JP2001057371A - Annealing method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an annealing method and an annealing cassette which is used for carrying out the same, where static electricity is restrained from occurring when substrates are housed in a cassette as stacked in layers corresponding to whether the substrates to treat are formed of metal or insulator in a batch-type annealing process. SOLUTION: When a substrate is formed of metal or a metal film is formed on it, the substrates are stacked up in layers in a heat-resistant cassette 3 in such a manner where a grounded conductor board 20 is interposed between the substrates at each time when substrates prescribed in number are stacked up. When the substrate 2b is formed of non-conductive material, a normal space t2 between the adjacent laminated substrates 2b is so controlled as to decrease electric charge or a potential.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annealing technique for activating and crystallizing a substrate on which a semiconductor element is formed by batch processing, and more particularly to a laminated structure of a substrate used for manufacturing a semiconductor element. The present invention relates to a technique for suppressing static electricity generated during installation.

[0002]

2. Description of the Related Art In recent years, development has been actively pursued for lowering the temperature of a semiconductor device manufacturing process. The major reason is that, despite the fact that it is inexpensive and has good workability, it is necessary to form a semiconductor element on an insulating substrate such as glass having a low melting point. For example, when manufacturing an active matrix type liquid crystal display device, several hundred (vertical) ×
It is necessary to form several hundred (horizontal) thin film transistors, and in other cases, there is a similar request accompanying miniaturization of elements and multilayering of elements.

In the process of manufacturing a semiconductor element, an amorphous component or an amorphous semiconductor material contained in a semiconductor material is crystallized. A semiconductor material that originally has high crystallinity (has a large crystal grain size or is close to a single crystal) but has reduced crystallinity due to the impact of the dopant implanted due to irradiation with ions for impurity implantation. May be recovered, or the crystallinity may need to be further improved. Conventionally, thermal annealing has been used as a means for achieving such an object.

When this thermal annealing is applied to silicon which is a semiconductor material to be processed, it is usually at 600 ° C.
From 1 to 100 ° C. for 0.1 to 48 hours or more, thereby performing amorphous crystallization, recovery of crystallinity, improvement of crystallinity, and the like.

[0005] Such thermal annealing generally has a shorter processing time as the temperature is higher, but has little effect at a temperature of 500 ° C or less. Therefore, from the viewpoint of lowering the temperature of the process, it is necessary to replace the step conventionally performed by thermal annealing with another means. In particular, when a glass substrate is used as the substrate, it is required that the temperature in the thermal annealing be 600 ° C. or lower in order to prevent deformation due to melting due to heating. Moreover,
It is required to shorten the heating time as much as possible. In a liquid crystal display device, since liquid crystal is held between a pair of glass substrates having a gap of several μm, deformation of the substrate has a large effect on the display of the liquid crystal display device and must be avoided.

[0006] These annealing apparatuses are performed using a heating furnace 51 shown in FIG. That is, after the end of the previous step, the substrates 53 to be processed transferred by the transfer cassette 52 are transferred to the heat-resistant cassette 54 and placed in the heating furnace 51 while being stored in the heat-resistant cassette 54. Heating is performed for a predetermined time in the heating furnace 51 to perform an annealing process.
When the annealing process is completed, it is discharged from the activation furnace 51, transferred to the transport cassette 52, and then sent to the next step.

In general, in the annealing process, the temperature of the heating furnace 51 is required to be 500 ° C. or more, and a plurality of sheets are put in a cassette in order to reduce the required temperature rise and fall times during the processing step. , A batch type in which annealing is performed at once. Further, as shown in FIG. 7, the heat-resistant cassette 54 is a rack-shaped structure in which the substrates 53 are separated and stored one by one. Repeated insertion into heating furnace 51
Since it is discharged, it is made of a heat-resistant electrical insulator such as heat-resistant glass, quartz, or ceramic to prevent deformation due to heating.

