JP2005072377A - Method for manufacturing semiconductor device and substrate processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device capable of manufacturing a high quality semiconductor device by suppressing a large fluctucation in oxide film thickness caused by a large difference of hydrogen concentration depending on a place of an arrangement of the substrate when an isotropic oxidation is conducted by a batch type vertical device, and to provide a substrate processor. <P>SOLUTION: The method for manufacturing the semiconductor device comprises the steps of carrying a plurality of substrates 1 into a processing chamber 4, supplying a gas including oxygen from an upstream side of the substrates 1 carried in the chamber 4, supplying a gas including hydrogen from an upstream side of the substrates 1 carried in the chamber 4 and from a midstream place corresponding to a region in which the plurality of substrates exist, oxidizing the substrates 1 by reacting the gas including oxigen and the gas inclding hydrogen in the chamber 4, and carruing out the processed substrates 1 from the chamber 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a semiconductor device (device) for oxidizing a surface of a substrate such as a semiconductor wafer.
The present invention relates to a manufacturing method and a substrate processing apparatus.

In the process of directly oxidizing the Si substrate (wafer) on which different Si crystal planes are exposed, formed in the middle of the semiconductor process, the conventional oxidation technology results in different oxidation rates depending on the crystal planes. Oxide films having different film thicknesses are formed on the substrate, and there is a problem that characteristics vary depending on locations on the substrate.

In the process of exposing different Si crystal planes on the substrate, for example, Shallow Trench Isolation (S
TI) There are element isolation processes known as TI) and a vertical MOS transistor forming process in which a Si substrate is dug. By forming a groove on the Si substrate by dry etching, different surfaces are formed on the side surface and the bottom surface of the groove. The bearing is exposed. In the STI process, in the oxidation process,
Since Si ₃ N _{4 is} also exposed on the substrate surface, the oxidation rate on Si ₃ N ₄ is close to the oxidation rate on the Si substrate, and there is a process requirement to make the oxide film thickness as much as possible.

Conventional oxidation methods include dry oxidation in which the substrate is oxidized in an atmosphere in which the reaction chamber atmosphere is normal pressure or reduced pressure, oxygen alone or an oxygen partial pressure of which is adjusted by N ₂ , Ar, or the like, and oxygen And wet oxidation in which the substrate is oxidized using moisture formed by mixing hydrogen and hydrogen in the front stage of the reaction chamber. As a method of forming moisture by mixing hydrogen and oxygen, a method of heating and burning above the ignition temperature of hydrogen and oxygen by resistance heating, lamp condensing heating, etc., and a method of hydrogen and oxygen by catalytic action below the ignition temperature The method of reacting is widely used (see Patent Document 1).
JP-A-11-204511

In the conventional oxidation method, between the plane orientations of different Si substrates, for example, the (100) plane and the (110) plane have a higher Si atomic plane density (110) depending on the Si atomic plane density on the Si substrate surface.
The oxidation rate of the surface is approximately twice that of the (100) surface in the thin film oxidation region. Further, on Si ₃ N ₄ , oxidation resistance is usually high, and it may be used as a barrier layer against oxidation, and oxidation hardly proceeds.

On the other hand, in a method in which oxygen and hydrogen are introduced into a reaction chamber in a reduced pressure atmosphere from an independent gas supply system and reacted directly in the vicinity of the substrate as the object to be processed, the reaction with the substrate is performed before moisture is formed. Therefore, the growth rate at the initial stage of oxidation is high, and the plane orientation between different Si substrates is different.
₃ N ₄ result difference growth rate decreases on, it is possible to significantly reduce the film thickness difference,
Isotropic oxidation is possible.

However, when isotropic oxidation is carried out in a batch type vertical apparatus, in the conventional method,
Since the gas supply location is only upstream of the substrate to be processed, the hydrogen concentration in the reaction chamber differs depending on the location of the substrates arranged in multiple stages in the vertical direction. There was a problem that it fluctuated greatly.

