Pressure regulation in remote zones

• US 20060169327A1
• Filed: 01/17/2006
• Published: 08/03/2006
• Est. Priority Date: 03/09/2004
• Status: Active Grant

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Shajii, Ali, Nagarkatti, Siddharth P., Hill, Gordon
• Granted Patent: US 8,037,896 B2
• Time in Patent Office: Days
• US Class Current: 137/487.500
• CPC Class Codes: G05D 16/206 the plurality of throttling means being arranged for the control of a plurality of diverging pressures from a single pressure G05D16/204 takes precedence
• CPC Class Codes: H01L 21/30625 With simultaneous mechanical treatment, e.g. mechanico-chemical polishing
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve
• CPC Class Codes: Y10T 137/7838 Plural
• CPC Class Codes: Y10T 137/87209 Electric
• CPC Class Codes: Y10T 137/8733 Fluid pressure regulator in at least one branch
• CPC Class Codes: Y10T 137/8741 With common operator
• CPC Class Codes: Y10T 137/87507 Electrical actuator
• CPC Class Codes: Y10T 137/87772 With electrical actuation

Abstract

A pressure control system remotely controls pressure within one or more remote zones, each respectively connected to an enclosure through a conduit, by controlling flow of a fluid into and out of each enclosure. The pressure of the fluid is measured within each enclosure. An estimated pressure within each zone is computed, as a function of the measured pressure in the enclosure and known characteristics of the conduit and the zone. For each zone, an inlet proportional valve and an outlet proportional valve of each enclosure is operated so as to control the input flow rate of the fluid into the respective enclosure and the output flow rate of the fluid out of the enclosure as a function of a pressure set point and the estimated pressure, thereby regulating pressure within the zone in accordance with the pressure set point.

Claims

1. A system for remotely controlling pressure within a zone, the system comprising:

a pressure sensor configured to measure pressure within an enclosure connectable to the zone through a conduit and located remote from the zone;

a valve system configured to regulate flow of a fluid into and out of the enclosure and through the conduit into the zone, the valve system including at least an inlet proportional valve configured to regulate an input flow rate of the fluid into the enclosure, and an outlet proportional valve configured to regulate an output flow rate of the fluid out of the enclosure;

a zone pressure estimator configured to compute an estimated pressure within the zone as a function of the pressure measured by the pressure sensor, and as a function of known characteristics of the conduit; and

a controller configured to regulate pressure within the zone by operating the inlet proportional valve and the outlet proportional valve so as to control the input flow rate and the output flow rate as a function of the estimated pressure from the zone pressure estimator and of a pressure set point for the zone.

2. The system of claim 1,

wherein the controller is further configured to send an input flow command signal to the inlet proportional valve and an output flow command signal to the output proportional valve so as to control the input flow rate and the output flow rate according to the input flow command signal and the output flow command signal, respectively.

3. The system of claim 1,

wherein the controller is further configured to effect PI (Proportional-Integral) control of the input flow rate and the output flow rate;

wherein the input flow command signal is given by;

Q_in=<sub>κ

Pin</sub> (P_t−

P_z)+<sub>κ

Iin</sub>∫

(P_t−

P_z) dt,

wherein the output flow command signal is given by;

Q_out=<sub>κ

Pout</sub> (P_t−

P_z)+<sub>κ

Iout</sub>∫

(P_t−

P_z) dt; and

wherein;

Q_in denotes the input flow rate,

Q_out denotes the output flow rate,

<sub>κ

Pin</sub> denotes a proportional gain for the input flow rate,

<sub>κ

Iin</sub>denotes an integral gain for the input flow rate,

<sub>κ

Pout</sub> denotes a proportional gain for the output flow rate,

<sub>κ

Iout</sub> denotes an integral gain for the output flow rate,

P_z denotes the estimated pressure within the zone,

P_t denotes a pressure trajectory for the pressure setpoint,

and P_t−

P_z denotes a tracking error.

4. The system of claim 1, further comprising a pressurized fluid source connected to the inlet proportional valve, and a vacuum exhaust connected to the outlet proportional valve.

5. The system of claim 4, further comprising a flow constrictor between the outlet proportional valve and the vacuum exhaust.

6. The system of claim 1, wherein the zone has flexible walls, and wherein the zone pressure estimator is further configured to compute an estimated volume of the zone as a function of known characteristics of the conduit and the pressure measured by the pressure sensor, so as to compute the estimated pressure within the enclosure.

