JP2014181373A - SILICON WAFER ON WHICH Ni AND Ni ALLOY FILM IS FORMED, FORMING METHOD OF Ni AND Ni ALLOY FILM ON Si WAFER, SURFACE ROUGHENING PROCESSING LIQUID TO SURFACE OF Si WAFER IN FORMING Ni AND Ni ALLOY FILM, AND SURFACE ROUGHENING PROCESSING METHOD OF THE SURFACE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming Ni film having excellent adhesion on an Si wafer with electroless Ni plating without coating metal element having a catalytic function and without performing excessive heat treatment.SOLUTION: There is provided a method of forming a Ni thin film 2 having a thickness of 0.05 to 0.5 μm on an Si wafer 1 and forming a thick film 3 of Ni or Ni alloy having a thickness of 3 to 7 μm on the thin film, in which SiOthat exists on the Si wafer is removed in advance by hydrofluoric acid aqueous solution or buffered hydrofluoric acid, then the wafer is immersed into aqueous solution containing strong alkali, ammonium fluoride and Cu to perform roughening processing by hydrophilic treatment and etching. In forming the Ni thin film 2, the wafer is immersed into aqueous solution containing Ni salt, complexing agent, ammonium fluoride and pH buffering agent, and Ni ion in the aqueous solution and Si are substituted. The thick film 3 of Ni or Ni alloy is formed by using electroless Ni plating liquid. Heat treatment is performed to the films in the atmospheric air at 150 to 200°C for 15 to 60 minutes.

Description

The present invention relates to a technique for directly forming an Ni or alloy thick film by electroless plating after forming a thin Ni film with good adhesion on a Si wafer on which a semiconductor device is formed.
In particular, a Ni plating film is formed not only on the device side of the Si substrate having a device structure such as IC or LSI, but also on the surface on the Si base substrate (back surface) side. A plated structure in which one or both of the plating layers are laminated is bumped onto another board substrate with a solder ball or a gold ball on the plated structure, thereby providing a device structure having various functions on the board substrate. The present invention relates to a Ni plating technology that can be used to manufacture integrated circuits or system circuits that are integrated into a single circuit composed of a plurality of elements for new specific applications such as MEMS elements and ASIC (application specific integrated circuit). .

  Also, by thinning the surface of the Si wafer substrate (back surface) side of the Si wafer on which the semiconductor device is formed by back wrapping or back grinding, and further forming a Ni plating film thereon The present invention relates to a Ni plating technique that can be used as a heat sink structure for efficiently radiating heat generated when a semiconductor device is driven.

  Conventionally, when a Ni film is formed on a Si wafer (substrate), a method of forming a Ni film by covering the Si with a metal element having a catalytic function and then performing electroless Ni plating has been used. However, sufficient adhesion of the Ni plating film was not obtained. As a method for increasing the adhesion of the Ni plating film, there are the following prior arts.

(1) A method for obtaining adhesion by performing Pt deposition on Si from an aqueous solution containing fluoride ions and performing heat treatment twice before and after electroless plating as a catalyst treatment (non-patent document 1 below) ).
(2) A method of performing a heat treatment after forming a Ni film on Si by electroless Ni plating (Patent Document 1 below).
(3) Immerse in a dilute HF-containing metal salt solution, form Ag nanoparticles on Si by electroless displacement deposition, and then form nanopores by metal-assisted HF etching dipped in a simple HF solution, and finally A method of forming a metal thin film by electroless autocatalytic plating starting from Ag nanoparticles remaining at the bottom of the nanopore (Non-patent Document 2 below).

  However, in the methods (1) and (3), when a catalytic metal remains on Si and the Si wafer is used as a semiconductor device, there is a concern about an adverse effect due to diffusion into Si or the like. In the method (2), the heat treatment temperature is as high as about 600 ° C., and there is a concern about adverse effects on the device. Furthermore, the Ag nanoparticles used in the above method (3) are not stable because they have good stability and are easy to handle. Therefore, an electroless Ni-B plating solution must be used, which is not practical.

