JP2010087019A - Method for manufacturing semiconductor device, thermal oxidizing processing method, and thermal oxidizing processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device, a thermal oxidizing processing method, and a thermal oxidizing processing apparatus which enable the formation of a gate oxide film having a highly uniform film thickness with respect to the thermal oxidizing processing method. <P>SOLUTION: The method for manufacturing the semiconductor device includes the steps of: setting the back surface of a monitor wafer M1 counter to the front surface of a first product wafer #2; setting the back surface of the first product wafer #2 counter to the front surface of a second product wafer #3; placing the monitor wafer M1 and the first and second product wafers #2 and #3 with silicon nitride films 23 formed on their respective back surfaces in the thermal oxidizing processing apparatus; and forming a thermal oxide film on the surfaces of the monitor wafer M1 and the first and second product wafers #2 and #3 by the thermal oxidizing processing apparatus. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor device manufacturing method, a thermal oxidation processing method, a thermal oxidation processing device, and the like, and in particular, a semiconductor device manufacturing method capable of forming a highly uniform gate oxide film between semiconductor wafers, The present invention relates to an oxidation treatment method and a thermal oxidation treatment apparatus.

  FIG. 9 is a schematic diagram for explaining a conventional wafer arrangement in a wafer holder of a vertical thermal oxidation processing apparatus. An unillustrated wafer holder (not shown) is installed in the vertical thermal oxidation processing apparatus, and a monitor wafer M1 and a plurality of product wafers # 2 to # 6 are held in the wafer holder.

  In a process in which a semiconductor device has two or more gate oxide film thicknesses, an antioxidant film such as a SiN film 23a is used for the semiconductor wafer 32 in order to separate the thicknesses of the respective gate oxide films. Thus, two or more types of gate oxide films can be formed by applying a selective oxidation process using the SiN film 23a in a vertical thermal oxidation processing apparatus (not shown).

  In the thermal oxidation process by selective oxidation, first, a SiN film 23 a is formed on the entire surface of the product wafer 21. At this time, the SiN film 23 is simultaneously formed on the entire back surface of the product wafer 21. Next, the SiN film 23a on the product wafer 21 is processed by a photolithography method and a dry etching method. As a result, the opening 25 is formed only on the region desired to be selectively oxidized on the product wafer 21. Further, since the back surface of the product wafer 21 is not exposed to plasma during dry etching, the SiN film 23 remains on the entire back surface.

  Next, a plurality of product wafers 21 are collectively held on a wafer holder (not shown) in a vertical thermal oxidation processing apparatus (not shown). As shown in FIG. 9, a monitor wafer (M1) 30 is held at the top of the wafer holder, and the second and subsequent wafer holders are in the order of # 2, # 3, # 4, # 5, # 6,. A plurality of product wafers 21 are held in order from the top. At this time, the surface of the product wafer 21 held by # 3 of the wafer holder faces the SiN film 23 remaining on the back surface of the product wafer 21 held by # 2 of the wafer holder. Further, the product wafers held in the order of # 4, # 5, # 6. That is, when a plurality of product wafers 21 are collectively held on the wafer holder in the vertical thermal oxidation processing apparatus, the front surface of the product wafer 21 and the back surface of the product wafer 21 on which the SiN film 23 remains face each other.

  The monitor wafer 30 held at the top of the wafer holder is prepared for managing the thickness of the oxide film formed in the vertical thermal oxidation processing apparatus. For example, a film is formed. The processing is performed simultaneously with the product wafer 21 using a non-silicon wafer as a monitor wafer. Thereby, the film forming ability of the vertical thermal oxidation processing apparatus is managed.

  As described above, a wafer holder (not shown) holding the monitor wafer and the plurality of product wafers 21 is inserted into a vertical thermal oxidation processing apparatus (not shown), and the product wafer 32 is subjected to thermal oxidation processing (for example, a patent). Reference 1).

JP-A-10-189565 (0007 to 0012)

  In the conventional selective oxidation process, the SiN film 23 remains on the back surface of the product wafer 21 by processing the SiN film by a dry etching method. As a result, as shown in FIG. 9, the product in which the SiN film 23 remains on the surfaces of the product wafers # 3, # 4, # 5, # 6... Held in the third and subsequent wafer holders. It faces the back surface of wafers # 2, # 3, # 4, # 5. On the other hand, the SiN film is not left on the surface of the top product wafer # 2 among the plurality of product wafers # 2, # 3, # 4, # 5, # 6. It faces the back surface of the wafer M1. That is, the front surface of the product wafer # 2 is different from the other product wafers # 3, # 4, # 5, and # 6 in that it faces the back surface of the silicon wafer 30 on which no SiN film is formed. For this reason, the oxidation rate of the product wafer # 2 may be different from that of the product wafers # 3, # 4, # 5, and # 6.

