JP2011208227A - Pretreatment liquid of electroless plating onto semiconductor wafer, electroless plating method, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretreatment liquid for performing electroless plating of nickel or an nickel alloy onto a semiconductor wafer in which n-type and p-type semiconductors are mixed.SOLUTION: The pretreatment liquid of electroless plating is an aqueous solution composed of hydrogen peroxide water, ammonia water and/or tetramethyl ammonium hydroxide (TMAH). When transistor electrodes in which n-type and p-type semiconductors are mixed such as a source and drain electrodes of FET are formed, impurities on a surface of a silicon substrate can be effectively removed or reduced and the surface of the silicon substrate can be activated with the use of the pretreatment liquid of electroless plating. When n-type and p-type semiconductors are mixed in such a silicon substrate, after treatment by the liquid is performed, the pretreatment liquid is adaptable to a subsequent electroless Ni or Ni alloy plating, and thus uniform electroless plating can be performed.

Description

  According to the present invention, in the step of forming an electroless plating film on a semiconductor wafer treated with the present pretreatment liquid, a metal film can be formed on both n-type and p-type semiconductors with the same electroless plating liquid. The present invention relates to a pretreatment liquid for electroless plating on a semiconductor wafer, an electroless plating method using the pretreatment, and a semiconductor device manufactured using the electroless plating method.

  In general, a semiconductor element such as a transistor has a pair of source / drain regions formed in an element region on a silicon substrate with a channel region therebetween, a source / drain electrode, and a gate electrode formed in the channel region via a gate insulating film. Semiconductor devices are known. Typical examples are MOSFET and CMOSFET.

  In recent years, when forming a transistor electrode in which an n-type semiconductor and a p-type semiconductor are mixed, such as a source / drain electrode such as an FET, a metal film having a thickness of 20-100 nm suitable for the electrode is formed. For example, a NiP electroless plating metal film or a NiB electroless plating film is formed.

  Further, the use of a NiSi film by a salicide process as a gate electrode material has attracted attention. Nickel has a feature that a silicide film can be formed with little silicon consumption by the salicide process. Since this NiSi has the feature that it is difficult for the wire resistance to increase due to miniaturization of the wiring, electroless Ni or Ni alloy plating is performed.

In general, the electroless Ni or Ni alloy plating method is a relatively simple method and has an advantage that a thin layer can be formed uniformly and with high productivity. In addition, performing electroless Ni or Ni alloy plating on a silicon element has a problem of selecting an optimal plating solution, but is not so difficult.
However, the problem here is that contaminants are present on the silicon semiconductor substrate. Therefore, in order to remove the contaminants and activate the surface, pretreatment is performed when Ni or Ni alloy plating is performed. Is required.

Major contaminants include metal ions such as Na ⁺ , Li ⁺ and K ⁺ , ionic contaminants such as F ⁻ , Cl ⁻ and SO ₄ ⁻⁻ ions, organic contaminants, Fe, Ni, Cr and the like. Heavy metals, noble metals such as Au and Ag, alkaline earth metals, oxides such as carbon (C), silica and alumina. These need to be removed or reduced.
On the other hand, a silicon substrate that removes such contaminants is a mixture of n-type semiconductors and p-type semiconductors. Therefore, it is possible to adapt to electroless Ni or Ni alloy plating, and whether electroless plating can be performed without any problem.

  In Patent Document 1 below, since the oxidation-reduction potential of Ni is located approximately in the middle of the band gap of a silicon semiconductor, it is easy to receive electrons from the high potential n side, and that on the p side is (Fermi level). It is described that the thickness of the electroless plating becomes non-uniform because it is difficult to release, and therefore a proposal has been made to use a pretreatment liquid of a mixture of hydrofluoric acid, hydrogen peroxide solution and phosphoric acid. However, in this case, since highly toxic hydrofluoric acid is used, it cannot be said to be a preferable pretreatment liquid.

In the following Patent Document 2, after performing metal plating of Ni or Cr, a heat treatment is performed to form a silicide layer. From the unreacted metal present on the silicide layer and the reducing agent used in the plating step, In order to remove the deposited layer, a method of forming an electrode of a semiconductor element is described in which etching is performed using hydrochloric acid and hydrogen peroxide, and Ni is plated on a silicide layer.
In this case, there is no particular description about the pretreatment of the plating, and this technique is used as an electrode for joining with a solder ball, and is applied to bulk Si that is not implanted. It is considered that (n-type, p-type) cannot be applied to Si.