  In addition, Patent Document 2 discloses a metal comprising a single crystal Si substrate having a volume resistivity of 1 to 100 Ω · cm, and one or more metal plating layers provided on the single crystal Si substrate. The single crystal Si substrate with a plating layer and the metal plating layer in contact with the surface of the single crystal Si substrate are selected from the group consisting of Ag, Co, Cu, Ni, Pd, Fe and Pt formed by a plating method. The single crystal Si substrate with a metal plating layer according to claim 1, which is one or more metals, or an alloy or compound containing one or more of the metals.

  However, as described in paragraph 0015 of this document 2, it is intended to improve the adhesion between the metal plating layer and the Si substrate by adjusting the volume resistivity of the Si substrate, as described in paragraph 0013. Furthermore, since it is premised on the use of a special Si substrate, there is a problem that it is not versatile.

  In addition, in paragraph [0028] of Patent Document 3, “the formation of the NiP film by electroless plating is performed under the conditions of pH 8.0, 70 ° C. × 1.0 min using a plating solution having the following composition. The plating solution has a composition of Ni sulfate hexahydrate 21 g / L, citric acid monohydrate 21 g / L, ammonium fluoride 37 g / L, phosphinic acid 26.4 g / L, and aqueous ammonia. The pH is adjusted to 8.0 by addition. "

In addition, paragraph [0029] of Patent Document 3 states that “The NiB film is formed by electroless plating using a plating solution having the following composition, pH 7.5, 70 ° C. × 1.0 min. The plating solution was composed of Ni sulfate sulfate 21 g / L, citric acid monohydrate 21 g / L, ammonium fluoride 37 g / L, dimethylamine borane (DMAB) 5.0 g / L. And the pH is adjusted to 7.5 by addition of aqueous ammonia ”, and an effective method is disclosed as an electroless plating method.
However, the process is not consistent with the present invention, and there is room for improvement in the electroless plating method, which does not agree with the problems, configurations, and effects of the present invention.

JP 2004-193337 A JP 2005-293778 A JP 2011-208227 A

S. Karmalkar, V. P. Kumar; J. Electrochem. Soc., 151, C554 (2004). S. Yae, K. Sakabe, N. Fukumura, S. Sakamoto, H. Matsuda; J. Electrochem. Soc., 158, D573 (2011)

  The present invention is to solve the above-mentioned problems, and without covering with a metal element having a catalytic function, without performing a harsh heat treatment, the electroless Ni plating on the Si wafer can provide an adhesive property. An object is to provide a method for forming a good Ni film.

The present invention provides the following inventions.
1) Provide a Ni thin film with a thickness of 0.05 μm or more and 0.5 μm or less formed on a Si wafer, a Ni thick film or a Ni alloy thick film with a thickness of 3 μm or more and 7 μm or less formed on the thin film. A Si wafer on which a Ni film structure is formed.
2) The Si wafer on which the Ni film structure according to 1) is formed, wherein the Ni alloy film is a Ni—P alloy film or a Ni—B alloy film.
3) The Si wafer on which the Ni film structure according to the above 1) or 2) is formed, wherein the arithmetic average roughness Ra of the interface between the Ni thin film and the Si wafer is 1.5 nm or more.
4) The Si alloy thick film according to any one of claims 1 to 3, wherein the Ni alloy thick film has a portion adjacent to the Ni thin film made of columnar crystals, and the average thickness of the columnar crystals is 100 to 1200 nm. Wafer.
5) A Si wafer on which the Ni film structure described in any one of 1 to 4 above is formed, wherein the adhesion strength between the Ni film structure and the Si wafer is compliant with JIS H8504. An Si wafer characterized by having an adhesion strength compatible with the “tape test method among the test methods”.

