JPS6253941B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an improved plasma reaction processing apparatus,
More specifically, it relates to an automatic precision low-temperature gas plasma reaction processing apparatus equipped with a single-wafer processing mechanism that automatically supplies wafers to be processed one by one to a plasma reaction chamber and automatically takes them out after plasma processing. It is.

Recent developments in the electronics industry have been remarkable, and significant progress has been made in processing technology for electronic component materials such as transistors, ICs, LSIs, and super LSIs. One such processing technology is the photoabsorption technology for semiconductor substrates. For example, in the case of etching, the conventional wet etching method using an etching solution is being replaced by a dry etching method using gas plasma. . Also, in wet etching for microfabrication, dry processing using plasma is applied as a pretreatment to improve wetting.

By the way, these plasma treatments require a gas plasma reaction device, but in all conventional devices, 10 to 25 wafers to be processed are placed side by side on a wafer stand and charged into a plasma reaction tube. It was a batch method in which after the pressure was reduced, plasma gas was introduced and a voltage was applied to generate plasma to perform etching.

However, in such a method, a large number of wafers are arranged over a considerable distance in the reaction tube and processed at one time, resulting in non-uniform action of the plasma gas, and in some cases, the wafers are separated by about 10%. This results in variations in etching. In order to prevent such variations, improvements in the shape of the reaction tube, improvements in the processing conditions, etc. have been proposed, but no complete improvements have been made and no satisfactory results have been obtained.

On the other hand, in conventional batch-type plasma equipment, the wafers to be processed are manually grabbed with tweezers from the wafer cassette sent from the previous process, arranged vertically on a wafer stand, loaded into a reaction tube, processed, and then loaded again. Normally, the wafers are manually transferred from the stand to a wafer cassette and then supplied to the subsequent process. However, this wafer cassette has the disadvantage that continuous operation cannot be achieved because all processes, including photoresist coating, baking, development, and rinsing, except plasma processing, are incorporated into an automated line, and only the plasma processing process relies on human labor. There is. Furthermore, since each wafer is gripped with tweezers, the wafer surface may be scratched or even cracked.Furthermore, as wafers become larger in the future, it will become difficult to grip them with tweezers.

In addition, a plasma apparatus is known in which a large number of wafers are arranged on a fixed wafer table, and a bell jar is raised and lowered to fit onto the wafer table to form a reaction chamber. However, this method requires space to line up a large number of wafers, which inevitably leads to an increase in size, and it also has the drawback that the processing conditions vary slightly for each wafer, resulting in variations in quality. Furthermore, since this method moves the bell jar up and down, the impact from the vertical movement causes dust attached to the inner wall of the bell jar to fall off, blocking the wafer surface to be processed and inhibiting etching, or preventing long-term use. During the process, problems such as etching reactions in the reaction chamber, damage to the bell gear material due to strain due to repeated vacuum operations, and shortening of the service life due to bending of the exhaust pipe connected to the bell gear may occur. have.

The inventors of the present invention have conducted intensive research to develop an automatic precision low temperature gas plasma reaction processing apparatus that solves the problems of conventional equipment. The inventors have discovered that this objective can be achieved by arranging vacuum preliminary chambers before and after the reaction chamber in the processing apparatus, and have completed the present invention based on this knowledge.

That is, the present invention provides an automated system that includes a plasma reaction chamber maintained in a vacuum state, a mechanism for feeding wafers to be processed into the plasma reaction chamber one by one, and a mechanism for taking out processed wafers one by one from the plasma reaction chamber. A plasma reaction processing apparatus characterized in that a vacuum preparatory chamber is arranged before and after the plasma reaction chamber, and the plasma reaction chamber and the vacuum preparatory chamber are each independently equipped with a vacuum evacuation mechanism. A processing device is provided.

The apparatus of the present invention equipped with such an automatic single wafer processing mechanism can be obtained, for example, as follows. That is, a wafer cassette containing wafers to be processed and a wafer cassette for receiving processed wafers are set upright at both ends of a tilted base that is lowered backwards, and a plasma display installed in the center of the tilted base is installed. Vacuum preparatory chambers are placed in front and behind the reaction chamber, and a hermetically sealed tube connecting the preparatory chambers in a straight line is provided. In the vacuum preliminary chamber, the wafer flowing down the sealed grate is temporarily accommodated and rotated.
Each rotary block is equipped with a rotary valve that also serves as a rotary valve to cause the wafer to flow downward after switching the internal and external pressures, and a mechanism for rotating the rotary block and the wafer table in the plasma reaction chamber is operated in conjunction with each other. Connect to a series of control mechanisms.

