JP2003100758A - Method for forming pattern and pressure sensitive adhesive sheet for metal film patterning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for patterning a metal film that facilitates peeling and the cost of which is low. SOLUTION: On the surface of a base where an aluminum thin film 3 as a first material and a polyimide film 4 as a second material different from the first material are exposed, a metal film 5 is formed and when patterning of the metal film 5 is carried out in such a way that the metal film 5 located on the aluminum thin film 3 is left and the metal film 5 located on the polyimide film 4 is peeled, a pressure sensitive adhesive sheet 8 is used to peel the metal film 5 and the surface is irradiated with reactive ions or radicals for refining as a process for preventing the metal film 5 from being peeled from the aluminum thin film 3 and for facilitating peeling on the surface of the polyimide film 4, then the desired metal film 5 is formed and the pressure sensitive adhesive sheet 8 is peeled off after it is pasted thereto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method, and more particularly to a technique for patterning a metal film in a desired region (for example, bump forming region) on a substrate.

[0002]

2. Description of the Related Art A pattern forming method using photolithography is well known as a method for forming a metal electrode of a semiconductor device, which allows an electrode to be formed in a desired region. Further, as another method, when forming an under bump metal (hereinafter referred to as a UBM film) for a Cu bump in a flip chip process, a UBM film is formed by an adhesive sheet by utilizing a difference in adhesion between a protective film and a base electrode. There is also proposed a method of selectively removing the ash with a sheet (Japanese Patent Laid-Open No. 10-64912).

[0003]

However, in the above-mentioned pattern forming method using photolithography,
There is a problem that equipment and process cost in the photolithography and etching process are very high. Further, regarding the method of selectively removing the UBM film with the adhesive sheet, it is difficult to apply it to a highly reducing metal (a metal having a strong adhesive force), and there is a demand for more stable peeling. is there.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to enable easy patterning of a metal film at low cost.

[0005]

According to the pattern forming method of the first aspect, the metal film is formed on the surface of the underlayer where the first material and the second material are exposed. At this time,
The adhesive force between the first material and the metal film and the adhesive force between the second material and the metal film are so strong that the metal film cannot be separated from the second material. On the other hand, by using a pressure-sensitive adhesive sheet for peeling the metal film and adding a step of facilitating peeling on the surface of the second material without causing peeling of the metal film on the first material, The adhesive force between the material of No. 2 and the metal film is reduced to a peelable range. Then, the metal film located on the first material is left and the metal film located on the second material is peeled off to pattern the metal film.

[0006] As a result, it is possible to prevent the equipment and process cost in the photolithography and etching steps from becoming very high as in the conventional method using photolithography and to prevent the conventional UBM film from being selectively used as an adhesive sheet. The peeling can be performed more stably as compared with the removing method. In this way, the metal film can be patterned easily and at low cost.

Here, the step of facilitating the peeling of the second material on the surface is a surface modification step in which the first material and the second material are exposed as described in claim 4. And
After the step, a desired metal film is formed, an adhesive sheet is attached, and then the sheet is peeled off. In particular, as described in claim 5, as the surface modification step, reactive ion or Radiation is irradiated, and more specifically, the reactive or radical to be irradiated may be generated by supplying a mixed gas of CF-based gas and oxygen into the chamber as described in claim 6. .

Further, the step of facilitating the peeling of the second material on the surface is, as described in claim 10, a metal film which is difficult to oxidize when the first material and the second material are exposed. Is a step of forming a film, and after the step, a desired metal film is formed, an adhesive sheet is attached, and then the sheet is peeled off. Particularly, it is difficult to oxidize as described in claim 11. The metal film is preferably a gold or platinum film having a thickness of 2 to 50 nm.

Further, the step of facilitating the peeling of the second material on the surface may be carried out from the state in which the first material and the second material are exposed, onto the second material, as described in claim 14. It is a step of forming a silicon oxide film. After the step, a desired metal film is formed, an adhesive sheet is attached, and then the sheet may be peeled off.

According to the invention described in claims 7, 12 and 15, in addition to the function and effect of the invention described in claim 1, the stress applied to the interface between the metal film and the underlying layer is adjusted on the metal film. The stress adjusting film is formed to reduce the adhesion between the second material and the metal film to a peelable range. Then, the metal film on the first material is left and the metal film on the second material is peeled off. Therefore, peeling becomes easier.

Particularly, as described in claims 8 and 13, the laminated film of the metal film and the stress adjusting film preferably has a total stress of 30 N / m or more. Further, as described in claim 16, the laminated film of the metal film and the stress adjusting film preferably has a total stress of 60 N / m or more.

Further, regarding the pressure-sensitive adhesive sheet, as described in claim 17, the acid value of the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet is 10 or more (particularly, as described in claim 18, 20 or more, 500 or more.
Hereinafter, more preferably, as described in claim 19, 5
If it is 0 or more and 300 or less), the releasability of the metal film from the second material is improved, and the pattern can be reliably formed.

A second aspect of the present invention is to realize an adhesive having this acid value.
As described in 0, the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet contains 2% by weight or more of a monomer unit having a carboxyl group (particularly,
A range of 2% by weight or more and 50% by weight or less as described in claim 21, more preferably 2% by weight or more.
It is preferable that the base polymer is included in a range of from wt% to 30 wt%).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show the manufacturing process of the semiconductor device in this embodiment. In this embodiment, a semiconductor device generally called a power element is embodied, and as shown in FIG. 2C, a metal (more specifically, an aluminum thin film) is used as the first material 3, and a second material is used. An insulator (specifically, a polyimide film) is used as the material 4.