The present invention also provides the following inventions.
6) A method of forming a Ni thin film with a thickness of 0.05 μm or more and 0.5 μm or less on a Si wafer, and a Ni or Ni alloy thick film with a thickness of 3 μm or more and 7 μm or less on the thin film. SiO ₂ present on the Si wafer is removed from the wafer by hydrofluoric acid aqueous solution or buffered hydrofluoric acid, and then a roughening process is performed by hydrophilization and etching, and a Ni thin film is formed on the surface of the Si wafer after the roughening process, A method for forming a Ni film structure on a Si wafer, further comprising forming a thick Ni film or Ni alloy film thereon.
7) A Ni thin film is formed on the Si wafer by a substitution reaction in which Ni ions and Si in the aqueous solution are substituted by immersion in an aqueous solution containing Ni salt, complexing agent, ammonium fluoride, and pH buffering agent. The method for forming Ni and Ni alloy films on the Si wafer as described in 6) above, wherein an Ni alloy thick film is formed using an electrolytic plating solution.
8) The method for forming Ni and Ni alloy films on the Si wafer as described in 7) above, wherein the Ni alloy thick film is a Ni—P alloy or Ni—B alloy thick film.
9) After forming the Ni thin film and the Ni alloy film, heat treatment is performed at 150 ° C. to 200 ° C. for 15 minutes to 60 minutes in the air, according to any one of 6) to 8) above. A method for forming Ni and Ni alloy films on a Si wafer.

The present invention also provides the following inventions.
10) A surface roughening solution for the surface of a Si wafer for Ni plating, wherein potassium hydroxide is 30% to 55%, ammonium fluoride is 0.5 mol / L to 2 mol / L, and Cu is 1 mg / liter. A surface roughening solution for the surface of a Si wafer, comprising an aqueous solution containing L or more.
11) By using the surface roughening treatment liquid described in 10) above, hydrophilization and etching of a Si wafer with a strong alkali aqueous solution at a temperature of 25 ° C. or more and 70 ° C. or less and a treatment time of 0.5 to 10 minutes, A surface roughening treatment method for a surface of a Si wafer, characterized by performing a roughening treatment on a Si surface.

  In the present invention, after a Si wafer is wet-etched, a Ni thin film is formed by electroless displacement deposition, followed by autocatalytic electroless Ni plating to form a Ni thick film. Furthermore, the heat treatment is performed after the Ni thick film is formed to provide a technique for ensuring the adhesion of the Ni film, and a severe heat treatment is performed without coating a metal element having a catalytic function as in the prior art. In addition, it has an excellent effect that it is possible to provide a method of forming a Ni film having good adhesion by electroless Ni plating on a Si wafer.

It is a schematic explanatory drawing of Ni thin film and Ni thick film which were formed on Si wafer. It is a figure which shows the cross-section of Ni thin film and Ni-P thick film which were formed on Si wafer.

  The Si wafer (Si substrate) on which the Ni or Ni alloy film of the present invention was formed was formed on the Ni thin film having a thickness of 0.05 μm or more and 0.5 μm or less formed on the Si wafer and the thin film. One of the major features is that a thick Ni film or Ni alloy thick film having a thickness of 3 μm or more and 7 μm or less is provided. FIG. 1 shows a schematic explanatory diagram of a Ni thin film and a Ni thick film formed on a Si wafer.

  The Ni alloy film may be a Ni-P alloy film or a Ni-B alloy film, but may be another Ni alloy film. Although there is no restriction | limiting in particular about P content of the said Ni-P alloy film and a Ni-B alloy film, Usually, it uses as an addition amount with 4-10 wt% of P content and 1-3 wt% of B content in many cases. .

  Arithmetic average roughness Ra (evaluated by “method for measuring surface roughness of fine ceramic thin film by atomic force microscope” based on JIS R1683 2007) based on JIS R1683 2007) is desirably 1.5 nm or more. . Since the interface between the Ni thin film and the Si wafer is in contact and transferred to each other, both interfaces have the same surface roughness. Thereby, the bondability between the Ni thin film and the Si wafer can be improved. However, the surface roughness is not limited.

