JP2011009752A - Substrate processing apparatus, method of manufacturing semiconductor device, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve reduction in cost by enabling formation of a thin film of high quality including oxygen and eliminating the need of a moisture generator or ozone generator.SOLUTION: An apparatus has: a reaction tube 203 that accommodates a plurality of laminated substrates; a first gas supply means 232a that supplies a first raw material gas; a second gas supply means 232b that supplies a second raw material gas including an oxygen containing gas and a hydrogen containing gas; and an exhausting means 246 that exhausts the reaction tube. The first gas supply means includes a first gas supply pipe connected to the bottom of the reaction tube and which supplies the first raw material gas and a gas nozzle 233 erected in the reaction tube and having a plurality of gas supply inlets 248a. The second gas supply means includes a second gas supply pipe connected to the top of the reaction tube and which supplies the second raw material gas and forms an oxide film on the substrate by alternately supplying the first raw material gas and the second raw material gas without mixing them.

Description

  The present invention relates to a substrate processing apparatus for forming a thin film on a substrate by alternately supplying a first source gas and a second source gas.

FIG. 3 shows a MOSFET structure which is a semiconductor device. A buried layer 13 is provided in a transistor region partitioned by providing an element isolation layer 12 in an epitaxial layer 11 grown on a substrate 10, and a strain channel layer 17 is formed thereon. In the strained channel layer 17, a source region (n ⁺ region) 15 and a drain region (n ⁺ region) 16 and a gate region sandwiched between the source region 15 and the drain region 16 are formed. A gate insulating film 18, a gate electrode 19, and a gate electrode 20 are stacked on the gate region, and the outside thereof is covered with a spacer 22 via an offset spacer 21 (these portions are referred to as a gate portion). A contact plug (W) 24 and a metal wiring layer (Cu) 25 are provided on the source region 15 via a contact 23. A contact plug 27 and a metal wiring layer 28 are also provided on the drain region 16 via a contact 26. Reference numeral 30 denotes an interlayer insulating film.

As the above-described MOSFET is miniaturized, the gate insulating film 18 or the offset spacer 21 and the spacer 22 (hereinafter referred to as a spacer portion) in the gate portion are made thinner and the temperature is lowered at the time of film formation. A gate insulating film and a spacer part are comprised with the thin film containing oxygen. For example, the gate insulating film is often formed of an HfO ₂ film or a ZrO ₂ film that becomes a high dielectric film (High-k film), and the spacer portion is often formed of an SiO ₂ film.
In order to cope with thinning and low temperature, it has been studied to form a gate insulating film and a spacer portion by ALD (Atomic Layer Deposition) called atomic layer growth. ALD is a film forming method in which a plurality of types, for example, two types of raw materials are alternately supplied, and a thin film is grown by increasing atomic layers one by one.

  In ALD, if the supply of each raw material is sufficient in the raw material supply cycle, a film having a constant thickness is formed for each raw material supply cycle regardless of the shape of the substrate surface. Since it is only proportional to the number of supply cycles and is not sensitive to process conditions such as the amount of raw material supply, the thickness of the thin film can be precisely controlled.

The feature of ALD is
(1) A very thin film can be formed.
(2) A film having a uniform thickness can be formed even if the substrate has a large area, and can be applied to a 300 mm wafer.
(3) Since a film having a constant thickness can be formed regardless of the unevenness of the substrate, the step coverage is excellent.
(4) There is no pinhole in the formed film.
(5) A film having a uniform thickness can be formed on a substance such as powder.

When a thin film containing oxygen is formed using this ALD, a film source gas is used for one of the two source gases, and an oxidizing gas is used for the other source gas. For example, when forming a silicon oxide film (SiO _2), using the two kinds of gases of Si-based gas and an oxidizing gas containing silicon, it is grown a thin film by increasing the atomic layer by one layer, SiO ₂ A film is formed. Other examples of the thin film containing oxygen include Al ₂ O ₃ , ZrO ₂ , HfO ₂ , Y ₂ O ₃ , and La ₂ O ₃ .

As the oxidizing gas, H ₂ O (water) and O ₃ (ozone) are often used, and generally H ₂ O (water) is often used. There are two types of H ₂ O (water): a method of directly supplying moisture and a method of not supplying moisture directly.

