JP2650445B2 - Thin film forming equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a thin film forming apparatus for forming a thin film on a semiconductor wafer in a semiconductor manufacturing process.

[Conventional technology]

Conventionally, to form a thin film on a semiconductor wafer (hereinafter simply referred to as a wafer) in a semiconductor manufacturing process, first, a reaction product film is formed on the wafer by a chemical vapor deposition apparatus,
Thereafter, the reaction product film is flattened using a diffusion furnace.

FIG. 3 is a sectional view showing a schematic configuration of a conventional chemical vapor deposition apparatus, FIG. 4 is a sectional view showing a schematic configuration of a conventional diffusion furnace,
FIG. 5 is an enlarged sectional view showing a wafer on which a reaction growth film is formed, and FIG. 6 is an enlarged sectional view showing a wafer subjected to a planarization process.

In these figures, reference numeral 1 denotes a wafer stage of a chemical vapor deposition apparatus, and the wafer stage 1 is connected to a transfer device (not shown) and is configured to move continuously in the lateral direction. Reference numeral 2 denotes a wafer mounted on the wafer stage 1, reference numeral 3 denotes a heater for heating the wafer 1 to a film forming temperature, reference numeral 4 denotes a gas head for supplying a reaction gas A to the wafer 2, and reference numeral 5 denotes exhaust B Is an exhaust port for discharging air. In FIG. 4, reference numeral 6 denotes a furnace chamber tube serving as a diffusion furnace main body. The furnace chamber tube 6 has a furnace chamber lid 8 having a gas supply air supply pipe 7 provided at one end, and provided at the other end. Is furnace tube 6
An exhaust pipe 9 for exhausting the gas inside is provided,
It is configured to be heated to a predetermined temperature by the diffusion furnace heater 10. Reference numeral 11 denotes a wafer device boat for introducing a plurality of the wafers 2 into the furnace chamber tube 6 in a state of being erected.

In order to form a reaction product film on the wafer 2 by the conventional chemical vapor deposition apparatus configured as described above, first, the wafer 2 is placed on the continuously moving wafer stage 1. Then, the wafer 2 is transported above the heater 3 by the wafer stage 1 and is heated to a film forming temperature by the heater 3. When the wafer 2 thus heated passes below the gas head 4, a reaction gas A is supplied from the gas head 4, and a reaction product film C is formed on the main surface of the wafer 2 as shown in FIG. Will be formed.
In FIG. 5, reference numeral 12 denotes a wiring formed on the wafer 2. As shown in FIG. 5, the surface of the reaction product film C is not flat because it is also formed on the outer peripheral portion of the wiring 12 or the like as a base, so the flattening process is performed by a diffusion furnace shown in FIG. Is applied.

In order to perform the flattening process of the reaction product film C using a diffusion furnace, first, the wafer 2 is inserted into the furnace chamber tube 6 while being held on the wafer mounting boat 11. Thereafter, the surface of the reaction product film C can be formed substantially flat as shown in FIG. 6 by heating the wafer 2 to a predetermined temperature by the heater 10 for the diffusion furnace. The heating by the heater 10 is performed while the gas is discharged from the exhaust pipe 9 while the gas is supplied from the air supply pipe 7 and the inside of the furnace chamber pipe 6 is maintained at a constant atmosphere.

As an example of forming a thin film using these apparatuses, for example, when an insulating film is formed on a polysilicon wiring formed on a main surface of a wafer 2, a chemical vapor deposition apparatus shown in FIG. In the above, a wafer 2 is heated to 400 ° C., and a film in which P and B are diffused in SiO ₂ in a small amount using SiH ₄ , PH ₃ , B ₂ H ₆ , and O ₂ gas as a reaction gas A (hereinafter, BPSG film) Is formed on the wafer 2. The formed BPSG film is indicated by C in FIG.
As shown by, it is also formed on the outer peripheral portion of the wiring 12. In the diffusion furnace shown in FIG. 4, the BPSG film is flattened by heating the furnace chamber tube 6 at 900 ° C. for 20 minutes in a constant atmosphere of H ₂ and O ₂ . Hereinafter, this flattening step is referred to as reflow. As shown by C in FIG. 6, the BPSG film after reflow has relatively smooth surface irregularities.