It is desirable that the adhesion strength between the Si wafer and the Ni film structure has a strength conforming to “tape test method of plating adhesion test method” based on JIS H8504, and this strength is preferably higher. .
In addition, the Ni alloy thick film formed on the Ni thin film has a columnar crystal adjacent to the Ni thin film, and the average thickness of the columnar crystal is usually 100 to 1200 nm.
FIG. 2 shows a cross-sectional structure of the Ni thin film and the Ni—P film formed on the Si wafer.

Next, a Ni thin film having a thickness of 0.05 μm or more and 0.5 μm or less is formed on the Si wafer, and a Ni or Ni alloy thick film having a thickness of 3 μm or more and 7 μm or less is formed on the thin film in advance. SiO ₂ present on the Si wafer is removed from the Si wafer with a hydrofluoric acid aqueous solution or buffered hydrofluoric acid, followed by a hydrophilic treatment and a roughening treatment by etching, and a Ni thin film is formed on the surface of the Si wafer after the roughening treatment. Further, a thick film of Ni film or Ni alloy film is formed thereon, which is one of the major features of the present invention.

  For the surface roughening treatment liquid on the Si wafer surface, an aqueous solution containing 30% to 55% potassium hydroxide, 0.5 mol / L to 2 mol / L ammonium fluoride, and 1 mg / L or more Cu is used. Is preferred. Using this surface roughening treatment liquid, the Si surface is roughened by hydrophilization and etching of the Si wafer with a strong alkaline aqueous solution at a temperature of 25 ° C. to 70 ° C. and a treatment time of 0.5 to 10 minutes. I do.

This surface roughening treatment step on the surface of the Si wafer is a step of roughening by hydrophilization and etching. First, it is immersed in an aqueous solution containing strong alkali, ammonium fluoride, and Cu. The Si wafer from which the SiO ₂ film has been removed by this process exhibits water repellency. However, since it cannot be “plated” as it is, it is hydrophilicized with a strong alkaline aqueous solution.
At this time, Si etching occurs simultaneously. In addition, when ammonium fluoride and Cu are added, there is a roughening effect on the Si surface during etching, so that the adhesion with the Ni thin film formed in a later step is improved.

  Under the above conditions, if the potassium hydroxide concentration is less than 30%, uniform etching is difficult, and the uniformity of plating and film adhesion in the subsequent process become insufficient, and the ammonium fluoride concentration is 0.5 mol / L or less. However, if the Cu concentration is less than 1 mg / L, the roughening tends to be insufficient and the adhesiveness tends to be poor. If the treatment time is short, the roughening is insufficient. There is a tendency for adhesion to be inferior. Therefore, the range of the above conditions is a preferable condition.

Next, the Ni thin film is formed on the Si wafer. Substitution is performed by immersing in an aqueous solution containing a Ni salt, a complexing agent, ammonium fluoride, and a pH buffer to replace Si in the aqueous solution with Ni ions. It is desirable to carry out by reaction.
The Ni salt acts as a Ni supply source, the complexing agent acts as an aqueous solution stabilizer, and the ammonium fluoride has the effect of promoting Ni precipitation by the dissolving action of Si and improving the adhesion by the roughening action. The pH buffering agent reduces the pH fluctuation in the vicinity of the Si wafer during Ni thin film deposition, brings about a stable reaction and is effective in controlling the deposition rate.

Examples of Ni salts, complexing agents, ammonium fluoride, pH buffering agents, treatment conditions, etc. are as follows.
Nickel sulfate hexahydrate: 0.1-0.2 mol / L
Citric acid monohydrate: 0.05 to 0.15 mol / L
Ammonium fluoride: 0.7-2 mol / L
Boric acid: 5 to 15 g / L
pH: 9 ± 0.3 (adjust ammonia water)
Processing conditions: temperature 60-80 ° C, time 3-10 minutes)

In the above, if the Ni salt concentration is low, the precipitation reaction is slow and takes time, which is economically disadvantageous. If it is too high, the cost of the aqueous solution increases, which is also economically disadvantageous.
Further, the complexing agent concentration needs to maintain a constant ratio with the Ni salt concentration, and the Ni salt / complexing agent concentration ratio is preferably about 1.5 to 2 in terms of mol concentration. If the ratio is low (the complexing agent concentration is high), the uniformity of the Ni thin film decreases, and if the ratio is high (the complexing agent concentration is low), the stability of the aqueous solution decreases. .