  As described above, when a plurality of semiconductor wafers are subjected to thermal oxidation simultaneously, if product wafer # 2 and other product wafers # 3, # 4, # 5, and # 6 have different oxidation rates, product wafer # 2 2 and other product wafers # 3, # 4, # 5, and # 6, the thickness uniformity of the thermal oxide film is deteriorated. As a result, the product characteristics of the product wafer # 2 are different from those of the other product wafers # 3, # 4, # 5, and # 6, the gate is formed with a thin film thickness, and the film thickness is very strictly controlled. There is a possibility of causing off-specification in oxide film formation. As a result, the yield decreases.

  Aspects according to the present invention are a method for manufacturing a semiconductor device, a thermal oxidation treatment method, and a thermal oxidation treatment apparatus capable of forming a gate oxide film with high film thickness uniformity between semiconductor wafers.

In order to solve the above-described problem, a method for manufacturing a semiconductor device according to one embodiment of the present invention makes a back surface of a monitor wafer and a front surface of a first product wafer face each other, and the back surface of the first product wafer and a second surface of the first product wafer. Placing the surface of the product wafer in a thermal oxidation apparatus in a state where a silicon nitride film is formed on the back surface of each of the monitor wafer and the first and second product wafers;
Forming a thermal oxide film on the surface of each of the monitor wafer and the first and second product wafers by the thermal oxidation processing apparatus;
It is characterized by comprising.

  According to the semiconductor device manufacturing method, the back surface of the monitor wafer and the front surface of the first product wafer are made to face each other, and the back surface of the first product wafer and the front surface of the second product wafer are made to face each other. A thermal oxide film is formed on the surface of each of the first and second product wafers. Thereby, the 1st and 2nd product wafer arrange | positioned in a thermal oxidation processing apparatus can be made into the state facing the surface in which the silicon nitride film was formed, and the 1st and 2nd product wafer was made into the same conditions. Can be processed below. As a result, in the gate oxide film whose film thickness is strictly controlled, the film thickness uniformity between product wafers can be improved, and the reduction in yield can be suppressed.

According to another aspect of the present invention, there is provided a method for manufacturing a semiconductor device, wherein a back surface of a monitor wafer and a front surface of a dummy wafer are opposed, a back surface of the dummy wafer is opposed to a front surface of a first product wafer, and the first product wafer is formed. And disposing the second product wafer in the thermal oxidation apparatus in a state where a silicon nitride film is formed on the respective back surfaces of the dummy wafer and the first and second product wafers. ,
Forming a thermal oxide film on the surface of each of the monitor wafer and the first and second product wafers by the thermal oxidation processing apparatus;
It is characterized by comprising.

  According to the method for manufacturing a semiconductor device, the back surface of the monitor wafer and the front surface of the dummy wafer are made to face each other, the back surface of the dummy wafer and the front surface of the first product wafer are made to face each other, and the back surface of the first product wafer and The surfaces of the two product wafers are opposed to each other and placed in a thermal oxidation processing apparatus, and a thermal oxide film is formed on the surface of each of the first and second product wafers. Thereby, the first and second product wafers arranged in the thermal oxidation processing apparatus can be brought into a state facing the surface on which the silicon nitride film is formed. Can be processed under the same conditions.

  In the method for manufacturing a semiconductor device according to one embodiment of the present invention, the thermal oxide film is preferably a gate oxide film.

  In the method for manufacturing a semiconductor device according to one embodiment of the present invention, the thermal oxidation processing apparatus may be a vertical or horizontal thermal oxidation processing apparatus.

In the thermal oxidation method according to one aspect of the present invention, the back surface of the monitor wafer faces the front surface of the first product wafer, and the back surface of the first product wafer faces the front surface of the second product wafer, And it arrange | positions in a thermal oxidation processing apparatus in the state in which the silicon nitride film was formed in the back surface of each of the said monitor wafer and said 1st and 2nd product wafer,
A thermal oxide film is formed on the surface of each of the monitor wafer and the first and second product wafers by the thermal oxidation processing apparatus.

In the thermal oxidation method according to one aspect of the present invention, the back surface of the monitor wafer faces the front surface of the dummy wafer, the back surface of the dummy wafer faces the front surface of the first product wafer, and the first product wafer The back surface and the front surface of the second product wafer are opposed to each other, and the dummy wafer and the first and second product wafers are disposed in the back surface of the first and second product wafers in a thermal oxidation processing apparatus,
A thermal oxide film is formed on the surface of each of the monitor wafer and the first and second product wafers by the thermal oxidation processing apparatus.