When the substrates 53 to be processed are made of metal or a metal film formed on the surface, since the heat-resistant cassette 54 is an electric insulator, FIGS.
As shown in FIG. 6, even if a small amount of electric charge is charged on one substrate 53a, if the number of substrates 53a is large, a large amount of electric charge is induced to the substrates 53 at both ends by electrostatic induction. That is,
8 (a) to 8 (d) are explanatory views showing a state where the substrates 53a are sequentially stored one by one in a rack of a heat-resistant cassette, and the charged charges of the substrates 53a are added. ,
At both ends of the stacked substrates 53a, the charged charges increase in accordance with the number of stacked substrates 53a. FIG.
FIG. 8 (b) shows that two substrates 53a are stacked.
In FIG. 8 (c), 53a...
8A is three times as large as the case of FIG. 8A, and FIG. 8D is a diagram of FIG.
4 times as large as

Therefore, when the number of stacked substrates 53a is large, when an object serving as a ground approaches the vicinity of the substrates 53a, a discharge may occur and the circuit on the substrates 53a may be destroyed.

In order to prevent this, as shown in FIG. 9, the substrates 53a.
A grounding conductor 56 is provided at the contact portion of the device for grounding.

If the substrates 53 are electrically insulating,
Even when the ground conductor 56 is brought into contact with the substrate 53b, only the charges near the ground portion escape. Therefore, when a plurality of substrates 53b are provided, the capacitors having charges corresponding to the number of substrates 53b are provided, and the potential is increased.
When an object serving as the ground approaches the vicinity of b, a discharge may occur and the circuit 57 formed on the substrate 53b may be destroyed.

On the other hand, as shown in FIG. 10, an ionizer 58 is provided to neutralize the electric charges charged on the substrates 53b.

[0013]

In the structure of the cassette for accommodating the substrate as described above, the conductor for releasing the electric charge of the substrate is a metal. However, it is not always easy to make accurate contact with the substrate, and the substrate is deformed by repeated heating, and in the structure shown in FIG. 9, which is a general structure, when the ground conductor 56 is deformed, the position of the substrate changes. Substrate 53a
... the transfer accuracy is reduced. Further, the ground conductor 56 is
In the structure not in contact with the entire surface of 3a, the charge of the insulating substrate 53b cannot escape, and in the structure in which the ground conductor 56 is arranged on the entire surface, the substrate 53b may be damaged and damaged.

In the method using the ionizer 58 shown in FIG. 10, since dust is generated at the electrode portion of the ionizer 58, there is a problem that the substrates 53b are contaminated by the dust. For this reason, the ionizer 58 requires maintenance for cleaning the electrode portion, so that the operating rate of the annealing step is reduced.

The present invention has been made on the basis of these circumstances. In a batch-type annealing process, depending on whether a substrate to be processed is a metal or an insulator, a laminated structure of substrates in a cassette is used. An object of the present invention is to provide an annealing method for suppressing static electricity generated during storage and an annealing cassette used in the annealing method.

[0016]

According to a first aspect of the present invention, there is provided an annealing method in which a plurality of substrates are divided into cassettes, stacked, stored in a heating furnace, and heated. Alternatively, in a case where a conductor is formed on the substrate, an annealing method is characterized in that substrates to be laminated in the cassette are laminated with a predetermined number of laminated layers sandwiching a grounded conductor substrate.

According to the second aspect of the present invention,
The annealing method is characterized in that the conductor substrate is in contact with a conductor provided in the cassette.

According to the third aspect of the present invention,
In the annealing method in which a plurality of substrates are stacked in a cassette, housed in an activation furnace, and heated, in a case where the substrate is non-conductive, two or more substrates are divided and stacked and arranged as a group. And dividing the group into a plurality of groups and storing the divided groups in the cassette at intervals.

According to the means of the invention of claim 4,
The substrate is a group in which two or more substrates are stacked and arranged, and a group of the substrates is stored in the cassette at an interval equal to or more than the product of the stacking arrangement interval and the number of stacked substrates. Is an annealing method.

According to the fifth aspect of the present invention,
In an annealing apparatus including a heating furnace, and a cassette for partitioning, stacking, and storing a plurality of substrates to be heated in the heating furnace, the cassette is provided with a conductor at a predetermined location. Is an annealing apparatus.

