WO2007049435A1

WO2007049435A1 - Semiconductor wafer manufacturing method and semiconductor wafer cleaning method

Info

Publication number: WO2007049435A1
Application number: PCT/JP2006/319840
Authority: WO
Inventors: Youji Ikeuchi; Takeme Sakai
Original assignee: Shin-Etsu Handotai Co., Ltd.
Priority date: 2005-10-26
Filing date: 2006-10-04
Publication date: 2007-05-03
Also published as: JP2007123383A

Abstract

A semiconductor wafer manufacturing method is provided with at least a slicing step for cutting out a thin-board-like wafer from a semiconductor ingot, a planarizing step for planarizing the wafer, an etching step for removing process distortion from the wafer, and a polishing step for polishing the wafer. The semiconductor wafer manufacturing method and a semiconductor wafer cleaning method are characterized in that the wafer is cleaned with a cleaning solution containing oxygenated water, citric acid and sodium hydroxide, after the polishing step. Thus, metal impurities adhered on the wafer after the polishing step can be efficiently removed.

Description

Specification

Method for manufacturing semiconductor wafer and method for cleaning semiconductor wafer

Technical field

TECHNICAL FIELD [0001] The present invention relates to a cleaning method performed in a process of manufacturing a semiconductor wafer such as silicon, and more particularly to a method of effectively removing metal contaminants adhering during a process of manufacturing a semiconductor substrate (wafer). . Background art

[0002] In the manufacture of semiconductor devices, the presence of fine particulate contaminants on the wafer surface of the wafer itself may adversely affect the performance characteristics of the device. The semiconductor substrate (UENO) used for semiconductor devices is manufactured by processing ingot blocks grown mainly by the pulling method (Chiyoklarski method, CZ method) into a mirror-like thin plate. The machining process mainly includes a slicing process for slicing an ingot block in a wafer shape, a chamfering process for chamfering the outer periphery of the sliced wafer, and the chamfered wafer is flattened by lapping or surface grinding. There are a flattening process, an etching process for removing the processing distortion of the flattened wafer, and a polishing process for polishing one or both surfaces of the etched wafer. Furthermore, it has a heat treatment process, inspection process, and various cleaning processes.

Conventionally, in a polishing step of polishing one side of a wafer, one side of the wafer to be polished is fixed to a turntable using wax, and the other side is polished. After this polishing process, in order to remove wax adhering to the wafer and particles adhering to the cake, an oxidizing agent such as hydrogen peroxide or hydrogen peroxide or ozone and sodium hydroxide or hydroxide Sequentially using a base such as potassium salt was washed at the same time (see Japanese Patent Publication No. 8-213356).

[0004] However, such a cleaning method has a problem in that metal impurities attached to the wafer surface cannot be sufficiently removed, which may adversely affect device performance characteristics required in recent years. Disclosure of the invention

The present invention has been made in view of such problems, and provides a semiconductor wafer manufacturing method and cleaning method that can efficiently remove metal impurities attached to the wafer after the polishing step. It is for the purpose.

[0006] The present invention has been made to solve the above-described problems. At least, a slicing step of cutting out a thin plate-like wafer from a semiconductor ingot, a flattening step of flattening the wafer, and a processing of the wafer In a method for manufacturing a semiconductor wafer, comprising: an etching process for removing distortion; and a polishing process for polishing the wafer. The wafer is washed with a hydrogen peroxide solution, a hydrogen peroxide solution, a citrate solution, and a sodium hydroxide solution after the polishing step. Provided is a method for producing a semiconductor wafer, characterized by washing with a clean solution.

[0007] In this way, if the wafer is washed with a cleaning solution containing hydrogen peroxide water, citrate and sodium hydroxide after the polishing step, the wax adhering to the wafer or adhering during processing. The metal impurities and particles that have been removed can be sufficiently removed, and in particular, the removal efficiency of Ni can be dramatically improved.

[0008] In this case, in the polishing step, a wafer to be polished can be attached to a glass plate using wax to perform one-side polishing.

[0009] Thus, in the above polishing step, when the wafer to be polished is affixed to a glass plate using wax, the wax adhered to the wafer in the polishing step is used. It is also effective for removing metal impurities and particles adhering during processing.