In the thermal oxidation processing apparatus according to one aspect of the present invention, the back surface of the monitor wafer and the front surface of the first product wafer are opposed to each other, and the back surface of the first product wafer and the front surface of the second product wafer are opposed to each other. A wafer holder to hold
A chamber into which the wafer holder is inserted;
A gas introduction mechanism for introducing oxygen gas into the chamber;
A heater for heating the inside of the chamber;
Comprising
A thermal oxide film is formed on the surface of each of the monitor wafer and the first and second product wafers with a silicon nitride film formed on the back surface of each of the monitor wafer and the first and second product wafers. It is characterized by that.

In the thermal oxidation processing apparatus according to one aspect of the present invention, the back surface of the monitor wafer faces the front surface of the dummy wafer, the back surface of the dummy wafer faces the front surface of the first product wafer, and the first product wafer A wafer holder for holding the back surface and the surface of the second product wafer so as to face each other;
A chamber into which the wafer holder is inserted;
A gas introduction mechanism for introducing oxygen gas into the chamber;
A heater for heating the inside of the chamber;
Comprising
A thermal oxide film is formed on the surface of each of the monitor wafer, the first product wafer, and the second product wafer in a state where a silicon nitride film is formed on the back surface of each of the monitor wafer, the dummy wafer, and the first and second product wafers. It is characterized by forming.

A method for manufacturing a semiconductor device according to one embodiment of the present invention includes a first monitor wafer in which a first silicon nitride film is formed on the back surface, a second silicon nitride film on the back surface, and the first silicon on the surface. Providing a first product wafer having a nitride mask formed thereon, and a second product wafer having a third silicon nitride film formed on the back surface and a second silicon nitride film mask formed on the front surface;
In the thermal oxidation processing apparatus, the back surface of the first monitor wafer and the front surface of the first product wafer are opposed to each other, and the back surface of the first product wafer and the front surface of the second product wafer are opposed to each other. Arranging, and
The surface of the first monitor wafer, the surface of the first product wafer not covered with the first silicon nitride mask, and the second product wafer not covered with the second silicon nitride mask A first thermal oxidation step of forming a thermal oxide film on the surface of the substrate by the thermal oxidation treatment apparatus;
A step of taking out the first monitor wafer and the first and second product wafers from the thermal oxidation processing apparatus;
Removing the first and second silicon nitride masks;
The back surface of the second monitor wafer having the fourth silicon nitride film formed on the back surface is opposed to the surface of the first product wafer, and the back surface of the first product wafer and the surface of the second product wafer are A step of disposing it in the thermal oxidation apparatus in a state of being opposed to each other;
The surface of the second monitor wafer, the surface of the first product wafer covered with the first silicon nitride film mask, and the second product wafer covered with the second silicon nitride film mask A second thermal oxidation step of forming a thermal oxide film on the surface of the substrate and the thermal oxide film formed in the first thermal oxidation step by the thermal oxidation treatment apparatus;
It is characterized by comprising.

A method for manufacturing a semiconductor device according to one embodiment of the present invention includes a first monitor wafer, a first dummy wafer having a first silicon nitride film formed on the back surface, a second silicon nitride film formed on the back surface, and a front surface. A first product wafer having a first silicon nitride film mask formed thereon and a second product wafer having a third silicon nitride film formed on the back surface and a second silicon nitride film mask formed on the front surface. A process to prepare;
The back surface of the first monitor wafer is opposed to the front surface of the first dummy wafer, the back surface of the first dummy wafer is opposed to the front surface of the first product wafer, and the back surface of the first product wafer is And placing in the thermal oxidation processing apparatus with the surface of the second product wafer facing each other,
The surface of the first monitor wafer, the surface of the first product wafer not covered with the first silicon nitride mask, and the second product wafer not covered with the second silicon nitride mask A first thermal oxidation step in which a thermal oxide film is formed on the surface of the substrate by the thermal oxidation treatment apparatus;
Taking out the first monitor wafer, the first dummy wafer, the first and second product wafers from the thermal oxidation processing apparatus;
Removing the first and second silicon nitride masks;
The back surface of the second monitor wafer having the fourth silicon nitride film formed on the back surface is opposed to the front surface of the second dummy wafer having the fifth silicon nitride film formed on the back surface. Disposing the back surface of the first product wafer in the thermal oxidation apparatus in a state in which the back surface of the first product wafer faces and the back surface of the first product wafer faces the surface of the second product wafer;
The surface of the second monitor wafer, the surface of the first product wafer covered with the first silicon nitride film mask, and the second product wafer covered with the second silicon nitride film mask And a second thermal oxidation step of forming a thermal oxide film on the thermal oxide film formed in the first thermal oxidation step on the surface of each of the first and second product wafers by the thermal oxidation processing apparatus. When,
It is characterized by comprising.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 7A is a schematic diagram showing a vertical thermal oxidation processing apparatus used in a thermal oxidation process for forming a gate oxide film, and FIG. 7B is a schematic diagram showing a wafer holder shown in FIG. 7A. It is.

