JP3416190B2 - Anodizing apparatus and method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anodizing apparatus and anodizing method for processing a semiconductor substrate.

[0002]

2. Description of the Related Art By anodizing a semiconductor substrate,
There is a technique of performing electrolytic polishing. Further, it was discovered that porous silicon is formed by anodizing a silicon wafer in an HF liquid (A. Ihril: Be.
ll Syst. Tech. J. , 35 (1956),
333. ).

Porous silicon contains many elongated pores of about 1 to 10 nm, and the volume including the pores is 1 cm ^3.
The surface area per hit ranges from 200 to 800 m ² (Hiroshi Sugiyama,
Osamu Irito: Bulletin of the Japan Institute of Metals, Vol. 30, No. 4 (1
991)). It has been discovered that this porous silicon emits light when a voltage is applied, and the utility value of the porous silicon itself has been found. It is also applied to SOI substrate technology by utilizing the property that silicon can be epitaxially grown on porous silicon.

In this substrate manufacturing method, an epitaxial layer is first grown and then bonded to an insulating substrate, and silicon on the porous side is removed by polishing and etching.
Next, since porous silicon has a large surface area and therefore has a higher etching rate than bulk silicon, only the porous layer is etched to leave a thin film of single crystal silicon on the insulating substrate (Patent Pending
Inventor: Takao Yonehara Application: August 3, 1990 Japanese Patent Application No. 2
-206548, JP-A-5-21338).

FIG. 4 shows a schematic view of a conventional anodizing bath.
In this conventional example, an example in which porous silicon is formed by anodization will be described. In the figure, + electrode 4
The formation is performed by passing an electric current between the 01 and-electrodes 402. Positive electrode 401 and negative electrode 402 are bolts 40
It is being fixed to the chemical conversion tanks 405 and 406 by 3,404, respectively. Sealing portions 407 are provided at 405 and 406 to sandwich and hold the silicon wafer 408 to prevent the liquid in the tank from flowing out. An HF solution is injected into the upper tank 409 to make the upper surface of the silicon wafer 408 porous. At this time, in order to prevent bubbles from adhering to the silicon surface and make the HF concentration and reaction rate uniform, the injection port 4
The HF liquid is injected from 10 and the HF liquid is discharged from the discharge port 411 and circulated. Further, the mesh 412 is arranged so that the flow of the HF liquid becomes uniform. The potential on the back surface of the silicon wafer 408 can be obtained by filling the lower bath 413 with the electrolytic solution.

The + electrode 401 is directly attached to the silicon wafer 408.
However, in order to prevent metal contamination of the wafer, electrical contact is obtained through an electrolytic solution in this example.

[0007]

However, in the conventional example shown in FIG. 4, when the electrolytic solution 413 in the lower part of the tank is an HF solution, the elution of the electrode into the solution was confirmed even when the + electrode was Pt. Further, an experiment was conducted using the electrolytic solution 413 with dilute sulfuric acid, and in this case as well, elution of the Pt electrode was confirmed.

Since the metal element dissolved in the electrolytic solution 413 is deposited on the back surface of the wafer 408 by the electric field, there is a problem to be solved that the metal contamination of the wafer is greatly affected.

Incidentally, the elution of Pt from the electrode was not confirmed as a result of the experiment.

[Object of the Invention] An object of the present invention is to provide an anodizing apparatus capable of preventing contamination of a wafer, and particularly to prevent contamination due to electrode components dissolved in an electrolytic solution.

[0011]

Therefore, the present invention comprises a tank for containing an electrolyte solution, and a positive electrode and a negative electrode for passing an electric current through the electrolyte solution, wherein the positive electrode and the negative electrode are provided. In the anodizing device for performing a chemical conversion treatment on the silicon wafer disposed between the silicon wafer and the positive electrode, a conductive partition other than metal is provided between the silicon wafer and the positive electrode to isolate the silicon wafer from the positive electrode. Moreover, the surface of the silicon wafer on the positive electrode side does not come into contact with metal. Further, the present invention comprises a tank for containing an electrolyte solution, a positive electrode and a negative electrode for flowing an electric current through the electrolyte solution, and a cover disposed between the positive electrode and the negative electrode. In an anodizing apparatus for subjecting a treated substrate to a chemical conversion treatment, a conductive partition wall other than metal is provided between the treated substrate and the positive electrode to separate the treated substrate from the positive electrode. In addition, the conductive partition covers the surface of the positive electrode.
It is assumed that the conductive partition and the positive electrode are in contact with each other. Furthermore, the present invention comprises a tank for containing an electrolyte solution, and a positive electrode and a negative electrode for passing an electric current through the electrolyte solution, and a cover disposed between the positive electrode and the negative electrode. In the anodizing apparatus for subjecting the treated substrate to the chemical conversion treatment, the partition wall made of a silicon member covers the surface of the positive electrode.
It is supposed to be in contact with the non-treated surface of the substrate to be treated so as to cover it.

