JP2978358B2 - Electrode plate for etching - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode plate for etching such as reactive ion etching (RIE) used for etching a silicon wafer.

[0002]

2. Description of the Related Art Conventionally, as an RIE electrode plate (cathode plate), a carbon material such as a glassy carbon material or a single crystal silicon material has been used.

[0003] The glassy carbon material has excellent characteristics such as light weight and high strength, high heat resistance, high electrical and thermal conductivity, and high corrosion resistance, similarly to a general carbon material. Therefore, it has been widely used as an electrode plate in a semiconductor wafer etching process.

However, the glassy carbon material has some dusting properties, and depending on etching conditions, the inside of the apparatus may be contaminated, resulting in deterioration of various characteristics of the semiconductor wafer. In this case, the yield of the semiconductor wafer naturally decreases.

Therefore, in recent years, single-crystal silicon materials with little dust contamination have been increasingly used as electrode plates for etching.

[0006]

The single crystal silicon material is obtained by pulling a silicon ingot. The electrode plate for etching is manufactured by slicing a cylindrical ingot into a plate shape.

A conventional RIE cathode plate has a shape in which several mounting stopper holes are formed near the outer periphery of a single-crystal silicon sliced into a plate shape, and a large number of fine through holes are provided in a central shower portion. ing. The diameter of the shower section needs to be 8 inches or more for an electrode plate for an 8-inch wafer. Therefore, the diameter of the electrode plate needs to be at least 8 inches + several inches.

As described above, the diameter of an electrode plate for an 8-inch wafer is usually 10 to 12 inches. However, pulling a large-diameter silicon single crystal ingot is technically difficult and costly. In particular, ingots of 10 to 12 inches are very expensive and difficult to obtain. As the diameter of the ingot increases, the height of the ingot decreases, and a large number of electrode plates cannot be obtained from a single ingot. This also contributes to an increase in cost.

In recent years, in the field of semiconductors, the diameter of wafers has been increasing and the demand for 8-inch wafers has been increasing. For this reason, it is desired to provide an inexpensive 8-inch wafer electrode plate.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an electrode plate for etching such as reactive ion etching which is inexpensive and high performance without fear of dust contamination. I have.

[0011]

SUMMARY OF THE INVENTION The present invention comprises a circular disk portion made of single crystal silicon and having a large number of fine through holes, and a ring portion disposed outside the disk portion and having a mounting hole. The gist of the present invention is an electrode plate for reactive ion etching, wherein the plate portion and the ring portion are integrally and conductively joined by silicon.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an example of an electrode plate for reactive ion etching (RIE) according to the present invention, and FIG. 2 is a top view thereof.

The RIE cathode plate 10 is generally disk-shaped, and comprises a central disk portion 11 and a ring portion 12 disposed outside the disk portion.

The disk portion 11 is made of single crystal silicon, and a large number of small through holes 13 are densely formed in the entire disk portion. The area becomes a shower section. However, in FIGS. 1 to 5, only a part of the through-hole is shown in an emphasized manner.
The ring portion 12 is made of poly (polycrystalline) silicon.

The through holes 13 serve to uniformly flow the etching gas to uniformly etch the wafer. The through-holes 13 are arranged at regular intervals over the top, bottom, left, and right, but may be arranged at random with good balance. It is preferable that the arrangement density of the through holes 13 is about 2 to 15 holes / cm ² . Therefore, when the diameter of the disk portion 11 is 8 inches, about 500 to 3000 through holes are formed. The diameter of each through hole is preferably set to 0.5 to 0.8 mm. By forming the through holes in this way, good etching can be performed.

In the case of an electrode plate for an 8-inch wafer, it is sufficient that the outer diameter of the disk portion 11 is 8 inches or slightly larger than 8 inches. That is, it can be set to about 200 to 220 mm.

The thickness of the disk portion 11 is, for example, 2-6.
mm. By setting the wall thickness in this manner, sufficient mechanical strength is obtained, and workability of the through hole is also ensured.

A ring portion 12 is integrally and conductively joined around the disk portion 11 with silicon. The outer periphery of the disk portion 11 and the inner periphery of the ring portion 12 are tapered. The two tapered surfaces can be combined by a mechanical, thermal, or chemical method, but in any case, it is important to electrically connect them so as to function sufficiently as an electrode plate.

In this embodiment, the tapered surface on the outer periphery of the disk portion 11 and the tapered surface on the inner periphery of the ring portion 12 are conductively bonded by a conductive Si layer formed by reacting and sintering Si powder. I have.