  As shown in FIG. 7A, the vertical thermal oxidation processing apparatus has a support base 1, and a wafer holder 2 that holds a wafer is supported on the support base 1. The vertical thermal oxidation processing apparatus has a quartz tube 3 as a chamber into which the wafer holder 2 can be inserted. A round portion 3 ′ is formed on the upper portion of the quartz tube 3, and a lower portion of the quartz tube 3 is formed. Is provided with an exhaust pipe 10.

  The vertical heat treatment apparatus has a gas introduction mechanism for introducing a gas such as nitrogen or oxygen into the chamber. Specifically, a partition plate 5 for partitioning the upper portion of the quartz tube 3 is provided in the quartz tube 3, and an opening 6 for ejecting a gas such as nitrogen or oxygen is formed on the partition plate 5 on the scattered point. Is provided. A gas chamber 7 surrounded by a rounded portion 3 ′ formed on the upper portion of the quartz tube 3 and a partition plate 5 is provided on the upper portion of the quartz tube 3. The gas chamber 7 is connected to a gas pipe 8, and the gas pipe 8 is fixed to the main body of the quartz tube 4 by a fixing member 9.

  Around the quartz tube 3, a soaking tube 11 for uniformizing the heat in the quartz tube 3 is provided. A heater 12 for heating the inside of the quartz tube 3 is provided around the soaking tube 11. When performing heat treatment of the wafer, the wafer is placed in the wafer holder 2 and the wafer holder 2 on which the wafer is placed is inserted into the quartz tube 3. Then, the inside of the quartz tube 3 is heated, and heat treatment of the wafer is performed while gas is ejected into the quartz tube 3 through the gas pipe 8 and the gas chamber 7.

Next, the arrangement of the wafer in the wafer holder 2 will be described.
As shown in FIG. 7B, the wafer holder 2 holds a monitor wafer and a plurality of semiconductor wafers. FIG. 1 is a schematic diagram for explaining the order of the wafers held by the wafer holder 2 shown in FIG.

  A first monitor wafer M1, a second monitor wafer M2, and a third monitor wafer M3 are held on the uppermost portion, the middle portion, and the lowermost portion of the wafer holder 2 shown in FIG. The first to third monitor wafers M1, M2, and M3 are for managing the film forming ability in the vertical thermal oxidation processing apparatus shown in FIG. A plurality of product wafers are held between the first monitor wafer M1 and the second monitor wafer M2 and between the second monitor wafer M2 and the third monitor wafer M3. Specifically, as shown in FIGS. 1 and 7B, the first monitor wafer M1, product wafers # 2, # 3, # 4, # 5, # 6,... .

  Next, a method for forming a gate oxide film using the vertical thermal oxidation processing apparatus shown in FIG. 7A will be described with reference to FIG. FIGS. 3A to 3D are cross-sectional views for explaining a step of forming a gate oxide film, illustrating the method for manufacturing the semiconductor device according to the first embodiment of the present invention.

  First, as shown in FIG. 3A, a LOCOS oxide film 22 as an element isolation film is formed on the surface of a silicon substrate (product wafer) 21. Next, as shown in FIG. 3B, SiN films (silicon nitride films) are formed on the front and back surfaces of the silicon substrate 21 including the LOCO oxide film 22 by the CVD method. The SiN film at this time is intended to be formed on the surface of the silicon substrate 21, but the SiN film is also formed on the back surface by the CVD gas flowing around the back surface of the silicon substrate 21. Next, an opening region 25 is formed in the SiN film (silicon nitride film mask) 23a on the surface of the silicon substrate 21 by processing and forming this SiN film by a photolithography method and a dry etching method. At this time, the SiN film 23 formed on the back surface of the silicon substrate 21 is etched in order to etch the SiN film on the surface of the silicon substrate 21 with the back surface of the silicon substrate 21 placed on the stage of the dry etching apparatus. Not removed.

  Further, the first monitor wafer M1 shown in FIG. 1 uses a silicon wafer 30a, and forms SiN films on the front and back surfaces of the silicon wafer 30a by the CVD method in the same process as the product wafer 21. Thereafter, the SiN film on the surface of the silicon wafer 30a is removed by a dry etching method. The second and third monitor wafers M2 and M3 are also produced by the same method. A plurality of first to third monitor wafers M1 to M3 may be prepared in advance separately from the product wafer 21 and used in the selective oxidation step.

