JPH05175162A - Dry etching system - Google Patents

Abstract

PURPOSE:To perform uniform plasma etching on a thin film on the rear surface of a substrate to be processed. CONSTITUTION:A cathode electrode 2 which has a gas introducing port 11 and upon which high-frequency power is impressed is provided in the lower section of a chamber 1 and, at the same time, an upper plate 3 having an exhaust port 12 is provider in the upper section of the chamber 2. Then a holder 7 for placing a substrate (semiconductor wafer 24) to be processed is arranged in the chamber 1 so that the rear surface of the substrate to be processed can face the cathode electrode 2. Therefore, a thin film on the rear surface of the substrate to be processed can be uniformly plasma-etched under a little-dust and less-damage condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus, and more particularly, to a polysilicon film formed on the back surface of a substrate to be processed such as a semiconductor wafer or a glass substrate for liquid crystal display element,
The present invention relates to a dry etching device suitable for etching removal treatment of a silicon nitride film or a silicon oxide film.

[0002]

2. Description of the Related Art Generally, in a semiconductor element manufacturing process, a dry etching apparatus is used for forming a thin film of a predetermined substance on a semiconductor wafer and removing an unnecessary portion thereof. In this dry etching apparatus, a pair of electrodes is arranged in a chamber kept at a predetermined vacuum pressure, one electrode is grounded, and a high-frequency power is supplied between the electrode and the other electrode while introducing a reaction gas into the chamber. The radical molecules of the gas ions generated by forming a high electric field are caused to collide with and react with the surface of the semiconductor wafer, which is the material to be etched, placed in the chamber to perform the etching process.

As this type of dry etching apparatus,
The equipment described in Chapter 3 of the special article entitled "Recent Ultra LS Technology and Manufacturing Equipment" in "Electronic Materials" (March 1983 issue) published by the Industrial Research Committee, and the publication of industrial books by Takuo Sugano The apparatus described on page 108 of "Chapter 2 Plasma Apparatus" of "Semiconductor Plasma Process Technology" (1980) is known.

Each of the above conventional devices is a parallel plate type device in which a pair of electrodes such as aluminum constituting a cathode electrode and an anode electrode are arranged in parallel in a chamber made of aluminum or quartz. Then, the substrate to be processed is brought into contact with the entire surface of the anode electrode and is subjected to etching treatment. The element substrate, the electrode layer, or the like is formed and patterned on the front surface, which is the main surface, of the substrate to be processed, and the film forming substance is also deposited on the back surface in this film forming step. The element constituting layer or the electrode layer deposited on the back surface is essentially unnecessary and needs to be removed.

In order to remove the unnecessary deposited layer by etching with the above-described conventional etching apparatus, a reversing mechanism for the substrate to be processed is provided in the transport system of the etching apparatus, and the back surface is faced to the cathode side to perform etching processing. I am trying. However, when the substrate to be processed is turned over, the surface side of the substrate to be processed (the surface side is coated with a resist for protection) directly contacts the anode electrode, and as a result, dust adheres to the main surface. There is a problem that the main surface is damaged.

Therefore, for etching the back surface of the substrate to be processed, the apparatus disclosed on pages 102 and 103 of "Chapter 2 Plasma Apparatus" of "Semiconductor Plasma Process Technology" is also used. The apparatus disclosed above is a cylindrical apparatus in which a pair of electrodes are fixed to the peripheral portion of a cylindrical quartz chamber and a boat for mounting a plurality of substrates to be processed vertically is provided in the chamber.

In this apparatus, since the reaction gas is passed along the axis of the cylindrical chamber,
It is difficult to make the plasma density in the chamber and the reaction gas flow uniform, and both the uniformity of etching within the surface of the substrate to be processed and the uniformity between the substrates to be processed are low, and the entire surface is exposed to plasma, so the main surface There is a lot of damage.

[0008]

As described above, the conventional dry etching apparatus has the following problems. First, in the former parallel plate type dry etching apparatus, the material to be etched must be inverted in order to etch the back surface of the substrate to be processed. for that reason,
The resist applied for protection on the surface (main surface) directly contacts the electrode. Further, since the electrode remains in contact with the surface side even during the transportation of the substrate to be processed, the resist is peeled off to become a foreign matter, which causes a problem of dust generation and damage to the surface side.

