Techniques for processing devices

1. A method of forming a microelectronic assembly, comprising:

preparing a bonding surface of a first substrate, including:

planarizing the bonding surface of the first substrate to have a first predetermined minimal surface variance; and

plasma activating the bonding surface of the first substrate;

preparing a bonding surface of a second substrate, including planarizing the bonding surface of the second substrate to have a second predetermined minimal surface variance;

mounting the second substrate to a dicing sheet or dicing tape held by a dicing frame;

singulating the second substrate into a plurality of dies while the second substrate is mounted to the dicing sheet or dicing tape, each die of the plurality of dies having a bonding surface comprising a portion of the bonding surface of the second substrate;

processing the plurality of dies while the plurality of dies is mounted to the dicing sheet or dicing tape;

selecting a die of the plurality of dies using a pick and place tool; and

directly bonding the bonding surface of the die to the bonding surface of the first substrate without adhesive, and without activating the bonding surface of the die.

2. The method of claim 1 , further comprising:

applying a protective coating to the bonding surface of the second substrate; and

cleaning the protective coating from the plurality of dies while the plurality of dies is mounted to the dicing sheet or dicing tape.

3. The method of claim 2 , further comprising cleaning one or more surfaces of the plurality of dies or the first substrate using a chemical reagent, a megasonic transducer, and/or a mechanical brush.

4. The method of claim 1 , further comprising processing the die of the plurality of dies while the die is held by the pick and place tool, the processing including insitu cleaning the bonding surface of the die.

5. The method of claim 1 , wherein the dicing sheet or dicing tape is a first dicing sheet or a first dicing tape, and further comprising transferring the plurality of dies to a second dicing sheet or second dicing tape to avoid contamination to the plurality of dies from particles or residue on the first dicing sheet or the first dicing tape and/or to enable use of solvents or chemicals that are not compatible with the first dicing tape.

6. The method of claim 1 , further comprising minimizing exposure of the dicing sheet or dicing tape to contaminants by shielding exposed portions of the dicing sheet or dicing tape beyond the plurality of dies, minimizing exposed portions of the dicing sheet or dicing tape between dies of the plurality of dies, and/or shortening one or more process step durations.

7. The method of claim 1 , further comprising selecting the die of the plurality of dies at the bonding surface of the die using the pick and place tool, without contaminating the bonding surface of the die to an extent greater than a predefined bonding quality specification.

8. The method of claim 7 , wherein a surface of the pick and place tool is in direct contact with the bonding surface of die when the die is selected with the pick and place tool.

9. The method of claim 7 , wherein a surface of the pick and place tool is porous.

10. The method of claim 7 , wherein a surface of the pick and place tool is formed from a hydrophobic material or is coated with a hydrophobic material.

11. The method of claim 1 , further comprising treating the bonding surface of the die to become hydrophobic.

12. The method of claim 1 , wherein the microelectronic assembly comprises a stack of multiple directly bonded dies of the plurality of dies, and wherein the microelectronic assembly is low-temperature annealed after placement of each die on the stack.

13. The method of claim 1 , wherein the microelectronic assembly comprises a stack of multiple directly bonded dies of the plurality of dies, and wherein the microelectronic assembly is annealed only after placement of a plurality of dies on the stack.

14. The method of claim 1 , wherein the bonding surface of the die of the plurality of dies is a first bonding surface and wherein the die of the plurality of dies includes a second bonding surface opposite the first bonding surface of the die, the method further comprising:

preparing the second bonding surface of the die, including:

planarizing and/or cleaning the second bonding surface of the die to have a third predetermined minimal surface variance; and

plasma activating the second bonding surface of the die;

preparing a first bonding surface of an additional die, the first bonding surface of the additional die having a fourth predetermined minimal surface variance; and

directly bonding the first bonding surface of the additional die to the second bonding surface of the die without adhesive, and without activating the first bonding surface of the additional die.

15. A method of forming a microelectronic assembly, comprising:

preparing a bonding surface of a first substrate;

preparing a bonding surface of a second substrate, including planarizing the bonding surface of the second substrate to have a predetermined minimal surface variance;

mounting the second substrate to a dicing tape;

singulating the second substrate into a plurality of dies while the second substrate is mounted to the dicing tape, each die of the plurality of dies having a bonding surface comprised of a portion of the bonding surface of the second substrate;

processing the plurality of dies while the plurality of dies is mounted to the dicing tape;

selecting a die of the plurality of dies using a pick and place tool; and

directly bonding the bonding surface of the die to the bonding surface of the first substrate without adhesive, and without activating the bonding surface of the die.

16. The method of claim 15 , further comprising planarizing the bonding surface of the first substrate to have another predetermined minimal surface variance; and plasma activating the bonding surface of the first substrate.

17. The method of claim 15 , further comprising planarizing the bonding surface of the first substrate to have another predetermined minimal surface variance; and plasma asking and plasma activating the bonding surface of the first substrate.

18. The method of claim 15 , further comprising rendering the bonding surface of the die hydrophobic prior to directly bonding the bonding surface of the die to the bonding surface of the first substrate.

19. A method of forming a microelectronic assembly, comprising:

preparing a bonding surface of a first substrate, including:

planarizing the bonding surface of the first substrate to have a first predetermined minimal surface variance; and

plasma activating the bonding surface of the first substrate;

preparing a bonding surface of a second substrate, including planarizing the bonding surface of the second substrate to have a second predetermined minimal surface variance;

mounting the second substrate to a dicing sheet or dicing tape held by a grip ring or dicing frame;

singulating the second substrate into a plurality of dies while the second substrate is mounted to the dicing sheet or dicing tape, each die of the plurality of dies having a bonding surface comprised of a portion of the bonding surface of the second substrate;

processing the plurality of dies while the plurality of dies is mounted to the dicing sheet or dicing tape;

selecting a die of the plurality of dies using a pick and place tool; and

directly bonding the bonding surface of the die to the bonding surface of the first substrate without adhesive.

20. The method of claim 19 , further comprising rendering the bonding surface of the die hydrophobic prior to directly bonding the bonding surface of the die to the bonding surface of the first substrate.

21. The method of claim 19 , further comprising activating the bonding surface of the die.

22. The method of claim 19 further comprising applying a megasonic cleaner to clean the plurality of dies or the first substrate or the plurality of dies and the first substrate.