  Patent Document 3 below describes that impurities on a silicon wafer are removed from a semiconductor surface using a tetraalkylammonium hydroxide and an aqueous hydrogen peroxide solution. However, in this case, it is used for removing contaminants, and when the silicon substrate is a mixture of n-type semiconductor and p-type semiconductor, after the treatment with this cleaning liquid, the subsequent electroless Ni or It is completely unknown whether or not Ni alloy plating can be applied and uniform electroless plating can be performed.

  Non-Patent Document 1 below describes that a semiconductor surface is cleaned using a cleaning solution based on ammonia water / hydrogen peroxide solution / water. In this case as well, it is used to remove contaminants on the surface of the semiconductor substrate as in the above-mentioned Patent Document 3. When the silicon substrate is a mixture of an n-type semiconductor and a p-type semiconductor, the treatment with this cleaning liquid was performed. Later, it is completely unknown whether it can be applied to the subsequent electroless Ni or Ni alloy plating and uniform electroless plating can be performed.

Japanese Patent No. 3975625 Japanese Patent No. 4343809 JP 50-147284 A

Masao Miyazaki “New RCA Cleaning Technology for Semiconductor / FPD”, Publication “The Chemical Times”, Vol. 198 (2005. No. 4), pages 6-10

  In the present invention, when forming a transistor electrode in which an n-type semiconductor and a p-type semiconductor are mixed, such as a source / drain electrode such as an FET, a silicon substrate (hereinafter referred to as “silicon wafer”. The cleaning solution can be used when the surface impurities can be effectively removed or reduced and activated, and the n-type semiconductor and the p-type semiconductor are mixed in such a silicon wafer. It is an object of the present invention to provide a technique that can be applied to subsequent electroless Ni or Ni alloy plating and can perform uniform electroless plating.

  In order to solve the above problems, it is possible to perform uniform electroless plating of nickel or a nickel alloy on a semiconductor silicon wafer in which an n-type semiconductor and a p-type semiconductor are mixed by appropriately selecting a pretreatment liquid. Obtained knowledge.

Based on this finding, the present invention provides the following inventions.
1) A pretreatment liquid for performing electroless plating of nickel or a nickel alloy on a semiconductor wafer in which an n-type semiconductor and a p-type semiconductor are mixed, the pretreatment liquid comprising hydrogen peroxide water, ammonia water, and / or Alternatively, a pretreatment solution for electroless plating, which is an aqueous solution made of tetramethylammonium hydroxide (TMAH).
2) In the pretreatment liquid described in 1), hydrogen peroxide is 0.1 to 10.0 wt%, ammonia is 0.1 to 10.0 wt%, and TMAH is 0.5 to 8.0 wt%. A pretreatment solution for electroless plating.

The present invention also provides the following inventions.
3) A nickel or nickel alloy layer is formed on a semiconductor wafer after cleaning a semiconductor wafer in which an n-type semiconductor and a p-type semiconductor are mixed using the pretreatment liquid described in 1) or 2) above. Electroless plating method.
4) The electroless plating method as described in 3) above, wherein a nickel or nickel alloy layer having a thickness of 20 to 100 nm is formed.
5) The electroless plating method according to 4) above, wherein the nickel alloy layer is NiP or NiB.
6) The semiconductor device manufactured by the electroless-plating method as described in any one of said 3) -5).

In the present invention, when forming a transistor electrode in which an n-type semiconductor and a p-type semiconductor are mixed, such as a source / drain electrode such as an FET, impurities on the surface of the silicon wafer, for example, metal ions such as Na ⁺ , Li ⁺ , K ⁺ , F ⁻ , Cl ⁻ , SO ₄ ⁻ ions and other ionic contaminants, organic contaminants, heavy metals such as Fe, Ni and Cr, noble metals such as Au and Ag, alkaline earth metals, carbon (C), silica In the case where an oxide impurity such as alumina can be effectively removed or reduced and activated, and when such a silicon wafer is mixed with an n-type semiconductor and a p-type semiconductor, the treatment with this cleaning liquid is performed. After performing the above, it can be adapted to subsequent electroless Ni or Ni alloy plating, and has an excellent effect that uniform electroless plating can be performed.