Further, in the latter cylindrical dry etching apparatus, it is difficult to make the plasma density and the gas flow uniform throughout the chamber. There is a problem that the uniformity is low. Specifically, in this type of dry etching apparatus, since the electrodes are arranged concentrically with respect to the substrate to be processed, the etching rate is higher toward the peripheral edge in the plane of the substrate to be processed, and Since a plurality of substrates to be processed are arranged on the boat, there is a problem that the etching rate of the substrates to be processed placed on both ends of the boat is higher than that of the central part. Furthermore, since the entire surface of the substrate to be processed is exposed to plasma, there is a problem that the main surface is greatly damaged.

An object of the present invention is to provide a main surface of a substrate to be processed, which is non-contact with no damage or dust generation, has high uniformity of a thin film deposited on the back surface of the substrate to be processed, and is free from damage to the main surface. It is an object of the present invention to provide a dry etching apparatus capable of performing etching processing with a minimum.

[0011]

In order to achieve the above object, the present invention has a vacuum chamber 1 constituting an anode electrode and a cathode electrode 2 installed in the vacuum chamber 1, and the cathode electrode 2 The substrate 24 to be processed is opposed to the substrate 24 at a predetermined interval, and a high electric field is formed between the cathode electrode 2 and the anode electrode in the reaction gas atmosphere introduced into the vacuum chamber 1, so that the substrate 24 is processed. In a dry etching apparatus for performing an etching process, the cathode electrode 2 is disposed on the inner bottom of the chamber 1, and the substrate 24 to be processed is placed above the cathode electrode 2 with a predetermined distance from the cathode electrode 2. A holder 7 is provided for placing the backsides thereof so that they face each other, and the backside of the substrate to be processed 24 placed on the holders 7 is etched. Characterized by being configured to ring.

Further, according to the present invention, a vacuum chamber 1 constituting an anode electrode and a cathode electrode 2 installed in the vacuum chamber 1 are provided, and a substrate 24 to be processed is opposed to the cathode electrode at a predetermined interval, In a dry etching apparatus for etching the substrate to be processed 24 by forming a high electric field between the cathode electrode 2 and the anode electrode in a reaction gas atmosphere introduced into the vacuum chamber 1, the cathode electrode 2 is removed. The substrate 24 to be processed is disposed on the inner bottom of the chamber 1 and at a predetermined distance above the cathode electrode 2.
A fixed holder 7 having a plurality of fixing claws 73 for mounting the cathode electrode 2 with the back surface thereof facing the cathode electrode 2.
And a movable holder 1 having a plurality of movable claws 74 which are arranged up and down and rotated with respect to the fixed holder 7 to move the mounting position of the substrate 24 to be mounted on the fixed holder 7.
And the substrate to be processed 2 mounted on the fixed holder 7.
The back surface of No. 4 is characterized in that the entire surface can be etched.

The dry etching apparatus of the present invention may be provided with a substrate transfer mechanism for transferring the substrate to be processed, and a holder for supporting the substrate to be processed in the chamber is configured as a part of the substrate transfer mechanism. You can also do it. Further, the entire chamber may be formed of a conductor, and the anode electrode and the cathode electrode may be arranged in the chamber through an insulator, or the chamber may be formed of an insulator, and the inner bottom portion and the ceiling of the chamber may be formed. You may arrange | position a cathode electrode and an anode electrode in the part, respectively.

Further, a reaction gas supply path is provided on the back surface of the cathode electrode, a large number of gas inlets are provided in the cathode electrode, and a gas vent hole or a gas removal hole is provided in a portion of the fixed holder near the substrate mounting position. By forming the gas vent slit, the reaction gas can uniformly act on the back surface of the substrate to be processed. By providing a gas exhaust port for exhausting gas to the outside of the chamber in the upper peripheral part of the chamber,
It is possible to minimize the gas contact with the main surface (surface) of the substrate to be processed.

[0015]

In the above-described structure of the present invention, by providing the fixed holder for supporting the limited peripheral edge or a part of the peripheral edge of the back surface of the substrate to be processed, etching can be performed with the back surface facing downward (cathode electrode side). Since there is no contact on the surface side (main surface) during etching and during transportation, it is possible to prevent dust from adhering to or damage the main surface.

