JP2015110821A - Forming method of forming nickel layer on surface of aluminium material, forming method of forming nickel layer on surface of aluminum electrode of semiconductor wafer using forming method, and semiconductor wafer substrate obtained using forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method of forming a nickel plating layer on a surface of an aluminum material and so on that enable an electroless nickel plating layer to be stably formed on the surface of the aluminum material.SOLUTION: There is employed a forming method including: forming a nickel strike plating layer on a surface of an aluminum material by using an electroless strike plating method; and forming an electroless nickel plating layer, an electroless nickel-phosphorus alloy plating layer, or an electroless nickel-copper-phosphorus alloy plating layer on the surface of the aluminum material by using an electroless plating method. The present invention can be applied to formation of a nickel layer on a surface of an aluminum electrode of a semiconductor wafer.

Description

  The invention according to the present application relates to a method of forming a nickel layer on the surface of an aluminum material. In particular, the present invention relates to a method of forming a nickel layer on the surface of an aluminum material without using a zincate method. The method according to the present application also relates to a method for forming a nickel layer having high adhesion on the surface of an aluminum electrode of a semiconductor wafer, and a semiconductor wafer substrate having a nickel layer formed on the surface of the aluminum electrode by the forming method.

  Conventionally, there is a wire bonding method as a method for mounting a semiconductor device such as a semiconductor chip on a circuit board such as a printed wiring board. This wire bonding method is a method in which a semiconductor device is mounted on a circuit board and electrically connected to an electrode pad of an aluminum pad or a copper pad arranged on the circuit board by a bonding wire. However, in the mounting method using the wire bonding method, it is necessary to secure a space for routing the bonding wire. Therefore, from the viewpoint of high-speed signal processing, a mounting method by a flip chip method using bumps of a semiconductor chip has been adopted.

  The flip-chip method is a mounting method in which the electrode side of the semiconductor chip is mounted facing the circuit board side, and the electrode of the circuit board and the electrode of the semiconductor chip are connected via a solder layer. Here, most of the material of the electrodes provided on the circuit board is aluminum. Since it is difficult to bond solder directly to the aluminum, a nickel plating film is formed on the aluminum electrode, and the electrode of the semiconductor chip is soldered to the electrode of the circuit board via the nickel plating film. I was going. Here, Patent Document 1 and Patent Document 2 are shown as conventional techniques in which a nickel layer is formed on the aluminum electrode.

  The semiconductor device disclosed in Patent Document 1 is “provided on a semiconductor chip, a first insulating layer that covers the semiconductor chip with at least a portion of a terminal electrode of the semiconductor chip exposed, and the first insulating layer. And a redistribution layer that leads the terminal electrode of the semiconductor chip to a connection position with an external circuit through the second insulating layer, and is joined to the terminal electrode. A semiconductor device in which a plating base layer is provided only in the presence region of the terminal electrode or on the first insulating layer from the presence region, and at least a part of the rewiring layer is a plating layer. It is. The plating underlayer in the semiconductor device of Patent Document 1 is formed from a zinc layer formed by performing a zincate process on a portion in contact with the terminal electrode, and a nickel plating layer formed on the zinc layer by an electroless plating method. Become.

  In Patent Document 1, in the zincate treatment, by immersing an aluminum electrode in a solution containing a zinc cation having a smaller ionization tendency than aluminum, the aluminum in the vicinity of the electrode surface is oxidized and dissolved. By being reduced, a zinc layer is formed on the surface of the electrode. Although the nickel plating layer cannot be directly attached to the aluminum electrode, by performing the zincate treatment, the oxide on the aluminum surface is removed and the zinc layer is formed. A plating layer is firmly formed.

  On the other hand, Patent Document 2 states that “a method of forming an Ni electrode layer by depositing an electroless Ni plating film on the surface of an input / output terminal electrode of an electronic circuit element using an electroless plating method, After etching the surface of the electrode, Ni substitution treatment is performed to form a Ni substitution film on the surface of the input / output terminal electrode, and then a dummy metal plate is formed at least at the beginning of the reaction in an electroless Ni plating bath. “Technology for depositing an electroless Ni plating film on the surface of the input / output terminal electrode in an immersed state”. In Patent Document 2, a Ni-substituted film is formed on the surface of a Cu-containing aluminum pad electrode in a Ni-substituted solution containing Ni ions and glycine without performing the zincate treatment on the electrode surface as in Patent Document 1, and Ni ions An electroless Ni plating film is formed in a state where a dummy metal plate coexists in an electroless Ni plating solution containing glycine and sodium hypophosphite.

JP 2007-157879 A JP 2001-107254 A

  However, in Patent Document 1 as described above, the zincate solution in which zinc ions used for the zincate treatment are dissolved is a strong alkaline solution having a pH of 12 or more. Therefore, there is a problem that the surface of the insulating layer composed of the aluminum pad electrode, the polyimide covering the semiconductor chip, polydimethylsiloxane, or the like is damaged by the zincate solution that is a strong alkaline solution.

  Therefore, as disclosed in Patent Document 2, a method of forming an electroless Ni plating layer on an aluminum electrode without performing a zincate process has been developed. However, in the method of forming the Ni-substituted film on the aluminum electrode according to Patent Document 2, the adhesion between the Ni-substituted film and the aluminum electrode is unstable, and an electroless Ni plating layer having a uniform thickness is formed. It was difficult to do. Therefore, the market demands the development of a technique for forming an electroless Ni plating layer on an aluminum electrode that does not involve zincate treatment, and can stably form the electroless Ni plating layer on the aluminum electrode. It had been.

  In view of the above, the present invention has demanded a method for forming a nickel layer on the surface of an aluminum material that can stably form an electroless Ni plating layer on the surface of the aluminum material without performing a zincate treatment. It was. In particular, it has been desired to provide a method for forming a nickel layer on the surface of an aluminum electrode on a semiconductor wafer and a semiconductor wafer substrate having a nickel layer formed on the surface of the aluminum electrode by the formation method.

  As a result of earnest research, the present inventors have conceived a new method for forming a nickel layer on the surface of an aluminum material without using the zincate method, and have solved the above-mentioned problems.

  That is, in the method for forming a nickel layer on the surface of the aluminum material according to the present invention, a nickel strike plating layer is formed on the surface of the aluminum material using an electroless strike plating method, and then the surface of the aluminum material is coated with no nickel. An electroless nickel plating layer, an electroless nickel-phosphorus alloy plating layer, or an electroless nickel-copper-phosphorus alloy plating layer is formed using an electrolytic plating method.

  The method for forming a nickel layer on the surface of an aluminum electrode on a semiconductor wafer according to the present invention employs the above-described method for forming a nickel layer on the surface of an aluminum material of the present invention, and is formed on the surface of the aluminum electrode. A nickel strike plating layer is formed using an electroless strike plating method, and then an electroless nickel plating layer or an electroless nickel-phosphorus alloy plating layer is formed on the surface of the aluminum electrode using an electroless plating method, or An electroless nickel-copper-phosphorus alloy plating layer is formed.

  A method for producing a semiconductor wafer substrate according to the present invention is a method for producing a semiconductor wafer substrate using the above-described method for forming a nickel layer on the surface of an aluminum electrode on a semiconductor wafer, wherein the insulating layer of the semiconductor wafer is formed. The surface is selectively irradiated with UV (ultraviolet rays) to modify the surface, a catalyst is selectively applied only to the modified portion, and an electroless plating method is selectively applied only to the portion to which the catalyst is applied. An electroless nickel plating layer, an electroless nickel-phosphorus alloy plating layer, or an electroless nickel-copper-phosphorus alloy plating layer is formed.