[Problems to be solved by the invention]

However, when a thin film is formed on the wafer 2 by the chemical vapor deposition apparatus and the diffusion furnace as described above, it takes time to transfer the wafer 2 from the chemical vapor deposition apparatus to the diffusion furnace. It will be exposed to.
For this reason, there has been a problem that moisture in the air is easily absorbed into the reaction product film C, and the BPSG film is liable to be reduced in the film chamber due to a decrease in insulation due to moisture absorption.

Also, the BPSG film wiring 12
Step coverage on the surface (hereinafter referred to as step coverage)
And the unevenness remains on the surface of the BPSG film after reflow. In particular, the distance between adjacent wirings 12 and the reaction product film C
Depending on the conditions such as the film thickness, the reaction product films formed on the adjacent wirings 12 may interfere with each other, and a gap may be formed between the adjacent wirings 12 as shown by D in FIG. . When the gap D is formed in this way, as shown in FIG. 7, bubbles E due to the gap D remain in the reaction product film C after the reflow. When the bubble E remains, the portion swells upward and the unevenness on the surface of the reaction product film further increases.

[Means for solving the problem]

The thin film forming apparatus according to the present invention includes a film forming heater that heats a semiconductor wafer, and in a thin film forming apparatus that forms a thin film on a semiconductor wafer heated in a reaction chamber by a film forming reaction gas, the reaction chamber includes: A gas head for supplying a reaction gas for film formation is provided so as to be able to move up and down, and a lamp body is surrounded by a lamp cover having an irradiation port facing a film formation surface of the semiconductor wafer, and selectively faces the reaction chamber into a thin film. A thin film flattening treatment lamp-type heater for heating to a temperature higher than the formation temperature is provided separately from the film formation heater, and the lamp-type heater is configured to be able to reciprocate between the reaction chamber and the lamp chamber, A state in which the head is lowered to supply a reaction gas and a film forming heater is driven to form a thin film, and the lamp type heater is moved to a reaction chamber to be flat. It is obtained by constituting repeated several times and the condition to take a treatment.

(Operation)

According to the present invention, film formation on a semiconductor wafer and planarization can be performed continuously without exposing the semiconductor wafer to the outside air, and a thin film can be formed by stacking a plurality of thin reaction product films. it can.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 (a) and (b) and FIGS. 2 (a) to (d).

1 (a) and 1 (b) are sectional views showing a thin film forming apparatus according to the present invention, FIG. 1 (a) shows a state at the time of film formation, and FIG. 1 (b) shows a state at the time of reflow. Fig. 2 (a)-
(D) is a cross-sectional view showing a state of formation on the wiring portion on the wafer, (a) showing a state after a reaction product film is formed on the wafer, and (b) of FIG. (C) shows a state in which a reaction product film is formed again on the wafer shown in (d) in FIG.
FIG. 3D shows a state after the wafer shown in FIG. In these figures, the same or equivalent members as those described in FIGS. 3 to 7 are denoted by the same reference numerals, and detailed description is omitted.

1 (a) and 1 (b) and FIGS. 2 (a) to 2 (d), reference numeral 21 denotes a film forming reaction chamber as a main body of the thin film forming apparatus according to the present invention. An exhaust port 5 is provided on the upper side, and a wafer stage 22 on which the wafer 2 is mounted is disposed below. This wafer stage 22
It is connected to an elevating device (not shown) via a push-up pin 23, and is configured to be able to move up and down in the film formation reaction chamber 21.

Reference numeral 24 denotes a gas head for supplying the reaction gas A to the wafer 2. The gas head 24 is disposed above the film forming reaction chamber 21, and is provided to be able to move up and down in the film forming reaction chamber 21.

Reference numeral 25 denotes a lamp chamber for accommodating a lamp to be described later when forming a thin film. The lamp chamber 25 is provided on a side of the film forming reaction chamber 21 and communicates with the film forming reaction chamber 21 via an airtight door 26. I have.

