JPS6383259A - Sputtering device - Google Patents

Abstract

PURPOSE:To control a vapor deposited film thickness to a set value with high reliability in a sputtering operation by measuring the vapor deposited film, comparing the same with a preset film thickness and changing sputtering conditions according to the result thereof. CONSTITUTION:The thin film of a target 11 material by the ionization of the gaseous Ar introduced from a pipe 22 is deposited by evaporation on a semiconductor wafer 8 in a treatment chamber 5, the inside of which is evacuated to a vacuum by a vacuum pump 34. The semiconductor wafer 8 is carried to a film thickness gage 30, by which the film thickness is measured. The measured value is inputted to a film thickness controller 31. Since the prescribed film thickness value is set in the controller 31 by a film thickness set value inputting device 32, the value is compared with the set value. The time for the sputtering treatment, the electric power to be supplied to the target 11, etc., are automatically controlled by the difference between the measured value and set value of the film thickness, by which the film thickness by sputtering on the wafer 8 is exactly controlled to the set film thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial Application Field> The present invention relates to a sputtering apparatus, and particularly to a sputtering apparatus equipped with a film thickness control mechanism.

(Prior art) In recent years, Targetera! has been used as a thin film forming device for ultra-LSI structures by sputtering a target with high-energy particles such as ion particles.・Sputtering equipment is widely used to form a thin film by attaching particles ejected from a substrate to a substrate, such as a semiconductor wafer.

In such sputtering equipment, as the amount of sputtering increases, the target wears out.
~ Film to sputter quality (=1 mass ratio) There is a problem that the so-called film formation efficiency decreases and it becomes impossible to obtain the film I sensitivity at the initial stage of the work.To solve this problem, the sputter link equipment usually uses the following methods: A film thickness control mechanism is provided which monitors the film thickness value and controls the amount of the film 17 by adjusting sputtering conditions such as the amount of power supplied to the targets 1 and the sputtering processing time.

By the way, the film thickness measurement method in the conventional film thickness control mechanism is as follows:
A so-called indirect measurement in which a film thickness detection sensor such as a crystal oscillator is installed in a sputtering reaction tank, and the film Jf value of a thin film formed on a substrate is estimated from the film thickness value of the thin film attached to this film thickness detection sensor. It was done by method.

(Problem to be solved by the invention) However, in the sputtering reaction tank, many devices such as sputtering electrodes, substrate holding devices, and substrate transporting devices are arranged in a haphazard manner, making it difficult to measure accurate film thickness values. It is difficult to install a film thickness detection sensor in a location where it is possible, especially in magnetron sputtering equipment that generates a magnetic field near the target and confines gas plasma within this magnetic field to perform sputtering. It is difficult to install the film thickness detection sensor in a position where accurate film thickness can be measured, for example near the object to be processed, because the gap between the film thickness and the film thickness is narrow, and the method of measuring the film thickness value is an indirect method. Therefore, there was a problem in that highly accurate film thickness measurement could not be performed. To solve this problem, calculate the film 1γ value from the integrated value of the amount of power supplied to the target and the time of power supply, that is, the integrated power value.W! Thickness control is also being considered, but since it is not a means to actually measure the film thickness of the processed substrate, it may be difficult to control the thickness if the sputtering conditions, such as the voltage or current value of the power supply, change during the sputtering process. There was a problem that the calculated film thickness value and the actual film thickness value did not match.

In addition, as a method of directly measuring the thin film formed on the substrate, a worker samples the sputtered substrate every certain number of substrates and measures the film thickness, and from this film thickness measurement value, the power supplied to Targtsu 1 ~ Although methods are being used to artificially adjust the amount and power supply time, there is a risk that the timing of board sampling may be off, resulting in defective products.
There is a problem in that highly accurate film thickness control cannot be achieved due to the artificial adjustment of sputter link conditions, and furthermore, this has been a major obstacle in fully automating the work.

As described above, with conventional film thickness control mechanisms, it is extremely difficult to perform highly accurate film thickness control because film thickness values cannot be determined accurately and sputtering conditions must be adjusted artificially. there were.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a sputtering apparatus that can improve the precision of film thickness control and can easily handle complete automation of sputtering operations.