  The semiconductor wafer substrate according to the present invention is an electroless nickel layer, an electroless nickel-phosphorus alloy layer, or an electroless nickel on the surface of the insulating layer of the semiconductor wafer using the above-described method for manufacturing a semiconductor wafer substrate. -A conductor circuit comprising a copper-phosphorus alloy layer is provided.

  The semiconductor wafer substrate according to the present invention was further formed on the surface of the electroless nickel layer, the electroless nickel-phosphorus alloy layer, or the electroless nickel-copper-phosphorus alloy layer by an electroless plating method. It is preferable to provide an electroless palladium layer.

  The semiconductor wafer substrate preferably further comprises an electroless gold plating layer formed by an electroless plating method on the surface of the electroless palladium layer.

  According to the method for forming a nickel layer on an aluminum material according to the present invention, a nickel strike plating layer is formed on the surface of the aluminum material using a low alkaline electroless strike plating bath, and is formed on the surface of the aluminum material. By using the nickel strike plating layer as a nucleus, an electroless nickel plating layer, an electroless nickel-phosphorus alloy plating layer, or an electroless nickel-copper-phosphorus alloy plating layer can be formed by an electroless plating method. Therefore, it is not necessary to perform a conventional zincate process to form a zinc layer for firmly forming a nickel plating layer on the surface of the aluminum material. Therefore, even when an electroless nickel plating layer or the like is formed on the surface of an aluminum electrode on a semiconductor wafer as a representative example of an aluminum material, the electroless nickel is not formed on the surface of the aluminum electrode without using a strong alkaline zincate solution. A plating layer etc. can be formed firmly. At this time, since the conventional strong alkaline zincate solution is not used, it is possible to avoid the disadvantage that the surface of the insulating layer of the semiconductor wafer is damaged by the strong alkaline zincate solution. Therefore, when a conductor circuit is formed on the surface of the insulating layer, the surface is partially modified by exposure at a UV wavelength of 184.9 nm and 253.7 nm using a glass pattern mask, and the modified portion. Since the surface of the insulating layer is kept smooth, a fine pitch conductor circuit can be formed.

  Further, in the present invention, a nickel strike plating layer is formed on the surface of an aluminum material using an electroless strike plating method, and an electroless nickel plating layer or the like is formed using the nickel strike plating layer as a nucleus. Stable adhesion can be realized between the material and the electroless nickel plating layer and the like, and an electroless nickel plating layer and the like having a uniform thickness can be formed.

It is a schematic process explanatory drawing of the formation method of the electroless nickel plating layer of this invention. It is explanatory drawing of the manufacturing process of the electroless nickel plating layer of this invention. It is a schematic process drawing explaining the manufacturing method of the semiconductor wafer substrate of this invention. It is a schematic block diagram of the semiconductor wafer substrate of this invention.

  Hereinafter, according to the present invention, “a method for forming a nickel layer on the surface of an aluminum material”, “a method for forming a nickel layer on the surface of an aluminum electrode of a semiconductor wafer using the method for forming”, and “a method for forming the same” Preferred embodiments of “a method for producing a semiconductor wafer substrate” and “a semiconductor wafer substrate obtained by using the method for producing a semiconductor wafer substrate” will be described.

<The form of the formation method of the nickel layer on the aluminum material surface which concerns on this invention>
First, a method for forming a nickel layer on the surface of an aluminum material according to the present invention will be described. The method for forming a nickel layer on the surface of an aluminum material according to the present invention is to form a nickel strike plating layer on the surface of the aluminum material using an electroless strike plating method, and then apply an electroless plating method to the surface of the aluminum material. An electroless nickel plating layer, an electroless nickel-phosphorus alloy plating layer, or an electroless nickel-copper-phosphorus alloy plating layer is used. In the present invention, the nickel layer formed on the surface of the aluminum material includes a nickel strike plating layer formed on the surface of the aluminum material, and an electroless nickel plating layer formed on the surface of the aluminum material by an electroless plating method. It consists of an electrolytic nickel-phosphorus alloy plating layer or an electroless nickel-copper-phosphorus alloy plating layer. Therefore, in the present invention, the nickel layer formed on the aluminum material surface is not only a combination of a nickel strike plating layer and an electroless nickel plating layer, but also a nickel strike plating layer, an electroless nickel-phosphorus alloy plating layer, A combination with an electroless nickel alloy plating layer such as an electroless nickel-copper-phosphorus alloy plating layer is also included. Hereinafter, the same shall apply to those having a nickel layer on the surface of the aluminum material.

  In the method for forming a nickel layer on the surface of an aluminum material according to the present invention, aluminum in the vicinity of the surface of the aluminum material is replaced with nickel by an electroless strike plating method, and nickel is deposited on the surface of the aluminum material. A strike plating layer is formed. Thereafter, the aluminum material was immersed in an electroless nickel plating bath, an electroless nickel-phosphorous plating bath, or an electroless nickel-copper-phosphorus plating bath, and formed on the surface of the aluminum material. A nickel plating layer, a nickel-phosphorus alloy plating layer, or a nickel-copper-phosphorus alloy plating layer, which is the main plating, is formed on the surface of the aluminum material by an electroless nickel plating method using the nickel strike plating layer as a nucleus.

  In the present invention, the nickel layer formed on the surface of the aluminum material is deposited on the surface of the aluminum material with the nickel strike plating layer formed by the electroless strike plating method as a nucleus. A layer having excellent adhesion and a uniform thickness can be formed.

<Mode of Forming Nickel Layer on Aluminum Electrode Surface of Semiconductor Wafer According to Present Invention>
Next, a method for forming a nickel layer on the surface of an aluminum electrode on a semiconductor wafer will be described as a typical application form of the method for forming a nickel layer on the surface of the aluminum material of the present invention described above. In the nickel layer forming method according to the present invention, a nickel strike plating layer is formed on the surface of an aluminum electrode of a semiconductor wafer by using an electroless strike plating method, and then the surface of the aluminum electrode is formed by using an electroless plating method. An electroless nickel plating layer, a nickel-phosphorus alloy plating layer, or a nickel-copper-phosphorus alloy plating layer is formed.

  Conventionally, since the zinc substitution method was used instead of the strike plating method, the surface of the aluminum electrode was exposed to a solution containing a large amount of caustic soda. Therefore, conventionally, in the process of processing, the surface of the aluminum electrode is etched by about 0.3 μm to 0.5 μm, and the occurrence of damage to the surface of the aluminum electrode cannot be avoided. On the other hand, in the present invention, since the electroless strike plating method is adopted, the etching amount of the aluminum electrode surface can be suppressed to within 0.2 μm, and the damage to the aluminum electrode surface is reduced as compared with the conventional case. This is advantageous in that it can be suppressed.

  Further, in the method for forming a nickel layer according to the present invention, aluminum in the vicinity of the surface of the aluminum electrode on the semiconductor wafer is replaced with nickel by an electroless strike plating method, and nickel is deposited on the surface of the aluminum electrode. A strike layer is formed. Thereafter, the aluminum electrode was immersed in an electroless nickel plating bath, an electroless nickel-phosphorous plating bath, or an electroless nickel-copper-phosphorous plating bath, and formed on the surface of the aluminum electrode. Using the nickel strike plating layer as the core, the nickel plating layer, which is the main plating, or the alloy plating layer of nickel and phosphorus, or the alloy plating layer of nickel, copper and phosphorus is formed on the surface of the aluminum electrode by electroless nickel plating. .

