# US 2018/0025930 A1 · Control of wafer bow in multiple stations

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- Number: US 2018/0025930 A1
- Document ID: US20180025930A1
- Status: Published application
- Kind: A1
- Application number: 15/640,053
- Filed: 2017-06-30
- Published: 2018-01-25
- Earliest claimed: 2016-07-25
- Assignees: Lam Research Corporation
- Applicants: Lam Research Corporation
- Inventors: Edward Augustyniak; David French; Sunil Kapoor; Yukinori Sakiyama; George Thomas
- Web page: https://patentgrep.com/patent/US20180025930A1

## CPC

- H10P 72/0616: {Monitoring of warpages, curvatures, damages, defects or the like}
- H01J 37/32183: {Matching circuits}
- H01J 37/32385: {Treating the edge of the workpieces}
- H01J 37/32577: {Electrical connecting means}
- H01J 37/32715: {Workpiece holder}
- H01J 37/32935: {Monitoring and controlling tubes by information coming from the object and/or discharge}
- H10P 72/0421: {for drying etching}
- H10P 72/0454: {surrounding a central transfer chamber}
- H10P 72/0466: {characterised by the construction of the load-lock chamber}
- H10P 72/0468: {comprising a chamber adapted to a particular process}
- H10P 72/0604: {Process monitoring, e.g. flow or thickness monitoring}
- H10P 72/0606: {Position monitoring, e.g. misposition detection or presence detection}
- H10P 72/7621: {characterised by supporting two or more semiconductor substrates}
- H01J 2237/3321: CVD [Chemical Vapor Deposition]
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A system for controlling of wafer bow in plasma processing stations is described. The system includes a circuit that provides a low frequency RF signal and another circuit that provides a high frequency RF signal. The system includes an output circuit and the stations. The output circuit combines the low frequency RF signal and the high frequency RF signal to generate a plurality of combined RF signals for the stations. Amount of low frequency power delivered to one of the stations depends on wafer bow, such as non-flatness of a wafer. A bowed wafer decreases low frequency power delivered to the station in a multi-station chamber with a common RF source. A shunt inductor is coupled in parallel to each of the stations to increase an amount of current to the station with a bowed wafer. Hence, station power becomes less sensitive to wafer bow to minimize wafer bowing.

## Claims

### Claim 1

A power distributor for delivering power to a plurality of plasma processing stations associated with a chamber, comprising:
a low frequency circuit coupled to a low frequency impedance matching network and configured to provide a low frequency RF signal;
a high frequency circuit coupled to a high frequency impedance matching network and configured to provide a high frequency RF signal, wherein the high frequency circuit is coupled to the low frequency circuit;
an output circuit coupled to the high frequency circuit and a plurality of plasma processing stations, wherein the output circuit is configured to combine the low frequency RF signal and the high frequency RF signal to generate a plurality of combined RF signals to provide to the plasma processing stations; and
a shunt inductor coupled in parallel to one of the plasma processing stations to increase an amount of current to the one of the plasma processing stations.

### Claim 2 (depends on 1)

The power distributor of claim 1, wherein the shunt inductor has two ends, wherein one of the ends is coupled to a ground connection and another one of the ends is coupled to the one of the plasma processing stations.

### Claim 3 (depends on 2)

The power distributor of claim 2, wherein the shunt inductor is coupled between an input of the low frequency circuit and an end of a coaxial cable that couples an output of the low frequency circuit to the one of the plasma processing stations.

### Claim 4 (depends on 1)

The power distributor of claim 1, wherein the shunt inductor is coupled at a point between the low frequency circuit and the one of the plasma processing stations.

### Claim 5 (depends on 1)

The power distributor of claim 1, wherein the shunt inductor is coupled at a point between an input of the low frequency circuit and a direct current (DC) blocking capacitor of the low frequency circuit.

### Claim 6 (depends on 1)

The power distributor of claim 1, wherein the shunt inductor is coupled at a point between a direct current (DC) blocking capacitor of the low frequency circuit and an inductor of the low frequency circuit.

### Claim 7 (depends on 1)

The power distributor of claim 1, wherein the shunt inductor is coupled to a ground connection at one end and to a high frequency blocking circuit at an opposite end, wherein the shunt inductor is coupled in parallel to a first capacitor, wherein the high frequency blocking circuit includes an inductor in parallel with a second capacitor, wherein the shunt inductor is coupled via a switch to a balancing inductor of the low frequency circuit.

