Electron beam drawing method

Claim 2

An electron beam drawing method whereby a surface of a semiconductor wafer is divided into a number of blocks, each block is divided into a plurality of chips, four matching marks (2, 3, 4, 5) are formed in each of the blocks, a correction is made to an electron beam deflecting system on the basis of position information of detected matching marks (7, 8, 9, 10), and the blocks are then drawn, wherein the correction is performed on the basis of different correcting equations in correspondence to the number of said matching marks detected.

Claim 3

A method according to claim 1, wherein when the number of said matching marks detected is four, eight correction coefficients are determined by a method of least squares on the basis of the coordinates of said four matching marks detected and thereafter, the correction is performed by using the following correcting equations: ΔX = AX + BY + CXY + D ΔY = AʹX + BʹY + CʹXY + Dʹ where, X and Y denote coordinates from the center of the block, ΔX and ΔY indicate correction amounts, and A, B, C, D, Aʹ, Bʹ, Cʹ, and Dʹ represent correction coefficients and have the following meanings. A : gain term in the X direction, B : rotational term regarding a Y axis, C : trapezoid term which is symmetrical with respect to the Y axis, D : shift term in the X direction, Aʹ: rotational term regarding an X axis, Bʹ: gain term in the Y direction, Cʹ: trapezoid term which is symmetrical with respect to the X axis, Dʹ shift term in the Y direction.

Claim 4

A method according to claim 1, wherein when the number of said matching marks detected is three, six correction coefficients are determined by a method of least squares on the basis of the coordinates of said three matching marks detected and thereafter, the correc­tion is executed by using the following correcting equations: ΔX = AX + BY + D ΔY = AʹX + BʹY + Dʹ where, X and Y denote coordinates from the center of the block, ΔX and ΔY indicate correction amounts, and A, B, D, Aʹ, Bʹ, and Dʹ represent correction coefficients and have the following meanings. A : gain term in the X direction, B : rotational term regarding a Y axis, D : shift term in the X direction, Aʹ: rotational term regarding an X axis, Bʹ: gain term in the Y direction, Dʹ: shift term in the Y direction.

Claim 5

A method according to claim 1, wherein when the number of said matching marks detected is two, four correction coefficients are determined by a method of least squares on the basis of the coordinates of said two detected matching marks and thereafter, the correction is performed by using the following correcting equations: ΔX = AX + BY + D ΔY = -BX + AY + Dʹ where, X and Y denote coordinates from the center of the block, ΔX and ΔY indicate correction amounts, and A, B, and D represent correction coefficients and have the following meanings. A : gain term in the X direction, B : rotational term regarding a Y axis, D : shift term in the X direction, Dʹ: shift term in the Y direction.

Claim 6

A method according to claim 1, wherein when the number of said matching marks detected is one, two correc­tion coefficients D and Dʹ are determined on the basis of the coordinates of said one detected matching mark by using the following correcting equations and thereafter, the correction is performed using *A, *B, *C, *Aʹ, *Bʹ, and *Cʹ of the preceding block: ΔX = *AX + *BY + *CXY + D ΔY = *AʹX + *BʹY + *CʹXY + Dʹ where, X and Y denote coordinates from the center of the block, aX and aY indicate correction amounts, and *A, *B, *C, D, *Aʹ, *Bʹ, *Cʹ, and Dʹ represent correction coeffi­cients and have the following meanings. *A : gain term in an X direction, *B : rotational term regarding a Y axis, *C : trapezoid term which is symmetrical with respect to the Y axis, D : shift term in the X direction, *Aʹ: rotational term regarding an X axis, *Bʹ: gain term in a Y direction, *Cʹ: trapezoid term which is symmetrical with respect to the X axis, Dʹ : shift term in the Y direction.