  In the present invention, the nickel layer formed on the surface of the aluminum electrode is formed by precipitation on the surface of the aluminum electrode with the nickel strike plating layer formed by the electroless strike plating method as a nucleus. It is excellent in adhesion and can achieve a uniform film thickness.

  Further, in the above-described method for forming a nickel strike plating layer by the electroless strike plating method, since a strong alkaline zincate solution is not used as in the prior art, the surface of the insulating layer of the semiconductor wafer is not damaged and a glass mask is formed by UV. Electroless nickel plating layer or electroless nickel-phosphorus alloy on the surface of the aluminum electrode and the circuit shape in which the palladium has penetrated by allowing the palladium catalyst to penetrate only where the insulating layer is pattern-modified using A plating layer or an electroless nickel-copper-phosphorus alloy plating layer can be formed.

  Here, in the formation method of the electroless nickel plating layer according to the present invention, the nickel strike plating layer formed on the surface of the aluminum electrode by the electroless strike plating method has a plating thickness of 0.2 μm to 0.5 μm. It is preferable. When the electroless strike plating method is applied under the condition that the nickel strike plating layer has a plating thickness exceeding 0.5 μm, the surface of the aluminum electrode is significantly damaged, and the electroless nickel plating is performed thereafter. This is because it is difficult to uniformly form the electroless nickel plating layer by the method. On the other hand, when the plating thickness of the nickel strike plating layer is less than 0.1 μm, it becomes difficult for the nickel strike plating layer to sufficiently function as a nucleus when the nickel plating layer is deposited, and stable adhesion is achieved. This is because it becomes difficult to form a nickel plating layer provided with.

  Further, in the method for forming a nickel layer according to the present invention, an electroless nickel plating layer formed on the surface of an aluminum electrode by an electroless nickel plating method, an electroless nickel-phosphorus alloy plating layer, or an electroless nickel- The copper-phosphorus alloy plating layer preferably has a plating thickness of 2 μm to 15 μm. This is because, when the plating thickness of the electroless nickel plating layer or the like exceeds 15 μm, it is impossible to secure a sufficient space with the adjacent wiring for use as a wiring on the semiconductor. On the other hand, when the plating thickness of the electroless nickel plating layer or the like is less than 2 μm, sufficient energization cannot be obtained because the plating film resistance is high.

  Below, the process of the formation method of the nickel layer of this invention is divided and demonstrated for every process with reference to FIG.1 and FIG.2. Note that the layer configuration of the semiconductor wafer shown in FIG. 2 schematically shows the concept of the layer configuration. Therefore, FIG. 2 is described so that the layered state of each layer can be grasped, and the thickness of each layer does not reflect the actual thickness of the product.

  A semiconductor wafer that can employ the nickel layer forming method of the present invention is, for example, as shown in FIG. 2A, each region of the semiconductor element on the semiconductor wafer 10 with a base insulating layer 11 interposed therebetween. And an aluminum electrode 12 serving as an input / output terminal electrode. FIG. 2 shows a state in which only one aluminum electrode 12 is formed for easy explanation of the configuration. Actually, a plurality of signal electrodes, ground electrodes, power supply electrodes, and the like are formed for one semiconductor chip. An insulating layer 13 made of an insulating layer constituent material such as polyimide or polydimethylsiloxane is formed on the surface of the base insulating layer 11 on which the aluminum electrode 12 is formed. The insulating layer 13 is provided with an opening 15 for forming the electroless nickel plating layer 18 on the aluminum electrode 12 by selective etching. At this stage, a thin natural oxide film 16 is formed on the surface of the aluminum electrode 12.

<Nickel layer formation process>
Neutral degreasing process:
As step S1, a neutral degreasing process is performed. In the neutral degreasing step, neutral degreasing treatment of the surface of the aluminum electrode 12 is performed using acetone, ethanol, a neutral detergent, or the like. By the neutral degreasing treatment, oil or the like attached to the surface of the aluminum electrode 12 can be removed. After completion of the neutral degreasing process, a water washing process is performed, and the process proceeds to the next acid dipping process.

Acid dipping process:
In the acid dipping step as step S2, acid dipping treatment of the semiconductor wafer 10 provided with the aluminum electrode 12 is performed using an acidic solution such as nitric acid or phosphoric acid. By the acid immersion treatment, the natural oxide film 16 formed on the surface of the aluminum electrode 12 can be removed. FIG. 2B shows a state where the natural oxide film 16 is removed. After completion of the acid soaking process, a water washing process is performed, and the process proceeds to the next reduction process.

Reduction process:
The reduction treatment step as step S3 is a step of performing reduction treatment on the surface of the aluminum electrode 12, and is preferably performed before the electroless strike plating treatment as the next step S4. In the reduction treatment step, by reducing the surface of the aluminum electrode, adhesion between the nickel strike plating layer formed by the electroless strike plating method in the next step and the surface of the aluminum electrode, and precipitation of the nickel strike plating layer Speed can be improved.

  The reducing agent used in the reduction treatment step is not particularly limited. Examples thereof include hydrazine compounds such as sodium hypophosphite, dimethylamine borane (DMAB), hydrazine hydrochloride and hydrazine sulfate.

  Moreover, when the same reducing agent as the reducing agent contained in the electroless strike nickel plating bath or the electroless nickel plating bath used in the subsequent steps is used, the aluminum electrode after the reduction treatment is not washed with water. It is preferable because an electroless strike plating process or an electroless plating process can be performed. Moreover, since there is little possibility of changing the composition of an electroless strike plating bath or an electroless plating bath, it is preferable.

Electroless strike plating process:
The electroless strike plating step as step S4 is a step of forming the nickel strike plating layer 17 on the surface of the aluminum electrode 12 by the electroless strike plating method. FIG. 2C shows a state in which the nickel strike plating layer 17 has been formed. As the electroless strike plating bath used in the electroless strike plating step, a bath generally used for nickel electroless strike plating can be adopted. The electroless strike nickel plating bath includes a nickel salt, a reducing agent, a complexing agent, and a stabilizer.

  As the nickel salt, those generally used for electroless strike plating of nickel can be used. Specific examples of the nickel salt include nickel sulfate, nickel chloride, nickel carbonate, nickel acetate, nickel hypophosphite, nickel sulfamate, and nickel citrate. These may be used alone or in combination of two or more. In the present invention, it is most preferable to use nickel sulfate hexahydrate as the nickel salt. The nickel salt is preferably used in the range of 0.05 mol / L to 0.3 mol / L.

  Examples of the reducing agent include hydrazine compounds such as sodium hypophosphite, dimethylamine borane (DMAB), hydrazine hydrochloride, and hydrazine sulfate, similarly to the reducing agent used in the above-described reduction treatment step. In the present invention, it is most preferable to use dimethylamine borane (DMAB) as the reducing agent. The reducing agent is preferably used in the range of 0.1 g / L to 10 g / L.

