JP3399144B2 - Method of forming silicon-based coating - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a silicon-based film and a heat treatment apparatus, and more particularly to a method for forming a silicon-based film on a wafer surface in a semiconductor device manufacturing process. The present invention relates to a method and a heat treatment apparatus used for the method. 2. Description of the Related Art In a process of manufacturing a semiconductor device, when a silicon-based film is formed on a surface of a wafer having an uneven shape by forming aluminum wiring, the following process is performed. First, a solution for forming a silicon-based film on the surface of the sample is spin-coated on the surface of the wafer. Next, if necessary, the wafer is placed on a heated hot plate, and the solvent in the solution is vaporized and removed.Then, the wafer is placed in a vacuum furnace or a furnace kept in a nitrogen atmosphere at normal pressure. Heat to solidify the solution. As a result, a silicon-based coating, ie, SOG (Sp
in On Glass) film is formed. However, in the above-described method for forming a silicon-based film, since the heat treatment of the solution is performed in a furnace, the solution is heated from the surface side by radiant heat. Therefore, the solidification of the solution, that is, the dehydration-condensation reaction of the solution comprising the silanol compound proceeds from the surface side of the solution, and the surface solidifies before the inside. When the solidification proceeds from the surface side in this manner, it becomes difficult for moisture to escape from under the solidified surface, and thus the dehydration / condensation reaction of the solution is inhibited. For this reason, a silicon-based film that is incompletely solidified with moisture remaining therein is formed. Then, in a wafer on which such a silicon-based coating is formed, the aluminum wiring under the silicon-based coating is corroded,
A so-called poisoned via in which the aluminum in the through hole corrodes occurs. Accordingly, an object of the present invention is to provide a method of forming a silicon-based film and a heat treatment apparatus which solve the above-mentioned problems. In order to achieve the above object, a method for forming a silicon-based film according to the present invention is intended for use in solidifying a solution for forming a silicon-based film applied to a sample surface. Then, the surface of the solution is exposed to an oxygen-free atmosphere while the sample coated with the solution is heated from the back side. The heating temperature on the back side is the first temperature at which the dehydration condensation reaction of the solution proceeds completely. The atmosphere containing no oxygen is heated from a second temperature lower than the first temperature to the first temperature. A heat treatment apparatus used for the method of forming a silicon-based coating comprises a sample table whose mounting surface is heated to a predetermined temperature by a first heating means and a first temperature control means, A gas supply pipe for supplying gas on the mounting surface. The gas supply pipe is provided with second heating means connected to second temperature control means. The second temperature control means raises the temperature of the gas in the gas supply pipe from a temperature lower than the mounting surface to the same temperature as the mounting surface. In the method of forming a silicon-based film, the sample coated with the solution for forming the silicon-based film is heated to the first temperature from the back surface side. Heated to the first temperature from the side. Further, since the temperature of the atmosphere in contact with the surface of the solution is raised from the second temperature lower than the first temperature to the first temperature, the surface side of the solution is raised from the second temperature to the first temperature. It is heated up to the temperature. For this reason, the inside of the solution gradually reaches the first temperature from the lower surface side as the temperature of the atmosphere in contact with the surface of the solution increases. Since the first temperature is a temperature at which the dehydration / condensation reaction proceeds completely, the dehydration / condensation reaction is gradually completed and solidified from the lower surface side of the solution as the temperature of the atmosphere increases. Further, in the above-mentioned heat treatment apparatus, since the mounting surface is provided with a sample stage heated to a predetermined temperature, the sample mounted on the sample stage is heated to a predetermined temperature from the lower surface side. . Further, a second heating means is provided in the gas supply pipe for supplying gas onto the mounting surface of the sample stage, and the temperature of the gas in the gas supply tube is increased from a temperature lower than the mounting surface of the sample stage. Since the second temperature control means for raising the temperature to the same temperature as the mounting surface is connected, the surface of the sample mounted on the sample stage is heated to the same temperature as the mounting surface of the sample stage. I do. For this reason, the inside of the sample sequentially reaches the heating temperature of the mounting surface from the lower surface side as the temperature of the gas supplied from the gas supply pipe rises. An embodiment of a heat treatment apparatus used in the method of forming a silicon-based film according to the present invention will be described below with reference to FIG. The heat treatment apparatus 1 has a sample stage 11, and a first heating unit 12 is provided inside the sample stage 11. The first heating means 12 includes a first temperature control means 13
Is connected. The sample stage 11 is disposed in a chamber 14, and an exhaust pipe 15 and a gas supply pipe 16 are connected to the chamber 14. The gas supply pipe 16 is provided with a second heating means 17.
