JPS61573A - Sputtering apparatus - Google Patents

Abstract

PURPOSE:To make the regulation of gas pressure of an ionized gas ease and to perform excellent filming by providing the first exhaust path having a turbo- pump and the second exhaust path having a cryopump to a sputtering chamber. CONSTITUTION:An exhaust duct 7 is fitted to a sputtering chamber 1 provided with a target 2, a base plate holder 3 and an introduction port 4 for sputtering gas such as argon via a gate valve 6. An exhaust duct 7 is provided with a turbopump 10 having an exhaust line 15 and a cryopump 14 having an exhaust line 16. The exhaust lines 15, 16 are connected with a rotary pump 17. The exhaust of whole period of the chamber 1 is performed by means of the exhaust system contg. the turbopump 10 plus the rotary pump and the pressure of the inside of the chamber 1 is regulated to prescribed pressure by the regulation of a variable valve 12 in the exhaust system contg. the cryopump 14 and the rotary pump. The pressure of the inside of the chamber 1 can be easily regulated to the prescribed pressure and the characteristics of a film and film quality due to the sputtering can be uniformly maintained always.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sputtering apparatus, and particularly to improvements in its exhaust system.

[Prior art and its problems]

Sputtering involves introducing an ionizing gas into a sputtering chamber, ionizing it, bombarding a target made of the material to be deposited with the ionized gas, sputtering molecules or atoms of the material, and sputtering the molecules or atoms of the material onto the substrate. This is a film formation method that consists of depositing the film on the surface. The introduced gas pressure is the film forming material,
It is necessary to adjust according to the type of introduced gas, etc.

In conventional sputtering apparatuses, the capacity of the exhaust system is fixed, so the pressure during sputtering is adjusted by changing the flow rate or pressure of the sputtering gas. However, in this method, the direction of gas flow is disturbed in the intermediate flow region (10'' to 10-'Torr) at the nosputter gas pressure, making it impossible to improve the film quality. Another method is to insert a variable orifice into the exhaust system to adjust the exhaust capacity, but this method also basically limits the range of variation in capacity.
A similar problem occurred where the pressure or flow rate of the introduced gas had to be changed. Spatter is usually 10-! ~10"-'
The process is performed at a gas pressure in the Torr range, but if the pressure is adjusted to the desired gas pressure within this range, in the conventional method, the flow pattern changes as described above, and gas stagnation points occur. This caused problems with the properties and uniformity of the film.

[Purpose of the invention]

An object of the present invention is to provide a sputtering apparatus that can uniformly adjust the gas pressure for forming ionized gas and can perform excellent film formation.

[Summary of structure and effects of the invention]

The present invention provides a first exhaust system having a turbo pump for a sputtering chamber having a gas inlet for forming ionized gas.
A sputtering device characterized in that an exhaust path and a second exhaust path having a cryopump are formed in parallel and each is provided with a variable orifice so that the sputtering gas pressure can be adjusted without changing the ratio between the constant flow rate of introduced gas and the residual gas. It is a device.

4 According to the present invention, sufficient exhaust capacity is obtained even for the intermediate flow region, and by using both of these exhaust channels during sputtering operation, the pressure during sputtering can be controlled by the exhaust system while extending the life of the cryopump. It can be adjusted by Therefore, the pressure can be adjusted without changing the gas flow direction or causing stagnation caused by fluctuations in the pressure or flow rate of the introduced gas, improving the quality and uniformity of the film distribution of the sputtered film produced. I can do it.

[Configuration of Example]

FIG. 1 shows a sputtering apparatus according to an embodiment of the invention. The sputtering device can be any type of device, such as a bipolar or multipolar DC or RF sputtering device. The airtight sputtering chamber 1 is of a predetermined type, with reference numeral 2 a target and 3 a substrate holder. is connected to a gas source (not shown) via a valve 5.

An exhaust duct 1 is connected to the exhaust port of the sputter chamber 1 via a gate valve 6, and a cold trap (liquefied Nt or the like) 8 is disposed within the duct 7 as required. The cold trap 8 is mainly used to prevent backflow, and also has a certain degree of exhaust ability. The exhaust side of the exhaust duct 7 is divided into two parts, one of which is connected to a turbo pump 10 via a gate pulp 9 and a variable orifice 11, and the other to a cryopump 14 via a variable orifice 12 and a gate valve 15. has been done. turbo pump 10
is connected via line 15 to the output terminal pump 17,
Further, the cryopump 14 is connected to a rotary pump 17 via a line 16.