27 is a lamp as a heater for thin film flattening processing for heating the wafer 2 at the time of reflow.
A lamp body 27a for heating the wafer 2 at a temperature higher than the film forming temperature, and a lamp cover 27b having a structure in which an irradiation port facing the film forming surface of the wafer 2 is opened at the bottom and surrounds the lamp body 27a; The apparatus is connected to an apparatus (not shown) via a lamp arm 28, and is provided to be able to reciprocate between the film forming reaction chamber 21 and the lamp chamber 25.

Next, a method of forming a thin film on the wafer 2 using the thin film forming apparatus of the present invention configured as described above will be described. In order to form a thin film on the wafer 2, first, the wafer 2 is placed on the wafer stage 22, and the gas head 24 is lowered as shown in FIG. By heating the wafer 2 to a predetermined temperature by the heater 3 and supplying the reaction gas A to the wafer 2 from the gas head 24, the reaction product film C is formed as shown in FIG. become. At this time, the reaction time and the like are controlled so that the film thickness of the reaction product film becomes about half of the predetermined film thickness.

In the case of forming a BPSG film as an example, the wafer 2 is heated to about 400 ° C.
The reaction is performed by supplying a reaction gas A comprising iH ₄ , PH ₃ , B ₂ H ₆ , O ₂ , and N ₂ to the wafer 2.

After the film formation is completed, as shown in FIG.
The lamp 27 is moved above the wafer 2 instead of the lamp 24, and the wafer stage 22 is raised by the push-up pins 23 to be separated from the heater 3. And gas head 24
The film formation reaction chamber 21 is supplied by air supply from the exhaust port and exhaust from the exhaust port 5.
The inside is made constant atmosphere of H ₂ and O ₂ . In this state, the lamp 27 is turned on to heat the wafer 2 to a predetermined temperature, and reflow is performed. In order to perform reflow on the wafer 2 on which the BPSG film is formed, the film formation reaction chamber 21 is heated to 900 ° C. for 20 minutes in a state of a constant atmosphere of H ₂ and O ₂ . By performing the reflow in this manner, as shown in FIG. 2 (b), the irregularities on the surface of the reaction product film are reduced.

According to the present invention, the above-described generation and reflow steps are repeatedly performed until a desired film thickness is obtained. As described above, the reaction product film C has a thickness of about half the predetermined thickness.
After forming the film, a reaction product film having a final thickness is obtained as shown in FIG. 2C by further forming a reaction product film having the remaining half thickness. At this time, the thin film of the reaction product film C obtained at a time is small,
It is possible to reliably prevent the reaction product films C formed in 12 from interfering with each other to form a gap. Then, by performing further reflow, the surface of the reaction product film C can be made substantially flat as shown in FIG. 2 (d).

In addition, since the wafer is heated by the lamp 27 during the flattening process, only the wafer 2 and the vicinity of the wafer 2 are heated to the flattening temperature at this time. For this reason, the temperature of the wafer 2 is likely to decrease after the flattening process is completed, so that the thin film forming process can be started as soon as possible after the flattening process.

Therefore, according to the present invention, the film formation and the reflow can be performed in the film formation reaction chamber 21, so that the thin film can be formed continuously on the wafer 2 without being exposed to the outside air. Further, by repeatedly performing film formation and reflow, a plurality of thin reaction product films C can be stacked to form a thin film, and a gap can be prevented from being formed in the reaction product film.

Further, since the lamp 27 heats the wafer during the planarization process, only the wafer 2 and the vicinity of the wafer 2 are heated to the planarization temperature at this time. For this reason, the temperature of the wafer 2 is likely to decrease after the flattening process is completed, so that the thin film forming process can be started as soon as possible after the flattening process.

The film formation mechanism, the number of times of film formation and heating, and the like are not limited to those described in the above embodiment, and needless to say, they can be appropriately changed.