[0010] Further, it is preferable to perform RCA cleaning after cleaning with the cleaning solution containing the hydrogen peroxide solution, citrate, and sodium hydroxide.

[0011] As described above, if RCA cleaning is performed after cleaning with the cleaning solution containing the hydrogen peroxide solution, citrate, and sodium hydroxide, metal impurities and particles can be further reduced.

In this case, the semiconductor wafer to be manufactured can be a silicon wafer.

[0013] If the semiconductor wafer to be manufactured as described above is a silicon wafer, it is used in a large amount. It is possible to produce clean and high-quality silicon wafers with reduced metal impurities and particles on the surface of the silicon wafer.

[0014] Further, the present invention provides a semiconductor wafer cleaning method, characterized in that the semiconductor wafer is cleaned with a cleaning solution containing hydrogen peroxide water, citrate and sodium hydroxide. provide.

[0015] With such a cleaning method, the wax adhering to the wafer and the metal impurities and particles adhering during the processing can be sufficiently removed, and in particular, the Ni removal efficiency is dramatically improved. can do.

[0016] In this case, the cleaning can be performed after the wafer is attached to the glass plate using wax and polished on one side.

[0017] When the wafer to be polished is affixed to a glass plate using wax and polishing is performed on one side, the present invention relates to the wax adhering to the wafer in the polishing process, metal impurities and particles adhering during processing. It is effective to sufficiently remove

[0018] In this case, it is preferable to perform RCA cleaning after cleaning with the cleaning solution containing the hydrogen peroxide solution, citrate and sodium hydroxide.

[0019] Thus, metal impurities and particles can be further reduced by performing RCA cleaning after cleaning with the cleaning solution containing the hydrogen peroxide solution, citrate, and sodium hydroxide.

In this case, the semiconductor wafer can be a silicon wafer.

If the semiconductor wafer to be cleaned is a silicon wafer in this way, it is possible to obtain a clean and high-quality silicon wafer in which metal impurities and particles on the surface of the silicon wafer used in large quantities are reduced. it can.

[0022] As described above, according to the present invention, after the polishing process, the wafer is washed with a cleaning solution containing hydrogen peroxide solution, citrate and sodium hydroxide, so that the wax adhering to the wafer is reduced. Metal impurities and particles adhering to the cake can be sufficiently removed, and in particular, Ni removal efficiency can be dramatically improved. As a result, a clean and high quality wafer can be obtained. Brief Description of Drawings

[0023] FIG. 1 is a schematic diagram for explaining an example of a semiconductor wafer manufacturing method and a cleaning method of the present invention.

[Fig. 2] A graph showing the relationship between the concentration of citrate in the cleaning solution and the concentration of Ni on the wafer surface.

FIG. 3 is a graph showing the results of measuring the Ni concentration on the surface of the wafers of the example and the comparative example.

FIG. 4 is a graph showing the results of measuring the number of particles on the surface of the wafers of the example and the comparative example.

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] Hereinafter, the present invention will be described in more detail. The present invention is not limited to these.

[0025] As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the wafer is washed with a cleaning solution containing hydrogen peroxide solution, hydrogen peroxide solution, citrate solution and sodium hydroxide solution after the polishing step. The inventors have conceived that the efficiency of removing Ni adhering to wafers can be dramatically improved by cleaning, and the present invention has been completed.

That is, the semiconductor wafer manufacturing method of the present invention includes at least a slicing step of cutting a thin plate-like wafer from a semiconductor ingot, a flattening step of flattening the wafer, and an etching step of removing processing distortion of the wafer. And a polishing process for polishing the wafer, wherein after the polishing process, the wafer is cleaned with a cleaning solution containing a hydrogen peroxide solution, a hydrogen peroxide solution and a sodium hydroxide solution. It is characterized by.

Here, FIG. 1 is a schematic view for explaining an example of a method for manufacturing and cleaning a semiconductor wafer according to the present invention.

First, a silicon single crystal ingot pulled up by the Chiyoklarsky method or the like is sliced and processed into a thin disc-shaped woofer (slicing process, Fig. L (a)).

