JPH0787192B2 - Plasma reaction processor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a plasma reaction processing apparatus used for etching a semiconductor wafer, removing an organic film formed on the wafer surface, and the like.

(Prior Art) In the manufacturing process of a semiconductor integrated circuit, a substrate surface such as a silicon wafer is selectively etched, or an organic film covering the wafer surface is removed as a mask material when selectively etching. As a device for doing so, a reaction processing device utilizing plasma has been conventionally used.

As such a plasma reaction processing apparatus, there are a batch type that simultaneously processes a large number of wafers and a single-wafer processing type that processes each wafer one by one. However, in a batch type reaction processing apparatus, plasma uniformly acts on a large number of wafers. If not, in particular, in the case of ion implantation in which an organic film is formed by leaving a part on the wafer surface and burying ions such as phosphorus and boron at a high speed in the part not covered with the organic film, after the implantation. The organic film of is carbonized or deteriorated, and it takes time to remove the organic film in a batch-type reaction processing apparatus that processes multiple wafers at once, and especially in ion implantation of high current, high dose, etc. Cannot be removed.

Therefore, recently, single-wafer processing type reaction processing devices are becoming mainstream.

As such a single-wafer processing apparatus, a parallel plate type as shown in JP-A-52-113164 and a pair of semi-cylindrical external electrodes as shown in JP-B-54-32740, and, There is an apparatus having a wafer processing unit and a plasma generation unit. As shown in Fig. 4, the parallel plate type reaction treatment device has a bottom plate (10
A bell jar type (hook-bell) chamber (101) is provided on the upper surface of the upper electrode (10).
2) and the lower electrode (103) are arranged, a plasma generating chamber (104) is formed between the upper and lower electrodes (102) and (103), and an exhaust port (105) for vacuuming is formed in the bottom plate (100). is doing. Then, the wafer (W) is placed on the lower electrode (103), the chamber (101) is decompressed through the exhaust port (105), and plasma is generated between the upper and lower electrodes (102) and (103). , The wafer (W) is processed.

Further, as a device having the pair of semi-cylindrical external electrodes and having a wafer processing unit and a plasma generating unit, a plasma ashing device TCA-2300 (hereinafter referred to as Tokyo Ohka Kogyo Co., Ltd.)
There is a TCA type), but the plasma reaction processing apparatus has a pair of semi-cylindrical electrodes (106) and (107) arranged on the upper part of the chamber (101) as shown in FIG. Ten
6) to the high frequency power source and the other to ground, and set the chamber (10
The upper part of 1) is the plasma generation chamber (104), the lower part of the chamber (101) is the plasma reaction processing chamber (108), and the wafer mounting table (109) is arranged from below in the chamber (101). I am facing.

(Problems to be Solved by the Invention) According to the parallel plate type plasma reaction processing apparatus described above, the removal of the organic film can be effectively performed, but since the wafer is set directly in the plasma generation chamber, it exists in the plasma. It may be damaged by ions or charged particles, or the temperature of the wafer itself may rise, resulting in defective products.

Further, according to the TCA type plasma reaction processing apparatus, since the wafer is not set in the plasma generation chamber, damage by ions and charged particles is small, but there is a problem that it takes time to remove or etch the organic film.

Further, all of the above-mentioned single-wafer processing type devices are bottom plates (100)
An exhaust port (105) for vacuuming is formed in the lower part, and this exhaust port (105) is the lower electrode (103) or the table (109).
Since it is located away from, active species such as oxygen radicals that contribute to the reaction flow laterally, which makes it impossible to perform uniform treatment or to prolong the treatment time.

