JPH0834192B2 - Heat treatment furnace for semiconductor wafers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention [Field of Industrial Application] The present invention relates to a heat treatment furnace for semiconductor wafers, and in particular,
The opening of the furnace core tube body is opened and closed and the supply gas to the furnace core tube body is selected according to the result of detecting the total gas pressure, hydrogen partial pressure, and oxygen partial pressure of the exhaust gas discharged from the furnace core tube body. The present invention relates to a heat treatment furnace for semiconductor wafers.

[Prior Art] Conventionally, as a heat treatment furnace for this type of semiconductor wafer,
For example, after accommodating the inner space of the furnace core tube main body surrounded by the soaking tube, the heating member, and the heat insulating tube in a state of being supported by a wafer heat treatment jig placed on the furnace lid main body, There has been proposed a semiconductor wafer heat treatment furnace in which a semiconductor wafer is subjected to appropriate heat treatment by supplying the heat treatment gas.

[Problems to be Solved] However, in the conventional heat treatment furnace for semiconductor wafers, when hydrogen gas is used as the heat treatment gas, (i)
Incomplete sealing of the opening of the furnace core tube body has the drawback that oxygen gas will enter the internal space of the furnace core tube body, and (ii) the furnace core when the semiconductor wafer is taken in and out of the furnace core tube body. There is also a drawback that the opening of the furnace core tube body is opened in the state where hydrogen gas remains because the scavenging by the inert gas (nitrogen gas etc.) of the inner space of the tube body is incomplete, resulting in (iii) furnace There is a drawback that oxygen gas and hydrogen gas react with each other in the inner space of the core tube body to cause an explosion.

Therefore, in order to eliminate these drawbacks, the present invention provides an opening of the furnace core tube body according to the result of detecting the total gas pressure, the hydrogen partial pressure, and the oxygen partial pressure of the exhaust gas discharged from the furnace core tube body. It is intended to provide a heat treatment furnace for semiconductor wafers, in which a portion is opened and closed and a supply gas to the furnace core tube main body is selected.

(2) Configuration of the Invention [Means for Solving the Problems] The means for solving the problems provided by the present invention include: “In the inner space of the furnace core tube body surrounded by the heating member and supplied with hydrogen gas as the heat treatment gas; On the other hand, in a heat treatment furnace for semiconductor wafers, in which the semiconductor wafer is heat-treated by closing the open end of the furnace core tube main body with the furnace lid in a state where the semiconductor wafer is supported and accommodated in a wafer heat treatment jig, A detector for detecting the hydrogen partial pressure, oxygen partial pressure, and total gas pressure of the exhaust gas discharged from the furnace core tube body, and (b) the hydrogen partial pressure, oxygen partial pressure, and total gas detected by the detector. A control circuit for generating first to third control signals in response to the pressure, and (c) opening and closing a furnace lid arranged at the open end of the furnace core body in response to the first control signal. A driving device for ) A heat treatment furnace for semiconductor wafers, comprising: a gas selection device for selecting a supply gas to the inner space of the furnace core tube body in accordance with second and third control signals.

[Operation] In the semiconductor wafer heat treatment furnace according to the present invention, the semiconductor wafer is supported by the wafer heat treatment jig in the inner space of the furnace core tube body surrounded by the heating member and supplied with hydrogen gas as the heat treatment gas. A heat treatment furnace for semiconductor wafers, in which a semiconductor wafer is heat-treated by closing an open end of a furnace core tube body with a furnace lid in a housed state, in particular, hydrogen of exhaust gas discharged from the furnace core tube body. The partial pressure, the oxygen partial pressure, and the total gas pressure are detected by the detection device, and the control circuit detects the first partial pressure, the third partial pressure, the oxygen partial pressure, and the total gas pressure. A control signal is generated, and in response to the first control signal, the drive device opens and closes the furnace lid arranged at the open end of the furnace core tube main body.
Since the gas selection device selects the supply gas for the internal space of the furnace core tube body in accordance with the control signal of (1), (i) oxygen is supplied to the internal space of the furnace core tube body during the period when hydrogen gas is present. It has the function of preventing accidental intrusion of gas, and (ii) has the function of immediately eliminating hydrogen gas even when an abnormality such as a crack occurs in the core tube body, and (iii) the core tube. It acts to prevent an explosion accident that accompanies the reaction between hydrogen gas and oxygen gas in the internal space of the main unit.

[Examples] Next, a heat treatment furnace for semiconductor wafers according to the present invention will be specifically described with reference to the accompanying drawings and preferred examples thereof. However, the examples described below are provided for facilitating or facilitating the understanding of the present invention, and not for limiting the present invention. In other words, each member disclosed in the embodiments described below includes all design changes and equivalent replacements within the spirit and technical scope of the present invention.

