JPH03157928A - Thin film formation and device therefor - Google Patents

Abstract

PURPOSE:To form thin films by laminating multiple thin reaction product films for avoiding the gap making between the films by a method wherein the formation and flattening processes of the thin films are separately performed in multiple times in the same device. CONSTITUTION:A semiconductor wafer 2 is mounted on a wafer stage 22 to be heated by a heater 23 simultaneously, reactive gas is fed from a gas head 24 controlling the reaction time, etc., to form a reaction product film C thinner than specified film thickness. After the formation of the film C, lamps 27 are shifted to the part above the wafer 2 while the wafer stage 22 is lifted to be isolated from the heater 3. Next, the lamps 27 are lighted in specific atmosphere of H2 and O2 to heat the wafer 2 for performing the reflowing process. This film formation process and the reflowing process are repeated until the films attain the specified thickness. Through these procedures, the formed films C interfere with the adjacent wiring 12 so that the gap formation between the films C can be surely avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and a thin film forming apparatus for forming a thin film on a semiconductor wafer in a semiconductor manufacturing process.

[Conventional technology]

Conventionally, in order to form a thin film on a semiconductor wafer (hereinafter simply referred to as a wafer) in a semiconductor manufacturing process, a reaction product film is first formed on the wafer using a chemical vapor deposition apparatus, and then a diffusion furnace is used to form a thin film on the wafer. This was done by flattening the reaction product film.

Fig. 4 is a cross-sectional view showing the schematic structure of a conventional chemical vapor deposition apparatus, Fig. 5 is a cross-sectional view showing the schematic structure of a conventional diffusion furnace, and Fig. 6 is an enlarged view of a wafer on which a reaction product film has been formed. FIG. 7 is an enlarged cross-sectional view of a wafer that has been subjected to a planarization process.

In these figures, 1 is a wafer stage of a chemical vapor deposition apparatus, and this wafer stage 1 is connected to a transport device (not shown) and is configured to move continuously in the lateral direction. 2 is a wafer placed on this wafer stage 17; 3 is a heater for heating the wafer 1 to a film forming temperature; 4 is a gas head for supplying reaction gas A to the wafer 2; 5 is an exhaust B This is an exhaust port for discharging.

Further, in FIG. 5, reference numeral 6 denotes a furnace chamber tube as a diffusion furnace main body, and this furnace chamber tube 6 is provided with a furnace chamber lid 8 having an air supply pipe 7 for gas supply at one end, and at the other end. is provided with an exhaust pipe 9 for discharging the gas in the furnace chamber pipe 6, and is configured to be heated to a predetermined temperature by a diffusion furnace heater 10. Note that 11 is a wafer loading port for introducing a plurality of wafers 2 in an upright state into the furnace chamber tube 6.

In order to form a reaction product film on the wafer 2 using the conventional chemical vapor deposition apparatus configured as described above, the wafer 2 is first placed on the wafer stage 1 which is continuously moving. The wafer 2 is then transported by the wafer stage 1 to the upper side of the heater 3, and heated by the heater 3 to a film forming temperature. When the wafer 2 heated in this way passes under the gas head 4, a reaction gas 8 is supplied from the gas head 4, and a reaction product film is formed on the main surface of the wafer 2, as shown in FIG. C will be formed.

Note that in FIG. 6, reference numeral 12 indicates wiring formed on the wafer 2. In FIG. The reaction product film C, as shown in FIG.
Since it is also formed on the outer periphery of the wiring 12 and the like as a base, its surface is not flat, so it is flattened using a diffusion furnace shown in FIG. To planarize 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 board 11. Thereafter, by heating the rewafer 2 to a predetermined temperature using the diffusion furnace heater 10, the surface of the reaction product film C can be formed to be substantially flat as shown in FIG.

In addition, when heating with this heater 10, gas is supplied from the air supply pipe 7 and gas is discharged from the exhaust pipe 9, thereby maintaining the inside of the furnace chamber pipe 6 at a constant atmosphere.

As an example of forming a thin film using these devices, for example, when forming an insulating film on polysilicon wiring formed on the main surface of the wafer 2, the chemical vapor deposition device shown in FIG. The wafer 2 was heated to 400° C., and the reaction gas A was S + Ha.

A film in which a small amount of P and B are diffused in 5in2 using PH3, B2H, and O□ gas (hereinafter referred to as BPSG film).
is formed on the wafer 2. The formed BPSG film is also formed on the outer periphery of the wiring 12, as shown by C in FIG. In addition, in the diffusion furnace shown in Fig. 5, BP
To flatten the SG film, the inside of the furnace chamber tube 6 is heated to H2,0.
It is heated to 900° C. for 20 minutes in a constant atmosphere of □. Hereinafter, this planarization process will be referred to as reflow.

After reflow, the surface of the BPSG film becomes relatively smooth, as shown by C in FIG.