In ALD, a method of directly supplying moisture is used, but in this case, the purity of the moisture is low, there is a problem in the quality of the thin film to be formed, and it is difficult to produce a good film. In the case where moisture is not directly supplied, a moisture generator is required and the cost is increased. Further, when O ₃ is used, there is a problem that the ozone generator becomes large.
An object of the present invention is to solve the above-mentioned problems of the prior art, and to form a high-quality film containing oxygen, to realize a low cost without requiring a moisture generator or an ozone generator. An object of the present invention is to provide a possible substrate processing apparatus.

According to a first aspect of the present invention, there is provided a processing chamber that accommodates a substrate, a heating unit that heats the substrate and the processing chamber, a first gas supply unit that supplies the first source gas to the processing chamber, and the first A second gas supply means for supplying a second source gas containing an O-containing gas and an H-containing gas different from the source gas to the processing chamber, an exhaust means for exhausting the atmosphere in the processing chamber, and a processing chamber Control means for controlling the first source gas and the second source gas to be alternately supplied to the substrate without being mixed with each other, and the first source material for the substrate in the processing chamber A gas is supplied to adsorb the first raw material on the substrate, a second raw material gas is supplied to generate O radicals and OH radicals, and the radicals cause a surface on the surface of the substrate on which the first raw material is adsorbed. Let the reaction occur and form an oxide film on the substrate A substrate processing apparatus, characterized in that had Unishi.
Of the first source gas and the second source gas supplied alternately into the processing chamber by the control means, the second source gas includes an O-containing gas (oxidizing gas) and an H-containing gas (reducing gas). Since gas is used to generate O radicals and OH radicals in the processing chamber and the surface reaction is performed on the substrate surface on which the first raw material is adsorbed, moisture is used as an oxidizing gas while having a simple structure. It is possible to solve the deterioration of purity as in use, and to reduce the cost without requiring a moisture generator or an ozone generator.

According to a second aspect of the present invention, a step of supplying a first source gas to a substrate in a processing chamber to adsorb the first source material on the substrate, a step of purging the processing chamber thereafter, a process after the purging, A second raw material gas containing an O-containing gas and an H-containing gas different from the first raw material gas is supplied to the first raw material adsorbed on the substrate in the room, and the O radical and the OH radical are supplied. And the surface reaction is performed on the surface of the substrate on which the first raw material is adsorbed by the radicals, and the step of forming an oxide film on the substrate and the step of purging the processing chamber thereafter are repeated a plurality of times. It is a manufacturing method of a semiconductor device.
Using a gas containing an O-containing gas and an H-containing gas as the second source gas, an O radical and an OH radical are generated in the processing chamber, so that a surface reaction is performed on the substrate surface on which the first source is adsorbed. As a result, it is a simple method, but it solves the deterioration of purity as when moisture is used as an oxidizing gas, and does not require a moisture generator or ozone generator, thus realizing cost reduction. be able to.

  According to the present invention, a high-quality film containing oxygen can be formed, and a cost reduction can be realized without requiring a moisture generator or an ozone generator.

It is the schematic of the processing furnace of the vertical ALD apparatus in embodiment. It is a gas flow diagram of the _H 2 / _{O 2} gas and Si-based gas by ALD in the embodiment. It is sectional drawing of MOSFET structure which is a semiconductor device. It is a see-through | perspective perspective view of the semiconductor manufacturing apparatus in embodiment. It is a longitudinal cross-sectional view of the semiconductor manufacturing apparatus in embodiment.

  Embodiments of the present invention will be described below.

  4 and 5, an outline of a semiconductor manufacturing apparatus which is an example of a substrate processing apparatus to which the present invention is applied will be described.

  A cassette stage 105 is provided on the front side of the inside of the housing 101 as a holding member transfer member that transfers the cassette 100 as a substrate storage container to and from an external transfer device (not shown). Is provided with a cassette elevator 115 as an elevating means, and a cassette transfer machine 114 as a conveying means is attached to the cassette elevator 115. Further, a cassette shelf 109 as a mounting means for the cassette 100 is provided on the rear side of the cassette elevator 115 and a spare cassette shelf 110 is also provided above the cassette stage 105. A clean unit 118 is provided above the spare cassette shelf 110 so as to distribute clean air through the inside of the casing 101.

  A processing furnace 202 is provided above the rear portion of the housing 101, and a boat 217 as a substrate holding unit that holds the wafers 200 as substrates in a multi-stage in a horizontal posture is provided below the processing furnace 202. A boat elevator 121 is provided as an elevating means for elevating and lowering, and a seal cap 219 as a lid is attached to the tip of an elevating member 122 attached to the boat elevator 121 to support the boat 217 vertically. . Between the boat elevator 121 and the cassette shelf 109, a transfer elevator 113 as an elevating means is provided, and a wafer transfer machine 112 as a transfer means is attached to the transfer elevator 113. Next to the boat elevator 121, a furnace port shutter 116 is provided as a shielding member that has an opening / closing mechanism and closes the lower surface of the processing furnace 202.