(Description of the accompanying drawings) FIG. 1 is a cross-sectional view showing an embodiment of a heat treatment furnace for semiconductor wafers according to the present invention, and particularly, a vertical heat treatment furnace.
10 is illustrated, the open end 21 of the furnace core tube body 21
The state where A is closed by the furnace lid body 71 is shown.

(Structure of Embodiment) First, the structure of an embodiment of a semiconductor wafer heat treatment furnace according to the present invention will be described in detail with reference to FIG. Although a vertical heat treatment furnace is illustrated in FIG. 1 as a heat treatment furnace for semiconductor wafers according to the present invention for the sake of simplicity of the following description, the present invention is not intended to be limited thereto.

10 disposed is a vertical heat treatment furnace of a semiconductor wafer according to the present invention, a furnace core tube device 20 for heat treating semiconductor wafers, optionally via an appropriate gap around the furnace core tube 20 a soaking tube 30 for facilitating securing a soaking section in which a furnace core tube 20 is, the soaking tube 30 generates heat by power supplied from an external power source is disposed around the liner tube 30 thermal insulation pipe 50 in order to prevent over heating member 40 for heating the furnace tube device 20, that the heat generated by which the heating member 40 is disposed around the heating member 40 from escaping to the external environment A housing 60 formed of an appropriate material such as stainless steel for holding the furnace core tube device 20 or the heat insulating tube 50 , and closing the opening of the furnace core tube device 20 to isolate the internal space 21A from the external environment. Furnace cover device 70 for
And the heat treatment gas supplied to the furnace core tube apparatus 20 according to the exhaust gas discharged from the furnace core tube apparatus 20, which is arranged for the furnace core tube apparatus 20 and the furnace lid apparatus 70 , and the furnace. Lid device
And a control circuit 80 for generating a control signal required to raise and lower 70 .

The furnace core tube device 20 is formed of an appropriate material such as quartz, and a furnace core tube main body 21 for heat-treating a semiconductor wafer in a soaking region formed in the internal space 21A, and a furnace from the outside of the heat insulating tube 50. After extending to the outer peripheral surface of the core tube main body 21 and then extending to the top along the outer peripheral surface of the furnace core tube main body 21 and opening to the internal space 21A at the top, an appropriate heat treatment gas (for example, hydrogen gas) or Gas supply pipe 22 for supplying scavenging gas (for example, nitrogen gas) as a supply gas
And the furnace core tube main body 21 provided for the gas supply pipe 22.
Control signal S to control the supply gas supplied to the internal space 21A of
₁₁ , a gas selection device 23 for selecting according to S ₁₂ , and a heat insulating pipe 50 opened near the open end 21B of the furnace core body 21.
Of the heat treatment gas or scavenging gas that has been extended to the outside of the furnace core tube body 21 and is exhausted from the inner space 21A of the furnace core tube body 21 toward the outside, and the open end of the furnace core tube body 21. Housing 6 is formed on the peripheral surface of part 21B.
It has a supporting projection 25 for supporting by 0 . Of the gas supply pipe 22 and the gas discharge pipe 24, the furnace core tube main body
Each of the parts located near 21 is formed of a material such as quartz that can be used at high temperature, as much as possible.
preferable.

Liner tube 30 is arranged so as to surround have been prepared, the total length of the furnace core tube 20 to ensure or extend the soaking zone of the furnace core tube 20 by a suitable material such as silicon carbide.

The heating member 40 is arranged outside the soaking tube 30 , and is appropriately arranged to form and secure a soaking area along the axial direction in the internal space 21A of the furnace core tube device 20. There is.

The heat insulating tube 50 is made of an appropriate heat insulating material such as glass fiber, and surrounds the furnace core tube device 20 , the soaking tube 30, and the heating member 40 as a whole.

The housing 60 includes a support member main body 61 for supporting the lower ends of the heat equalizing pipe 30 and the heat insulating pipe 50 on the upper surface, and a support member main body.
A furnace core tube main body for supporting the lower surface of a support projection 25 formed around the opening end 21B of the furnace core tube main body 21 by the step end surface of the central opening 62a attached to the lower surface of 61. Support member 62 and central opening 62a of core tube main body support member 62
An O-ring 63 that is disposed in a disposition groove formed on the peripheral surface of the stepped portion and that seals between the support projection 25 formed on the peripheral surface of the open end 21B of the furnace core body 21. And is attached to the lower surface of the support member 61 to surround the periphery of the furnace core tube main body support member 62 and the furnace lid device 70 to open the end 21 of the core tube main body 21.
An opening 64a is formed in the center to allow the end face of B to approach and separate from the end face of B, and the heat treatment gas leaked along with the opening and closing of the furnace core tube body 21 when the furnace lid device 70 is moved up and down. Alternatively, a gas capturing member 64 for capturing scavenging gas
And a gas discharge pipe 65 having one end opened at the side surface of the gas capturing member 64 and for discharging the leaked gas captured by the gas capturing member 64 toward the outside.

