# US 5,700,401 A · Liquid auto-level apparatus and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,700,401 A - Document ID: US5700401A - Status: Granted - Kind: A - Application number: 08/577,560 - Filed: 1995-12-22 - Granted: 1997-12-23 - Earliest claimed: 1995-12-22 - Assignees: Microbar Systems, Inc. - Inventors: Richard S. Weinberg; James W. Thomas - Web page: https://patentgrep.com/patent/US5700401A ## CPC - H10P 72/0416: {with the semiconductor substrates being dipped in baths or vessels} - F17C 13/021: {having the height as the parameter} - G05D 9/12: characterised by the use of electric means - F17C 2205/0326: electrically actuated - F17C 2205/0335: Check-valves or non-return valves - F17C 2205/0338: Pressure regulators - F17C 2221/014: Nitrogen - F17C 2223/0123: gaseous, e.g. CNG, GNC - F17C 2227/0135: Pumps - F17C 2250/032: using computers - F17C 2250/0408: Level of content in the vessel - F17C 2250/043: Pressure - F17C 2250/061: Level of content in the vessel - F17C 2250/075: when full - F17C 2250/077: when empty - F17C 2260/022: Avoiding overfilling - F17C 2270/0518: Semiconductors - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - F17C: VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES (storing fluids in natural or artificial cavities or chambers in the earth B65G5/00; construction or assembling of bulk storage containers employing civil-engineering techniques E04H7/00; variable-capacity gas-holders F17B; liquefaction or refrigeration machines, plants, or systems F25) - G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES ## Abstract An HMDS tank for use in an integrated circuit fabrication process includes a tank configured to hold HMDS having an first inlet port configured to receive a carrier gas below an HMDS surface level, an outlet port configured to release said carrier gas saturated with HMDS above the HMDS surface level, and a second inlet port configured to receive HMDS. A sensor is positioned in the tank at a predetermined HMDS level and configured to generate a sensor signal when the HMDS surface level falls below the predetermined HMDS level. A processor is coupled to the sensor and configured to generate a fill signal in response to the sensor signal to initiate introduction of HMDS into the tank through the second inlet port. In another embodiment, the HMDS tank further includes a second sensor positioned in the tank at a low HMDS level. The processor is also coupled to the second sensor and configured to generate an alarm signal in response to the second sensor signal to warn an operator of a low HMDS level in the tank. The alarm signal can instruct the integrated circuit fabrication process to halt until corrective action is taken. An advantage of the invention includes a substantially constant HMDS level that in turn provides a substantially constant concentration of HMDS in the carrier gas which is delivered to the integrated circuit fabrication process. Additional advantages include increased integrated circuit fabrication up-time, reduced contamination and improved efficiency and continuity of the integrated circuit fabrication process. ## Claims ### Claim 1 A tank apparatus for use in an integrated circuit fabrication process, comprising: a tank configured to hold a liquid, said tank having a first inlet port configured to receive a carrier gas below a liquid surface level, an outlet port configured to release said carrier gas saturated with said liquid above said liquid surface level and a second inlet port configured to receive said liquid; a sensor positioned in said tank at a predetermined liquid level and configured to generate a fill sensor signal when said liquid surface level falls below said predetermined liquid level; and a processor coupled to said sensor and configured to generate a fill signal in response to said fill sensor signal to initiate introduction of said liquid into said tank through said second inlet port to maintain said liquid surface level at a substantially constant level and to provide a substantially constant path length for said carrier gas in said liquid in order to maintain a substantially constant concentration of said liquid in said carrier gas. ### Claim 2 (depends on 1) The tank apparatus of claim 1, wherein: said sensor is configured to generate a full sensor signal when said liquid surface level rises above said predetermined liquid level; and said processor is further configured to generate a halt signal in response to said full sensor signal to halt introduction of said liquid into said tank through said second inlet port. ### Claim 3 (depends on 1) The tank apparatus of claim 1, further comprising: a low sensor positioned in said tank at a low liquid level and configured to generate an alarm signal when said liquid surface level falls below said low sensor. ### Claim 4 (depends on 1) The tank apparatus of claim 1, further comprising: a high sensor positioned in said tank at a high liquid level and configured to generate an alarm signal when said liquid surface rises above said high sensor; and wherein said processor is coupled to said high sensor and configured to generate a halt signal in response to said alarm signal to halt introduction of said liquid into said tank through said second inlet port. ### Claim 5 (depends on 3) The tank apparatus of claim 3, further comprising: a high sensor positioned in said tank at a high liquid level and configured to generate a second alarm signal when said liquid surface rises above said high sensor; and wherein said processor is coupled to said high sensor and configured to generate a halt signal in response to said second alarm signal to halt introduction of said liquid into said tank through said second inlet port. ### Claim 6 (depends on 1) The tank apparatus of claim 1, further comprising: a liquid reserve tank configured to hold said liquid and having an outlet port; and a pump coupled to said liquid reserve tank outlet port, to said tank apparatus second inlet port, and to