JP2003224075A - Manufacturing method for semiconductor device and substrate processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a semiconductor device capable of film-forming the boron doped poly-silicon germanium or boron doped amorphous silicon germanium of an appropriate boron density by low pressure CVD method, and to provide a substrate processor. <P>SOLUTION: In the manufacturing method for the semiconductor device and the substrate processor, monosilane (SiH<SB>4</SB>) and monogermane (GeH<SB>4</SB>) are made to act under low pressure on a wafer 4 loaded on a boat 3 inside a reaction furnace 11 heated by a heater 6, and the boron doped poly-silicon germanium or the boron doped amorphous silicon germanium is film-formed on the surface of the wafer 4. Boron trichloride (BCl<SB>3</SB>) is used as a doping gas and the partial pressure of the boron trichloride is set to ≥0.2 Pa and ≤1 Pa. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing method and a substrate processing apparatus, and more particularly to a semiconductor device for forming polysilicon germanium or amorphous silicon germanium by a low pressure CVD method (chemical vapor deposition method). The present invention relates to a manufacturing method and a substrate processing apparatus.

[0002]

2. Description of the Related Art In a process of manufacturing a semiconductor device such as an IC and an LSI, a low pressure CVD method (chemical vapor deposition method) is used.
According to this, a thin film is formed on a substrate. As one of such film forming processes, low pressure CVD
Attempts have been made to form a silicon germanium film by the method.

For silicon germanium, it is attempted to grow epitaxial silicon germanium in a base region in a heterojunction bipolar transistor (HBT) or to form a polysilicon germanium film in a gate electrode portion in a MOS transistor depending on a target device. Has been.

Diborane (B ₂ H ₆ ) has been used to dope boron in the conventional polysilicon germanium film formation by a low pressure CVD apparatus. However, when diborane is used, it is a batch type vertical low pressure CVD.
In the apparatus, it was difficult to secure the boron (B) concentration uniformity in the silicon germanium film within the wafer surface and between the wafer surfaces. Therefore, boron trichloride (BCl ₃ ) has been used as an alternative doping gas for diborane. Since boron trichloride has a lower reactivity than diborane, it is not consumed so much in the gas flow direction, so that the boron concentration inter-plane uniformity can be secured. Further, it is known that even if the wafer interval is as narrow as about 5.2 mm pitch, the boron trichloride reaches the central part of the wafer and the boron concentration in-plane uniformity is improved.

[0005]

The appropriate value of the boron concentration in the silicon germanium film differs depending on the applied device portion. For example, for a gate electrode, a high concentration of boron is introduced to reduce the resistance. It is known that the concentration of boron in the silicon germanium film due to diborane monotonically increases in proportion to the partial pressure of diborane. However, it is not known what the behavior of chlorine-containing boron trichloride is. Therefore, clarifying the behavior of boron in the silicon germanium film when boron trichloride is used as a doping gas is an important issue in carrying out boron doping at an appropriate concentration.

An object of the present invention is to solve the above problems and to manufacture a semiconductor device capable of forming a film of boron-doped polysilicon germanium or boron-doped amorphous silicon germanium having an appropriate boron doping concentration by a low pressure CVD method. A method and a substrate processing apparatus are provided.

[0007]

In order to solve the above-mentioned problems, the present invention uses a monosilane and a monogermane as a reaction gas as described in claim 1 and uses a low pressure CVD method in a reaction furnace. Thus, in a method for manufacturing a semiconductor device in which boron-doped polysilicon germanium or boron-doped amorphous silicon germanium is formed on a substrate, using boron trichloride as a doping gas,
A method of manufacturing a semiconductor device is characterized in that the partial pressure of the boron trichloride during film formation is 0.2 Pa or more and 1 Pa or less.

Further, according to the present invention, as described in claim 2, a reaction tube for processing a substrate, a heater for heating the substrate in the reaction tube, and monosilane as a film forming gas in the reaction tube. A nozzle for supplying, a nozzle for supplying monogermane as a film forming gas, a nozzle for supplying boron trichloride as a doping gas, an exhaust pipe for exhausting the inside of the reaction tube, and the boron trichloride at the time of film formation The partial pressure of 0.2
A substrate processing apparatus comprising: a control device for controlling Pa to 1 Pa or less.

[0009]

DETAILED DESCRIPTION OF THE INVENTION As a result of intensive studies, the present inventors have clarified the relationship between the boron concentration incorporated in a silicon germanium film and the partial pressure of boron trichloride when boron trichloride is used as a doping gas. The present invention has been completed based on the results.

The method for manufacturing a semiconductor device according to the present invention is characterized in that, in a vertical low pressure CVD apparatus which is one of the substrate processing apparatus according to the present invention, monosilane (SiH ₄ ) and monogermane (GeH ₄ ) are used as reaction gases, and Boron trichloride is used as a gas to form a film of boron-doped polysilicon germanium or boron-doped amorphous silicon germanium on a wafer.