  Next, as shown in FIG. 3C, the product wafers # 2, # 3, # 4... In which the opening region 25 is formed in the SiN film 23a on the surface of the silicon substrate 21 are wafer holders of the vertical thermal oxidation processing apparatus. Retained. Specifically, the first to third monitor wafers and the product wafer are held by the order of the wafers held by the wafer holder 2 shown in FIG. After that, oxygen gas is filled in the vertical thermal oxidation processing apparatus, thermal oxidation processing is started, and the SiN film 23a on the surface of the silicon substrate 21 is used as a mask in the opening region 25 where the SiN film 23a is not formed. One region of gate oxide film 24 is formed. Thereafter, the product wafer is taken out from the vertical thermal oxidation processing apparatus.

  Thereafter, as shown in FIG. 3D, the silicon substrate 21 on which the gate oxide film 24 in the first region is formed is subjected to wet etching, whereby the SiN film 23a on the surface of the silicon substrate 21 and the back surface of the silicon substrate 21 are formed. The SiN film 23 is removed.

  As described above, according to the first embodiment of the present invention, the silicon wafer 30a in which the SiN film 23 remains on the back surface is used as the first monitor wafer M1. As a result, the SiN film 23 is formed on the back surface of the product wafer facing the front surfaces of the product wafers # 3, # 4, # 5. The SiN film 23 is also formed on the back surface of one monitor wafer M1. That is, at the time of the thermal oxidation process for forming the gate oxide film, all the product wafers including the product wafer # 2 can be made to face the surface on which the SiN film is formed. Therefore, it is possible to suppress the difference in oxidation rate between the product wafer # 2 and the other product wafers # 3, # 4, # 5, # 6..., For example, the product wafer # facing the first monitor wafer M1. It can suppress that the oxidation rate of only 2 becomes high compared with another product wafer. Therefore, all the product wafers held by the wafer holder 2 can be processed under the same conditions. As a result, in the gate oxide film whose film thickness is strictly controlled, the film thickness uniformity between product wafers can be improved, and the reduction in yield can be suppressed.

(Second Embodiment)
Next, a method for manufacturing a semiconductor device according to the second embodiment of the present invention will be described. Components that are the same as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The wafer arrangement in the wafer holder 2 according to the second embodiment will be described.
FIG. 2 is a schematic diagram for explaining the order of the wafers held by the wafer holder 2 shown in FIG.

  As shown in FIGS. 2 and 7B, the first monitor wafer M1, dummy wafer # 2, product wafers # 3, # 4, # 5, # 6,... The dummy wafer # 2 uses a silicon wafer 31, and has a SiN film 23a formed on the surface of the silicon wafer 31 and a SiN film 23 formed on the back surface of the silicon wafer. A dummy wafer is also disposed under the second monitor wafer M2.

  Next, as shown in FIG. 2, a wafer holder on which product wafers and the like are arranged is inserted into the vertical thermal oxidation processing apparatus shown in FIG. 7A, and a gate oxide film is formed using this vertical thermal oxidation processing apparatus. The method will be described with reference to FIG. The description of the same parts as those in the first embodiment is omitted.

  Product wafers # 3, # 4, # 5, # 6,... Go through the same steps as in FIGS. The first monitor wafer M1 uses a silicon wafer 30 on which no film is formed. Further, the dummy wafer # 2 uses a silicon wafer 31, and the surface of the silicon wafer 31 and the wafers # 3, # 4, # 5, # 6. SiN films 23a and 23 are formed on the back surface. However, the SiN film 23a on the surface of the silicon wafer 31 may or may not be patterned, and the LOCOS oxide film 22 may or may not be formed. A plurality of first to third monitor wafers M1 to M3 and dummy wafer # 2 used in the selective oxidation step are prepared in advance separately from product wafers # 3, # 4, # 5, # 6. It may be used during the selective oxidation step.

  Next, the step shown in FIG. At this time, the first to third monitor wafers, the dummy wafer, and the product wafer are held in the order of the wafers held by the wafer holder 2 shown in FIG. Thereafter, the step shown in FIG.

  As described above, according to the second embodiment of the present invention, as shown in FIG. 2, the first monitor wafer M1, the dummy wafer # 2, the product wafers # 3, # 4, # 5, # 6 ... are arranged. As a result, the surface of the product wafer # 3 located at the top of the plurality of product wafers faces the SiN film 23 formed on the back surface of the dummy wafer # 2, and is the same as in the first embodiment. An effect can be obtained.

  Further, in order to manage the film forming capability, a dummy wafer # 2 having a SiN film 23 formed on the back surface to be opposed to the product wafer # 3 is used separately from the first monitor wafer M1. This eliminates the need to form a SiN film on the back surface of the first monitor wafer M1, eliminates the need to remove the SiN film 23a formed on the front surface of the dummy wafer # 2, and simplifies the process.

(Third embodiment)
Next, a method for manufacturing a semiconductor device according to the third embodiment of the present invention will be described with reference to FIGS. 4 and 6. Omitted.

  FIG. 4 is a schematic diagram for explaining the order of the wafers held by the wafer holder 2 shown in FIG. The wafer arrangement in the wafer holder 2 according to the second embodiment shown in FIG. 4 is the same as that in the first embodiment shown in FIG.