Is connected to a second temperature control means 18. The sample stage 11 mounts a sample 20 such as a wafer on which a silicon-based film is formed. Then, inside the sample stage 11, that is, on the opposite side to the sample 20 placed on the placement surface 11a of the sample stage 11,
For example, a first heating means 12 such as a heater is provided. The first temperature control means 13 connected to the first heating means 12 is provided on the mounting surface 11 of the sample table 11.
a is heated to a predetermined temperature of, for example, 400 ° C.
The heating means 12 is controlled. In the sample stage 11, a plurality of sample stages may be arranged in a multi-stage manner. In this case, a plurality of samples can be processed at one time. The chamber 14 isolates the atmosphere around the sample table 11 housed therein from the outside air. An exhaust pipe 15 is connected below the sample table 11 and a gas supply pipe 16 is formed above the sample table 11. It has a connected structure. Thereby, the surface of the sample 20 placed on the sample stage 11 becomes
The gas 19 supplied from the gas supply pipe 16 is exposed to the atmosphere. The second heating means 17 comprises, for example, a heater arranged around the gas supply pipe 16. Further, the second temperature control means 18 connected to the second heating means 17 connects the gas supply pipe 16 to the mounting surface 11a.
The temperature of the gas 19 supplied above is raised from a temperature lower than the heating temperature of the mounting surface 11a to the heating temperature of the mounting surface 11a. For example, the gas 19 supplied from the gas supply pipe 16 is supplied. The heating temperature of the heating unit 16a is controlled so that the temperature is increased from 20 ° C. to 400 ° C. at a rate of 20 ° C./min. The second heating means 17
May be provided in the chamber 14. In this case, the gas 19 supplied into the chamber 14 is heated by the second heating means. In the heat treatment apparatus 1 having the above configuration, the sample table 1
The sample 20 placed on 1 is heated to 400 ° C. from the back side. The surface side of the sample 20 is 2 ° C. to 2 ° C.
Gas 19 heated to 400 ° C. at a rate of 0 ° C./min
Exposed to Therefore, the inside of the sample 20 sequentially reaches the heating temperature of the mounting surface 11a from the lower surface side as the temperature of the gas 19 supplied from the gas supply pipe 16 increases. The reaching speed of the heating temperature can be adjusted by the heating speed of the gas 19. Next, a method for forming a silicon-based film using the heat treatment apparatus 1 will be described with reference to FIGS. FIG. 2 is a process diagram showing a method of forming a silicon-based film, FIG. 3 is a graph showing a change over time of a temperature of a gas supplied into a chamber of a heat treatment apparatus, and FIG. is there. As shown in FIG. 2A, in a sample 20 on which a silicon-based film is formed on the surface, for example, a wiring 22 made of aluminum is patterned on a substrate 21, and an oxide film 23 is formed so as to cover the wiring 22. The surface of the wiring 22 has an uneven shape due to the formation of the wiring 22. When a silicon-based coating is formed on the surface of the sample 20 in a state where the irregularities are buried, first, a solution for forming a silicon-based coating on the surface of the sample 20 (hereinafter referred to as silicon 24) is spin-coated. This silicon-based coating solution 24 is a solution containing an organic or inorganic silanol compound. Next, as shown in FIG.