First, as shown in FIG. 1A, a silicon substrate 1 which is a semiconductor substrate is prepared. Then, a transistor element (not shown) is formed on the silicon substrate 1 in a wafer state by using a general semiconductor device manufacturing technique.
Further, the insulating film 2 is formed on the silicon substrate 1 by the CVD method or the like. This insulating film 2 is formed of BPSG (Boron-P
hosphorus Silicate Glass) film and PSG (Phospho
rus Silicate Glass) film or the like. Further, an opening 2a is formed in the insulating film 2 by a photolithography method in order to obtain conduction inside the silicon substrate (bulk portion). Subsequently, an aluminum thin film 3 is formed on the insulating film 2 including the opening 2a by using a sputtering method or a vapor deposition method. After that, the unnecessary portion of the aluminum thin film 3 is removed by the photolithography method. The aluminum thin film 3 thus left serves as an electrode portion of an element such as a transistor.

In this way, the electrode portion (aluminum thin film) 3 and the insulating film 2 are exposed on the silicon substrate 1. Further, heat treatment is performed so that good conduction can be obtained between the silicon substrate 1 and the aluminum thin film 3. A metal layer called a barrier metal may be formed between the silicon substrate 1 and the electrode portion (aluminum thin film) 3 for the purpose of preventing alloy spikes due to the interaction between the substrate 1 and the aluminum thin film 3.

Thereafter, as shown in FIG. 1B, a protective film (insulating film) 4 is formed by coating or the like. This protective film 4
Is made of a polyimide film or the like. Further, an opening 4a is formed in this protective film 4 by a photolithography method in order to obtain conduction with the aluminum thin film 3.

Subsequently, the process proceeds to the surface modification step in which the first material 3 and the second material 4 different from the first material 3 are exposed. More specifically, as shown in FIG. 1C, a protective film (insulating film) 4 and an aluminum film are formed on a silicon substrate 1 in a wafer state by further irradiating reactive ions or radicals using a mixed gas of CF4 and O2. The outermost surface of the thin film 3 is fluorinated (F). The gas is CHF3 instead of CF4.
Other CF-based gas may also be used. FIG. 3 shows a schematic configuration of an apparatus for performing this surface modification treatment.

In FIG. 3, a CF-based gas (C
(F4 etc.) and oxygen mixed gas is supplied and a high frequency voltage is applied by the high frequency power source 10 to form plasma,
Reactive ions or radicals are generated from this plasma. Then, the silicon wafer 12 on the electrode 11 is irradiated with the reactive ions or radicals, and the surface of the silicon wafer 12 is modified.

As a result, as shown in FIG. 1C, the outermost surfaces of the aluminum thin film 3 and the protective film 4 are fluorinated (F).
To be done. By this surface modification, the adhesive force between the protective film 4 and the metal film (member indicated by reference numeral 5 in FIG. 2A) described later is reduced to a peelable range in the subsequent steps, and the metal film 5 is removed. The protective film 4 can be easily peeled off.

Returning to the description of the pattern forming process, subsequently, as shown in FIG. 2A, metal films 5, 6 and 7 are sequentially formed on the silicon substrate 1 in a wafer state. An enlarged view of the metal films 5, 6 and 7 is shown in FIG.

In FIG. 4, the metal film 5 which is the first layer
Is a film for forming a good bond with the aluminum thin film 3, and specifically, a titanium thin film is used. Instead of the titanium thin film, another metal film that achieves the above-mentioned object,
For example, vanadium, chromium, cobalt, zirconium,
Aluminum, tantalum, tungsten, a nitride of these metals, an alloy containing these metals as a main component, or the like may be used. In addition, since an oxide film is usually formed on the aluminum thin film 3, generally, when another metal film is formed on the aluminum thin film 3, the above-mentioned oxide film removing step is required. However, when a titanium thin film is used as the first-layer metal film as in the present embodiment, titanium reduces the above-mentioned oxide film and oxidizes itself to form a good interface. The film removal step may be unnecessary. That is, the titanium thin film 5 in contact with the aluminum thin film 3
Is a metal thin film having a high reducing property.

In FIG. 4, the metal film 6 as the second layer.
Is a film for adjusting the stress applied to the interface between the metal film 5 and the underlying substrate 1 (protective film 4), and specifically, a nickel thin film is used. Instead of the nickel thin film, another metal film that achieves the above-mentioned object, for example, copper, palladium, or an alloy containing these metals as a main component may be used. With this metal film 6, the adhesion between the insulating film 4 and the metal film 5 can be reduced to a peelable range in the subsequent steps, and the metal film 5 can be easily peeled from the insulating film 4. . Here, the metal film 5 and
The laminated film of the metal film (stress adjustment film) 6 has a total stress (Total S
tress), that is, the product of the film thickness and the internal stress (total stress = film thickness × internal stress) is 30 N / m or more.