  Next, as shown in FIG. 4, a wafer holder on which product wafers and the like are arranged is inserted into the vertical thermal oxidation processing apparatus shown in FIG. 7A, and a gate oxide film is formed using this vertical thermal oxidation processing apparatus. The method will be described with reference to FIG. 6A to 6D are cross-sectional views for explaining a method for manufacturing a semiconductor device according to the third embodiment of the present invention.

  The semiconductor device manufacturing method according to the third embodiment first undergoes the steps shown in FIGS. Next, as shown in FIG. 6A, the SiN film 23a on the surface of the silicon substrate 21 is removed by a dry etching method, but the back surface of the semiconductor wafer 32 is not exposed to plasma during the dry etching. The SiN film 23 remains on the entire surface.

  Next, the product wafers # 2, # 3, # 4, # 5... And the first monitor wafer M1 in the state shown in FIG. 6A are placed on the wafer holder shown in FIG. Is held in place.

  Next, the vertical thermal oxidation treatment apparatus shown in FIG. 7A is filled with a gas such as nitrogen or oxygen, and thermal oxidation treatment is performed. As a result, as shown in FIG. 6B, a gate oxide film 24a in the second region is formed on the silicon substrate 21. At this time, since the gate oxide film 24 in the first region is also thermally oxidized together with the gate oxide film 24a in the second region, the first region having a thickness larger than the thickness of the gate oxide film 24a in the second region. One region of the gate oxide film 24 is formed. As a result, gate oxide films having two types of film thickness are formed on the silicon substrate 21.

  Thereafter, as shown in FIG. 6C, wet etching treatment is performed on the silicon substrate 21 on which the gate oxide film 24 in the first region and the gate oxide film 24a in the second region are formed, whereby the back surface of the silicon substrate 21 is obtained. The SiN film 23 is removed.

  As described above, also in the third embodiment of the present invention, the same effect as that of the first embodiment can be obtained.

  In this embodiment, the gate oxide film 24 in the first region is formed by performing thermal oxidation twice. For this reason, compared with the case where a prior art is used, the fall of the film thickness uniformity between the product wafers in the gate oxide film 24 of the first region can be further suppressed.

(Fourth embodiment)
Next, a semiconductor device manufacturing method according to the fourth embodiment of the present invention will be described with reference to FIG.

The wafer arrangement in the wafer holder 2 according to the fourth embodiment will be described.
FIG. 5 is a schematic diagram for explaining the order of the wafers held by the wafer holder 2 shown in FIG. The arrangement of wafers in the wafer holder 2 according to the fourth embodiment shown in FIG. 5 is the same as that of the second embodiment shown in FIG. The first monitor wafer M1 and dummy wafer # 2 shown in FIG. 5 are the same as those in the second embodiment.

  Next, as shown in FIG. 5, a wafer holder on which product wafers are arranged is inserted into the vertical thermal oxidation processing apparatus shown in FIG. 7A, and a gate oxide film is formed using this vertical thermal oxidation processing product wafer apparatus. A forming method will be described with reference to FIG.

  The semiconductor device manufacturing method according to the fourth embodiment first undergoes the steps shown in FIGS. 3A to 3C and FIG.

  Next, the product wafers # 2, # 3, # 4, # 5... And the first monitor wafer M1 in the state shown in FIG. 6A are placed on the wafer holder shown in FIG. Is held in place. Then, the step shown in FIG. 6B is performed.

  As described above, also in the fourth embodiment of the present invention, the same effect as that of the third embodiment can be obtained.

(Fifth embodiment)
Next, manufacture of a semiconductor device according to the fifth embodiment of the present invention will be described with reference to FIG. Further, the description of the same parts as those in the first embodiment will be omitted.

  FIG. 8 is a schematic view showing a horizontal thermal oxidation processing apparatus in the method for manufacturing a semiconductor device according to the fifth embodiment of the present invention. The horizontal thermal oxidation processing apparatus is a horizontal furnace in which the vertical thermal oxidation processing apparatus shown in FIG. A plurality of semiconductor wafers Waf are held by wafer holder BT1, and are carried into process tube CHB1 by movement control of fork FK1. The inside of the process tube CHB1 is a heat treatment environment within a predetermined temperature range by the surrounding heater HT1.

  The arrangement of the semiconductor wafers Waf accompanied by the wafer holder BT1 is carried into the horizontal thermal oxidation processing apparatus from the wafer carry-in / out side A1 of the process tube CHB1 brought to a predetermined temperature range. The front end of the semiconductor wafer Waf is placed on the end E1 side. In the process tube CHB1, a heat treatment process is performed on the semiconductor wafer Waf accompanied by the supply of the reaction gas. Thereafter, the arrangement of the semiconductor wafers Waf is again carried out from the wafer carry-in / out side A1.