The object of the present invention is to suppress high fluctuations in the oxide film thickness due to the difference in hydrogen concentration depending on the location of the substrate when isotropic oxidation is carried out in a batch type vertical apparatus. An object of the present invention is to provide a semiconductor device manufacturing method and a substrate processing apparatus capable of manufacturing a device.

The first feature of the present invention includes a step of carrying a plurality of substrates into a processing chamber, a step of supplying an oxygen-containing gas from the upstream side of the plurality of substrates carried into the processing chamber, A step of supplying a hydrogen-containing gas from an upstream side of the plurality of substrates carried into the processing chamber and a midpoint corresponding to a region where the plurality of substrates exist, and the oxygen-containing gas and the A method of manufacturing a semiconductor device comprising: a step of oxidizing a plurality of substrates by reacting with a hydrogen-containing gas; and a step of unloading the processed substrates from a processing chamber.

A second feature of the present invention is that in the first feature, the step of oxidizing the substrate is performed in a state where the pressure in the processing chamber is lower than atmospheric pressure. Is in the way.

The third feature of the present invention is that, in the first feature, the oxygen-containing gas is at least one gas selected from the group consisting of oxygen gas and nitrous oxide gas, and the hydrogen-containing gas. Is a method of manufacturing a semiconductor device, characterized in that it is at least one gas selected from the group consisting of hydrogen gas, ammonia gas, and methane gas.

According to a fourth feature of the present invention, in the method of manufacturing a semiconductor device according to the first feature, the oxygen-containing gas is an oxygen gas, and the hydrogen-containing gas is a hydrogen gas. is there.

A fifth feature of the present invention is that, in the first feature, the surface of the substrate has different crystal orientation planes, is polycrystalline silicon by CVD, or is silicon nitride. A method of manufacturing a semiconductor device.

The sixth feature of the present invention is that a processing chamber for processing a plurality of substrates, a holder for holding the plurality of substrates in the processing chamber, and a substrate from the upstream side of the plurality of substrates to the substrate. Hydrogen for supplying a hydrogen-containing gas to a substrate from an oxygen-containing gas supply line for supplying an oxygen-containing gas to an upstream side of the plurality of substrates and a midpoint corresponding to a region where the plurality of substrates exist The substrate processing apparatus includes a containing gas supply line and an exhaust line for exhausting the processing chamber.

A seventh feature of the present invention resides in the substrate processing apparatus according to the sixth feature, further comprising control means for controlling the pressure in the processing chamber to be equal to or lower than atmospheric pressure. .

An eighth feature of the present invention is that, in the sixth feature, the hydrogen-containing gas supply line includes a supply line that supplies a hydrogen-containing gas from an upstream side of the plurality of substrates, and the plurality of substrates. The substrate processing apparatus includes a supply line that supplies a hydrogen-containing gas from a midpoint corresponding to a region where the gas exists, and each supply line is provided independently.

A ninth feature of the present invention is that, in the sixth feature, the hydrogen-containing gas supply line includes a supply line that supplies a hydrogen-containing gas from an upstream side of the plurality of substrates, and the plurality of substrates. The substrate processing apparatus is characterized by comprising a plurality of supply lines for supplying hydrogen-containing gas from a plurality of locations in the middle corresponding to the region where the gas exists, and each supply line is provided independently.

A tenth feature of the present invention resides in the substrate processing apparatus according to the eighth feature, wherein each of the supply lines is provided with a mass flow controller.

An eleventh feature of the present invention resides in a substrate processing apparatus according to the ninth feature, wherein each of the supply lines is provided with a mass flow controller.

A twelfth feature of the present invention is the substrate processing apparatus according to the sixth feature, wherein the hydrogen-containing gas supply line includes a plurality of independent nozzles.

A thirteenth feature of the present invention is the substrate processing apparatus according to the sixth feature, wherein the hydrogen-containing gas supply line includes a perforated nozzle having at least two or more holes provided on a side surface. It is in.