In FIG. 4, the metal film 7 as the third layer is
A film with good solder wettability, specifically gold (Au)
Is used. Instead of gold (Au), another metal film that achieves the above-mentioned object, such as copper, silver, platinum, iron, tin,
You may use Cu-Sn alloy etc. Further, the metal film 7 can be omitted when the metal film 6 is made of a metal having good solder wettability such as nickel. However, it is desirable to use the metal film 7 because the solder wettability deteriorates when the nickel surface is oxidized.

The above-mentioned three metal films 5, 6 and 7 are formed by a sputtering apparatus as shown in FIG. 5, which is capable of continuous film formation in vacuum without exposure to the atmosphere. That is, the vacuum chamber 15 is provided with a wafer inlet 16 at one end and a wafer outlet 17 at the other end, and the chamber 15 has a first metal film target 18 and a second metal film. Target 19 and third metal film target 20 are arranged. Then, the films 5, 6 and 7 can be sequentially formed while the wafer is transferred in the vacuum chamber 15. A control panel 21 is arranged near the vacuum chamber 15. By using the apparatus of FIG. 5, it is possible to form a film without forming an oxide film between the metal films. Therefore, the adhesiveness between the metal films is increased, and the stacked films 5, 6,
7 behaves like one metal film.

Even if the apparatus having the shape shown in FIG. 5 is used, it can be realized by a different sputtering apparatus or vapor deposition apparatus as long as it can be transported without breaking the vacuum.

After the metal films 5, 6, and 7 are formed, the wafer-shaped silicon substrate 1 is taken out from the sputtering apparatus shown in FIG. 5, and the wafer-shaped silicon substrate 1 is fixed with a vacuum chuck or the like. ), An adhesive sheet (adhesive film) 8 is attached onto the metal film 7. The adhesive sheet 8 comprises a sheet base material (film material) 8a and an adhesive agent (adhesive layer) 8b.

Regarding this pressure-sensitive adhesive sheet 8, the following are specifically used in this embodiment. Acrylic polymer A (weight average molecular weight 700,000, weight average molecular weight (Mw) / number average) composed of a copolymer of 2-ethylhexyl acrylate / acrylic acid = 90/10 (weight ratio) as a composition in adhesive 8b Molecular weight (Mn) = 18, acid value 7
32 g of dipentaerythritol hexaacrylate (manufactured by Nippon Synthetic Chemical Industry; trade name: UV1700B) and 0.8 g of polyisocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd .: trade name: Coronate L) were mixed with 100 g of a 27% ethyl acetate solution of 0). An adhesive composition (ethyl acetate solution) is used. This adhesive composition has a thickness of 50 μm.
m onto the base film 8a made of a polyester film, and dried in a drying oven at 130 ° C. for 3 minutes,
An adhesive 8b having a thickness of 40 μm was formed. In this way, the pressure-sensitive adhesive sheet 8 was produced. The acid value of this pressure-sensitive adhesive composition was measured and found to be "30".

Here, the functions (composition, etc.) required for the adhesive sheet 8 will be mentioned. The adhesive 8b of the adhesive sheet 8 is
It contains a lot of carboxyl groups. Specifically, the acid value of the pressure sensitive adhesive 8b is "10" or more. In order to have excellent adhesion to the metal film 5, the acid value is preferably "20" or more, more preferably "50" or more. Thereby, the metal film 5
The peelability from the insulating film 4 is improved, and the pattern is reliably formed. On the other hand, if the acid value of the pressure-sensitive adhesive 8b is too high, a part of the pressure-sensitive adhesive 8b of the pressure-sensitive adhesive sheet 8 may remain on the metal film 5, so the acid value of the pressure-sensitive adhesive 8b is "500" or less,
Further, it is preferably set to "300" or less.

The pressure sensitive adhesive 8b of the pressure sensitive adhesive tape 8 preferably contains a base polymer containing 2% by weight or more of a monomer unit having a carboxyl group. It is more preferable that the monomer unit having a carboxyl group is contained in an amount of 5% by weight or more. By containing the base polymer in which the monomer unit having a carboxyl group is adjusted to the above ratio, the pressure-sensitive adhesive 8b having the acid value can be realized. When the proportion of the monomer unit having a carboxyl group increases, the acid value of the pressure-sensitive adhesive 8b also increases. Therefore, the proportion of the monomer unit having a carboxyl group is 50% by weight or less, and further 30% by weight or less. preferable.

As described above, the pressure-sensitive adhesive sheet 8 is obtained by forming the pressure-sensitive adhesive 8b having the specific acid value on the base film 8a. The adhesive sheet 8 may be in the form of a sheet or a roll.

As the base film 8a, polyethylene, polypropylene, polyethylene terephthalate,
Examples include plastic films used for general pressure-sensitive adhesive sheets such as acetyl cellulose. Also, FIG.
In (b), the thickness t1 of the sheet base material 8a is not particularly limited, but is about 10 to 100 μm. On the other hand, the thickness t2 of the adhesive 8b formed on the surface of the base film 8a
Is about 10 to 180 μm.

As the adhesive 8b, a base polymer applied to general pressure sensitivity is used. As the base polymer, various known polymers such as acrylic polymers and rubber materials can be used, but it is particularly preferable to use acrylic polymers.

The acrylic polymer is a (meth) acrylic acid alkyl ester (note that (meth) acrylic acid ester means acrylic acid ester and / or methacrylic acid ester, and hereinafter (meth) has the same meaning}.
Is the main monomer. The alkyl group has 1 to 1 carbon atoms
It is about 2. Specific examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate,
Examples thereof include ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, and these can be used alone or in combination.

