Patent US4386460A successfully refreshed from Google Patents.
US4386460A
Expired / Lapsed
US
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Method of making multi-megohm thin film resistors
Assignee: AT&T Inc
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Filing: 1981-05-14
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Granted: 1983-06-07
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Expires: 2001-05-14
Abstract
Abstract A geometry and method of fabricating thin film resistors which are tolerant of faults in the film and therefore permit attainment of high resistances. The resistor includes a series of connected closed loops (15) each with a member (17) providing a short circuit path. Such members are successively cut and the change in resistance is determined after each cut. This change is compared to certain threshold values to determine the presence or absence of an open circuit fault in each loop. The resistor is then trimmed to its desired value by cutting only the loops where no opens have been discovered.
Inventors
- 👤 Dennis H. Klockow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:41
CPC Classifications
H; H01; H01C; H01C17/00; H01C17/22; H01C17/23; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49004; Y10T29/49082; Y10T29/49099
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
143 words
A method of fabricating on an insulating layer (10) a thin film resistor including a series of closed loops (15) electrically coupled by horizontal connectors (16) between an input and output portion (11 and 12) where each loop comprises an upper portion above the connector and a lower portion below the connector characterized in the steps of providing, in addition to said closed loops, an individual short circuit path (17) for each of said loops, successively cutting each of said short circuit paths, measuring the resulting change in resistance between the input and output portions after each individual short circuit path is cut and comparing said change to a threshold value to determine the presence or absence of an open circuit in that loop, and successively cutting only the loops for which no open circuit is indicated until a desired resistance is achieved.
Claim 2
Independent Claim
143 words
A method of fabricating on an insulating layer (10) a thin film resistor including a series of closed loops (15) electrically coupled by horizontal connectors (16) between an input and output portion (11 and 12) where each loop comprises an upper portion above the connector and a lower portion below the connector characterized in the steps of providing, in addition to said closed loops, an individual short circuit path (17) for each of said loops, successively cutting each of said short circuit paths, measuring the resulting change in resistance between the input and output portions after each individual short circuit path is cut and comparing said change to a threshold value to determine the presence or absence of an open circuit in that loop, and successively cutting only the loops for which no open circuit is indicated until a desired resistance is achieved.
Claim 3
Dependent Claim
22 words
The method according to claim 1 wherein each loop consists of an upper portion above the connector with at least two peaks.
Claim 4
Dependent Claim
20 words
The method according to claim 2 wherein the short circuit paths electrically couple the two peaks of the upper portion.
Claim 5
Dependent Claim
74 words
The method according to claim 3 wherein threshold values are set about a nominal change in resistance (ΔR L /R L ) for a loop with no open fault calculated essentially according to the relationship: ##EQU10## where n is the ratio of the length of a leg of the upper portion to the length of the bottom portion and R L is the resistance of the loop prior to cutting the short circuit path.
Claim 6
Dependent Claim
38 words
The method according to claim 1 wherein the short circuit paths electrically couple the loops to the output portion and the threshold value is determined from the mean change in resistance (ΔR mean ) after cutting all paths.
Claim 7
Dependent Claim
40 words
The method according to claim 5 wherein the threshold value ΔR TH is determined essentially from the relationship: ##EQU11## where m is the ratio of the path length of the upper portion to the path length of the lower portion.
Claim 8
Dependent Claim
18 words
The method according to claim 1 wherein the line width of the resistor is less than 25 μm.
Claim 9
Dependent Claim
22 words
The method according to claim 1 wherein the final value of resistance for the resistor is within the range 50 KΩ-100 MΩ.
Claim 10
Dependent Claim
18 words
The method according to claim 1 wherein the short circuit paths and loops are cut by a laser.
Claim 11
Dependent Claim
19 words
The method according to claim 1 wherein the resistor comprises a tantalum nitride film formed on a ceramic substrate.
Claim 12
Independent Claim
211 words
A method of fabricating on an insulating substrate (10) a thin film resistor having a final resistance greater than 50 kilohms and a line width less that 25 μm, said resistor including a series of closed loops (15) electrically coupled by means of horizontal connectors (16) between an input and output termination pad (11 and 12), where each loop comprises an upper portion above the connector and a lower portion below the connector characterized in that the upper portion of each loop comprises at least two peaks, an individual short circuit path, (17) in addition to said closed loops, is provided between the two peaks of each loop, threshold values for a loop without an open circuit fault are provided based on the ratio (n) between the length of a leg of the upper portion and the length of the lower portion, each individual short circuit path is cut and the resulting change in resistance between the input and output pads after each individual short circuit path is cut is measured and compared to the threshold values to determine the presence or absence of an open circuit fault in each loop, and only the loops for which no open circuit fault is indicated are cut until a desired resistance is achieved.
Claim 13
Independent Claim
211 words
A method of fabricating on an insulating substrate (10) a thin film resistor having a final resistance greater than 50 kilohms and a line width less that 25 μm, said resistor including a series of closed loops (15) electrically coupled by means of horizontal connectors (16) between an input and output termination pad (11 and 12), where each loop comprises an upper portion above the connector and a lower portion below the connector characterized in that the upper portion of each loop comprises at least two peaks, an individual short circuit path, (17) in addition to said closed loops, is provided between the two peaks of each loop, threshold values for a loop without an open circuit fault are provided based on the ratio (n) between the length of a leg of the upper portion and the length of the lower portion, each individual short circuit path is cut and the resulting change in resistance between the input and output pads after each individual short circuit path is cut is measured and compared to the threshold values to determine the presence or absence of an open circuit fault in each loop, and only the loops for which no open circuit fault is indicated are cut until a desired resistance is achieved.
Claim 14
Independent Claim
176 words
A method of fabricating on an insulating substrate (10) a thin film resistor having a final resistance greater than 50 kilohms and a line width less than 25 μm, said resistor including a series of closed loops (15) electrically coupled by means of horizontal connectors (16) between an input and output termination pad (11 and 12), each loop having an upper portion above the connector and a lower portion below the connector, characterized in the steps of providing, in addition to said closed loops, an individual short circuit path (17) between each loop and the output pad (12), successively cutting each of said short circuit paths and measuring the resulting change in resistance between the input and output pads after each individual short circuit path is cut, establishing a threshold value (ΔR TH ) based on the mean change in resistance (ΔR mean ) after all short circuit paths are cut, and successively cutting only the loops for which a change in resistance less than the threshold value was measured until a desired resistance is achieved.
Claim 15
Independent Claim
176 words
A method of fabricating on an insulating substrate (10) a thin film resistor having a final resistance greater than 50 kilohms and a line width less than 25 μm, said resistor including a series of closed loops (15) electrically coupled by means of horizontal connectors (16) between an input and output termination pad (11 and 12), each loop having an upper portion above the connector and a lower portion below the connector, characterized in the steps of providing, in addition to said closed loops, an individual short circuit path (17) between each loop and the output pad (12), successively cutting each of said short circuit paths and measuring the resulting change in resistance between the input and output pads after each individual short circuit path is cut, establishing a threshold value (ΔR TH ) based on the mean change in resistance (ΔR mean ) after all short circuit paths are cut, and successively cutting only the loops for which a change in resistance less than the threshold value was measured until a desired resistance is achieved.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-06-06 | 1986-12-06 | 1987-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-06 | 1990-12-06 | 1991-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-06 | 1994-12-06 | 1995-06-07 | $7700.00 | Window Closed / Lapsed |