Is heated to obtain the silicon-based coating solution 2
4 is solidified. At this time, first, for example, nitrogen gas or other oxygen-free gas (1) is supplied from the gas supply pipe (16) into the chamber (14) of the heat treatment apparatus (1).
9) is supplied. Here, oxygen-free gas (1
Nitrogen gas is used as 9), and the inside of the chamber (14) is set to a nitrogen gas atmosphere. This gas (19)
The initial temperature of the temperature T ₂ a dehydration condensation reaction is a second lower than the first temperature T ₁ of proceeding entirely silicon based film solution 24
Is set to The second temperature T ₂ is a temperature at which the dehydration-condensation reaction of the silicon-based coating solution 24 does not easily proceed. Here, for example, the first temperature is set to T ₁ ≧ 320 ° C., and the second temperature is set to T ₂ = 20 ° C. Next, the sample 20 coated with the silicon-based coating solution 24 is placed on the mounting surface (11) of the sample stage (11) of the heat treatment apparatus (1) with the coated surface of the silicon-based coating solution 24 facing upward. 11a) placed on the sample, and the heat treatment of the sample 20 is started. At this time, it kept heated to a temperature T ₁ of advance the first placement surface (11a), gradually heating the sample 20 from the lower surface side. Here, the temperature of the mounting surface (11a) is set to 400
Set to ° C. Thus, at the time when the heat treatment is started, the surface d of the silicon-based coating solution 24 is placed in an atmosphere of the nitrogen gas supplied at the second temperature T ₂ = 20 ° C.
₀ to expose the surface d ₀ to 20 ° C. On the other hand, the silicon-based coating solution 24 was heated to 400 ° C.
By heat from 1a) is heated from its lower surface d ₁ side to 400 ° C. nearby. Then, the temperature gradient in the depth direction of the silicon-based coating solution 24 from the surface d ₀ side toward the lower surface d ₁ side so that a high temperature. Thereafter, the temperature of the nitrogen gas (19) supplied from the gas supply pipe (16) into the chamber (14) is increased by the second temperature control means (18) to the second temperature T ₂ = 20.
° C to the first temperature T ₁ ≧ 320 ° C, where the mounting surface (1
The temperature is raised to 400 ° C., which is the heating temperature of 1a). The heating rate is set to, for example, 20 ° C./min in accordance with the rate at which the dehydration condensation reaction is completed from the lower surface d ₁ side of the silicon-based coating solution 24. Thus, in the process of increasing the temperature of the nitrogen gas (19), the surface d ₀ of the silicon-based coating solution 24 is increased in accordance with the temperature of the nitrogen gas (19). On the other hand, the lower surface d ₁ of the silicon-based coating solution 24 is 40
40 ° C. by the heat from the mounting surface (11a) heated to 0 ° C.
Heat to 0 ° C. The depth range d ₁ -d ₂ from the lower surface d ₁ to the depth d ₂ of the silicon-based coating solution 24 is the first.