Further, since the cathode electrode is arranged so as to face the back surface of the substrate to be processed and the plasma and the reaction gas flow between the substrate to be processed and the cathode electrode can be made uniform, highly uniform etching can be performed. It can be carried out. Furthermore, since the holder has a structure in which the surface side of the substrate to be processed is not easily exposed to plasma, the main surface is less damaged.

Further, in addition to the fixed holder, by providing a movable holder that moves up and down, the portion of the material to be etched that comes into contact with the fixed holder can be exposed to the plasma, and the portion that comes into contact with the holder can be etched. Can be prevented from decreasing.

[0018]

Embodiments of the dry etching apparatus according to the present invention will be described below in detail with reference to the drawings. 1 is a schematic sectional view illustrating a first embodiment of a dry etching apparatus according to the present invention, in which 1 is a chamber for forming a vacuum space, 2 is a cathode electrode, 3 is an upper plate, 4 is a cathode electrode support, 5 Is an insulator (insulator), 6 is a high frequency power source, 7 is a holder, 72 is a flange of the holder 7,
8 is a gas supply path, 9 is a mass flow controller, 10 is a gas valve, 11 is a gas inlet provided in the cathode electrode 2, 12 is an exhaust port for discharging gas from the chamber 1, 2
4 is a semiconductor wafer.

In the figure, a cathode 1 and an upper plate 3 are arranged in a chamber 1. The cathode electrode 2 is attached to the chamber 1 via a cathode electrode support 4 and an insulating insulator 5, and is connected to a high frequency power supply 6 via the cathode electrode support 4. In addition, the upper plate 3 as an anode electrode forming the casing of the chamber 1 is grounded.

The holder 7 has a substantially cylindrical shape and is fixed to the bottom of the chamber 1 by a flange 72.
Are placed on the holder 7 attached to the chamber 1. Further, a gas supply passage 8 is provided in the cathode electrode support 4, and a plurality of kinds of reaction gases (process gases) whose flow rates are controlled by the mass flow controller 9 are used in the gas valve 1.
When 0 is opened, the gas is introduced into the chamber 1 through the gas supply passage 8 and the gas introduction port 11 provided in the cathode electrode 2.
At the same time, the interior of the chamber 1 is maintained at a predetermined degree of vacuum by the exhaust from the exhaust port 12.

In this state, by applying high-frequency power to the cathode electrode 2 from the high-frequency power source 6 via the cathode electrode support 4, plasma is generated in the chamber 1 (mainly inside the holder 7), and the cathode electrode of the semiconductor wafer 24 is produced. The surface (back surface) facing 2 is etched. According to the above embodiment, the semiconductor wafer 24 has the front surface (main surface).
Is facing upward (upper plate side) and the back surface is cathode electrode 2
The back surface is supported by the holder 7 so as to face the. As a result, when the semiconductor wafer 24 is supported in the chamber 1, there is no contact with the surface side of the semiconductor wafer 24, so that there is a problem of dusting or damage on the surface due to the contact, unlike the prior art. It won't happen.

Further, in this configuration, the semiconductor wafer 24
Since the back surface of the semiconductor wafer 24 and the cathode electrode 2 are arranged so as to face each other, a uniform plasma gas flow can be supplied to the back surface of the semiconductor wafer 24. As a result, an etching process with good uniformity can be performed. Since the surface side thereof is hard to be exposed to plasma, damage to the element constituting layer formed or patterned on the surface is extremely small.

FIG. 2 is a plan view seen from the upper plate side showing an example of a state in which the semiconductor wafer is placed on the holder in the first embodiment of the dry etching apparatus according to the present invention shown in FIG. And the same reference numerals correspond to the same parts,
Reference numeral 70 is an opening of the holder 7, and 71 is a gas vent hole. The semiconductor wafer 24 is placed in the opening 70 of the flange portion 74 of the holder 7 with the inner peripheral edge of the opening 70 in contact with the outer peripheral edge. The overlapping portion of the inner peripheral edge and the outer peripheral edge is preferably outside the effective area of the surface of the semiconductor wafer 24.

