JPH07302765A - Air-cooled processor and continuously processing method using this processor - Google Patents

Abstract

PURPOSE:To provide the plasma CVD device capable of equalizing the film thickness even if the following steps are continuously performed i.e., the first step of forming a nitride film etc., the second step of carrying out the processed bodies after the formation, the third step of etching the reaction chamber and the fourth step of carrying the next wafer in. CONSTITUTION:A shower head 18 is composed of the upper wall of a reaction chamber 4 wherefrom a reaction gas flows to a workpiece. A heat sink 30 is arranged in contact with the upper surface of the shower head 18 while the heat sink 30 is provided with a fin extending in the radial direction. A cooling fan 40 is provided on a cap cover 34 covering the circular cover encircling the periphery of the heat sink 30. On the other hand, a thermocouple is fitted to the heat sink 30 to monitor the temperature of the shower head 18 so that, when the shower head temperature rises exceeding the specified temperature, the cooling fan 40 may be started to control the shower head temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-wafer processing apparatus and method for performing predetermined processing such as thin film formation on a plurality of objects to be processed such as semiconductor wafers, ceramics, glass and metal plates.

[0002]

2. Description of the Related Art Plasma CVD apparatuses for forming a nitride film or the like on a semiconductor wafer include a batch type and a single wafer type. The batch method has a feature that it can process a plurality of wafers at a time although the deposition rate is slow. On the other hand, the single-wafer processing has a feature that although the wafers are processed one by one, there is no problem of uniformity in batch. Wafers having a large diameter have been processed today, and a single wafer type plasma CVD apparatus is suitable for processing such wafers.

In order to process a plurality of wafers in a single wafer plasma CVD apparatus, the wafer is loaded into the processing chamber of the single CVD apparatus, a nitride film is formed, and the wafer is unloaded after the film formation. Then, the process of etching the processing chamber and loading the next wafer into the processing chamber is continuously performed.

[0004]

However, when such a continuous process is performed in the conventional plasma CVD apparatus, the temperature of the shower head for supplying the process gas rises as the process process progresses, as shown in FIG. Thus, the film thickness of the film formed on the wafer also increases as the temperature of the shower head increases.

When the temperature of the shower head becomes constant, the film thickness of the film formed in each process also becomes constant. However, as the number of processed wafers (indicated by "●") further increases as shown in FIG. The thickness is decreasing. Further, as shown in FIG. 7, in the conventional apparatus, as the number of processed wafers increases, unevenness appears in the surface of the thin film formed on the wafer.

As described above, in the conventional plasma CVD apparatus, when the above steps are continuously performed to increase the throughput of wafers, the film thickness changes with the number of processed wafers and the film surface on each wafer. The homogeneity within also changes. This cannot increase the throughput.

Further, in order to sequentially etch the surfaces of a plurality of wafers, ceramics, glass, metal plates, etc., an etching gas is flown from a shower head in an etcher (the above CVD apparatus can also be used as an etcher). Similar to the thin film formation, the uniformity of etching on the surface changes as the number of processed wafers increases, and the throughput cannot be increased.

Therefore, an object of the present invention is to treat the object to be processed with CV.
D is carried into the processing chamber, a nitride film is formed, and after the film formation, the object to be processed is carried out from there, and the processing chamber is etched,
It is an object of the present invention to provide a plasma CVD apparatus in which the thickness of film formation is uniform even if the process of loading the next wafer from the processing chamber is continuously performed.

Another object of the present invention is to provide the above-mentioned plasma CVD apparatus which makes the surface of the film formed on each individual object to be processed uniform.

A further object of the present invention is plasma CVD.
An object of the present invention is to provide a method for forming a uniform and uniform film in an apparatus regardless of the number of objects to be processed that are continuously processed.

A further object of the present invention is to provide an etching apparatus having a uniform etching thickness even when a plurality of objects to be processed are sequentially etched.

Still another object of the present invention is to provide the above-mentioned etching apparatus for uniformly etching individual objects to be processed.

[0013]

A processing apparatus of the present invention that achieves the above object is a shower head for supplying a processing gas to an object to be processed placed on a susceptor constituting a lower wall of a processing chamber. Characterized by having means for forming an air stream for cooling the.

The air flow forming means may be formed by a heat sink which comes into contact with the upper surface of the shower head, and a cooling fan which is located above the heat sink. In order to improve the cooling efficiency, it is desirable to provide a cooling piece, for example, a large number of fins extending in the radial direction, on the upper surface of the heat sink.

The cooling fan is provided on the processing chamber on the cover covering the cylindrical portion surrounding the heat sink. The airflow generated by the cooling fan is a flow that enters into the cover through an opening formed at a position corresponding to the cooling fan of the cover or flows out through the opening. If the air passage hole is provided at least inside the cylindrical portion, the cooling efficiency can be further improved.