To reach the temperature T ₁ , and the depth range d ₁ -d ₂
Completes the dehydration-condensation reaction of the silicon-based coating solution 24. This depth range d ₁ -d ₂ increases as the supply temperature of the nitrogen gas (19) increases. On the other hand, in the depth range d ₀ -d ₁ from the surface d ₀ to the depth d ₂ of the silicon-based coating solution 24, dehydration condensation occurs because the internal temperature has not reached the first temperature T _1. The reaction does not proceed completely. This depth range d ₀ -d ₁ corresponds to the nitrogen gas (1
It is reduced as the supply temperature increases in 9). After the heat treatment further proceeds and the temperature of the nitrogen gas (19) reaches 400 ° C., the temperature is raised to 400 ° C. until the dehydration condensation reaction on the surface d ₀ of the silicon-based coating solution 24 is completed. Heated nitrogen gas (19)
Continue to be supplied into the chamber (14). by this,
After the temperature of the nitrogen gas (19) reaches 400 ° C., the temperature gradient in the depth direction of the recon-based coating solution 24 is reduced to 0, and the silicon-based coating solution is dehydrated on the surface d _0. Allow the condensation reaction to proceed completely. As described above, the silicon-based coating solution (24)
The silicon-based coating 25 is formed on the surface of the sample 20 by advancing the dehydration condensation reaction. The silicon-based coating film 25 formed here is solidified by sequentially completing the dehydration-condensation reaction of the silicon-based coating solution (24) applied on the surface of the sample 20 from the lower surface side. Finally, since the surface of the silicon-based coating solution 24 is exposed to the nitrogen gas (19) heated to 400 ° C., the dehydration-condensation reaction on the surface of the silicon-based coating solution 24 sufficiently proceeds, and the silicon-based coating solution 24 The solution 24 can be sufficiently solidified. Further, the surface atmosphere of the silicon-based coating solution 24 is
By exposing to a gas that does not contain oxygen, such as nitrogen gas,
It is possible to prevent the surface side of the silicon-based coating solution 24 from undergoing a dehydration condensation reaction with oxygen. For this reason, the silicon-based coating 2 due to the moisture remaining in the silicon-based coating 25
Corrosion of the wiring 22 made of aluminum in the lower five layers can be prevented. As described above, according to the method for forming a silicon-based film of the present invention, the lower surface of a sample coated with a solution for forming a silicon-based film is subjected to a dehydration condensation reaction of the solution. Is heated to a first temperature at which the solution completely advances, and the temperature of the atmosphere in contact with the surface of the solution is gradually increased from the second temperature to the first temperature, whereby the dehydration condensation is gradually performed from the lower surface side inside the solution. The reaction can be completed to solidify the solution. For this reason, it is possible to prevent moisture from remaining inside by solidifying the solution from the surface side, and it is possible to form a silicon-based film in which the dehydration condensation reaction is completely completed. Further, in the heat treatment apparatus, the temperature of the gas in the gas supply pipe is lower than that of the mounting surface in the sample table in which the mounting surface is heated to a predetermined temperature and the gas supply pipe that supplies the gas on the mounting surface. By providing the second heating means and the second temperature control means for raising the temperature from the temperature to the same temperature as the mounting surface, the inside of the sample mounted on the sample stage is supplied from the gas supply pipe. As the temperature of the gas rises, heating can be performed so that the temperature of the mounting surface is sequentially reached from the lower surface side. Therefore, the dehydration condensation reaction of the solution for forming the silicon-based coating applied to the surface of the sample,
As the heat treatment proceeds, it can be gradually completed and solidified from the lower side. Therefore, it is possible to perform the above-described method for forming a silicon-based coating.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a heat treatment apparatus. FIG. 2 is a diagram illustrating a method for forming a silicon-based coating. FIG. 3 is a graph showing a change over time in a supply gas temperature. FIG. 4 is a graph showing a change in a temperature gradient in a depth direction of a sample. DESCRIPTION OF SYMBOLS 1 Heat treatment apparatus 11 Sample table 12 First heating means 13 First temperature control means 16 Gas supply pipe 17 Second heating means 18 Second temperature control means 19 Gas 20 Sample 24 Silicon-based coating Solution (Solution) 25 Silicon-based film T ₁ First temperature T ₂ Second temperature

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Claims (1)

(57) [Claim 1] After applying a solution for forming a silicon-based film on the surface of a sample, performing heat treatment while exposing the surface of the solution to an atmosphere containing no oxygen. In the method for forming a silicon-based film that solidifies the solution, the heat treatment is performed by heating the sample from the back side to a first temperature at which the dehydration-condensation reaction of the solution completely proceeds. A method for forming a silicon-based film, wherein an atmosphere containing no oxygen is heated from a second temperature lower than the first temperature to the first temperature.