The bottom of the holder 7 is fixed to the bottom of the chamber 1 by a flange 72, and the upper part of the holder 7 is close to the semiconductor wafer 24 to be mounted and has a degassing hole 71 in the collar 74.
Are formed. The reaction gas from the cathode electrode 2 side flows toward the exhaust port 12 through the gas vent hole 71 (see FIG. 1). Instead of providing the gas vent hole 71, a plurality of protrusions projecting toward the upper plate 3 are provided in the flange portion 74 of the holder near the inner peripheral edge of the flange portion 74 in the circumferential direction, and the semiconductor wafer 24 is provided with the protrusions. The reaction gas may pass through the protrusions by being mounted on the substrate.

FIG. 3 is a plan view seen from the upper plate side showing another example of the state in which the semiconductor wafer is placed on the holder in the first embodiment of the dry etching apparatus according to the present invention shown in FIG. The same reference numerals as those in FIG. 1 correspond to the same parts, 71 'denotes a gas vent slit, and 73 denotes a fixed claw.
This holder 7 is similar to that shown in FIG. 2 above in that it is fixed to the bottom of the chamber 1 by a flange 72.
The collar portion 74 of the holder 7 is provided with a fixed claw 73 that horizontally projects toward the center, and the semiconductor wafer 24 is placed on the fixed claw 73.
By mounting the semiconductor wafer 24 on the fixing claw 73, the contact area between the holder 7 and the semiconductor substrate 24 can be reduced, and the back surface can be uniformly etched.

Then, the collar portion 74 and the semiconductor wafer 24
The collar portion 74 is provided so that a degassing slit 71 is formed between and. The fixing claw 73 may have its tip end projected upward in the direction of the mounted semiconductor wafer 24. As described above, with the configuration of the holder 7 as shown in FIG. 2 or FIG. 3, a uniform plasma gas flow can be supplied to the back surface of the semiconductor wafer 24, and an etching process with good uniformity can be performed. Since the surface side is less likely to be exposed to plasma, film formation on the surface or damage to the element constituting layer is extremely small.

FIG. 4 is a schematic sectional view for explaining a second embodiment of the dry etching apparatus according to the present invention. The same reference numerals as those in FIGS. 1 and 3 correspond to the same parts, 13 is a movable holder, and 75 is It is a movable claw provided on the movable holder 13. Further, 14 is a shaft fixed to the movable holder 13, 15 is a lift plate, 16 is a power transmission means such as a belt, 17 is a lift plate drive means such as an air cylinder, and 18 is a rotation drive means such as a motor that rotates the shaft 14. Is.

In this embodiment, etching of the mounting portion on the back surface of the semiconductor wafer 24 mounted on the holder 7 can be advanced. In the figure,
The holder 7 is of the type having the fixing claw 73 as shown in FIG.
4 is provided with a movable holder 13 capable of moving up and down and rotating.

The movable holder 13 is mounted on the fixed claw 73 provided on the flange portion 74 of the holder 7 to perform the etching process.
As shown in the drawing, it stops at a position below the fixed claw 73 without making contact with. A shaft 14 is attached to the movable holder 13, the shaft 14 communicates with the atmosphere side outside the chamber 1, is rotatably attached to an elevating plate 15 in the atmosphere, and extends upward from the elevating plate 15 in the drawing. ..

A pulley 16 ′ is fixed to the shaft 14 above the lifting plate 15, and a belt 16 is provided on the drive pulley 16 ″ of the motor 18 mounted on the lifting plate 15 and the pulley 16 ′. Further, air cylinders 17 and 17 'are provided between the chamber 1 and the elevating plate 15 so that the elevating plate 15 can be driven up and down.

In the above structure, when the mounting position of the semiconductor wafer 24 on the fixed holder 7 is moved, the air cylinders 17 and 17 'are driven to raise the elevating plate 15 to move the movable portion connected to the shaft 14. The movable claw 75 of the holder 13 supports the semiconductor wafer 24 and lifts it from the fixed claw 73 of the fixed holder 7. When the semiconductor wafer 24 is lifted above the fixed claw 73 of the fixed holder 7, the driving of the air cylinders 17 and 17 ′ is stopped and the movable holder 13 is stopped.
Stop rising.