As the monomer having a carboxyl group used for imparting an acid value to the resulting acrylic polymer, (meth) acrylic acid is usually used, but maleic acid, fumaric acid, itaconic acid, etc. may also be used. it can.

The monomer constituting the acrylic polymer has a crosslinkability having a functional group such as a hydroxyl group such as glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and N-methylol (meth) acrylamide. A monomer can also be used together. Furthermore, monomers such as (meth) acrylonitrile, vinyl acetate and styrene may be used in combination to the extent that the adhesive properties of the (meth) acrylic acid ester copolymer are not impaired.

The weight average molecular weight of the acrylic polymer is 20.
The dispersity (weight average molecular weight / number average molecular weight) is about 5 to 15 million. Adhesive 8 of adhesive sheet 8
b can also be a pressure-sensitive adhesive composition in which, in addition to various base polymers, tackifiers such as rosin-based resins, terpene-based resins, and petroleum-based resins, and various cross-linking agents are appropriately mixed. Further, as the adhesive 8b, a filler, an antioxidant, an ultraviolet absorber, a coloring agent, or the like can be appropriately used if necessary. Also,
The form of the adhesive 8b may be either solvent type or emulsion type. Furthermore, the pressure-sensitive adhesive 8b can also be made into a heat-curable or photo-curable pressure-sensitive adhesive by using a thermosetting or photo-curable polymerizable compound in combination.

The compounding ratio of the tackifier, the cross-linking agent, and the other compound is not particularly limited, but it is used so that the acid value of the pressure-sensitive adhesive composition is 10 or more. The acid value of the adhesive and the compounding ingredients in the adhesive are measured according to JIS
According to the standard K0070, the sample was dissolved in a mixed solution of benzene: ethyl alcohol = 2: 1 (weight ratio) and titrated by neutralization with 0.1 mol / liter potassium hydroxide-ethyl alcohol solution using phenolphthalein as an indicator. , Calculated.

Returning to the explanation of the pattern forming step, the adhesive sheet 8 is attached to the metal film 7 on the substrate shown in FIG. 2 (b) by a roll at 20 ° C., and then the wafer-shaped substrate 1 is formed as shown in FIG. When it is gently stripped from the top, unnecessary portions of the metal films 5, 6, 7 are removed from the semiconductor device as shown in FIG. 2 (c). That is, as shown in FIG. 7, the metal films 5, 6, 7 on the protective film (insulating film) 4 are removed (peeled) from the wafer-shaped substrate 1, but the underlying pattern (aluminum thin film) is used.
The metal films 5, 6, 7 on 3 remain on the wafer-shaped substrate 1.
In this way, the pressure-sensitive adhesive sheet 8 is peeled off, and only the metal films 5, 6, 7 on the insulating film 4 are peeled and removed together with the pressure-sensitive adhesive sheet 8, and the bump metal pattern 5, 5 is formed on the electrode portion 3.
6, 7 are formed.

The peeling rate of the metal films 5, 6, 7 on the insulating film 4 was about 90% of the whole, and the remaining part could be removed cleanly by washing the substrate 1 with pure water. .

In FIG. 6, the adhesive sheet 8 is cut in the same shape as the wafer-shaped silicon substrate 1, but this is for facilitating the transportation and temporary storage of the wafer-shaped substrate 1. The shape of the adhesive sheet 8 does not need to be the same shape as the wafer-shaped substrate 1 when it is not required to be transported or temporarily stored, and it is larger than the wafer-shaped substrate 1.
Moreover, it does not matter whether it is circular or rectangular. In particular, when it is not necessary to temporarily store, it is preferable that the size is larger than that of the wafer-shaped substrate 1 because it can be easily peeled off.

The principle of peeling is as follows.
Titanium, which is the first metal film 5 of this embodiment, forms a good bond not only with aluminum but also with the protective film 4. Therefore, it is usually difficult to peel off between the protective film 4 and the titanium thin film 5. However, the adhesion of the insulating film 4 and the titanium thin film 5 can be reduced by making the surface F. Further, as shown in FIG. 4, when a nickel thin film 6 is formed on the titanium thin film 5, a large film stress (tensile stress) is generated inside the nickel thin film 6 due to the difference in rigidity and thermal expansion coefficient during film formation.
Occurs. At this time, the thickness of the titanium thin film 5 is set to 500 n.
When the thickness is m or less and the film is formed without forming the oxide film between the titanium thin film 5 and the nickel thin film 6 as described above, the influence of stress extends to the interface between the titanium thin film 5 and the protective film 4, and The adhesive force between the protective film 4 and the protective film 4 is reduced to a peelable range.

Thus, the adhesiveness (adhesion) of the base material
And the internal stress of the metal electrode thin film (5, 6, 7), the desired electrode material can be stably peeled off only on the protective film 4. The titanium thin film 5 is a metal that is difficult to peel from an oxide or the like, and the stress of another film is used as a method of peeling such a metal film from a silicon oxide or the like.