If the ammonium fluoride concentration is low, the surface of the Si wafer is not sufficiently roughened, resulting in poor adhesion, and if it is high, the uniformity of the Ni thin film tends to decrease. In addition, when the boric acid concentration is low, the pH is not stable and the state of the Ni thin film is not stable. When the boric acid concentration is high, the deposition rate is lowered and the uniformity of the Ni thin film is lowered.
Aqueous ammonia used for pH adjustment also works as a complexing agent for Ni salt. The above range is desirable because the adhesiveness tends to decrease if the pH is too high or too low.
Furthermore, if the treatment time is short, a uniform Ni thin film cannot be obtained, and if the treatment time is long, the Ni film becomes too thick and the adhesion decreases, so the above range is preferable.

  After the formation of the Ni thin film, a Ni alloy thick film is further formed using an electroless plating solution. This Ni alloy thick film can be a Ni-P alloy or Ni-B alloy thick film. The thick film of Ni or Ni alloy can be formed using a commercially available electroless plating solution. For example, plating can be performed using “electroless Ni—P plating solution, KG-537” available from JX Metals Corporation.

After forming the Ni thin film and the Ni alloy film, heat treatment can be performed in the air at 150 ° C. or more and 200 ° C. or less for 15 minutes or more and 60 minutes or less. If the processing temperature is low, sufficient adhesion cannot be obtained, and if it is high, the Si wafer surface tends to be brittle. Further, if the treatment time is short, sufficient adhesion cannot be obtained, so it is desirable that the above range.
In the present invention, a Ni film structure composed of a Ni thin film and a Ni alloy thick film is formed on a Si wafer, and the bonding strength at the interface can be improved by the heat treatment.

  Next, examples of the present invention will be described. In addition, a present Example is an example to the last, and is not restrict | limited to this example. That is, all the aspects or modifications other than the Example included in the scope of the technical idea of the present invention are included.

Using a non-doped Si wafer (Si substrate), the following processes (1) to (5) were sequentially performed to form a Ni thin film and a Ni alloy thick film on the Si wafer (Si substrate).
(1) SiO ₂ removal (2) Hydrophilization and roughening by etching (3) Ni thin film formation (4) Ni alloy thick film formation (5) Heat treatment

The conditions of (1) to (3) and (5) are shown in Tables 1 to 3 and Table 5, respectively.
The conditions for removing SiO _{2 in} Table 1 show two conditions: the case where the hydrofluoric acid concentration is adjusted (No. 1-01) and the case where ammonium fluoride is further added (No. 1-02).

The conditions for roughening by hydrophilization and etching in Table 2 show the case where the KOH concentration, ammonium fluoride concentration, and Cu concentration are adjusted, and the processing temperature (° C.) and processing time (minutes) are adjusted. No. 2-01 to No. 2 Among the implementation conditions of No. 2-13, no. 2-01 to No. 2 Up to 2-08 is a condition within the scope of the present invention. No. 2-09 to No. The conditions up to 2-13 are conditions outside the present invention.
That is, no. In No. 2-09, the concentration of KOH was too low. In No. 2-10, the ammonium fluoride concentration is 0, which is outside the conditions of the present invention. In No. 2-11, the Cu concentration was 0. 2-12 and No. 2-12. In 2-13, the processing temperature and time are outside the conditions of the present invention.

  Table 3 shows specific examples of conditions for forming the Ni thin film. Specific examples (No. 3-01 to No. 3) of conditions for performing a substitution reaction in which Ni ions and Si in an aqueous solution are substituted by immersing in an aqueous solution containing a Ni salt, a complexing agent, ammonium fluoride, and a pH buffer. -02), and adjusted nickel sulfate hexahydrate concentration, citric acid monohydrate concentration, ammonium fluoride concentration, boric acid, pH adjustment (ammonia water), and 70 ° C. treatment time (minutes). An example is shown.

