JP2004266297A - Manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LP-CVD device which forms a BSG film of uniform boron concentration on the surface of a semiconductor wafer without using a distributing nozzle, and to provide a method for forming the BSG film of uniform boron concentration with superior reproducibility by using the device. <P>SOLUTION: A decompression CVD device 20 comprises: a boat 4 holding a plurality of wafers to be processed 10; a reactor housing the boat 4; a heater 5 which is arranged around the reactor to heat an atmosphere in the reactor; and gas introduction pipes 2 and 3 introducing a reactant gas into the reactor. In a method for manufacturing a semiconductor device which forms a boron silicate glass (BSG) thin film on the wafer to be processed 10 by using the device 20, a source gas containing a boron (B) of concentration of 4 wt.% or more is supplied through the gas introduction pipes 2 and 3 having a spout positioned below a position where the wafer to be processed 10 is held, at a temperature of 600-800 °C and a pressure of 0.1-5 Torr. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a semiconductor manufacturing apparatus and a method of manufacturing a semiconductor device, and more particularly to a low-pressure CVD apparatus and a method of manufacturing a semiconductor device including a step of forming a BSG film on a semiconductor wafer using the same.

In the manufacture of a semiconductor device, an oxide film is used as a mask material in a process of selectively removing silicon by RIE (Reactive Ion Etching). Further, in the case of selectively stripping only the mask material after the step completion of RIE, the boron in the oxide film (B) a boron silicate glass doped with a high concentration (B oron- S ilicate G lass, hereinafter simply BSG Is widely used.

  A method of manufacturing a BSG film by a conventional technique using a batch type LP-CVD (Low Pressure-Chemical Vapor Deposition) apparatus will be described with reference to FIG.

  FIG. 3 is a schematic view showing a furnace structure of an example of a conventional LP-CVD apparatus. The LP-CVD apparatus 50 shown in FIG. 1 has a reaction tube having a double structure having an outer tube 1 and an inner tube 6, and a boat 4 holding a semiconductor substrate 10 as a processing target wafer inside the inner tube 6. Have. From the vicinity of the bottom of the inner tube 6, nozzles 3, 52 for introducing a reaction gas are arranged to extend into the inner tube 6.

  The nozzle 52 is disposed up to the peripheral region at the upper end of the boat 4, and the reaction gas is introduced into the inner tube through the nozzle. The used reaction gas passes through a region sandwiched between the inner tube 6 and the outer tube 1 and is discharged from exhaust ports 12 and 13 provided at the lower part of the apparatus. The heating of the wafer 10 is performed by a heater 5 provided outside the reaction tube. In addition, a vacuum pump 11 is connected to a pressure reducing port 15 provided at the bottom of the LP-CVD apparatus 50, and thereby the pressure inside the reaction tube is adjusted.

  Conventionally, when a BSG film is formed using such an LP-CVD apparatus 50, the BSG film is used as a source of boron by using a dispersion nozzle having a plurality of injection ports corresponding to the positions of the semiconductor substrates held by the boat 4. A gas, for example, trimethyl borate (TMB) was introduced into the reactor. This is for uniformly supplying the source gas to a large number of semiconductor substrates, whereby a BSG film having a uniform boron concentration could be formed on the semiconductor substrates with a uniform thickness.

  However, in the above-described film forming method using the dispersion nozzle, the uniformity of the concentration and the film thickness largely depends on the diameter of the gas nozzle. Therefore, when the gas nozzle is replaced due to regular maintenance or the like, if the processing accuracy of the gas nozzle varies, there is a problem that reproducibility of the process cannot be obtained before and after the replacement of the nozzle.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an LP-CVD apparatus for forming a BSG film having a uniform boron concentration on a surface of a semiconductor wafer without using a dispersion nozzle, and a semiconductor using the same. It is an object of the present invention to provide a method of manufacturing a device, in which a BSG film having a uniform boron concentration is formed with good reproducibility.

  The present invention solves the above problems by the following means.

That is, according to the present invention,
A boat for holding a plurality of wafers to be processed, a reactor for accommodating the boat, and a heater disposed around the reactor for heating an atmosphere in the reactor to a temperature of about 600 ° C. to about 800 ° C. And a gas introduction pipe having a jet port located below a position where the wafer to be processed is held, and introducing a source gas containing boron (B) having a concentration by weight of 4% or more into the reaction furnace. And a pressure reducing means for maintaining the pressure in the reaction furnace at 0.1 Torr to 5 Torr, thereby providing a reduced pressure CVD (Chemical Vapor Deposition) apparatus.

  It is preferable that the low-pressure CVD apparatus further includes temperature control means for controlling the heater so that the atmosphere in the reaction furnace is maintained at about 700 ° C.

  More preferably, the reduced pressure CVD apparatus further includes reduced pressure control means for controlling the reduced pressure means so that the pressure in the reaction furnace is maintained at about 0.5 Torr.

According to the present invention,
A boat for holding a plurality of wafers to be processed, a reaction furnace for accommodating the boat, a heater disposed around the reaction furnace for heating an atmosphere in the reaction furnace, and holding the wafer for processing; A method for manufacturing a semiconductor device using a reduced-pressure CVD apparatus having a gas introduction pipe for introducing a reaction gas into the reaction furnace from an ejection port located below the position, wherein the temperature is about 600 ° C. to about 800 ° C. At a temperature of 0.1 Torr to 5 Torr, a source gas containing boron (B) having a weight ratio of 4% or more is supplied from the gas introduction pipe to form boron silicate glass (BSG) on the wafer to be processed. A method of manufacturing a semiconductor device including a step of forming a thin film is provided.

  The source gas may contain trimethyl borate (TMB) or triethyl borate (TEB).

