Planarizing machines and control systems for mechanical and/or chemical-mechanical planarization of microelectronic substrates
View Patent ↗A system for controlling a mechanical or chemical-mechanical planarizing machine comprises a light system, a sensor, and a computer. The light system can have at least a first emitter that generates a first light pulse having a first color and a second emitter that generates a second light pulse having a second color different than the first color. The first and second light pulses reflect from a microelectronic substrate in a manner that creates a first return light pulse corresponding to a reflectance of the first light pulse and a second return light pulse corresponding to a reflectance of the second light pulse. The sensor receives the first return light pulse and the second return light pulse, and the sensor generates a first measured intensity of the first return light pulse and a second measured intensity of the second return light pulse. The computer has a database and a computer readable medium. The database contains a plurality of sets of reference reflectances in which each set has a first reference component defined by a reflectance intensity of the first light pulse and a second reference component defined by a reflectance intensity of the second light pulse from a selected surface level in a layer of material on the microelectronic substrate. The computer readable medium contain a computer readable program that causes the computer to control a parameter of the planarizing machine when the first and second measured intensities correspond to the first and second reference components of a selected reference reflectance set.
1. A microelectronic substrate assembly for use in controlling mechanical and/or chemical-mechanical planarization processes, comprising:
a substrate;
a first layer of a first material having first color, the first layer being disposed over at least a portion of the substrate, and the first layer having a first surface defining a desired endpoint elevation for a planarizing cycle;
a second layer of a second material disposed over the first layer, the second layer having a second color different than the first color; and
a sacrificial marker layer of a third material having a third color optically distinct from the first and second colors of the first and second materials.
2 .The microelectronic substrate of claim 1 wherein:
the first material comprises silicon nitride;
the second material comprises silicon dioxide; and
the third material of the sacrificial marker layer comprises an opaque resist material.
3. The microelectronic substrate of claim 1 wherein:
the first material comprises silicon nitride;
the second material comprises silicon dioxide; and
the third material of the sacrificial marker layer comprises an optically transmissive material.
4. The microelectronic substrate of claim 1 wherein:
the first material comprises silicon nitride;
the second material comprises silicon dioxide; and
the third material of the sacrificial marker layer comprises a red layer of material.
5. The microelectronic substrate of claim 1 wherein:
the first material comprises silicon nitride;
the second material comprises silicon dioxide; and
the third material of the sacrificial marker layer comprises a black layer of material.
6. The microelectronic substrate of claim 1 wherein:
the first material comprises silicon nitride;
the second material comprises silicon dioxide; and
the third material of the sacrificial marker layer comprises a white layer of material.
7. A microelectronic substrate assembly for use in controlling mechanical and/or chemical-mechanical planarization processes, comprising:
a substrate;
a first layer of a first material having a first color, the first layer being disposed over at least a portion of the substrate;
a second layer of a second material having a second color, the second layer being disposed relative to the first layer; and
a sacrificial marker layer of a third material having a third color optically distinct from the first and second colors of the first and second materials, the sacrificial layer being disposed between the first layer and the second layer.
8. The microelectronic substrate of claim 7 wherein the sacrificial layer is on the first layer and the second layer is on the sacrificial layer.
9. The microelectronic substrate of claim 7 wherein the first layer is silicon nitride, the second layer is silicon dioxide, and the sacrificial layer is an opaque material.
10. The microelectronic substrate of claim 7 wherein the first layer is silicon nitride, the second layer is silicon dioxide, the sacrificial layer is on the first layer, and the second layer is on the sacrificial layer.
11. The microelectronic substrate of claim 7 wherein the first layer comprises silicon nitride, the second layer comprises silicon dioxide, and the third material of the sacrificial layer is red.
12. The microelectronic substrate of claim 7 wherein the first layer comprises silicon nitride, the second layer comprises silicon dioxide, and the third material of the sacrificial layer is black.
13. The microelectronic substrate of claim 7 wherein the first layer comprises silicon nitride, the second layer comprises silicon dioxide, and the third material of the sacrificial layer is white.
14. A method of mechanical and/or chemical-mechanical planarization of a microelectronic workpiece, comprising:
providing a microelectronic workpiece including (a) a substrate, (b) a first layer of a first material having a first color, the first layer being disposed over at least a portion of the substrate, (c) a second layer of a second material having a second color, the second layer being disposed relative to the first layer, and (c) a sacrificial marker layer of a third material having a third color optically distinct from the first and second colors of the first and second materials, the sacrificial layer being disposed between the first layer and the second layer;
contacting a face of the substrate with a planarizing surface of a planarizing pad while moving the substrate and/or the planarizing pad relative to each other;
impinging a series of light pulses against the substrate including a first light pulse at a first time interval and a second light pulse at a second time interval, the first light pulse having a first frequency and the second light pulse having a second frequency;
sensing a first intensity of a first return light pulse corresponding to the first light pulse reflecting from the substrate and a second intensity of a second return light pulse corresponding to the second light pulse reflecting from the substrate; and
controlling a parameter of the planarization process when the first and second intensities indicate that the sacrificial layer is exposed and/or at least partially removed from the substrate.
15. The method of claim 14 wherein controlling a parameter of the planarization process comprises indicating the intensity of the second color of the second layer and the intensity of third color of the sacrificial layer.
16. The method of claim 14 wherein controlling a parameter of the planarization process comprises indicating the intensity of the first color of the first layer and the intensity of the third color of the sacrificial layer.
17. The method of claim 14 wherein the sacrificial layer is red and controlling a parameter of the planarization process comprises indicating the intensity of the first color of the first layer, the second color of the second layer, and the third color of the sacrificial layer.
18. The method of claim 17 wherein one of the first light pulse or second light pulse is red, the sacrificial layer is red, and indicating the intensity of the sacrificial layer comprises impinging the first or second pulse of red light against the substrate and sensing the intensity of the return pulse of the red light.
19. The method of claim 17 wherein the sacrificial layer is white and indicating the intensity of the sacrificial layer comprises impinging discreet pulses of red, green and blue light against the substrate and sensing the intensities of return pulses of the red, green and blue light.
20. The method of claim 17 wherein the sacrificial layer is black and indicating the intensity of the sacrificial layer comprises impinging discreet pulses of red, green and blue light against the substrate and sensing the intensities of return pulses of the red, green and blue light.