer of 2-ethylhexyl acrylate / pentafluoroethyl acrylate / acrylic acid = 50/47/3 (weight ratio) (weight average molecular weight 300,000, weight average molecular weight (Mw) / number average molecular weight ( Mn) = 8) and Nippon Polyurethane Industry Co., Ltd .; Trade name: Coronate L) An adhesive composition (ethyl acetate solution) blended with 3.2 g was applied onto a film substrate made of a polyester film having a thickness of 100 μm, Each of them was dried at 130 ° C. for 3 minutes in a drying oven to form an adhesive layer having a thickness of 5 μm to produce an adhesive sheet for surface treatment.
[0037]
Example 2
A semiconductor substrate 1 having a convex insulating portion 3 and a concave electrode portion 4 as shown in FIG. The convex insulating part 3 is a polyimide film, and the concave electrode part 4 is an aluminum thin film. Next, as shown in FIG. 2, the pressure-sensitive adhesive layer of the surface treatment adhesive sheet was brought into contact only with the convex insulating portion 3, and was stuck along a roll at 140 ° C.
[0038]
Subsequently, as shown in FIG. 3, after providing the metal films 7, 8 and 9 on the semiconductor substrate 1, the adhesive sheet prepared in Reference Example 1 was placed on the metal film along the roll at 50 ° C. Pasted. Thereafter, the mixture was kept at this temperature for 1 minute and cooled to room temperature. When the adhesive sheet was peeled off, only the metal films 7, 8 and 9 on the insulating film 3 were peeled off together with the adhesive sheet, and a metal electrode pattern for bump connection was formed on the electrode portion 4.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a semiconductor substrate having a convex insulating portion and a concave electrode portion.
FIG. 2 is a cross-sectional view of a method of performing a surface treatment only on a convex insulating portion. FIG. 3 is a cross-sectional view in which a metal film is provided on the surfaces of the convex insulating portion and the concave electrode portion.
4 is a step of attaching a metal film peeling and removing adhesive sheet to the metal film of FIG. 3;
FIG. 5 is a metal electrode pattern formed in a recessed electrode portion on a semiconductor substrate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 3 Insulation part 4 Electrode part 5 Surface treatment sheet 7, 8, 9 Metal film A Adhesive sheet

Claims (1)

A flat or sheet-like article (B) made of a surface member containing a fluorine-containing resin or a fluorine-adhesive substance only on the convex insulating part on the substrate (A) on which the convex insulating part and the concave electrode part are formed. ) In a state where the surface portion is in contact with each other, a part of the surface member containing the fluorine-containing resin or the fluorine adhesive substance is transferred to the convex insulating portion on the substrate (A), and the convex portion Forming a metal film on the convex insulating film and the concave electrode part after applying a surface treatment to weaken the adhesion of the convex insulating part to the metal film formed on the surface of the partial insulating part and the concave electrode part; The adhesive film is attached to the entire surface of the outermost layer portion of the formed metal film, and then the adhesive film is peeled off to selectively remove the metal film on the surface of the convex insulating portion. The recessed electrode part on the semiconductor substrate A method of forming a metal film pattern only.

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