  By performing the heat treatment of the semiconductor wafer Waf with the above-described horizontal thermal oxidation processing apparatus, a gate oxide film is formed by the selective oxidation process shown in FIG. The wafer arrangement in the wafer holder BT1 is the same as that in the vertical thermal oxidation processing apparatus.

  As described above, also in the fifth embodiment of the present invention, the same effect as that of the first embodiment can be obtained.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

The schematic diagram for demonstrating the order of the wafer hold | maintained at the wafer holder 2 shown to FIG. 7 (B) in the 1st Embodiment of this invention. The schematic diagram for demonstrating the order of the wafer hold | maintained at the wafer holder 2 shown to FIG. 7 (B) in the 2nd Embodiment of this invention. Sectional drawing for demonstrating the manufacturing method of the semiconductor device by the 1st Embodiment of this invention. It is a schematic diagram for demonstrating the order of the wafer hold | maintained at the wafer holder 2 shown to FIG. 7 (B) in the 3rd Embodiment of this invention. The schematic diagram for demonstrating the order of the wafer hold | maintained at the wafer holder 2 shown to FIG. 7 (B) in the 4th Embodiment of this invention. 4 is a cross-sectional view of the semiconductor wafer 32 shown in FIG. 4, illustrating a method for manufacturing a semiconductor device in a third embodiment of the present invention. (A) is a schematic diagram which shows the vertical thermal oxidation processing apparatus in the manufacturing method of a semiconductor device, (b) is a schematic diagram which shows the wafer holder shown to FIG. 7 (A). The schematic diagram which shows the horizontal thermal oxidation processing apparatus in the manufacturing method of the semiconductor device which concerns on the 5th Embodiment of this invention. The schematic diagram for demonstrating the conventional wafer arrangement | sequence.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Support stand, 2 ... Wafer holder, 3 ... Quartz tube, 3 '... Earl part, 5 ... Partition plate, 6 ... Opening part, 7 ... Gas chamber, 8 ... Gas piping, 9 ... Fixing member, 10 ... Exhaust pipe, 11 ... Soaking pipe, 12 ... Heater, M1,30 ... Monitor wafer, BT1 ... Wafer holder, CHB1 ..Process tube, HT1 ... heater, Waf ... semiconductor wafer, FK1 ... fork, A1 ... wafer loading / unloading side, E1 ... terminal side, 21 ... product wafer, 23, 23a ... SiN film, 25 ... opening, 30a ... silicon wafer, 22 ... LOCOS oxide film, 24, 24a ... gate oxide film

Claims (10)

