Apparatus and method for rinsing and drying silicon wafers

• US 4,722,752 A
• Filed: 06/16/1986
• Issued: 02/02/1988
• Est. Priority Date: 06/16/1986
• Status: Expired due to Fees

• Current Assignee: Trebor International Limited (Mondelez International, Inc.)
• Original Assignee: Robert F. Orr
• Inventors: Steck, Ricky B.
• Primary Examiner(s): Hornsby, Harvey C.
• Application Number:
  US06/874,383
• Time in Patent Office: 596 Days
• Field of Search: 134/25.1, 134/25.4, 134/30, 134/135, 134/137, 134/140, 134/142, 134/154, 134/155
• US Class Current: 134/25.4
• CPC Class Codes: H01L 21/67028 for cleaning followed by drying, rinsing, stripping, blasting or the like
• CPC Class Codes: Y10S 134/902 Semiconductor wafer

Abstract

Apparatus and method for rinsing and drying thin wafers such as silicon wafers or other disc-like substrates or elements wherein the wafers are rinsed in a hot water bath while supported in a conventional slotted carrier. The wafers are dried by slowly, raising the wafers out of the water bath such that the water surface tension at the surface of the water bath evenly and effectively draws off water from the rising surfaces of the wafers. A novel lift mechanism is provided for slowly and independently lifting the wafers and the cassette in which the wafers were supported during rinsing through the surface of the water such that there is no contact between the wafers and the cassette or between the wafers and any other object or between the cassette and any other object at the point where the cassette and wafers move through the surface of the water.

Claims

1. Apparatus for rinsing and drying of wafers which are contained within a slotted carrier in edgewise, parallel, coaxial arrangement with said slotted carrier having an opening in the bottom thereof and an essentially open top, said apparatus comprising

a tank filled with high purity, hot, deionized water;

a diffuser;

means for introducing high purity, hot, deionized water into the tank through said diffuser to create laminar flow of hot, deionized water upwardly through said tank;

a peripheral overflow which allows hot, deionized water to drain around the periphery of said tank;

support means within said tank for supporting at least one of said slotted carriers and a mutually respective batch of wafers such that each such slotted carrier and batch of wafers carried therein are completely submerged beneath the surface of the deionized water in said tank;

lift means within said tank for lifting the respective batches of wafers from said slotted carriers, said lift means comprising a number of lift elements corresponding to the number of slotted carriers which can be supported on said support means, said lift elements being movable from a lowered position beneath a mutually respective slotted carrier supported on said support means through the opening in the bottom of said respective slotted carrier to an elevated position adjacent to the top of said respective slotted carrier;

means on said lift elements for engaging the bottom edges of the wafers in a mutually respective slotted carrier and lifting the wafers upwardly out of said respective slotted carrier as said lift elements move from their lowered position to their elevated position;

means for moving said support means upwardly in a first movement to a position where the upper edges of said slotted carriers are positioned immediately beneath and adjacent to the surface of the hot, deionized water in said tank;

means for moving said lift elements of said lift means upwardly in a second movement following the completion of said first movement of said support means, with said lift means engaging and lifting the wafers out of the respective slotted carriers and partially through the surface of the hot, deionized water in said tank to a position at the end of said second movement wherein the bottom edges of said wafers which are engaged by said lift means remain submerged with said lift means beneath the surface of the hot deionized water in said tank;

means for moving said support means upwardly in a third movement following the completion of said second movement of said lift elements, wherein the slotted carrier reengages said wafers at positions along the side edges of said wafers which are above the surface of the hot, deionized water in said tank, with the slotted carrier then supporting and lifting said wafers completely out of the hot, deionized water in said tank.

2. Apparatus in accordance with claim 1, wherein there are further provided

means for moving said support means and said lift elements in a fourth combined movement downwardly beneath the surface of the hot, deionized water to a position in which the slotted carriers and batches of wafers supported on said support means are submerged beneath the surface of the hot, deionized water in said tank;

and

means for repeating said first, second and third movements.

3. Apparatus in accordance with claim 1, wherein

the means for moving said support means in the first and third movements comprises a hydraulic piston coupled to said support means and controlled to produce the first and third movements;

and

the means for moving said lift elements in the second movement comprises a second hydraulic piston coupled to said lift elements and controlled to produce the second movement.

4. A method of rinsing and drying wafers comprising the steps of:

(a) placing the wafers to be rinsed and dried in a slotted carrier wherein the wafers are supported edgewise along the opposite sides of said slotted carrier in spaced, parallel, coaxial relation;

(b) submerging said slotted carrier and the wafers which are to be rinsed and dried beneath the surface of hot, deionized water in a tank;

(c) introducing hot, deionized water into said tank through a diffuser to create a laminar flow of hot, deionized water upwardly through said tank and about said wafers and slotted carrier which are submerged in the hot, deionized water;

(d) maintaining the wafers and slotted carrier submerged in said tank for a time sufficient to rinse said wafers;

(e) slowly raising the slotted carrier containing the rinsed wafers in a first movement to a position in which the upper edges of the slotted carrier are positioned immediately beneath and adjacent to the surface of the hot, deionized water in said tank;

(f) following the completion of said first movement in step (3), slowly raising a lift element upwardly in a second movement through the opening in the bottom of said slotted carrier to engage the bottom edges of said wafers and to slowly lift the wafers out of the slotted carrier and partially through the surface of the hot, deionized water in said tank to a position in which the bottom edges of said wafers which are engaged by said lift means remain submerged with said lift means beneath the surface of the hot, deionized water in said tank; and

(g) following the completion of said second movement in step (f), slowly raising the slotted carrier upwardly in a third movement, such that the slotted carrier reengages said wafers at positions along the side edges of said wafers which are above the surface of the hot, deionized water, with the slotted carrier then supporting and lifting said wafers completely out of said hot, deionized water in said tank,

wherein the movement of said slotted carrier and said lift element is sufficiently slow that the deionized water is drawn from the wafers and the slotted carrier by water surface tension as the wafers and slotted carrier move across the interface with the surface of the deionized water.