(Means for Solving the Problems) In order to solve the above problems, the plasma reaction processing apparatus according to the present invention is premised on a single-wafer processing type plasma reaction processing apparatus, and an upper part of a bell jar type chamber provided on a bottom plate. A cylindrical upper electrode to which a high frequency is applied is arranged on the outside or inside,
An opening is formed in the bottom plate, a collar is fitted, and a grounded table-shaped lower electrode that goes up and down along the inner peripheral surface of this collar is exposed to the lower part inside the chamber. Furthermore, the outer peripheral surface is on the bottom plate outside the lower electrode. Is in contact with the inner peripheral surface of the chamber, and the upper surface is provided with an exhaust ring flush with the lower electrode. The inner diameter of this exhaust ring is larger than the outer diameter of the lower electrode, and the inner peripheral surface of the exhaust ring and the outer periphery of the lower electrode are The gap between the surface and the upper surface of the collar was used as an exhaust port and was connected to an exhaust passage below the exhaust port.

(Function) Unlike the conventional parallel plate type, the upper electrode is separated from the lower electrode, and the part surrounded by the upper part is the main plasma generation region, so the wafer surface is less likely to be damaged by ions or charged particles. Since the wafer is placed on the lower electrode, the density of active species involved in the reaction is higher than that of the conventional TCA type, and since the vacuum is drawn from the vicinity of the outer periphery of the lower electrode, the active species do not flow to the outside. First, the generated active species are effectively processed on the wafer.

(Example) Below, the Example of this invention is described based on an accompanying drawing.

FIG. 1 is an overall view of a plasma reaction processing apparatus according to the present invention. A bell jar type quartz chamber (2) is placed and fixed on a bottom plate (1). An exhaust passage (3) is formed in the bottom plate (1), and the quartz chamber (2) has a small diameter part (2a) at the upper part and a large diameter part (2b) at the lower part, and a small diameter part (2a).
A reaction gas introduction pipe (4) is connected to the upper end of the tube, and a cylindrical upper electrode (6) connected to the high frequency power source (5) is arranged outside the small diameter part (2a).

Further, an opening (7) is formed in the bottom plate (1), a cylindrical collar (8) is fitted in the opening (7), and a table-shaped lower electrode () is formed along the inner peripheral surface of the collar (8). 9) goes up and down. This lower electrode (9) is grounded, and a flange portion (9a) extending outward is formed on the lower portion, and when the lower electrode (9) rises, the flange portion (9)
a) Seal member (10) with the upper end attached to the bottom plate (1) lower surface
The airtightness in the chamber (2) is ensured by pressing it against.

On the other hand, an exhaust ring (11) is provided on the bottom plate (1) in the chamber (2). The outer peripheral surface of the exhaust ring (11) is in contact with the inner peripheral surface of the chamber (2), the upper surface thereof is flush with the lower electrode (9), and the inner diameter of the exhaust ring (11) is the same as that of the lower electrode (9). Exhaust ring (11) larger than outer diameter
An exhaust port (12) for vacuuming is formed in a gap between the inner peripheral surface and the outer peripheral surface of the lower electrode (9). And exhaust port (12)
Is an exhaust passage formed in the bottom plate (1) through an exhaust passage (13) formed between the exhaust ring (11) and the collar (8) and the bottom plate (1) and located below the exhaust port (12). It is connected to (3).

The electrode (6) may be provided in the chamber (2), and the exhaust port (12) formed on the outer periphery of the lower electrode (9) has a plurality of openings around the lower electrode (9). They may be formed at even intervals. When the size of the wafer (W) to be processed is smaller than that of the table-shaped lower electrode (9), the exhaust ring (11) and the lower electrode (9) are not flush with each other. ) May be extended to the outer periphery of the wafer (W) to exhaust gas through the gap between the exhaust ring (11) and the lower electrode (9), that is, the exhaust port (12) and the exhaust passage (13).

In the above, in order to remove the organic film formed on the surface of the semiconductor wafer (W), first the lower electrode (9) is lowered from the position shown in FIG. 1 and the wafer ( W) is placed and the lower electrode (9) is raised again to make the chamber (2) airtight, and then the exhaust port (1)
The inside of the chamber (2) is decompressed by suction through 2) and a mixed gas containing, for example, 5% by volume of hexafluoroethane and oxygen as the balance is introduced from the reaction gas introduction pipe (4), and the upper electrode (6) Apply high frequency to.