Next, one embodiment of the present invention will be explained with reference to the accompanying drawings. Fig. 1 is a longitudinal cross-sectional view of the apparatus of the present invention, and Fig. 2 is a perspective view of the rotating block installed in the vacuum preliminary chamber of the apparatus of the present invention. As shown in FIG. 1, an elevator 2 for raising and lowering unprocessed wafer cassettes is provided above one end of the box-shaped main body 1, and an elevator 3 for raising and lowering processed wafer cassettes is provided below the other end.
is provided, and the elevator 2 always carries the unprocessed wafer cassette 4 downward one frame (wafer retaining shelf 1).
The elevator 3 is designed to move the processed wafer cassettes 5 up one step at a time. A tilted base 6 is bridged between both elevators 2 and 3, and this tilted base 6 is provided with a dome-shaped plasma reaction chamber 7 in the center and box-shaped vacuum preliminary chambers 8 and 9 in front and behind it. are located in a straight line and connected by a sealed gage 10 large enough for the required wafer to pass through, and can be independently controlled to open and close with a vacuum pump (not shown) provided in the box-shaped main body 1. They are connected via an exhaust pipe 11. Inside the vacuum preparatory chambers 8 and 9, there are further short cylindrical rotating blocks 12 and 13 whose peripheral surfaces are in sliding contact with the circumferential surface of the vacuum preparatory chamber.
It is fitted airtight and also serves as a rotary valve, and is rotatably attached via shafts 14 and 15 protruding from the lower end. These rotating blocks 12,1
3 has a sealed hole 1 on a part of the circumference as shown in Figure 2.
One pocket-shaped wafer storage section 16, 1 has an opening that coincides with 0 and uses this opening as an entrance.
7 is provided. The wafer table 18 in the plasma reaction chamber 7 has a stopper claw 19 projecting from its upper surface and a shaft 20 projecting downward like the rotating block. These protruding shafts 14, 15, 20 are connected to rotation mechanisms 21, 23, 22, respectively.

The apparatus of the present invention is constructed as described above, and its operation will be explained. As the unprocessed wafer cassette 4 descends, the desired wafers placed on the feeder belt 24 are moved by the feeder belt 24. The inclined base 6 is then sent to the left in Fig. 1.
The front vacuum preliminary chamber 8
The wafer enters the wafer accommodating section 16 of the rotating block 12 inside and stops. Next, the rotating block 12 is rotated 90 degrees via the rotating mechanism 21. At this time, this rotary block acts as a rotary valve between the vacuum preparatory chamber 8 and the hermetic gutter 10, and the air in the front vacuum preparatory chamber 8 is removed via the exhaust pipe 11, creating a negative pressure equivalent to that of the plasma reaction chamber 7. Become. When the rotating block 12 is further rotated by 90 degrees in this state, the entrance of the wafer accommodating section 16 coincides with the entrance of the plasma reaction chamber 7, so that the wafer inside slides inside the groove 10 and moves into the plasma reaction chamber. 7 on the wafer table 18,
It comes into contact with the claw 19 and stops sliding.

In this state, a predetermined plasma gas is blown into the plasma reaction chamber 7 and an excitation voltage is applied to perform plasma processing.

When this plasma treatment is finished, the wafer table 18 is rotated 90 degrees, so that the wafer on the table is released from the claws 19 and slides into the groove 10, and the wafer on the rotating block 13 located in the rear vacuum prechamber 9 is moved. It slides into the accommodating part 17 and is supported. Then, the rotating block 13 is rotated by 90 degrees via the rotating mechanism 23, and communication between the wafer accommodating section 17 and the plasma reaction chamber 7 is blocked. Next, by rotating 90 degrees, the entrance of the wafer accommodating section 17 is opened to the processed wafer cassette 5 through the sealing hole 10.
The wafers are sequentially stored in the cassette 5.