  As the complexing agent, those generally used in the electroless strike plating method can be used. Specific examples of the complexing agent include, for example, carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid and oxalic acid, hydroxycarboxylic acids such as lactic acid, glycolic acid, malic acid and citric acid, alanine, valine, Examples include amino acids such as tyrosine, glycine, aspartic acid, histidine and the like. In the present invention, it is preferable to use glycine and succinic acid in combination as the complexing agent. The complexing agent is preferably used in the range of 0.01 mol / L to 0.6 mol / L.

  As the stabilizer, those generally used in the electroless strike plating method can be used. Specific examples of the stabilizer include bismuth, antimony, thiosulfuric acid, molybdenum, lead sulfate and the like. In the present invention, it is preferable to use bismuth as a stabilizer. The stabilizer is preferably used in the range of 0.01 mg / L to 5.0 mg / L.

  In addition to the above, the electroless strike nickel plating bath in the present invention includes, for example, brighteners (sodium thiosulfate, lead, copper, etc.), pH buffer materials (ammonium sulfate, boric acid, ammonium chloride, etc.), pH adjusters ( It may contain components such as sulfuric acid and ammonia). In the present invention, it is preferable that ammonium sulfate and boric acid are contained as the pH buffer material, and sodium thiosulfate is contained as the brightener.

  Moreover, it is preferable that pH of the electroless strike nickel plating bath in this invention is a neutral region of 6.0-8.0. And it is preferable that the temperature of the said electroless strike nickel plating bath is 25 to 50 degreeC.

  In the electroless strike plating step, the nickel strike plating layer 17 having a thickness of 1 μm to 5 μm is deposited on the surface of the aluminum electrode 12 by immersing the semiconductor wafer in the above-described electroless strike nickel plating bath. After completion of the electroless strike plating process, a water washing process is performed, and the process proceeds to the next reduction process.

Reduction process:
The reduction treatment step as step S5 after the end of the electroless strike plating step in step S4 is a step of performing reduction treatment on the surface of the aluminum electrode 12 on which the nickel strike plating layer 17 is formed. As in the case of step S3, the reduction treatment step is preferably performed before the electroless plating treatment as the next step S5. Since the reducing agent used in the reduction process is the same as that in step S3 described above, the description thereof is omitted here. In the reduction treatment step, the surface of the aluminum electrode 12 on which the nickel strike plating layer 17 is formed is reduced, so that in the next electroless plating treatment step, the nickel plating is formed with the nickel strike plating layer 17 as a nucleus. It is possible to improve the adhesion between the layer, the nickel-phosphorus alloy plating layer, or the nickel-copper-phosphorus alloy plating layer 18 and the aluminum electrode 12, and the deposition rate of the nickel plating layer. When the same reducing agent contained in the electroless nickel plating bath used in the next step is used in the reduction treatment step, the aluminum electrode 12 is transferred to the electroless plating treatment step without being washed after the reduction treatment. can do.

Electroless plating process:
In the electroless plating step as step S6, the surface of the aluminum electrode 12 on which the nickel strike plating layer 17 is formed is electrolessly plated by a nickel plating layer, a nickel-phosphorus alloy plating layer, or nickel-copper- In this step, the phosphorus alloy plating layer 18 is formed. FIG. 2D shows a state where an electroless nickel plating layer is formed. As the electroless plating bath used in the electroless plating step, it is possible to employ a nickel, nickel-phosphorous alloy, or nickel-copper-phosphorus alloy that is generally used for electroless plating. That is, the electroless nickel plating bath contains a nickel salt, a reducing agent, a complexing agent, and a stabilizer. The electroless nickel-phosphorus alloy plating bath includes a nickel salt, a hypophosphite, a reducing agent, a complexing agent, and a stabilizer. The electroless nickel-copper-phosphorus alloy plating bath includes a nickel salt, a copper salt, a hypophosphite, a reducing agent, a complexing agent, and a stabilizer.

  Similar to the electroless strike plating process described above, the nickel salt used in the electroless nickel plating bath can be one generally used for electroless plating of nickel. Specific examples of the nickel salt include nickel sulfate, nickel chloride, nickel carbonate, nickel acetate, nickel hypophosphite, nickel sulfamate, and nickel citrate. These may be used alone or in combination of two or more. In the present invention, it is most preferable to use nickel sulfate hexahydrate as the nickel salt. The nickel salt is preferably used in the range of 0.05 mol / L to 0.3 mol / L.

  As the reducing agent used in the electroless nickel plating bath, for example, hydrazine such as sodium hypophosphite, dimethylamine borane (DMAB), hydrazine hydrochloride and hydrazine sulfate is used in the same manner as the reducing agent used in the above-described reduction treatment step. A compound etc. can be mentioned. In the present invention, it is most preferable to use sodium hypophosphite as the reducing agent. The reducing agent is preferably used in the range of 0.01 mol / L to 0.5 mol / L.

  As the complexing agent used in the electroless nickel plating bath, those generally used in the electroless plating method can be used. Specific examples of the complexing agent include, for example, carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid and oxalic acid, hydroxycarboxylic acids such as lactic acid, glycolic acid, malic acid and citric acid, alanine, valine, Examples include amino acids such as tyrosine, glycine, aspartic acid, histidine and the like. In the present invention, it is preferable to use a combination of malic acid and succinic acid as the complexing agent. The complexing agent is preferably used in the range of 0.01 mol / L to 0.6 mol / L.

  As the stabilizer used in the electroless nickel plating bath, those generally used in the electroless plating method can be used. Specific examples of the stabilizer include bismuth, antimony, thiosulfuric acid, molybdenum, lead sulfate and the like. In the present invention, it is preferable to use lead sulfate as a stabilizer. The stabilizer is preferably used in the range of 0.01 mol / L to 2.0 mol / L.

  The electroless nickel plating bath and electroless nickel-phosphorus alloy plating bath in the present invention may contain components such as a pH adjuster (sulfuric acid, sodium hydroxide), for example, in addition to the above.

  In addition, the electroless nickel plating bath and the electroless nickel-phosphorus alloy plating bath in the present invention preferably have a pH in a neutral region of 4.5 to 6.0. And it is preferable that the temperature of the said electroless-plating bath is 60 to 90 degreeC.

  The nickel salt, reducing agent, complexing agent, stabilizer, etc. used in the electroless nickel-phosphorus alloy plating bath can be the same as those described above. In general, those used in the electroless plating method can be used. Specific examples of hypophosphites include sodium hypophosphite and potassium hypophosphite.

  Furthermore, as a source of nickel ions and copper ions used in the electroless nickel-copper-phosphorus alloy plating bath, various aqueous salts such as copper sulfate pentahydrate and nickel sulfate hexahydrate, for example, , Chlorides, sulfates, formates, acetates, carbonates, hydroxides or other salts can be used. The copper ion concentration C is preferably used in the range of 0.005 mol / L to 0.3 mol / L. This is because if 0.005 mol / L or more is contained, the precipitation reaction can proceed stably, and if it is 0.3 mol / L or less, precipitation of copper sulfate or the like does not occur. The copper ion concentration C and the nickel ion concentration N are preferably used in the range of (copper ion concentration C / nickel ion concentration N) of 1 to 10. If C / N is 1 or more, it becomes possible for copper precipitation reaction to proceed continuously, and if C / N is 1 or less and 10 or less, the nickel content in the plating layer is reduced and the resistance is low. Because it becomes.