  Further, in the above manufacturing method, it is preferable to heat the atmosphere in the reaction furnace to about 700 ° C.

  Further, in the above manufacturing method, it is more preferable that the pressure in the reaction furnace is about 0.5 Torr.

  As described in detail above, the present invention has the following effects.

  That is, according to the semiconductor manufacturing apparatus of the present invention, a source gas containing boron (B) having a concentration by weight of 4% or more is provided, having an ejection port located below a position where a wafer to be processed is held. Since a gas introduction pipe for introducing the gas into the reaction furnace is provided, a BSG film having a uniform boron concentration and a uniform thickness can be formed on the surface of the wafer to be processed without using a dispersion nozzle.

  Further, according to the method of manufacturing a semiconductor device of the present invention, the semiconductor device has a spout located below a position where a source gas containing boron (B) at a weight ratio of 4% or more is held below a position where a wafer to be processed is held. Since the gas is supplied from the gas inlet tube into the reaction furnace, a BSG film having a uniform boron concentration between wafers can be stably manufactured. Thus, even if there is some variation in the processing accuracy of the gas nozzle, it is not necessary to change the film forming conditions before and after the replacement, so that a semiconductor manufacturing method with high reproducibility is provided.

  Hereinafter, some embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same portions as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  FIG. 1 is a schematic diagram showing a furnace structure of one embodiment of a reduced pressure CVD apparatus according to the present invention. As is clear from comparison with FIG. 3, the batch-type LP-CVD apparatus 20 shown in FIG. 3 is not a dispersion nozzle as a nozzle for guiding a source gas, but is located below a position where the wafer 10 to be processed is held. It is characterized by having a short nozzle 2 having an ejection port. The other points are almost the same as those of the low pressure CVD apparatus 50 shown in FIG.

  Next, a method for manufacturing a semiconductor using the low-pressure CVD apparatus 20 shown in FIG. 1 will be described as an embodiment of a method for manufacturing a semiconductor device according to the present invention. This embodiment is characterized in that the material gas is supplied to the reaction furnace using the short nozzle 2 so that the boron concentration in the furnace becomes 4% by weight or more.

  FIG. 2 shows the relationship between the boron concentration in the furnace (horizontal axis: weight ratio%) and the boron concentration uniformity of the BSG film (vertical axis:%) when the BSG film is formed by the semiconductor device manufacturing method of the present embodiment. FIG. Trimethyl borate (TMB) is supplied from the short nozzle 2 as a material gas under a film forming condition of a temperature of 700 ° C. and a pressure of 0.5 Torr using an L-shaped 25 mm-6 mmφ as the short nozzle 2. Ethyl orthosilicate (TEOS: Tetraethoxysilane) was supplied from the nozzle 3.

  As can be seen from FIG. 2, in the region where the boron concentration in the furnace is 4% by weight or more, even when the short nozzle 2 is used, the variation in the boron concentration in the BSG film formed on the semiconductor wafer is reduced to less than 4%. Can be suppressed.

  Further, there is a process of selectively removing the BSG film by wet etching. At this time, the selectivity to the remaining oxide film depends on the boron concentration in the BSG film. Therefore, in order to obtain a sufficient selectivity, it is necessary to dope boron into the BSG film at a high concentration. In this case, if the material gas is supplied using the semiconductor manufacturing method of the present embodiment so that the boron concentration of the BSG film becomes 4% or more by weight, film formation using the short nozzle 2 shown in FIG. 2 is possible. It is. Thereby, a BSG film can be formed with high reproducibility.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be variously modified and used without departing from the gist thereof. Further, materials and various film forming conditions can be changed according to required specifications. For example, in the above-described embodiment, trimethyl borate (TMB) is used as the boron source gas. However, the present invention is not limited to this. For example, triethyl borate (TEB) may be used. Also, the film forming conditions are not limited to 700 ° C., and good results are obtained in the range of 600 ° C. to 800 ° C. Further, the pressure is not limited to 0.5 Torr, and in the range of 0.1 Torr to 5 Torr, good uniformity can be obtained almost similarly to the uniformity shown in FIG.

FIG. 1 is a schematic view showing a furnace structure of an LP-CVD apparatus used in an embodiment of a method for manufacturing a semiconductor device according to the present invention. It is a correlation diagram which shows the relationship between the boron concentration in a furnace, and the boron concentration uniformity between wafers. It is the schematic which shows the furnace structure of an example of the conventional LP-CVD apparatus.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Outer tube 2, 3, 52 Nozzle 4 Boat 5 Heater 6 Inner tube 8 Flange 9 Heat shield plate 10 Wafer to be processed 11 Vacuum pump 12, 13 Outlet 20 Low pressure CVD apparatus

Claims (5)

A boat for holding a plurality of wafers to be processed, a reactor for accommodating the boat, a heater disposed around the reactor to heat an atmosphere in the reactor, and the wafer to be processed held therein A method for manufacturing a semiconductor device, comprising using a reduced pressure CVD apparatus having a gas introduction pipe for introducing a reaction gas into the reaction furnace from an ejection port located below the position,
A source gas is supplied from the gas introduction tube at a temperature of about 600 ° C. to about 800 ° C. and a pressure of 0.1 Torr to 5 Torr, and a thin film of boron silicate glass (BSG) is formed. A) forming a thin film having a weight ratio of 4% or more.   2. The method according to claim 1, further comprising controlling the heater so that an atmosphere in the reaction furnace is maintained at about 700.degree.   The method according to claim 1, further comprising maintaining a pressure in the reaction furnace at about 0.5 Torr.   4. The method according to claim 1, wherein the source gas includes trimethyl borate (TMB). 5.   4. The method according to claim 1, wherein the source gas includes triethyl borate (TEB).

Images