A fourteenth feature of the present invention is the substrate processing apparatus according to the thirteenth feature, wherein at least two types of holes having different opening areas are provided on a side surface of the porous nozzle.

According to the present invention, the difference in the growth rate of the oxide film on the silicon surface with different plane orientations on the silicon substrate formed in the process steps of various semiconductor wafers can be significantly reduced as compared with the conventional oxidation method. it can. In addition, when a plurality of substrates are processed in a batch type vertical apparatus, variations in oxide film thickness due to variations in hydrogen concentration on each substrate can be suppressed, and a high-quality semiconductor device (device) is manufactured. be able to.

The inventors of the present invention have found that isotropic oxidation directly reacts with a substrate heated by a heating source in the vicinity of oxygen and hydrogen, and that the film formation rate is a hydrogen-controlled rate-dependent reaction. In order to make the film formation speed on each substrate arranged in multiple stages constant, it has been devised that the number of hydrogen supply paths to the reaction chamber is two or more. As a result, the hydrogen supplied from the upstream of the reaction chamber is
Similarly, it is possible to eliminate attenuation of hydrogen concentration in the downstream direction of the gas flow in the reaction chamber due to the reaction and consumption of oxygen supplied from the upstream of the reaction chamber and directly above the substrate, using a batch type vertical apparatus. In the case of performing isotropic oxidation, the present inventors succeeded in improving the uniformity of the oxide film thickness on a plurality of substrates.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 illustrates a batch type vertical semiconductor manufacturing apparatus (oxidation apparatus) as a substrate processing apparatus in an embodiment of the present invention. The reaction furnace 20 has a reaction tube 21, and a boat 2 as a substrate holder is inserted into a reaction chamber (processing chamber) 4 formed by the reaction tube 21. The holder 2 is configured to hold a plurality of semiconductor wafers (silicon wafers) 1 as substrates in a plurality of stages with a gap (substrate pitch interval) in a substantially horizontal state. The lower part of the reaction tube 21 is opened to insert the holder 2, and this open part is sealed with a seal cap 22. A resistance heater 5 is disposed around the reaction tube 21 as a heating source. The reaction tube 21 includes an oxygen supply line 7 for supplying oxygen (O ₂ ) gas as an oxygen-containing gas to the substrate from the upstream side of the substrate, and hydrogen (H ₂ ) gas as a hydrogen-containing gas upstream of the substrate. A first hydrogen supply line 8 that supplies the substrate from the side and a second hydrogen supply line 9 that supplies the substrate from a midpoint corresponding to a region where a plurality of substrates exist are connected. A plurality of second hydrogen supply lines 9 are preferably provided. Each supply line 7, 8, 9 is provided with an electromagnetic valve 6 for supplying and stopping gas supply.
An exhaust line 23 for exhausting the processing gas is connected to the reaction tube 21, and the vacuum exhaust pump 3 is connected to the exhaust line 23. During the substrate processing, the inside of the reaction tube 21 is set to a predetermined pressure (reduced pressure) lower than the atmospheric pressure by the vacuum pump 3. This pressure control is performed by the control means 2.
4 is performed.

Next, a method for performing an oxidation process on a substrate as one step of a semiconductor device (device) manufacturing process using the above-described oxidation apparatus will be described.

When one batch of wafers 1 is transferred to the holder 2, the holder 2 loaded with a plurality of wafers 1 is loaded into the processing chamber 4 of the reaction furnace 20 maintained in a heated state by the heating source 5 (loading). The inside of the reaction tube 21 is sealed with the seal cap 22. Next, the reaction tube 21 is driven by the vacuum pump 3.
The inside is evacuated and the control means 24 performs control so that the furnace pressure becomes a predetermined processing pressure lower than the atmospheric pressure. In addition, the furnace temperature is raised, and the control means 24 controls the furnace temperature to be a predetermined processing temperature. Thereafter, oxygen is supplied into the processing chamber 4 from the oxygen supply line 7, and hydrogen gas is supplied into the processing chamber 4 from the first hydrogen supply line 8 and the second hydrogen supply line 9. As a result, the oxygen gas and the hydrogen gas react directly in the vicinity of the substrate heated by the heating source 5, and the wafer 1 is oxidized. As processing temperature, 500-1000 degreeC and 1-133Pa are illustrated as processing pressure.