  Examples of the complexing agent used in the electroless nickel-copper-phosphorus alloy plating bath include various water-soluble compounds such as trisodium citrate anhydrate, such as Rochelle salt, ethylenediaminetetraacetic acid (EDTA), Aspartic acid, glutamic acid, succinic acid, citric acid, or a salt or derivative of the above compound can be used. The concentration of the complexing agent is preferably 0.5 to 4 times the total concentration (C + N) of the copper ion concentration C and the nickel ion concentration N described above. If it is 4 times or less, precipitation does not occur, and if it is 0.5 times or more, the production of the concentrated liquid becomes easy.

  Moreover, hypophosphorous acid can be used as a reducing agent. As a source of hypophosphorous acid, sodium hypophosphite or potassium hypophosphite can be used. The concentration of hypophosphite ions is preferably 1 to 10 times the total concentration (C + N) of the copper ion concentration C and the nickel ion concentration N. If the concentration of hypophosphite ions is equal to or greater than (C + N), the precipitation reaction can be allowed to proceed stably, and if the concentration of hypophosphite ions is 10 times or less of (C + N), plating is performed. This is because the bath does not self-decompose.

  Lithium hydroxide may be added to the electroless nickel-copper-phosphorus alloy plating bath to adjust pH and improve conductivity. The lithium hydroxide is not an essential component, and sodium hydroxide or the like may be used. The electroless nickel-copper-phosphorus alloy plating bath preferably has a pH in the range of 8-11. In addition, the electroless nickel-copper-phosphorus alloy plating bath does not contain a surfactant, but is added to improve the wettability with the aluminum electrode surface on which the strike nickel plating layer is formed. Is preferred. As the surfactant, a cationic, anionic, nonionic or amphoteric surfactant that has been conventionally added to a plating bath can be used.

  In the electroless plating step, the electroless nickel having a thickness of 2 μm to 15 μm is formed on the surface of the aluminum electrode 12 on which the nickel strike plating layer 17 is formed by immersing the semiconductor wafer in the above-described electroless nickel plating bath. A plating layer, an electroless nickel-phosphorus alloy plating layer, or an electroless nickel-copper-phosphorus alloy plating layer 18 is deposited. After completion of the electroless plating process, a water washing process is performed.

  As described above, in the method of forming the electroless nickel plating layer of the present invention, the aluminum on the surface of the aluminum electrode 12 on the semiconductor wafer is replaced with nickel by the electroless strike plating method, and the surface of the aluminum electrode is formed. A nickel strike plating layer on which nickel is deposited is formed. Then, by immersing the semiconductor wafer on which the nickel strike plating layer is formed in an electroless plating bath, the electroless nickel which is the main plating using the nickel strike plating layer formed on the surface of the aluminum electrode as a nucleus. A plating layer, an electroless nickel-phosphorus alloy plating layer, or an electroless nickel-copper-phosphorus alloy plating layer is formed on the surface of the aluminum electrode by an electroless nickel plating method. Therefore, since the electroless nickel plating layer in the present invention is formed by deposition using the nickel strike plating layer as a nucleus, the electroless nickel plating layer has excellent adhesion with the aluminum electrode and can achieve a uniform film thickness.

  In particular, the electroless strike plating bath and the electroless plating bath used in the present invention are solutions each having a neutral pH range. Therefore, unlike the case of using a zincate solution or the like in the conventional strong alkaline region, it is possible to avoid the disadvantage that the surface of the aluminum electrode or the surface of the insulating layer of the semiconductor wafer is damaged. Therefore, when the conductor circuit is formed on the surface of the insulating layer 13, the surface of the insulating layer is kept smooth, so that a fine pitch conductor circuit can be formed.

  In addition, after completion | finish of the electroless-plating process mentioned above, after performing a water-wash process, it is preferable to make it dry and to anneal.

<Mode of Manufacturing Method of Semiconductor Wafer Substrate Comprising Nickel Layer as described above>
Next, the manufacturing method of a semiconductor wafer substrate provided with the nickel layer concerning this invention is demonstrated. The manufacturing method of a semiconductor wafer substrate according to the present invention is a manufacturing method of a semiconductor wafer substrate in which a conductor circuit is formed on the surface of an insulating layer of a semiconductor wafer provided with a nickel layer by the above-described forming method. In the method of manufacturing a semiconductor wafer substrate according to the present invention, the surface of the insulating layer of the semiconductor wafer is selectively surface-modified using a UV glass mask, and a catalyst is selectively applied only to the modified portion. And forming an electroless nickel layer, an electroless nickel-phosphorus alloy layer, or an electroless nickel-copper-phosphorus alloy layer selectively by an electroless plating method only on the portion to which the catalyst is applied. Features.

  Specifically, in the method for manufacturing a semiconductor wafer substrate according to the present invention, the electroless nickel plating layer is formed only on the surface of the aluminum electrode 12 of the semiconductor wafer as described above, and the electroless nickel plating layer is formed. A part of the surface of the insulating layer other than the above is subjected to surface modification treatment by UV irradiation, alkali degreasing and catalyst application, and then an electroless nickel plating bath, an electroless nickel-phosphorus alloy plating bath, or no Electroless nickel layer, electroless nickel-phosphorus alloy layer, or electroless nickel-copper-phosphorus alloy layer only on the part that has been immersed in the electrolytic nickel-copper-phosphorus alloy plating bath and subjected to the modification treatment A conductor circuit is formed.

  Hereinafter, a method for manufacturing a semiconductor wafer substrate according to the present invention will be described separately for each step with reference to FIGS. The layer configuration of the semiconductor wafer substrate shown in FIG. 4 schematically shows the concept of the layer configuration. Therefore, FIG. 4 is described so that the lamination state of each layer can be grasped, and the thickness of each layer does not reflect the thickness of the actual product.

  In the description of the method for manufacturing a semiconductor wafer substrate according to the present invention, an electroless nickel layer (or an electroless nickel-phosphorus alloy layer or an electroless nickel-copper-phosphorus alloy layer is formed on the surface of the aluminum electrode 12 described above. ) 18 will be described using the semiconductor wafer 10 formed thereon.

<Semiconductor wafer substrate manufacturing process>
Surface modification process:
The surface modification step as step S10 is a step of modifying the surface of the insulating layer 13 of the semiconductor wafer 10 in which the nickel plating layer 18 is formed on the surface of the aluminum electrode 12. In the surface modification step, UV is irradiated in an aerobic atmosphere using a photomask in which a conductor circuit pattern is formed, and only the portion where the conductor circuit is formed is surface-modified. At this time, it is preferable to partially expose the surface of the insulating layer 13 of the semiconductor wafer 10 with UV of the wavelength through a synthetic quartz mask using a low-pressure mercury lamp preferentially expressing the wavelengths of 184.9 nm and 257.3 nm. .

  The insulating layer 13 made of an insulating layer constituent material such as polyimide or polydimethylsiloxane is selectively subjected to surface modification treatment by partially exposing the UV having the wavelength. Specifically, the surface of an insulating layer made of an insulating layer constituent material such as polyimide or polydimethylsiloxane is irradiated with UV energy irradiated in an aerobic atmosphere such as an air atmosphere, and an —OH group or a —C═O group. Is formed. After the surface modification process, the process proceeds to step S11, and the process proceeds to the alkali immersion process.