The present invention uses an anodizing apparatus comprising a tank for containing an electrolyte solution, and a positive electrode and a negative electrode for passing an electric current through the electrolyte solution, using the positive electrode and the negative electrode. anodizing method of applying a silicon wafer to a chemical conversion treatment disposed between, arranged conductive partition wall between the positive electrode and the silicon wafer, the Shirikon'u
The chemical conversion treatment is performed in a state where the air and the positive electrode are separated from each other, and the surface of the silicon wafer on the positive electrode side does not come into contact with metal . Still further, the present invention uses an anodizing apparatus comprising a tank for containing an electrolyte solution and a positive electrode and a negative electrode for passing an electric current through the electrolyte solution, using the positive electrode and the negative electrode. In the anodizing method for performing a chemical conversion treatment on the substrate to be treated arranged in between, a conductive partition is arranged between the substrate to be treated and the positive electrode, and the substrate to be treated and the positive electrode are separated from each other, In addition, the chemical conversion treatment is performed in a state where the conductive partition and the positive electrode are in contact with each other. Furthermore, the present invention uses an anodizing apparatus comprising a tank for containing an electrolyte solution and a positive electrode and a negative electrode for flowing an electric current through the electrolyte solution, and using an anodizing device between the positive electrode and the negative electrode. In the anodizing method for performing a chemical conversion treatment on the substrate to be treated arranged in, the chemical conversion treatment is performed in a state where the silicon member is in contact with the non-treated surface side of the substrate to be treated arranged between the positive electrode and the negative electrode. It will be done.

[0013]

According to the present invention, a metal contamination preventing wafer (conductive partition wall) is arranged between the processing wafer and the + side metal electrode, and the processing wafer is directly or through a liquid, Since it does not come into contact with the + side metal electrode, metal contamination of the wafer can be prevented.

[0014]

【Example】

[First Embodiment] FIG. 1 is a schematic view of an anodizing apparatus according to the first embodiment of the present invention. This anodizing apparatus is composed of a + electrode 101, a − electrode 102, a bath lower stage 103, and a bath upper stage 104. A silicon wafer (conductive partition) 106, which is larger in size than the wafer 105 to be formed, is provided on the + electrode 101 so that the electrolytic solution 107 does not directly contact the anode electrode 101. HF in the upper tank
The liquid can be injected to make the upper surface of the silicon wafer 105 porous. The tank is provided with a seal part 108,
Prevents the outflow of liquid.

In this embodiment, the electrolytic solution 107 is the metal electrode 1
Since it does not come into direct contact with 01, the metal does not melt into the electrolytic solution 107, and the metal contamination of the silicon wafer 105 can be prevented.

When the HF liquid is used in the lower part of the tank, the upper surface of the silicon wafer 106 is also chemically formed, so that the bolt 1
The wafer 106 has a structure that can be replaced by removing 09.

[Second Embodiment] In the first embodiment, the effect of the present invention is effective even if the lower liquid tank is not provided. FIG. 2 shows a second embodiment according to the present invention. This anodizing apparatus is composed of a + electrode 201, a − electrode 202, a holder 203, and a liquid tank 204. A silicon wafer (conductive partition) 206 having a size larger than that of the formed wafer 205 is provided on the + electrode 201, and is used as an electrode that contacts the wafer 205 and gives a potential.

The HF liquid is injected into the liquid tank 204 to make the upper surface of the silicon wafer 205 porous. The tank is provided with a seal portion 207 to prevent the liquid from flowing out.

Since the silicon wafer 205 formed in this embodiment does not come into direct contact with the metal electrode 201, metal contamination of the wafer can be prevented.

In this embodiment, the wafer 206 can be replaced by removing the bolt 208.

When electrical contact between the wafer 205 to be formed and the wafer 206 to be an electrode is insufficient, a conductive paste can be provided between them.

[Third Embodiment] FIG. 3 shows a third embodiment of the present invention.
An example of is shown. This anodizing device is + electrode 301,-
Electrode 302, lower tank 303, middle tank 304, upper tank 30
It is composed of 5. The + electrode 301 gives a potential to a wafer (conductive partition) 307 made of the same element as the wafer formed through the electrolytic solution injected into the bath 303. Between the formed wafer 306 and the wafer (conductive partition wall) 307, conduction is established by the liquid injected into the bath 304. The HF solution is injected into the upper stage of the tank, so that the upper surface of the silicon wafer 306 can be made porous. The tank is provided with a seal portion 308 to prevent the liquid from flowing out.