[0028] Subsequently, the wafer is mechanically ground (lapping) in order to remove the work-affected layer induced on the wafer surface by cutting in the slicing process and to flatten the wafer. (Flatting process, Fig. 1 (b)). This flattening may be performed by surface grinding or double-sided grinding.

[0029] Further, the wafer is etched in order to remove the processing distortion generated in the wafer surface layer in the above process (etching process, FIG. 1 (c)).

Next, in order to further flatten the surface of the etched wafer, a polishing step for polishing the wafer is performed (FIG. 1 (d)). The polishing method is not particularly limited, and the power that can be applied to polishing using a double-sided polishing plate. In particular, the wafer to be polished is affixed to a glass plate using wax, and the wafer surface is polished while rotating the glass plate. One side can be polished by sliding against the cloth while pressing.

[0031] The process up to this point is not particularly different from the conventional method. In addition to this, some processes such as chamfering 'cleaning' and heat treatment may be added. However, various conventional processes can be employed.

[0032] Next, the polished wafer is cleaned with a cleaning solution containing hydrogen peroxide solution, hydrogen peroxide solution, and sodium hydroxide solution (FIG. 1 (e)).

[0033] As described above, the wafer is washed with a cleaning solution containing hydrogen peroxide solution, hydrogen peroxide solution, and citrate solution and sodium hydroxide solution, so that the wax adhering to the wafer in the polishing process or Adhering metal impurities and particles can be sufficiently removed, and in particular, the efficiency of removing Ni adhering to the wafer surface can be dramatically improved.

Next, the wafer is rinsed with pure water to remove the cleaning solution (FIG. 1 (f)).

[0035] Next, RCA cleaning is performed as necessary (Fig. 1 (g)). This RCA cleaning is not particularly limited as long as conventional RCA cleaning is adopted. For example, as shown in Fig. 1, SC1 cleaning, rinsing, SC2 cleaning, and rinsing can be performed in this order. This mixed solution of ammonia and hydrogen peroxide used for SC1 cleaning is 29 wt% NH: 30 wt% H 2 O: H 0 = 1: 1: 5 (body

3 2 2 2

The liquid temperature can be 80 ° C. Also, the hydrochloric acid / hydrogen peroxide solution mixed solution used for SC2 cleaning is 30 wt% HC1: 30 wt% H 2 O: H 0 = 1: 1: 5 (

2 2 2

The liquid temperature can be 80 ° C. As shown in Fig. 1, after SC1 cleaning and SC2 cleaning, it is desirable to rinse with pure water to remove the cleaning solution. [0036] After the RCA cleaning, the wafer is dried (FIG. 1 (h)). The drying method is not particularly limited, but for example, IPA drying can be performed.

A semiconductor wafer can be obtained by the above manufacturing method and cleaning method.

[0037] It should be noted that RCA cleaning can be omitted in the above manufacturing method and cleaning method. However, RCA cleaning can reduce metal impurities and particles.

[0038] Further, if silicon wafers are manufactured by the above manufacturing method and cleaning method, metal impurities and particles are reduced, and in particular, Ni adhering to the wafer surface is greatly removed. You can get silicon wafers.

[0039] The mixing ratio of the cleaning solution containing the hydrogen peroxide solution, citrate and sodium hydroxide is not particularly limited. In the above manufacturing method and cleaning method, the inventors changed the concentration of citrate in the cleaning solution containing hydrogen peroxide solution, citrate, and sodium hydroxide to clean the wafer after the polishing step. After drying, the amount of Ni deposited on each wafer surface was recovered with vaporized hydrofluoric acid (VPD: Vapor Phase Decomposition) and measured by ICPMS (Inductively Coupled Plasma Mass Spectrometry). The results are shown in Fig. 2. At this time, the composition ratio of the cleaning solution other than citrate is 10 wt% NaOH: 30 wt% H 2 O: H 0 = 1: 1: 250 (

2 2 2

Volume ratio). As is apparent from Fig. 2, the removal efficiency of Ni is dramatically improved by adding citrate to the cleaning solution compared to NaO H + H O + H O alone.