[Problem to be solved by the invention]

However, when a thin film is formed on the wafer 2 using a chemical vapor deposition apparatus and a diffusion furnace as described above, it takes time to transfer the wafer 2 from the chemical vapor deposition apparatus to the diffusion furnace, and during that time the wafer 2 is exposed to the outside air. I will be exposed. For this reason, there is a problem in that moisture in the air is easily absorbed into the reaction product film C, and the film quality of the BPSG film is likely to deteriorate due to a drop in insulation properties due to moisture absorption. In addition, the wiring 1 of the BPSG film is
Step coverage to step 2 (hereinafter referred to as Stemp Kahale method).

) is low, and unevenness remains on the surface of the BPSG film after reflow. In particular, depending on conditions such as the spacing between adjacent wirings 12 and the thickness of the reaction product film C, the adjacent wirings 12 may
The reaction product films formed in the 6th
As shown in the figure, a gap may be formed between adjacent wirings 12. When gaps are formed in this way, air bubbles E due to the gaps are left in the reaction product film C after reflow, as shown in FIG. If the bubbles E remain, the bubbles bulge upward, making the surface of the reaction product film even more uneven.

[Means to solve the problem]

In the thin film forming method according to the present invention, thin film formation and planarization processing are performed in the same apparatus in multiple steps. Furthermore, the thin film forming apparatus according to the present invention includes a heater block for thin film planarization processing that selectively faces the reaction chamber and heats the semiconductor wafer to a temperature higher than the thin film forming temperature, separately from the film forming heater. It was established. Furthermore, another thin film forming apparatus according to the present invention includes a reaction chamber for forming a thin film by supplying a film forming reaction gas to a heated semiconductor wafer, and a reaction chamber for heating the semiconductor wafer to a temperature higher than the thin film forming temperature. A plurality of thin film planarization processing chambers are alternately arranged in a line, and between the reaction chamber and the thin film planarization processing chamber,
A passage is provided for keeping each chamber airtight and sequentially transporting semiconductor wafers from the reaction chamber along the direction in which the chambers are arranged.

[For production]

According to the present invention, film formation and planarization treatment on a semiconductor wafer 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. can.

〔Example〕

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

FIGS. 1(a) and 1(b) are cross-sectional views showing the thin film forming apparatus according to the present invention, with FIG. 1(a) showing the state during film formation, and FIG. 1(b) showing the state during beam flow. . Figure 2(a)-(
d) is a cross-sectional view showing the state of film formation on the wiring part of the wafer, FIG. The same figure (c) shows the state after the wafer shown in figure (b) has been subjected to reflow, and the figure (d) shows the state in which the reaction product film has been formed again on the wafer shown in figure (b). This figure shows the state of the wafer shown in Figure 1 after being subjected to reflow again. In these figures, the same or equivalent members as those explained in FIGS. 4 to 8 are given the same reference numerals and detailed explanations will be omitted. In FIGS. 1(a) and (b) and FIGS. 2(a) to (d), 21 is a film forming reaction chamber as the main body of the thin film forming apparatus according to the present invention, and this film forming reaction chamber 21 includes: An exhaust port 5 is provided at the upper side, and a wafer stage 22 on which the wafer 2 is placed is arranged at the lower part. This wafer stage 22
is connected to an elevating device (not shown) via a push-up bottle 23, and is configured to be able to move up and down within the film-forming reaction chamber 21.

Reference numeral 24 denotes a gas head for supplying the reaction gas A to the wafer 2. This gas head 24 is disposed above the film-forming reaction chamber 21 and is movable up and down within the film-forming reaction chamber 21.

Reference numeral 25 denotes a lamp chamber for housing a lamp to be described later during thin film formation, and this lamp chamber 25 is provided on the side of the film-forming reaction chamber 21 and communicated with the film-forming reaction chamber 21 through an airtight door 26. There is.

Reference numeral 27 denotes a lamp serving as a thin film flattening heater for heating the wafer 2 during reflow. It is provided with a surrounding lamp cover 27b, and is connected to a drive device (not shown) via a lamp arm 28 so as to be able to freely 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 explained. 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. 1(a). Then, by heating the wafer 2 to a predetermined temperature with the heater 3 and supplying the reaction gas A to the wafer 2 from the gas head 24, a reaction product film C is formed as shown in FIG. 2(a). become. At this time, the reaction time and the like are controlled so that the thickness of the reaction product film is about half of the predetermined thickness. For example, when forming a BPSG film, the wafer 2 is heated to about 400° C. by the heater 3, and in this state S I H4+ P H31B2. Hl,,o□,
This is carried out by supplying a reaction gas A consisting of N2 to the sea urchin 2. After the film formation is completed, as shown in FIG. 1(b), the lamp 27 is moved above the wafer 2 instead of the gas head 24, and the wafer stage 22
is raised by the push-up bottle 23 and separated from the heater 3. Then, the inside of the film forming reaction chamber 21 is made into a constant atmosphere of H2 and 02 by supplying air from the gas head 24 and exhausting from the exhaust port 5. In this state, the lamp 27 is turned on to heat the wafer 2 to a predetermined temperature to perform reflow. Note that in order to perform reflow on the wafer 2 on which the BPSG film is formed, the film forming reaction chamber 21 is heated to 900° C. for 20 minutes in a constant atmosphere of Hz and Oz. By performing reflow in this manner, as shown in FIG. 2(b), the unevenness on the surface of the reaction product film becomes smaller.