  Table 4 shows the heat treatment conditions. In this case, the treatment temperature (° C.) and the treatment time (minute) are adjusted. 4-01 and No. 4-2 are conditions within the scope of the present invention. 4-3 to No.4. 4-5 shows conditions outside the present invention.

  The Ni alloy thick film formation of (4) is performed under the conditions of a liquid temperature of 85 ° C., a pH of 4.5, and a plating time of 20 minutes using “electroless Ni-P plating solution, KG-537” available from JX Metals Corporation. went.

Next, the conditions for removing SiO ₂ , the conditions for hydrophilization and roughening by etching, the conditions for forming the Ni thin film, and the heat treatment conditions shown in Table 1 to Table 4 are selected as appropriate, and the appearance (uniformity), adhesion, The thickness of the Ni thin film (μm), the thickness of the Ni alloy thick film (μm), the average thickness of the columnar crystals in the adjacent portion of the Ni alloy thick film and the Ni thin film (nm), the interface between the Ni thin film and the Si wafer Table 5 shows the results of examining the arithmetic average roughness Ra (nm). As for the appearance, the uniformity and the surface smoothness were judged as good (◯), slightly bad (Δ), and poor (×).

  The adhesion was evaluated by the “tape test method” in the “plating adhesion test method” based on JIS H8504. Specifically, an adhesive tape (adhesive strength of about 8N per 25 mm width, nominal width 12 to 19 mm) specified in JIS Z1522 is applied to the surface of the Ni film of each sample and pressed strongly so as not to generate bubbles. And it is the method of holding the edge part of an adhesive tape, pulling an adhesive tape strongly perpendicularly | vertically with respect to the Ni film | membrane surface, and peeling off instantaneously.

  In this way, the area of the peeled Ni film was measured, and if the peeled Ni film area was 5% or less of the total area of the Ni film attached to the adhesive tape, the adhesiveness was good (O). Those exceeding 5% were defined as poor adhesion (x).

The thickness of the Ni thin film, the Ni alloy thick film, and the average thickness of the columnar crystals adjacent to the Ni thin film were measured by SEM observation of the cross section.
Arithmetic mean roughness Ra of the interface between the Ni thin film and the Si wafer was measured by measuring the surface of the Si wafer by forming a Ni thin film and a Ni alloy thick film on the Si wafer and then dissolving them in an aqueous nitric acid solution. Here, the arithmetic average roughness Ra was evaluated by a “method for measuring the surface roughness of a fine ceramic thin film using an atomic force microscope” in accordance with JIS R1683 2007.

  As shown in Table 5, roughening conditions by hydrophilization and etching, Ni thin film formation conditions, heat treatment conditions, Ni thin film thickness, Ni alloy thick film thickness, arithmetic average roughness at the interface between Ni thin film and Si wafer Under the conditions (Examples 1 to 8) included in the present invention, Ra was the result that the appearance uniformity, surface smoothness, and adhesion were all good (◯).

On the other hand, under the conditions deviating from the present invention (Comparative Example 1 to Comparative Example 8), the uniformity of the appearance and the surface smoothness may be poor, and the adhesiveness was both poor (x).
That is, for Comparative Examples 1 to 5, the roughening conditions by hydrophilization and etching deviate from the present invention, and for Comparative Examples 6 to 8, the heat treatment conditions deviate from the present invention, and the Ni thin film Since the thickness and the thickness of the Ni alloy thick film did not conform to the present invention, the uniformity of the appearance and the surface smoothness were sometimes poor, and the adhesion was both poor (x).

Further, the arithmetic average roughness Ra of the interface between the Ni thin film and the Si wafer was not within the scope of the present invention in any of the comparative examples.
Under the conditions shown in Tables 1 to 4 above, combinations of those under the conditions of the present invention all gave good results, and combinations of those outside the conditions of the present invention were poor.