[Structure of the Invention] (Means for Solving the Problems) The sputtering apparatus of the present invention includes a sputtering means for sputtering a target and depositing particles flying from the target on a substrate to form a thin film, and this sputtering means. a film thickness measuring means for measuring the film thickness of the substrate sputtered by the method; a comparing means for comparing the measured value of the film thickness measuring means with a preset reference film thickness value; The apparatus is characterized in that it includes a control means for controlling sputtering conditions of the sputtering means in accordance with the output.

(Function) In the present invention, a desired film thickness value is set in advance, the film thickness formed on the substrate is constantly or periodically measured using a film thickness meter, and this measured value is compared with the above-mentioned film thickness setting value. By automatically changing the sputtering conditions and controlling the film thickness based on the comparison results, highly reliable film thickness control can be achieved, and the sputtering operation can be fully automated.

(Example) An example in which the present invention is not applied to a magnetron sputtering apparatus will be described below.

Inside the cylindrical reaction tank 1 which maintains airtightness, there are cylindrical wafer processing chambers such as a wafer insertion/removal chamber 2, an etching processing chamber 3, a wafer heating chamber 4, a first sputter processing chamber 5, and a second sputter processing chamber. The processing chambers 6 are arranged in parallel in the order of semiconductor wafer processing steps. Then, the semiconductor wafer is inserted into the reaction tank 1 from the wafer insertion/removal chamber 2 by a transport device (not shown), and is sequentially sent between the processing chambers and subjected to a predetermined process. sequentially takes out the semiconductor wafers that have been processed and inserts new semiconductor wafers.

A more specific configuration of the sputtering chamber will be described with reference to FIG. 2.゛In the sputtering chamber 5, a sputtering electrode section 7 is provided parallel to the inner wall surface of the reaction chamber 1, and this sputtering electrode section 7
A semiconductor wafer 8 is placed opposite to.

A cylindrical partition wall 9 extends from the inner wall surface of the reaction tank 1 on the back side of the sputter electrode part 7 so as to cover the sputter electrode part 7 in the side direction, and the front edge of the partition wall 9 and the inner wall of the reaction tank 1 are connected to each other. A gap 10 is provided between them so that the atmospheric gas in the reaction tank 1 can flow between the respective processing chambers.

The sputter electrode section 7 includes a target 11 having an inverted conical ring-shaped sputtering surface connected to a power supply 33, a disc-shaped one pole such as an N magnetic pole 12 disposed at the center of the target 11, and the target 11. For example, an S magnetic pole 13 is attached to the front edge of the partition wall 9 so as to surround the outer periphery of the target 11. do. This arc-shaped magnetic field A acts to temporarily confine generated plasma particles, which will be described later.

A disk-shaped shutter 15 is provided at the front edge of the partition wall 9 with a slight gap therebetween and is opened and closed by a drive mechanism 14 to open and close the partition opening.

In the gap 10 between the front edge of the partition wall 9 and the inner wall surface of the reaction chamber 1, there are provided one rotatable disk-shaped transfer plate that holds the semiconductor wafer 8 with a clip 18 in the wafer fixing hole 17, and one Herans force plate. Close contact @ side, located on the bulkhead 9 side of 19 and omitted from illustration, I/Lanfer play 1
・Disc-shaped pressure play 1 to 20 that presses 19
are provided parallel to the inner wall of the reaction tank 1, respectively. These one transfer plate, the pressure plate 20, and the inner wall surface of the reaction chamber 1 are each attached 4-1 so that they can be separated from each other, so that when the semiconductor wafer 8 is transferred to another processing chamber, for example, the second sputter processing chamber 6, , the pressure plate 20 is moved back to the partition wall 9 side, and one transfer plate is made rotatable. Note that the illustrated state shows that the sputtering process is in progress, and shows a state in which the transfer plate 19 is pressed by the pressure plate 20 and its movement is restricted.