  The present invention relates to a pretreatment liquid that pretreats a semiconductor wafer in advance, effectively removes impurities, and activates when performing electroless plating of nickel or a nickel alloy on a semiconductor wafer, In particular, it is a pretreatment liquid for processing a semiconductor wafer in which an n-type semiconductor and a p-type semiconductor are mixed. The meaning of “mixed” of an n-type semiconductor and a p-type semiconductor means that an n-type semiconductor and a p-type semiconductor exist on the processing surface of a wafer to be electrolessly plated with nickel or a nickel alloy.

The pretreatment liquid is important in terms of removing impurities from the semiconductor wafer and activating the semiconductor wafer. What is further necessary is that the n-type semiconductor is used in the subsequent electroless plating of nickel or a nickel alloy. This means that the electroless plating layer on the semiconductor wafer “mixed” with the p-type semiconductor forms a uniform plating film at any location.
Since the required electroless plating of nickel or nickel alloy has a very thin film thickness of 20 to 100 nm, it is very important to make it uniform. The present invention is able to achieve this.

  The pretreatment liquid for electroless plating of the present invention is an aqueous solution comprising hydrogen peroxide water and ammonia water and / or tetramethylammonium hydroxide (TMAH). In this case, it is desirable that hydrogen peroxide is 0.1 to 10.0 wt%, ammonia is 0.1 to 10.0 wt%, and TMAH is 0.5 to 8.0 wt%.

If the hydrogen peroxide is less than 0.5 wt%, uneven plating, cloudiness, and loss of plating are likely to occur. Also, if hydrogen peroxide exceeds 10.0 wt%, it takes time to warm up. (Because a method in which pure water and ammonia water are heated in advance and hydrogen peroxide water is added thereto, If there is a lot of water, the temperature drop will increase and it will take time to heat.The commercially available aqueous hydrogen peroxide solution is 30 wt%, so in the case of 10 wt%, an amount of hydrogen peroxide aqueous solution corresponding to 30% of the solution added at the time of mixing The amount of hydrogen peroxide decomposed and lost during heating is increased and wasted, so it is desirable that the hydrogen peroxide be 0.5 to 10.0 wt%.
On the other hand, if the ammonia content is less than 0.1 wt%, uneven plating, cloudiness, and loss of plating are likely to occur. If the amount of ammonia exceeds 10.0 wt%, the effect is not improved, but the vapor pressure of ammonia increases, and the amount of ammonia gas dissipated outside the system becomes large. Therefore, the amount of ammonia is set to 0.5 to 10.0 wt%. Is desirable.

  Furthermore, when TMAH is less than 0.5 wt%, uneven plating, cloudiness, and loss of plating tend to occur. If TMAH exceeds 8.0 wt%, elution of the Si surface occurs, so it is desirable that TMAH be 0.5 to 8.0 wt%. It is also possible to use a mixture of ammonia and TMAH. In this case, strictness is not required, but the total amount used is preferably 0.5 to 10.0 wt%.

  Since TMAH has a low vapor pressure, fluctuations in the liquid composition due to evaporation can be suppressed, and generation of harmful gases can also be prevented. TMAH is not designated as a deleterious substance. Furthermore, ammonia is flammable but TMAH is nonflammable. Therefore, TMAH can be said to be more preferable because it is a high quality and safe process as compared with the case of using ammonia.

The present invention includes an electroless plating method of forming a nickel or nickel alloy layer on a semiconductor wafer after cleaning a semiconductor wafer in which an n-type semiconductor and a p-type semiconductor are mixed using the pretreatment liquid. The electroless plating desirably has a pH of less than 9. This is because when the pH is 9 or more, the elution reaction of Si becomes active and the interface between the Ni plating and Si tends to be rough, but if the pH is less than 9, this can be suppressed.
As the nickel alloy layer, a NiP layer or a NiB layer can be particularly preferably used. The present invention also includes a semiconductor device manufactured by the electroless plating method.

  Next, examples and comparative 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 aspects or modifications other than the embodiments are included within the scope of the technical idea of the present invention.

