INTRODUCTION

The MPS Series is a multi-function, multi-chamber plasma processing system for the deposition and etching of semi-conducting materials and devices. The concepts incorporated into this system are based upon proprietary designs for a distributed system. Principle features are as follows:

1. The system is load locked for both receiving and sending substrates. The load lock acts as the send and receive station, and is capable of serving an arbitrary number of process chambers. The system may be expandable by two or more load locks if required.

2. The process chambers are separate and capable of independent operation. Each process chamber is isolated by a slit valve and has independent electronics, gas pumping and gas handling lines.

3. The system utilizes a linear substrate handling device, contained in the vacuum, that is capable of transferring a substrate from any process/load-lock chamber to any other chamber, quickly and with minimal particulate contamination.

PROCESS CHAMBERS

Each of the process chambers is devoted to a particular mode of operation. The available modes are listed in the introduction. Chamber construction is available in stainless steel or aluminum. The aluminum chambers are constructed of type 6061-T6 alloy. They may be supplied anodized for an etch resistant finish. The stainless steel chambers are constructed of type 304 alloy.

The chambers utilize pre-baked elastomer O-rings for cover and base plate sealing. The ports on the stainless steel chambers are supplied with either metal sealed or elastomer O-ring sealed flanges, depending upon the customer's specifications.

The standard port configuration for the rectangular chambers consist of: one 3" view port, three 1.5" instrumentation ports, one 4" high vacuum pumping port, and one 6.5" x 1.25" port for access to the robot. Two of the 1.5" ports are in line of sight and a third 1.5" port is at a right angle to these two.

The instrumentation ports and the viewing ports are located at the plasma level for ease of viewing and optimal plasma diagnostics. Two 1.5" pumping ports and two 0.5" ports are located in the base plate. The 0.5" ports are for connection to gas handling devices and pressure sensing devices. All chamber designs are bakeable to 150 C.

PLASMA POWER SUPPLIES

Each chamber is equipped with a dedicated automatic matching network (AMN). The load lock chamber is equipped with an AMN if configured for process. All matching networks feature manual override. Standard power supplies are one 300 watt solid state 13.56 MHZ generator and one 0-750 volt DC power supply. The DC supply is used for cathodic biasing or DC glow discharge. Any power supply can be directed to any chamber. The 13.56 MHZ supply and the DC supply can be directed to the same chamber simultaneously.

LINEAR TRANSFER MECHANISM

The Substrate Transfer Mechanism features:

1. Compound motion.
2. Minimal particulate generation.
3. Precision placement.
4. Ease of use.

The transfer mechanism allows a 36" reach. A viewport for inspection is centrally located in each chamber for convenient viewing. The mechanism contains no rubbing surfaces. All motion is supported by precision bearings. The motion which moves the substrate mechanism is transmitted into the central chamber through two separate shafts.

The substrate transfer mechanism is designed to handle and place substrates into the deposition chambers in the non-inverted deposition mode. Substrate deposition in the inverted mode is available as an option. The loading, unloading and choice of chambers is selected by the operator. The transfer mechanism is designed to accurately and reproducibly locate 6" round (or smaller) substrates within each process chamber. Each process chamber is separated from the central chamber by a rectangular gate valve. The process chambers have separate gas pumping lines, flow lines, and individual matching networks for independent operation. The plasma generation in each process chamber is accomplished by parallel plate capacitance. The substrates, which can weigh up to 250 grams, are processed on the upper and lower electrodes, as specified.

The "robot arm" performs two functions. The robot can position the substrate in the appropriate process/loadlock chamber and both extends and retracts to load or unload the substrate into the designated chamber.

GENERAL OPTIONS:

A wide variety of options are available. A common substitution is aluminum chamber construction for stainless steel. An external loadlock is available which allows all of the chambers to be used for processing. Inverted substrate processing is available. A popular addition has been the inclusion of a 25-125 Khz low frequency generator. Special chamber designs, pumping systems and instrumentation can be accommodated upon request.

GAS HANDLING SYSTEM:

All chambers have identical gas handling features and they all use downstream pressure control. Located between the chambers and the Blowers are 1-1/2" throttle valves. These valves maintain pressure by comparing the chamber pressure to a user selected setpoint pressure. The throttle valve adjusts its conductance until the two pressure set points are equal. Chamber pressure is monitored with a 0-10 torr capacitance manometer (or other range). All gas handling lines are type 316L stainless steel seamless tubing. The tubing is cleaned and micro-polished prior to assembly. All fabricated parts are welded. Reusable connections are made with metal gasket fittings. The gases flowing into the process chamber are controlled with electronic mass flow controllers. The number of MFC's is to be determined by the users requirements.

VARIABLE ELECTRODE SPACING:

The grounded counter-electrode can be adjusted from ½" to 3". Adjustment is conducted externally from outside of the vacuum system, even while the system is operating.

COMPUTER INTERFACING:

The MPS Series Systems are supplied computer interface ready. All electro-pneumatic valves can be controlled from either the instrument control panel or by 0-5 volt TTL logic level. The method of control is determined by the system operator via a front panel switch labeled manual/auto.

The mass flow controllers, RF generators, throttle valves and platen heaters can all be controlled with either 0-10 volt or 0-5 volt analog signals.

The mass flows, chamber pressures, ion gauge pressures, deposition platen temperatures and thermocouple gauge set points can all be monitored by computer or data logger while the system is under manual or automatic control.

A complete menu driven computer system can be factory installed. The basic system includes a monitor, disk drive, printer and the necessary RAM memory for the application. A card cage is supplied which connects to the computer by a GPIO interface. Included are: a digital to analog converter (DAC), an analog to digital converter (ADC), BCD conversion, event sense, TTL output and TTL input. Options available are stepper motor control and communication protocols such as IEEE-488.

VACUUM SYSTEM:

The process chambers are rough pumped through 1-1/2" pumping lines by an 6.8 CFM mechanical pump. Optional 104 CFM Roots Blowers, backed by mechanical pumps, are connected to the system with 1-1/2" pumping lines.

The pumps can be charged with Fomblin oil for use with corrosive gases. All pumps in the system are corrosion resistant and the mechanical pumps can have oil filtration systems. Roots Blowers may be connected to any process chamber or combination of process chambers as desired.

High vacuum pump down of process chambers is accomplished with a 140 liter/sec. Turbo-molecular pump backed by an 6.8 CFM mechanical pump. The turbo-molecular pump is connected to the process chamber by 4" pumping lines. The turbo pump can also be used to pump process gases at pressures below 100 millitorr.

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