FIG. 1 shows a schematic diagram of a reactor structure of a hot-wall vertical type low pressure CVD apparatus which is an example of the vertical type low pressure CVD apparatus. In the figure, a quartz outer tube 1 and an outer tube of a reaction furnace 11 are provided inside a heater 6 which constitutes a hot wall furnace and is divided into four zones (U, CU, CL and L) for heating a substrate. An inner tube 2 inside the tube 1 is installed, and a vacuum is drawn between the two types of tubes by using a mechanical booster pump 7 and a dry pump 8. Therefore, monogermane, SiH ₄ + GeH ₄ nozzles 13 are used as reaction gas from the four intermediate supply nozzles 12 inside the inner tube 2.
Mixed gas of monosilane and monogermane as a reaction gas, and boron trichloride as a doping gas from the BCl ₃ nozzle 14, the reaction gas and the doping gas rise in the inner tube 2, and two kinds of tubes 1, It goes down between 2 and is exhausted. The supply flow rate of each gas is controlled by a flow rate control device (not shown) provided in each gas supply system.

A plurality of wafers 4, which are substrates, are vertically stacked and loaded in a vertical direction, and are mounted on a substrate support tool made of quartz and made of quartz 3 (for example, for 8-inch wafers, wafer-to-wafer spacing 5.2).
(mm pitch) is installed in the inner tube 2, and when exposed to a reaction gas, a boron-doped silicon germanium thin film is formed on the wafer 4 by the reaction in the gas phase and on the surface of the wafer 4. At that time, in order to control the pressure in the reaction furnace 11, nitrogen (N ₂ ) is introduced into the exhaust system through the N ₂ ballast valve 16, and the flow rate of the nitrogen is controlled by the controller 17 using the output signal of the pressure gauge 15. Control based on. The partial pressure of boron trichloride is controlled by adjusting the ratio of the internal pressure to the total flow rate and BCl ₃ flow rate. However, since the in-furnace pressure (growth pressure) greatly affects the film thickness uniformity within the wafer surface, in the present embodiment,
The BCl ₃ partial pressure is controlled by increasing / decreasing the flow rate of BCl ₃ . That is, in the present embodiment, a pressure control device including the N ₂ ballast valve 16, the pressure gauge 15 and the controller 17, and a flow rate control device (not shown) for controlling the flow rate of boron trichloride are claimed. The control device described in 2 controls the partial pressure of boron trichloride.

The heat insulating plate 5 is for insulating the space between the boat 3 and the lower part of the apparatus. Further, 9 is a boat rotating shaft, and 10 is a stainless steel lid.

FIG. 2 shows a film forming procedure using the substrate processing apparatus shown in FIG.

First, a plurality of wafers 4 are loaded into the boat 3 to stabilize the inside of the reaction furnace 11 at the film forming temperature, and then the boat 3 loaded with the wafers 4 is loaded (inserted) into the reaction furnace 11.
To do. The reactor (reactor 11) is evacuated and the boat 3
N ₂ purge is performed in order to desorb water and the like adsorbed on the tubes 1 and 2.

Then, after checking the leak in the reactor, the flow rate of each raw material gas is set, and while each gas is allowed to flow in the reaction furnace 11, the growth pressure is stabilized by N ₂ ballast. At this time, the BCl ₃ partial pressure is determined by the relationship between the growth pressure, the total flow rate, and the ratio of the BCl ₃ flow rate. However, as described above, the growth pressure greatly affects the film thickness uniformity within the surface of the wafer 4.
Controlling the BCl ₃ partial pressure by increasing or decreasing the ₃ flow. Then, after the growth pressure in the reaction furnace 11 becomes stable, film formation is performed.

[0017] After the deposition is completed, the flow of the reaction gas is stopped, the pipe was cycle purged with N _2, returning the reactor (reactor 11) with N ₂ to atmospheric pressure. After returning to atmospheric pressure, the boat 3 is unloaded and the wafer 4 is naturally cooled.
Finally, the wafer 4 is taken out from the boat 3.

An example of the embodiment is shown below.

Boron-doped silicon germanium was deposited on an 8-inch wafer using the substrate processing apparatus shown in FIG.

The film forming conditions in this case are the film forming temperature of 450 to 5
00 ° C., growth pressure 30-120 Pa, GeH_Four/ SiH
_Four= 0.038, BCl_Three/ SiH_Four= 0.00001
It was set to 7 to 0.028. In addition, these ratios (GeH_Four/
SiH_Four, BCl_Three/ SiH _Four) Are SiH
_FourAgainst GeH_Four, BCl_ThreeThe flow rate ratio of is shown.

In FIG. 3, the partial pressure of boron trichloride is 1.02 ×
Within the range of 10 ^{−4 to} 2 (Pa), 0.05 to
The relationship between the partial pressure of boron trichloride and the boron concentration up to 2 Pa is shown.