In this embodiment, in addition to the effects obtained in the first embodiment, the liquid injected into the bath 303 is supplied to the wafer 307.
By using a liquid having a good contact property with, for example, a liquid containing a surfactant, the resistance of the wafer 307 and the + electrode 301 can be reduced.
The conduction between can be obtained.

In this embodiment, the wafer 307 can be replaced by removing the bolt 309.

[Fourth Embodiment] In the first, second, and third embodiments, impurities are implanted into the silicon wafers (conductive barrier ribs) 106, 206, and 307 used as electrodes to improve the resistance of the system. It is possible to facilitate the flow of the lower current. By using low resistance substrates (for example, 0.01 Ω · cm) for the silicon wafers 106, 206, and 307, ohmic contact is made between the wafer to be formed, the electrolytic solution, and the + electrode, and the voltage of several volts is applied. It is possible to flow a current of 1 A, and thereby formation can be performed.

Further, since the resistance at the interface between the wafers 106, 206 and 307 dominates the resistance to prevent the formation current, even if a medium or high resistance substrate is used, one or both surfaces can be used. For example, the resistance of the interface can be reduced by doping the impurities by ion implantation. Such wafers 106, 206, or 3
It goes without saying that the effects of the first, second and third embodiments are not impaired even when used for No. 07.

[0027]

As described above, according to the present invention, the wafer to be formed is directly contacted with a wafer as a conductive partition made of the same element to be given an electric potential, or is not in contact with a metal electrode. Since the potential is applied by coming into contact with the conductive liquid, it does not come into direct contact with the anode-side metal electrode, and also does not come into contact with the liquid in contact with the anode-side electrode.

Therefore, the effect of preventing metal contamination of the wafer due to the elution of electrode components can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an anodizing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an anodizing apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram of an anodizing apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram of a conventional anodizing apparatus.

[Explanation of symbols]

101 + electrode 102-electrode 103 lower tank 104 upper tank 105 wafers 106 Silicon wafer 107 Electrolyte 108 Seal part 109 bolt 201 + electrode 202-electrode 203 holder 204 liquid tank 205 wafer 206 Silicon wafer 207 Seal part 208 volts 301 + electrode 302-electrode 303 lower tank 304 middle tank 305 upper tank 306 wafer 307 Silicon wafer 308 Seal part 309 volts 401 + electrode 402-electrode 403 volts 404 bolt 405 lower tank 406 upper tank 407 seal 408 wafer 409 HF liquid 410 HF liquid inlet 411 HF liquid outlet

Claims (34)