  The cassette 100 loaded with the wafer 200 is loaded into the cassette stage 105 from an external transfer device (not shown) in an upward posture and rotated by 90 ° on the cassette stage 105 so that the wafer 200 is in a horizontal posture. Be made. Further, the cassette 100 is moved from the cassette stage 105 to the cassette shelf 109 or the spare cassette shelf 110 by cooperation of the raising / lowering operation of the cassette elevator 115, the transverse operation, the advance / retreat operation of the cassette transfer machine 114, and the rotation operation. Be transported.

  The cassette shelf 109 has a transfer shelf 123 in which the cassette 100 to be transferred by the wafer transfer device 112 is stored. The cassette 100 to which the wafer 200 is transferred is the cassette elevator 115, The cassette is transferred to the transfer shelf 123 by the cassette transfer device 114.

  When the cassette 100 is transferred to the transfer shelf 123, the wafer 100 is lowered from the transfer shelf 123 by the cooperation of the advancing / retreating operation, rotation operation, and lifting / lowering operation of the transfer elevator 113. The wafer 200 is transferred to the boat 217.

When a predetermined number of wafers 200 are transferred to the boat 217, the boat 121 is inserted into the processing furnace 202 by the boat elevator 121, and the seal cap 219 is inserted.
As a result, the processing furnace 202 is hermetically closed. The wafer 200 is heated and the processing gas is supplied into the processing furnace 202 in the hermetically closed processing furnace 202, and the wafer 200 is processed.

  When the processing on the wafer 200 is completed, the wafer 200 is transferred from the boat 217 to the cassette 100 of the transfer shelf 123 by the reverse procedure of the above-described operation, and the cassette 100 is transferred to the cassette transfer machine. 114 is transferred from the transfer shelf 123 to the cassette stage 105 and is carried out of the casing 101 by an external transfer device (not shown). The furnace port shutter 116 closes the lower surface of the processing furnace 202 when the boat 217 is in the lowered state, and prevents outside air from being caught in the processing furnace 202.

  The transport operation of the cassette transfer machine 114 and the like is controlled by the transport control means 124.

Next, the outline of the processing furnace 202 of the vertical ALD apparatus according to the embodiment will be described with reference to FIG.
A reaction tube 203 constituting a processing chamber 201 for accommodating the wafer 200 is provided inside a heater 207 as a heating means. The reaction tube 203 is supported by the furnace port flange 205. The lower end opening of the furnace port flange 205 is hermetically closed by a seal cap 218, and a boat 217 is erected on the seal cap 218 and inserted into the reaction tube 203. On the boat 217, a plurality of wafers 200 to be batch-processed are stacked in a multi-stage in the tube axis direction in a horizontal posture. The heater 207 heats the wafer 200 in the reaction tube 203 to a predetermined temperature.

  The reaction tube 203 is provided with two gas supply pipes 232a and 232b as supply means for supplying the first and second source gases into the reaction tube 203. The first gas supply pipe 232 a that supplies the first source gas is connected to the furnace port flange 205 that supports the reaction tube 203. A second gas supply pipe 232 b that supplies a first source gas containing an O-containing gas and an H-containing gas different from the second source gas is connected to the top of the reaction tube 203. On the opposite side of the furnace port flange 205 from the first gas supply pipe 232a, an exhaust pipe 231 is provided as exhaust means for exhausting the processing chamber 201. The exhaust pipe 231 is provided with a vacuum pump 246. The inside is evacuated.

  The first gas supply pipe 232 a is connected to a nozzle 233 that is erected along the boat 217 in the reaction tube 203. The nozzle 233 is provided with a large number of outlet holes 248a along the nozzle axis direction so as to face a large number of wafers 200 stacked in multiple stages.

  In order to uniformly supply the second source gas from the gas upstream wafer 200 to the gas downstream wafer 200, the outlet hole 248a reduces the gas upstream outlet hole diameter and increases the gas downstream outlet hole diameter. It is preferable to change the conductance so that the gas is blown evenly upstream and downstream.

  Further, a controller 125 is provided as a control means for controlling the above-described two kinds of source gas supply methods and the film forming temperature of the wafer 200. The controller 125 is a gas supply control means for controlling valves (not shown) provided in the first gas supply pipe 232a and the second gas supply pipe 232b so as to alternately and repeatedly flow two kinds of gases one by one. And temperature control means for controlling the heater 207 so that the wafer temperature by the heater heating becomes the film forming temperature.