The temperature of the shower head is monitored by heat detecting means provided on the heat sink, for example, a thermocouple, and the cooling fan is activated when the temperature of the shower head rises above a predetermined temperature.

The method of the present invention is for forming an air flow for cooling a shower head for supplying a processing gas to an object to be processed placed on a susceptor constituting a lower wall of the processing chamber of the processing chamber. In a plasma CVD apparatus having means, a) a step of maintaining the shower head at a predetermined temperature by an air flow forming means, and b) a step of inserting an object to be processed into a processing chamber and forming a thin film on the object to be processed. , C) a step of unloading the object having the thin film formed thereon from the processing chamber, and d)
Etching process chamber, and e) a) to d)
The process is repeated until a thin film is formed on a predetermined number of objects to be processed. Here, the temperature of the shower head is most preferably about 113 ° C.

[0018]

1 is a partial sectional view of a single-wafer plasma CVD apparatus 1 according to an embodiment of the present invention. A processing chamber 4 is formed in the processing chamber 2 of the CVD apparatus 1. A susceptor 6 constituting a lower wall of the processing chamber 4 is provided so as to be movable up and down, and a wafer 8 which is a substrate to be processed has a wafer lifting pin. It is supported by a pin 10 of a support mechanism (not shown). A heater is embedded in the susceptor 6 to heat the temperature of the wafer to a set value. The gas in the processing chamber 4 is exhausted through the exhaust pipe 12. The susceptor, the wafer lifting pin support mechanism, the heater, and the exhaust pipe have the structures of a conventional CVD apparatus, and therefore these structures are schematically shown in FIG. 1 for the sake of simplicity of description.

An intermediate annular portion 14 is attached to the inside of the upper portion of the processing chamber 2, and the inner annular portion 1 is further provided inside thereof.
6 is attached. A shower head 18 is provided inside the inner annular portion 16. The shower head 18 includes a bottom plate 22 having a large number of holes 20 and forming an upper wall of the processing chamber 4, and a top plate 28 having a flat upper surface and connected to a pipe 26 for sending a processing gas. Composed. A flat circular cavity is provided in the shower head 18 so that the processing (reaction) gas introduced by the pipe 26 uniformly flows out from the large number of holes 20.

Top plate 28 of shower head 18
A heat sink 30 is attached to the flat upper surface of the (FIG. 2). In this embodiment, the heat sink 30 consists of six fan-shaped segments 30 'for ease of installation and a plan view of one basic segment is shown in Figure 3a. Figure 3b shows a cross-sectional view of the segment along the line bb of Figure 3a.

Each segment 30 ', as shown in FIG.
A plurality of fins 31 are provided in the radial direction. The fins 31 extend from the inner side to the outer side in order to allow the airflow to flow radially outward from the center (or vice versa) to cool the heat sink 30 and the showerhead 18, as will be described later. However, if the heat sink 30 and the shower head 18 can be cooled by the airflow, such a plate-shaped fin is not necessary, and a large number of small fins may be arranged in a line, or a rod-shaped piece such as a wire may be radially arranged. It may be arranged in. Also, the heat sink 3
Even if 0 is integrated with the top plate 28, the cooling effect can be similarly obtained.

A recess 32 (FIG. 2) is formed in one of the segments of the heat sink 30 in which a sheathed thermocouple (not shown) is attached to monitor the temperature of the heat sink 30, and thus the showerhead 28. .

A circular cover 33 is attached to the upper surface of the processing chamber 2, and the cover 33 is covered with a cap cover 34 shown in FIG. Cap cover 34
The two cover parts 35 (see FIG. 4) for easy mounting.
a) and 36 (Fig. 4b). One cover part 3
5, a large opening 38 and a cutout 39 'that forms a small opening 39 are formed. A cooling fan 40 is mounted above the opening 38 so that the airflow generated by the cooling fan 40 can flow in and out through the opening 38 (FIG. 1).

Below the cover portion 35, a plate 41 in the shape of a semi-genuine ellipse shown by a dotted line in FIG.
Is attached through. Furthermore, the plate 41 has a notch 43 ′ that forms a circular opening 43. Similarly, below the cover 36, a semicircular plate 44, which is indicated by a dotted line in FIG. 4c, is attached via a peripheral wall 45. Further, the plate 44 also has a notch 43 ″ that forms the circular opening 43.

When the cap cover 34 is formed from the cover portions 35 and 36, the cap cover 34, the plates 41 and 44, and the peripheral walls 42 and 45 form a substantially circular cavity 46 (see FIG. 1). Therefore, the airflow generated by the cooling fan 40 enters the cavity 46 through the opening 38 and then from there through the opening 43 to the heat sink 30. Thus, although airflow is introduced through the off-center openings 38, it can flow radially outward from the center of the heat sink 30 and evenly cool the showerhead 18.