(57) [Claims] 1. A silicon wafer provided with a tank for containing an electrolyte solution and a positive electrode and a negative electrode for passing an electric current through the electrolyte solution, the silicon wafer being arranged between the positive electrode and the negative electrode. In the anodizing apparatus for subjecting the silicon wafer and the positive electrode to each other, a conductive partition other than a metal is provided between the silicon wafer and the positive electrode to separate the silicon wafer and the positive electrode from each other. An anodizing device characterized in that the surface of the wafer on the positive electrode side does not come into contact with metal. 2. The anodizing apparatus according to claim 1, wherein the conductive partition wall is arranged in contact with the positive electrode surface so as to cover the surface, and the positive electrode surface is isolated from an electrolyte solution. 3. The anodizing apparatus according to claim 1, wherein the silicon wafer and one surface of the conductive partition are arranged in contact with each other, and the positive electrode and the other surface of the conductive partition are arranged in contact with each other. 4. The anodizing apparatus according to claim 1, wherein the positive electrode and the conductive partition are separated from each other with a conductive liquid interposed therebetween. 5. The anodizing apparatus according to claim 1, wherein the conductive partition wall is made of the same material as the silicon wafer. 6. The anodizing apparatus according to claim 5, wherein impurities for increasing conductivity are added to the surface of the conductive partition. 7. The anodizing apparatus according to claim 1, wherein the conductive partition is a silicon wafer. 8. An anodizing device comprising a tank for containing an electrolyte solution and a positive electrode and a negative electrode for passing an electric current through the electrolyte solution, and using a positive electrode and a negative electrode between the positive electrode and the negative electrode. In the anodization method of subjecting the silicon wafer disposed on the silicon wafer to a chemical conversion treatment, a conductive partition other than metal is disposed between the silicon wafer and the positive electrode, and the silicon wafer and the positive electrode are connected to each other. And the chemical conversion treatment is performed in a state where the surface of the silicon wafer on the side of the positive electrode does not come into contact with a metal. 9. The anodization method according to claim 8, wherein the conductive partition is placed in contact with the positive electrode so as to cover the surface of the positive electrode, and the surface of the positive electrode is isolated from an electrolyte solution. 10. The anodization method according to claim 8, wherein the silicon wafer and one surface of the conductive partition are brought into contact with each other, and the positive electrode and the other surface of the conductive partition are brought into contact with each other. 11. The anodization method according to claim 8, wherein the positive electrode and the conductive partition are separated from each other with a conductive liquid interposed therebetween. 12. The anodization method according to claim 8, wherein the same material as the silicon wafer is used as the conductive partition. 13. The anodization method according to claim 12, wherein impurities are added to the surface of the conductive partition wall to enhance conductivity. 14. The anodization method according to claim 8, wherein a silicon wafer is used as the conductive partition. 15. The anodization method according to claim 8, wherein the silicon wafer is made porous. 16. The anodizing apparatus according to claim 1, wherein the conductive partition wall and the positive electrode are in contact with each other. 17. The anodizing apparatus according to claim 1, wherein the size of the conductive partition is larger than the size of the silicon wafer. 18. The anodization method according to claim 8, wherein the conductive partition and the positive electrode are in contact with each other. 19. The anodization method according to claim 8, wherein the size of the conductive partition wall is larger than the size of the substrate to be treated. 20. An object of treatment, which is provided with a tank for containing an electrolyte solution, and a positive electrode and a negative electrode for passing an electric current through the electrolyte solution, and which is arranged between the positive electrode and the negative electrode. In an anodizing apparatus for subjecting a substrate to a chemical conversion treatment, a conductive partition wall other than metal is provided between the substrate to be treated and the positive electrode, and the substrate to be treated and the positive electrode are separated from each other,
Further, the anodizing device , wherein the conductive partition and the positive electrode are in contact with each other so that the conductive partition covers the surface of the positive electrode. 21. An anodizing apparatus comprising a tank for containing an electrolyte solution and a positive electrode and a negative electrode for passing an electric current through the electrolyte solution, and using a positive electrode and a negative electrode between the positive electrode and the negative electrode. In the anodization method for subjecting the substrate to be treated, which is placed in step 1, to a chemical conversion treatment, a conductive partition wall other than a metal is provided between the substrate to be treated and the positive electrode to separate the substrate to be treated from the positive electrode. Then
Further, the anodization method is characterized in that the chemical conversion treatment is performed in a state where the conductive partition and the positive electrode are in contact with each other so that the conductive partition covers the surface of the positive electrode. 22. The anodizing apparatus according to claim 20, wherein the conductive partition wall and the substrate to be treated are in contact with each other. 23. The anodization method according to claim 21, wherein the conductive partition wall and the substrate to be treated are in contact with each other. 24. The anodizing apparatus according to claim 22, wherein the conductive partition wall is made of silicon. 25. The anodization method according to claim 23, wherein the conductive partition wall is made of silicon. 26. An object of treatment, which is provided with a tank for containing an electrolyte solution, and a positive electrode and a negative electrode for passing an electric current through the electrolyte solution, and which is arranged between the positive electrode and the negative electrode. in the anodizing apparatus for performing chemical conversion treatment to the substrate, shea
Make sure that the partition wall made of recon member covers the surface of the positive electrode.
An anodizing device, which is in contact with the non-treated surface of the substrate to be treated . 27. The anodizing apparatus according to claim 26, wherein the substrate to be processed and the silicon member are horizontally supported. 28. The anodizing apparatus according to claim 26, wherein only the chemical conversion treatment surface side of the substrate to be treated is filled with the electrolyte solution. 29. The anodizing apparatus according to claim 26, wherein the non-treated surface side of the substrate to be treated is separated from the positive electrode. 30. The anodizing apparatus according to claim 26, wherein the non-treated surface side is a positive electrode side. 31. The anodizing apparatus according to claim 26, wherein the non-treated surface side is a surface side which is not made porous. 32. The anodizing apparatus according to claim 26, wherein the silicon member is a silicon wafer. 33. Between the positive electrode and the negative electrode, using an anodizing device comprising a tank for containing an electrolytic solution and a positive electrode and a negative electrode for passing an electric current through the electrolytic solution. anodizing method of applying a chemical conversion process on a target substrate arranged on the partition wall is the made of silicon member
The anodization method, wherein the anodization treatment is carried out in a state of being in contact with the non-treated surface of the substrate to be treated so as to cover the surface of the positive electrode . 34. The anodization method according to claim 33, wherein the non-treated surface is separated from the positive electrode.