Alkaline immersion process:
In the alkali dipping process as step S11, the semiconductor wafer 10 after the surface modification treatment is dipped in a sodium hydroxide aqueous solution, and the surface is degreased. Further, by being immersed in the alkaline solution, the polyimide imide ring constituting the insulating layer is opened to form [— (NH) C═O] and [— (C═O) OH], The hydrogen of [— (C═O) OH] is replaced by Na in aqueous sodium hydroxide. Therefore, [-(C = O) ONa], that is, -COONa is formed on the surface of the insulating layer 13. After completion of the alkali soaking process, the semiconductor wafer is washed with water, and then the process proceeds to the next catalyst application process.

Catalyst application process:
In the catalyst application step as step S12, the semiconductor wafer 10 after the alkali immersion step is immersed in a solution containing a catalyst such as palladium ions, so that Na of COONa on the surface of the insulating layer 13 is replaced with palladium ions. The palladium ion is adsorbed on the carboxyl group by substitution. After the semiconductor wafer 10 having the catalyst adsorbed on the surface of the insulating layer 13 is washed with water, the process proceeds to the next reduction process.

Reduction process:
In the reduction treatment step as Step S13, the semiconductor wafer 10 after the catalyst application step is immersed in a reducing solution, whereby the palladium ions of -COOPd are substituted with Na to reduce the palladium ions, and the reduced palladium ions are converted into the reduced palladium ions. It is deposited on the surface of the insulating layer 13 as a Pd catalyst. After reducing and precipitating the catalyst on the surface of the insulating layer 13, the semiconductor wafer 10 is washed with water, and the process proceeds to the next electroless plating step.

Electroless plating process:
In the electroless plating step as step S14, a nickel layer, a nickel-phosphorus alloy layer, or a nickel-copper-phosphorus alloy is formed on the surface of the insulating layer 13 on which the catalyst is selectively deposited by an electroless plating method. This is a step of forming the layer 20. FIG. 4 shows a state in which a nickel layer, a nickel-phosphorus alloy layer, or a nickel-copper-phosphorus alloy layer is formed. As the electroless plating bath used in the electroless plating step, it is possible to employ one generally used for electroless plating of nickel, nickel-phosphorus alloy or nickel-copper-phosphorus alloy. The electroless nickel plating bath includes a nickel salt, a reducing agent, a complexing agent, and a stabilizer. The electroless nickel-phosphorous alloy plating bath includes a nickel salt, a hypophosphite, a reducing agent, a complexing agent, and a stabilizer. The electroless nickel-copper-phosphorus alloy plating bath contains a nickel salt, a copper salt, a hypophosphite, a reducing agent, a complexing agent, and a stabilizer.

  Similar to the electroless strike plating process in step S4 and the electroless plating process in step S5, nickel salts generally used for electroless plating of nickel are used as the nickel salt used in the electroless nickel plating bath. be able to. Specific examples of the nickel salt include nickel sulfate, nickel chloride, nickel carbonate, nickel acetate, nickel hypophosphite, nickel sulfamate, and nickel citrate. These may be used alone or in combination of two or more. In the present invention, it is most preferable to use nickel sulfate hexahydrate as the nickel salt. The nickel salt is preferably used in the range of 0.05 mol / L to 0.3 mol / L.

  As the reducing agent used in the electroless nickel plating bath, for example, hydrazine such as sodium hypophosphite, dimethylamine borane (DMAB), hydrazine hydrochloride and hydrazine sulfate is used in the same manner as the reducing agent used in the above-described reduction treatment step. A compound etc. can be mentioned. In the present invention, it is most preferable to use sodium hypophosphite as the reducing agent. The reducing agent is preferably used in the range of 0.01 mol / L to 0.5 mol / L.

  As the complexing agent used in the electroless nickel plating bath, those generally used in the electroless plating method can be used. Specific examples of the complexing agent include, for example, carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid and oxalic acid, hydroxycarboxylic acids such as lactic acid, glycolic acid, malic acid and citric acid, alanine, valine, Examples include amino acids such as tyrosine, glycine, aspartic acid, histidine and the like. In the present invention, it is preferable to use a combination of citric acid and glycine as the complexing agent. The complexing agent is preferably used in the range of 0.01 mol / L to 0.5 mol / L.

  As the stabilizer used in the electroless nickel plating bath, those generally used in the electroless plating method can be used. Specific examples of the stabilizer include bismuth, antimony, thiosulfuric acid, molybdenum, lead sulfate and the like. In the present invention, it is preferable to use bismuth as a stabilizer. The stabilizer is preferably used in the range of 0.01 mg / L to 3.0 mg / L.

  The nickel salt, reducing agent, complexing agent, stabilizer, etc. used in the electroless nickel-phosphorus alloy plating bath can be the same as those described above. In general, those used in the electroless plating method can be used. Specific examples of hypophosphites include sodium hypophosphite and potassium hypophosphite.

  The electroless nickel plating bath and electroless nickel-phosphorus alloy plating bath in the present invention are not limited to those described above. For example, brighteners (sodium thiosulfate, lead, copper, etc.), pH buffer materials (ammonium sulfate, boric acid, chloride) It may contain components such as ammonium) and pH adjusters (sulfuric acid, sodium hydroxide). In the present invention, it is preferable that ammonium sulfate is contained as the pH buffer material and sodium thiosulfate is contained as the brightener.

  In addition, the electroless plating bath and the electroless nickel-phosphorus alloy plating bath in the present invention preferably have a pH in a neutral region to a weak alkali region of 4.5 to 8.0. And it is preferable that the temperature of the said electroless-plating bath is 40 to 80 degreeC.

  Furthermore, as a source of nickel ions and copper ions used in the electroless nickel-copper-phosphorus alloy plating bath, various aqueous salts such as copper sulfate pentahydrate and nickel sulfate hexahydrate, for example, , Chlorides, sulfates, formates, acetates, carbonates, hydroxides or other salts can be used. The copper ion concentration C is preferably used in the range of 0.005 mol / L to 0.3 mol / L. This is because if 0.005 mol / L or more is contained, the precipitation reaction can proceed stably, and if it is 0.3 mol / L or less, precipitation of copper sulfate or the like does not occur. The copper ion concentration C and the nickel ion concentration N are preferably used in the range of (copper ion concentration C / nickel ion concentration N) of 1 to 10. If C / N is 1 or more, it becomes possible for copper precipitation reaction to proceed continuously, and if C / N is 1 or less and 10 or less, the nickel content in the plating layer is reduced and the resistance is low. Because it becomes.

  Examples of the complexing agent used in the electroless nickel-copper-phosphorus alloy plating bath include various water-soluble compounds such as trisodium citrate anhydrate, such as Rochelle salt, ethylenediaminetetraacetic acid (EDTA), Aspartic acid, glutamic acid, succinic acid, citric acid, or a salt or derivative of the above compound can be used. The concentration of the complexing agent is preferably 0.5 to 4 times the total concentration (C + N) of the copper ion concentration C and the nickel ion concentration N described above. If it is 4 times or less, precipitation does not occur, and if it is 0.5 times or more, the production of the concentrated liquid becomes easy.

  Moreover, hypophosphorous acid can be used as a reducing agent. As a source of hypophosphorous acid, sodium hypophosphite or potassium hypophosphite can be used. The concentration of hypophosphite ions is preferably 1 to 10 times the total concentration (C + N) of the copper ion concentration C and the nickel ion concentration N. If the concentration of hypophosphite ions is equal to or greater than (C + N), the precipitation reaction can be allowed to proceed stably, and if the concentration of hypophosphite ions is 10 times or less of (C + N), plating is performed. This is because the bath does not self-decompose.