2 2 2

Recognize. The 10 weight ^_0/0 NaOH: 30 weight ⁰ / oH O: the ratio of HO 1~50: 1~50: 1~

2 2 2

A force of similar experiment was obtained, and almost the same result was obtained. In addition, the concentration of citrate was almost the same as when 10% or 30% was added, but several%. The lower limit is preferably 10 ppm or more, more preferably 10 ppm or more, as shown in FIG. The liquid temperature can be selected from about 10 to 90 ° C.

[0040] As described above, the wafer adhered to the wafer or the metal adhered during processing by washing the wafer with a cleaning solution containing peroxy hydrogen water and citrate and sodium hydroxide after the polishing step. Impurities and particles can be removed sufficiently, and in particular, the removal efficiency of Ni on the wafer surface can be dramatically improved. This makes it clean and high quality You can get quality wafers.

[0041] Examples of the present invention will be described below, but the present invention is not limited thereto. (Example 1)

First, a silicon single crystal ingot pulled up by the Chiyoklarsky method was sliced and processed into a thin disk-shaped uno (slicing process, Fig. 1 (a)).

[0042] After chamfering the periphery of the wafer, the wafer is then mechanically ground to remove the work-affected layer induced on the wafer surface by cutting in the slicing process and to flatten the wafer. (Lapping) (flattening process, Fig. 1 (b)).

[0043] Further, the wafer was etched in order to remove the processing distortion generated in the wafer surface layer in the above process (etching process, FIG. 1 (c)).

Next, as a polishing process, the etched wafer is affixed to a glass plate using wax and polished on one side (FIG. 1 (d)), and has a diameter of 200 mm, conductivity type p-type, resistivity.

A mirror-polished CZ wafer with 5-20Ω'cm was obtained.

[0044] Next, the CZ wafer was washed with a washing solution containing hydrogen peroxide solution, citrate and sodium hydroxide for 2 minutes (FIG. 1 (e)). At this time, the temperature of the cleaning solution is 55 ° C.

The composition ratio is 10 weight. / ₀ NaOH: 30 wt% HO: 10 wt% citrate: H 0 = 1: 1:

2 2 2

1: 250 (volume ratio).

Thereafter, rinsing was performed with pure water at room temperature for 2 minutes (Fig. L (f)).

[0045] Next, RCA cleaning was performed (Fig. 1 (g)). First, as SC1 cleaning, 29% NH: 30%

3 Quantity ⁰ / oH O: H 0 = 1: 1: 5 (volume ratio) mixing ratio of ammonia monoperoxide and hydrogen water

2 2 2

The wafer was washed for 2 minutes using the solution at a temperature of 80 ° C. Thereafter, rinsing was performed with pure water at room temperature for 2 minutes. Furthermore, as SC2 cleaning, 30 wt% HC1: 30 wt% H 2 O: H 0 =

2 2 2

The wafer was washed for 2 minutes using a mixed solution of hydrochloric acid and hydrogen peroxide in a mixing ratio of 1: 1: 5 (volume ratio) at a liquid temperature of 80 ° C. Thereafter, rinsing was performed with pure water at room temperature for 2 minutes.

Finally, IPA drying was performed for 2 minutes to obtain silicon wafer (Fig. 1 (h)).

[Example 2] Under the same conditions as in Example 1, a slicing step, a flattening step, an etching step, and a polishing step were performed to obtain a mirror-polished CZ wafer having a diameter of 200 mm, a conductivity type p-type, and a resistivity of 5 to 20 Ω'cm. .

[0047] After that, cleaning and rinsing with a cleaning solution containing hydrogen peroxide solution, citrate and sodium hydroxide were performed under the same conditions as in Example 1.

Finally, silicon wafers were obtained by IPA drying for 2 minutes without RCA cleaning.

[0048] (Comparative Example 1)

Under the same conditions as in Example 1, a slicing step, a flattening step, an etching step, and a polishing step were performed to obtain a mirror-polished CZ wafer having a diameter of 200 mm, a conductivity type p-type, and a resistivity of 5 to 20 Ω'cm. .