said processor; and wherein said processor is configured to activate said pump in response to said fill sensor signal. ### Claim 7 (depends on 2) The tank apparatus of claim 2, further comprising: a liquid reserve tank configured to hold said liquid and having an outlet port; and a pump coupled to said liquid reserve tank outlet port, to said tank apparatus second inlet port, and to said processor; and wherein said processor is configured to activate said pump in response to said fill sensor signal and to halt said pump in response to said full sensor signal. ### Claim 8 (depends on 3) The tank apparatus of claim 3, further comprising: a liquid reserve tank configured to hold said liquid and having an outlet port; and a pump coupled to said liquid reserve tank outlet port, to said tank apparatus second inlet port, and to said processor; and wherein said processor is configured to activate said pump in response to said fill sensor signal and to halt said pump in response to said full sensor signal. ### Claim 9 (depends on 4) The tank apparatus of claim 4, further comprising: a liquid reserve tank configured to hold said liquid and having an outlet port; and a pump coupled to said liquid reserve tank outlet port, to said tank apparatus second inlet port, and to said processor; and wherein said processor is configured to activate said pump in response to said fill sensor signal and to halt said pump in response to said full sensor signal. ### Claim 10 (depends on 5) The tank apparatus of claim 5, further comprising: a liquid reserve tank configured to hold said liquid and having an outlet port; and a pump coupled to said liquid reserve tank outlet port, to said tank apparatus second inlet port, and to said processor; and wherein said processor is configured to activate said pump in response to said fill sensor signal and to halt said pump in response to said full sensor signal. ### Claim 11 (depends on 6) The tank apparatus of claim 6, further comprising: a regulator coupled to said processor and said first inlet port and configured to deliver said carrier gas to said tank at a regulated pressure; and wherein said processor is configured to control said regulator to maintain a pressure range of said carrier gas in said tank of approximately 5 to 15 pounds per square inch. ### Claim 12 (depends on 7) The tank apparatus of claim 7, further comprising: a regulator coupled to said processor and said first inlet port and configured to deliver said carrier gas to said tank at a regulated pressure; and wherein said processor is configured to control said regulator to maintain a pressure range of said carrier gas in said tank of approximately 5 to 15 pounds per square inch. ### Claim 13 (depends on 8) The tank apparatus of claim 8, further comprising: a regulator coupled to said processor and said first inlet port and configured to deliver said carrier gas to said tank at a regulated pressure; and wherein said processor is configured to control said regulator to maintain a pressure range of said carrier gas in said tank of approximately 5 to 15 pounds per square inch. ### Claim 14 (depends on 9) The tank apparatus of claim 9, further comprising: a regulator coupled to said processor and said first inlet port and configured to deliver said carrier gas to said tank at a regulated pressure; and wherein said processor is configured to control said regulator to maintain a pressure range of said carrier gas in said tank of approximately 5 to 15 pounds per square inch. ### Claim 15 (depends on 10) The tank apparatus of claim 10, further comprising: a regulator coupled to said processor and said first inlet port and configured to deliver said carrier gas to said tank at a regulated pressure; and wherein said processor is configured to control said regulator to maintain a pressure range of said carrier gas in said tank of approximately 5 to 15 pounds per square inch. ### Claim 16 (depends on 1) The tank apparatus of claim 1, further comprising: a liquid reserve tank configured to hold said liquid and having an outlet port; and a fluid transfer structure coupled to said liquid reserve tank outlet port, to said tank apparatus second inlet port, and to said processor; and wherein said processor is configured to activate said fluid transfer structure in response to said fill sensor signal. ### Claim 17 (depends on 2) The tank apparatus of claim 2, further comprising: a liquid reserve tank configured to hold said liquid and having an outlet port; and a fluid transfer structure coupled to said liquid reserve tank outlet port, to said tank apparatus second inlet port, and to said processor; and wherein said processor is configured to activate said fluid transfer structure in response to said fill sensor signal. ### Claim 18 (depends on 3) The tank apparatus of claim 3, further comprising: a liquid reserve tank configured to hold said liquid and having an outlet port; and a fluid transfer structure coupled to said liquid reserve tank outlet port, to said tank apparatus second inlet port, and to said processor; and wherein said processor is configured to activate said fluid transfer structure in response to said fill sensor signal. ### Claim 19 (depends on 4) The tank apparatus of claim 4, further comprising: a liquid reserve tank configured to hold said liquid and having an outlet port; and a fluid transfer structure coupled to said liquid reserve tank outlet port, to said tank apparatus second inlet port, and to said processor; and wherein said processor is configured to activate said fluid transfer structure in response to said fill sensor signal. ### Claim 20 (depends on 16) The tank apparatus of claim 16, further comprising: a regulator coupled to said processor and said first inlet port and configured to deliver said carrier gas to said tank at a regulated pressure; and wherein said processor is configured to control said regulator to maintain a pressure range of said carrier gas in said tank of approximately 5 to 15 pounds per square inch.