〔The invention's effect〕

As described above, the thin film forming apparatus according to the present invention includes a film forming heater for heating a semiconductor wafer, and a thin film forming apparatus for forming a thin film on a semiconductor wafer heated in a reaction chamber by a film forming reaction gas. In the reaction chamber, a gas head for supplying a reaction gas for film formation is provided so as to be able to move up and down, and a lamp body having a lamp cover having an irradiation port facing a film formation surface of a semiconductor wafer is surrounded and selectively placed in the reaction chamber. A thin film flattening lamp type heater for heating the semiconductor wafer to a temperature higher than the thin film formation temperature is provided separately from the film forming heater, and the lamp type heater is reciprocally movable between the reaction chamber and the lamp chamber. A state in which the gas head is lowered to supply a reaction gas and a film forming heater is driven to form a thin film; Since the semiconductor wafer is moved to the chamber and the state of performing the flattening process is repeated a plurality of times, the film formation on the semiconductor wafer and the flattening process can be performed continuously without exposing the semiconductor wafer to the outside air, and quickly after the film formation. Since the flattening process can be performed, the processing time including the transfer time of the semiconductor wafer can be reduced, and the moisture in the air can be reliably prevented from being absorbed into the reaction product film. A reactive film can be obtained.

Further, since a thin film can be formed by stacking a plurality of thin reaction product films, it is possible to prevent a gap from being formed in the reaction product film, and to improve the step coverage.

In addition, when the flattening process of the thin film is performed, only the semiconductor wafer and the vicinity thereof are heated to a relatively high flattening process temperature. Therefore, the temperature of the semiconductor wafer tends to decrease after the flattening process is completed. . That is, the heating temperature of the semiconductor wafer when forming the thin film is lower than that during the flattening process. However, as described above, the temperature of the semiconductor wafer rapidly decreases, so that the thin film is early formed after the flattening process step is completed. The formation process can begin.

Accordingly, the required time can be reduced as much as possible in repeating the film forming process from the thin film forming process to the planarization process a plurality of times.

[Brief description of the drawings]

1 (a) and 1 (b) are cross-sectional views showing a thin film forming apparatus according to the present invention. FIG. 1 (a) shows a state during film formation, and FIG. 1 (b) shows a state during reflow. . Fig. 2 (a)-
(D) is a cross-sectional view showing a film formation state on a wiring portion on the wafer, (a) shows a state after a reaction product film is formed on the wafer, and (b) is a figure (a). (C) shows a state in which a reaction product film is formed again on the wafer shown in (b) of FIG.
FIG. 3D shows a state after the wafer shown in FIG. FIG. 3 is a sectional view showing a schematic configuration of a conventional chemical vapor deposition apparatus, FIG. 4 is a sectional view showing a schematic configuration of a conventional diffusion furnace, and FIG. 5 is an enlarged view of a wafer on which a reaction product film is formed. 6, FIG. 6 is an enlarged sectional view of a wafer subjected to a planarization process, and FIG. 7 is an enlarged sectional view of a wafer having bubbles remaining in a reaction product film. 2 ... semiconductor wafer, 3 ... heater, 21 ... film forming reaction chamber, 25 ... lamp chamber, 26 ... airtight door, 27 ... lamp, C
...... Reaction product film.

Claims (1)

(57) [Claims] An apparatus for forming a thin film on a semiconductor wafer heated in a reaction chamber by using a reaction gas for film formation, comprising: a heater for film formation for heating a semiconductor wafer; A gas head for supplying gas is provided so as to be movable up and down, and the lamp body is surrounded by a lamp cover having an irradiation port facing the film forming surface of the semiconductor wafer and selectively faces the reaction chamber, and the semiconductor wafer is heated to a temperature higher than the thin film forming temperature. A thin-film flattening lamp heater for heating to a temperature is provided separately from the film forming heater, the lamp heater is configured to be reciprocable between the reaction chamber and the lamp chamber, and the gas head is lowered. A state in which a thin film is formed by supplying a reaction gas and driving a film forming heater, and a state in which a flattening process is performed by moving the lamp heater to a reaction chamber. Thin film forming apparatus is characterized in that a structure is repeated a plurality of times and.