In this state, the motor 18 is driven to rotate the shaft 14 by a certain angle to a position avoiding the fixed claw 73 by the belt 16 suspended around the drive pulley 16 "and the pulley 16 'of the shaft 14. This will
The semiconductor wafer 24 rotates by a certain angle. Shaft 14
After rotating the motor by a certain angle, stop the motor 18,
The air cylinders 17 and 17 ′ are driven to lower the movable holder 7, and the semiconductor wafer 24 is placed on the fixed claw 73.
The movable holder 13 is stopped at a further lowered position, and the movable claw 75 is separated from the back surface of the semiconductor wafer 24.

As a result, the portion of the back surface of the semiconductor wafer 24 that overlaps with the fixed claw 73 can be etched, and the entire back surface can be uniformly etched. 5 and 6 are explanatory views of the semiconductor wafer viewed from the rear surface of the holder for explaining the operation of moving the mounting position of the semiconductor wafer on the fixed holder in FIG. The same symbols as 4 correspond to the same parts.

In FIG. 5, the semiconductor wafer 24 is moved to the movable holder 13
Of the movable holder 13 is shown with the movable claw 74 of the
The movable claw 74 is located at the position of arrow A. 6 shows a state in which the movable holder 13 is rotated and the movable claw 74 is moved to the position of the arrow B. By this movement, the fixed holder 7
The supporting portion of the semiconductor wafer 24 placed on the fixed claw 73 of the above is sufficiently exposed to the plasma, and the back surface of the semiconductor wafer 24 is uniformly etched by performing the above movement at least once. can do.

FIG. 7 is an explanatory view of the overall structure of a dry etching system to which the present invention is applied. The same reference numerals as those in the drawings for explaining the respective embodiments correspond to the same portions, and 19 is a reaction gas supply source. A gas cylinder, 20-
1, 20-2 are vacuum preparatory chambers, 21-1, 21-2 are vacuum exhaust systems, 22 is a loader, 23 is an unloader, 25
-1 to 25-4 are robots, and 26-1 to 26-4 are gates.

In the figure, the semiconductor wafer before processing is loaded from the loader 22 into the vacuum preliminary chamber 20-1 by the robots 25-1 and 25-2. At this time, the gate 26-1
Is open, the gate 26-2 is closed, and the vacuum preliminary chamber 20-1 is in the atmosphere. The chamber 1 is always kept in a predetermined vacuum atmosphere by the vacuum exhaust system 21-2.

After the semiconductor wafer is loaded into the vacuum preliminary chamber 20-1, the gate 26-1 is closed and the vacuum exhaust system 21-1 is operated to make the vacuum preliminary chamber 20-1 similar to the chamber 1. The gate 26-
2, the semiconductor wafer 24 is opened by the robot 25-2.
Is placed on the holder 7 of the chamber 1. Gas cylinder 1
A predetermined reaction gas is introduced into the chamber 1 from 9 and high frequency power energy is applied from the high frequency power source 6 to the cathode electrode 2 to perform the etching process of the semiconductor wafer 24.

When the etching process is completed, the gate 26-3 of the chamber 1 is opened, and the robot 25-3 takes out the semiconductor wafer 24 from the chamber 1 to the vacuum preliminary chamber 20-2. At this time, the gate 26-4 is closed and the vacuum preliminary chamber 20-2 is in the same predetermined vacuum atmosphere as the chamber 1. After the semiconductor wafer 24 is taken out to the vacuum preliminary chamber 20-2, the gate 26-3 is closed, the gate 26-4 is opened to open the vacuum preliminary chamber 20-2 to the atmosphere, and the robot 25-3 performs the semiconductor operation. Board 24
To the robot 25-4, and the robot 25-4 transfers the received semiconductor substrate 24 to the unloader 23. afterwards,
The gate 26-4 is closed, and the evacuation system 21-1
Is exhausted to a predetermined vacuum atmosphere.

The back surface of the semiconductor wafer 24 is etched by performing the above series of operations. In addition, although the above-mentioned embodiment is about the back surface etching of the semiconductor wafer, it goes without saying that the present invention is not limited to this and can be applied to the front surface etching.

The present invention can be applied not only to semiconductor wafers but also to the manufacture of glass plates for liquid crystal display devices, substrates for other electronic or electric devices, and the like.

[0041]

As described above, according to the dry etching apparatus of the present invention, the cathode electrode is provided in the lower part of the chamber, and the holder is arranged around the cathode electrode so as not to contact the surface of the substrate to be processed such as a semiconductor wafer. Thus, the substrate to be processed can be etched and transported, and plasma etching can be performed without causing dusting or damage to the substrate to be processed due to contact with the holder or the carrier.

