Method and structures for indexing dice

• US 20080153250A1
• Filed: 02/19/2008
• Published: 06/26/2008
• Est. Priority Date: 04/19/2004
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Valtolina, Marco Natale, Brambilla, Daniele Alfredo
• Granted Patent: US 7,491,620 B2
• Time in Patent Office: Days
• US Class Current: 438/401
• CPC Class Codes: H01L 2223/5442 comprising non digital, non alphanumeric information, e.g. symbols
• CPC Class Codes: H01L 2223/54433 containing identification or tracking information
• CPC Class Codes: H01L 2223/54466 Located in a dummy or reference die
• CPC Class Codes: H01L 2223/54473 for use after dicing
• CPC Class Codes: H01L 2223/5448 Located on chip prior to dicing and remaining on chip after dicing
• CPC Class Codes: H01L 23/544 Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps test patterns for characterising or monitoring manufacturing processes H01L22/00
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method of indexing a plurality of dice obtained from a material wafer comprising a plurality of stacked material layers, each die being obtained in a respective die position in the wafer, the method including providing a visible index on each die indicative of the respective die position, wherein providing the visible index on each die includes: forming in a first material layer of the die a reference structure adapted to defining a mapping of the wafer; and forming in a second material layer of the die a marker associated with the reference structure, a position of the marker with respect to the reference structure being adapted to provide an indication of the die position in the wafer.

Claims

1. A method of indexing a plurality of dice obtained from a material wafer comprising a plurality of stacked material layers, each die being obtained in a respective die position in the wafer, the method including providing a visible index on each die indicative of the respective die position,

wherein

providing the visible index on each die includes:

forming in a first material layer of the die a reference structure adapted to defining a mapping of the wafer; and

forming in a second material layer of the die a marker associated with the reference structure, a position of the marker with respect to the reference structure being adapted to provide an indication of the die position in the wafer.

2. The method of indexing according to claim 1, wherein said reference structure identifies a two-coordinate system, and wherein said position of the marker identifies a respective pair of coordinates in the two-coordinates system.

3. The method of indexing according to claim 1, wherein said plurality of dice includes at least two subsets of dice obtained from respective portions of the material wafer, and wherein said visible index includes a first visible index element and a second visible index element, the first visible index element being adapted to define a position of the die in the respective portion of the wafer, and the second visible index element defining a respective position of the portion of the wafer on said wafer.

4. The method according to claim 1, wherein the first material layer of the die coincides with the second material layer of the die and particularly includes one among a metal layer, a polysilicon layer, and a passivation layer.

5. A process for fabricating a plurality of dice from a material wafer comprising a plurality of stacked material layers, the process being performed in at least one stage by exploiting at least one photolithographic mask for treating a surface of the material wafer through an exposition to a suitable radiation, each die being obtained in a respective die position in the wafer, the process including forming a visible index on each die indicative of the respective die position,

wherein

said forming the visible index is accomplished according to the method according to claim 1.

6. The process according to claim 5, wherein the at least one stage comprises at least two steps for treating a respective superficial portion of the material wafer corresponding to a respective subset of said plurality of dice by said at least one photolithographic mask through the exposition to the suitable radiation in temporal succession.

7. The process according to claim 6, wherein said at least one mask comprises a first mask and a second mask, and wherein said reference structure is formed by the first photolithographic mask moved into respective first positions on the wafer, and wherein said marker is formed by the second photolithographic mask moved into respective second positions on the wafer suitably offset with respect to the first positions of an amount depending on the at least two steps.

8. The process according to claim 5, wherein forming in said first material layer of the die the reference structure includes selectively removing a portion of the first material layer.

9. The process according to claim 5, wherein forming in said second material layer of the die the marker includes selectively removing a portion of the second material layer.

10. The process according to claim 7, wherein the first mask and the second mask are exploited during a same stage for patterning a same material layer.

11-23. -23. (canceled)

24. A method, comprising:

aligning a first mask with a first region of a wafer having multiple regions that each include a respective die such that the first mask has a first alignment offset relative to the first region;

defining with the first mask in the die within the first region a first marker that identifies the first region;

aligning the first mask with a second region of the wafer such that the first mask has a second alignment offset relative to the second region, the second offset different from the first offset; and

defining with the first mask in the die within the second region a second marker that identifies the second region.

25. The method of claim 24 wherein the first alignment offset comprises a zero offset.

26. The method of claim 24 wherein the second marker has a relative offset from the first marker, the relative offset equal to a difference between the first and second alignment offsets.

27. A method, comprising:

aligning a first mask with a first region of a wafer having multiple regions that each include a respective die;

defining with the first mask in the die within the first region a first reference;

aligning a second mask with the first region such that the second mask has a first alignment offset relative to the first region;

defining with the second mask in the die within the first region a first marker having a location relative to the first reference, the location of the first marker corresponding to the first region;

aligning the first mask with a second region of the wafer;

defining with the first mask in the die within the second region the first reference;

aligning the second mask with the second region such that the second mask has a second alignment offset relative to the second region; and

defining with the second mask in the die within the second region a second marker having a location relative to the first reference, the location of the second marker corresponding to the second region.