A heater block 21 for preheating the wafer is arranged on the back surface of the semiconductor wafer 8, and a sputtering gas introduction pipe 22 is provided passing through the heater block 21. The sputtering gas generated by the reaction gas generator 35 flows through the gas introduction pipe 22 and flows into the reaction chamber 1 through an outlet 22 a provided on the outer periphery of the back surface of the semiconductor wafer 8 .

Reaction Jf! 1 Externally, there is a film thickness meter 3 for measuring the thickness of the thin film formed on the semiconductor wafer 8 and outputting a film thickness value signal.
0 is provided, and the film thickness value signal output from this film thickness meter 30 is input to the film thickness control device 31.

The film thickness control bag W 31 compares the film thickness signal with the signal inputted from the film thickness setting value input bag W 32 for setting a desired film thickness value in advance, and determines the sputtering conditions, such as the sputtering time and the target. This is a device for controlling the amount of power supplied to the target, and in this example, controls the power supply 33 to increase or decrease the amount of power supplied to the target. Further, the magnetic field may be controlled as necessary. These film thickness gauges are 30
, a film thickness control device 31, and a film thickness setting value input device 32 constitute a film thickness control system.

The sputtering operation of such a sputtering apparatus is performed by first transporting the semiconductor wafer 8 into the sputtering chamber 5, and then vacuuming the inside of the reaction chamber 1 with a vacuum pump 23 to a high vacuum, e.g.
Torr, and a high-temperature sputtering gas, such as argon gas, is introduced from the gas introduction pipe 22. At this time, the heat of the sputtering gas is transferred to the semiconductor wafer 8 through the heater block 21 and heats it. Next, the power supply 3 is supplied at an appropriate timing according to a predetermined program.
3, electric power is applied to the target 11 to turn the sputtering gas introduced into the reaction chamber 1 into plasma near the target 11. The sputtering gas turned into plasma is temporarily confined in a donut shape near the sputtering surface of the target 11 as shown by B in the figure due to the magnetic field A generated near the target 11, and the plasma particles excited at this time collide with the target particles 1 to 11. without ejecting flying particles a. When the shutter 15 rotates and opens, the flying particles a are scattered into the sputtering chamber, and some of these flying particles adhere and deposit on the semiconductor wafer 8 to form a thin film.

The semiconductor wafer that has undergone the sputtering process in this manner is transferred to the film thickness gauge 30, where the film thickness value that is used as a control parameter when controlling the film thickness is measured.

The operation of the film thickness control system of this example will be described below with reference to flowcharts 1 to 3 in FIG.

First, a semiconductor wafer that has been subjected to sputtering is taken out of the wafer insertion/removal chamber 2 to the outside of the reaction chamber 1 and transported to a film thickness meter 30 by a transport device (not shown) to measure the thickness of the thin film formed on the semiconductor wafer. Do (100).

The film thickness measurement value measured by the film thickness meter 30 is outputted to the film thickness control device 31 as a film thickness measurement value signal.

The film thickness control device 31 compares the film thickness setting value input in advance from the film 1γ setting value input device 32 with the film thickness measurement value (101), and calculates the film thickness setting value and g! If the measured film thickness values are equal, it is determined that the film forming operation is being performed normally and the current sputtering operation is continued102); if the measured film thickness value is different from the film thickness setting value, both film forming operations are performed. The difference in the thickness value is converted into a correction layer for the amount of power supplied to the targeters 1 and 11, and this information is output as a correction signal for the amount of power supplied to the power supply 33 (103).
. The power supply 33 receives the power supply correction signal and increases or decreases the power supply amount to the target 11. For example, if the measured film thickness value is smaller than the film thickness setting value, the power supply amount is increased (10/l). . Note that all of the above operations are performed automatically.

In this way, by automatically measuring the film thickness value of semiconductor wafers that have undergone sputtering and performing film thickness control, it is possible to improve the accuracy of film thickness control, and moreover, it is easy to fully automate the work process. can do.