Example 1
Pretreatment was performed on a p-type semiconductor substrate with a pretreatment liquid composed of hydrogen peroxide and ammonia, and NiP plating thin film and NiB plating thin film were formed thereon by electroless plating.
As the P-type semiconductor substrate, P: 1.0 × 10 ¹³ was implanted in Si at 150 keV and B1.0 × 10 ¹⁵ was implanted at 8 keV to form a p-type semiconductor.

When the pretreatment liquid is heated after preparation, the decomposition and consumption of hydrogen peroxide is remarkable. Therefore, the necessary amount of aqueous hydrogen peroxide solution is added to the mixture of ion-exchanged water and the required amount of ammonia kept at 80 ° C in advance. Was added to suppress the decomposition of the hydrogen peroxide solution.
As a result, an aqueous solution containing 0.1 wt% hydrogen peroxide and 0.1 wt% ammonia was obtained. This was kept at 70 ° C. and the semiconductor substrate was immersed for 10 minutes. Then, it was immersed and washed in ion-exchanged water at room temperature and immediately plated.

The NiP film was formed by electroless plating under the conditions of pH 8.0 and 70 ° C. × 1.0 minutes 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, and phosphinic acid 26.4 g / L. It is adjusted to 8.0.

The NiB film was formed by electroless plating under the conditions of pH 7.5, 70 ° C. × 1.0 minutes 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, dimethylamine borane (DMAB) 5.0 g / L, and aqueous ammonia. The pH is adjusted to 7.5 by addition.
Judgment of the deposition of the plating was confirmed by a fluorescent X-ray spectrometer that the deposit was Ni, and the appearance of the plating was visually evaluated based on the presence or absence of unevenness and the presence or absence of omission. The results are summarized in Table 1.

  In Example 1, a p-type Si substrate was used. An aqueous solution containing 0.1 wt% hydrogen peroxide and 0.1 wt% ammonia, that is, an aqueous solution of hydrogen peroxide and ammonia was used in the present invention. Since it is the lower limit value, the electroless NiP plating and the electroless NiB plating were found to be uneven. However, although this level of unevenness is not a problem, the evaluation is Δ (a little good).

(Example 2)
In Example 2, the pretreatment liquid in Example 1 is an aqueous solution containing 1 wt% of hydrogen peroxide and 1 wt% of ammonia as shown in Table 1, and this type of pretreatment liquid is used to form P-type as in Example 1. A Si substrate was pretreated, and in the same manner as in Example 1, a NiP plating thin film and a NiB plating thin film were formed thereon by an electroless plating method and evaluated. The same applies to Example 6 below.
Both the electroless NiP plating and the electroless NiB plating did not cause unevenness or cloudiness, and were good plating.

(Example 3)
In Example 3, the pretreatment liquid in Example 1 is an aqueous solution containing 3 wt% of hydrogen peroxide and 3 wt% of ammonia as shown in Table 1, and this type of pretreatment liquid is used to form P-type as in Example 1. A Si substrate was pretreated, and in the same manner as in Example 1, a NiP plating thin film and a NiB plating thin film were formed thereon by an electroless plating method and evaluated.
Both the electroless NiP plating and the electroless NiB plating did not cause unevenness or cloudiness, and were good plating.

Example 4
In Example 4, the pretreatment liquid in Example 1 is an aqueous solution containing 5 wt% of hydrogen peroxide and 5 wt% of ammonia as shown in Table 1, and this type of pretreatment liquid is used to form P-type as in Example 1. A Si substrate was pretreated, and in the same manner as in Example 1, a NiP plating thin film and a NiB plating thin film were formed thereon by an electroless plating method and evaluated.
Both the electroless NiP plating and the electroless NiB plating did not cause unevenness or cloudiness, and were good plating.

(Example 5)
In Example 5, the pretreatment liquid in Example 1 is an aqueous solution containing 8 wt% of hydrogen peroxide and 8 wt% of ammonia as shown in Table 1, and by using this pretreatment liquid, as in Example 1, P-type A Si substrate was pretreated, and in the same manner as in Example 1, a NiP plating thin film and a NiB plating thin film were formed thereon by an electroless plating method and evaluated.
Both the electroless NiP plating and the electroless NiB plating did not cause unevenness or cloudiness, and were good plating.