Of course, similar cooling can be performed even if the cooling fan forms an air flow flowing from the lower side to the upper side. That is, when such an air flow is formed, the air is absorbed by the heat sink 3
Cooling is achieved by flowing from around 0 towards the center and through the openings 39 to the outside.

In the above-mentioned embodiment, since the pipe 26 extends vertically in the center, the cooling fan cannot be arranged in the center. Therefore, the air flow by the cooling fan is guided into the cavity 46 by using the plates 41 and 44, Through the opening 43 of the heat sink 18. However, by displacing the pipe 26 from the center, the cooling fan can be arranged in the center. In this case, the plate 4 is placed under the cap cover 34.
It is not necessary to provide 1, 44.

In order to enhance the cooling effect and to form the air flow more effectively, it is desirable to form holes 33 'in the circular cover 33 by punching or the like.

The apparatus of the above-described embodiment described above is a plasma CVD apparatus, but this apparatus can also be used as an etching apparatus (etcher) by flowing an etching gas instead of a reaction gas. Also in this case, as described above, when the air flow is formed by the cooling fan, the sequentially inserted objects can be uniformly etched.

The cooling fan, the cap cover,
By equipping the conventional etching apparatus with the heat sink, uniform and uniform etching can be performed as described above.

The above CVD apparatus and etching apparatus can perform desired processing on not only semiconductor wafers but also ceramics, glass, metal plates and the like.

[0032] Examples above embodiment inserts the wafer using a CVD apparatus shown in Example, deposition, unloading of the wafer, etching, an example of executing a series of processing steps of the insertion of the wafer.

The deposition conditions and etching conditions executed in a series of processing steps are as shown in the table below.

[0034]

[Table 1] Table 1 ( Deposition conditions) SiH ₄ 220cc / min NH ₃ 900cc / min N ₂ 600cc / min PRESS 3.75torr RF HF 450W LF 500W GAP 10mm TEMP 420 ° C

[Table 2] Table 2 (Etching conditions) C ₂ F ₆ 1500cc / min O ₂ 2000cc / min PRESS 3.0torr RF HF 700W GAP 14mm TEMP 420 ° C

In the apparatus shown in FIG. 1, as shown in Table 3 below, the temperature of the shower head 18 was 139 ° C. even when the cooling fan was not started (air cooling specification (fan OFF)). On the other hand, before the heat sink 30, the circular cover 32, the cap cover 34, and the cooling fan 40, which are means for forming an air flow for cooling, are installed (in the case of standard specifications), the temperature of the shower head 18 is 160. ℃
Had reached. When the cooling fan was started (air cooling specification (fan ON)), the temperature reached 68 ° C.

[0036]

[Table 3]

When the temperature detected by the thermocouple installed on the heat sink exceeds a predetermined temperature, the cooling fan is started to maintain the temperature of the shower head at the predetermined temperature, and the above deposition conditions and etching conditions are set. Then, a series of processes of inserting a wafer into the apparatus, performing deposition, taking out the wafer, etching the apparatus, and then inserting a new wafer were performed up to 100 wafers.

FIG. 6 shows the results when the shower head was maintained at 113 ° C., 140 ° C., and the standard specifications. As can be seen from FIG. 6, when the shower head is maintained at 113 ° C. by providing a means for forming an air flow and activating the cooling fan, the film thickness formed on the wafer is almost constant up to the 100th wafer. There was (Fig. 6
Is indicated by "○"). Also, when it was maintained at 140 ° C., it was almost constant up to the 53rd sheet.

On the other hand, in the case of the standard specifications, that is, when the above-mentioned treatment is carried out without providing the means for forming the air flow for cooling, the film thickness is increased up to the 27th sheet as the shower head temperature rises. Also increases (FIG. 5), and the film thickness gradually decreases from around the 55th sheet (indicated by “●” in FIG. 6), and a uniform film thickness cannot be formed in continuous processing.

Further, when the in-plane distribution mapping of the wafer on which the thin film was formed was taken for the first, 25th, 50th and 100th wafers, as shown in FIG. When kept at 113 ° C, the first sheet, 2
Almost no change was observed on the surface of the 5th, 50th and 100th sheets. When the temperature of the shower head was maintained at 140 ° C, there was almost no change in the surface up to the 50th sheet. On the other hand, when not air-cooled, unevenness appeared on the 25th sheet, and the change was remarkable on the 50th sheet and the 100th sheet.

Further, when the film quality was examined, it was as shown in Table 4.