  Lithium hydroxide may be added to the electroless nickel-copper-phosphorus alloy plating bath to adjust pH and improve conductivity. The lithium hydroxide is not an essential component, and sodium hydroxide or the like may be used. The electroless nickel-copper-phosphorus alloy plating bath preferably has a pH in the range of 8-11. In addition, the electroless nickel-copper-phosphorus alloy plating bath does not contain a surfactant, but is added to improve the wettability with the aluminum electrode surface on which the strike nickel plating layer is formed. Is preferred. As the surfactant, a cationic, anionic, nonionic or amphoteric surfactant that has been conventionally added to a plating bath can be used.

  After completion of the electroless plating process described above, it is preferable to perform a water washing treatment, then dry and perform an annealing treatment. By passing through the above process, the semiconductor wafer substrate in which the nickel plating layer concerning this invention was formed can be obtained.

<Mode of Semiconductor Wafer Substrate Obtained by Method of Manufacturing Semiconductor Wafer Substrate According to Present Invention>
Next, the semiconductor wafer substrate according to the present invention will be described. The semiconductor wafer substrate according to the present invention is a semiconductor wafer substrate obtained by the above-described manufacturing method, and the nickel plating layer is provided on the surface of the aluminum electrode on the semiconductor wafer as described above in detail. A conductive circuit comprising a nickel layer, a nickel-phosphorus alloy layer, or a nickel-copper-phosphorus alloy layer is formed on the surface of the insulating layer of the semiconductor wafer by electroless plating.

  The thickness of the nickel layer, nickel-phosphorus alloy layer or nickel-copper-phosphorus alloy layer formed by the electroless plating method is preferably 2.0 μm to 10 μm.

  Further, a palladium layer may be further formed by an electroless plating method on the surface of the nickel layer, the nickel-phosphorus alloy layer, or the nickel-copper-phosphorus alloy layer formed by the electroless plating method. The thickness of the electroless palladium layer is preferably 0.03 μm to 0.3 μm.

  Furthermore, a gold plating layer may be formed on the surface of the electroless palladium layer by an electroless plating method. The thickness of the electroless gold plating layer is preferably 0.03 μm to 0.3 μm.

  The thickness of the metal layer formed on the surface of the nickel layer, the nickel-phosphorus alloy layer, or the nickel-copper-phosphorus alloy layer constituting the conductor circuit is not limited to the materials and thicknesses described above. Any material and thickness may be selected according to the use of the semiconductor wafer substrate to be manufactured.

  As described above, a palladium layer or a gold plating layer is further formed on the surface of the nickel layer, the nickel-phosphorus alloy layer, or the nickel-copper-phosphorus alloy layer 20 formed by the electroless plating method by the electroless plating method. By forming, it is possible to improve electrical conductivity and adhesion.

  A semiconductor wafer substrate in which a nickel layer, a nickel-phosphorus alloy layer, or a nickel-copper-phosphorus alloy layer is formed as a conductor circuit on the surface of the insulating layer according to the present invention as described above by electroless plating is applied to the surface of the insulating layer. A conductor circuit is formed by electroless plating after partial modification by UV irradiation. Here, the surface of the insulating layer in the present invention is not damaged by the strong alkaline solution in the process of forming the nickel plating layer on the aluminum electrode surface. Therefore, in the present invention, the surface of the insulating layer in a smooth state is partially irradiated with UV to perform surface modification treatment and a conductor circuit is formed by an electroless plating method. A strong anchor is obtained between the surface of the layer and the conductor circuit, and a conductor circuit with high adhesion can be realized.

  Hereinafter, as a specific example of a method for forming a nickel layer on the surface of an aluminum material according to the present invention, a semiconductor wafer having a nickel layer formed on the surface of an aluminum electrode, and a nickel layer on the insulating layer of the semiconductor wafer are provided. Example 1 of the semiconductor wafer substrate provided with the conductor circuit is shown.

  In the semiconductor wafer employed in Example 1, an aluminum electrode is formed through a base insulating layer, and an insulating layer made of polyimide is formed on the surface of the base insulating layer on which the aluminum electrode is formed. ing. An opening is formed in the insulating layer formed on the semiconductor wafer by a selective etching process, and the aluminum electrode is exposed.

  First, a neutral degreasing process was performed. In the neutral degreasing step in this example, a semiconductor wafer provided with an aluminum electrode exposed in a solution of 50 ml / L at 45 ° C. diluted with 5% of a tableware neutral detergent (cascade complete manufactured by P & G). Was immersed for 2 minutes. Thereafter, the semiconductor wafer was washed with water and then subjected to an acid dipping process.

  In the acid soaking step in the examples, sulfuric acid 50 ml / L, phosphoric acid 50 ml / L, Toho Chemical Co., Ltd. PEG-1000 (polyethylene glycol) 100 g / L of acidic solution at 45 ° C. after neutral degreasing step The semiconductor wafer was immersed for 5 minutes. Thereafter, the semiconductor wafer was washed with water and then subjected to a reduction treatment step.

  In the reduction treatment step in Examples, the semiconductor wafer after the acid immersion step was immersed in 2.5 g / L of dimethylamine borane (DMAB) at 45 ° C. for 1 minute. Then, the electroless strike plating process was performed without performing the water washing process.

In the electroless strike plating step in the examples, a nickel strike plating layer was formed on the surface of the aluminum electrode of the semiconductor wafer by a plating bath having the following composition and plating conditions. After completion of the electroless strike plating step, washing with water was performed.
Electroless strike nickel plating bath composition:
Nickel sulfate hexahydrate 0.1 mol / L
Dimethylamine borane (DMAB) 2.5g / L
Glycine 0.1 mol / L
Succinic acid 0.1 mol / L
Bismuth 1.0mg / L
Ammonium sulfate 0.2 mol / L
Boric acid 10g / L
Sodium thiosulfate 2.0mg / L
Sulfuric acid and ammonia plating conditions for pH adjustment:
Bath pH 5.5
Bath temperature 50 ° C
Plating time 10 minutes

In the electroless plating process in Example 1, an electroless nickel plating layer was formed on the surface of the aluminum electrode of the semiconductor wafer by a plating bath having the following composition and plating conditions.
Electroless nickel plating bath composition:
Nickel sulfate hexahydrate 0.1 mol / L
Sodium hypophosphite 0.2mol / L
Malic acid 0.1 mol / L
Succinic acid 0.15 mol / L
Lead sulfate 0.1mg / L
Sulfuric acid and sodium hydroxide plating conditions for pH adjustment:
Bath pH 7.0
Bath temperature 80 ° C
Plating time 15 minutes

  After completion of the electroless plating step, the substrate was washed with water, then dried and annealed at 150 ° C. for 60 minutes. Through the above steps, a semiconductor wafer having a nickel plating layer formed on the surface of the aluminum electrode could be obtained.

  Next, an example of a semiconductor wafer substrate in which a conductor circuit is formed on the surface of an insulating layer of a semiconductor wafer provided with a nickel layer on the surface of the aluminum electrode described above will be described.

  First, in the surface modification step, UV light is irradiated from a UV lamp manufactured by Koto Electric Co., Ltd. in an air atmosphere using a photomask on which a conductor circuit is formed, and only the surface of the insulating layer where the conductor circuit is formed is irradiated. The surface was modified. The distance between the UV lamp and the surface of the insulating layer was 30 mm, and UV irradiation was performed for 1 minute.