FIG. 8 shows the results of the tape peeling test. Since the titanium thin film, which is often used as an electrode material, has high adhesion to the polyimide (protective film 4), no peeling occurred even when the peeling test with the adhesive tape was performed. However, a nickel thin film (6) is laminated to give F by surface modification and a total stress of 30 N / m is applied to the polyimide.
The i / polyimide structure enables peeling with an adhesive tape. That is, in addition to the effect of surface modification, tensile stress is present in the sputtered Ni film, and this stress causes high tensile stress at the interface between the titanium thin film and the underlying layer.
Peeling at the i / polyimide interface is possible.

9 and 10 show the results of XPS outermost surface analysis. FIG. 9 shows the analysis result before the surface modification, and FIG. 10 shows the analysis result after the surface modification. This FIG.
From the results, it can be seen that the surface of the polyimide shifted the peak of C to the high energy side (left side in FIGS. 9 and 10), and thus the polyimide surface was converted to F. That is, in FIG. 9, C
Alternatively, it has a CH peak and has CF3 and CF2 peaks in FIG. As described above, the F surface of the polyimide increases the peelability of the titanium thin film.

FIG. 11 shows the results of measuring the peeling rate of the adhesive tape when the total stress was changed when the titanium thin film (5) was used. That is, the results of measuring the adhesive force between the titanium thin film 5 and the protective film (polyimide) 4 and the adhesive force between the titanium thin film 5 and the aluminum thin film 3 are shown. The surface modification here uses surface modification with CF4 and O2 gas. From FIG. 11, it can be seen that peeling can occur at 30 N / m on the polyimide film. On the other hand, it can be seen that peeling does not occur even at 100 N / m on the surface of the aluminum thin film without pretreatment (surface modification). Therefore, for example, if a total stress of 100 N / m is used, the titanium thin film can be selectively left on the surface of the aluminum thin film without pretreatment by performing peeling using the adhesive tape after film formation.

Thus, the adhesive force between the metal film 5 and the protective film 4 is smaller than the adhesive force between the metal film 5 and the aluminum thin film 3,
When the total stress is 30 N / m or more and the metal film 5 is peeled off using the adhesive sheet 8, the metal film 5 is peeled off from the protective film 4 but remains on the aluminum thin film 3.

Here, the total stress of the laminated film of the film 5 and the film 6 is
It can be controlled mainly by the film thickness of the nickel thin film 6. The higher the total stress value, the more advantageous it is for peeling on the protective film 4. However, when the stress is 1500 N / m or more, the wafer warps, and in some cases (such as when the wafer is thin), the wafer may be damaged.
It is preferable to control in the range of N / m or more and 1500 N / m or less. In this way, by suppressing the total stress to 1500 N / m or less, it is possible to prevent problems such as warpage and damage of the wafer after film formation.

Here, the usefulness of this embodiment will be described with reference to a comparative example. As a comparative example, the acrylic polymer A used as the base polymer of the pressure-sensitive adhesive 8b is an acrylic polymer A (weight average molecular weight of 100) made of a copolymer of 2-ethylhexyl acrylate / acrylic acid = 99/1 (weight ratio). The pressure-sensitive adhesive composition was prepared in the same manner as in the above embodiment, except that the weight average molecular weight (Mw) / number average molecular weight (Mn) = 22, acid value 6) was changed to prepare a pressure-sensitive adhesive sheet. The acid value of this pressure-sensitive adhesive composition was "3". Then, using this adhesive sheet, peeling evaluation of the metal film was performed in the same manner as in the present embodiment. As a result, the metal film on the insulating film 4 could hardly be removed. In this way, the usefulness of this embodiment is confirmed.

As described above, this embodiment has the following features. (A) As a pattern forming method, as shown in FIG. 1B, an aluminum thin film (metal) 3 as a first material and a polyimide film (insulator) 4 as a second material different from the aluminum film 3 are exposed. A metal film 5 is formed on the surface of the base as shown in FIG. 2A, and thereafter, as shown in FIG. 2C, the metal film 5 located on the aluminum thin film 3 is left and the polyimide is formed. When the metal film 5 located on the film 4 is peeled and the metal film 5 is patterned, as shown in FIG. 2B, the adhesive sheet 8 is used for peeling the metal film 5, and
As shown in (c), in the step of facilitating the peeling of the polyimide film 4 on the surface of the polyimide film 4 without causing the peeling of the metal film 5 with the aluminum thin film 3, the aluminum thin film 3 and the polyimide film 4 are exposed in a reactive state. Surface modification is performed by irradiating with ions or radicals, and then a desired metal film 5 is formed,
After sticking the adhesive sheet 8, the sheet 8 was peeled off.

Therefore, when the metal film 5 is formed on the surface of the underlayer, the adhesion between the first material 3 and the metal film 5 and the adhesion between the second material 4 and the metal film 5 Strong, second
In contrast to the state in which the metal film 5 cannot be peeled off from the material 4 of FIG.
Is added to the second material 4, and the second material 4 and the metal film 5 can be easily separated on the surface of the second material 4 without causing the metal film 5 to separate from the first material 3. The adhesive force between and is reduced to a peelable range. Then, the metal film 5 located on the first material 3 is left and the metal film 5 located on the second material 4 is peeled off to remove the metal film 5.
Are patterned. As a result, it is possible to prevent the equipment and process cost in the photolithography and etching steps from becoming very high as in the conventional method using photolithography, and to selectively remove the conventional UBM film with an adhesive sheet. The peeling can be performed more stably as compared with In this way, the metal film can be patterned easily and at low cost. (B) Regarding the adhesive sheet, the adhesive 8b of the adhesive sheet 8
The acid value of 10 or more, particularly 20 or more and 500 or less, more preferably 50 or more and 300 or less, the metal film 5
The peelability from the second material 4 is improved, and the pattern can be reliably formed.