When the oxidation treatment of the wafer 1 is completed, the residual gas in the furnace is removed by evacuation, purging with an inert gas, etc., the temperature in the furnace is lowered to a predetermined temperature, and then the holder 2 is unloaded from the reaction furnace 20. Then, the holder 2 is put on standby at a predetermined position until all the wafers 1 supported by the holder 2 are cooled. When the wafer 1 held by the holder 2 that has been waiting is cooled to a predetermined temperature, the wafer is recovered by a substrate transfer machine or the like.

According to the present embodiment, the difference in the growth rate of the oxide film on the silicon surface with different plane orientations on the wafer substrate, which is formed in various semiconductor wafer process steps, is significantly reduced as compared with the conventional oxidation method. In addition, when a plurality of wafers are processed by the vertical semiconductor manufacturing apparatus, it is possible to suppress variations in oxide film thickness due to variations in hydrogen concentration on each wafer. The present invention is particularly effective when the surface of the substrate to be oxidized has different crystal orientation planes, is polycrystalline silicon by CVD, or is silicon nitride.

In the above embodiment, the case where oxygen gas is used as the oxygen-containing gas has been described with respect to the case where hydrogen gas is used as the hydrogen-containing gas.
At least one gas selected from the group consisting of O ₂ ) gas and nitrous oxide (N ₂ O) gas can be used. As the hydrogen-containing gas, hydrogen (H ₂ ) gas, ammonia (NH ₃ )
At least one gas selected from the group consisting of gas and methane (CH ₄ ) gas can be used.

Next, the substrate processing apparatus in the first embodiment will be described in detail with reference to FIG.
An independent oxygen supply line 7 and a first hydrogen supply nozzle 8 are connected to the reaction chamber 4 that is in a reduced pressure atmosphere via the vacuum pump 3, and oxygen gas and hydrogen gas are connected to the reaction chamber 4. Since the reaction between active hydrogen and oxygen occurs immediately in the vicinity of the wafer 1 which is the object to be processed heated by the heating source 5 without being mixed before being supplied to the substrate, the oxidation rate in the initial oxidation stage is increased. I can do it.

The acceleration of the oxidation rate depends on the hydrogen concentration in the vicinity of the wafer. In the configuration in which hydrogen gas is supplied only from the upstream of the arrangement of the wafers 1 through the first hydrogen supply line 8, The hydrogen gas is consumed as it contributes to the oxidation reaction toward the downstream direction, and the hydrogen gas concentration varies depending on the wafer arrangement position, resulting in extremely poor film thickness uniformity.

Therefore, as a hydrogen supply line, in addition to the first hydrogen supply line 8, second, third,... Hydrogen supply lines 9 are provided in order to compensate for the hydrogen gas consumed in the oxidation reaction and deficient downstream. A plurality are provided. Thus, hydrogen gas can be supplied to the substrate from a plurality of locations in the middle of the region where the plurality of wafers 1 exist, and hydrogen gas deficient in the middle of the region where the wafers 1 exist can be compensated. Thus, it is possible to improve the film thickness uniformity of the plurality of wafers 1 arranged in the number 4. The second and third hydrogen supply lines 9 are independent of each other, and the gas outlets face the wafer direction (opposite the wafer 1), and supply oxygen upstream of the wafer array. Hydrogen can be supplied in the vicinity of the wafer without being mixed with oxygen supplied from the line 7.