According to the means of the invention of claim 6,
The annealing apparatus is characterized in that the conductor is connected to a conductor terminal provided in the heating furnace in the heating furnace.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of an annealing apparatus according to an embodiment of the present invention and a transfer system of an object to be processed constituting the apparatus.

The annealing apparatus has, for example, an activation furnace 1 as a heating furnace for performing an annealing process. In the activation furnace 1, a substrate 2 such as a semiconductor to be processed is placed in the activation furnace 1. A heat-resistant cassette 3 to be used when inserting the inside is used. It is needless to say that the present invention can be widely used for heat treatment such as crystallization treatment as well as activation treatment.

The heat-resistant cassette 3 is provided with a transfer robot 5 for transferring the substrates 2 between the transfer cassette 4 and the heat-resistant cassette 3 from the transfer cassette 4 as a process before and after the annealing process. ing.

Since the activation furnace 1 has a processing temperature of 500 ° C. or higher, the annealing furnace requires a time for raising and lowering the temperature in the activation furnace 1. Therefore, a batch method is used in which a plurality of substrates 2 to be processed are placed in a heat-resistant cassette 3 made of heat-resistant glass or quartz at a time and an annealing process is performed at a time.

Further, the substrates 2 which are the object of the present invention.
Is provided with an electronic element, an electric circuit, or a recording film (not shown) on the surface of the substrate 2..., And is not limited to its electrical properties. For example, silicon, GaAs
s or a substrate 2 made of glass or the like. Further, an electronic element or an electric circuit is an electronic element or an electric circuit in which a functional failure such as an interlayer short-circuit easily occurs in a laminated wiring portion due to static electricity, for example, a TFT (Thin Film Tr).
ansistor), MOSFET (MetalOxi)
de Semiconductor Field Em
ittionTransistor) or Diod
e Capacitor and the like.

The material of the conductive portion constituting the electric circuit and the like is, for example, Ta, Ti, W, Au, Pt, A
g, Cu or Al is used.

As shown in FIG. 1, the activation furnace 1 has a heater 7 along an inner wall of a furnace chamber 6 formed of a ceramic furnace material.
A quartz tube 8 for transmitting heat from the heater 7 to the inside of the furnace chamber 6 is provided inside the heater 7. A heat-resistant cassette guide 9 is provided at the center of the furnace chamber 6 in the space formed by the quartz tube 8. The heat-resistant cassette guide 9 is used for the heat-resistant cassette 3
Restrain the movement of at least the lower two corners in the short direction,
It has a structure that is movable in the longitudinal direction, and is provided from the side of the door 10 provided on one of the side walls of the activation furnace 1 to the other side wall.

As shown in FIG. 2, the heat-resistant cassette 3 is made of an insulating material having a high melting point, such as heat-resistant glass, quartz, or ceramic, in order to prevent the heat-resistant cassette 3 from being deformed when it is repeatedly heated and used in the activation furnace 1. , And has a rectangular frame structure in which the substrates 2... Are separated and held one by one, and is formed with external dimensions that movably engage with the heat-resistant cassette guide 9. Also, the divided sections 11a, 11
11n are provided with ground conductors 12, which will be described in detail in the embodiments described later, at predetermined locations.

The transfer robot 5 is a device for transferring the substrates 2... Stored in the transfer cassette 4 one by one to be stored in the heat-resistant cassette 3. That is, the substrates 2 stored in the transport cassette 4 are sucked and held by the fingers 15 provided at the tip of the arm 14, and the substrates 2.
Are stored one by one in a predetermined position of the heat-resistant cassette 3.

In this embodiment, the fingers 15 spatially support the substrates 2 so that the substrates 2 come into contact with objects other than the substrates 2 and have no electrical conduction. A conductive material such as SUS, Al, or Cu is used to perform the function and simultaneously neutralize the charge generated on the substrate 2.

In the present embodiment, the transfer cassette 4 is also a supporting member of the substrates 2 for holding the substrates 2 so as not to come into contact with objects other than the substrates 2. At the same time as having a function of spatially supporting the substrates 2..., The support members of the substrates 2.
It is formed of a conductive material such as S, Al, or Cu. Further, one end thereof is in a state of being in contact with a part of the conductive portion of the substrate 2... And the other end is in a state of being electrically grounded.