7. A system for remotely controlling pressure within each of i zones respectively connectable to i enclosures through conduits i, by controlling flow of a fluid into and out of each enclosure i, and through each conduit i into each zone i, wherein i=1, . . . , N, the system comprising:

a pressure measurement system configured to measure pressure of the fluid in each of the i enclosures;

a valve system including, for each enclosure i, at least one inlet proportional valve configured to regulate an input flow rate of the fluid into the enclosure i, and at least one outlet proportional valve configured to regulate an output flow rate of the fluid out of the enclosure i;

a zone pressure estimator coupled to the pressure measurement system and configured to, for each zone i, receive a measured pressure in the enclosure i from the pressure measurement system, and compute an estimated pressure within the zone i as a function of the measured pressure in the enclosure i, and as a function of known characteristics of the conduit i and the zone i; and

a controller configured to control pressure within each zone i by operating the inlet proportional valve and the outlet proportional valve of each enclosure i so as to control the input flow rate of the fluid into the enclosure i and the outlet flow rate of the fluid out of the enclosure i as a function of a pressure set point for the zone i and the estimated pressure within the zone i from the zone pressure estimator.

8. The system of claim 7,

wherein the pressure measurement system comprises a plurality of pressure sensors, each of the pressure sensors respectively connected to measure pressure within the i enclosures.

9. The system of claim 7,

wherein for each zone i, the controller is further configured to send an input flow command signal to the inlet proportional valve of enclosure i and an output flow command signal to the output proportional valve of enclosure i so as to control the input flow rate into enclosure i and the output flow rate out of enclosure i according to the input flow command signal and the output flow command signal, respectively,

10. The system of claim 7,

wherein for at least one of the enclosures i, the controller is further configured to effect PI control of the input flow rate and the output flow rate of the at least one enclosure;

wherein the input flow command signal from the controller to the inlet proportional valve of enclosure i comprises;

Q_in=<sub>κ

Pin</sub> (P_t−

P_z)+<sub>κ

Iin</sub>∫

(P_t−

P_z) dt,

wherein the output flow command signal from the controller to the outlet proportional valve of enclosure i is given by;

Q_out=<sub>κ

Pout</sub> (P_t−

P_z)+<sub>κ

Iout</sub> ∫

(P_t−

P_z) dt; and

wherein;

Q_in,i denotes the input flow rate into enclosure i,

Q_out,i denotes the output flow rate out of enclosure i,

<sub>κ

Pin</sub> denotes a proportional gain for the input flow rate,

<sub>κ

Iin</sub> denotes an integral gain for the input flow rate,

<sub>κ

Pout</sub> denotes a proportional gain for the output flow rate,

<sub>κ

Iout</sub> denotes an integral gain for the output flow rate,

P_z,i denotes the estimated pressure within the zone i,

P_t denotes a desired pressure trajectory from one pressure setpoint to another pressure setpoint,

and P_t−

P_z,i denotes a tracking error.

11. The system of claim 7, further comprising a pressurized fluid source connected to the inlet proportional valves of the i enclosures, and a vacuum exhaust connected to the outlet proportional valves of the i enclosures.

12. The system of claim 11, further comprising a flow constrictor between each outlet proportional valve and the vacuum exhaust.

13. The system of claim 11, further comprising a pressure manifold between the pressurized fluid source and the inlet proportional valves.

14. The system of claim 12, wherein the flow constrictor comprises a venturi.

15. The system of claim 7, wherein at least some of the i zones have rigid walls.

16. The system of claim 7, wherein at least some of the i zones have flexible walls that allow the zones having the flexible walls to expand and to contract.

17. The system of claim 16, wherein the zone pressure estimator is further configured to compute an estimated volume of each of the zones with flexible walls so as to compute the estimated pressure within the enclosures that are connected to the zones with flexible walls.

18. The system of claim 7, wherein at least some of the i zones are coupled.

19. The system of claim 7, wherein at least some of the i zones are non-coupled.

20. The system of claim 8,

wherein at least some of the i zones have flexible walls that allow the zones having the flexible walls to expand and to contract,

wherein at least some of the i zones are coupled, and

wherein the known characteristics of the i conduits include constants C_tube,i and τ

_tube,i associated with each conduit i connecting the line i to the zone i, C_tube,i representing a conductance of the conduit, and τ

_tube,i representing a flow equilibration time constant across the conduit; and

wherein the known characteristics of the i zones include an initial volume (V_z,0i) of each zone i under STP (Standard Temperature and Pressure) conditions, a volume expansion/contraction time constant (T_V), an expansion/contraction coefficient (Y_ii) of zone i, and a coupling coefficient (Y_ij) between zone i and zone j, where j=1, . . . , N.