(Example 6)
In Example 6, the pretreatment liquid in Example 1 is an aqueous solution containing 10 wt% of hydrogen peroxide and 10 wt% of ammonia as shown in Table 1, and this type of pretreatment liquid is used to form P-type as in Example 1. A Si substrate was pretreated, and in the same manner as in Example 1, a NiP plating thin film and a NiB plating thin film were formed thereon by an electroless plating method and evaluated.
Both the electroless NiP plating and the electroless NiB plating did not cause unevenness or cloudiness, and were good plating.

(Example 7)
Electroless plating was performed and evaluated in the same manner as in Example 1-6 except that the semiconductor substrate in Example 1-6 was changed to an n-type semiconductor. As the n-type semiconductor, As 1.0 × 10 ¹⁵ was implanted into Si at 40 keV to form an n-type semiconductor. The same applies to Example 12 below.
In Example 7, an aqueous solution containing 0.1 wt% of hydrogen peroxide and 0.1 wt% of ammonia, that is, an aqueous solution of hydrogen peroxide and ammonia is the lower limit value of the present invention, so electroless NiP plating and electroless The NiB plating was found to be uneven and cloudy. However, the occurrence of such unevenness and cloudiness is not a problem, but the evaluation is Δ (somewhat good).

(Example 8)
In Example 8, pretreatment was performed on an n-type Si substrate by using a pretreatment liquid composed of an aqueous solution containing 1 wt% hydrogen peroxide and 1 wt% ammonia. The NiP plating thin film and the NiB plating thin film were formed by a plating method and evaluated.
In this case, unevenness was observed in both the electroless NiP plating and the electroless NiB plating. However, the occurrence of such unevenness and cloudiness is not a problem, but the evaluation is Δ (somewhat good).

Example 9
In this Example 9, a pretreatment was performed on an n-type Si substrate using a pretreatment liquid composed of an aqueous solution containing 3 wt% hydrogen peroxide and 3 wt% ammonia. The NiP plating thin film and the NiB plating thin film were formed by a plating method and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 10)
In this Example 10, pretreatment was performed on an n-type Si substrate using a pretreatment liquid composed of an aqueous solution containing 5 wt% hydrogen peroxide and 5 wt% ammonia. The NiP plating thin film and the NiB plating thin film were formed by a plating method and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 11)
In this example 11, pretreatment was performed on an n-type Si substrate using a pretreatment liquid composed of an aqueous solution containing 8 wt% hydrogen peroxide and 8 wt% ammonia. The NiP plating thin film and the NiB plating thin film were formed by a plating method and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 12)
In Example 12, pretreatment was performed on an n-type Si substrate using a pretreatment liquid composed of an aqueous solution containing 10 wt% hydrogen peroxide and 10 wt% ammonia. The NiP plating thin film and the NiB plating thin film were formed by a plating method and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 13)
Except that ammonia in the pretreatment liquid in Example 1-12 was changed to TMAH as shown in Table 1, electroless plating was performed and evaluated in the same manner as in Example 1-6. The same applies to Example 17 below.
In this Example 13, a p-type Si substrate was pretreated with a pretreatment liquid composed of an aqueous solution containing 0.5 wt% hydrogen peroxide and 0.5 wt% TMAH, and in the same manner as in Example 1, The NiP plating thin film and the NiB plating thin film were formed by electroless plating and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 14)
In this Example 14, a p-type Si substrate was pretreated using a pretreatment liquid composed of an aqueous solution containing 3 wt% hydrogen peroxide and 3 wt% TMAH, and electroless plating was further formed thereon as in the first embodiment. The NiP plating thin film and the NiB plating thin film were formed by the method and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 15)
In this Example 15, a p-type Si substrate was pretreated using a pretreatment liquid composed of an aqueous solution containing 5 wt% hydrogen peroxide and 5 wt% TMAH, and in the same manner as in Example 1, electroless plating was performed thereon. The NiP plating thin film and the NiB plating thin film were formed by the method and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 16)
In this example 16, a p-type Si substrate was pretreated using a pretreatment liquid composed of an aqueous solution containing 8 wt% hydrogen peroxide and 8 wt% TMAH, and electroless plating was performed thereon as in the case of the first embodiment. The NiP plating thin film and the NiB plating thin film were formed by the method and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 17)
In this Example 17, a p-type Si substrate was pretreated using a pretreatment liquid composed of an aqueous solution containing 10 wt% hydrogen peroxide and 10 wt% TMAH, and in the same manner as in Example 1, electroless plating was performed thereon. The NiP plating thin film and the NiB plating thin film were formed by the method and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 18)
As shown in Table 1, for Examples 18-22, electroless electrolysis was performed in the same manner as in Examples 13-17 except that the p-type Si substrate in Examples 13-17 was changed to an n-type Si substrate. Plating was performed and evaluated.
In Example 18, a n-type Si substrate was subjected to pretreatment using a pretreatment liquid composed of an aqueous solution containing 0.5 wt% hydrogen peroxide and 0.5 wt% TMAH. The NiP plating thin film and the NiB plating thin film were formed by electroless plating and evaluated.
In this case, unevenness was observed in both the electroless NiP plating and the electroless NiB plating. However, the occurrence of such unevenness and cloudiness is not a problem, but the evaluation is Δ (somewhat good).