The furnace lid device 70 is made of a high-purity material that can be used at high temperature, such as quartz or silicon carbide, that is in direct contact with the end surface of the open end 21B of the furnace core body 21.
A furnace lid holding member 72 made of an appropriate material such as stainless steel for holding the furnace lid main body 71, and the furnace lid holding member 72.
The lower surface of the furnace lid body 71 is supported via an elastic member (not shown), and the furnace lid body 71 is moved toward and away from the open end portion 21B of the furnace core tube body 21 via the opening portion 64a of the gas capturing member 64. For moving the furnace lid moving member 73 and one end of the furnace lid moving member 73 and driven by the drive device 74 according to the control signal S ₁₃ to move the furnace lid moving member 73 up and down. Like the shaft 75 and the drive shaft 75, the furnace lid moving member
A guide shaft 76 that is provided for one end of the furnace lid moving member 73 to stabilize the vertical movement of the furnace lid moving member 73, and the furnace lid body 71 on the lower end surface of the open end 21B of the furnace core body 21. When the upper surface is abutted, the upper surface of the furnace lid holding member 72 and the furnace core tube main body supporting member
Furnace lid holding member to ensure a seal with the underside of 62
It also includes an O-ring 77 disposed in a disposition groove formed on the upper surface of 72.

The control circuit 80 is provided for the gas exhaust pipe 24 and has an oxygen partial pressure sensor for measuring an oxygen partial pressure P _O contained in the exhaust gas and a hydrogen partial pressure for detecting the hydrogen partial pressure P _H. A gas pressure detection device 81 including a pressure sensor and a total gas pressure sensor for detecting the total gas pressure P of exhaust gas, and a gas pressure detection device
The control signals S ₁₁ and S ₁₂ for controlling the gas selection device 23 and the drive device 74, which are connected to 81, are used to control the gas selection device 23 in accordance with the detection results (that is, oxygen partial pressure P _O , hydrogen partial pressure P _H and total gas pressure P). Control circuit 8 for generating another control signal S ₁₃ for controlling
It contains 2 and.

(Operation of Embodiment) Further, regarding one embodiment of the heat treatment furnace for semiconductor wafers according to the present invention, the operation will be described in detail with reference to the vertical heat treatment furnace illustrated in FIG. 1 and with reference to Table 1. Explained.

Scavenging operation ...... Hydrogen gas elimination ...... Nitrogen gas atmosphere The control circuit 82 first maintains the control signal S ₁₁ at a low level before starting a series of work related to the heat treatment of the semiconductor wafer in the internal space 21A of the furnace core body 21. Meanwhile, the control signal S _{12 is set} to the high level.

The gas selection device 23 starts the supply of nitrogen gas in response to the control signal S ₁₂ becoming high level.

The nitrogen gas is guided by the gas supply pipe 22 as shown by the arrow A, and then supplied from the top of the furnace core tube main body 21 toward the internal space 21A thereof.

The nitrogen gas supplied to the inner space 21A of the furnace core tube body 21 moves inside the inner space 21A as indicated by arrow B, and then is guided toward the gas discharge pipe 24 as indicated by arrow C. Along with this, the residual gas (for example, hydrogen gas) filled in the internal space 21A of the furnace core tube main body 21 becomes
Scavenged towards 24.

The nitrogen gas and the hydrogen gas are discharged to the outside of the furnace core tube main body 21 by the gas discharge pipe 24 as shown by an arrow D.

As the scavenging of hydrogen gas with nitrogen gas progresses, the hydrogen partial pressure P _H detected by the gas pressure detection device 81 gradually decreases.

Furnace entry operation When the internal space 21A of the furnace core tube body 21 is filled with nitrogen gas, the hydrogen partial pressure P _H becomes lower than the reference hydrogen partial pressure _H. In response to this, the control circuit 82 sets the control signal S ₁₃ to the high level for a predetermined period.

The drive device 74 drives the drive shaft 75 in response to the high level of the control signal S ₁₃ to move the furnace lid moving member 73 in the arrow Y direction and lower it to a predetermined position. , And move in the direction of the arrow X to raise it to the initial position.