21. The system of claim 20, wherein for each zone i, the zone pressure estimator is programmed to calculate an nth sample ^{{circumflex over (P)}z,i(n)} of the estimated pressure of the zone i, an nth sample ^{{circumflex over (V)}z,i(n)} of an estimated volume of the zone i, and an nth sample ^{{circumflex over (Q)}z,i(n)} of an estimated input flow rate into the enclosure i;

and wherein

$\begin{array}{c}{\hat{P}}_{z,i}^{\left(n\right)}=\text{\hspace{1em}<br><br>}<br><br>\begin{array}{c}<br><br>{\hat{P}}_{z,i}^{\left(n-1\right)}+\\ <br><br>\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t<br><br>\left(\begin{array}{c}\frac{P_{\mathrm{STP}}}{{\hat{V}}_{z,i}^{\left(n\right)}}<br><br>{\hat{Q}}_{z,i}^{\left(n\right)}+\frac{{\hat{P}}_{z,i}^{\left(n-1\right)}}{{\mathrm{\tau <br><br>}}_v<br><br>{\hat{V}}_{z,i}^{\left(n\right)}}\\ \left[\begin{array}{c}{\hat{V}}_{z,i}^{\left(n\right)}-V_{z<br><br>\text{\hspace{1em}<br><br>}<br><br>0,i}-{\mathrm{\gamma <br><br>}}_{\mathrm{ii}}<br><br>\left({\hat{P}}_{z,i}^{\left(n-1\right)}-P_{\mathrm{STP}}\right)-\\ \underset{i\ne <br><br>j}{\sum <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\gamma <br><br>}}_{\mathrm{ij}}<br><br>\left({\hat{P}}_{z,i}^{\left(n-1\right)}-{\hat{P}}_{i,j}^{\left(n-1\right)}\right)\end{array}\right]\end{array}\right),\end{array}\\ {\hat{Q}}_{z,i}^{\left(n\right)}=\frac{{\hat{Q}}_{z,i}^{\left(n-1\right)}+\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{tC}}_{\mathrm{pipe},i}<br><br>\left(P_{b,i}^{\left(n\right)}-{\hat{P}}_{z,i}^{\left(n-1\right)}\right)}{\left(1+\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t}{{\mathrm{\tau <br><br>}}_{\mathrm{pipe},i}}\right)},\\ {\hat{V}}_{z,i}^{\left(n\right)}=\begin{array}{c}{\hat{V}}_{z,i}^{\left(n-1\right)}+\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t}{{\mathrm{\tau <br><br>}}_v}\\ \frac{\left[V_{z<br><br>\text{\hspace{1em}<br><br>}<br><br>0,i}+{\mathrm{\gamma <br><br>}}_{\mathrm{ii}}<br><br>\left({\hat{P}}_{z,i}^{\left(n-1\right)}-P_{\mathrm{STP}}\right)+\underset{i\ne <br><br>j}{\sum <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\gamma <br><br>}}_{\mathrm{ij}}<br><br>\left({\hat{P}}_{z,i}^{\left(n-1\right)}-{\hat{P}}_{z,j}^{\left(n-1\right)}\right)\right]}{\left(1+\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t}{{\mathrm{\tau <br><br>}}_v}\right)},\mathrm{and}\end{array}\end{array}$

wherein P_bi denotes the pressure measured by the pressure sensor connected to enclosure i,

wherein Q_zi denotes an input flow rate of the fluid into zone i that is given by a different between the input flow rate Q_in,i of the fluid into enclosure i and the output flow rate Q_out,i of the fluid out of enclosure i.

22. A machine including the system of claim 21, and further including the i zones respectively connected to the i enclosures.

23. The machine of claim 22, further comprising a CMP carrier head containing the i zones.

24. A method of remotely controlling pressure within each of i zones respectively connectable to i enclosures through conduits i, by controlling flow of a fluid into and out of each enclosure i and through each conduit into each zone i, wherein i=1, . . . N. comprising:

measuring pressure of the fluid within each of i enclosures;

computing an estimated pressure within each zone i as a function of the measured pressure in the enclosure i, and as a function of known characteristics of the conduit i and the zone i; and

for each zone i, operating an inlet proportional valve and an outlet proportional valve of each enclosure i so as to control the input flow rate of the fluid into the enclosure i and the output flow rate of the fluid out of the enclosure i as a function of a pressure set point for the zone i and the estimated pressure within the zone i, thereby regulating pressure within the zone i in accordance with the pressure set point.