  After wet etching the Si wafer, an Ni thin film is formed by electroless displacement deposition, and then an Ni thick film is formed by performing an electroless electroless Ni plating. Furthermore, the present invention provides a technique for performing heat treatment after forming the Ni thick film to ensure the adhesion of the Ni film. There is provided a method for forming a Ni film having good adhesion by electroless Ni plating on a Si wafer without covering a metal element having a catalytic function as in the prior art and without performing a severe heat treatment. In addition to the device side of a Si substrate having a device structure such as an IC or LSI, device structures having various functions are loaded on the Si substrate, and MEMS elements or ASICs (application specific integrated circuits) can be obtained. ) And the like can be used to manufacture an integrated circuit or a system circuit in which circuits composed of a plurality of elements for a specific application are combined into one.

1: Si wafer 2: Ni thin film 3: Ni thick film or Ni alloy thick film

Claims (11)

  A Ni thin film having a thickness of 0.05 μm or more and 0.5 μm or less formed on a Si wafer, and a Ni thick film or a Ni alloy thick film having a thickness of 3 μm or more and 7 μm or less formed on the thin film; A Si wafer on which a characteristic Ni film structure is formed.   In the Si wafer on which the Ni film structure according to claim 1 is formed, when the film formed on the Ni thin film is a Ni alloy thick film, the Ni alloy thick film is a Ni-P alloy film or a Ni-B film. 2. The Si wafer formed with the Ni film structure according to claim 1, wherein the Si wafer is an alloy film.   The Si wafer on which the Ni film structure according to claim 1 or 2 is formed, wherein an arithmetic average roughness Ra of an interface between the Ni thin film and the Si wafer is 1.5 nm or more.   4. The Ni film structure according to claim 1, wherein the Ni alloy thick film has a columnar crystal adjacent to the Ni thin film, and an average thickness of the columnar crystal is 100 to 1200 nm. Si wafer on which a body is formed.   5. An Si wafer on which the Ni film structure according to claim 1 is formed, wherein the adhesion strength between the Ni film structure and the Si wafer conforms to JIS H8504. A Si wafer on which a Ni film structure is formed, having adhesion strength compatible with “tape test method among test methods”. A method of forming a Ni thin film having a thickness of 0.05 μm or more and 0.5 μm or less on a Si wafer, and a Ni or Ni alloy thick film having a thickness of 3 μm or more and 7 μm or less on the thin film, The SiO ₂ present on the Si wafer is removed with an aqueous hydrofluoric acid solution or buffered hydrofluoric acid, and then a roughening process is performed by hydrophilization and etching, and a Ni thin film is further formed on the surface of the Si wafer after the roughening process. A method for forming a Ni film structure on a Si wafer, comprising forming a Ni thick film or a Ni alloy thick film thereon   A Ni thin film is formed on the Si wafer by a substitution reaction in which Ni ions and Si in the aqueous solution are substituted by immersing in an aqueous solution containing Ni salt, complexing agent, ammonium fluoride, and pH buffering agent. 7. The method for forming a Ni film structure on a Si wafer according to claim 6, wherein a Ni alloy thick film is formed using a liquid.   The method for forming a Ni film structure on a Si wafer according to claim 7, wherein the Ni alloy thick film is a Ni-P alloy or Ni-B alloy thick film.   After forming the Ni thin film and the Ni alloy film, heat treatment is performed at 150 ° C. to 200 ° C. for 15 minutes to 60 minutes in the air, on the Si wafer according to claim 6. Of forming a Ni film structure on the substrate.   A surface roughening solution for the surface of a Si wafer for Ni plating, wherein potassium hydroxide is 30% to 55%, ammonium fluoride is 0.5 mol / L to 2 mol / L, and Cu is 1 mg / L or more. A surface roughening treatment liquid for the surface of a Si wafer, comprising an aqueous solution containing the same.   Using the surface roughening treatment liquid according to claim 10, the Si surface is hydrophilized and etched with a strong alkaline aqueous solution of the Si wafer at a temperature of 25 ° C. to 70 ° C. and a treatment time of 0.5 to 10 minutes. The surface roughening method of the surface of Si wafer characterized by performing the roughening process of this.