[0049] This was carried out except that the wafer was cleaned using a cleaning solution containing peracid-hydrogen water and sodium hydroxide-sodium (not containing taenoic acid) as the cleaning solution after the polishing process. Rinsing, RCA cleaning, and drying were performed under the same conditions as in Example 1 to obtain silicon wafers.

[0050] (Comparative Example 2)

After the polishing process, RCA cleaning and drying were performed under the same conditions as in Example 1 without cleaning with a cleaning solution containing hydrogen peroxide solution, hydrogen peroxide solution, and sodium hydroxide solution. Obtained.

[0051] (Evaluation of silicon wafer)

For each of the silicon wafers obtained in the above examples and comparative examples, the Ni concentration on the wafer surface was measured by ICPMS using the VPD method. Figure 3 shows the results obtained. Sarakuko, 24 wafers each using measuring instrument CR-81 (made by ADE) The number of particles on the wafer surface was measured. The average value of the results obtained is shown in Fig. 4.

As is clear from FIG. 3, in the example washed with a cleaning solution containing a hydrogen peroxide solution, a citrate acid and a sodium hydroxide solution after the polishing step, the Ni removal effect was compared with the comparative example. It can be seen that the rate has improved dramatically. In Example 1 where RCA cleaning is combined with this cleaning, the Ni concentration is further reduced.

In addition, as is clear from FIG. 4, in the example where the cleaning process was performed with a cleaning solution containing hydrogen peroxide solution, citrate, and sodium hydroxide after the polishing process, the particles were smaller than in the conventional cleaning method. It turns out that it is decreasing. In Example 1 where RCA cleaning is combined with this cleaning, it can be seen that particles are further reduced.

As described above, the wafer obtained by the semiconductor wafer manufacturing method and the cleaning method of the present invention has dramatically reduced metal impurities, particularly Ni, and further reduced particles. It could be confirmed.

Note that the present invention is not limited to the above embodiment. The above embodiment is an exemplification, and the present invention has the same configuration as that of the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present embodiment. It is included in the technical scope of the invention.

For example, it goes without saying that the manufacturing method and cleaning method of the present invention can be applied to various semiconductor wafers such as compound semiconductors. The cleaning method of the present invention can be applied without being limited to cleaning of a wafer after polishing because metal impurities such as Ni can be remarkably reduced.

[0057] In the above description, a case where a wafer to be polished is affixed to a glass plate using wax to perform polishing on one side has been described. However, the present invention is not limited to this, and double-side polishing or a template is used. It can also be applied to polishing.

Claims

The scope of the claims

[1] At least a slicing step of cutting a thin wafer from a semiconductor ingot, a flattening step of flattening the wafer, an etching step of removing processing distortion of the wafer, and a polishing step of polishing the wafer A method for manufacturing a semiconductor wafer comprising: cleaning a wafer with a cleaning solution containing hydrogen peroxide water, citrate and sodium hydroxide after the polishing step. .

[2] The method for producing a semiconductor wafer according to [1], wherein the wafer to be polished in the polishing step is bonded to a glass plate using wax to perform one-side polishing.

[3] The method for producing a semiconductor wafer according to claim 1 or 2, wherein RCA cleaning is performed after cleaning with the cleaning solution containing the hydrogen peroxide solution, citrate, and sodium hydroxide. .

[4] The method for producing a semiconductor wafer according to any one of [1] to [3], wherein the semiconductor wafer to be produced is a silicon wafer.

[5] A method for cleaning a semiconductor wafer, wherein the semiconductor wafer is cleaned with a cleaning solution containing a hydrogen peroxide solution, citrate and sodium hydroxide.

6. The method for cleaning a semiconductor wafer according to claim 5, wherein the cleaning is performed after the wafer is attached to a glass plate using wax and polished on one side.

[7] The half of claim 5 or 6, wherein RCA cleaning is performed after cleaning with a cleaning solution containing the hydrogen peroxide solution, citrate, and sodium hydroxide. Cleaning method for conductor wafers. The method for cleaning a semiconductor wafer according to claim 5, wherein the semiconductor wafer is a silicon wafer.