Next, a method for forming a film using the processing furnace 202 of the vertical ALD apparatus described above will be described with reference to FIG. Film is formed a SiO _2. DCS (SiH ₂ Cl ₂ : dichlorosilane) is used as the first source gas, and oxygen (O ₂ : oxidizing gas) and hydrogen (H ₂ : reducing gas) are used as the second source gas.

A wafer 200 to be deposited is loaded into a boat 217 and carried into a reaction tube 203 (hereinafter also simply referred to as a furnace). Next, a SiO ₂ film is formed on the wafer. The furnace temperature at this time is a temperature at which a film having good adhesion to the base film and few interface defects is formed, for example, 450 to 600 ° C. For this film formation, ALD is used in which DCS, O ₂ and H ₂ are alternately flowed to form a film for each atomic layer.

  First, the exhaust gas is exhausted from the exhaust pipe 231 while DCS is supplied into the processing chamber 201 from the first gas supply pipe 232a. DCS reacts at the furnace temperature. At this time, DCS is supplied at 10 sccm to 300 slm for 0.1 seconds to 60 seconds while maintaining the furnace pressure at a relatively low pressure of 13 Pa (0.1 Torr) to 1333 Pa (10 Torr). Since the source gas supplied into the processing chamber 201 is only DCS, the DCS causes a surface reaction with the base film on the wafer 200 without causing a gas phase reaction, and Si atoms are adsorbed on the base film.

After the Si atoms are adsorbed, for example, the inside of the processing chamber 201 is purged from the first gas supply pipe 232a with N ₂ to exhaust the residual gas in the first gas supply pipe 232a and the processing chamber 201. The purge N ₂ gas flow rate at this time is 10 sccm to 100 slm, and the purge time is 0.1 second to 60 seconds.

Next, oxygen and hydrogen are supplied into the processing chamber 210 from the second gas supply pipe 232b. By supplying O ₂ and H ₂ , an oxygen active species O ^* is generated as described later, and this oxygen active species and the Si atoms on the base film are surface-reacted to form a SiO ₂ film.

When H ₂ and O ₂ are used, H ₂ initiates reaction with O ₂ at 500-600 ° C. At this time, it is considered that the following reaction occurs in the processing chamber.
H ₂ + O ₂ → H ^* + HO ₂
O ₂ + H ^* → OH ^* + O ^*
H ₂ + O ^* → H ^* + OH ^*
H ₂ + OH ^* → H ^* + H ₂ O
O ^* (oxygen active species), OH ^* (hydroxyl active species)

Therefore, the furnace temperature when supplying O ₂ and H ₂ is set to 500 ° C. or higher. O ^* (active oxygen species) extends the life of active species when the pressure in the furnace is a low pressure of 266 Pa (2 Torr) or less. Therefore, in order to improve the uniformity of the thin film within the wafer surface and between the wafer surfaces, the furnace pressure at this time is set to 266 Pa or less.
Further, the H ₂ flow rate to flow at this time is 10 sccm to 30 slm, the O ₂ flow rate is 10 sccm to 30 slm, and the H ₂ / O ₂ gas supply time is 0.1 to 60 seconds.

After forming the SiO ₂ film, the inside of the processing chamber 201 is purged with N ₂ to exhaust the residual gas in the processing chamber 201. The purge N ₂ gas flow rate at this time is 10 sccm to 100 slm, and the purge time is 0.1 second to 60 seconds.

The above-described process of alternately flowing DCS, oxygen, and hydrogen is defined as one cycle. By repeating this cycle, a SiO ₂ film having a predetermined thickness is formed.
These cycle controls are performed by the controller 125.

As described above, according to the present embodiment, in order to form a SiO ₂ film by ALD using DCS, Si ₂ and O ₂ atoms are increased by one layer and SiO ₂ is deposited. In this case, O ₂ and H ₂ are introduced into a furnace under reduced pressure to generate oxygen active species O ^* .
Therefore, compared with the case where moisture with low purity is used, high-quality oxygen active species can be obtained, high-quality film formation can be realized, semiconductor device performance can be improved, and productivity can be increased. Also, if the furnace temperature _{H 2} is the _{O 2} and the start 500 to 600 ° C. The reaction, only supplies the _{O 2} and _{H 2} into the processing chamber, it is possible to generate oxygen active species ^{O *} Further, since neither a moisture generator nor an ozone generator is required, and a gas that is easily available and inexpensive such as generally used O ₂ and H ₂ is used, cost reduction can be realized.
In particular, if the SiO ₂ film forming method according to the present embodiment is applied to the spacer portion of the MOSFET, it is possible to realize a low temperature of the film formation of the offset spacer and the spacer and a thin film of the offset spacer and the spacer.