Next, the substrate processing apparatus in the second embodiment will be described in detail with reference to FIG.
The first hydrogen supply line 8 independent of the oxygen supply line 7 is connected to the reaction chamber 4 as in the first embodiment. The difference from the first embodiment is that the second, third,... Hydrogen supply lines 9 independent from the first hydrogen supply line 8 rise in the reaction chamber 4 along the inner wall of the reaction tube 21. The point is that they are connected to a plurality of (multiple) nozzles of different sizes. Specifically, the second, third,... Hydrogen supply lines 9 are connected to a second hydrogen supply nozzle 10, a third hydrogen supply nozzle 11,. Thus, the hydrogen concentration in the reaction chamber in the wafer arrangement direction (vertical direction) can be adjusted. In addition, the front-end | tip of each nozzle is open | released and this open part becomes a gas jet nozzle. This gas jet port faces upward of the reaction chamber 4 and does not face the direction of the wafer 1, but may face the direction of the wafer (opposite the wafer 1) as in the first embodiment.

Next, the substrate processing apparatus in the third embodiment will be described in detail with reference to FIG.
A first hydrogen supply line 8 independent of the oxygen supply line 7 is connected to the reaction chamber 4, and separately from the first hydrogen supply line 8, the hydrogen gas consumed in the oxidation reaction and deficient downstream is supplemented. For this reason, the second, third,... Hydrogen supply lines 9 are provided in the same manner as in the first embodiment. The difference from the first embodiment is that the oxygen supply line 7, the first hydrogen supply line 8, the second,
A third,... Hydrogen supply line 9 is provided with a mass flow controller (flow rate control device) 12 capable of adjusting the flow rate. As a result, the oxygen flow rate and the hydrogen flow rate flowing through the respective supply lines can be adjusted, and the hydrogen concentration in the reaction chamber can be finely controlled.

Next, the substrate processing apparatus in the fourth embodiment will be described in detail with reference to FIG.
The first hydrogen supply line 8 independent of the oxygen supply line 7 is connected to the reaction chamber 4 as in the first embodiment. The difference from the first embodiment is that the second, third,... Are intermediate supply nozzles for adjusting the hydrogen concentration in the reaction chamber provided independently of the first hydrogen supply line 8.
The porous nozzle 13 is provided in place of the hydrogen supply line 9. This perforated nozzle 13
The nozzle tip is sealed and has at least two small holes in the nozzle side surface direction, and the hydrogen concentration in the reaction chamber can be controlled without using a plurality of hydrogen lines. It has become. You may make it provide at least 2 or more types of small holes from which the diameter, ie, opening area, differs in the side surface of the porous nozzle 13. That is, at least two kinds of small hole diameters may be provided. Thereby, it is possible to finely control the flow rate of hydrogen flowing out from each small hole.

Next, the substrate processing apparatus in the fifth embodiment will be described in detail with reference to FIG.
FIG. 5 is an embodiment in which the gas flow direction in the reaction chamber 4 is different from the first to fourth embodiments described in FIGS. In the case of the first to fourth embodiments, the gas basically flows from the upper side to the lower side in the reaction chamber 4. In the present embodiment, the gas flows from the lower side to the upper side in the reaction chamber 4. Flowing. In the structure of the reaction chamber, the inner tube 14 is provided in the outer tube (reaction tube) 21, and the reaction chamber 4 is divided through the inner tube 14, and oxygen and hydrogen, which are reaction gases, are respectively supplied to the reaction chamber. Supplied to the inside of the inner tube 14 from below,
The hydrogen supply nozzle for supply on the way also stands vertically inside the inner tube 14, and the reacted gas and unreacted gas flow outside the inner tube 14 (the space between the inner tube 14 and the outer tube 21). As described above, the exhaust gas is exhausted through the exhaust line 23 and the vacuum pump 3.