(Example 19)
In Example 19, an n-type Si substrate was subjected to pretreatment using a pretreatment liquid composed of an aqueous solution containing 3 wt% hydrogen peroxide and 3 wt% TMAH, and in the same manner as in Example 1, an electroless plating method was formed thereon. The NiP plating thin film and the NiB plating thin film were formed and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 20)
In Example 20, a n-type Si substrate was subjected to pretreatment using a pretreatment liquid composed of an aqueous solution containing 5 wt% hydrogen peroxide and 5 wt% TMAH, and in the same manner as in Example 1, an electroless plating method was formed thereon. The NiP plating thin film and the NiB plating thin film were formed and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 21)
In Example 21, an n-type Si substrate was subjected to pretreatment using a pretreatment liquid composed of an aqueous solution containing 8 wt% hydrogen peroxide and 8 wt% TMAH, and the electroless plating method was further formed thereon as in Example 1. The NiP plating thin film and the NiB plating thin film were formed and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

(Example 22)
In Example 22, pretreatment was performed on an n-type Si substrate using a pretreatment liquid composed of an aqueous solution containing 10 wt% hydrogen peroxide and 10 wt% TMAH, and the electroless plating method was further formed thereon as in Example 1. The NiP plating thin film and the NiB plating thin film were formed and evaluated.
In this case, both the electroless NiP plating and the electroless NiB plating were good.

For Examples 1-22 above, the pretreatment liquid consisting of an aqueous solution of hydrogen peroxide and ammonia or TMAH had the same combined addition amount, but if the amount is within the scope of the present invention, for example, Similar results were obtained even when the addition amount was changed and combined, such as 3 wt% hydrogen peroxide and 5 wt% TMAH.
In addition, as apparent from the above results, ammonia and TMAH with respect to hydrogen peroxide show almost equivalent effects, so even if ammonia and TMAH are mixed and added, almost equivalent results can be obtained. I was able to. The amount added can be adjusted to approximately 0.1 to 10.0 wt%.

(Comparative Example 1)
In Comparative Example 1, electroless plating was performed and evaluated in the same manner as in Example 1 except that a p-type Si substrate was used and the pretreatment was only immersion in ion exchange water.
As a result, a NiP plating thin film and a NiB plating thin film could not be formed.

(Comparative Example 2)
In Comparative Example 2, electroless plating was performed and evaluated in the same manner as in Example 1 except that an n-type Si substrate was used and the pretreatment was only immersion in ion exchange water.
As a result, the NiP plating thin film and the NiB plating thin film were considerably clouded (ΔΔ), and as a result, they were poor overall.

(Comparative Example 3)
In Comparative Example 3, except that a p-type Si substrate was used, and the pretreatment liquid was changed to an aqueous solution containing 5 wt% hydrogen peroxide and 7 wt% HCl, and the treatment was performed under conditions of 70 ° C. × 10 minutes. In the same manner as in Example 1, electroless plating was performed and evaluated.
As a result, a NiP plating thin film and a NiB plating thin film could not be formed.