At the same time, the thin film on the back surface of the substrate to be processed such as a semiconductor wafer can be etched with high uniformity, and since the plasma does not wrap around to the front surface side of the substrate to be processed, etching with reduced damage to the surface is performed. It can be processed. Then, in addition to a fixed holder provided in the chamber for supporting a substrate to be processed such as a semiconductor wafer, a movable holder that moves up and down independently of the fixed holder is provided so as to contact the fixed holder. The thin film on the back surface of the substrate to be processed can also be completely etched.

[Brief description of drawings]

FIG. 1 is a schematic sectional view illustrating a first embodiment of a dry etching apparatus according to the present invention.

FIG. 2 is a plan view seen from the upper plate side showing an example of a state in which a semiconductor wafer is placed on a holder in the first embodiment of the dry etching apparatus according to the present invention shown in FIG.

FIG. 3 is a plan view seen from the upper plate side showing another example of the state in which the semiconductor wafer is placed on the holder in the first embodiment of the dry etching apparatus according to the present invention shown in FIG.

FIG. 4 is a schematic sectional view illustrating a second embodiment of the dry etching apparatus according to the present invention.

FIG. 5 is an explanatory diagram of the mounted semiconductor wafer before moving, which is viewed from the rear surface direction of the holder, for explaining the operation of moving the mounting position of the semiconductor wafer on the fixed holder in FIG. 4;

FIG. 6 is an explanatory diagram after moving the mounted semiconductor wafer as viewed from the rear surface direction of the holder for explaining the operation of FIG. 4 in which the mounting position of the semiconductor wafer is moved on the fixed holder.

FIG. 7 is an explanatory diagram of the overall configuration of a dry etching system to which the present invention is applied.

[Explanation of symbols]

 1 Chamber 2 Cathode Electrode 3 Upper Plate 4 Cathode Electrode Support 5 Insulator 6 High Frequency Power Supply 7 Holder 8 Gas Supply Channel 9 Mass Flow Controller 10 Gas Valve 11 Gas Inlet 12 Exhaust 13 13 Movable Holder 14 Shaft 15 Elevating Plate 16 Belt 17, 17 'Air Cylinder 18 Motor 19 Gas cylinder 20-1, 20-2 Vacuum reserve chamber 21-1, 21-2 Vacuum exhaust system 22 Loader 23 Unloader 24 Semiconductor wafer 25-1 to 25-4 Robot 26-1 to 26-4 Gate 71 gas Vent hole 71 'Gas vent slit 72 Flange 73 Fixed claw 74 Collar

Claims (2)

[Claims] 1. A reaction including a vacuum chamber constituting an anode electrode and a cathode electrode installed in the vacuum chamber, a substrate to be processed being opposed to the cathode electrode at a predetermined interval, and introduced into the vacuum chamber. In a dry etching apparatus for etching the substrate to be processed by forming a high electric field between the cathode electrode and the anode electrode in a gas atmosphere, the cathode electrode is arranged on the inner bottom of the chamber, and A configuration is provided above the cathode electrode for mounting the substrate to be processed with the back surface facing the cathode electrode at a predetermined distance, and a holder for etching the back surface of the substrate to be processed placed on the holder. The dry etching apparatus characterized in that 2. A reaction in which a vacuum chamber forming an anode electrode and a cathode electrode installed in the vacuum chamber are provided, a substrate to be processed is opposed to the cathode electrode at a predetermined interval, and the substrate is introduced into the vacuum chamber. In a dry etching apparatus for etching the substrate to be processed by forming a high electric field between the cathode electrode and the anode electrode in a gas atmosphere, the cathode electrode is arranged on the inner bottom of the chamber, and A fixed holder having a plurality of fixing claws for mounting the substrate to be processed with a predetermined distance above the cathode electrode with its back surface facing the cathode electrode, and ascending / descending / rotating with respect to the fixed holder. And a plurality of movable claws for changing the mounting position of the substrate to be mounted on the fixed holder. A holder provided, a dry etching apparatus, wherein a rear surface of the substrate to be processed which is placed on the fixing holder and the entire etchable configuration.