In the above embodiment, the film thickness was controlled for each sputtering process, but the film thickness may be controlled by periodically sampling the semiconductor wafer and measuring the film thickness value. In addition, in sputtering operations using such sputtering equipment, a large number of semiconductor wafers are often processed continuously in wafer cassette units, and in such cases, one
From the viewpoint of managing each wafer cassette, it is convenient to calculate the average film thickness value of the semiconductor wafer for the force set and compare this average film thickness value with the film thickness setting value.

Below, as another embodiment of the present invention, a means for calculating the average film thickness value of a semiconductor wafer for one force set and comparing the average film thickness value with a film thickness setting value to perform film thickness control will be described.

As shown in FIG. 4, the film thickness measurement values of each semiconductor wafer input to the film thickness control device 31 are temporarily stored, and when all the semiconductor wafers in the first cassette have been processed, Calculate the average film thickness measurement (101a
). Next, compare the average film thickness measurement value and the film thickness setting value.
1) If these two values are different, a supplied power amount correction signal is output (103).

At this time, the average film thickness measurement value for the first cassette is set as Xl,
If the preset film thickness setting value is S, the amount of power supplied to the target from the power supply is P, and the amount of power supplied after the first correction is Pl, then the amount of power supplied from the first cassette 1 to the end is P1.
can be expressed by the following formula.

P+=Px s Similarly, the supplied power fP2 at the end of the second cassette is P2-
Px S ′X S
is S S Po =Pa XX033.1. ×Sx,
Expressed as X2 Xn. Therefore, the total amount of correction of the final power supply amount is S XX, 01.1. ×S x, x2 x mouth.

In the above embodiment, the film thickness was controlled by the amount of power supplied to the target 11, but the present invention is not limited to this. For example, the sputtering time may be controlled as shown in FIG. . That is, the difference between the film thickness measurement value input to the film thickness control device 31 and the film thickness setting value is converted into a correction amount for the sputtering processing time, and this is output (105). The power supply 33 receives the sputtering processing time correction signal and increases or decreases the power supply time to the turquoise 1 (106).

As described above, the present invention can be applied to any control of elements related to sputtering conditions. The MW meter used in the present invention may be of any type, such as a thin current type or a four-point probe type, and is not particularly limited to the model.

By integrating these film thickness values, it is also possible to know the lifespan of the target.

Further, by storing a preset film thickness value corresponding to each continuous or intermittent time period at the start of sputtering, and setting deviation, complete control of the intermediate layer can be performed automatically.

[Effects of the Invention] As explained above, according to the sputtering apparatus of the present invention, the accuracy of film thickness control can be improved, and moreover, it becomes possible to easily support complete automation of sputtering operations.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the arrangement of a wafer processing chamber of a magnetron sputtering apparatus to which the present invention is applied, and FIG.
3 is a flowchart showing the operation of the film thickness control device of the embodiment shown in FIG. 1; FIG. 4 is a flowchart showing the operation of the film thickness control device of the second embodiment; FIG. 5 is a flowchart 1 to 1 showing the operation of the film thickness control device of the third embodiment. 1... Reaction tank, 5... Sputtering chamber, 7... Sputtering electrode, 8... Semiconductor wafer, 11... Old target, 30... ...Film thickness meter, 31...Film thickness control device, 32...Film thickness setting value Kugata device, 33.Old...Power supply, 34...
・Vacuum pump, 35. Old...Reaction gas generator. Applicant Tokyo Electron Co., Ltd. Agent Patent Attorney Sasu Suyama - Figure 1

Claims (3)

[Claims] (1) A sputtering means for sputtering a target and depositing particles flying from the target onto a substrate to form a thin film; a film thickness measuring means for measuring the thickness of the substrate sputtered by the sputtering means; It is characterized by comprising a comparison means for comparing the measured value of the measurement means and a preset reference film thickness value, and a control means for controlling the sputtering conditions of the sputtering means according to the output of the comparison means. Sputtering equipment. (2) The sputtering apparatus according to claim 1, wherein the sputtering condition controlled by the film thickness control means is the amount of power supplied to the target. (3) The sputtering apparatus according to claim 1, wherein the sputtering condition controlled by the film thickness control means is a sputtering time.