Turbo pump 10, line 15 and rotary pump 17
The exhaust system including the exhaust system is in charge of exhausting the chamber 1 during the entire period.

The cryopump 14 is used during sputtering operations in the intermediate flow region by achieving high vacuum and introducing sputtering gas. To give an example of the capacity of a turbo pump and a cryopump, if the volume of the chamber 1 is 800 cm'', pumps having capacities of 5 toz/min and 2600 t/sec, respectively, can be used.

[Operations and effects]

After the sputter chamber 1 is sufficiently evacuated, the valve 5 is opened to introduce a constant flow of argon gas.

Two exhaust systems are used together. The system including the turbo pump 10 sets the pressure in the chamber 1 in the intermediate flow region to approximately a predetermined value. A system including the cryopump 14 adjusts the pressure within the chamber 1 by adjusting the variable pulp 12 to establish a predetermined sputtering pressure. The variable orifice 11 in front of the turbo pump 10 is adjusted to achieve more precise pressure regulation.

A significant effect of the present invention is that a predetermined pressure within the chamber 1 can be achieved simply by adjusting the exhaust system, particularly the cryopump 14, without changing the flow rate or pressure of the introduced gas.

Since the flow rate of the introduced gas is constant, changing the exhaust capacity will change the flow rate and pressure of the sputtering gas.As a result, the flow pattern of the sputtering gas will not substantially change, and the flow rate of the film formed by sputtering will change. The properties and film quality become uniform. In addition, since the Lyopump is first operated on the high vacuum side, its evacuation ability can be maintained for a long period of time. Furthermore, according to the present invention, the range in which the gas pressure can be adjusted is wider than in the past, making it easier to control sputtering conditions.

On the other hand, when using a sputtering system equipped with an exhaust system that includes a variable orifice and a turbo pump, or a variable orifice and a cryopump, the exhaust capacity is changed by changing the variable orifice for a constant flow rate of introduced gas. Therefore, the ratio of the introduced gas partial pressure to the residual gas partial pressure changes and cannot be ignored, causing a change in the film composition. If the amount of input gas is changed to avoid such changes, the flow pattern within the chamber will change and the film quality will also change. The device of the present invention does not have this problem, and the pressure can be adjusted only by changing the variable orifice on the cryopump side without changing the pumping capacity of the basic pumping system, that is, the turbo pump system, so that sufficient pumping can be achieved. There is plenty of capacity, and the ratio of the residual gas partial pressure to the introduced gas partial pressure changes only by the variable orifice amount, so that it can be ignored.

For example, when the partial pressure of water was measured, the results shown in FIGS. 2 and 3 were obtained for the conventional exhaust system and the exhaust system of the present invention, respectively, indicating a large difference.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the sputtering apparatus of the present invention, FIG. 2 is a graph showing the exhaust characteristics of the conventional sputtering apparatus, and FIG. 3 is a graph showing the exhaust characteristics of the sputtering apparatus of the present invention. 1 Varnish Bubble Chamber 2: Target 3: Substrate holder 4: Gas inlet 6.9.16; Gate valve 7: Exhaust duct 10: Turbo pump 11: Variable orifice 12: Movable valve 14: Cryopump 17: Rotary pump\ −shi−〆

Claims (1)

[Scope of Claims] 1. A sputtering apparatus having a sputtering chamber having a gas inlet for forming ionized gas at a constant flow rate, and an exhaust system for evacuating the chamber, wherein the exhaust system includes a first exhaust having a turbo pump. What is claimed is: 1. A sputtering apparatus comprising a second exhaust path having a cryopump and a second exhaust path having a cryopump in parallel. 2. The sputtering apparatus 3 according to the above item 1, in which the gas pressure can be adjusted by changing the number of ionized gases without changing the flow path of the ionized gas, the ratio of the ionized gas pressure to the residual (released) gas being kept constant. 2. The sputtering apparatus according to claim 1, having an exhaust system that changes the pressure.