In the above-described embodiment, the case where the SiO ₂ film is formed as a thin film containing oxygen has been described, but the present invention is not limited to this. For example, HfO ₂ and ZrO ₂ can also be applied using the above-described apparatus and method.

Here, the film forming conditions of HfO ₂ and ZrO ₂ are exemplified as follows.
Furnace temperature: 450 ° C. to 600 ° C. (however, furnace temperature when O ₂ / H _{2 is} supplied: 50 ° C. to 600 ° C.)
Furnace pressure: 13 Pa (0.1 Torr) to 1333 Pa (10 Torr) (however, the furnace pressure when supplying O ₂ / H ₂ is 266 Pa or less)
HfCl ₄ / ZrCl ₄ : 10 sccm to 300 slm (gas flow rate during sublimation)
H ₂ flow rate: 10sccm~30slm
O ₂ flow rate: 10 sccm to 30 slm
Purge N ₂ flow rate: 10 sccm to 100 slm
The time for each gas to flow per cycle is as follows.
HfCl ₄ / ZrCl ₄ : 0.1 seconds to 500 seconds Purge gas (N ₂ ): 0.1 seconds to 180 seconds H ₂ / O ₂ : 0.1 seconds to 180 seconds Purge gas (N ₂ ): 0.1 seconds to 120 seconds

In this way, oxygen active species O ^* is generated using O ₂ and H ₂ as oxidizing gases, and this is surface-reacted with Hf atoms and Zr atoms adsorbed on the wafer, so that high-quality HfO _{2 is formed} on the wafer. Or ZrO ₂ can be deposited. In particular, when the method for forming HfO ₂ or ZrO ₂ according to the present embodiment is applied to the gate insulating film of a MOSFET, the temperature of the gate insulating film can be lowered and the thickness of the gate insulating film can be reduced.

200 wafer (substrate)
201 Processing chamber 207 Heater (heating means)
232a First gas supply pipe (first gas supply means)
232b Second gas supply pipe (second gas supply means)
231 Exhaust piping (exhaust means)
125 controller (control means)

Claims (4)

A reaction tube for laminating and accommodating a plurality of substrates;
First gas supply means for supplying a first source gas into the reaction tube;
A second gas supply means for supplying a second source gas containing an O-containing gas and an H-containing gas in the reaction tube;
An exhaust means for exhausting the reaction tube;
Control means for controlling the first gas supply means, the second gas supply means and the exhaust means,
The first gas supply means is connected to a lower portion of the reaction tube, and is connected to a first gas supply pipe for supplying the first source gas into the reaction tube and the first gas supply pipe. A gas nozzle standing in the reaction tube along the stacking direction of the substrate and having a plurality of gas supply ports,
The second gas supply means includes a second gas supply pipe connected to the top of the reaction tube and supplying the second source gas into the reaction tube,
The control means controls the first gas supply means, the second gas supply means, and the exhaust means so that the first source gas and the second source gas are alternately mixed without being mixed with each other. And an oxide film is formed on the substrate. The substrate processing apparatus according to claim 1, wherein the exhaust unit includes a gas exhaust pipe that is connected to the lower side of the reaction tube and opposite to the first gas supply tube. Supplying a first source gas to a plurality of substrates stacked in a reaction tube from a plurality of gas supply ports that open to gas nozzles erected along the stacking direction of the substrates;
Exhausting the first source gas remaining in the reaction tube;
Supplying a second source gas containing an O-containing gas and an H-containing gas from the top in the reaction tube;
Exhausting the second source gas remaining in the reaction tube;
A method of manufacturing a semiconductor device, wherein an oxide film is formed on the substrate by sequentially performing a plurality of times. A semiconductor device having an oxide film,
The oxide film is
Supplying a first source gas to a plurality of substrates stacked in a reaction tube from a plurality of gas supply ports that open to gas nozzles erected along the stacking direction of the substrates;
Exhausting the first source gas remaining in the reaction tube;
Supplying a second source gas containing an O-containing gas and an H-containing gas from the top in the reaction tube;
Exhausting the second source gas remaining in the reaction tube;
The semiconductor device is formed on the substrate by sequentially performing a plurality of times.

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