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Level control systems for high purity chemical delivery systems

  • US 5,711,354 A
  • Filed: 06/07/1995
  • Issued: 01/27/1998
  • Est. Priority Date: 04/28/1993
  • Status: Expired due to Term
First Claim
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1. A level control system comprising a refillable ampule;

  • a bulk container containing a high purity source chemical;

    a refill line interposed between and communicating with said ampule and said bulk container for transferring the high purity source chemical from said bulk container to said ampule;

    a first metallic float level sensor inside said ampule having at least one trigger point for detecting a first level of the high purity source chemical and comprising a first magnetic sensor, said first magnetic sensor comprising a normally open terminal, a normally closed terminal and a common terminal; and

    an interface circuit for interfacing said metallic float level sensor with a CVD reactor, said CVD reactor having an indicator that provides a signal to indicate that the high purity source chemical in said ampule is at said first level when the level of the high purity source chemical in said ampule reaches the trigger point of said metallic float sensorsaid interface circuit comprising a first resistor connected to the output of said normally closed terminal of said first magnetic sensor, a voltage supply connected to said common terminal of said first magnetic sensor, and said first resistor and said normally open terminal of said first magnetic sensor tied together and communicated to said CVD reactor.

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