In order to realize the adhesive having this acid value, the adhesive 8b of the adhesive sheet 8 contains 2% by weight or more, particularly 2% by weight or more of the monomer unit having a carboxyl group.
50% by weight or less, more preferably 2% by weight or more,
The base polymer may be contained in an amount of 30% by weight or less. (Second Embodiment) Next, the second embodiment will be described with reference to the first embodiment.
The difference from the above embodiment will be mainly described.

12 and 13 show the manufacturing process of the diode in this embodiment. In the present embodiment, as shown in FIG. 13, the first material 51 is an impurity-doped semiconductor and the second material 2 is an insulator. That is, the first
Although the metal film 3 forming the electrode portion (or the wiring portion) is an aluminum thin film and the metal film 5 is formed on the metal film 3 in the above embodiment, the silicon substrate 50, which is a semiconductor substrate, is used in this embodiment. The metal film 60 is arranged on the impurity diffusion region 51 in FIG. 1, and the metal film 5 is formed thereon.

A detailed description will be given below. First, FIG.
As shown in (a), the N-type impurity diffusion region 5 is formed on the P-type silicon substrate 50 by using a general semiconductor device manufacturing technique.
1 is formed. As a result, a diode having a PN junction is formed. Then, the same insulating film 2 as that shown in the first embodiment is formed, and the opening 52 is formed by the photolithography method. Further, the natural oxide film formed in the opening 52 is removed by hydrofluoric acid or the like.

Thereafter, with the N-type impurity diffusion region 51 and the insulating film 2 exposed, as shown in FIG. 12B, the metal films 60, 5, 6, 7 are sequentially formed without forming the aluminum thin film. To film. The metal film 60 that is the first layer is a metal film that is difficult to oxidize, and specifically, gold (Au) is used. Instead of gold (Au), another metal film that achieves the above-mentioned object, such as silver or platinum, may be used. Metal film 60
Has a thickness of 2 to 50 nm. By forming this metal film 60, peeling of the metal film 5 does not occur in the N-type impurity diffusion region 51, and peeling on the surface of the insulating film 2 becomes easy. The metal film 6 is a stress adjusting film as in the first embodiment, and the laminated film of the metal film 5 and the stress adjusting film 6 has a total stress of 30 N / m or more.

Subsequently, the electrode 5 is formed on the back surface of the silicon substrate 50.
3 is formed. Further, as shown in FIG. 12C, the adhesive sheet 8 is attached. Then, the adhesive sheet 8 is peeled off from the wafer-shaped substrate 50 by the same method as that shown in FIGS. Then, as shown in FIG. 13A, the metal films 60, 5, 6, 7 can be left only in the opening 52 of the insulating film 2.

Then, as shown in FIG. 13B, soldering is performed on the entire surfaces of the metal films 60, 5, 6, 7.
The solder 54 is mounted. Here, the evaluation according to the present embodiment will be described. As described in the first embodiment, the acrylic polymer A used as the base polymer of the pressure-sensitive adhesive 8b was prepared by adding 2-ethylhexyl acrylate /
Acrylic polymer A consisting of a copolymer of acrylic acid = 99/1 (weight ratio) (weight average molecular weight 1,000,000, weight average molecular weight (Mw) / number average molecular weight (Mn) = 22, acid value 6) 40 g, Rosin-based tackifying resin (Arakawa Chemical Co., Ltd .; trade name: Pine Crystal KR85; acid value 170)
A pressure-sensitive adhesive composition was prepared in the same manner as in the first embodiment, except that the pressure-sensitive adhesive composition was mixed with 50 g and 0.8 g of a polyisocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd .: trade name: Coronate L), An adhesive sheet was produced.
The acid value of this pressure-sensitive adhesive composition was measured and found to be "85". Further, using this pressure-sensitive adhesive sheet, peeling evaluation of the metal film was performed in the same manner as in the first embodiment. As a result, the metal film on the insulating film 2 is 100% peeled and removed, and the electrode portion 51 is removed.
A metal electrode pattern was formed on top. In this way, the usefulness of this embodiment was confirmed.

Further description will be added with reference to FIG. FIG. 14 shows the measurement results of the adhesive force between the titanium thin film 5 and the insulating film 2 by the scratch test. The horizontal axis of FIG. 14 is Au.
The film thickness (film thickness of the metal film 60) is taken, and the peeling strength is taken on the vertical axis. The horizontal axis shows the adhesion between the titanium thin film 5 and the insulating film (SiO2) 2 when Au film thickness = 0. The results of measuring the adhesive force and the adhesive force when the Au film 60 is inserted between the titanium thin film 5 and the insulating film 2 are shown. On the silicon oxide film (Au film thickness = 0), the peel strength was 100 mN or more, but the Au film thickness could be 50 mN or less at 2 nm. Therefore, by inserting the Au film 60 and peeling it off using the adhesive sheet 8, the titanium thin film 5 can be easily peeled off from the insulating film 2, and on the other underlying N-type silicon layer 51. Can be left. (Third Embodiment) Next, the third embodiment will be described with reference to the second embodiment.
The difference from the above embodiment will be mainly described.