Schematic sectional view showing a substrate processing apparatus according to an embodiment (first example) of the present invention. Schematic sectional view showing a substrate processing apparatus according to an embodiment (second example) of the present invention. Schematic sectional view showing a substrate processing apparatus according to an embodiment (third example) of the present invention. Schematic sectional view showing a substrate processing apparatus according to an embodiment (fourth example) of the present invention. Schematic sectional view showing a substrate processing apparatus according to an embodiment (fifth example) of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wafer 2 Wafer holder 3 Vacuum exhaust pump 4 Reaction chamber 5 Heat source 6 Electromagnetic valve 7 Oxygen supply line 8 First hydrogen supply line 9 Second hydrogen supply line 10 First hydrogen supply nozzle 11 Second hydrogen supply Nozzle 12 Mass flow controller 13 Perforated nozzle

Claims (14)

Carrying a plurality of substrates into the processing chamber;
Supplying oxygen-containing gas from the upstream side of the plurality of substrates carried into the processing chamber;
Supplying a hydrogen-containing gas from an upstream side of the plurality of substrates carried into the processing chamber and a midpoint corresponding to a region where the plurality of substrates exist;
Oxidizing the plurality of substrates by reacting the oxygen-containing gas and the hydrogen-containing gas in the processing chamber;
A step of unloading the processed substrate from the processing chamber;
A method for manufacturing a semiconductor device, comprising: 2. The method of manufacturing a semiconductor device according to claim 1, wherein the step of oxidizing the substrate is performed in a state where the pressure in the processing chamber is lower than atmospheric pressure. The oxygen-containing gas is at least one gas selected from the group consisting of oxygen gas and nitrous oxide gas, and the hydrogen-containing gas is at least selected from the group consisting of hydrogen gas, ammonia gas, and methane gas. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the gas is a single gas. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the oxygen-containing gas is an oxygen gas, and the hydrogen-containing gas is a hydrogen gas. Whether the surface of the substrate has different crystal orientation planes, or is CVD polycrystalline silicon;
2. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is silicon nitride. A processing chamber for processing a plurality of substrates;
A holder for holding the plurality of substrates in the processing chamber;
An oxygen-containing gas supply line for supplying an oxygen-containing gas to the substrate from the upstream side of the plurality of substrates;
A hydrogen-containing gas supply line for supplying a hydrogen-containing gas to the substrate from an upstream side of the plurality of substrates and a midpoint corresponding to a region where the plurality of substrates are present;
An exhaust line for exhausting the processing chamber;
A substrate processing apparatus comprising: 7. The substrate processing apparatus according to claim 6, further comprising control means for controlling the pressure in the processing chamber to be a pressure equal to or lower than atmospheric pressure. The hydrogen-containing gas supply line includes a supply line that supplies a hydrogen-containing gas from an upstream side of the plurality of substrates, and a supply line that supplies a hydrogen-containing gas from a midpoint corresponding to a region where the plurality of substrates exist. 7. The substrate processing apparatus according to claim 6, wherein each supply line is provided independently. The hydrogen-containing gas supply line supplies a hydrogen-containing gas from a supply line that supplies a hydrogen-containing gas from an upstream side of the plurality of substrates, and a plurality of locations on the way corresponding to a region where the plurality of substrates exist. The substrate processing apparatus according to claim 6, comprising a plurality of supply lines, wherein each supply line is provided independently. 9. The substrate processing apparatus according to claim 8, wherein each of the supply lines is provided with a mass flow controller. The substrate processing apparatus according to claim 9, wherein each supply line is provided with a mass flow controller. The substrate processing apparatus according to claim 6, wherein the hydrogen-containing gas supply system line includes a plurality of independent nozzles. The substrate processing apparatus according to claim 6, wherein the hydrogen-containing gas supply line includes a perforated nozzle having at least two holes provided on a side surface. The substrate processing apparatus according to claim 13, wherein at least two types of holes having different opening areas are provided on a side surface of the porous nozzle.

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