In other words, the rotating mechanisms 21, 22, and 23 sequentially rotate each other by 90 degrees after a certain period of time without overlapping adjacent ones,
In addition, the elevators 2 and 3 move one frame at a time in response to this, and a control mechanism that operates in conjunction with each other in this way is a well-known program control used for automatic machining of machine tools, for example. For example, a large number of cams may be mounted on one shaft through a skewer, thereby making it possible to operate each part in a fixed order for a required period of time.

In the apparatus of the present invention, vacuum preparatory chambers are provided before and after the plasma reaction chamber, and each chamber is equipped with an independent evacuation mechanism, and each chamber is connected to a series of control mechanisms that evacuate the chambers in conjunction with each other. Since outside air is not directly communicated into the reaction chamber when wafers are supplied and discharged from the reaction chamber, the inside of the plasma reaction chamber is always kept in a constant vacuum state.
Therefore, it goes without saying that processing efficiency is greatly improved, and since atmospheric dust, nitrogen gas, moisture, etc. do not flow into the reaction chamber, and the state of the plasma gas remains unchanged, variations in reaction processing are reduced. Excellent results can be obtained without

For example, if this device is used without a vacuum pre-chamber, it will take approximately 20 to 40 seconds to create a satisfactory vacuum in the plasma reaction chamber; however, if this device is used without a vacuum pre-chamber, Using the invented device, approx.
A satisfactory vacuum condition can be achieved in 10 seconds.

In addition, if a vacuum preliminary chamber is not provided, the reaction chamber will take one breath each time one wafer is processed, and as a result, dust, nitrogen gas, moisture, etc. in the atmosphere will flow into the reaction chamber and cause various problems during plasma processing. adversely affect. In other words, if dust adheres to the wafer, it will cause incomplete etching, and for nitrogen gas, a method is widely used in which the end point of the reaction is detected from changes in the intensity of the emission spectrum in the plasma reaction chamber during plasma reaction processing. However, nitrogen gas disturbs the intensity change of the emission spectrum and causes damage, making it impossible to detect the end point of the reaction.Furthermore, regarding moisture, especially in anisotropic etching using plasma gas, chlorine-based gas is used as the reaction gas. If moisture is present in the reaction chamber, this chlorine-based gas will reduce its activity and cause a decrease in etching efficiency, causing harm.

Furthermore, the apparatus of the present invention can perform plasma reaction treatment continuously and automatically, and since the movable parts are small parts such as rotating blocks, it is structurally reasonable, and maintenance is easy. The entire device can be made compact, and it has many advantages, such as the ability to install several devices side by side in a small area, such as on an automated line for semiconductor manufacturing.

[Brief explanation of the drawing]

The drawing shows one example of the device of the present invention,
FIG. 1 is a longitudinal sectional view of the apparatus, and FIG. 2 is a perspective view of a rotating block installed in a vacuum preliminary chamber. In the figure, numerals 4 and 5 are wafer cassettes, 6 is a tilted base, 7 is a plasma reaction chamber, 8 and 9 are vacuum preparatory chambers, 10 is a seal, 12 and 13 are rotating blocks, 18 is a wafer table, and 21, 22,2
3 indicates a rotation mechanism.

Claims (1)

[Claims] 1. Vacuum plasma reaction chamber, front and rear vacuum preparatory chambers each communicating with the vacuum plasma reaction chamber through a sealed gutter, and a mechanism for supplying wafers to be processed one by one to the vacuum plasma reaction chamber via the front vacuum preparatory chamber. In a plasma reactor, which consists of a mechanism for sending processed wafers one by one from a vacuum plasma reaction chamber through a rear vacuum preliminary chamber, the front and rear vacuum preliminary chambers are each equipped with a vacuum exhaust mechanism independent of the vacuum plasma reaction chamber. It is formed into a short cylindrical case with an inlet and an outlet opening on opposite sides, and a wafer is temporarily received and received inside each case, and rotates while sliding on the inner wall of the cylinder to switch between internal and external pressures. A plasma reaction apparatus characterized by having a structure incorporating a short cylindrical rotary block that also serves as a rotary valve and has a storage chamber bored on the side surface for sending out a wafer.