At this time, in the lowered position, the wafer heat treatment jig (not shown) holding the semiconductor wafer is held by the furnace lid main body 71 held by the furnace lid moving member 73 by an appropriate working tool.
Therefore, when the furnace lid moving member 73 is raised to the initial position, the semiconductor wafer to be heat-treated is inserted into the internal space 21A of the furnace core tube body 21.

Scavenging operation: Oxygen gas elimination In order to scavenge the oxygen gas that has entered when the wafer heat treatment jig is inserted even after the opening 21B is closed in the inner space 21A of the furnace core tube body 21 by the furnace lid body 71. Then, nitrogen gas is continuously supplied. As a result, nitrogen gas such as oxygen gas is gradually scavenged through the gas discharge pipe 24.

The control circuit 82 uses the oxygen partial pressure detected by the gas pressure detection device 81.
As long as P _O exceeds the reference oxygen partial pressure _O , the control signal S ₁₂
Maintain a high level.

Therefore, the gas selection device 23 continues to supply the nitrogen gas to the internal space 21A of the furnace core tube body 21 until the oxygen partial pressure P _O becomes lower than the reference oxygen partial pressure _O.

Scavenging operation: Oxygen partial pressure P _O detected by nitrogen gas elimination gas pressure detection device 81
Is smaller than the reference oxygen partial pressure _O , the control circuit 82
Causes the control signal S ₁₁ to be high level and the control signal S ₁₂ to be low level.

The gas selection member 23 stops the supply of nitrogen gas in response to the control signal S ₁₂ becoming low level, and then supplies the hydrogen gas in response to the control signal S ₁₁ becoming high level. Start.

The hydrogen gas is guided by the gas supply pipe 22 as shown by an arrow A, and then supplied from the top of the furnace core tube main body 21 toward the internal space 21A thereof.

The hydrogen gas supplied to the internal space 21A of the furnace core body 21 moves inside the internal space 21A as indicated by arrow B, and is then guided toward the gas discharge pipe 24 as indicated by arrow C. Along with this, the nitrogen gas filling the internal space 21A of the furnace core tube body 21 is scavenged toward the gas discharge pipe 24.

The nitrogen gas and the hydrogen gas are discharged to the outside of the furnace core tube main body 21 by the gas discharge pipe 24 as shown by an arrow D.

When progresses scavenging of the nitrogen gas with hydrogen gas, a hydrogen partial pressure P _H being sensed by the gas pressure detecting device 81 is gradually increased.

Heat treatment operation After the hydrogen partial pressure P _H detected by the gas pressure detection device 81 becomes larger than the reference hydrogen partial pressure _H and the total gas pressure P becomes larger than the reference total gas pressure, the heat treatment operation of the semiconductor wafer is started. To be done.

That is, an appropriate heat treatment gas (eg, argon gas) starts to be supplied together with hydrogen gas from the gas selection device 23 to the internal space 21A of the furnace core tube body 21 via the gas supply pipe 22.

As a result, the semiconductor wafer held by the wafer heat treatment jig is appropriately heat-treated in the internal space 21A of the furnace core tube body 21.

Here, the reason why the total gas pressure P detected by the gas pressure detection device 81 is maintained higher than the reference total gas pressure is that oxygen gas enters from the outside when an abnormality such as a crack occurs in the furnace core body 21. To avoid doing.

Scavenging operation ... Hydrogen gas elimination When the heat treatment operation of the semiconductor wafer is completed, the supply of the heat treatment gas from the gas selector 23 to the internal space 21A of the furnace core tube body 21 is stopped, and the furnace core tube body 21 is not cracked or otherwise abnormal. When it occurs, hydrogen gas leaks from the furnace core tube main body 21, so that the total gas pressure P detected by the gas pressure detection device 81 becomes smaller than the reference total gas pressure. In response to this, the control circuit 82 sets the control signal S ₁₁ to the low level and
₁₂ is a high level.

The gas selection device 23 stops the supply of hydrogen gas in response to the low level of the control signal S ₁₁ , and then supplies the nitrogen gas in response to the high level of the control signal S _12. Start.

The nitrogen gas is guided by the gas supply pipe 22 as shown by the arrow A, and then supplied from the top of the furnace core tube main body 21 toward the internal space 21A thereof.

The nitrogen gas supplied to the inner space 21A of the furnace core tube body 21 moves inside the inner space 21A as indicated by arrow B, and then is guided toward the gas discharge pipe 24 as indicated by arrow C. Along with this, the hydrogen gas filled in the internal space 21A of the furnace core body 21 is scavenged toward the gas discharge pipe 24.