(Comparative Example 4)
In Comparative Example 3, except that an n-type Si substrate was used and the pretreatment liquid was changed to an aqueous solution containing 5 wt% hydrogen peroxide and 7 wt% HCl, and the treatment was performed under conditions of 70 ° C. × 10 minutes. In the same manner as in Example 1, electroless plating was performed and evaluated.
As a result, although the NiP plating thin film could be formed satisfactorily, the NiB plating thin film was severely clouded (ΔΔ), and was poor overall.

(Comparative Example 5)
In Comparative Example 5, a P-type Si substrate was used, and the pretreatment liquid was an aqueous solution containing 5 wt% hydrogen peroxide and 80 wt% sulfuric acid (H ₂ SO ₄ ), and was processed under conditions of 100 ° C. × 10 minutes. Except for the above, electroless plating was performed and evaluated in the same manner as in Example 1. As a result, a NiP plating thin film and a NiB plating thin film could not be formed.

(Comparative Example 6)
In Comparative Example 6, an n-type Si substrate was used, and the pretreatment liquid was an aqueous solution containing 5 wt% hydrogen peroxide and 80 wt% sulfuric acid (H ₂ SO ₄ ), and was processed under conditions of 100 ° C. × 10 minutes. Except for the above, electroless plating was performed and evaluated in the same manner as in Example 1. As a result, a NiP plating thin film and a NiB plating thin film could not be formed.

(Comparative Example 7)
In Comparative Example 7, a p-type Si substrate was used, and the pretreatment liquid was an aqueous solution containing 1.5 wt% hydrogen fluoride (Hf), and the treatment was performed under the conditions of 25 ° C. × 10 minutes. Similarly, electroless plating was performed and evaluated. As a result, a NiP plating thin film and a NiB plating thin film could not be formed.

(Comparative Example 8)
In Comparative Example 8, an n-type Si substrate was used, the pretreatment liquid was an aqueous solution containing 1.5 wt% hydrogen fluoride (Hf), and the treatment was performed under the conditions of 25 ° C. × 10 minutes. Similarly, electroless plating was performed and evaluated. As a result, a NiP plating thin film and a NiB plating thin film could not be formed.

As described above, impurities on the silicon wafer surface, for example, metal ions such as Na ⁺ , Li ⁺ and K ⁺ , ionic contaminants such as F ⁻ , Cl ⁻ and SO ₄ ⁻ ions, organic contaminants, Fe, Impurities such as heavy metals such as Ni and Cr, noble metals such as Au and Ag, alkaline earth metals, carbon (C), silica and alumina can be effectively removed or reduced for activation. In particular, when such a silicon wafer is a mixture of n-type semiconductor and p-type semiconductor, it can be applied to subsequent electroless Ni or Ni alloy plating after the treatment with this cleaning solution, and uniform electroless plating can be performed. Since it has an excellent effect that it can be performed, it is extremely useful for manufacturing a transistor electrode in which an n-type semiconductor and a p-type semiconductor are mixed, such as a source and drain electrode such as an FET.

Claims (6)

  A pretreatment liquid for performing electroless plating of nickel or a nickel alloy on a semiconductor wafer in which an n-type semiconductor and a p-type semiconductor are mixed, the pretreatment liquid comprising hydrogen peroxide water, ammonia water and / or water A pretreatment solution for electroless plating, which is an aqueous solution comprising tetramethylammonium oxide (TMAH).   The pretreatment liquid according to claim 1, wherein hydrogen peroxide is 0.1 to 10.0 wt%, ammonia is 0.1 to 10.0 wt%, and TMAH is 0.5 to 8.0 wt%. Pretreatment solution for electroless plating.   An electroless method comprising: forming a layer of nickel or a nickel alloy on a semiconductor wafer after cleaning a semiconductor wafer in which an n-type semiconductor and a p-type semiconductor are mixed using the pretreatment liquid according to claim 1. Plating method.   4. The electroless plating method according to claim 3, wherein a nickel or nickel alloy layer having a thickness of 20 to 100 nm is formed.   The electroless plating method according to claim 4, wherein the nickel alloy layer is NiP or NiB.   The semiconductor device manufactured by the electroless-plating method as described in any one of Claims 3-5.