According to the present invention, the above-described film formation and reflow steps are repeated until a desired film thickness is obtained. As described above, after forming the reaction product film C with a film thickness of about half of the predetermined film thickness, if the reaction product film is further formed with the remaining half film thickness, the final film as shown in FIG. 2(c) is formed. A reaction product film C having a film thickness is obtained. At this time, since the film thickness of the reaction product film C obtained at - degree is small, the adjacent wiring 1
It is possible to reliably prevent the formation of gaps due to interference between the reaction product films C formed on the surfaces 2 and 2. By further performing reflow, the surface of the reaction product film C can be made substantially flat, as shown in FIG. 2(d).

Therefore, according to the present invention, since the film formation and flow can be performed within the film formation reaction chamber 21, the thin film can be continuously formed on the wafer 2 without being exposed to the outside air. In addition, by repeating the film formation flow and the flow, a plurality of thin reaction product films C can be stacked to form a thin film, and it is possible to prevent gaps from being formed in the reaction product films.

It goes without saying that the reaction gas, film-forming mechanism, heating mechanism, heating temperature, number of times of film-forming and heating, etc. are not limited to those described in the examples above, and can be changed as appropriate. do not have.

-11-2 Next, a thin film forming apparatus according to another invention of the present invention will be explained with reference to FIG.

FIG. 3 is a sectional view showing another thin film forming apparatus according to the present invention, and in this figure, the same or equivalent members as those explained in FIGS. 1(a) and (b) are designated by the same reference numerals. Detailed explanation will be omitted. In FIG. 3, numeral 31 indicates a film-forming reaction chamber, and this film-forming reaction chamber 31 has a gas head 2.
4. A heater 3 and an exhaust port 5 are provided. 32
is a wafer stage, and this wafer stage 32 is connected to a transport device (not shown) and is provided so as to be movable laterally by this transport device.

33 is a heating chamber for performing reflow on the wafer 2; a lamp 27 for heating the wafer 2 is disposed in the heating chamber 33; A trachea 33a and an exhaust pipe 33b for exhausting indoor gas are provided. In addition, this heating chamber 3
3 is placed adjacent to the film-forming reaction chamber 31, and an airtight door 34 for keeping each chamber airtight is provided on the side wall that partitions the chambers. That is, by opening the airtight door 34, the film forming reaction chamber 31 and the heating chamber 33 are brought into communication.

Note that 35 is a push-up bottle for bringing the wafer stage 32 closer to the lamp 27.

In this embodiment, the film forming reaction chamber 31 and the heating chamber 33 are
A plurality of wafers 2 are alternately stacked on top of each other, and the wafers 2 are sequentially transported to each chamber together with the wafer stage 32.

In the thin film forming apparatus configured in this way, the wafer 2 is heated by the heater 3 in the film forming reaction chamber 31, and the reaction gas A is supplied to the main surface of the heated wafer 2 by the gas head 24 to perform the reaction. A produced film C is formed.

After film formation, the wafer 2 and wafer stage 32 are closed to the airtight door 3.
4 to the adjacent heating chamber 33. In the heating chamber 33, the wafer stage 32 is raised by the push-up bottle 35, and the lamp 27 is turned on, thereby heating the wafer 2 and performing reflow. Note that during reflow, a constant atmosphere is maintained in the heating chamber 33 by supplying air from the supply pipe 33a and exhausting from the exhaust pipe 33b. After the reflow, the wafer 2 and the wafer stage 32 are further transported to the adjacent film forming reaction chamber 31, and a reaction product film is formed again. Then, it is further transported to the adjacent heating chamber 33, where reflow is performed.

That is, in this thin film forming apparatus, by sequentially transporting the wafer 2 to each chamber, the film forming flow can be repeated multiple times until a predetermined film thickness is obtained.

Therefore, according to the thin film forming apparatus shown in FIG. 3, since film forming and reflow can be performed in the same apparatus, there is no need to expose the wafer 2 to the outside air (continuously) when forming the thin film on the wafer 2. In addition, by repeating the film formation and removal flow, it is possible to form a thin film by stacking a plurality of thin reaction product films C, thereby preventing the formation of gaps in the reaction product films. can.