As shown in FIG. 3, it was found that the boron trichloride partial pressure increased monotonically and the boron concentration was almost saturated at the boron trichloride partial pressure "a" point. This point is near the solid solution limit region of boron taken into the silicon germanium film. Therefore, by setting the partial pressure of boron trichloride to the partial pressure at the point "a", that is, 0.1 Pa or more, boron can be doped to the maximum extent. Further, it can be seen from this that an arbitrary boron concentration can be obtained by controlling the partial pressure of boron trichloride.

FIG. 4 is a diagram showing the relationship between the boron concentration and the resistivity immediately after the formation of the boron-doped silicon germanium film doped with boron trichloride. From the figure, it can be seen that the resistivity decreases as the boron concentration increases. On the contrary, as the boron concentration decreases, the resistivity increases, and when the boron concentration is lower than the "b" point, the resistivity becomes too high, which is not preferable. When the boron concentration is higher than the “c” point, the boron concentration increases,
The resistivity tends to be high, which is not preferable. From these facts, it can be said that the boron concentration range between the “b” point and the “c” point is suitable for the gate electrode that requires low resistance. The boron concentrations at points "b" and "c" in FIG. 4 correspond to the boron concentrations at points "d" and "e" in FIG. Therefore, in the silicon germanium film having a boron concentration range suitable for the gate electrode as described above, the partial pressure of boron trichloride is divided by the partial pressure at point “d” in FIG. It can be seen that the film is formed by setting the pressure to 1 Pa or less. It should be noted that even if the partial pressure of boron trichloride is made larger than 1 Pa, the boron concentration in the film only slightly increases as shown in FIG. 3, and moreover, as shown in FIG. As the rate increases, it is not practically advantageous.

From this, the partial pressure of boron trichloride is
It can be seen that a silicon germanium film having a boron concentration suitable for the gate electrode can be obtained by setting it to 0.2 Pa or more and 1 Pa or less. The resistivity of such a silicon germanium film is realized immediately after film formation at a film formation temperature of 450 to 500 ° C., and from this fact, high temperature (5
It can be seen that a low-resistance silicon germanium film can be formed only by a low-temperature (500 ° C. or lower) treatment step without using an annealing treatment step at a temperature higher than 00 ° C.).

Incidentally, if the above-mentioned film forming conditions are appropriately determined, either amorphous or poly film formation is possible.

As described above, according to the present invention, in a semiconductor manufacturing method and a substrate processing apparatus for forming a film of boron-doped polysilicon germanium or boron-doped amorphous silicon germanium in a vertical decompression CVD apparatus, boron trichloride is used. A method of manufacturing a semiconductor device and a substrate processing apparatus capable of obtaining a boron concentration suitable for a gate electrode by controlling the partial pressure of and reducing resistance at low temperature without using a high temperature annealing process. Can be provided.

[0027]

According to the present invention, a method of manufacturing a semiconductor device and a substrate processing apparatus capable of forming a film of boron-doped polysilicon germanium or boron-doped amorphous silicon germanium having an appropriate boron concentration by a low pressure CVD method. Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a reactor structure of a vertical decompression CVD apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a film forming procedure by a low pressure CVD method.

FIG. 3 is a diagram showing a relationship between a partial pressure of boron trichloride and a boron concentration in a silicon germanium film during a film forming process.

FIG. 4 is a diagram showing a relationship between a boron concentration in a silicon germanium film and a silicon germanium film resistivity.

[Explanation of symbols]

1 ... Outer tube, 2 ... Inner tube, 3 ... Boat, 4 ... Wafer, 5 ... Heat insulating plate, 6 ... Heater, 7 ... Mechanical booster pump, 8 ... Dry pump, 9 ... Boat rotating shaft, 10 ... Stainless lid, 11 ... Reactor, 12 ...
Midway supply nozzle, 13 ... SiH ₄ + GeH ₄ nozzle, 1
4 ... BCl ₃ nozzle, 15 ... Pressure gauge, 16 ... N ₂ ballast valve, 17 ... Controller.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4K030 AA03 AA05 AA06 AA20 BA08                       BA26 BA29 BA30 BA35 BB03                       FA10 HA15 JA09 KA41                 5F045 AA06 AB01 AC01 AC19 DA57                       DP19 DQ05 EE15

Claims (2)

[Claims] 1. Using monosilane and monogermane as a reaction gas, and by a low pressure CVD method in a reaction furnace,
In a method of manufacturing a semiconductor device in which boron-doped polysilicon germanium or boron-doped amorphous silicon germanium is formed on a substrate, boron trichloride is used as a doping gas, and the partial pressure of the boron trichloride at the time of film formation is 0.2 Pa or more. A method for manufacturing a semiconductor device, which is set to 1 Pa or less. 2. A reaction tube for processing a substrate, a heater for heating the substrate in the reaction tube, a nozzle for supplying monosilane as a film forming gas into the reaction tube, and a monogermane as a film forming gas. For supplying boron trichloride as a doping gas, an exhaust pipe for exhausting the inside of the reaction tube, and a partial pressure of the boron trichloride at the time of film formation are controlled to 0.2 Pa or more and 1 Pa or less. A substrate processing apparatus comprising: a controller.