The nitrogen gas and the hydrogen gas are discharged to the outside of the furnace core tube main body 21 by the gas discharge pipe 24 as shown by an arrow D.

As the scavenging of hydrogen gas with nitrogen gas progresses, the hydrogen partial pressure P _H detected by the gas pressure detection device 81 gradually decreases.

When the internal space 21A of the furnace core tube body 21 is filled with nitrogen gas, the hydrogen partial pressure P _H becomes lower than the reference hydrogen partial pressure _H. In response to this, the control circuit 82 controls the control signal S ₁₃
Is set to a high level for a predetermined period.

The drive device 74 drives the drive shaft 75 in response to the high level of the control signal S ₁₃ to move the furnace lid moving member 73 in the arrow Y direction and lower it to a predetermined position. , And move in the direction of the arrow X to raise it to the initial position.

The jig for wafer heat treatment should be placed in its lowered position. Then, it is unloaded from the furnace lid main body 71 held by the furnace lid moving member 73 by an appropriate working tool, so that the heat-treated semiconductor wafer is taken out from the internal space 21A of the furnace core tube main body 21.

(Modification) In the above description, the furnace lid 71 of the furnace lid device 70 is the furnace core tube main body 21.
Although the case of directly contacting the end surface of the open end 21B of the above has been described, the present invention is not limited to this, and the furnace lid of the furnace lid device is only on the lower surface of the furnace core tube main body supporting member. It is also included when contacted.

(3) Effects of the Invention As is clear from the above, the semiconductor wafer heat treatment furnace according to the present invention is a semiconductor wafer with respect to the internal space of the furnace core tube body surrounded by the heating member and supplied with hydrogen gas as the heat treatment gas. Is a heat treatment furnace for semiconductor wafers, in which the semiconductor wafer is heat-treated by closing the open end of the furnace core tube main body with the furnace lid in a state of being supported and accommodated in a wafer heat treatment jig, The hydrogen partial pressure, oxygen partial pressure, and total gas pressure of the exhaust gas discharged from the pipe main body are detected by the detection device, and the hydrogen partial pressure, oxygen partial pressure, and total gas pressure detected by the detection device are respectively detected. The control circuit generates the first to third control signals, and the drive device opens and closes the furnace lid arranged at the open end of the furnace core tube body in response to the first control signal. Control core tube depending on control signal Since the gas to be supplied to the internal space of the body is selected by the gas selection device, (i) Oxygen gas is prevented from accidentally intruding into the internal space of the furnace core tube main body while hydrogen gas is present. It has the effect that (ii) hydrogen gas can be immediately eliminated even when an abnormality such as a crack occurs in the core tube main body, and (iii) hydrogen gas in the internal space of the core tube main body It has the effect of preventing an explosion accident that accompanies the reaction with oxygen gas.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a heat treatment furnace for semiconductor wafers according to the present invention. 10 …… Vertical heat treatment furnace 20 …… Furnace core tube device 21 …… Furnace core tube main body 21A …… Internal space 21B …… Opening end 22 …… Gas supply pipe 23 …… Gas selection device 24 …… Gas exhaust pipe 25 …… Supporting protrusion 30 …… Soaking tube 40 …… Heating member 50 …… Insulation tube 60 …… Housing 61 …… Supporting member body 62 …… Reactor core tube supporting member 62a …… Opening 63 …… O ring 64 …… Gas trapping member 64a …… Opening 65 …… Gas discharge pipe 70 …… Furnace lid device 71 …… Furnace lid holding member 73 …… Furnace lid moving member 74 …… Driving device 75… … Drive shaft 76 …… Guide shaft 77 …… O-ring 80 …… Control device 81 …… Gas pressure detection device 82 …… Control circuit

Claims (1)

[Claims] 1. A furnace core with a furnace lid in a state where a semiconductor wafer is supported and accommodated in a wafer heat treatment jig in an inner space of a furnace core tube body surrounded by a heating member and supplied with hydrogen gas as a heat treatment gas. (A) Hydrogen partial pressure, oxygen partial pressure, and total gas pressure of exhaust gas discharged from the furnace core tube body in a semiconductor wafer heat treatment furnace in which a semiconductor wafer is heat-treated by closing the open end of the tube body. And (b) a control circuit for generating first to third control signals in accordance with the hydrogen partial pressure, the oxygen partial pressure, and the total gas pressure detected by the detection device, respectively. , (C) a drive device for opening and closing the furnace lid arranged at the open end of the furnace core tube body in response to the first control signal, and (d) furnace in response to the second and third control signals. Select the supply gas for the inner space of the core tube body Heat treatment furnace of a semiconductor wafer, comprising by comprising a because of the gas selection device.