Then, plasma is mainly generated in the upper part of the chamber (2) surrounded by the upper electrode (6), and oxygen radicals activated by the generation of the plasma are discharged through the exhaust port (1
By suction from 2), it reaches the wafer (W) together with plasma, and reacts with the organic film on the surface of the wafer (W) to remove the organic film.

2 and 3 are overall views of a plasma reaction apparatus according to another embodiment. In the apparatus shown in FIG. 2, the upper electrode (6) has a cap shape, and the upper electrode (6) is used to form a chamber. The small diameter portion (2a) of (2) is entirely covered to increase the generation of active species.

In the device shown in FIG. 3, the cylindrical upper electrode (6)
Is divided into two semi-cylindrical electrodes (6a) and (6b), only one electrode (6a) is connected to the high frequency power supply (5), and the other electrode (6b) is connected to the high frequency power supply via the switch (14). It is designed so that it can be connected to (5) or grounded.

With such a configuration, for example, both electrodes (6a) and (6b) are connected to the high frequency power source (5) at the initial stage of removing the organic film.
The upper layer of the carbonized or altered organic film is removed by increasing the reaction rate by connecting to the electrode. If the organic film is removed to some extent, the electrode (6b) is grounded, and only the upper part of the chamber (2) is used as the plasma generation chamber. , The wafer (W) can be prevented from being damaged by ions or charged particles.

(Effects of the Invention) The results of performing the organic film removal by the device of the present invention and the organic film removal by the conventional parallel plate device under the same conditions are described below.

The organic film was used when phosphorus was ion-implanted at 10 mA and 80 keV, and its thickness was 10600Å. Oxygen gas was independently supplied as a reaction gas at a rate of 100 sccm, the chamber internal pressure was 0.3 Torr, the applied power was 250 W, and the temperature was 100 ° C.

As a result, according to the apparatus of the present invention, the removal of the organic film was completed in 1 minute and 30 seconds, but it took 5 minutes with the conventional apparatus. That is, the ashing rate using the conventional device is about 2150Å / min.
On the other hand, it was confirmed that the device of the present invention reached about 7,000 Å / min.

Further, almost no damage was found on the wafer after ashing, and the wafer was uniformly removed. In the case of the conventional TCA type device, ashing could not be performed at all.

As described above, according to the plasma reaction processing apparatus of the present invention, it is possible to quickly and uniformly perform processing such as removal or etching of the organic film without damaging the wafer.

[Brief description of drawings]

FIG. 1 is an overall view of a plasma reaction processing apparatus according to the present invention,
2 and 3 are overall views of a plasma reaction processing apparatus according to another embodiment, and FIGS. 4 and 5 are views showing a conventional plasma reaction processing apparatus. In the drawing, (2) is a chamber, (3) and (13) are exhaust passages, (5) is a high frequency power source, (6) is an upper electrode, and (9).
Is a lower electrode, (11) is an exhaust ring, and (12) is an exhaust port.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazutoshi Fujisawa 15-10 Higashikubo-cho, Nishi-ku, Yokohama-shi, Kanagawa (56) Reference JP-A-56-51828 (JP, A)

Claims (2)

[Claims] 1. A cylindrical upper electrode to which a high frequency is applied is arranged outside or inside a bell jar type chamber provided on a bottom plate, an opening is formed in the bottom plate, and a collar is fitted therein. A grounded table-shaped lower electrode that rises and lowers along the inner peripheral surface is exposed to the lower part of the chamber, and the outer peripheral surface abuts the inner peripheral surface of the chamber on the bottom plate outside the lower electrode, and the upper surface faces the lower electrode. One exhaust ring is provided, the inner diameter of this exhaust ring is made larger than the outer diameter of the lower electrode, and the gap between the inner peripheral surface of the exhaust ring, the outer peripheral surface of the lower electrode, and the upper surface of the collar serves as the exhaust port, A plasma reaction processing apparatus, which is connected to an exhaust passage below the mouth. 2. The upper electrode is divided into a semi-cylindrical shape, one of the divided upper electrodes is connected to a high frequency power source, and the other upper electrode is selectively connected to a ground and a high frequency power source. The plasma reaction processing apparatus according to claim 1.