FIG. 15 shows not the portion shown in FIG. 13B but the portion of the circuit around which a plurality of elements are formed on the silicon substrate 1. In the present embodiment, the first material 71 is nitride and the second material 70 is metal.

First, as shown in FIG. 15A, an aluminum electrode (aluminum thin film) 70 is formed on the silicon substrate 1,
A silicon nitride (Si3N4) film 71, which is an insulating film, is formed in a predetermined region on the film. Furthermore, from the state where the silicon nitride film 71 and the aluminum electrode 70 are exposed,
As shown in FIG. 15B, the TEOS-SiO2 film 72 is formed.
And a TEOS film 72 located on the aluminum electrode 70 is opened by a photoetching method. After that, FIG.
As shown in (c), metal films 5, 6, and 7 are formed. The metal film 6 is a stress adjusting film as in the first embodiment, and the laminated film of the metal film 5 and the stress adjusting film 6 has a total stress of 60 N / m.
That is all.

Further, an adhesive sheet 8 (see FIG. 12C) is attached on the metal film 7. Then, the adhesive sheet 8 is attached to the wafer-shaped substrate 1 by a method similar to that shown in FIGS.
Peel more. Then, as shown in FIG.
The metal film 5 is formed only on the opening of the TEOS-SiO2 film 72.
You can leave 6,7.

In this way, the aluminum electrode (second material) 7
In order to facilitate the peeling on the surface of 0, the silicon nitride film (first material) 71 and the aluminum electrode 70 are exposed, and then the silicon oxide film 72 is formed on the aluminum electrode 70. After the film 5 is formed and an adhesive sheet is attached, the sheet is peeled off.

In FIG. 16, the titanium thin film 5 and the insulating film (Si
N) 71 and the peelability between the titanium thin film 5 and the insulating film (TEOS-SiO2) 72. The peeling rate between the titanium thin film 5 and the SiN film 71 is 0%,
The peeling rate between the titanium thin film 5 and the TEOS-SiO2 film 72 was 100%. Therefore, TEOS is formed on the SiN film 71.
-By forming the SiO2 film 72, the adhesive sheet 8
The titanium thin film 5 can be easily peeled from the TEOS-SiO2 film 72 by peeling it off using SiN.
It remains on the film 71.

[Brief description of drawings]

FIG. 1 is a diagram showing a pattern forming process according to a first embodiment.

FIG. 2 is a diagram showing a pattern forming process according to the first embodiment.

FIG. 3 is a diagram showing an outline of a surface modification device.

FIG. 4 is an enlarged view after Ti / Ni / Au film formation.

FIG. 5 is a diagram showing an outline of a sputtering apparatus.

FIG. 6 is a perspective view for explaining a peeling step of the adhesive sheet.

FIG. 7 is a cross-sectional view for explaining the peeling step of the adhesive sheet.

FIG. 8 is a diagram showing the results of a tape peeling test with and without surface modification.

FIG. 9 is a diagram showing a result of XPS analysis before surface modification.

FIG. 10 is a diagram showing the results of XPS analysis after surface modification.

FIG. 11 is a diagram showing a result of peeling measurement in a tape test.

FIG. 12 is a diagram showing a pattern forming step in the second embodiment.

FIG. 13 is a diagram showing a pattern forming step in the second embodiment.

FIG. 14 is a diagram showing the results of measuring the adhesive force between a titanium thin film and an insulating film by a scratch test.

FIG. 15 is a view showing a pattern forming step in the third embodiment.

FIG. 16 is a diagram showing a result of peeling measurement in a tape test.

[Explanation of symbols]

1 ... Silicon substrate, 2 ... Insulating film, 3 ... Aluminum thin film, 4 ...
Protective film, 5 ... Titanium thin film, 6 ... Nickel thin film, 7 ... Gold thin film, 8 ... Adhesive sheet, 8a ... Sheet base material, 8b ... Adhesive, 50 ... P-type silicon substrate, 51 ... N-type impurity diffusion region, 60 ... gold thin film, 70 ... aluminum thin film, 71 ... silicon nitride film, 72 ... TEOS-SiO2 film.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Noritake Chikage             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Mikimasa Suzuki             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Hideshi Toyoda             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 4M104 AA01 BB04 BB07 BB08 BB09                       BB13 BB36 DD00 DD06 DD23                       DD61 FF02 GG02 HH09 HH20                 5F033 HH07 HH08 HH11 HH12 HH13                       HH14 HH15 HH16 HH17 HH18                       HH19 HH21 HH22 HH32 JJ01                       JJ07 JJ08 JJ11 JJ12 JJ13                       JJ14 JJ17 JJ18 JJ19 JJ21                       JJ22 JJ32 KK08 MM08 PP15                       PP19 QQ00 QQ09 QQ37 QQ73                       QQ91 QQ98 RR04 RR06 RR14                       RR15 RR22 SS04 SS11 VV07                       WW00 WW02 WW05 XX00 XX12                       XX14

Claims (24)