Next, in the alkali dipping step, the semiconductor wafer was dipped in a solution of sodium hydroxide at a concentration of 1 g / L at 65 ° C. for 1 minute. After completion of the alkali soaking process, the semiconductor wafer was washed with water, and then a catalyst application process was performed. In the catalyst application step, the semiconductor wafer was immersed in a solution of palladium (II) chloride at a concentration of 10.3 g / L at 45 ° C. for 1 minute. Then, after performing the water washing process, the reduction process process was performed. In the reduction treatment step, 45 ° C. of _{NaH 2 PO 2 · H 2 O} 1 minute to a solution of concentration 35 g / L of were immersed the semiconductor wafer. Then, after performing the water washing process, the electroless-plating process was performed.

In the electroless plating process in the embodiment, the surface of the insulating layer of the semiconductor wafer is subjected to surface modification treatment by a plating bath having the following composition and plating conditions, and a nickel-phosphorus alloy layer is formed on the surface of the portion provided with the catalyst. Formed. After completion of the electroless plating process, washing with water was performed.
Electroless nickel-phosphorus plating bath composition:
Nickel sulfate hexahydrate 26.3 g / L
Sodium hypophosphite 21.2g / L
Glycine 7.5g / L
Citric acid (anhydrous) 19.2 g / L
Bismuth 1.0ppm
Ammonium sulfate 26.4g / L
Sodium thiosulfate 20g / L
Sodium hydroxide 20g / L
Plating conditions:
Bath pH 8.0
Bath temperature 45 ° C
Plating time 40 minutes

  After completion of the electroless plating step, the substrate was washed with water, then dried and annealed at 150 ° C. for 60 minutes. Through the above steps, a semiconductor wafer substrate in which a conductor circuit made of a nickel-phosphorus alloy layer was formed on the surface of the insulating layer could be obtained. On the semiconductor wafer substrate on which the conductor circuit is formed, the surface of the insulating layer made of an insulating layer constituent material such as polyimide or polydimethylsiloxane is partially modified by UV irradiation with a low-pressure mercury lamp, and the conductor circuit is formed by an electroless plating method. It has been done. Therefore, a strong anchor is obtained between the surface of the insulating layer and the conductor circuit, and a conductor circuit with high adhesion can be realized.

  A semiconductor wafer substrate having a nickel layer formed on the surface of an aluminum electrode as Example 2 and a conductor circuit made of a nickel layer on the insulating layer of the semiconductor wafer will be described. The semiconductor wafer in Example 2 differs from Example 1 described above only in the plating bath used in the electroless plating process, and is otherwise the same. Here, only the plating bath used in the electroless plating process will be described.

In the electroless plating step in Example 2, an electroless nickel-copper-phosphorus alloy plating layer was formed on the surface of the aluminum electrode of the semiconductor wafer by a plating bath and plating conditions having the following composition.
Electroless nickel-copper-phosphorus alloy plating bath composition:
Copper sulfate pentahydrate 0.03 mol / L
Nickel sulfate hexahydrate 0.01mol / L
Trisodium citrate anhydrous 0.06 mol / L
Sodium carbonate 0.25 mol / L
Sodium hypophosphite monohydrate 0.18 mol / L
Surfactant appropriate amount Lithium hydroxide 0.1g / L
Bath pH 9.0
Bath temperature 45 ° C
Plating time 50 minutes

  According to Example 2, a semiconductor wafer in which a nickel-copper-phosphorus alloy plating layer was formed on the aluminum electrode surface could be obtained. In the case of Example 2, as in Example 1, a conductor circuit made of a nickel-phosphorus alloy layer was formed on the surface of the insulating layer on the surface of the insulating layer of the semiconductor wafer substrate. Even in the case of Example 2, when the nickel layer is formed on the surface of the aluminum electrode, since the surface of the insulating layer is not greatly damaged, a strong anchor is provided between the surface of the insulating layer and the conductor circuit. As a result, a conductor circuit with high adhesion could be realized.

  According to the method for forming a nickel layer on the surface of an aluminum material according to the present invention, a nickel strike plating layer is formed on the surface of the aluminum material using a low alkaline electroless strike plating bath, and formed on the surface of the aluminum material. Using the nickel strike plating layer as a nucleus, a nickel plating layer, a nickel-phosphorus alloy plating layer, or a nickel-copper-phosphorus alloy plating layer can be formed by electroless plating. Therefore, when the nickel plating layer is formed on the surface of the aluminum electrode of the semiconductor wafer, it is not necessary to use a conventional strong alkaline zincate solution by adopting the present invention. Therefore, the insulating layer of the semiconductor wafer is formed by the zincate solution. It is possible to avoid the inconvenience of damaging the surface. Therefore, when the conductor circuit is formed on the surface of the insulating layer, the smoothness of the surface of the insulating layer is maintained, so that the conductor circuit can be appropriately formed.

DESCRIPTION OF SYMBOLS 10 Semiconductor wafer 11 Base insulating layer 12 Aluminum electrode 13 Insulating layer 15 Opening part 16 Natural oxide film 17 Nickel strike plating layer 18 Nickel plating layer 20 Nickel layer or nickel- phosphorus alloy layer or nickel- copper- phosphorus alloy layer (conductor circuit)

Claims (6)

A method of forming a nickel layer on the surface of an aluminum material,
A nickel strike plating layer is formed on the surface of the aluminum material using an electroless strike plating method, and then an electroless nickel plating layer or an electroless nickel-phosphorus alloy plating is formed on the surface of the aluminum material using an electroless plating method. Forming a nickel layer on the surface of an aluminum material, comprising forming a layer or an electroless nickel-copper-phosphorus alloy plating layer. A method for forming a nickel plating layer on the surface of an aluminum electrode on a semiconductor wafer using the method for forming a nickel layer on the surface of an aluminum material according to claim 1,
A nickel strike plating layer is formed on the surface of the aluminum electrode using an electroless strike plating method, and then an electroless nickel plating layer or an electroless nickel-phosphorus alloy plating is formed on the surface of the aluminum electrode using an electroless plating method. A method of forming a nickel plating layer on an aluminum electrode surface on a semiconductor wafer, comprising forming a layer or an electroless nickel-copper-phosphorus alloy plating layer. A method for producing a semiconductor wafer substrate using the method for forming a nickel plating layer on the surface of an aluminum electrode on a semiconductor wafer according to claim 2,
The surface of the insulating layer of the semiconductor wafer is selectively irradiated with UV to modify the surface, the catalyst is selectively applied only to the modified portion, and the electroless plating is selectively applied only to the portion to which the catalyst is applied. A method for producing a semiconductor wafer substrate, comprising forming an electroless nickel layer, an electroless nickel-phosphorus alloy layer, or an electroless nickel-copper-phosphorus alloy layer using a method.   A conductor circuit comprising a nickel layer, a nickel-phosphorus alloy layer, or a nickel-copper-phosphorus alloy layer is provided on the surface of the insulating layer of the semiconductor wafer using the method for producing a semiconductor wafer substrate according to claim 3. A semiconductor wafer substrate.   The semiconductor wafer substrate according to claim 4, further comprising a palladium layer formed by an electroless plating method on a surface of the nickel layer, the nickel-phosphorus alloy layer, or the nickel-copper-phosphorus alloy layer.   The semiconductor wafer substrate according to claim 5, comprising a gold plating layer formed by an electroless plating method on a surface of the palladium layer.

Images