However, the above configuration is merely an example, and it suffices that the grounding conductor 12 is formed at a portion where the transport cassette 4 and the substrate 2 contact each other.

With these structures, the substrates 2... Stored in the transfer cassette 4 and transferred are transferred to the transfer robot 5.
The heat-resistant cassette 3 is sucked and transferred one by one
Is stored in. When the transfer to the heat-resistant cassette 3 is completed by repeating these operations, the heat-resistant cassette 3 is guided by the heat-resistant cassette guide 9 of the activation furnace 1 to be activated.
It is attached to a predetermined position in. Door 10 of activation furnace 1
Is closed, and an annealing process by heating for a predetermined time is performed. After a predetermined time has elapsed and the annealing process is completed, the opening and closing door 10 is opened and the heat-resistant cassette 3 is discharged to the outside of the activation furnace 1 along the heat-resistant cassette guide 9. The transfer robot 5 transfers the substrates 2 stored in the heat-resistant cassette 3 to the transport cassette 4 one by one. When the transfer is completed, the transfer cassette 4 is transferred to the next processing step. Hereinafter, a batch-type annealing process is performed by repeating the same operation. (Embodiment 1) As shown in FIG. 2, a substrate 2a laminated in a heat-resistant cassette 3 is subjected to an annealing process when the substrates 2a for manufacturing semiconductors are provided with a metal or a metal film.
a, a conductor substrate 20 for electrostatic shielding is inserted between the substrates 2a... so that the amount of charge does not increase due to electrostatic induction in the substrates 2a. The conductor substrate 20 is connected to a ground potential via a ground conductor 12 provided in the heat-resistant cassette 3 and a ground wire 21 provided in the active furnace 1. That is, the grounding of the conductor substrate 20 to the ground potential is performed in a state in which the conductor substrate 20 is inserted into a position where the ground conductor 12 is provided at each predetermined position of the heat-resistant cassette 3 and is in contact with the ground conductor 12. When inserted into the active furnace 1, the ground conductor 12 contacts and connects to a ground wiring terminal (not shown) provided in the active furnace 1. Since the ground wiring is connected to the ground wiring terminal, the conductor substrate 20 in contact with the ground conductor 12 is grounded.

The conductor substrate 20 and the ground conductor 12
Is not used as the transfer cassette 4 for the next step or the like, and does not cause any trouble even if it is used or repeatedly used in the annealing treatment in the activation furnace 1. When the conductor board 20 is greatly deformed, it is replaced.

Now, assuming that each of the conductive substrates 20 is charged with the same amount, the relationship between the installation interval of the conductive substrates 20 in the heat-resistant cassette 3 and the amount of charged charge is as shown in the graph of FIG. ∝1 / d (1) is determined by the installation interval and the number of substrates 2a for manufacturing semiconductors. That is, the size of the substrate 2a is 300 mm
× 360 mm and an initial charge of 66 (pC), the substrate 2
In order to set the distance d ₁ = 5 mm between the a .... and the charge amount Q to be 100 V or less as static electricity (potential), it can be achieved by inserting one conductive substrate 20 for every 30 substrates 2a. (Example 2) This is an annealing process in the case where the substrates 2b for manufacturing semiconductors are made of an insulator.

As shown in FIG. 4, the substrates 2b are stacked on the heat-resistant cassette 3, and the capacitance C with both ends sandwiched between the conductive substrates 20 (metal plates) is expressed by formula (2), and the potential V is expressed by formula (3). It becomes an expression.

C = 1 / (t ₁ · n ₁ / ε ₁ S + t ₂ · n ₂ / ε ₂ S) (2) V = Q / C (3) S: substrate 2 area, t ₁ : substrate 2... thickness
t ₂ : substrate 2... interval, n ₁ , n ₂ : substrate 2.
Number and number of gaps, Q: surface charge That is, the potential V is proportional to the distance between the stacked substrates 2b and the gaps.