Note that the film forming mechanism, heating mechanism, number of times of film forming and heating, etc. are not limited to those described in the above embodiments.
It goes without saying that it can be changed as appropriate.

〔Effect of the invention〕

As explained above, the thin film forming method according to the present invention performs the thin film formation and planarization treatment in the same apparatus in multiple steps, and the thin film forming apparatus according to the present invention has a reaction chamber. In addition, a heater block for thin film planarization that selectively enters the reaction chamber and heats the semiconductor wafer to a temperature higher than the thin film formation temperature is installed separately from the film forming heater, so that the film formation and planarization process on the semiconductor wafer can be easily performed. These steps can be carried out continuously without exposing the semiconductor wafer to the outside air, and the planarization process can be performed immediately after film formation, which reduces the processing time including the time for transporting the semiconductor wafer, and reduces the amount of damage caused by the reaction-generated film. It is possible to reliably prevent moisture from being absorbed in the air and obtain a high-quality reaction product membrane. Furthermore, since a thin film can be formed by stacking a plurality of thin reaction product films, it is possible to prevent gaps from being formed in the reaction product films, and it is possible to improve step coverage. Furthermore, another thin film forming apparatus according to the present invention includes a reaction chamber for forming a thin film by supplying a film forming reaction gas to a heated semiconductor wafer, and a reaction chamber for forming a thin film by supplying a film forming reaction gas to a heated semiconductor wafer; A plurality of thin film planarization processing chambers to be heated are arranged alternately in a line, and each chamber is kept airtight between the reaction chamber and the thin film planarization processing chamber, and semiconductor wafers are placed between the reaction chambers along the arrangement direction of each chamber. By providing a passageway for sequentially transporting semiconductor wafers, it is possible to perform film deposition and planarization on semiconductor wafers in succession without exposing the semiconductor wafers to the outside air, and to form thin films by stacking multiple thin reaction product films. can do. Therefore, the film formation and planarization treatment, which are performed in multiple steps until a predetermined film thickness is reached, can be performed alternately on a plurality of semiconductor wafers, thereby reducing the overall processing time.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are cross-sectional views showing the thin film forming apparatus according to the present invention, with FIG. 1(a) showing the state during film formation, and FIG. 1(b) showing the state during beam flow. . Figure 2(a)-(
d) is a cross-sectional view showing the state of film formation on the wiring part on the wafer;
Figure (a) shows the state after a reaction product film has been formed on the wafer, Figure (b) shows the state after reflowing the wafer shown in Figure (a), and Figure (c) shows the state after the wafer shown in Figure (a) has been subjected to reflow. (b) shows a state in which a reaction product film has been formed again on the wafer shown in figure (b), and (d) of the same figure shows a state in which the wafer shown in figure (c) has been subjected to reflow again. FIG. 3 is a sectional view showing another thin film forming apparatus according to the present invention. Fig. 4 is a cross-sectional view showing the schematic structure of a conventional chemical vapor deposition apparatus, Fig. 5 is a cross-sectional view showing the schematic structure of a conventional diffusion furnace, and Fig. 6 is an enlarged view of a wafer on which a reaction product film has been formed. FIG. 7 is an enlarged new view of a wafer that has been subjected to flattening treatment, and FIG. 8 is an enlarged cross-sectional view of a wafer with bubbles remaining in the reaction product film. . 2...Semiconductor wafer, 3...Heater, 213
1... Film-forming reaction chamber, 25... Lamp chamber, 263
4... Airtight door, 27... Lamp, 33...
Heating chamber, C...reaction product film.

Claims (3)

[Claims] (1) A thin film forming method in which a thin film is formed on a semiconductor wafer heated in a reaction chamber using a film forming reaction gas, and then the semiconductor wafer is heated to a temperature higher than the thin film forming temperature to planarize the thin film. A thin film forming method characterized in that the thin film formation and planarization treatment are performed in multiple steps in the same apparatus. (2) Equipped with a film-forming heater that heats the semiconductor wafer,
In a thin film forming apparatus that forms a thin film on a semiconductor wafer heated in a reaction chamber using a reaction gas for film formation, a thin film forming device selectively faces the reaction chamber and heats the semiconductor wafer to a temperature higher than the thin film forming temperature. 1. A thin film forming apparatus, characterized in that a heater block for chemical treatment is provided separately from the film forming heater. (3) A plurality of reaction chambers that form a thin film by supplying a film-forming reaction gas to a heated semiconductor wafer and a plurality of thin film planarization processing chambers that heat the semiconductor wafer to a temperature higher than the thin film formation temperature are arranged in a line alternately. are arranged, and a passage is provided between the reaction chamber and the thin film planarization processing chamber to keep each chamber airtight and to sequentially transport the semiconductor wafers from the reaction chamber along the arrangement direction of each chamber. Thin film forming equipment.