[Table 4] Table 4 Film quality evaluation results No air cooling 113 ° C 114 ° C Film thickness (Å) 7769 7819 7373 Wafer-to-wafer (±%) 3.10 2.48 3.61 In-plane (±%) 1.55 0.67 2.39 Refractive index 2.086 2.056 2.097 STRESS (dyn / cm ² ) -2.67 x 10 ^-9 -2.67 x 10 ^-9 -2.26 x 10 ^{-9 In} any case, There is no difference in stress and the refractive index is 1
It was the lowest at 13 ° C.

Although no clear reason is known that the film thickness formed on a wafer changes depending on the number of processings without cooling and the film surface (uniformity) of each wafer changes, the cooling is not known. It is considered that one of the reasons is that the white powder adheres to the surface of the shower head when the step is not performed, and the powder changes the adhesion rate.

It has been found that when the temperature of the shower head is controlled according to the present invention, the generation of powder can be suppressed and the fluctuation of the film thickness can be suppressed.

[0044]

As described above, by cooling the CVD apparatus according to the present invention with air, a thin film having a uniform film thickness is formed on the objects to be sequentially inserted. Further, the inside of the thin film becomes uniform. Furthermore, by air-cooling the etching apparatus according to the present invention, it is possible to uniformly etch the objects to be sequentially inserted. Moreover, the etching becomes uniform. .

[Brief description of drawings]

1 shows a partial cross-sectional side view of a single wafer plasma CVD apparatus according to the present invention.

FIG. 2 shows a partially sectional plan view of a single wafer plasma CVD apparatus according to the present invention.

FIG. 3 shows a plan view and a cross-sectional view of one segment constituting a heat sink used in a single wafer plasma CVD apparatus according to the present invention.

FIG. 4 shows a cover portion that constitutes a cap cover used in a single wafer plasma CVD apparatus according to the present invention.

FIG. 5 shows the relationship between the temperature and film thickness of the shower head and the number of processed wafers during continuous processing in a conventional single wafer plasma CVD apparatus.

FIG. 6 shows the relationship between the film thickness and the number of processed wafers when the temperature of the shower head is controlled.

FIG. 7 shows the mapping of the surface of the film formed on the first, 25th, 50th and 100th wafers when the temperature of the shower head is controlled.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single wafer type plasma CVD apparatus 2 Processing chamber 4 Processing chamber 14 Intermediate annular part 16 Inner annular part 18 Shower head 20 Hole 22 Bottom plate 26 Pipe 28 Top plate 30 Heat sink 30 'segment 31 Fin 32 Recess 33 Circular cover 34 Cap cover 38 Opening 39 Opening 40 Cooling Fan 41 Plate 43 Opening 44 Plate 46 Cavity

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 25, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 7]

Claims (8)

[Claims] 1. A processing object is placed on a susceptor forming a lower wall of a processing chamber of a processing chamber, and a processing gas is emitted from a shower head located above the processing object and forming an upper wall of the processing chamber. A processing apparatus which flows into a processing object and is processed on the processing object, comprising a means for forming an air flow for cooling the shower head. 2. The plasma CVD in which the processing gas is a reaction gas and the processing apparatus forms a thin film on an object to be processed.
The processing apparatus according to claim 1, wherein the processing apparatus is an apparatus. 3. The processing gas is an etching gas,
The processing apparatus according to claim 1, wherein the processing apparatus is an etching apparatus that etches an object to be processed. 4. The processing apparatus according to claim 2, wherein the air flow forming unit includes a heat sink that comes into contact with an upper surface of the shower head, and a cooling fan that is located above the heat sink. The processing apparatus, wherein a large number of cooling pieces are provided on the upper surface of the heat sink. 5. The processing apparatus according to claim 4, wherein the cooling fan is provided on a cover that covers a cylindrical portion surrounding the heat sink, and an air flow generated by the cooling fan is The processing apparatus is characterized in that the flow enters the inside through an opening formed at a position corresponding to the cooling fan of the cover or flows out through the opening. 6. The processing device according to claim 2, wherein a thermocouple is attached to the heat sink, the temperature of the shower head is monitored, and the temperature of the shower head rises above a predetermined temperature. A processing device, wherein the cooling fan is activated at times. 7. The processing apparatus according to claim 5, wherein the cylindrical portion has an air circulation hole. 8. An object to be processed is placed on a susceptor forming a lower wall of the processing chamber of the processing chamber, and a reaction gas is emitted from a shower head located on the object to be processed and forming an upper wall of the processing chamber. A plasma CVD apparatus that flows to an object to be processed and on which a thin film is formed, the plasma CVD apparatus having means for forming an air flow for cooling on the shower head, a) the air formation Maintaining the showerhead at a predetermined temperature by means, b) inserting an object to be processed into a processing chamber, and forming a thin film on the object to be processed, and c) an object to be processed having the thin film formed thereon. Carrying out the body from the processing chamber; d) etching the processing chamber; and e) repeating steps a) to d) until a thin film is formed on a predetermined number of objects to be processed. From How.