The substrates 2b stacked in the heat-resistant cassette 3 are a part of the transfer robot 5 serving as charged electrodes shown in FIG. A potential is generated when approached. Discharge occurs due to this potential, and the circuit on the substrate 2b may be destroyed.

Therefore, the potential V can be suppressed by limiting the substrates 2b to be laminated and dividing them into blocks. As shown in the schematic diagram of FIG.
_If it is set to 3, it becomes possible by setting the relation of the expression (4) so as not to be affected by the adjacent blocks.

D ₃ > t ₁ · n ₁ (4) That is, the interval d ₃ for each block may be set to be larger than the thickness of the substrates 2 b housed in the block.

As described above, according to the present invention, for example,
Conductor and non-conductor substrates 2a... 2b.
Can be eliminated by inserting the conductor board 20 for electrostatic shielding in the conductor boards 2a... Without using an ionizer when arranging them in a stack.

When the substrates 2b are made of a nonconductive material, the charge can be reduced or the potential can be reduced by controlling the lamination interval.

Therefore, in any case, a clean environment is formed without being affected by the dust generated from the ionizer, and the electrostatic damage of the circuits manufactured on the substrates 2... 2 a. This can be reliably prevented, and a desired annealing process can be performed.

[0046]

According to the present invention, according to the batch type annealing process, the configuration of the arrangement for accommodating the substrates in the heat-resistant cassette is changed depending on whether the substrate to be processed is a metal or an insulator. As a result, an annealing method for reducing the amount of static electricity on the substrate and an annealing apparatus used for the method can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an annealing apparatus according to an embodiment of the present invention and a transfer system thereof.

FIG. 2 is a side view of the heat-resistant cassette.

FIG. 3 is a graph showing a relationship between an installation interval of a conductive substrate and a charge amount;

FIG. 4 is an explanatory diagram of a lamination arrangement of substrates on a heat-resistant cassette according to the embodiment of the present invention.

FIG. 5 is a schematic view showing that a laminated substrate is divided into blocks.

FIG. 6 is a schematic diagram showing a relationship between an annealing device and a cassette.

FIG. 7 is a perspective view of a heat-resistant cassette.

FIGS. 8A to 8D show an increase in the number of laminated substrates.
FIG. 4 is an explanatory diagram for explaining that a charge is applied to a substrate.

FIG. 9 is an explanatory view of grounding of the heat-resistant cassette.

FIG. 10 is a schematic diagram of static elimination using an ionizer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Activation furnace, 2 ... 2a ... 2b ... Substrate 3 ... Heat resistant cassette 4 ... Transport cassette 5 ... Transfer robot,
6 furnace chamber, 12 ground conductor, 20 conductor board, 21 ground wiring

Claims (6)

[Claims] 1. An annealing method in which a plurality of substrates are divided into a cassette, stacked, stored in a heating furnace, and heated, wherein the substrate is a conductor or the substrate has a conductor formed thereon. An annealing method comprising: laminating substrates to be laminated in a cassette with a predetermined number of laminated layers sandwiching a grounded conductor substrate. 2. The apparatus according to claim 1, wherein the conductor substrate is in contact with a conductor provided on the cassette.
The described annealing method. 3. An annealing method for laminating a plurality of substrates in a cassette, storing the substrates in an activation furnace, and heating the substrates, wherein when the substrates are non-conductive, two or more substrates are divided and laminated and arranged. An annealing method, wherein said group is divided into a plurality of groups, and said group is divided into a plurality of groups, and said plurality of groups are stored in said cassette at intervals. 4. A group in which two or more substrates are stacked and arranged as a group, and a group of the substrates is placed in the cassette at an interval equal to or more than the product of the stacking arrangement interval and the number of stacked substrates. 4. The annealing method according to claim 3, wherein the method is stored. 5. An annealing apparatus comprising: a heating furnace; and a cassette for partitioning, stacking, and storing a plurality of substrates to be heated in the heating furnace, wherein the cassette is provided at a predetermined position of the partition. An annealing apparatus comprising a conductor. 6. The annealing apparatus according to claim 5, wherein the conductor is connected to a conductor terminal provided in the heating furnace in the heating furnace.