### Claim 8 (depends on 7)

The power distributor of claim 7, wherein the first capacitor is coupled to the ground connection at one end and to the high frequency blocking circuit at an opposite end.

### Claim 9 (depends on 1)

The power distributor of claim 1, wherein the shunt inductor is a variable or a fixed inductor.

### Claim 10

A system for delivering power to a plurality of plasma processing stations, comprising:
a first radio frequency (RF) generator configured to generate a first RF signal having a first frequency;
a second RF generator configured to generate a second RF signal having a second frequency;
a first matching network coupled to the first RF generator to receive the first RF signal, wherein the first impedance matching network is configured to output a first modified RF signal upon receiving the first RF signal from the first RF generator;
a second matching network coupled to the second RF generator to receive the second RF signal, wherein the second matching network is configured to output a second modified RF signal upon receiving the second RF signal from the second RF generator;
a power distributor coupled to an output of the first matching network and an output of the second matching network, wherein the power distributor is configured to combine the first modified RF signal and the second modified RF signal to provide combined RF signals to a plurality of plasma processing stations, wherein the power distributor has multiple outputs coupled to the plasma processing stations, wherein the power distributor includes:
a low frequency circuit coupled to the first matching network and configured to provide a low frequency RF signal;
a high frequency circuit coupled to the second matching network and to the low frequency circuit and configured to provide a high frequency RF signal; and
an output circuit coupled to the high frequency circuit and the plurality of plasma processing stations, wherein the output circuit is configured to combine the low frequency RF signal and the high frequency RF signal to generate the combined RF signals to provide to the plasma processing stations; and
a shunt inductor coupled in parallel to one of the plasma processing stations to increase an amount of current to the one of the plasma processing stations.

### Claim 11 (depends on 10)

The system of claim 10, wherein the shunt inductor has two ends, wherein one of the ends is coupled to a ground connection and another one of the ends is coupled to the one of the plasma processing stations.

### Claim 12 (depends on 11)

The system of claim 11, wherein the shunt inductor is coupled between an input of the low frequency circuit and an end of a coaxial cable that couples an output of the low frequency circuit to the one of the plasma processing stations.

### Claim 13 (depends on 10)

The system of claim 10, wherein the shunt inductor is coupled at a point between the low frequency circuit and the one of the plasma processing stations.

### Claim 14 (depends on 10)

The system of claim 10, wherein the shunt inductor is coupled at a point between an input of the low frequency circuit and a direct current (DC) blocking capacitor of the low frequency circuit.

### Claim 15 (depends on 10)

The system of claim 10, wherein the shunt inductor is coupled at a point between a direct current (DC) blocking capacitor of the low frequency circuit and an inductor of the low frequency circuit.

### Claim 16 (depends on 10)

The system of claim 10, wherein the shunt inductor is coupled to a ground connection at one end and to a high frequency blocking circuit at an opposite end, wherein the shunt inductor is coupled in parallel to a first capacitor, wherein the high frequency blocking circuit includes an inductor in parallel with a second capacitor, wherein the shunt inductor is coupled via a switch to a balancing inductor of the low frequency circuit.

### Claim 17 (depends on 16)

The system of claim 16, wherein the first capacitor is coupled to the ground connection at one end and to the high frequency blocking circuit at an opposite end.

### Claim 18 (depends on 10)

The system of claim 10, wherein the shunt inductor is a variable or a fixed inductor.

### Claim 19

A method for reducing wafer bow, comprising:
providing, by a low frequency circuit coupled to a low frequency impedance matching network, a low frequency RF signal;
providing, by a high frequency circuit coupled to a high frequency impedance matching network, a high frequency RF signal;
combining the low frequency RF signal and the high frequency RF signal to generate a plurality of combined RF signals to provide to a plurality of plasma processing stations; and
reducing wafer bow by a shunt inductor of the low frequency circuit, wherein the wafer bow is reduced when the shunt inductor is coupled in parallel to one of the plasma processing stations to increase an amount of current to the one of the plasma processing stations.

### Claim 20 (depends on 19)

The method of claim 19, wherein the shunt inductor has two ends, wherein one of the ends is coupled to a ground connection and another one of the ends is coupled to the one of the plasma processing stations.

### Claim 21 (depends on 19)

The method of claim 19, wherein the shunt inductor is a variable or a fixed inductor.