[Claims] 1. A metal film (5) is formed on a surface of an underlayer on which a first material (3, 51, 71) and a second material (2, 4, 70) different from the first material are exposed, and thereafter. , The first
The metal film (5) located on the material (3, 51, 71) of
And the metal film (5) located on the second material (2, 4, 70) is peeled off to pattern the metal film (5). ) Is used for peeling the second material (2, 4, 70) without peeling the metal film (5) with the first material (3, 51, 71).
A method for forming a pattern, comprising the step of facilitating peeling on the surface of the. 2. The pattern forming method according to claim 1, wherein the first material (3, 51) is a metal or a semiconductor doped with impurities, and the second material (2, 4) is A pattern forming method characterized by being an insulator. 3. The pattern forming method according to claim 1, wherein the first material (71) is a nitride and the second material (70) is a metal. . 4. The pattern forming method according to claim 1, wherein the step of facilitating peeling on the surface of the second material (4) includes the first material (3) and the second material (4). ) Is an exposed surface modification step, and after the step, a desired metal film (5) is formed, an adhesive sheet (8) is attached, and then the sheet (8) is peeled off. A method of forming a pattern, characterized in that 5. The pattern forming method according to claim 4, wherein reactive ions or radicals are irradiated as the surface modifying step. 6. The pattern forming method according to claim 5, wherein the reactive ions or radicals to be irradiated are generated by supplying a mixed gas of CF type gas and oxygen into the chamber (9). A characteristic pattern forming method. 7. The pattern forming method according to claim 4, wherein a stress adjusting film (6) is provided on the metal film (5) for adjusting a stress applied to an interface between the metal film (5) and an underlayer. ) Is formed, after which the adhesive sheet (8) is attached and then the adhesive sheet (8) is peeled off. 8. The pattern forming method according to claim 7, wherein the laminated film of the metal film (5) and the stress adjusting film (6) has a total stress of 30 N / m or more. Method. 9. The pattern forming method according to claim 1, wherein the metal film (5) in contact with the first material (3) is a metal thin film having high reducing property. And a pattern forming method. 10. The pattern forming method according to claim 1, wherein the step of facilitating peeling on the surface of the second material (2) includes the first material (51) and the second material (2). ) Is exposed, a metal film (60) that is difficult to oxidize is formed, and after the step, a desired metal film (5) is formed and an adhesive sheet (8) is attached. , The sheet (8)
A pattern forming method, characterized in that the pattern is peeled off. 11. The pattern forming method according to claim 10, wherein the metal film (60) which is resistant to oxidation has a film thickness of 2 to 50 n.
m is a gold or platinum film. 12. The pattern forming method according to claim 10, wherein a stress adjusting film (6) is provided on the metal film (5) for adjusting a stress applied to an interface between the metal film (5) and an underlayer. ) Is formed, after which the adhesive sheet (8) is attached and then the adhesive sheet (8) is peeled off. 13. The pattern forming method according to claim 12, wherein the laminated film of the metal film (5) and the stress adjusting film (6) has a total stress of 30 N / m or more. Method. 14. The pattern forming method according to claim 1, wherein the step of facilitating peeling on the surface of the second material (70) includes a first material (71) and a second material (70). ) Is exposed, a silicon oxide film (72) is formed on the second material (70), and after the step,
A pattern forming method characterized in that a desired metal film (5) is formed, an adhesive sheet (8) is attached, and then the sheet (8) is peeled off. 15. The pattern forming method according to claim 14, wherein a stress adjusting film (6) is provided on the metal film (5) for adjusting a stress applied to an interface between the metal film (5) and an underlayer. ) Is formed, after which the adhesive sheet (8) is attached and then the adhesive sheet (8) is peeled off. 16. The pattern forming method according to claim 15, wherein the laminated film of the metal film (5) and the stress adjusting film (6) has a total stress of 60 N / m or more. Method. 17. The pattern forming method according to claim 1, wherein the pressure-sensitive adhesive sheet (8) has an acid value of the pressure-sensitive adhesive (8b) of 10 or more. 18. The pattern forming method according to claim 17, wherein the pressure-sensitive adhesive sheet (8) has an acid value of the pressure-sensitive adhesive (8b) of 20 or more and 500 or less. 19. The pattern forming method according to claim 18, wherein the pressure-sensitive adhesive sheet (8) has an acid value of the pressure-sensitive adhesive (8b) of 50 or more and 300 or less. 20. The pattern forming method according to claim 1, wherein the pressure-sensitive adhesive (8b) of the pressure-sensitive adhesive sheet (8) contains a base polymer containing 2% by weight or more of a monomer unit having a carboxyl group. And a pattern forming method. 21. The pattern forming method according to claim 20, wherein the pressure-sensitive adhesive (8b) of the pressure-sensitive adhesive sheet (8) contains a monomer unit having a carboxyl group in a range of 2% by weight or more and 50% by weight or less. A pattern forming method comprising a base polymer. 22. The pattern forming method according to claim 21, wherein the pressure-sensitive adhesive (8b) of the pressure-sensitive adhesive sheet (8) contains a monomer unit having a carboxyl group in a range of 2% by weight or more and 30% by weight or less. A pattern forming method comprising a base polymer. 23. The pressure-sensitive adhesive sheet (8) used in the pattern forming method according to claim 1, wherein the pressure-sensitive adhesive (8b) is used.
An acid value of 10 or more is a pressure-sensitive adhesive sheet for metal film patterning. 24. The pressure-sensitive adhesive sheet for patterning a metal film according to claim 23, wherein the pressure-sensitive adhesive (8b) contains a base polymer containing 2% by weight or more of a monomer unit having a carboxyl group.