The back surface of the monitor wafer and the front surface of the first product wafer are made to face each other, and the back surface of the first product wafer and the front surface of the second product wafer are made to face each other, and the monitor wafer, the first and second products A step of disposing in a thermal oxidation processing apparatus in a state in which a silicon nitride film is formed on the back surface of each wafer;
Forming a thermal oxide film on the surface of each of the monitor wafer and the first and second product wafers by the thermal oxidation processing apparatus;
A method for manufacturing a semiconductor device, comprising: The back surface of the monitor wafer and the front surface of the dummy wafer are opposed, the back surface of the dummy wafer is opposed to the surface of the first product wafer, and the back surface of the first product wafer is opposed to the surface of the second product wafer; And placing the dummy wafer and the first and second product wafers in a thermal oxidation apparatus in a state where a silicon nitride film is formed on the back surface thereof,
Forming a thermal oxide film on the surface of each of the monitor wafer and the first and second product wafers by the thermal oxidation processing apparatus;
A method for manufacturing a semiconductor device, comprising:   2. The method of manufacturing a semiconductor device according to claim 1, wherein the thermal oxide film is a gate oxide film.   4. The method for manufacturing a semiconductor device according to claim 1, wherein the thermal oxidation processing apparatus is a vertical or horizontal thermal oxidation processing apparatus. 5. The back surface of the monitor wafer and the front surface of the first product wafer are made to face each other, and the back surface of the first product wafer and the front surface of the second product wafer are made to face each other, and the monitor wafer, the first and second products Place the silicon nitride film on the backside of each wafer in the thermal oxidation treatment device,
A thermal oxidation processing method, wherein a thermal oxide film is formed on the surface of each of the monitor wafer and the first and second product wafers by the thermal oxidation processing apparatus. The back surface of the monitor wafer and the front surface of the dummy wafer are opposed, the back surface of the dummy wafer is opposed to the surface of the first product wafer, and the back surface of the first product wafer is opposed to the surface of the second product wafer; And it arrange | positions in a thermal oxidation processing apparatus in the state in which the silicon nitride film was formed in the back surface of each of the said dummy wafer and said 1st and 2nd product wafer,
A thermal oxidation processing method, wherein a thermal oxide film is formed on the surface of each of the monitor wafer and the first and second product wafers by the thermal oxidation processing apparatus. A wafer holder that holds the back surface of the monitor wafer and the front surface of the first product wafer, and holds the back surface of the first product wafer and the front surface of the second product wafer;
A chamber into which the wafer holder is inserted;
A gas introduction mechanism for introducing oxygen gas into the chamber;
A heater for heating the inside of the chamber;
Comprising
A thermal oxide film is formed on the surface of each of the monitor wafer and the first and second product wafers with a silicon nitride film formed on the back surface of each of the monitor wafer and the first and second product wafers. The thermal oxidation processing apparatus characterized by the above-mentioned. The back surface of the monitor wafer is opposed to the front surface of the dummy wafer, the back surface of the dummy wafer is opposed to the front surface of the first product wafer, and the back surface of the first product wafer is opposed to the front surface of the second product wafer. A wafer holder to hold
A chamber into which the wafer holder is inserted;
A gas introduction mechanism for introducing oxygen gas into the chamber;
A heater for heating the inside of the chamber;
Comprising
A thermal oxide film is formed on the surface of each of the monitor wafer, the first product wafer, and the second product wafer in a state where a silicon nitride film is formed on the back surface of each of the monitor wafer, the dummy wafer, and the first and second product wafers. Forming a thermal oxidation treatment apparatus. A first monitor wafer having a first silicon nitride film formed on the back surface, a first product wafer having a second silicon nitride film formed on the back surface and a first silicon nitride film mask formed on the surface; and Preparing a second product wafer having a third silicon nitride film formed on the back surface and a second silicon nitride film mask formed on the front surface;
In the thermal oxidation processing apparatus, the back surface of the first monitor wafer and the front surface of the first product wafer are opposed to each other, and the back surface of the first product wafer and the front surface of the second product wafer are opposed to each other. Arranging, and
The surface of the first monitor wafer, the surface of the first product wafer not covered with the first silicon nitride mask, and the second product wafer not covered with the second silicon nitride mask A first thermal oxidation step of forming a thermal oxide film on the surface of the substrate by the thermal oxidation treatment apparatus;
A step of taking out the first monitor wafer and the first and second product wafers from the thermal oxidation processing apparatus;
Removing the first and second silicon nitride masks;
The back surface of the second monitor wafer having the fourth silicon nitride film formed on the back surface is opposed to the surface of the first product wafer, and the back surface of the first product wafer and the surface of the second product wafer are A step of disposing it in the thermal oxidation apparatus in a state of being opposed to each other;
The surface of the second monitor wafer, the surface of the first product wafer covered with the first silicon nitride film mask, and the second product wafer covered with the second silicon nitride film mask A second thermal oxidation step of forming a thermal oxide film on the surface of the substrate and the thermal oxide film formed in the first thermal oxidation step by the thermal oxidation treatment apparatus;
A method for manufacturing a semiconductor device, comprising: A first monitor wafer, a first dummy wafer having a first silicon nitride film formed on the back surface, a second silicon nitride film formed on the back surface, and a first silicon nitride film mask formed on the front surface Preparing a product wafer and a second product wafer having a third silicon nitride film formed on the back surface and a second silicon nitride film mask formed on the front surface;
The back surface of the first monitor wafer is opposed to the front surface of the first dummy wafer, the back surface of the first dummy wafer is opposed to the front surface of the first product wafer, and the back surface of the first product wafer is And placing in the thermal oxidation processing apparatus with the surface of the second product wafer facing each other,
The surface of the first monitor wafer, the surface of the first product wafer not covered with the first silicon nitride mask, and the second product wafer not covered with the second silicon nitride mask A first thermal oxidation step in which a thermal oxide film is formed on the surface of the substrate by the thermal oxidation treatment apparatus;
Taking out the first monitor wafer, the first dummy wafer, the first and second product wafers from the thermal oxidation processing apparatus;
Removing the first and second silicon nitride masks;
The back surface of the second monitor wafer having the fourth silicon nitride film formed on the back surface is opposed to the front surface of the second dummy wafer having the fifth silicon nitride film formed on the back surface. Disposing the back surface of the first product wafer in the thermal oxidation apparatus in a state in which the back surface of the first product wafer faces and the back surface of the first product wafer faces the surface of the second product wafer;
The surface of the second monitor wafer, the surface of the first product wafer covered with the first silicon nitride film mask, and the second product wafer covered with the second silicon nitride film mask And a second thermal oxidation step of forming a thermal oxide film on the thermal oxide film formed in the first thermal oxidation step on the surface of each of the first and second product wafers by the thermal oxidation processing apparatus. When,
A method for manufacturing a semiconductor device, comprising:

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