The formation of a large number of small through holes 13 in the disk portion 11 may be performed before or after the connection with the ring portion 12.

When the through hole 13 is formed at one time,
It is preferably performed after the joining. Thereby, excellent dimensional accuracy is obtained.

The outer diameter of the ring portion 12 can be set to 10 to 12 inches. The ring portion 12 can be made of poly (polycrystalline) silicon or glassy carbon.

The ring portion 12 has four large holes 14 formed therein. The hole 14 is intended to be attached to the RIE apparatus, and has a two-stage shape having a small diameter portion and a large diameter portion.

Next, a method of manufacturing the RIE cathode plate of FIG. 1 will be described with reference to FIG. FIG.
It is an assembly drawing of a cathode plate for IE.

The disk portion 11 is manufactured from an 8-inch silicon single crystal ingot material. That is, a large number of through holes 13 are formed in a disk obtained by slicing an ingot material, and the outer peripheral surface is processed into a tapered shape. The 8-inch ingot material is easier to obtain and less expensive than the large-diameter ingot material of 10 to 12 inches. Therefore, the cathode plate of the present invention is also effective for processing a 5 to 6 inch wafer, but the cost reduction effect becomes extremely large particularly in the case of an 8 inch cathode plate.

The ring portion 12 is formed of a polysilicon plate or glassy carbon. When it is made of glassy carbon, for example, it is formed by shaping a raw material into a predetermined shape, curing it, firing it, and finally purifying it. At this time, the impurity content of the ring portion 12 made of glassy carbon is suppressed to 3 ppm or less.

After the disk portion 11 and the ring 12 are fitted together, they are placed in a furnace, and the surface is coated with Si by flowing silicon tetrachloride and hydrogen. Thereby, the disk part 11 and the ring part 12 are substantially joined. In this case,
It is preferable that the diameter of each of a large number of small through holes 13 formed in advance in the disk portion 11 is previously increased by the amount of the Si film. Alternatively, the mask may be coated with Si by masking only a large number of through-holes except for the outer periphery of the ring.

FIG. 4 shows the disk portion 11 based on the above embodiment.
3 shows a RIE cathode plate in which the surface of a ring portion 12 is coated with Si.

The formation of the through-hole 13 may be performed before or after the joining of the disk portion 11 and the ring portion 12 as described above. In order to obtain excellent dimensional accuracy of the through-hole 13, it is preferable that the through-hole 13 is joined.

Next, another embodiment of the present invention will be briefly described with reference to FIGS.

The RIE cathode plate 20 shown in FIG.
The outer periphery of the disk portion 21 and the inner periphery of the ring portion 22 are paired with each other in a key shape (stepped shape). Other configurations are the same as those of the embodiment of FIGS.

In the embodiment shown in FIG. 6, the boundary between the disk portion 31 and the ring portion 32 is of a straight type. In this case, the joining of the disk portion 31 and the ring portion 32 is performed by conductive joining as in the embodiment of FIG.

[0033]

The etching electrode plate of the present invention comprises a disk portion made of single crystal silicon and having a large number of fine through holes, and a ring portion disposed outside the disk portion and having a mounting hole, Since the disk portion and the ring portion are integrally and conductively joined by silicon, there is no risk of dust and contamination, and the device can be manufactured at low cost.

The present invention is not limited to the above embodiment. For example, the annular ring portion does not need to be integral, and may have a divided structure in terms of material removal. Further, the electrode plate of the present invention can be applied to the entire etching process.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an electrode plate for RIE according to the present invention.

FIG. 2 is a top view of FIG. 2;

FIG. 3 is an assembly view of FIG. 1;

FIG. 4 is a sectional view showing another embodiment of the present invention.

FIG. 5 is a sectional view showing still another embodiment of the present invention.

FIG. 6 is a sectional view showing still another embodiment of the present invention.

[Explanation of symbols]

 10, 20, 30 RIE cathode plate 11, 21, 31 Disk portion 12, 22, 32 Ring portion 13, 23, 33 Through hole 14, 24, 34 Mounting hole

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/3065 C23F 4/00

Claims (1)

(57) [Claims] A disk portion (11, 12) made of single crystal silicon and having a large number of fine through holes (13, 23, 33).
1, 31) and a ring portion (12, 22, 32) disposed outside the disk portion (11, 21, 31) and having a mounting hole (14, 24, 34). 11,2
1, 31) and the ring part (12, 22, 32) are silicon
An electrode plate for etching characterized in that the electrode plate is integrally and conductively joined by the above.